Differential and directional effects of perfusion on electrical and thermal conductivities in liver.

Science.gov (United States)

Podhajsky, Ronald J; Yi, Ming; Mahajan, Roop L

2009-01-01

Two different measurement probes--an electrical probe and a thermal conductivity probe--were designed, fabricated, calibrated, and used in experimental studies on a pig liver model that was designed to control perfusion rates. These probes were fabricated by photolithography and mounted in 1.5-mm diameter catheters. We measured the local impedance and thermal conductivity, respectively, of the artificially perfused liver at different flow rates and, by rotating the probes, in different directions. The results show that both the local electrical conductivity and the thermal conductivity varied location to location, that thermal conductivity increased with decreased distance to large blood vessels, and that significant directional differences exist in both electrical and thermal conductivities. Measurements at different perfusion rates demonstrated that both the local electrical and local thermal conductivities increased linearly with the square root of perfusion rate. These correlations may be of great value to many energy-based biomedical applications.

The Interplay Between the Unfair Commercial Practices Directive and Codes of Conduct

NARCIS (Netherlands)

Charlotte Pavillon (C.M.D.S.)

2013-01-01

markdownabstract__Abstract__ At the heart of this paper lies the reciprocal influence between codes of conduct and the Unfair Commercial Practices Directive (UCPD). It assesses to what extent self-regulatory practice both affects and is affected by the directive. The codes' contribution to

Higher-resolution selective metallization on alumina substrate by laser direct writing and electroless plating

Science.gov (United States)

Lv, Ming; Liu, Jianguo; Wang, Suhuan; Ai, Jun; Zeng, Xiaoyan

2016-03-01

How to fabricate conductive patterns on ceramic boards with higher resolution is a challenge in the past years. The fabrication of copper patterns on alumina substrate by laser direct writing and electroless copper plating is a low cost and high efficiency method. Nevertheless, the lower resolution limits its further industrial applications in many fields. In this report, the mechanisms of laser direct writing and electroless copper plating were studied. The results indicated that as the decomposed products of precursor PdCl2 have different chemical states respectively in laser-irradiated zone (LIZ) and laser-affected zone (LAZ). This phenomenon was utilized and a special chemical cleaning method with aqua regia solution was taken to selectively remove the metallic Pd in LAZ, while kept the PdO in LIZ as the only active seeds. As a result, the resolution of subsequent copper patterns was improved significantly. This technique has a great significance to develop the microelectronics devices.

Development of a direct push based in-situ thermal conductivity measurement system

Science.gov (United States)

Chirla, Marian Andrei; Vienken, Thomas; Dietrich, Peter; Bumberger, Jan

2016-04-01

Heat pump systems are commonly utilized in Europe, for the exploitation of the shallow geothermal potential. To guarantee a sustainable use of the geothermal heat pump systems by saving resources and minimizing potential negative impacts induced by temperature changes within soil and groundwater, new geothermal exploration methods and tools are required. The knowledge of the underground thermal properties is a necessity for a correct and optimum design of borehole heat exchangers. The most important parameter that indicates the performance of the systems is thermal conductivity of the ground. Mapping the spatial variability of thermal conductivity, with high resolution in the shallow subsurface for geothermal purposes, requires a high degree of technical effort to procure adequate samples for thermal analysis. A collection of such samples from the soil can disturb sample structure, so great care must be taken during collection to avoid this. Factors such as transportation and sample storage can also influence measurement results. The use of technologies like Thermal Response Test (TRT) require complex mechanical and electrical systems for convective heat transport in the subsurface and longer monitoring times, often three days. Finally, by using thermal response tests, often only one integral value is obtained for the entire coupled subsurface with the borehole heat exchanger. The common thermal conductivity measurement systems (thermal analyzers) can perform vertical thermal conductivity logs only with the aid of sample procurement, or by integration into a drilling system. However, thermal conductivity measurements using direct push with this type of probes are not possible, due to physical and mechanical limitations. Applying vertical forces using direct push technology, in order to penetrate the shallow subsurface, can damage the probe and the sensors systems. The aim of this study is to develop a new, robust thermal conductivity measurement probe, for direct

Proton conductive montmorillonite-Nafion composite membranes for direct ethanol fuel cells

International Nuclear Information System (INIS)

Wu, Xiu-Wen; Wu, Nan; Shi, Chun-Qing; Zheng, Zhi-Yuan; Qi, Hong-Bin; Wang, Ya-Fang

2016-01-01

Highlights: • Composite membranes are prepared with different montmorillonites and nafion solution. • Proton conductivities of the composite membranes are between 36.0 mS/cm and 38.5 mS/cm. • Ethanol permeability is between 0.69 × 10"−"6 cm"2/s and 2.67 × 10"−"6 cm"2/s. • Water uptake is approximately 24.30 mass%. - Abstract: The preparation of Nafion membranes modified with montmorillonites is less studied, and most relative works mainly applied in direct methanol fuel cells, less in direct ethanol fuel cells. Organic/inorganic composite membranes are prepared with different montmorillonites (Ca-montmorillonite, Na-montmorillonite, K-montmorillonite, Mg-montmorillonite, and H-montmorillonite) and Nafion solution via casting method at 293 K in air, and with balance of their proton conductivity and ethanol permeability. The ethanol permeability and proton conductivity of the membranes are comparatively studied. The montmorillonites can well decrease the ethanol permeability of the membranes via inserted them in the membranes, while less decrease the proton conductivities of the membranes depending on the inserted amount and type of montmorillonites. The proton conductivities of the membranes are between 36.0 mS/cm and 38.5 mS/cm. The ethanol permeability of the membranes is between 0.69 × 10"−"6 cm"2/s and 2.67 × 10"−"6 cm"2/s.

Direct measurement of thermal conductivity in solid iron at planetary core conditions.

Science.gov (United States)

Konôpková, Zuzana; McWilliams, R Stewart; Gómez-Pérez, Natalia; Goncharov, Alexander F

2016-06-02

The conduction of heat through minerals and melts at extreme pressures and temperatures is of central importance to the evolution and dynamics of planets. In the cooling Earth's core, the thermal conductivity of iron alloys defines the adiabatic heat flux and therefore the thermal and compositional energy available to support the production of Earth's magnetic field via dynamo action. Attempts to describe thermal transport in Earth's core have been problematic, with predictions of high thermal conductivity at odds with traditional geophysical models and direct evidence for a primordial magnetic field in the rock record. Measurements of core heat transport are needed to resolve this difference. Here we present direct measurements of the thermal conductivity of solid iron at pressure and temperature conditions relevant to the cores of Mercury-sized to Earth-sized planets, using a dynamically laser-heated diamond-anvil cell. Our measurements place the thermal conductivity of Earth's core near the low end of previous estimates, at 18-44 watts per metre per kelvin. The result is in agreement with palaeomagnetic measurements indicating that Earth's geodynamo has persisted since the beginning of Earth's history, and allows for a solid inner core as old as the dynamo.

Study on the Electric Conductivity of Ag-Doped DNA in Transverse Direction

Directory of Open Access Journals (Sweden)

Ban Ge

2009-01-01

Full Text Available Abstract In this article, we reported a novel experiment results on Ag-doped DNA conductor in transverse direction.I–Vcharacteristics were measured and the relative conductances were calculated for different silver ions concentrations. With the increase of the concentration of silver ions, the conductive ability of DNA risen rapidly, the relative conductance of DNA enhanced about three magnitudes and reached a stable value when Ag+concentration was up to 0.005 mM. In addition, Raman spectra were carried out to analyse and confirm conduction mechanism.

Considerations of the Effects of Naphthalene Moieties on the Design of Proton-Conductive Poly(arylene ether ketone) Membranes for Direct Methanol Fuel Cells.

Science.gov (United States)

Wang, Baolong; Hong, Lihua; Li, Yunfeng; Zhao, Liang; Wei, Yuxue; Zhao, Chengji; Na, Hui

2016-09-14

Novel sulfonated poly(arylene ether ketones) (SDN-PAEK-x), consisting of dual naphthalene and flexible sulfoalkyl groups, were prepared via polycondensation, demethylation, and sulfobutylation grafting reaction. Among them, SDN-PAEK-1.94 membrane with the highest ion exchange capacity (IEC = 2.46 mequiv·g(-1)) exhibited the highest proton conductivity, which was 0.147 S· cm(-1) at 25 °C and 0.271 S·cm(-1) at 80 °C, respectively. The introduction of dual naphthalene moieties is expected to achieve much enhanced properties compared to those of sulfonated poly(arylene ether ketones) (SNPAEK-x), consisting of single naphthalene and flexible sulfoalkyl groups. Compared with SNPAEK-1.60 with a similar IEC, SDN-PAEK-1.74 membrane showed higher proton conductivity, higher IEC normalized conductivity, and higher effective proton mobility, although it had lower analytical acid concentration. The SDN-PAEK-x membranes with IECs higher than 1.96 mequiv·g(-1) also exhibited higher proton conductivity than that of recast Nafion membrane. Furthermore, SDN-PAEK-1.94 displayed a better single cell performance with a maximum power density of 60 mW·cm(-2) at 80 °C. Considering its high proton conductivity, excellent single cell performance, good mechanical stabilities, low membrane swelling, and methanol permeability, SDN-PAEK-x membranes are promising candidates as alternative polymer electrolyte membranes to Nafion for direct methanol fuel cell applications.

Proton conductive montmorillonite-Nafion composite membranes for direct ethanol fuel cells

Energy Technology Data Exchange (ETDEWEB)

Wu, Xiu-Wen, E-mail: wuxw2008@163.com [School of Science, China University of Geosciences, Beijing 100083 (China); National Laboratory of Mineral Materials, China University of Geosciences, Beijing 100083 (China); Wu, Nan; Shi, Chun-Qing; Zheng, Zhi-Yuan; Qi, Hong-Bin; Wang, Ya-Fang [School of Science, China University of Geosciences, Beijing 100083 (China)

2016-12-01

Highlights: • Composite membranes are prepared with different montmorillonites and nafion solution. • Proton conductivities of the composite membranes are between 36.0 mS/cm and 38.5 mS/cm. • Ethanol permeability is between 0.69 × 10{sup −6} cm{sup 2}/s and 2.67 × 10{sup −6} cm{sup 2}/s. • Water uptake is approximately 24.30 mass%. - Abstract: The preparation of Nafion membranes modified with montmorillonites is less studied, and most relative works mainly applied in direct methanol fuel cells, less in direct ethanol fuel cells. Organic/inorganic composite membranes are prepared with different montmorillonites (Ca-montmorillonite, Na-montmorillonite, K-montmorillonite, Mg-montmorillonite, and H-montmorillonite) and Nafion solution via casting method at 293 K in air, and with balance of their proton conductivity and ethanol permeability. The ethanol permeability and proton conductivity of the membranes are comparatively studied. The montmorillonites can well decrease the ethanol permeability of the membranes via inserted them in the membranes, while less decrease the proton conductivities of the membranes depending on the inserted amount and type of montmorillonites. The proton conductivities of the membranes are between 36.0 mS/cm and 38.5 mS/cm. The ethanol permeability of the membranes is between 0.69 × 10{sup −6} cm{sup 2}/s and 2.67 × 10{sup −6} cm{sup 2}/s.

Direct numerical reconstruction of conductivities in three dimensions using scattering transforms

DEFF Research Database (Denmark)

Bikowski, Jutta; Knudsen, Kim; Mueller, Jennifer L

2011-01-01

A direct three-dimensional EIT reconstruction algorithm based on complex geometrical optics solutions and a nonlinear scattering transform is presented and implemented for spherically symmetric conductivity distributions. The scattering transform is computed both with a Born approximation and from...

Direct measurement of surface-state conductance by microscopic four-point probe method

DEFF Research Database (Denmark)

Hasegawa, S.; Shiraki, I.; Tanikawa, T.

2002-01-01

For in situ measurements of local electrical conductivity of well defined crystal surfaces in ultrahigh vacuum, we have developed microscopic four-point probes with a probe spacing of several micrometres, installed in a scanning-electron - microscope/electron-diffraction chamber. The probe...... is precisely positioned on targeted areas of the sample surface by using piezoactuators. This apparatus enables conductivity measurement with extremely high surface sensitivity, resulting in direct access to surface-state conductivity of the surface superstructures, and clarifying the influence of atomic steps...

Anisotropic conductivity tensor imaging in MREIT using directional diffusion rate of water molecules

International Nuclear Information System (INIS)

Kwon, Oh In; Jeong, Woo Chul; Sajib, Saurav Z K; Kim, Hyung Joong; Woo, Eung Je

2014-01-01

Magnetic resonance electrical impedance tomography (MREIT) is an emerging method to visualize electrical conductivity and/or current density images at low frequencies (below 1 KHz). Injecting currents into an imaging object, one component of the induced magnetic flux density is acquired using an MRI scanner for isotropic conductivity image reconstructions. Diffusion tensor MRI (DT-MRI) measures the intrinsic three-dimensional diffusion property of water molecules within a tissue. It characterizes the anisotropic water transport by the effective diffusion tensor. Combining the DT-MRI and MREIT techniques, we propose a novel direct method for absolute conductivity tensor image reconstructions based on a linear relationship between the water diffusion tensor and the electrical conductivity tensor. We first recover the projected current density, which is the best approximation of the internal current density one can obtain from the measured single component of the induced magnetic flux density. This enables us to estimate a scale factor between the diffusion tensor and the conductivity tensor. Combining these values at all pixels with the acquired diffusion tensor map, we can quantitatively recover the anisotropic conductivity tensor map. From numerical simulations and experimental verifications using a biological tissue phantom, we found that the new method overcomes the limitations of each method and successfully reconstructs both the direction and magnitude of the conductivity tensor for both the anisotropic and isotropic regions. (paper)

Steady-state properties of Josephson junctions with direct conductivity

International Nuclear Information System (INIS)

Zubkov, A.A.; Kupriyanov, M.Y.; Semenov, V.K.

1981-01-01

A new criterion for determining the kinetic inductance of Josephson junctions is introduced. The effects of temperature T, the critical temperatures of the superconducting electrodes T/sub c/1 and T/sub c/2, and the weak-link length on the kinetic inductance of ''dirty'' junctions with direct conductivity are analyzed within the framework of the Usadel equations. Numerical calculations show that both a large characteristic voltage and a nearly harmonic dependence of the current on the phase difference of the superconducting-electrode wave functions cannot be obtained by varying the junction parameters

Higher direct bilirubin levels during mid-pregnancy are associated with lower risk of gestational diabetes mellitus.

Science.gov (United States)

Liu, Chaoqun; Zhong, Chunrong; Zhou, Xuezhen; Chen, Renjuan; Wu, Jiangyue; Wang, Weiye; Li, Xiating; Ding, Huisi; Guo, Yanfang; Gao, Qin; Hu, Xingwen; Xiong, Guoping; Yang, Xuefeng; Hao, Liping; Xiao, Mei; Yang, Nianhong

2017-01-01

Bilirubin concentrations have been recently reported to be negatively associated with type 2 diabetes mellitus. We examined the association between bilirubin concentrations and gestational diabetes mellitus. In a prospective cohort study, 2969 pregnant women were recruited prior to 16 weeks of gestation and were followed up until delivery. The value of bilirubin was tested and oral glucose tolerance test was conducted to screen gestational diabetes mellitus. The relationship between serum bilirubin concentration and gestational weeks was studied by two-piecewise linear regression. A subsample of 1135 participants with serum bilirubin test during 16-18 weeks gestation was conducted to research the association between serum bilirubin levels and risk of gestational diabetes mellitus by logistic regression. Gestational diabetes mellitus developed in 8.5 % of the participants (223 of 2969). Two-piecewise linear regression analyses demonstrated that the levels of bilirubin decreased with gestational week up to the turning point 23 and after that point, levels of bilirubin were increased slightly. In multiple logistic regression analysis, the relative risk of developing gestational diabetes mellitus was lower in the highest tertile of direct bilirubin than that in the lowest tertile (RR 0.60; 95 % CI, 0.35-0.89). The results suggested that women with higher serum direct bilirubin levels during the second trimester of pregnancy have lower risk for development of gestational diabetes mellitus.

Effects of an applied voltage on direct interspecies electron transfer via conductive materials for methane production.

Science.gov (United States)

Lee, Jung-Yeol; Park, Jeong-Hoon; Park, Hee-Deung

2017-10-01

Direct interspecies electron transfer (DIET) between exoelectrogenic bacteria and methanogenic archaea via conductive materials is reported as an efficient method to produce methane in anaerobic organic waste digestion. A voltage can be applied to the conductive materials to accelerate the DIET between two groups of microorganisms to produce methane. To evaluate this hypothesis, two sets of anaerobic serum bottles with and without applied voltage were used with a pair of graphite rods as conductive materials to facilitate DIET. Initially, the methane production rate was similar between the two sets of serum bottles, and later the serum bottles with an applied voltage of 0.39V showed a 168% higher methane production rate than serum bottles without an applied voltage. In cyclic voltammograms, the characteristic redox peaks for hydrogen and acetate oxidation were identified in the serum bottles with an applied voltage. In the microbial community analyses, hydrogenotrophic methanogens (e.g. Methanobacterium) were observed to be abundant in serum bottles with an applied voltage, while methanogens utilizing carbon dioxide (e.g., Methanosaeta and Methanosarcina) were dominant in serum bottles without an applied voltage. Taken together, the applied voltage on conductive materials might not be effective to promote DIET in methane production. Instead, it appeared to generate a condition for hydrogenotrophic methanogenesis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Direct numerical simulation of MHD flow with electrically conducting wall

International Nuclear Information System (INIS)

Satake, S.; Kunugi, T.; Naito, N.; Sagara, A.

2006-01-01

The 2D vortex problem and 3D turbulent channel flow are treated numerically to assess the effect of electrically conducting walls on turbulent MHD flow. As a first approximation, the twin vortex pair is considered as a model of a turbulent eddy near the wall. As the eddy approaches and collides with the wall, a high value electrical potential is induced inside the wall. The Lorentz force, associated with the potential distribution, reduces the velocity gradient in the near-wall region. When considering a fully developed turbulent channel flow, a high electrical conductivity wall was chosen to emphasize the effect of electromagnetic coupling between the wall and the flow. The analysis was performed using DNS. The results are compared with a non-MHD flow and MHD flow in the insulated channel. The mean velocity within the logarithmic region in the case of the electrically conducting wall is slightly higher than that in the non-conducting wall case. Thus, the drag is smaller compared to that in the non-conducting wall case due to a reduction of the Reynolds stress in the near wall region through the Lorentz force. This mechanism is explained via reduction of the production term in the Reynolds shear stress budget

Study on thermal conductivity of HTR spherical fuel element matrix graphite

International Nuclear Information System (INIS)

Zhang Kaihong; Liu Xiaoxue; Zhao Hongsheng; Li Ziqiang; Tang Chunhe

2014-01-01

Taking the spherical fuel element matrix graphite ball samples as an example, this paper introduced the principle and method of laser thermal conductivity meter, as well as the specific heat capacity, and analyzed the effects of different test methods and sampling methods on the thermal conductivities at 1000 ℃ of graphite material. The experimental results show that the thermal conductivities of graphite materials tested by synchronous thermal analyzer combining with laser thermal conductivity meter were different from that directly by laser thermal conductivity meter, the former was more reliable and accurate than the later; When sampling from different positions, central samples had higher thermal conductivities than edging samples, which was related to the material density and porosity at the different locations; the thermal conductivities had obvious distinction between samples from different directions, which was because the layer structure of polycrystalline graphite preferred orientation under pressure, generally speaking, the thermal conductivities perpendicular to the molding direction were higher than that parallel to the molding direction. Besides this, the test results show that the thermal conductivities of all the graphite material samples were greater than 30 W/(m (K), achieving the thermal performance index of high temperature gas cooled reactor. (authors)

Teaching Higher Order Thinking in the Introductory MIS Course: A Model-Directed Approach

Science.gov (United States)

Wang, Shouhong; Wang, Hai

2011-01-01

One vision of education evolution is to change the modes of thinking of students. Critical thinking, design thinking, and system thinking are higher order thinking paradigms that are specifically pertinent to business education. A model-directed approach to teaching and learning higher order thinking is proposed. An example of application of the…

Printing of highly conductive solution by alternating current electrohydrodynamic direct-write

Science.gov (United States)

Jiang, Jiaxin; Zheng, Gaofeng; Wang, Xiang; Zheng, Jianyi; Liu, Juan; Liu, Yifang; Li, Wenwang; Guo, Shumin

2018-03-01

Electrohydrodynamic Direct-Write (EDW) is a novel technology for the printing of micro/nano structures. In this paper, Alternating Current (AC) electrical field was introduced to improve the ejection stability of jet with highly conductive solution. By alternating the electrical field, the polarity of free charges on the surface of jet was changed and the average density of charge, as well as the repulsive force, was reduced to stabilize the jet. When the frequency of AC electrical field increased, the EDW process became more stable and the shape of deposited droplets became more regular. The diameter of printed droplets decreased and the deposition frequency increased with the increase of voltage frequency. The phenomenon of corona discharge was overcome effectively as well. To further evaluate the performance of AC EDW for highly conductive solution, more NaCl was added to the solution and the conductivity was increased to 2810μs/cm. With such high conductivity, the problem of serious corona discharge could still be prevented by AC EDW, and the diameter of printed droplets decreased significantly. This work provides an effective way to accelerate industrial applications of EDW.

Direct calculation of modal contributions to thermal conductivity via Green–Kubo modal analysis

International Nuclear Information System (INIS)

Lv, Wei; Henry, Asegun

2016-01-01

We derived a new method for direct calculation of the modal contributions to thermal conductivity, which is termed Green–Kubo modal analysis (GKMA). The GKMA method combines the lattice dynamics formalism with the Green–Kubo formula for thermal conductivity, such that the thermal conductivity becomes a direct summation of modal contributions, where one need not define the phonon velocity. As a result, the GKMA method can be applied to any material/group of atoms, where the atoms vibrate around stable equilibrium positions, which includes non-stoichiometric compounds, random alloys, amorphous materials and even rigid molecules. By using molecular dynamics simulations to obtain the time history of each mode’s contribution to the heat current, one naturally includes anharmonicity to full order and can obtain insight into the interactions between different modes through the cross-correlations. As an example, we applied the GMKA method to crystalline and amorphous silicon. The modal contributions at each frequency result from the analysis and thereby allow one to apply a quantum correction to the mode heat capacity to determine the temperature dependence of thermal conductivity. The predicted temperature dependent thermal conductivity for amorphous silicon shows the best agreement with experiments to date. The GKMA method provides new insight into the nature of phonon transport, as it casts the problem in terms of mode–mode correlation instead of scattering, and provides a general unified formalism that can be used to understand phonon–phonon interactions in essentially any class of materials or structures where the atoms vibrate around stable equilibrium sites. (paper)

Higher order equivalent edge currents for fringe wave radar scattering by perfectly conducting polygonal plates

DEFF Research Database (Denmark)

Breinbjerg, Olav

1992-01-01

An approach for including higher order edge diffraction in the equivalent edge current (EEC) method is proposed. This approach, which applies to monostatic as well as bistatic radar configurations with perfectly conducting polygonal plates, involves three distinct sets of EECs. All of these sets...

High electrical conductivity in out of plane direction of electrodeposited Bi2Te3 films

Directory of Open Access Journals (Sweden)

Miguel Muñoz Rojo

2015-08-01

Full Text Available The out of plane electrical conductivity of highly anisotropic Bi2Te3 films grown via electro-deposition process was determined using four probe current-voltage measurements performed on 4.6 - 7.2 μm thickness Bi2Te3 mesa structures with 80 - 120 μm diameters sandwiched between metallic film electrodes. A three-dimensional finite element model was used to predict the electric field distribution in the measured structures and take into account the non-uniform distribution of the current in the electrodes in the vicinity of the probes. The finite-element modeling shows that significant errors could arise in the measured film electrical conductivity if simpler one-dimensional models are employed. A high electrical conductivity of (3.2 ± 0.4 ⋅ 105 S/m is reported along the out of plane direction for Bi2Te3 films highly oriented in the [1 1 0] direction.

Anisotropic ionic conductivity observed in superplastically deformed yttria-stabilized zirconia/alumina composite

International Nuclear Information System (INIS)

Drennan, J.; Swain, M.V.; Badwal, S.P.S.

1989-01-01

Ionic conductivity measurements on a yttria-stabilized tetragonal zirconia polycrystal/alumina composite subjected to superplastic deformation demonstrate anisotropic character. Parallel to the pressing direction, the grain-boundary resistance to oxygen ion mobility is 25% to 30% higher than that measured perpendicular to the pressing direction. The same directional dependency on the volume conductivity is observed but is less pronounced, showing approximately a 9% difference. Microstructural evidence reveals an agglomeration and elongation of alumina particles perpendicular to the pressing direction, and it is suggested that this phenomenon restricts the passage of ions parallel to the compression direction, giving rise to the anisotropic nature of the conductivity measurements

Application possibility of the direct current conduction method for nondestructive crack measurement

International Nuclear Information System (INIS)

Riedl, R.

1982-01-01

An important value to determine the danger of cracks is the determination of crack depths. The crack depth can be determined quite accurate by means of the direct current conduction method, if one holds onto certain rules. Often complicated experimental set-ups are applied. However, portable commercial devices can be obtained that can be used for partial fluxation, that yield good results. By means of two examples: crack conduction samples in which the built-up of a constant-cracking is persued up to a certain depth, as well as the persuasion of an continuing crack in a bearing cylinder, shall be demonstrated that is very well possible to record accurate profiles with commercial devices and to avoid expensive measurement devices. (orig.) [de

LOCAL POLITICAL DYNAMICS IN THE GENERAL ELECTION DIRECTLY CONDUCTED TO VOTE FOR DISTRICT HEADS (PILKADA IN BADUNG REGENCY IN 2005

Directory of Open Access Journals (Sweden)

Anak Agung Gede Oka Wisnumurti

2012-11-01

Full Text Available The general election directly conducted to vote for the regent and vice regent(Pemilihan Kepala Daerah, abbreviated to Pilkada by the people in Badung Regency in2005 was the first one. The people’s direct involvement in the local political life movedhighly dynamically. The struggle for power by various strengths affected variousdimensions of the people’s lives; therefore, it is interesting to investigate the localpolitical dynamics in the Pilkada directly conducted in Badung Regency in 2005 in theperspective of cultural studies. There are three problems formulated in this study. Theyare (1 what was the dynamics of the Pilkada directly conducted in Badung Regency in2005 like?; (2 how the relation of strengths affected the local political dynamics in thePilkada directly conducted in Badung Regency in 2005?; (3 what were the implicationsand meanings of the local political dynamics of the Pilkada directly conducted in BadungRegency in 2005?The results of the study show that fluctuative changes took place continuouslywith regard to the form and functions of societal structure. Culturally, the people’sideology changed from being mono centric into being multi centric. The relation ofstrengths became segmented into three main strengths forming a new formation ofstrength referred to as trisula. This led to an institutional configuration, differentiation ofpower and locality sedimentation, and provided meanings to competition and tolerance,emancipatory, political comodification, adaptive leadership and local democratic culturalstrengthening.

