Science.gov

Sample records for barrier energy difference

  1. Fusion of Si28+Si28,30: Different trends at sub-barrier energies

    NASA Astrophysics Data System (ADS)

    Montagnoli, G.; Stefanini, A. M.; Esbensen, H.; Jiang, C. L.; Corradi, L.; Courtin, S.; Fioretto, E.; Grebosz, J.; Haas, F.; Jia, H. M.; Mazzocco, M.; Michelagnoli, C.; Mijatović, T.; Montanari, D.; Parascandolo, C.; Scarlassara, F.; Strano, E.; Szilner, S.; Torresi, D.

    2014-10-01

    Background: The fusion excitation function of the system Si28+Si28 at energies near and below the Coulomb barrier is known only down to ≃15 mb. This precludes any information on both coupling effects on sub-barrier cross sections and the possible appearance of hindrance. For Si28+Si30 even if the fusion cross section is measured down to ≃50 μb, the evidence of hindrance is marginal. Both systems have positive fusion Q values. While Si28 has a deformed oblate shape, Si30 is spherical. Purpose: We investigate 1. the possible influence of the different structure of the two Si isotopes on the fusion excitation functions in the deep sub-barrier region and 2. whether hindrance exists in the Si+Si systems and whether it is strong enough to generate an S-factor maximum, thus allowing a comparison with lighter heavy-ion systems of astrophysical interest. Methods: Si28 beams from the XTU Tandem accelerator of the INFN Laboratori Nazionali di Legnaro were used. The setup was based on an electrostatic beam separator, and fusion evaporation residues (ER) were detected at very forward angles. Angular distributions of ER were measured. Results: Fusion cross sections of Si28+Si28 have been obtained down to ≃600 nb. The slope of the excitation function has a clear irregularity below the barrier, but no indication of a S-factor maximum is found. For Si28+Si30 the previous data have been confirmed and two smaller cross sections have been measured down to ≃4 μb. The trend of the S-factor reinforces the previous weak evidence of hindrance. Conclusions: The sub-barrier cross sections for Si28+Si28 are overestimated by coupled-channels calculations based on a standard Woods-Saxon potential, except for the lowest energies. Calculations using the M3Y+repulsion potential are adjusted to fit the Si28+Si28 and the existing Si30+Si30 data. An additional weak imaginary potential (probably simulating the effect of the oblate Si28 deformation) is required to fit the low-energy trend of

  2. Specific Barriers and Drivers in Different Stages of Decision-Making about Energy Efficiency Upgrades in Private Homes.

    PubMed

    Klöckner, Christian A; Nayum, Alim

    2016-01-01

    Energy efficiency upgrades of privately owned homes like adding to the insulation layers in the walls, roof or floor, or replacing windows with more efficiently insulated versions can contribute significantly to reducing the energy impact of the building sector and thus also the CO2 footprint of a household. However, even in countries like Norway that have a rather high rate of renovation, energy upgrades are not always integrated into such a refurbishment project. This study tests which structural and internal psychological barriers hinder and which drivers foster decision-making to implement such measures, once a renovation project is planned. With a theoretical background in stage-based models of decision-making 24 barriers and drivers were tested for their specific effect in the stages of decision-making. The four stages of decision-making assumed in this study were (1) "not being in a decision mode," (2) "deciding what to do," (3) "deciding how to do it," and (4) "planning implementation." Based on an online survey of 3787 Norwegian households, it was found that the most important barriers toward deciding to implement energy efficiency upgrades were not owning the dwelling and feeling the right time had not come yet. The most important drivers of starting to decide were higher expected comfort levels, better expected living conditions, and an expected reduction of energy costs. For the transition from deciding what to do to how to do it, not managing to make a decision and feeling the right point in time has not come yet were the strongest barriers, easily accessible information and an expected reduction of energy costs were the most important drivers. The final transition from deciding how to do the upgrades to planning implementation was driven by expecting a payoff within a reasonable time frame and higher expected comfort levels; the most important barriers were time demands for supervising contractors and-again-a feeling that the right point in time has

  3. Specific Barriers and Drivers in Different Stages of Decision-Making about Energy Efficiency Upgrades in Private Homes

    PubMed Central

    Klöckner, Christian A.; Nayum, Alim

    2016-01-01

    Energy efficiency upgrades of privately owned homes like adding to the insulation layers in the walls, roof or floor, or replacing windows with more efficiently insulated versions can contribute significantly to reducing the energy impact of the building sector and thus also the CO2 footprint of a household. However, even in countries like Norway that have a rather high rate of renovation, energy upgrades are not always integrated into such a refurbishment project. This study tests which structural and internal psychological barriers hinder and which drivers foster decision-making to implement such measures, once a renovation project is planned. With a theoretical background in stage-based models of decision-making 24 barriers and drivers were tested for their specific effect in the stages of decision-making. The four stages of decision-making assumed in this study were (1) “not being in a decision mode,” (2) “deciding what to do,” (3) “deciding how to do it,” and (4) “planning implementation.” Based on an online survey of 3787 Norwegian households, it was found that the most important barriers toward deciding to implement energy efficiency upgrades were not owning the dwelling and feeling the right time had not come yet. The most important drivers of starting to decide were higher expected comfort levels, better expected living conditions, and an expected reduction of energy costs. For the transition from deciding what to do to how to do it, not managing to make a decision and feeling the right point in time has not come yet were the strongest barriers, easily accessible information and an expected reduction of energy costs were the most important drivers. The final transition from deciding how to do the upgrades to planning implementation was driven by expecting a payoff within a reasonable time frame and higher expected comfort levels; the most important barriers were time demands for supervising contractors and—again—a feeling that the right

  4. Barriers to improvements in energy efficiency

    SciTech Connect

    Reddy, A.K.N.

    1991-10-01

    To promote energy-efficiency improvements, actions may be required at one or more levels -- from the lowest level of the consumer (residential, commercial, industrial, etc.) through the highest level of the global agencies. But barriers to the implementation of energy-efficiency improvements exist or can arise at all these levels. Taking up each one of these barriers in turn, the paper discusses specific measures that can contribute to overcoming the barriers. However, a one-barrier-one-measure approach must be avoided. Single barriers may in fact involve several sub-barriers. Also, combinations of measures are much more effective in overcoming barriers. In particular, combinations of measures that simultaneously overcome several barriers are most successful. The paper discusses the typology of barriers, explores their origin and suggests measures that by themselves or in combination with other measures, will overcome these barriers. Since most of the barriers dealt with can be found in the ``barriers`` literature, any originality in the paper lies in its systematic organization, synoptic view and holistic treatment of this issue. This paper is intended to initiate a comprehensive treatment of barriers, their origins and the measures that contribute to overcoming them. Hopefully, such a treatment will facilitate the implementation of energy-efficiency improvements involving a wide diversity of ever-changing energy end uses and consumer preferences.

  5. Barriers to improvements in energy efficiency

    SciTech Connect

    Reddy, A.K.N.

    1991-10-01

    To promote energy-efficiency improvements, actions may be required at one or more levels -- from the lowest level of the consumer (residential, commercial, industrial, etc.) through the highest level of the global agencies. But barriers to the implementation of energy-efficiency improvements exist or can arise at all these levels. Taking up each one of these barriers in turn, the paper discusses specific measures that can contribute to overcoming the barriers. However, a one-barrier-one-measure approach must be avoided. Single barriers may in fact involve several sub-barriers. Also, combinations of measures are much more effective in overcoming barriers. In particular, combinations of measures that simultaneously overcome several barriers are most successful. The paper discusses the typology of barriers, explores their origin and suggests measures that by themselves or in combination with other measures, will overcome these barriers. Since most of the barriers dealt with can be found in the barriers'' literature, any originality in the paper lies in its systematic organization, synoptic view and holistic treatment of this issue. This paper is intended to initiate a comprehensive treatment of barriers, their origins and the measures that contribute to overcoming them. Hopefully, such a treatment will facilitate the implementation of energy-efficiency improvements involving a wide diversity of ever-changing energy end uses and consumer preferences.

  6. Market and Policy Barriers to Energy Storage Deployment

    SciTech Connect

    Bhatnagar, Dhruv; Currier, Aileen; Hernandez, Jacquelynne; Ma, Ookie; Kirby, Brendan

    2013-09-01

    Electric energy storage technologies can provide numerous grid services; there are a number of factors that restrict their current deployment. The most significant barrier to deployment is high capital costs, though several recent deployments indicate that capital costs are decreasing and energy storage may be the preferred economic alternative in certain situations. However, a number of other market and regulatory barriers persist, limiting further deployment. These barriers can be categorized into regulatory barriers, market (economic) barriers, utility and developer business model barriers, cross-cutting barriers and technology barriers.

  7. Directed transport of active particles over asymmetric energy barriers.

    PubMed

    Koumakis, N; Maggi, C; Di Leonardo, R

    2014-08-21

    We theoretically and numerically investigate the transport of active colloids to target regions, delimited by asymmetric energy barriers. We show that it is possible to introduce a generalized effective temperature that is related to the local variance of particle velocities. The stationary probability distributions can be derived from a simple diffusion equation in the presence of an inhomogeneous effective temperature resulting from the action of external force fields. In particular, transition rates over asymmetric energy barriers can be unbalanced by having different effective temperatures over the two slopes of the barrier. By varying the type of active noise, we find that equal values of diffusivity and persistence time may produce strongly varied effective temperatures and thus stationary distributions.

  8. Developing effective rockfall protection barriers for low energy impacts

    NASA Astrophysics Data System (ADS)

    Mentani, Alessio; Giacomini, Anna; Buzzi, Olivier; Govoni, Laura; Gottardi, Guido; Fityus, Stephen

    2016-04-01

    Recently, important progresses have been made towards the development of high capacity rockfall barriers (100 kJ - 8000 kJ). The interest of researchers and practitioners is now turning to the development of fences of minor capacity, whose use becomes essential in areas where rockfall events generally have low intensity and the use of high capacity barriers would be accompanied by excessive costs and high environmental impact. Low energy barriers can also provide a cost-effective solution even in areas where high energies events are expected. Results of full-scale tests are vital to any investigation on the behaviour of these structures. An experimental set-up has been developed at The University of Newcastle (AUS), to investigate the response of low energy rockfall barrier prototypes to low energy impacts. The Australian territory, and in particular New South Wales, is in fact characterised by rockfall events of low-to-medium intensity (50 kJ - 500 kJ) and the need of protection structures working within such energy range, is particularly felt [1]. The experiments involved the impact of a test block onto three spans, low energy barrier prototypes, made of steel structural posts, fully fixed at the base, side cables and a steel meshwork constituted by a double twist hexagonal wire net [2]. Test data enabled the development, calibration and assessment of FE models [3], on which non-linear and dynamic analyses have been performed addressing the effect of the block size. Results have shown that the response of the structure is strongly governed by the net. Data from tests conducted on the sole net and on the entire barrier showed in fact a similar trend, different to what typically observed for high capacity barriers, whose behaviour is also led by the presence of uphill cables and brakes. In particular, the numerical analyses have demonstrated a dependence of the net performance on the block size. In particular, a loss of capacity in the order of 50% occurred as the

  9. Free energy barriers to evaporation of water in hydrophobic confinement.

    PubMed

    Sharma, Sumit; Debenedetti, Pablo G

    2012-11-08

    We use umbrella sampling Monte Carlo and forward and reverse forward flux sampling (FFS) simulation techniques to compute the free energy barriers to evaporation of water confined between two hydrophobic surfaces separated by nanoscopic gaps, as a function of the gap width, at 1 bar and 298 K. The evaporation mechanism for small (1 × 1 nm(2)) surfaces is found to be fundamentally different from that for large (3 × 3 nm(2)) surfaces. In the latter case, the evaporation proceeds via the formation of a gap-spanning tubular cavity. The 1 × 1 nm(2) surfaces, in contrast, are too small to accommodate a stable vapor cavity. Accordingly, the associated free energy barriers correspond to the formation of a critical-sized cavity for sufficiently large confining surfaces, and to complete emptying of the gap region for small confining surfaces. The free energy barriers to evaporation were found to be of O(20kT) for 14 Å gaps, and to increase by approximately ~5kT with every 1 Å increase in the gap width. The entropy contribution to the free energy of evaporation was found to be independent of the gap width.

  10. Barriers to Industrial Energy Efficiency - Study (Appendix A), June 2015

    SciTech Connect

    2015-06-01

    This study examines barriers that impede the adoption of energy efficient technologies and practices in the industrial sector, and identifies successful examples and opportunities to overcome these barriers. Three groups of energy efficiency technologies and measures were examined: industrial end-use energy efficiency, industrial demand response, and industrial combined heat and power. This study also includes the estimated economic benefits from hypothetical Federal energy efficiency matching grants, as directed by the Act.

  11. Barriers to Industrial Energy Efficiency - Report to Congress, June 2015

    SciTech Connect

    2015-06-01

    This report examines barriers that impede the adoption of energy efficient technologies and practices in the industrial sector, and identifies successful examples and opportunities to overcome these barriers. Three groups of energy efficiency technologies and measures were examined: industrial end-use energy efficiency, industrial demand response, and industrial combined heat and power. This report also includes the estimated economic benefits from hypothetical Federal energy efficiency matching grants, as directed by the Act.

  12. Parametric modeling of energy filtering by energy barriers in thermoelectric nanocomposites

    SciTech Connect

    Zianni, Xanthippi E-mail: xzianni@gmail.com; Narducci, Dario

    2015-01-21

    We present a parametric modeling of the thermoelectric transport coefficients based on a model previously used to interpret experimental measurements on the conductivity, σ, and Seebeck coefficient, S, in highly Boron-doped polycrystalline Si, where a very significant thermoelectric power factor (TPF) enhancement was observed. We have derived analytical formalism for the transport coefficients in the presence of an energy barrier assuming thermionic emission over the barrier for (i) non-degenerate and (ii) degenerate one-band semiconductor. Simple generic parametric equations are found that are in agreement with the exact Boltzmann transport formalism in a wide range of parameters. Moreover, we explore the effect of energy barriers in 1-d composite semiconductors in the presence of two phases: (a) the bulk-like phase and (b) the barrier phase. It is pointed out that significant TPF enhancement can be achieved in the composite structure of two phases with different thermal conductivities. The TPF enhancement is estimated as a function of temperature, the Fermi energy position, the type of scattering, and the barrier height. The derived modeling provides guidance for experiments and device design.

  13. Summary of Workshop: Barriers to Energy Efficient Residential Ventilation

    SciTech Connect

    Sherman, Max; Sherman, Max

    2008-01-10

    The objectives for this workshop were to bring together those with different viewpoints on the implementation of energy efficient ventilation in homes to share their perspectives. The primary benefit of the workshop is to allow the participants to get a broader understanding of the issues involved and thereby make themselves more able to achieve their own goals in this area. In order to achieve this objective each participant was asked to address four objectives from their point of view: (1) Drivers for energy efficient residential ventilation: Why is this an important issue? Who cares about it? Where is the demand: occupants, utilities, regulation, programs, etc? What does sustainability mean in this context? (2) Markets & Technologies: What products, services and systems are out there? What kinds of things are in the pipeline? What is being installed now? Are there regional or other trends? What are the technology interactions with other equipment and the envelope? (3) Barriers to Implementation: What is stopping decision makers from implementing energy-efficient residential ventilation systems? What kind of barriers are there: technological, cost, informational, structural, etc. What is the critical path? (4) Solutions: What can be done to overcome the barriers and how can/should we do it? What is the role of public vs. private institutions? Where can investments be made to save energy while improving the indoor environment? Ten participants prepared presentations for the workshop. Those presentations are included in sections at the end of this workshop report. These presentations provided the principal context for the discussions that happened during the workshop. Critical path issues were raised and potential solutions discussed during the workshop. As a secondary objective they have listed key issues and some potential consensus items which resulted from the discussions.

  14. Market and policy barriers to energy storage deployment :

    SciTech Connect

    Bhatnagar, Dhruv; Currier, Aileen B.; Hernandez, Jacquelynne; Ma, Ookie; Kirby, Brendan

    2013-09-01

    Electric energy storage technologies have recently been in the spotlight, discussed as essential grid assets that can provide services to increase the reliability and resiliency of the grid, including furthering the integration of variable renewable energy resources. Though they can provide numerous grid services, there are a number of factors that restrict their current deployment. The most significant barrier to deployment is high capital costs, though several recent deployments indicate that capital costs are decreasing and energy storage may be the preferred economic alternative in certain situations. However, a number of other market and regulatory barriers persist, limiting further deployment. These barriers can be categorized into regulatory barriers, market (economic) barriers, utility and developer business model barriers, crosscutting barriers and technology barriers. This report, through interviews with stakeholders and review of regulatory filings in four regions roughly representative of the United States, identifies the key barriers restricting further energy storage development in the country. The report also includes a discussion of possible solutions to address these barriers and a review of initiatives around the country at the federal, regional and state levels that are addressing some of these issues. Energy storage could have a key role to play in the future grid, but market and regulatory issues have to be addressed to allow storage resources open market access and compensation for the services they are capable of providing. Progress has been made in this effort, but much remains to be done and will require continued engagement from regulators, policy makers, market operators, utilities, developers and manufacturers.

  15. Energy barriers and cell migration in confluent tissues

    NASA Astrophysics Data System (ADS)

    Bi, Dapeng; Lopez, J. H.; Schwarz, J. M.; Manning, M. Lisa

    2014-03-01

    Biological processes such as embryogensis, tumorigenesis and wound healing require cells to move within a tissue. While the migration of single cells has been extensively studied, it has remained unclear how single cell properties control migration through a confluent tissue. We develop numerical and theoretical models to calculate energy barriers to cell rearrangements, which govern cell motility. In contrast to sheared foams where energy barriers are power-law distributed, energy barriers in tissues are exponentially distributed and depend systematically on the cell's number of neighbors. Using simple extensions of `trap' and `Soft Glassy Rheology' models, we demonstrate that these energy barrier distributions give rise to glassy behavior and use the models to make testable predictions for two-time correlation functions and caging times. We incorporate these ideas into a continuum model that combines glassy rheology with active polarization to better understand collective migration in epithelial sheets.

  16. Radiant Barriers Save Energy in Buildings

    NASA Technical Reports Server (NTRS)

    2014-01-01

    Langley Research Center needed to coat the Echo 1 satellite with a fine mist of vaporized metal, and collaborated with industry to create "radiant barrier technology." In 2010, Ryan Garrett learned about a new version of the technology resistant to oxidation and founded RadiaSource in Ogden, Utah, to provide the NASA-derived technology for applications in homes, warehouses, gymnasiums, and agricultural settings.

  17. Blood-brain barrier and energy balance.

    PubMed

    Banks, William A

    2006-08-01

    The blood-brain barrier (BBB) plays a critical role in the transduction of signals between the central nervous system and peripheral tissues. It does so through several mechanisms, including the direct transport of peptides and regulatory proteins such as insulin and leptin. Another mechanism that may be important is the secretion by brain endothelial cells of substances that affect feeding, such as proinflammatory cytokines and NO. We have recently shown that the BBB is capable of receiving an input from one side and secreting a substance into the other. Additionally, BBB secretions can be modulated by substances that affect feeding, such as adiponectin and lipopolysaccharide.

  18. Renewable Energy Permitting Barriers in Hawaii: Experience from the Field

    SciTech Connect

    Busche, S.; Donnelly, C.; Atkins, D.; Fields, R.; Black, C.

    2013-03-01

    This white paper presents a summary of the solicited input from permitting agencies and renewable energy developers on the permitting process in Hawaii to provide stakeholders in Hawaii, particularly those involved in permitting, with information on current permitting barriers that renewable energy developers are experiencing.

  19. Renewable energy technologies adoption in Kazakhstan: potentials, barriers and solutions

    NASA Astrophysics Data System (ADS)

    Karatayev, Marat; Marazza, Diego; Contin, Andrea

    2015-04-01

    The growth in environmental pollution alongside an increasing demand for electricity in Kazakhstan calls for a higher level of renewable energy penetration into national power systems. Kazakhstan has great potential for renewable energies from wind, solar, hydro and biomass resources that can be exploited for electricity production. In 2013, the Kazakhstani Ministry of Energy initiated a new power development plan, which aims to bring the share of renewable energy to 3% by 2020 rising to 30% by 2030 and 50% by 2050. The current contribution of renewable energy resources in the national electricity mix, however, is less than 1%. As a developing country, Kazakhstan has faced a number of barriers to increase renewable energy use, which have to be analysed and translated into a comprehensive renewable energy policy framework. This study presents an overview of the current conditions of renewable energy development in Kazakhstan. Secondly, it identifies and describes the main barriers that prevent diffusion of renewable energy technologies in Kazakhstan. Finally, the paper provides solutions to overcome specific barriers in order to successfully develop a renewable energy technology sector in Kazakhstan.

  20. Energy deposition characteristics of nanosecond dielectric barrier discharge plasma actuators: Influence of dielectric material

    NASA Astrophysics Data System (ADS)

    Correale, G.; Winkel, R.; Kotsonis, M.

    2015-08-01

    An experimental study aimed at the characterization of energy deposition of nanosecond Dielectric Barrier Discharge (ns-DBD) plasma actuators was carried out. Special attention was given on the effect of the thickness and material used for dielectric barrier. The selected materials for this study were polyimide film (Kapton), polyamide based nylon (PA2200), and silicone rubber. Schlieren measurements were carried out in quiescent air conditions in order to observe density gradients induced by energy deposited. Size of heated area was used to qualify the energy deposition coupled with electrical power measurements performed using the back-current shunt technique. Additionally, light intensity measurements showed a different nature of discharge based upon the material used for barrier, for a fixed thickness and frequency of discharge. Finally, a characterisation study was performed for the three tested materials. Dielectric constant, volume resistivity, and thermal conductivity were measured. Strong trends between the control parameters and the energy deposited into the fluid during the discharge were observed. Results indicate that efficiency of energy deposition mechanism relative to the thickness of the barrier strongly depends upon the material used for the dielectric barrier itself. In general, a high dielectric strength and a low volumetric resistivity are preferred for a barrier, together with a high heat capacitance and a low thermal conductivity coefficient in order to maximize the efficiency of the thermal energy deposition induced by an ns-DBD plasma actuator.

  1. A classical determination of vibrationally adiabatic barriers and wells of a collinear potential energy surface

    NASA Astrophysics Data System (ADS)

    Pollak, Eli

    1981-05-01

    A necessary and sufficient condition for the existence of a classical vibrationally adiabatic barrier or well in collinear systems is the existence of periodic orbit dividing surfaces. Knowledge of all pods immediately provides all adiabatic barriers and wells. Furthermore, the classical equation connecting the barriers and wells to the masses and potential energy surface of the system is shown, under mild conditions, to be identical in form to the corresponding quantal equation. The only difference is in the determination of the vibrational state which is obtained by WKB quantization classically. The classical barriers and wells can therefore be used to analyze quantal computations. Such analysis is provided for the hydrogen exchange reaction and the F+HH system. A novel result is the existence of vibrationally adiabatic barriers even where no saddle point exists on the static potential energy surface. These barriers are an outcome of competition between the increase of potential energy and decrease of vibrational force constant along the reaction coordinate. Their existence is therefore of general nature — not limited to the specific structure of a given potential energy surface. The experimental significance of these barriers is discussed. The implications on the use of forward or reverse quasiclassical computations is analyzed. A definite conclusion is that one should not average over initial vibrational action in such calculations.

  2. Implementing District Energy Systems: Municipal Approaches To Overcoming Barriers

    NASA Astrophysics Data System (ADS)

    Simpson, Kevin George

    Climate change and energy security are issues facing municipalities throughout the world. Efficient, resilient, sustainable, community-based energy systems, such as district energy systems (DES), fuelled mostly by renewables, are an important tool for addressing both climate change and energy security at the municipal level. In spite of their benefits, DES are not widely adopted in Canada (CDEA, 2011). This is due to the complex nature of the barriers which project proponents face. This thesis examines the experience of the City of Prince George in adopting and implementing the Downtown DES. Using a case study methodology, data was collected through a review of relevant municipal documents and a series of semi-structured, open-ended interviews. A thematic analysis revealed unexpected barriers related to lack of adequate public consultation and negative perceptions regarding biomass as a fuel for the DES. These `lessons learned' were then developed into recommendations for other municipalities considering DES.

  3. Energy management action plan: Developing a strategy for overcoming institutional barriers to municipal energy conservation

    SciTech Connect

    Not Available

    1992-12-31

    Energy offices working to improve efficiency of local government facilities face not only technical tasks, but institutional barriers, such as budget structures that do not reward efficiency, a low awareness of energy issues, and purchasing procedures based only on minimizing initial cost. The bureau, in working to remove such barriers in San Francisco, has identified 37 institutional barriers in areas such as operations & maintenance, purchasing, and facility design; these barriers were then reorganized into three groupings-- policy & attitudes, budget & incentives, and awareness & information-- and mapped. This map shows that the barriers mutually reinforce each other, and that a holistic approach is required for permanent change. The city`s recreation & parks department was used as a model department, and information about facility energy use was compiled into a departmental energy review. Staff interviews showed how barriers affect conservation. The bureau then generated ideas for projects to remove specific barriers and rated them according to potential impact and the resources required to implement them. Four of the six projects selected focused on maintenance staff: a cost- sharing lighting retrofit program, a boiler efficiency program, a departmental energy tracking system, and a budgetary incentive program for conservation. The other two projects are city-wide: promotion of a new term contract supplying energy-efficient light materials, and publication/distribution of ENERGY NEWS newsletter. A general methodology, the EMAP Strategy Guide, has been created to assist other energy offices in developing EMAPs.

  4. Mesoscale geomorphic change on low energy barrier islands in Chesapeake Bay, U.S.A.

    NASA Astrophysics Data System (ADS)

    Cooper, J. Andrew G.

    2013-10-01

    This paper presents an analysis of decadal (mesoscale) geomorphic change on sandy barrier islands in the fetch-limited environment of Chesapeake Bay. Low energy barrier islands exist in two settings: on the fringe of marshes and in open water and this analysis shows the various types of barrier island to be genetically related. Barrier islands that face the dominant wind and wave direction (E or W) retreat via barrier translation, preserving the barrier island volume. Those that exist in re-entrants are dominated by longshore transport processes, are strongly affected by sediment supply and are subject to disintegration. Marsh fringe barrier islands are perched on or draped over the surface of the underlying marsh. They migrate landwards via barrier translation during periodic high water events accompanied by large waves (hurricanes and northeasters). The underlying marsh surface erodes under all water levels and the rate of retreat of the barrier island and underlying marsh may take place at different rates, leading to various configurations from perched barrier islands several metres landward of the marsh edge, to barrier islands that have a sandy shoreface extending into the subtidal zone. The coastal configuration during landward retreat of marsh fringe barrier islands is subject to strong local control exerted by the underyling marsh topography. As erosion of marsh promontories occurs and marsh creeks are intersected and bypassed, the configuration is subject to rapid change. Periodic sediment influxes cause spits to develop at re-entrants in the marsh. The spits are initiated as extensions of adjacent marsh fringe barrier islands, but as the sediment volume is finite, the initial drift-aligned spits become sediment-starved and begin to develop a series of swash-aligned cells as they strive for morphodynamic equilibrium. The individual cells are stretched until breaches form in the barrier islands, creating inlets with tidal deltas. At this stage the low

  5. Overcoming of energy barrier for irreversible magnetization in nanocomposite magnets

    NASA Astrophysics Data System (ADS)

    Li, Zhu-bai; Zhang, Ying; Shen, Bao-gen; Zhang, Ming; Hu, Feng-xia; Sun, Ji-rong

    2017-01-01

    The irreversible magnetization occurs mainly in hard grains in nanocomposite magnets, and the domain wall involves a little part of defect region in irreversible magnetization due to the self-interaction. The investigation on thermal activation shows that the defect region involved in domain wall becomes narrower due to the TiNb addition in Pr2Fe14B/α-Fe magnets. The defect region augments the energy density in the negative direction of domain wall to overcome the energy barrier of perfect hard region. The soft phase, exchange-coupled with defect region at hard grain outer-layer, promotes magnetization reversal in defect region by exchange coupling. While the defect region plays a role as a ladder to overcome the energy barrier, resulting in the decrease of coecivity more or less depending upon the width and anisotropy of defect region.

  6. Energy Dissipating Devices in Falling Rock Protection Barriers

    NASA Astrophysics Data System (ADS)

    Castanon-Jano, L.; Blanco-Fernandez, E.; Castro-Fresno, D.; Ballester-Muñoz, F.

    2017-03-01

    Rockfall is a phenomenon which, when uncontrolled, may cause extensive material damage and personal injury. One of the structures used to avoid accidents caused by debris flows or rockfalls is flexible barriers. The energy dissipating devices which absorb the energy generated by rock impact and reduce the mechanical stresses in the rest of the elements of the structure are an essential part of these kinds of structures. This document proposes an overview of the performance of energy dissipating devices, as well as of the role that they fulfil in the barrier. Furthermore, a compilation and a description of the dissipating elements found in the literature are proposed. Additionally, an analysis has been performed of the aspects taken into account in the design, such as experimental (quasi-static and dynamic) tests observing the variation of the behaviour curve depending on the test speed and numerical simulations by means of several finite element software packages.

  7. Barriers to household investment in residential energy conservation: preliminary assessment

    SciTech Connect

    Hoffman, W.L.

    1982-12-01

    A general assessment of the range of barriers which impede household investments in weatherization and other energy efficiency improvements for their homes is provided. The relationship of similar factors to households' interest in receiving a free energy audits examined. Rates of return that underly household investments in major conservation improvements are assessed. A special analysis of household knowledge of economically attractive investments is provided that compares high payback improvements specified by the energy audit with the list of needed or desirable conservation improvements identified by respondents. (LEW)

  8. Sign preference in ion-induced nucleation: contributions to the free energy barrier.

    PubMed

    Keasler, Samuel J; Kim, Hyunmi; Chen, Bin

    2012-11-07

    We have performed a series of computer simulations using the AVUS-HR approach to better understand the origin of the sign preference in ion-induced nucleation. In particular, we emphasize the importance of distinguishing between the total formation free energy of a cluster, and the nucleation free energy, which involves only those steps contributing to the free energy barrier. We have separately considered how the ion-water potential energy, the water-water potential energy, and the entropy contribute to both the cluster formation free energy, and the nucleation free energy. These simulations have shown that while the ion-water potential energies make the largest contribution to the formation free energy difference between positive and negative ions, the entropy is the contribution leading to lower nucleation free energy barriers for negative ions. The primary reason for this is the larger stable (but precritical) clusters formed around negative ions. We have further shown that the distinction between formation and nucleation free energies is of particular importance when comparing small cations with larger anions where the formation free energies can be much lower for the cationic clusters, even though the nucleation barriers are lower for the anionic clusters.

  9. Scattering of Halo Nuclei at Energies below and around the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Borge, M. J. G.; Cubero, M.; Fernández-García, J. P.; Moro, A. M.; Pesudo, V.; Acosta, L.; Alcorta, M.; Alvarez, M. A. G.; Bender, P.; Buchmann, L.; Diget, C. A.; Di Pietro, A.; Escrig, D.; Falou, H. A.; Figuera, P. P.; Fulton, B. R.; Fynbo, H. O. U.; Galaviz, D.; Garnsworthy, A.; Gómez-Camacho, J.; Hackman, G.; Kanungo, R.; Lay, J. A.; Madurga, M.; Martel, I.; Mukha, I.; Nilsson, T.; Rodríguez-Gallardo, M.; Rusek, K.; Sánchez-Benítez, A. M.; Rajabali, M.; Sarazin, F.; Shotter, A.; Tengblad, O.; Unsworth, C.; Walden, P.

    The loosely bound structure of halo nuclei is predicted to affect the collisions with heavy targets at energies around the Coulomb barrier. We report here on the results on a series of experiments done at different facilities to study the behaviour of the scattering of the archetype of the halo nuclei: 6He, 11Li, and 11Be on heavy targets at energies below and around the Coulomb barrier. The results are interpreted in the framework of Continuum-Discretized Coupled-Channel calculations (CDCC). The departure from Rutherford scattering is larger than expected. In first approximation the effect certainly scales with the loosely bound character of the projectile.

  10. Pattern formation in dielectric barrier discharges with different dielectric materials

    SciTech Connect

    Dong, L. F.; Fan, W. L.; Wang, S.; Ji, Y. F.; Liu, Z. W.; Chen, Q.

    2011-03-15

    The influence of dielectric material on the bifurcation and spatiotemporal dynamics of the patterns in dielectric barrier discharge in argon/air at atmospheric pressure is studied. It is found that pattern bifurcation sequences are different with different dielectric materials. The spatiotemporal dynamics of the hexagonal pattern in dielectric barrier discharge depends on the dielectric material. The hexagon pattern with glass dielectric is an interleaving of two rectangular sublattices appearing at different moments. The hexagon pattern with quartz dielectric is composed of one set of hexagonal lattice discharging twice in one half cycle of the applied voltage, one is at the rising edge and the other at the falling edge. It results in that the accumulation of wall charges in individual microdischarges in a hexagon pattern with quartz dielectric is greater than that with glass dielectric, which is in agreement with the electron density measurement by Stark broadening of Ar I 696.54 nm.

  11. Wetting transition on patterned surfaces: transition states and energy barriers.

    PubMed

    Ren, Weiqing

    2014-03-18

    We study the wetting transition on microstructured hydrophobic surfaces. We use the string method [J. Chem. Phys. 2007, 126, 164103; J. Chem. Phys. 2013, 138, 134105] to accurately compute the transition states, the energy barriers, and the minimum energy paths for the wetting transition from the Cassie-Baxter state to the Wenzel state. Numerical results are obtained for the wetting of a hydrophobic surface textured with a square lattice of pillars. It is found that the wetting of the solid substrate occurs via infiltration of the liquid in a single groove, followed by lateral propagation of the liquid front. The propagation of the liquid front proceeds in a stepwise manner, and a zipping mechanism is observed during the infiltration of each layer. The minimum energy path for the wetting transition goes through a sequence of intermediate metastable states, whose wetted areas reflect the microstructure of the patterned surface. We also study the dependence of the energy barrier on the drop size and the gap between the pillars.

  12. Universal Pinning Energy Barrier for Driven Domain Walls in Thin Ferromagnetic Films

    NASA Astrophysics Data System (ADS)

    Jeudy, V.; Mougin, A.; Bustingorry, S.; Savero Torres, W.; Gorchon, J.; Kolton, A. B.; Lemaître, A.; Jamet, J.-P.

    2016-07-01

    We report a comparative study of magnetic field driven domain wall motion in thin films made of different magnetic materials for a wide range of field and temperature. The full thermally activated creep motion, observed below the depinning threshold, is shown to be described by a unique universal energy barrier function. Our findings should be relevant for other systems whose dynamics can be modeled by elastic interfaces moving on disordered energy landscapes.

  13. Universal Pinning Energy Barrier for Driven Domain Walls in Thin Ferromagnetic Films.

    PubMed

    Jeudy, V; Mougin, A; Bustingorry, S; Savero Torres, W; Gorchon, J; Kolton, A B; Lemaître, A; Jamet, J-P

    2016-07-29

    We report a comparative study of magnetic field driven domain wall motion in thin films made of different magnetic materials for a wide range of field and temperature. The full thermally activated creep motion, observed below the depinning threshold, is shown to be described by a unique universal energy barrier function. Our findings should be relevant for other systems whose dynamics can be modeled by elastic interfaces moving on disordered energy landscapes.

  14. Breaking the Diffraction Barrier Using Fluorescence Emission Difference Microscopy

    PubMed Central

    Kuang, Cuifang; Li, Shuai; Liu, Wei; Hao, Xiang; Gu, Zhaotai; Wang, Yifan; Ge, Jianhong; Li, Haifeng; Liu, Xu

    2013-01-01

    We propose a novel physical mechanism for breaking the diffraction barrier in the far field. Termed fluorescence emission difference microscopy (FED), our approach is based on the intensity difference between two differently acquired images. When fluorescence saturation is applied, the resolving ability of FED can be further enhanced. A detailed theoretical analysis and a series of simulation tests are performed. The validity of FED in practical use is demonstrated by experiments on fluorescent nanoparticles and biological cells in which a spatial resolution of <λ/4 is achieved. Featuring the potential to realize a high imaging speed, this approach may be widely applied in nanoscale investigations. PMID:23486546

  15. Market barriers to energy efficiency: A critical reappraisal of the rationale for public policies to promote energy efficiency

    SciTech Connect

    Golove, W.H.; Eto, J.H.

    1996-03-01

    This report reviews current perspectives on market barriers to energy efficiency. Ratepayer-funded utility energy-efficiency programs are likely to change in scope, size, and nature as the deregulation process proceeds; the authors research focuses on understanding to what extent some form of future intervention may be warranted and how they might judge the success of particular interventions, especially those funded by ratepayers. They find that challenges to the existence of market barriers have, for the most part, failed to provide a testable alternative explanation for evidence suggesting that there is a substantial ``efficiency gap`` between a consumer`s actual investments in energy efficiency and those that appear to be in the consumer`s own interest. They then suggest that differences of opinion about the appropriateness of public policies stem not from disputes about whether market barriers exist, but from different perceptions of the magnitude of the barriers, and the efficacy and (possibly unintended) consequences of policies designed to overcome them. They conclude that there are compelling justifications for future energy-efficiency policies. Nevertheless, in order to succeed, they must be based on a sound understanding of the market problems they seek to correct and a realistic assessment of their likely efficacy. This understanding can only emerge from detailed investigations of the current operation of individual markets.

  16. Anti-terrorist vehicle crash impact energy absorbing barrier

    DOEpatents

    Swahlan, David J.

    1989-01-01

    An anti-terrorist vehicle crash barrier includes side support structures, crushable energy absorbing aluminum honeycomb modules, and an elongated impact-resistant beam extending between, and at its opposite ends through vertical guideways defined by, the side support structures. An actuating mechanism supports the beam at its opposite ends for movement between a lowered barrier-withdrawn position in which a traffic-supporting side of the beam is aligned with a traffic-bearing surface permitting vehicular traffic between the side support structures and over the beam, and a raised barrier-imposed position in which the beam is aligned with horizontal guideways defined in the side support structures above the traffic-bearing surface, providing an obstruction to vehicular traffic between the side support structures. The beam is movable rearwardly in the horizontal guideways with its opposite ends disposed transversely therethrough upon being impacted at its forward side by an incoming vehicle. The crushable modules are replaceably disposed in the horizontal guideways between aft ends thereof and the beam. The beam, replaceable modules, side support structures and actuating mechanism are separate and detached from one another such that the beam and replaceable modules are capable of coacting to disable and stop an incoming vehicle without causing structural damage to the side support structures and actuating mechanism.

  17. Anti-terrorist vehicle crash impact energy absorbing barrier

    SciTech Connect

    Swahlan, D.J.

    1989-04-18

    An anti-terrorist vehicle crash barrier includes side support structures, crushable energy absorbing aluminum honeycomb modules, and an elongated impact-resistant beam extending between, and at its opposite ends through vertical guideways defined by, the side support structures. An actuating mechanism supports the beam at its opposite ends for movement between a lowered barrier-withdrawn position in which a traffic-supporting side of the beam is aligned with a traffic-bearing surface permitting vehicular traffic between the side support structures and over the beam, and a raised barrier-imposed position in which the beam is aligned with horizontal guideways defined in the side support structures above the traffic-bearing surface, providing an obstruction to vehicular traffic between the side support structures. The beam is movable rearwardly in the horizontal guideways with its opposite ends disposed transversely therethrough upon being impacted at its forward side by an incoming vehicle. The crushable modules are replaceably disposed in the horizontal guideways between aft ends thereof and the beam. The beam, replaceable modules, side support structures and actuating mechanism are separate and detached from one another such that the beam and replaceable modules are capable of coacting to disable and stop an incoming vehicle without causing structural damage to the side support structures and actuating mechanism. 6 figs.

  18. Transition model for ricin-aptamer interactions with multiple pathways and energy barriers

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Xu, Bingqian

    2014-02-01

    We develop a transition model to interpret single-molecule ricin-aptamer interactions with multiple unbinding pathways and energy barriers measured by atomic force microscopy dynamic force spectroscopy. Molecular simulations establish the relationship between binding conformations and the corresponding unbinding pathways. Each unbinding pathway follows a Bell-Evans multiple-barrier model. Markov-type transition matrices are developed to analyze the redistribution of unbinding events among the pathways under different loading rates. Our study provides detailed information about complex behaviors in ricin-aptamer unbinding events.

  19. Multi-neutron transfer reactions at sub-barrier energies.

    SciTech Connect

    Rehm, K. E.

    1998-01-20

    The optimum conditions for multi-neutron transfer have been studied in the system {sup 58}Ni + {sup 124}Sn at bombarding energies at and below the Coulomb barrier. The experiments were performed in inverse kinematics with a {sup 124}Sn beam bombarding a {sup 58}Ni target. The particles were identified with respect to mass and Z in the split-pole spectrograph with a hybrid focal plane detector with mass and Z-resolutions of A/{Delta}A = 150 and Z/{Delta}Z = 70. At all energies the transfer of up to 6 neutrons was observed. The yields for these transfer reactions are found to decrease by about a factor of four for each transferred neutron.

  20. Free energy barrier for dissociation of the guanosine monophosphate anion in water

    NASA Astrophysics Data System (ADS)

    Cornetta, Lucas M.; Coutinho, Kaline; Canuto, Sylvio; Varella, Márcio T. do N.

    2016-08-01

    We report free energy barriers for the ground-state dissociation of the guanosine nucleotide anion in solution, employing implicit and explicit solvation models. The latter was based on the Free Energy Perturbation technique and Monte Carlo simulations. For the lowest-energy structure, both solvation models indicate a solvent-induced transition from a dipole-bound state in the gas phase to a π∗ valence state in solution. The free barrier estimates obtained from explicit and implicit solvation are in fair agreement with each other, although significantly overestimated in comparison to a previously reported explicit solvation model based on ab initio molecular dynamics simulations. Accounting for corrections related to the different DFT functionals used in the present and previous studies significantly improves the agreement. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  1. Lowering energy barriers in surface reactions through concerted reaction mechanisms.

    PubMed

    Sakong, Sung; Mosch, Christian; Lozano, Ariel; Busnengo, H Fabio; Gross, Axel

    2012-10-22

    Any technologically important chemical reaction typically involves a number of different elementary reaction steps consisting of bond-breaking and bond-making processes. Usually, one assumes that such complex chemical reactions occur in a step-wise fashion where one single bond is made or broken at a time. Using first-principles calculations based on density functional theory we show that the barriers of rate-limiting steps for technologically relevant surface reactions are significantly reduced if concerted reaction mechanisms are taken into account.

  2. Probing the fusion of 7Li with 64Ni at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Shaikh, Md. Moin; Roy, Subinit; Rajbanshi, S.; Mukherjee, A.; Pradhan, M. K.; Basu, P.; Nanal, V.; Pal, S.; Shrivastava, A.; Saha, S.; Pillay, R. G.

    2016-04-01

    Background: The stable isotopes of Li, 6Li6 and 7Li, have two-body cluster structures of α +d and α +t with α -separation energies or breakup thresholds at 1.47 and 2.47 MeV, respectively. The weak binding of these projectiles introduces several new reaction channels not usually observed in the case of strongly bound projectiles. The impact of these breakup or breakup-like reaction channels on fusion, the dominant reaction process at near-barrier energies, with different target masses is of current interest. Purpose: Our purpose is to explore the fusion, at above and below the Coulmb barrier, of 7Li with 64Ni target in order to understand the effect of breakup or breakup-like processes with medium-mass target in comparison with 6Li, which has a lower breakup threshold. Measurement: The total fusion (TF) excitation of the weakly bound projectile 7Li with the medium-mass target 64Ni has been measured at the near-barrier energies (0.8 to 2 VB). The measurement was performed using the online characteristic γ -ray detection method. The complete fusion (CF) excitation function for the system was obtained using the x n -evaporation channels with the help of statistical model predictions. Results: At the above barrier energies CF cross sections exhibit an average suppression of about 6.5% compared to the one-dimensional barrier penetration model (1DBPM) predictions, while the model describes the measured TF cross section well. But below the barrier, both TF and CF show enhancements compared to 1DBPM predictions. Unlike 6Li, enhancement of CF for 7Li could not be explained by inelastic coupling alone. Conclusion: Whereas the σTF cross sections are almost the same for both the systems in the above barrier region, the suppression of σCF at above the barrier is less for the 7Li+64Ni system than for the 6+64Ni system. Also direct cluster transfer has been identified as the probable source for producing large enhancement in TF cross sections.

  3. Low energy barriers of H-atom abstraction from phenols

    NASA Astrophysics Data System (ADS)

    Tishchenko, Oksana; Kryachko, Eugene S.; Nguyen, Minh Tho

    2002-09-01

    The energy barriers governing the hydrogen atom transfer between phenols related to Vitamin E and methylperoxyl radical are determined using the B3LYP/6-31G(d,p) method. For phenol, o, o-dimethylphenol, and o, o, m-trimethylphenol, they are equal to 6.0, 4.2, and 3.5 kcal/mol, respectively. While in both reactants and products the H-bond is nearly coplanar with the aromatic ring, it becomes essentially twisted out of the ring in the transition state structures. This implies that the transition states in such reactions are likely located at the avoided crossing of the lower-lying electronic states of the H-bonded complex, correlating with the ground π and first excited σ states of the incipient phenoxyl radical.

  4. Free Energy Wells and Barriers to Ion Transport Across Membranes

    NASA Astrophysics Data System (ADS)

    Rempe, Susan

    2014-03-01

    The flow of ions across cellular membranes is essential to many biological processes. Ion transport is also important in synthetic materials used as battery electrolytes. Transport often involves specific ions and fast conduction. To achieve those properties, ion conduction pathways must solvate specific ions by just the ``right amount.'' The right amount of solvation avoids ion traps due to deep free energy wells, and avoids ion block due to high free energy barriers. Ion channel proteins in cellular membranes demonstrate this subtle balance in solvation of specific ions. Using ab initio molecular simulations, we have interrogated the link between binding site structure and ion solvation free energies in biological ion binding sites. Our results emphasize the surprisingly important role of the environment that surrounds ion-binding sites for fast transport of specific ions. We acknowledge support from Sandia's LDRD program. Sandia National Labs is a multi-program laboratory operated by Sandia Corp., a wholly owned subsidiary of Lockheed Martin Corp., for the US DOE's NNSA under contract DE-AC04-94AL85000.

  5. Energy from low temperature differences

    NASA Astrophysics Data System (ADS)

    Parsons, B. K.

    1985-05-01

    A number of energy conservation and alternative energy approaches utilize a low temperature heat source. Applications in this category include: solar ponds, ocean thermal energy conversion (OTEC), low temperature solar thermal, geothermal, and waste heat recovery and bottoming cycles. Low temperature power extraction techniques are presented and the differences between closed and open Rankine power cycles are discussed. Specific applications and technical areas of current research in OTEC along with a breakdown of plant operating conditions and a rough cost estimate illustrate how the use of low temperature power conversion technology can be cost effective.

  6. Perceived Career Barriers and Coping among Youth in Israel: Ethnic and Gender Differences

    ERIC Educational Resources Information Center

    Lipshits-Braziler, Yuliya; Tatar, Moshe

    2012-01-01

    This study investigated gender and ethnic differences in the perception of different types of career barriers among young adults in relation to their views of themselves as individuals (Personal Career Barriers) and their views of their gender and ethnic group (Group Career Barriers). This study also explored gender and ethnic differences in the…

  7. Coarse-grained molecular dynamics study of membrane fusion: Curvature effects on free energy barriers along the stalk mechanism

    NASA Astrophysics Data System (ADS)

    Kawamoto, Shuhei; Klein, Michael L.; Shinoda, Wataru

    2015-12-01

    The effects of membrane curvature on the free energy barrier for membrane fusion have been investigated using coarse-grained molecular dynamics (CG-MD) simulations, assuming that fusion takes place through a stalk intermediate. Free energy barriers were estimated for stalk formation as well as for fusion pore formation using the guiding potential method. Specifically, the three different geometries of two apposed membranes were considered: vesicle-vesicle, vesicle-planar, and planar-planar membranes. The free energy barriers for the resulting fusion were found to depend importantly on the fusing membrane geometries; the lowest barrier was obtained for vesicular membranes. Further, lipid sorting was observed in fusion of the mixed membranes of dimyristoyl phosphatidylcholine and dioleoyl phosphatidylethanolamine (DOPE). Specifically, DOPE molecules were found to assemble around the stalk to support the highly negative curved membrane surface. A consistent result for lipid sorting was observed when a simple continuum model (CM) was used, where the Helfrich energy and mixing entropy of the lipids were taken into account. However, the CM predicts a much higher free energy barrier than found using CG-MD. This discrepancy originates from the conformational changes of lipids, which were not considered in the CM. The results of the CG-MD simulations reveal that a large conformational change in the lipid takes place around the stalk region, which results in a reduction of free energy barriers along the stalk mechanism of membrane fusion.

  8. Coarse-grained molecular dynamics study of membrane fusion: Curvature effects on free energy barriers along the stalk mechanism

    SciTech Connect

    Kawamoto, Shuhei; Shinoda, Wataru; Klein, Michael L.

    2015-12-28

    The effects of membrane curvature on the free energy barrier for membrane fusion have been investigated using coarse-grained molecular dynamics (CG-MD) simulations, assuming that fusion takes place through a stalk intermediate. Free energy barriers were estimated for stalk formation as well as for fusion pore formation using the guiding potential method. Specifically, the three different geometries of two apposed membranes were considered: vesicle–vesicle, vesicle–planar, and planar–planar membranes. The free energy barriers for the resulting fusion were found to depend importantly on the fusing membrane geometries; the lowest barrier was obtained for vesicular membranes. Further, lipid sorting was observed in fusion of the mixed membranes of dimyristoyl phosphatidylcholine and dioleoyl phosphatidylethanolamine (DOPE). Specifically, DOPE molecules were found to assemble around the stalk to support the highly negative curved membrane surface. A consistent result for lipid sorting was observed when a simple continuum model (CM) was used, where the Helfrich energy and mixing entropy of the lipids were taken into account. However, the CM predicts a much higher free energy barrier than found using CG-MD. This discrepancy originates from the conformational changes of lipids, which were not considered in the CM. The results of the CG-MD simulations reveal that a large conformational change in the lipid takes place around the stalk region, which results in a reduction of free energy barriers along the stalk mechanism of membrane fusion.

  9. Coarse-grained molecular dynamics study of membrane fusion: Curvature effects on free energy barriers along the stalk mechanism.

    PubMed

    Kawamoto, Shuhei; Klein, Michael L; Shinoda, Wataru

    2015-12-28

    The effects of membrane curvature on the free energy barrier for membrane fusion have been investigated using coarse-grained molecular dynamics (CG-MD) simulations, assuming that fusion takes place through a stalk intermediate. Free energy barriers were estimated for stalk formation as well as for fusion pore formation using the guiding potential method. Specifically, the three different geometries of two apposed membranes were considered: vesicle-vesicle, vesicle-planar, and planar-planar membranes. The free energy barriers for the resulting fusion were found to depend importantly on the fusing membrane geometries; the lowest barrier was obtained for vesicular membranes. Further, lipid sorting was observed in fusion of the mixed membranes of dimyristoyl phosphatidylcholine and dioleoyl phosphatidylethanolamine (DOPE). Specifically, DOPE molecules were found to assemble around the stalk to support the highly negative curved membrane surface. A consistent result for lipid sorting was observed when a simple continuum model (CM) was used, where the Helfrich energy and mixing entropy of the lipids were taken into account. However, the CM predicts a much higher free energy barrier than found using CG-MD. This discrepancy originates from the conformational changes of lipids, which were not considered in the CM. The results of the CG-MD simulations reveal that a large conformational change in the lipid takes place around the stalk region, which results in a reduction of free energy barriers along the stalk mechanism of membrane fusion.

  10. Transition path time distribution and the transition path free energy barrier.

    PubMed

    Pollak, Eli

    2016-10-19

    The recent experimental measurement of the transition path time distributions of proteins presents several challenges to theory. Firstly, why do the fits of the experimental data to a theoretical expression lead to barrier heights which are much lower than the free energies of activation of the observed transitions? Secondly, there is the theoretical question of determining the transition path time distribution, without invoking the Smoluchowski limit. In this paper, we derive an exact expression for a transition path time distribution which is valid for arbitrary memory friction using the normal mode transformation which underlies Kramers' rate theory. We then recall that for low barriers, there is a noticeable difference between the transition path time distribution obtained with absorbing boundary conditions and free boundary conditions. For the former, the transition times are shorter, since recrossings of the boundaries are disallowed. As a result, if one uses the distribution based on absorbing boundary conditions to fit the experimental data, one will find that the transition path barrier will be larger than the values found based on a theory with free boundary conditions. We then introduce the paradigm of a transition path barrier height, and show that one should always expect it to be much smaller than the activation energy.

  11. The effects of a high-energy diet on hippocampal-dependent discrimination performance and blood-brain barrier integrity differ for diet-induced obese and diet-resistant rats.

    PubMed

    Davidson, Terry L; Monnot, Andrew; Neal, Adelai U; Martin, Ashley A; Horton, J Josiah; Zheng, Wei

    2012-08-20

    Rats that consume high-energy (HE) diets (i.e., diets high in saturated fats and sugar) show impaired hippocampal-dependent learning and memory (e.g., Kanoski and Davidson (2011) [1]). To further investigate this effect, we trained rats given restricted access to low-fat lab chow on hippocampal-dependent serial feature-negative (FN) and hippocampal-independent simple discrimination problems. When training was completed, Group Chow received ad libitum lab chow. The remaining rats received ad libitum HE diet. Performance on both discrimination problems was tested following 7, 14, 21 and 28 days of HE diet exposure. FN, but not simple discrimination, was abolished initially for all rats, and then re-emerged for Group Chow. For rats fed HE diet, those that weighed the least and had the lowest amount of body fat (HE-diet resistant (HE-DR) rats), performed like Group Chow on both discrimination problems. However, HE diet-induced obese (HE-DIO) rats (i.e., rats that weighed the most weight and had the most body fat) performed like Group Chow on the simple discrimination problem, but were impaired throughout testing on the FN problem. Subsequent assessment of blood-brain barrier (BBB) permeability revealed that concentrations of an exogenously administered dye were elevated in the hippocampus, but not in the striatum or prefrontal cortex for HE-DIO rats relative to the HE-DR and Chow groups. The results indicate that the adverse consequences of HE diet on hippocampal-dependent cognitive functioning are associated with detrimental effects on the BBB and that both of these outcomes vary with sensitivity to HE diet-induced increases in weight and adiposity.

  12. Permeation of low-Z atoms through carbon sheets: Density functional theory study on energy barriers and deformation effects

    SciTech Connect

    Huber, Stefan E. E-mail: Michael.probst@uibk.ac.at; Mauracher, Andreas; Probst, Michael E-mail: Michael.probst@uibk.ac.at

    2013-12-15

    Energetic and geometric aspects of the permeation of the atoms hydrogen to neon neutral atoms through graphene sheets are investigated by investigating the associated energy barriers and sheet deformations. Density functional theory calculations on cluster models, where graphene is modeled by planar polycyclic aromatic hydrocarbons (PAHs), provide the energies and geometries. Particularities of our systems, such as convergence of both energy barriers and deformation curves with increasing size of the PAHs, are discussed. Three different interaction regimes, adiabatic, planar and vertical, are investigated by enforcing different geometrical constraints. The adiabatic energy barriers range from 5 eV for hydrogen to 20 eV for neon. We find that the permeation of oxygen and carbon into graphene is facilitated by temporary chemical bonding while for other, in principle reactive atoms, it is not. We discuss implications of our results for modeling chemical sputtering of graphite.

  13. Modeling the Catalysis of Anti-Cocaine Catalytic Antibody: Competing Reaction Pathways and Free Energy Barriers

    PubMed Central

    Pan, Yongmei; Gao, Daquan; Zhan, Chang-Guo

    2010-01-01

    The competing reaction pathways and the corresponding free energy barriers for cocaine hydrolysis catalyzed by an anti-cocaine catalytic antibody, mAb 15A10, were studied by using a novel computational strategy based on the binding free energy calculations on the antibody binding with cocaine and transition states. The calculated binding free energies were used to evaluate the free energy barrier shift from the cocaine hydrolysis in water to the antibody-catalyzed cocaine hydrolysis for each reaction pathway. The free energy barriers for the antibody-catalyzed cocaine hydrolysis were predicted to be the corresponding free energy barriers for the cocaine hydrolysis in water plus the calculated free energy barrier shifts. The calculated free energy barrier shift of −6.33 kcal/mol from the dominant reaction pathway of the cocaine benzoyl ester hydrolysis in water to the dominant reaction pathway of the antibody-catalyzed cocaine hydrolysis is in good agreement with the experimentally-derived free energy barrier shift of −5.93 kcal/mol. The calculated mutation-caused shifts of the free energy barrier are also reasonably close to the available experimental activity data. The good agreement suggests that the protocol for calculating the free energy barrier shift from the cocaine hydrolysis in water to the antibody-catalyzed cocaine hydrolysis may be used in future rational design of possible high-activity mutants of the antibody as anti-cocaine therapeutics. The general strategy of the free energy barrier shift calculation may also be valuable in studying a variety of chemical reactions catalyzed by other antibodies or proteins through non-covalent bonding interactions with the substrates. PMID:18341277

  14. Technical Barriers, Gaps,and Opportunities Related to Home Energy Upgrade Market Delivery

    SciTech Connect

    Bianchi, Marcus V.A.

    2011-11-01

    This report outlines the technical barriers, gaps, and opportunities that arise in executing home energy upgrade market delivery approaches, as identified through research conducted by the U.S. Department of Energy's Building America program.

  15. Polymeric nanoparticles of different sizes overcome the cell membrane barrier.

    PubMed

    Lerch, Simone; Dass, Martin; Musyanovych, Anna; Landfester, Katharina; Mailänder, Volker

    2013-06-01

    Polymeric nanoparticles have tremendous potential either as carriers or markers in treatment for diseases or as diagnostics in biomedical applications. Finding the optimal conditions for effective intracellular delivery of the payload to the location of interest is still a big challenge. The particles have to overcome the barrier of the cell membrane. Here, we investigated the uptake in HeLa cells of fluorescent polystyrene particles with different size and surface charge. Particles stabilized with the nonionic surfactant Lutensol AT50® (132 nm, 180 nm, 242 nm, 816 nm, 846 nm diameter) were synthesized via dispersion polymerization. Cationic particles (120 nm, 208 nm, 267 nm, 603 nm diameter) were obtained by a combination of miniemulsion and seed dispersion polymerization using cationic surfactant (cetyltrimethylammonium chloride (CTMA-Cl). The particle uptake into HeLa cells was studied by confocal laser scanning microscopy and flow cytometry. Nonionic particles were - independent of their size - taken up by cells only at a barely detectable level, thus aggravating a quantitative comparison. The uptake of positively charged particles was substantially higher and therefore enabling further investigation keeping constant one of these parameters: either material amount or particles number or total interaction surface area. It was found that the uptake rather depends on the total amount of polymeric material present in the media than on the number of particles. The total particle's surface area does not correlate linearly with the uptake, thus indicating that there is no direct dependency between the total surface area and the cellular endocytotic process to overcome the biobarrier "cell membrane." A potentially novel uptake mechanism is found which can be described as an excavator shovel like mechanism. It is a kind of macropinocytosis dependent on actin filaments as well as dynamin, but is clathrin-independent.

  16. Gate-controlled energy barrier at a graphene/molecular semiconductor junction

    NASA Astrophysics Data System (ADS)

    Parui, S.; Pietrobon, L.; Ciudad, D.; Velez, S.; Sun, X.; Stoliar, P.; Casanova, F.; Hueso, L. E.

    The formation of an energy barrier at a metal/molecular semiconductor junction is both a ubiquitous phenomenon as well as the subject of intense research in order to improve the performance of molecular semiconductor-based electronic and optoelectronic devices. For these devices, a junction with a large energy barrier provides rectification, leading to a diode behavior, whereas a relatively small energy barrier provides nearly-ohmic behavior, resulting in efficient carrier injection (extraction) into the molecular semiconductor. Typically, a specific metal/molecular semiconductor combination leads to a fixed energy barrier; therefore, the possibility of a gate-controlled energy barrier is very appealing for advanced applications. Here, we present a graphene/C60 junction-based vertical field-effect transistor in which we demonstrate control of the interfacial energy-barrier such that the junction switches from a highly rectifying diode at negative gate voltages to a nearly-ohmic behavior at positive gate voltages and at room temperature. We extract an energy-barrier modulation of up to 660 meV, a transconductance of up to five orders of magnitude and a gate-modulated photocurrent.

  17. Heavy-ion reactions at energies near the Coulomb barrier

    SciTech Connect

    Satchler, G.R.

    1991-01-01

    The title covers a very broad area of both experimental and theoretical studies. The common characteristic of heavy-ion collisions at these energies, compared to what is usually seen at higher energies, is the important interplay between different reaction channels or internal degrees of freedom. The couplings between the various channels can result in important multistep contributions to a given channel. These often have to be treated explicitly, for example by solving the appropriate set of coupled equations. In contrast, at higher energies the effects of these couplings frequently can be represented in a simple, average way, as is done when one introduces an imaginary part to the optical potential for elastic scattering. At first, it might be thought that the possible importance of multistep transitions would be a strong disadvantage of working at these energies. However, although the analysis of the data becomes more complicate, the study of these terms and their interferences can be a rich source of information. In particular, it can tell us, indirectly, something about transitions between two excited states. Overviews of some of these phenomena have been presented elsewhere; here I have selected two topics as representative. Even then I cannot go into much detail, so perhaps this paper is best regarded as providing some references as the stating point for a literature search

  18. Between-species variation in the kinetic stability of TIM proteins linked to solvation-barrier free energies.

    PubMed

    Costas, Miguel; Rodríguez-Larrea, David; De Maria, Leonardo; Borchert, Torben V; Gómez-Puyou, Armando; Sanchez-Ruiz, Jose M

    2009-01-23

    Theoretical, computational, and experimental studies have suggested the existence of solvation barriers in protein unfolding and denaturation processes. These barriers are related to the finite size of water molecules and can be envisioned as arising from the asynchrony between water penetration and breakup of internal interactions. Solvation barriers have been proposed to play roles in protein cooperativity and kinetic stability; therefore, they may be expected to be subject to natural selection. We study the thermal denaturation, in the presence and in the absence of chemical denaturants, of triosephosphate isomerases (TIMs) from three different species: Trypanosoma cruzi, Trypanosoma brucei, and Leishmania mexicana. In all cases, denaturation was irreversible and kinetically controlled. Surprisingly, however, we found large differences between the kinetic denaturation parameters, with T. cruzi TIM showing a much larger activation energy value (and, consequently, much lower room-temperature, extrapolated denaturation rates). This disparity cannot be accounted for by variations in the degree of exposure to solvent in transition states (as measured by kinetic urea m values) and is, therefore, to be attributed mainly to differences in solvation-barrier contributions. This was supported by structure-energetics analyses of the transition states and by application of a novel procedure to estimate from experimental data the solvation-barrier impact at the entropy and free-energy levels. These analyses were actually performed with an extended protein set (including six small proteins plus seven variants of lipase from Thermomyces lanuginosus and spanning a wide range of activation parameters), allowing us to delineate the general trends of the solvation-barrier contributions. Overall, this work supports that proteins sharing the same structure and function but belonging to different organisms may show widely different solvation barriers, possibly as a result of different

  19. On the economic analysis of problems in energy efficiency: Market barriers, market failures, and policy implications

    SciTech Connect

    Sanstad, A.H.; Koomey, J.G.; Levine, M.D.

    1993-01-01

    In his recent paper in The Energy Journal, Ronald Sutherland argues that several so-called ``market barriers`` to energy efficiency frequently cited in the literature are not market failures in the conventional sense and are thus irrelevant for energy policy. We argue that Sutherland has inadequately analyzed the idea of market barrier and misrepresented the policy implications of microeconomics. We find that economic theory, correctly interpreted, does not provide for the categorical dismissal of market barriers. We explore important methodological issues underlying the debate over market barriers, and discuss the importance of reconciling the findings of non-economic social sciences with the economic analysis of energy demand and consumer decision-making. We also scrutinize Sutherland`s attempt to apply finance theory to rationalize high implicit discount rates observed in energy-related choices, and find this use of finance theory to be inappropriate.

  20. On the economic analysis of problems in energy efficiency: Market barriers, market failures, and policy implications

    SciTech Connect

    Sanstad, A.H.; Koomey, J.G.; Levine, M.D.

    1993-01-01

    In his recent paper in The Energy Journal, Ronald Sutherland argues that several so-called market barriers'' to energy efficiency frequently cited in the literature are not market failures in the conventional sense and are thus irrelevant for energy policy. We argue that Sutherland has inadequately analyzed the idea of market barrier and misrepresented the policy implications of microeconomics. We find that economic theory, correctly interpreted, does not provide for the categorical dismissal of market barriers. We explore important methodological issues underlying the debate over market barriers, and discuss the importance of reconciling the findings of non-economic social sciences with the economic analysis of energy demand and consumer decision-making. We also scrutinize Sutherland's attempt to apply finance theory to rationalize high implicit discount rates observed in energy-related choices, and find this use of finance theory to be inappropriate.

  1. Barriers to Energy Efficiency and the Uptake of Green Revolving Funds in Canadian Universities

    ERIC Educational Resources Information Center

    Maiorano, John; Savan, Beth

    2015-01-01

    Purpose: The purpose of this paper is to investigate the barriers to the implementation of energy efficiency projects in Canadian universities, including access to capital, bounded rationality, hidden costs, imperfect information, risk and split incentives. Methods to address these barriers are investigated, including evaluating the efficacy of…

  2. Influence of rotational energy barriers to the conformational search of protein loops in molecular dynamics and ranking the conformations.

    PubMed

    Tappura, K

    2001-08-15

    An adjustable-barrier dihedral angle potential was added as an extension to a novel, previously presented soft-core potential to study its contribution to the efficacy of the search of the conformational space in molecular dynamics. As opposed to the conventional soft-core potential functions, the leading principle in the design of the new soft-core potential, as well as of its extension, the soft-core and adjustable-barrier dihedral angle (SCADA) potential (referred as the SCADA potential), was to maintain the main equilibrium properties of the original force field. This qualifies the methods for a variety of a priori modeling problems without need for additional restraints typically required with the conventional soft-core potentials. In the present study, the different potential energy functions are applied to the problem of predicting loop conformations in proteins. Comparison of the performance of the soft-core and SCADA potential showed that the main hurdles for the efficient sampling of the conformational space of (loops in) proteins are related to the high-energy barriers caused by the Lennard-Jones and Coulombic energy terms, and not to the rotational barriers, although the conformational search can be further enhanced by lowering the rotational barriers of the dihedral angles. Finally, different evaluation methods were studied and a few promising criteria found to distinguish the near-native loop conformations from the wrong ones.

  3. Experimental study on temperature characteristics and energy conversion in packed bed reactor with dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Li, Sen; Tang, Zuchen; Gu, Fan

    2010-10-01

    The temperature characteristics and energy conversion in packed bed reactor combined with a dielectric barrier discharge (DBD) plasma was investigated experimentally. The pellet temperatures of two types packed bed reactor, cylindrical reactor and parallel-plate reactor, was measured in conditions of various inlet voltage of DBD plasma. The relationship between pellet temperature of the packed bed and applied voltage of DBD plasma was discovered. The experimental result indicates a tendency that the pellet temperature of packed bed increases as the applied voltage of inlet plasma increases. When the voltage of inlet plasma is high enough, the pellet temperature increment decreases. Simultaneously,the packed bed temperature is sensitive to the inlet plasma energy and there is a potential application to heat exchanger. Moreover the proportion of energy consumption of plasma inputting into packed bed reactor was analyzed and calculated. The mechanisms that electrical energy of inlet plasma is transformed into heat energy in the two phases, gaseous and pellets of the packed bed reactor are different. The energy consumption in pellet phase is dielectric polarization loss and depends on packed bed geometry and DBD plasma etc. The energy consumption in gaseous phase is plasma sheath procedure. The important factors effecting on gas discharge are gaseous component and voltage, frequency of power.

  4. Reaction Pathway and Free Energy Barrier for Urea Elimination in Aqueous Solution

    PubMed Central

    Yao, Min; Chen, Xi; Zhan, Chang-Guo

    2015-01-01

    To accurately predict the free energy barrier for urea elimination in aqueous solution, we examined the reaction coordinates for the direct and water-assisted elimination pathways, and evaluated the corresponding free energy barriers by using the surface and volume polarization for electrostatics (SVPE) model-based first-principles electronic-structure calculations. Based on the computational results, the water-assisted elimination pathway is dominant for urea elimination in aqueous solution, and the corresponding free energy barrier is 25.3 kcal/mol. The free energy barrier of 25.3 kcal/mol predicted for the dominant reaction pathway of urea elimination in aqueous solution is in good agreement with available experimental kinetic data. PMID:25821238

  5. Barriers and opportunities: A review of selected successful energy-efficiency programs

    SciTech Connect

    Worrell, Ernst; Price, Lynn

    2001-03-20

    In industry, barriers may exist at various points in the decision making process, and in the implementation and management of measures to improve energy efficiency. Barriers may take many forms, and are determined by the business environment and include decision-making processes, energy prices, lack of information, a lack of confidence in the information, or high transaction costs for obtaining reliable information, as well as limited capital availability. Other barriers are the ''invisibility'' of energy efficiency measures and the difficulty of quantifying the impacts, and slow diffusion of innovative technology into markets while firms typically under-invest in R and D, despite the high pay-backs. Various programs try to reduce the barriers to improve the uptake of innovative technologies. A wide array of policies has been used and tested in the industrial sector in industrialized countries, with varying success rates. We review some new approaches to industrial energy efficiency improvement in industrialized countries, focusing on voluntary agreements.

  6. Energy barriers for dipole moment flipping in PVDF-related ferroelectric polymers.

    PubMed

    Yu, Ying-Ju; McGaughey, Alan J H

    2016-01-07

    Energy barriers for flipping the transverse dipole moments in poly(vinylidene fluoride) (PVDF) and related copolymers and terpolymers are predicted using the nudged elastic band method. The dipole moments flip individually along the chain, with an order and energy barrier magnitudes (0.1-1.2 eV) that depend on the chain composition and environment. Trifluoroethylene (TrFE) and chlorofluoroethylene (CFE) monomers have larger energy barriers than VDF monomers, while a chain in an amorphous environment has a similar transition pathway as that of an isolated molecule. In a crystalline environment, TrFE and CFE monomers expand the lattice and lower the energy barriers for flipping VDF monomers. This finding is consistent with experimental observations of a large electrocaloric effect in P(VDF-TrFE-CFE) terpolymers.

  7. Energy barriers for dipole moment flipping in PVDF-related ferroelectric polymers

    NASA Astrophysics Data System (ADS)

    Yu, Ying-Ju; McGaughey, Alan J. H.

    2016-01-01

    Energy barriers for flipping the transverse dipole moments in poly(vinylidene fluoride) (PVDF) and related copolymers and terpolymers are predicted using the nudged elastic band method. The dipole moments flip individually along the chain, with an order and energy barrier magnitudes (0.1-1.2 eV) that depend on the chain composition and environment. Trifluoroethylene (TrFE) and chlorofluoroethylene (CFE) monomers have larger energy barriers than VDF monomers, while a chain in an amorphous environment has a similar transition pathway as that of an isolated molecule. In a crystalline environment, TrFE and CFE monomers expand the lattice and lower the energy barriers for flipping VDF monomers. This finding is consistent with experimental observations of a large electrocaloric effect in P(VDF-TrFE-CFE) terpolymers.

  8. Building America Top Innovations 2012: Thermal Bypass Air Barriers in the 2009 International Energy Conservation Code

    SciTech Connect

    none,

    2013-01-01

    This Building America Top Innovations profile describes Building America research supporting Thermal Bypass Air Barrier requirements. Since these were adopted in the 2009 IECC, close to one million homes have been mandated to include this vitally important energy efficiency measure.

  9. A Local Order Parameter-Based Method for Simulation of Free Energy Barriers in Crystal Nucleation.

    PubMed

    Eslami, Hossein; Khanjari, Neda; Müller-Plathe, Florian

    2017-03-14

    While global order parameters have been widely used as reaction coordinates in nucleation and crystallization studies, their use in nucleation studies is claimed to have a serious drawback. In this work, a local order parameter is introduced as a local reaction coordinate to drive the simulation from the liquid phase to the solid phase and vice versa. This local order parameter holds information regarding the order in the first- and second-shell neighbors of a particle and has different well-defined values for local crystallites and disordered neighborhoods but is insensitive to the type of the crystal structure. The order parameter is employed in metadynamics simulations to calculate the solid-liquid phase equilibria and free energy barrier to nucleation. Our results for repulsive soft spheres and the Lennard-Jones potential, LJ(12-6), reveal better-resolved solid and liquid basins compared with the case in which a global order parameter is used. It is also shown that the configuration space is sampled more efficiently in the present method, allowing a more accurate calculation of the free energy barrier and the solid-liquid interfacial free energy. Another feature of the present local order parameter-based method is that it is possible to apply the bias potential to regions of interest in the order parameter space, for example, on the largest nucleus in the case of nucleation studies. In the present scheme for metadynamics simulation of the nucleation in supercooled LJ(12-6) particles, unlike the cases in which global order parameters are employed, there is no need to have an estimate of the size of the critical nucleus and to refine the results with the results of umbrella sampling simulations. The barrier heights and the nucleation pathway obtained from this method agree very well with the results of former umbrella sampling simulations.

  10. Quantum chemical ab initio prediction of proton exchange barriers between CH{sub 4} and different H-zeolites

    SciTech Connect

    Tuma, Christian; Sauer, Joachim

    2015-09-14

    A hybrid MP2:DFT (second-order Møller–Plesset perturbation theory–density functional theory) method that combines MP2 calculations for cluster models with DFT calculations for the full periodic structure is used to localize minima and transition structures for proton jumps at different Brønsted sites in different frameworks (chabazite, faujasite, ferrierite, and ZSM-5) and at different crystallographic positions of a given framework. The MP2 limit for the periodic structures is obtained by extrapolating the results of a series of cluster models of increasing size. A coupled-cluster (CCSD(T)) correction to MP2 energies is calculated for cluster models consisting of three tetrahedra. For the adsorption energies, this difference is small, between 0.1 and 0.9 kJ/mol, but for the intrinsic proton exchange barriers, this difference makes a significant (10.85 ± 0.25 kJ/mol) and almost constant contribution across different systems. The total values of the adsorption energies vary between 22 and 34 kJ/mol, whereas the total proton exchange energy barriers fall in the narrow range of 152–156 kJ/mol. After adding nuclear motion contributions (harmonic approximation, 298 K), intrinsic enthalpy barriers between 134 and 141 kJ/mol and apparent energy barriers between 105 and 118 kJ/mol are predicted for the different sites examined for the different frameworks. These predictions are consistent with experimental results available for faujasite, ferrierite, and ZSM-5.

  11. Barrier distributions and signatures of transfer channels in the Ca40+Ni58,64 fusion reactions at energies around and below the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Bourgin, D.; Courtin, S.; Haas, F.; Stefanini, A. M.; Montagnoli, G.; Goasduff, A.; Montanari, D.; Corradi, L.; Fioretto, E.; Huiming, J.; Scarlassara, F.; Rowley, N.; Szilner, S.; Mijatović, T.

    2014-10-01

    Background: The nuclear structure of colliding nuclei is known to influence the fusion process. Couplings of the relative motion to nuclear shape deformations and vibrations lead to an enhancement of the sub-barrier fusion cross section in comparison with the predictions of one-dimensional barrier penetration models. This enhancement is explained by coupled-channels calculations including these couplings. The sub-barrier fusion cross section is also affected by nucleon transfer channels between the colliding nuclei. Purpose: The aim of the present experiment is to investigate the influence of the projectile and target nuclear structures on the fusion cross sections in the Ca40+Ni58 and Ca40+Ni64 systems. Methods: The experimental and theoretical fusion excitation functions as well as the barrier distributions were compared for these two systems. Coupled-channels calculations were performed using the ccfull code. Results: Good agreement was found between the measured and calculated fusion cross sections for the Ca40+Ni58 system. The situation is different for the Ca40+Ni64 system where the coupled-channels calculations with no nucleon transfer clearly underestimate the fusion cross sections below the Coulomb barrier. The fusion excitation function was, however, well reproduced at low and high energies by including the coupling to the neutron pair-transfer channel in the calculations. Conclusions: The nuclear structure of the colliding nuclei influences the fusion cross sections below the Coulomb barrier for both Ca40+Ni58,64 systems. Moreover, we highlighted the effect of the neutron pair-transfer channel on the fusion cross sections in Ca40+Ni64.

  12. Summary of Gaps and Barriers for Implementing Residential Building Energy Efficiency Strategies

    SciTech Connect

    Not Available

    2010-08-01

    This report presents the key gaps and barriers to implementing residential energy efficiency strategies in the U.S. market, as identified in sessions at the U.S. Department of Energy's Building America 2010 Residential Energy Efficiency Meeting held in Denver, Colorado, on July 20-22, 2010.

  13. Do stigma and other perceived barriers to mental health care differ across Armed Forces?

    PubMed Central

    Gould, Matthew; Adler, Amy; Zamorski, Mark; Castro, Carl; Hanily, Natalie; Steele, Nicole; Kearney, Steve; Greenberg, Neil

    2010-01-01

    Summary Objectives Military organizations are keen to address barriers to mental health care yet stigma and barriers to care remain little understood, especially potential cultural differences between Armed Forces. The aim of this study was to compare data collected by the US, UK, Australian, New Zealand and Canadian militaries using Hoge et al.'s perceived stigma and barriers to care measure (Combat duty in Iraq and Afghanistan, mental health problems and barriers to care. New Engl J Med 2004;351:13–22). Design Each member country identified data sources that had enquired about Hoge et al.'s perceived stigma and perceived barriers to care items in the re-deployment or immediate post-deployment period. Five relevant statements were included in the study. Setting US, UK Australian, New Zealand and Canadian Armed Forces. Results Concerns about stigma and barriers to care tended to be more prominent among personnel who met criteria for a mental health problem. The pattern of reported stigma and barriers to care was similar across the Armed Forces of all five nations. Conclusions Barriers to care continue to be a major issue for service personnel within Western military forces. Although there are policy, procedural and cultural differences between Armed Forces, the nations studied appear to share some similarities in terms of perceived stigma and barriers to psychological care. Further research to understand patterns of reporting and subgroup differences is required. PMID:20382906

  14. The effect of applied voltage frequency on surface dielectric barrier discharge energy

    NASA Astrophysics Data System (ADS)

    Lazukin, A. V.; Gundareva, S. V.; Krivov, S. A.; Nikitin, A. M.; Kavyrshin, D. I.; Fedorovich, S. D.

    2016-11-01

    Results of the experimental investigation of surface dielectric barrier discharge's energy dependence on frequency of applied sinusoidal voltage varying from 0.6 to 40 kHz at atmospheric pressure are presented in the paper for disk electrodes of 20, 50 and 150 μm thick. It is shown that surface dielectric barrier discharge's energy dependence on applied voltage frequency represents an U-shaped curve with a distinct minimum. The value and position of energy minimum are related with thickness of the generating plasma electrode, the barrier material and supply voltage. Increase of plasma heat dissipation owing to selection of the dielectric barrier material changes significantly a trend of the U-shaped curve.

  15. Fusion excitation function measurement for 6Li+64Ni at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Moin Shaikh, Md.; Roy, Subinit; Rajbanshi, S.; Pradhan, M. K.; Mukherjee, A.; Basu, P.; Pal, S.; Nanal, V.; Pillay, R. G.; Shrivastav, A.

    2015-01-01

    Total fusion excitation function has been measured for the reaction of weakly bound 6Li projectile on medium mass 64Ni target at energies near the Coulomb barrier of the system. Online characteristic γ-ray detection method has been used to identify and determine the cross sections of the residues. No suppression of total fusion cross section (σTF) is observed at above barrier energies. But enhancement of measured cross section with respect to the one-dimensional barrier penetration model (1-DBPM) calculation is observed at below barrier energies. The enhancement can not be explained by coupled channels calculation with dominant projectile and target excitations as well as one-neutron stripping reaction.

  16. A novel method for calculating the energy barriers for carbon diffusion in ferrite under heterogeneous stress

    SciTech Connect

    Tchitchekova, Deyana S.; Morthomas, Julien; Perez, Michel; Ribeiro, Fabienne; Ducher, Roland

    2014-07-21

    A novel method for accurate and efficient evaluation of the change in energy barriers for carbon diffusion in ferrite under heterogeneous stress is introduced. This method, called Linear Combination of Stress States, is based on the knowledge of the effects of simple stresses (uniaxial or shear) on these diffusion barriers. Then, it is assumed that the change in energy barriers under a complex stress can be expressed as a linear combination of these already known simple stress effects. The modifications of energy barriers by either uniaxial traction/compression and shear stress are determined by means of atomistic simulations with the Climbing Image-Nudge Elastic Band method and are stored as a set of functions. The results of this method are compared to the predictions of anisotropic elasticity theory. It is shown that, linear anisotropic elasticity fails to predict the correct energy barrier variation with stress (especially with shear stress) whereas the proposed method provides correct energy barrier variation for stresses up to ∼3 GPa. This study provides a basis for the development of multiscale models of diffusion under non-uniform stress.

  17. Gender and Ethnic Differences in the Perception of Barriers to Career Development.

    ERIC Educational Resources Information Center

    Luzzo, Darrell Anthony

    The present study examined: (1) the relationship between the number and types of occupational barriers perceived by college students and their current levels of career development; and (2) gender and ethnic differences in the types of barriers perceived. Participants (129 women and 59 men) responded to open-ended questions about perceived barriers…

  18. Electric current effect on the energy barrier of magnetic domain wall depinning: origin of the quadratic contribution.

    PubMed

    Kim, Kab-Jin; Ryu, Jisu; Gim, Gi-Hong; Lee, Jae-Chul; Shin, Kyung-Ho; Lee, Hyun-Woo; Choe, Sug-Bong

    2011-11-18

    The energy barrier of a magnetic domain wall trapped at a defect is measured experimentally. When the domain wall is pushed by an electric current and/or a magnetic field, the depinning time from the barrier exhibits perfect exponential distribution, indicating that a single energy barrier governs the depinning. The electric current is found to generate linear and quadratic contributions to the energy barrier, which are attributed to the nonadiabatic and adiabatic spin-transfer torques, respectively. The adiabatic spin-transfer torque reduces the energy barrier and, consequently, causes depinning at lower current densities, promising a way toward low-power current-controlled magnetic applications.

  19. Ion channel gates: comparative analysis of energy barriers.

    PubMed

    Tai, Kaihsu; Haider, Shozeb; Grottesi, Alessandro; Sansom, Mark S P

    2009-04-01

    The energetic profile of an ion translated along the axis of an ion channel should reveal whether the structure corresponds to a functionally open or closed state of the channel. In this study, we explore the combined use of Poisson-Boltzmann electrostatic calculations and evaluation of van der Waals interactions between ion and pore to provide an initial appraisal of the gating state of a channel. This approach is exemplified by its application to the bacterial inward rectifier potassium channel KirBac3.1, where it reveals the closed gate to be formed by a ring of leucine (L124) side chains. We have extended this analysis to a comparative survey of gating profiles, including model hydrophobic nanopores, the nicotinic acetylcholine receptor, and a number of potassium channel structures and models. This enables us to identify three gating regimes, and to show the limitation of this computationally inexpensive method. For a (closed) gate radius of 0.4 nm < R < 0.8 nm, a hydrophobic gate may be present. For a gate radius of 0.2 nm < R < 0.4 nm, both electrostatic and van der Waals interactions will contribute to the barrier height. Below R = 0.2 nm, repulsive van der Waals interactions are likely to dominate, resulting in a sterically occluded gate. In general, the method is more useful when the channel is wider; for narrower channels, the flexibility of the protein may allow otherwise-unsurmountable energetic barriers to be overcome.

  20. Free energy and hidden barriers of the β-sheet structure of prion protein.

    PubMed

    Paz, S Alexis; Abrams, Cameron F

    2015-10-13

    On-the-fly free-energy parametrization is a new collective variable biasing approach akin to metadynamics with one important distinction: rather than acquiring an accelerated distribution via a history-dependent bias potential, sampling on this distribution is achieved from the beginning of the simulation using temperature-accelerated molecular dynamics. In the present work, we compare the performance of both approaches to compute the free-energy profile along a scalar collective variable measuring the H-bond registry of the β-sheet structure of the mouse Prion protein. Both methods agree on the location of the free-energy minimum, but free-energy profiles from well-tempered metadynamics are subject to a much higher degree of statistical noise due to hidden barriers. The sensitivity of metadynamics to hidden barriers is shown to be a consequence of the history dependence of the bias potential, and we detail the nature of these barriers for the prion β-sheet. In contrast, on-the-fly parametrization is much less sensitive to these barriers and thus displays improved convergence behavior relative to that of metadynamics. While hidden barriers are a frequent and central issue in free-energy methods, on-the-fly free-energy parametrization appears to be a robust and preferable method to confront this issue.

  1. Free-energy barrier for electric-field-driven polymer entry into nanoscale channels.

    PubMed

    Nikoofard, Narges; Fazli, Hossein

    2011-05-01

    Free-energy barrier for entry of a charged polymer into a nanoscale channel by a driving electric field is studied theoretically and using molecular dynamics simulations. Dependence of the barrier height on the polymer length, the driving field strength, and the channel entrance geometry is investigated. Squeezing effect of the electric field on the polymer before its entry to the channel is taken into account. It is shown that lateral confinement of the polymer prior to its entry changes the polymer length dependence of the barrier height noticeably. Our theory and simulation results are in good agreement and reasonably describe related experimental data.

  2. Factors Affecting Energy Barriers for Pyramidal Inversion in Amines and Phosphines: A Computational Chemistry Lab Exercise

    ERIC Educational Resources Information Center

    Montgomery, Craig D.

    2013-01-01

    An undergraduate exercise in computational chemistry that investigates the energy barrier for pyramidal inversion of amines and phosphines is presented. Semiempirical calculations (PM3) of the ground-state and transition-state energies for NR[superscript 1]R[superscript 2]R[superscript 3] and PR[superscript 1]R[superscript 2]R[superscript 3] allow…

  3. On the role of energy barriers in determining contact angle hysteresis.

    PubMed

    Long, J; Chen, P

    2006-11-30

    The thermodynamic model of contact angles on rough, heterogeneous surfaces developed by Long et al. [J. Long, M.N. Hyder, R.Y.M. Huang and P. Chen, Adv. Colloid Interface Sci. 118 (2005) 173] was employed to study the role of energy barriers in determining contact angle hysteresis. Major energy barriers corresponding to metastable states and minor energy barriers corresponding to secondary metastable states were defined. Distributions of major and/or minor energy barriers as a function of apparent contact angle for various surfaces were obtained. The reproducibility of contact angle measurement, the effect of vibrational energy on contact angle hysteresis and the "stick-slip" phenomenon were discussed. Quantitative relations between contact angles and vibrational energy were obtained. It was found that receding contact angles are normally poorly reproducible for hydrophilic surfaces, but for extremely hydrophobic surfaces, advancing contact angles may have a poor reproducibility. When the vibrational energy available to a system increases, the measured advancing contact angle will decrease while the receding angle will increase until both reach a common value: the system equilibrium angle. This finding not only agrees well with the experimental observations in system equilibrium contact angle measurements, but also lays a theoretical foundation for such measurements. A small vibrational energy may result in a "stick-slip" phenomenon.

  4. Financing Projects That Use Clean-Energy Technologies. An Overview of Barriers and Opportunities

    SciTech Connect

    Goldman, D. P.; McKenna, J. J.; Murphy, L. M.

    2005-10-01

    This technical paper describes the importance of project financing for clean-energy technology deployment. It describes the key challenges in financing clean-energy technology projects, including technical risks, credit worthiness risk, revenue security risk, market competition, scale and related cost, as well as first-steps to overcome those barriers.

  5. Field-dependent energy barriers in Co/CoO core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Nieves, P.; Kechrakos, D.; Chubykalo-Fesenko, O.

    2016-02-01

    We perform atomistic modeling of Co/CoO nanoparticles with a diameter of a few nanometers and realistic values of the exchange and anisotropy parameters in order to study the field-dependent energy barriers under forward and backward reversal of the magnetization. The barriers are extracted from the constrained energy minimization using the integration of the Landau-Lifshitz-Gilbert equations and the Lagrange multiplier method. We show that the applied field and the interface exchange strength have opposite effects on the values of the energy barriers. In particular, while the backward (forward) energy barrier increases (decreases) linearly with the strength of the interface exchange coupling, it decreases (increases) almost quadratically with the applied magnetic field. Our results are in good agreement with the well-known Meiklejohn-Bean model of exchange bias, and allow us to analyze the limits of applicability of the macrospin approach to the study of energy barriers in core-shell Co/CoO nanoparticles.

  6. Multinucleon transfer in O,1816,19F+208Pb reactions at energies near the fusion barrier

    NASA Astrophysics Data System (ADS)

    Rafferty, D. C.; Dasgupta, M.; Hinde, D. J.; Simenel, C.; Simpson, E. C.; Williams, E.; Carter, I. P.; Cook, K. J.; Luong, D. H.; McNeil, S. D.; Ramachandran, K.; Vo-Phuoc, K.; Wakhle, A.

    2016-08-01

    Background: Nuclear reactions are complex, involving collisions between composite systems where many-body dynamics determines outcomes. Successful models have been developed to explain particular reaction outcomes in distinct energy and mass regimes, but a unifying picture remains elusive. The irreversible transfer of kinetic energy from the relative motion of the collision partners to their internal states, as is known to occur in deep inelastic collisions, has yet to be successfully incorporated explicitly into fully quantal reaction models. The influence of these processes on fusion is not yet quantitatively understood. Purpose: To investigate the population of high excitation energies in transfer reactions at sub-barrier energies, which are precursors to deep inelastic processes, and their dependence on the internuclear separation. Methods: Transfer probabilities and excitation energy spectra have been measured in collisions of O,1816,19F+208Pb , at various energies below and around the fusion barrier, by detecting the backscattered projectile-like fragments in a Δ E -E telescope. Results: The relative yields of different transfer outcomes are strongly driven by Q values, but change with the internuclear separation. In 16O+208Pb , single nucleon transfer dominates, with a strong contribution from -2 p transfer close to the Coulomb barrier, though this channel becomes less significant in relation to the -2 p 2 n transfer channel at larger separations. For 18O+208Pb , the -2 p 2 n channel is the dominant charge transfer mode at all separations. In the reactions with 19F,-3 p 2 n transfer is significant close to the barrier, but falls off rapidly with energy. Multinucleon transfer processes are shown to lead to high excitation energies (up to ˜15 MeV), which is distinct from single nucleon transfer modes which predominantly populate states at low excitation energy. Conclusions: Kinetic energy is transferred into internal excitations following transfer, with this

  7. Removing the barrier to the calculation of activation energies

    SciTech Connect

    Mesele, Oluwaseun O.; Thompson, Ward H.

    2016-10-06

    Approaches for directly calculating the activation energy for a chemical reaction from a simulation at a single temperature are explored with applications to both classical and quantum systems. The activation energy is obtained from a time correlation function that can be evaluated from the same molecular dynamics trajectories or quantum dynamics used to evaluate the rate constant itself and thus requires essentially no extra computational work.

  8. The Clean Air Act and Renewable Energy: Opportunities, Barriers, and Options

    SciTech Connect

    Wooley, D.R.; Morss, E.M.; Fang, J.M.

    2001-03-01

    This paper examines the opportunities, obstacles, and potential options to promote renewable energy under the CAA and related programs. It deals, in sequence, with the regulation of SO2, NOx, regional haze/particulate matter, and CO2. For each pollutant, the paper discusses the opportunities, barriers, and options for boosting renewables under the CAA. It concludes by comparing the options discussed. The paper is based on a project on environmental regulation and renewable energy in electricity generation conducted by the National Renewable Energy Laboratory for the Office of Power Technologies, Office of Energy Efficiency and Renewable Energy, US Department of Energy.

  9. Calculation of free energy barriers to the fusion of small vesicles.

    PubMed

    Lee, J Y; Schick, M

    2008-03-01

    The fusion of small vesicles, either with a planar bilayer or with one another, is studied using a microscopic model in which the bilayers are composed of hexagonal- and lamellar-forming amphiphiles. The free energy of the system is obtained within the self-consistent field approximation. We find that the free energy barrier to form the initial stalk is hardly affected by the radius of the vesicle, but that the barrier to expand the hemifusion diaphragm and form a fusion pore decreases rapidly as the radius decreases. As a consequence, once the initial barrier to stalk formation is overcome, one which we estimate at 13 k(B)T for biological membranes, fusion involving small vesicles should proceed with little or no further input of energy.

  10. Numerical determination of the interfacial energy and nucleation barrier of curved solid-liquid interfaces in binary systems

    NASA Astrophysics Data System (ADS)

    Kundin, Julia; Choudhary, Muhammad Ajmal

    2016-07-01

    The phase-field crystal (PFC) technique is a widely used approach for modeling crystal growth phenomena with atomistic resolution on mesoscopic time scales. We use a two-dimensional PFC model for a binary system based on the work of Elder et al. [Phys. Rev. B 75, 064107 (2007), 10.1103/PhysRevB.75.064107] to study the effect of the curved, diffuse solid-liquid interface on the interfacial energy as well as the nucleation barrier. The calculation of the interfacial energy and the nucleation barrier certainly depends on the proper definition of the solid-liquid dividing surface and the corresponding nucleus size. We define the position of the sharp interface at which the interfacial energy is to be evaluated by using the concept of equimolar dividing surface (re) and the minimization of the interfacial energy (rs). The comparison of the results based on both radii shows that the difference re-rs is always positive and has a limit for large cluster sizes which is comparable to the Tolman length. Furthermore, we found the real nucleation barrier for small cluster sizes, which is defined as a function of the radius rs, and compared it with the classical nucleation theory. The simulation results also show that the extracted interfacial energy as function of both radii is independent of system size, and this dependence can be reasonably described by the nonclassical Tolman formula with a positive Tolman length.

  11. The energy barrier at noble metal/TiO{sub 2} junctions

    SciTech Connect

    Hossein-Babaei, F. E-mail: fhbabaei@yahoo.com; Lajvardi, Mehdi M. Alaei-Sheini, Navid

    2015-02-23

    Nobel metal/TiO{sub 2} structures are used as catalysts in chemical reactors, active components in TiO{sub 2}-based electronic devices, and connections between such devices and the outside circuitry. Here, we investigate the energy barrier at the junctions between vacuum-deposited Ag, Au, and Pt thin films and TiO{sub 2} layers by recording their electrical current vs. voltage diagrams and spectra of optical responses. Deposited Au/, Pt/, and Ag/TiO{sub 2} behave like contacts with zero junction energy barriers, but the thermal annealing of the reverse-biased devices for an hour at 523 K in air converts them to Schottky diodes with high junction energy barriers, decreasing their reverse electric currents up to 10{sup 6} times. Similar thermal processing in vacuum or pure argon proved ineffective. The highest energy barrier and the lowest reverse current among the devices examined belong to the annealed Ag/TiO{sub 2} contacts. The observed electronic features are described based on the physicochemical parameters of the constituting materials. The formation of higher junction barriers with rutile than with anatase is demonstrated.

  12. Direct measurement of free-energy barrier to nucleation of crystallites in amorphous silicon thin films

    NASA Technical Reports Server (NTRS)

    Shi, Frank G.

    1994-01-01

    A method is introduced to measure the free-energy barrier W(sup *), the activation energy, and activation entropy to nucleation of crystallites in amorphous solids, independent of the energy barrier to growth. The method allows one to determine the temperature dependence of W(sup *), and the effect of the preparation conditions of the initial amorphous phase, the dopants, and the crystallization methds on W(sup *). The method is applied to determine the free-energy barrier to nucleation of crystallites in amorphous silicon (a-Si) thin films. For thermally induced nucleation in a-Si thin films with annealing temperatures in the range of from 824 to 983 K, the free-energy barrier W(sup *) to nucleation of silicon crystals is about 2.0 - 2.1 eV regardless of the preparation conditions of the films. The observation supports the idea that a-Si transforms into an intermediate amorphous state through the structural relaxation prior to the onset of nucleation of crystallites in a-Si. The observation also indicates that the activation entropy may be an insignificant part of the free-energy barrier for the nucleation of crystallites in a-Si. Compared with the free-energy barrier to nucleation of crystallites in undoped a-Si films, a significant reduction is observed in the free-energy barrier to nucleation in Cu-doped a-Si films. For a-Si under irradiation of Xe(2+) at 10(exp 5) eV, the free-energy barrier to ion-induced nucleation of crystallites is shown to be about half of the value associated with thermal-induced nucleation of crystallites in a-Si under the otherwise same conditions, which is much more significant than previously expected. The present method has a general kinetic basis; it thus should be equally applicable to nucleation of crystallites in any amorphous elemental semiconductors and semiconductor alloys, metallic and polymeric glasses, and to nucleation of crystallites in melts and solutions.

  13. Overcoming barriers to residential conservation: do energy audits help

    SciTech Connect

    Hoffman, W.L.

    1982-12-01

    A study on the effects of energy audits on the pace and choice of household investment in energy-saving improvements in the home is reported. An evaluation based on the household's assessment of the usefulness of the audit which was provided for their home was performed. The number and types of recent conservation actions among audited and unaudited samples of households are compared. The audit's effect on household knowledge about the economically attractive options for their home and on the choice of recent improvements is assessed. Possible reasons are suggested for the weak effect of audits in stimulating activity and reorienting investment choices. (LEW)

  14. Technical Barriers, Gaps, and Opportunities Related to Home Energy Upgrade Market Delivery

    SciTech Connect

    Bianchi, M. V. A.

    2011-11-01

    This report outlines the technical barriers, gaps, and opportunities that arise in executing home energy upgrade market delivery approaches, as identified through research conducted by the U.S. Department of Energy's Building America program. The objective of this report is to outline the technical1 barriers, gaps, and opportunities that arise in executing home energy upgrade market delivery approaches, as identified through research conducted by the U.S. Department of Energy's (DOE) Building America program. This information will be used to provide guidance for new research necessary to enable the success of the approaches. Investigation for this report was conducted via publications related to home energy upgrade market delivery approaches, and a series of interviews with subject matter experts (contractors, consultants, program managers, manufacturers, trade organization representatives, and real estate agents). These experts specified technical barriers and gaps, and offered suggestions for how the technical community might address them. The potential benefits of home energy upgrades are many and varied: reduced energy use and costs; improved comfort, durability, and safety; increased property value; and job creation. Nevertheless, home energy upgrades do not comprise a large part of the overall home improvement market. Residential energy efficiency is the most complex climate intervention option to deliver because the market failures are many and transaction costs are high (Climate Change Capital 2009). The key reasons that energy efficiency investment is not being delivered are: (1) The opportunity is highly fragmented; and (2) The energy efficiency assets are nonstatus, low-visibility investments that are not properly valued. There are significant barriers to mobilizing the investment in home energy upgrades, including the 'hassle factor' (the time and effort required to identify and secure improvement works), access to financing, and the opportunity cost of

  15. Elastic scattering of {sup 9}Li on {sup 208}Pb at energies around the Coulomb barrier

    SciTech Connect

    Cubero, M.; Fernandez-Garcia, J. P.; Alvarez, M. A. G.; Lay, J. A.; Moro, A. M.; Acosta, L.; Martel, I.; Sanchez-Benitez, A. M.; Alcorta, M.; Borge, M. J. G.; Tengblad, O.; Buchmann, L.; Shotter, A.; Walden, P.; Diget, D. G.; Fulton, B.; Fynbo, H. O. U.; Galaviz, D.; Gomez-Camacho, J.; Mukha, I.

    2011-10-28

    We have studied the dynamical effects of the halo structure of {sup 11}Li on the scattering on heavy targets at energies around the Coulomb barrier. This experiment was performed at ISAC-II at TRIUMF with a world record in production of the post-accelerated {sup 11}Li beam. As part of this study we report here on the first measurement of the elastic cross section of the core nucleus, i.e. {sup 9}Li on {sup 208}Pb, at energies around the Coulomb barrier. A preliminary optical model analysis has been performed in order to extract a global optical potential to describe the measured angular distributions.

  16. Fusion enhancement at near and sub-barrier energies in 19O + 12C

    NASA Astrophysics Data System (ADS)

    Singh, Varinderjit; Vadas, J.; Steinbach, T. K.; Wiggins, B. B.; Hudan, S.; deSouza, R. T.; Lin, Zidu; Horowitz, C. J.; Baby, L. T.; Kuvin, S. A.; Tripathi, Vandana; Wiedenhöver, I.; Umar, A. S.

    2017-02-01

    Measuring the fusion excitation function for an isotopic chain of projectile nuclei provides a stringent test of a microscopic description of fusion. We report the first measurement of the fusion excitation function at near-barrier energies for the 19O + 12C system. The measured excitation function is compared with the fusion excitation function of 18O + 12C. A significant enhancement in the fusion probability of 19O ions with a 12C target as compared to 18O ions is observed. The experimental cross-sections observed at near-barrier energies are compared with a state-of-the-art microscopic model.

  17. Energy Savings Certificate Markets: Opportunities and Implementation Barriers

    SciTech Connect

    Friedman, B.; Bird, L.; Barbose, G.

    2009-07-01

    Early experiences with energy savings certificates (ESCs) have revealed their merits and the challenges associated with them. While in the United States ESC markets have yet to gain significant traction, lessons can be drawn from early experiences in the states of Connecticut and New York, as well as from established markets in Italy, France, and elsewhere. The staying power of European examples demonstrates that ESCs can help initiate more efficiency projects. This article compares ESCs with renewable energy certificates (RECs), looks at the unique opportunities and challenges they present, and reviews solutions and best practices demonstrated by early ESC markets. Three major potential ESC market types are also reviewed: compliance, voluntary, and carbon. Additionally, factors that will benefit ESC markets in the United States are examined: new state EEPS policies, public interest in tools to mitigate climate change, and the growing interest in a voluntary market for ESCs.

  18. Analyzing Barriers to Energy Conservation in Residences and Offices: The Rewire Program at the University of Toronto

    ERIC Educational Resources Information Center

    Stokes, Leah C.; Mildenberger, Matto; Savan, Beth; Kolenda, Brian

    2012-01-01

    Conducting a barriers analysis is an important first step when designing proenvironmental behavior change interventions. Yet, detailed information on common barriers to energy conservation campaigns remains unavailable. Using a pair of original surveys, we leverage the theory of planned behavior to report on the most important barriers for…

  19. Analysis of the barriers to renewable energy development on tribal lands

    NASA Astrophysics Data System (ADS)

    Jones, Thomas Elisha

    Native American lands have significant renewable energy resource potential that could serve to ensure energy security and a low carbon energy future for the benefit of tribes as well as the United States. Economic and energy development needs in Native American communities match the energy potential. A disproportionate amount of Native American households have no access to electricity, which is correlated with high poverty and unemployment rates. Despite the vast resources and need for energy, the potential for renewable energy development has not fully materialized. This research explores this subject through three separate articles: 1) a case study of the Navajo Nation that suggests economic viability is not the only significant factor for low adoption of renewable energy on Navajo lands; 2) an expert elicitation of tribal renewable energy experts of what they view as barriers to renewable energy development on tribal lands; and 3) a reevaluation of Native Nation Building Theory to include external forces and the role that inter-tribal collaboration plays with renewable energy development by Native nations. Major findings from this research suggests that 1) many Native nations lack the technical and legal capacity to develop renewable energy; 2) inter-tribal collaboration can provide opportunities for sharing resources and building technical, legal, and political capacity; and 3) financing and funding remains a considerable barrier to renewable energy development on tribal lands.

  20. Ethnic differences in cancer symptom awareness and barriers to seeking medical help in England

    PubMed Central

    Niksic, Maja; Rachet, Bernard; Warburton, Fiona G; Forbes, Lindsay J L

    2016-01-01

    Background: Ethnic differences in cancer symptom awareness and barriers to seeking medical help in the English population are not fully understood. We aimed to quantify these differences, to help develop more effective health campaigns, tailored to the needs of different ethnic groups. Methods: Using a large national data set (n=38 492) of cross-sectional surveys that used the Cancer Research UK Cancer Awareness Measure, we examined how cancer symptom awareness and barriers varied by ethnicity, controlling for socio-economic position, age and gender. Data were analysed using multivariable logistic regression. Results: Awareness of cancer symptoms was lower in minority ethnic groups than White participants, with the lowest awareness observed among Bangladeshis and Black Africans. Ethnic minorities were more likely than White British to report barriers to help-seeking. South Asians reported the highest emotional barriers, such as lack of confidence to talk to the doctor, and practical barriers, such as worry about many other things. The Irish were more likely than the White British to report practical barriers, such as being too busy to visit a doctor. White British participants were more likely than any other ethnic group to report that they would feel worried about wasting the doctor's time. Overall, Black Africans had the lowest barriers. All differences were statistically significant (P<0.01 level), after controlling for confounders. Conclusions: Our findings suggest the need for culturally sensitive and targeted health campaigns, focused on improving recognition of cancer symptoms among ethnic minorities. Campaigns should tackle the specific barriers prevalent in each ethnic group. PMID:27280638

  1. Temperature-dependent hydration at micellar surface: activation energy barrier crossing model revisited.

    PubMed

    Mitra, Rajib Kumar; Sinha, Sudarson Sekhar; Pal, Samir Kumar

    2007-07-05

    In recent years, the validity of the activation energy barrier crossing model at the micellar surface brings notable controversy (Sen, P.; Mukherjee, S.; Halder, A.; Bhattacharyya, K. Chem. Phys. Lett. 2004, 385, 357-361. Kumbhakar, M.; Goel, T.; Mukherjee, T.; Pal, H. J. Phys. Chem. B 2004, 108, 19246-19254.) in the literature. In order to check the validity of the model by time-resolved solvation of a probe fluorophore, a wider range of temperature must be considered. At the same time, spatial heterogeneity (solubilization) of the probe and structural perturbation of the host micelle should carefully be avoided, which was not strictly maintained in the earlier studies. We report here the solvation dynamics of 4-(dicyanomethylene)-2-methyl-6(p-dimethylamino-styryl) 4H-pyran (DCM) in the SDS micelle at 298, 323, and 348 K. The probe DCM is completely insoluble in bulk water in this wide range of temperature. The size of the micelle at different temperatures using the dynamic light scattering (DLS) technique is found to have insignificant change. The hydration number of the micelle, determined by sound velocity measurements, decreases with increasing temperature. Time-resolved fluorescence anisotropy reveals the retention of the probe in the micellar interface within the temperature range. The average solvation time decreases with increasing temperature. The result of the solvation study has been analyzed in the light of energetics of bound to free water conversion at a constant size and decreasing hydration number at the micellar surface. The solvation process at the micellar surface has been found to be the activation energy barrier crossing type, in which interfacially bound type water molecules get converted into free type molecules. We have calculated Ea to be 3.5 kcal mol-1, which is in good agreement with that obtained by molecular dynamics simulation studies.

  2. SCC-DFTB Energy Barriers for Single and Double Proton Transfer Processes in the Model Molecular Systems Malonaldehyde and Porphycene

    SciTech Connect

    Walewski, L.; Krachtus, D; Fischer, S.; Smith, Jeremy C; Bala, P.; Lesyng, B.

    2005-09-01

    Self-consistent charge-density functional tight-binding SCC-DFTB is a computationally efficient method applicable to large (bio)molecular systems in which (bio)chemical reactions may occur. Among these reactions are proton transfer processes. This method, along with more advanced ab initio techniques, is applied in this study to compute intramolecular barriers for single and double proton transfer processes in the model systems, malonaldehyde and porphycene, respectively. SCC-DFTB is compared with experimental data and higher-level ab initio calculations. For malonaldehyde, the SCC-DFTB barrier height is 3.1 kcal/mol in vacuo and 4.2 kcal/mol in water solution. In the case of porphycene, the minimum energy pathways for double intramolecular proton transfer were determined using the conjugate peak refinement (CPR) method. Six isomers of porphycene were ordered according to energy. The only energetically allowed pathway was found to connect two symmetrical trans states via an unstable cis-A isomer. The SCC-DFTB barrier heights are 11.1 kcal/mol for the trans-cis-A process, and 7.4 kcal/mol for the reverse cis-A-trans one with the energy difference of 3.7 kcal/mol between the trans- and cis-A states. The method provides satisfactory energy results when compared with reference ab initio and experimental data.

  3. Lack of an energy policy remains a major barrier

    SciTech Connect

    Owen, D.

    1991-03-01

    This paper reports that the war with Iraq provided a new dimension to the ongoing oil industry struggle to cope with oppressive government action and regulation. Coming as it did just before the administration was to announce guidelines for a long-awaited National Energy Strategy (NES), the war created a renewed and dramatic focus on the national energy security question. Now, numerous congressmen, senators and administration leaders are taking a fresh look at how the U.S. can extricate itself from excessive dependence on Middle East oil imports. For example, the planned free-trade agreement with Mexico could figure prominently in an alliance that would bring much more Mexican oil to the U.S. Meanwhile, the wild card is proposals to open up U.S. drilling offshore and in the Arctic National Wildlife Region (ANWR). Prior to hostilities, Middle East tensions brought on significant increases in the price of oil, and with it a large gain in oil company profits for fourth-quarter 1990. Result: talk in Congress of a new windfall profits tax.

  4. State Successes: Using Outreach and Eduction to Transcend Barriers to Wind Energy (Poster)

    SciTech Connect

    Kelly, M.; Flowers, L.

    2010-05-01

    Many states projected to contribute significantly to the United States' 20% wind energy by 2030 goal have not yet achieved a first wind farm, and many more have not yet hit the 100-MW mark. These states are struggling with basic barriers of the need for understanding of the wind resource; wind energy benefits and impacts; economic development, water, and carbon impacts; issues such as transmission, utility integration, siting, and wildlife; involvement of key constituents such as the electrical sector, the ag sector, and county commissioners; effective policy; and an educated public and an educated workforce. Other states have partially transcended these barriers and are encountering organized pushback; NIMBYism; siting problems such as zoning, permitting, and environmental issues; and interstate barriers such as transmission.

  5. Facile Control of Interfacial Energy-Barrier Scattering in Antimony Telluride Electrodeposits

    NASA Astrophysics Data System (ADS)

    Kim, Jiwon; Jung, Hyunsung; Lim, Jae-Hong; Myung, Nosang V.

    2017-04-01

    The augmented thermoelectric performance of nanocrystalline antimony telluride (Sb2Te3) films is investigated by introducing interfacial energy-barrier scattering (i.e., barrier heights), which occurs at both the grain boundaries and the interfaces with embedded second phases. It is postulated that the barriers created at both the interfaces and boundaries filter the low-energy carriers, thus favoring a high Seebeck coefficient. A facile, but high-precision composition-controlled electrodeposition technique is employed to synthesize single-phase nanocrystalline Sb2Te3 and nanocomposite Te/Sb2Te3. Both the initial composition of the Sb-Te solid solution and the post-annealing profiles are varied to control the grain size, as well as the formation of second-phase Te. The electrical and thermoelectric properties are measured and correlated with the physical properties, where an enhanced Seebeck coefficient at a fixed carrier concentration is interpreted as indicating that the energy-dependent carrier filtering effect is in force. On a promising note, modification of the Sb2Te3 film physical properties and formation of the second phase affect the interfacial energy-barrier scattering and yields an enhanced power factor. Thus, Sb2Te3 film is a promising p-type thermoelectric material for a room-temperature-operational micro-thermoelectric power generator.

  6. Investigation of the hole resonant energies in GaAs-AlGaAs double-barrier

    NASA Astrophysics Data System (ADS)

    Sekkal, N.; Zitouni, K.; Kadri, A.

    1994-12-01

    A rigorous calculation of the resonant energies corresponding to valence sub-band hold transmission maxima is presented for GaAs/AlGaAs double-barrier heterostructures, employing the k.p method, the envelope-function approximation, and transfer matrix techniques. Incident waves associated with both the two light-hole and two heavy-hole bands are treated explicitly.

  7. Differences in psychiatric symptoms and barriers to mental health care between volunteer and career firefighters.

    PubMed

    Stanley, Ian H; Boffa, Joseph W; Hom, Melanie A; Kimbrel, Nathan A; Joiner, Thomas E

    2017-01-01

    Firefighters are at increased risk for mental health problems. However, little is known about differences in psychiatric symptoms between volunteer and career firefighters. This study aimed to (1) describe differences in psychiatric symptoms and barriers to mental health care between U.S. firefighters in volunteer-only and career-only departments; and (2) determine if greater self-reported structural barriers to mental health care (e.g., cost, availability of resources) explain the differences in psychiatric symptom levels. Overall, 525 current U.S. firefighters participated. Analyses of covariance and logistic regression analyses were used to evaluate group differences between volunteer (n=204) and career (n=321) firefighters, adjusting for demographic and occupational characteristics. Volunteer firefighters reported significantly elevated levels of depression, posttraumatic stress, and suicidal symptoms compared to career firefighters. Career firefighters reported relatively elevated levels of problematic alcohol use. Volunteer firefighters additionally reported greater structural barriers to mental health care (e.g., cost, availability of resources), and these barriers accounted for the differences in mental health variables between volunteer and career firefighters. Findings suggest that volunteer firefighters report elevated psychiatric symptoms compared to career firefighters and greater structural barriers to mental health treatment may explain this link. Increased efforts are needed to develop firefighter-specific interventions and bolster mental health service utilization.

  8. Origin of the Energy Barrier to Chemical Reactions of O2 on Al(111): Evidence for Charge Transfer, Not Spin Selection

    DTIC Science & Technology

    2012-11-08

    change of O2 spin, at the barrier [Fig. 3]; i.e., the corresponding diabatic surfaces cross. Far from the Al surface, the triplet state is...previous theoretical models, in particular nonadiabatic [17] or diabatic [16] approaches, which also find an energy barrier consistent with experiment...crossings of different diabatic O2 spin configuration sur- faces are accommodated by small spin fluctuations within the metal surface. For parallel

  9. Surface barrier height for different Al compositions and barrier layer thicknesses in AlGaN/GaN heterostructure field effect transistors

    SciTech Connect

    Goyal, Nitin Fjeldly, Tor A.; Iniguez, Benjamin

    2013-12-04

    In this paper, we present a physics based analytical model for the calculation of surface barrier height for given values of barrier layer thicknesses and Al mole fractions. An explicit expression for the two dimensional electron gas density is also developed incorporating the change in polarization charges for different Al mole fractions.

  10. Understanding {sup 6}He induced reactions at energies around the Coulomb barrier

    SciTech Connect

    Moro, A. M.; Arias, J. M.; Acosta, L.; Martel, I.; Sanchez-Benitez, A. M.; Borge, M. J. G.; Escrig, D.; Tengblad, O.; Gomez-Camacho, J.; Rodriguez-Gallardo, M.

    2009-06-03

    Recent developments aimed to understand the observed features arising in the scattering of the Borromean nucleus {sup 6}He on heavy targets are discussed and compared with recent data for {sup 6}He+{sup 208}Pb measured at the RIB facility at Louvain-la-Neuve at energies around the Coulomb barrier. The analysis of the elastic scattering data in terms of the optical model, reveals the presence of a long range absorption mechanism, that manifests in the form of a large value of the imaginary diffuseness parameter. The elastic data have been also compared with three--body CDCC calculations, based on a di-neutron model of {sup 6}He, and four--body CDCC calculations, based on a more realistic three-body model of this nucleus. Finally, the angular and energy distribution of {alpha} particles emitted at backward angles are discussed and compared with different theoretical approaches. We find that these {alpha} particles are produced mainly by a two-neutron transfer mechanism to very excited states in the residual nucleus.

  11. Perceived Barriers to Employment Success: Are There Differences between European American and African American VR Consumers?

    ERIC Educational Resources Information Center

    Zanskas, Stephen A.; Lustig, Daniel C.; Ishitani, Terry T.

    2011-01-01

    Purpose: The primary purpose of this study was to investigate whether there were differences between European and African American vocational rehabilitation consumers' perceptions of the barriers they experience towards obtaining employment. A secondary purpose was to determine whether there were differences in these perceptions based upon gender…

  12. Effects of intrinsic degrees of freedom in enhancement of sub-barrier fusion excitation function data and energy-dependent one-dimensional barrier penetration model

    NASA Astrophysics Data System (ADS)

    Gautam, M. S.

    2016-03-01

    We have analyzed the role of barrier modification effects (barrier height, barrier position, barrier curvature) introduced due to the energy-dependent Woods-Saxon potential model (EDWSP model) and the coupled channel model on the sub-barrier fusion dynamics of {}_{16}^{32,36} {{S}} + {}_{40}^{90,96} {{Zr}} reactions. The influence of inelastic surface excitations of colliding pairs and multi-neutron transfer channels is found to be a dominant mode of couplings. The coupling of relative motion of colliding nuclei to these dominant intrinsic degrees of freedom leads to a substantially large fusion enhancement at below-barrier energies over the expectations of one-dimensional barrier penetration model. The coupled channel calculations based upon static Woods-Saxon potential must include the internal nuclear structure degrees of freedom of colliding nuclei for complete description of experimental data. On the other hand, theoretical calculations based upon the EDWSP model along with Wong formula provide a complete description of sub-barrier fusion enhancement of various heavy-ion fusion reactions. In EDWSP model calculations, significantly larger values of diffuseness parameter ranging from a = 0.98 fm to a = 0.85 fm are required to address the observed sub-barrier fusion enhancement of {}_{16}^{32,36} {{S}} + {}_{40}^{90,96} {{Zr}} reactions. Furthermore, within the context of EDWSP model, it is possible to achieve an agreement with the experimental fusion cross-sectional data within 10 %. For four heavy-ion fusion reactions, only at 4 fusion data points out of 90 fusion data points deviates exceeding 5 %, while 86 fusion data points lie within 5 % and hence the EDWSP model is able to account the above-barrier portion of the fusion cross-sectional data within 5 % with a probability greater than 90 %.

  13. Direct measurement of energy barriers on rough and heterogeneous solid surfaces

    SciTech Connect

    Lloyd, T.B.; LaGow, J.; Connelly, G.M.

    1996-12-31

    This paper will deal with the phenomenon of energy barriers to the spread of liquids on solids. These barriers often manifest themselves as a {open_quotes}pinning{close_quotes} of a sessile drop as liquid is added to it. That is, the volume of the drop increases, but the diameter does not. Thus the advancing contact angle ({theta}{sub a}) increases to a maximum. At the point where the hydrostatic pressure in the drop overcomes the {open_quotes}pinning{close_quotes} force the diameter suddenly increases and the drop relaxes to a metastable configuration which has a lower {theta}{sub a}. Energy barriers should be considered in many applications such as the spreading of liquid adhesives where thorough wetting is the goal. The interfacial forces involved are both long-range Lifshitz-van der Waals (LW) forces and short-range acid-base (AB) forces. The authors will describe how they measure the energy barriers on real surfaces directly and resolve them into their LW and AB components.

  14. Investigation of Li6+Ni64 fusion at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Shaikh, Md. Moin; Roy, Subinit; Rajbanshi, S.; Pradhan, M. K.; Mukherjee, A.; Basu, P.; Pal, S.; Nanal, V.; Pillay, R. G.; Shrivastava, A.

    2014-08-01

    The total fusion (TF) excitation function for a Li6 projectile with a Ni64 target has been measured using the online characteristic γ ray detection method at energies around the Coulomb barrier. The complete fusion (CF) excitation function for the system is subsequently estimated from the dominating neutron evaporation channels with the help of statistical model predictions. The CF cross sections exhibit a suppression of about 13% compared to the one-dimensional barrier penetration model (1DBPM) at above-barrier energies, but no suppression is observed for TF cross sections. The observation does corroborate the estimated suppression for Li6 on Co59 target, but does not corroborate the recently proposed universal suppression factor for the Li6 projectile. The result supports the conjecture of reduced suppression of CF cross sections with decreasing target mass. At energies below the barrier, both the TF and the CF cross sections are enhanced. The observed enhancement of the CF process can be explained by channel coupling (CC), but the enhancement in TF cross sections is significantly higher than the CC predictions.

  15. Overcoming Codes and Standards Barriers to Innovations in Building Energy Efficiency

    SciTech Connect

    Cole, Pamala C.; Gilbride, Theresa L.

    2015-02-15

    In this journal article, the authors discuss approaches to overcoming building code barriers to energy-efficiency innovations in home construction. Building codes have been a highly motivational force for increasing the energy efficiency of new homes in the United States in recent years. But as quickly as the codes seem to be changing, new products are coming to the market at an even more rapid pace, sometimes offering approaches and construction techniques unthought of when the current code was first proposed, which might have been several years before its adoption by various jurisdictions. Due to this delay, the codes themselves can become barriers to innovations that might otherwise be helping to further increase the efficiency, comfort, health or durability of new homes. . The U.S. Department of Energy’s Building America, a program dedicated to improving the energy efficiency of America’s housing stock through research and education, is working with the U.S. housing industry through its research teams to help builders identify and remove code barriers to innovation in the home construction industry. The article addresses several approaches that builders use to achieve approval for innovative building techniques when code barriers appear to exist.

  16. Free energy barriers for homogeneous crystal nucleation in a eutectic system of binary hard spheres.

    PubMed

    Ganagalla, Srinivasa Rao; Punnathanam, Sudeep N

    2013-05-07

    In this study, the free energy barriers for homogeneous crystal nucleation in a system that exhibits a eutectic point are computed using Monte Carlo simulations. The system studied is a binary hard sphere mixture with a diameter ratio of 0.85 between the smaller and larger hard spheres. The simulations of crystal nucleation are performed for the entire range of fluid compositions. The free energy barrier is found to be the highest near the eutectic point and is nearly five times that for the pure fluid, which slows down the nucleation rate by a factor of 10(-31). These free energy barriers are some of highest ever computed using simulations. For most of the conditions studied, the composition of the critical nucleus corresponds to either one of the two thermodynamically stable solid phases. However, near the eutectic point, the nucleation barrier is lowest for the formation of the metastable random hexagonal closed packed (rhcp) solid phase with composition lying in the two-phase region of the phase diagram. The fluid to solid phase transition is hypothesized to proceed via formation of a metastable rhcp phase followed by a phase separation into respective stable fcc solid phases.

  17. The Analytical Parametrization of Fusion Barrier by Using the Skyrme Energy-Density Function Model

    NASA Astrophysics Data System (ADS)

    Zanganeh, V.; Mirzaei, M.; N., Wang

    2015-08-01

    Using the skyrme energy density formalism, a pocket formula is introduced for barrier heights and positions of 95 fusion reactions (48 ≤ ZP ZT ≤ 1520) with respect to the charge and mass numbers of the interacting nuclei. It is shown that the parameterized values of RB and VB are able to reproduce the corresponding experimental data with good accuracy. Moreover, the absolute errors of our formulas are less than those obtained using the analytical parametrization forms of the fusion barrier based on the proximity versions. The ability of the parameterized forms of the barrier heights and its positions to reproduce the experimental data of the fusion cross section have been analyzed using the Wong model.

  18. Opportunities and barriers for a crop-based energy sector in Ontario

    NASA Astrophysics Data System (ADS)

    Klupfel, Ellen Joanne

    This study investigates the existing opportunities and barriers for expanding the crop-based energy sector in Ontario. The investigation takes place at a time when growing concerns about sustainability---environmental, social, and economic---are encouraging the exploration of alternatives to energy systems based on fossil fuels, and concerns around the future viability of rural communities are making agriculturally-based and rural-based energy production systems attractive to many. To explore opportunities and barriers for the crop-based energy sector, this thesis addresses the question: What is the political-economic context within which the crop-based energy sector operates in Ontario? Taking an institutional approach, the study involved 26 interviews with individuals whose organizations influence Ontario's crop-based energy sector (that includes the biofuels ethanol and biodiesel), developed a model outlining relationships between the crop-based energy sector and other sectors of the economy, as well as the state, and implemented a survey of Ontario Members of Provincial Parliament's perspectives on biofuels. This research examines the balance of power of knowledge, production, security, finance, and technology for Ontario's crop-based energy sector. The overall balance of power currently rests with the petroleum sector. Through force field analysis, the study also identifies the key opportunities and barriers for the growth and development of the biofuels sector. These opportunities include climate change and rural development agendas, and the barriers include the petroleum sector, cost of production, and some sectors of the state. A few overarching conclusions emerge from this research: (1) Change in Ontario's crop-based energy sector is driven foremost by political and economic forces; (2) Climate change is the most significant driving force for the development and expansion of Ontario's crop-based energy sector; (3) Production cost and resistance from the

  19. Thermodynamics of downhill folding: multi-probe analysis of PDD, a protein that folds over a marginal free energy barrier.

    PubMed

    Naganathan, Athi N; Muñoz, Victor

    2014-07-31

    Downhill folding proteins fold in microseconds by crossing a very low or no free energy barrier (<3 RT), and exhibit a complex unfolding behavior in equilibrium. Such unfolding complexity is due to the weak thermodynamic coupling that exists between the various structural segments of these proteins, and it is manifested in unfolding curves that differ depending on the structural probe employed to monitor the process. Probe-dependent unfolding has important practical implications because it permits one to investigate the folding energy landscape in detail using multiprobe thermodynamic experiments. This type of thermodynamic behavior has been investigated in depth on the protein BBL, an example of extreme (one-state) downhill folding in which there is no free energy barrier at any condition, including the denaturation midpoint. However, an open question is, to what extent is such thermodynamic behavior observed on less extreme downhill folders? Here we perform a multiprobe spectroscopic characterization of the microsecond folder PDD, a structural and functional homologue of BBL that folds within the downhill regime, but is not an example of one-state downhill folding; rather at the denaturation midpoint PDD folds by crossing an incipient free energy barrier. Model-free analysis of the unfolding curves from four different spectroscopic probes together with differential scanning calorimetry reveals a dispersion of ∼9 K in the apparent melting temperature and also marked differences in unfolding broadness (from ∼50 to ∼130 kJ mol(-1) when analyzed with a two-state model), confirming that such properties are also observed on less extreme downhill folders. We subsequently perform a global quantitative analysis of the unfolding data of PDD using the same ME statistical mechanical model that was used before for the BBL domain. The analysis shows that this simple model captures all of the features observed on the unfolding of PDD (i.e., the intensity and temperature

  20. Calculating Transition Energy Barriers and Characterizing Activation States for Steps of Fusion

    PubMed Central

    Ryham, Rolf J.; Klotz, Thomas S.; Yao, Lihan; Cohen, Fredric S.

    2016-01-01

    We use continuum mechanics to calculate an entire least energy pathway of membrane fusion, from stalk formation, to pore creation, and through fusion pore enlargement. The model assumes that each structure in the pathway is axially symmetric. The static continuum stalk structure agrees quantitatively with experimental stalk architecture. Calculations show that in a stalk, the distal monolayer is stretched and the stored stretching energy is significantly less than the tilt energy of an unstretched distal monolayer. The string method is used to determine the energy of the transition barriers that separate intermediate states and the dynamics of two bilayers as they pass through them. Hemifusion requires a small amount of energy independently of lipid composition, while direct transition from a stalk to a fusion pore without a hemifusion intermediate is highly improbable. Hemifusion diaphragm expansion is spontaneous for distal monolayers containing at least two lipid components, given sufficiently negative diaphragm spontaneous curvature. Conversely, diaphragms formed from single-component distal monolayers do not expand without the continual injection of energy. We identify a diaphragm radius, below which central pore expansion is spontaneous. For larger diaphragms, prior studies have shown that pore expansion is not axisymmetric, and here our calculations supply an upper bound for the energy of the barrier against pore formation. The major energy-requiring deformations in the steps of fusion are: widening of a hydrophobic fissure in bilayers for stalk formation, splay within the expanding hemifusion diaphragm, and fissure widening initiating pore formation in a hemifusion diaphragm. PMID:26958888

  1. Calculating Transition Energy Barriers and Characterizing Activation States for Steps of Fusion.

    PubMed

    Ryham, Rolf J; Klotz, Thomas S; Yao, Lihan; Cohen, Fredric S

    2016-03-08

    We use continuum mechanics to calculate an entire least energy pathway of membrane fusion, from stalk formation, to pore creation, and through fusion pore enlargement. The model assumes that each structure in the pathway is axially symmetric. The static continuum stalk structure agrees quantitatively with experimental stalk architecture. Calculations show that in a stalk, the distal monolayer is stretched and the stored stretching energy is significantly less than the tilt energy of an unstretched distal monolayer. The string method is used to determine the energy of the transition barriers that separate intermediate states and the dynamics of two bilayers as they pass through them. Hemifusion requires a small amount of energy independently of lipid composition, while direct transition from a stalk to a fusion pore without a hemifusion intermediate is highly improbable. Hemifusion diaphragm expansion is spontaneous for distal monolayers containing at least two lipid components, given sufficiently negative diaphragm spontaneous curvature. Conversely, diaphragms formed from single-component distal monolayers do not expand without the continual injection of energy. We identify a diaphragm radius, below which central pore expansion is spontaneous. For larger diaphragms, prior studies have shown that pore expansion is not axisymmetric, and here our calculations supply an upper bound for the energy of the barrier against pore formation. The major energy-requiring deformations in the steps of fusion are: widening of a hydrophobic fissure in bilayers for stalk formation, splay within the expanding hemifusion diaphragm, and fissure widening initiating pore formation in a hemifusion diaphragm.

  2. Binding Energy and Dissociation Barrier: Experimental Determination of the Key Parameters of the Potential Energy Curve of Diethyl Ether on Si(001).

    PubMed

    Reutzel, Marcel; Lipponer, Marcus; Dürr, Michael; Höfer, Ulrich

    2015-10-01

    The key parameters of the potential energy curve of organic molecules on semiconductor surfaces, binding energy of the intermediate state and dissociation barrier, were experimentally investigated for the model system of diethyl ether (Et2O) on Si(001). Et2O adsorbs via a datively bonded intermediate from which it converts via ether cleavage into a covalently attached final state. This thermally activated conversion into the final state was followed in real-time by means of optical second-harmonic generation (SHG) at different temperatures and the associated energy barrier ϵa = 0.38 ± 0.05 eV and pre-exponential factor νa = 10(4±1) s(-1) were determined. From molecular beam experiments on the initial sticking probability, the difference between the desorption energy ϵd and ϵa was extracted and thus the binding energy of the intermediate state was determined (0.62 ± 0.08 eV). The results are discussed in terms of general chemical trends as well as with respect to a wider applicability on adsorbate reactions on semiconductor surfaces.

  3. Elastic scattering of 17O ions from 58Ni at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Torresi, D.; Strano, E.; Mazzocco, M.; Boiano, A.; Boiano, C.; Di Meo, P.; Guglielmetti, A.; La Commara, M.; Manea, C.; Nicoletto, M.; Parascandolo, C.; Parascandolo, L.; Pierroutsakou, D.; Sandoli, M.; Signorini, C.; Soramel, F.; Toniolo, N.; Grebosz, J.; Filipescu, D.; Gheorghe, A.; Glodariu, T.; Stroe, L.; Miyatake, H.; Watanabe, Y.; Jeong, S.; Kim, Y. H.; Pakou, A.; Sgouros, O.; Soukeras, V.; Zerva, K.

    2014-03-01

    Elastic scattering has been studied for the collisions induced by 17O on 58Ni target at energies around and above the Coulomb barrier. The elastic scattering angular distributions were measured for several energies and were analyzed within the framework of the optical model to obtain total reaction cross sections. The reaction cross-sections of the tightly bound 17O were compared with those of weakly bound 17F on the same targets in order to investigate the effects of the low binding energy in the reaction dynamics.

  4. Inequalities in cancer screening participation: examining differences in perceived benefits and barriers

    PubMed Central

    McGregor, L.M.; Raine, R.; Wardle, J.; von Wagner, C.; Robb, K.A.

    2016-01-01

    Abstract Objective Inequalities exist in colorectal cancer (CRC) screening uptake, with people from lower socioeconomic status backgrounds less likely to participate. Identifying the facilitators and barriers to screening uptake is important to addressing screening disparities. We pooled data from 2 trials to examine educational differences in psychological constructs related to guaiac fecal occult blood testing. Methods Patients (n = 8576) registered at 7 general practices in England, within 15 years of the eligible age range for screening (45‐59.5 years), were invited to complete a questionnaire. Measures included perceived barriers (emotional and practical) and benefits of screening, screening intentions, and participant characteristics including education. Results After data pooling, 2181 responses were included. People with high school education or no formal education reported higher emotional and practical barriers and were less likely to definitely intend to participate in screening, compared with university graduates in analyses controlling for study arm and participant characteristics. The belief that one would worry more about CRC after screening and concerns about tempting fate were strongly negatively associated with education. In a model including education and participant characteristics, respondents with low emotional barriers, low practical barriers, and high perceived benefits were more likely to definitely intend to take part in screening. Conclusions In this analysis of adults approaching the CRC screening age, there was a consistent effect of education on perceived barriers toward guaiac fecal occult blood testing, which could affect screening decision making. Interventions should target specific barriers to reduce educational disparities in screening uptake and avoid exacerbating inequalities in CRC mortality. PMID:27309861

  5. Numerical Modelling of a Low-Energy Rockfall Barrier: New Insight into the Bullet Effect

    NASA Astrophysics Data System (ADS)

    Mentani, A.; Giacomini, A.; Buzzi, O.; Govoni, L.; Gottardi, G.; Fityus, S.

    2016-04-01

    This paper investigates the dynamic response of low energy, semi-rigid rockfall barriers. The study is based on a FE model that reproduces the geometry, components and connections of the existing systems that were previously tested at The University of Newcastle. The mechanical behaviour of the relevant barrier components was calibrated from simple mechanical tests and the response of the assembled system, i.e. 2 m high, 15 m long rockfall barrier, was validated against of full-scale tests results. Following a satisfactory validation of the model, further dynamic non-linear analyses were conducted to investigate the dependence of the full system performance to the size of impacting blocks. Interestingly, the total failure energy was found to evolve non-monotonically with block size because of dynamic effects that seem to prevail for impact speeds in the range of 15-20 m/s. The study also highlights the complex effects of adding intermediate longitudinal cables to the system. An improvement of the barrier performance is observed for the large blocks but the bullet effect is exacerbated for small blocks.

  6. Random free energy barrier hopping model for ac conduction in chalcogenide glasses

    NASA Astrophysics Data System (ADS)

    Murti, Ram; Tripathi, S. K.; Goyal, Navdeep; Prakash, Satya

    2016-03-01

    The random free energy barrier hopping model is proposed to explain the ac conductivity (σac) of chalcogenide glasses. The Coulomb correlation is consistently accounted for in the polarizability and defect distribution functions and the relaxation time is augmented to include the overlapping of hopping particle wave functions. It is observed that ac and dc conduction in chalcogenides are due to same mechanism and Meyer-Neldel (MN) rule is the consequence of temperature dependence of hopping barriers. The exponential parameter s is calculated and it is found that s is subjected to sample preparation and measurement conditions and its value can be less than or greater than one. The calculated results for a - Se, As2S3, As2Se3 and As2Te3 are found in close agreement with the experimental data. The bipolaron and single polaron hopping contributions dominates at lower and higher temperatures respectively and in addition to high energy optical phonons, low energy optical and high energy acoustic phonons also contribute to the hopping process. The variations of hopping distance with temperature is also studied. The estimated defect number density and static barrier heights are compared with other existing calculations.

  7. Critical energy barrier for capillary condensation in mesopores: Hysteresis and reversibility

    NASA Astrophysics Data System (ADS)

    Hiratsuka, Tatsumasa; Tanaka, Hideki; Miyahara, Minoru T.

    2016-04-01

    Capillary condensation in the regime of developing hysteresis occurs at a vapor pressure, Pcond, that is less than that of the vapor-like spinodal. This is because the energy barrier for the vapor-liquid transition from a metastable state at Pcond becomes equal to the energy fluctuation of the system; however, a detailed mechanism of the spontaneous transition has not been acquired even through extensive experimental and simulation studies. We therefore construct accurate atomistic silica mesopore models for MCM-41 and perform molecular simulations (gauge cell Monte Carlo and grand canonical Monte Carlo) for argon adsorption on the models at subcritical temperatures. A careful comparison between the simulation and experiment reveals that the energy barrier for the capillary condensation has a critical dimensionless value, Wc* = 0.175, which corresponds to the thermal fluctuation of the system and depends neither on the mesopore size nor on the temperature. We show that the critical energy barrier Wc* controls the capillary condensation pressure Pcond and also determines a boundary between the reversible condensation/evaporation regime and the developing hysteresis regime.

  8. Critical energy barrier for capillary condensation in mesopores: Hysteresis and reversibility.

    PubMed

    Hiratsuka, Tatsumasa; Tanaka, Hideki; Miyahara, Minoru T

    2016-04-28

    Capillary condensation in the regime of developing hysteresis occurs at a vapor pressure, Pcond, that is less than that of the vapor-like spinodal. This is because the energy barrier for the vapor-liquid transition from a metastable state at Pcond becomes equal to the energy fluctuation of the system; however, a detailed mechanism of the spontaneous transition has not been acquired even through extensive experimental and simulation studies. We therefore construct accurate atomistic silica mesopore models for MCM-41 and perform molecular simulations (gauge cell Monte Carlo and grand canonical Monte Carlo) for argon adsorption on the models at subcritical temperatures. A careful comparison between the simulation and experiment reveals that the energy barrier for the capillary condensation has a critical dimensionless value, Wc (*) = 0.175, which corresponds to the thermal fluctuation of the system and depends neither on the mesopore size nor on the temperature. We show that the critical energy barrier Wc (*) controls the capillary condensation pressure Pcond and also determines a boundary between the reversible condensation/evaporation regime and the developing hysteresis regime.

  9. Do Perceived Cues, Benefits, and Barriers to Physical Activity Differ between Male and Female Adolescents?

    ERIC Educational Resources Information Center

    Tergerson, Jennifer L.; King, Keith A.

    2002-01-01

    Surveyed adolescents at single-sex high schools to examine whether perceptions of physical activity differed by gender. The most helpful cue to physical activity for males and females was having a friend to exercise with. Parental encouragement and having a parent who exercised were also helpful. Wanting to do other things was a common barrier to…

  10. Gender Differences in the Perceived Needs and Barriers of Youth Offenders Preparing for Community Reentry

    ERIC Educational Resources Information Center

    Fields, Diane; Abrams, Laura S.

    2010-01-01

    This study explored how gender differences may influence the community reentry experiences of incarcerated youth. Structured surveys assessing risk factors for re-offending, perceived reentry needs, and anticipated barriers to meeting these needs were administered to a convenience sample of males (n = 36) and females (n = 35) who were within 60…

  11. Fine-tuning terminal solvent ligands to rationally enhance the energy barrier in dinuclear dysprosium single-molecule magnets.

    PubMed

    Zhang, Kun; Yuan, Chen; Guo, Fu-Sheng; Zhang, Yi-Quan; Wang, Yao-Yu

    2016-12-20

    In search of simple approaches to rationally enhance the energy barriers in polynuclear dysprosium single-molecule magnets, a new system containing two structurally closely related dinuclear dysprosium complexes, namely [Dy2(L)2(DBM)2(DMF)2] (1) and [Dy2(L)2(DBM)2(DMA)2]·2DMA (2) (HDBM = dibenzoylmethane, H2L = 2-hydroxy-N'-(2-hydroxy-3-methoxybenzylidene)benzohydrazide), is introduced and the structure-dependent magnetic properties are investigated. The two complexes display only slight variations in the coordination geometries of the Dy(iii) ion but display remarkably different magnetic behaviors. By replacing the DMF (dimethylformamide) ligand in complex 1 with DMA (dimethylacetamide) in 2 while retaining the same coordination atoms, we were able to create a 3-fold enhancement in the energy barrier, from 24 K for complex 1 to 77 K for complex 2. Complete-active-space self-consistent field (CASSCF) calculations revealed that the charge distribution surrounding the Dy(iii) centers in 1 and 2 is the key factor in determining the relaxation properties of the SMMs. The introduction of an electron-donating CH3 group in DMA to replace the hydrogen in DMF resulted in a larger average charge along the magnetic axes of complex 2 compared to complex 1, which resulted in a stronger easy-axis ligand field, thus increasing the energy difference between the ground and the first excited states of complex 2. This work presents a simple method to rationally enhance the energy barrier in polynuclear lanthanide SMMs through fine-tuning of the electrostatic potential of the atoms along the magnetic axis.

  12. Nucleon exchange mechanism in heavy-ion collisions at near-barrier energies

    SciTech Connect

    Yilmaz, B.; Ayik, S.; Lacroix, D.

    2011-06-15

    Nucleon drift and diffusion mechanisms in central collisions of asymmetric heavy ions at near-barrier energies are investigated in the framework of a stochastic mean-field approach. Expressions for diffusion and drift coefficients for nucleon transfer deduced from the stochastic mean-field approach in the semiclassical approximation have similar forms familiar from the phenomenological nucleon exchange model. The variance of fragment mass distribution agrees with the empirical formula {sigma}{sub AA}{sup 2}(t)=N{sub exc}(t). The comparison with the time-dependent Hartree-Fock calculations shows that below barrier energies, the drift coefficient in the semiclassical approximation underestimates the mean number of nucleon transfer obtained in the quantal framework. Motion of the window in the dinuclear system has a significant effect on the nucleon transfer in asymmetric collisions.

  13. Observation of the one- to six-neutron transfer reactions at sub-barrier energies

    SciTech Connect

    Jiang, C.L.; Rehm, K.E.; Gehring, J.

    1995-08-01

    It was suggested many years ago that when two heavy nuclei are in contact during a grazing collision, the transfer of several correlated neutron-pairs could occur. Despite considerable experimental effort, however, so far only cross sections for up to four-neutron transfers have been uniquely identified. The main difficulties in the study of multi-neutron transfer reactions are the small cross sections encountered at incident energies close to the barrier, and various experimental uncertainties which can complicate the analysis of these reactions. We have for the first time found evidence for multi-neutron transfer reactions covering the full sequence from one- to six-neutron transfer reactions at sub-barrier energies in the system {sup 58}Ni + {sup 100}Mo.

  14. Formation of hyperdeformed states in capture reactions at sub-barrier energies

    SciTech Connect

    Zubov, A. S.; Antonenko, N. V.; Sargsyan, V. V.; Adamian, G. G.; Scheid, W.

    2010-09-15

    The high-spin hyperdeformed nuclear states treated as dinuclear or quasimolecular configurations are suggested to be directly populated in heavy ion collisions at sub-barrier energies. Tunneling through the Coulomb barrier is considered using the quantum diffusion approach based on the formalism of reduced density matrix. The reactions {sup 48}Ca+{sup 86}Kr,{sup 124}Sn,{sup 136}Xe,{sup 138}Ba,{sup 140}Ce, {sup 58}Ni+{sup 58}Ni, and {sup 40,48}Ca+{sup 40,48}Ca, are suggested for populating high-spin hyperdeformed states. The partial production and identification cross sections for the hyperdeformed states are calculated as the functions of bombarding energy.

  15. Barriers to Incorporating Climate Change Science into High School and Community College Energy Course Offerings

    NASA Astrophysics Data System (ADS)

    Howell, C.

    2013-05-01

    In reviewing studies evaluating trends in greenhouse gasses, weather, climate and/or ecosystems, it becomes apparent that climate change is a reality. It has also become evident that the energy sector accounts for most of the greenhouse gas emissions with worldwide emissions of carbon dioxide increasing by 31 percent from 1990 to 2005, higher than in the previous thousands of years. While energy courses and topics are presented in high school and community college classes the topic of Climate Change Science is not always a part of the conversation. During the summer of 2011 and 2012, research undergraduates conducted interviews with a total of 39 national community college and 8 high school instructors who participated in a two week Sustainable Energy Education Training (SEET) workshop. Interview questions addressed the barriers and opportunities to the incorporation of climate change as a dimension of an energy/renewable energy curriculum. Barriers found included: there is not enough instruction time to include it; some school administrators including community members do not recognize climate change issues; quality information about climate change geared to students is difficult to find; and, most climate change information is too scientific for most audiences. A Solution to some barriers included dialogue on sustainability as a common ground in recognizing environmental changes/concerns among educators, administrators and community members. Sustainability discussions are already supported in school business courses as well as in technical education. In conclusion, we cannot expect climate change to dissipate without humans making more informed energy and environmental choices. With global population growth producing greater emissions resulting in increased climate change, we must include the topic of climate change to students in high school and community college classrooms, preparing our next generation of leaders and workforce to be equipped to find solutions

  16. Influence of porous media structure in colloid retention in the absence of an energy barrier

    NASA Astrophysics Data System (ADS)

    Pazmino, E. F.; Johnson, W. P.; Ma, H.