Strategic Planning Directions of Malaysia's Higher Education: University Autonomy in the Midst of Political Uncertainties

Science.gov (United States)

Sirat, Morshidi Bin

2010-01-01

In Malaysia, the national government has seen fit to steer higher education policy in a direction that is in the "national interest". This notion of "national interest" is best exemplified by the changing relationship between the State, higher education institutions and the market. Since the late 1960s, we saw the gradual but…

Direct Electron Transfer of Enzymes in a Biologically Assembled Conductive Nanomesh Enzyme Platform.

Science.gov (United States)

Lee, Seung-Woo; Lee, Ki-Young; Song, Yong-Won; Choi, Won Kook; Chang, Joonyeon; Yi, Hyunjung

2016-02-24

Nondestructive assembly of a nanostructured enzyme platform is developed in combination of the specific biomolecular attraction and electrostatic coupling for highly efficient direct electron transfer (DET) of enzymes with unprecedented applicability and versatility. The biologically assembled conductive nanomesh enzyme platform enables DET-based flexible integrated biosensors and DET of eight different enzyme with various catalytic activities. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Direct 2-D reconstructions of conductivity and permittivity from EIT data on a human chest.

Science.gov (United States)

Herrera, Claudia N L; Vallejo, Miguel F M; Mueller, Jennifer L; Lima, Raul G

2015-01-01

A novel direct D-bar reconstruction algorithm is presented for reconstructing a complex conductivity distribution from 2-D EIT data. The method is applied to simulated data and archival human chest data. Permittivity reconstructions with the aforementioned method and conductivity reconstructions with the previously existing nonlinear D-bar method for real-valued conductivities depicting ventilation and perfusion in the human chest are presented. This constitutes the first fully nonlinear D-bar reconstructions of human chest data and the first D-bar permittivity reconstructions of experimental data. The results of the human chest data reconstructions are compared on a circular domain versus a chest-shaped domain.

Thermodynamic analysis of direct internal reforming of methane and butane in proton and oxygen conducting fuel cells

NARCIS (Netherlands)

Biesheuvel, P.M.; Geerlings, J.J.C.

2008-01-01

We present results of a thermodynamic analysis of direct internal reforming fuel cells, based on either a proton conducting fuel cell (FC-H+) or an oxygen ion conducting fuel cell (FC-O2-). We analyze the option of methane as fuel as well as butane. The model self-consistently combines all chemical

Maternal warmth and directiveness jointly moderate the etiology of childhood conduct problems.

Science.gov (United States)

Alexandra Burt, S; Klahr, Ashlea M; Neale, Michael C; Klump, Kelly L

2013-10-01

Prior studies exploring gene-environment interactions (GxE) in the development of youth conduct problems (CP) have focused almost exclusively on single-risk experiences, despite research indicating that the presence of other risk factors and or the absence of protective factors can accentuate the influence of a given risk factor on CP. The goal of the current study was to fill this gap in the literature, evaluating whether risky and protective aspects of parenting might combine to jointly moderate the etiology of CP. The sample consisted of 500 child twin pairs from the Michigan State University Twin Registry (MSUTR). Child CP was assessed using multiple informant reports. Maternal warmth and directiveness were assessed via videotaped dyadic interactions between mothers and each of their twins. Biometric GxE analyses revealed that directiveness and warmth did appear to jointly moderate the etiology of CP. In particular, shared environmental influences were accentuated by colder, less directive or 'less engaged' mothering, whereas genetic influences were strongest when the child was experiencing warmer, more directive or 'more authoritative' mothering. Such findings serve to highlight the synergistic effects of risky and protective experiences on child outcomes. They also provide additional empirical support for the bioecological form of GxE, which postulates that, in some cases, genetic influences may be most strongly expressed in the presence of low-risk environments. © 2013 The Authors. Journal of Child Psychology and Psychiatry © 2013 Association for Child and Adolescent Mental Health.

Conductivity change of defective graphene by helium ion beams

Directory of Open Access Journals (Sweden)

Yuichi Naitou

2017-04-01

Full Text Available Applying a recently developed helium ion microscope, we demonstrated direct nano-patterning and Anderson localization of single-layer graphene (SLG on SiO2/Si substrates. In this study, we clarified the spatial-resolution-limitation factor of direct nano-patterning of SLG. Analysis of scanning capacitance microscopy measurements reveals that the conductivity of helium ion (H+-irradiated SLG nanostructures depends on their geometrical size, i.e., the smaller the H+-irradiated SLG region, the higher its conductivity becomes. This finding can be explained by the hopping carrier transport across strongly localized states of defective SLG.

Preparation of conductive Cu patterns by directly writing using nano-Cu ink

Energy Technology Data Exchange (ETDEWEB)

Li, Wei [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Li, Wenjiang; Wei, Jun [School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China); Tan, Junjun [School of Chemical and Materials and Engineering, Hubei University of Technology, Hubei 435003 (China); Chen, Minfang, E-mail: mfchentj@126.com [School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China)

2014-07-01

Conductive and air-stable Cu patterns were directly made on ordinary photo paper using a roller pen filled with nano-Cu ink, which was mainly composed of metallic Cu nanoparticles (NPs) capped with poly(N-vinylpyrrolidone) (PVP). The nano-Cu NPs were obtained via the reduction of Cu{sup 2+} ions by using an excess of hydrazine and PVP. The low sintering temperature (160 °C) in Ar atmosphere played an important role for the preparation of air-stable Cu patterns. The conductivity of a radio-frequency identification antenna made from nano-Cu ink was tested by a lamp, and its resistivity achieved 13.4 ± 0.4 μΩ cm. The Cu NPs were confirmed by means of X-ray powder diffraction and X-ray photoelectron spectra, and the Cu patterns were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. A mechanism for the high conductivity of the Cu pattern made from Cu NPs is proposed. - Highlights: • The synthesis of pure Cu is related to the reducing agent and capping agent. • The sintering under Ar atmosphere prevents Cu pattern's rapid oxidation. • The formation of the bulk Cu decreases the resistivity of the Cu pattern.

Robotic extrusion processes for direct ink writing of 3D conductive polyaniline structures

Science.gov (United States)

Holness, F. Benjamin; Price, Aaron D.

2016-04-01

The intractable nature of intrinsically conductive polymers (ICP) leads to practical limitations in the fabrication of ICP-based transducers having complex three-dimensional geometries. Conventional ICP device fabrication processes have focused primarily on thin-film deposition techniques; therefore this study explores novel additive manufacturing processes specifically developed for ICP with the ultimate goal of increasing the functionality of ICP sensors and actuators. Herein we employ automated polymer paste extrusion processes for the direct ink writing of 3D conductive polyaniline (PANI) structures. Realization of these structures is enabled through a modified fused filament fabrication delta robot equipped with an integrated polymer paste extruder. This unique robot-controlled additive manufacturing platform is capable of fabricating high-resolution 3D conductive PANI and has been utilized to produce structures with a minimum feature size of 1.5 mm. The required processability of PANI is achieved by means of a counter-ion induced thermal doping method. Using this method, a viscous paste is formulated as the extrudate and a thermo-chemical treatment is applied post extrusion to finalize the complexation.

Significance, Nature, and Direction of the Association Between Child Sexual Abuse and Conduct Disorder: A Systematic Review.

Science.gov (United States)

Maniglio, Roberto

2015-07-01

To elucidate the significance, nature, and direction of the potential relationship between child sexual abuse and conduct disorder, all the pertinent studies were reviewed. Ten databases were searched. Blind assessments of study eligibility and quality were performed by two independent researchers. Thirty-six studies including 185,358 participants and meeting minimum quality criteria that were enough to ensure objectivity and to not invalidate results were analyzed. Across the majority of studies, conduct disorder was significantly and directly related to child sexual abuse, especially repeated sexual molestation and abuse involving penetration, even after controlling for various sociodemographic, family, and clinical variables. The association between child sexual abuse and conduct disorder was not confounded by other risk factors, such as gender, socioeconomic status, school achievement, substance problems, physical abuse, parental antisocial behavior or substance problems, parent-child relationships, and family disruption, conflict, or violence. Evidence for a significant interactive effect between child sexual abuse and monoamine oxidase A gene on conduct disorder was scant. Early sexual abuse might predispose to the subsequent onset of conduct disorder which, in turn, may lead to further sexual victimization through association with sexually abusive peers or involvement in dangerous situations or sexual survival strategies. © The Author(s) 2014.

Simple Moving Voltage Average Incremental Conductance MPPT Technique with Direct Control Method under Nonuniform Solar Irradiance Conditions

Directory of Open Access Journals (Sweden)

Amjad Ali

2015-01-01

Full Text Available A new simple moving voltage average (SMVA technique with fixed step direct control incremental conductance method is introduced to reduce solar photovoltaic voltage (VPV oscillation under nonuniform solar irradiation conditions. To evaluate and validate the performance of the proposed SMVA method in comparison with the conventional fixed step direct control incremental conductance method under extreme conditions, different scenarios were simulated. Simulation results show that in most cases SMVA gives better results with more stability as compared to traditional fixed step direct control INC with faster tracking system along with reduction in sustained oscillations and possesses fast steady state response and robustness. The steady state oscillations are almost eliminated because of extremely small dP/dV around maximum power (MP, which verify that the proposed method is suitable for standalone PV system under extreme weather conditions not only in terms of bus voltage stability but also in overall system efficiency.

Four-point probe measurements of a direct current potential drop on layered conductive cylinders

International Nuclear Information System (INIS)

Lu, Yi; Bowler, John R

2012-01-01

We have determined the steady state electric field due to direct current flowing via point contacts at the cylindrical surface of a uniformly layered conductive rod of finite length. The solution allows one to use four-point probe potential drop measurements to estimate the conductivity or thickness of the layer assuming that the other parameters are known. The electrical potential in the rod has a zero radial derivative at its surface except at the injection and extractions points. This means that the required solution can be expressed in terms of a Green’s function satisfying a Neumann boundary condition. Four-point measurements have been made to demonstrate the validity of theoretical results. (paper)

Four-point probe measurements of a direct current potential drop on layered conductive cylinders

Science.gov (United States)

Lu, Yi; Bowler, John R.

2012-11-01

We have determined the steady state electric field due to direct current flowing via point contacts at the cylindrical surface of a uniformly layered conductive rod of finite length. The solution allows one to use four-point probe potential drop measurements to estimate the conductivity or thickness of the layer assuming that the other parameters are known. The electrical potential in the rod has a zero radial derivative at its surface except at the injection and extractions points. This means that the required solution can be expressed in terms of a Green’s function satisfying a Neumann boundary condition. Four-point measurements have been made to demonstrate the validity of theoretical results.

Faculty Development for Advancing Community Engagement in Higher Education: Current Trends and Future Directions

Science.gov (United States)

Welch, Marshall; Plaxton-Moore, Star

2017-01-01

This research involved the conduct of a conceptual review of 28 refereed journal articles and a survey of campus centers for community engagement staff to identify salient features and trends of existing faculty development programming designed to advance service-learning and community engagement in higher education. Results of this investigation…

Effect of doctoring on the performance of direct gravure printing for conductive microfine lines

Science.gov (United States)

Phuong Hoang, Huu; Lim Ko, Sung

2015-11-01

Printed electronics on flexible thin film has challenged and inspired the motivation of scientists in many fields. Among traditional printing methods such as stamping, flexography, offset, screen-printing, and inkjet, the gravure method is expected to reduce costs and increase productivity for printed electronics applications. In this research, conductive microfine line patterns, which print out the layer as microelectrodes for organic thin film transistor (OTFT) or microcircuit lines, have been designed with different size widths and lengths according to the printing direction, MD (machine direction), and CMD (cross machine direction, or transverse direction, TD, which is popularly used in industry). These patterns were printed with nano-particle silver ink on PI thin film, but had some serious problems with discontinuity and less filling after doctoring and printing. To solve these problems, the doctoring effect is investigated and analyzed before ink transferring, mainly in the printing machine direction and CMD. The uniformity and accuracy of the microfine lines are controlled and improved in order to achieve the stability of the printed pattern lines. In this work, considering the effect of the deflection of the doctor blade in the CMD (transverse direction), a doctoring model in the CMD is proposed and compared with the experimental result. Experimentally, proper doctoring conditions like blade stiffness and doctoring pressure are sought.

Effect of doctoring on the performance of direct gravure printing for conductive microfine lines

International Nuclear Information System (INIS)

Hoang, Huu Phuong; Ko, Sung Lim

2015-01-01

Printed electronics on flexible thin film has challenged and inspired the motivation of scientists in many fields. Among traditional printing methods such as stamping, flexography, offset, screen-printing, and inkjet, the gravure method is expected to reduce costs and increase productivity for printed electronics applications. In this research, conductive microfine line patterns, which print out the layer as microelectrodes for organic thin film transistor (OTFT) or microcircuit lines, have been designed with different size widths and lengths according to the printing direction, MD (machine direction), and CMD (cross machine direction, or transverse direction, TD, which is popularly used in industry). These patterns were printed with nano-particle silver ink on PI thin film, but had some serious problems with discontinuity and less filling after doctoring and printing. To solve these problems, the doctoring effect is investigated and analyzed before ink transferring, mainly in the printing machine direction and CMD. The uniformity and accuracy of the microfine lines are controlled and improved in order to achieve the stability of the printed pattern lines. In this work, considering the effect of the deflection of the doctor blade in the CMD (transverse direction), a doctoring model in the CMD is proposed and compared with the experimental result. Experimentally, proper doctoring conditions like blade stiffness and doctoring pressure are sought. (paper)

Development of a Vibration-Based Electromagnetic Energy Harvester by a Conductive Direct-Write Process

Directory of Open Access Journals (Sweden)

Yao-Yun Feng

2017-03-01

Full Text Available A conductive direct-write process of multilayered coils for micro electromagnetic generators is proposed. This novel approach of using silver ink to form the conductive structures largely reduces the fabrication complexity, and it provides a faster alternative to the conventional semiconductor methods. Multi-layered coils with insulation were accurately layered on a micromachined cantilevered diaphragm by a dispenser. Coils several layers thick could be used to increase the power output and double coils were separated by a layer of insulation. Six prototypes, all capable of efficient conversion of vibrational energy into electrical energy, were fabricated. The experimental results, which include measurements of the electromotive force and power output, are presented. Prototypes with two coils and thicker conducting layers had less resistance and the power output was much more than that of a single-coil unit. This generator can produce 82 nW of power at a resonance frequency of 275 Hz under 5 g excitation.

Higher-order conductivity corrections to the Casimir force

International Nuclear Information System (INIS)

Bezerra, Valdir Barbosa; Klimchitskaya, Galina; Mostepanenko, Vladimir

2000-01-01

Full text follows: Considerable recent attention has been focused on the new experiments on measuring the Casimir force. To be confident that experimental data fit theory at a level of several percent, a variety of corrections to the ideal expression for the Casimir force should be taken into account. One of the main corrections at small separations between interacting bodies is the one due to finite conductivity of the boundary metal. This correction has its origin in non-zero penetration depth δ 0 of electromagnetic vacuum oscillations into the metal (for a perfect metal of infinitely large conductivity δ 0 = 0). The other quantity of the dimension of length is the space separation a between two plates or a plate and a sphere. Their relation δ 0 /a is the natural perturbation parameter in which powers the corrections to the Casimir force due to finite conductivity can be expanded. Such an expansion works good for all separations a >> δ 0 (i.e. for separations larger than 100-150 nm). The first-order term of this expansion was calculated almost forty years ago, and the second-order one in 1985 [1]. These two terms are not sufficient for the comparison of the theory with precision modern experiments. In this talk we report the results of paper [2] where the third- and fourth-order terms in δ 0 /a expansion of the Casimir force were calculated first. They gave the possibility to achieve an excellent agreement of a theory and experiment. (author)

Thermal conductivities of single- and multi-layer phosphorene: a molecular dynamics study.

Science.gov (United States)

Zhang, Ying-Yan; Pei, Qing-Xiang; Jiang, Jin-Wu; Wei, Ning; Zhang, Yong-Wei

2016-01-07

As a new two-dimensional (2D) material, phosphorene has drawn growing attention owing to its novel electronic properties, such as layer-dependent direct bandgaps and high carrier mobility. Herein we investigate the in-plane and cross-plane thermal conductivities of single- and multi-layer phosphorene, focusing on geometrical (sample size, orientation and layer number) and strain (compression and tension) effects. A strong anisotropy is found in the in-plane thermal conductivity with its value along the zigzag direction being much higher than that along the armchair direction. Interestingly, the in-plane thermal conductivity of multi-layer phosphorene is insensitive to the layer number, which is in strong contrast to that of graphene where the interlayer interactions strongly influence the thermal transport. Surprisingly, tensile strain leads to an anomalous increase in the in-plane thermal conductivity of phosphorene, in particular in the armchair direction. Both the in-plane and cross-plane thermal conductivities can be modulated by external strain; however, the strain modulation along the cross-plane direction is more effective and thus more tunable than that along the in-plane direction. Our findings here are of great importance for the thermal management in phosphorene-based nanoelectronic devices and for thermoelectric applications of phosphorene.

The Conductive Silver Nanowires Fabricated by Two-beam Laser Direct Writing on the Flexible Sheet

Science.gov (United States)

He, Gui-Cang; Zheng, Mei-Ling; Dong, Xian-Zi; Jin, Feng; Liu, Jie; Duan, Xuan-Ming; Zhao, Zhen-Sheng

2017-02-01

Flexible electrically conductive nanowires are now a key component in the fields of flexible devices. The achievement of metal nanowire with good flexibility, conductivity, compact and smooth morphology is recognized as one critical milestone for the flexible devices. In this study, a two-beam laser direct writing system is designed to fabricate AgNW on PET sheet. The minimum width of the AgNW fabricated by this method is 187 ± 34 nm with the height of 84 ± 4 nm. We have investigated the electrical resistance under different voltages and the applicable voltage per meter range is determined to be less than 7.5 × 103 V/m for the fabricated AgNW. The flexibility of the AgNW is very excellent, since the resistance only increases 6.63% even after the stretched bending of 2000 times at such a small bending radius of 1.0 mm. The proposed two-beam laser direct writing is an efficient method to fabricate AgNW on the flexible sheet, which could be applied in flexible micro/nano devices.

Direct ink writing of 3D conductive polyaniline structures and rheological modelling

Science.gov (United States)

Holness, F. Benjamin; Price, Aaron D.

2018-01-01

The intractable nature of conjugated polymers (CP) leads to practical limitations in the fabrication of CP-based transducers having complex three-dimensional geometries. Conventional CP device fabrication processes have focused primarily on thin-film deposition techniques; this study explores novel additive manufacturing processes specifically developed for CP with the ultimate goal of increasing the functionality of CP sensors and actuators. Herein we employ automated polymer paste extrusion processes for the direct ink writing of 3D conductive polyaniline (PANI) structures. Realization of these structures was enabled through a modified fused filament fabrication delta robot equipped with an integrated polymer paste extruder to fabricate high-resolution 3D conductive PANI structures. The required processability of PANI was achieved by means of a counterion-induced thermal doping method. The effect of thermal doping on the PANI-DBSA paste by means of a constitutive relationship to describe the paste flow as a function of the thermal doping time is explored. This relationship is incorporated within a flow model to predict the extruded track width as a function of various process parameters including: print speed, gauge pressure, nozzle diameter, and pre-extrusion thermal doping time.

Report of the Two-Day National Seminar on New Directions in Higher Education, Organized by the Kerala State Higher Education Council on 12th and 13th July 2010

Science.gov (United States)

Praveen, C.

2010-01-01

This is a report of the Two-Day National Seminar on New Directions in Higher Education, organized by the Kerala State Higher Education Council on 12th and 13th July 2010. The objective of the seminar was to deliberate upon the reforms being undertaken by the Government of India in Higher Education. Reputed scholars from within and outside the…

ac conductivity of a one-dimensional site-disordered lattice

International Nuclear Information System (INIS)

Albers, R.C.; Gubernatis, J.E.

1978-01-01

We report the results of a numerical study of the ac conductivity for the Anderson model of a one-dimensional, site-disordered system of 400 atoms. For different degrees of disorder, we directly diagonalized the Anderson Hamiltonian, used the Kubo-Greenwood formula to evaluate the conductivity, and then averaged the conductivity over 12 configurations. We found that the dominant frequency dependence of the conductivity consisted of a single peak which shifted to higher frequency and decreased in overall magnitude as the disorder was increased. The joint density of states and the eigenstate localization were also computed and are discussed in connection with our results

Coupled Chiral Structure in Graphene-Based Film for Ultrahigh Thermal Conductivity in Both In-Plane and Through-Plane Directions.

Science.gov (United States)

Meng, Xin; Pan, Hui; Zhu, Chengling; Chen, Zhixin; Lu, Tao; Xu, Da; Li, Yao; Zhu, Shenmin

2018-06-21

The development of high-performance thermal management materials to dissipate excessive heat both in plane and through plane is of special interest to maintain efficient operation and prolong the life of electronic devices. Herein, we designed and constructed a graphene-based composite film, which contains chiral liquid crystals (cellulose nanocrystals, CNCs) inside graphene oxide (GO). The composite film was prepared by annealing and compacting of self-assembled GO-CNC, which contains chiral smectic liquid crystal structures. The helical arranged nanorods of carbonized CNC act as in-plane connections, which bridge neighboring graphene sheets. More interestingly, the chiral structures also act as through-plane connections, which bridge the upper and lower graphene layers. As a result, the graphene-based composite film shows extraordinary thermal conductivity, in both in-plane (1820.4 W m -1 K -1 ) and through-plane (4.596 W m -1 K -1 ) directions. As a thermal management material, the heat dissipation and transportation behaviors of the composite film were investigated using a self-heating system and the results showed that the real-time temperature of the heater covered with the film was 44.5 °C lower than a naked heater. The prepared film shows a much higher efficiency of heat transportation than the commonly used thermal conductive Cu foil. Additionally, this graphene-based composite film exhibits excellent mechanical strength of 31.6 MPa and an electrical conductivity of 667.4 S cm -1 . The strategy reported here may open a new avenue to the development of high-performance thermal management films.

Nano-composite of PtRu alloy electrocatalyst and electronically conducting polymer for use as the anode in a direct methanol fuel cell

Energy Technology Data Exchange (ETDEWEB)

Jongho Choi; Kyungwon Park; Hyekyung Lee; Youngmin Kim; Jaesuk Lee; Yungeun Sung [Kwangju Inst. of Science and Technology, Dept. of Materials Science and Engineering, Gwangju (Korea)

2003-08-15

Nano-composites comprised of PtRu alloy nanoparticles and an electronically conducting polymer for the anode electrode in direct methanol fuel cell (DMFC) were prepared. Two conducting polymers of poly(N-vinyl carbazole) and poly(9-(4-vinyl-phenyl)carbazole) were used for the nano-composite electrodes. Structural analyses were carried out using Fourier transform nuclear magnetic resonance spectroscopy, AC impedance spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Electrocatalytic activities were investigated by voltammetry and chronoamperometry in a 2 M CH{sub 3}OH/{sub 0.5} M H{sub 2}SO{sub 4} solution and the data compared with a carbon-supported PtRu electrode. XRD patterns indicated good alloy formation and nano-composite formation was confirmed by TEM. Electrochemical measurements and DMFC unit-cell tests indicate that the nano-composites could be useful in a DMFC, but its performance would be slightly lower than that of a carbon-supported electrode. The interfacial property between the PtRu-polymer nano-composite anode and the polymer electrolyte was good, as evidenced by scanning electron microscopy. For better performance in a DMFC, a higher electric conductivity of the polymer and a lower catalyst loss are needed in nano-composite electrodes. (Author)

Direct patterning of highly-conductive graphene@copper composites using copper naphthenate as a resist for graphene device applications.

Science.gov (United States)

Bi, Kaixi; Xiang, Quan; Chen, Yiqin; Shi, Huimin; Li, Zhiqin; Lin, Jun; Zhang, Yongzhe; Wan, Qiang; Zhang, Guanhua; Qin, Shiqiao; Zhang, Xueao; Duan, Huigao

2017-11-09

We report an electron-beam lithography process to directly fabricate graphene@copper composite patterns without involving metal deposition, lift-off and etching processes using copper naphthenate as a high-resolution negative-tone resist. As a commonly used industrial painting product, copper naphthenate is extremely cheap with a long shelf time but demonstrates an unexpected patterning resolution better than 10 nm. With appropriate annealing under a hydrogen atmosphere, the produced graphene@copper composite patterns show high conductivity of ∼400 S cm -1 . X-ray diffraction, conformal Raman spectroscopy and X-ray photoelectron spectroscopy were used to analyze the chemical composition of the final patterns. With the properties of high resolution and high conductivity, the patterned graphene@copper composites could be used as conductive pads and interconnects for graphene electronic devices with ohmic contacts. Compared to common fabrication processes involving metal evaporation and lift-off steps, this pattern-transfer-free fabrication process using copper naphthenate resist is direct and simple but allows comparable device performance in practical device applications.

Hydraulic conductance as well as nitrogen accumulation plays a role in the higher rate of leaf photosynthesis of the most productive variety of rice in Japan.

Science.gov (United States)

Taylaran, Renante D; Adachi, Shunsuke; Ookawa, Taiichiro; Usuda, Hideaki; Hirasawa, Tadashi

2011-07-01

An indica variety Takanari is known as one of the most productive rice varieties in Japan and consistently produces 20-30% heavier dry matter during ripening than Japanese commercial varieties in the field. The higher rate of photosynthesis of individual leaves during ripening has been recognized in Takanari. By using pot-grown plants under conditions of minimal mutual shading, it was confirmed that the higher rate of leaf photosynthesis is responsible for the higher dry matter production after heading in Takanari as compared with a japonica variety, Koshihikari. The rate of leaf photosynthesis and shoot dry weight became larger in Takanari after the panicle formation and heading stages, respectively, than in Koshihikari. Roots grew rapidly in the panicle formation stage until heading in Takanari compared with Koshihikari. The higher rate of leaf photosynthesis in Takanari resulted not only from the higher content of leaf nitrogen, which was caused by its elevated capacity for nitrogen accumulation, but also from higher stomatal conductance. When measured under light-saturated conditions, stomatal conductance was already decreased due to the reduction in leaf water potential in Koshihikari even under conditions of a relatively small difference in leaf-air vapour pressure difference. In contrast, the higher stomatal conductance was supported by the maintenance of higher leaf water potential through the higher hydraulic conductance in Takanari with the larger area of root surface. However, no increase in root hydraulic conductivity was expected in Takanari. The larger root surface area of Takanari might be a target trait in future rice breeding for increasing dry matter production.

Accurate Models for Evaluating the Direct Conducted and Radiated Emissions from Integrated Circuits

Directory of Open Access Journals (Sweden)

Domenico Capriglione

2018-03-01

Full Text Available This paper deals with the electromagnetic compatibility (EMC issues related to the direct and radiated emissions from a high-speed integrated circuits (ICs. These emissions are evaluated here by means of circuital and electromagnetic models. As for the conducted emission, an equivalent circuit model is derived to describe the IC and the effect of its loads (package, printed circuit board, decaps, etc., based on the Integrated Circuit Emission Model template (ICEM. As for the radiated emission, an electromagnetic model is proposed, based on the superposition of the fields generated in the far field region by the loop currents flowing into the IC and the package pins. A custom experimental setup is designed for validating the models. Specifically, for the radiated emission measurement, a custom test board is designed and realized, able to highlight the contribution of the direct emission from the IC, usually hidden by the indirect emission coming from the printed circuit board. Measurements of the package currents and of the far-field emitted fields are carried out, providing a satisfactory agreement with the model predictions.

Direct growth of transparent conducting Nb-doped anatase TiO2 polycrystalline films on glass

International Nuclear Information System (INIS)

Yamada, Naoomi; Kasai, Junpei; Hitosugi, Taro; Hoang, Ngoc Lam Huong; Nakao, Shoichiro; Hirose, Yasushi; Shimada, Toshihiro; Hasegawa, Tetsuya

2009-01-01

This paper proposes a novel sputter-based method for the direct growth of transparent conducting Ti 1-x Nb x O 2 (TNO) polycrystalline films on glass, without the need for any postdeposition treatments, by the use of an initial seed-layer. Anatase TNO epitaxial films grown on LaAlO 3 (100) substrates under a reducing atmosphere exhibited a low resistivity (ρ) of (3-6)x10 -4 Ω cm. On glass, however, highly resistive rutile phase polycrystalline films (ρ∼100 Ω cm) formed preferentially under the same conditions. These results suggest that epitaxial stabilization of the oxygen-deficient anatase phase occurs on lattice-matched substrates. To produce a similar effect on a glass surface, we deposited a seed-layer of anatase TNO with excellent crystallinity under an increased oxygen atmosphere. As a result, anatase phase TNO polycrystalline films could be grown even under heavily reducing atmospheres. An optimized film exhibited ρ=1.1x10 -3 Ω cm and optical absorption lower than 10% in the visible region. This ρ value is more than one order of magnitude lower than values reported for directly deposited TNO polycrystalline films. This indicates that the seed-layer method has considerable potential for producing transparent conducting TNO polycrystalline films on glass.

Influence of Crucible Thermal Conductivity on Crystal Growth in an Industrial Directional Solidification Process for Silicon Ingots

Directory of Open Access Journals (Sweden)

Zaoyang Li

2016-01-01

Full Text Available We carried out transient global simulations of heating, melting, growing, annealing, and cooling stages for an industrial directional solidification (DS process for silicon ingots. The crucible thermal conductivity is varied in a reasonable range to investigate its influence on the global heat transfer and silicon crystal growth. It is found that the crucible plays an important role in heat transfer, and therefore its thermal conductivity can influence the crystal growth significantly in the entire DS process. Increasing the crucible thermal conductivity can shorten the time for melting of silicon feedstock and growing of silicon crystal significantly, and therefore large thermal conductivity is helpful in saving both production time and power energy. However, the high temperature gradient in the silicon ingots and the locally concave melt-crystal interface shape for large crucible thermal conductivity indicate that high thermal stress and dislocation propagation are likely to occur during both growing and annealing stages. Based on the numerical simulations, some discussions on designing and choosing the crucible thermal conductivity are presented.

The Model of Transformational Change for Moral Action: A Conceptual Framework to Elevate Student Conduct Practice in Higher Education

Science.gov (United States)

Neumeister, James R.

2017-01-01

Higher education faces heightened scrutiny regarding student misconduct, but collegiate disciplinary processes often have minimal impact on students. Their ineffectiveness is partially attributable to the absence of a conceptual framework that guides conduct administration by linking theory, practice, and outcomes. This article presents a…

Electrochemical depositing rGO-Ti-rGO heterogeneous substrates with higher thermal conductivity and heat transfer performance compared to pure Ti.

Science.gov (United States)

Wang, Jing; Wang, Huatao; Zhang, Wenying; Yang, Xinyi; Wen, Guangwu; Wang, Yijie; Zhou, Weiwei

2017-02-17

Titanium (Ti) and its alloys are widely applied in many high strength, light weight applications, but their thermal conductivity is lower compared to that of other metals, which limits their further applications. In this paper, we demonstrated experimentally that rGO-Ti-rGO heterogeneous substrates with higher thermal conductivity, up to ∼38.8% higher than Ti, could be fabricated by electrochemical depositing rGO on their surface. The rGO layers are grown on the surface of Ti substrates, with appearance of bedclothes on the beds. The thickness of rGO layers is around 300-500 nm and around 600-1000 nm when deposited for 5 cycles and 10 cycles, respectively. According to the cooling experiment results, as-prepared Ti + rGO substrates can present excellent thermal conduction performance, and reduce the chip temperature close to 3.2 °C-13.1 °C lower than Ti alloy substrates with the heat flow density of 0.4-3.6 W cm -2 . Finally, the approach to electro-chemically deposit hundreds of nanometer rGO layers on the surface of Ti substrates can improve their thermal conductivity and heat transfer performance, which may have further application in the increasing thermal conduction of other metal-alloys, ceramics and polymers.

Negative infl uence of internet on the conduct studies in higher education

Directory of Open Access Journals (Sweden)

L. B. Ershteyn

2016-01-01

Full Text Available The paper shows that nowadays the Internet is increasingly used in higher education. It is argued that the main directions of research use the Internet show a positive effect of using a global network of higher education. It was revealed that in addition to the positive influence of the Internet network has a signifi cant negative impact. Identifi ed such negative factors as the widespread learning task solving and quick copying in the case of the emergence of new jobs. Not shown the ability to publish new textbooks in applying active methods lectures, due to these facilities benefi ts the Internet. The prevalence of false information on the Internet. The question of providing students with the information as it is fi nished, it is shown that in some cases it is not advisable to do. It is said that the publication of the full study guides is suitable only in the case when it comes to the basic disciplines, in other cases it is doubtful. Analyzed the shortcomings of such methods of struggle with the designated program to identify factors such as plagiarism, limiting the exchange of scientifi c and methodological experience. Revealed such disadvantages of using plagiarism detection software as programs to combat the use of these programs, and others. It is shown that the use of new teaching jobs, may lead to the fact that completed assignments will be distributed by students via the Internet, and thus the depreciation of these tasks will occur. Revealed the following pattern of use of new teaching jobs in higher education: the more effective is the learning task, the greater the likelihood that it will be devalued. The question required a waiver of such types of learning tasks as translation work, which is due to the fact that students are copying term papers or materials to them without even reading them. The ways of using reports and abstracts that allow overcome the negative trend. It is shown that the use of the

Studies of Electrical and Thermal Conductivities of Sheared Multi-Walled Carbon Nanotube with Isotactic Polypropylene Polymer Composites

Directory of Open Access Journals (Sweden)

Parvathalu Kalakonda

2015-01-01

at higher temperature due to isotropic electrical and thermal contact in both directions. Oriented MWCNT/iPP nanocomposites exhibit higher electrical and thermal conductivities, attributed primarily by orientation of nanotubes due to the shearing fabrication process.

Infrared photoexcitation spectroscopy of conducting polymer and C60 composites: direct evidence of photo-induced electron transfer

NARCIS (Netherlands)

Lee, Kwanghee; Janssen, R.A.J.; Sariciftci, N.S.; Heeger, A.J.

1994-01-01

We report direct spectral evidence of photoinduced electron transfer from the excited state of conducting polymer onto C60 by infrared photoexcitation spectroscopy, from 0.01 eV (100 cm-1) to 1.3 eV (11,000 cm-1). The photoinduced absorption spectra of poly(3-octylthiophene) (P30T) and

Applications of alternating direction methods to the solution of the heat conduction equation, with source, and in transient state

International Nuclear Information System (INIS)

Oliveira Barroso, A.C. de; Alvim, A.C.M.; Gebrin, A.N.; Santos, R.S. dos

1981-01-01

Various types and variants of alternating direction methods. (ADM), were applied to the solution of the time-dependent heat conduction equation, with source, in regions with axial simmetry. Among the basic ADM's, the alternating direction explicit was the one which performed better. An exponential transformation coupled to the ADE seems to be the variant with greater potential, especially if used with a variable time step scheme. (Author) [pt

31 CFR 363.28 - Does Public Debt reserve the right to require that any TreasuryDirect ® transaction be conducted...

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Does Public Debt reserve the right to... Provisions Governing Securities Held in TreasuryDirect § 363.28 Does Public Debt reserve the right to require that any TreasuryDirect ® transaction be conducted in paper form? We reserve the right to require any...

Direct synthesis of pure single-crystalline Magnéli phase Ti8O15 nanowires as conductive carbon-free materials for electrocatalysis

Science.gov (United States)

He, Chunyong; Chang, Shiyong; Huang, Xiangdong; Wang, Qingquan; Mei, Ao; Shen, Pei Kang

2015-02-01

The Magnéli phase Ti8O15 nanowires (NWs) have been grown directly on a Ti substrate by a facile one-step evaporation-deposition synthesis method under a hydrogen atmosphere. The Ti8O15 NWs exhibit an outstanding electrical conductivity at room temperature. The electrical conductivity of a single Ti8O15 nanowire is 20.6 S cm-1 at 300 K. Theoretical calculations manifest that the existence of a large number of oxygen vacancies changes the band structure, resulting in the reduction of the electronic resistance. The Magnéli phase Ti8O15 nanowires have been used as conductive carbon-free supports to load Pt nanoparticles for direct methanol oxidation reaction (MOR). The Pt/Ti8O15 NWs show an enhanced activity and extremely high durability compared with commercial Pt/C catalysts.The Magnéli phase Ti8O15 nanowires (NWs) have been grown directly on a Ti substrate by a facile one-step evaporation-deposition synthesis method under a hydrogen atmosphere. The Ti8O15 NWs exhibit an outstanding electrical conductivity at room temperature. The electrical conductivity of a single Ti8O15 nanowire is 20.6 S cm-1 at 300 K. Theoretical calculations manifest that the existence of a large number of oxygen vacancies changes the band structure, resulting in the reduction of the electronic resistance. The Magnéli phase Ti8O15 nanowires have been used as conductive carbon-free supports to load Pt nanoparticles for direct methanol oxidation reaction (MOR). The Pt/Ti8O15 NWs show an enhanced activity and extremely high durability compared with commercial Pt/C catalysts. Electronic supplementary information (ESI) available: Additional data for the characterization and experimental details see DOI: 10.1039/c4nr05806b

Proton conducting hydrocarbon membranes: Performance evaluation for room temperature direct methanol fuel cells

International Nuclear Information System (INIS)

Krivobokov, Ivan M.; Gribov, Evgeniy N.; Okunev, Alexey G.

2011-01-01

The methanol permeability, proton conductivity, water uptake and power densities of direct methanol fuel cells (DMFCs) at room temperature are reported for sulfonated hydrocarbon (sHC) and perfluorinated (PFSA) membranes from Fumatech, and compared to Nafion membranes. The sHC membranes exhibit lower proton conductivity (25-40 mS cm -1 vs. ∼95-40 mS cm -1 for Nafion) as well as lower methanol permeability (1.8-3.9 x 10 -7 cm 2 s -1 vs. 2.4-3.4 x 10 -6 cm 2 s -1 for Nafion). Water uptake was similar for all membranes (18-25 wt%), except for the PFSA membrane (14 wt%). Methanol uptake varied from 67 wt% for Nafion to 17 wt% for PFSA. The power density of Nafion in DMFCs at room temperature decreases with membrane thickness from 26 mW cm -2 for Nafion 117 to 12.5 mW cm -2 for Nafion 112. The maximum power density of the Fumatech membranes ranges from 4 to 13 mW cm -1 . Conventional transport parameters such as membrane selectivity fail to predict membrane performance in DMFCs. Reliable and easily interpretable results are obtained when the power density is plotted as a function of the transport factor (TF), which is the product of proton concentration in the swollen membrane and the methanol flux. At low TF values, cell performance is limited by low proton conductivity, whereas at high TF values it decreases due to methanol crossover. The highest maximum power density corresponds to intermediate values of TF.

Enhanced Proton Conductivity of Sulfonated Hybrid Poly(arylene ether ketone) Membranes by Incorporating an Amino-Sulfo Bifunctionalized Metal-Organic Framework for Direct Methanol Fuel Cells.

Science.gov (United States)

Ru, Chunyu; Li, Zhenhua; Zhao, Chengji; Duan, Yuting; Zhuang, Zhuang; Bu, Fanzhe; Na, Hui

2018-03-07

Novel side-chain-type sulfonated poly(arylene ether ketone) (SNF-PAEK) containing naphthalene and fluorine moieties on the main chain was prepared in this work, and a new amino-sulfo-bifunctionalized metal-organic framework (MNS, short for MIL-101-NH 2 -SO 3 H) was synthesized via a hydrothermal technology and postmodification. Then, MNS was incorporated into a SNF-PAEK matrix as an inorganic nanofiller to prepare a series of organic-inorganic hybrid membranes (MNS@SNF-PAEK-XX). The mechanical property, methanol resistance, electrochemistry, and other properties of MNS@SNF-PAEK-XX hybrid membranes were characterized in detail. We found that the mechanical strength and methanol resistances of these hybrid membranes were improved by the formation of an ionic cross-linking structure between -NH 2 of MNS and -SO 3 H on the side chain of SNF-PAEK. Particularly, the proton conductivity of these hybrid membranes increased obviously after the addition of MNS. MNS@SNF-PAEK-3% exhibited the proton conductivity of 0.192 S·cm -1 , which was much higher than those of the pristine membrane (0.145 S·cm -1 ) and recast Nafion (0.134 S·cm -1 ) at 80 °C. This result indicated that bifunctionalized MNS rearranged the microstructure of hybrid membranes, which could accelerate the transfer of protons. The hybrid membrane (MNS@SNF-PAEK-3%) showed a better direct methanol fuel cell performance with a higher peak power density of 125.7 mW/cm 2 at 80 °C and a higher open-circuit voltage (0.839 V) than the pristine membrane.

Synthesis of polymer nanostructures with conductance switching properties

Science.gov (United States)

Su, Kai; Nuraje, Nurxat; Zhang, Lingzhi; Matsui, Hiroshi; Yang, Nan Loh

2015-03-03

The present invention is directed to crystalline organic polymer nanoparticles comprising a conductive organic polymer; wherein the crystalline organic polymer nanoparticles have a size of from 10 nm to 200 nm and exhibits two current-voltage states: (1) a high resistance current-voltage state, and (2) a low resistance current-voltage state, wherein when a first positive threshold voltage (V.sub.th1) or higher positive voltage, or a second negative threshold voltage (V.sub.th2) or higher negative voltage is applied to the nanoparticle, the nanoparticle exhibits the low-resistance current-voltage state, and when a voltage less positive than the first positive threshold voltage or a voltage less negative than the second negative threshold voltage is applied to the nanoparticle, the nanoparticle exhibits the high-resistance current-voltage state. The present invention is also directed methods of manufacturing the nanoparticles using novel interfacial oxidative polymerization techniques.

Innovative Directions of the Higher Education of Ukraine

Directory of Open Access Journals (Sweden)

Klyap Marianna

2016-11-01

Full Text Available The article clarifies the concept of “innovation”, including “educational innovation”, examines some innovative teaching methods in universities. The main approaches of implementation innovations in modern higher education of Ukraine are analysed. It also defines the differences between traditional and innovative teaching, discovers different variants of the classification of innovative teaching methods and formulates basic approaches to the selection of innovative didactic purpose in accordance with the classes, the advantages and disadvantages of the use of certain methods. It tightly describes actual interpretation of innovative study methods in the Ukrainian higher educational institutions, as well as the realization of the innovative aspects in the separate Ukrainian universities. The importance of innovation in the learning process of entering higher education of Ukraine into the European educational space is also being highlighted.

Nanoporous palladium anode for direct ethanol solid oxide fuel cells with nanoscale proton-conducting ceramic electrolyte

Science.gov (United States)

Li, Yong; Wong, Lai Mun; Xie, Hanlin; Wang, Shijie; Su, Pei-Chen

2017-02-01

In this work, we demonstrate the operation of micro-solid oxide fuel cells (μ-SOFCs) with nanoscale proton-conducting Y-BaZrO3 (BZY) electrolyte to avoid the fuel crossover problem for direct ethanol fuel cells (DEFCs). The μ-SOFCs are operated with the direct utilisation of ethanol vapour as a fuel and Pd as anode at the temperature range of 300-400 °C. The nanoporous Pd anode is achieved by DC sputtering at high Ar pressure of 80 mTorr. The Pd-anode/BYZ-electrolyte/Pt-cathode cell show peak power densities of 72.4 mW/cm2 using hydrogen and 15.3 mW/cm2 using ethanol at 400 °C. No obvious carbon deposition is seen from XPS analysis after fuel cell test with ethanol fuel.

Summary of recent works conducted in Azerbaijan Republic in the direction of peaceful use of nuclear energy

International Nuclear Information System (INIS)

Garibov, A.A.

2012-01-01

Full text :The following terms are shown for the projects carried out on peaceful use of nuclear energy: Scientific-technical innovations; Economical productivity; Maintenance of nuclear security and radiation safety; Competitiveness and inability of execution with order methods. In the Republic of Azerbaijan at state level has been determined the strategically trends in the direction of peaceful use of nuclear energy and expedient works are carried out. The achieved condition allows developing of the most advanced world technologies, scientific and technical directions in Azerbaijan Republic. For this purpose, the most advanced and modern projects are being conducted in the direction of peaceful use of nuclear and radiation technologies : 1) The most modern monitoring equipment's have been installed in all border crossing points and permanent and operative working regime has been provided. Import-export monitoring system is being conducted according to the international requirements; 2) The body provided with the most advanced technology and equipment's has been developed on the execution of storage and utilization of nuclear and radioactive wastes and existing problems in the field are being successfully solved; 3) The most advanced equipment's, methods and technologies are being applied on the basis of nuclear and radioactive materials in the diagnosis and treatment fields of medicine. 4. The most modern radiation calibrating and standardization center are being developed in the Republic. 5. Project is being carried out on the establishment of complex of the most modern sterilization purpose with high-active isotope source in Azerbaijan Republic; 6) Scientific-research works in Azerbaijan republic on peaceful use of nuclear energy has been carried out in the most actual directions since 1969; 7) Azerbaijan Republic actively participates in national and regional projects together with IAEA and other international organizations.

Sol-gel preparation of Ag-silica nanocomposite with high electrical conductivity

Science.gov (United States)

Ma, Zhijun; Jiang, Yuwei; Xiao, Huisi; Jiang, Bofan; Zhang, Hao; Peng, Mingying; Dong, Guoping; Yu, Xiang; Yang, Jian

2018-04-01

Sol-gel derived noble-metal-silica nanocomposites are very useful in many applications. Due to relatively low price, higher conductivity, and higher chemical stability of silver (Ag) compared with copper (Cu), Ag-silica has gained much more research interest. However, it remains a significant challenge to realize high loading of Ag content in sol-gel Ag-silica composite with high structural controllability and nanoparticles' dispersity. Different from previous works by using multifunctional silicon alkoxide to anchor metal ions, here we report the synthesis of Ag-silica nanocomposite with high loading of Ag nanoparticles by employing acetonitrile bi-functionally as solvent and metal ions stabilizer. The electrical conductivity of the Ag-silica nanocomposite reached higher than 6800 S/cm. In addition, the Ag-silica nanocomposite could simultaneously possess high electrical conductivity and positive conductivity-temperature coefficient by properly controlling the loading content of Ag. Such behavior is potentially advantageous for high-temperature devices (like phosphoric acid fuel cells) and inhibiting the thermal-induced increase of devices' internal resistance. The strategy proposed here is also compatible with block-copolymer directed self-assembly of mesoporous material, spin-coating of film and electrospinning of nanofiber, making it more charming in various practical applications.

Complex conductivity of organic-rich shales

Science.gov (United States)

Woodruff, W. F.; Revil, A.; Torres-Verdin, C.

2013-12-01

components of the formation factor and connectivity (tortuosity) tensors Fij and Tij (affecting the bulk and surface conductivity, respectively) are correlated as Fij=TijΦ. Both conductivity and connectivity tensors share the same eigenvectors; the anisotropy ratio is equivalent in TI media. At high pore water salinity, surface and quadrature conductivity share the same bulk tortuosity; when surface conductivity dominates (low salinity), conductivity is controlled by the surface conductance, and the tortuosity of electrical current along mineral surfaces usually higher than that of the pore water. We developed two distinct SIP measurement protocols to obtain the tensor: (1) azimuthal sampling and inversion of phasor potentials through the full-field solution of the Laplace equation; (2) direct measurement of complex conductivity eigenvalues by polarized, single-component stimulus current. Experiments also include unsaturated and saturated measurements with three brines of known salinity and pH, at log-distributed frequencies ranging 1 mHz to 45 kHz. Both azimuthal spectra and eigenvalue spectra validate the theoretical model and illustrate the effectiveness of the protocols themselves. We obtain the textural tensors and invert key parameters including Archie exponents and CEC, and characterize the relaxation phenomena associated with kerogen content and maturity for multiphase fluid systems.

Direct cost of monitoring conventional hemodialysis conducted by nursing professionals

OpenAIRE

Lima, Antônio Fernandes Costa

2017-01-01

ABSTRACT Objective: to analyze the mean direct cost of conventional hemodialysis monitored by nursing professionals in three public teaching and research hospitals in the state of São Paulo, Brazil. Method: this was a quantitative, explorative and descriptive investigation, based on a multiple case study approach. The mean direct cost was calculated by multiplying (clocked) time spent per procedure by the unit cost of direct labor. Values were calculated in Brazilian real (BRL). Results: H...

High temperature thermal conductivity measurements of UO2 by Direct Electrical Heating. Final report

International Nuclear Information System (INIS)

Bassett, B.

1980-10-01

High temperature properties of reactor type UO 2 pellets were measured using a Direct Electrical Heating (DEH) Facility. Modifications to the experimental apparatus have been made so that successful and reproducible DEH runs may be carried out while protecting the pellets from oxidation at high temperature. X-ray diffraction measurements on the UO 2 pellets have been made before and after runs to assure that sample oxidation has not occurred. A computer code has been developed that will model the experiment using equations that describe physical properties of the material. This code allows these equations to be checked by comparing the model results to collected data. The thermal conductivity equation for UO 2 proposed by Weilbacher has been used for this analysis. By adjusting the empirical parameters in Weilbacher's equation, experimental data can be matched by the code. From the several runs analyzed, the resulting thermal conductivity equation is lambda = 1/4.79 + 0.0247T/ + 1.06 x 10 -3 exp[-1.62/kT/] - 4410. exp[-3.71/kT/] where lambda is in w/cm K, k is the Boltzman constant, and T is the temperature in Kelvin

Direct cost of monitoring conventional hemodialysis conducted by nursing professionals.

Science.gov (United States)

Lima, Antônio Fernandes Costa

2017-04-01

to analyze the mean direct cost of conventional hemodialysis monitored by nursing professionals in three public teaching and research hospitals in the state of São Paulo, Brazil. this was a quantitative, explorative and descriptive investigation, based on a multiple case study approach. The mean direct cost was calculated by multiplying (clocked) time spent per procedure by the unit cost of direct labor. Values were calculated in Brazilian real (BRL). Hospital C presented the highest mean direct cost (BRL 184.52), 5.23 times greater than the value for Hospital A (BRL 35.29) and 3.91 times greater than Hospital B (BRL 47.22). the costing method used in this study can be reproduced at other dialysis centers to inform strategies aimed at efficient allocation of necessary human resources to successfully monitor conventional hemodialysis.

Direct cost of monitoring conventional hemodialysis conducted by nursing professionals

Directory of Open Access Journals (Sweden)

Antônio Fernandes Costa Lima

Full Text Available ABSTRACT Objective: to analyze the mean direct cost of conventional hemodialysis monitored by nursing professionals in three public teaching and research hospitals in the state of São Paulo, Brazil. Method: this was a quantitative, explorative and descriptive investigation, based on a multiple case study approach. The mean direct cost was calculated by multiplying (clocked time spent per procedure by the unit cost of direct labor. Values were calculated in Brazilian real (BRL. Results: Hospital C presented the highest mean direct cost (BRL 184.52, 5.23 times greater than the value for Hospital A (BRL 35.29 and 3.91 times greater than Hospital B (BRL 47.22. Conclusion: the costing method used in this study can be reproduced at other dialysis centers to inform strategies aimed at efficient allocation of necessary human resources to successfully monitor conventional hemodialysis.