    2010-12-01

    Many colloid transport experiments have been conducted in a porous media with narrow size distribution, which allows a single collector size to be used in filtration theory to predict deposition rates. In this work, deposition of colloids (ranging from 0.21 μm to 9.1 μm) in packed columns is examined in the absence of an energy barrier with three different glass bead porous media: uniform mono-dispersed, mono-modal poly-dispersed and bimodal poly-dispersed. The corresponding porosities to these media are 0.378, 0.339 and 0.282. The effect of gravitational settling on deposition is studied by injecting the particles co-current and counter-current with gravity, especially for larger size colloids. Also, direct observations are conducted in a flow cell for selected colloid sizes for a better understanding of the mechanisms of attachment. Experimental results are compared with theoretical predictions to determine characteristic collector sizes that represent poly-dispersed porous media in filtration theory.

  17. The fusion of membranes and vesicles: pathway and energy barriers from dissipative particle dynamics.

    PubMed

    Grafmüller, Andrea; Shillcock, Julian; Lipowsky, Reinhard

    2009-04-08

    The fusion of lipid bilayers is studied with dissipative particle dynamics simulations. First, to achieve control over membrane properties, the effects of individual simulation parameters are studied and optimized. Then, a large number of fusion events for a vesicle and a planar bilayer are simulated using the optimized parameter set. In the observed fusion pathway, configurations of individual lipids play an important role. Fusion starts with individual lipids assuming a splayed tail configuration with one tail inserted in each membrane. To determine the corresponding energy barrier, we measure the average work for interbilayer flips of a lipid tail, i.e., the average work to displace one lipid tail from one bilayer to the other. This energy barrier is found to depend strongly on a certain dissipative particle dynamics parameter, and, thus, can be adjusted in the simulations. Overall, three subprocesses have been identified in the fusion pathway. Their energy barriers are estimated to lie in the range 8-15 k(B)T. The fusion probability is found to possess a maximum at intermediate tension values. As one decreases the tension, the fusion probability seems to vanish before the tensionless membrane state is attained. This would imply that the tension has to exceed a certain threshold value to induce fusion.

  18. Sub-barrier fusion excitation function data and energy dependent Woods-Saxon potential

    NASA Astrophysics Data System (ADS)

    Gautam, Manjeet Singh

    2016-07-01

    This paper analyzed the role of intrinsic degrees of freedom of colliding nuclei in the enhancement of sub-barrier fusion cross-section data of various heavy ion fusion reactions. The influences of inelastic surface vibrations of colliding pairs are found to be dominant and their couplings result in the significantly larger fusion enhancement over the predictions of the one dimensional barrier penetration model at sub-barrier energies. The theoretical calculations are performed by using energy dependent Woods-Saxon potential model (EDWSP model) in conjunction with the one dimensional Wong formula. The effects of dominant intrinsic channels are entertained within framework of the coupled channel calculations obtained by using the code CCFULL. It is quite interesting to note that the energy dependence in Woods-Saxon potential simulates the effects of inelastic surface vibrational states of reactants wherein significantly larger value of diffuseness parameter ranging from a = 0.85 fm to a = 0.95 fm is required to address the observed fusion excitation function data of the various heavy ion fusion reactions.

  19. Barriers on the propagation of renewable energy sources and sustainable solid waste management practices in Greece.

    PubMed

    Boemi, Sn; Papadopoulos, Am; Karagiannidis, A; Kontogianni, S

    2010-11-01

    Renewable energy sources (RES), excluding large hydroelectric plants, currently produce 4.21% of total electricity production in Greece. Even when considering the additional production from large hydroelectric plants, which accounts for some 7.8%, the distance to be covered towards the objective of 20% electricity produced from RES by 2010 and respectively towards 20% of total energy production by 2020 is discouraging. The potential, however, does exist; unfortunately so do serious barriers. On the other hand, solid waste management (SWM) is an issue that generates continuously increasing interest due to the extra amounts of solid waste generated; the lack of existing disposal facilities with adequate infrastructure and integrated management plans, also often accompanied by legislative and institutional gaps. However, socio-economic and public awareness problems are still met in the planning and implementation of RES and SWM projects, together with the lack of a complete national cadastre and a spatial development master plan, specifying areas eligible for RES and SWM development. Specific barriers occur for individual RES and the on-going inclusion of waste-derived renewable energy in the examined palette further increases the complexity of the entire issue. The consolidated study of this broad set of barriers was a main task of the present study which was carried out within the frame of a Hellenic-Canadian research project; the main results will be discussed herein.

  20. Effect of bleaching agents on sealing properties of different intraorifice barriers and root filling materials

    PubMed Central

    Canoglu, Ebru; Gulsahi, Kamran; Sahin, Cem; Altundasar, Emre

    2012-01-01

    Objective: To evaluate the effect of intracoronal bleaching agents on the sealing properties of different intraorifice barriers and root filling materials. Study Design: The root canals of extracted human premolars (n=180) were prepared by using System GT rotary files and filled with either gutta-percha+AH Plus or Resilon+Epiphany sealer. In both groups, the coronal 3mm of root filling was removed and replaced with one of the following materials applied as intraorifice barriers (n=30/group): 1. ProProot-MTA; 2. Conventional Glass ionomer cement; and 3. Hybrid resin composite. In each subgroup, intracoronal bleaching was performed using either sodium perborate with distilled water or 35% hydrogen peroxide gel for 3 weeks. The leakage of specimens was measured using fluid-filtration and dye penetration tests. The data were analyzed statistically with One-way ANOVA, Repeated Measures t-test and Independent Samples t-test (p=0.05). Results: The fluid conductance values of the test groups were not influenced by the type of the bleaching agent, the intraorifice barrier, or the root filling material (all p>0.05). However, the extent of dye leakage was significantly affected by the type of intraorifice barrier material (p<0.05), which showed the following statistical ranking: glass ionomer cement > resin composite > ProRoot-MTA (p<0.05). Conclusions: The effect of 35% hydrogen peroxide gel or sodium perborate/distilled water on the sealing properties of tested intraorifice barriers and root filling materials varied conforming leakage assessment. These properties were not affected by using fluid filtration test, while the glass ionomer barrier showed the greatest amount of dye leakage in both gutta-percha and Resilon root-filled teeth. Key words:Tooth Bleaching, root canal filling materials, glass ionomer cement, mineral trioxide aggregate, micro leakage PMID:22322509

  1. Tunnel spin polarization versus energy for clean and doped Al2O3 barriers.

    PubMed

    Park, B G; Banerjee, T; Lodder, J C; Jansen, R

    2007-11-23

    The variation of the tunnel spin-polarization (TSP) with energy is determined using a magnetic tunnel transistor, allowing quantification of the energy dependent TSP separately for both ferromagnet/insulator interfaces and direct correlation with the tunnel magnetoresistance (TMR) measured in the same device. The intrinsic TSP is reduced below the Fermi level, and more strongly so for tunneling into empty states above the Fermi level. For artificially doped barriers, the low bias TMR decreases due to defect-assisted tunneling. Yet, this mechanism becomes ineffective at large bias, where instead inelastic spin scattering causes a strong TMR decay.

  2. [Study on Spectral Characteristics of Micro Plasma Channels of Different Gas-Gap in Dielectric Barrier Discharge].

    PubMed

    Gao, Ye-nan; Dong, Li-fang; Liu, Ying

    2015-10-01

    By optical emission spectrum, we report on the first investigation on the plasma parameters of micro plasma channels which are generated in two gas-gaps with different thickness in a triple-layer dielectric barrier discharge system. Different from the micro plasma channels formed in traditional two-layer dielectric barrier discharge, micro plasma channels formed in the triple-layer dielectric barrier discharge system reflect a unique discharge characteristic. From the pattern images taken by an ordinary camera, it shows that micro plasma channels generated in two discharge gas-gaps discharge with different sizes and light intensities. The micro plasma channels in wide gas-gap are much bigger than those in narrow gas-gap, and their light intensities are obvious stronger. By collecting the emission spectra of N2 second positive band (C3∏u --> B3∏g ) and calculating the relative intensity ratio method of N2 molecular ion line at 391.4 and the N2 molecular line at 394.1, the molecular vibration temperature and the average electron energy of micro plasma channels in two gas-gaps as functions of Argon concentration and applied voltage are investigated, respectively. It is found that the molecular vibration temperature and the average electron energy of micro plasma channels in wide gas-gap are lower than those in narrow gas-gap, and they both decrease with the increasing of the Argon concentration. As the applied voltage increases, micro plasma channels in wide gas-gap vary in a small range on the above two plasma investigations, while those in narrow gas-gap vary obviously. It indicates that micro plasma channels in narrow gas-gap are more sensitive to the applied voltage and they have a wider variation range of electric field than those in wide gas-gap.

  3. Final report. Renewable energy and energy efficiency in Mexico: Barriers and opportunities

    SciTech Connect

    Ashford, Mike

    2000-09-28

    The report describes the prospects for energy efficiency and greenhouse gas emissions reductions in Mexico, along with renewable energy potential. A methodology for developing emissions baselines is shown, in order to prepare project emissions reductions calculations. An application to the USIJI program was also prepared through this project, for a portfolio of energy efficiency projects.

  4. Field Study and Energy-Plus Benchmarks for Energy Saver Homes having Different Envelope Designs

    SciTech Connect

    Shrestha, Som S; Childs, Kenneth W; Stannard, Eric E

    2012-01-01

    An alliance to maximize energy efficiency and cost-effective residential construction (ZEBRAlliance) built and field tested four homes that are 50 percent more energy efficient than a code compliant home. The homes are unoccupied for the duration of a two-year field study, thereby eliminating the confounding issue of occupancy habits. All homes have about the same consistent and scheduled internal load. Each home showcases a unique envelope strategy: 1) structural insulated panel (SIP), 2) optimal value wall framing (OVF), 3) advanced framing featuring the benefits of insulations mixed with phase change materials (PCM), and 4) an exterior insulation and finish system (EIFS). All homes have different weather resistive barriers (WRBs) and/or air barriers to limit air and moisture infiltration. Three homes provide space conditioning and water heating via a ground loop heat exchanger, while the fourth home uses a high efficiency air-to-air heat pump and heat pump water heater. Field performance and results of EnergyPlus V7.0 benchmarks were made for roof and attics as compared to cathedral design and for wall heat flows to validate models. The moisture content of the wall sheathing is shown to prove the protecting effectiveness of WRBs. Temperature distributions through insulations in the wall and ceiling with and without PCMs are described to characterize the performance of the PCM building envelopes.

  5. Symmetric splitting for the system 32S+238U at energies near and below the barrier

    NASA Astrophysics Data System (ADS)

    Freifelder, R.; Braun-Munzinger, P.; Deyoung, P.; Schicker, R.; Sen, S.; Stachel, J.

    1987-06-01

    The total capture cross section for the system 32S+238U has been measured at energies from 0.93 to 1.08 times the s-wave interaction barrier by detecting coincident fission fragments following full momentum transfer reactions. The subbarrier cross section cannot be reproduced by a one-dimensional barrier penetration model. Using a quantum mechanical coupled channels model, good agreement is obtained. The measured angular distributions of fission fragments were compared to the predictions of saddle and scission point transition state theory. Saddle point transition state model calculations fail to reproduce the data, while scission point transition state calculations are in agreement with their qualitative trend. Evidence for nonequilibrium processes is presented.

  6. Evolution of fusion hindrance for asymmetric systems at deep sub-barrier energies

    NASA Astrophysics Data System (ADS)

    Shrivastava, A.; Mahata, K.; Pandit, S. K.; Nanal, V.; Ichikawa, T.; Hagino, K.; Navin, A.; Palshetkar, C. S.; Parkar, V. V.; Ramachandran, K.; Rout, P. C.; Kumar, Abhinav; Chatterjee, A.; Kailas, S.

    2016-04-01

    Measurements of fusion cross-sections of 7Li and 12C with 198Pt at deep sub-barrier energies are reported to unravel the role of the entrance channel in the occurrence of fusion hindrance. The onset of fusion hindrance has been clearly observed in 12C +198Pt system but not in 7Li +198Pt system, within the measured energy range. Emergence of the hindrance, moving from lighter (6,7Li) to heavier (12C, 16O) projectiles is explained employing a model that considers a gradual transition from a sudden to adiabatic regime at low energies. The model calculation reveals a weak effect of the damping of coupling to collective motion for the present systems as compared to that obtained for systems with heavier projectiles.

  7. Canonical free-energy barrier of particle and polymer cluster formation

    NASA Astrophysics Data System (ADS)

    Zierenberg, Johannes; Schierz, Philipp; Janke, Wolfhard

    2017-02-01

    A common approach to study nucleation rates is the estimation of free-energy barriers. This usually requires knowledge about the shape of the forming droplet, a task that becomes notoriously difficult in macromolecular setups starting with a proper definition of the cluster boundary. Here we demonstrate a shape-free determination of the free energy for temperature-driven cluster formation in particle as well as polymer systems. Combined with rigorous results on equilibrium droplet formation, this allows for a well-defined finite-size scaling analysis of the effective interfacial free energy at a fixed density. We first verify the theoretical predictions for the formation of a liquid droplet in a supersaturated particle gas by generalized-ensemble Monte Carlo simulations of a Lennard-Jones system. Going one step further, we then generalize this approach to cluster formation in a dilute polymer solution. Our results suggest an analogy with particle condensation, when the macromolecules are interpreted as extended particles.

  8. On the role of dynamical barriers in barrierless reactions at low energies: S(1D) + H2.

    PubMed

    Lara, Manuel; Jambrina, P G; Varandas, A J C; Launay, J-M; Aoiz, F J

    2011-10-07

    Reaction probabilities as a function of total angular momentum (opacity functions) and the resulting reaction cross sections for the collision of open shell S((1)D) atoms with para-hydrogen have been calculated in the kinetic energy range 0.09-10 meV (1-120 K). The quantum mechanical hyperspherical reactive scattering method and quasi-classical trajectory and statistical quasi-classical trajectory approaches were used. Two different ab initio potential energy surfaces (PESs) have been considered. The widely used reproducing kernel Hilbert space (RKHS) PES by Ho et al. [T.-S. Ho, T. Hollebeek, H. Rabitz, S. D. Chao, R. T. Skodje, A. S. Zyubin, and A. M. Mebel, J. Chem. Phys 116, 4124 (2002)] and the recently published accurate double many-body expansion (DMBE)/complete basis set (CBS) PES by Song and Varandas [Y. Z. Song and A. J. C. Varandas, J. Chem. Phys. 130, 134317 (2009)]. The calculations at low collision energies reveal very different dynamical behaviors on the two PESs. The reactivity on the RKHS PES is found to be considerably larger than that on the DMBE/CBS PES as a result of larger reaction probabilities at low total (here also orbital) angular momentum values and to opacity functions which extend to significantly larger total angular momentum values. The observed differences have their origin in two major distinct topographic features. Although both PESs are essentially barrierless for equilibrium H-H distances, when the H-H bond is compressed the DMBE/CBS PES gives rise to a dynamical barrier which limits the reactivity of the system. This barrier is completely absent in the RHKS PES. In addition, the latter PES exhibits a van der Walls well in the entrance channel which reduces the height of the centrifugal barrier and is able to support resonances. As a result, a significant larger cross section is found on this PES, with marked oscillations attributable to shape resonances and/or to the opening of partial wave contributions. The comparison of the

  9. A finite difference analysis of the field present behind an acoustically impenetrable two-layer barrier.

    PubMed

    Hurrell, Andrew M

    2008-06-01

    The interaction of an incident sound wave with an acoustically impenetrable two-layer barrier is considered. Of particular interest is the presence of several acoustic wave components in the shadow region of this barrier. A finite difference model capable of simulating this geometry is validated by comparison to the analytical solution for an idealized, hard-soft barrier. A panel comprising a high air-content closed cell foam backed with an elastic (metal) back plate is then examined. The insertion loss of this panel was found to exceed the dynamic range of the measurement system and was thus acoustically impenetrable. Experimental results from such a panel are shown to contain artifacts not present in the diffraction solution, when acoustic waves are incident upon the soft surface. A finite difference analysis of this experimental configuration replicates the presence of the additional field components. Furthermore, the simulated results allow the additional components to be identified as arising from the S(0) and A(0) Lamb modes traveling in the elastic plate. These Lamb mode artifacts are not found to be present in the shadow region when the acoustic waves are incident upon the elastic surface.

  10. pH-Regulated Mechanisms Account for Pigment-Type Differences in Epidermal Barrier Function

    PubMed Central

    Gunathilake, Roshan; Schurer, Nanna Y.; Shoo, Brenda A.; Celli, Anna; Hachem, Jean-Pierre; Crumrine, Debra; Sirimanna, Ganga; Feingold, Kenneth R.; Mauro, Theodora M.; Elias, Peter M.

    2009-01-01

    To determine whether pigment type determines differences in epidermal function, we studied stratum corneum (SC) pH, permeability barrier homeostasis, and SC integrity in three geographically disparate populations with pigment type I–II versus IV–V skin (Fitzpatrick I–VI scale). Type IV–V subjects showed: (i) lower surface pH (≈0.5 U); (ii) enhanced SC integrity (transepidermal water loss change with sequential tape strippings); and (iii) more rapid barrier recovery than type I–II subjects. Enhanced barrier function could be ascribed to increased epidermal lipid content, increased lamellar body production, and reduced acidity, leading to enhanced lipid processing. Compromised SC integrity in type I–II subjects could be ascribed to increased serine protease activity, resulting in accelerated desmoglein-1 (DSG-1)/corneodesmosome degradation. In contrast, DSG-1-positive CDs persisted in type IV–V subjects, but due to enhanced cathepsin-D activity, SC thickness did not increase. Adjustment of pH of type I–II SC to type IV–V levels improved epidermal function. Finally, dendrites from type IV–V melanocytes were more acidic than those from type I–II subjects, and they transfer more melanosomes to the SC, suggesting that melanosome secretion could contribute to the more acidic pH of type IV–V skin. These studies show marked pigment-type differences in epidermal structure and function that are pH driven. PMID:19177137

  11. Energy efficient engine, high pressure turbine thermal barrier coating. Support technology report

    NASA Technical Reports Server (NTRS)

    Duderstadt, E. C.; Agarwal, P.

    1983-01-01

    This report describes the work performed on a thermal barrier coating support technology task of the Energy Efficient Engine Component Development Program. A thermal barrier coating (TBC) system consisting of a Ni-Cr-Al-Y bond cost layer and ZrO2-Y2O3 ceramic layer was selected from eight candidate coating systems on the basis of laboratory tests. The selection was based on coating microstructure, crystallographic phase composition, tensile bond and bend test results, erosion and impact test results, furnace exposure, thermal cycle, and high velocity dynamic oxidation test results. Procedures were developed for applying the selected TBC to CF6-50, high pressure turbine blades and vanes. Coated HPT components were tested in three kinds of tests. Stage 1 blades were tested in a cascade cyclic test rig, Stage 2 blades were component high cycle fatigue tested to qualify thermal barrier coated blades for engine testing, and Stage 2 blades and Stage 1 and 2 vanes were run in factory engine tests. After completion of the 1000 cycle engine test, the TBC on the blades was in excellent condition over all of the platform and airfoil except at the leading edge above midspan on the suction side of the airfoil. The coating damage appeared to be caused by particle impingement; adjacent blades without TBC also showed evidence of particle impingement.

  12. Driven diffusion against electrostatic or effective energy barrier across α-hemolysin

    SciTech Connect

    Ansalone, Patrizio; Chinappi, Mauro; Rondoni, Lamberto; Cecconi, Fabio

    2015-10-21

    We analyze the translocation of a charged particle across an α-Hemolysin (αHL) pore in the framework of a driven diffusion over an extended energy barrier generated by the electrical charges of the αHL. A one-dimensional electrostatic potential is extracted from the full 3D solution of the Poisson’s equation. We characterize the particle transport under the action of a constant forcing by studying the statistics of the translocation time. We derive an analytical expression of translocation time average that compares well with the results from Brownian dynamic simulations of driven particles over the electrostatic potential. Moreover, we show that the translocation time distributions can be perfectly described by a simple theory which replaces the true barrier by an equivalent structureless square barrier. Remarkably, our approach maintains its accuracy also for low-applied voltage regimes where the usual inverse-Gaussian approximation fails. Finally, we discuss how the comparison between the simulated time distributions and their theoretical prediction results to be greatly simplified when using the notion of the empirical Laplace transform technique.

  13. Driven diffusion against electrostatic or effective energy barrier across α-hemolysin

    NASA Astrophysics Data System (ADS)

    Ansalone, Patrizio; Chinappi, Mauro; Rondoni, Lamberto; Cecconi, Fabio

    2015-10-01

    We analyze the translocation of a charged particle across an α-Hemolysin (αHL) pore in the framework of a driven diffusion over an extended energy barrier generated by the electrical charges of the αHL. A one-dimensional electrostatic potential is extracted from the full 3D solution of the Poisson's equation. We characterize the particle transport under the action of a constant forcing by studying the statistics of the translocation time. We derive an analytical expression of translocation time average that compares well with the results from Brownian dynamic simulations of driven particles over the electrostatic potential. Moreover, we show that the translocation time distributions can be perfectly described by a simple theory which replaces the true barrier by an equivalent structureless square barrier. Remarkably, our approach maintains its accuracy also for low-applied voltage regimes where the usual inverse-Gaussian approximation fails. Finally, we discuss how the comparison between the simulated time distributions and their theoretical prediction results to be greatly simplified when using the notion of the empirical Laplace transform technique.

  14. 7Be- and 8B-reaction dynamics at Coulomb barrier energies

    NASA Astrophysics Data System (ADS)

    Mazzocco, M.; Boiano, A.; Boiano, C.; La Commara, M.; Manea, C.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Strano, E.; Torresi, D.; Yamaguchi, H.; Kahl, D.; Acosta, L.; Di Meo, P.; Fernandez-Garcia, J. P.; Glodariu, T.; Grebosz, J.; Guglielmetti, A.; Imai, N.; Hirayama, Y.; Ishiyama, H.; Iwasa, N.; Jeong, S. C.; Jia, H. M.; Keeley, N.; Kim, Y. H.; Kimura, S.; Kubono, S.; Lay, J. A.; Lin, C. J.; Marquinez-Duran, G.; Martel, I.; Miyatake, H.; Mukai, M.; Nakao, T.; Nicoletto, M.; Pakou, A.; Rusek, K.; Sakaguchi, Y.; Sánchez-Benítez, A. M.; Sava, T.; Sgouros, O.; Stefanini, C.; Soramel, F.; Soukeras, V.; Stiliaris, E.; Stroe, L.; Teranishi, T.; Toniolo, N.; Wakabayashi, Y.; Watanabe, Y. X.; Yang, L.; Yang, Y. Y.

    2016-05-01

    We investigated the reaction dynamics induced by the Radioactive Ion Beams 7Be and 8B on a 208Pb target at energies around the Coulomb barrier. The two measurements are strongly interconnected, being 7Be (Sα = 1.586 MeV) the loosely bound core of the even more exotic 8B (Sp = 0.1375 MeV) nucleus. Here we summarize the present status of the data analysis for the measurement of the elastic scattering process for both reactions and the preliminary results for the optical model analysis of the collected data.

  15. OVERVIEW OF THE U.S. DEPARTMENT OF ENERGY AND NUCLEAR REGULATORY COMMISSION PERFORMANCE ASSESSMENT APPROACHES: CEMENTITIOUS BARRIERS PARTNERSHIP

    SciTech Connect

    Langton, C.; Burns, H.

    2009-05-29

    Engineered barriers including cementitious barriers are used at sites disposing or contaminated with low-level radioactive waste to enhance performance of the natural environment with respect to controlling the potential spread of contaminants. Drivers for using cementitious barriers include: high radionuclide inventory, radionuclide characteristics (e.g., long half-live, high mobility due to chemical form/speciation, waste matrix properties, shallow water table, and humid climate that provides water for leaching the waste). This document comprises the first in a series of reports being prepared for the Cementitious Barriers Partnership. The document is divided into two parts which provide a summary of: (1) existing experience in the assessment of performance of cementitious materials used for radioactive waste management and disposal and (2) sensitivity and uncertainty analysis approaches that have been applied for assessments. Each chapter is organized into five parts: Introduction, Regulatory Considerations, Specific Examples, Summary of Modeling Approaches and Conclusions and Needs. The objective of the report is to provide perspective on the state of the practice for conducting assessments for facilities involving cementitious barriers and to identify opportunities for improvements to the existing approaches. Examples are provided in two contexts: (1) performance assessments conducted for waste disposal facilities and (2) performance assessment-like analyses (e.g., risk assessments) conducted under other regulatory regimes. The introductory sections of each section provide a perspective on the purpose of performance assessments and different roles of cementitious materials for radioactive waste management. Significant experience with assessments of cementitious materials associated with radioactive waste disposal concepts exists in the US Department of Energy Complex and the commercial nuclear sector. Recently, the desire to close legacy facilities has created

  16. Barriers to Building Energy Efficiency (BEE) promotion: A transaction costs perspective

    NASA Astrophysics Data System (ADS)

    Qian Kun, Queena

    Worldwide, buildings account for a surprisingly high 40% of global energy consumption, and the resulting carbon footprint significantly exceeds that of all forms of transportation combined. Large and attractive opportunities exist to reduce buildings' energy use at lower costs and higher returns than in other sectors. This thesis analyzes the concerns of the market stakeholders, mainly real estate developers and end-users, in terms of transaction costs as they make decisions about investing in Building Energy Efficiency (BEE). It provides a detailed analysis of the current situation and future prospects for BEE adoption by the market's stakeholders. It delineates the market and lays out the economic and institutional barriers to the large-scale deployment of energy-efficient building techniques. The aim of this research is to investigate the barriers raised by transaction costs that hinder market stakeholders from investing in BEES. It explains interactions among stakeholders in general and in the specific case of Hong Kong as they consider transaction costs. It focuses on the influence of transaction costs on the decision-making of the stakeholders during the entire process of real estate development. The objectives are: 1) To establish an analytical framework for understanding the barriers to BEE investment with consideration of transaction costs; 2) To build a theoretical game model of decision making among the BEE market stakeholders; 3) To study the empirical data from questionnaire surveys of building designers and from focused interviews with real estate developers in Hong Kong; 4) To triangulate the study's empirical findings with those of the theoretical model and analytical framework. The study shows that a coherent institutional framework needs to be established to ensure that the design and implementation of BEE policies acknowledge the concerns of market stakeholders by taking transaction costs into consideration. Regulatory and incentive options

  17. Coronal microleakage of three different dental biomaterials as intra-orifice barrier during nonvital bleaching

    PubMed Central

    Zarenejad, Nafiseh; Asgary, Saeed; Ramazani, Nahid; Haghshenas, Mohammad Reza; Rafiei, Alireza; Ramazani, Mohsen

    2015-01-01

    Background: This study was designed to assess the microleakage of glass-ionomer (GI), mineral trioxide aggregate (MTA), and calcium-enriched mixture (CEM) cement as coronal orifice barrier during walking bleaching. Materials and Methods: In this experimental study, endodontic treatment was done for 70 extracted human incisors without canal calcification, caries, restoration, resorption, or cracks. The teeth were then divided into three experimental using “Simple randomization allocation” (n = 20) and two control groups (n = 5). The three cements were applied as 3-mm intra-orifice barrier in test groups, and bleaching process was then conducted using a mixture of sodium perborate powder and distilled water, for 9 days. For leakage evaluation, bovine serum albumin marker was traced in a dual-chamber technique with Bradford indicator. The Kruskal-Wallis and Mann-Whitney tests were used for statistical analysis. Results: The mean ± standard deviation leakage of samples from negative control, positive control, GI, MTA, and CEM cement groups were 0.0, 8.9 ± 0.03, 0.47 ± 0.02, 0.48 ± 0.02, and 0.49 ± 0.02 mg/mL, respectively. Statistical analysis showed no significant difference between three experimental groups (P > 0.05). Conclusion: It is concluded that GI, MTA, and CEM cements are considered as suitable intra-orifice barrier to provide coronal seal during walking bleaching. PMID:26759596

  18. Sensing properties of different classes of gases based on the nanowire-electrode junction barrier modulation

    NASA Astrophysics Data System (ADS)

    Singh, Nandan; Yan, Chaoyi; Lee, Pooi See; Comini, Elisabetta

    2011-04-01

    The role of contact between semiconducting nanowire and metal electrodes in a single nanowire field effect transistor (NW-FET) is investigated for the sensing of different type of gases. Two different types of In2O3nanowire devices, namely; Schottky contact device (SCD) and Ohmic contact device (OCD) are evaluated. SCD has shown a superior response to the reducing gas (CO) compared to oxidizing gas (NO), while OCD has shown high sensitivity towards oxidizing gas (NO) compared to the reducing gas (CO) under similar working conditions. The sensing mechanism is dominated by the contact resistance at the metal-semiconductor junction in SCD and the change in nanowirechannel conductance dominates in OCD. The Schottky barrier height (SBH) was extracted using low temperature current voltage measurement which provided direct evidence for the notion that the barrier height plays a crucial role in the sensing of different types of gases. The sensing mechanism is illustrated in this work for both devices.The role of contact between semiconducting nanowire and metal electrodes in a single nanowire field effect transistor (NW-FET) is investigated for the sensing of different type of gases. Two different types of In2O3nanowire devices, namely; Schottky contact device (SCD) and Ohmic contact device (OCD) are evaluated. SCD has shown a superior response to the reducing gas (CO) compared to oxidizing gas (NO), while OCD has shown high sensitivity towards oxidizing gas (NO) compared to the reducing gas (CO) under similar working conditions. The sensing mechanism is dominated by the contact resistance at the metal-semiconductor junction in SCD and the change in nanowirechannel conductance dominates in OCD. The Schottky barrier height (SBH) was extracted using low temperature current voltage measurement which provided direct evidence for the notion that the barrier height plays a crucial role in the sensing of different types of gases. The sensing mechanism is illustrated in this work

  19. Efficient dynamical correction of the transition state theory rate estimate for a flat energy barrier.

    PubMed

    Mökkönen, Harri; Ala-Nissila, Tapio; Jónsson, Hannes

    2016-09-07

    The recrossing correction to the transition state theory estimate of a thermal rate can be difficult to calculate when the energy barrier is flat. This problem arises, for example, in polymer escape if the polymer is long enough to stretch between the initial and final state energy wells while the polymer beads undergo diffusive motion back and forth over the barrier. We present an efficient method for evaluating the correction factor by constructing a sequence of hyperplanes starting at the transition state and calculating the probability that the system advances from one hyperplane to another towards the product. This is analogous to what is done in forward flux sampling except that there the hyperplane sequence starts at the initial state. The method is applied to the escape of polymers with up to 64 beads from a potential well. For high temperature, the results are compared with direct Langevin dynamics simulations as well as forward flux sampling and excellent agreement between the three rate estimates is found. The use of a sequence of hyperplanes in the evaluation of the recrossing correction speeds up the calculation by an order of magnitude as compared with the traditional approach. As the temperature is lowered, the direct Langevin dynamics simulations as well as the forward flux simulations become computationally too demanding, while the harmonic transition state theory estimate corrected for recrossings can be calculated without significant increase in the computational effort.

  20. Synthesis and characterization of low surface energy fluoropolymers as potential barrier coatings in oral care.

    PubMed

    Churchley, David P; Barbu, Eugen; Ewen, Richard J; Shen, Zhihao; Kim, Yongchul; McHugh, Mark A; Zhang, Zhong Yi; Nevell, Thomas G; Rees, Gareth D; Tsibouklis, John

    2008-03-15

    A series of low surface energy fluorinated homopolymers and copolymers has been synthesized and characterized using thermal, optical, spectroscopic, and chromatographic techniques. Their utility as barrier technologies in oral care has been considered, and aqueous nanosuspensions of the materials have been deposited as films on model dental hard surfaces in the presence and absence of a salivary pellicle. Calcium hydroxyapatite has been used as a model for enamel, as has PMMA due to its widespread use in denture fabrication. Surface energy determinations, combined with XPS studies, have provided insights into the molecular-level organization at the surface of the film structures. Studies of solubility in supercritical carbon dioxide have identified the polymers that are suitable for processing in this medium.

  1. The {sup 6}He Optical Potential at energies around the Coulomb barrier

    SciTech Connect

    Fernandez-Garcia, J. P.; Alvarez, M. A. G.; Moro, A. M.

    2010-04-26

    We present an Optical Model (OM) study of {sup 6}He on {sup 208}Pb elastic scattering data, measured at laboratory energies around the Coulomb barrier (E{sub lab} = 14, 16, 18, 22, and 27 MeV)[1]. For the projectile-target bare interaction, we use the microscopic Sao Paulo Potential (SPP). This bare interaction is supplemented with a Coulomb Dipole Polarization (CDP) potential, as well as a diffuse complex Woods-Saxon potential. Four-body Continuum-Discretized-Coupled-Channels (CDCC) calculations have been performed in order to support the optical model analysis. We have also studied the alpha channel, which is the dominant reaction process. In the analysis of this channel, we compare the angular and energy distributions of the alpha particles measured at 22 MeV, with Distorted Wave Born Approximation (DWBA) calculations.

  2. Total reaction cross sections for 8Li + 90Zr at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Pakou, A.; Pierroutsakou, D.; Mazzocco, M.; Acosta, L.; Aslanoglou, X.; Boiano, A.; Boiano, C.; Carbone, D.; Cavallaro, M.; Grebosz, J.; Keeley, N.; La Commara, M.; Manea, C.; Marquinez-Duran, G.; Martel, I.; Parascandolo, C.; Rusek, K.; Sánchez-Benítez, A. M.; Sgouros, O.; Signorini, C.; Soramel, F.; Soukeras, V.; Stiliaris, E.; Strano, E.; Torresi, D.; Trzcinska, A.; Watanabe, Y. X.; Yamaguchi, H.

    2015-05-01

    Total reaction cross sections for the radioactive nucleus 8Li on 90Zr are reported at the near-barrier energies of 18.5 and 21.5MeV, derived from quasi-elastic scattering measurements. An analysis of the quasi-elastic scattering results is performed within an optical model framework using the BDM3Y1 interaction and total reaction cross sections are deduced. These quantities, appropriately reduced, are compared with previous data obtained in elastic scattering measurements with well and weakly bound projectiles on various targets and a formula for predicting total reaction cross sections with an uncertainty of % is obtained. Further on, the ratios of direct to total reaction cross sections are estimated for 6,8Li on various targets and are compared with CDCC or CRC calculations. The energy dependence of the optical potential is also discussed.

  3. Entrance Channel Mass Asymmetry Effects in Sub-Barrier Fusion Dynamics by Using Energy Dependent Woods-Saxon Potential

    NASA Astrophysics Data System (ADS)

    Manjeet Singh, Gautam

    2015-12-01

    The present article highlights the inconsistency of static Woods-Saxon potential and the applicability of energy dependent Woods-Saxon potential to explore the fusion dynamics of {}4822Ti+58,60,6428Ni, {}4622Ti+{}6428Ni,{}5022Ti+{}6028Ni, and {}199F+9341Nb reactions leading to formation of different Sn-isotopes via different entrance channels. Theoretical calculations based upon one-dimensional Wong formula obtained by using static Woods-Saxon potential unable to provide proper explanation for sub-barrier fusion enhancement of these projectile-target combinations. However, the predictions of one-dimensional Wong formula based upon energy dependent Woods-Saxon potential model (EDWSP model) accurately describe the observed fusion dynamics of these systems wherein the significantly larger value of diffuseness parameter ranging from a = 0.85 fm to a = 0.97 fm is required to address the experimental data in whole range of energy. Therefore, the energy dependence in nucleus-nucleus potential simulates the influence of the nuclear structure degrees of freedom of the colliding pairs. Supported by Dr. D.S. Kothari Post-Doctoral Fellowship Scheme sponsored by University Grants Commission (UGC), New Delhi, India

  4. A Review of Barriers to and Opportunities for the Integration of Renewable Energy in the Southeast

    SciTech Connect

    McConnell, Ben W; Hadley, Stanton W; Xu, Yan

    2011-08-01

    The objectives of this study were to prepare a summary report that examines the opportunities for and obstacles to the integration of renewable energy resources in the Southeast between now and the year 2030. The report, which is based on a review of existing literature regarding renewable resources in the Southeast, includes the following renewable energy resources: wind, solar, hydro, geothermal, biomass, and tidal. The evaluation was conducted by the Oak Ridge National Laboratory for the Energy Foundation and is a subjective review with limited detailed analysis. However, the report offers a best estimate of the magnitude, time frame, and cost of deployment of renewable resources in the Southeast based upon the literature reviewed and reasonable engineering and economic estimates. For the purposes of this report, the Southeast is defined as the states of Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, and West Virginia. In addition, some aspects of the report (wind and geothermal) also consider the extended Southeast, which includes Maryland, Missouri, Oklahoma, and Texas. A description of the existing base of renewable electricity installations in the region is given for each technology considered. Where available, the possible barriers and other considerations regarding renewable energy resources are listed in terms of availability, investment and maintenance costs, reliability, installation requirements, policies, and energy market. As stated above, the report is a comprehensive review of renewable energy resources in the southeastern region of United States based on a literature study that included information obtained from the Southern Bio-Power wiki, sources from the Energy Foundation, sources available to ORNL, and sources found during the review. The report consists of an executive summary, this introductory chapter describing report objectives, a chapter on analysis methods and

  5. Role of energy dependent interaction potential in sub-barrier fusion of S2814i +Z9040r system

    NASA Astrophysics Data System (ADS)

    Gautam, Manjeet Singh; Sharma, Manoj K.

    2015-08-01

    We have analyzed the importance of the inelastic surface vibrations of colliding nuclei in the sub-barrier fusion enhancement of S2814i +Z9040r system by using the energy dependent Woods-Saxon potential model (EDWSP model) in conjunction with one dimensional Wong formula and the coupled channel formulation using the code CCFULL. The multi-phonon vibrational states of colliding nuclei seem to impart significant contribution. The coupling between relative motion of reactants and these relevant channels in turn produce anomalously large sub-barrier fusion enhancement over the expectations of one dimensional barrier penetration model. Furthermore, the effects of coupling to inelastic surface excitations are imitated due to energy dependence in the Woods-Saxon potential. In EDWSP model calculations, a wide range of diffuseness parameter much larger than the elastic scattering predictions is needed to account the observed fusion enhancement in the close vicinity of Coulomb barrier.

  6. Investigation of contribution of incomplete fusion in the total fusion process induced by 9Be on 181Ta target at near barrier energies

    NASA Astrophysics Data System (ADS)

    Kharab, Rajesh; Chahal, Rajiv; Kumar, Rajiv

    2016-02-01

    We have studied the relative contribution of incomplete fusion (ICF) and complete fusion (CF) in total fusion (TF) induced by 9Be on 181Ta target at energies in the vicinity of Coulomb barrier using classical dynamical model and Wong's formula in conjugation with energy dependent Woods-Saxon formula. It is found that at above barrier energies ICF contributes almost 30% in TF while at energies below the barrier qualitatively its contribution is much more than thirty percent.

  7. Calculation of energy-barrier lowering by incoherent switching in spin-transfer torque magnetoresistive random-access memory

    SciTech Connect

    Munira, Kamaram; Visscher, P. B.

    2015-05-07

    To make a useful spin-transfer torque magnetoresistive random-access memory (STT-MRAM) device, it is necessary to be able to calculate switching rates, which determine the error rates of the device. In a single-macrospin model, one can use a Fokker-Planck equation to obtain a low-current thermally activated rate ∝exp(−E{sub eff}/k{sub B}T). Here, the effective energy barrier E{sub eff} scales with the single-macrospin energy barrier KV, where K is the effective anisotropy energy density and V the volume. A long-standing paradox in this field is that the actual energy barrier appears to be much smaller than this. It has been suggested that incoherent motions may lower the barrier, but this has proved difficult to quantify. In the present paper, we show that the coherent precession has a magnetostatic instability, which allows quantitative estimation of the energy barrier and may resolve the paradox.

  8. Fusion evaporation and fusion-fission with aligned /sup 23/Na ions at energies near and below the fusion barrier

    SciTech Connect

    Butsch, R.; Jaensch, H.; Kraemer, D.; Moebius, K.; Ott, W.; Steffens, E.; Tungate, G.; Weller, a.A.; Becker, K.; Blatt, K.; and others

    1987-10-01

    Using aligned /sup 23/Na beams, fusion cross sections sigma/sup fus/ and second-rank tensor analyzing powers for fusion T/sub 20//sup fus/ have been measured at energies near and below the fusion barrier for /sup 23/Na+ /sup 48/Ti and for /sup 23/Na+ /sup 206/Pb. At sub-barrier energies, large, nearly maximal, values of T/sub 20//sup fus/ occur, especially for fusion with the heavy target /sup 206/Pb. This reflects the strong influence of the spectroscopic deformation of the projectile on the fusion process at energies below the barrier. However, within a quantum-mechanical coupled-channels calculation this degree of freedom is not enough to describe both the fusion cross section and the second-rank tensor analyzing power for fusion in the energy regime below the fusion barrier. It is shown that the coupling of the fusion channel to inelastic excitations of the projectile and the target can describe the magnitude and energy dependence of T/sub 20//sup fus/ for both heavy ion systems, but fails to reproduce the ''sub-barrier enhancement'' of the fusion cross section for both systems.

  9. Enhancing ability of harvesting energy from random vibration by decreasing the potential barrier of bistable harvester

    NASA Astrophysics Data System (ADS)

    Lan, Chunbo; Qin, Weiyang

    2017-02-01

    When a bistable energy harvester (BEH) is driven by weak random excitation, its harvesting efficiency will decrease due to the seldom occurrence of interwell motion. To overcome this defect, we developed an improved bistable energy harvester (IBEH) from BEH by adding a small magnet at the middle of two fixed magnets. It is proved that the attractive force originated from the additional magnet can pull down the potential barrier and shallow the potential well, but still keep the middle position of beam unstable. This can make jumping between potential wells easier. Thus IBEH can realize snap-through even at fairly weak excitation. The magnetic potential energy is given and the electromechanical equations are derived. Then the harvesting performance of IBEH under random excitation is studied. Validation experiments are designed and carried out. Comparisons prove that IBEH is preferable to BEH in harvesting random energy and can give out a high output voltage even at weak excitation. The size of additional magnet can be optimized to reach the best performance of IBEH.

  10. Effect of 2450-MHz microwave energy on the blood-brain barrier to hydrophilic molecules

    SciTech Connect

    Williams, W.M.

    1983-01-01

    Microwave energy at 2450 MHz 120 Hz AM was found ineffective in increasing the permeability of the blood-brain barrier to the hydrophilic tracers HRP and (/sup 14/C) sucrose. Furthermore, a diminished permeability to HRP and sodium fluorescein was apparent after 180 minutes of exposure to microwaves at an incident power density of 20 mW/cm/sup 2/. Colonic temperature, as well as temperature within the cerebral cortex, hypothalamus, cerebellum and medulla, were elevated by less than 1/sup 0/C over those of sham-exposed rats. A significant decrease in the permeability to HRP and (/sup 14/C) sucrose occurred after exposure to an incident power density of 65 mW/cm/sup 2/ for 30 minutes. The reduction in permeability to HRP correlated with a suppressed incorporation of the tracer by pinocytosis in cerebral microvessels. Suppression of blood-brain barrier permeability to hydrophilic tracers was most pronounced at brain temperatures exceeding approx. 40/sup 0/C and is demonstrated to be temperature dependent.

  11. Single-Chain Magnets Based on Octacyanotungstate with the Highest Energy Barriers for Cyanide Compounds

    PubMed Central

    Wei, Rong-Min; Cao, Fan; Li, Jing; Yang, Li; Han, Yuan; Zhang, Xiu-Ling; Zhang, Zaichao; Wang, Xin-Yi; Song, You

    2016-01-01

    By introducing large counter cations as the spacer, two isolated 3, 3-ladder compounds, (Ph4P)[CoII(3-Mepy)2.7(H2O)0.3WV(CN)8]·0.6H2O (1) and (Ph4As)[CoII(3-Mepy)3WV(CN)8] (2, 3-Mepy = 3-methylpyridine), were synthesized and characterized. Static and dynamic magnetic characterizations reveal that compounds 1 and 2 both behave as the single-chain magnets (SCMs) with very high energy barriers: 252(9) K for 1 and 224(7) K for 2, respectively. These two compounds display the highest relaxation barriers for cyano-bridged SCMs and are preceded only by two cobalt(II)-radical compounds among all SCMs. Meanwhile, a large coercive field of 26.2 kOe (1) and 22.6 kOe (2) were observed at 1.8 K. PMID:27071451

  12. Activation of metabotropic GABA receptors increases the energy barrier for vesicle fusion.

    PubMed

    Rost, Benjamin R; Nicholson, Patrick; Ahnert-Hilger, Gudrun; Rummel, Andreas; Rosenmund, Christian; Breustedt, Joerg; Schmitz, Dietmar

    2011-09-15

    Neurotransmitter release from presynaptic terminals is under the tight control of various metabotropic receptors. We report here that in addition to the regulation of Ca(2+) channel activity, metabotropic GABA(B) receptors (GABA(B)Rs) at murine hippocampal glutamatergic synapses utilize an inhibitory pathway that directly targets the synaptic vesicle release machinery. Acute application of the GABA(B)R agonist baclofen rapidly and reversibly inhibits vesicle fusion, which occurs independently of the SNAP-25 C-terminus. Using applications of hypertonic sucrose solutions, we find that the size of the readily releasable pool remains unchanged by GABA(B)R activation, but the sensitivity of primed vesicles to hypertonic stimuli appears lowered as the response amplitudes at intermediate sucrose concentrations are smaller and release kinetics are slowed. These data show that presynaptic GABA(B)Rs can inhibit neurotransmitter release directly by increasing the energy barrier for vesicle fusion.

  13. Cross sections and barriers for nuclear fission induced by high-energy nucleons

    SciTech Connect

    Grudzevich, O. T.; Yavshits, S. G.

    2013-03-15

    The cross sections for the fission of {sup 232}Th, {sup 235,238}U, {sup 237}Np, and {sup 239}Pu target nuclei that was induced by 20- to 1000-MeV neutrons and protons were calculated. The respective calculations were based on the multiconfiguration-fission (MCFx) model, which was used to describe three basic stages of the interaction of high-energy nucleons with nuclei: direct processes (intranuclear cascade), equilibration of the emerging compound system, and the decay of the compound nucleus (statistical model). Fission barriers were calculated within the microscopic approach for isotopic chains formed by 15 to 20 nuclei of the required elements. The calculated fission cross sections were compared with available experimental data. It was shown that the input data set and the theoretical model used made it possible to predict satisfactorily cross section for nuclear fission induced by 20- to 1000-MeV nucleons.

  14. The free-energy barrier to hydride transfer across a dipalladium complex.

    PubMed

    Vanston, C R; Kearley, G J; Edwards, A J; Darwish, T A; de Souza, N R; Ramirez-Cuesta, A J; Gardiner, M G

    2015-01-01

    We use density-functional theory molecular dynamics (DFT-MD) simulations to determine the hydride transfer coordinate between palladium centres of the crystallographically observed terminal hydride locations, Pd-Pd-H, originally postulated for the solution dynamics of the complex bis-NHC dipalladium hydride [{(MesIm)2CH2}2Pd2H][PF6], and then calculate the free-energy along this coordinate. We estimate the transfer barrier-height to be about 20 kcal mol(-1) with a hydride transfer rate in the order of seconds at room temperature. We validate our DFT-MD modelling using inelastic neutron scattering which reveals anharmonicity of the hydride environment that is so pronounced that there is complete failure of the harmonic model for the hydride ligand. The simulations are extended to high temperature to bring the H-transfer to a rate that is accessible to the simulation technique.

  15. The free-energy barrier to hydride transfer across a dipalladium complex

    SciTech Connect

    Ramirez-Cuesta, Anibal J

    2015-01-01

    We use density-functional theory molecular dynamics (DFT-MD) simulations to determine the hydride transfer coordinate between palladium centres of the crystallographically observed terminal hydride locations, Pd-Pd-H, originally postulated for the solution dynamics of the complex bis-NHC dipalladium hydride [{(MesIm)(2)CH2}(2)Pd2H][PF6], and then calculate the free-energy along this coordinate. We estimate the transfer barrier-height to be about 20 kcal mol(-1) with a hydride transfer rate in the order of seconds at room temperature. We validate our DFT-MD modelling using inelastic neutron scattering which reveals anharmonicity of the hydride environment that is so pronounced that there is complete failure of the harmonic model for the hydride ligand. The simulations are extended to high temperature to bring the H-transfer to a rate that is accessible to the simulation technique.

  16. The free-energy barrier to hydride transfer across a dipalladium complex

    DOE PAGES

    Ramirez-Cuesta, Anibal J

    2015-01-01

    We use density-functional theory molecular dynamics (DFT-MD) simulations to determine the hydride transfer coordinate between palladium centres of the crystallographically observed terminal hydride locations, Pd-Pd-H, originally postulated for the solution dynamics of the complex bis-NHC dipalladium hydride [{(MesIm)(2)CH2}(2)Pd2H][PF6], and then calculate the free-energy along this coordinate. We estimate the transfer barrier-height to be about 20 kcal mol(-1) with a hydride transfer rate in the order of seconds at room temperature. We validate our DFT-MD modelling using inelastic neutron scattering which reveals anharmonicity of the hydride environment that is so pronounced that there is complete failure of the harmonic model formore » the hydride ligand. The simulations are extended to high temperature to bring the H-transfer to a rate that is accessible to the simulation technique.« less

  17. Why Density-Gradient Corrections Improve Atomization Energies and Barrier Heights

    NASA Astrophysics Data System (ADS)

    Perdew, John P.; Ernzerhof, Matthias; Zupan, Ales; Burke, Kieron

    While the Hartree-Fock (HF) approximation typically underestimates the strength of the chemical bond, the local spin density (LSD) approximation overestimates it. Thus LSD overbinds atoms in molecules, and underestimates the heights of energy barriers when the transition state is more highly bonded than the initial state. Generalized gradient approximations (GGA's), which incorporate density-gradient corrections to LSD, improve the agreement between calculated and measured energetics. This has been previously understood as a consequence of the fact that gradient corrections favor density inhomogeneity, which increases when a bond is stretched or broken. We show that gradient corrections also favor high density, which increases when a bond is compressed or formed, but that the inhomogeneity effect usually prevails. To quantify the discussion, we present a thermodynamic-like inequality which is satisfied when gradient corrections favor a process.

  18. Quantum dynamics study of energy requirement on reactivity for the HBr + OH reaction with a negative-energy barrier.

    PubMed

    Wang, Yuping; Li, Yida; Wang, Dunyou

    2017-01-10

    A time-dependent, quantum reaction dynamics approach in full dimensional, six degrees of freedom was carried out to study the energy requirement on reactivity for the HBr + OH reaction with an early, negative energy barrier. The calculation shows both the HBr and OH vibrational excitations enhance the reactivity. However, even this reaction has a negative energy barrier, the calculation shows not all forms of energy are equally effective in promoting the reactivity. On the basis of equal amount of total energy, the vibrational energies of both the HBr and OH are more effective in enhancing the reactivity than the translational energy, whereas the rotational excitations of both the HBr and OH hinder the reactivity. The rate constants were also calculated for the temperature range between 5 to 500 K. The quantal rate constants have a better slope agreement with the experimental data than quasi-classical trajectory results.

  19. Quantum dynamics study of energy requirement on reactivity for the HBr + OH reaction with a negative-energy barrier

    PubMed Central

    Wang, Yuping; Li, Yida; Wang, Dunyou

    2017-01-01

    A time-dependent, quantum reaction dynamics approach in full dimensional, six degrees of freedom was carried out to study the energy requirement on reactivity for the HBr + OH reaction with an early, negative energy barrier. The calculation shows both the HBr and OH vibrational excitations enhance the reactivity. However, even this reaction has a negative energy barrier, the calculation shows not all forms of energy are equally effective in promoting the reactivity. On the basis of equal amount of total energy, the vibrational energies of both the HBr and OH are more effective in enhancing the reactivity than the translational energy, whereas the rotational excitations of both the HBr and OH hinder the reactivity. The rate constants were also calculated for the temperature range between 5 to 500 K. The quantal rate constants have a better slope agreement with the experimental data than quasi-classical trajectory results. PMID:28071762

  20. Quantum dynamics study of energy requirement on reactivity for the HBr + OH reaction with a negative-energy barrier

    NASA Astrophysics Data System (ADS)

    Wang, Yuping; Li, Yida; Wang, Dunyou

    2017-01-01

    A time-dependent, quantum reaction dynamics approach in full dimensional, six degrees of freedom was carried out to study the energy requirement on reactivity for the HBr + OH reaction with an early, negative energy barrier. The calculation shows both the HBr and OH vibrational excitations enhance the reactivity. However, even this reaction has a negative energy barrier, the calculation shows not all forms of energy are equally effective in promoting the reactivity. On the basis of equal amount of total energy, the vibrational energies of both the HBr and OH are more effective in enhancing the reactivity than the translational energy, whereas the rotational excitations of both the HBr and OH hinder the reactivity. The rate constants were also calculated for the temperature range between 5 to 500 K. The quantal rate constants have a better slope agreement with the experimental data than quasi-classical trajectory results.

  1. Elastic scattering of 17O+208Pb at energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Torresi, D.; Strano, E.; Mazzocco, M.; Boiano, A.; Boiano, C.; Di Meo, P.; La Commara, M.; Manea, C.; Nicoletto, M.; Grebosz, J.; Guglielmetti, A.; Molini, P.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Soramel, F.; Toniolo, N.; Filipescu, D.; Gheorghe, A.; Glodariu, T.; Jeong, S.; Kim, Y. H.; Lay, J. A.; Miyatake, H.; Pakou, A.; Sgouros, O.; Soukeras, V.; Stroe, L.; Vitturi, A.; Watanabe, Y.; Zerva, K.

    2016-05-01

    Within the frame of the commissioning of a new experimental apparatus EXPADES we undertook the measurement of the elastic scattering angular distribution for the system 17O+208Pb at energy around the Coulomb barrier. The reaction dynamics induced by loosely bound Radioactive Ion Beams is currently being extensively studied [4]. In particular the study of the elastic scattering process allows to obtain direct information on the total reaction cross section of the exotic nuclei. In order to understand the effect of the low binding energy on the reaction mechanism it is important to compare radioactive weakly bound nuclei with stable strongly-bound nuclei. In this framework the study of the 17O+208Pb elastic scattering can be considered to be complementary to a previous measurement of the total reaction cross section for the system 17F+208Pb at energies of 86, 90.4 MeV [5, 6]. The data will be compared with those obtained for the neighboring systems 16,18O+208Pb and others available in literature.

  2. Canonical free-energy barrier of particle and polymer cluster formation

    PubMed Central

    Zierenberg, Johannes; Schierz, Philipp; Janke, Wolfhard

    2017-01-01

    A common approach to study nucleation rates is the estimation of free-energy barriers. This usually requires knowledge about the shape of the forming droplet, a task that becomes notoriously difficult in macromolecular setups starting with a proper definition of the cluster boundary. Here we demonstrate a shape-free determination of the free energy for temperature-driven cluster formation in particle as well as polymer systems. Combined with rigorous results on equilibrium droplet formation, this allows for a well-defined finite-size scaling analysis of the effective interfacial free energy at a fixed density. We first verify the theoretical predictions for the formation of a liquid droplet in a supersaturated particle gas by generalized-ensemble Monte Carlo simulations of a Lennard-Jones system. Going one step further, we then generalize this approach to cluster formation in a dilute polymer solution. Our results suggest an analogy with particle condensation, when the macromolecules are interpreted as extended particles. PMID:28240262

  3. Functional and cytometric examination of different human lung epithelial cell types as drug transport barriers

    PubMed Central

    Min, Kyoung Ah; Rosania, Gus R.; Kim, Chong-Kook; Shin, Meong Cheol

    2016-01-01

    To develop inhaled medications, various cell culture models have been used to examine the transcellular transport or cellular uptake properties of small molecules. For the reproducible high throughput screening of the inhaled drug candidates, a further verification of cell architectures as drug transport barriers can contribute to establishing appropriate in vitro cell models. In the present study, side-by-side experiments were performed to compare the structure and transport function of three lung epithelial cells (Calu-3, normal human bronchial primary cells (NHBE), and NL-20). The cells were cultured on the nucleopore membranes in the air-liquid interface (ALI) culture conditions, with cell culture medium in the basolateral side only, starting from day 1. In transport assays, paracellular transport across all three types of cells appeared to be markedly different with the NHBE or Calu-3 cells, showing low paracellular permeability and high TEER values, while the NL-20 cells showed high paracellular permeability and low TEER. Quantitative image analysis of the confocal microscope sections further confirmed that the Calu-3 cells formed intact cell monolayers in contrast to the NHBE and NL-20 cells with multilayers. Among three lung epithelial cell types, the Calu-3 cell cultures under the ALI condition showed optimal cytometric features for mimicking the biophysical characteristics of in vivo airway epithelium. Therefore, the Calu-3 cell monolayers could be used as functional cell barriers for the lung-targeted drug transport studies. PMID:26746641

  4. The barriers encountered by teachers implementing education for sustainable development: discipline bound differences and teaching traditions

    NASA Astrophysics Data System (ADS)

    Borg, Carola; Gericke, Niklas; Höglund, Hans-Olof; Bergman, Eva

    2012-07-01

    Background : According to the Swedish curriculum teachers in all subjects have a responsibility to integrate a holistic perspective of sustainable development (SD) and teach according to an education for sustainable development (ESD) approach. However previous research has shown that teachers from different subjects perceive SD differently. Purpose : The study aimed at investigating if and how teachers' subject area influences their ability to implement a holistic perspective of ESD; we investigated both the impact of teaching traditions and the barriers that teachers experienced. Sample : A stratified sample of 224 Swedish upper secondary schools participated. An online questionnaire was sent and answered by a total of 3229 teachers at these schools. In total, there were 669 science teachers, 373 social science teachers, 483 language teachers, 713 vocational and esthetical-practical teachers, and 739 teachers from other disciplines who participated in the survey. Design and methods : The questionnaire consisted of questions requiring Likert-scale responses and multiple-choice questions. The data from the questionnaire were analyzed using Pearson's Chi-square test and one-way ANOVA. The significance level accepted was p < 0.05. Results : Teachers were influenced by their own subject traditions. Science teachers in our study were grounded in the fact-based tradition and lectures were the most common teaching method used. The teaching tradition of the social science teachers seemed to be most in line to an ESD approach. Many language teachers (41%) stated they did not include SD issues in their teaching at all. Among the barriers identified, the most common obstacles were that the teachers lacked inspiring examples of how to include SD in their teaching and that they lacked the necessary expertise about SD. Conclusion : This study highlights the need for the management within schools to create opportunities for teachers to work collaboratively when teaching ESD. It

  5. Asymmetric isolating barriers between different microclimatic environments caused by low immigrant survival

    PubMed Central

    Gosden, Thomas P.; Waller, John T.; Svensson, Erik I.

    2015-01-01

    Spatially variable selection has the potential to result in local adaptation unless counteracted by gene flow. Therefore, barriers to gene flow will help facilitate divergence between populations that differ in local selection pressures. We performed spatially and temporally replicated reciprocal field transplant experiments between inland and coastal habitats using males of the common blue damselfly (Enallagma cyathigerum) as our study organism. Males from coastal populations had lower local survival rates than resident males at inland sites, whereas we detected no differences between immigrant and resident males at coastal sites, suggesting asymmetric local adaptation in a source–sink system. There were no intrinsic differences in longevity between males from the different environments suggesting that the observed differences in male survival are environment-dependent and probably caused by local adaptation. Furthermore, the coastal environment was found to be warmer and drier than the inland environment, further suggesting local adaptation to microclimatic factors has lead to differential survival of resident and immigrant males. Our results suggest that low survival of immigrant males mediates isolation between closely located populations inhabiting different microclimatic environments. PMID:25631994

  6. Making AlN(x) Tunnel Barriers Using a Low-Energy Nitrogen-Ion Beam

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama; Kleinsasser, Alan; Bumble, Bruce; LeDuc, Henry; Lee, Karen

    2005-01-01

    A technique based on accelerating positive nitrogen ions onto an aluminum layer has been demonstrated to be effective in forming thin (<2 nm thick) layers of aluminum nitride (AlN(x)) for use as tunnel barriers in Nb/Al-AlN(x)/Nb superconductor/insulator/ superconductor (SIS) Josephson junctions. AlN(x) is the present material of choice for tunnel barriers because, to a degree greater than that of any other suitable material, it offers the required combination of low leakage current at high current density and greater thermal stability. While ultra-thin AlN films with good thickness and stoichiometry control are easily formed using techniques such as reactive molecular beam epitaxy and chemical vapor deposition, growth temperatures of 900 C are necessary for the dissociative adsorption of nitrogen from either nitrogen (N2) or ammonia (NH3). These growth temperatures are prohibitively high for the formation of tunnel barriers on Nb films because interfacial reactions at temperatures as low as 200 to 300 C degrade device properties. Heretofore, deposition by reactive sputtering and nitridation of thin Al layers with DC and RF nitrogen plasmas have been successfully used to form AlN barriers in SIS junctions. However, precise control over critical current density Jc has proven to be a challenge, as is attaining adequate process reproducibility from system to system. The present ion-beam technique is an alternative to the plasma or reactive sputtering techniques as it provides a highly controlled arrival of reactive species, independent of the electrical conditions of the substrate or vacuum chamber. Independent and accurate control of parameters such as ion energy, flux, species, and direction promises more precise control of film characteristics such as stoichiometry and thickness than is the case with typical plasma processes. In particular, the background pressure during ion-beam nitride growth is 2 or 3 orders of magnitude lower, minimizing the formation of

  7. Changes in Properties of Dielectric Barrier Discharge Plasma Jets for Different Gases and for Insulating and Conducting Transfer Plates

    NASA Astrophysics Data System (ADS)

    do Nascimento, Fellype; Moshkalev, Stanislav; Machida, Munemasa

    2017-03-01

    Dielectric barrier discharge (DBD) plasma jets have been studied extensively in recent years because of its wide range of applications. DBD plasmas can be produced using many different gases and can be applied to a broad variety of surfaces and substrates. This work provides comparisons of DBD plasmas generated using argon (Ar), helium (He), and nitrogen (N2), as well as their mixtures with water vapor in order to know how some plasma properties are affected by the use of different gases. All plasmas were studied in two different conditions: using a transfer plate made of a conductive material and using a transfer plate made of an insulating one. It was observed that the process of Penning ionization of nitrogen molecules by direct collisions with metastable atoms and molecules is evident and significant only in plasmas that use He as the working gas, which means that He atoms in metastable states have greater ability to transfer energy to molecules of nitrogen in the plasma. The collisions of metastable He with N2 molecules determine the vibrational temperature (T vib) values in He plasmas, while in Ar and N2 plasmas, the T vib values are determined mainly by collisions of electrons with N2 molecules. It was noticed that the use of an insulating or a conducting transfer plate as the sample holder affects the results of adhesion between poly(dimethylsiloxane) samples, and it is mainly due to the differences in the plasma power, with a higher plasma power leading to better adhesion.

  8. Transient effects of drying creep in nanoporous solids: understanding the effects of nanoscale energy barriers

    NASA Astrophysics Data System (ADS)

    Sinko, Robert; Vandamme, Matthieu; Bažant, Zdeněk P.; Keten, Sinan

    2016-07-01

    The Pickett effect is the phenomenon of creep enhancement during transient drying. It has been observed for many nanoporous solids, including concrete, wood and Kevlar. While the existing micromechanical models can partially explain this effect, they have yet to consider nanoscale dynamic effects of water in nanopores, which are believed to be of paramount importance. Here, we examine how creep deformations in a slit pore are accelerated by the motion of water due to drying forces using coarse-grained molecular dynamics simulations. We find that the drying that drives water flow in the nanopores lowers both the activation energy of pore walls sliding past one another and the apparent viscosity of confined water molecules. This lowering can be captured with an analytical Arrhenius relationship accounting for the role of water flow in overcoming the energy barriers. Notably, we use this model and simulation results to demonstrate that the drying creep strain is not linearly dependent on the applied creep stress at the nanopore level. Our findings establish the scaling relationships that explain how the creep driving force, drying force and fluid properties are related. Thus, we establish the nanoscale origins of the Pickett effect and provide strategies for minimizing the additional displacements arising from this effect.

  9. Transient effects of drying creep in nanoporous solids: understanding the effects of nanoscale energy barriers.

    PubMed

    Sinko, Robert; Vandamme, Matthieu; Bažant, Zdeněk P; Keten, Sinan

    2016-07-01

    The Pickett effect is the phenomenon of creep enhancement during transient drying. It has been observed for many nanoporous solids, including concrete, wood and Kevlar. While the existing micromechanical models can partially explain this effect, they have yet to consider nanoscale dynamic effects of water in nanopores, which are believed to be of paramount importance. Here, we examine how creep deformations in a slit pore are accelerated by the motion of water due to drying forces using coarse-grained molecular dynamics simulations. We find that the drying that drives water flow in the nanopores lowers both the activation energy of pore walls sliding past one another and the apparent viscosity of confined water molecules. This lowering can be captured with an analytical Arrhenius relationship accounting for the role of water flow in overcoming the energy barriers. Notably, we use this model and simulation results to demonstrate that the drying creep strain is not linearly dependent on the applied creep stress at the nanopore level. Our findings establish the scaling relationships that explain how the creep driving force, drying force and fluid properties are related. Thus, we establish the nanoscale origins of the Pickett effect and provide strategies for minimizing the additional displacements arising from this effect.

  10. Influence of hydrodynamic energy on Holocene reef flat accretion, Great Barrier Reef

    NASA Astrophysics Data System (ADS)

    Dechnik, Belinda; Webster, Jody M.; Nothdurft, Luke; Webb, Gregory E.; Zhao, Jian-xin; Duce, Stephanie; Braga, Juan C.; Harris, Daniel L.; Vila-Concejo, Ana; Puotinen, Marji

    2016-01-01

    The response of platform reefs to sea-level stabilization over the past 6 ka is well established for the Great Barrier Reef (GBR), with reefs typically accreting laterally from windward to leeward. However, these observations are based on few cores spread across reef zones and may not accurately reflect a reef's true accretional response to the Holocene stillstand. We present a new record of reef accretion based on 49 U/Th ages from Heron and One Tree reefs in conjunction with re-analyzed data from 14 reefs across the GBR. We demonstrate that hydrodynamic energy is the main driver of accretional direction; exposed reefs accreted primarily lagoon-ward while protected reefs accreted seawards, contrary to the traditional growth model in the GBR. Lateral accretion rates varied from 86.3 m/ka-42.4 m/ka on the exposed One Tree windward reef and 68.35 m/ka-15.7 m/ka on the protected leeward Heron reef, suggesting that wind/wave energy is not a dominant control on lateral accretion rates. This represents the most comprehensive statement of lateral accretion direction and rates from the mid-outer platform reefs of the GBR, confirming great variability in reef flat growth both within and between reef margins over the last 6 ka, and highlighting the need for closely-spaced transects.

  11. In vivo measurements of skin barrier: comparison of different methods and advantages of laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Patzelt, A.; Sterry, W.; Lademann, J.

    2010-12-01

    A major function of the skin is to provide a protective barrier at the interface between external environment and the organism. For skin barrier measurement, a multiplicity of methods is available. As standard methods, the determination of the transepidermal water loss (TEWL) as well as the measurement of the stratum corneum hydration, are widely accepted, although they offer some obvious disadvantages such as increased interference liability. Recently, new optical and spectroscopic methods have been introduced to investigate skin barrier properties in vivo. Especially, laser scanning microscopy has been shown to represent an excellent tool to study skin barrier integrity in many areas of relevance such as cosmetology, occupation, diseased skin, and wound healing.

  12. Imaging the radical channel in acetaldehyde photodissociation: Competing mechanisms at energies close to the triplet exit barrier

    SciTech Connect

    Amaral, G. A.; Arregui, A.; Rodriguez, J. D.; Banares, L.; Rubio-Lago, L.

    2010-08-14

    The photodissociation of acetaldehyde in the radical channel has been studied at wavelengths between 315 and 325 nm using the velocity-map imaging technique. Upon one-photon absorption at 315 nm, the molecule is excited to the first singlet excited state S{sub 1}, which, in turn, undergoes intersystem crossing to the first excited triplet state T{sub 1}. On the triplet surface, the molecule dissociates into CH{sub 3} and HCO radicals with large kinetic energy release (KER), in accordance with the well characterized exit barrier on T{sub 1}. However, at longer wavelengths (>320 nm), which correspond to excitation energies just below the triplet barrier, a sudden change in KER is observed. At these photolysis wavelengths, there is not enough energy to surpass the exit barrier on the triplet state, which leaves the possibility of unimolecular dissociation on S{sub 0} after internal conversion from S{sub 1}. We have characterized the fragments' KER at these wavelengths, as well as determined the energy partitioning for the radical fragments. A new accurate estimate of the barrier height on T{sub 1} is presented.

  13. Pentametallic lanthanide-alkoxide square-based pyramids: high energy barrier for thermal relaxation in a holmium single molecule magnet.

    PubMed

    Blagg, Robin J; Tuna, Floriana; McInnes, Eric J L; Winpenny, Richard E P

    2011-10-14

    Pentametallic Ln complexes of formula [Ln(5)O(O(i)Pr)(13)] have been made, where Ln(III) = Sm, Gd, Tb, Ho and Er; slow magnetisation relaxation to 33 K is observed for the Ho complex with an energy barrier of ca. 400 K.

  14. One-neutron stripping from 9Be to 181Ta, 169Tm, 187Re and at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Fang, Y. D.; Gomes, P. R. S.; Lubian, J.; Ferreira, J. L.; Mendes Junior, D. R.; Zhou, X. H.; Liu, M. L.; Zhang, N. T.; Zhang, Y. H.; Li, G. S.; Wang, J. G.; Guo, S.; Qiang, Y. H.; Gao, B. S.; Zheng, Y.; Lei, X. G.; Wang, Z. G.

    2016-03-01

    We report the measurement of one-neutron stripping of 9Be to the 181Ta, 187Re and nuclei, in the range from subbarrier to above-barrier energies. The activation technique was used, with the detection of off-line γ rays. The results show that the transfer cross sections for the three systems investigated are very similar and are much larger than the corresponding fusion cross sections at subbarrier energies, whereas fusion predominates at energies above the barrier. Data are in good agreement with our coupled reaction channel calculations. We also investigate the ratio, as a function of energy, between experimental transfer and fusion cross sections. The role of transfer couplings on the fusion excitation functions is also discussed.

  15. Relative Gibbs energies in solution through continuum models: effect of the loss of translational degrees of freedom in bimolecular reactions on Gibbs energy barriers.

    PubMed

    Ardura, Diego; López, Ramón; Sordo, Tomás L

    2005-12-15

    We present here a cell model for evaluating Gibbs energy barriers corresponding to bimolecular reactions (or processes of larger molecularity) in which a loss of translational degrees of freedom takes place along the reaction coordinate. With this model, we have studied the Walden inversion processes: Xa- + H3CXb --> XaCH3 + Xb- (X = F, Cl, Br, and I). In these processes, our model yields an increase of about 2.3-3.4 kcal/mol in Gibbs energy in solution corresponding to the loss of the translational degrees of freedom when passing from separate reactants to the TS in good agreement with experimental data. The corresponding value in the gas phase is about 6.7-7.1 kcal/mol. When the difference between these two figures is used to correct the results obtained by the standard UAHF implementation of the continuum model, the theoretical results are brought significantly closer to the experimental ones. This seems to indicate that for these reactions the parametrization used does not adequately introduce the increase in Gibbs energy corresponding to the constriction of the translational motion of the species along the reaction coordinate when passing from the gas phase to solution. Therefore, we believe that continuum models could perform much better if we released the parametrization process from the task of taking into account the constriction in translation motion in solution, which could be more adequately evaluated using the cell model proposed here, thus allowing it to focus on better reproducing all the remaining solvation effects.