Proton conducting semi-IPN based on Nafion and crosslinked poly(AMPS) for direct methanol fuel cell

International Nuclear Information System (INIS)

Cho, Ki-Yun; Jung, Ho-Young; Shin, Seung-Shik; Choi, Nam-Soon; Sung, Shi-Joon; Park, Jung-Ki; Choi, Jong-Ho; Park, Kyung-Won; Sung, Yung-Eun

2004-01-01

For direct methanol fuel cell, the proton conducting membrane based on semi-interpenetrating polymer networks (IPNs) of Nafion and crosslinked poly(AMPS) was prepared and characterized. The modification of Nafion with crosslinked poly(AMPS) such as hydrocarbon polymer changed the state of water in membranes. Without a significant increase of the membrane resistance, the semi-IPNs demonstrated a reduction of the methanol permeability, comparing to the native Nafion. And the maximum power density of AMPS60 increased as much as 22.2% compared with Nafion

Compiler-Directed Transformation for Higher-Order Stencils

Energy Technology Data Exchange (ETDEWEB)

Basu, Protonu [Univ. of Utah, Salt Lake City, UT (United States); Hall, Mary [Univ. of Utah, Salt Lake City, UT (United States); Williams, Samuel [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Straalen, Brian Van [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Oliker, Leonid [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Colella, Phillip [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2015-07-20

As the cost of data movement increasingly dominates performance, developers of finite-volume and finite-difference solutions for partial differential equations (PDEs) are exploring novel higher-order stencils that increase numerical accuracy and computational intensity. This paper describes a new compiler reordering transformation applied to stencil operators that performs partial sums in buffers, and reuses the partial sums in computing multiple results. This optimization has multiple effect son improving stencil performance that are particularly important to higher-order stencils: exploits data reuse, reduces floating-point operations, and exposes efficient SIMD parallelism to backend compilers. We study the benefit of this optimization in the context of Geometric Multigrid (GMG), a widely used method to solvePDEs, using four different Jacobi smoothers built from 7-, 13-, 27-and 125-point stencils. We quantify performance, speedup, andnumerical accuracy, and use the Roofline model to qualify our results. Ultimately, we obtain over 4× speedup on the smoothers themselves and up to a 3× speedup on the multigrid solver. Finally, we demonstrate that high-order multigrid solvers have the potential of reducing total data movement and energy by several orders of magnitude.

Code of conduct for scientists (abstract)

International Nuclear Information System (INIS)

Khurshid, S.J.

2011-01-01

The emergence of advanced technologies in the last three decades and extraordinary progress in our knowledge on the basic Physical, Chemical and Biological properties of living matter has offered tremendous benefits to human beings but simultaneously highlighted the need of higher awareness and responsibility by the scientists of 21 century. Scientist is not born with ethics, nor science is ethically neutral, but there are ethical dimensions to scientific work. There is need to evolve an appropriate Code of Conduct for scientist particularly working in every field of Science. However, while considering the contents, promulgation and adaptation of Codes of Conduct for Scientists, a balance is needed to be maintained between freedom of scientists and at the same time some binding on them in the form of Code of Conducts. The use of good and safe laboratory procedures, whether, codified by law or by common practice must also be considered as part of the moral duties of scientists. It is internationally agreed that a general Code of Conduct can't be formulated for all the scientists universally, but there should be a set of 'building blocks' aimed at establishing the Code of Conduct for Scientists either as individual researcher or responsible for direction, evaluation, monitoring of scientific activities at the institutional or organizational level. (author)

Intermittent Contact Alternating Current Scanning Electrochemical Microscopy: A Method for Mapping Conductivities in Solid Li Ion Conducting Electrolyte Samples

Energy Technology Data Exchange (ETDEWEB)

Catarelli, Samantha Raisa; Lonsdale, Daniel [Uniscan Instruments Ltd., Macclesfield (United Kingdom); Cheng, Lei [Energy Storage and Distribution Resources Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Materials Sciences and Engineering Department, University of California Berkeley, Berkeley, CA (United States); Syzdek, Jaroslaw [Bio-Logic USA LLC, Knoxville, TN (United States); Doeff, Marca, E-mail: mmdoeff@lbl.gov [Energy Storage and Distribution Resources Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

2016-03-31

Intermittent contact alternating current scanning electrochemical microscopy (ic-ac-SECM) has been used to determine the electrochemical response to an ac signal of several types of materials. A conductive gold foil and insulating Teflon sheet were first used to demonstrate that the intermittent contact function allows the topography and conductivity to be mapped simultaneously and independently in a single experiment. Then, a dense pellet of an electronically insulating but Li ion conducting garnet phase, Al-substituted Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} (LLZO), was characterized using the same technique. The polycrystalline pellet was prepared by classical ceramic sintering techniques and was comprised of large (~150 μm) grains. Critical information regarding the contributions of grain and grain boundary resistances to the total conductivity of the garnet phase was lacking due to ambiguities in the impedance data. In contrast, the use of the ic-ac-SECM technique allowed spatially resolved information regarding local conductivities to be measured directly. Impedance mapping of the pellet showed that the grain boundary resistance, while generally higher than that of grains, varied considerably, revealing the complex nature of the LLZO sample.

Thermal conductivity of a two-dimensional phosphorene sheet: a comparative study with graphene.

Science.gov (United States)

Hong, Yang; Zhang, Jingchao; Huang, Xiaopeng; Zeng, Xiao Cheng

2015-11-28

A recently discovered two-dimensional (2D) layered material phosphorene has attracted considerable interest as a promising p-type semiconducting material. In this work, thermal conductivity (κ) of monolayer phosphorene is calculated using large-scale classical non-equilibrium molecular dynamics (NEMD) simulations. The predicted thermal conductivities for infinite length armchair and zigzag phosphorene sheets are 63.6 and 110.7 W m(-1) K(-1) respectively. The strong anisotropic thermal transport is attributed to the distinct atomic structures at altered chiral directions and direction-dependent group velocities. Thermal conductivities of 2D graphene sheets with the same dimensions are also computed for comparison. The extrapolated κ of the 2D graphene sheet are 1008.5(+37.6)(-37.6) and 1086.9(+59.1)(-59.1) W m(-1) K(-1) in the armchair and zigzag directions, respectively, which are an order of magnitude higher than those of phosphorene. The overall and decomposed phonon density of states (PDOS) are calculated in both structures to elucidate their thermal conductivity differences. In comparison with graphene, the vibrational frequencies that can be excited in phosphorene are severely limited. The temperature effect on the thermal conductivity of phosphorene and graphene sheets is investigated, which reveals a monotonic decreasing trend for both structures.

Comparing the similarity of responses received from studies in Amazon's Mechanical Turk to studies conducted online and with direct recruitment.

Science.gov (United States)

Bartneck, Christoph; Duenser, Andreas; Moltchanova, Elena; Zawieska, Karolina

2015-01-01

Computer and internet based questionnaires have become a standard tool in Human-Computer Interaction research and other related fields, such as psychology and sociology. Amazon's Mechanical Turk (AMT) service is a new method of recruiting participants and conducting certain types of experiments. This study compares whether participants recruited through AMT give different responses than participants recruited through an online forum or recruited directly on a university campus. Moreover, we compare whether a study conducted within AMT results in different responses compared to a study for which participants are recruited through AMT but which is conducted using an external online questionnaire service. The results of this study show that there is a statistical difference between results obtained from participants recruited through AMT compared to the results from the participant recruited on campus or through online forums. We do, however, argue that this difference is so small that it has no practical consequence. There was no significant difference between running the study within AMT compared to running it with an online questionnaire service. There was no significant difference between results obtained directly from within AMT compared to results obtained in the campus and online forum condition. This may suggest that AMT is a viable and economical option for recruiting participants and for conducting studies as setting up and running a study with AMT generally requires less effort and time compared to other frequently used methods. We discuss our findings as well as limitations of using AMT for empirical studies.

A simple technique for direct growth of Au into a nanoporous alumina layer on conductive glass as a reusable SERS substrate

Energy Technology Data Exchange (ETDEWEB)

Yu, Jiajie [Chemicobiology and Functional Materials Institute, Nanjing University of Science and Technology, Nanjing 210094 (China); Shen, Muzhong [School of Engineering, AnHui Agricultural University, Hefei 230036 (China); Liu, Siyu; Li, Feng [Chemicobiology and Functional Materials Institute, Nanjing University of Science and Technology, Nanjing 210094 (China); Sun, Dongping, E-mail: sundpe301@163.com [School of Engineering, AnHui Agricultural University, Hefei 230036 (China); Wang, Tianhe, E-mail: thwang56@126.com [Chemicobiology and Functional Materials Institute, Nanjing University of Science and Technology, Nanjing 210094 (China)

2017-06-01

Graphical abstract: A simple technique for direct growth of gold nanoparticles (GNPs) into a nanostructured porous alumina layer on conductive glass slide (PAOCG). Gold was uniformly distributed in porous alumina layer. Au/PAOCG can serve as a portable, durable and reusable SERS substrate. - Highlights: • A simple method of producing nanoporous alumina layer on conductive glasses. • A facile technique for direct growth of gold nanoparticles (GNPs) into PAOCG. • It presents a general protocol for preparation of (MNPs) on conductive glasses. • Au/PAOCG exhibits high SERS sensitivity and excellent reusability. - Abstract: In this paper, we describe a simple technique for direct growth of gold nanoparticles (GNPs) into a nanostructured porous alumina layer on conductive glass slide (PAOCG). PAOCG was attached firmly with a small piece of steel and was then immersed in a HAuCl{sub 4} solution. Electro-induced electrons from steel were employed to reduce AuCl{sub 4}{sup −} on PAOCG. The galvanic replacement reaction (GRR) was adopted as the fundamental mechanism for reducing metal precursors. This mechanism was further studied by open circuit potential-time (OCP-t) experiment and the result demonstrated that steel induced the continuous proceeding of this reaction. This strategy presents a simple and general protocol for preparation of metal nanoparticles (MNPs) on conductive glass substrates. The SERS properties of Au/PAOCG were investigated using aqueous crystal violet (CV) and 4-mercaptopyridine (4-Mpy) as probe molecules. Au/PAOCG allowed as low as 10{sup −9} M CV and 10{sup −8} M 4-Mpy to be detected. The reusability of this substrate was achieved by measuring the SERS spectrum of the probe molecules followed with a 400 °C heat treatment for 10 min to remove the residuals. This substrate could be reused for at least ten cycles without any significantly reduced SERS performance. Therefore, this surface can serve as a portable, durable and reusable SERS

Enhancement of methanogenesis via direct interspecies electron transfer between Geobacteraceae and Methanosaetaceae conducted by granular activated carbon.

Science.gov (United States)

Zhang, Shuo; Chang, Jiali; Lin, Chao; Pan, Yiran; Cui, Kangping; Zhang, Xiaoyuan; Liang, Peng; Huang, Xia

2017-12-01

To understand how granular activated carbon (GAC) promotes methanogenesis, batch tests of CH 4 production potential in anaerobic serum bottles with addition of GAC or not were conducted. Tests showed that GAC promoted methanogenesis remarkably, but the non-conductive zeolite did not. The qPCR demonstrated that the biomass on GAC contributed little to the promotion. High-throughput sequencing data implied that promotion was related with direct interspecies electron transfer between Geobacteraceae and Methanosaetaceae. According to the c-type cytochromes (c-Cyts) response to the supplement of GAC, it was speculated that GAC may play the role of c-Cyts' substitution. In the undefined cultures, the phenomenon that c-Cyts were repressed by GAC was first observed. This research provided new evidence to microbial mechanism of promoting methanogenesis via GAC. Copyright © 2017 Elsevier Ltd. All rights reserved.

Spin and spinless conductivity in polypyrrole. Evidence for mixed-valence conduction

Energy Technology Data Exchange (ETDEWEB)

Zotti, G.; Schiavon, G. (Ist. di Polarografia ed Elettrochimica Preparativa, Padova (Italy))

In situ conductivity of polypyrrole (as tosylate) as a function of oxidative doping level attains a maximum at three-quarters the total oxidation charge and the relevant in situ ESR signal corresponds to an equal concentration of spin-carrying (polaron) and spinless (bipolaron) species. Results are explained on the basis of mixed-valence conduction. Bipolaron conduction, taking the place of polaron-bipolaron conductivity at higher oxidation levels, accounts for persisting conductivity in the high-oxidation state.

Path integration of head direction: updating a packet of neural activity at the correct speed using axonal conduction delays.

Science.gov (United States)

Walters, Daniel; Stringer, Simon; Rolls, Edmund

2013-01-01

The head direction cell system is capable of accurately updating its current representation of head direction in the absence of visual input. This is known as the path integration of head direction. An important question is how the head direction cell system learns to perform accurate path integration of head direction. In this paper we propose a model of velocity path integration of head direction in which the natural time delay of axonal transmission between a linked continuous attractor network and competitive network acts as a timing mechanism to facilitate the correct speed of path integration. The model effectively learns a "look-up" table for the correct speed of path integration. In simulation, we show that the model is able to successfully learn two different speeds of path integration across two different axonal conduction delays, and without the need to alter any other model parameters. An implication of this model is that, by learning look-up tables for each speed of path integration, the model should exhibit a degree of robustness to damage. In simulations, we show that the speed of path integration is not significantly affected by degrading the network through removing a proportion of the cells that signal rotational velocity.

Comparing the similarity of responses received from studies in Amazon's Mechanical Turk to studies conducted online and with direct recruitment.

Directory of Open Access Journals (Sweden)

Christoph Bartneck

Full Text Available Computer and internet based questionnaires have become a standard tool in Human-Computer Interaction research and other related fields, such as psychology and sociology. Amazon's Mechanical Turk (AMT service is a new method of recruiting participants and conducting certain types of experiments. This study compares whether participants recruited through AMT give different responses than participants recruited through an online forum or recruited directly on a university campus. Moreover, we compare whether a study conducted within AMT results in different responses compared to a study for which participants are recruited through AMT but which is conducted using an external online questionnaire service. The results of this study show that there is a statistical difference between results obtained from participants recruited through AMT compared to the results from the participant recruited on campus or through online forums. We do, however, argue that this difference is so small that it has no practical consequence. There was no significant difference between running the study within AMT compared to running it with an online questionnaire service. There was no significant difference between results obtained directly from within AMT compared to results obtained in the campus and online forum condition. This may suggest that AMT is a viable and economical option for recruiting participants and for conducting studies as setting up and running a study with AMT generally requires less effort and time compared to other frequently used methods. We discuss our findings as well as limitations of using AMT for empirical studies.

Direct Integration: Training Software Developers to Conduct Usability Evaluations

DEFF Research Database (Denmark)

Skov, Mikael B.; Stage, Jan

2008-01-01

is based on an empirical study where 36 teams with a total of 234 first-year university students on software development and design educations were trained in a simple approach for user-based website usability testing that was taught in a 40 hour course. This approach supported them in planning, conducting......Many improvements of the interplay between usability evaluation and software development rely either on better methods for conducting usability evaluations or on better formats for presenting evaluation results in ways that are useful for software designers and developers. Both approaches involve...... a complete division of work between developers and evaluators, which is an undesirable complexity for many software development projects. This paper takes a different approach by exploring to what extent software developers and designers can be trained to carry out their own usability evaluations. The paper...

Applications of alternating direction methods to the solution of the time-dependent heat conduction equation with source and in transients stage

International Nuclear Information System (INIS)

Gebrin, A.N.

1981-10-01

Various types and also some variants of alternating direction methods, (A.D.M.), were applied to the solution of the time-dependent heat conduction equation, with source, in region with axial symetry. The results shown that some of the variants perform consistently better than the Classical Cranck-Nicolson method. Having in mind a combination of accuracy, ability to support larg time steps and computational efficiency, the 'alternating direction explicit', (A.D.E.) method appears as the best choice, being the 'alternating direction checkerboard', (A.D.C), method the second best. Additional operations like the exponential transformation or the truncation pos-correction don't seem to be worth, excect for some special cases. (Author) [pt

Directional rf probe for measurement of conductivity of flowing plasmas

International Nuclear Information System (INIS)

Jayakumar, R.; Chakravarthy, D.P.; Rohatgi, V.K.

1977-01-01

An electrodeless immersible rf probe for measurement of plasma conductivity in the range 0.01 to 100 mho/m has been designed and fabricated. The probe, with an overall diameter of 11 mm, employs unidirectional electromagnetic field lines which reduce the inaccuracies caused by insertion of the probe in a flowing plasma. In the range studied the probe output shows a linear relationship with the conductivity of the medium. Such probes are of interest in the study of MHD and reentry plasmas

Controlling the optical performance of transparent conducting oxides using direct laser interference patterning

International Nuclear Information System (INIS)

Berger, Jana; Roch, Teja; Correia, Stelio; Eberhardt, Jens; Lasagni, Andrés Fabián

2016-01-01

In this study, a laser based process called Direct Laser Interference Patterning (DLIP) was used to fabricate micro-textured boron doped zinc oxide (ZnO:B) thin films to be used as electrodes in thin-film silicon solar cells. First, the ablation thresholds of the ZnO:B film were determined using a nanosecond pulsed laser at wavelengths of 266 and 355 nm (100 mJ/cm"2 and 89 mJ/cm"2, respectively). After that, DLIP experiments were performed at 355 nm wavelength. Line-like periodic surface structures with spatial periods ranging from 0.8 to 5.0 μm were fabricated using two interfering laser beams. It was found that the structuring process of the transparent conducting oxide (TCO) is mainly based on a photo-thermal mechanism. The surface of the ZnO:B film was molten and evaporated at the interference maxima positions and the depth and width of the generated microfeatures depend on the laser parameters as well as the spatial period of the interference pattern. The optical properties of the structured TCOs were investigated as a function of the utilized laser processing parameters. Both diffuse and total transmission and the intensity of the diffraction orders were determined. These data were used to calculate the increase of the optical path of the transmitted light. - Highlights: • Direct Laser Interference Patterning (DLIP) on boron doped zinc oxide (LPCVD-ZnO:B) • No relevant decrease of total transmission • Periods of 1.5 μm provide large diffraction angle and good diffraction intensity. • Significant increase of optical path length could be reached.

Controlling the optical performance of transparent conducting oxides using direct laser interference patterning

Energy Technology Data Exchange (ETDEWEB)

Berger, Jana; Roch, Teja [Fraunhofer-Institut für Werkstoff-und Strahltechnik IWS, Winterbergstr. 28, 01277 Dresden (Germany); Technische Universität Dresden, Institute of Manufacturing Technology, George-Baehr-Str.1, 01069 Dresden (Germany); Correia, Stelio; Eberhardt, Jens [Bosch Solar Energy AG, August-Broemel-Str. 6, 99310 Arnstadt (Germany); Lasagni, Andrés Fabián, E-mail: andres_fabian.lasagni@tu-dresden.de [Fraunhofer-Institut für Werkstoff-und Strahltechnik IWS, Winterbergstr. 28, 01277 Dresden (Germany); Technische Universität Dresden, Institute of Manufacturing Technology, George-Baehr-Str.1, 01069 Dresden (Germany)

2016-08-01

In this study, a laser based process called Direct Laser Interference Patterning (DLIP) was used to fabricate micro-textured boron doped zinc oxide (ZnO:B) thin films to be used as electrodes in thin-film silicon solar cells. First, the ablation thresholds of the ZnO:B film were determined using a nanosecond pulsed laser at wavelengths of 266 and 355 nm (100 mJ/cm{sup 2} and 89 mJ/cm{sup 2}, respectively). After that, DLIP experiments were performed at 355 nm wavelength. Line-like periodic surface structures with spatial periods ranging from 0.8 to 5.0 μm were fabricated using two interfering laser beams. It was found that the structuring process of the transparent conducting oxide (TCO) is mainly based on a photo-thermal mechanism. The surface of the ZnO:B film was molten and evaporated at the interference maxima positions and the depth and width of the generated microfeatures depend on the laser parameters as well as the spatial period of the interference pattern. The optical properties of the structured TCOs were investigated as a function of the utilized laser processing parameters. Both diffuse and total transmission and the intensity of the diffraction orders were determined. These data were used to calculate the increase of the optical path of the transmitted light. - Highlights: • Direct Laser Interference Patterning (DLIP) on boron doped zinc oxide (LPCVD-ZnO:B) • No relevant decrease of total transmission • Periods of 1.5 μm provide large diffraction angle and good diffraction intensity. • Significant increase of optical path length could be reached.

Emotional communication in families of conduct problem children with high versus low callous-unemotional traits.

Science.gov (United States)

Pasalich, Dave S; Dadds, Mark R; Vincent, Lucy C; Cooper, Francesca A; Hawes, David J; Brennan, John

2012-01-01

This study examined relationships between parent-child emotional communication and callous-unemotional (CU) traits and conduct problems. References to negative and positive emotions made by clinic-referred boys (3-9 years) and their parents were coded from direct observations of family interactions involving the discussion of shared emotional experiences. Although frequencies of parents' emotion expression did not generally relate to levels of CU traits, boys higher on CU traits were observed to be more expressive of negative emotions in conversation with their caregivers-specifically for sadness and fear. Independent coders did not judge these children to be less genuine in their emotion expression compared to their low-CU counterparts. We also examined whether CU traits moderated the relationship between parents' focus on emotions and conduct problem severity. Higher levels of maternal focus on negative emotions were found to be associated with lower conduct problems in high-CU boys but related to higher conduct problems in low-CU boys. Frequencies of fathers' emotional communication were unrelated to either child CU traits or conduct problems. We discuss the implications of these findings for the conceptualization of CU traits in preadolescent children, and interventions for conduct problems in children elevated on these traits.

Multi-Directional Environmental Sensors

Science.gov (United States)

Manohara, Harish (Inventor); Del Castillo, Linda Y. (Inventor); Mojarradi, Mohammed M. (Inventor)

2016-01-01

Systems and methods in accordance with embodiments of the invention implement multi-directional environmental sensors. In one embodiment, a multi-directional environmental sensor includes: an inner conductive element that is substantially symmetrical about three orthogonal planes; an outer conductive element that is substantially symmetrical about three orthogonal planes; and a device that measures the electrical characteristics of the multi-directional environmental sensor, the device having a first terminal and a second terminal; where the inner conductive element is substantially enclosed within the outer conductive element; where the inner conductive element is electrically coupled to the first terminal of the device; and where the outer conductive element is electrically coupled to the second terminal of the device.

Reusable bi-directional 3ω sensor to measure thermal conductivity of 100-μm thick biological tissues

Science.gov (United States)

Lubner, Sean D.; Choi, Jeunghwan; Wehmeyer, Geoff; Waag, Bastian; Mishra, Vivek; Natesan, Harishankar; Bischof, John C.; Dames, Chris

2015-01-01

Accurate knowledge of the thermal conductivity (k) of biological tissues is important for cryopreservation, thermal ablation, and cryosurgery. Here, we adapt the 3ω method—widely used for rigid, inorganic solids—as a reusable sensor to measure k of soft biological samples two orders of magnitude thinner than conventional tissue characterization methods. Analytical and numerical studies quantify the error of the commonly used "boundary mismatch approximation" of the bi-directional 3ω geometry, confirm that the generalized slope method is exact in the low-frequency limit, and bound its error for finite frequencies. The bi-directional 3ω measurement device is validated using control experiments to within ±2% (liquid water, standard deviation) and ±5% (ice). Measurements of mouse liver cover a temperature ranging from -69 °C to +33 °C. The liver results are independent of sample thicknesses from 3 mm down to 100 μm and agree with available literature for non-mouse liver to within the measurement scatter.

Purposeful Goal-Directed Movements Give Rise to Higher Tactile Discrimination Performance

Directory of Open Access Journals (Sweden)

Georgiana Juravle

2011-10-01

Full Text Available Tactile perception is inhibited during goal-directed reaching movements (sensory suppression. Here, participants performed simple reaching or exploratory movements (where contact with the table surface was maintained. We measured tactile discrimination thresholds for vibratory stimuli delivered to participants' wrists while executing the movement, and while at rest. Moreover, we measured discrimination performance (in a same vs. different task for the materials covering the table surface, during the execution of the different movements. The threshold and discrimination tasks could be performed either singly or together, both under active movement and passive conditions (ie, no movement required, but with tactile stimulation. Thresholds measured at rest were significantly lower than thresholds measured during both active movements and passive touches. This provides a clear indication of sensory suppression during movement execution. Moreover, the discrimination data revealed main effects of task (single vs. dual, movement execution type (passive vs. active, and movement type (reach vs. exploration: Discrimination performance was significantly higher under conditions of single-tasking, active movements, as well as exploratory movements. Therefore, active movement of the hand with the purpose of gaining tactual information about the surface of the table gives rise to enhanced performance, thus suggesting that we feel more when we need to; It would appear that tactual information is prioritized when relevant for the movement being executed.

Crystallite Size Effect on Thermal Conductive Properties of Nonwoven Nanocellulose Sheets.

Science.gov (United States)

Uetani, Kojiro; Okada, Takumi; Oyama, Hideko T

2015-07-13

The thermal conductive properties, including the thermal diffusivity and resultant thermal conductivity, of nonwoven nanocellulose sheets were investigated by separately measuring the thermal diffusivity of the sheets in the in-plane and thickness directions with a periodic heating method. The cross-sectional area (or width) of the cellulose crystallites was the main determinant of the thermal conductive properties. Thus, the results strongly indicate that there is a crystallite size effect on phonon conduction within the nanocellulose sheets. The results also indicated that there is a large interfacial thermal resistance between the nanocellulose surfaces. The phonon propagation velocity (i.e., the sound velocity) within the nanocellulose sheets was estimated to be ∼800 m/s based on the relationship between the thermal diffusivities and crystallite widths. The resulting in-plane thermal conductivity of the tunicate nanocellulose sheet was calculated to be ∼2.5 W/mK, markedly higher than other plastic films available for flexible electronic devices.

Light sensitive memristor with bi-directional and wavelength-dependent conductance control

Energy Technology Data Exchange (ETDEWEB)

Maier, P.; Hartmann, F., E-mail: fabian.hartmann@physik.uni-wuerzburg.de; Emmerling, M.; Schneider, C.; Kamp, M.; Worschech, L. [Technische Physik and Wilhelm Conrad Röntgen Research Center for Complex Material Systems, Physikalisches Institut, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); Rebello Sousa Dias, M. [Departamento de Fisica, Universidade Federal de São Carlos, 13565-905 São Carlos, São Paulo (Brazil); Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Castelano, L. K.; Marques, G. E.; Lopez-Richard, V. [Departamento de Fisica, Universidade Federal de São Carlos, 13565-905 São Carlos, São Paulo (Brazil); Höfling, S. [Technische Physik and Wilhelm Conrad Röntgen Research Center for Complex Material Systems, Physikalisches Institut, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS (United Kingdom)

2016-07-11

We report the optical control of localized charge on positioned quantum dots in an electro-photo-sensitive memristor. Interband absorption processes in the quantum dot barrier matrix lead to photo-generated electron-hole-pairs that, depending on the applied bias voltage, charge or discharge the quantum dots and hence decrease or increase the conductance. Wavelength-dependent conductance control is observed by illumination with red and infrared light, which leads to charging via interband and discharging via intraband absorption. The presented memristor enables optical conductance control and may thus be considered for sensory applications in artificial neural networks as light-sensitive synapses or optically tunable memories.

Light sensitive memristor with bi-directional and wavelength-dependent conductance control

International Nuclear Information System (INIS)

Maier, P.; Hartmann, F.; Emmerling, M.; Schneider, C.; Kamp, M.; Worschech, L.; Rebello Sousa Dias, M.; Castelano, L. K.; Marques, G. E.; Lopez-Richard, V.; Höfling, S.