  16. Installed Cost Benchmarks and Deployment Barriers for Residential Solar Photovoltaics with Energy Storage: Q1 2016

    SciTech Connect

    Ardani, Kristen; O'Shaughnessy, Eric; Fu, Ran; McClurg, Chris; Huneycutt, Joshua; Margolis, Robert

    2016-12-01

    In this report, we fill a gap in the existing knowledge about PV-plus-storage system costs and value by providing detailed component- and system-level installed cost benchmarks for residential systems. We also examine other barriers to increased deployment of PV-plus-storage systems in the residential sector. The results are meant to help technology manufacturers, installers, and other stakeholders identify cost-reduction opportunities and inform decision makers about regulatory, policy, and market characteristics that impede solar plus storage deployment. In addition, our periodic cost benchmarks will document progress in cost reductions over time. To analyze costs for PV-plus-storage systems deployed in the first quarter of 2016, we adapt the National Renewable Energy Laboratory's component- and system-level cost-modeling methods for standalone PV. In general, we attempt to model best-in-class installation techniques and business operations from an installed-cost perspective. In addition to our original analysis, model development, and review of published literature, we derive inputs for our model and validate our draft results via interviews with industry and subject-matter experts. One challenge to analyzing the costs of PV-plus-storage systems is choosing an appropriate cost metric. Unlike standalone PV, energy storage lacks universally accepted cost metrics, such as dollars per watt of installed capacity and lifetime levelized cost of energy. We explain the difficulty of arriving at a standard approach for reporting storage costs and then provide the rationale for using the total installed costs of a standard PV-plus-storage system as our primary metric, rather than using a system-size-normalized metric.

  17. Hyperosmolar opening of the blood-brain barrier in the energy-depleted rat brain. Part 1. Permeability studies

    SciTech Connect

    Greenwood, J.; Luthert, P.J.; Pratt, O.E.; Lantos, P.L.

    1988-02-01

    A simple saline perfusion system was used to investigate the effects of hyperosmolar solutions of arabinose and mannitol upon the permeability of the blood-brain barrier. The small, polar molecule (/sup 14/C)mannitol and the larger, visual marker Evans blue were used as indicators of barrier integrity in the perfused energy-depleted brain. One-minute perfusion of hyperosmolar solutions consistently opened the barrier suggesting that the mechanism of osmotic barrier opening is independent of energy-producing metabolism. The accumulation of radiolabel in the brain was expressed as the ratio of tissue to perfusate radioactivity (Rt/Rp) and, for cerebrum, this increased from a control value of 0.0022 +/- 0.0007 (mean +/- SEM; n = 4) to a value of 0.0124 +/- 0.0008 (n = 4) following 0.9 M arabinose and to 0.0495 +/- 0.0072 (n = 4) following 1.8 M arabinose. There was a significant reduction of water content of hyperosmolar perfused brains. These findings support the hypothesis that osmotic barrier opening is the result of the passive shrinkage of endothelial cells and the surrounding tissue.

  18. US-China Clean Energy Research Center on Building Energy Efficiency: Materials that Improve the Cost-Effectiveness of Air Barrier Systems

    SciTech Connect

    Hun, Diana E.

    2016-12-01

    The US–China Clean Energy Research Center (CERC) was launched in 2009 by US Energy Secretary Steven Chu, Chinese Minister of Science and Technology Wan Gang, and Chinese National Energy Agency Administrator Zhang Guobao. This 5-year collaboration emerged from the fact that the United States and China are the world’s largest energy producers, energy consumers, and greenhouse gas emitters, and that their joint effort could have significant positive repercussions worldwide. CERC’s main goal is to develop and deploy clean energy technologies that will help both countries meet energy and climate challenges. Three consortia were established to address the most pressing energy-related research areas: Advanced Coal Technology, Clean Vehicles, and Building Energy Efficiency (BEE). The project discussed in this report was part of the CERC-BEE consortia; its objective was to lower energy use in buildings by developing and evaluating technologies that improve the cost-effectiveness of air barrier systems for building envelopes.

  19. Regional Differences as Barriers to Body Mass Index Screening Described by Ohio School Nurses

    ERIC Educational Resources Information Center

    Stalter, Ann M.; Chaudry, Rosemary V.; Polivka, Barbara J.

    2011-01-01

    Background: Body mass index (BMI) screening is advocated by the National Association of School Nurses (NASN). Research identifying barriers to BMI screening in public elementary school settings has been sparse. The purpose of the study was to identify barriers and facilitating factors of BMI screening practices among Ohio school nurses working in…

  20. Impact of compliance with different guidelines on physical activity during pregnancy and perceived barriers to leisure physical activity.

    PubMed

    Santos, Paula Clara; Abreu, Sandra; Moreira, Carla; Lopes, Diana; Santos, Rute; Alves, Odete; Silva, Pedro; Montenegro, Nuno; Mota, Jorge

    2014-01-01

    The aims of the this prospective study were to analyse physical activity (PA) engagement during the first and second trimesters, considering the different guidelines published on PA, to document the individual characteristics associated with the accomplishment of these guidelines and to examine pregnant women's perceived barriers to leisure PA, using a socioecological framework. A sample of 133 pregnant women in two stages--at 10-12 weeks' gestation (T1) and 20-22 weeks' gestation (T2)--were evaluated. PA was assessed by accelerometry during the T1 and T2 evaluation stages. Socio-demographic characteristics, lifestyle factors and barriers to leisure PA were assessed via questionnaire. A large proportion of women (ranging from 32% to 96%) did not reach the levels of PA recommended by the guidelines. There were no significant differences between T1 and T2 with regard to compliance with PA recommendations. A decrease in PA levels from T1 to T2 was noted for all recommendations. No associations were found between participants' characteristics and adherence to the recommendations in T1 and T2. No significant differences were found in barriers to leisure PA between T1 and T2. The most commonly reported barriers to leisure PA were intrapersonal, not health related. Our results indicate that there were no differences between trimesters regarding compliance of PA recommendations, and perceived barriers were similar in both trimesters.

  1. Enhancing the effective energy barrier of a Dy(III) SMM using a bridged diamagnetic Zn(II) ion.

    PubMed

    Upadhyay, Apoorva; Singh, Saurabh Kumar; Das, Chinmoy; Mondol, Ranajit; Langley, Stuart K; Murray, Keith S; Rajaraman, Gopalan; Shanmugam, Maheswaran

    2014-08-18

    Field induced single-molecule-magnet behaviour is observed for both a heterodinuclear [ZnDy(L(-))2](3+) complex (1) and a mononuclear [Dy(HL)2](3+) complex (2), with effective energy barriers of 83 cm(-1) and 16 cm(-1), respectively. Insights into the relaxation mechanism(s) and barrier heights are provided via ab initio and DFT calculations. Our findings reveal an interesting observation that the U(eff) of SMMs can be enhanced by incorporating diamagnetic metal ions.

  2. Free-Energy Barrier of Filling a Spherical Cavity in the Presence of Line Tension: Implication to the Energy Barrier between the Cassie and Wenzel States on a Superhydrophobic Surface with Spherical Cavities.

    PubMed

    Iwamatsu, Masao

    2016-09-20

    The free-energy barrier of filling a spherical cavity having an inner wall of various wettabilities is studied. The morphology and free energy of a lens-shaped droplet are determined from the minimum of the free energy. The effect of line tension on the free energy is also studied. Then, the equilibrium contact angle of the droplet is determined from the generalized Young's equation. By increasing the droplet volume within the spherical cavity, the droplet morphology changes from spherical with an equilibrium contact angle of 180° to a lens with a convex meniscus, where the morphological complete drying transition occurs. By further increasing the droplet volume, the meniscus changes from convex to concave. Then, the lens-shaped droplet with concave meniscus spreads over the whole inner wall, resulting in an equilibrium contact angle of 0° to leave a spherical bubble, where the morphological complete wetting transition occurs. Finally, the whole cavity is filled with liquid. The free energy shows a barrier from complete drying to complete wetting as a function of droplet volume, which corresponds to the energy barrier between the Cassie and Wenzel states of the superhydrophobic surface with spherical cavities. The free-energy maximum occurs when the meniscus of the droplet becomes flat, and it is given by an analytic formula. The effect of line tension is expressed by the scaled line tension, and this effect is largest at the free-energy maximum. The positive line tension increases the free-energy maximum, which thus increases the stability of the Cassie superhydrophobic state, whereas the negative line tension destabilizes the superhydrophobic state.

  3. Gender Differences in Barriers to Physical Activity among College Students Reporting Varying Levels of Regular Physical Activity

    ERIC Educational Resources Information Center

    Munford, Shawn N.

    2011-01-01

    Researchers have studied the primary determinants of physical activity in an effort to enhance health promotion initiatives nationwide. These physical activity determinants have been observed to differ among various segments of the population, suggesting a further examination of physical activity barriers among differing populations. Little…

  4. Transportation Energy Futures Series. Non-Cost Barriers to Consumer Adoption of New Light-Duty Vehicle Technologies

    SciTech Connect

    Stephens, Thomas

    2013-03-01

    Consumer preferences are key to the adoption of new vehicle technologies. Barriers to consumer adoption include price and other obstacles, such as limited driving range and charging infrastructure; unfamiliarity with the technology and uncertainty about direct benefits; limited makes and models with the technology; reputation or perception of the technology; standardization issues; and regulations. For each of these non-cost barriers, this report estimates an effective cost and summarizes underlying influences on consumer preferences, approximate magnitude and relative severity, and assesses potential actions, based on a comprehensive literature review. While the report concludes that non-cost barriers are significant, effective cost and potential market share are very uncertain. Policies and programs including opportunities for drivers to test drive advanced vehicles, general public outreach and information programs, incentives for providing charging and fueling infrastructure, and development of technology standards were examined for their ability to address barriers, but little quantitative data exists on the effectiveness of these measures. This is one in a series of reports produced as a result of the Transportation Energy Futures project, a Department of Energy-sponsored multi-agency effort to pinpoint underexplored strategies for reducing GHGs and petroleum dependence related to transportation. View all reports on the TEF Web page, http://www.eere.energy.gov/analysis/transportationenergyfutures/index.html.

  5. Surface charge measurements on different dielectrics in diffuse and filamentary barrier discharges

    NASA Astrophysics Data System (ADS)

    Tschiersch, R.; Nemschokmichal, S.; Bogaczyk, M.; Meichsner, J.

    2017-03-01

    Previously, we reported on the measurement of surface charges during the operation of barrier discharges (BDs) using the electro-optic Pockels effect of a bismuth silicon oxide (BSO) crystal. With the present work, the next milestone is achieved by making this powerful method accessible to various dielectrics which are typically used in BD configurations. The dynamics and spatial distribution of positive and negative surface charges were determined on optically transparent borosilicate glass, mono-crystalline alumina and magnesia, respectively, covering the BSO crystal. By variation of the nitrogen admixture to helium and the pressure between 500~\\text{mbar} and 1~\\text{bar} , both the diffuse glow-like BD and the self-stabilized discharge filaments were operated inside of a gas gap of 3~\\text{mm} . The characteristics of the discharge and, especially, the influence of the different dielectrics on its development were studied by surface charge diagnostics, electrical measurements and ICCD camera imaging. Regarding the glow-like BD, the breakdown voltage changes significantly by variation of the cathodic dielectric, due to the different effective secondary electron emission (SEE) coefficients. These material-specific SEE yields were estimated using Townsend’s criterion in combination with analytical calculations of the effective ionization coefficient in helium with air impurities. Moreover, the importance of the surface charge memory effect for the self-stabilization of discharge filaments was quantified by the recalculated spatio-temporal behavior of the gap voltage.

  6. Protein misfolding occurs by slow diffusion across multiple barriers in a rough energy landscape

    PubMed Central

    Yu, Hao; Dee, Derek R.; Liu, Xia; Brigley, Angela M.; Sosova, Iveta; Woodside, Michael T.

    2015-01-01

    The timescale for the microscopic dynamics of proteins during conformational transitions is set by the intrachain diffusion coefficient, D. Despite the central role of protein misfolding and aggregation in many diseases, it has proven challenging to measure D for these processes because of their heterogeneity. We used single-molecule force spectroscopy to overcome these challenges and determine D for misfolding of the prion protein PrP. Observing directly the misfolding of individual dimers into minimal aggregates, we reconstructed the energy landscape governing nonnative structure formation. Remarkably, rather than displaying multiple pathways, as typically expected for aggregation, PrP dimers were funneled into a thermodynamically stable misfolded state along a single pathway containing several intermediates, one of which blocked native folding. Using Kramers’ rate theory, D was found to be 1,000-fold slower for misfolding than for native folding, reflecting local roughening of the misfolding landscape, likely due to increased internal friction. The slow diffusion also led to much longer transit times for barrier crossing, allowing transition paths to be observed directly for the first time to our knowledge. These results open a new window onto the microscopic mechanisms governing protein misfolding. PMID:26109573

  7. Role of tunnelling in complete and incomplete fusion induced by 9Be on 169Tm and 187Re targets at around barrier energies

    NASA Astrophysics Data System (ADS)

    Kharab, Rajesh; Chahal, Rajiv; Kumar, Rajiv

    2017-04-01

    We have analyzed the complete and incomplete fusion excitation function for 9Be +169Tm, 187Re reactions at around barrier energies using the code PLATYPUS based on classical dynamical model. The quantum mechanical tunnelling correction is incorporated at near and sub barrier energies which significantly improves the matching between the data and prediction.

  8. Spectral Modeling of Residual Stress and Stored Elastic Strain Energy in Thermal Barrier Coatings

    SciTech Connect

    Donegan, Sean; Rolett, Anthony

    2013-12-31

    Solutions to the thermoelastic problem are important for characterizing the response under temperature change of refractory systems. This work extends a spectral fast Fourier transform (FFT) technique to analyze the thermoelastic behavior of thermal barrier coatings (TBCs), with the intent of probing the local origins of failure in TBCs. The thermoelastic FFT (teFFT) approach allows for the characterization of local thermal residual stress and strain fields, which constitute the origins of failure in TBC systems. A technique based on statistical extreme value theory known as peaks-over-threshold (POT) is developed to quantify the extreme values ("hot spots") of stored elastic strain energy (i.e., elastic energy density, or EED). The resolution dependence of the teFFT method is assessed through a sensitivity study of the extreme values in EED. The sensitivity study is performed both for the local (point-by-point) eld distributions as well as the grain scale eld distributions. A convergence behavior to a particular distribution shape is demonstrated for the local elds. The grain scale fields are shown to exhibit a possible convergence to a maximum level of EED. To apply the teFFT method to TBC systems, 3D synthetic microstructures are created to approximate actual TBC microstructures. The morphology of the grains in each constituent layer as well as the texture is controlled. A variety of TBC materials, including industry standard materials and potential future materials, are analyzed using the teFFT. The resulting hot spots are quantified using the POT approach. A correlation between hot spots in EED and interface rumpling between constituent layers is demonstrated, particularly for the interface between the bond coat (BC) and the thermally grown oxide (TGO) layer.

  9. Quasi-elastic scattering and transfer angular distribution for B,1110+232Th systems at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Dubey, Shradha; Biswas, D. C.; Mukherjee, S.; Patel, D.; Gupta, Y. K.; Prajapati, G. K.; Joshi, B. N.; Danu, L. S.; Mukhopadhyay, S.; John, B. V.; Suryanarayana, S. V.; Vind, R. P.

    2016-12-01

    Quasi-elastic scattering and transfer angular distributions for B,1110+232Th reactions have been measured simultaneously in a wide range of bombarding energies around the Coulomb barrier. The quasi-elastic angular distribution data are analyzed using the optical model code ecis with phenomenological Woods-Saxon potentials. The obtained potential parameters suggest the presence of usual threshold anomaly, confirming tightly bound characteristics for both the projectiles. The reaction cross sections are obtained from the fitting of quasi-elastic angular distribution data. The reduced cross sections at sub-barrier energies compared with Li,76+232Th systems show a systematic dependence on projectile breakup energy. The angular distribution of the transfer products show similar behavior for both the systems.

  10. Degradation of organic pollutants and microorganisms from wastewater using different dielectric barrier discharge configurations--a critical review.

    PubMed

    Mouele, Emile S Massima; Tijani, Jimoh O; Fatoba, Ojo O; Petrik, Leslie F

    2015-12-01

    The growing global drinking water crisis requires the development of novel advanced, sustainable, and cost-effective water treatment technologies to supplement the existing conventional methods. One such technology is advanced oxidation based on dielectric barrier discharge (DBD). DBD such as single and double planar and single and double cylindrical dielectric barrier configurations have been utilized for efficient degradation of recalcitrant organic pollutants. The overall performance of the different DBD system varies and depends on several factors. Therefore, this review was compiled to give an overview of different DBD configurations vis-a-viz their applications and the in situ mechanism of generation of free reactive species for water and wastewater treatment. Our survey of the literature indicated that application of double cylindrical dielectric barrier configuration represents an ideal and viable route for achieving greater water and wastewater purification efficiency.

  11. Effects of different disturbance types on butterflyfish communities of Australia's Great Barrier Reef

    NASA Astrophysics Data System (ADS)

    Emslie, M. J.; Pratchett, M. S.; Cheal, A. J.

    2011-06-01

    The effects of disturbances on coral reef fishes have been extensively documented but most studies have relied on opportunistic sampling following single events. Few studies have the spatial and temporal extent to directly compare the effects of multiple disturbances over a large geographic scale. Here, benthic communities and butterflyfishes on 47 reefs of the Great Barrier Reef were surveyed annually to examine their responses to physical disturbances (cyclones and storms) and/or biological disturbances (bleaching, outbreaks of crown-of-thorns starfish and white syndrome disease). The effects on benthic and butterflyfish communities varied among reefs depending on the structure and geographical setting of each community, on the size and type of disturbance, and on the disturbance history of that reef. There was considerable variability in the response of butterflyfishes to different disturbances: physical disturbances (occurring with or without biological disturbances) produced substantial declines in abundance, whilst biological disturbances occurring on their own did not. Butterflyfishes with the narrowest feeding preferences, such as obligate corallivores, were always the species most affected. The response of generalist feeders varied with the extent of damage. Wholesale changes to the butterflyfish community were only recorded where structural complexity of reefs was drastically reduced. The observed effects of disturbances on butterflyfishes coupled with predictions of increased frequency and intensity of disturbances sound a dire warning for the future of butterflyfish communities in particular and reef fish communities in general.

  12. Comparison of the surface dielectric barrier discharge characteristics under different electrode gaps

    NASA Astrophysics Data System (ADS)

    Gao, Guoqiang; Dong, Lei; Peng, Kaisheng; Wei, Wenfu; Li, Chunmao; Wu, Guangning

    2017-01-01

    Currently, great interests are paid to the surface dielectric barrier discharge due to the diverse and interesting application. In this paper, the influences of the electrode gap on the discharge characteristics have been studied. Aspects of the electrical parameters, the optical emission, and the discharge induced gas flow were considered. The electrode gap varied from 0 mm to 21 mm, while the applied AC voltage was studied in the range of 17 kV-27 kV. Results indicate that with the increase of the electrode gap, the variation of discharge voltage exhibits an increasing trend, while the other parameters (i.e., the current, power, and induced flow velocity) increase first, and then decrease once the gap exceeded the critical value. Mechanisms of the electrode gap influencing these key parameters were discussed from the point of equivalent circuit. The experimental results reveal that an optimal discharge gap can be obtained, which is closely related to the applied voltage. Visualization of the induced flow with different electrode gaps was realized by the Schlieren diagnostic technique. Finally, the velocities of induced gas flow determined by the pitot tube were compared with the results of intensity-integral method, and good agreements were found.

  13. Effect of four different reflective barriers on black-globe temperatures in calf hutches.

    PubMed

    Friend, T H; Haberman, J A; Binion, W R

    2014-12-01

    Polyethylene hutches are a popular method of housing dairy calves from 0 to 60 or more days of age, although these hutches get hot when in full sun. This study characterized the relative differences in the ability of four different types of radiant barriers to reduce black-globe temperature within these hutches. Treatments included three different types of covers (two types of laminates (Cadpak P and Cadpak ESD) and an aluminized 3.0-mil white low-density polyethylene (LDPE)) and a reflective paint (LO/MIT-1). The reflective covers were 1.8 × 3 m finished size, and covered the top and sides of the hutch down to 0.15 m above the ground, leaving the front and back exposed. The LO/MIT-1 paint covered the entire sides and roof of the hutch. Two 24-h trials 1 week apart were conducted during relatively hot and clear days in early August. Black-globe temperatures were recorded in duplicate and averaged at 20-min intervals using blackened table tennis balls mounted 0.3 m above the floor in the center of each hutch. Ambient temperature (shade) during the hottest 2-h period for both trials averaged 39.9 °C while the uncovered control averaged 41.1 °C, and LO/MIT-1 averaged 39.9 °C; both of which were significantly higher (P < 0.01) than the Cadpak P (38.9 °C), Cadpak ESD (38.6 °C), and aluminized LDPE (38.7 °C). During periods of high solar radiation, the hutches with covers had lowest black-globe temperatures followed by hutches painted with reflective paint, while control hutches had the highest temperature.

  14. Effect of four different reflective barriers on black-globe temperatures in calf hutches

    NASA Astrophysics Data System (ADS)

    Friend, T. H.; Haberman, J. A.; Binion, W. R.

    2014-12-01

    Polyethylene hutches are a popular method of housing dairy calves from 0 to 60 or more days of age, although these hutches get hot when in full sun. This study characterized the relative differences in the ability of four different types of radiant barriers to reduce black-globe temperature within these hutches. Treatments included three different types of covers (two types of laminates (Cadpak P and Cadpak ESD) and an aluminized 3.0-mil white low-density polyethylene (LDPE)) and a reflective paint (LO/MIT-1). The reflective covers were 1.8 × 3 m finished size, and covered the top and sides of the hutch down to 0.15 m above the ground, leaving the front and back exposed. The LO/MIT-1 paint covered the entire sides and roof of the hutch. Two 24-h trials 1 week apart were conducted during relatively hot and clear days in early August. Black-globe temperatures were recorded in duplicate and averaged at 20-min intervals using blackened table tennis balls mounted 0.3 m above the floor in the center of each hutch. Ambient temperature (shade) during the hottest 2-h period for both trials averaged 39.9 °C while the uncovered control averaged 41.1 °C, and LO/MIT-1 averaged 39.9 °C; both of which were significantly higher ( P < 0.01) than the Cadpak P (38.9 °C), Cadpak ESD (38.6 °C), and aluminized LDPE (38.7 °C). During periods of high solar radiation, the hutches with covers had lowest black-globe temperatures followed by hutches painted with reflective paint, while control hutches had the highest temperature.

  15. Measuring the Fusion Cross-Section of 18,19 O + 12 C with Low-Intensity Beams at Energies Near and Below the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Steinbach, Tracy; Vadas, Justin; Schmidt, Jon; Singh, Varinderjit; Hudan, Sylvie; Desouza, Romualdo; Baby, Lagy; Kuvin, Sean; Wiedenhover, Ingo; Umar, Sait; Oberacker, Volker

    2015-04-01

    Fusion of neutron-rich light nuclei has been proposed as a heat source that triggers an X-ray superburst in the crust of an accreting neutron star. To investigate this hypothesis the total fusion cross-section for beams of low-intensity, neutron-rich nuclei (<105 ions/s) on light targets has been measured at energies near and below the Coulomb barrier. Evaporation residues, resulting from the fusion of oxygen and 12 C nuclei, were identified by their energy and Time-of-flight. Using this technique, the fusion excitation function was measured in the sub-barrier domain down to the 2 mb level. Comparison of the measured fusion excitation function with the predictions of a density constrained TDHF model reveals that the experimental data exhibit a smaller decrease in cross-section with decreasing energy than is theoretically predicted. This difference can be interpreted as a larger tunneling probability for the experimental data as compared to the theoretical predictions. To determine if this difference increases in magnitude with decreasing incident energy improvements have been implemented to enable measurement of the fusion cross-section to an even lower level. Supported by the US DOE under Grand No. DEFG02-88ER-40404.

  16. Transportation Energy Futures Series: Non-Cost Barriers to Consumer Adoption of New Light-Duty Vehicle Technologies

    SciTech Connect

    Stephens, T.

    2013-03-01

    Consumer preferences are key to the adoption of new vehicle technologies. Barriers to consumer adoption include price and other obstacles, such as limited driving range and charging infrastructure; unfamiliarity with the technology and uncertainty about direct benefits; limited makes and models with the technology; reputation or perception of the technology; standardization issues; and regulations. For each of these non-cost barriers, this report estimates an effective cost and summarizes underlying influences on consumer preferences, approximate magnitude and relative severity, and assesses potential actions, based on a comprehensive literature review. While the report concludes that non-cost barriers are significant, effective cost and potential market share are very uncertain. Policies and programs including opportunities for drivers to test drive advanced vehicles, general public outreach and information programs, incentives for providing charging and fueling infrastructure, and development of technology standards were examined for their ability to address barriers, but little quantitative data exists on the effectiveness of these measures. This is one in a series of reports produced as a result of the Transportation Energy Futures project, a Department of Energy-sponsored multi-agency effort to pinpoint underexplored strategies for reducing GHGs and petroleum dependence related to transportation.

  17. Influence of a channel-forming peptide on energy barriers to ion permeation, viewed from a continuum dielectric perspective.

    PubMed Central

    Partenskii, M B; Dorman, V; Jordan, P C

    1994-01-01

    The continuum three-dielectric model for an aqueous ion channel pore-forming peptide-membrane system is extended to account for the finite length of the channel. We focus on the electrostatic influence that a channel-forming peptide may exert on energy barriers to ion permeation. The nonlinear dielectric behavior of channel water caused by dielectric saturation in the presence of an ion is explicitly modeled by assigning channel water a mean dielectric constant much less than that of bulk water. An exact solution of the continuum problem is formulated by approximating the dielectric behavior of bulk water, assigning it a dielectric constant of infinity. The validity of this approximation is verified by comparison with a Poisson-Boltzmann description of the electrolyte. The formal equivalence of high ionic strength and high electrolyte dielectric constant is demonstrated. We estimate limits on the reduction of the electrostatic free energy caused by ionic interaction with the channel-forming peptide. We find that even assigning this region an epsilon of 100, its influence is insufficient to lower permeation free energy barriers to values consistent with observed channel conductances. We provide estimates of the effective dielectric constant of this highly polarizable region, by comparing energy barriers computed using the continuum approach with those found from a semi-microscopic analysis of a simplified model of a gramicidin-like charge distribution. Possible ways of improving both models are discussed. PMID:7529581

  18. Differences in Perceptions of Barriers to College Enrollment and the Completion of a Degree among Latinos in the United States

    ERIC Educational Resources Information Center

    Becerra, David

    2010-01-01

    This study examined the differences in perceptions of barriers in education among Latinos in the United States based on the level of linguistic acculturation, generational status, academic achievement, and socioeconomic status of the participants. This study used data from the Pew Hispanic Research Center. Results indicated that later-generation…

  19. Female and Male Juvenile Offenders with Disabilities: Differences in the Barriers to Their Transition to the Community

    ERIC Educational Resources Information Center

    Unruh, Deanne; Bullis, Michael

    2005-01-01

    This article examined differences between young women and men who were incarcerated juvenile offenders with disabilities in Oregon in terms of the barriers they faced in their transition from the correctional system back into the community. Data were gathered on 72 females and 276 males, all of whom presented disabilities and who were…

  20. A four-coordinate cobalt(II) single-ion magnet with coercivity and a very high energy barrier

    PubMed Central

    Rechkemmer, Yvonne; Breitgoff, Frauke D.; van der Meer, Margarethe; Atanasov, Mihail; Hakl, Michael; Orlita, Milan; Neugebauer, Petr; Sarkar, Biprajit; van Slageren, Joris

    2016-01-01

    Single-molecule magnets display magnetic bistability of molecular origin, which may one day be exploited in magnetic data storage devices. Recently it was realised that increasing the magnetic moment of polynuclear molecules does not automatically lead to a substantial increase in magnetic bistability. Attention has thus increasingly focussed on ions with large magnetic anisotropies, especially lanthanides. In spite of large effective energy barriers towards relaxation of the magnetic moment, this has so far not led to a big increase in magnetic bistability. Here we present a comprehensive study of a mononuclear, tetrahedrally coordinated cobalt(II) single-molecule magnet, which has a very high effective energy barrier and displays pronounced magnetic bistability. The combined experimental-theoretical approach enables an in-depth understanding of the origin of these favourable properties, which are shown to arise from a strong ligand field in combination with axial distortion. Our findings allow formulation of clear design principles for improved materials. PMID:26883902

  1. Colloid Retention in Porous Media in the Presence of Energy Barriers: Hemispheres-in-Cell Model with Heterogeneity

    NASA Astrophysics Data System (ADS)

    Ma, H.; Pazmino, E. F.; Johnson, W. P.

    2010-12-01

    Experimental evidences indicate that surface heterogeneities (charge and/or roughness) play an important role in colloidal retention in porous media under conditions when colloid-surface repulsion exists, at least for colloids of relatively small sizes (e.g. about 2 microns or less). Hence, we have incorporated surface charge heterogeneity into our recently delevoped hemispheres-in-cell model, with an aim to have a better understanding of colloid retention mechanisms in the presence of repulsive energy barriers via numerically simulating the transport and deposition behavior of different size colloids under the coupled effect of heterogeneity, pore structure (e.g. grain to grain contacts), fluid hydrodynamics, etcetera. Here we describe the strategies employed to account for heterogenously charged collector surfaces in the hemispheres-in-cell model so as to correctly compute the colloid-surface internation forces, and then present preliminary results obtained from this model on colloidal retention under various coverage of heterogenous attractive domains over the collector surfaces.

  2. A multilayer ΔE-E R telescope for breakup reactions at energies around the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Ma, Nan-Ru; Lin, Cheng-Jian; Wang, Jian-Song; Yang, Lei; Wang, Dong-Xi; Zheng, Lei; Xu, Shi-Wei; Sun, Li-Jie; Jia, Hui-Ming; Ma, Jun-Bing; Ma, Peng; Jin, Shi-Lun; Bai, Zhen; Yang, Yan-Yun; Xu, Xin-Xing; Zhang, Gao-Long; Yang, Feng; He, Jian-Jun; Zhang, Huan-Qiao; Liu, Zu-Hua

    2016-11-01

    The breakup reactions of weakly-bound nuclei at energies around the Coulomb barrier and the corresponding coupling effect on the other reaction channels are hot topics nowadays. To overcome the difficulty in identifying both heavier and lighter fragments simultaneously, a new kind of ionization-chamber based detector telescope has been designed and manufactured. It consists of a PCB ionization chamber and three different thickness silicon detectors installed inside the chamber, which form a multilayer ΔE-E R telescope. The working conditions were surveyed by using an α source. An in-beam test experiment shows that the detector has good particle identification for heavy particles like 17F and 16O as well as light particles like protons and alpha particles. The measured quasi-elastic scattering angular distribution and the related discussions for 17F+208Pb are presented. Supported by National Key Basic Research Development Program of China (2013CB834404) and National Natural Science Foundation of China (11375268, 11475263, U1432127, U1432246).

  3. Market and behavioral barriers to energy efficiency: A preliminary evaluation of the case for tariff financing in California

    SciTech Connect

    Fujita, K. Sydny

    2011-06-23

    Consumers regularly forgo purchases of high efficiency appliances that appear to be cost effective at a reasonable rate of return. While some argue that this is a true revelation of preferences for appliance features, this 'efficiency gap' can be largely explained by a combination of market and behavioral failures that reduce consumers ability to evaluate the relative value of appliances and skew preferences toward initial cost savings, undervaluing future reductions in operating costs. These failures and barriers include externalities of energy use, imperfect competition between manufacturers, asymmetric information, bounded rationality, split incentives, and transaction costs (Golove 1996). Recognizing the social benefit of energy conservation, several major methods are used by policymakers to ensure that efficient appliances are purchased: minimum efficiency standards, Energy Star labeling, and rebates and tax credits. There is no single market for energy services; there are hundreds of uses, thousands of intermediaries, and millions of users, and likewise, no single appropriate government intervention (Golove 1996). Complementary approaches must be implemented, considering policy and institutional limitations. In this paper, I first lay out the rationale for government intervention by addressing the market and behavioral failures and barriers that arise in the context of residential energy efficiency. I then consider the ways in which some of these failures and barriers are addressed through major federal programs and state and utility level programs that leverage them, as well as identifying barriers that are not addressed by currently implemented programs. Heterogeneity of consumers, lack of financing options, and split incentives of landlords and tenants contribute significantly to the under-adoption of efficient appliances. To quantify the size of the market most affected by these barriers, I estimate the number of appliances, and in particular the number

  4. Additive effects on the energy barrier for synaptic vesicle fusion cause supralinear effects on the vesicle fusion rate.

    PubMed

    Schotten, Sebastiaan; Meijer, Marieke; Walter, Alexander Matthias; Huson, Vincent; Mamer, Lauren; Kalogreades, Lawrence; ter Veer, Mirelle; Ruiter, Marvin; Brose, Nils; Rosenmund, Christian; Sørensen, Jakob Balslev; Verhage, Matthijs; Cornelisse, Lennart Niels

    2015-04-14

    The energy required to fuse synaptic vesicles with the plasma membrane ('activation energy') is considered a major determinant in synaptic efficacy. From reaction rate theory, we predict that a class of modulations exists, which utilize linear modulation of the energy barrier for fusion to achieve supralinear effects on the fusion rate. To test this prediction experimentally, we developed a method to assess the number of releasable vesicles, rate constants for vesicle priming, unpriming, and fusion, and the activation energy for fusion by fitting a vesicle state model to synaptic responses induced by hypertonic solutions. We show that complexinI/II deficiency or phorbol ester stimulation indeed affects responses to hypertonic solution in a supralinear manner. An additive vs multiplicative relationship between activation energy and fusion rate provides a novel explanation for previously observed non-linear effects of genetic/pharmacological perturbations on synaptic transmission and a novel interpretation of the cooperative nature of Ca(2+)-dependent release.

  5. Ab initio calculations of stationary points on the benzene-Ar and p-difluorobenzene-Ar potential energy surfaces: barriers to bound orbiting states.

    PubMed

    Moulds, Rebecca J; Buntine, Mark A; Lawrance, Warren D

    2004-09-08

    The potential energy surfaces of the van der Waals complexes benzene-Ar and p-difluorobenzene-Ar have been investigated at the second-order Møller-Plesset (MP2) level of theory with the aug-cc-pVDZ basis set. Calculations were performed with unconstrained geometry optimization for all stationary points. This study has been performed to elucidate the nature of a conflict between experimental results from dispersed fluorescence and velocity map imaging (VMI). The inconsistency is that spectra for levels of p-difluorobenzene-Ar and -Kr below the dissociation thresholds determined by VMI show bands where free p-difluorobenzene emits, suggesting that dissociation is occurring. We proposed that the bands observed in the dispersed fluorescence spectra are due to emission from states in which the rare gas atom orbits the aromatic chromophore; these states are populated by intramolecular vibrational redistribution from the initially excited level [S. M. Bellm, R. J. Moulds, and W. D. Lawrance, J. Chem. Phys. 115, 10709 (2001)]. To test this proposition, stationary points have been located on both the benzene-Ar and p-difluorobenzene-Ar potential energy surfaces (PESs) to determine the barriers to this orbiting motion. Comparison with previous single point CCSD(T) calculations of the benzene-Ar PES has been used to determine the amount by which the barriers are overestimated at the MP2 level. As there is little difference in the comparable regions of the benzene-Ar and p-difluorobenzene-Ar PESs, the overestimation is expected to be similar for p-difluorobenzene-Ar. Allowing for this overestimation gives the barrier to movement of the Ar atom around the pDFB ring via the valley between the H atoms as < or = 204 cm(-1) in S0 (including zero point energy). From the estimated change upon electronic excitation, the corresponding barrier in S1 is estimated to be < or = 225 cm(-1). This barrier is less than the 240 cm(-1) energy of 30(2), the vibrational level for which the

  6. EFFECTS OF NUCLEAR INDUCED BREAKUP ON THE FUSION OF 6Li+12C AND 6He+12C SYSTEMS AROUND BARRIER ENERGIES

    NASA Astrophysics Data System (ADS)

    Duhan, Sukhvinder S.; Singh, Manjeet; Kharab, Rajesh

    2012-06-01

    We have studied the effects of nuclear induced breakup channel coupling on the fusion cross-section for 6Li+12C and 6He+12C systems in the near barrier energy regime using the dynamic polarization potential (DPP) approach. It has been found that there is enhancement in the fusion cross-section with respect to standard one-dimensional barrier penetration model in the below barrier energy regime while at energies above the barrier there is suppression of fusion cross-section with respect to simple barrier penetration model is observed. The agreement between data and predictions for 6Li+12C system improves significantly as a result of the inclusion of nuclear induced DPP.

  7. How Accurate Are the Minnesota Density Functionals for Noncovalent Interactions, Isomerization Energies, Thermochemistry, and Barrier Heights Involving Molecules Composed of Main-Group Elements?

    PubMed

    Mardirossian, Narbe; Head-Gordon, Martin

    2016-09-13

    The 14 Minnesota density functionals published between the years 2005 and early 2016 are benchmarked on a comprehensive database of 4986 data points (84 data sets) involving molecules composed of main-group elements. The database includes noncovalent interactions, isomerization energies, thermochemistry, and barrier heights, as well as equilibrium bond lengths and equilibrium binding energies of noncovalent dimers. Additionally, the sensitivity of the Minnesota density functionals to the choice of basis set and integration grid is explored for both noncovalent interactions and thermochemistry. Overall, the main strength of the hybrid Minnesota density functionals is that the best ones provide very good performance for thermochemistry (e.g., M06-2X), barrier heights (e.g., M08-HX, M08-SO, MN15), and systems heavily characterized by self-interaction error (e.g., M06-2X, M08-HX, M08-SO, MN15), while the main weakness is that none of them are state-of-the-art for the full spectrum of noncovalent interactions and isomerization energies (although M06-2X is recommended from the 10 hybrid Minnesota functionals). Similarly, the main strength of the local Minnesota density functionals is that the best ones provide very good performance for thermochemistry (e.g., MN15-L), barrier heights (e.g., MN12-L), and systems heavily characterized by self-interaction error (e.g., MN12-L and MN15-L), while the main weakness is that none of them are state-of-the-art for the full spectrum of noncovalent interactions and isomerization energies (although M06-L is clearly the best from the four local Minnesota functionals). As an overall guide, M06-2X and MN15 are perhaps the most broadly useful hybrid Minnesota functionals, while M06-L and MN15-L are perhaps the most broadly useful local Minnesota functionals, although each has different strengths and weaknesses.

  8. Applying Risk Science and Stakeholder Engagement to Overcome Environmental Barriers to Marine and Hydrokinetic Energy Projects

    SciTech Connect

    Copping, Andrea E.; Anderson, Richard M.; Van Cleve, Frances B.

    2010-09-20

    The production of electricity from the moving waters of the ocean has the potential to be a viable addition to the portfolio of renewable energy sources worldwide. The marine and hydrokinetic (MHK) industry faces many hurdles, including technology development, challenges of offshore deployments, and financing; however, the barrier most commonly identified by industry, regulators, and stakeholders is the uncertainty surrounding potential environmental effects of devices placed in the water and the permitting processes associated with real or potential impacts. Regulatory processes are not well positioned to judge the severity of harm due to turbines or wave generators. Risks from MHK devices to endangered or protected animals in coastal waters and rivers, as well as the habitats that support them, are poorly understood. This uncertainty raises concerns about catastrophic interactions between spinning turbine blades or slack mooring lines and marine mammals, birds and fish. In order to accelerate the deployment of tidal and wave devices, there is a need to sort through the extensive list of potential interactions that may cause harm to marine organisms and ecosystems, to set priorities for regulatory triggers, and to direct future research. Identifying the risk of MHK technology components on specific marine organisms and ecosystem components can separate perceived from real risk-relevant interactions. Scientists from Pacific Northwest National Laboratory (PNNL) are developing an Environmental Risk Evaluation System (ERES) to assess environmental effects associated with MHK technologies and projects through a systematic analytical process, with specific input from key stakeholder groups. The array of stakeholders interested in the development of MHK is broad, segmenting into those whose involvement is essential for the success of the MHK project, those that are influential, and those that are interested. PNNL and their partners have engaged these groups, gaining

  9. Intermediate-band photosensitive device with quantum dots embedded in energy fence barrier

    DOEpatents

    Forrest, Stephen R.; Wei, Guodan

    2010-07-06

    A plurality of layers of a first semiconductor material and a plurality of dots-in-a-fence barriers disposed in a stack between a first electrode and a second electrode. Each dots-in-a-fence barrier consists essentially of a plurality of quantum dots of a second semiconductor material embedded between and in direct contact with two layers of a third semiconductor material. Wave functions of the quantum dots overlap as at least one intermediate band. The layers of the third semiconductor material are arranged as tunneling barriers to require a first electron and/or a first hole in a layer of the first material to perform quantum mechanical tunneling to reach the second material within a respective quantum dot, and to require a second electron and/or a second hole in a layer of the first semiconductor material to perform quantum mechanical tunneling to reach another layer of the first semiconductor material.

  10. Assessing Understanding of the Energy Concept in Different Science Disciplines

    ERIC Educational Resources Information Center

    Park, Mihwa; Liu, Xiufeng

    2016-01-01

    Energy is one of the most central and richly connected ideas across all science disciplines. The purpose of this study was to develop a measurement instrument for assessing students' understanding of the energy concept within and across different science disciplines. To achieve this goal, the Inter-Disciplinary Energy concept Assessment (IDEA) was…

  11. Potential energy barriers for interlayer mass transport in homoepitaxial growth on fcc(111) surfaces: Pt and Ag

    NASA Astrophysics Data System (ADS)

    Li, Yinggang; DePristo, Andrew E.

    1994-11-01

    The efficiency of interlayer mass transport determines the growth mode and film quality in molecular beam epitaxy. In this paper we report potential energy barriers (PEB) to interlayer diffusion for Pt and Ag homoepitaxial growth on fcc (111) surfaces, as calculated using the corrected effective medium theory. Various island structures were considered. The island sizes ranged from 3- to about 60-atom islands and to various steps ("infinite" large islands). We found that jumping directly over the island edge has a much higher PEB than does the so-called displacement-exchange mechanism. Exchange at edges with kink sites also had a higher or comparable PEB to those at the straight (perfect) edges, contrary to previous speculations [M. Henzler, T. Schmidt and E.Z. Luo, in: The Structure of Surfaces IV (World Scientific, Signapore, 1994)]. The PEB depended strongly on the local atomic arrangement but was insensitive to the global island size and shape as long as the island edges were at least five atoms long. For the displacement-exchange process, the PEB did not decrease monotonically with decreasing island size over the entire island size range. For very small islands of less than ten atoms the PEB increased abruptly by an order of magnitude. This qualitative behavior was exhibited by both Pt and Ag systems but the two differed quantitatively for island sizes above ten atoms. We discuss the relevance of these results to the experimental observations, i.e., the reentrant growth in Pt [R. Kunkel, B. Poelsema, L.K. Verheij and G. Comsa, Phys. Rev. Lett. 65 (1990) 733], layer-by-layer growth in Ag induced by surfactant [H.A. van der Vegt, H.M. van Pinxteren, M. Lohmerier and E. Vlieg, Phys. Rev. Lett. 68 (1992) 3335] or by high-density of islands [G. Rosenfeld, R. Servaty, C. Teichert, B. Poelsema and G. Comsa, Phys. Rev. Lett. 71 (1993) 895 ], as well as the different growth behaviors found in the two systems.

  12. Hindrance of complete fusion in the {sup 8}Li+{sup 208}Pb system at above-barrier energies

    SciTech Connect

    Aguilera, E. F.; Martinez-Quiroz, E.; Rosales, P.; Kolata, J. J.; DeYoung, P. A.; Peaslee, G. F.; Mears, P.; Guess, C.; Becchetti, F. D.; Lupton, J. H.; Chen, Yu

    2009-10-15

    The {sup 211,212}At yields resulting from the interaction of the radioactive projectile {sup 8}Li with a {sup 208}Pb target have been measured at energies between 3 and 8.5 MeV above the Coulomb barrier. They are signatures for fusion of the whole charge but not necessarily the whole mass of the projectile, so they are included in a corresponding operational definition of complete fusion. Within this definition, a fusion suppression factor of 0.70{+-}0.02 (stat.) {+-}0.04 (syst.) is deduced from a comparison to a one-dimensional barrier-penetration-model calculation using parameters extrapolated from values for {sup 6,7}Li+{sup 209}Bi and {sup 9}Be+{sup 208}Pb taken from the literature. Possible incomplete fusion processes are discussed and the results are fitted with a phenomenological model assuming breakup prior to fusion followed by capture of a {sup 7}Li fragment.

  13. Analysis of Different Methods for Computing Source Energy in the Context of Zero Energy Buildings

    SciTech Connect

    Torcellini, Paul A.; Bonnema, Eric; Goldwasser, David; Pless, Shanti

    2016-08-26

    Building energy consumption can only be measured at the site or at the point of utility interconnection with a building. Often, to evaluate the total energy impact, this site-based energy consumption is translated into source energy, that is, the energy at the point of fuel extraction. Consistent with this approach, the U.S. Department of Energy's (DOE) definition of zero energy buildings uses source energy as the metric to account for energy losses from the extraction, transformation, and delivery of energy. Other organizations, as well, use source energy to characterize the energy impacts. Four methods of making the conversion from site energy to source energy were investigated in the context of the DOE definition of zero energy buildings. These methods were evaluated based on three guiding principles--improve energy efficiency, reduce and stabilize power demand, and use power from nonrenewable energy sources as efficiently as possible. This study examines relative trends between strategies as they are implemented on very low-energy buildings to achieve zero energy. A typical office building was modeled and variations to this model performed. The photovoltaic output that was required to create a zero energy building was calculated. Trends were examined with these variations to study the impacts of the calculation method on the building's ability to achieve zero energy status. The paper will highlight the different methods and give conclusions on the advantages and disadvantages of the methods studied.

  14. Survey of the Relationship Between Activity Energy Expenditure Metabolic Equivalents and Barrier Factors of Physical Activity in the Elderly in Kashan

    PubMed Central

    Sadrollahi, Ali; Khalili, Zahra; Pour Nazari, Robab; Mohammadi, Majid; Ahmadi Khatir, Maryam; Mossadegh, Najima

    2016-01-01

    Background Physical activity in the elderly is influenced by aspects of aging that cause personal, mental, environmental, and social changes. Increases in factors that are barriers to activity cause physical energy expenditure to decrease. Objectives The aim of the present study was to survey the relationship between energy expenditure in metabolic equivalent units (MET) and factors that are barriers to physical activity in elderly people in Kashan, Iran Methods This is a descriptive analysis done in 2014. The study population was 400 people above 60 years old in medical facilities in Kashan. Multistage sampling was used in 10 clinics in 5 areas of Kashan. The sample size was varied according to gender and elderly population. Contributors were given questionnaires concerning energy expenditure levels in physical activity and factors that are barriers to being active. Results The average age among the study population was 67.6 ± 6.8 years median, and the interquartile range (IQR) of barriers to physical activity among Kashan’s elderly was (8.75) ± 33. Average energy expenditure was 326.21 ± 364.84 based on metabolic equivalent units (MET). In fact, 340 persons (85%) were practically without any active energy expenditure. The most common barrier was the lack of an appropriate place for doing physical activity; 298 (74%) of the participants cited this barrier. The results show the Spearman rank-order correlation is significant (P = 0.038, r = 0.104) between barriers to physical activity and activity energy expenditure in Kashan’s elderly. Conclusions Decreasing barriers to physical activity among the elderly causes physical activities to increase; therefore, energy expenditure is increased. Decreasing social and environmental problems for the elderly is effective in increasing physical activity and energy expenditure. PMID:28191341

  15. Diabat Interpolation for Polymorph Free-Energy Differences.

    PubMed

    Kamat, Kartik; Peters, Baron

    2017-02-02

    Existing methods to compute free-energy differences between polymorphs use harmonic approximations, advanced non-Boltzmann bias sampling techniques, and/or multistage free-energy perturbations. This work demonstrates how Bennett's diabat interpolation method ( J. Comput. Phys. 1976, 22, 245 ) can be combined with energy gaps from lattice-switch Monte Carlo techniques ( Phys. Rev. E 2000, 61, 906 ) to swiftly estimate polymorph free-energy differences. The new method requires only two unbiased molecular dynamics simulations, one for each polymorph. To illustrate the new method, we compute the free-energy difference between face-centered cubic and body-centered cubic polymorphs for a Gaussian core solid. We discuss the justification for parabolic models of the free-energy diabats and similarities to methods that have been used in studies of electron transfer.

  16. Batteries for efficient energy extraction from a water salinity difference.

    PubMed

    La Mantia, Fabio; Pasta, Mauro; Deshazer, Heather D; Logan, Bruce E; Cui, Yi

    2011-04-13

    The salinity difference between seawater and river water is a renewable source of enormous entropic energy, but extracting it efficiently as a form of useful energy remains a challenge. Here we demonstrate a device called "mixing entropy battery", which can extract and store it as useful electrochemical energy. The battery, containing a Na(2-x)Mn(5)O(10) nanorod electrode, was shown to extract energy from real seawater and river water and can be applied to a variety of salt waters. We demonstrated energy extraction efficiencies of up to 74%. Considering the flow rate of river water into oceans as the limiting factor, the renewable energy production could potentially reach 2 TW, or ∼13% of the current world energy consumption. The mixing entropy battery is simple to fabricate and could contribute significantly to renewable energy in the future.

  17. The Effects of a High-Energy Diet on Hippocampal Function and Blood-Brain Barrier Integrity in the Rat

    PubMed Central

    Kanoski, Scott E.; Zhang, Yanshu; Zheng, Wei; Davidson, Terry L.

    2016-01-01

    Cognitive impairment and Alzheimer’s Disease are linked with intake of a Western Diet, characterized by high levels of saturated fats and simple carbohydrates. In rats, these dietary components have been shown to disrupt hippocampal-dependent learning and memory processes, particularly those involving spatial memory. Using a rat model, the present research assessed the degree to which consumption of a high-energy (HE) diet, similar to those found in modern Western cultures, produces a selective impairment in hippocampal function as opposed to a more global cognitive disruption. Learning and memory performance was examined following 90-days consumption of an HE-diet in three nonspatial discrimination learning problems that differed with respect to their dependence on the integrity of the hippocampus. The results showed that consumption of the HE-diet impaired performance in a hippocampal-dependent feature negative discrimination problem relative to chow-fed controls, whereas performance was spared on two discrimination problems that do not rely on the hippocampus. To explore the mechanism whereby consuming HE-diets impairs cognitive function, we investigated the effect of HE-diets on the integrity of the blood-brain barrier (BBB). We found that HE-diet consumption produced a decrease in mRNA expression of tight junction proteins, particularly Claudin-5 and -12, in the choroid plexus and the BBB. Consequently, an increased blood-to-brain permeability of sodium fluorescein was observed in the hippocampus, but not in the striatum and prefrontal cortex following HE-diet access. There results indicate that hippocampal function may be particularly vulnerable to disruption by HE-diets, and this disruption may be related to impaired BBB integrity. PMID:20413889

  18. Barrier-Independent, Fitness-Associated Differences in Sofosbuvir Efficacy against Hepatitis C Virus

    PubMed Central

    Gallego, Isabel; Sheldon, Julie; Moreno, Elena; Gregori, Josep; Quer, Josep; Esteban, Juan Ignacio; Rice, Charles M.; Domingo, Esteban

    2016-01-01

    Sofosbuvir displays a high phenotypic barrier to resistance, and it is a component of several combination therapies for hepatitis C virus (HCV) infections. HCV fitness can be a determinant of decreased sensitivity to direct-acting antiviral agents such as telaprevir or daclatasvir, but fitness-dependent decreased drug sensitivity has not been established for drugs with a high phenotypic barrier to resistance. Low- and high-fitness HCV populations and biological clones derived from them were used to infect Huh-7.5 hepatoma cells. Sofosbuvir efficacy was analyzed by measuring virus progeny production during several passages and by selection of possible sofosbuvir resistance mutations determined by sequencing the NS5B-coding region of the resulting populations. Sofosbuvir exhibited reduced efficacy against high-fitness HCV populations, without the acquisition of sofosbuvir-specific resistance mutations. A reduced sofosbuvir efficacy, similar to that observed with the parental populations, was seen for high-fitness individual biological clones. In independently derived high-fitness HCV populations or clones passaged in the presence of sofosbuvir, M289L was selected as the only substitution in the viral polymerase NS5B. In no case was the sofosbuvir-specific resistance substitution S282T observed. High HCV fitness can lead to decreased sensitivity to sofosbuvir, without the acquisition of specific sofosbuvir resistance mutations. Thus, fitness-dependent drug sensitivity can operate with HCV inhibitors that display a high barrier to resistance. This mechanism may underlie treatment failures not associated with selection of sofosbuvir-specific resistance mutations, linked to in vivo fitness of pretreatment viral populations. PMID:27067341

  19. Efficient sampling over rough energy landscapes with high barriers: A combination of metadynamics with integrated tempering sampling

    NASA Astrophysics Data System (ADS)

    Yang, Y. Isaac; Zhang, Jun; Che, Xing; Yang, Lijiang; Gao, Yi Qin

    2016-03-01

    In order to efficiently overcome high free energy barriers embedded in a complex energy landscape and calculate overall thermodynamics properties using molecular dynamics simulations, we developed and implemented a sampling strategy by combining the metadynamics with (selective) integrated tempering sampling (ITS/SITS) method. The dominant local minima on the potential energy surface (PES) are partially exalted by accumulating history-dependent potentials as in metadynamics, and the sampling over the entire PES is further enhanced by ITS/SITS. With this hybrid method, the simulated system can be rapidly driven across the dominant barrier along selected collective coordinates. Then, ITS/SITS ensures a fast convergence of the sampling over the entire PES and an efficient calculation of the overall thermodynamic properties of the simulation system. To test the accuracy and efficiency of this method, we first benchmarked this method in the calculation of ϕ - ψ distribution of alanine dipeptide in explicit solvent. We further applied it to examine the design of template molecules for aromatic meta-C—H activation in solutions and investigate solution conformations of the nonapeptide Bradykinin involving slow cis-trans isomerizations of three proline residues.

  20. Spin-unrestricted random-phase approximation with range separation: Benchmark on atomization energies and reaction barrier heights

    SciTech Connect

    Mussard, Bastien; Reinhardt, Peter; Toulouse, Julien; Ángyán, János G.

    2015-04-21

    We consider several spin-unrestricted random-phase approximation (RPA) variants for calculating correlation energies, with and without range separation, and test them on datasets of atomization energies and reaction barrier heights. We show that range separation greatly improves the accuracy of all RPA variants for these properties. Moreover, we show that a RPA variant with exchange, hereafter referred to as RPAx-SO2, first proposed by Szabo and Ostlund [J. Chem. Phys. 67, 4351 (1977)] in a spin-restricted closed-shell formalism, and extended here to a spin-unrestricted formalism, provides on average the most accurate range-separated RPA variant for atomization energies and reaction barrier heights. Since this range-separated RPAx-SO2 method had already been shown to be among the most accurate range-separated RPA variants for weak intermolecular interactions [J. Toulouse et al., J. Chem. Phys. 135, 084119 (2011)], this works confirms range-separated RPAx-SO2 as a promising method for general chemical applications.

  1. Case histories portraying different methods of installing liners for verticle barriers

    SciTech Connect

    Burke, G.K.; Crockford, R.M.; Achhorner, F.N.

    1997-12-31

    The installation of liners for vertical barriers is difficult and has been a learning experience for every contractor making the attempt. Soil stratigraphy and hydrogeologic conditions can vary over short distances, creating a variety of problems. This is particularly so when working near landfills and documentation of the as-built condition is poor. Successful installation requires detailed planning and knowledge of what to expect, as well as alternate plans for potential problems. Several successful methods of panel connection will be presented as well as a variety of installation techniques. Project case histories will be reviewed, highlighting the challenges associated with specific construction techniques.

  2. Rural-Urban Differences in Colorectal Cancer Screening Barriers in Nebraska.

    PubMed

    Hughes, Alejandro G; Watanabe-Galloway, Shinobu; Schnell, Paulette; Soliman, Amr S

    2015-12-01

    Nebraska ranks 36th nationally in colorectal cancer screening. Despite recent increases in CRC screening rates, rural areas in Nebraska have consistently shown lower rates of CRC screening uptake, compared to urban areas. The objective of this study was to investigate reasons for lower CRC screening rates among Nebraska residents, especially among rural residents. We developed a questionnaire based on Health Belief Model (HBM) constructs to identify factors associated with the use of CRC screening. The questionnaire was mailed in 2014 to adults aged 50-75 years in an urban community in the east and a rural community in the west regions of the state. Multiple logistic regression models were created to assess the effects of HBM constructs, rural residence, and demographic factors on CRC screening use. Of the 1200 surveys mailed, 393 were returned (rural n = 200, urban n = 193). Rural respondents were more likely to perceive screening cost as a barrier. Rural residents were also more likely to report that CRC cannot be prevented and it would change their whole life. In multiple regression models, rural residence, perceived embarrassment, and perceived unpleasantness about screening were significantly associated with reduced odds of receiving colonoscopy. Older age (62 years and older), having a personal doctor, and perceived risk of getting CRC were significantly associated with increased odds of receiving colonoscopy. Interventions to increase uptake of colorectal cancer screening in rural residents should be tailored to acknowledge unique perceptions of screening methods and barriers to screening.

  3. SOLPLAN report: An assessment of barriers and incentives to conservation and alternative-energy use in the residential sector in Wisconsin

    NASA Astrophysics Data System (ADS)

    Fulenwider, C. K.; Weiss, L. S.; Pfefferkorn, C.; Wiener, D. E.; Feldmam, S. L.

    1981-03-01

    The Alternative Energy Policy Project of the Wisconsin Center for Public Policy focused upon two principle objectives: gathering and analyzing data on energy conservation and alternative energy commercialization; and building consensus around alternative energy policy to develop guidelines for alternative energy policy for the state. Particular attention was paid to public involvement in the policy process and to assessing barriers and incentives from as many key sectors of the energy field as possible. Data were gathered from the general public, alternative energy users, the heating industry generally, the alternative-energy industry specifically, and key decision makers.

  4. Barriers to Point-of-Care Testing in India: Results from Qualitative Research across Different Settings, Users and Major Diseases

    PubMed Central

    Engel, Nora; Ganesh, Gayatri; Patil, Mamata; Yellappa, Vijayashree; Pant Pai, Nitika; Vadnais, Caroline; Pai, Madhukar

    2015-01-01

    Background Successful point-of-care testing, namely ensuring the completion of the test and treat cycle in the same encounter, has immense potential to reduce diagnostic and treatment delays, and impact patient outcomes. However, having rapid tests is not enough, as many barriers may prevent their successful implementation in point-of-care testing programs. Qualitative research on diagnostic practices may help identify such barriers across different points of care in health systems. Methods In this exploratory qualitative study, we conducted 78 semi-structured interviews and 13 focus group discussions in an urban and rural area of Karnataka, India, with healthcare providers (doctors, nurses, specialists, traditional healers, and informal providers), patients, community health workers, test manufacturers, laboratory technicians, program managers and policy-makers. Participants were purposively sampled to represent settings of hospitals, peripheral labs, clinics, communities and homes, in both the public and private sectors. Results In the Indian context, the onus is on the patient to ensure successful point-of-care testing across homes, clinics, labs and hospitals, amidst uncoordinated providers with divergent and often competing practices, in settings lacking material, money and human resources. We identified three overarching themes affecting point-of-care testing: the main theme is ‘relationships’ among providers and between providers and patients, influenced by the cross-cutting theme of ‘infrastructure’. Challenges with both result in ‘modified practices’ often favouring empirical (symptomatic) treatment over treatment guided by testing. Conclusions Even if tests can be conducted on the spot and infrastructure challenges have been resolved, relationships among providers and between patients and providers are crucial for successful point-of-care testing. Furthermore, these barriers do not act in isolation, but are interlinked and need to be examined

  5. A family of enantiopure Fe(III)4 single molecule magnets: fine tuning of energy barrier by remote substituent.

    PubMed

    Zhu, Yuan-Yuan; Cui, Chang; Qian, Kang; Yin, Ji; Wang, Bing-Wu; Wang, Zhe-Ming; Gao, Song

    2014-08-21

    A new family of enantiopure star-shaped Fe(III)4 single-molecule magnets (SMMs) with the general formula [Fe4(L(K))6] (H2L = (R or S)-2-((2-hydroxy-1-phenylethylimino methyl)phenol); K = H (), Cl (), Br (), I (), and t-Bu ()), were structurally and magnetically characterized. Complex was reported in our previous paper (Chem. Commun., 2011, 47, 8049-8051). Detailed magnetic measurements and a systematic magneto-structural correlation study revealed that the SMM properties of this series of compounds can be finely tuned by the remote substituent of the ligands. Although the change in the coordination environment of the central Fe(3+) ions is very small, the properties of SMM behavior are changed considerably. All five complexes display frequency dependence of the ac susceptibility. However, the χ peaks of complexes and cannot be observed down to 0.5 K. The fitted anisotropy energy barriers (Ueff) of complexes , , and were 5.9, 7.1, and 11.0 K, respectively. Moreover, the hysteresis loops of these three complexes can be also observed around 0.5 K. Magneto-structural correlation analyses revealed that the coordination symmetry of the central Fe(3+) ion and the intermolecular interaction are two key factors affecting the SMM properties. Deviation to a trigonal prism coordination environment and the existence of intermolecular interactions between neighboring clusters may both reduce the anisotropy energy barriers.

  6. Maximum collectible solar energy by different solar tracking systems

    SciTech Connect

    Helwa, N.H.; Bahgat, A.B.G.; El Shafee, A.M.R.; El Shenawy, E.T.

    2000-01-01

    The output energy from any solar energy system depends on the solar energy input to that system. Using different ways to track the solar energy system to follow the sun can increase solar energy input according to the type of the tracker. A practical study was carried out on difference solar tract systems. The layout of these systems are a fixed system facing south and tilted 40{degree}, a vertical-axis tracker, a 6{degree} tilted-axis tracker, and a two-axis tracker. All the trackers are microprocessor controlled systems, and all systems have photovoltaic arrays for electric energy production. The evaluation of the different systems is based on a complete year of measurements for solar radiation input to the systems and the electric power output from them. The study also includes the effect of some operating parameters on the tracker operation. These studies showed that the collected solar energy as well as the electrical output energy of the tracking solar system are more than that of the stationary system. These gains are higher in the case of the two-axis tracker and decrease gradually from the vertical-axis tracker to the tilted-axis tracker.

  7. Through-thickness determination of phase composition and residual stresses in thermall barrier coatings using high- energy x-rays.

    SciTech Connect

    Weyant, , C. M.; Almer, J. D.; Faber, K. T.; Stony Brook Univ.

    2009-01-01

    High-energy X-rays were used to determine the local phase composition and residual stresses through the thickness of as-sprayed and heat-treated plasma-sprayed thermal barrier coatings consisting of a NiCoCrAlY bond coat and an yttria-stabilized zirconia (YSZ) topcoat produced with through-thickness segmentation cracks. The as-sprayed residual stresses reflected the combined influence of quenching stresses from the plasma spray process, thermal expansion mismatch between the topcoat, bond coat and substrate, and stress relief from the segmentation cracks. Heat treatments led to the formation of a thermally grown oxide (TGO) which was in compression in the plane, as well as relief of quenching stresses and development of a stress gradient in the YSZ topcoat. The high-energy X-ray technique used in this study revealed the effects that TGO and segmentation cracks have on the in-plane stress state of the entire coating.

  8. Autonomously Folding Protein Fragments Reveal Differences in the Energy Landscapes of Homologous RNases H

    PubMed Central

    Rosen, Laura E.; Marqusee, Susan

    2015-01-01

    An important approach to understanding how a protein sequence encodes its energy landscape is to compare proteins with different sequences that fold to the same general native structure. In this work, we compare E. coli and T. thermophilus homologs of the protein RNase H. Using protein fragments, we create equilibrium mimics of two different potential partially-folded intermediates (Icore and Icore+1) hypothesized to be present on the energy landscapes of these two proteins. We observe that both T. thermophilus RNase H (ttRNH) fragments are folded and have distinct stabilities, indicating that both regions are capable of autonomous folding and that both intermediates are present as local minima on the ttRNH energy landscape. In contrast, the two E. coli RNase H (ecRNH) fragments have very similar stabilities, suggesting that the presence of additional residues in the Icore+1 fragment does not affect the folding or structure as compared to Icore. NMR experiments provide additional evidence that only the Icore intermediate is populated by ecRNH. This is one of the biggest differences that has been observed between the energy landscapes of these two proteins. Additionally, we used a FRET experiment in the background of full-length ttRNH to specifically monitor the formation of the Icore+1 intermediate. We determine that the ttRNH Icore+1 intermediate is likely the intermediate populated prior to the rate-limiting barrier to global folding, in contrast to E. coli RNase H for which Icore is the folding intermediate. This result provides new insight into the nature of the rate-limiting barrier for the folding of RNase H. PMID:25803034

  9. Republic of Korea Reduction of Financing Barriers for Energy Savings Performance Contracts

    SciTech Connect

    Howard, D. L.

    2005-11-01

    This paper discusses the findings developed for strengthening the role of performance contracting in improving energy efficiency in the Republic of Korea. The U.S. Environmental Protection Agency (EPA) sponsored development of this paper by the National Renewable Energy Laboratory (NREL), as a part of the Korean-U.S. Climate Technology Partnerships (CTP) program. The results and recommendations outlined in this paper together with other efforts are designed to assist other countries striving to improve their efficient use of energy.

  10. Energy Efficiency of Biogas Produced from Different Biomass Sources

    NASA Astrophysics Data System (ADS)

    Begum, Shahida; Nazri, A. H.

    2013-06-01

    Malaysia has different sources of biomass like palm oil waste, agricultural waste, cow dung, sewage waste and landfill sites, which can be used to produce biogas and as a source of energy. Depending on the type of biomass, the biogas produced can have different calorific value. At the same time the energy, being used to produce biogas is dependent on transportation distance, means of transportation, conversion techniques and for handling of raw materials and digested residues. An energy systems analysis approach based on literature is applied to calculate the energy efficiency of biogas produced from biomass. Basically, the methodology is comprised of collecting data, proposing locations and estimating the energy input needed to produce biogas and output obtained from the generated biogas. The study showed that palm oil and municipal solid waste is two potential sources of biomass. The energy efficiency of biogas produced from palm oil residues and municipal solid wastes is 1.70 and 3.33 respectively. Municipal solid wastes have the higher energy efficiency due to less transportation distance and electricity consumption. Despite the inherent uncertainties in the calculations, it can be concluded that the energy potential to use biomass for biogas production is a promising alternative.

  11. Influence of the intercalated cations on the surface energy of montmorillonites: consequences for the morphology and gas barrier properties of polyethylene/montmorillonites nanocomposites.

    PubMed

    Picard, E; Gauthier, H; Gérard, J-F; Espuche, E

    2007-03-15

    Organically modified montmorillonites obtained by cation exchange from the same natural layered silicate were studied. The surface properties of the pristine and a series of organically modified clays were determined by inverse gas chromatography and the water adsorption mechanisms were studied by a gravimetric technique coupled with a microcalorimeter. A significant increase of the specific surface area, a decrease of the water adsorption, and a decrease of the dispersive component of the surface energy were observed when the sodium cations of the natural montmorillonite were exchanged for a quaternary ammonium. Slighter differences in surface properties were observed, on the other hand, between the different types of organically modified montmorillonites. Indeed, similar dispersive components of the surface energy were determined on the organoclays. Nevertheless, the specific surface area increased in the range 48-80 m(2)/g with increasing d-spacing values and the presence of specific groups attached to the quaternary ammonium, such as phenyl rings or hydroxyl groups, led to some specific behaviors, i.e., a more pronounced base character and a higher water adsorption at high activity, respectively. Differences in interlayer cation chain organization, denoted as crystallinity, were also observed as a function of the nature of the chains borne by the quaternary ammonium. In a later step, polyethylene-based nanocomposites were prepared with those organically modified montmorillonites. The clay dispersion and the barrier properties of the nanocomposites were discussed as a function of the montmorillonite characteristics and of the matrix/montmorillonite interactions expected from surface energy characterization.

  12. Molecular transport through surfactant-covered oil-water interfaces: role of physical properties of solutes and surfactants in creating energy barriers for transport.

    PubMed

    Ahn, Yong Nam; Gupta, Ashish; Chauhan, Anuj; Kopelevich, Dmitry I

    2011-03-15

    Mechanisms of molecular transport across oil-water interfaces covered by nonionic surfactants are investigated using coarse-grained molecular dynamics simulations. Resistance of the surfactant monolayer to the solute transport is shown to be controlled by dense regions in the monolayer. The dense regions are formed on both sides of the dividing surface and the barrier to the solute transport is created by those of them experiencing unfavorable interactions with the solute. Resistance to the transport of a hydrophobic (hydrophilic) solute increases with the excess density of the head (tail) group region of the monolayer, which in turn increases with the length of the surfactant head (tail) group. Barriers for solute transport through surfactant monolayers are also influenced by the solute size. However, the extent of this influence is determined by the monolayer thickness and the solute structure and composition. For example, it is shown that resistance offered by thin monolayers to transport of linear oligomers is relatively insensitive to the solute length. The barrier sensitivity to the length of these solutes increases with the monolayer thickness. In addition to the static barriers, the solute transport is shown to be affected by dynamic barriers due to a nonadiabatic coupling of the monolayer surface with the solute position and configuration. This coupling leads to deviations of the system dynamics from the minimum energy path. The deviations are most significant in the neighborhood of the static energy barrier, which effectively leads to an increase of the barrier for the solute transport.

  13. Energy dependence of the optical potentials for the 9Be +208Pb and 9Be +209Bi systems at near-Coulomb-barrier energies

    NASA Astrophysics Data System (ADS)

    Gómez Camacho, A.; Yu, N.; Zhang, H. Q.; Gomes, P. R. S.; Jia, H. M.; Lubian, J.; Lin, C. J.

    2015-04-01

    We analyze the energy dependence of the interacting optical potential, at near barrier energies, for two systems involving the weakly bound projectile 9Be and the heavy 208Pb and 209Bi targets, by the simultaneous fit of elastic scattering angular distributions and fusion excitation functions. The approach used consists of dividing the optical potential into two parts. A short-range potential VF+i WF that is responsible for fusion, and a superficial potential VDR+i WDR for direct reactions. It is found, for both systems studied, that the fusion imaginary potential WF presents the usual threshold anomaly (TA) observed in tightly bound systems, whereas the direct reaction imaginary potential WDR shows a breakup threshold anomaly (BTA) behavior. Both potentials satisfy the dispersion relation. The direct reaction polarization potential predominates over the fusion potential and so a net overall behavior is found to follow the BTA phenomenon.

  14. Additive effects on the energy barrier for synaptic vesicle fusion cause supralinear effects on the vesicle fusion rate

    PubMed Central

    Schotten, Sebastiaan; Meijer, Marieke; Walter, Alexander Matthias; Huson, Vincent; Mamer, Lauren; Kalogreades, Lawrence; ter Veer, Mirelle; Ruiter, Marvin; Brose, Nils; Rosenmund, Christian

    2015-01-01

    The energy required to fuse synaptic vesicles with the plasma membrane (‘activation energy’) is considered a major determinant in synaptic efficacy. From reaction rate theory, we predict that a class of modulations exists, which utilize linear modulation of the energy barrier for fusion to achieve supralinear effects on the fusion rate. To test this prediction experimentally, we developed a method to assess the number of releasable vesicles, rate constants for vesicle priming, unpriming, and fusion, and the activation energy for fusion by fitting a vesicle state model to synaptic responses induced by hypertonic solutions. We show that complexinI/II deficiency or phorbol ester stimulation indeed affects responses to hypertonic solution in a supralinear manner. An additive vs multiplicative relationship between activation energy and fusion rate provides a novel explanation for previously observed non-linear effects of genetic/pharmacological perturbations on synaptic transmission and a novel interpretation of the cooperative nature of Ca2+-dependent release. DOI: http://dx.doi.org/10.7554/eLife.05531.001 PMID:25871846

  15. Negligible suppression of the complete fusion of Li,76 on light targets, at energies above the barrier

    NASA Astrophysics Data System (ADS)

    Guo, M. F.; Zhang, G. L.; Gomes, P. R. S.; Lubian, J.; Ferioli, E.

    2016-10-01

    Motivated by a recent work performed at Australian National University by S. Kalkal et al. [Phys. Rev. C 93, 044605 (2016), 10.1103/PhysRevC.93.044605] on breakup and its time scale, where it was shown that the prompt (or near-target) breakup of Li,76 is almost negligible and consequently the near-barrier complete fusion cross section induced by these weakly bound Li isotopes on light targets should not be suppressed by the breakup, as it is for heavier targets, we estimated the contributions of complete and incomplete fusion in the measured total fusions for several light systems available in the literature. The chosen systems were those for which the fusion cross sections had been measured using the γ -ray spectroscopy method and all evaporation channel cross sections were reported. For the estimation, we used, apart from the data, the predictions of the evaporation code cascade. The results show that, indeed, the complete fusion suppression is negligible for such systems at energies slightly above the barrier, in agreement with the above-mentioned recent measurements of breakup time scales.