2016-01-01

We report the optical control of localized charge on positioned quantum dots in an electro-photo-sensitive memristor. Interband absorption processes in the quantum dot barrier matrix lead to photo-generated electron-hole-pairs that, depending on the applied bias voltage, charge or discharge the quantum dots and hence decrease or increase the conductance. Wavelength-dependent conductance control is observed by illumination with red and infrared light, which leads to charging via interband and discharging via intraband absorption. The presented memristor enables optical conductance control and may thus be considered for sensory applications in artificial neural networks as light-sensitive synapses or optically tunable memories.

Method of forming electronically conducting polymers on conducting and nonconducting substrates

Science.gov (United States)

Murphy, Oliver J. (Inventor); Hitchens, G. Duncan (Inventor); Hodko, Dalibor (Inventor); Clarke, Eric T. (Inventor); Miller, David L. (Inventor); Parker, Donald L. (Inventor)

2001-01-01

The present invention provides electronically conducting polymer films formed from photosensitive formulations of pyrrole and an electron acceptor that have been selectively exposed to UV light, laser light, or electron beams. The formulations may include photoinitiators, flexibilizers, solvents and the like. These solutions can be used in applications including printed circuit boards and through-hole plating and enable direct metallization processes on non-conducting substrates. After forming the conductive polymer patterns, a printed wiring board can be formed by sensitizing the polymer with palladium and electrolytically depositing copper.

Study of temperature-dependent charge conduction in silicon-nanocrystal/SiO_2 multilayers

International Nuclear Information System (INIS)

Mavilla, Narasimha Rao; Chavan, Vinayak; Solanki, Chetan Singh; Vasi, Juzer

2016-01-01

Silicon-nanocrystals (Si-NCs) realized by SiO_x _ 8 MV/cm; independent of temperature), while for lower electric fields (5–8 MV/cm) at higher temperatures, the trap-related Generalized Poole–Frenkel (GPF) is dominant. This signified the role of traps in modifying the conduction in bulk ICPCVD SiO_2 films. We then present the conduction in ML samples. For multilayer samples with SiO_2 sublayer thickness of 1.5 nm and 2.5 nm, Direct Tunneling (DT) is observed to be dominant, while for SiO_2 sublayer thickness of 3.5 nm, Space Charge Limited Conduction (SCLC) with exponential trap distribution is found to be the dominant conduction mechanism. This signifies the role of traps in modifying the conduction in Si-NC multilayer samples and SiO_2 sublayer thickness dependence. - Highlights: • Electrical conduction in SiO_2 film & Si-nanocrystal layers (Si-NCs) is reported. • SiO_2/SiO_x multilayer based Si-NCs were realized by Inductively Coupled plasma CVD. • For SiO_2 film, Fowler–Nordheim tunneling & Generalized Poole–Frenkel are observed. • For Si-NCs with thin SiO_2 sublayers (< 2.5 nm) Direct Tunneling is dominant. • For Si-NCs with 3.5 nm SiO_2 sublayers Space Charge Limited Conduction is dominant.

Relevance of Conduction Disorders in Bachmann's Bundle During Sinus Rhythm in Humans.

Science.gov (United States)

Teuwen, Christophe P; Yaksh, Ameeta; Lanters, Eva A H; Kik, Charles; van der Does, Lisette J M E; Knops, Paul; Taverne, Yannick J H J; van de Woestijne, Pieter C; Oei, Frans B S; Bekkers, Jos A; Bogers, Ad J J C; Allessie, Maurits A; de Groot, Natasja M S

2016-05-01

Bachmann's bundle (BB) is considered to be the main route of interatrial conduction and to play a role in development of atrial fibrillation (AF). The goals of this study are to characterize the presence of conduction disorders in BB during sinus rhythm and to study their relation with AF. High-resolution epicardial mapping (192 unipolar electrodes, interelectrode distance: 2 mm) of sinus rhythm was performed in 185 patients during coronary artery bypass surgery of whom 13 had a history of paroxysmal AF. Continuous rhythm monitoring was used to detect postoperative AF during the first 5 postoperative days. In 67% of the patients, BB was activated from right to left; in the remaining patients from right and middle (21%), right, central, and left (8%), or central (4%) site. Mean effective conduction velocity was 89 cm/s. Conduction block was present in most patients (75%; median 1.1%, range 0-12.8) and was higher in patients with paroxysmal AF compared with patients without a history of AF (3.2% versus 0.9%; P=0.03). A high amount of conduction block (>4%) was associated with de novo postoperative AF (P=0.02). Longitudinal lines of conduction block >10 mm were also associated with postoperative AF (P=0.04). BB may be activated through multiple directions, but the predominant route of conduction is from right to left. Conduction velocity across BB is around 90 cm/s. Conduction is blocked in both longitudinal and transverse direction in the majority of patients. Conduction disorders, particularly long lines of longitudinal conduction block, are more pronounced in patients with AF episodes. © 2016 American Heart Association, Inc.

Conductivity enhancement induced by casting of polymer electrolytes under a magnetic field

International Nuclear Information System (INIS)

Kovarsky, R.; Golodnitsky, D.; Peled, E.; Khatun, S.; Stallworth, P.E.; Greenbaum, S.; Greenbaum, A.

2011-01-01

Highlights: ► Ordering of polymer electrolytes under applied magnetic field. ► Positive effect of nanosize ferromagnetic filler. ► Structure-ion conductivity interrelationship. - Abstract: We recently presented a procedure for orienting the polyethylene-oxide (PEO) helices in a direction perpendicular to the film plane by casting the polymer electrolytes (PE) under a magnetic field (MF). Here we study the influence of magnetic fields of different strengths and configurations on the structural properties and ionic conductivity of concentrated LiCF 3 SO 3 (LiTf) and LiAsF 6 :P(EO) pristine and composite polymer electrolytes containing γ-Fe 2 O 3 nanoparticles. Some data of LiI:P(EO) system are shown for comparison. We suggest that the effect of type of salt (LiI, LiTf and LiAsF 6 ) on the structure–conductivity relationship of the polymer electrolytes cast under magnetic field is closely connected to the crystallinity of the PEO–LiX system. It was found that the higher the content of the crystalline phase and the size of spherulites in the typically cast salt-polymer system, the stronger the influence of the magnetic field on the conductivity enhancement when the electrolyte is cast and dried under MF. Casting of the PE from a high-dielectric-constant solvent results in disentanglement of the PEO chains, which facilitates even more the perpendicular orientation of helices under applied MF. The enhancement of ionic conductivity was appreciably higher in the PEs cast under strong NdFeB magnets than under SmCo. Both bulk (intrachain) and grain-boundary conductivities increase when a MF is applied, but the improvement in the grain-boundary conductivity – associated with ion-hopping between polymer chains – is more pronounced. For LiAsF 6 :(PEO) 3 at 65 °C, the interchain conductivity increased by a factor of 75, while the intrachain conductivity increased by a factor of 11–14. At room temperature, the SEI resistance of these PEs, cast under NdFeB HMF

75 FR 53611 - Direct Investment Surveys: BE-577, Quarterly Survey of U.S. Direct Investment Abroad-Direct...

Science.gov (United States)

2010-09-01

...] RIN 0691-AA75 Direct Investment Surveys: BE-577, Quarterly Survey of U.S. Direct Investment Abroad--Direct Transactions of U.S. Reporter With Foreign Affiliate AGENCY: Bureau of Economic Analysis, Commerce...-577 quarterly survey of U.S. direct investment abroad. The survey is conducted quarterly and obtains...

The effect of radiation induced electrical conductivity (RIC) on the thermal conductivity

International Nuclear Information System (INIS)

White, D.P.

1993-01-01

Microwave heating of plasmas in fusion reactors requires the development of microwave windows through which the microwaves can pass without great losses. The degradation of the thermal conductivity of alumina in a radiation environment is an important consideration in reliability studies of these microwave windows. Several recent papers have addressed this question at higher temperatures and at low temperatures. The current paper extends the low temperature calculations to determine the effect of phonon-electron scattering on the thermal conductivity at 77 K due to RIC. These low temperature calculations are of interest because the successful application of high power (>1 MW) windows for electron cyclotron heating systems in fusion reactors will most likely require cryogenic cooling to take advantage of the low loss tangent and higher thermal conductivity of candidate window materials at these temperatures

Thermal cure effects on electromechanical properties of conductive wires by direct ink write for 4D printing and soft machines

Science.gov (United States)

Mu, Quanyi; Dunn, Conner K.; Wang, Lei; Dunn, Martin L.; Qi, H. Jerry; Wang, Tiejun

2017-04-01

Recent developments in soft materials and 3D printing are promoting the rapid development of novel technologies and concepts, such as 4D printing and soft machines, that in turn require new methods for fabricating conductive materials. Despite the ubiquity of silver nanoparticles (NPs) in the conducting electrodes of printed electronic devices, their potential use in stretchable conductors has not been fully explored in 4D printing and soft machines. This paper studies the effect of thermal cure conditions on conductivity and electro-mechanical behaviors of silver ink by the direct ink write (DIW) printing approach. We found that the electro-mechanical properties of silver wires can be tailored by controlling cure time and cure temperature to achieve conductivity as well as stretchability. For the silver NP ink we used in the experiments, silver wires cured at 80 °C for 10-30 min have conductivity >1% bulk silver, Young’s modulus printed silver ink patterns on the surface of 3D printed polymer parts, with the future goal of constructing fully 3D printed arbitrarily formed soft and stretchable devices and of applying them to 4D printing. We demonstrated a fully printed functional soft-matter sensor and a circuit element that can be stretched by as much as 45%.

Reputation in Higher Education

DEFF Research Database (Denmark)

Martensen, Anne; Grønholdt, Lars

2005-01-01

leaders of higher education institutions to set strategic directions and support their decisions in an effort to create even better study programmes with a better reputation. Finally, managerial implications and directions for future research are discussed.Keywords: Reputation, image, corporate identity......The purpose of this paper is to develop a reputation model for higher education programmes, provide empirical evidence for the model and illustrate its application by using Copenhagen Business School (CBS) as the recurrent case. The developed model is a cause-and-effect model linking image...

Mixed oxygen ion/electron-conducting ceramics for oxygen separation

Energy Technology Data Exchange (ETDEWEB)

Stevenson, J.W.; Armstrong, T.R.; Armstrong, B.L. [Pacific Northwest National Lab., Richland, WA (United States)

1996-08-01

Mixed oxygen ion and electron-conducting ceramics are unique materials that can passively separate high purity oxygen from air. Oxygen ions move through a fully dense ceramic in response to an oxygen concentration gradient, charge-compensated by an electron flux in the opposite direction. Compositions in the system La{sub 1{minus}x}M{sub x}Co{sub 1{minus}y{minus}z}Fe{sub y}N{sub z}O{sub 3{minus}{delta}}, perovskites where M=Sr, Ca, and Ba, and N=Mn, Ni, Cu, Ti, and Al, have been prepared and their electrical, oxygen permeation, oxygen vacancy equilibria, and catalytic properties evaluated. Tubular forms, disks, and asymmetric membrane structures, a thin dense layer on a porous support of the same composition, have been fabricated for testing purposes. In an oxygen partial gradient, the passive oxygen flux through fully dense structures was highly dependent on composition. An increase in oxygen permeation with increased temperature is attributed to both enhanced oxygen vacancy mobility and higher vacancy populations. Highly acceptor-doped compositions resulted in oxygen ion mobilities more than an order of magnitude higher than yttria-stabilized zirconia. The mixed conducting ceramics have been utilized in a membrane reactor configuration to upgrade methane to ethane and ethylene. Conditions were established to balance selectivity and throughput in a catalytic membrane reactor constructed from mixed conducting ceramics.

The Higher Order Structure of Environmental Attitudes: A Cross-Cultural Examination

Directory of Open Access Journals (Sweden)

Taciano L. Milfont

2010-01-01

Full Text Available Past research has suggested that Preservation and Utilization are the two higher order dimensions forming the hierarchical structure of environmental attitudes. This means that these two higher order dimensions could group all kinds of perceptions or beliefs regarding the natural environment people have. A crosscultural study was conducted in Brazil, New Zealand, and South Africa to test this hierarchical structure of environmental attitudes. Results from single- and multi-group confirmatory factor analyses demonstrated that environmental attitudes are a multidimensional construct, and that their first-order factors associate to each other to form a vertical structure. However, the question whether the vertical structure comprise a single higher order factor or two higher order factors still remains unanswered. These results are discussed and directions for future research trying to demonstrate that Preservation and Utilization, taken as distinct second-order environmental attitudes factors, are more empirically meaningful than a single and generalised environmental attitudes higher order factor are presented.

Impact of uncertain head tissue conductivity in the optimization of transcranial direct current stimulation for an auditory target

Science.gov (United States)

Schmidt, Christian; Wagner, Sven; Burger, Martin; van Rienen, Ursula; Wolters, Carsten H.

2015-08-01

Objective. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique to modify neural excitability. Using multi-array tDCS, we investigate the influence of inter-individually varying head tissue conductivity profiles on optimal electrode configurations for an auditory cortex stimulation. Approach. In order to quantify the uncertainty of the optimal electrode configurations, multi-variate generalized polynomial chaos expansions of the model solutions are used based on uncertain conductivity profiles of the compartments skin, skull, gray matter, and white matter. Stochastic measures, probability density functions, and sensitivity of the quantities of interest are investigated for each electrode and the current density at the target with the resulting stimulation protocols visualized on the head surface. Main results. We demonstrate that the optimized stimulation protocols are only comprised of a few active electrodes, with tolerable deviations in the stimulation amplitude of the anode. However, large deviations in the order of the uncertainty in the conductivity profiles could be noted in the stimulation protocol of the compensating cathodes. Regarding these main stimulation electrodes, the stimulation protocol was most sensitive to uncertainty in skull conductivity. Finally, the probability that the current density amplitude in the auditory cortex target region is supra-threshold was below 50%. Significance. The results suggest that an uncertain conductivity profile in computational models of tDCS can have a substantial influence on the prediction of optimal stimulation protocols for stimulation of the auditory cortex. The investigations carried out in this study present a possibility to predict the probability of providing a therapeutic effect with an optimized electrode system for future auditory clinical and experimental procedures of tDCS applications.

Community Violence Exposure and Conduct Problems in Children and Adolescents with Conduct Disorder and Healthy Controls

OpenAIRE

Linda Kersten; Noortje Vriends; Martin Steppan; Nora M. Raschle; Martin Praetzlich; Helena Oldenhof; Robert Vermeiren; Lucres Jansen; Katharina Ackermann; Anka Bernhard; Anne Martinelli; Karen Gonzalez-Madruga; Ignazio Puzzo; Amy Wells; Jack C. Rogers

2017-01-01

Exposure to community violence through witnessing or being directly victimized has been associated with conduct problems in a range of studies. However, the relationship between community violence exposure (CVE) and conduct problems has never been studied separately in healthy individuals and individuals with conduct disorder (CD). Therefore, it is not clear whether the association between CVE and conduct problems is due to confounding factors, because those with high conduct problems also te...

A pore water conductivity sensor

NARCIS (Netherlands)

Hilhorst, M.A.

2001-01-01

The electrical permittivity and conductivity of the bulk soil are a function of the permittivity and conductivity of the pore water. For soil water contents higher than 0.10 both functions are equal, facilitating in situ conductivity measurements of the pore water. A novel method is described, based

Heat Transfer in Directional Water Transport Fabrics

Directory of Open Access Journals (Sweden)

Chao Zeng

2016-10-01

Full Text Available Directional water transport fabrics can proactively transfer moisture from the body. They show great potential in making sportswear and summer clothing. While moisture transfer has been previously reported, heat transfer in directional water transport fabrics has been little reported in research literature. In this study, a directional water transport fabric was prepared using an electrospraying technique and its heat transfer properties under dry and wet states were evaluated, and compared with untreated control fabric and the one pre-treated with NaOH. All the fabric samples showed similar heat transfer features in the dry state, and the equilibrium temperature in the dry state was higher than for the wet state. Wetting considerably enhanced the thermal conductivity of the fabrics. Our studies indicate that directional water transport treatment assists in moving water toward one side of the fabric, but has little effect on thermal transfer performance. This study may be useful for development of “smart” textiles for various applications.

Development of electrical-erosion instrument for direct write micro-patterning on large area conductive thin films

Energy Technology Data Exchange (ETDEWEB)

Álvarez, Ángel Luis; Coya, Carmen; García-Vélez, Miguel [Departamento Teoría de la Señal y Comunicaciones, Sistemas Telemáticos y Computación, Escuela Técnica Superior de Ingeniería de Telecomunicación, Universidad Rey Juan Carlos, Fuenlabrada, Madrid 28943 (Spain)

2015-08-15

We have developed a complete instrument to perform direct, dry, and cost-effective lithography on conductive materials, based on localized electrical discharges, which avoids using masks or chemicals typical of conventional photolithography. The technique is considered fully compatible with substrate transport based systems, like roll-to-roll technology. The prototype is based on two piezo nano-steppers coupled to three linear micro-stages to cover a large scale operation from micrometers to centimeters. The operation mode consists of a spring probe biased at low DC voltage with respect to a grounded conductive layer. The tip slides on the target layer keeping contact with the material in room conditions, allowing continuous electric monitoring of the process, and also real-time tilt correction via software. The sliding tip leaves an insulating path (limited by the tip diameter) along the material, enabling to draw electrically insulated tracks and pads. The physical principle of operation is based in the natural self-limitation of the discharge due to material removal or insulation. The so produced electrical discharges are very fast, in the range of μs, so features may be performed at speeds of few cm/s, enabling scalability to large areas. The instrument has been tested on different conducting materials as gold, indium tin oxide, and aluminum, allowing the fabrication of alphanumeric displays based on passive matrix of organic light emitting diodes without the use of masks or photoresists. We have verified that the highest potential is achieved on graphene, where no waste material is detected, producing excellent well defined edges. This allows manufacturing graphene micro-ribbons with a high aspect ratio up to 1200:1.

Electronic Conductivity of Doped-Lanthanum Gallate Electrolytes

Science.gov (United States)

Yamaji, Katsuhiko; Xiong, Yue Ping; Kishimoto, Haruo; Horita, Teruhisa; Sakai, Natsuko; Brito, Manuel E.; Yokokawa, Harumi

Electronic conductivity of doped lanthanum gallate electrolytes were determined by using a Hebb-Wagner type polarization cell. Electronic conductivity of cobalt-doped, La0.8Sr0.2Ga0.8Mg0.15Co0.5O3-δ (LSGMC), and non cobalt-doped, La0.8Sr0.2Ga0.8Mg0.2O2.8 (LSGM8282), were measured as a function of oxygen partial pressures. The electronic conductivity of LSGM8282 showed a linear dependence on p(O2)1/4 in the higher p(O2) region, which is attributed to the electronic hole conductivity. The electronic conductivity of LSGMC showed a linear dependence on p(O2)1/6 in the higher p(O2) region. LSGMC has higher electronic conductivity than LSGM, and the conductivity was not clearly changed with temperatures between 600 and 800 °C. In lower p(O2) region, the electronic conductivity data have poor reproducibility and did not show any dependence on p(O2) because of the degradation of the electrolytes in severe reducing atmospheres.

Integrating Financial Aid and Financial Policies: Case Studies from Five States. Changing Direction: Integrating Higher Education Financial Aid and Financing Policies.

Science.gov (United States)

Western Interstate Commission for Higher Education, Boulder, CO.

This report is a collection of five state case studies comprising a major component of the first phase of the project, "Changing Direction: Integrating Higher Education Financial Aid and Financing Policies." The project explored state-level strategies to better align financing and financial aid policies and support more informed decision…

High temperature thermal conductivity measurements of UO/sub 2/ by Direct Electrical Heating. Final report. [MANTRA-III

Energy Technology Data Exchange (ETDEWEB)

Bassett, B

1980-10-01

High temperature properties of reactor type UO/sub 2/ pellets were measured using a Direct Electrical Heating (DEH) Facility. Modifications to the experimental apparatus have been made so that successful and reproducible DEH runs may be carried out while protecting the pellets from oxidation at high temperature. X-ray diffraction measurements on the UO/sub 2/ pellets have been made before and after runs to assure that sample oxidation has not occurred. A computer code has been developed that will model the experiment using equations that describe physical properties of the material. This code allows these equations to be checked by comparing the model results to collected data. The thermal conductivity equation for UO/sub 2/ proposed by Weilbacher has been used for this analysis. By adjusting the empirical parameters in Weilbacher's equation, experimental data can be matched by the code. From the several runs analyzed, the resulting thermal conductivity equation is lambda = 1/4.79 + 0.0247T/ + 1.06 x 10/sup -3/ exp(-1.62/kT/) - 4410. exp(-3.71/kT/) where lambda is in w/cm K, k is the Boltzman constant, and T is the temperature in Kelvin.

Higher-Order Program Generation

DEFF Research Database (Denmark)

Rhiger, Morten

for OCaml, a dialect of ML, that provides run-time code generation for OCaml programs. We apply these byte-code combinators in semantics-directed compilation for an imperative language and in run-time specialization using type-directed partial evaluation. Finally, we present an approach to compiling goal......This dissertation addresses the challenges of embedding programming languages, specializing generic programs to specific parameters, and generating specialized instances of programs directly as executable code. Our main tools are higher-order programming techniques and automatic program generation....... It is our thesis that they synergize well in the development of customizable software. Recent research on domain-specific languages propose to embed them into existing general-purpose languages. Typed higher-order languages have proven especially useful as meta languages because they provide a rich...

Cobalt Oxide Porous Nanofibers Directly Grown on Conductive Substrate as a Binder/Additive-Free Lithium-Ion Battery Anode with High Capacity.

Science.gov (United States)

Liu, Hao; Zheng, Zheng; Chen, Bochao; Liao, Libing; Wang, Xina

2017-12-01

In order to reduce the amount of inactive materials, such as binders and carbon additives in battery electrode, porous cobalt monoxide nanofibers were directly grown on conductive substrate as a binder/additive-free lithium-ion battery anode. This electrode exhibited very high specific discharging/charging capacities at various rates and good cycling stability. It was promising as high capacity anode materials for lithium-ion battery.

Temporal and vertical variations radon and its progeny related to atmospheric electrical conductivity

International Nuclear Information System (INIS)

Pruthvi Rani, K.S.; Chandrashekara, M.S.; Paramesh, L.

2015-01-01

Atmospheric radon, its progeny, electrical conductivity and meteorological parameters such as wind, temperature, humidity, pressure and rainfall were continuously monitored during 2012 to 2014 at one location in Mysuru city. The annual mean atmospheric radon concentration at the study location was found to be 16.4 Bqm -3 . The diurnal cycle of radon and its progeny show a peak in the early morning hours followed by a drastic decrease after sunrise and rising to a second peak in the afternoon. It was found that the stability of the atmosphere and ambient temperature played a major role in the diurnal variations. Higher concentrations of radon and its progeny were observed in winter and lower values in summer. This may due to the variations in origin of air mass and meteorological parameters. Wind direction analyses reveal that in sectors with air which has spent a longer period over the granitic region and low wind speeds will lead to higher concentrations of radon. Atmospheric electrical conductivity near the ground is mainly due to the ionization from radon and its progeny. The diurnal variations of conductivity and ionization rate due to radon and its individual progeny were of similar trend. In addition its significant dependence on meteorological parameters is confirmed. The vertical variations of atmospheric electrical conductivity were studied at different heights up to 250 m from the ground level. Higher values were observed close to the ground surface, there was a rapid reduction up to about 10 m and beyond that the conductivity gradually decreases. The diurnal conductivity cycle is studied at 10 m and 100 m showed the expected similar trend at both the heights but early morning maxima were considerably different, this confirms the accumulation of radon gas close to the ground surface during night time leading to increase of conductivity values. (author)

Ecological Risk Assessment of Genetically Modified Higher Plants (GMHP)

DEFF Research Database (Denmark)

Kjær, C.; Damgaard, C.; Kjellsson, G.

Preface This publication is a first version of a manual identifying the data needs for ecological risk assessment of genetically modified higher plants (GMHP). It is the intention of the authors to stimulate further discussion of what data are needed in order to conduct a proper ecological risk...... of the project Biotechnology: elements in environmental risk assessment of genetically modified plants. December 1999 Christian Kjær Introduction In ecological risk assessment of transgenic plants, information on a wide range of subjects is needed for an effective and reliable assessment procedure...... in the amendment to the directive. This report suggests a structured way to identify the type of data needed to perform a sound ecological risk assessment for genetically modified higher plants (GMHP). The identified data types are intended to support the evaluation of the following risks: risk of invasion...

Electronic structure effects on stability and quantum conductance in 2D gold nanowires

International Nuclear Information System (INIS)

Kashid, Vikas; Shah, Vaishali; Salunke, H. G.

2011-01-01

In this study, we have investigated the stability and conductivity of unsupported, two-dimensional infinite gold nanowires using ab initio density functional theory (DFT). Two-dimensional ribbon-like nanowires with 1–5 rows of gold atoms in the non-periodic direction and with different possible structures have been considered. The nanowires with >2 rows of atoms exhibit dimerization, similar to finite wires, along the non-periodic direction. Our results show that in these zero thickness nanowires, the parallelogram motif is the most stable. A comparison between parallelogram- and rectangular-shaped nanowires of increasing width indicates that zero thickness (111) oriented wires have a higher stability over (100). A detailed analysis of the electronic structure, reveals that the (111) oriented structures show increased delocalization of s and p electrons in addition to a stronger delocalization of the d electrons and hence are the most stable. The density of states show that the nanowires are metallic and conducting except for the double zigzag structure, which is semiconducting. Conductance calculations show transmission for a wide range of energies in all the stable nanowires with more than two rows of atoms. The conductance channels are not purely s and have strong contributions from the d levels, and weak contributions from the p levels.

Tritium conductivity and isotope effect in proton-conducting perovskites

International Nuclear Information System (INIS)

Mukundan, R.; Brosha, E.L.; Birdsell, S.A.; Costello, A.L.; Garzon, F.H.; Willms, R.S.

1999-01-01

The tritium ion conductivities of SrZr 0.9 Yb 0.1 O 2.95 and BaCe 0.9 Yb 0.1 O 2.95 have been measured by ac impedance analysis. The high tritium conductivity of these perovskites could potentially lead to their application as an electrochemical membrane for the recovery of tritium from tritiated gas streams. The conductivities of these perovskites, along with SrCe 0.95 Yb 0.05 O 2.975 , were also measured in hydrogen- and deuterium-containing atmospheres to illustrate the isotope effect. For the strontium zirconate and barium cerate samples, the impedance plot consists of two clearly resolved arcs, a bulk and a grain boundary arc, in the temperature range 50--350 C. However, for the strontium cerate sample, the clear resolution of the bulk conductivity was not possible and only the total conductivity was measurable. Thus, the isotope effect was clearly established only for the strontium zirconate and barium cerate samples. The decrease in bulk conductivity with increasing isotope mass was found to be a result of an increase in the activation energy for conduction accompanied by a decrease in the pre-exponential factor. Since the concentration of the mobile species (H+, D+, or T+) should remain relatively constant at T < 350 C, this increase in activation energy is directly attributable to the increased activation energy for the isotope mobility

The n-type conduction of indium-doped Cu{sub 2}O thin films fabricated by direct current magnetron co-sputtering

Energy Technology Data Exchange (ETDEWEB)

Cai, Xing-Min; Su, Xiao-Qiang; Ye, Fan, E-mail: yefan@szu.edu.cn; Wang, Huan; Tian, Xiao-Qing; Zhang, Dong-Ping; Fan, Ping; Luo, Jing-Ting; Zheng, Zhuang-Hao; Liang, Guang-Xing [Institute of Thin Film Physics and Applications, School of Physical Science and Technology and Shenzhen Key Laboratory of Sensor Technology, Shenzhen University, Shenzhen 518060 (China); Roy, V. A. L. [Center of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Kowloon Tong, Hong Kong (China)

2015-08-24

Indium-doped Cu{sub 2}O thin films were fabricated on K9 glass substrates by direct current magnetron co-sputtering in an atmosphere of Ar and O{sub 2}. Metallic copper and indium disks were used as the targets. X-ray diffraction showed that the diffraction peaks could only be indexed to simple cubic Cu{sub 2}O, with no other phases detected. Indium atoms exist as In{sup 3+} in Cu{sub 2}O. Ultraviolet-visible spectroscopy showed that the transmittance of the samples was relatively high and that indium doping increased the optical band gaps. The Hall effect measurement showed that the samples were n-type semiconductors at room temperature. The Seebeck effect test showed that the films were n-type semiconductors near or over room temperature (<400 K), changing to p-type at relatively high temperatures. The conduction by the samples in the temperature range of the n-type was due to thermal band conduction and the donor energy level was estimated to be 620.2–713.8 meV below the conduction band. The theoretical calculation showed that indium doping can raise the Fermi energy level of Cu{sub 2}O and, therefore, lead to n-type conduction.

Aspirated capacitor measurements of air conductivity and ion mobility spectra

International Nuclear Information System (INIS)

Aplin, K.L.

2005-01-01

Measurements of ions in atmospheric air are used to investigate atmospheric electricity and particulate pollution. Commonly studied ion parameters are (1) air conductivity, related to the total ion number concentration, and (2) the ion mobility spectrum, which varies with atmospheric composition. The physical principles of air ion instrumentation are long established. A recent development is the computerized aspirated capacitor, which measures ions from (a) the current of charged particles at a sensing electrode, and (b) the rate of charge exchange with an electrode at a known initial potential, relaxing to a lower potential. As the voltage decays, only ions of higher and higher mobility are collected by the central electrode and contribute to the further decay of the voltage. This enables extension of the classical theory to calculate ion mobility spectra by inverting voltage decay time series. In indoor air, ion mobility spectra determined from both the voltage decay inversion, and an established voltage switching technique, were compared and shown to be of similar shape. Air conductivities calculated by integration were: 5.3±2.5 and 2.7±1.1 fSm -1 , respectively, with conductivity determined to be 3 fSm -1 by direct measurement at a constant voltage. Applications of the relaxation potential inversion method include air ion mobility spectrum retrieval from historical data, and computation of ion mobility spectra in planetary atmospheres

Direct measurement of the microscale conductivity of conjugated polymer monolayers

DEFF Research Database (Denmark)

Bøggild, Peter; Grey, Francois; Hassenkam, T.

2000-01-01

The in-plane conductivity of conjugated polymer monolayers is mapped here for the first time on the microscale using a novel scanning micro four-point probe (see Figure). The probe allows the source, drain, and voltage electrodes to be positioned within the same domain and the mapping results...

Conductivity of higher dimensional holographic superconductors with nonlinear electrodynamics

Science.gov (United States)

Sheykhi, Ahmad; Hashemi Asl, Doa; Dehyadegari, Amin

2018-06-01

We investigate analytically as well as numerically the properties of s-wave holographic superconductors in d-dimensional spacetime and in the presence of Logarithmic nonlinear electrodynamics. We study three aspects of this kind of superconductors. First, we obtain, by employing analytical Sturm-Liouville method as well as numerical shooting method, the relation between critical temperature and charge density, ρ, and disclose the effects of both nonlinear parameter b and the dimensions of spacetime, d, on the critical temperature Tc. We find that in each dimension, Tc /ρ 1 / (d - 2) decreases with increasing the nonlinear parameter b while it increases with increasing the dimension of spacetime for a fixed value of b. Then, we calculate the condensation value and critical exponent of the system analytically and numerically and observe that in each dimension, the dimensionless condensation get larger with increasing the nonlinear parameter b. Besides, for a fixed value of b, it increases with increasing the spacetime dimension. We confirm that the results obtained from our analytical method are in agreement with the results obtained from numerical shooting method. This fact further supports the correctness of our analytical method. Finally, we explore the holographic conductivity of this system and find out that the superconducting gap increases with increasing either the nonlinear parameter or the spacetime dimension.

Thermal conductivity of electrospun polyethylene nanofibers.

Science.gov (United States)

Ma, Jian; Zhang, Qian; Mayo, Anthony; Ni, Zhonghua; Yi, Hong; Chen, Yunfei; Mu, Richard; Bellan, Leon M; Li, Deyu

2015-10-28

We report on the structure-thermal transport property relation of individual polyethylene nanofibers fabricated by electrospinning with different deposition parameters. Measurement results show that the nanofiber thermal conductivity depends on the electric field used in the electrospinning process, with a general trend of higher thermal conductivity for fibers prepared with stronger electric field. Nanofibers produced at a 45 kV electrospinning voltage and a 150 mm needle-collector distance could have a thermal conductivity of up to 9.3 W m(-1) K(-1), over 20 times higher than the typical bulk value. Micro-Raman characterization suggests that the enhanced thermal conductivity is due to the highly oriented polymer chains and enhanced crystallinity in the electrospun nanofibers.

Anistropically varying conductivity in irreversible electroporation simulations.

Science.gov (United States)

Labarbera, Nicholas; Drapaca, Corina

2017-11-01

One recent area of cancer research is irreversible electroporation (IRE). Irreversible electroporation is a minimally invasive procedure where needle electrodes are inserted into the body to ablate tumor cells with electricity. The aim of this paper is to propose a mathematical model that incorporates a tissue's conductivity increasing more in the direction of the electrical field as this has been shown to occur in experiments. It was necessary to mathematically derive a valid form of the conductivity tensor such that it is dependent on the electrical field direction and can be easily implemented into numerical software. The derivation of a conductivity tensor that can take arbitrary functions for the conductivity in the directions tangent and normal to the electrical field is the main contribution of this paper. Numerical simulations were performed for isotropic-varying and anisotropic-varying conductivities to evaluate the importance of including the electrical field's direction in the formulation for conductivity. By starting from previously published experimental results, this paper derived a general formulation for an anistropic-varying tensor for implementation into irreversible electroporation modeling software. The anistropic-varying tensor formulation allows the conductivity to take into consideration both electrical field direction and magnitude, as opposed to previous published works that only took into account electrical field magnitude. The anisotropic formulation predicts roughly a five percent decrease in ablation size for the monopolar simulation and approximately a ten percent decrease in ablation size for the bipolar simulations. This is a positive result as previously reported results found the isotropic formulation to overpredict ablation size for both monopolar and bipolar simulations. Furthermore, it was also reported that the isotropic formulation overpredicts the ablation size more for the bipolar case than the monopolar case. Thus, our

Future direction of direct writing

Science.gov (United States)

Kim, Nam-Soo; Han, Kenneth N.

2010-11-01

Direct write technology using special inks consisting of finely dispersed metal nanoparticles in liquid is receiving an undivided attention in recent years for its wide range of applicability in modern electronic industry. The application of this technology covers radio frequency identification-tag (RFID-tag), flexible-electronics, organic light emitting diodes (OLED) display, e-paper, antenna, bumpers used in flip-chip, underfilling, frit, miniresistance applications and biological uses, artificial dental applications and many more. In this paper, the authors have reviewed various direct write technologies on the market and discussed their advantages and shortfalls. Emphasis has given on microdispensing deposition write (MDDW), maskless mesoscale materials deposition (M3D), and ink-jet technologies. All of these technologies allow printing various patterns without employing a mask or a resist with an enhanced speed with the aid of computer. MDDW and M3D are capable of drawing patterns in three-dimension and MDDW, in particular, is capable of writing nanoinks with high viscosity. However, it is still far away for direct write to be fully implemented in the commercial arena. One of the hurdles to overcome is in manufacturing conductive inks which are chemically and physically stable, capable of drawing patterns with acceptable conductivity, and also capable of drawing patterns with acceptable adhesiveness with the substrates. The authors have briefly discussed problems involved in manufacturing nanometal inks to be used in various writing devices. There are numerous factors to be considered in manufacturing such inks. They are reducing agents, concentrations, oxidation, compact ability allowing good conductivity, and stability in suspension.

The Main Directions of Improving the Management of the Higher Education System

Directory of Open Access Journals (Sweden)

Terovanesov Mykhajlo R.

2017-04-01

Full Text Available The article is aimed at determining the mechanisms of improving the management of the system of higher education in the context of the current regulatory support, which will be the means to solve the problem of inefficient functioning, lack of financing, and low quality of higher education. The factors, causing negative impact on development of the higher education system were analyzed, the most important of which are the lack of financing and the shortcomings of the legal support of the education sector. It has been determined that a shortage of funds and lack of communication between the education sphere and employers reduces the efficiency of management of the system of higher education. The legal support of the educational activities requires improvement due to the declarative nature of individual provisions on the management of the system of higher education. Consideration of the legal factor is necessary for regulating the decentralization of management in the education sphere, improvement of financing, perfection of the system of control of the education quality. Ways for decentralizing the management of the education sphere, increasing its effectiveness, and improving the economic status of higher education institutions, have been suggested. The scientific-practical recommendations have been formulated to attract potential consumers of educational services to reforming the higher education system and increasing its effectiveness.

An FDTD Study of Errors in Magnetic Direction Finding of Lightning Due to the Presence of Conducting Structure Near the Field Measuring Station

Directory of Open Access Journals (Sweden)

Yosuke Suzuki

2016-07-01

Full Text Available Lightning electromagnetic fields in the presence of conducting (grounded structure having a height of 60 m and a square cross-section of 40 m × 40 m within about 100 m of the observation point are analyzed using the 3D finite-difference time-domain (FDTD method. Influence of the conducting structure on the two orthogonal components of magnetic field is analyzed, and resultant errors in the estimated lightning azimuth are evaluated. Influences of ground conductivity and lightning current waveshape parameters are also examined. When the azimuth vector passes through the center of conducting structure diagonally (e.g., azimuth angle is 45° or parallel to its walls (e.g., azimuth angle is 0°, the presence of conducting structure equally influences Hx and Hy, so that Hx/Hy is the same as in the absence of structure. Therefore, no azimuth error occurs in those configurations. When the conducting structure is not located on the azimuth vector, the structure influences Hx and Hy differently, with the resultant direction finding error being greater when the structure is located closer to the observation point.

Stay connected: Electrical conductivity of microbial aggregates.

Science.gov (United States)

Li, Cheng; Lesnik, Keaton Larson; Liu, Hong

2017-11-01

The discovery of direct extracellular electron transfer offers an alternative to the traditional understanding of diffusional electron exchange via small molecules. The establishment of electronic connections between electron donors and acceptors in microbial communities is critical to electron transfer via electrical currents. These connections are facilitated through conductivity associated with various microbial aggregates. However, examination of conductivity in microbial samples is still in its relative infancy and conceptual models in terms of conductive mechanisms are still being developed and debated. The present review summarizes the fundamental understanding of electrical conductivity in microbial aggregates (e.g. biofilms, granules, consortia, and multicellular filaments) highlighting recent findings and key discoveries. A greater understanding of electrical conductivity in microbial aggregates could facilitate the survey for additional microbial communities that rely on direct extracellular electron transfer for survival, inform rational design towards the aggregates-based production of bioenergy/bioproducts, and inspire the construction of new synthetic conductive polymers. Copyright © 2017 Elsevier Inc. All rights reserved.

Direct and Indirect Harassment Experiences and Burnout among Academic Faculty in Japan.

Science.gov (United States)

Takeuchi, Masumi; Nomura, Kyoko; Horie, Saki; Okinaga, Hiroko; Perumalswami, Chithra R; Jagsi, Reshma

2018-05-01

The purpose of this study is three-fold: (1) to compare harassment (sexual, gender, and academic harassment both directly and indirectly experienced - i.e. "directly harassed" and "have seen or heard of someone who experienced harassment", respectively) experienced by males and females, (2) to investigate whether such experiences correlate with burnout, and (3) to explore whether social support might mitigate any such relationship between harassment and burnout. This cross-sectional study was conducted at a private university in Japan in February 2014 and is based on a work-life balance survey obtained from 330 academic faculty members. We investigated the association between each of the six subcategories of harassment (direct and indirect forms of each of the three types) and burnout using general linear regression models; we then evaluated interactions between harassment and social support in these models. The prevalence of direct and indirect experiences of harassment was higher in females than in males for all three types of harassment. Males showed higher burnout scores if they had direct experiences of harassment. There were significant interactions between social support and the direct experience of harassment; high social support mitigated the effect size of direct harassment on burnout among males. Females showed higher burnout scores if they had indirect experiences of harassment. However, the same buffering effect of social support on burnout as observed in males was not observed in females. Direct harassment experiences increased the risk of burnout in males, and indirect harassment experiences increased burnout in females.

Comparative studies of the structure, morphology and electrical conductivity of polyaniline weakly doped with chlorocarboxylic acids

International Nuclear Information System (INIS)

Gmati, Fethi; Fattoum, Arbi; Bohli, Nadra; Dhaoui, Wadia; Mohamed, Abdellatif Belhadj

2007-01-01

We report the results of studies on two series of polyaniline (PANI), doped with dichloroacetic (DCA) and trichloroacetic (TCA) acids, respectively, at various doping rates and obtained by the in situ polymerization method. Samples were characterized by x-ray diffraction, scanning electron microscopy and conductivity measurements. The direct current (dc) and alternating current (ac) electrical conductivities of PANI salts have been investigated in the temperature range 100-310 K and frequency range 7-10 6 Hz. The results of this study indicate better chain ordering and higher conductivity for PANI doped with TCA. The dc conductivity of all samples is suitably fitted to Mott's three-dimensional variable-range hopping (VRH) model. Different Mott parameters such as characteristic temperature T 0 , density of states at the Fermi level (N(E F )), average hopping energy (W) and the average hopping distance (R) have been evaluated. The dependence of such values on the dopant acid used is discussed. At high frequencies, the ac conductivity follows the power law σ ac (ω,T) A(T)ω s(T,ω) , which is characteristic for charge transport in disordered materials by hopping or tunnelling processes. The observed increase in the frequency exponent s with temperature suggests that the small-polaron tunnelling model best describes the dominant ac conduction mechanism. A direct correlation between conductivity, structure and morphology was obtained in our systems

Exploiting both optical and electrical anisotropy in nanowire electrodes for higher transparency.

Science.gov (United States)

Dong, Jianjin; Goldthorpe, Irene A

2018-01-26

Transparent electrodes such as indium tin oxide and random meshes of silver nanowires (AgNWs) have isotropic in-plane properties. However, we show that imparting some alignment to AgNWs can create anisotropic transparency and electrical conductivity characteristics that may benefit many applications. For example, liquid crystal displays and the touch sensors on top of them often only need to be transparent to one type of polarized light as well as predominantly conductive in only one direction. Herein, AgNWs are slightly preferentially aligned during their deposition by rod coating. Compared to randomly oriented AgNW films, the alignment boosts the transparency to perpendicularly polarized light, as well as achieves a higher transparency for a given sheet resistance in one direction compared to randomly oriented AgNWs films. These factors together increase the transparency of a 16 Ω/sq electrode by 7.3 percentage points. The alignment technique is cheap and scalable, compatible with roll-to-roll processes, and most importantly does not require extra processing steps, as rod coating is already a standard process for AgNW electrode fabrication.

Study of temperature-dependent charge conduction in silicon-nanocrystal/SiO{sub 2} multilayers

Energy Technology Data Exchange (ETDEWEB)

Mavilla, Narasimha Rao; Chavan, Vinayak [National Centre for Photovoltaic Research and Education (NCPRE), Powai, Mumbai 400 076 (India); Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076 (India); Solanki, Chetan Singh [National Centre for Photovoltaic Research and Education (NCPRE), Powai, Mumbai 400 076 (India); Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076 (India); Vasi, Juzer [National Centre for Photovoltaic Research and Education (NCPRE), Powai, Mumbai 400 076 (India); Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076 (India)

2016-08-01

Silicon-nanocrystals (Si-NCs) realized by SiO{sub x} {sub <} {sub 2}/SiO{sub 2} multilayer (ML) approach have shown promise for realizing tightly-controlled dimensions, thus efficiently exploiting the size-dependent quantum effects for device applications. Unfortunately, the confining insulating barriers (SiO{sub 2} sublayers), instrumental for realizing quantum size effects in Si-NC MLs, can also hinder the charge conduction which is crucial for device applications including Si-NC based tandem solar cells and multi-exciton solar cells. Owing to this, a comprehensive study of conduction mechanisms has been carried out using a thorough analysis of temperature-dependent dark I-V measurements of SiO{sub 2} thin film and Si-NC multilayer samples fabricated by Inductively Coupled Plasma CVD (ICPCVD). As the ML samples consisted of interleaved SiO{sub 2} sublayers, current in SiO{sub 2} thin film has initially been studied to understand the conduction properties of bulk ICPCVD SiO{sub 2}. For 21 nm thick SiO{sub 2} film, conduction is observed to be dominated by Fowler–Nordheim (FN) tunneling for higher electric fields (> 8 MV/cm; independent of temperature), while for lower electric fields (5–8 MV/cm) at higher temperatures, the trap-related Generalized Poole–Frenkel (GPF) is dominant. This signified the role of traps in modifying the conduction in bulk ICPCVD SiO{sub 2} films. We then present the conduction in ML samples. For multilayer samples with SiO{sub 2} sublayer thickness of 1.5 nm and 2.5 nm, Direct Tunneling (DT) is observed to be dominant, while for SiO{sub 2} sublayer thickness of 3.5 nm, Space Charge Limited Conduction (SCLC) with exponential trap distribution is found to be the dominant conduction mechanism. This signifies the role of traps in modifying the conduction in Si-NC multilayer samples and SiO{sub 2} sublayer thickness dependence. - Highlights: • Electrical conduction in SiO{sub 2} film & Si-nanocrystal layers (Si-NCs) is reported. • Si

Attenuation in Rectangular Waveguides with Finite Conductivity Walls

Directory of Open Access Journals (Sweden)

K. C. Yeong

2011-06-01

Full Text Available We present a fundamental and accurate approach to compute the attenuation of electromagnetic waves propagating in rectangular waveguides with finite conductivity walls. The wavenumbers kx and ky in the x and y directions respectively, are obtained as roots of a set of transcendental equations derived by matching the tangential component of the electric field (E and the magnetic field (H at the surface of the waveguide walls. The electrical properties of the wall material are determined by the complex permittivity ε, permeability μ, and conductivity σ. We have examined the validity of our model by carrying out measurements on the loss arising from the fundamental TE10 mode near the cutoff frequency. We also found good agreement between our results and those obtained by others including Papadopoulos’ perturbation method across a wide range of frequencies, in particular in the vicinity of cutoff. In the presence of degenerate modes however, our method gives higher losses, which we attribute to the coupling between modes as a result of dispersion.

Submicron Features in Higher Manganese Silicide

Directory of Open Access Journals (Sweden)

Yatir Sadia

2013-01-01

Full Text Available The world energy crisis had increased the demand for alternative energy sources and as such is one of the topics at the forefront of research. One way for reducing energy consumption is by thermoelectricity. Thermoelectric effects enable direct conversion of thermal into electrical energy. Higher manganese silicide (HMS, MnSi1.75 is one of the promising materials for applications in the field of thermoelectricity. The abundance and low cost of the elements, combined with good thermoelectric properties and high mechanical and chemical stability at high temperatures, make it very attractive for thermoelectric applications. Recent studies have shown that Si-rich HMS has improved thermoelectric properties. The most interesting of which is the unusual reduction in thermal conductivity. In the current research, transmission (TEM and scanning (SEM electron microscopy as well as X-ray diffraction methods were applied for investigation of the govern mechanisms resulting in very low thermal conductivity values of an Si-rich HMS composition, following arc melting and hot-pressing procedures. In this paper, it is shown that there is a presence of sub-micron dislocations walls, stacking faults, and silicon and HMS precipitates inside each other apparent in the matrix, following a high temperature (0.9 Tm hot pressing for an hour. These are not just responsible for the low thermal conductivity values observed but also indicate the ability to create complicate nano-structures that will last during the production process and possibly during the application.

Economic Deprivation and Its Effects on Childhood Conduct Problems: The Mediating Role of Family Stress and Investment Factors

Directory of Open Access Journals (Sweden)

Edward M. Sosu

2017-09-01

Full Text Available This study investigated the mechanisms by which experiences of poverty influence the trajectory of conduct problems among preschool children. Drawing on two theoretical perspectives, we focused on family stress (stress and harsh discipline and investment variables (educational investment, nutrition, and cognitive ability as key mediators. Structural equation modeling techniques with prospective longitudinal data from the Growing Up in Scotland survey (N = 3,375 were used. Economic deprivation measured around the first birthday of the sample children had both direct and indirect effects on conduct problems across time (ages 4, 5, and 6. In line with the family stress hypothesis, higher levels of childhood poverty predicted conduct problems across time through increased parental stress and punitive discipline. Consistent with the investment model, childhood deprivation was associated with higher levels of conduct problems via educational investment and cognitive ability. The study extends previous knowledge on the mechanisms of this effect by demonstrating that cognitive ability is a key mediator between poverty and the trajectory of childhood conduct problems. This suggests that interventions aimed at reducing child conduct problems should be expanded to include factors that compromise parenting as well as improve child cognitive ability.

Creating a Culture of Giving in Irish Higher Education: An Education in Direct(ing) Philanthropic Giving in Ireland

Science.gov (United States)

Gallo, Maria L.

2014-01-01

Philanthropy in Irish higher education has an interesting historical reference point, with the role Atlantic Philanthropies played in steering the agenda for philanthropy in higher education institutions. To investigate the question of philanthropic culture in Ireland, this research draws on policy documents and academic literature related to…

Transport properties of olivine grain boundaries from electrical conductivity experiments

Science.gov (United States)

Pommier, Anne; Kohlstedt, David L.; Hansen, Lars N.; Mackwell, Stephen; Tasaka, Miki; Heidelbach, Florian; Leinenweber, Kurt

2018-05-01

Grain boundary processes contribute significantly to electronic and ionic transports in materials within Earth's interior. We report a novel experimental study of grain boundary conductivity in highly strained olivine aggregates that demonstrates the importance of misorientation angle between adjacent grains on aggregate transport properties. We performed electrical conductivity measurements of melt-free polycrystalline olivine (Fo90) samples that had been previously deformed at 1200 °C and 0.3 GPa to shear strains up to γ = 7.3. The electrical conductivity and anisotropy were measured at 2.8 GPa over the temperature range 700-1400 °C. We observed that (1) the electrical conductivity of samples with a small grain size (3-6 µm) and strong crystallographic preferred orientation produced by dynamic recrystallization during large-strain shear deformation is a factor of 10 or more larger than that measured on coarse-grained samples, (2) the sample deformed to the highest strain is the most conductive even though it does not have the smallest grain size, and (3) conductivity is up to a factor of 4 larger in the direction of shear than normal to the shear plane. Based on these results combined with electrical conductivity data for coarse-grained, polycrystalline olivine and for single crystals, we propose that the electrical conductivity of our fine-grained samples is dominated by grain boundary paths. In addition, the electrical anisotropy results from preferential alignment of higher-conductivity grain boundaries associated with the development of a strong crystallographic preferred orientation of the grains.

High temperature heat capacities and electrical conductivities of boron carbides

International Nuclear Information System (INIS)

Matsui, Tsuneo; Arita, Yuri; Naito, Keiji; Imai, Hisashi

1991-01-01

The heat capacities and the electrical conductivities of B x C(x=3, 4, 5) were measured by means of direct heating pulse calorimetry in the temperature range from 300 to 1500 K. The heat capacities of B x C increased with increasing x value. This increase in the heat capacity is probably related to the change of the lattice vibration mode originated from the reduction of the stiffness of the intericosahedral chain accompanied with a change from C-B-C to C-B-B chains. A linear relationship between the logarithm of σT (σ is the electrical conductivity and T is the absolute temperature) of B x C and the reciprocal temperature was observed, indicating the presence of small polaron hopping as the predominant conduction mechanism. The electrical conductivity of B x C also increased with increasing x value (from 4 to 5) due to an increase of the polaron hopping of holes between carbon atoms at geometrically nonequivalent sites, since these nonequivalent sites of carbon atoms were considered to increase in either B 11 C icosahedra or in icosahedral chains with increasing x. The electrical conductivity of B 3 C was higher than that of B 4 C, which is probably due to the precipitation of high-conducting carbon. The thermal conductivity and the thermodynamic quantities of B 4 C were also determined precisely from the heat capacity value. (orig.)

Conduction cooling: multicrate fastbus hardware

International Nuclear Information System (INIS)

Makowiecki, D.; Sims, W.; Larsen, R.

1980-11-01

Described is a new and novel approach for cooling nuclear instrumentation modules via heat conduction. The simplicity of liquid cooled crates and ease of thermal management with conduction cooled modules are described. While this system was developed primarily for the higher power levels expected with Fastbus electronics, it has many general applications

Transparent Conductive Nanostructures

Energy Technology Data Exchange (ETDEWEB)

None

2008-06-22

The objectives of this program between UT-Battelle, LLC (the ''Contractor'') and (Battelle Memorial Institute) (the "Participant") were directed towards achieving significant improvement: in the electrical conductivity and optical/infrared transmission of single-wall carbon nanotube (SWNT)-based composite materials. These materials will be used in coating applications that range from aircraft canopies to display applications. The goal of the project was to obtain supported mats of SWNTs with sheet conductivities approaching 10 ohms/square combined with high optical transmission (>85% transmission at 550 nm), thereby permitting their application as a replacement for indium tin oxide (ITO) in a variety of applications such as flexible displays.