  16. Simulation study of free-energy barriers in the wetting transition of an oily fluid on a rough surface with reentrant geometry.

    PubMed

    Savoy, Elizabeth S; Escobedo, Fernando A

    2012-11-20

    When in contact with a rough solid surface, fluids with low surface tension, such as oils and alkanes, have their lowest free energy in the fully wetted state. For applications where nonwetting by these phillic fluids is desired, some barrier must be introduced to maintain the nonwetted composite state. One way to create this free-energy barrier is to fabricate roughness with reentrant geometry, but the question remains as to whether the free-energy barrier is sufficiently high to prevent wetting. Our goal is to quantify the free-energy landscape for the wetting transition of an oily fluid on a surface of nails and identify significant surface features and conditions that maximize the wetting free-energy barrier (ΔGfwd*). This is a departure from most work on wetting, which focuses on the equilibrium composite and wetted states. We use boxed molecular dynamics (BXD) (Glowacki, D. R.; Paci, E.; Shalashilin, D. V. J. Phys. Chem. B2009, 113, 16603-16611) with a modified control scheme to evaluate both the thermodynamics and kinetics of the transition over a range of surface affinities (chemistry). We find that the reentrant geometry of the nails does create a free-energy barrier to transition for phillic chemistry whereas a corresponding system on straight posts wets spontaneously and, that doubling the nail height more than doubles ΔGfwd*. For neutral to phillic chemistry, the dewetting free-energy barrier is at least an order of magnitude higher than that for wetting, indicating an essentially irreversible wetting transition. Transition rates from BXD simulations and the associated trends agree well with those in our previous study that used forward flux sampling to compute transition rates for similar systems.

  17. Extracting renewable energy from a salinity difference using a capacitor.

    PubMed

    Brogioli, Doriano

    2009-07-31

    Completely renewable energy can be produced by using water solutions of different salinity, like river water and sea water. Many different methods are already known, but development is still at prototype stage. Here I report a novel method, based on electric double-layer capacitor technology. Two porous electrodes, immersed in the salt solution, constitute a capacitor. It is first charged, then the salt solution is brought into contact with fresh water. The electrostatic energy increases as the salt concentration of the solution is reduced due to diffusion. This device can be used to turn sources of salinity difference into completely renewable sources of energy. An experimental demonstration is given, and performances and possible improvements are discussed.

  18. Comparing the health and environmental hazards of different energy systems

    SciTech Connect

    Hamilton, L.D.

    1982-01-01

    Energy and environment can pose difficult challenges for policy makers and scientists. Assessing health impacts of different energy sources requires synthesis of research results from many different disciplines into a rational framework. Information is often scanty; qualitatively different risks, or energy systems with quite different end uses, must be put on a common footing. Risk-assessment methods reviewed include examples drawn from work of the Biomedical and Environmental Assessment Division at Brookhaven National Laboratory and elsewhere. Coal and nuclear fuel cycles are compared in respect to morbidity and mortality. Other cycles (oil, gas and renewables) are also examined. In broadening comparisons to include new technologies, one must include the impact of manufacturing the energy-producing devices as part of an expanded fuel cycle, via input-output methods. Input-output analysis allows comparisons of direct and system-wide impacts. Throughout the analysis, uncertainties must be explicitly recognized in the results, including uncertainty in validity of data and uncertainty in choice of appropriate models. No single method of comparative risk assessment is fully satisfactory; each has its limitations. By use of several methods progress has been made in understanding the relative impact of energy technologies.

  19. Molecular biology of the blood-brain and the blood-cerebrospinal fluid barriers: similarities and differences

    PubMed Central

    2011-01-01

    Efficient processing of information by the central nervous system (CNS) represents an important evolutionary advantage. Thus, homeostatic mechanisms have developed that provide appropriate circumstances for neuronal signaling, including a highly controlled and stable microenvironment. To provide such a milieu for neurons, extracellular fluids of the CNS are separated from the changeable environment of blood at three major interfaces: at the brain capillaries by the blood-brain barrier (BBB), which is localized at the level of the endothelial cells and separates brain interstitial fluid (ISF) from blood; at the epithelial layer of four choroid plexuses, the blood-cerebrospinal fluid (CSF) barrier (BCSFB), which separates CSF from the CP ISF, and at the arachnoid barrier. The two barriers that represent the largest interface between blood and brain extracellular fluids, the BBB and the BCSFB, prevent the free paracellular diffusion of polar molecules by complex morphological features, including tight junctions (TJs) that interconnect the endothelial and epithelial cells, respectively. The first part of this review focuses on the molecular biology of TJs and adherens junctions in the brain capillary endothelial cells and in the CP epithelial cells. However, normal function of the CNS depends on a constant supply of essential molecules, like glucose and amino acids from the blood, exchange of electrolytes between brain extracellular fluids and blood, as well as on efficient removal of metabolic waste products and excess neurotransmitters from the brain ISF. Therefore, a number of specific transport proteins are expressed in brain capillary endothelial cells and CP epithelial cells that provide transport of nutrients and ions into the CNS and removal of waste products and ions from the CSF. The second part of this review concentrates on the molecular biology of various solute carrier (SLC) transport proteins at those two barriers and underlines differences in their

  20. Molecular biology of the blood-brain and the blood-cerebrospinal fluid barriers: similarities and differences.

    PubMed

    Redzic, Zoran

    2011-01-18

    Efficient processing of information by the central nervous system (CNS) represents an important evolutionary advantage. Thus, homeostatic mechanisms have developed that provide appropriate circumstances for neuronal signaling, including a highly controlled and stable microenvironment. To provide such a milieu for neurons, extracellular fluids of the CNS are separated from the changeable environment of blood at three major interfaces: at the brain capillaries by the blood-brain barrier (BBB), which is localized at the level of the endothelial cells and separates brain interstitial fluid (ISF) from blood; at the epithelial layer of four choroid plexuses, the blood-cerebrospinal fluid (CSF) barrier (BCSFB), which separates CSF from the CP ISF, and at the arachnoid barrier. The two barriers that represent the largest interface between blood and brain extracellular fluids, the BBB and the BCSFB, prevent the free paracellular diffusion of polar molecules by complex morphological features, including tight junctions (TJs) that interconnect the endothelial and epithelial cells, respectively. The first part of this review focuses on the molecular biology of TJs and adherens junctions in the brain capillary endothelial cells and in the CP epithelial cells. However, normal function of the CNS depends on a constant supply of essential molecules, like glucose and amino acids from the blood, exchange of electrolytes between brain extracellular fluids and blood, as well as on efficient removal of metabolic waste products and excess neurotransmitters from the brain ISF. Therefore, a number of specific transport proteins are expressed in brain capillary endothelial cells and CP epithelial cells that provide transport of nutrients and ions into the CNS and removal of waste products and ions from the CSF. The second part of this review concentrates on the molecular biology of various solute carrier (SLC) transport proteins at those two barriers and underlines differences in their

  1. Revealing highly unbalanced energy barriers in the extension and contraction of the muscle-like motion of a [c2]daisy chain.

    PubMed

    Zhao, Yan-Ling; Zhang, Rui-Qin; Minot, Christian; Hermann, Klaus; Van Hove, Michel A

    2015-07-28

    Nanoscale muscle-like materials have aroused great interest as they may provide controllable mechanical operations by artificial actuations. Molecular designs to achieve the desired motion at the macroscopic scale in experiments require atomic level understanding. By systematic quantum chemical and molecular dynamics calculations we reveal that the length change is not only due to the linear telescoping from the dibenzo[24]crown-8 recognition at two docking stations but also the folding/unfolding of two bulky stoppers. The extension and contraction processes of a [c2]daisy chain under acidic vs. basic conditions are exothermic but need to cross very different energy barriers, being at least double the height under acidic compared to basic conditions, hindering balanced cyclic motions at moderate excitation. Our result suggests that to realize the desired muscle-like motion one should adopt sufficiently high external excitation, using for example reasonably high temperature and further optimizing the solution used.

  2. Molecular dynamics simulation of the structure and interfacial free energy barriers of mixtures of ionic liquids and divalent salts near a graphene wall.

    PubMed

    Gómez-González, Víctor; Docampo-Álvarez, Borja; Méndez-Morales, Trinidad; Cabeza, Oscar; Ivaništšev, Vladislav B; Fedorov, Maxim V; Gallego, Luis J; Varela, Luis M

    2016-12-21

    A molecular dynamics study of mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) with magnesium tetrafluoroborate (Mg[BF4]2) confined between two parallel graphene walls is reported. The structure of the system is analyzed by means of ionic density profiles, lateral structure of the first layer close to the graphene surface and angular orientations of imidazolium cations. Free energy profiles for divalent magnesium cations are calculated using two different methods in order to evaluate the height of the potential barriers near the walls, and the results are compared with those of mixtures of the same ionic liquid and a lithium salt (Li[BF4]). Preferential adsorption of magnesium cations is analyzed using a simple model and compared to that of lithium cations, and vibrational densities of states are calculated for the cations close to the walls analyzing the influence of the graphene surface charge. Our results indicate that magnesium cations next to the graphene wall have a roughly similar environment to that in the bulk. Moreover, they face higher potential barriers and are less adsorbed on the charged graphene walls than lithium cations. In other words, magnesium cations have a more stable solvation shell than lithium ones.

  3. A responsive human triple-culture model of the air-blood barrier: incorporation of different macrophage phenotypes.

    PubMed

    Kasper, Jennifer Y; Hermanns, Maria I; Unger, Ronald E; Kirkpatrick, C James

    2015-06-15

    Current pulmonary research underlines the relevance of the alveolar macrophage (AM) integrated in multicellular co-culture-systems of the respiratory tract to unravel, for example, the mechanisms of tissue regeneration. AMs demonstrate a specific functionality, as they inhabit a unique microenvironment with high oxygen levels and exposure to external hazards. Healthy AMs display an anti-inflammatory phenotype, prevent hypersensitivity to normally innocuous contaminants and maintain tissue homeostasis in the alveolus. To mirror the actual physiological function of the AM, we developed three different polarized [classically activated (M1) and alternatively activated (M2wh , wound-healing; M2reg , regulatory)] macrophage models using a mixture of differentiation mediators, as described in the current literature. To test their immunological impact, these distinct macrophage phenotypes were seeded on to the epithelial layer of an established in vitro air-blood barrier co-culture, consisting of alveolar epithelial cells A549 or H441 and microvascular endothelial cells ISO-HAS-1 on the opposite side of a Transwell filter-membrane. IL-8 and sICAM release were measured as functionality parameters after LPS challenge. The M1 model itself already provoked a severe inflammatory-like response of the air-blood barrier co-culture, thus demonstrating its potential as a useful in vitro model for inflammatory lung diseases. The two M2 models represent a 'non-inflammatory' phenotype but still showed the ability to trigger inflammation following LPS challenge. Hence, the latter could be used to establish a quiescent, physiological in vitro air-blood model. Thus, the more complex differentiation protocol developed in the present study provides a responsive in vitro triple-culture model of the air-blood-barrier that mimics AM features as they occur in vivo. © 2015 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons, Ltd.

  4. An Ising iron(ii) chain exhibits a large finite-size energy barrier and "hard" magnetic behaviour.

    PubMed

    Deng, Yi-Fei; Han, Tian; Xue, Wei; Hayashi, Naoaki; Kageyama, Hiroshi; Zheng, Yan-Zhen

    2017-01-31

    One-dimensional spin chains featuring strong axial anisotropic magnetism are promising candidates for isolatable and miniatured information storage materials, the so-called single-chain magnets (SCMs). Here we show a mixed azido/carboxylato bridged metamagnetic iron(ii) chain [Fe(N3)2(4-mpc)]n (4-mpc = N-methylpyridinium-4-carboxylate) with a large energy barrier of 150 K, a large remnant magnetization (1.55Nβ) and coercivity (1.7 T at 2 K) for homo-spin SCMs. Heat capacity and Mössbauer spectroscopy studies corroborate the intrinsic nature of SCM behavior regardless of weak interchain magnetic interactions, which lead to the coexistence of metamagnetism but not long-range magnetic ordering. Moreover, detailed magnetic investigations indicate that the system is not only within the "Ising limit" but also in the "finite-size" regime.

  5. Total and partial capture cross sections in reactions with deformed nuclei at energies near and below the Coulomb barrier

    SciTech Connect

    Kuzyakin, R. A. Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.

    2013-06-15

    Within the quantum diffusion approach, the capture of a projectile nucleus by a target nucleus is studied at bombarding energies above and below the Coulomb barrier. The effects of deformation of interacting nuclei and neutron transfer between them on the total and partial capture cross sections and the mean angular momentum of the captured system are studied. The results obtained for the {sup 16}O + {sup 112}Cd, {sup 152}Sm, and {sup 184}W; {sup 19}F +{sup 175}Lu; {sup 28}Si +{sup 94,100}Mo and {sup 154}Sm; {sup 40}Ca +{sup 96}Zr; {sup 48}Ca+ {sup 90}Zr; and {sup 64}Ni +{sup 58,64}Ni, {sup 92,96}Zr, and {sup 100}Mo reactions are in good agreement with available experimental data.

  6. Transesterification thio effects of phosphate diesters: free energy barriers and kinetic and equilibrium isotope effects from density-functional theory.

    PubMed

    Liu, Yun; Gregersen, Brent A; Hengge, Alvan; York, Darrin M

    2006-08-22

    Primary and secondary kinetic and equilibrium isotope effects are calculated with density-functional methods for the in-line dianionic methanolysis of the native (unsubstituted) and thio-substituted cyclic phosphates. These reactions represent reverse reaction models for RNA transesterification under alkaline conditions. The effect of solvent is treated with explicit (single and double) water molecules and self-consistently with an implicit (continuum) solvation model. Singly substituted reactions at the nonbridging O(P1) position and bridging O(2)('), O(3)('), and O(5)(') positions and a doubly substituted reaction at the O(P1) and O(P2) positions were considered. Aqueous free energy barriers are calculated, and the structures and bond orders of the rate-controlling transition states are characterized. The results are consistent with available experimental data and provide useful information for the interpretation of measured isotope and thio effects used to probe mechanism in phosphoryl transfer reactions catalyzed by enzymes and ribozymes.

  7. Nucleon-nucleon correlations in heavy ion transfer reactions: Recent investigations at energies far below the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Corradi, Lorenzo

    2015-10-01

    Excitation functions of one- and two-neutron transfer channels have been measured for the 96Zr+40Ca and 116Sn+60Ni systems at bombarding energies ranging from the Coulomb barrier to ˜25% below. Target-like recoils have been identified in A, Z and velocity with the large solid angle magnetic spectrometer PRISMA. The experimental transfer probabilities have been compared, in absolute values and in slope, with semiclassical microscopic calculations which incorporate nucleon-nucleon pairing correlations. For the first time in a heavy ion collision, one was able to provide a consistent description of one and two neutron transfer reactions by incorporating, in the reaction mechanism, all known structure information of entrance and exit channels nuclei. In particular, there is no need to introduce any enhancement factor for the description of two neutron transfer, of course very important are the correlations induced by the pairing interaction.

  8. Elastic scattering for the system {sup 6}Li+p at near barrier energies with MAGNEX

    SciTech Connect

    Soukeras, V.; Pakou, A.; Sgouros, O.; Cappuzzello, F.; Bondi, M.; Nicolosi, D.; Acosta, L.; Marquinez-Duran, G.; Martel, I.; Agodi, C.; Carbone, D.; Cavallaro, M.; Cunsolo, A.; Di Pietro, A.; Fernández-García, J. P.; Figuera, P.; Fisichella, M.; Alamanos, N.; De Napoli, M.; Foti, A.; and others

    2015-02-24

    Elastic scattering measurements have been performed for the {sup 6}Li+p system in inverse kinematics at the energies of 16, 20, 25 and 29 MeV. The heavy ejectile was detected by the large acceptance MAGNEX spectrometer at the Laboratori Nazionali del Sud (LNS) in Catania, in the angular range between ∼2{sup 0} and 12{sup 0} in the laboratory system, giving us the possibility to span almost a full angular range in the center of mass system. Results will be presented and discussed for one of the energies.

  9. Elastic scattering and transfer reactions for the system 7Be + 58Ni at Coulomb barrier energies

    NASA Astrophysics Data System (ADS)

    Mazzocco, M.; Torresi, D.; Acosta, L.; Boiano, A.; Boiano, C.; Glodariu, T.; Guglielmetti, A.; Keeley, N.; La Commara, M.; Lay, J. A.; Martel, I.; Mazzocchi, C.; Molini, P.; Parascandolo, C.; Parkar, V. V.; Pierroutsakou, D.; Romoli, M.; Rusek, K.; Sanchez-Benitez, A. M.; Sandoli, M.; Signorini, C.; Silvestri, R.; Soramel, F.; Strano, E.; Stroe, L.

    2015-09-01

    We investigated the reaction induced by the Radioactive Ion Beam 7Be on the closed proton shell nucleus 58Ni at 22.0 MeV bombarding energy. The 7Be beam was produced by means of the in-flight technique with the facility EXOTIC at INFN-LNL (Italy). Charged reaction products were mass and charge identified in a rather wide angular range and their energy distributions were analyzed to infer some information on the production mechanism. The relevance of direct processes, especially 3He- and 4He-stripping, as well as compound nucleus reactions is critically reviewed.

  10. High Penetration of Renewable Energy in the Transportation Sector: Scenarios, Barriers, and Enablers; Preprint

    SciTech Connect

    Vimmerstedt, L.; Brown, A.; Heath, G.; Mai, T.; Ruth, M.; Melaina, M.; Simpkins, T.; Steward, D.; Warner, E.; Bertram, K.; Plotkin, S.; Patel, D.; Stephens, T.; Vyas, A.

    2012-06-01

    Transportation accounts for 71% of U.S. petroleum use and 33% of its greenhouse gases emissions. Pathways toward reduced greenhouse gas emissions and petroleum dependence in the transportation sector have been analyzed in considerable detail, but with some limitations. To add to this knowledge, the U.S. Department of Energy has launched a study focused on underexplored greenhouse-gas-abatement and oil-savings opportunities related to transportation. This Transportation Energy Futures study analyzes specific issues and associated key questions to strengthen the existing knowledge base and help cultivate partnerships among federal agencies, state and local governments, and industry.

  11. Inter-arm blood pressure difference in type 2 diabetes: a barrier to effective management?

    PubMed Central

    Clark, Christopher E; Greaves, Colin J; Evans, Philip H; Dickens, Andy; Campbell, John L

    2009-01-01

    Background Previous studies have identified a substantial prevalence of a blood pressure difference between arms in various populations, but not patients with type 2 diabetes. Recognition of such a difference would be important as a potential cause of underestimation of blood pressure. Aim To measure prevalence of an inter-arm blood pressure difference in patients with type 2 diabetes, and to estimate how frequently blood pressure measurements could be erroneously underestimated if an inter-arm difference is unrecognised. Design of study Cross-sectional study. Setting Five surgeries covered by three general practices, Devon, England. Method Patients with type 2 diabetes underwent bilateral simultaneous blood pressure measurements using a validated protocol. Mean blood pressures were calculated for each arm to derive mean systolic and diastolic differences, and to estimate point prevalence of predefined magnitudes of difference. Results A total of 101 participants were recruited. Mean age was 66 years (standard deviation [SD] = 13.9 years); 59% were male, and mean blood pressure was 138/79 mmHg (SD = 15/10 mmHg). Ten participants (10%; 95% confidence interval [CI] = 4 to 16) had a systolic inter-arm difference ≥10 mmHg; 29 (29%; 95% CI = 20 to 38) had a diastolic difference ≥5 mmHg; and three (3%; 95% CI = 0 to 6) a diastolic difference ≥10 mmHg. No confounding variable was observed to account for the magnitude of an inter-arm difference. Conclusion A systolic inter-arm difference ≥10 mmHg was observed in 10% of patients with diabetes. Failure to recognise this would misclassify half of these as normotensive rather than hypertensive using the lower-reading arm. New patients with type 2 diabetes should be screened for an inter-arm blood pressure difference. PMID:19520026

  12. The C12(O16,γSi28) radiative capture reaction at sub-barrier energies

    NASA Astrophysics Data System (ADS)

    Goasduff, A.; Courtin, S.; Haas, F.; Lebhertz, D.; Jenkins, D. G.; Fallis, J.; Ruiz, C.; Hutcheon, D. A.; Amandruz, P.-A.; Davis, C.; Hager, U.; Ottewell, D.; Ruprecht, G.

    2014-01-01

    The heavy-ion radiative capture C12(O16,γSi28) was measured at the sub-Coulomb barrier bombarding energy Elab=15.7 MeV, which corresponds to the lowest important resonance observed in the C12+ O16 fusion excitation function. Thanks to combination of the bismuth germanate (BGO) γ-ray array and the 0∘ DRAGON electromagnetic spectrometer at TRIUMF, the γ-decay spectrum from the entrance channel down to the ground state of 28Si was measured. Comparisons of the experimental spectrum to γ spectrum extracted from Monte Carlo simulations of the complete setup suggest a Jπ=2+ spin-parity assignment to the entrance channel and yield the radiative capture cross section σRC=0.22±0.04μb. Combining this present spin assignment with previous data on radiative capture, a J (J+1) systematics was constructed, and it indicated a moment of inertia commensurate with the C12+O16 grazing angular momentum. Strong dipole transitions are observed from the entrance channel to T =1 states around 11.5 MeV and are found to result from enhanced M1IV transitions to states exhausting a large part of the M1 sum rule built on the ground state of 28Si. This specific decay was also reported at bombarding energies close to the Coulomb barrier in our previous study of the C12(C12,γ24Mg) heavy-ion radiative capture reaction. Similarities between both systems are investigated.

  13. The Barriers Encountered by Teachers Implementing Education for Sustainable Development: Discipline Bound Differences and Teaching Traditions

    ERIC Educational Resources Information Center

    Borg, Carola; Gericke, Niklas; Hoglund, Hans-Olof; Bergman, Eva

    2012-01-01

    Background: According to the Swedish curriculum teachers in all subjects have a responsibility to integrate a holistic perspective of sustainable development (SD) and teach according to an education for sustainable development (ESD) approach. However previous research has shown that teachers from different subjects perceive SD differently.…

  14. The role of couplings in nuclear rainbow formation at energies far above the barrier

    SciTech Connect

    Pereira, D.; Linares, R.; and others

    2012-10-20

    A study of the {sup 16}O+{sup 28}Si elastic and inelastic scattering is presented in the framework of Coupled Channel theory. The Sao Paulo Potential is used in the angular distribution calculations and compared with the existing data at 75 MeV bombarding energy. A nuclear rainbow pattern is predicted and becomes more clear above 100 MeV.

  15. Constraining the Symmetry Energy:. a Journey in the Isospin Physics from Coulomb Barrier to Deconfinement

    NASA Astrophysics Data System (ADS)

    di Toro, M.; Colonna, M.; Greco, V.; Ferini, G.; Rizzo, C.; Rizzo, J.; Baran, V.; Gaitanos, T.; Prassa, V.; Wolter, H. H.; Zielinska-Pfabe, M.

    Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation. In this work we present a selection of reaction observables in dissipative collisions particularly sensitive to the isovector part of the interaction, i.e.to the symmetry term of the nuclear Equation of State (EoS). At low energies the behavior of the symmetry energy around saturation influences dissipation and fragment production mechanisms. We will first discuss the recently observed Dynamical Dipole Radiation, due to a collective neutron-proton oscillation during the charge equilibration in fusion and deep-inelastic collisions. Important Iso - EOS are stressed. Reactions induced by unstable 132Sn beams appear to be very promising tools to test the sub-saturation Isovector EoS. New Isospin sensitive observables are also presented for deep-inelastic, fragmentation collisions and Isospin equilibration measurements (Imbalance Ratios). The high density symmetry term can be derived from isospin effects on heavy ion reactions at relativistic energies (few AGeV range), that can even allow a "direct" study of the covariant structure of the isovector interaction in the hadron medium. Rather sensitive observables are proposed from collective flows and from pion/kaon production. The possibility of the transition to a mixed hadron-quark phase, at high baryon and isospin density, is finally suggested. Some signatures could come from an expected "neutron trapping" effect. The importance of studying violent collisions with radioactive beams from low to relativistic energies is finally stressed.

  16. The difference between energy consumption and energy cost: Modelling energy tariff structures for water resource recovery facilities.

    PubMed

    Aymerich, I; Rieger, L; Sobhani, R; Rosso, D; Corominas, Ll

    2015-09-15

    The objective of this paper is to demonstrate the importance of incorporating more realistic energy cost models (based on current energy tariff structures) into existing water resource recovery facilities (WRRFs) process models when evaluating technologies and cost-saving control strategies. In this paper, we first introduce a systematic framework to model energy usage at WRRFs and a generalized structure to describe energy tariffs including the most common billing terms. Secondly, this paper introduces a detailed energy cost model based on a Spanish energy tariff structure coupled with a WRRF process model to evaluate several control strategies and provide insights into the selection of the contracted power structure. The results for a 1-year evaluation on a 115,000 population-equivalent WRRF showed monthly cost differences ranging from 7 to 30% when comparing the detailed energy cost model to an average energy price. The evaluation of different aeration control strategies also showed that using average energy prices and neglecting energy tariff structures may lead to biased conclusions when selecting operating strategies or comparing technologies or equipment. The proposed framework demonstrated that for cost minimization, control strategies should be paired with a specific optimal contracted power. Hence, the design of operational and control strategies must take into account the local energy tariff.

  17. Potential Energy Landscape of the Electronic States of the GFP Chromophore in Different Protonation Forms: Electronic Transition Energies and Conical Intersections.

    PubMed

    Polyakov, I V; Grigorenko, B L; Epifanovsky, E M; Krylov, A I; Nemukhin, A V

    2010-08-10

    We present the results of quantum chemical calculations of the transition energies and conical intersection points for the two lowest singlet electronic states of the green fluorescent protein chromophore, 4'-hydroxybenzylidene-2,3-dimethylimidazolinone, in the vicinity of its cis conformation in the gas phase. Four protonation states of the chromophore, i.e., anionic, neutral, cationic, and zwitterionic, were considered. Energy differences were computed by the perturbatively corrected complete active space self-consistent field (CASSCF)-based approaches at the corresponding potential energy minima optimized by density functional theory and CASSCF (for the ground and excited states, respectively). We also report the EOM-CCSD and SOS-CIS(D) results for the excitation energies. The minimum energy S0/S1 conical intersection points were located using analytic state-specific CASSCF gradients. The results reproduce essential features of previous ab initio calculations of the anionic form of the chromophore and provide an extension for the neutral, cationic, and zwitterionic forms, which are important in the protein environment. The S1 PES of the anion is fairly flat, and the barrier separating the planar bright conformation from the dark twisted one as well as the conical intersection point with the S0 surface is very small (less than 2 kcal/mol). On the cationic surface, the barrier is considerably higher (∼13 kcal/mol). The PES of the S1 state of the zwitterionic form does not have a planar minimum in the Franck-Condon region. The S1 surface of the neutral form possesses a bright planar minimum; the energy barrier of about 9 kcal/mol separates it from the dark twisted conformation as well as from the conical intersection point leading to the cis-trans chromophore isomerization.

  18. One-dimensional free-energy profiles of complex systems: progress variables that preserve the barriers.

    PubMed

    Krivov, Sergei V; Karplus, Martin

    2006-06-29

    We show that the balanced minimum-cut procedure introduced in PNAS 2004, 101, 14766 can be reinterpreted as a method for solving the constrained optimization problem of finding the minimum cut among the cuts with a particular value of an additive function of the nodes on either side of the cut. Such an additive function (e.g., the partition function of the reactant region) can be used as a progress coordinate to determine a one-dimensional profile (FEP) of the free-energy surface of the protein-folding reaction as well as other complex reactions. The algorithm is based on the network (obtained from an equilibrium molecular dynamics simulation) that represents the calculated reaction behavior. The resulting FEP gives the exact values of the free energy as a function of the progress coordinate; i.e., at each value of the progress coordinate, the profile is obtained from the surface with the minimal partition function among the surfaces that divide the full free-energy surface between two chosen end points. In many cases, the balanced minimum-cut procedure gives results for only a limited set of points. An approximate method based on p(fold) is shown to provide the profile for a more complete set of values of the progress coordinate. Applications of the approach to model problems and to realistic systems (beta-hairpin of protein G, LJ38 cluster) are presented.

  19. Different sound decay patterns and energy feedback in coupled volumes.

    PubMed

    Pu, Hongjie; Qiu, Xiaojun; Wang, Jiqing

    2011-04-01

    Different non-exponential decays such as the concave and the convex double sloped decays in the coupled rooms provide distinct sound qualities. These are commonly considered to occur in the less reverberant sub-room and the more reverberant sub-room, respectively. However, numerical simulations and experiments in this paper show that the demarcation line is not located along the physical boundaries (e.g., the partition and the coupling aperture), but in the more reverberant sub-room. The sound field with the concave double sloped decay penetrates into the auxiliary sub-room to an extent which is influenced by the difference between the two natural reverberations of the sub-rooms. Furthermore the sound energy flows in different regions are investigated, demonstrating how energy feedback leads to the concave double sloped decay.

  20. Energy radiated by seismic events of different scales and geneses

    NASA Astrophysics Data System (ADS)

    Kocharyan, G. G.; Ivanchenko, G. N.; Kishkina, S. B.

    2016-07-01

    Extensive data comprising about 1500 seismic events with the moment magnitudes M W from-3.5 to 9.2 have been analyzed for identifying the implications of the event size, the type of faulting in the source, and tectonic situations for the efficiency of the radiation. It is shown that there are several hierarchy levels with different patterns of scaling relationships describing the changes in the parameters of seismic events with the event size. This is due to the specificity of the hierarchy in the macroscopic characteristics of the rock mass. The size and mechanism of the earthquake determine the general trends in the variations of its radiation efficiency. The role of the macroscopic parameter controlling the efficiency of a seismic source is played by the stiffness of a fault or a fracture. The scaling relationship of this parameter determines several hierarchical levels within which the changes in the characteristics of the earthquakes follow the different laws. The huge scatter in the values of the scaled energy (the ratio of the radiated seismic energy to the seismic moment, energy-to-moment ratio) about the average requires additional study. Quite probably, the value of the scaled seismic energy is determined by the mesostructure and physicomechanical characteristics of the fault's core. Small variations in these factors may lead to drastic changes in the stress drop amplitude and in the rupture propagation velocity up to the emergence of different regimes of deformation.

  1. Gender Differences in Insulin Resistance, Body Composition, and Energy Balance

    PubMed Central

    Geer, Eliza B.; Shen, Wei

    2010-01-01

    Background Men and women differ substantially in regard to degrees of insulin resistance, body composition, and energy balance. Adipose tissue distribution, in particular the presence of elevated visceral and hepatic adiposity, plays a central role in the development of insulin resistance and obesity-related complications. Objective This review summarizes published data on gender differences in insulin resistance, body composition, and energy balance, to provide insight into novel gender-specific avenues of research as well as gender-tailored treatments of insulin resistance, visceral adiposity, and obesity. Methods English-language articles were identified from searches of the PubMed database through November 2008, and by reviewing the references cited in these reports. Searches included combinations of the following terms: gender, sex, insulin resistance, body composition, energy balance, and hepatic adipose tissue. Results For a given body mass index, men were reported to have more lean mass, women to have higher adiposity. Men were also found to have more visceral and hepatic adipose tissue, whereas women had more peripheral or subcutaneous adipose tissue. These differences, as well as differences in sex hormones and adipokines, may contribute to a more insulin-sensitive environment in women than in men. When normalized to kilograms of lean body mass, men and women had similar resting energy expenditure, but physical energy expenditure was more closely related to percent body fat in men than in women. Conclusion Greater amounts of visceral and hepatic adipose tissue, in conjunction with the lack of a possible protective effect of estrogen, may be related to higher insulin resistance in men compared with women. PMID:19318219

  2. Acetylated rice starches films with different levels of amylose: Mechanical, water vapor barrier, thermal, and biodegradability properties.

    PubMed

    Colussi, Rosana; Pinto, Vânia Zanella; El Halal, Shanise Lisie Mello; Biduski, Bárbara; Prietto, Luciana; Castilhos, Danilo Dufech; Zavareze, Elessandra da Rosa; Dias, Alvaro Renato Guerra

    2017-04-15

    Biodegradable films from native or acetylated starches with different amylose levels were prepared. The films were characterized according to the mechanical, water vapor barrier, thermal, and biodegradability properties. The films from acetylated high amylose starches had higher moisture content and water solubility than the native high amylose starch film. However, the acetylation did not affect acid solubility of the films, regardless of the amylose content. Films made from high and medium amylose rice starches were obtained; however low amylose rice starches, whether native or acetylated, did not form films with desirable characteristics. The acetylation decreased the tensile strength and increased the elongation of the films. The acetylated starch-based films had a lower decomposition temperature and higher thermal stability than native starch films. Acetylated starches films exhibited more rapid degradation as compared with the native starches films.

  3. Experimental evidence for a fusion enhancement in 19O+12C at near barrier energies

    NASA Astrophysics Data System (ADS)

    Singh, Varinderjit; Steinbach, T. K.; Vadas, J.; Wiggins, B. B.; Hudan, S.; Desouza, R. T.; Baby, L. T.; Tripathi, V.; Kuvin, S. A.; Wiedenhover, I.; Umar, A. S.; Oberacker, V. E.

    2016-03-01

    Fusion of neutron-rich light nuclei in the outer crust of an accreting neutron star has been proposed as responsible for triggering X-ray super-bursts. The underlying hypothesis in this proposition is that the fusion of neutron-rich nuclei is enhanced as compared to stable nuclei. To investigate this hypothesis, an experiment has been performed to measure the fusion excitation function for 18O and 19O nuclei incident on a 12C target. A beam of 19O was produced by the 18O(d,p) reaction at Florida State University and separated using the RESOLUT mass spectrometer. The resulting 19O beam bombarded a 100 μg/cm2 12C target at an intensity of 2-4 x 104p/s. Evaporation residues resulting from the de-excitation of the fusion product were distinguished by measuring their energy and time-of-flight. Evaporation residues were detected with high efficiency by measuring them in the angular range 4.4° <=θlab <= 11.7°. The fusion cross-section has been measured down to 170 mb level. As compared to 18O+12C the fusion cross-section for 19O+12C is enhanced by approximately a factor of 3 times at the lowest energy measured. The measured excitation function will be compared with theoretical calculations. Supported by the US DOE under Grant No. DEFG02-88ER-40404.

  4. Effects of surface barrier layer in AlGaAs/GaAs solar cells

    NASA Astrophysics Data System (ADS)

    Urabe, Hiroyuki; Kuramoto, Makoto; Nakano, Tomohiro; Kawaharazuka, Atsushi; Makimoto, Toshiki; Horikoshi, Yoshiji

    2015-09-01

    In this paper, we report the effects of surface barrier layers on the characteristics of AlGaAs/GaAs solar cells. The external quantum efficiency (EQE) spectra for AlGaAs barrier samples with different barrier layer AlAs fractions and thickness of the surface barrier layer were measured to increase the solar cell efficiency. The results show that the surface barrier layer is effective to block diffusing photoexcited electrons to the surface while the thicker barrier layer absorbs higher energy photons to generate carriers which recombine at the surface. The optimal surface barrier structure is a 50 nm thick Al0.7Ga0.3As.

  5. Metastability and hysteretic vortex pinning near the order-disorder transition in NbSe2: Interplay between plastic and elastic energy barriers

    NASA Astrophysics Data System (ADS)

    Marziali Bermúdez, M.; Louden, E. R.; Eskildsen, M. R.; Dewhurst, C. D.; Bekeris, V.; Pasquini, G.

    2017-03-01

    We studied thermal and dynamic history effects in the vortex lattice (VL) near the order-disorder transition in clean NbSe2 single crystals. Comparing the evolution of the effective vortex pinning and the bulk VL structure, we observed metastable superheated and supercooled VL configurations that coexist with a hysteretic effective pinning response due to thermal cycling of the system. A novel scenario, governed by the interplay between (lower) elastic and (higher) plastic energy barriers, is proposed as an explanation for our observations: Plastic barriers, which prevent the annihilation or creation of topological defects, require dynamic assistance to be overcome and to achieve a stable VL at each temperature. Conversely, thermal hysteresis in the pining response is ascribed to low energy barriers, which inhibit rearrangement within a single VL correlation volume and are easily overcome as the relative strength of competing interactions changes with temperature.

  6. A robust numerical method for self-polarization energy of spherical quantum dots with finite confinement barriers.

    PubMed

    Deng, Shaozhong

    2010-04-01

    By utilizing a novel three-layer dielectric model for the interface between a spherical quantum dot and the surrounding matrix, a robust numerical method for calculating the self-polarization energy of a spherical quantum dot with a finite confinement barrier is presented in this paper. The proposed numerical method can not only overcome the inherent mathematical divergence in the self-polarization energy which arises for the simplest and most widely used step-like model of the dielectric interface, but also completely eliminate the potential numerical divergence which may occur in the Bolcatto-Proetto's formula [J. Phys.: Condens. Matter 13, 319-334 (2001)], an approximation method commonly employed for more realistic three-layer dielectric models such as the linear and the cosine-like models frequently mentioned in the literature. Numerical experiments have demonstrated the convergence of the proposed numerical method as the number of the steps used to discretize the translation layer in a three-layer model goes to infinity, an important property that the Bolcatto-Proetto's formula appears not necessarily to possess.

  7. Enhancement of fusion at near-barrier energies for neutron-rich light nuclei: 19O +12 C

    NASA Astrophysics Data System (ADS)

    Singh, Varinderjit; Vadas, J.; Steinbach, T. K.; Wiggins, B. B.; Hudan, S.; Desouza, R. T.; Baby, L. T.; Kuvin, S. A.; Tripathi, Vandana; Wiedenhover, I.; Umar, A. S.

    2017-01-01

    Measuring the fusion excitation function for an isotopic chain of projectile nuclei provides a sensitive test of a microscopic description of fusion. To investigate the theoretically predicted fusion enhancement for neutron-rich light nuclei, an experiment was performed to measure the fusion excitation functions for 19 O +12 C and 18 O +12 C . Using the 18O(d,p) reaction and the RESOLUT mass spectrometer at Florida State University, a beam of 19O was produced with an intensity of 2-4 x 103 p/s. This beam bombarded a 100 μg/cm2 carbon target. Using an approach optimized for the measurement of fusion with a low-intensity beam, evaporation residues (ERs) resulting from the de-excitation of the fusion product were measured. The ERs were identified by measuring their energy and time-of-flight. At near-barrier energies, an enhancement of fusion by a factor of three has been observed for 19 O +12 C in comparison to 18 O +12 C . Comparison of the experimental results with the predictions of a density constrained time-dependent Hartree-Fock (DC-TDHF) model provide evidence for the importance of pairing in the fusion process. Supported by the US DOE under Grant No. DEFG02-88ER-40404.

  8. Edge energy transport barrier and turbulence in the I-mode regime on Alcator C-Moda)

    NASA Astrophysics Data System (ADS)

    Hubbard, A. E.; Whyte, D. G.; Churchill, R. M.; Cziegler, I.; Dominguez, A.; Golfinopoulos, T.; Hughes, J. W.; Rice, J. E.; Bespamyatnov, I.; Greenwald, M. J.; Howard, N.; Lipschultz, B.; Marmar, E. S.; Reinke, M. L.; Rowan, W. L.; Terry, J. L.

    2011-05-01

    We report extended studies of the I-mode regime [Whyte et al., Nucl. Fusion 50, 105005 (2010)] obtained in the Alcator C-Mod tokamak [Marmar et al., Fusion Sci. Technol. 51(3), 3261 (2007)]. This regime, usually accessed with unfavorable ion B × ∇B drift, features an edge thermal transport barrier without a strong particle transport barrier. Steady I-modes have now been obtained with favorable B × ∇B drift, by using specific plasma shapes, as well as with unfavorable drift over a wider range of shapes and plasma parameters. With favorable drift, power thresholds are close to the standard scaling for L-H transitions, while with unfavorable drift they are ˜ 1.5-3 times higher, increasing with Ip. Global energy confinement in both drift configurations is comparable to H-mode scalings, while density profiles and impurity confinement are close to those in L-mode. Transport analysis of the edge region shows a decrease in edge χeff, by typically a factor of 3, between L- and I-mode. The decrease correlates with a drop in mid-frequency fluctuations (f ˜ 50-150 kHz) observed on both density and magnetics diagnostics. Edge fluctuations at higher frequencies often increase above L-mode levels, peaking at f ˜ 250 kHz. This weakly coherent mode is clearest and has narrowest width (Δf/f ˜ 0.45) at low q95 and high Tped, up to 1 keV. The Er well in I-mode is intermediate between L- and H-mode and is dominated by the diamagnetic contribution in the impurity radial force balance, without the Vpol shear typical of H-modes.

  9. The difference of energies of Si atoms with single-crystalline, amorphous, free and nanoparticle configurations

    NASA Astrophysics Data System (ADS)

    Wang, Y. L.; Deng, Z. C.; Chu, L. Z.; Fu, G. S.; Peng, Y. C.

    2009-04-01

    Nanocrystalline silicon (nc-Si) films were systematically prepared via three ways: a) laser anneal or b) thermal anneal of the amorphous silicon (α-Si) films deposited by pulsed-laser ablation (PLA) in base vacuum, c) direct PLA in high-purity Ar gas with pressure of 10 Pa. The anneal-laser fluence, thermal-anneal temperature and ablation-laser fluence thresholds corresponding to the beginning of nanoparticles formation were respectively determined by using scanning electron microscopy (SEM), Raman and X-ray diffraction (XRD) techniques. Incorporated with crystallization mechanism, energies compensated for the formation of one Si nanoparticle in the three ways were calculated approximately. The result shows that for different crystallization ways, the potential barriers during the formation of one ~16 nm nanoparticle are on the order of 10-9 mJ.

  10. Diagnostic group differences in temporomandibular joint energy densities

    PubMed Central

    Gallo, LM; Iwasaki, LR; Gonzalez, YM; Liu, H; Marx, DB; Nickel, JC

    2015-01-01

    Objectives Cartilage fatigue, due to mechanical work, may account for precocious development of degenerative joint disease in the temporomandibular joint (TMJ). This study compared energy densities (mJ/mm3) in TMJs of three diagnostic groups. Setting and Sample Population Sixty-eight subjects (44 women, 24 men) gave informed consent. Diagnostic criteria for temporomandibular disorders (DC/TMD) and imaging were used to group subjects according to presence of jaw muscle or joint pain (+P) and bilateral disc displacement (+DD). Material and Methods Subjects (+P+DD, n=16; −P+DD, n=16; and −P−DD, n=36) provided cone-beam computed tomography and magnetic resonance images, and jaw tracking data. Numerical modeling was used to determine TMJ loads (Fnormal). Dynamic stereometry was used to characterize individual-specific data of stress-field dynamics during 10 symmetrical jaw closing cycles. These data were used to estimate tractional forces (Ftraction). Energy densities were then calculated as W/Q(W=workdoneormechanicalenergyinput=tractionalforce×distanceofstress-fieldtranslation,Q=volumeofcartilage). ANOVA and Tukey-Kramer post-hoc analyses tested for intergroup differences. Results Mean ±standard error energy density for the +P+DD group was 12.7±1.5 mJ/mm3 and significantly greater (all adjusted p<0.04) when compared to −P+DD (7.4±1.4 mJ/mm3) and −P−DD (5.8±0.9 mJ/mm3) groups. Energy densities in −P+DD and −P−DD groups were not significantly different. Conclusion Diagnostic group differences in energy densities suggest that mechanical work may be a unique mechanism which contributes to cartilage fatigue in subjects with pain and disc displacement. PMID:25865545

  11. Energy-Efficient Phase-Change Memory with Graphene as a Thermal Barrier.

    PubMed

    Ahn, Chiyui; Fong, Scott W; Kim, Yongsung; Lee, Seunghyun; Sood, Aditya; Neumann, Christopher M; Asheghi, Mehdi; Goodson, Kenneth E; Pop, Eric; Wong, H-S Philip

    2015-10-14

    Phase-change memory (PCM) is an important class of data storage, yet lowering the programming current of individual devices is known to be a significant challenge. Here we improve the energy-efficiency of PCM by placing a graphene layer at the interface between the phase-change material, Ge2Sb2Te5 (GST), and the bottom electrode (W) heater. Graphene-PCM (G-PCM) devices have ∼40% lower RESET current compared to control devices without the graphene. This is attributed to the graphene as an added interfacial thermal resistance which helps confine the generated heat inside the active PCM volume. The G-PCM achieves programming up to 10(5) cycles, and the graphene could further enhance the PCM endurance by limiting atomic migration or material segregation at the bottom electrode interface.

  12. Limitations and barriers for adopting sustainable management practices in different farm types across Europe

    NASA Astrophysics Data System (ADS)

    Guzmán, Gema; Portero, Ángela; Vanwalleghem, Tom; Pedrera, Ana; Jesús Gaitán, Antonio; Ten Berge, Hein

    2014-05-01

    Although apparently the conservation of natural resources such as water and soil does not represent important concerns for our society, the evolution of the world population and the degradation of these resources pose a challenge to improving agricultural food production capacity and conserving, and in some cases restoring, the environmental quality. Unfortunately, the history contains numerous examples of abandonment of these resources (McNeill 1992, Montgomery 2007). Although most of the agronomic conservation practices have been known for millennia, their implementation has often been hindered by non-agricultural motives (Davis et al. 2012). The European project CATCH-C (ten Berge 2011) started last year with the aim of evaluating sustainable soil management practices and exploring the difficulties for their adoption, both at farm and institutional level, to overcome them in the near future. As a first step with that purpose, a selection of best management practices (BMPs) based on interviews with advisors and scientific knowledge were proposed for each of the considered farm typologies: arable crops, permanent crops and pasture. These farm types are representative of the Mediterranean area in terms of agroecological properties, extension, economical importance and soil degradation problems. Semi-structured interviews were carried out by addressing different profiles of farmers to identify in a qualitative way the main limitations for adopting these BMPs on their farms. Different questionnaires were prepared based on the farmers' responses and launched at a larger scale, with the aim of achieving approximately 100 responses per each farm typology. Finally, responses from the questionnaires will be analyzed to explore the causes that hinder or impede the adoption of BMPs in different farm typologies. References: Davis A.S. et al. 2012. Plos ONE 7(10): e4719. doi:10.1371/journalpone.0047149. McNeill, J.R. 1992. The mountains of the Mediterranean world. Cambridge

  13. Comparative studies of Coulomb barrier heights for nuclear models applied to sub-barrier fusion

    NASA Astrophysics Data System (ADS)

    Qu, W. W.; Zhang, G. L.; Zhang, H. Q.; Wolski, R.

    2014-12-01

    Coulomb barrier heights provided by different nuclear interaction models including the Bass model, the proximity potential model, and the double folding model have been applied for experimental data of fusion in terms of a recently proposed energy scaling approach. The results show that the proximity potential description of the barrier heights seems to be closest to the values required by the systematics. It is suggested that the proximity potential model is the most suitable model to calculate the barrier height. However, the double folding model gives the lowest barrier heights.

  14. Corneal critical barrier against the penetration of dexamethasone and lomefloxacin hydrochloride: evaluation by the activation energy for drug partition and diffusion in cornea.

    PubMed

    Yasueda, Shin-ichi; Higashiyama, Masayo; Yamaguchi, Masazumi; Isowaki, Akiharu; Ohtori, Akira

    2007-08-01

    The cornea is a solid barrier against drug permeation. We searched the critical barrier of corneal drug permeation using a hydrophobic drug, dexamethasone (DM), and a hydrophilic drug, lomefloxacin hydrochloride (LFLX). The activation energies for permeability of DM and LFLX across the intact cornea were 88.0 and 42.1 kJ/mol, respectively. Their activation energies for permeability across the cornea without epithelium decreased to 33.1 and 16.6 kJ/mol, respectively. The results show that epithelium is the critical barrier on the cornea against the permeation of a hydrophobic drug of DM as well as a hydrophilic drug of LFLX. The activation energy of partition for DM (66.8 kJ/mol) was approximately 3-fold larger than that of diffusion (21.2 kJ/mol). The results indicate that the partition for the hydrophobic drug of DM to the corneal epithelium is the primary barrier. Thermodynamic evaluation of activation energy for the drug permeation parameters is a good approach to investigate the mechanism of drug permeability.

  15. Gender-Based Differences and Barriers in Skin Protection Behaviors in Melanoma Survivors.

    PubMed

    Chen, Jeffrey; Shih, Johnny; Tran, Andrew; Mullane, Aaron; Thomas, Christina; Aydin, Nail; Misra, Subhasis

    2016-01-01

    Purpose. Skin protection behaviors and environmental exposure play a crucial role in the development and subsequent management of melanoma. This study investigates gender-based differences in skin protection behaviors after melanoma treatment. Methods. Patients diagnosed and surgically treated for cutaneous melanomas over the last six years in a geographically high risk area were surveyed over telephone using a standardized script. Results. Of 150 survey results obtained, there were 82 males and 68 females. Overall, 87% of participants reported skin self-examination for abnormal markings more often and 94% reported wearing skin protective clothing more often, with females being more than males. Females limited outdoor activity more often than males, 79% to 54%, p < 0.05. When outside, females sought shade more often than males, 75% to 56%, p < 0.05. However, males wore a wide brim hat more often than females, 52% to 28%, p < 0.05. Interestingly, 60% of participants reported wearing SPF 30 sunscreen less often, p < 0.05. Conclusion. Larger percentage of females adopted behavioral changes to prevent future melanoma. Those living in high risk areas and with outdoor occupations need particular attention to skin care. Population based screening should be adopted to deal with this rising public health crisis.

  16. Gender-Based Differences and Barriers in Skin Protection Behaviors in Melanoma Survivors

    PubMed Central

    2016-01-01

    Purpose. Skin protection behaviors and environmental exposure play a crucial role in the development and subsequent management of melanoma. This study investigates gender-based differences in skin protection behaviors after melanoma treatment. Methods. Patients diagnosed and surgically treated for cutaneous melanomas over the last six years in a geographically high risk area were surveyed over telephone using a standardized script. Results. Of 150 survey results obtained, there were 82 males and 68 females. Overall, 87% of participants reported skin self-examination for abnormal markings more often and 94% reported wearing skin protective clothing more often, with females being more than males. Females limited outdoor activity more often than males, 79% to 54%, p < 0.05. When outside, females sought shade more often than males, 75% to 56%, p < 0.05. However, males wore a wide brim hat more often than females, 52% to 28%, p < 0.05. Interestingly, 60% of participants reported wearing SPF 30 sunscreen less often, p < 0.05. Conclusion. Larger percentage of females adopted behavioral changes to prevent future melanoma. Those living in high risk areas and with outdoor occupations need particular attention to skin care. Population based screening should be adopted to deal with this rising public health crisis. PMID:27648306

  17. Stereotyping as a barrier to collaboration: Does interprofessional education make a difference?

    PubMed

    Ateah, Christine A; Snow, Wanda; Wener, Pamela; MacDonald, Laura; Metge, Colleen; Davis, Penny; Fricke, Moni; Ludwig, Sora; Anderson, Judy

    2011-02-01

    This research was part of a Health Canada funded initiative developed to provide evidence about the effectiveness of interprofessional education (IPE) interventions to promote collaborative patient-centred care. Health professional students' ratings of health professions and the effect of IPE on those ratings were examined. Participants were divided into three groups (N=51); control, education, and practice site immersion. Utilizing the Student Stereotypes Rating Questionnaire (SSRQ) which consists of a five point Likert-type scale each group rated health professionals on nine characteristics: academic ability, interpersonal skills, professional competence, leadership, practical skills, independence, confidence, decision-making, and being a team player (Hean, Macleod-Clark, Adams, and Humphris, 2006). Data were collected at four time points; prior to an IPE classroom intervention, following an IPE classroom intervention, following the IPE immersion experience, and four months post IPE immersion experience. Overall, perceptions of other health professions were more positive following the 2.5day interprofessional education session and immersion experience. Student ratings of the seven professions among the nine characteristics will be presented, highlighting similarities and differences across professional groups. Findings support the incorporation of IPE curricula that address the role and functions of other health care professions to facilitate the development collaborative patient-centred care health care teams.

  18. Measurement of the fusion excitation function for 19O + 12C at near barrier energies

    NASA Astrophysics Data System (ADS)

    Singh, Varinderjit; Steinbach, T. K.; Vadas, J.; Wiggins, B. B.; Hudan, S.; Desouza, R. T.; Baby, L. T.; Tripathi, V.; Kuvin, S. A.; Wiedenhover, I.

    2015-10-01

    Fusion of neutron-rich light nuclei in the outer crust of an accreting neutron star has been proposed as responsible for triggering X-ray super-bursts. The underlying hypothesis in this proposition is that the fusion of neutron-rich nuclei is enhanced as compared to stable nuclei. To investigate this hypothesis, an experiment has been performed to measure the fusion excitation function for 18O and 19O nuclei incident on a 12C target. A beam of 19O was produced by the 18O(d,p) reaction at Florida State University and separated using the RESOLUT mass spectrometer. The resulting 19O beam bombarded a 100 μg/cm2 12C target at an intensity of 2-4 × 103 p/s. Evaporation residues resulting from the de-excitation of the fusion product were distinguished by measuring their energy and time-of-flight. Using silicon detectors, micro-channel plate detectors, and an ionization chamber, evaporation residues were detected in the angular range θlab <= 23° with high efficiency. Initial experimental results including measurement of the fusion cross-section to approximately the 100 mb level will be presented. The measured excitation function will be compared to theoretical predictions. Supported by the US DOE under Grand No. DEFG02-88ER-40404.

  19. Energy expenditure and sex differences of golf playing.

    PubMed

    Zunzer, Stefan C; von Duvillard, Serge P; Tschakert, Gerhard; Mangus, Brent; Hofmann, Peter

    2013-01-01

    The purpose of the study was to assess the average physical intensity and energy expenditure during a single round of golf on hilly and flat courses in a heterogeneous group of healthy men and women of varying age and golf handicap. Forty-two males and 24 females completed an incremental cycle-ergometer exercise test to determine exercise performance markers. The heart rate (HR), duration, distance, walking speed, ascent and descent were measured via a global positioning system (GPS)/HR monitor during the game and energy expenditure was calculated. Playing 9 or 18-holes of golf, independent of the golf course design, the average HR was not significantly different between sexes or the subgroups. The intensities were light with respect to the percentage of maximal HR and metabolic equivalents of task (METs). Total energy expenditure of all participants was not significantly different for hilly (834 ± 344 kcal) vs. flat courses (833 ± 295 kcal) whereas male players expended significantly greater energy than female players (926 ± 292 vs. 556 ± 180 kcal), but did not have significantly greater relative energy expenditure (2.8 ± 0.8 vs. 2.2 ± 0.7 METs). As a high volume physical activity, playing golf is suggested to yield health benefits. Since the intensity was well below recommended limits, golf may have health related benefits unrelated to the intensity level of the activity.

  20. Protein-inhibitor flexible docking by a multicanonical sampling: native complex structure with the lowest free energy and a free-energy barrier distinguishing the native complex from the others.

    PubMed

    Kamiya, Narutoshi; Yonezawa, Yasushige; Nakamura, Haruki; Higo, Junichi

    2008-01-01

    Flexible docking between a protein (lysozyme) and an inhibitor (tri-N-acetyl-D-glucosamine, tri-NAG) was carried out by an enhanced conformational sampling method, multicanonical molecular dynamics simulation. We used a flexible all-atom model to express lysozyme, tri-NAG, and water molecules surrounding the two bio-molecules. The advantages of this sampling method are as follows: the conformation of system is widely sampled without trapping at energy minima, a thermally equilibrated conformational ensemble at an arbitrary temperature can be reconstructed from the simulation trajectory, and the thermodynamic weight can be assigned to each sampled conformation. During the simulation, exchanges between the binding and free (i.e., unbinding) states of the protein and the inhibitor were repeatedly observed. The conformational ensemble reconstructed at 300 K involved various conformational clusters. The main outcome of the current study is that the most populated conformational cluster (i.e., the cluster of the lowest free energy) was assigned to the native complex structure (i.e., the X-ray complex structure). The simulation also produced non-native complex structures, where the protein and the inhibitor bound with different modes from that of the native complex structure, as well as the unbinding structures. A free-energy barrier (i.e., activation free energy) was clearly detected between the native complex structures and the other structures. The thermal fluctuations of tri-NAG in the lowest free-energy complex correlated well with the X-ray B-factors of tri-NAG in the X-ray complex structure. The existence of the free-energy barrier ensures that the lowest free-energy structure can be discriminated naturally from the other structures. In other words, the multicanonical molecular dynamics simulation can predict the native complex structure without any empirical objective function. The current study also manifested that the flexible all-atom model and the physico

  1. Indomethacin co-crystals and their parent mixtures: does the intestinal barrier recognize them differently?

    PubMed

    Ferretti, Valeria; Dalpiaz, Alessandro; Bertolasi, Valerio; Ferraro, Luca; Beggiato, Sarah; Spizzo, Federico; Spisni, Enzo; Pavan, Barbara

    2015-05-04

    Co-crystals are crystalline complexes of two or more molecules bound together in crystal lattices through noncovalent interactions. The solubility and dissolution properties of co-crystals can allow to increase the bioavailability of poorly water-soluble active pharmaceutical ingredients (APIs). It is currently believed that the co-crystallization strategy should not induce changes on the pharmacological profile of the APIs, even if it is not yet clear whether a co-crystal would be defined as a physical mixture or as a new chemical entity. In order to clarify these aspects, we chose indomethacin as guest poorly aqueous soluble molecule and compared its properties with those of its co-crystals obtained with 2-hydroxy-4-methylpyridine (co-crystal 1), 2-methoxy-5-nitroaniline (co-crystal 2), and saccharine (co-crystal 3). In particular, we performed a systematic comparison among indomethacin, its co-crystals, and their parent physical mixtures by evaluating via HPLC analysis the API dissolution profile, its ability to permeate across intestinal cell monolayers (NCM460), and its oral bioavailability in rat. The indomethacin dissolution profile was not altered by the presence of co-crystallizing agents as physical mixtures, whereas significant changes were observed by the dissolution of the co-crystals. Furthermore, there was a qualitative concordance between the API dissolution patterns and the relative oral bioavailabilities in rats. Co-crystal 1 induced a drastic decrease of the transepithelial electrical resistance (TEER) value of NCM460 cell monolayers, whereas its parent mixture did not evidence any effect. The saccharin-indomethacin mixture induced a drastic decrease of the TEER value of monolayers, whereas its parent co-crystal 3 did not induce any effects on their integrity, being anyway able to increase the permeation of indomethacin. Taken together, these results demonstrate for the first time different effects induced by co-crystals and their parent physical

  2. Culture and language differences as a barrier to provision of quality care by the health workforce in Saudi Arabia

    PubMed Central

    Almutairi, Khalid M.

    2015-01-01

    Objectives: To identify, synthesize, and summarize issues and challenges related to the culture and language differences of the health workforce in Saudi Arabia. Methods: A comprehensive systematic review was conducted in May 2014 to locate published articles. Two independent researchers in consultation with several experts used 4 electronic databases (ISI Web of Knowledge, Science Direct, PubMed, and Cochrane) to scrutinize articles published from January 2000 - March 2014. Each of the studies was given a quality assessment rating of weak, moderate, or strong, and was evaluated for methodological soundness using Russell and Gregory’s criteria. Results: The online literature search identified 12 studies that met the inclusion criteria. Lack of knowledge of non-Muslim nurses or culture in Saudi Arabia, difficulties in achieving cultural competence, and culture shock were documented as cultural difference factors. Issues in language difference include the clarity of language use by health care providers in giving information and providing adequate explanation regarding their activities. Conclusion: The available information provided by this review study shows that there is a communication barrier between patients and health care workers such as healthcare workers demonstrate low cultural competency. Despite the fact that the government provides programs for expatriate healthcare workers, there is a need to further improve educational and orientation programs regarding the culture and language in Saudi Arabia. PMID:25828278

  3. Utilisation of health services and geography: deconstructing regional differences in barriers to facility-based delivery in Nepal.

    PubMed

    Hodge, Andrew; Byrne, Abbey; Morgan, Alison; Jimenez-Soto, Eliana

    2015-03-01

    While established that geographical inaccessibility is a key barrier to the utilisation of health services, it remains unknown whether disparities are driven only by limited access to these services, or are also attributable to health behaviour. Significant disparities exist in health outcomes and the coverage of many critical health services between the mountains region of Nepal and the rest of the country, yet the principal factors driving these regional disparities are not well understood. Using national representative data from the 2011 Nepal Demographic and Health Survey, we examine the extent to which observable factors explain the overall differences in the utilisation of maternal health services. We apply nonlinear Blinder-Oaxaca-type decomposition methods to quantify the effect that differences in measurable characteristics have on the regional coverage gap in facility-based delivery. The mean coverage of facility-based deliveries was 18.6 and 36.3 % in the mountains region and the rest of Nepal, respectively. Between 54.8 and 74.1 % of the regional coverage gap was explained by differences in observed characteristics. Factors influencing health behaviours (proxied by mothers' education, TV viewership and tobacco use, and household wealth) and subjective distance to the health facility were the major factors, contributing between 52.9 and 62.5 % of the disparity. Mothers' birth history was also noteworthy. Policies simultaneously addressing access and health behaviours appear necessary to achieve greater coverage and better health outcomes for women and children in isolated areas.

  4. Similar Students and Different Countries? An Analysis of the Barriers and Drivers for Erasmus Participation in Seven Countries

    ERIC Educational Resources Information Center

    Beerkens, Maarja; Souto-Otero, Manuel; de Wit, Hans; Huisman, Jeroen

    2016-01-01

    Increasing participation in the Erasmus study abroad program in Europe is a clear policy goal, and student-reported barriers and drivers are regularly monitored. This article uses student survey data from seven countries to examine the extent to which student-level barriers can explain the considerable cross-country variation in Erasmus…

  5. Differences in energy capacities between tennis players and runners.

    PubMed

    Novak, Dario; Vucetić, Vlatko; Zugaj, Sanja

    2013-05-01

    The primary purpose of this study was to determine differences between elite athletes and tennis players in order to provide a clearer picture regarding the energy demands in modern tennis. Forty-eight (48) athletes and 24 tennis players from Croatian national leagues were compared in morphological and physiological parameters of an all-out incremental treadmill test with gas exchange measurements. Tennis players' HRmax (192.96+/-7.75 bpm) shows values that are most different to 400-meters sprinters (200.13+/-6.95 bpm). Maximum running speed of tennis players on the treadmill (vmax) is no different with the speed achieved by sprinters, while there are significant differences among other athletes. Values in running speed at anaerobic threshold (vAnT) show no statistically significant difference with the values for athlete sprinters and 400-m sprinters. Values of RvO2max for tennis players indicate significant similarities with athlete sprinters and 400-m sprinters while the values of RvO2AnT are nearly identical with the values for sprinters and show no statistically significant differences (p<0.05). The results indicate that values achieved by tennis players approximate most different those of the middle and long distance runners. This singles out the possible importance of the anaerobic capacity and the high level of sprint endurance in tennis players. Knowing these characteristics is the basis for planning and implementing training systems that will enable the increase and optimal usage of energy capacities of tennis players in possibly improving sports results.

  6. How well do we understand quasi-elastic reactions at energies close to the barrier

    SciTech Connect

    Rehm, K.E.

    1988-01-01

    In collisions between too heavy nuclei a wide spectrum of different reaction modes is observed covering the range from simple processes like elastic scattering to complicated multistep transfers and fusion. On the theoretical side heavy ion reactions are usually analyzed using models that were developed first for light ion induced reactions: the optical model for elastic scattering and the DWBA for more inelastic processes like transfer and inelastic scattering. Some of the assumptions going into these approximations, however, are not valid for heavy ion induced reactions. The region between fusion and quasi-elastic reactions is not well understood theoretically. This region is associated with deep inelastic collisions, which are complex multiparticle reactions involving transfer of several protons and neutrons. In this paper, the author discusses to what extent experiments in the field of quasi-elastic scattering are understood within the framework of various theoretical models and in what areas more work is needed.

  7. Distributional implications of reducing interstate energy price differences

    SciTech Connect

    Schmidt, R.H.; Gunther, J.W.

    1986-11-01

    A model of state residential energy consumption for electricity, natural gas, and petroleum examines scenarios which reflect the response to a reduction in regional price differences attributable to deregulation. The results indicate that natural gas deregulation will benefit eastern and northwestern consumers at the expense of middle and western consumers. The deregulation of bulk electric power also benefits the east coast, but rising electricity prices would outweigh any benefits for the northwest. In contrast, electricity producers in the west have the most to gain from deregulation of bulk power transmissions because of the opportunities of a national market. A deregulated environment will likely have less dramatic distributional consequences from future energy price shocks, while increased fuel competition will probably limit price movements in any one fuel. 3 figures, 5 tables.

  8. Coastal Ohio Wind Project for Reduced Barriers to Deployment of Offshore Wind Energy

    SciTech Connect

    Gorsevski, Peter; Afjeh, Abdollah; Jamali, Mohsin; Carroll, Michael

    2014-04-09

    The Coastal Ohio Wind Project was created to establish the viability of wind turbines on the coastal and offshore regions of Northern Ohio. The project’s main goal was to improve operational unit strategies used for environmental impact assessment of offshore turbines on lake wildlife by optimizing and fusing data from the multi-instrument surveillance system and providing an engineering analysis of potential design/operational alternatives for offshore wind turbines. The project also developed a general economic model for offshore WTG deployment to quantify potential revenue losses due to wind turbine shutdown related to ice and avian issues. In a previous phase of this project (Award Number: DE-FG36-06GO86096), we developed a surveillance system that was used to collect different parameters such as passage rates, flight paths, flight directions, and flight altitudes of nocturnal migrating species, movements of birds and bats, and bird calls for assessing patterns and peak passage rates during migration. To derive such parameters we used thermal IR imaging cameras, acoustic recorders, and marine radar Furuno (XANK250), which was coupled with a XIR3000B digitizing card from Russell Technologies and open source radR processing software. The integration yielded a development of different computational techniques and methods, which we further developed and optimized as a combined surveillance system. To accomplish this task we implemented marine radar calibration, optimization of processing parameters, and fusion of the multi-sensor data in order to make inferences about the potential avian targets. The main goal of the data fusion from the multi-sensor environment was aimed at reduction of uncertainties while providing acceptable confidence levels with detailed information about the migration patterns. Another component comprised of an assessment of wind resources in a near lake environment and an investigation of the effectiveness of ice coating materials to

  9. The influence of the design of two different bioresorbable barriers on the results of guided tissue regeneration therapy. An intra-individual comparative study in the monkey.

    PubMed

    Lundgren, D; Laurell, L; Gottlow, J; Rylander, H; Mathisen, T; Nyman, S; Rask, M

    1995-07-01

    The aim of the present study was to compare two bioresorbable barriers to evaluate whether differences in design influence the result of guided tissue regeneration (GTR) therapy. Twenty-four (24) plaque exposed, recession type defects in 4 monkeys were treated. Contralateral defects were randomized for test or control treatment. During a healing period of 6 weeks, gingival recession resulting in device exposure occurred at 3 test and 10 control sites. One control barrier was exfoliated. Histologically, 9 of the 12 test barriers were completely integrated with the surrounding tissues. At 3 test sites, epithelium had migrated apically outside the barrier to a level not exceeding one-third of the height of the device. Seven of the 11 control barriers were enclosed by dentogingival epithelium. The adjacent connective tissue exhibited local inflammatory cell infiltrates (ICT). At the remaining 4 control sites, the epithelial downgrowth as well as the adjacent ICT areas were limited to the coronal 1/3 of the device. New attachment; i.e., new cementum with inserting collagen fibers, averaged 2.2 mm and 0.8 mm at the test and control sites respectively (P < 0.01). Based on the results of the present study, it was concluded that a bioresorbable GTR device, designed to prevent epithelial downgrowth along the barrier surface, has a higher potential to promote new attachment formation than a device which does not have this property.

  10. Examples of Department of Energy Successes for Remediation of Contaminated Groundwater: Permeable Reactive Barrier and Dynamic Underground Stripping ASTD Projects

    SciTech Connect

    Purdy, C.; Gerdes, K.; Aljayoushi, J.; Kaback, D.; Ivory, T.

    2002-02-27

    Since 1998, the Department of Energy's (DOE) Office of Environmental Management has funded the Accelerated Site Technology Deployment (ASTD) Program to expedite deployment of alternative technologies that can save time and money for the environmental cleanup at DOE sites across the nation. The ASTD program has accelerated more than one hundred deployments of new technologies under 76 projects that focus on a broad spectrum of EM problems. More than 25 environmental restoration projects have been initiated to solve the following types of problems: characterization of the subsurface using chemical, radiological, geophysical, and statistical methods; treatment of groundwater contaminated with DNAPLs, metals, or radionuclides; and other projects such as landfill covers, purge water management systems, and treatment of explosives-contaminated soils. One of the major goals of the ASTD Program is to deploy a new technology or process at multiple DOE sites. ASTD projects are encouraged to identify subsequent deployments at other sites. Some of the projects that have successfully deployed technologies at multiple sites focusing on cleanup of contaminated groundwater include: Permeable Reactive Barriers (Monticello, Rocky Flats, and Kansas City), treating uranium and organics in groundwater; and Dynamic Underground Stripping (Portsmouth, and Savannah River), thermally treating DNAPL source zones. Each year more and more new technologies and approaches are being used at DOE sites due to the ASTD program. DOE sites are sharing their successes and communicating lessons learned so that the new technologies can replace the baseline or standard approaches at DOE sites, thus expediting cleanup and saving money.

  11. Measuring the fusion cross-section of 39,47K + 28Si at near barrier energies

    NASA Astrophysics Data System (ADS)

    Vadas, Justin; Singh, Varinderjit; Wiggins, Blake; Huston, Jacob; Hudan, Sylvie; Desouza, Romualdo; Chbihi, Abdou; Ackermann, Dieter; Brown, Kyle

    2017-01-01

    The outer crust of an accreting neutron star provides an interesting environment for nuclear reactions to occur. In particular, the enhancement of fusion between neutron-rich nuclei relative to their β-stable counterparts has been suggested as a trigger for an X-ray superburst. Recently, nuclei in the mass range of A=20-40 have been proposed as the most likely candidates for this process. To investigate this question, comparing the fusion excitation functions for both neutron-rich and β-stable nuclei at energies near the fusion barrier is necessary. The development of a 47K radioactive beam at NSCL's ReA3 facility makes such a comparison possible for the first time. An approved experiment to measure the fusion excitation functions for 39,47K + 28Si will be described. This experiment utilizes a technique optimized for measuring the total fusion cross-section of reactions involving low-intensity (103 - 106 ions/s) radioactive beams. In addition, protons and α particles emitted by the compound nucleus as it de-excites are measured. Preliminary results will be presented. Supported by DOE Grant No. DE-FG02-88ER-40404 and NSF Grant No. 1342962.

  12. Comparision between different metal oxide nanostructures and nanocomposites for sensing, energy generation, and energy harvesting

    NASA Astrophysics Data System (ADS)

    Willander, Magnus; Alnoor, Hatim; Elhag, Sami; Ibupoto, Zafar Hussain; Nour, Eiman Satti; Nur, Omer

    2016-02-01

    Highlights from research on different nanocomposites and nanostructures for sensing and other energy related applications will be presented. The synthesized nanostructures and nanocomposites presented here were all obtained using the low temperature (< 100 °C) chemical approach. Nanostructures featured by small foot-print and synthesized by the low temperature aqueous chemical approach allows the utilization of non-conventional solid and soft substrates like e.g. glass, plastic, textile and paper. We here present results from different metal oxide nanostructures employed for chemical sensing and some innovative energy related applications. Efficient sensitive and selective sensing of dopamine, melamine, and glucose are presented as some examples of self-powered sensors utilizing the electrochemical phenomenon i.e. transferring chemical energy into electrical signal. Further the use of nanomaterials for developing selfpowered devices utilizing mechanical ambient energy is presented via piezoelectric and triboelectric effects. Here the self-powered devices and systems were relying on utilizing the electormechanical phenomenon i.e. transferring ambient mechanical energy into useful electrical energy. Finally the visibility of nanomaterials prepared by the low temperature chemical synthesis as possible low cost replacement of Pt electrodes for hydrogen production is briefly presented and discussed.