Proton conducting membranes prepared by incorporation of organophosphorus acids into alcohol barrier polymers for direct methanol fuel cells

Science.gov (United States)

Jiang, Zhongyi; Zheng, Xiaohong; Wu, Hong; Pan, Fusheng

A novel type of DMFC membrane was developed via incorporation of organophosphorus acids (OPAs) into alcohol barrier materials (polyvinyl alcohol/chitosan, PVA/CS) to simultaneously acquire high proton conductivity and low methanol permeability. Three kinds of OPAs including amino trimethylene phosphonic acid (ATMP), ethylene diamine tetra(methylene phosphonic acid) (EDTMP) and hexamethylene diamine tetra(methylene phosphonic acid) (HDTMP), with different molecular structure and phosphonic acid groups content were added into PVA/CS blends and served the dual functions as proton conductor as well as crosslinker. The as-prepared OPA-doped PVA/CS membranes exhibited remarkably enhanced proton conducting ability, 2-4 times higher than that of the pristine PVA/CS membrane, comparable with that for Nafion ®117 membrane (5.04 × 10 -2 S cm -1). The highest proton conductivities 3.58 × 10 -2, 3.51 × 10 -2 and 2.61 × 10 -2 S cm -1 for ATMP-, EDTMP- and HDTMP-doped membranes, respectively were all achieved at highest initial OPA doping content (23.1 wt.%) at room temperature. The EDTMP-doped PVA/CS membrane with an acid content of 13.9 wt.% showed the lowest methanol permeability of 2.32 × 10 -7 cm 2 s -1 which was 16 times lower than that of Nafion ®117 membrane. In addition, the thermal stability and oxidative durability were both significantly improved by the incorporation of OPAs in comparison with pristine PVA/CS membranes.

Anisotropic in-plane thermal conductivity in multilayer silicene

Science.gov (United States)

Zhou, Yang; Guo, Zhi-Xin; Chen, Shi-You; Xiang, Hong-Jun; Gong, Xin-Gao

2018-06-01

We systematically study thermal conductivity of multilayer silicene by means of Boltzmann Transportation Equation (BTE) method. We find that their thermal conductivity strongly depends on the surface structures. Thermal conductivity of bilayer silicene varies from 3.31 W/mK to 57.9 W/mK with different surface structures. Also, the 2 × 1 surface reconstruction induces unusual large thermal conductivity anisotropy, which reaches 70% in a four-layer silicene. We also find that the anisotropy decreases with silicene thickness increasing, owing to the significant reduction of thermal conductivity in the zigzag direction and its slight increment in the armchair direction. Finally, we find that both the phonon-lifetime anisotropy and the phonon-group-velocity anisotropy contribute to the thermal conductivity anisotropy of multilayer silicene. These findings could be helpful in the field of heat management, thermoelectric applications involving silicene and other multilayer nanomaterials with surface reconstructions in the future.

Direct electron transfer: an approach for electrochemical biosensors with higher selectivity and sensitivity

Directory of Open Access Journals (Sweden)

Freire Renato S.

2003-01-01

Full Text Available The most promising approach for the development of electrochemical biosensors is to establish a direct electrical communication between the biomolecules and the electrode surface. This review focuses on advances, directions and strategies in the development of third generation electrochemical biosensors. Subjects covered include a brief description of the fundamentals of the electron transfer phenomenon and amperometric biosensor development (different types and new oriented enzyme immobilization techniques. Special attention is given to different redox enzymes and proteins capable of electrocatalyzing reactions via direct electron transfer. The analytical applications and future trends for third generation biosensors are also presented and discussed.

Current state and future directions of research and development in conducting polymers

International Nuclear Information System (INIS)

Spinks, G.M.; Innis, P.C.; Lewis, T.W.; Kane-Maghire, L.A.P.; Wallace, G.G.

2000-01-01

Polymers that inherently conduct electricity have been researched intensively for a little over 20 years. An enormous research effort in academic and industrial institutions has resulted in over 17,000 publications published in the last 10 years alone. Significant advances in the synthesis of new polymers and the methods for processing these polymers into products have resulted from this research activity. A number of commercial developments have emerged, some of which have reached maturity as marketed products. Some others have failed in the marketplace. The diversity of applications for conducting polymers continues to fuel research and development and ensures that new products will emerge over the foreseeable future. In the more distant future, truly intelligent polymer systems remain as an achievable objective. By developing appropriate processing and fabrication technologies, it should be possible to integrate sensing, actuating and energy storage functions into a single system. Further developments in self-assembly of conducting polymers from the nano- to the meso-scale will open up applications in MEMS and nanotechnology

Change of direction ability test differentiates higher level and lower level soccer referees

Science.gov (United States)

Los, Arcos A; Grande, I; Casajús, JA

2016-01-01

This report examines the agility and level of acceleration capacity of Spanish soccer referees and investigates the possible differences between field referees of different categories. The speed test consisted of 3 maximum acceleration stretches of 15 metres. The change of direction ability (CODA) test used in this study was a modification of the Modified Agility Test (MAT). The study included a sample of 41 Spanish soccer field referees from the Navarre Committee of Soccer Referees divided into two groups: i) the higher level group (G1, n = 20): 2ndA, 2ndB and 3rd division referees from the Spanish National Soccer League (28.43 ± 1.39 years); and ii) the lower level group (G2, n = 21): Navarre Provincial League soccer referees (29.54 ± 1.87 years). Significant differences were found with respect to the CODA between G1 (5.72 ± 0.13 s) and G2 (6.06 ± 0.30 s), while no differences were encountered between groups in acceleration ability. No significant correlations were obtained in G1 between agility and the capacity to accelerate. Significant correlations were found between sprint and agility times in the G2 and in the total group. The results of this study showed that agility can be used as a discriminating factor for differentiating between national and regional field referees; however, no observable differences were found over the 5 and 15 m sprint tests. PMID:27274111

Electronic Conductivity of Vanadium-Tellurite Glass-Ceramics

DEFF Research Database (Denmark)

Kjeldsen, Jonas; Yue, Yuanzheng; Bragatto, Caio B.

2013-01-01

In this paper, we investigate the electronic conductivity of 2TeO2-V2O5 glass-ceramics with crystallinity ranging from 0 to 100 wt.%, i.e., from entirely amorphous to completely crystalline. The glass is prepared by the melt quenching technique, and the crystal is prepared by subsequent heat...... spectroscopy. We find similar activation energies for both glass and crystal, implying that they have similar conduction mechanisms, i.e., thermally activated hopping. The electronic conductivity of 2TeO2-V2O5 glass is about one order of magnitude higher than that of the corresponding crystal......, and a percolation phenomenon occurs at a glass fraction of 61 wt.%, increasing from a lower conductivity in the crystal to a higher conductivity in the glass. We explain the behavior of electronic conduction in the 2TeO2-V2O5 glass-ceramics by considering constriction effects between particles as well...

Anisotropy of hopping conductivity in TIGaSe2, crystal

International Nuclear Information System (INIS)

Nadjafov, A.I.; Sardarli, R.M.; Samedov, O. A.; Abdullayev, A.P.; Zeynalova, E.A.; Jabbarov, J.H.

2005-01-01

Full Text: The temperature dependences of electrical conductivity of a chained semiconductor crystal TIGaTe 2 in a direction of chains and perpendicularly have been investigated. It was established that in a constant electrical field in both crystallographic directions took place hopping conductivity with variable length of a jump on located near Fermi level. The energy activation of conductivity has been determined. It was appreciated density of a condition in a vicinity of a Fermi level, their disorder, radius of localization, average distance of jumps of carriers

Conductance spectra of asymmetric ferromagnet/ferromagnet/ferromagnet junctions

Energy Technology Data Exchange (ETDEWEB)

Pasanai, K., E-mail: krisakronmsu@gmail.com

2017-01-15

A theory of tunneling spectroscopy of ferromagnet/ferromagnet/ferromagnet junctions was studied. We applied a delta-functional approximation for the interface scattering properties under a one-dimensional system of a free electron approach. The reflection and transmission probabilities were calculated in the ballistic regime, and the conductance spectra were then calculated using the Landauer formulation. The magnetization directions were set to be either parallel (P) or anti-parallel (AP) alignments, for comparison. We found that the conductance spectra was suppressed when increasing the interfacial scattering at the interfaces. Moreover, the electron could exhibit direct transmission when the thickness was rather thin. Thus, there was no oscillation in this case. However, in the case of a thick layer the conductance spectra oscillated, and this oscillation was most prominent when the middle layer thickness increased. In the case of direct transmission, the conductance spectra of P and AP systems were definitely suppressed with increased exchange energy of the middle ferromagnet. This also refers to an increase in the magnetoresistance of the junction. In the case of oscillatory behavior, the positions of the resonance peaks were changed as the exchange energy was changed. - Highlights: • The conductance spectra of a FM/FM/FM junction were calculated. • The conductance spectra were suppressed by the exchange energy. • The exchange energy and the potential strength play similar roles in the junctions.

Conductance spectra of asymmetric ferromagnet/ferromagnet/ferromagnet junctions

International Nuclear Information System (INIS)

Pasanai, K.

2017-01-01

A theory of tunneling spectroscopy of ferromagnet/ferromagnet/ferromagnet junctions was studied. We applied a delta-functional approximation for the interface scattering properties under a one-dimensional system of a free electron approach. The reflection and transmission probabilities were calculated in the ballistic regime, and the conductance spectra were then calculated using the Landauer formulation. The magnetization directions were set to be either parallel (P) or anti-parallel (AP) alignments, for comparison. We found that the conductance spectra was suppressed when increasing the interfacial scattering at the interfaces. Moreover, the electron could exhibit direct transmission when the thickness was rather thin. Thus, there was no oscillation in this case. However, in the case of a thick layer the conductance spectra oscillated, and this oscillation was most prominent when the middle layer thickness increased. In the case of direct transmission, the conductance spectra of P and AP systems were definitely suppressed with increased exchange energy of the middle ferromagnet. This also refers to an increase in the magnetoresistance of the junction. In the case of oscillatory behavior, the positions of the resonance peaks were changed as the exchange energy was changed. - Highlights: • The conductance spectra of a FM/FM/FM junction were calculated. • The conductance spectra were suppressed by the exchange energy. • The exchange energy and the potential strength play similar roles in the junctions.

Thermal conductivities and conduction mechanisms of Sb-Te Alloys at high temperatures

International Nuclear Information System (INIS)

Lan, Rui; Endo, Rie; Kobayashi, Yoshinao; Susa, Masahiro; Kuwahara, Masashi

2011-01-01

Sb-Te alloys have drawn much attention due to its application in phase change memory as well as the unique properties as chalcogenide. In this work, the thermal conductivities of Sb-x mol%Te alloys (x = 14, 25, 44, 60, 70, and 90) have been measured by the hot strip method from room temperature up to temperature just below the respective melting points. For the intermetallic compound Sb 2 Te 3 (x = 60), the thermal conductivity decreases up to approximately 600 K and then increases. For other Sb-x mol%Te alloys where x > 60, the thermal conductivities of the alloys decrease with increasing temperature. In contrast, for x < 60, the thermal conductivities of the alloys keep roughly constant up to approximately 600 K and then increase with increasing temperature. It is proposed that free electron dominates the heat transport below 600 K, and ambipolar diffusion also contributes to the increase in the thermal conductivity at higher temperatures. The prediction equation from temperature and chemical composition has been proposed for thermal conductivities of Sb-Te alloys.

Multivalent ion conducting solids

Energy Technology Data Exchange (ETDEWEB)

Imanaka, N. [Osaka Univ., Suita, Osaka (Japan). Dept. of Applied Chemistry

2008-07-01

Solid electrolytes possess important characteristics for industrial applications. Only a single ionic species can macroscopically migrate in these solids. This paper described a the new NASICON (M-Zr-Nb-P-O) type system, exhibiting an exceptionally high level of trivalent M3+ ion conductivity on polycrystalline solids. The partial substitution of the smaller higher valent Nb5+ ion for Zr4+ stabilized the NASICON phase and realized the M3+ ion conduction in the NASICON structure. It was concluded that the conductivities of the series are comparable to those of the practically applied solid electrolytes of oxide anion conductors of YSZ and CSZ. 3 refs., 2 figs.

Methodological issues involved in conducting qualitative research on support for nurses directly involved with women who chose to terminate their pregnancy

Directory of Open Access Journals (Sweden)

Antoinette Gmeiner

2001-11-01

Full Text Available The purpose of this article is to describe the methodological issues involved in conducting qualitative research to explore and describe nurses’ experience of being directly involved with termination of pregnancies and developing guidelines for support for these nurses. Opsomming Die doel van hierdie artikel is om die metodologiese vraagstukke te beskryf rondom die uitvoer van kwalitatiewe navorsing waar verpleegkundiges se ervaring van hul direkte betrokkenheid by terminasie van swangerskap verken en beskryf is. *Please note: This is a reduced version of the abstract. Please refer to PDF for full text.

Mutation direction by irradiation in rice

International Nuclear Information System (INIS)

Wang Cailian; Chen Qiufang; Jin Wei; Lu Yimei

2001-01-01

The mutation directions of rice were studied. The results indicated that the mutation directions of rice induced by 14 C were invert correlation to their genetic backgrounds of tested rice varieties, i.e. early mature and short stem varieties produced later mature and higher stem mutation; late mature and high stem varieties produced earlier mature and shorter stem mutation; the varieties of middle maturity and height produced both direction mutations of earlier and later maturity or shorter and higher stem. The mutation directions induced by 14 C were also related to treated doses and stages. Frequency of earlier maturity mutation by protons treatment were higher than those induced by other mutagens. Frequency of later maturity by γ-rays were higher than those induced by other mutagens. Frequency of short stem mutation by synchronous irradiation (soft X-rays) were higher than those induced by other mutagens. Frequency of beneficial mutation induced by proton treatment were higher than those induced by γ-rays

Proton conducting membranes prepared by incorporation of organophosphorus acids into alcohol barrier polymers for direct methanol fuel cells

Energy Technology Data Exchange (ETDEWEB)

Jiang, Zhongyi; Zheng, Xiaohong; Wu, Hong; Pan, Fusheng [Key Laboratory for Green Chemical Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

2008-10-15

A novel type of DMFC membrane was developed via incorporation of organophosphorus acids (OPAs) into alcohol barrier materials (polyvinyl alcohol/chitosan, PVA/CS) to simultaneously acquire high proton conductivity and low methanol permeability. Three kinds of OPAs including amino trimethylene phosphonic acid (ATMP), ethylene diamine tetra(methylene phosphonic acid) (EDTMP) and hexamethylene diamine tetra(methylene phosphonic acid) (HDTMP), with different molecular structure and phosphonic acid groups content were added into PVA/CS blends and served the dual functions as proton conductor as well as crosslinker. The as-prepared OPA-doped PVA/CS membranes exhibited remarkably enhanced proton conducting ability, 2-4 times higher than that of the pristine PVA/CS membrane, comparable with that for Nafion {sup registered} 117 membrane (5.04 x 10{sup -2} S cm{sup -1}). The highest proton conductivities 3.58 x 10{sup -2}, 3.51 x 10{sup -2} and 2.61 x 10{sup -2} S cm{sup -1} for ATMP-, EDTMP- and HDTMP-doped membranes, respectively were all achieved at highest initial OPA doping content (23.1 wt.%) at room temperature. The EDTMP-doped PVA/CS membrane with an acid content of 13.9 wt.% showed the lowest methanol permeability of 2.32 x 10{sup -7} cm{sup 2} s{sup -1} which was 16 times lower than that of Nafion {sup registered} 117 membrane. In addition, the thermal stability and oxidative durability were both significantly improved by the incorporation of OPAs in comparison with pristine PVA/CS membranes. (author)

Conductance measurement by two-line probe method of polypyrrole nano-films formed on mica by admicellar polymerization

Energy Technology Data Exchange (ETDEWEB)

Mou, C.-Y. [Graduate Institute of Textile Engineering, Feng Chia University, Taichung 40724, Taiwan (China); Yuan, W.-L. [Department of Chemical Engineering, Feng Chia University, Taichung 40724, Taiwan (China)], E-mail: wyuan@fcu.edu.tw; Tsai, I-S. [Graduate Institute of Textile Engineering, Feng Chia University, Taichung 40724, Taiwan (China); O' Rear, Edgar A. [School of Chemical, Biological and Material Engineering, University of Oklahoma, Norman, OK 73019 (United States); Barraza, Harry [Unilever R and D HPC, Quarry Road East, Bebington, Wirral, CH63 3JW (United Kingdom)

2008-10-01

Measuring the electrical conductance is of importance in fabricating electronic devices based on semiconducting thin films. In this report, electrically conducting polypyrrole (PPy) nano-films were deposited on insulating mica plates by admicellar polymerization. It becomes difficult to measure such film conductance in the lateral direction due the nanometric thickness which only allows for very low electrical current. In order to understand the effects of surfactant on the film conductivity, morphological studies using atomic force microscopy and conductance measurements with a sub-fA multimeter were performed. Higher conductances were found for PPy thin films made using surfactant templates, than that of a bare mica surface. Using the two-line probe method by drawing two lines of silver glue 8 mm apart on the sample surface, the current-voltage curves of bare mica surface yielded a lateral conductance of 6.0 x 10{sup -13} S. In comparison, PPy thin films made using sodium dodecyl sulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB) as surfactant templates showed conductances of 1.2 x 10{sup -11} S and 7.7 x 10{sup -12} S, respectively. The higher conductances indicate tunneling, hopping, and percolation of charge carriers throughout the films. The lower-bound conductivities were calculated as 4.0 x 10{sup -3} S/cm and 2.6 x 10{sup -3} S/cm, measured based on the average thickness 2.3 nm for the SDS-PPy films and 2.4 nm for the CTAB-PPy films. Conductivities for both SDS and CTAB template PPy films are found to be of the same order.

Conductance measurement by two-line probe method of polypyrrole nano-films formed on mica by admicellar polymerization

International Nuclear Information System (INIS)

Mou, C.-Y.; Yuan, W.-L.; Tsai, I-S.; O'Rear, Edgar A.; Barraza, Harry

2008-01-01

Measuring the electrical conductance is of importance in fabricating electronic devices based on semiconducting thin films. In this report, electrically conducting polypyrrole (PPy) nano-films were deposited on insulating mica plates by admicellar polymerization. It becomes difficult to measure such film conductance in the lateral direction due the nanometric thickness which only allows for very low electrical current. In order to understand the effects of surfactant on the film conductivity, morphological studies using atomic force microscopy and conductance measurements with a sub-fA multimeter were performed. Higher conductances were found for PPy thin films made using surfactant templates, than that of a bare mica surface. Using the two-line probe method by drawing two lines of silver glue 8 mm apart on the sample surface, the current-voltage curves of bare mica surface yielded a lateral conductance of 6.0 x 10 -13 S. In comparison, PPy thin films made using sodium dodecyl sulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB) as surfactant templates showed conductances of 1.2 x 10 -11 S and 7.7 x 10 -12 S, respectively. The higher conductances indicate tunneling, hopping, and percolation of charge carriers throughout the films. The lower-bound conductivities were calculated as 4.0 x 10 -3 S/cm and 2.6 x 10 -3 S/cm, measured based on the average thickness 2.3 nm for the SDS-PPy films and 2.4 nm for the CTAB-PPy films. Conductivities for both SDS and CTAB template PPy films are found to be of the same order

An Overview of the Current State of Women’s Leadership in Higher Education in Saudi Arabia and a Proposal for Future Research Directions

Directory of Open Access Journals (Sweden)

Azzah Alsubaie

2017-10-01

Full Text Available Despite the predominance of perspectives on women’s leadership, which consistently emphasize the underrepresentation of women in virtually every sphere of political and economic life in countries around the world, very little is known about women’s leadership, especially in higher education, in the Kingdom of Saudi Arabia (KSA. This has resulted in a gap in the literature, since higher education is one area of employment where Saudi women have made progress, and in spite of complex social, religious, cultural and organisational barriers, some have broken through the glass ceiling into higher education leadership. One goal of this paper is to highlight, through a synthesis of existing literature, the current state of women’s higher education leadership in Saudi Arabia. The second goal of this paper is to propose new directions for future research to address the current dearth of empirical work on women’s leadership in higher education in Saudi Arabia. This may be relevant to other regions of the Middle East and elsewhere.

Numerical estimation of the effective electrical conductivity in carbon paper diffusion media

International Nuclear Information System (INIS)

Zamel, Nada; Li, Xianguo; Shen, Jun

2012-01-01

Highlights: ► Anisotropic effective electrical conductivity of the GDL is estimated numerically. ► The electrical conductivity is a key component in understanding the structure of the GDL. ► Expressions for evaluating the electrical conductivity were proposed. ► The tortuosity factor was evaluated as 1.7 and 3.4 in the in- and through-plane directions, respectively. - Abstract: The transport of electrons through the gas diffusion layer (GDL) of polymer electrolyte membrane (PEM) fuel cells has a significant impact on the optimal design and operation of PEM fuel cells and is directly affected by the anisotropic nature of the carbon paper material. In this study, a three-dimensional reconstruction of the GDL is used to numerically estimate the directional dependent effective electrical conductivity of the layer for various porosity values. The distribution of the fibers in the through-plane direction results in high electrical resistivity; hence, decreasing the overall effective electrical conductivity in this direction. This finding is in agreement with measured experimental data. Further, using the numerical results of this study, two mathematical expressions were proposed for the calculation of the effective electrical conductivity of the carbon paper GDL. Finally, the tortuosity factor was evaluated as 1.7 and 3.4 in the in- and through-plane directions, respectively.

A saxitoxin-binding aptamer with higher affinity and inhibitory activity optimized by rational site-directed mutagenesis and truncation.

Science.gov (United States)

Zheng, X; Hu, B; Gao, S X; Liu, D J; Sun, M J; Jiao, B H; Wang, L H

2015-07-01

Saxitoxin (STX), a member of the family of paralytic shellfish poisoning toxins, poses toxicological and ecotoxicological risks. To develop an analytical recognition element for STX, a DNA aptamer (APT(STX1)) was previously discovered via an iterative process known as Systematic Evolution of Ligands by Exponential Enrichment (SELEX) by Handy et al. Our study focused on generating an improved aptamer based on APT(STX1) through rational site-directed mutation and truncation. In this study, we generated the aptamer, M-30f, with a 30-fold higher affinity for STX compared with APT(STX1). The Kd value for M-30f was 133 nM, which was calculated by Bio-Layer Interferometry. After optimization, we detected and compared the interaction of STX with aptamers (APT(STX1) or M-30f) through several techniques (ELISA, cell bioassay, and mouse bioassay). Both aptamers' STX-binding ability was demonstrated in all three methods. Moreover, M-30f performs better than its parent sequence with higher suppressive activity against STX. As a molecular recognition element, M-30f has good prospects for practical application. Copyright © 2015 Elsevier Ltd. All rights reserved.

On higher derivative gravity

International Nuclear Information System (INIS)

Accioly, A.J.

1987-01-01

A possible classical route conducting towards a general relativity theory with higher-derivatives starting, in a sense, from first principles, is analysed. A completely causal vacuum solution with the symmetries of the Goedel universe is obtained in the framework of this higher-derivative gravity. This very peculiar and rare result is the first known vcuum solution of the fourth-order gravity theory that is not a solution of the corresponding Einstein's equations.(Author) [pt

THERMAL CONDUCTIVITY OF THE POTENTIAL REPOSITORY HORIZON

Energy Technology Data Exchange (ETDEWEB)

J.E. BEAN

2004-09-27

The primary purpose of this report is to assess the spatial variability and uncertainty of bulk thermal conductivity in the host horizon for the repository at Yucca Mountain. More specifically, the lithostratigraphic units studied are located within the Topopah Spring Tuff (Tpt) and consist of the upper lithophysal zone (Tptpul), the middle nonlithophysal zone (Tptpmn), the lower lithophysal zone (Tptpll), and the lower nonlithophysal zone (Tptpln). Design plans indicate that approximately 81 percent of the repository will be excavated in the Tptpll, approximately 12 percent in the Tptpmn, and the remainder in the Tptul and Tptpln (BSC 2004 [DIRS 168370]). This report provides three-dimensional geostatistical estimates of the bulk thermal conductivity for the four stratigraphic layers of the repository horizon. The three-dimensional geostatistical estimates of matrix and lithophysal porosity, dry bulk density, and matrix thermal conductivity are also provided. This report provides input to various models and calculations that simulate heat transport through the rock mass. These models include the ''Drift Degradation Analysis, Multiscale Thermohydrologic Model, Ventilation Model and Analysis Report, Igneous Intrusion Impacts on Waste Packages and Waste Forms, Drift-Scale Coupled Processes (DST and TH Seepage) Models'', and ''Drift Scale THM Model''. These models directly or indirectly provide input to the total system performance assessment (TSPA). The main distinguishing characteristic among the lithophysal and nonlithophysal units is the percentage of large-scale (centimeters-meters) voids within the rock. The Tptpul and Tptpll, as their names suggest, have a higher percentage of lithophysae than the Tptpmn and the Tptpln. Understanding the influence of the lithophysae is of great importance to understanding bulk thermal conductivity.

Proton Conductive Channel Optimization in Methanol Resistive Hybrid Hyperbranched Polyamide Proton Exchange Membrane

Directory of Open Access Journals (Sweden)

Liying Ma

2017-12-01

Full Text Available Based on a previously developed polyamide proton conductive macromolecule, the nano-scale structure of the self-assembled proton conductive channels (PCCs is adjusted via enlarging the nano-scale pore size within the macromolecules. Hyperbranched polyamide macromolecules with different size are synthesized from different monomers to tune the nano-scale pore size within the macromolecules, and a series of hybrid membranes are prepared from these two micromoles to optimize the PCC structure in the proton exchange membrane. The optimized membrane exhibits methanol permeability low to 2.2 × 10−7 cm2/s, while the proton conductivity of the hybrid membrane can reach 0.25 S/cm at 80 °C, which was much higher than the value of the Nafion 117 membrane (0.192 S/cm. By considering the mechanical, dimensional, and the thermal properties, the hybrid hyperbranched polyamide proton exchange membrane (PEM exhibits promising application potential in direct methanol fuel cells (DMFC.

Conductive properties of methanogenic biofilms.