  13. Nonstochastic effects of different energy beta emitters on pig skin.

    PubMed

    Peel, D M; Hopewell, J W; Wells, J; Charles, M W

    1984-08-01

    Circular areas of pig skin from 1- to 40-mm diameter were irradiated with beta emitters of high, medium, and low energies, 90Sr, 170Tm, and 147Pm, respectively. The study provides information for radiological protection problems of localized skin exposures. During the first 16 weeks after irradiation 90Sr produced a first reaction due to epithelial cell death followed by a second reaction attributable to damage to the dermal blood vessels. 170Tm and 147Pm produced the epithelial reaction only. The epithelial dose response varied as a function of beta energy. The doses required to produce moist desquamation in 50% of 15- to 22.5-mm fields (ED50) were 30-45 Gy from 90Sr, approximately 80 Gy from 170Tm, and approximately 500 Gy from 147Pm. A model involving different methods of epithelial repopulation is proposed to explain this finding. An area effect was observed in the epithelial response to 90Sr irradiation. The ED50 for moist desquamation ranged from approximately 25 Gy for a 40-mm source to approximately 450 Gy for a 1-mm source. The 5-, 9-, and 19-mm 170Tm sources all produced an ED50 of approximately 80 Gy, while the value for the 2-mm source was approximately 250 Gy. It is also suggested that the area effects could be explained by different modes of epithelial repopulation after irradiation. After high energy beta irradiation repopulation would be mainly from the field periphery, while after lower energy irradiation repopulation from hair follicle epithelium would predominate.

  14. Potential-barrier model at metal surfaces: Application to analyses of low-energy electron-diffraction fine-structure experiments

    NASA Astrophysics Data System (ADS)

    Mola, E. E.; Paola, C. A.; Vicente, J. L.

    1991-12-01

    We propose a model for the potential barrier for electrons crossing a metal surface, in which (1) we reproduce the effective potential of Lang and Kohn, in fact, better than any approximation in the existing literature and (2) we approach the classical image potential for large separation from the surface. Our potential does not diverge as the electron approaches the surface and goes over smoothly to the electron-electron interaction potential in the bulk. It reproduces the first peak in the effective potential of Lang and Kohn, which is a Friedel oscillation. We achieve better agreement with the Lang-Kohn potential than Jennings, Jones, and Weinert in their barrier model. This makes our model useful in the analysis of low-energy electron-diffraction fine-structure experiments. Our simple barrier model allows analytical solutions of the Schrödinger equation in the density-functional formalism.

  15. Interaction energy evaluation of soluble microbial products (SMP) on different membrane surfaces: role of the reconstructed membrane topology.

    PubMed

    Chen, Lin; Tian, Yu; Cao, Chu-qing; Zhang, Jun; Li, Zhi-neng

    2012-05-15

    Soluble microbial products (SMP), a majority of organic matter in effluents, play a key role in membrane fouling. A series of filtration experiments were conducted, and demonstrated that the flux decrement rate was in order of cellulose acetate membrane (CA, 65.4%), polyvinylidene fluoride (PVDF, 47.9%) and polyether sulfones (PES, 29.2%). Results showed that the fouling behavior of membrane should be predicted from the combined knowledge of solution chemistry, surface chemical properties and surface morphology. To better understand the interactions between the SMP and different membranes, a technique for reconstructing the membrane surface topology was developed on the basis of statistical parameters obtained from atomic force microscopy. The interaction energy, represented by extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) potential, was calculated by surface element integration, allowing exploring the interaction energy profiles for different surfaces and providing considerable insights into the role of such interactions on the macroscopic fouling behavior. The resulting interaction energy differed considerably from the corresponding interaction between perfectly smooth surfaces. The great influence of protrusion on the membrane surface was to reduce the primary energy barrier height, thus rendering rough surface more favorable for deposition. An attractive energy region was immediately surrounded by each positive asperity as demonstrated in the roughness-engendered interaction energy maps. As the SMP approached closer to the membrane, they had a high probability of getting trapped in the attractive energy region, leading to a more rapid loss of flux than smooth membrane.

  16. Energy expenditure on recreational visits to different natural environments.

    PubMed

    Elliott, Lewis R; White, Mathew P; Taylor, Adrian H; Herbert, Stephen

    2015-08-01

    Physical inactivity poses a significant challenge to physical and mental health. Environmental approaches to tackle physical inactivity have identified natural environments as potentially important public health resources. Despite this, little is known about characteristics of the activity involved when individuals visit different types of natural environment. Using Natural England's Monitor of Engagement with the Natural Environment Survey, we examined 71,603 English respondents' recreational visits to natural environments in the past week. Specifically, we examined the intensity of the activities they undertook on the visits (METs), the duration of their visit, and the associated total energy expenditure (MET minutes). Visits to countryside and urban greenspace environments were associated with more intense activities than visits to coastal environments. However, visits to coastal environments were associated with the most energy expenditure overall due to their relatively long duration. Results differed by the urbanity or rurality of the respondent's residence and also how far respondents travelled to their destination. Knowledge of what types of natural environment afford the highest volumes and intensities of physical activity could inform landscape architecture and exercise prescriptions. Isolating activity-supporting characteristics of natural environments that can be translated into urban design is important in providing physical activity opportunities for those less able to access expansive environments.

  17. Different mechanisms influencing permeation of PDGF-AA and PDGF-BB across the blood-brain barrier.

    PubMed

    Kastin, Abba J; Akerstrom, Victoria; Hackler, Laszlo; Pan, Weihong

    2003-10-01

    Platelet-derived growth factor (PDGF) exerts neurotrophic and neuromodulatory effects on the CNS. To determine the permeability of the blood-brain barrier (BBB) to PDGF, we examined the blood-to-brain influx of radioactively labeled PDGF isoforms (PDGF-AA and PDGF-BB) by multiple-time regression analysis after intravenous (i.v.) injection and by in-situ perfusion, and also determined the physicochemical characteristics which affect their permeation across the BBB, including lipophilicity (measured by octanol:buffer partition coefficient), hydrogen bonding (measured by differences in octanol : buffer and isooctane : buffer partition coefficients), serum protein binding (measured by capillary electrophoresis), and stability of PDGF in blood 10 min after i.v. injection (measured by HPLC). After i.v. bolus injection, neither 125I-PDGF-AA nor 125I-PDGF-BB crossed the BBB, their influx rates being similar to that of the vascular marker 99mTc-albumin. 125I-PDGF-AA degraded significantly faster in blood than 125I-PDGF-BB. PDGF-BB, however, was completely bound to a large protein in serum whereas PDGF-AA showed no binding. Thus, degradation might explain the poor blood-to-brain influx of PDGF-AA, whereas protein binding could explain the poor influx of circulating PDGF-BB. Despite their lack of permeation in the intact mouse, both 125I-PDGF-AA and 125I-PDGF-BB entered the brain by perfusion in blood-free buffer, and the significantly faster rate of 125I-PDGF-AA than 125I-PDGF-BB may be explained by the lower hydrogen bonding potential of 125I-PDGF-AA. Thus, the lack of significant distribution of PDGF from blood to brain is not because of the intrinsic barrier function of the BBB but probably because of degradation and protein binding. Information from these studies could be useful in the design of analogues for delivery of PDGF as a therapeutic agent.

  18. An in vitro comparative evaluation of different intraorifice barriers on the fracture resistance of endodontically treated roots obturated with gutta-percha

    PubMed Central

    Gupta, Abhishek; Arora, Vipin; Jha, Padmanabh; Nikhil, Vineeta; Bansal, Parul

    2016-01-01

    Aim: To compare and evaluate the root reinforcement potential of four different intraorifice barriers: Mineral trioxide aggregate (MTA), resin-modified glass ionomer cement (RMGIC), fiber-reinforced composite (FRC), and nanohybrid composite (NC). Materials and Methods: Seventy-five mandibular premolars were decoronated to a standardized length, and prepared and obturated with gutta-percha and AH Plus sealer. Except for control specimens, the coronal 3-mm gutta-percha was removed and filled with different materials. The specimens (75) were divided into five groups (n = 15) on the basis of the intraorifice barrier material used. Group 1: MTA, Group 2: RMGIC, Group 3: FRC, Group 4: NC, Group 5: no barrier (control). Fracture resistance of the specimens was tested. Results: Fracture resistance of roots was significantly affected by the type of intraorifice barrier used and the following pattern was observed: RMGIC > FRC > NC > MTA. Conclusion: Intraorifice barriers can be regarded as a viable choice to reduce the occurrence of postendodontic root fractures. Among the four tested materials, RMGIC showed the maximum reinforcement. PMID:27099413

  19. Fuelling in front of the barrier-are there age based behavioral differences in Garden Warblers Sylvia borin?

    PubMed

    Barboutis, Christos; Henshaw, Ian; Kullberg, Cecilia; Nikolopoulou, Stamatina; Fransson, Thord

    2014-01-01

    Garden Warblers Sylvia borin were studied during autumn stopover in Crete before crossing the barrier of the Mediterranean Sea and the Sahara Desert. Birds followed with transmitters show extensive stopover periods, which were longer in first-year birds, 16 days, compared with adult birds, 14 days. The distribution of body masses from birds trapped in fig trees were used to estimate the departure body mass and the results found indicate that both age categories on average depart with a fuel load close to 100% of lean body mass. The movement of transmitter birds shows differences between first-year and adult birds. Adult birds move further away from the release site and many also left the study area. Several were found settled outside the study area, up to 17 km away, indicating that they regularly make longer stopover movements. It is suggested that this might be a result of that they return to a place where they stayed during an earlier migration. It was shown that stopover site fidelity exists and nine garden warblers were recaptured in the area during a following autumn. The results found highlights the importance of stopover areas close to the Sahara Desert.

  20. Neutron transfer versus inelastic surface vibrations in the enhancement of sub-barrier fusion excitation function data and the energy dependent Woods-Saxon potential

    NASA Astrophysics Data System (ADS)

    Singh Gautam, Manjeet

    2015-02-01

    This work deeply analyzed the relative importance of the neutron transfer channels and inelastic surface vibrations of colliding nuclei in the sub-barrier fusion enhancement of various heavy ion systems using an energy dependent Woods-Saxon potential (EDWSP) model in conjunction with a one-dimensional Wong formula and the coupled channel formulation using the code CCFULL. The multi-phonon vibrational states of colliding nuclei and the nucleon transfer channels are found to be dominant internal degrees of freedom. The coupling between the relative motion of reactants and these relevant channels produces anomalously large sub-barrier fusion enhancement over the expectations of the one-dimensional barrier penetration model. In some cases, the influence of neutron transfer dominates over the couplings to low lying surface vibrational states of collision partners. Furthermore, the effects of coupling to inelastic surface excitations and the impact of neutron transfer channels with positive ground state Q-values are imitated due to energy dependence in the Woods-Saxon potential. In the EDWSP model calculations, a wide range for the diffuseness parameter, which is much larger than the value extracted from the elastic scattering data, is needed to account for the observed fusion enhancement in the close vicinity of the Coulomb barrier.

  1. Ubiquitous human ‘master’ origins of replication are encoded in the DNA sequence via a local enrichment in nucleosome excluding energy barriers

    NASA Astrophysics Data System (ADS)

    Drillon, Guénola; Audit, Benjamin; Argoul, Françoise; Arneodo, Alain

    2015-02-01

    As the elementary building block of eukaryotic chromatin, the nucleosome is at the heart of the compromise between the necessity of compacting DNA in the cell nucleus and the required accessibility to regulatory proteins. The recent availability of genome-wide experimental maps of nucleosome positions for many different organisms and cell types has provided an unprecedented opportunity to elucidate to what extent the DNA sequence conditions the primary structure of chromatin and in turn participates in the chromatin-mediated regulation of nuclear functions, such as gene expression and DNA replication. In this study, we use in vivo and in vitro genome-wide nucleosome occupancy data together with the set of nucleosome-free regions (NFRs) predicted by a physical model of nucleosome formation based on sequence-dependent bending properties of the DNA double-helix, to investigate the role of intrinsic nucleosome occupancy in the regulation of the replication spatio-temporal programme in human. We focus our analysis on the so-called replication U/N-domains that were shown to cover about half of the human genome in the germline (skew-N domains) as well as in embryonic stem cells, somatic and HeLa cells (mean replication timing U-domains). The ‘master’ origins of replication (MaOris) that border these megabase-sized U/N-domains were found to be specified by a few hundred kb wide regions that are hyper-sensitive to DNase I cleavage, hypomethylated, and enriched in epigenetic marks involved in transcription regulation, the hallmarks of localized open chromatin structures. Here we show that replication U/N-domain borders that are conserved in all considered cell lines have an environment highly enriched in nucleosome-excluding-energy barriers, suggesting that these ubiquitous MaOris have been selected during evolution. In contrast, MaOris that are cell-type-specific are mainly regulated epigenetically and are no longer favoured by a local abundance of intrinsic NFRs

  2. Ubiquitous human 'master' origins of replication are encoded in the DNA sequence via a local enrichment in nucleosome excluding energy barriers.

    PubMed

    Drillon, Guénola; Audit, Benjamin; Argoul, Françoise; Arneodo, Alain

    2015-02-18

    As the elementary building block of eukaryotic chromatin, the nucleosome is at the heart of the compromise between the necessity of compacting DNA in the cell nucleus and the required accessibility to regulatory proteins. The recent availability of genome-wide experimental maps of nucleosome positions for many different organisms and cell types has provided an unprecedented opportunity to elucidate to what extent the DNA sequence conditions the primary structure of chromatin and in turn participates in the chromatin-mediated regulation of nuclear functions, such as gene expression and DNA replication. In this study, we use in vivo and in vitro genome-wide nucleosome occupancy data together with the set of nucleosome-free regions (NFRs) predicted by a physical model of nucleosome formation based on sequence-dependent bending properties of the DNA double-helix, to investigate the role of intrinsic nucleosome occupancy in the regulation of the replication spatio-temporal programme in human. We focus our analysis on the so-called replication U/N-domains that were shown to cover about half of the human genome in the germline (skew-N domains) as well as in embryonic stem cells, somatic and HeLa cells (mean replication timing U-domains). The 'master' origins of replication (MaOris) that border these megabase-sized U/N-domains were found to be specified by a few hundred kb wide regions that are hyper-sensitive to DNase I cleavage, hypomethylated, and enriched in epigenetic marks involved in transcription regulation, the hallmarks of localized open chromatin structures. Here we show that replication U/N-domain borders that are conserved in all considered cell lines have an environment highly enriched in nucleosome-excluding-energy barriers, suggesting that these ubiquitous MaOris have been selected during evolution. In contrast, MaOris that are cell-type-specific are mainly regulated epigenetically and are no longer favoured by a local abundance of intrinsic NFRs encoded in

  3. Large cross sections for transitions with a small energy difference

    NASA Astrophysics Data System (ADS)

    McGuire, J. H.; Shakov, Kh. Kh.

    2009-05-01

    Cross sections for transitions between states with small differences in energy can be quite large. An example is the 1s-2p transition in atomic hydrogen caused by the impact of a fast charged particle [1] or a photon [3]. In such cases the actual cross section may become much larger than the simple geometric cross section. Such transitions are often difficult to observe in the laboratory. However, they can be evaluated numerically. This effect can be significant in analysis of astrophysical data, as pointed out by T. Nandi [2]. I discuss a few examples of calculations and give a physical explanation for this effect. [4pt] [1] J.H. McGuire, D. J. Land, J. G. Brennan and G. Basbas, Phys. Rev. A19, 2180 (1979).[0pt] [2] Kh.Kh. Shakov and J.H. McGuire, Phys. Rev. A67 033405 (2003). [0pt] [3] T. Nandi, private communication, 2008.

  4. Increasing the effective energy barrier promoted by the change of a counteranion in a Zn-Dy-Zn SMM: slow relaxation via the second excited state.

    PubMed

    Oyarzabal, I; Ruiz, J; Ruiz, E; Aravena, D; Seco, J M; Colacio, E

    2015-08-11

    The trinuclear complex [ZnCl(μ-L)Dy(μ-L)ClZn]PF6 exhibits a single-molecule magnetic behaviour under zero field with a relatively large effective energy barrier of 186 cm(-1). Ab initio calculations reveal that the relaxation of the magnetization is symmetry-driven (the Dy(III) ion possesses a C2 symmetry) and occurs via the second excited state.

  5. Computing the Free Energy Barriers for Less by Sampling with a Coarse Reference Potential while Retaining Accuracy of the Target Fine Model.

    PubMed

    Plotnikov, Nikolay V

    2014-08-12

    Proposed in this contribution is a protocol for calculating fine-physics (e.g., ab initio QM/MM) free-energy surfaces at a high level of accuracy locally (e.g., only at reactants and at the transition state for computing the activation barrier) from targeted fine-physics sampling and extensive exploratory coarse-physics sampling. The full free-energy surface is still computed but at a lower level of accuracy from coarse-physics sampling. The method is analytically derived in terms of the umbrella sampling and the free-energy perturbation methods which are combined with the thermodynamic cycle and the targeted sampling strategy of the paradynamics approach. The algorithm starts by computing low-accuracy fine-physics free-energy surfaces from the coarse-physics sampling in order to identify the reaction path and to select regions for targeted sampling. Thus, the algorithm does not rely on the coarse-physics minimum free-energy reaction path. Next, segments of high-accuracy free-energy surface are computed locally at selected regions from the targeted fine-physics sampling and are positioned relative to the coarse-physics free-energy shifts. The positioning is done by averaging the free-energy perturbations computed with multistep linear response approximation method. This method is analytically shown to provide results of the thermodynamic integration and the free-energy interpolation methods, while being extremely simple in implementation. Incorporating the metadynamics sampling to the algorithm is also briefly outlined. The application is demonstrated by calculating the B3LYP//6-31G*/MM free-energy barrier for an enzymatic reaction using a semiempirical PM6/MM reference potential. These modifications allow computing the activation free energies at a significantly reduced computational cost but at the same level of accuracy compared to computing full potential of mean force.

  6. Differences in amyloid-β clearance across mouse and human blood-brain barrier models: kinetic analysis and mechanistic modeling.

    PubMed

    Qosa, Hisham; Abuasal, Bilal S; Romero, Ignacio A; Weksler, Babette; Couraud, Pierre-Oliver; Keller, Jeffrey N; Kaddoumi, Amal

    2014-04-01

    Alzheimer's disease (AD) has a characteristic hallmark of amyloid-β (Aβ) accumulation in the brain. This accumulation of Aβ has been related to its faulty cerebral clearance. Indeed, preclinical studies that used mice to investigate Aβ clearance showed that efflux across blood-brain barrier (BBB) and brain degradation mediate efficient Aβ clearance. However, the contribution of each process to Aβ clearance remains unclear. Moreover, it is still uncertain how species differences between mouse and human could affect Aβ clearance. Here, a modified form of the brain efflux index method was used to estimate the contribution of BBB and brain degradation to Aβ clearance from the brain of wild type mice. We estimated that 62% of intracerebrally injected (125)I-Aβ40 is cleared across BBB while 38% is cleared by brain degradation. Furthermore, in vitro and in silico studies were performed to compare Aβ clearance between mouse and human BBB models. Kinetic studies for Aβ40 disposition in bEnd3 and hCMEC/D3 cells, representative in vitro mouse and human BBB models, respectively, demonstrated 30-fold higher rate of (125)I-Aβ40 uptake and 15-fold higher rate of degradation by bEnd3 compared to hCMEC/D3 cells. Expression studies showed both cells to express different levels of P-glycoprotein and RAGE, while LRP1 levels were comparable. Finally, we established a mechanistic model, which could successfully predict cellular levels of (125)I-Aβ40 and the rate of each process. Established mechanistic model suggested significantly higher rates of Aβ uptake and degradation in bEnd3 cells as rationale for the observed differences in (125)I-Aβ40 disposition between mouse and human BBB models. In conclusion, current study demonstrates the important role of BBB in the clearance of Aβ from the brain. Moreover, it provides insight into the differences between mouse and human BBB with regards to Aβ clearance and offer, for the first time, a mathematical model that describes

  7. Impact of microbial activities on the mineralogy and performance of column-scale permeable reactive iron barriers operated under two different redox conditions.

    PubMed

    Van Nooten, Thomas; Lieben, François; Dries, Jan; Pirard, Eric; Springael, Dirk; Bastiaens, Leen

    2007-08-15

    The present study focuses on the impact of microbial activities on the performance of various long-term operated laboratory-scale permeable reactive barriers. The barriers contained both aquifer and Fe0 compartments and had received either sulfate or iron(III)-EDTA to promote sulfate-reducing and iron(III)-reducing bacteria, respectively. After dismantlement of the compartments after almost 3 years of operation, DNA-based PCR-DGGE analysis revealed the presence of methanogenic, sulfate-reducing, metal-reducing, and denitrifying bacteria within as well as up- and downgradient of the Fe0 matrix. Under all imposed conditions, the main secondary phases were vivianite, siderite, ferrous hydroxy carbonate, and carbonate green rust as found by scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD). Under sulfate-reduction promoting conditions, iron sulfides were formed in addition, resulting in 7 and 10 times higher degradation rates for PCE and TCE, respectively, compared to unreacted iron. These results indicate that the presence of sulfate-reducing bacteria in or around iron barriers and the subsequent formation of iron sulfides might increase the barrier reactivity.

  8. Barriers in access to healthcare in countries with different health systems. A cross-sectional study in municipalities of central Colombia and north-eastern Brazil.

    PubMed

    Garcia-Subirats, Irene; Vargas, Ingrid; Mogollón-Pérez, Amparo Susana; De Paepe, Pierre; da Silva, Maria Rejane Ferreira; Unger, Jean Pierre; Vázquez, María Luisa

    2014-04-01

    There are few comprehensive studies available on barriers encountered from the initial seeking of healthcare through to the resolution of the health problem; in other words, on access in its broad domain. For Colombia and Brazil, countries with different healthcare systems but common stated principles, there have been no such analyses to date. This paper compares factors that influence access in its broad domain in two municipalities of each country, by means of a cross-sectional study based on a survey of a multistage probability sample of people who had had at least one health problem within the last three months (2163 in Colombia and 2155 in Brazil). The results reveal important barriers to healthcare access in both samples, with notable differences between and within countries, once differences in sociodemographic characteristics and health needs are accounted for. In the Colombian study areas, the greatest barriers were encountered in initial access to healthcare and in resolving the problem, and similarly when entering the health service in the Brazilian study areas. Differences can also be detected in the use of services: in Colombia greater geographical and economic barriers and the need for authorization from insurers are more relevant, whereas in Brazil, it is the limited availability of health centres, doctors and drugs that leads to longer waiting times. There are also differences according to enrolment status and insurance scheme in Colombia, and between areas in Brazil. The barriers appear to be related to the Colombian system's segmented, non-universal nature, and to the involvement of insurance companies, and to chronic underfunding of the public system in Brazil. Further research is required, but the results obtained reveal critical points to be tackled by health policies in both countries.

  9. α and 3He production in the 7Be+28Si reaction at near-barrier energies: Direct versus compound-nucleus mechanisms

    NASA Astrophysics Data System (ADS)

    Sgouros, O.; Pakou, A.; Pierroutsakou, D.; Mazzocco, M.; Acosta, L.; Aslanoglou, X.; Betsou, Ch.; Boiano, A.; Boiano, C.; Carbone, D.; Cavallaro, M.; Grebosz, J.; Keeley, N.; La Commara, M.; Manea, C.; Marquinez-Duran, G.; Martel, I.; Nicolis, N. G.; Parascandolo, C.; Rusek, K.; Sánchez-Benítez, A. M.; Signorini, C.; Soramel, F.; Soukeras, V.; Stefanini, C.; Stiliaris, E.; Strano, E.; Strojek, I.; Torresi, D.

    2016-10-01

    The production of α and 3He particles, the cluster constituents of 7Be, in the 7Be+28Si reaction was studied at three near-barrier energies, namely 13, 20, and 22 MeV. Angular distribution measurements were performed at each energy, and the data were analyzed in both statistical model and Distorted-Wave Born Approximation (DWBA) frameworks in order to disentangle the degree of competition between direct and compound channels. The energy evolution of the ratio of direct to total reaction cross section was mapped in comparison with similar data for 6Li and 7Li projectiles on a 28Si target. The results indicate larger transfer contributions for collisions involving the mirror nuclei 7Be and 7Li than in the 6Li case. Fusion cross sections were deduced, taking into account the α -particle cross sections due to compound-nucleus formation and particle multiplicities deduced from our statistical model framework. It was found that fusion is compatible with systematics and single-barrier penetration cross sections to within an uncertainty band of 10% to 20%. Indications of fusion hindrance for 7Li and 7Be compared to 6Li, starting from the barrier and below it, are given. This hindrance is attributed to the existence of large transfer channels. Furthermore, the experimental results, analyzed in the DWBA framework, suggest 3He and 4He transfer as the dominant direct reaction mechanism.

  10. Interstellar Isomers: The Importance of Bonding Energy Differences

    NASA Technical Reports Server (NTRS)

    Remijan, Anthony J.; Hollis, J. M.; Lovas, F. J.; Plusquellic, D. F.; Jewell, P. R.

    2005-01-01

    We present strong detections of methyl cyanide (CH3CN), vinyl cyanide (CH2CHCN), ethyl cyanide (CH3CH2CN) and cyanodiacetylene (HC4CN) molecules with the Green Bank Telescope (GBT) toward the Sgr B2(N) molecular cloud. Attempts to detect the corresponding isocyanide isomers were only successful in the case of methyl isocyanide (CH3NC) for its J(sub K) = 1(sub 0) - 0(sub 0) transition, which is the first interstellar report of this line. To determine the spatial distribution of CH3NC, we used archival Berkeley-Illinois-Maryland Association (BIMA) array data for the J(sub K) = 1(sub 0) - 0(sub 0) transitions but no emission was detected. From ab initio calculations, the bonding energy difference between the cyanide and isocyanide molecules is greater than 8500 per centimeter (greater than 12,000 K). Thus, cyanides are the more stable isomers and would likely be formed more preferentially over their isocyanide counterparts. That we detect CH3NC emission with a single antenna (Gaussian beamsize(omega(sub B))=1723 arcsec(sup 2)) but not with an interferometer (omega(sub b)=192 arcsec(sup 2)), strongly suggests that CH3NC has a widespread spatial distribution toward the Sgr B2(N) region. Other investigators have shown that CH3CN is present both in the LMH hot core of Sgr B2(N) and in the surrounding medium, while we have shown that CH3NC appears to be deficient in the LMH hot core. Thus, largescale, non-thermal processes in the surrounding medium may account for the conversion of CH3CN to CH3NC while the LMH hot core, which is dominated by thermal processes, does not produce a significant amount of CH3NC. Ice analog experiments by other investigators have shown that radiation bombardment of CH3CN can produce CH3NC, thus supporting our observations. We conclude that isomers separated by such large bonding energy differences are distributed in different interstellar environments, making the evaluation of column density ratios between such isomers irrelevant unless it can

  11. Two-barrier stability that allows low-power operation in current-induced domain-wall motion.

    PubMed

    Kim, Kab-Jin; Hiramatsu, Ryo; Koyama, Tomohiro; Ueda, Kohei; Yoshimura, Yoko; Chiba, Daichi; Kobayashi, Kensuke; Nakatani, Yoshinobu; Fukami, Shunsuke; Yamanouchi, Michihiko; Ohno, Hideo; Kohno, Hiroshi; Tatara, Gen; Ono, Teruo

    2013-01-01

    Energy barriers in magnetization reversal dynamics have long been of interest because the barrier height determines the thermal stability of devices as well as the threshold force triggering their dynamics. Especially in memory and logic applications, there is a dilemma between the thermal stability of bit data and the operation power of devices, because larger energy barriers for higher thermal stability inevitably lead to larger magnetic fields (or currents) for operation. Here we show that this is not the case for current-induced magnetic domain-wall motion induced by adiabatic spin-transfer torque. By quantifying domain-wall depinning energy barriers by magnetic field and current, we find that there exist two different pinning barriers, extrinsic and intrinsic energy barriers, which govern the thermal stability and threshold current, respectively. This unique two-barrier system allows low-power operation with high thermal stability, which is impossible in conventional single-barrier systems.

  12. Two-barrier stability that allows low-power operation in current-induced domain-wall motion

    NASA Astrophysics Data System (ADS)

    Kim, Kab-Jin; Hiramatsu, Ryo; Koyama, Tomohiro; Ueda, Kohei; Yoshimura, Yoko; Chiba, Daichi; Kobayashi, Kensuke; Nakatani, Yoshinobu; Fukami, Shunsuke; Yamanouchi, Michihiko; Ohno, Hideo; Kohno, Hiroshi; Tatara, Gen; Ono, Teruo

    2013-06-01

    Energy barriers in magnetization reversal dynamics have long been of interest because the barrier height determines the thermal stability of devices as well as the threshold force triggering their dynamics. Especially in memory and logic applications, there is a dilemma between the thermal stability of bit data and the operation power of devices, because larger energy barriers for higher thermal stability inevitably lead to larger magnetic fields (or currents) for operation. Here we show that this is not the case for current-induced magnetic domain-wall motion induced by adiabatic spin-transfer torque. By quantifying domain-wall depinning energy barriers by magnetic field and current, we find that there exist two different pinning barriers, extrinsic and intrinsic energy barriers, which govern the thermal stability and threshold current, respectively. This unique two-barrier system allows low-power operation with high thermal stability, which is impossible in conventional single-barrier systems.

  13. Physicians' psychosocial barriers to different modes of withdrawal of life support in critical care: A qualitative study in Japan.

    PubMed

    Aita, Kaoruko; Kai, Ichiro

    2010-02-01

    Despite a number of guidelines issued in Anglo-American countries over the past few decades for forgoing treatment stating that there is no ethically relevant difference between withholding and withdrawing life-sustaining treatments (LST), it is recognized that many healthcare professionals in Japan as well as some of their western counterparts do not agree with this statement. This research was conducted to investigate the barriers that prevent physicians from withdrawing specific LST in critical care settings, focusing mainly on the modes of withdrawal of LST, in what the authors believe was the first study of its kind anywhere in the world. In 2006-2007, in-depth, face-to-face, semistructured interviews were conducted with 35 physicians working at emergency and critical care facilities across Japan. We elicited their experiences, attitudes, and perceptions regarding withdrawal of mechanical ventilation and other LST. The process of data analysis followed the grounded theory approach. We found that the psychosocial resistance of physicians to withdrawal of artificial devices varied according to the modes of withdrawal, showing a strong resistance to withdrawal of mechanical ventilation that requires physicians to halt the treatment when continuation of its mechanical operation is possible. However, there was little resistance to the withdrawal of percutaneous cardiopulmonary support and artificial liver support when their continuation was mechanically or physiologically impossible. The physicians shared a desire for a "soft landing" of the patient, that is, a slow and gradual death without drastic and immediate changes, which serves the psychosocial needs of the people surrounding the patient. For that purpose, vasopressors were often withheld and withdrawn. The findings suggest what the Japanese physicians avoid is not what they call a life-shortening act but an act that would not lead to a soft landing, or a slow death that looks 'natural' in the eyes of those

  14. Schottky barrier height of Ni to β-(AlxGa1‑x)2O3 with different compositions grown by plasma-assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Ahmadi, Elaheh; Oshima, Yuichi; Wu, Feng; Speck, James S.

    2017-03-01

    Coherent β-(AlxGa1‑x)2O3 films (x = 0, 0.038, 0.084, 0.164) were grown successfully on a Sn-doped β-Ga2O3 (010) substrate using plasma-assisted molecular beam epitaxy. Atom probe tomography, transmission electron microscopy, and high resolution x-ray diffraction were used to verify the alloy composition and high quality of the films. Schottky diodes were then fabricated using Ni as the Schottky metal. Capacitance–voltage measurements revealed a very low (<7 × 1015 cm‑3) free charge density in the nominally undoped films. The barrier height and ideality factor were estimated by current–voltage (I–V) measurements performed at temperatures varying from 300 K to 500 K on the Schottky diodes. These measurements revealed that the apparent Schottky barrier height could have similar values for different compositions of β-(AlxGa1‑x)2O3. We believe this is attributed to the lateral fluctuation in the alloy’s composition. This results in a lateral variation in the barrier height. Therefore, the average Schottky barrier height extracted from I–V measurements could be similar for β-(AlxGa1‑x)2O3 films with different compositions.

  15. Diffusion barriers

    NASA Technical Reports Server (NTRS)

    Nicolet, M. A.

    1983-01-01

    The choice of the metallic film for the contact to a semiconductor device is discussed. One way to try to stabilize a contact is by interposing a thin film of a material that has low diffusivity for the atoms in question. This thin film application is known as a diffusion barrier. Three types of barriers can be distinguished. The stuffed barrier derives its low atomic diffusivity to impurities that concentrate along the extended defects of a polycrystalline layer. Sacrificial barriers exploit the fact that some (elemental) thin films react in a laterally uniform and reproducible fashion. Sacrificial barriers have the advantage that the point of their failure is predictable. Passive barriers are those most closely approximating an ideal barrier. The most-studied case is that of sputtered TiN films. Stuffed barriers may be viewed as passive barriers whose low diffusivity material extends along the defects of the polycrystalline host.

  16. Interhabitat differences in energy acquisition and expenditure in a lizard

    SciTech Connect

    Karasov, W.H.; Anderson, R.A.

    1984-02-01

    Cnemidophorus hyperythrus, a small (approx. =4-g) teiid lizard, occurs along an elevational thorn scrub-thorn woodland-thorn forest habitat gradient in the cape region of Baja California. The authors compared body size, daily energy expenditure (DEE, measured with double labeled water), relative feeding rate (as reflected by H/sub 2/O influx rate), behavior, and abundance of this species at two sites along the gradient. At the inland thorn woodland site C. hyperythrus were more abundant (approx. =50 lizards/ha.). Mean body mass of woodland site lizards was 13% greater than that of scrub lizards. The DEE of the thorn woodland lizards, 330 site J x g/sup -1/ x d/sup -1/, and their H/sub 2/O influx, 99 mm/sup 3/ x g/sup -1/ x d/sup -1/, were also higher than the thorn scrub lizards', 219 J x g/sup -1/ x d/sup -1/ and 52 mm/sup 3/ x g/sup -1/ x d/sup -1/. Diets at the two sites were similar. There were no differences between sexes in diet, DEE, or H/sub 2/ influx. Daily maintenance energy costs were calculated based upon laboratory measures of O/sub 2/ consumption of resting lizards at a series of temperatures that represented the daily range of body temperatures experienced by lizards in the field. Activity costs (=DEE minus maintenance) were three times higher in the woodland lizards. Behavioral observations showed that woodland lizards were active most of the day (approx. =9 h/d) whereas scrub lizards were active primarily in the morning (approx. =3.5 h/d). Thus, the higher activity cost, DEE, and feeding rate of woodland lizards can be explained by their longer daily activity period. We suggest causal factors for the difference in daily activity period, and discuss implications of length of daily forging period for adult body size, population density, and various life history parameters of lizards.

  17. Interhabitat differences in energy acquisition and expenditure in a lizard

    SciTech Connect

    Karasov, W.H.; Anderson, R.A.

    1984-02-01

    Cnemidophorus hyperythrus, a small (approx. =4-g) teiid lizard, occurs along an elevational thorn scrub - thorn woodland - thorn forest habitat gradient in the cape region of Baja California. Body size, daily energy expenditure (DEE, measured with doubly labeled water), relative feeding rate (as reflected by H/sub 2/O influx rate), behavior, and abundance of this species at two sites along the gradient were compared. At the inland thorn woodland site C. hyperythrus were more abundant (approx. =100 lizards/ha) than at the thorn scrub site near the ocean (approx. =50 lizards/ha). Mean body mass of woodland site lizards was 13% greater than that of scrub lizards. The DEE of the thorn woodland lizards, 330 J x g/sup -1/ x d/sup -1/,> and their H/sub 2/O influx, 99 mm/sup 3/ x g/sup -1/ x d/sup -1/, were also higher than the thorn scrub lizards', 219 J x g/sup -1/ x d/sup -1/ and 52 mm/sup 3/ x g/sup -1/ x d/sup -1/. Diets at the two sites were similar. There were no differences between sexes in diet, DEE, or H/sub 2/O influx. Daily maintenance energy costs were calculated based upon laboratory measures of O/sub 2/ consumption of resting lizards at a series of temperatures that represented the daily range of body temperatures experienced by lizards in the field. Activity costs (=DEE minus maintenance) were three times higher in the woodland lizards. Behavioral observations showed that woodland lizards were active most of the day (approx. =9 h/d) whereas scrub lizards were active primarily in the morning (approx. =3.5 h/d). Thus, the higher activity cost, DEE, and feeding rate of woodland lizards can be explained by their longer daily activity period. Causal factors for the difference in daily activity period are suggested, and implications of length of daily foraging period for adult body, size, population density, and various life history parameters of lizards are discussed.

  18. Eddy covariance measurement of the spatial heterogeneity of surface energy exchanges over Heron Reef, Great Barrier Reef, Australia

    NASA Astrophysics Data System (ADS)

    MacKellar, M.; McGowan, H. A.; Phinn, S. R.

    2011-12-01

    Coral reefs cover 2.8 to 6.0 x 105 km2 of the Earth's surface and are warm, shallow regions that are believed to contribute enhanced sensible and latent heat to the atmosphere, relative to the surrounding ocean. To predict the impact of climate variability on coral reefs and their weather and climate including cloud, winds, rainfall patterns and cyclone genesis, accurate parameterisation of air-sea energy exchanges over coral reefs is essential. This is also important for the parameterisation and validation of regional to global scale forecast models to improve prediction of tropical and sub-tropical marine and coastal weather. Eddy covariance measurements of air-sea fluxes over coral reefs are rare due to the complexities of installing instrumentation over shallow, tidal water. Consequently, measurements of radiation and turbulent flux data for coral reefs have been captured remotely (satellite data) or via single measurement sites downwind of coral reefs (e.g. terrestrial or shipboard instrumentation). The resolution of such measurements and those that have been made at single locations on reefs may not capture the spatial heterogeneity of surface-atmosphere energy exchanges due to the different geomorphic and biological zones on coral reefs. Accordingly, the heterogeneity of coral reefs with regard to substrate, benthic communities and hydrodynamic processes are not considered in the characterization of the surface radiation energy flux transfers across the water-atmosphere interface. In this paper we present a unique dataset of concurrent in situ eddy covariance measurements made on instrumented pontoons of the surface energy balance over different geomorphic zones of a coral reef (shallow reef flat, shallow and deep lagoons). Significant differences in radiation transfers and air-sea turbulent flux exchanges over the reef were highlighted, with higher Bowen ratios over the shallow reef flat. Increasing wind speed was shown to increase flux divergence between

  19. Importance of sports during youth and exercise barriers in 20- to 29-year-old male nonathletes differently motivated for regular physical activities.

    PubMed

    Leyk, Dieter; Witzki, Alexander; Sievert, Alexander; Rohde, Ulrich; Moedl, Anne; Rüther, Thomas; Löllgen, Herbert; Hackfort, Dieter

    2012-07-01

    The number of sedentary young adults has dramatically increased in past decades, and sedentary lifestyles are adopted at an increasingly earlier age. Little is known about barriers or predictors to (re)initiate regular physical activity in this group. The purpose of the study is to (a) identify subgroups in nonathletes differing in their amenability to physical exercise, (b) to analyze them for differences in barriers and intention to exercise, and (c) compare importance of sports during youth in nonathletes to trained peers. Using a health and fitness questionnaire 589 nonathletes were queried in the cross-sectional survey and compared with 270 trained peers. Athletic abstainers (A), lower (L), and higher (H) motivated nonathletes were separated based on previous engagement in sports. Of the nonathletes, 54.7% reported only 1 barrier to exercise. Although this feature was most prominent in H (71.5%), the other groups showed significantly more barriers and a broader distribution. Similar characteristics but minor differences were observed for perceived importance of sports during youth. The most significant differences between athletes and nonathletes emerged enquiring the attitude and activity of the parents. The majority of nonathletes (72.8%) indicate their intention to exercise in the future. Their intention differed significantly in H (88.1%), L (76.1%), and A (59.1%). However, there are good reasons to doubt that most of those intending nonathletes will actually become physically active. Even in the analyzed narrow age range of men different motivated groups of nonathletes were found. Because of the differences in receptiveness and approachability health promotion policies may not only consider the often recommended tailored interventions but also carefully designed incentive programs.

  20. Barriers and opportunities for improving energy efficiency in the social housing sector: Case study of E4C's Division of Housing and Mental Health

    NASA Astrophysics Data System (ADS)

    Marchand-Smith, Patrick

    Energy efficiency improvements in the social housing sector have the potential to produce a range of environmental and social benefits. These improvements can be produced through retrofits that deliver energy savings or new construction built to a high standard of energetic efficiency. However, implementation of these approaches is hindered by economic and organizational constraints affecting the agencies that provide society with social housing and the governments that support the provision of these services. This thesis builds on the work of other researchers studying these constraints by supplying an in-depth case study from Alberta and a discussion based on its findings. The case study focuses on E4C, a social service agency with several housing projects. Overall, findings matched important themes identified in the academic literature. The in-depth nature of the case study added additional insight to many of these themes. Most barriers are economic in nature and related to a lack of sufficient funding or the up-front costs of energy-saving retrofits. The recommendations presented are based on consideration of the multiple barriers and opportunities faced. Most of these require a considerable investment of time on the part of agencies and would be followed up by capital investments to implement energy-saving changes. Therefore it is important to note that the most significant barrier is commitment, which is one of E4C's central values. This thesis showed that commitment cannot exceed capacity to act. Greater commitment on the part of governments, agencies or society at large could have significant impacts in improving the energy efficiency of buildings in the Albertan, and Canadian, social housing sector.

  1. Comparative study of different waste biomass for energy application.

    PubMed

    Motghare, Kalyani A; Rathod, Ajit P; Wasewar, Kailas L; Labhsetwar, Nitin K

    2016-01-01

    Biomass is available in many varieties, consisting of crops as well as its residues from agriculture, forestry, and the agro-industry. These different biomass find their way as freely available fuel in rural areas but are also responsible for air pollution. Emissions from such solid fuel combustion to indoor, regional and global air pollution largely depend on fuel types, combustion device, fuel properties, fuel moisture, amount of air supply for combustion and also on climatic conditions. In both economic and environment point of view, gasification constitutes an attractive alternative for the use of biomass as a fuel, than the combustion process. A large number of studies have been reported on a variety of biomass and agriculture residues for their possible use as renewable fuels. Considering the area specific agriculture residues and biomass availability and related transportation cost, it is important to explore various local biomass for their suitability as a fuel. Maharashtra (India) is the mainstay for the agriculture and therefore, produces a significant amount of waste biomass. The aim of the present research work is to analyze different local biomass wastes for their proximate analysis and calorific value to assess their potential as fuel. The biomass explored include cotton waste, leaf, soybean waste, wheat straw, rice straw, coconut coir, forest residues, etc. mainly due to their abundance. The calorific value and the proximate analysis of the different components of the biomass helped in assessing its potential for utilization in different industries. It is observed that ash content of these biomass species is quite low, while the volatile matter content is high as compared to Indian Coal. This may be appropriate for briquetting and thus can be used as a domestic fuel in biomass based gasifier cook stoves. Utilizing these biomass species as fuel in improved cook-stove and domestic gasifier cook-stoves would be a perspective step in the rural energy and

  2. Health and climate benefits of different energy-efficiency and renewable energy choices

    NASA Astrophysics Data System (ADS)

    Buonocore, Jonathan J.; Luckow, Patrick; Norris, Gregory; Spengler, John D.; Biewald, Bruce; Fisher, Jeremy; Levy, Jonathan I.

    2016-01-01

    Energy efficiency (EE) and renewable energy (RE) can benefit public health and the climate by displacing emissions from fossil-fuelled electrical generating units (EGUs). Benefits can vary substantially by EE/RE installation type and location, due to differing electricity generation or savings by location, characteristics of the electrical grid and displaced power plants, along with population patterns. However, previous studies have not formally examined how these dimensions individually and jointly contribute to variability in benefits across locations or EE/RE types. Here, we develop and demonstrate a high-resolution model to simulate and compare the monetized public health and climate benefits of four different illustrative EE/RE installation types in six different locations within the Mid-Atlantic and Lower Great Lakes of the United States. Annual benefits using central estimates for all pathways ranged from US$5.7-US$210 million (US$14-US$170 MWh-1), emphasizing the importance of site-specific information in accurately estimating public health and climate benefits of EE/RE efforts.

  3. Identifying perceived barriers and benefits to reducing energy consumption in an affordable housing complex using the Community-Based Social Marketing model

    NASA Astrophysics Data System (ADS)

    Reaves, Daniel

    Energy production and consumption has a negative impact on both environmental and human health. Energy consumption can be directly impacted by human behavior, especially in the residential sector. As a result, this sector has been studied significantly; however, energy reducing behavior change research focusing on the affordable housing sector has not been studied thoroughly to date. This study seeks to implement the first two phases of the Community Based Social Marketing (CBSM) framework in an affordable housing setting. The goals were to identify the optimal behaviors for energy reduction based on phase one survey results and to identify the perceived benefits and barriers associated with those behaviors. Additionally, this study identified nuances in the CBSM process that researchers should take into consideration when implementing CBSM in an affordable housing environment.

  4. Structure and energy difference of two isomers of He-CH3F.

    PubMed

    Higgins, Kelly J; Klemperer, William

    2005-06-22

    The intermolecular potential surface of He-CH(3)F is investigated through ab initio calculations and microwave and millimeter-wave spectroscopies. The intermolecular potential is calculated at the fourth-order Møller-Plesset level with a large basis set including bond functions. Three minimums exist, the deepest of which is at the carbon end of the C-F axis and has a depth of 46.903 cm(-1), the second deepest is in a T-shaped position relative to the C-F axis with a depth of 44.790 cm(-1), and the shallowest is at the fluorine end of the C-F axis with a depth of 30.929 cm(-1). The barrier to internal rotation of the CH(3)F subunit about its C-F axis is very low, thus leading to essentially free internal rotation and two separate sets of bound states correlating to ortho-CH(3)F (|K| = 3n) for the ground, or A, internal rotor state upon which this study focuses, and to para-CH(3)F (|K| = 3n +/- 1) for the excited, or E, internal rotor state. Bound-state calculations of the A state performed using two different techniques show the lowest-energy state to have the helium localized in the T-shaped well with an energy of -11.460 cm(-1), while two excited configurations of the A state have the helium localized either in the well at the carbon end ("linear") with an energy of -7.468 cm(-1) or in the well at the fluorine end ("antilinear") with an energy of -4.805 cm(-1). Spectroscopic observations confirm the predicted energy-level structure of the ground and first excited states. Sixteen transitions between 12 distinct energy levels have been observed, including pure rotational transitions of both the T-shaped ground state and the linear excited state, as well as rovibrational transitions between the ground state and the linear excited state. The energy difference between the T-shaped state and the linear state is measured to be 132 374.081(16) MHz. There is significant Coriolis mixing of the ground state J(K(a)K(c)) = 2(20) and the linear J(K) = 2(0) levels which aided

  5. Energy Use and Quality of Foods Cooked by Different Appliances.

    ERIC Educational Resources Information Center

    Odland, Dianne; And Others

    1987-01-01

    The authors compared energy consumption, cooking time, and quality of five foods cooked using electric range surface units and oven, induction cooktop, electric frypan, microwave oven, and toaster oven. The induction cooktop was among the most energy conserving. For most products, cooking treatment had little impact on quality. (Author/CH)

  6. Observations of Surface Energy Fluxes and Boundary-Layer Structure Over Heron Reef, Great Barrier Reef, Australia

    NASA Astrophysics Data System (ADS)

    MacKellar, Mellissa C.; McGowan, Hamish A.; Phinn, Stuart R.; Soderholm, Joshua S.

    2013-02-01

    Over warm, shallow coral reefs the surface radiation and energy fluxes differ from those of the open ocean and result in modification to the marine atmospheric boundary layer via the development of convective internal boundary layers. The complex interrelationships between the surface energy balance and boundary-layer characteristics influence local weather (wind, temperature, humidity) and hydrodynamics (water temperature and currents), as well as larger scale processes, including cloud field properties and precipitation. The nature of these inter-relationships has not been accurately described for coral reef environments. This study presents the first measurements of the surface energy balance, radiation budget and boundary layer thermodynamics made over a coral reef using an eddy-covariance system and radiosonde aerological profiling of the lower atmosphere. Results show that changes in surface properties and the associated energetics across the ocean-reef boundary resulted in modification to the marine atmospheric boundary layer during the Austral winter and summer. Internal convective boundary layers developed within the marine atmospheric boundary layer over the reef and were found to be deeper in the summer, yet more unstable during the winter when cold and drier flow from the mainland enhances heat and moisture fluxes to the atmosphere. A mixed layer was identified in the marine atmospheric boundary layer varying from 375 to 1,200 m above the surface, and was deeper during the summer, particularly under stable anticyclonic conditions. Significant cloud cover and at times rain resulted in the development of a stable stratified atmosphere over the reef. Our findings show that, for Heron Reef, a lagoonal platform reef, there was a horizontal discontinuity in surface energy fluxes across the ocean-reef boundary, which modified the marine atmospheric boundary layer.

  7. Fabrication of double barrier structures in single layer c-Si-QDs/a-SiOx films for realization of energy selective contacts for hot carrier solar cells

    NASA Astrophysics Data System (ADS)

    Kar, Debjit; Das, Debajyoti

    2017-01-01

    Thin films of c-Si-QDs embedded in an a-SiOx dielectric matrix forming arrays of double barrier structures have been fabricated by reactive rf-magnetron sputtering at ˜400 °C, without post-deposition annealing. The formation of larger size c-Si-QDs of reduced number density in homogeneous distribution within a less oxygenated a-SiOx matrix at higher plasma pressure introduces systematic widening of the average periodic distance between the adjacent `c-Si-QDs in a-SiOx', as obtained by X-ray reflectivity and transmission electron microscopy studies. A wave-like pattern in the J-E characteristics identifies the formation of periodic double-barrier structures along the path of the movement of charge carriers across the QDs and that those are originated by the a-SiOx dielectric matrix around the c-Si-QDs. A finite distribution of the size of c-Si-QDs introduces a broadening of the current density peak and simultaneously originates the negative differential resistance-like characteristics, which have suitable applications in the energy selective contacts that act as energy filters for hot carrier solar cells. A simple yet effective process technology has been demonstrated. Further initiative on tuning the energy selectivity by reducing the size and narrowing the size-distribution of Si-QDs can emerge superior energy selective contacts for hot carrier solar cells, paving ground for accomplishing all-Si solar cells.

  8. Equilibrium free-energy differences at different temperatures from a single set of nonequilibrium transitions

    NASA Astrophysics Data System (ADS)

    Patra, Puneet Kumar; Bhattacharya, Baidurya

    2016-10-01

    Crook's fluctuation theorem (CFT) and Jarzynski equality (JE) are effective tools for obtaining free-energy difference Δ F (λA→λB,T0) through a set of finite-time protocol driven nonequilibrium transitions between two equilibrium states A and B [parametrized by the time-varying protocol λ (t ) ] at the same temperature T0. Using the generalized dimensionless work function Δ WG , we extend CFT to transitions between two nonequilibrium steady states (NESSs) created by a thermal gradient. We show that it is possible, provided the period over which the transitions occur is sufficiently long, to obtain Δ F (λA→λB,T0) for different values of T0, using the same set of finite-time transitions between these two NESSs. Our approach thus completely eliminates the need to make new samples for each new T0. The generalized form of JE arises naturally as the average of the exponentiated Δ WG . The results are demonstrated on two test cases: (i) a single particle quartic oscillator having a known closed form Δ F , and (ii) a one-dimensional ϕ4 chain. Each system is sampled from the canonical distribution at an arbitrary T' with λ =λA , then subjected to a temperature gradient between its ends, and after steady state is reached, the protocol change λA→λB is effected in time τ , following which Δ WG is computed. The reverse path likewise initiates in equilibrium at T' with λ =λB and the protocol is time reversed leading to λ =λA and the reverse Δ WG . Our method is found to be more efficient than either JE or CFT when free-energy differences at multiple T0's are required for the same system.

  9. Evaluation of atrazine degradation applied to different energy systems.

    PubMed

    Moreira, Ailton J; Pinheiro, Bianca S; Araújo, André F; Freschi, Gian P G

    2016-09-01

    Atrazine is an herbicide widely used in crops and has drawn attention due to potential pollution present in soil, sediment, water, and food. Since conventional methods are not potentially efficient to persistent degradation of organic compounds, new technology has been developed to remove them, especially practices utilizing advanced oxidation processes (AOPs). This work aims to evaluate the use of different energies (ultraviolet (UV), microwaves (MW), and radiations (MW-UV)) to the herbicide atrazine through the process of photo-oxidation. These systems found degradation rates of around 12 % (UV), 28 % (MW), and 83 % (MW-UV), respectively, with time intervals of 120 s. After the photolytic processes, the samples were analyzed at a wavelength scanning the range of 190 to 300 nm, where the spectral analysis of the signal was used to evaluate the degradation of atrazine and the appearance of some other peaks (degradation products). The spectrum evaluation resulting from photolytic processes gave rise to a new signal which was confirmed by chromatography. This spectrum indicated the possible pathway of atrazine degradation by the process of photolytic MW-UV, generating atrazine-2-hydroxy, atrazine-desethyl-2-hidroxy, and atrazine-desisopropyl-2-hydroxy. The process indicated that in all situations, chloride was present in the analytic structure and was substituted by a hydroxyl group, which lowered the toxicity of the compound through the photolytic process MW-UV. Chromatographic analysis ascertained these preliminary assessments using spectrophotometry. It was also significantly observed that the process can be optimized by adjusting the pH of the solution, which was evident by an improvement of 10 % in the rate of degradation when subjected to a pH solution equal to 8.37.

  10. Energy Inputs Uncertainty: Total Amount, Distribution and Correlation Between Different Forms of Energy

    NASA Technical Reports Server (NTRS)

    Deng, Yue

    2014-01-01

    Describes solar energy inputs contributing to ionospheric and thermospheric weather processes, including total energy amounts, distributions and the correlation between particle precipitation and Poynting flux.

  11. Differences between African-American and Caucasian students on enrollment influences and barriers in kinesiology-based allied health education programs.

    PubMed

    Barfield, J P; Cobler, D C; Lam, Eddie T C; Zhang, James; Chitiyo, George

    2012-06-01

    Kinesiology departments have recently started to offer allied health education programs to attract additional students to teacher education units (9). Although allied health professions offer increased work opportunities, insufficient enrollment and training of minority students in these academic fields contribute to underrepresentation in the workforce (3). To improve workforce diversity, kinesiology departments must understand how enrollment influences and barriers differ by race among prospective students. Therefore, the purpose of this study was to identify differences in allied health education enrollment influences and enrollment barriers between minority and Caucasian students. Participants (n = 601) consisted of students enrolled in kinesiology-based allied health education programs. Multivariate ANOVA was used to compare group differences in enrollment decision making. "Personal influence," "career opportunity," and "physical self-efficacy" were all significantly stronger enrollment influences among African-American students than among Caucasian students, and "social influence," "experiential opportunity," "academic preparation," and "physical self-efficacy" were all perceived as significantly greater barriers compared with Caucasian students. Findings support the need to recruit African-American students through sport and physical education settings and to market program-based experiential opportunities.

  12. The importance of the different kinds of energy sources for energy future of Turkey

    NASA Astrophysics Data System (ADS)

    Kaplan, Yusuf Alper; Aladağ, Canan

    2016-11-01

    Nowadays, the need of energy has been increasing day by day with the population growth and the advancements of technology. In this study, the current state of nuclear, wind and solar energy on the worldwide has been generally investigated. The general assessments have been made based on Turkey's energy potential and the evaluation situation of this potential. The current political structures of countries are generally assessed and under this policy, the last situation and the latest implemented innovations are given. Turkey's energy demand is constantly increasing and Turkey is a country that needs to energy imports. This is a need for new energy sources to meet the growing need for energy. Nuclear, wind and solar energy are the new sources of energy to the fore in our country recently. In this study is given general information on the usage of energy sources of making and some deficiencies were been emphasized by political considerations in this regard.

  13. Elastic Barrier Dynamical Freezing in Free Energy Calculations: A Way To Speed Up Nonequilibrium Molecular Dynamics Simulations by Orders of Magnitude.

    PubMed

    Giovannelli, Edoardo; Cardini, Gianni; Chelli, Riccardo

    2016-03-08

    An important issue concerning computer simulations addressed to free energy estimates via nonequilibrium work theorems, such as the Jarzynski equality [Phys. Rev. Lett. 1997, 78, 2690], is the computational effort required to achieve results with acceptable accuracy. In this respect, the dynamical freezing approach [Phys. Rev. E 2009, 80, 041124] has been shown to improve the efficiency of this kind of simulations, by blocking the dynamics of particles located outside an established mobility region. In this report, we show that dynamical freezing produces a systematic spurious decrease of the particle density inside the mobility region. As a consequence, the requirements to apply nonequilibrium work theorems are only approximately met. Starting from these considerations, we have developed a simulation scheme, called "elastic barrier dynamical freezing", according to which a stiff potential-energy barrier is enforced at the boundaries of the mobility region, preventing the particles from leaving this region of space during the nonequilibrium trajectories. The method, tested on the calculation of the distance-dependent free energy of a dimer immersed into a Lennard-Jones fluid, provides an accuracy comparable to the conventional steered molecular dynamics, with a computational speedup exceeding a few orders of magnitude.

  14. Polarization Energies at Organic-Organic Interfaces: Impact on the Charge Separation Barrier at Donor-Acceptor Interfaces in Organic Solar Cells.

    PubMed

    Ryno, Sean M; Fu, Yao-Tsung; Risko, Chad; Brédas, Jean-Luc

    2016-06-22

    We probe the energetic landscape at a model pentacene/fullerene (C60) interface to investigate the interactions between positive and negative charges, which are critical to the processes of charge separation and recombination in organic solar cells. Using a polarizable force field, we find that polarization energy, i.e., the stabilization a charge feels due to its environment, is larger at the interface than in the bulk for both a positive and a negative charge. The combination of the charge being more stabilized at the interface and the Coulomb attraction between the charges results in a barrier to charge separation at the pentacene/C60 interface that can be in excess of 0.7 eV for static configurations of the donor and acceptor locations. However, the impact of molecular motions, i.e., the dynamics, at the interface at room temperature results in a distribution of polarization energies and in charge separation barriers that can be significantly reduced. The dynamic nature of the interface is thus critical, with the polarization energy distributions indicating that sites along the interface shift in time between favorable and unfavorable configurations for charge separation.

  15. Consumer Attitudes About Renewable Energy: Trends and Regional Differences

    SciTech Connect

    Natural Marketing Institute, Harleysville, Pennsylvania

    2011-04-01

    The data in this report are taken from Natural Marketing Institute's (NMI's) Lifestyles of Health and Sustainability Consumer Trends Database. Created in 2002, the syndicated consumer database contains responses from 2,000 to 4,000 nationally representative U.S. adults (meaning the demographics of the sample are consistent with U.S. Census findings) each year. NMI used the database to analyze consumer attitudes and behavior related to renewable energy and to update previously conducted related research. Specifically, this report will explore consumer awareness, concerns, perceived benefits, knowledge of purchase options, and usage of renewable energy as well as provide regional comparisons and trends over time.

  16. Consumer Attitudes About Renewable Energy. Trends and Regional Differences

    SciTech Connect

    Bird, Lori; Sumner, Jenny

    2011-04-01

    The data in this report are taken from Natural Marketing Institute's (NMI's) Lifestyles of Health and Sustainability Consumer Trends Database. Created in 2002, the syndicated consumer database contains responses from 2,000 to 4,000 nationally representative U.S. adults (meaning the demographics of the sample are consistent with U.S. Census findings) each year. NMI used the database to analyze consumer attitudes and behavior related to renewable energy and to update previously conducted related research. Specifically, this report will explore consumer awareness, concerns, perceived benefits, knowledge of purchase options, and usage of renewable energy as well as provide regional comparisons and trends over time.

  17. OVERCOMING CULTURAL BARRIERS.

    ERIC Educational Resources Information Center

    BARRUTIA, RICHARD

    THE RELATIONSHIP OF LANGUAGE DEVELOPMENT TO CULTURAL BARRIERS AND THE TEACHING OF FOREIGN LANGUAGES IS DISCUSSED IN THIS ARTICLE. VARIOUS VIEWS OF THE MEANING OF CULTURE ARE MENTIONED IN ORDER TO SINGLE OUT ANTHROPOLOGICAL CULTURE AS A MAIN FOCAL POINT. INTERCULTURAL DIFFERENCES ARE SPELLED OUT WITH EXAMPLES OF LINGUISTIC BARRIERS, AND…

  18. Confounding parameters in preclinical assessment of blood-brain barrier permeation: an overview with emphasis on species differences and effect of disease states.

    PubMed

    Deo, Anand K; Theil, Frank-Peter; Nicolas, Jean-Marie

    2013-05-06

    Drug delivery across the brain-blood interfaces is a complex process involving physicochemical drug properties, transporters, enzymes, and barrier dysfunction in diseased conditions. Intact blood-brain barrier (BBB) limits the entry of potentially harmful compounds into the brain but may also reduce the CNS permeability of therapeutic agents. BBB permeability is typically assessed by measuring brain-to-plasma ratio in rodents (referred to as B/P ratio, BB, or Kp, often calculated as logBB), an approach that suffers significant limitations as discussed in the present review. Kp is not a permeability measurement but a partition coefficient mainly driven by the relative binding to plasma and brain tissue components including lipids, phospholipids, and proteins. Compounds with high Kp are often lipophilic with low free fraction available to mediate CNS activities. Efforts should be more concentrated on measuring pharmacologically relevant free drug concentrations at the target site. Using healthy rodents to predict brain penetration in patients might be biased due to species differences in BBB-related parameters such as transporter expression and functional activities. In addition, pathophysiological conditions such as aging, multiple sclerosis, and Alzheimer's and Parkinson's diseases have been described to affect BBB permeability, with barrier leakage and altered transporter activity. The impact of these species differences and disease states on drug delivery to the brain is largely overlooked. More data are needed to better understand their clinical implication in order to design more appropriate screening strategies and ultimately better mitigate the risk for failure in late stage development.

  19. The crystal-fluid interfacial free energy and nucleation rate of NaCl from different simulation methods.

    PubMed

    Espinosa, Jorge R; Vega, Carlos; Valeriani, Chantal; Sanz, Eduardo

    2015-05-21

    In this work, we calculate the crystal-fluid interfacial free energy, γ(cf), for the Tosi-Fumi model of NaCl using three different simulation techniques: seeding, umbrella sampling, and mold integration. The three techniques give an orientationaly averaged γ(cf) of about 100 mJ/m(2). Moreover, we observe that the shape of crystalline clusters embedded in the supercooled fluid is spherical. Using the mold integration technique, we compute γ(cf) for four different crystal orientations. The obtained interfacial free energies range from 100 to 114 mJ/m(2), being (100) and (111) the crystal planes with the lowest and highest γ(cf), respectively. Within the accuracy of our calculations, the interfacial free energy either does not depend on temperature or changes very smoothly with it. Combining the seeding technique with classical nucleation theory, we also estimate nucleation free energy barriers and nucleation rates for a wide temperature range (800-1040 K). The obtained results compare quite well with brute force calculations and with previous results obtained with umbrella sampling [Valeriani et al., J. Chem. Phys, 122, 194501 (2005)].

  20. Mirror nuclei 3H and 3He binding energies difference and low energy parameters of neutron-neutron scattering

    NASA Astrophysics Data System (ADS)

    Babenko, V. A.; Petrov, N. M.

    2015-07-01

    A relationship between the binding energy difference for the mirror nuclei 3H and 3He and the low energy parameters of neutron-neutron and proton-proton scattering is established. The experimental values for the difference of 3H and 3He binding energies and the low-energy proton-proton scattering parameters are used to obtain the values for the neutron-neutron scattering length a nn = -18.38(55) fm and the effective range r nn = 2.84(4) fm. The calculated neutron-neutron scattering length is in good agreement with one of the two well-known and differing experimental values of this quantity.

  1. The Oklahoma Field Test: Air-conditioning electricity savings from standard energy conservation measures, radiant barriers, and high-efficiency window air conditioners

    SciTech Connect

    Ternes, M.P.; Levins, W.P.

    1992-08-01

    A field test Involving 104 houses was performed in Tulsa, Oklahoma, to measure the air-conditioning electricity consumption of low-income houses equipped with window air conditioners, the reduction in this electricity consumption attributed to the installation of energy conservation measures (ECMS) as typically installed under the Oklahoma Weatherization Assistance Program (WAP), and the reduction achieved by the replacement of low-efficiency window air conditioners with high-efficiency units and the installation of attic radiant barriers. Air-conditioning electricity consumption and indoor temperature were monitored weekly during the pre-weatherization period (June to September 1988) and post-weatherization period (May to September 1989). House energy consumption models and regression analyses were used to normalize the air-conditioning electricity savings to average outdoor temperature conditions and the pre-weatherization indoor temperature of each house. The following conclusions were drawn from the study: (1) programs directed at reducing air-conditioning electricity consumption should be targeted at clients with high consumption to improve cost effectiveness; (2) replacing low-efficiency air conditioners with high-efficiency units should be considered an option in a weatherization program directed at reducing air-conditioning electricity consumption; (3) ECMs currently being installed under the Oklahoma WAP (chosen based on effectiveness at reducing space-heating energy consumption) should continue to be justified based on their space-heating energy savings potential only; and (4) attic radiant barriers should not be included in the Oklahoma WAP if alternatives with verified savings are available or until further testing demonstrates energy savings or other benefits in this typo of housing.

  2. Bonneville Power Administration and the Industrial Technologies Program Leverage Support to Overcome Energy Efficiency Barriers in the Northwest

    SciTech Connect

    2010-06-18

    Through its Energy Smart Industrial program, BPA is informing and assisting utilities and industries to have a better understanding of the benefits that come from participating in energy-savings programs. Read about how BPA is encouraging energy efficiency projects through its utilities.

  3. Competition of different methods for recovering energy from waste.

    PubMed

    Friege, Henning; Fendel, Ansgar

    2011-10-01

    Waste-to-energy (WtE) facilities have been established worldwide as a sustainable method for the disposal of residual waste. In the present study the following competing WtE systems were compared: (1) municipal solid waste incinerators (MSWIs) with energy recovery; (2) co-incineration of waste in old lignite or coal-fired power plants; (3) substitute [refuse-derived fuel (RDF)] incinerators with energy recovery; and (4) co-incineration of defined waste fractions in cement kilns. In general the municipal solid waste incinerators in Europe are designed for a broad range of municipal and commercial waste without a pre-treatment of the waste. All other WtE processes including the cement kilns require a pre-treatment and are more limited in terms of RDF composition; namely particle size, chlorine content, calorific value. As to Germany, the emission limit values for all facilities are similar. A sensitivity analysis of the economics of boilers using RDF and municipal solid waste leads to the conclusion that the feasibility of RDF incinerators might partially recover if the prices for primary energy increase again. On the other hand, pre-treatment of waste leads to higher costs for RDF. Incineration and recycling capacities are large enough in middle Europe to avoid landfilling of organic waste. The steep decline of gate fees observed in some national spot markets is a clear indicator of an already existing overcapacity. Considering the enormous amount of greenhouse gas emissions saved by WtE facilities in comparison with landfilling, free capacities of WtE installations should be used to incinerate waste from EU member states where waste disposal is still predominantly based on landfilling.

  4. ZEB2-transgene expression in the epidermis compromises the integrity of the epidermal barrier through the repression of different tight junction proteins.

    PubMed

    Tatari, Marianthi N; De Craene, Bram; Soen, Bieke; Taminau, Joachim; Vermassen, Petra; Goossens, Steven; Haigh, Katharina; Cazzola, Silvia; Lambert, Jo; Huylebroeck, Danny; Haigh, Jody J; Berx, Geert

    2014-09-01

    Epithelial homeostasis within the epidermis is maintained by means of multiple cell-cell adhesion complexes such as adherens junctions, tight junctions, gap junctions, and desmosomes. These complexes co-operate in the formation and the regulation of the epidermal barrier. Disruption of the epidermal barrier through the deregulation of the above complexes is the cause behind a number of skin disorders such as psoriasis, dermatitis, keratosis, and others. During epithelial-to-mesenchymal transition (EMT), epithelial cells lose their adhesive capacities and gain mesenchymal properties. ZEB transcription factors are key inducers of EMT. In order to gain a better understanding of the functional role of ZEB2 in epidermal homeostasis, we generated a mouse model with conditional overexpression of Zeb2 in the epidermis. Our analysis revealed that Zeb2 expression in the epidermis leads to hyperproliferation due to the combined downregulation of different tight junction proteins compromising the epidermal barrier. Using two epidermis-specific in vivo models and in vitro promoter assays, we identified occludin as a new Zeb2 target gene. Immunohistological analysis performed on human skin biopsies covering various pathogeneses revealed ZEB2 expression in the epidermis of pemphigus vulgaris. Collectively, our data support the notion for a potential role of ZEB2 in intracellular signaling of this disease.

  5. Vehicle barrier

    DOEpatents

    Hirsh, Robert A.

    1991-01-01

    A vehicle security barrier which can be conveniently placed across a gate opening as well as readily removed from the gate opening to allow for easy passage. The security barrier includes a barrier gate in the form of a cable/gate member in combination with laterally attached pipe sections fixed by way of the cable to the gate member and lateral, security fixed vertical pipe posts. The security barrier of the present invention provides for the use of cable restraints across gate openings to provide necessary security while at the same time allowing for quick opening and closing of the gate areas without compromising security.

  6. C sbnd N rotational barrier, MP4 and CCSD(T) energies of formohydrazide and formohydroxamic acid and vibrational spectral analysis of the hydrazide

    NASA Astrophysics Data System (ADS)

    Badawi, Hassan M.

    2009-02-01

    The C sbnd N internal rotations in formohydrazide OHC sbnd NH sbnd NH 2 and formohydroxamic acid OHC sbnd NH sbnd OH were investigated at the B3LYP/6-311+G** and MP2/6-311+G** levels of theory. The C sbnd N rotational barrier in the molecules was calculated to be about 28-30 kcal/mol. The energies of the molecules were calculated at the B3LYP, MP2, MP4(SDTQ) and CCSD(T) levels of theory with both 6-311G** and 6-311+G** basis sets. From the calculations at all the levels formohydroxamic acid was predicted to exist predominantly in a non-planar near- cis conformation at ambient temperature. From all the calculations formohydrazide was predicted to have a planar cis-syn (C dbnd O and N sbnd N bonds eclipse each other and NH 2 moiety is syn to C sbnd N bond) conformation as the lowest energy structure. The NH 2 inversion barrier in formohydrazide was predicted to be about 5-7 kcal/mol. The vibrational frequencies of the cis-syn formohydrazide were computed at the B3LYP/6-311+G** level and normal coordinate calculations were carried out. Complete vibrational assignments were made on the basis of normal coordinate analyses and experimental infrared and Raman data of the molecule.

  7. Development of Simultaneous Corrosion Barrier and Optimized Microstructure in FeCrAl Heat-Resistant Alloy for Energy Applications. Part 1: The Protective Scale

    NASA Astrophysics Data System (ADS)

    Pimentel, G.; Aranda, M. M.; Chao, J.; González-Carrasco, J. L.; Capdevila, C.

    2015-09-01

    Coarse-grained Fe-based oxide dispersion-strengthened (ODS) steels are a class of advanced materials for combined cycle gas turbine systems to deal with operating temperatures and pressures of around 1100°C and 15-30 bar in aggressive environments, which would increase biomass energy conversion efficiencies up to 45% and above. This two-part paper reports the possibility of the development of simultaneous corrosion barrier and optimized microstructure in a FeCrAl heat-resistant alloy for energy applications. The first part reports the mechanism of generating a dense, self-healing α-alumina layer by thermal oxidation, during a heat treatment that leads to a coarse-grained microstructure with a potential value for high-temperature creep resistance in a FeCrAl ODS ferritic alloy, which will be described in more detail in the second part.

  8. On colloid retention in saturated porous media in the presence of energy barriers: The failure of α, and opportunities to predict η

    NASA Astrophysics Data System (ADS)

    Johnson, William P.; Tong, Meiping; Li, Xiqing

    2007-12-01

    This contribution reviews recent findings that illuminate the processes governing colloid retention in porous media under environmentally relevant conditions. In the environment, colloids act as conveyors of contaminants, or even as contaminants themselves; however, despite decades of research, we are unable to accurately predict the retention of colloids in granular aquifer media under environmental conditions, where repulsion exists between colloids and surfaces. This failure cannot be blamed solely on the complexities of the subsurface, since colloid filtration theory (CFT) works well in the absence of colloid-collector repulsion despite its idealization of porous media as consisting of spherical grains completely surrounded by fluid envelopes. Rather, the failure of CFT stems from failure to incorporate the correct mechanisms of retention when repulsion exists. Recent observations implicate wedging in grain-to-grain contacts and retention in secondary energy minima as dominant mechanisms of colloid retention in the presence of an energy barrier. Mechanistic simulations in unit cells containing grain-to-grain contacts corroborate these mechanisms of colloid retention. The resulting concept for colloid retention in the presence of an energy barrier involves translation of colloids across the collector surfaces until they become wedged within grain-to-grain contacts, or are retained via secondary energy minima (without attachment) in zones where the balance of fluid drag, diffusion, gravitational, and colloid-collector interaction forces allow retention. The above findings highlight the pore domain geometry as a dominant governor of colloid retention in so far as the geometry gives rise to grain-to-grain contacts and zones of relatively low fluid drag.

  9. Electron flux models for different energies at geostationary orbit

    NASA Astrophysics Data System (ADS)

    Boynton, R. J.; Balikhin, M. A.; Sibeck, D. G.; Walker, S. N.; Billings, S. A.; Ganushkina, N.

    2016-10-01

    Forecast models were derived for energetic electrons at all energy ranges sampled by the third-generation Geostationary Operational Environmental Satellites (GOES). These models were based on Multi-Input Single-Output Nonlinear Autoregressive Moving Average with Exogenous inputs methodologies. The model inputs include the solar wind velocity, density and pressure, the fraction of time that the interplanetary magnetic field (IMF) was southward, the IMF contribution of a solar wind-magnetosphere coupling function proposed by Boynton et al. (2011b), and the Dst index. As such, this study has deduced five new 1 h resolution models for the low-energy electrons measured by GOES (30-50 keV, 50-100 keV, 100-200 keV, 200-350 keV, and 350-600 keV) and extended the existing >800 keV and >2 MeV Geostationary Earth Orbit electron fluxes models to forecast at a 1 h resolution. All of these models were shown to provide accurate forecasts, with prediction efficiencies ranging between 66.9% and 82.3%.

  10. Deep inelastic scattering near the Coulomb barrier

    SciTech Connect

    Gehring, J.; Back, B.; Chan, K.

    1995-08-01

    Deep inelastic scattering was recently observed in heavy ion reactions at incident energies near and below the Coulomb barrier. Traditional models of this process are based on frictional forces and are designed to predict the features of deep inelastic processes at energies above the barrier. They cannot be applied at energies below the barrier where the nuclear overlap is small and friction is negligible. The presence of deep inelastic scattering at these energies requires a different explanation. The first observation of deep inelastic scattering near the barrier was in the systems {sup 124,112}Sn + {sup 58,64}Ni by Wolfs et al. We previously extended these measurements to the system {sup 136}Xe + {sup 64}Ni and currently measured the system {sup 124}Xe + {sup 58}Ni. We obtained better statistics, better mass and energy resolution, and more complete angular coverage in the Xe + Ni measurements. The cross sections and angular distributions are similar in all of the Sn + Ni and Xe + Ni systems. The data are currently being analyzed and compared with new theoretical calculations. They will be part of the thesis of J. Gehring.

  11. Concentrated vs. distributed energy: employment based community level differences

    SciTech Connect

    Hoover, L. J.; Santini, D. J.; Smeltzer, K. K.; Stenehjem, E. J.

    1980-01-01

    Consideration is given to the differences between concentrated options (central station electric, synfuels) and distributed options (SHACOB) for residential space conditioning. Employment, geographic location, community stability, and locational equity are the factors discussed.

  12. Age-related differences in mucosal barrier function and morphology of the small intestine in low and normal birth weight piglets.

    PubMed

    Huygelen, V; De Vos, M; Willemen, S; Fransen, E; Casteleyn, C; Van Cruchten, S; Van Ginneken, C

    2014-08-01

    To test the hypothesis that the mucosal maturation of the small intestine is altered in low birth weight piglets, pairs of naturally suckled low birth weight (LBW, n = 20) and normal birth weight (NBW, n = 20) littermate piglets were selected and sampled after 0, 3, 10, and 28 d of suckling. In vivo intestinal permeability was evaluated via a lactulose-mannitol absorption test. Other indirect measurements for mucosal barrier functioning included sampling for histology and immunohistochemistry (intestinal trefoil factor [ITF]), measuring intestinal alkaline phosphatase (IAP) activity, and immunoblotting for occludin, caspase-3, and proliferating cell nuclear antigen (PCNA). The lactulose-mannitol ratio did not differ between NBW and LBW piglets, but a significant increase in this ratio was observed in 28-d-old piglets (P = 0.001). Small intestinal villus height did not differ with age (P = 0.02) or birth weight (P = 0.20). In contrast, villus width (P = 0.02) and crypt depth (P < 0.05) increased gradually with age, but no birth-weight-related differences were observed. LBW piglets had significantly (P = 0.03) more ITF immunoreactive positive cells per villus area compared to NBW piglets, whereas no age (P = 0.82) or region-related (P = 0.13) differences could be observed. The activity of IAP in the small intestine was higher in newborn piglets compared to the older piglets. No significant differences in cell proliferation in the small intestine was observed (P = 0.47) between NBW and LBW piglets; the highest proliferation was seen in piglets of 28 d of age (P = 0.01). Newborn piglets had significantly fewer apoptotic cells, whereas more apoptotic cells were seen in piglets of 10 d of age (P < 0.01). In conclusion, birth weight did not affect the parameters related to intestinal barrier function investigated in this study, suggesting that the mucosal barrier function is not altered in LBW piglets. Nevertheless, these results confirm that the mucosal barrier function

  13. Contributions of parent molecule fixed and excess energies to product energy partitioning in four-center elimination reactions

    NASA Astrophysics Data System (ADS)

    Benito, R. M.; Santamaría, J.

    1989-03-01

    In four-center elimination reactions such as hydrogen halide elimination from halogenated hydrocarbons the energy barrier is higher than the difference in enthalpy of formation between the parent molecule and its fragments (HX and olefin). This determines that the energy available to products has two origins: the reverse reaction barrier (fixed energy), and the excess energy (energy above the barrier). Both types of energy are partitioned among products following different laws: more or less statistical for excess energy and non-statistical for fixed energy. In a study of CF 3-CH 3 decomposition, we describe a practical method, based on the variation of product energy partitioning with excess energy, to determine the partitioning of the fixed energy among different types of product energy, thus defining the exact nature of the reverse reaction energy barrier. We applied this model to other types of reactions, such as three-center molecular eliminations.

  14. Routes to increase the conversion and the energy efficiency in the splitting of CO2 by a dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Ozkan, A.; Bogaerts, A.; Reniers, F.

    2017-03-01

    Here, we present routes to increase CO2 conversion into CO using an atmospheric pressure dielectric-barrier discharge. The change in conversion as a function of simple plasma parameters, such as power, flow rate, but also frequency, on-and-off power pulse, thickness and the chemical nature of the dielectric, wall and gas temperature, are described. By means of an in-depth electrical characterization of the discharge (effective plasma voltage, dielectric voltage, plasma current, number and lifetime of the microdischarges), combined with infrared analysis of the walls of the reactor, optical emission spectroscopy for the gas temperature, and mass spectrometry for the CO2 conversion, we propose a global interpretation of the effect of all the experimental parameters on the conversion and efficiency of the reaction.

  15. Alchemical Free Energy Differences in Flexible Molecules from Thermodynamic Integration or Free Energy Perturbation Combined with Driven Adiabatic Dynamics.

    PubMed

    Cuendet, Michel A; Tuckerman, Mark E

    2012-10-09

    Alchemical free energy simulations are commonly used to calculate relative binding or solvation free energies in molecular systems. The convergence of alchemical free energy calculations is often hampered by inefficient sampling of the conformational degrees of freedom, which remain trapped in metastable substates. Here, we show that thermodynamic integration (TI) or free energy perturbation (FEP) can be combined with the recent driven adiabatic free energy dynamics (dAFED) method, in order to enhance conformational sampling along a set of chosen collective variables. The resulting TI-dAFED or FEP-dAFED methods are validated on a two-dimensional analytical problem. The ability of these methods to provide accurate free energy differences for realistic molecular systems is demonstrated by calculating the enantiomerization free energy of the alanine dipeptide in explicit solvent.

  16. Integrated geological-engineering model of Patrick Draw field and examples of similarities and differences among various shoreline barrier systems

    SciTech Connect

    Schatzinger, R.A.; Szpakiewicz, M.J.; Jackson, S.R.; Chang, M.M.; Sharma, B.; Tham, M.K.; Cheng, A.M.

    1992-04-01

    The Reservoir Assessment and Characterization Research Program at NIPER employs an interdisciplinary approach that focuses on the high priority reservoir class of shoreline barrier deposits to: (1) determine the problems specific to this class of reservoirs by identifying the reservoir heterogeneities that influence the movement and trapping of fluids; and (2) develop methods to characterize effectively this class of reservoirs to predict residual oil saturation (ROS) on interwell scales and improve prediction of the flow patterns of injected and produced fluids. Accurate descriptions of the spatial distribution of critical reservoir parameters (e.g., permeability, porosity, pore geometry, mineralogy, and oil saturation) are essential for designing and implementing processes to improve sweep efficiency and thereby increase oil recovery. The methodologies and models developed in this program will, in the near- to mid-term, assist producers in the implementation of effective reservoir management strategies such as location of infill wells and selection of optimum enhanced oil recovery methods to maximize oil production from their reservoirs.

  17. Measurement of reactive species generated by dielectric barrier discharge in direct contact with water in different atmospheres

    NASA Astrophysics Data System (ADS)

    Kovačević, Vesna V.; Dojčinović, Biljana P.; Jović, Milica; Roglić, Goran M.; Obradović, Bratislav M.; Kuraica, Milorad M.

    2017-04-01

    The formation of hydroxyl radical and long-living chemical species (H2O2, O3, \\text{NO}3- and \\text{NO}2- ) generated in the liquid phase of a water falling film dielectric barrier discharge in dependence on the gas atmosphere (air, nitrogen, oxygen, argon and helium) was studied. The chemical molecular probe dimethyl sulfoxide was employed for quantification of ˙OH, and the influence of hydroxyl radical scavenging on formation of reactive oxygen and nitrogen species was investigated. In addition to liquid analysis, plasma diagnostics was applied to indicate possible reaction pathways of plasma–liquid interaction. The highest ˙OH production rate of 1.19  ×  10‑5 mol l‑1 s‑1 was found when water was treated in oxygen, with a yield of 2.75  ×  10‑2 molecules of ˙OH per 100 eV. Formation of hydrogen peroxide in air, nitrogen and argon discharges is determined by recombination reaction of hydroxyl radicals, reaching the highest yield of about 0.7 g kWh‑1 when distilled water was treated in argon discharge. Ozone formation was dominant in oxygen and air discharges. Strong acidification along with formation of reactive nitrogen species was detected in water treated in air and nitrogen discharges.

  18. Barriers and Motivators to Voluntary Medical Male Circumcision Uptake among Different Age Groups of Men in Zimbabwe: Results from a Mixed Methods Study

    PubMed Central

    Hatzold, Karin; Mavhu, Webster; Jasi, Phineas; Chatora, Kumbirai; Cowan, Frances M.; Taruberekera, Noah; Mugurungi, Owen; Ahanda, Kim; Njeuhmeli, Emmanuel

    2014-01-01

    Background We conducted quantitative and qualitative studies to explore barriers and motivating factors to VMMC for HIV prevention, and to assess utilization of existing VMMC communication channels. Methods and Findings A population-based survey was conducted with 2350 respondents aged 15–49. Analysis consisted of descriptive statistics and bivariate analysis between circumcision and selected demographics. Logistic regression was used to determine predictors of male circumcision uptake compared to intention to circumcise. Focus group discussions (FGDs) were held with men purposively selected to represent a range of ethnicities. 68% and 53% of female/male respondents, respectively, had heard about VMMC for HIV prevention, mostly through the radio (71%). Among male respondents, 11.3% reported being circumcised and 49% reported willingness to undergo VMMC. Factors which men reported motivated them to undergo VMMC included HIV/STI prevention (44%), improved hygiene (26%), enhanced sexual performance (6%) and cervical cancer prevention for partner (6%). Factors that deterred men from undergoing VMMC included fear of pain (40%), not believing that they were at risk of HIV (18%), lack of partner support (6%). Additionally, there were differences in motivators and barriers by age. FGDs suggested additional barriers including fear of HIV testing, partner refusal, reluctance to abstain from sex and myths and misconceptions. Conclusions VMMC demand-creation messages need to be specifically tailored for different ages and should emphasize non-HIV prevention benefits, such as improved hygiene and sexual appeal, and need to address men's fear of pain. Promoting VMMC among women is crucial as they appear to have considerable influence over men's decision to get circumcised. PMID:24802746

  19. Is it possible to obtain cosmic accelerated expansion through energy transfer between different energy densities?

    NASA Astrophysics Data System (ADS)

    Erdem, Recai

    2017-03-01

    The equation of state of an energy density may be significantly modified by coupling it to another energy density. In the light of this observation we check the possibility of producing cosmic accelerated expansion in this way. In particular we consider the case where matter is converted to radiation (or vice versa by particle physics processes). We find that cosmic accelerated expansion can be obtained in this way only if an intermediate state with negative equation of state forms during the conversion.

  20. Assessing Different Causes of Crown-of-Thorns Starfish Outbreaks and Appropriate Responses for Management on the Great Barrier Reef

    PubMed Central

    Babcock, Russell C.; Dambacher, Jeffrey M.; Morello, Elisabetta B.; Plagányi, Éva E.; Hayes, Keith R.; Sweatman, Hugh P. A.; Pratchett, Morgan S.

    2016-01-01

    The crown-of-thorns starfish Acanthaster planci (COTS) has contributed greatly to declines in coral cover on Australia’s Great Barrier Reef, and remains one of the major acute disturbances on Indo-Pacific coral reefs. Despite uncertainty about the underlying causes of outbreaks and the management responses that might address them, few studies have critically and directly compared competing hypotheses. This study uses qualitative modelling to compare hypotheses relating to outbreak initiation, explicitly considering the potential role of positive feedbacks, elevated nutrients, and removal of starfish predators by fishing. When nutrients and fishing are considered in isolation, the models indicate that a range of alternative hypotheses are capable of explaining outbreak initiation with similar levels of certainty. The models also suggest that outbreaks may be caused by multiple factors operating simultaneously, rather than by single proximal causes. As the complexity and realism of the models increased, the certainty of outcomes decreased, but key areas that require further research to improve the structure of the models were identified. Nutrient additions were likely to result in outbreaks only when COTS larvae alone benefitted from nutrients. Similarly, the effects of fishing on the decline of corals depended on the complexity of interactions among several categories of fishes. Our work suggests that management approaches which seek to be robust to model structure uncertainty should allow for multiple potential causes of outbreaks. Monitoring programs can provide tests of alternative potential causes of outbreaks if they specifically monitor all key taxa at reefs that are exposed to appropriate combinations of potential causal factors. PMID:28036360

  1. The impact of lactoferrin with different levels of metal saturation on the intestinal epithelial barrier function and mucosal inflammation.

    PubMed

    Majka, Grzegorz; Więcek, Grażyna; Śróttek, Małgorzata; Śpiewak, Klaudyna; Brindell, Małgorzata; Koziel, Joanna; Marcinkiewicz, Janusz; Strus, Magdalena

    2016-12-01

    Translocation of bacteria, primarily Gram-negative pathogenic flora, from the intestinal lumen into the circulatory system leads to sepsis. In newborns, and especially very low birth weight infants, sepsis is a major cause of morbidity and mortality. The results of recently conducted clinical trials suggest that lactoferrin, an iron-binding protein that is abundant in mammalian colostrum and milk, may be an effective agent in preventing sepsis in newborns. However, despite numerous basic studies on lactoferrin, very little is known about how metal saturation of this protein affects a host's health. Therefore, the main objective of this study was to elucidate how iron-depleted, iron-saturated, and manganese-saturated forms of lactoferrin regulate intestinal barrier function via interactions with epithelial cells and macrophages. For these studies, a human intestinal epithelial cell line, Caco-2, was used. In this model, none of the tested lactoferrin forms induced higher levels of apoptosis or necrosis. There was also no change in the production of tight junction proteins regardless of lactoferrin metal saturation status. None of the tested forms induced a pro-inflammatory response in Caco-2 cells or in macrophages either. However, the various lactoferrin forms did effectively inhibit the pro-inflammatory response in macrophages that were activated with lipopolysaccharide with the most potent effect observed for apolactoferrin. Lactoferrin that was not bound to its cognate receptor was able to bind and neutralize lipopolysaccharide. Lactoferrin was also able to neutralize microbial-derived antigens, thereby potentially reducing their pro-inflammatory effect. Therefore, we hypothesize that lactoferrin supplementation is a relevant strategy for preventing sepsis.

  2. Assessing Different Causes of Crown-of-Thorns Starfish Outbreaks and Appropriate Responses for Management on the Great Barrier Reef.

    PubMed

    Babcock, Russell C; Dambacher, Jeffrey M; Morello, Elisabetta B; Plagányi, Éva E; Hayes, Keith R; Sweatman, Hugh P A; Pratchett, Morgan S

    2016-01-01

    The crown-of-thorns starfish Acanthaster planci (COTS) has contributed greatly to declines in coral cover on Australia's Great Barrier Reef, and remains one of the major acute disturbances on Indo-Pacific coral reefs. Despite uncertainty about the underlying causes of outbreaks and the management responses that might address them, few studies have critically and directly compared competing hypotheses. This study uses qualitative modelling to compare hypotheses relating to outbreak initiation, explicitly considering the potential role of positive feedbacks, elevated nutrients, and removal of starfish predators by fishing. When nutrients and fishing are considered in isolation, the models indicate that a range of alternative hypotheses are capable of explaining outbreak initiation with similar levels of certainty. The models also suggest that outbreaks may be caused by multiple factors operating simultaneously, rather than by single proximal causes. As the complexity and realism of the models increased, the certainty of outcomes decreased, but key areas that require further research to improve the structure of the models were identified. Nutrient additions were likely to result in outbreaks only when COTS larvae alone benefitted from nutrients. Similarly, the effects of fishing on the decline of corals depended on the complexity of interactions among several categories of fishes. Our work suggests that management approaches which seek to be robust to model structure uncertainty should allow for multiple potential causes of outbreaks. Monitoring programs can provide tests of alternative potential causes of outbreaks if they specifically monitor all key taxa at reefs that are exposed to appropriate combinations of potential causal factors.

  3. Binary association complexes of LiH, BeH/sub 2/, and BH/sub 3/. Relative isomer stabilities and barrier heights for their interconversion: energy barriers in the dimerization reactions

    SciTech Connect

    DeFrees, D.J.; Raghavachari, K.; Schlegel, H.B.; Pople, J.A.; Schleyer, P.v.R.

    1987-03-26

    Ab initio molecular orbital theory has been used to study the six compounds Li/sub 2/H/sub 2/, LiBeH/sub 3/, LiBH/sub 4/, Be/sub 2/H/sub 4/, BeBH/sub 5/, and B/sub 2/H/sub 6/. Geometry optimizations and vibrational analysis at the HF/6-31G* level indicate Li--(H)/sub 2/--Li (D/sub 2h/), Li--(H)/sub 2/--BeH (C/sub 2v/), Li--(H)/sub 3/--BH (C/sub 3v/), HBe--(H)/sub 2/--BeH (D/sub 2h/), HBe--(H)/sub 3/--BH (C/sub 3v/), and H/sub 2/B--(H)/sub 2/--BH/sub 2/ (D/sub 2h/) to the most stable forms. Inclusion of electron correlation corrections at the MP4/6-31G** level does not alter these conclusions. Other isomers were also examined in detail, and it was found that the potential energy surfaces for the species are generally flat. Activation energies for isomer interconversion and hydrogen scrambling reactions are generally less than 10 kcal mol/sup -1/. Examination of the HF/3-21 G potential surfaces indicates that there is no activation energy for the dimerization of LiH or BeH/sub 2/. The same is true for the dimerization of BH/sub 3/ at the correlated MP26-31G* level, although a small barrier is found on the HF/6-31G* surface. Enthalpies of complexation at 298 K from separate LiH, BeH/sub 2/, and BH/sub 3/ fragments, ..delta..H/sup 0//sub 298/, computed by using the HF/6-31G* harmonic frequencies and the MP4/6-31G** electronic energies are as follows: Li/sub 2/H/sub 2/, -45.9; LiBeH/sub 3/, -43.6; LiBH/sub 4/, -60.1; Be/sub 2/H/sub 4/, -30.5; BeBH/sub 5/, -45.7; B/sub 2/H/sub 6/, -36.0 kcal mol/sup -1/.

  4. Apoplastic Diffusion Barriers in Arabidopsis

    PubMed Central

    Schreiber, Lukas; Franke, Rochus Benni; Geldner, Niko; Reina-Pinto, José J.; Kunst, Ljerka

    2013-01-01

    During the development of Arabidopsis and other land plants, diffusion barriers are formed in the apoplast of specialized tissues within a variety of plant organs. While the cuticle of the epidermis is the primary diffusion barrier in the shoot, the Casparian strips and suberin lamellae of the endodermis and the periderm represent the diffusion barriers in the root. Different classes of molecules contribute to the formation of extracellular diffusion barriers in an organ- and tissue-specific manner. Cutin and wax are the major components of the cuticle, lignin forms the early Casparian strip, and suberin is deposited in the stage II endodermis and the periderm. The current status of our understanding of the relationships between the chemical structure, ultrastructure and physiological functions of plant diffusion barriers is discussed. Specific aspects of the synthesis of diffusion barrier components and protocols that can be used for the assessment of barrier function and important barrier properties are also presented. PMID:24465172

  5. Fission barriers in a macroscopic-microscopic model

    SciTech Connect

    Dobrowolski, A.; Pomorski, K.; Bartel, J.

    2007-02-15

    In the framework of the macroscopic-microscopic model, this study investigates fission barriers in the region of actinide nuclei. A very effective four-dimensional shape parametrization for fissioning nuclei is proposed. Taking, in particular, the left-right mass asymmetric and nonaxial shapes into account is demonstrated to have a substantial effect on fission barrier heights. The influence of proton versus neutron deformation differences on the potential energy landscape of fissioning nuclei is also discussed.

  6. PLATYPUS: A code for reaction dynamics of weakly-bound nuclei at near-barrier energies within a classical dynamical model

    NASA Astrophysics Data System (ADS)

    Diaz-Torres, Alexis

    2011-04-01

    A self-contained Fortran-90 program based on a three-dimensional classical dynamical reaction model with stochastic breakup is presented, which is a useful tool for quantifying complete and incomplete fusion, and breakup in reactions induced by weakly-bound two-body projectiles near the Coulomb barrier. The code calculates (i) integrated complete and incomplete fusion cross sections and their angular momentum distribution, (ii) the excitation energy distribution of the primary incomplete-fusion products, (iii) the asymptotic angular distribution of the incomplete-fusion products and the surviving breakup fragments, and (iv) breakup observables, such as angle, kinetic energy and relative energy distributions. Program summaryProgram title: PLATYPUS Catalogue identifier: AEIG_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEIG_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 332 342 No. of bytes in distributed program, including test data, etc.: 344 124 Distribution format: tar.gz Programming language: Fortran-90 Computer: Any Unix/Linux workstation or PC with a Fortran-90 compiler Operating system: Linux or Unix RAM: 10 MB Classification: 16.9, 17.7, 17.8, 17.11 Nature of problem: The program calculates a wide range of observables in reactions induced by weakly-bound two-body nuclei near the Coulomb barrier. These include integrated complete and incomplete fusion cross sections and their spin distribution, as well as breakup observables (e.g. the angle, kinetic energy, and relative energy distributions of the fragments). Solution method: All the observables are calculated using a three-dimensional classical dynamical model combined with the Monte Carlo sampling of probability-density distributions. See Refs. [1,2] for further details. Restrictions: The

  7. Pursuit of Record Breaking Energy Barriers: A Study of Magnetic Axiality in Diamide Ligated Dy(III) Single-Molecule Magnets.

    PubMed

    Harriman, Katie L M; Brosmer, Jonathan L; Ungur, Liviu; Diaconescu, Paula L; Murugesu, Muralee

    2017-02-01

    Dy(III) single-ion magnets (SIMs) with strong axial donors and weak equatorial ligands are attractive model systems with which to harness the maximum magnetic anisotropy of Dy(III) ions. Utilizing a rigid ferrocene diamide ligand (NN(TBS)), a Dy(III) SIM, (NN(TBS))DyI(THF)2, 1-Dy (NN(TBS) = fc(NHSitBuMe2)2, fc = 1,1'-ferrocenediyl), composed of a near linear arrangement of donor atoms, exhibits a large energy barrier to spin reversal (770.8 K) and magnetic blocking (14 K). The effects of the transverse ligands on the magnetic and electronic structure of 1-Dy were investigated through ab initio methods, eliciting significant magnetic axiality, even in the fourth Kramers doublet, thus demonstrating the potential of rigid diamide ligands in the design of new SIMs with defined magnetic axiality.

  8. Direct and compound-nucleus reaction mechanisms in the 7Be+58Ni system at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Mazzocco, M.; Torresi, D.; Pierroutsakou, D.; Keeley, N.; Acosta, L.; Boiano, A.; Boiano, C.; Glodariu, T.; Guglielmetti, A.; La Commara, M.; Lay, J. A.; Martel, I.; Mazzocchi, C.; Molini, P.; Parascandolo, C.; Pakou, A.; Parkar, V. V.; Romoli, M.; Rusek, K.; Sánchez-Benítez, A. M.; Sandoli, M.; Sgouros, O.; Signorini, C.; Silvestri, R.; Soramel, F.; Soukeras, V.; Stiliaris, E.; Strano, E.; Stroe, L.; Zerva, K.

    2015-08-01

    The energy and angular distributions of 3He and 4He ions produced in the 7Be +58Ni reaction at a bombarding energy of 22 MeV have been measured for the first time. The yield of the heavier helium isotope was four to five times more abundant than that of its lighter counterpart, ruling out the possibility that in this energy range the 7Be reaction dynamics is dominated by the exclusive breakup process 7Be→3He +4He (Sα=1.586 MeV). Extensive kinematic and theoretical calculations suggest that the 3He ions mostly originate from the 4He-stripping process and the 4He production is mainly triggered by the fusion-evaporation channel. The role played by the breakup, 3He-stripping, 1 n -stripping, and 1 n -pickup processes is also discussed.

  9. Thermal dissipation of light energy is regulated differently and by different mechanisms in lichens and higher plants.

    PubMed

    Kopecky, J; Azarkovich, M; Pfündel, E E; Shuvalov, V A; Heber, U

    2005-03-01

    Modulated chlorophyll fluorescence was used to compare dissipation of light energy as heat in photosystem II of homoiohydric and poikilohydric photosynthetic organisms which were either hydrated or dehydrated. In hydrated chlorolichens with an alga as the photobiont, fluorescence quenching revealed a dominant mechanism of energy dissipation which was based on a protonation reaction when zeaxanthin was present. CO2 was effective as a weak protonating agent and actinic light was not necessary. In a hydrated cyanobacterial lichen, protonation by CO2 was ineffective to initiate energy dissipation. This was also true for leaves of higher plants. Thus, regulation of zeaxanthin-dependent energy dissipation by protonation was different in leaves and in chlorolichens. A mechanism of energy dissipation different from that based on zeaxanthin became apparent on dehydration of both lichens and leaves. Quenching of maximum or Fm fluorescence increased strongly during dehydration. In lichens, this was also true for so-called basal or Fo fluorescence. In contrast to zeaxanthin-dependent quenching, dehydration-induced quenching could not be inhibited by dithiothreitol. Both zeaxanthin-dependent and dehydration-induced quenching cooperated in chlorolichens to increase thermal dissipation of light energy if desiccation occurred in the light. In cyanolichens, which do not possess a zeaxanthin cycle, only desiccation-induced thermal energy dissipation was active in the dry state. Fluorescence emission spectra of chlorolichens revealed stronger desiccation-induced suppression of 685-nm fluorescence than of 720-nm fluorescence. In agreement with earlier reports of , fluorescence excitation data showed that desiccation reduced flow of excitation energy from chlorophyll b of the light harvesting complex II to emitting centres more than flow from chlorophyll a of core pigments. The data are discussed in relation to regulation and localization of thermal energy dissipation mechanisms. It is

  10. Energies and wave functions of an off-centre donor in hemispherical quantum dot: Two-dimensional finite difference approach and ritz variational principle

    NASA Astrophysics Data System (ADS)

    Nakra Mohajer, Soukaina; El Harouny, El Hassan; Ibral, Asmaa; El Khamkhami, Jamal; Assaid, El Mahdi

    2016-09-01

    Eigenvalues equation solutions of a hydrogen-like donor impurity, confined in a hemispherical quantum dot deposited on a wetting layer and capped by an insulating matrix, are determined in the framework of the effective mass approximation. Conduction band alignments at interfaces between quantum dot and surrounding materials are described by infinite height barriers. Ground and excited states energies and wave functions are determined analytically and via one-dimensional finite difference approach in case of an on-center donor. Donor impurity is then moved from center to pole of hemispherical quantum dot and eigenvalues equation is solved via Ritz variational principle, using a trial wave function where Coulomb attraction between electron and ionized donor is taken into account, and by two-dimensional finite difference approach. Numerical codes developed enable access to variations of donor total energy, binding energy, Coulomb correlation parameter, spatial extension and radial probability density with respect to hemisphere radius and impurity position inside the quantum dot.

  11. Socio-Demographic Differences in Energy Drink Consumption and Reasons for Consumption among US College Students

    ERIC Educational Resources Information Center

    Poulos, Natalie S.; Pasch, Keryn E.

    2016-01-01

    Background: Energy drink consumption has become increasingly prevalent among US college students, yet little is known about current rates of consumption and reasons for consumption among current energy drink users, particularly differences related to gender and race/ethnicity. Objectives: To better understand energy drink consumption alone and…

  12. Multilayer coatings for flexible high-barrier materials

    NASA Astrophysics Data System (ADS)

    Vaško, Karol; Noller, Klaus; Mikula, Milan; Amberg-Schwab, Sabine; Weber, Ulrike

    2009-06-01

    A multilayer, flexible, and transparent high-barrier system based on flexible plastic foils, polyethyleneterephthalate (PET) and ethylene-tetrafluoroethylene-copolymer (ETFE), combined with vacuum-deposited, inorganic SiOx layers and hybrid ORMOCER® varnish layers were prepared in different orders on a semiproduction level. Barrier properties of prepared systems, as water vapour transmission (WVTR) and oxygen transmission (OTR), were measured and studied in connection with surface energy, surface topography, and water vapour adsorption properties. Correlations among layers sequence, barrier properties, and other parameters are presented, including some basic principles of permeation of substances through multilayer barrier systems. A combination of several inorganic and hybrid varnish layers is necessary to achieve the technological demands from a barrier standpoint. It is easier to suppress the oxygen transport than the water transport, due to the additional active penetration of water through hydrogen bonds and silanol creations at oxide interfaces, capillary condensation, and swelling with high internal pressure, leading to new defects.

  13. Multilayer coatings for flexible high-barrier materials

    NASA Astrophysics Data System (ADS)

    Vaško, Karol; Noller, Klaus; Mikula, Milan; Amberg-Schwab, Sabine; Weber, Ulrike

    2009-06-01

    A multilayer, flexible, and transparent high-barrier system based on flexible plastic foils, polyethyleneterephthalate (PET) and ethylene-tetrafluoroethylene-copolymer (ETFE), combined with vacuum-deposited, inorganic SiOx layers and hybrid ORMOCER® varnish layers were prepared in different orders on a semiproduction level. Barrier properties of prepared systems, as water vapour transmission (WVTR) and oxygen transmission (OTR), were measured and studied in connection with surface energy, surface topography, and water vapour adsorption properties. Correlations among layers sequence, barrier properties, and other parameters are presented, including some basic principles of permeation of substances through multilayer barrier systems. A combination of several inorganic and hybrid varnish layers is necessary to achieve the technological demands from a barrier standpoint. It is easier to suppress the oxygen transport than the water transport, due to the additional active penetration of water through hydrogen bonds and silanol creations at oxide interfaces, capillary condensation, and swelling with high internal pressure, leading to new defects.

  14. Consistent force field modeling of matrix isolated molecules. V. Minimum energy path potential to the conformer conversion of 1,2-difluoroethane: Ar 364, ab initio calculation of electric multipole moments and electric polarization contribution to the conversion barrier

    NASA Astrophysics Data System (ADS)

    Gunde, R.; Ha, T.-K.; Günthard, H. H.

    1990-08-01

    In this paper results of consistent force field modeling (CFF) of the potential function to conversion of the gauche (g) to the trans (t) conformer of 1,2-difluoroethane (DFE) isolated in an argon matrix will be reported. Starting point are locally stable configurations gDFE:Ar 364 (defect GH1) and tDFE:Ar 364 (TH1) obtained in previous work from CFF modeling of a cube shaped Ar 364 fragment containing one DFE molecule in its center. Using the dihedral angle of DFE as an independent parameter the minimum energy path of the conversion process gDFE:Ar 364→tDFE:Ar 364 will be determined by CFF energy minimization. Determination of the minimum energy path is found to require large numbers of energy minimization steps and to lead to a rather complicated motion of the molecule with respect to the crystal fragment. Surprisingly the molecule-matrix interactions lead to a reduction of the g-t barrier by ≈500 cal/mol and to a stabilization of the trans species by ≈500 cal/mol. This finding is a consequence of a delicate interplay of matrix-molecule and matrix-matrix interactions. Calculation of the electric polarization energy (induced dipole-first-order polarization approximation) is based on extended ab initio calculations of dipole and quadrupole moments and a bond polarizability estimate of the first-order polarizability of DFE as a function of the internal rotation angle, on Fourier expansion of multipole components and use of symmetry for reduction of the order of the linear system defining the (self-consistent) induced dipole moments of all Ar atoms. Electric polarization is found to alter the potential function of the conversion process in a profound way: the g-t barrier and the t-g energy difference are increased to ≈3000 cal/mol and to ≈1500 cal/mol respectively (≈2500 and ≈530 cal/mol respectively for free DFE). Further applications of the technique developed in this work to related problems of matrix isolated molecules, e.g., vibrational matrix

  15. Field study of moisture damage in walls insulated without a vapor barrier. Final report for the Oregon Department of Energy

    SciTech Connect

    Tsongas, G.A.

    1980-05-01

    Considerable uncertainty has existed over whether or not wall insulation installed without a vapor barrier causes an increased risk of moisture damage (wood decay) within walls. This report describes the results of one of the first major studies in the country aimed at finding out if such a moisture problem really exists. The exterior walls of a total of 96 homes in Portland, Oregon were opened, of which 70 had retrofitted insulation and 26 were uninsulated and were a control group. The types of insulation included urea-formaldehyde foam (44), mineral wool (16), and cellulose (10). In each opened wall cavity the moisture content of wood was measured and insulation and wood samples were taken for laboratory analysis of moisture content and for the determination of the presence of absence of decay fungi. Foam shrinkage was also measured. To evaluate the possible influence of the relative air tightness of the homes, fan depressurization tests were run using a door blower unit. The field and laboratory test results indicating the lack of a moisture damage problem in existing homes with wood siding in climates similar to that of western Oregon are described along with results of a statistical analysis of the data. Related problems of interest to homeowners and insulation installers are noted. The standard operating procedures used throughout the study are discussed, including the home selection process, quantitative and qualitative techniques used to identify wall locations with the highest moisture content, wall opening and data/sample collection methodology, laboratory analysis of samples, data processing and analysis, and applicability of the results. Recommendations for furutre tests are made. Finally, the potential and desirability for future retrofitting of wall insulation is explored.

  16. Measurement of blood-brain barrier permeability with t1-weighted dynamic contrast-enhanced MRI in brain tumors: a comparative study with two different algorithms.

    PubMed

    Bergamino, Maurizio; Saitta, Laura; Barletta, Laura; Bonzano, Laura; Mancardi, Giovanni Luigi; Castellan, Lucio; Ravetti, Jean Louis; Roccatagliata, Luca

    2013-01-01

    The purpose of this study was to assess the feasibility of measuring different permeability parameters with T1-weighted dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in order to investigate the blood brain-barrier permeability associated with different brain tumors. The Patlak algorithm and the extended Tofts-Kety model were used to this aim. Twenty-five adult patients with tumors of different histological grades were enrolled in this study. MRI examinations were performed at 1.5 T. Multiflip angle, fast low-angle shot, and axial 3D T1-weighted images were acquired to calculate T1 maps, followed by a DCE acquisition. A region of interest was placed within the tumor of each patient to calculate the mean value of different permeability parameters. Differences in permeability measurements were found between different tumor grades, with higher histological grades characterized by higher permeability values. A significant difference in transfer constant (K (trans)) values was found between the two methods on high-grade tumors; however, both techniques revealed a significant correlation between the histological grade of tumors and their K (trans) values. Our results suggest that DCE acquisition is feasible in patients with brain tumors and that K (trans) maps can be easily obtained by these two algorithms, even if the theoretical model adopted could affect the final results.

  17. Energy Systems Based on Polyacetylene: Rechargeable Batteries and Schottky Barrier Solar Cells. Final Report, March 1, 1981-February 29, 1984

    DOE R&D Accomplishments Database

    MacDiarmid, A. G.

    1984-02-01

    The chief thrust of the research has been directed towards the evaluation of polyacetylene (CH){sub x}, the prototype conducting polymer as an electrode- active material in novel, rechargeable batteries employing nonaqueous electrolytes. The p-doped material, [(CH{sup +y})A{sub y}{sup -}]{sub x}, (where A{sup -} is an anion) in conjunction with a Li anode, shows excellent discharge characteristics, e.g., very little change in discharge voltage with change in discharge current and a high power density. Its energy density is also good but it shows poor shelf life. When (CH){sub x} is used as a cathode (Li anode), which results in the formation of the n-doped polymer, [Li{sub y} {sup +}(CH/sup -y/)]{sub x}, during discharge, good discharge plateaus and power densities are obtained together with excellent shelf life and good recyclability. The energy density is, however only moderate. Cells employing an [M{sub y}{sup +}(CH/sup -y/)]{sub x} (where M = Li, Na) anode and a TiS{sub 2} cathode show very good discharge and recycling characteristics but their energy density is poor.

  18. The Oklahoma Field Test: Air-Conditioning Electricity Savings from Standard Energy Conservation Measures, Radiant Barriers, and High-Efficiency Window Air Conditioners

    SciTech Connect

    Ternes, M.P.

    1992-01-01

    A field test involving 104 houses was performed in Tulsa, Oklahoma, to measure the air-conditioning electricity consumption of low-income houses equipped with window air conditioners, the reduction in this electricity consumption attributed to the installation of energy conservation measures (ECMs) as typically installed under the Oklahoma Weatherization Assistance Program (WAP), and the reduction achieved by the replacement of low-efficiency window air conditioners with high-efficiency units and the installation of attic radiant barriers. Air-conditioning electricity consumption and indoor temperature were monitored weekly during the pre-weatherization period (June to September 1988) and post-weatherization period (May to September 1989). House energy consumption models and regression analyses were used to normalize the air-conditioning electricity savings to average outdoor temperature conditions and the pre-weatherization indoor temperature of each house. The average measured pre-weatherization air-conditioning electricity consumption was 1664 kWh/year ($119/year). Ten percent of the houses used less than 250 kWh/year, while another 10% used more than 3000 kWh/year. An average reduction in air-conditioning electricity consumption of 535 kWh/year ($38/year and 28% of pre-weatherization consumption) was obtained from replacement of one low-efficiency window air conditioner (EER less than 7.0) per house with a high-efficiency unit (EER greater than 9.0). For approximately the same cost, savings tripled to 1503 kWh/year ($107/year and 41% of pre-weatherization consumption) in those houses with initial air-conditioning electricity consumption greater than 2750 kWh/year. For these houses, replacement of a low-efficiency air conditioner with a high-efficiency unit was cost effective using the incremental cost of installing a new unit now rather than later; the average installation cost for these houses under a weatherization program was estimated to be $786. The

  19. Accurate calculation of conformational free energy differences in explicit water: the confinement-solvation free energy approach.

    PubMed

    Esque, Jeremy; Cecchini, Marco

    2015-04-23

    The calculation of the free energy of conformation is key to understanding the function of biomolecules and has attracted significant interest in recent years. Here, we present an improvement of the confinement method that was designed for use in the context of explicit solvent MD simulations. The development involves an additional step in which the solvation free energy of the harmonically restrained conformers is accurately determined by multistage free energy perturbation simulations. As a test-case application, the newly introduced confinement/solvation free energy (CSF) approach was used to compute differences in free energy between conformers of the alanine dipeptide in explicit water. The results are in excellent agreement with reference calculations based on both converged molecular dynamics and umbrella sampling. To illustrate the general applicability of the method, conformational equilibria of met-enkephalin (5 aa) and deca-alanine (10 aa) in solution were also analyzed. In both cases, smoothly converged free-energy results were obtained in agreement with equilibrium sampling or literature calculations. These results demonstrate that the CSF method may provide conformational free-energy differences of biomolecules with small statistical errors (below 0.5 kcal/mol) and at a moderate computational cost even with a full representation of the solvent.

  20. Renewable Energy and Efficiency Modeling Analysis Partnership (REMAP): An Analysis of How Different Energy Models Addressed a Common High Renewable Energy Penetration Scenario in 2025

    SciTech Connect

    Blair, Nate; Jenkin, Thomas; Milford, James; Short, Walter; Sullivan, Patrick; Evans, David; Lieberman, Elliot; Goldstein, Gary; Wright, Evelyn; Jayaraman, Kamala R.; Venkatesh, Boddu; Kleiman, Gary; Namovicz, Christopher; Smith, Bob; Palmer, Karen; Wiser, Ryan; Wood, Frances

    2009-09-01

    Energy system modeling can be intentionally or unintentionally misused by decision-makers. This report describes how both can be minimized through careful use of models and thorough understanding of their underlying approaches and assumptions. The analysis summarized here assesses the impact that model and data choices have on forecasting energy systems by comparing seven different electric-sector models. This analysis was coordinated by the Renewable Energy and Efficiency Modeling Analysis Partnership (REMAP), a collaboration among governmental, academic, and nongovernmental participants.

  1. Are There Any Different Effects of Bifidobacterium, Lactobacillus and Streptococcus on Intestinal Sensation, Barrier Function and Intestinal Immunity in PI-IBS Mouse Model?

    PubMed Central

    Wang, Huan; Gong, Jing; Wang, Wenfeng; Long, Yanqin; Fu, Xiaochao; Fu, Yu; Qian, Wei; Hou, Xiaohua

    2014-01-01

    Background and Aims Research has increasingly suggested that gut flora plays an important role in the development of post-infectious irritable bowel syndrome (PI-IBS). Studies of the curative effect of probiotics for IBS have usually been positive but not always. However, the differences of treatment effects and mechanisms among probiotic stains, or mixture of them, are not clear. In this study, we compared the effects of different probiotics (Befidobacterium, Lactobacillus, Streptococcus or mixture of the three) on intestinal sensation, barrier function and intestinal immunity in PI-IBS mouse model. Methods PI-IBS model was induced by Trichinella spiralis infection in mice. Different probiotics were administered to mice after 8 weeks infection. Visceral sensitivity was measured by scores of abdominal withdrawal reflex (AWR) and the threshold intensity of colorectal distention. Colonic smooth muscle contractile response was assessed by contraction of the longitudinal muscle strips. Plasma diamine oxidase (DAO) and d-lactate were determined by an enzymatic spectrophotometry. Expression of tight junction proteins and cytokines in ileum were measured by Western blotting. Results Compared to control mice, PI-IBS mice treated either alone with Befidobacterium or Lactobacillus (but not Streptococcus), or the mixture of the three exhibited not only decreased AWR score and contractile response, but also reduced plasma DAO and D-lactate. These probiotic treatments also suppressed the expression of proinflammatory cytokine IL-6 and IL-17 and promoted the expression of major tight junction proteins claudin-1 and occludin. The mixture of the three probiotic strains performed better than the individual in up-regulating these tight junction proteins and suppressing IL-17 expression. Conclusions Bifidobacterium and Lactobacillus, but not Streptococcus, alleviated visceral hypersensitivity and recovered intestinal barrier function as well as inflammation in PI-IBS mouse model

  2. Surface tension, surface energy, and chemical potential due to their difference.

    PubMed

    Hui, C-Y; Jagota, A

    2013-09-10

    It is well-known that surface tension and surface energy are distinct quantities for solids. Each can be regarded as a thermodynamic property related first by Shuttleworth. Mullins and others have suggested that the difference between surface tension and surface energy cannot be sustained and that the two will approach each other over time. In this work we show that in a single-component system where changes in elastic energy can be neglected, the chemical potential difference between the surface and bulk is proportional to the difference between surface tension and surface energy. By further assuming that mass transfer is driven by this chemical potential difference, we establish a model for the kinetics by which mass transfer removes the difference between surface tension and surface energy.

  3. Assessment of Orbital-Optimized MP2.5 for Thermochemistry and Kinetics: Dramatic Failures of Standard Perturbation Theory Approaches for Aromatic Bond Dissociation Energies and Barrier Heights of Radical Reactions.

    PubMed

    Soydaş, Emine; Bozkaya, Uğur

    2015-04-14

    An assessment of orbital-optimized MP2.5 (OMP2.5) [ Bozkaya, U.; Sherrill, C. D. J. Chem. Phys. 2014, 141, 204105 ] for thermochemistry and kinetics is presented. The OMP2.5 method is applied to closed- and open-shell reaction energies, barrier heights, and aromatic bond dissociation energies. The performance of OMP2.5 is compared with that of the MP2, OMP2, MP2.5, MP3, OMP3, CCSD, and CCSD(T) methods. For most of the test sets, the OMP2.5 method performs better than MP2.5 and CCSD, and provides accurate results. For barrier heights of radical reactions and aromatic bond dissociation energies OMP2.5-MP2.5, OMP2-MP2, and OMP3-MP3 differences become obvious. Especially, for aromatic bond dissociation energies, standard perturbation theory (MP) approaches dramatically fail, providing mean absolute errors (MAEs) of 22.5 (MP2), 17.7 (MP2.5), and 12.8 (MP3) kcal mol(-1), while the MAE values of the orbital-optimized counterparts are 2.7, 2.4, and 2.4 kcal mol(-1), respectively. Hence, there are 5-8-folds reductions in errors when optimized orbitals are employed. Our results demonstrate that standard MP approaches dramatically fail when the reference wave function suffers from the spin-contamination problem. On the other hand, the OMP2.5 method can reduce spin-contamination in the unrestricted Hartree-Fock (UHF) initial guess orbitals. For overall evaluation, we conclude that the OMP2.5 method is very helpful not only for challenging open-shell systems and transition-states but also for closed-shell molecules. Hence, one may prefer OMP2.5 over MP2.5 and CCSD as an O(N(6)) method, where N is the number of basis functions, for thermochemistry and kinetics. The cost of the OMP2.5 method is comparable with that of CCSD for energy computations. However, for analytic gradient computations, the OMP2.5 method is only half as expensive as CCSD.

  4. [Vascular endothelial Barrier Function].

    PubMed

    Ivanov, A N; Puchinyan, D M; Norkin, I A

    2015-01-01

    Endothelium is an important regulator of selective permeability of the vascular wall for different molecules and cells. This review summarizes current data on endothelial barrier function. Endothelial glycocalyx structure, its function and role in the molecular transport and leukocytes migration across the endothelial barrier are discussed. The mechanisms of transcellular transport of macromolecules and cell migration through endothelial cells are reviewed. Special section of this article addresses the structure and function of tight and adherens endothelial junction, as well as their importance for the regulation of paracellular transport across the endothelial barrier. Particular attention is paid to the signaling mechanism of endothelial barrier function regulation and the factors that influence on the vascular permeability.

  5. A Ploidy Difference Represents an Impassable Barrier for Hybridisation in Animals. Is There an Exception among Botiid Loaches (Teleostei: Botiidae)?

    PubMed Central

    Bohlen, Jörg; Šlechtová, Vendula; Šlechta, Vlastimil; Šlechtová, Vera; Sember, Alexandr; Ráb, Petr

    2016-01-01

    One of the most efficient mechanisms to keep animal lineages separate is a difference in ploidy level (number of whole genome copies), since hybrid offspring from parents with different ploidy level are functionally sterile. In the freshwater fish family Botiidae, ploidy difference has been held responsible for the separation of its two subfamilies, the evolutionary tetraploid Botiinae and the diploid Leptobotiinae. Diploid and tetraploid species coexist in the upper Yangtze, the Pearl River and the Red River basins in China. Interestingly, the species ‘Botia’ zebra from the Pearl River basin combines a number of morphological characters that otherwise are found in the diploid genus Leptobotia with morphological characters of the tetraploid genus Sinibotia, therefore the aim of the present study is to test weather ‘B.’ zebra is the result of a hybridisation event between species from different subfamilies with different ploidy level. A closer morphological examination indeed demonstrates a high similarity of ‘B.’ zebra to two co-occurring species, the diploid Leptobotia guilinensis and the tetraploid Sinibotia pulchra. These two species thus could have been the potential parental species in case of a hybrid origin of ‘B.’ zebra. The morphologic analysis further reveals that ‘B.’ zebra bears even the diagnostic characters of the genera Leptobotia (Leptobotiinae) and Sinibotia (Botiinae). In contrast, a comparison of six allozyme loci between ‘B.’ zebra, L. guilinensis and S. pulchra showed only similarities between ‘B.’ zebra and S. pulchra, not between ‘B.’ zebra and L. guilinensis. Six specimens of ‘B.’ zebra that were cytogenetically analysed were tetraploid with 4n = 100. The composition of the karyotype (18% metacentric, 18% submetacentric, 36% subtelocentric and 28% acrocentric chromosomes) differs from those of L. guilinensis (12%, 24%, 20% and 44%) and S. pulchra (20%, 26%, 28% and 26%), and cannot be obtained by any

  6. Improving the efficiency of cadmium sulfide-sensitized titanium dioxide/indium tin oxide glass photoelectrodes using silver sulfide as an energy barrier layer and a light absorber

    NASA Astrophysics Data System (ADS)

    Chen, Chong; Zhai, Yong; Li, Chunxi; Li, Fumin

    2014-11-01

    Cadmium sulfide (CdS) and silver sulfide (Ag2S) nanocrystals are deposited on the titanium dioxide (TiO2) nanocrystalline film on indium tin oxide (ITO) substrate to prepare CdS/Ag2S/TiO2/ITO photoelectrodes through a new method known as the molecular precursor decomposition method. The Ag2S is interposed between the TiO2 nanocrystal film and CdS nanocrystals as an energy barrier layer and a light absorber. As a consequence, the energy conversion efficiency of the CdS/Ag2S/TiO2/ITO electrodes is significantly improved. Under AM 1.5 G sunlight irradiation, the maximum efficiency achieved for the CdS(4)/Ag2S/TiO2/ITO electrode is 3.46%, corresponding to an increase of about 150% as compared to the CdS(4)/TiO2/ITO electrode without the Ag2S layer. Our experimental results show that the improved efficiency is mainly due to the formation of Ag2S layer that may increase the light absorbance and reduce the recombination of photogenerated electrons with redox ions from the electrolyte.

  7. Non-linear, non-monotonic effect of nano-scale roughness on particle deposition in absence of an energy barrier: Experiments and modeling

    NASA Astrophysics Data System (ADS)

    Jin, Chao; Glawdel, Tomasz; Ren, Carolyn L.; Emelko, Monica B.

    2015-12-01

    Deposition of colloidal- and nano-scale particles on surfaces is critical to numerous natural and engineered environmental, health, and industrial applications ranging from drinking water treatment to semi-conductor manufacturing. Nano-scale surface roughness-induced hydrodynamic impacts on particle deposition were evaluated in the absence of an energy barrier to deposition in a parallel plate system. A non-linear, non-monotonic relationship between deposition surface roughness and particle deposition flux was observed and a critical roughness size associated with minimum deposition flux or “sag effect” was identified. This effect was more significant for nanoparticles (<1 μm) than for colloids and was numerically simulated using a Convective-Diffusion model and experimentally validated. Inclusion of flow field and hydrodynamic retardation effects explained particle deposition profiles better than when only the Derjaguin-Landau-Verwey-Overbeek (DLVO) force was considered. This work provides 1) a first comprehensive framework for describing the hydrodynamic impacts of nano-scale surface roughness on particle deposition by unifying hydrodynamic forces (using the most current approaches for describing flow field profiles and hydrodynamic retardation effects) with appropriately modified expressions for DLVO interaction energies, and gravity forces in one model and 2) a foundation for further describing the impacts of more complicated scales of deposition surface roughness on particle deposition.

  8. Non-linear, non-monotonic effect of nano-scale roughness on particle deposition in absence of an energy barrier: Experiments and modeling

    PubMed Central

    Jin, Chao; Glawdel, Tomasz; Ren, Carolyn L.; Emelko, Monica B.

    2015-01-01

    Deposition of colloidal- and nano-scale particles on surfaces is critical to numerous natural and engineered environmental, health, and industrial applications ranging from drinking water treatment to semi-conductor manufacturing. Nano-scale surface roughness-induced hydrodynamic impacts on particle deposition were evaluated in the absence of an energy barrier to deposition in a parallel plate system. A non-linear, non-monotonic relationship between deposition surface roughness and particle deposition flux was observed and a critical roughness size associated with minimum deposition flux or “sag effect” was identified. This effect was more significant for nanoparticles (<1 μm) than for colloids and was numerically simulated using a Convective-Diffusion model and experimentally validated. Inclusion of flow field and hydrodynamic retardation effects explained particle deposition profiles better than when only the Derjaguin-Landau-Verwey-Overbeek (DLVO) force was considered. This work provides 1) a first comprehensive framework for describing the hydrodynamic impacts of nano-scale surface roughness on particle deposition by unifying hydrodynamic forces (using the most current approaches for describing flow field profiles and hydrodynamic retardation effects) with appropriately modified expressions for DLVO interaction energies, and gravity forces in one model and 2) a foundation for further describing the impacts of more complicated scales of deposition surface roughness on particle deposition. PMID:26658159

  9. Improving the efficiency of cadmium sulfide-sensitized titanium dioxide/indium tin oxide glass photoelectrodes using silver sulfide as an energy barrier layer and a light absorber

    PubMed Central

    2014-01-01

    Cadmium sulfide (CdS) and silver sulfide (Ag2S) nanocrystals are deposited on the titanium dioxide (TiO2) nanocrystalline film on indium tin oxide (ITO) substrate to prepare CdS/Ag2S/TiO2/ITO photoelectrodes through a new method known as the molecular precursor decomposition method. The Ag2S is interposed between the TiO2 nanocrystal film and CdS nanocrystals as an energy barrier layer and a light absorber. As a consequence, the energy conversion efficiency of the CdS/Ag2S/TiO2/ITO electrodes is significantly improved. Under AM 1.5 G sunlight irradiation, the maximum efficiency achieved for the CdS(4)/Ag2S/TiO2/ITO electrode is 3.46%, corresponding to an increase of about 150% as compared to the CdS(4)/TiO2/ITO electrode without the Ag2S layer. Our experimental results show that the improved efficiency is mainly due to the formation of Ag2S layer that may increase the light absorbance and reduce the recombination of photogenerated electrons with redox ions from the electrolyte. PMID:25411566

  10. Improving the efficiency of cadmium sulfide-sensitized titanium dioxide/indium tin oxide glass photoelectrodes using silver sulfide as an energy barrier layer and a light absorber.

    PubMed

    Chen, Chong; Zhai, Yong; Li, Chunxi; Li, Fumin

    2014-01-01

    Cadmium sulfide (CdS) and silver sulfide (Ag2S) nanocrystals are deposited on the titanium dioxide (TiO2) nanocrystalline film on indium tin oxide (ITO) substrate to prepare CdS/Ag2S/TiO2/ITO photoelectrodes through a new method known as the molecular precursor decomposition method. The Ag2S is interposed between the TiO2 nanocrystal film and CdS nanocrystals as an energy barrier layer and a light absorber. As a consequence, the energy conversion efficiency of the CdS/Ag2S/TiO2/ITO electrodes is significantly improved. Under AM 1.5 G sunlight irradiation, the maximum efficiency achieved for the CdS(4)/Ag2S/TiO2/ITO electrode is 3.46%, corresponding to an increase of about 150% as compared to the CdS(4)/TiO2/ITO electrode without the Ag2S layer. Our experimental results show that the improved efficiency is mainly due to the formation of Ag2S layer that may increase the light absorbance and reduce the recombination of photogenerated electrons with redox ions from the electrolyte.

  11. Sealing Ability of Mineral Trioxide Aggregate and Calcium-Enriched Mixture Cement as Apical Barriers with Different Obturation Techniques

    PubMed Central

    Tabrizizade, Mahdi; Asadi, Yasin; Sooratgar, Aidin; Moradi, Saeed; Sooratgar, Hossein; Ayatollahi, Fatemeh

    2014-01-01

    Introduction: Endodontic treatment in pulpless immature teeth is challenging due to the lack of an apical stop. Insertion of an apical plug is an alternative to conventional long-term apexification with calcium hydroxide. The aim of this study was to compare the apical microleakage of mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement as apical plugs with three different obturation techniques. Methods and Materials: This experimental study was conducted on 130 single rooted human teeth with one canal. Samples were randomly divided into 2 experimental groups (n=60) and two negative and positive control groups containing 5 samples each. After cleaning and shaping, an open apex configuration was prepared in all samples. MTA or CEM cement apical plugs with 5 mm thicknesses were placed. Then, each group was divided to 4 subgroups and the remaining space of root canals were filled with either lateral compaction or thermoplasticized injectable gutta-percha or was obturated by filling the entire canal with apical plug material. In one remaining subgroup the canal space was left unfilled. Microleakage was measured by the fluid filtration method and results were analyzed by means of the two-way ANOVA test. Results: There were no significant differences between microleakage of MTA and CEM cement apical plugs (P=0.92). The difference between three obturation methods was not significant, either (P=0.39). Conclusion: MTA and CEM cement have similar sealing ability as apical plugs and no significant difference was found in microleakage of the three groups. PMID:25386206

  12. Diversities of coral-associated bacteria differ with location, but not species, for three acroporid corals on the Great Barrier Reef.

    PubMed

    Littman, Raechel A; Willis, Bette L; Pfeffer, Christian; Bourne, David G

    2009-05-01

    Patterns in the diversity of bacterial communities associated with three species of Acropora (Acropora millepora, Acropora tenuis and Acropora valida) were compared at two locations (Magnetic Island and Orpheus Island) on the Great Barrier Reef to better understand the nature and specificity of coral-microbial symbioses. Three culture-independent techniques demonstrated consistent bacterial communities among replicate samples of each coral species, confirming that corals associate with specific microbiota. Profiles were also conserved among all three species of Acropora within each location, suggesting that closely related corals of the same genus harbor similar bacterial types. Bacterial community profiles of A. millepora at Orpheus Island were consistent in samples collected throughout the year, indicating a stable community despite temporal changes. However, DGGE and T-RFLP profiles differed on corals from different reefs. Nonmetric multidimensional scaling of T-RFLP profiles showed that samples grouped according to location rather than coral species. Although similar sequences were retrieved from clone libraries of corals at both Magnetic and Orpheus Island, differences in the relative dominant bacterial ribotypes within the libraries drive bacterial community structure at different geographical locations. These results indicate certain bacterial groups associated specifically with corals, but the dominant bacterial genera differ between geographically-spaced corals.

  13. Evaluation of Different Holder Devices for Freeze-Drying in Dual-Chamber Cartridges With a Focus on Energy Transfer.

    PubMed

    Korpus, Christoph; Friess, Wolfgang

    2017-04-01

    For freeze-drying in dual-chamber cartridges, a holder device to enable handling and safe positioning in the freeze-dryer is necessary. The aim of this study was to analyze 4 different types of holder devices and to define the best system based on energy transfer. The main criteria were drying homogeneity, ability to minimize the influence of atypical radiation on product temperatures, and heat transfer effectiveness. The shell holder reduced the influence of atypical radiation by almost 60% compared to a block system and yielded the most homogenous sublimation rates. Besides the most efficient heat transfer with values of 1.58E-4 ± 2.06E-6 cal/(s*cm(2)*K) at 60 mTorr to 3.63E-4 ± 1.85E-5 cal/(s*cm(2)*K) at 200 mTorr for Ktot, reaction times to shelf temperature changes were up to 4 times shorter compared to the other holder systems and even faster than for vials. The flexible holder provided a comparable shielding against atypical radiation as the shell but introduced a third barrier against energy transfer. Block and guardrail holder were the least efficient system tested. Hence, the shell holder provided the best radiation shielding, enhanced the transferability of the results to a larger scale, and improved the homogeneity between the dual-chamber cartridges.

  14. Investigation of complete and incomplete fusion dynamics of {sup 20}Ne induced reactions at energies above the Coulomb barrier

    SciTech Connect

    Singh, D.; Ali, R.; Kumar, Harish; Ansari, M. Afzal; Rashid, M. H.; Guin, R.

    2014-08-14

    Experiment has been performed to explore the complete and incomplete fusion dynamics in heavy ion collisions using stacked foil activation technique. The measurement of excitation functions of the evaporation residues produced in the {sup 20}Ne+{sup 165}Ho system at projectile energies ranges ≈ 4-8 MeV/nucleon have been done. Measured cumulative and direct cross-sections have been compared with the theoretical model code PACE-2, which takes into account only the complete fusion process. The analysis indicates the presence of contributions from incomplete fusion processes in some α-emission channels following the break-up of the projectile {sup 20}Ne in the nuclear field of the target nucleus {sup 165}Ho.

  15. Recommend, but also Discuss: Different Patterns of Physician-Perceived Barriers to Discussing HPV Vaccination and Their Association with Vaccine Administration in 11-12 Year-Old Girls.

    PubMed

    Kulczycki, Andrzej; Qu, Haiyan; Shewchuk, Richard

    2016-12-01

    Objectives We examined variation in primary care physicians' (PCPs') perceptions of barriers to physician-initiated discussion of HPV vaccination, and how this is associated with the rates at which they discuss, initiate and continue to administer vaccination with 11-12 year-old girls. Methods We surveyed 301 PCPs using systematic random sampling. PCP variation in perceived barriers to discussing HPV vaccination was modeled using latent class analysis (LCA). The distinct PCP groups identified were compared with each other using three iterative logistic regression models to predict the likelihood of initiating vaccine discussion and the reported percentages of 11-12 year-old patients who initiated HPV vaccination and received follow-up shots. Results LCA revealed three groups of PCPs who perceived major, moderately significant and relatively minor barriers (17.9, 41.9 and 40.2 % of respondents, respectively). Pediatricians, PCPs who were female, had minority racial/ethnic status and who perceived only minor barriers had significantly higher odds of initiating discussion. PCPs were more likely to initiate HPV vaccination if they had initiated discussion and perceived minor or moderate communication barriers. Increased likelihood to administer follow-up HPV vaccine was associated with having initiated discussion, perceiving only minor barriers and working outside Deep South states, but not with having initiated vaccination. Conclusions for Practice PCPs who discuss HPV vaccination with girls aged 11-12 and their mothers are more likely to start and sustain vaccine administration. However, different PCPs perceive barriers to discussion in different ways. Interventions tailored to different groups of PCPs should assist them in overcoming barriers to discussing their recommendations when necessary.

  16. Quasi-Elastic Reactions of SILICON-28 and Chlorine -37 with LEAD-208 at Energies in the Range of 1 TO 3 Times the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Dixit, Sunil

    Measurements have been made for the quasi-elastic scattering of ^{28}Si on ^{208}Pb at 280 and 420 MeV, and of ^{37}Cl on ^{208}Pb at 190, 330 and 433 MeV incident projectile energies. The elastic and inelastic scattering data, along with existing data at 152, 162, 166, 210, and 225 MeV, for the ^ {28}Si + ^{208} Pb system, and existing data at 250 MeV for the ^{37}Cl + ^ {208}Pb system have been analyzed using a collective model CCBA formalism. The data are well reproduced within this model at the higher energies. However, the ^{208}Pb(3_1 ^-) state predictions require an additional rotational quadrupole reorientation term at the lower energies which exhibit a striking energy dependence in the extracted effective quadrupole moment, the nuclear deformations, and the ratio (M_{rm N} /M_{rm P}) of the neutron to proton multipole matrix elements. These results suggest the possibility of threshold anomalies in the reorientation channel, highlighting the inadequacy of the collective model in describing the inelastic excitation process for heavy-ion reactions near the Coulomb barrier, at least for this state. The transfer data show large quasi-elastic yields for the one-neutron pickup channel, contributing between 50%-87% and 55%-71% of the total neutron transfer cross section as a function of decreasing projectile energy for the ^{28}Si,^ {37}Cl + ^{208} Pb reactions, respectively. The one nucleon transfer data has been analyzed using the finite range DWBA with optical-model parameters deduced from CCBA analysis and spectroscopic factors obtained from the literature. These transfer processes display a strong dependence on the ground state reaction Q-value, projectile mass, and charge. At the higher energies there is a strong deep-inelastic component (Q <= -30 MeV). This corresponds to angular distributions that are predominantly exponential for charged particle transfer greater than two. Finally, the recently observed "slope anomaly" between the one- and two

  17. Design of Protein Multi-specificity Using an Independent Sequence Search Reduces the Barrier to Low Energy Sequences

    PubMed Central

    Sevy, Alexander M.; Jacobs, Tim M.; Crowe, James E.; Meiler, Jens

    2015-01-01

    Computational protein design has found great success in engineering proteins for thermodynamic stability, binding specificity, or enzymatic activity in a ‘single state’ design (SSD) paradigm. Multi-specificity design (MSD), on the other hand, involves considering the stability of multiple protein states simultaneously. We have developed a novel MSD algorithm, which we refer to as REstrained CONvergence in multi-specificity design (RECON). The algorithm allows each state to adopt its own sequence throughout the design process rather than enforcing a single sequence on all states. Convergence to a single sequence is encouraged through an incrementally increasing convergence restraint for corresponding positions. Compared to MSD algorithms that enforce (constrain) an identical sequence on all states the energy landscape is simplified, which accelerates the search drastically. As a result, RECON can readily be used in simulations with a flexible protein backbone. We have benchmarked RECON on two design tasks. First, we designed antibodies derived from a common germline gene against their diverse targets to assess recovery of the germline, polyspecific sequence. Second, we design “promiscuous”, polyspecific proteins against all binding partners and measure recovery of the native sequence. We show that RECON is able to efficiently recover native-like, biologically relevant sequences in this diverse set of protein complexes. PMID:26147100

  18. Design of Protein Multi-specificity Using an Independent Sequence Search Reduces the Barrier to Low Energy Sequences.

    PubMed

    Sevy, Alexander M; Jacobs, Tim M; Crowe, James E; Meiler, Jens

    2015-07-01

    Computational protein design has found great success in engineering proteins for thermodynamic stability, binding specificity, or enzymatic activity in a 'single state' design (SSD) paradigm. Multi-specificity design (MSD), on the other hand, involves considering the stability of multiple protein states simultaneously. We have developed a novel MSD algorithm, which we refer to as REstrained CONvergence in multi-specificity design (RECON). The algorithm allows each state to adopt its own sequence throughout the design process rather than enforcing a single sequence on all states. Convergence to a single sequence is encouraged through an incrementally increasing convergence restraint for corresponding positions. Compared to MSD algorithms that enforce (constrain) an identical sequence on all states the energy landscape is simplified, which accelerates the search drastically. As a result, RECON can readily be used in simulations with a flexible protein backbone. We have benchmarked RECON on two design tasks. First, we designed antibodies derived from a common germline gene against their diverse targets to assess recovery of the germline, polyspecific sequence. Second, we design "promiscuous", polyspecific proteins against all binding partners and measure recovery of the native sequence. We show that RECON is able to efficiently recover native-like, biologically relevant sequences in this diverse set of protein complexes.

  19. Hierarchies, multiple energy barriers, and robustness govern the fracture mechanics of alpha-helical and beta-sheet protein domains.

    PubMed

    Ackbarow, Theodor; Chen, Xuefeng; Keten, Sinan; Buehler, Markus J

    2007-10-16

    The fundamental fracture mechanisms of biological protein materials remain largely unknown, in part, because of a lack of understanding of how individual protein building blocks respond to mechanical load. For instance, it remains controversial whether the free energy landscape of the unfolding behavior of proteins consists of multiple, discrete transition states or the location of the transition state changes continuously with the pulling velocity. This lack in understanding has thus far prevented us from developing predictive strength models of protein materials. Here, we report direct atomistic simulation that over four orders of magnitude in time scales of the unfolding behavior of alpha-helical (AH) and beta-sheet (BS) domains, the key building blocks of hair, hoof, and wool as well as spider silk, amyloids, and titin. We find that two discrete transition states corresponding to two fracture mechanisms exist. Whereas the unfolding mechanism at fast pulling rates is sequential rupture of individual hydrogen bonds (HBs), unfolding at slow pulling rates proceeds by simultaneous rupture of several HBs. We derive the hierarchical Bell model, a theory that explicitly considers the hierarchical architecture of proteins, providing a rigorous structure-property relationship. We exemplify our model in a study of AHs, and show that 3-4 parallel HBs per turn are favorable in light of the protein's mechanical and thermodynamical stability, in agreement with experimental findings that AHs feature 3.6 HBs per turn. Our results provide evidence that the molecular structure of AHs maximizes its robustness at minimal use of building materials.

  20. An energy conservative difference scheme for the nonlinear fractional Schrödinger equations

    NASA Astrophysics Data System (ADS)

    Wang, Pengde; Huang, Chengming

    2015-07-01

    In this paper, an energy conservative Crank-Nicolson difference scheme for nonlinear Riesz space-fractional Schrödinger equations is studied. We give a rigorous analysis of the conservation properties, including mass conservation and energy conservation in the discrete sense. Based on Brouwer fixed point theorem, the existence of the difference solution is proved. By virtue of the energy method, the difference solution is shown to be unique and convergent at the order of O (τ2 +h2) in the l2-norm with time step τ and mesh size h. Finally a linearized iterative algorithm is presented and numerical experiments are given to confirm the theoretical results.

  1. The ratios of partition functions at different temperatures - Sensitivity to potential energy shape II

    NASA Astrophysics Data System (ADS)

    Buchowiecki, Marcin

    2016-05-01

    The ratios of partition functions at different temperatures are calculated and its dependence on potential energy shape is analyzed. The role of anharmonicity and non-rigidity of rotations is discussed in the context of the angular frequency and the shape of potential energy curve. A role of inflection point of potential energy curve for the quality of rigid rotor harmonic oscillator and rigid rotor Morse oscillator is elucidated.

  2. Differing impact of a major biogeographic barrier on genetic structure in two large kangaroos from the monsoon tropics of Northern Australia.

    PubMed

    Eldridge, Mark D B; Potter, Sally; Johnson, Christopher N; Ritchie, Euan G

    2014-03-01

    Tropical savannas cover 20-30% of the world's land surface and exhibit high levels of regional endemism, but the evolutionary histories of their biota remain poorly studied. The most extensive and unmodified tropical savannas occur in Northern Australia, and recent studies suggest this region supports high levels of previously undetected genetic diversity. To examine the importance of barriers to gene flow and the environmental history of Northern Australia in influencing patterns of diversity, we investigated the phylogeography of two closely related, large, vagile macropodid marsupials, the antilopine wallaroo (Macropus antilopinus; n = 78), and the common wallaroo (Macropus robustus; n = 21). Both species are widespread across the tropical savannas of Australia except across the Carpentarian Barrier (CB) where there is a break in the distribution of M. antilopinus. We determined sequence variation in the hypervariable Domain I of the mitochondrial DNA control region and genotyped individuals at 12 polymorphic microsatellite loci to assess the historical and contemporary influence of the CB on these species. Surprisingly, we detected only limited differentiation between the disjunct Northern Territory and QueenslandM. antilopinus populations. In contrast, the continuously distributedM. robustus was highly divergent across the CB. Although unexpected, these contrasting responses appear related to minor differences in species biology. Our results suggest that vicariance may not explain well the phylogeographic patterns in Australia's dynamic monsoonal environments. This is because Quaternary environmental changes in this region have been complex, and diverse individual species' biologies have resulted in less predictable and idiosyncratic responses.

  3. Intra-Subtype Variation in Enteroadhesion Accounts for Differences in Epithelial Barrier Disruption and Is Associated with Metronidazole Resistance in Blastocystis Subtype-7

    PubMed Central

    Tan, Kevin Shyong Wei

    2014-01-01

    Blastocystis is an extracellular, enteric pathogen that induces intestinal disorders in a range of hosts including humans. Recent studies have identified potential parasite virulence factors in and host responses to this parasite; however, little is known about Blastocystis-host attachment, which is crucial for colonization and virulence of luminal stages. By utilizing 7 different strains of the parasite belonging to two clinically relevant subtypes ST-4 and ST-7, we investigated Blastocystis-enterocyte adhesion and its association with parasite-induced epithelial barrier disruption. We also suggest that drug resistance in ST-7 strains might result in fitness cost that manifested as impairment of parasite adhesion and, consequently, virulence. ST-7 parasites were generally highly adhesive to Caco-2 cells and preferred binding to intercellular junctions. These strains also induced disruption of ZO-1 and occludin tight junction proteins as well as increased dextran-FITC flux across epithelial monolayers. Interestingly, their adhesion was correlated with metronidazole (Mz) susceptibility. Mz resistant (Mzr) strains were found to be less pathogenic, owing to compromised adhesion. Moreover, tolerance of nitrosative stress was also reduced in the Mzr strains. In conclusion, the findings indicate that Blastocystis attaches to intestinal epithelium and leads to epithelial barrier dysfunction and that drug resistance might entail a fitness cost in parasite virulence by limiting entero-adhesiveness. This is the first study of the cellular basis for strain-to-strain variation in parasite pathogenicity. Intra- and inter-subtype variability in cytopathogenicity provides a possible explanation for the diverse clinical outcomes of Blastocystis infections. PMID:24851944

  4. Language barriers

    PubMed Central

    Ngwakongnwi, Emmanuel; Hemmelgarn, Brenda R.; Musto, Richard; King-Shier, Kathryn M.; Quan, Hude

    2012-01-01

    Abstract Objective To assess use of regular medical doctors (RMDs), as well as awareness and use of telephone health lines or telehealth services, by official language minorities (OLMs) in Canada. Design Analysis of data from the 2006 postcensal survey on the vitality of OLMs. Setting Canada. Participants In total, 7691 English speakers in Quebec and 12 376 French speakers outside Quebec, grouped into those who experienced language barriers and those with no language barriers. Main outcome measures Health services utilization (HSU) by the presence of language barriers; HSU measures included having an RMD, use of an RMD’s services, and awareness of and use of telephone health lines or telehealth services. Multivariable models examined the associations between HSU and language barriers. Results After adjusting for age and sex, English speakers residing in Quebec with limited proficiency in French were less likely to have RMDs (adjusted odds ratio [AOR] 0.66, 95% CI 0.50 to 0.87) and to use the services of their RMDs (AOR 0.65, 95% CI 0.50 to 0.86), but were more likely to be aware of the existence of (AOR 1.50, 95% CI 1.16 to 1.93) and to use (AOR 1.43, 95% CI 0.97 to 2.11) telephone health lines or telehealth services. This pattern of having and using RMDs and telehealth services was not observed for French speakers residing outside of Quebec. Conclusion Overall we found variation in HSU among the language barrier populations, with lower use observed in Quebec. Age older than 45 years, male sex, being married or in common-law relationships, and higher income were associated with having RMDs for OLMs. PMID:23242902

  5. Differences in demographic traits of four butterflyfish species between two reefs of the Great Barrier Reef separated by 1,200 km

    NASA Astrophysics Data System (ADS)

    Berumen, M. L.; Trip, E. D. L.; Pratchett, M. S.; Choat, J. H.

    2012-03-01

    Many species demonstrate variation in life history attributes in response to gradients in environmental conditions. For fishes, major drivers of life history variation are changes in temperature and food availability. This study examined large-scale variation in the demography of four species of butterflyfishes ( Chaetodon citrinellus, Chaetodon lunulatus, Chaetodon melannotus, and Chaetodon trifascialis) between two locations on Australia's Great Barrier Reef (Lizard Island and One Tree Island, separated by approximately 1,200 km). Variation in age-based demographic parameters was assessed using the re-parameterised von Bertalanffy growth function. All species displayed measurable differences in body size between locations, with individuals achieving a larger adult size at the higher latitude site (One Tree Island) for three of the four species examined. Resources and abundances of the study species were also measured, revealing some significant differences between locations. For example, for C. trifascialis, there was no difference in its preferred resource or in abundance between locations, yet it achieved a larger body size at the higher latitude location, suggesting a response to temperature. For some species, resources and abundances did vary between locations, limiting the ability to distinguish between a demographic response to temperature as opposed to a response to food or competition. Future studies of life histories and demographics at large spatial scales will need to consider the potentially confounding roles of temperature, resource usage and availability, and abundance/competition to disentangle the effects of these environmental variables.

  6. Problems in characterizing barrier performance

    NASA Technical Reports Server (NTRS)

    Jordan, Harry F.

    1988-01-01

    The barrier is a synchronization construct which is useful in separating a parallel program into parallel sections which are executed in sequence. The completion of a barrier requires cooperation among all executing processes. This requirement not only introduces the wait for the slowest process delay which is inherent in the definition of the synchronization, but also has implications for the efficient implementation and measurement of barrier performance in different systems. Types of barrier implementation and their relationship to different multiprocessor environments are described. Then the problem of measuring the performance of barrier implementations on specific machine architecture is discussed. The fact that the barrier synchronization requires the cooperation of all processes makes the problem of performance measurement similarly global. Making non-intrusive measurements of sufficient accuracy can be tricky on systems offering only rudimentary measurement tools.

  7. Climate impacts on extreme energy consumption of different types of buildings.

    PubMed

    Li, Mingcai; Shi, Jun; Guo, Jun; Cao, Jingfu; Niu, Jide; Xiong, Mingming

    2015-01-01

    Exploring changes of building energy consumption and its relationships with climate can provide basis for energy-saving and carbon emission reduction. Heating and cooling energy consumption of different types of buildings during 1981-2010 in Tianjin city, was simulated by using TRNSYS software. Daily or hourly extreme energy consumption was determined by percentile methods, and the climate impact on extreme energy consumption was analyzed. The results showed that days of extreme heating consumption showed apparent decrease during the recent 30 years for residential and large venue buildings, whereas days of extreme cooling consumption increased in large venue building. No significant variations were found for the days of extreme energy consumption for commercial building, although a decreasing trend in extreme heating energy consumption. Daily extreme energy consumption for large venue building had no relationship with climate parameters, whereas extreme energy consumption for commercial and residential buildings was related to various climate parameters. Further multiple regression analysis suggested heating energy consumption for commercial building was affected by maximum temperature, dry bulb temperature, solar radiation and minimum temperature, which together can explain 71.5 % of the variation of the daily extreme heating energy consumption. The daily extreme cooling energy consumption for commercial building was only related to the wet bulb temperature (R2= 0.382). The daily extreme heating energy consumption for residential building was affected by 4 climate parameters, but the dry bulb temperature had the main impact. The impacts of climate on hourly extreme heating energy consumption has a 1-3 hour delay in all three types of buildings, but no delay was found in the impacts of climate on hourly extreme cooling energy consumption for the selected buildings.

  8. Climate Impacts on Extreme Energy Consumption of Different Types of Buildings

    PubMed Central

    Li, Mingcai; Shi, Jun; Guo, Jun; Cao, Jingfu; Niu, Jide; Xiong, Mingming

    2015-01-01

    Exploring changes of building energy consumption and its relationships with climate can provide basis for energy-saving and carbon emission reduction. Heating and cooling energy consumption of different types of buildings during 1981-2010 in Tianjin city, was simulated by using TRNSYS software. Daily or hourly extreme energy consumption was determined by percentile methods, and the climate impact on extreme energy consumption was analyzed. The results showed that days of extreme heating consumption showed apparent decrease during the recent 30 years for residential and large venue buildings, whereas days of extreme cooling consumption increased in large venue building. No significant variations were found for the days of extreme energy consumption for commercial building, although a decreasing trend in extreme heating energy consumption. Daily extreme energy consumption for large venue building had no relationship with climate parameters, whereas extreme energy consumption for commercial and residential buildings was related to various climate parameters. Further multiple regression analysis suggested heating energy consumption for commercial building was affected by maximum temperature, dry bulb temperature, solar radiation and minimum temperature, which together can explain 71.5 % of the variation of the daily extreme heating energy consumption. The daily extreme cooling energy consumption for commercial building was only related to the wet bulb temperature (R2= 0.382). The daily extreme heating energy consumption for residential building was affected by 4 climate parameters, but the dry bulb temperature had the main impact. The impacts of climate on hourly extreme heating energy consumption has a 1-3 hour delay in all three types of buildings, but no delay was found in the impacts of climate on hourly extreme cooling energy consumption for the selected buildings. PMID:25923205

  9. Path Integral Computation of Quantum Free Energy Differences Due to Alchemical Transformations Involving Mass and Potential.

    PubMed

    Pérez, Alejandro; von Lilienfeld, O Anatole

    2011-08-09

    Thermodynamic integration, perturbation theory, and λ-dynamics methods were applied to path integral molecular dynamics calculations to investigate free energy differences due to "alchemical" transformations. Several estimators were formulated to compute free energy differences in solvable model systems undergoing changes in mass and/or potential. Linear and nonlinear alchemical interpolations were used for the thermodynamic integration. We find improved convergence for the virial estimators, as well as for the thermodynamic integration over nonlinear interpolation paths. Numerical results for the perturbative treatment of changes in mass and electric field strength in model systems are presented. We used thermodynamic integration in ab initio path integral molecular dynamics to compute the quantum free energy difference of the isotope transformation in the Zundel cation. The performance of different free energy methods is discussed.

  10. Species differences in blood-brain barrier transport of three positron emission tomography radioligands with emphasis on P-glycoprotein transport.

    PubMed

    Syvänen, Stina; Lindhe, Orjan; Palner, Mikael; Kornum, Birgitte R; Rahman, Obaidur; Långström, Bengt; Knudsen, Gitte M; Hammarlund-Udenaes, Margareta

    2009-03-01

    Species differences occur in the brain concentrations of drugs, but the reasons for these differences are not yet apparent. This study was designed to compare brain uptake of three radiolabeled P-glycoprotein (P-gp) substrates across species using positron emission tomography. Brain concentrations and brain-to-plasma ratios were compared; [(11)C]verapamil in rats, guinea pigs, and monkeys; [(11)C](S)-(2-methoxy-5-(5-trifluoromethyltetrazol-1-yl)-phenylmethylamino)-2(S)-phenylpiperidine (GR205171) in rats, guinea pigs, monkeys, and humans; and [(18)F]altanserin in rats, minipigs, and humans. The fraction of the unbound radioligand in plasma was studied along with its metabolism. The effect of P-gp inhibition was investigated by administering cyclosporin A (CsA). Pronounced species differences were found in the brain and brain-to-plasma concentrations of [(11)C]verapamil, [(11)C]GR205171, and [(18)F]altanserin with higher brain distribution in humans, monkeys, and minipigs than in rats and guinea pigs. For example, the brain-to-plasma ratio of [(11)C]GR205171 was almost 9-fold higher in humans compared with rats. The species differences were still present after P-gp inhibition, although the increase in brain concentrations after P-gp inhibition was somewhat greater in rats than in the other species. Differences in plasma protein binding and metabolism did not explain the species-related differences. The findings are important for interpretation of brain drug delivery when extrapolating preclinical data to humans. Compounds found to be P-gp substrates in rodents are likely to also be substrates in higher species, but sufficient blood-brain barrier permeability may be retained in humans to allow the compound to act at intracerebral targets.

  11. Irritants and Skin Barrier Function.

    PubMed

    Angelova-Fischer, Irena

    2016-01-01

    The barrier response to irritant challenge involves complex biologic events and can be modulated by various environmental, exposure and host-related factors. Irritant damage to the epidermal barrier elicits a cascade of homeostatic or pathologic responses that could be investigated by both in vitro and in vivo methods providing different information at biochemical and functional level. The present chapter summarizes the changes in key barrier function parameters following irritant exposure with focus on experimental controlled in vivo human skin studies.

  12. Improving photoelectrochemical performance on quantum dots co-sensitized TiO2 nanotube arrays using ZnO energy barrier by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Zeng, Min; Zeng, Xi; Peng, Xiange; Zhu, Zhuo; Liao, Jianjun; Liu, Kai; Wang, Guizhen; Lin, Shiwei

    2016-12-01

    PbS and CdS quantum dots (QDs) have been deposited onto TiO2 nanotube arrays (TNTAs) in turn via a sonication-assisted successive ionic layer adsorption and reaction method. This method could uniformly decorate TNTAs with QDs, avoiding QDs aggregation at the mouth of TiO2 nanotube. The loading amounts of QDs on TNTAs could be controlled by adjusting the TNTAs length. Under one sun illumination, the QDs co-sensitized TNTAs (TNTAs/QDs) with the length of about 2.4 μm displayed the highest photocurrent of 4.32 mA cm-2, which is 27 times higher than that of the bare TNTAs. Introduction of a thin ZnO energy barrier by atomic layer deposition (ALD) between the TNTAs and QDs can further improve the photocurrent of TNTAs/QDs. And the TNTAs/QDs with 10 ALD cycles of ZnO interlayer exhibits the highest photocurrent of 5.24 mA cm-2 and best photoconversion efficiency of 4.9%, a more than 20% enhancement over the bare TNTAs/QDs. Such enhanced photoelectrochemical performance may be ascribed to the increased amounts of QDs on the TNTAs due to the introduction of ZnO interlayer. The benefits of ALD layers play a crucial role in development and optimization of high-performance photoelectrodes in the near future.

  13. Preparation and characterization of nanocrystalline ZrO2-7%Y2O3 powders for thermal barrier coatings by high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Bobzin, Kirsten; Zhao, Lidong; Schlaefer, Thomas; Warda, Thomas

    2011-06-01

    High-energy ball milling is an effective method to produce nanocrystalline oxides. In this study, a conventional ZrO2-7%Y2O3 spray powder was ball-milled to produce nanocrystalline powders with high levels of crystalline disorders for deposition of thermal barrier coatings. The powder was milled both with 100Cr6 steel balls and with ZrO2-3%Y2O3 ceramic balls as grinding media. The milling time was varied in order to investigate the effect of the milling time on the crystallite size. The powders were investigated in terms of their crystallite sizes and morphologies by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that under given milling conditions the powder was already nanostructured after 40 min milling. The crystallite size decreased significantly with increasing milling time within first 120 min. After that, a further increase of milling time did not lead to a significant reduction of the crystallite size. Ball-milling led to lattice microstrains. Milling with the steel balls resulted in finer nano-sized crystal grains, but caused the contamination of the powder. The nano-sized crystal grains coarsened during the heat-treatment at 1250°C.

  14. Sub-barrier fusion calculations for the neutron star crust using the microscopic Brueckner G -matrix and Skyrme energy density functionals

    NASA Astrophysics Data System (ADS)

    Rashdan, M.

    2015-05-01

    Sub-barrier fusion cross sections for reactions involving stable and very neutron-rich nuclei, which may be important in determining the composition and heating of the crust of accreting neutron stars, are calculated using internuclear potentials derived from the microscopic Brueckner G -matrix and Skyrme SKM* and SLy4 energy density functionals. Microscopic Skyrme-Hartree-Fock proton and neutron density distributions are used. No parameters have been fit to fusion data. Calculations are performed for the isotopic reactions 16O+16O,16O+24O,16O+28O,24O+24O,12C+16O,12C+24O , and 12C+12C , which are of great astrophysical importance for the understanding of the time scale and the nucleosynthesis during late stellar evolution. The coupling to the low lying excited states is considered through the ccfull code. I compare my results with the time-dependent-Hartree-Fock calculations and with the São Paulo model as well as the experimental data. I found a remarkable agreement with the fusion cross sections for stable nuclei.

  15. Understanding the role of silica nanospheres with their light scattering and energy barrier properties in enhancing the photovoltaic performance of ZnO based solar cells.

    PubMed

    Banik, Avishek; Ansari, Mohammad Shaad; Sahu, Tushar Kanta; Qureshi, Mohammad

    2016-10-12

    The present study discusses the design and development of a dye sensitized solar cell (DSSC) using a hybrid composite of ZnO nanoparticles (ZnO NP) and silica nanospheres (SiO2 NS). A ≈22% enhancement in the overall power conversion efficiency (PCE, η) was observed for the device fabricated with a binary hybrid composite of 1 wt% SiO2 NS and ZnO NP compared to the pristine ZnO NP device. A systematic investigation revealed the dual function of the silica nanospheres in enhancing the device efficacy compared to the bare ZnO NP based device. Sub-micron sized SiO2 NS can boost the light harvesting efficiency of the photoanode by optical confinement, resulting in increased propagation length of the incident light by multiple internal reflections, which was confirmed by UV-Vis diffused reflectance spectroscopy. Electrochemical impedance spectroscopic (EIS) analysis showed a reduced recombination of photo-generated electrons to the I(-)/I3(-) redox shuttle in the case of the composite photoanode. The higher recombination resistance (Rct) in the case of a 1 wt% composite indicates that the SiO2 NS serves as a partial energy barrier layer to retard the interfacial recombination (back transfer) of photo-generated electrons at the working electrode/electrolyte interface, increasing the device efficiency.

  16. Effect of inter-species selective interactions on the thermodynamics and nucleation free-energy barriers of a tessellating polyhedral compound

    NASA Astrophysics Data System (ADS)

    Escobedo, Fernando A.

    2016-12-01

    The phase behavior and the homogeneous nucleation of an equimolar mixture of octahedra and cuboctahedra are studied using thermodynamic integration, Gibbs-Duhem integration, and umbrella sampling simulations. The components of this mixture are modeled as polybead objects of equal edge lengths so that they can assemble into a space-filling compound with the CsCl crystal structure. Taking as reference the hard-core system where the compound crystal does not spontaneously nucleate, we quantified the effect of inter-species selective interactions on facilitating the disorder-to-order transition. Facet selective and facet non-selective inter-species attractions were considered, and while the former was expectedly more favorable toward the target tessellating structure, the latter was found to be similarly effective in nucleating the crystal compound. Ranges for the strength of attractions and degree of supersaturation were identified where the nucleation free-energy barrier was small enough to foretell a fast process but large enough to prevent spinodal fluctuations that can trap the system in dense metastable states lacking long-range order. At those favorable conditions, the tendency toward the local orientational order favored by packing entropy is amplified and found to play a key role seeding nuclei with the CsCl structure.

  17. Mechanism of pluronic effect on P-glycoprotein efflux system in blood-brain barrier: contributions of energy depletion and membrane fluidization.

    PubMed

    Batrakova, E V; Li, S; Vinogradov, S V; Alakhov, V Y; Miller, D W; Kabanov, A V

    2001-11-01

    Pluronic block copolymer, P85, inhibits the P-glycoprotein (Pgp) drug efflux system and increases the permeability of a broad spectrum of drugs in the blood-brain barrier (BBB). This study examines the mechanisms by which P85 inhibits Pgp using bovine brain microvessel endothelial cells (BBMEC) as an in vitro model of the BBB. The hypothesis was that simultaneous alterations in intracellular ATP levels and membrane fluidization in BBMEC monolayers by P85 results in inhibition of the drug efflux system. The methods included the use of 1) standard Pgp substrate rhodamine 123 to assay the Pgp efflux system in BBMEC, 2) luciferin/luciferase assay for ATP intracellular levels, and 3) 1,6-diphenyl-1,3,5-hexatriene for membrane microviscosity. Using 3H-labeled P85 and fluorescein-labeled P85 for confocal microscopy, this study suggests that P85 accumulates in the cells and intracellular organelles such as the mitochondria where it can interfere with metabolic processes. Following exposure of BBMEC to P85, the ATP levels were depleted, and microviscosity of the cell membranes was decreased. Furthermore, P85 treatment decreased Pgp ATPase activity in membranes expressing human Pgp. A combination of experiments examining the kinetics, concentration dependence, and directionality of P85 effects on Pgp-mediated efflux in BBMEC monolayers suggests that both energy depletion (decreasing ATP pool available for Pgp) and membrane fluidization (inhibiting Pgp ATPase activity) are critical factors contributing to the activity of the block copolymer in the BBB.

  18. Impact behaviour of Napier/polyester composites under different energy levels

    NASA Astrophysics Data System (ADS)

    Fahmi, I.; Majid, M. S. Abdul; Afendi, M.; Haslan, M.; Helmi E., A.; M. Haameem J., A.

    2016-07-01

    The effects of different energy levels on the impact behaviour of Napier fibre/polyester reinforced composites were investigated. Napier fibre was extracted using traditional water retting process to be utilized as reinforcing materials in polyester composite laminates. 25% fibre loading composite laminates were prepared and impacted at three different energy levels; 2.5,5 and 7.5 J using an instrumented drop weight impact testing machine (IMATEK IM10). The outcomes show that peak force and contact time increase with increased impact load. The energy absorption was then calculated from the force displacement curve. The results indicated that the energy absorption decreases with increasing energy levels of the impact. Impacted specimens were observed visually for fragmentation fracture using an optical camera to identify the failure mechanisms. Fracture fragmentation pattern from permanent dent to perforation with radial and circumferential was observed.

  19. Correlated states and transparency of a barrier for low-energy particles at monotonic deformation of a potential well with dissipation and a stochastic force

    NASA Astrophysics Data System (ADS)

    Vysotskii, V. I.; Vysotskyy, M. V.

    2014-04-01

    The features of the formation of correlated coherent states of a particle in a parabolic potential well at its monotonic deformation (expansion or compression) in finite limits have been considered in the presence of dissipation and a stochastic force. It has been shown that, in both deformation regimes, a correlated coherent state is rapidly formed with a large correlation coefficient | r| → 1, which corresponds at a low energy of the particle to a very significant (by a factor of 1050-10100 or larger) increase in the transparency of the potential barrier at its interaction with atoms (nuclei) forming the "walls" of the potential well or other atoms located in the same well. The efficiency of the formation of correlated coherent states, as well as | r|, increases with an increase in the deformation interval and with a decrease in the deformation time. The presence of the stochastic force acting on the particle can significantly reduce the maximum | r| value and result in the fast relaxation of correlated coherent states with | r| → 0. The effect of dissipation in real systems is weaker than the action of the stochastic force. It has been shown that the formation of correlated coherent states at the fast expansion of the well can underlie the mechanism of nuclear reactions at a low energy, e.g., in microcracks developing in the bulk of metal hydrides loaded with hydrogen or deuterium, as well as in a low-pressure plasma in a variable magnetic field in which the motion of ions is similar to a harmonic oscillator with a variable frequency.

  20. Energy cost and energy sources of a ballet dance exercise in female adolescents with different technical ability.

    PubMed

    Guidetti, Laura; Emerenziani, Gian Pietro; Gallotta, Maria Chiara; Da Silva, Sergio Gregorio; Baldari, Carlo

    2008-06-01

    This study evaluated energy cost and energy sources of a ballet exercise (grand adage) in young female dancers with different technical ability, and then related the energy sources to the subject's VO(2max) and anaerobic threshold (IAT). Twenty-five dancers (13-16 years) were divided into two different technical ability groups: low-level (n = 13) and high-level (n = 12). The overall energy requirement of dance exercise (VO(2eq)) was obtained by adding the amount of VO(2) during exercise above resting (aerobic source or VO(2ex)) to the VO(2) up to the fast component of recovery (anaerobic alactic source or VO(2al)) and to the energy equivalent of peak blood lactate accumulation (anaerobic lactic source or VO(2la) of recovery. VO(2eq) of exercise amounted to 81 +/- 10 and 94 +/- 9 ml kg(-1) in low-level and high-level groups, respectively. VO(2ex) represented the higher fraction (65 +/- 4% and 77 +/- 5%) in low-level and high-level groups, respectively, of VO(2eq )in both the groups. In the low-level group the remaining fractions were: 23 +/- 2 % for VO(2al) and 12 +/- 1% for VO(2la). In high-level group the remaining fractions were: 18 +/- 2 % for VO(2al) and 4 +/- 1% for VO(2la). Between two groups, significant differences were found in VO(2ex )(P < 0.01), VO(2al) (P < 0.01), and VO(2al )(P < 0.05). IAT was 55 and 60% of VO(2max) for low-level and high-level dancers, respectively. Low-level dancers performed more exercise above IAT than high-level. For these reasons, it should be better to define exercise intensity according to the IAT parameter and not only to VO(2max).

  1. Renewable Energy and Efficiency Modeling Analysis Partnership: An Analysis of How Different Energy Models Addressed a Common High Renewable Energy Penetration Scenario in 2025

    SciTech Connect

    Blair, N.; Jenkin, T.; Milford, J.; Short, W.; Sullivan, P.; Evans, D.; Lieberman, E.; Goldstein, G.; Wright, E.; Jayaraman, K.; Venkatech, B.; Kleiman, G.; Namovicz, C.; Smith, B.; Palmer, K.; Wiser, R.; Wood, F.

    2009-09-30

    The Renewable Energy and Efficiency Modeling and Analysis Partnership (REMAP) sponsors ongoing workshops to discuss individual 'renewable' technologies, energy/economic modeling, and - to some extent - policy issues related to renewable energy. Since 2002, the group has organized seven workshops, each focusing on a different renewable technology (geothermal, solar, wind, etc.). These workshops originated and continue to be run under an informal partnership of the Environmental Protection Agency (EPA), the Department of Energy's (DOE) Office of Energy Efficiency and Renewable Energy (EERE), the National Renewable Energy Laboratory (NREL), and the American Council on Renewable Energy (ACORE). EPA originally funded the activities, but support is now shared between EPA and EERE. REMAP has a wide range of participating analysts and models/modelers that come from government, the private sector, and academia. Modelers include staff from the Energy Information Administration (EIA), the American Council for an Energy-Efficient Economy (ACEEE), NREL, EPA, Resources for the Future (RFF), Argonne National Laboratory (ANL), Northeast States for Coordinated Air Use Management (NESCAUM), Regional Economic Models Inc. (REMI), ICF International, OnLocation Inc., and Boston University. The working group has more than 40 members, which also includes representatives from DOE, Lawrence Berkeley National Laboratory (LBNL), Union of Concerned Scientists (UCS), Massachusetts Renewable Energy Trust, Federal Energy Regulatory Commission (FERC), and ACORE. This report summarizes the activities and findings of the REMAP activity that started in late 2006 with a kickoff meeting, and concluded in mid-2008 with presentations of final results. As the project evolved, the group compared results across models and across technologies rather than just examining a specific technology or activity. The overall goal was to better understand how and why different energy models give similar and

  2. Barriers of the peripheral nerve

    PubMed Central

    Peltonen, Sirkku; Alanne, Maria; Peltonen, Juha

    2013-01-01

    This review introduces the traditionally defined anatomic compartments of the peripheral nerves based on light and electron microscopic topography and then explores the cellular and the most recent molecular basis of the different barrier functions operative in peripheral nerves. We also elucidate where, and how, the homeostasis of the normal human peripheral nerve is controlled in situ and how claudin-containing tight junctions contribute to the barriers of peripheral nerve. Also, the human timeline of the development of the barriers of the peripheral nerve is depicted. Finally, potential future therapeutic modalities interfering with the barriers of the peripheral nerve are discussed. PMID:24665400

  3. The effect of fruit in different forms on energy intake and satiety at a meal.

    PubMed

    Flood-Obbagy, Julie E; Rolls, Barbara J

    2009-04-01

    Consuming whole fruit reduces ratings of satiety more than fruit juice, but little is known about the effects of different forms of fruit on subsequent energy intake. This study tested how consuming preloads of apples in different forms prior to a meal (apple, applesauce, and apple juice with and without added fiber) influences satiety and energy intake at meal. Preloads were matched for weight, energy content, energy density, and ingestion rate. Once a week for 5 weeks, 58 adults consumed one of four preloads (266 g; 125 kcal [523 kJ]), or no preload (control), followed by a test meal consumed ad libitum 15 min later. Results showed that eating apple reduced lunch energy intake (preload+test meal) by 15% (187+/-36 kcal [782+/-151 kJ]) compared to control (p<0.0001) and decreased energy intake compared to applesauce and both juices. Fullness ratings differed significantly after preload consumption (apple>applesauce>both juices>control). Overall, whole apple increased satiety more than applesauce or apple juice. Adding naturally occurring levels of fiber to juice did not enhance satiety. These results suggest that solid fruit affects satiety more than pureed fruit or juice, and that eating fruit at the start of a meal can reduce energy intake.

  4. Charge transport in molecular electronic junctions: compression of the molecular tunnel barrier in the strong coupling regime.

    PubMed

    Sayed, Sayed Y; Fereiro, Jerry A; Yan, Haijun; McCreery, Richard L; Bergren, Adam Johan

    2012-07-17

    Molecular junctions are essentially modified electrodes familiar to electrochemists where the electrolyte is replaced by a conducting "contact." It is generally hypothesized that changing molecular structure will alter system energy levels leading to a change in the transport barrier. Here, we show the conductance of seven different aromatic molecules covalently bonded to carbon implies a modest range (< 0.5 eV) in the observed transport barrier despite widely different free molecule HOMO energies (> 2 eV range). These results are explained by considering the effect of bonding the molecule to the substrate. Upon bonding, electronic inductive effects modulate the energy levels of the system resulting in compression of the tunneling barrier. Modification of the molecule with donating or withdrawing groups modulate the molecular orbital energies and the contact energy level resulting in a leveling effect that compresses the tunneling barrier into a range much smaller than expected. Whereas the value of the tunneling barrier can be varied by using a different class of molecules (alkanes), using only aromatic structures results in a similar equilibrium value for the tunnel barrier for different structures resulting from partial charge transfer between the molecular layer and the substrate. Thus, the system does not obey the Schottky-Mott limit, and the interaction between the molecular layer and the substrate acts to influence the energy level alignment. These results indicate that the entire system must be considered to determine the impact of a variety of electronic factors that act to determine the tunnel barrier.

  5. Penetration barrier contributes to bacterial biofilm-associated resistance against only select antibiotics, and exhibits genus-, strain- and antibiotic-specific differences.

    PubMed

    Singh, Rachna; Sahore, Simmi; Kaur, Preetinder; Rani, Alka; Ray, Pallab

    2016-08-01

    Bacterial biofilms are implicated in a wide range of implant-based and chronic infections. These infections are often associated with adverse therapeutic outcomes, owing to the decreased antibiotic susceptibility of biofilms compared with their planktonic counterparts. This altered biofilm susceptibility has been attributed to multiple factors, including a reduced antibiotic penetration. Although several studies have addressed the role of penetration barrier in biofilm-associated drug resistance, it remains inconclusive. This study was done to elucidate antibiotic penetration through biofilms formed by Staphylococcus aureus, S. epidermidis, Escherichia coli and Klebsiella pneumoniae, using an agar disk diffusion assay. Penetration capacity of six antimicrobial drugs from different classes (β-lactams, aminoglycosides, tetracyclines, phenicols, fluoroquinolones and glycopeptides) through biofilms formed by standard strains and clinical isolates from catheter-related bloodstream infections (CRBSI) was elucidated by measuring their growth-inhibition zones in lawn cultures on Mueller-Hinton agar, following diffusion of an antibiotic from an overlying disk through their biofilm to the agar medium. Penetration of only select antimicrobials (vancomycin and chloramphenicol) was hindered through biofilms. There was considerable variation in biofilm-permeating capacity depending upon the genus, strain/CRBSI isolate and antibiotic tested. Furthermore, antibiotics failed to kill the biofilm cells independent of penetration, indicating that other factors contributed substantially to biofilm resistance.

  6. Target or barrier? The cell wall of early- and later-diverging plants vs cadmium toxicity: differences in the response mechanisms

    PubMed Central

    Parrotta, Luigi; Guerriero, Gea; Sergeant, Kjell; Cai, Giampiero; Hausman, Jean-Francois

    2015-01-01

    Increasing industrialization and urbanization result in emission of pollutants in the environment including toxic heavy metals, as cadmium and lead. Among the different heavy metals contaminating the environment, cadmium raises great concern, as it is ecotoxic and as such can heavily impact ecosystems. The cell wall is the first structure of plant cells to come in contact with heavy metals. Its composition, characterized by proteins, polysaccharides and in some instances lignin and other phenolic compounds, confers the ability to bind non-covalently and/or covalently heavy metals via functional groups. A strong body of evidence in the literature has shown the role of the cell wall in heavy metal response: it sequesters heavy metals, but at the same time its synthesis and composition can be severely affected. The present review analyzes the dual property of plant cell walls, i.e., barrier and target of heavy metals, by taking Cd toxicity as example. Following a summary of the known physiological and biochemical responses of plants to Cd, the review compares the wall-related mechanisms in early- and later-diverging land plants, by considering the diversity in cell wall composition. By doing so, common as well as unique response mechanisms to metal/cadmium toxicity are identified among plant phyla and discussed. After discussing the role of hyperaccumulators’ cell walls as a particular case, the review concludes by considering important aspects for plant engineering. PMID:25814996

  7. Linking HIV-positive adolescents to care in 15 different clinics across the United States: creating solutions to address structural barriers for linkage to care.

    PubMed

    Philbin, Morgan M; Tanner, Amanda E; Duval, Anna; Ellen, Jonathan; Kapogiannis, Bill; Fortenberry, J Dennis

    2014-01-01

    Linkage to care is a critical corollary to expanded HIV testing, but many adolescents are not successfully linked to care, in part due to fragmented care systems. Through a collaboration of the National Institutes of Health (NIH), Centers for Disease Control and Prevention (CDC) and the Adolescent Trials Network (ATN), a linkage to care outreach worker was provided to ATN clinics. Factors related to linkage were explored to better understand how to improve retention rates and health outcomes for HIV-positive adolescents. We conducted 124 interviews with staff at 15 Adolescent Trials Network clinics to better understand linkage to care processes, barriers, and facilitators. Content analysis was conducted focusing on structural barriers to care and potential solutions, specifically at the macro-, meso-, and micro-levels. Macro-level barriers included navigating health insurance policies, transportation to appointments, and ease of collecting and sharing client-level contact information between testing agencies, local health departments and clinics; meso-level barriers included lack of youth friendliness within clinic space and staff, and duplication of linkage services; micro-level barriers included adolescents' readiness for care and adolescent developmental capacity. Staff initiated solutions included providing transportation for appointments and funding clinic visits and tests with a range of grants and clinic funds while waiting for insurance approval. However, such solutions were often ad hoc and partial, using micro-level solutions to address macro-level barriers. Comprehensive initiatives to improve linkage to care are needed to address barriers to HIV-care for adolescents, whose unique developmental needs make accessing care particularly challenging. Matching the level of structural solution to the level of structural barriers (i.e., macro-level with macro-level), such as creating policy to address needed youth healthcare entitlements versus covering

  8. Emergy-based comparative analysis of energy intensity in different industrial systems.

    PubMed

    Liu, Zhe; Geng, Yong; Wang, Hui; Sun, Lu; Ma, Zhixiao; Tian, Xu; Yu, Xiaoman

    2015-12-01

    With the rapid economic development, energy consumption of China has been the second place in the world next to the USA. Usually, measuring energy consumption intensity or efficiency applies heat unit which is joule per gross domestic production (GDP) or coal equivalent per GDP. However, this measuring approach is only oriented by the conversion coefficient of heat combustion which does not match the real value of the materials during their formation in the ecological system. This study applied emergy analysis to evaluate the energy consumption intensity to fill this gap. Emergy analysis is considered as a bridge between ecological system and economic system, which can evaluate the contribution of ecological products and services as well as the load placed on environmental systems. In this study, emergy indicator for performing energy consumption intensity of primary energy was proposed. Industrial production is assumed as the main contributor of energy consumption compared to primary and tertiary industries. Therefore, this study validated this method by investigating the two industrial case studies which were Dalian Economic Development Area (DEDA) and Fuzhou economic and technological area (FETA), to comparatively study on their energy consumption intensity between the different kinds of industrial systems and investigate the reasons behind the differences. The results show that primary energy consumption (PEC) of DEDA was much higher than that of FETA during 2006 to 2010 and its primary energy consumption ratio (PECR) to total emergy involvement had a dramatically decline from year 2006 to 2010. In the same time, nonrenewable energy of PEC in DEDA was also much higher than that in FETA. The reason was that industrial structure of DEDA was mainly formed by heavy industries like petro-chemistry industry, manufacturing industries, and high energy-intensive industries. However, FETA was formed by electronic business, food industry, and light industries. Although

  9. Heavy-Ion Fusion near and below the Coulomb Barrier: New Results

    NASA Astrophysics Data System (ADS)

    Stefanini, A. M.

    2009-03-01

    Fusion hindrance well below the Coulomb barrier has been observed in several systems in recent years showing systematic but also unsystematic behaviours. Our understanding of this phenomenon has greatly advanced in the last 2-3 years. Coupled-channel effects leading to barrier distributions, influence the threshold energy for hindrance. Very recent measurements on 36S+48Ca, 64Ni, performed at LNL, are presented. The two excitation functions are very different below the barrier, possibly due to the Q-value for CN formation. A few other systems, for which previous experiments were done, show interesting features, suggesting measurements at still lower energies.

  10. Performance analysis of different ORC configurations for thermal energy and LNG cold energy hybrid power generation system

    NASA Astrophysics Data System (ADS)

    Sun, Zhixin; Wang, Feng; Wang, Shujia; Xu, Fuquan; Lin, Kui

    2017-01-01

    This paper presents a thermal energy and Liquefied natural gas (LNG) cold energy hybrid power generation system. Performances of four different Organic Rankine cycle (ORC) configurations (the basic, the regenerative, the reheat and the regenerative-reheat ORCs) are studied based on the first and the second law of thermodynamics. Dry organic fluid R245fa is selected as the typical working fluid. Parameter analysis is also conducted in this paper. The results show that regeneration could not increase the thermal efficiency of the thermal and cold energy hybrid power generation system. ORC with the reheat process could produce more specific net power output but it may also reduce the system thermal efficiency. The basic and the regenerative ORCs produce higher thermal efficiency while the regenerative-reheat ORC performs best in the exergy efficiency. A preheater is necessary for the thermal and cold energy hybrid power generation system. And due to the presence of the preheater, there will be a step change of the system performance as the turbine inlet pressure rises.

  11. Nested barriers to low-carbon infrastructure investment

    NASA Astrophysics Data System (ADS)

    Granoff, Ilmi; Hogarth, J. Ryan; Miller, Alan

    2016-12-01

    Low-carbon, 'green' economic growth is necessary to simultaneously improve human welfare and avoid the worst impacts of climate change and environmental degradation. Infrastructure choices underpin both the growth and the carbon intensity of the economy. This Perspective explores the barriers to investing in low-carbon infrastructure and some of the policy levers available to overcome them. The barriers to decarbonizing infrastructure 'nest' within a set of barriers to infrastructure development more generally that cause spending on infrastructure--low-carbon or not--to fall more than 70% short of optimal levels. Developing countries face additional barriers such as currency and political risks that increase the investment gap. Low-carbon alternatives face further barriers, such as commercialization risk and financial and public institutions designed for different investment needs. While the broader barriers to infrastructure investment are discussed in other streams of literature, they are often disregarded in literature on renewable energy diffusion or climate finance, which tends to focus narrowly on the project costs of low- versus high-carbon options. We discuss how to overcome the barriers specific to low-carbon infrastructure within the context of the broader infrastructure gap.

  12. Computation of free energy differences through nonequilibrium stochastic dynamics: The reaction coordinate case

    SciTech Connect

    Lelievre, Tony . E-mail: lelievre@cermics.enpc.fr; Rousset, Mathias . E-mail: rousset@cermics.enpc.fr; Stoltz, Gabriel . E-mail: stoltz@cermics.enpc.fr

    2007-03-20

    The computation of free energy differences through an exponential weighting of out-of-equilibrium paths (known as the Jarzynski equality [C. Jarzynski, Equilibrium free energy differences from nonequilibrium measurements: a master equation approach, Phys. Rev. E 56 (5) (1997) 5018-5035, C. Jarzynski, Nonequilibrium equality for free energy differences, Phys. Rev. Lett. 78 (14) (1997) 2690-2693]) is often used for transitions between states described by an external parameter in the Hamiltonian. An extension to transitions between states defined by different values of some reaction coordinate is presented here, using a projected Brownian dynamics. In contrast with other approaches (see e.g. [S. Park, F. Khalili-Araghi, E. Tajkhorshid, K. Schulten, Free energy calculation from steered molecular dynamics simulations using Jarzynski's equality, J. Chem. Phys. 119 (6) (2003) 3559-3566]), a projection is used rather than a constraining potential to let the constraints associated with the reaction coordinate evolve. It is shown how to use the Lagrange multipliers associated with these constraints to compute the work associated with a given trajectory. Appropriate discretizations are proposed. Some numerical results demonstrate the applicability of the method for the computation of free energy difference profiles.

  13. Evaluation of the Effects of Different Energy Drinks and Coffee on Endothelial Function.

    PubMed

    Molnar, Janos; Somberg, John C

    2015-11-01

    Endothelial function plays an important role in circulatory physiology. There has been differing reports on the effect of energy drink on endothelial function. We set out to evaluate the effect of 3 energy drinks and coffee on endothelial function. Endothelial function was evaluated in healthy volunteers using a device that uses digital peripheral arterial tonometry measuring endothelial function as the reactive hyperemia index (RHI). Six volunteers (25 ± 7 years) received energy drink in a random order at least 2 days apart. Drinks studied were 250 ml "Red Bull" containing 80 mg caffeine, 57 ml "5-hour Energy" containing 230 mg caffeine, and a can of 355 ml "NOS" energy drink containing 120 mg caffeine. Sixteen volunteers (25 ± 5 years) received a cup of 473 ml coffee containing 240 mg caffeine. Studies were performed before drink (baseline) at 1.5 and 4 hours after drink. Two of the energy drinks (Red Bull and 5-hour Energy) significantly improved endothelial function at 4 hours after drink, whereas 1 energy drink (NOS) and coffee did not change endothelial function significantly. RHI increased by 82 ± 129% (p = 0.028) and 63 ± 37% (p = 0.027) after 5-hour Energy and Red Bull, respectively. The RHI changed after NOS by 2 ± 30% (p = 1.000) and by 7 ± 30% (p = 1.000) after coffee. In conclusion, some energy drinks appear to significantly improve endothelial function. Caffeine does not appear to be the component responsible for these differences.

  14. Deriving exact energy solutions to the symmetrized q-difference Harper equation.

    PubMed

    Papp, E; Micu, C

    2002-04-01

    This paper deals with the application of the q calculus to second order q-difference equations, like the q symmetrized form of the Harper equation. One obtains three-term recurrence relations, for which a symmetrized version is written down. This opens the way to establish explicit energy results that are dependent on the commensurability parameter. The continuous realization of such energy results exhibits interesting patterns characterized by hierarchical structures.

  15. Effects of nuclear cross sections at different energies on the radiation hazard from galactic cosmic rays.

    PubMed

    Lin, Z W; Adams, J H

    2007-03-01

    The radiation hazard for astronauts from galactic cosmic rays (GCR) is a major obstacle to long-duration human space exploration. Space radiation transport codes have been developed to calculate the radiation environment on missions to the Moon, Mars, and beyond. We have studied how uncertainties in fragmentation cross sections at different energies affect the accuracy of predictions from such radiation transport calculations. We find that, in deep space, cross sections at energies between 0.3 and 0.85 GeV/nucleon have the largest effect in solar maximum GCR environments. At the International Space Station, cross sections at higher energies have the largest effect due to the geomagnetic cutoff.

  16. Angular distributions of the quenched energy flow from dijets with different radius parameters in CMS

    NASA Astrophysics Data System (ADS)

    McGinn, Christopher F.

    2016-12-01

    The flow of the quenched energy in imbalanced dijet events has been previously studied by transverse vector sum of charged particles with the CMS detector, namely the missing pT measurement. The results have led to new theoretical insights to order to explain the wide angle radiation. The missing pT technique has been improved so that it allows the study of angular distribution of the energy flow with respect to the dijet axis. The measurements are performed using different distance parameters R with the anti-kT clustering algorithm, which provide information about how the angular distribution of the quenched energy depends on the jet width.

  17. Energy conversion method in the ocean using the density difference of water

    SciTech Connect

    Mochizuki, H.; Mitsuhashi, W.

    1981-01-01

    A new method which produces energy from the ocean by utilizing the density difference of water, by means of a ''chimney effect'', is proposed. Density difference of water in the ocean occurs in two ways, namely differences of consistency and water temperature. For instance, fresh river water and melting flows and icebergs are pointed out as some origins of the former, while thermal effects of volcanoes and hot springs may account for the latter. 5 refs.

  18. Analysis of temperature difference on the total of energy expenditure during static bicycle exercise

    NASA Astrophysics Data System (ADS)

    Sugiono

    2016-04-01

    How to manage energy expenditure for cyclist is very crucial part to achieve a good performance. As the tropical situation, the differences of temperature level might be contributed in energy expenditure and durability. The aim of the paper is to estimate and to analysis the configuration of energy expenditure for static cycling activity based on heart rate value in room with air conditioning (AC)/no AC treatment. The research is started with study literatures of climate factors, temperature impact on human body, and definition of energy expenditure. The next step is design the experiment for 5 participants in 2 difference models for 26.80C - 74% relative humidity (room no AC) and 23,80C - 54.8% relative humidity (room with AC). The participants’ heart rate and blood pressure are measured in rest condition and in cycling condition to know the impact of difference temperature in energy expenditure profile. According to the experiment results, the reducing of the temperature has significantly impact on the decreasing of energy expenditure at average 0.3 Kcal/minute for all 5 performers. Finally, the research shows that climate condition (temperature and relative humidity) are very important factors to manage and to reach a higher performance of cycling sport.

  19. Energy barrier at the N719-dye/CsSnI3 interface for photogenerated holes in dye-sensitized solar cells

    PubMed Central

    Zhang, Jin; Yu, Chunhui; Wang, Lili; Li, Yizhi; Ren, Yuhang; Shum, Kai

    2014-01-01

    This report is to address the question if black γ-polymorph of cesium tin tri-iodide (B-γ-CsSnI3) can be used as a solid-state hole-transport material in the conventional DSSCs with the N719 dye to replace the liquid electrolyte as reported by I. Chung et al. on Nature 485, 486, (2012). Here we demonstrate rigorously that B-γ-CsSnI3 is not energetically possible to collect photogenerated holes because of the large energy barrier at the interface of N719/B-γ-CsSnI3. Therefore, it cannot serve as a hole-transporter for the conventional DSSCs although it is a good hole-conducting material. A solution-based method was employed to synthesize the B-γ-CsSnI3 polycrystalline thin-films used for this work. These thin-films were then characterized by X-ray diffraction, Hall measurements, optical reflection, and photoluminescence (PL). Particularly, spatially resolved PL intensity images were taken after B-γ-CsSnI3 was incorporated in the DSSC structure to insure the material integrity. The means of ultraviolet photoemission spectroscopy (UPS) was used to reveal why B-γ-CsSnI3 could not act as the substitute of liquid electrolyte in the conventional DSSCs. For the completeness, other two related compounds, one is the yellow polymorph of CsSnI3 and other is Cs2SnI6 with tetravalent tin instead of double-valent tin in CsSnI3 were also investigated by UPS. PMID:25378076

  20. Large Energy Barrier and Magnetization Hysteresis at 5 K for a Symmetric {Dy2} Complex with Spherical Tricapped Trigonal Prismatic Dy(III) Ions.

    PubMed

    Mazarakioti, Eleni C; Regier, Jeffery; Cunha-Silva, Luís; Wernsdorfer, Wolfgang; Pilkington, Melanie; Tang, Jinkui; Stamatatos, Theocharis C

    2017-03-20

    The introduction of the Schiff base ligand N-salicylidene-2-amino-5-chlorobenzoic acid (sacbH2) in 4f-metal chemistry has afforded a new dinuclear complex, [Dy2(NO3)4(sacbH)2(H2O)2(MeCN)2] (1), with the metal ions adopting a rare spherical tricapped trigonal prismatic coordination geometry. The deprotonated phenoxido O atoms of the organic chelate occupy the axial triangular faces of the prism and were found to be very close to the main anisotropy axes of the two Dy(III) ions. As a result, the {Dy(III)2} compound exhibits frequency- and temperature-dependent out-of-phase ac signals below ∼25 K in the absence of a static dc field, yielding an energy barrier of 109.3(1) K for the reversal of magnetization. Fast and efficient quantum tunneling of magnetization, attributed to the strong tails of signals below ∼15 K, was suppressed through the application of a small dc field, yielding entirely visible χM″ signals below 27 K. Single-crystal magnetic hysteresis studies confirmed the single-molecule magnet (SMM) behavior of 1; the hysteresis loops appear at temperatures below ∼5 K, which is one of the highest blocking temperatures in the field of 4f-SMMs to date. This joint magneto-structural and ab initio study demonstrates the ability of more common coordination numbers (i.e., 9), but with rare coordination geometries (i.e., spherical tricapped trigonal prismatic), to promote axiality that enhances the molecular anisotropy and subsequently the magnetization dynamics of the system.

  1. Energy barrier at the N719-dye/CsSnI₃ interface for photogenerated holes in dye-sensitized solar cells.

    PubMed

    Zhang, Jin; Yu, Chunhui; Wang, Lili; Li, Yizhi; Ren, Yuhang; Shum, Kai

    2014-11-07

    This report is to address the question if black γ-polymorph of cesium tin tri-iodide (B-γ-CsSnI3) can be used as a solid-state hole-transport material in the conventional DSSCs with the N719 dye to replace the liquid electrolyte as reported by I. Chung et al. on Nature 485, 486, (2012). Here we demonstrate rigorously that B-γ-CsSnI3 is not energetically possible to collect photogenerated holes because of the large energy barrier at the interface of N719/B-γ-CsSnI3. Therefore, it cannot serve as a hole-transporter for the conventional DSSCs although it is a good hole-conducting material. A solution-based method was employed to synthesize the B-γ-CsSnI3 polycrystalline thin-films used for this work. These thin-films were then characterized by X-ray diffraction, Hall measurements, optical reflection, and photoluminescence (PL). Particularly, spatially resolved PL intensity images were taken after B-γ-CsSnI3 was incorporated in the DSSC structure to insure the material integrity. The means of ultraviolet photoemission spectroscopy (UPS) was used to reveal why B-γ-CsSnI3 could not act as the substitute of liquid electrolyte in the conventional DSSCs. For the completeness, other two related compounds, one is the yellow polymorph of CsSnI3 and other is Cs2SnI6 with tetravalent tin instead of double-valent tin in CsSnI3 were also investigated by UPS.

  2. Different Approaches for MØLLER'S Energy in the Kasner-Type Spacetime

    NASA Astrophysics Data System (ADS)

    Salti, Mustafa

    Considering the Møller energy definition in both Einstein's theory of general relativity and tele-parallel theory of gravity, we find the energy of the universe based on viscous Kasner-type metrics. The energy distribution which includes both the matter and gravitational field is found to be zero in both of these different gravitation theories and this result agrees with previous works of Cooperstock and Israelit et al., Banerjee-Sen, Vargas who investigated the problem of the energy in Friedmann-Robertson-Walker universe in Einstein's theory of general relativity and Aydogdu-Saltı who considered the same problem in tele-parallel gravity. In all of these works, they found that the energy of the Friedmann-Robertson-Walker spacetime is zero. Our result is the same as that obtained in the studies of Saltı and Havare. They used the viscous Kasner-type metric and found the total energy and momentum by using Bergmann-Thomson energy-momentum formulation in both general relativity and tele-parallel gravity. The result that the total energy and momentum components of the universe is zero supports the viewpoints of Albrow and Tryon.

  3. Barrier Formation

    PubMed Central

    Lyaruu, D.M.; Medina, J.F.; Sarvide, S.; Bervoets, T.J.M.; Everts, V.; DenBesten, P.; Smith, C.E.; Bronckers, A.L.J.J.

    2014-01-01

    Enamel fluorosis is an irreversible structural enamel defect following exposure to supraoptimal levels of fluoride during amelogenesis. We hypothesized that fluorosis is associated with excess release of protons during formation of hypermineralized lines in the mineralizing enamel matrix. We tested this concept by analyzing fluorotic enamel defects in wild-type mice and mice deficient in anion exchanger-2a,b (Ae2a,b), a transmembrane protein in maturation ameloblasts that exchanges extracellular Cl− for bicarbonate. Defects were more pronounced in fluorotic Ae2a,b−/− mice than in fluorotic heterozygous or wild-type mice. Phenotypes included a hypermineralized surface, extensive subsurface hypomineralization, and multiple hypermineralized lines in deeper enamel. Mineral content decreased in all fluoride-exposed and Ae2a,b−/− mice and was strongly correlated with Cl−. Exposure of enamel surfaces underlying maturation-stage ameloblasts to pH indicator dyes suggested the presence of diffusion barriers in fluorotic enamel. These results support the concept that fluoride stimulates hypermineralization at the mineralization front. This causes increased release of protons, which ameloblasts respond to by secreting more bicarbonates at the expense of Cl− levels in enamel. The fluoride-induced hypermineralized lines may form barriers that impede diffusion of proteins and mineral ions into the subsurface layers, thereby delaying biomineralization and causing retention of enamel matrix proteins. PMID:24170372

  4. Energy Impact of Different Penetrations of Connected and Automated Vehicles: A Preliminary Assessment

    SciTech Connect

    Rios-Torres, Jackeline; Malikopoulos, Andreas

    2016-01-01

    Previous research reported in the literature has shown the benefits of traffic coordination to alleviate congestion, and reduce fuel consumption and emissions. However, there are still many remaining challenges that need to be addressed before a massive deployment of fully automated vehicles. This paper aims to investigate the energy impacts of different penetration rates of connected and automated vehicles (CAVs) and their interaction with human-driven vehicles. We develop a simulation framework for mixed traffic (CAVs interacting with human-driven vehicles) in merging roadways and analyze the energy impact of different penetration rates of CAVs on the energy consumption. The Gipps car following model is used along with heuristic controls to represent the driver decisions in a merging roadways traffic scenario. Using different penetration rates of CAVs, the simulation results indicated that for low penetration rates, the fuel consumption benefits are significant but the total travel time increases. The benefits in travel time are noticeable for higher penetration rates of CAVs.

  5. Regional Differences in the Price-Elasticity of Demand for Energy

    SciTech Connect

    Bernstein, M. A.; Griffin, J.

    2006-02-01

    At the request of the National Renewable Energy Laboratory (NREL), the RAND Corporation examined the relationship between energy demand and energy prices with the focus on whether the relationships between demand and price differ if these are examined at different levels of data resolution. In this case, RAND compares national, regional, state, and electric utility levels of data resolution. This study is intended as a first step in helping NREL understand the impact that spatial disaggregation of data can have on estimating the impacts of their programs. This report should be useful to analysts in NREL and other national laboratories, as well as to policy nationals at the national level. It may help them understand the complex relationships between demand and price and how these might vary across different locations in the United States.

  6. Computing converged free energy differences between levels of theory via nonequilibrium work methods: Challenges and opportunities.

    PubMed

    Kearns, Fiona L; Hudson, Phillip S; Woodcock, Henry L; Boresch, Stefan

    2017-03-08

    We demonstrate that Jarzynski's equation can be used to reliably compute free energy differences between low and high level representations of systems. The need for such a calculation arises when employing the so-called "indirect" approach to free energy simulations with mixed quantum mechanical/molecular mechanical (QM/MM) Hamiltonians; a popular technique for circumventing extensive simulations involving quantum chemical computations. We have applied this methodology to several small and medium sized organic molecules, both in the gas phase and explicit solvent. Test cases include several systems for which the standard approach; that is, free energy perturbation between low and high level description, fails to converge. Finally, we identify three major areas in which the difference between low and high level representations make the calculation of ΔAlow→high difficult: bond stretching and angle bending, different preferred conformations, and the response of the MM region to the charge distribution of the QM region. © 2016 Wiley Periodicals, Inc.

  7. Sound barriers from materials of inhomogeneous impedance.

    PubMed

    Wang, Xu; Mao, Dongxing; Yu, Wuzhou; Jiang, Zaixiu

    2015-06-01

    Sound barriers are extensively used in environmental noise protection. However, when barriers are placed in parallel on opposite sides of a sound source, their performance deteriorates markedly. This paper describes a barrier made from materials of inhomogeneous impedance which lacks this drawback. The nonuniform impedance affects the way sound undergoes multiple reflections, and in the process traps acoustic energy. A proposed realization of the barrier comprises a closely spaced array of progressively tuned hollow narrow tubes which create a phase gradient. The acoustics of the barrier is theoretically examined and its superiority over conventional barriers is calculated using finite element modeling. Structural parameters of the barrier can be changed to achieve the required sound insertion loss, and the barrier has the potential to be widely used in environmental noise control.

  8. Comparing the health impacts of different sources of energy. Keynote address

    SciTech Connect

    Hamilton, L.D.

    1981-01-01

    Assessing health impacts of different energy sources requires synthesis of research results from any different disciplines into a rational framework. Information is often scanty; qualitatively different risks, or energy systems with substantially different end uses, must be put on a common footing. Historically institutional constraints have inhibited agencies from making incisive comparisons necessary for formulating energy policy; this has exacerbated public controversy over appropriate energy sources. Risk assessment methods reviewed include examples drawn from work of the Biomedical and Environmental Assessment Division at Brookhaven National Laboratory and elsewhere. Uncertainty over the mechanism and size of air pollution health damage is addressed through a probabilistic health-damage function, using sulfate-particle exposure as an indicator. This facilitates intercomparison through analysis of each step in the whole fuel cycle between a typical coal and nuclear powerplant. Occupational health impacts, a significant fraction of overall damage, are illustrated by accident trends in coal mining. In broadening comparisons to include new technologies, one must include the impact of manufacturing the energy-producing device as part of an expanded fuel cycle, via input/output methods. Throughout the analysis, uncertainties must be made explicit in the results, including uncertainty of data and uncertainty in choice of appropriate models and methods. No single method of comparative risk assessment is fully satisfactory; each has its limitations. One needs to compare several methods if decision-making is to be realistic.

  9. A parametric study of the thermal performance of green roofs in different climates through energy modeling

    NASA Astrophysics Data System (ADS)

    Mukherjee, Sananda

    In recent years, there has been great interest in the potential of green roofs as an alternative roofing option to reduce the energy consumed by individual buildings as well as mitigate large scale urban environmental problems such as the heat island effect. There is a widespread recognition and a growing literature of measured data that suggest green roofs can reduce building energy consumption. This thesis investigates the potential of green roofs in reducing the building energy loads and focuses on how the different parameters of a green roof assembly affect the thermal performance of a building. A green roof assembly is modeled in Design Builder- a 3D graphical design modeling and energy use simulation program (interface) that uses the EnergyPlus simulation engine, and the simulated data set thus obtained is compared to field experiment data to validate the roof assembly model on the basis of how accurately it simulates the behavior of a green roof. Then the software is used to evaluate the thermal performance of several green roof assemblies under three different climate types, looking at the whole building energy consumption. For the purpose of this parametric simulation study, a prototypical single story small office building is considered and one parameter of the green roof is altered for each simulation run in order to understand its effect on building's energy loads. These parameters include different insulation thicknesses, leaf area indices (LAI) and growing medium or soil depth, each of which are tested under the three different climate types. The energy use intensities (EUIs), the peak and annual heating and cooling loads resulting from the use of these green roof assemblies are compared with each other and to a cool roof base case to determine the energy load reductions, if any. The heat flux through the roof is also evaluated and compared. The simulation results are then organized and finally presented as a decision support tool that would

  10. Coulomb Energy Differences in T = 1 Mirror Rotational Bands in 50Fe and 50Cr

    NASA Astrophysics Data System (ADS)

    Lenzi, S. M.; Mărginean, N.; Napoli, D. R.; Ur, C. A.; Zuker, A. P.; de Angelis, G.; Algora, A.; Axiotis, M.; Bazzacco, D.; Belcari, N.; Bentley, M. A.; Bizzeti, P. G.; Bizzeti-Sona, A.; Brandolini, F.; von Brentano, P.; Bucurescu, D.; Cameron, J. A.; Chandler, C.; de Poli, M.; Dewald, A.; Eberth, H.; Farnea, E.; Gadea, A.; Garces-Narro, J.; Gelletly, W.; Grawe, H.; Isocrate, R.; Joss, D. T.; Kalfas, C. A.; Klug, T.; Lampman, T.; Lunardi, S.; Martínez, T.; Martínez-Pinedo, G.; Menegazzo, R.; Nyberg, J.; Podolyak, Zs.; Poves, A.; Ribas, R. V.; Rossi Alvarez, C.; Rubio, B.; Sánchez-Solano, J.; Spolaore, P.; Steinhardt, T.; Thelen, O.; Tonev, D.; Vitturi, A.; von Oertzen, W.; Weiszflog, M.

    2001-09-01

    Gamma rays from the N = Z-2 nucleus 50Fe have been observed, establishing the rotational ground state band up to the state Jπ = 11+ at 6.994 MeV excitation energy. The experimental Coulomb energy differences, obtained by comparison with the isobaric analog states in its mirror 50Cr, confirm the qualitative interpretation of the backbending patterns in terms of successive alignments of proton and neutron pairs. A quantitative agreement with experiment has been achieved by exact shell model calculations, incorporating the differences in radii along the yrast bands, and properly renormalizing the Coulomb matrix elements in the pf model space.

  11. Barrier infrared detector

    NASA Technical Reports Server (NTRS)

    Ting, David Z. (Inventor); Khoshakhlagh, Arezou (Inventor); Soibel, Alexander (Inventor); Hill, Cory J. (Inventor); Gunapala, Sarath D. (Inventor)

    2012-01-01

    A superlattice-based infrared absorber and the matching electron-blocking and hole-blocking unipolar barriers, absorbers and barriers with graded band gaps, high-performance infrared detectors, and methods of manufacturing such devices are provided herein. The infrared absorber material is made from a superlattice (periodic structure) where each period consists of two or more layers of InAs, InSb, InSbAs, or InGaAs. The layer widths and alloy compositions are chosen to yield the desired energy band gap, absorption strength, and strain balance for the particular application. Furthermore, the periodicity of the superlattice can be "chirped" (varied) to create a material with a graded or varying energy band gap. The superlattice based barrier infrared detectors described and demonstrated herein have spectral ranges covering the entire 3-5 micron atmospheric transmission window, excellent dark current characteristics operating at least 150K, high yield, and have the potential for high-operability, high-uniformity focal plane arrays.

  12. Gold(I)-catalyzed Claisen rearrangement of allenyl vinyl ethers: missing transition states revealed through evolution of aromaticity, Au(I) as an oxophilic Lewis acid, and lower energy barriers from a high energy complex.

    PubMed

    Vidhani, Dinesh V; Cran, John W; Krafft, Marie E; Manoharan, Mariappan; Alabugin, Igor V

    2013-03-01

    Curtin-Hammett analysis of four alternative mechanisms of the gold(I)-catalyzed [3,3] sigmatropic rearrangement of allenyl vinyl ethers by density functional theory calculations reveals that the lowest energy pathway (cation-accelerated oxonia Claisen rearrangement) originates from the second most stable of the four Au(I)-substrate complexes in which gold(I) coordinates to the lone pair of oxygen. This pathway proceeds via a dissociative transition state where the C-O bond cleavage precedes C1-C6 bond formation. The alternative Au(I) coordination at the vinyl π-system produces a more stable but less reactive complex. The two least stable modes of coordination at the allenyl π-system display reactivity that is intermediate between that of the Au(I)-oxygen and the Au(I)-vinyl ether complexes. The unusual electronic features of the four potential energy surfaces (PESs) associated with the four possible mechanisms were probed with intrinsic reaction coordinate calculations in conjunction with nucleus independent chemical shift (NICS(0)) evaluation of aromaticity of the transient structures. The development of aromatic character along the "6-endo" reaction path is modulated via Au-complexation to the extent where both the cyclic intermediate and the associated fragmentation transition state do not correspond to stationary points at the reaction potential energy surface. This analysis explains why the calculated PES for cyclization promoted by coordination of gold(I) to allenyl moiety lacks a discernible intermediate despite proceeding via a highly asynchronous transition state with characteristics of a stepwise "cyclization-mediated" process. Although reaction barriers can be strongly modified by aryl substituents of varying electronic demand, direct comparison of experimental and computational substituent effects is complicated by formation of Au-complexes with the Lewis-basic sites of the substrates.

  13. Transfer vs. Breakup in the interaction of the 7Be Radioactive Ion Beam with a 58Ni target at Coulomb barrier energies

    NASA Astrophysics Data System (ADS)

    Mazzocco, M.; Torresi, D.; Acosta, L.; Boiano, A.; Boiano, C.; Fierro, N.; Glodariu, T.; Guglielmetti, A.; Keeley, N.; La Commara, M.; Martel, I.; Mazzocchi, C.; Molini, P.; Pakou, A.; Parascandolo, C.; Parkar, V. V.; Patronis, N.; Pierroutsakou, D.; Romoli, M.; Rusek, K.; Sanchez-Benitez, A. M.; Sandoli, M.; Signorini, C.; Silvestri, R.; Soramel, F.; Stiliaris, E.; Strano, E.; Stroe, L.; Zerva, K.

    2014-03-01

    We measured for the first time 7Be elastically scattered nuclei as well as 3,4He reaction products from a 58Ni target at 22.3 MeV beam energy. The data were analyzed within the optical model formalism to extract the total reaction cross section. Extensive kinematical, Distorted Wave Born Approximation (DWBA)and Continuum Discretized Coupled Channel (CDCC) calculations were performed to investigate the 3,4He originating mechanisms and the interplay between different reaction channels.

  14. Circularly polarized antennas for active holographic imaging through barriers

    SciTech Connect

    McMakin, Douglas L; Severtsen, Ronald H; Lechelt, Wayne M; Prince, James M

    2011-07-26

    Circularly-polarized antennas and their methods of use for active holographic imaging through barriers. The antennas are dielectrically loaded to optimally match the dielectric constant of the barrier through which images are to be produced. The dielectric loading helps to remove barrier-front surface reflections and to couple electromagnetic energy into the barrier.

  15. Comparative dosimetric characterization for different types of detectors in high-energy electron beams

    NASA Astrophysics Data System (ADS)

    Lee, Chang Yeol; Kim, Woo Chul; Kim, Hun Jeong; Huh, Hyun Do; Park, Seungwoo; Choi, Sang Hyoun; Kim, Kum Bae; Min, Chul Kee; Kim, Seong Hoon; Shin, Dong Oh

    2017-02-01

    The purpose of this study is to perform a comparison and on analysis of measured dose factor values by using various commercially available high-energy electron beam detectors to measure dose profiles and energy property data. By analyzing the high-energy electron beam data from each detector, we determined the optimal detector for measuring electron beams in clinical applications. The dose linearity, dose-rate dependence, percentage depth dose, and dose profile of each detector were measured to evaluate the dosimetry characteristics of high-energy electron beams. The dose profile and the energy characteristics of high-energy electron beams were found to be different when measured by different detectors. Through comparison with other detectors based on the analyzed data, the microdiamond detector was found to have outstanding dose linearity, a low dose-rate dependency, and a small effective volume. Thus, this detector has outstanding spatial resolution and is the optimal detector for measuring electron beams. Radiation therapy results can be improved and related medical accidents can be prevented by using the procedure developed in this research in clinical practice for all beam detectors when measuring the electron beam dose.

  16. Static versus energy-dependent nucleus-nucleus potential for description of sub-barrier fusion dynamics of {}_{8}^{16}O+{}^{112,116,120}\\!\\!\\!\\!\\!\\!{}_{50}Sn reactions

    NASA Astrophysics Data System (ADS)

    Manjeet Singh, Gautam

    2015-11-01

    The static and energy-dependent nucleus-nucleus potentials are simultaneously used along with the Wong formula for exploration of fusion dynamics of {}816O+{}112,116,120{}50Sn reactions. The role of internal structure degrees of freedom of colliding pairs, such as inelastic surface vibrations, are examined within the context of coupled channel calculations performed using the code CCFULL. Theoretical calculations based on the static Woods-Saxon potential along with the one-dimensional Wong formula fail to address the fusion data of {}816O+{}112,116,120{}50Sn reactions. Such discrepancies can be removed if one uses couplings to internal structure degrees of freedom of colliding nuclei. However, the energy-dependent Woods-Saxon potential model (EDWSP model) accurately describes the sub-barrier fusion enhancement of {}816O+{}112,116,120{}50Sn reactions. Therefore, in sub-barrier fusion dynamics, energy dependence in the nucleus-nucleus potential governs barrier modification effects in a closely similar way to that of the coupled channel approach. Supported by Dr. D. S. Kothari Post-Doctoral Fellowship Scheme sponsored by University Grants Commission (UGC), New Delhi, India

  17. Prevalence of energy intake misreporting in Malay children varies based on application of different cut points.

    PubMed

    Yang, Wai Yew; Burrows, Tracy; Collins, Clare E; MacDonald-Wicks, Lesley; Williams, Lauren T; Chee, Winnie Siew Swee

    2014-12-01

    This study aimed to identify the prevalence of energy misreporting amongst a sample of Malay children aged 9-11 years (n = 14) using a range of commonly used cut points. Participants were interviewed using repeated 24 h dietary recalls over three occasions. The Goldberg equations (1991 and 2000), Torun cut points and the Black and Cole method were applied to the data. Up to 11 of 14 children were classified as misreporters, with more under-reporters (between seven and eight children) than over-reporters (four or less children). There were significant differences in the proportion of children classified as energy misreporters when applying basal metabolic rate calculated using FAO/UNU/WHO (1985) and Malaysian-specific equations (p < 0.05). The results show that energy misreporting is common amongst Malay children, varying according to cut point chosen. Objective evaluation of total energy expenditure would help identify which cut point is appropriate for use in Malay paediatric populations.

  18. Evaluation of the mutagenic potential of different forms of energy production.

    PubMed

    Léonard, A; Léonard, E D

    1983-08-01

    The consequence of exposure to the effluents of power plants that elicits the most concern is probably the induction of cancers. Due mainly to the high uncertainty of epidemiological surveys on exposure to low doses of mutagens, observations performed up to now on man have provided contradictory and inconclusive results. Since a high correlation exists between the mutagenicity of environmental agents and their carcinogenic properties, an attempt has been made to evaluate the carcinogenic potential of the different forms of energy production on the basis of the results of short term tests performed on the effluents of several power plants. Any energy source is associated with such risks and, in spite of the fact that real comparative studies were not available, coal as a source of energy presents obviously higher mutagenic potential than nuclear power. Renewable forms of energy are cleaner but are, however, not entirely devoid of health impacts.

  19. Estimation of free-energy differences from computed work distributions: an application of Jarzynski's equality.

    PubMed

    Echeverria, Ignacia; Amzel, L Mario

    2012-09-13

    Equilibrium free-energy differences can be computed from nonequilibrium molecular dynamics (MD) simulations using Jarzynski's equality (Jarzynski, C. Phys. Rev. Lett.1997, 78, 2690) by combining a large set of independent trajectories (path ensemble). Here we present the multistep trajectory combination (MSTC) method to compute free-energy differences, which by combining trajectories significantly reduces the number of trajectories necessary to generate a representative path ensemble. This method generates well-sampled work distributions, even for large systems, by combining parts of a relatively small number of trajectories carried out in steps. To assess the efficiency of the MSTC method, we derived analytical expressions and used them to compute the bias and the variance of the free-energy estimates along with numerically calculated values. We show that the MSTC method significantly reduces both the bias and variance of the free-energy estimates compared to the estimates obtained using single-step trajectories. In addition, because in the MSTC method the process is divided into steps, it is feasible to compute the reverse transition. By combining the forward and reverse processes, the free-energy difference can be computed using the Crooks' fluctuation theorem (Crooks, G. E. J. Stat. Phys.1998, 90, 1481 and Crooks, G. E. Phys. Rev. E 2000, 61, 2361) or Bennett's acceptance ratio (Bennett, C. H. J. Comput. Phys. 1976, 22, 245), which further reduces the bias and variance of the estimates.

  20. Difference in Energy Metabolism of Annulus Fibrosus and Nucleus Pulposus Cells of the Intervertebral Disc