Science.gov (United States)

Li, Cheng; Lesnik, Keaton Larson; Liu, Hong

2018-02-01

Extracellular electron transfer between syntrophic partners needs to be efficiently maintained in methanogenic environments. Direct extracellular electron transfer via electrical current is an alternative to indirect hydrogen transfer but requires construction of conductive extracellular structures. Conductive mechanisms and relationship between conductivity and the community composition in mixed-species methanogenic biofilms are not well understood. The present study investigated conductive behaviors of methanogenic biofilms and examined the correlation between biofilm conductivity and community composition between different anaerobic biofilms enriched from the same inoculum. Highest conductivity observed in methanogenic biofilms was 71.8±4.0μS/cm. Peak-manner response of conductivity upon changes over a range of electrochemical potentials suggests that electron transfer in methanogenic biofilms occurs through redox driven super-exchange. The strong correlation observed between biofilm conductivity and Geobacter spp. in the metabolically diverse anaerobic communities suggests that the efficiency of DEET may provide pressure for microbial communities to select for species that can produce electrical conduits. Copyright © 2017 Elsevier B.V. All rights reserved.

Conducting polymer-based multilayer films for instructive biomaterial coatings

OpenAIRE

Hardy, John G; Li, Hetian; Chow, Jacqueline K; Geissler, Sydney A; McElroy, Austin B; Nguy, Lindsey; Hernandez, Derek S; Schmidt, Christine E

2015-01-01

Aim: To demonstrate the design, fabrication and testing of conformable conducting biomaterials that encourage cell alignment. Materials & methods: Thin conducting composite biomaterials based on multilayer films of poly (3,4-ethylenedioxythiophene) derivatives, chitosan and gelatin were prepared in a layer-by-layer fashion. Fibroblasts were observed with fluorescence microscopy and their alignment (relative to the dipping direction and direction of electrical current passed through the films)...

Randomized trials published in higher vs. lower impact journals differ in design, conduct, and analysis.

Science.gov (United States)

Bala, Malgorzata M; Akl, Elie A; Sun, Xin; Bassler, Dirk; Mertz, Dominik; Mejza, Filip; Vandvik, Per Olav; Malaga, German; Johnston, Bradley C; Dahm, Philipp; Alonso-Coello, Pablo; Diaz-Granados, Natalia; Srinathan, Sadeesh K; Hassouneh, Basil; Briel, Matthias; Busse, Jason W; You, John J; Walter, Stephen D; Altman, Douglas G; Guyatt, Gordon H

2013-03-01

To compare methodological characteristics of randomized controlled trials (RCTs) published in higher vs. lower impact Core Clinical Journals. We searched MEDLINE for RCTs published in 2007 in Core Clinical Journals. We randomly sampled 1,140 study reports in a 1:1 ratio in higher (five general medicine journals with the highest total citations in 2007) and lower impact journals. Four hundred sixty-nine RCTs proved eligible: 219 in higher and 250 in lower impact journals. RCTs in higher vs. lower impact journals had larger sample sizes (median, 285 vs. 39), were more likely to receive industry funding (53% vs. 28%), declare concealment of allocation (66% vs. 36%), declare blinding of health care providers (53% vs. 41%) and outcome adjudicators (72% vs. 54%), report a patient-important primary outcome (69% vs. 50%), report subgroup analyses (64% vs. 26%), prespecify subgroup hypotheses (42% vs. 20%), and report a test for interaction (54% vs. 27%); P journals were more likely to report methodological safeguards against bias and patient-important outcomes than those published in lower impact journals. However, sufficient limitations remain such that publication in a higher impact journal does not ensure low risk of bias. Copyright © 2013 Elsevier Inc. All rights reserved.

Thermal conductivity of carbon foams. Measurements and interpretation; Conductivite thermique de mousses de carbone. Mesures et interpretation

Energy Technology Data Exchange (ETDEWEB)

Bourret, F.; Fort, C.; Duffa, G. [CEA CESTA, 33 - Le Barp (France)

1996-12-31

This paper describes thermal diffusivity measurements performed with the flash method on carbon foams with open porosity at ambient and higher temperatures. The influence of gas inclusions in the pores has been studied too. In this type of highly insulating material, radiant heat transfer plays a major role. The experiments carried out are interpreted in terms of equivalent thermal conductivity and show the difficulties encountered, in particular the dependence with sample thickness. An interpretation based on a direct simulation with an equivalent periodical material is given with an estimation of the gaseous conductivity based on the kinetics theory of gases. This study demonstrates that the notion of equivalent thermal conductivity is not applicable to all experiments. (J.S.) 10 refs.

Effect of anionic surfactant concentration on the variable range hopping conduction in polypyrrole nanoparticles

International Nuclear Information System (INIS)

Rawal, Ishpal; Kaur, Amarjeet

2014-01-01

The mechanism of charge transport in polypyrrole (PPy) nanoparticles prepared with different concentrations (5 to 30 mM) of anionic surfactant (sodium dodecyl sulfate) is reported. Transmission electron microscopy technique confirms the formation of PPy nanoparticles of sizes ∼52 to 28 nm under surfactant directed approach. The room temperature electrical conductivity of the prepared nanoparticles found to increase from 3 to 22 S/cm with surfactant concentration. The temperature dependent activation energy rules out the possibility of band conduction mechanism in the prepared PPy nanoparticles and thus the synthesized nanoparticles are analyzed under variable range hopping (VRH) model for conduction mechanism. The PPy nanoparticles, reduced with liquid ammonia, hold 3D VRH conduction mechanism for the charge transport. However, in the doped samples, some deviation from 3D VRH conduction behavior at higher temperatures (>150 K) has been observed. This may be attributed to the presence of anionic surfactant in these samples. The doping of anionic surfactant causes rise in conducting islands, which may lead to the change in the shape/distribution of density of states governed by Gaussian or exponential type near Fermi level

Effect of anionic surfactant concentration on the variable range hopping conduction in polypyrrole nanoparticles

Science.gov (United States)

Rawal, Ishpal; Kaur, Amarjeet

2014-01-01

The mechanism of charge transport in polypyrrole (PPy) nanoparticles prepared with different concentrations (5 to 30 mM) of anionic surfactant (sodium dodecyl sulfate) is reported. Transmission electron microscopy technique confirms the formation of PPy nanoparticles of sizes ˜52 to 28 nm under surfactant directed approach. The room temperature electrical conductivity of the prepared nanoparticles found to increase from 3 to 22 S/cm with surfactant concentration. The temperature dependent activation energy rules out the possibility of band conduction mechanism in the prepared PPy nanoparticles and thus the synthesized nanoparticles are analyzed under variable range hopping (VRH) model for conduction mechanism. The PPy nanoparticles, reduced with liquid ammonia, hold 3D VRH conduction mechanism for the charge transport. However, in the doped samples, some deviation from 3D VRH conduction behavior at higher temperatures (>150 K) has been observed. This may be attributed to the presence of anionic surfactant in these samples. The doping of anionic surfactant causes rise in conducting islands, which may lead to the change in the shape/distribution of density of states governed by Gaussian or exponential type near Fermi level.

Conductance spectra of asymmetric ferromagnet/ferromagnet/ferromagnet junctions

Science.gov (United States)

Pasanai, K.

2017-01-01

A theory of tunneling spectroscopy of ferromagnet/ferromagnet/ferromagnet junctions was studied. We applied a delta-functional approximation for the interface scattering properties under a one-dimensional system of a free electron approach. The reflection and transmission probabilities were calculated in the ballistic regime, and the conductance spectra were then calculated using the Landauer formulation. The magnetization directions were set to be either parallel (P) or anti-parallel (AP) alignments, for comparison. We found that the conductance spectra was suppressed when increasing the interfacial scattering at the interfaces. Moreover, the electron could exhibit direct transmission when the thickness was rather thin. Thus, there was no oscillation in this case. However, in the case of a thick layer the conductance spectra oscillated, and this oscillation was most prominent when the middle layer thickness increased. In the case of direct transmission, the conductance spectra of P and AP systems were definitely suppressed with increased exchange energy of the middle ferromagnet. This also refers to an increase in the magnetoresistance of the junction. In the case of oscillatory behavior, the positions of the resonance peaks were changed as the exchange energy was changed.

Purely hopping conduction in c-axis oriented LiNbO3 thin films

Science.gov (United States)

Shandilya, Swati; Tomar, Monika; Sreenivas, K.; Gupta, Vinay

2009-05-01

Dielectric constant and ac conductivity of highly c-axis oriented LiNbO3 thin film grown by pulsed laser deposition were studied in a metal-insulator-metal configuration over a wide temperature (200 to 450 K) and frequency (100 Hz to 1 MHz) range. The preferred oriented Al (1%) doped ZnO film with electrical conductivity 1.1×103 Ω-1 cm-1 was deposited for dual purpose: (1) to serve as nucleating center for LiNbO3 crystallites along preferred c-axis growth direction, and (2) to act as a suitable bottom electrode for electrical studies. The room temperature dc conductivity (σdc) of LiNbO3 film was about 5.34×10-10 Ω-1 cm-1 with activation energy ˜0.3 eV, indicating extrinsic conduction. The ac conductivity σac was found to be much higher in comparison to σdc in the low temperature region (300 K), σac shows a weak frequency dependence, whereas dielectric constant exhibits a strong frequency dispersion. The dielectric dispersion data has been discussed in the light of theoretical models based on Debye type mixed conduction and purely hopping conduction. The dominant conduction in c-axis oriented LiNbO3 thin film is attributed to the purely hopping where both σdc and σac arise due to same mechanism.

Tunneling conductance of a two-dimensional electron gas with Dresselhaus spin-orbit coupling

International Nuclear Information System (INIS)

Srisongmuang, B.; Ka-oey, A.

2012-01-01

We theoretically studied the spin-dependent charge transport in a two-dimensional electron gas with Dresselhaus spin-orbit coupling (DSOC) and metal junctions. It is shown that the DSOC energy can be directly measured from the tunneling conductance spectrum. We found that spin polarization of the conductance in the propagation direction can be obtained by injecting from the DSOC system. We also considered the effect of the interfacial scattering barrier (both spin-flip and non-spin-flip scattering) on the overall conductance and the spin polarization of the conductance. It is found that the increase of spin-flip scattering can enhance the conductance under certain conditions. Moreover, both types of scattering can increase the spin polarization below the branches crossing of the energy band. - Highlights: → DSOC energy can be directly measured from tunneling conductance spectrum. → Spin polarization of conductance in the propagation direction can be obtained by injecting from DSOC system. → Both types of scattering can increase spin polarization.

Thermal conductivity and heat transfer in superlattices

Energy Technology Data Exchange (ETDEWEB)

Chen, G; Neagu, M; Borca-Tasciuc, T

1997-07-01

Understanding the thermal conductivity and heat transfer processes in superlattice structures is critical for the development of thermoelectric materials and devices based on quantum structures. This work reports progress on the modeling of thermal conductivity of superlattice structures. Results from the models established based on the Boltzmann transport equation could explain existing experimental results on the thermal conductivity of semiconductor superlattices in both in plane and cross-plane directions. These results suggest the possibility of engineering the interfaces to further reduce thermal conductivity of superlattice structures.

Disruptive Conduct: The Impact of Disruptive Technologies on Social Relations in Higher Education

Science.gov (United States)

Flavin, Michael

2016-01-01

Higher education institutions (HEIs) have invested significantly in digital technologies for learning and teaching. However, technologies provided by HEIs have not been universally successful in terms of adoption and usage. Meanwhile, both students and lecturers use disruptive technologies to support learning and teaching. This article examines…

Formation of ultralong copper nanowires by hydrothermal growth for transparent conducting applications

Science.gov (United States)

Balela, Mary Donnabelle L.; Tan, Michael

2017-07-01

Transparent conducting electrodes are key components of optoelectronic devices, such as touch screens, organic light emitting diodes (OLEDs) and solar cells. Recent market surveys have shown that the demands for these devices are rapidly growing at a tremendous rate. Semiconducting oxides, in particular indium tin oxide (ITO) are the material of choice for transparent conducting electrodes. However, these conventional oxides are typically brittle, which limits their applicability in flexible electronics. Metal nanowires, e.g. copper (Cu) nanowires, are considered as the best candidate as substitute for ITO due to their excellent mechanical and electrical properties. In this paper, ultralong copper (Cu) nanowires with were successfully prepared by hydrothermal growth at 50-80°C for 1 h. Ethylenediamine was employed as the structure-directing agents, while hydrazine was used as the reductant. In situ mixed potential measurement was also carried out to monitor Cu deposition. Higher temperature shifted the mixed potential negatively, leading to thicker Cu nanowires. Transparent conducting electrode, with a sheet resistance of 197 Ω sq-1 at an optical transmittance of around 61 %, was fabricated with the Cu nanowire ink.

Conduct Disorder and Neighborhood Effects.

Science.gov (United States)

Jennings, Wesley G; Perez, Nicholas M; Reingle Gonzalez, Jennifer M

2018-05-07

There has been a considerable amount of scholarly attention to the relationship between neighborhood effects and conduct disorder, particularly in recent years. Having said this, it has been nearly two decades since a comprehensive synthesis of this literature has been conducted. Relying on a detailed and comprehensive search strategy and inclusion criteria, this article offers a systematic and interdisciplinary review of 47 empirical studies that have examined neighborhood effects and conduct disorder. Described results suggest that there are generally robust linkages between adverse neighborhood factors and conduct disorder and externalizing behavior problems, as 67 of the 93 (72.04%) effect sizes derived from these studies yielded statistically significant neighborhood effects. The review also identifies salient mediating and moderating influences. It discusses study limitations and directions for future research as well.

The Process of Change in Higher Education Institutions. AAHE-ERIC/Higher Education Research Report, No. 7, 1982.

Science.gov (United States)

Nordvall, Robert C.

Conditions that inhibit change in higher education institutions and various models of the change process are described. Attention is also directed to: organizational character, structural features, planning procedures, key individuals in the change process, and practical advice about change. The major change models for higher education…

Combined effects of cooled EGR and a higher geometric compression ratio on thermal efficiency improvement of a downsized boosted spark-ignition direct-injection engine

International Nuclear Information System (INIS)

Su, Jianye; Xu, Min; Li, Tie; Gao, Yi; Wang, Jiasheng

2014-01-01

Highlights: • Experiments for the effects of cooled EGR and two compression ratios (CR) on fuel efficiency were conducted. • The mechanism for the observed fuel efficiency behaviors by cooled EGR and high CR was clarified. • Cooled EGR offers more fuel efficiency improvement than elevating CR from 9.3 to 10.9. • Combining 18–25% cooled EGR with 10.9 CR lead to 2.1–3.5% brake thermal efficiency improvements. - Abstract: The downsized boosted spark-ignition direct-injection (SIDI) engine has proven to be one of the most promising concepts to improve vehicle fuel economy. However, the boosted engine is typically designed at a lower geometric compression ratio (CR) due to the increased knock tendency in comparison to naturally aspirated engines, limiting the potential of improving fuel economy. On the other hand, cooled exhaust gas recirculation (EGR) has drawn attention due to the potential to suppress knock and improve fuel economy. Combing the effects of boosting, increased CR and cooled EGR to further improve fuel economy within acceptable knock tolerance has been investigated using a 2.0 L downsized boosted SIDI engine over a wide range of engine operating conditions from 1000 rpm to 3000 rpm at low to high loads. To clarify the mechanism of this complicated effects, the first law of thermodynamics analysis was conducted with the inputs from GT-Power® engine simulation. Experiment results indicate that cooled EGR provides more brake thermal efficiency improvement than increasing geometric CR from 9.3 to 10.9. The benefit of brake thermal efficiency from the higher CR is limited to low load conditions. The attributes for improving brake thermal efficiency by cooled EGR include reduced heat transfer loss, reduced pumping work and increased ratio of specific heats for all the engine operating conditions, as well as higher degree of constant volume heat release only for the knock-limited high load conditions. The combined effects of 18–25% cooled EGR

Dependence of the optical conductivity on the uniaxial and biaxial strains in black phosphorene

Science.gov (United States)

Yang, C. H.; Zhang, J. Y.; Wang, G. X.; Zhang, C.

2018-06-01

By using the Kubo formula, the optical conductivity of strained black phosphorene was studied. The anisotropic band dispersion gives rise to an orientation dependent optical conductivity. The energy gap can be tuned by the uniaxial and biaxial strains which can be observed from the interband optical conductivity polarized along the armchair (x ) direction. The preferential conducting direction is along the x direction. The dependence of the intraband optical conductivity along the zigzag (y ) direction on the Fermi energy and strain exhibits increasing or decreasing monotonously. However, along the x direction this dependence is complicated which originates from the carriers' inverse-direction movements obtained by two types of the nearest phosphorus atom interactions. The modification of the biaxial strain on the energy structure and optical-absorption property is more effective. The imaginary part of the total optical conductivity (Im σ ) can be negative around the threshold of the interband optical transition by modifying the chemical potential. Away from this frequency region, Im σ exhibits positive value. It can be used in the application of the surface plasmon propagations in multilayer dielectric structures.

Shear deformation-induced anisotropic thermal conductivity of graphene.

Science.gov (United States)

Cui, Liu; Shi, Sanqiang; Wei, Gaosheng; Du, Xiaoze

2018-01-03

Graphene-based materials exhibit intriguing phononic and thermal properties. In this paper, we have investigated the heat conductance in graphene sheets under shear-strain-induced wrinkling deformation, using equilibrium molecular dynamics simulations. A significant orientation dependence of the thermal conductivity of graphene wrinkles (GWs) is observed. The directional dependence of the thermal conductivity of GWs stems from the anisotropy of phonon group velocities as revealed by the G-band broadening of the phonon density of states (DOS), the anisotropy of thermal resistance as evidenced by the G-band peak mismatch of the phonon DOS, and the anisotropy of phonon relaxation times as a direct result of the double-exponential-fitting of the heat current autocorrelation function. By analyzing the relative contributions of different lattice vibrations to the heat flux, we have shown that the contributions of different lattice vibrations to the heat flux of GWs are sensitive to the heat flux direction, which further indicates the orientation-dependent thermal conductivity of GWs. Moreover, we have found that, in the strain range of 0-0.1, the anisotropy ratio of GWs increases monotonously with increasing shear strain. This is induced by the change in the number of wrinkles, which is more influential in the direction perpendicular to the wrinkle texture. The findings elucidated here emphasize the utility of wrinkle engineering for manipulation of nanoscale heat transport, which offers opportunities for the development of thermal channeling devices.

Ionic Conductivity of Polyelectrolyte Hydrogels.

Science.gov (United States)

Lee, Chen-Jung; Wu, Haiyan; Hu, Yang; Young, Megan; Wang, Huifeng; Lynch, Dylan; Xu, Fujian; Cong, Hongbo; Cheng, Gang

2018-02-14

Polyelectrolytes have many important functions in both living organisms and man-made applications. One key property of polyelectrolytes is the ionic conductivity due to their porous networks that allow the transport of water and small molecular solutes. Among polyelectrolytes, zwitterionic polymers have attracted huge attention for applications that involve ion transport in a polyelectrolyte matrix; however, it is still unclear how the functional groups of zwitterionic polymer side chains affect their ion transport and swelling properties. In this study, zwitterionic poly(carboxybetaine acrylamide), poly(2-methacryloyloxyethyl phosphorylcholine), and poly(sulfobetaine methacrylate) hydrogels were synthesized and their ionic conductivity was studied and compared to cationic, anionic, and nonionic hydrogels. The change of the ionic conductivity of zwitterionic and nonionic hydrogels in different saline solutions was investigated in detail. Zwitterionic hydrogels showed much higher ionic conductivity than that of the widely used nonionic poly(ethylene glycol) methyl ether methacrylate hydrogel in all tested solutions. For both cationic and anionic hydrogels, the presence of mobile counterions led to high ionic conductivity in low salt solutions; however, the ionic conductivity of zwitterionic hydrogels surpassed that of cationic and ionic hydrogels in high salt solutions. Cationic and anionic hydrogels showed much higher water content than that of zwitterionic hydrogels in deionized water; however, the cationic hydrogels shrank significantly with increasing saline concentration. This work provides insight into the effects of polyelectrolyte side chains on ion transport. This can guide us in choosing better polyelectrolytes for a broad spectrum of applications, including bioelectronics, neural implants, battery, and so on.

Emissions characteristics of higher alcohol/gasoline blends

International Nuclear Information System (INIS)

Gautam, M.; Martin, D.W.; Carder, D.

2000-01-01

An experimental investigation was conducted to determine the emissions characteristics of higher alcohols and gasoline (UTG96) blends. While lower alcohols (methanol and ethanol) have been used in blends with gasoline, very little work has been done or reported on higher alcohols (propanol, butanol and pentanol). Comparisons of emissions and fuel characteristics between higher alcohol/gasoline blends and neat gasoline were made to determine the advantages and disadvantages of blending higher alcohols with gasoline. All tests were conducted on a single-cylinder Waukesha Cooperative Fuel Research engine operating at steady state conditions and stoichiometric air-fuel (A/F) ratio. Emissions test were conducted at the optimum spark timing-knock limiting compression ratio combination for the particular blend being tested. The cycle emission [mass per unit time (g/h)] of CO, CO 2 and organic matter hydrocarbon equivalent (OMHCE) from the higher alcohol/gasoline blends were very similar to those from neat gasoline. Cycle emissions of NO x from the blends were higher than those from neat gasoline. However, for all the emissions species considered, the brake specific emissions (g/kW h) were significantly lower for the higher alcohol/gasoline blends than for neat gasoline. This was because the blends had greater resistance to knock and allowed higher compression ratios, which increased engine power output. The contribution of alcohols and aldehydes to the overall OMHCE emissions was found to be minimal. Cycle fuel consumption (g/h) of higher alcohol/gasoline blends was slightly higher than with neat gasoline due to the lower stoichiometric A/F ratios required by the blends. However, the brake specific fuel consumption (g/kW h) for the blends was significantly lower than that for neat gasoline. (Author)

Mordenite/Nafion and analcime/Nafion composite membranes prepared by spray method for improved direct methanol fuel cell performance

Science.gov (United States)

Prapainainar, Paweena; Du, Zehui; Kongkachuichay, Paisan; Holmes, Stuart M.; Prapainainar, Chaiwat

2017-11-01

The aim of this work was to improve proton exchange membranes (PEMs) used in direct methanol fuel cells (DMFCs). A membrane with a high proton conductivity and low methanol permeability was required. Zeolite filler in Nafion (NF matrix) composite membranes were prepared using two types of zeolite, mordenite (MOR) and analcime (ANA). Spray method was used to prepare the composite membranes, and properties of the membranes were investigated: mechanical properties, solubility, water and methanol uptake, ion-exchange capacity (IEC), proton conductivity, methanol permeability, and DMFC performance. It was found that MOR filler showed higher performance than ANA. The MOR/Nafion composite membrane gave better properties than ANA/Nafion composite membrane, including a higher proton conductivity and a methanol permeability that was 2-3 times lower. The highest DMFC performance (10.75 mW cm-2) was obtained at 70 °C and with 2 M methanol, with a value 1.5 times higher than that of ANA/Nafion composite membrane and two times higher than that of commercial Nafion 117 (NF 117).

Why do Accounting Students at Higher Learning Institutions Conduct an Academic Dishonesty?

Directory of Open Access Journals (Sweden)

Mustikarini Arizona

2017-01-01

Full Text Available Academic dishonesty is a serious educational problem. Moreover, the tendency to cheat at workplace appertain with the frequency of cheating in college. This study aims to empirically examine the influence of individual factors and situational factors to the intention of accounting students to conduct an academic dishonesty. This study uses survey as data collection technique by employing a set of a questionnaire. This result of this research finds that attitudes, subjective norms, and perceived behavioural control have positive and significant effects to the intention of the accounting students to commit an academic dishonesty. However, among three situational factors only pressure and definitional ambiguity that have a positive and significant effect to the intention of accounting students.

Education Pays, 2010: The Benefits of Higher Education for Individuals and Society. Trends in Higher Education Series

Science.gov (United States)

Baum, Sandy; Ma, Jennifer; Payea, Kathleen

2010-01-01

Students who attend institutions of higher education obtain a wide range of personal, financial, and other lifelong benefits; likewise, taxpayers and society as a whole derive a multitude of direct and indirect benefits when citizens have access to postsecondary education. Accordingly, uneven rates of participation in higher education across…

Effect of triangular vacancy defect on thermal conductivity and thermal rectification in graphene nanoribbons

Energy Technology Data Exchange (ETDEWEB)

Yang, Ping, E-mail: yangpingdm@ujs.edu.cn [Laboratory of Advanced Manufacturing and Reliability for MEMS/NEMS/OEDS, Jiangsu University, Zhenjiang 212013 (China); Li, Xialong; Zhao, Yanfan [Laboratory of Advanced Manufacturing and Reliability for MEMS/NEMS/OEDS, Jiangsu University, Zhenjiang 212013 (China); Yang, Haiying [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Wang, Shuting, E-mail: wangst@mail.hust.edu.cn [School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

2013-11-01

We investigate the thermal transport properties of armchair graphene nanoribbons (AGNRs) possessing various sizes of triangular vacancy defect within a temperature range of 200–600 K by using classical molecular dynamics simulation. The results show that the thermal conductivities of the graphene nanoribbons decrease with increasing sizes of triangular vacancy defects in both directions across the whole temperature range tested, and the presence of the defect can decrease the thermal conductivity by more than 40% as the number of removed cluster atoms is increased to 25 (1.56% for vacancy concentration) owing to the effect of phonon–defect scattering. In the meantime, we find the thermal conductivity of defective graphene nanoribbons is insensitive to the temperature change at higher vacancy concentrations. Furthermore, the dependence of temperatures and various sizes of triangular vacancy defect for the thermal rectification ration are also detected. This work implies a possible route to achieve thermal rectifier for 2D materials by defect engineering.

Red mud enhances methanogenesis with the simultaneous improvement of hydrolysis-acidification and electrical conductivity.

Science.gov (United States)

Ye, Jie; Hu, Andong; Ren, Guoping; Zhou, Ting; Zhang, Guangming; Zhou, Shungui

2018-01-01

The role of red mud in the improvement of methanogenesis during sludge anaerobic digestion was innovatively investigated in this study. The results demonstrated that the addition of 20g/L red mud resulted in a 35.5% increase in methane accumulation. Red mud effectively promoted the hydrolysis-acidification of organic compounds in the sludge, which resulted in the increase of protein, polysaccharide, and VFAs by 5.1-94.5%. The activities of key enzymes were improved by 41.4-257.3%. Electrochemical measurements presented direct evidence that the electrical conductivity was significantly improved with red mud. More conductive magnetite was formed during the secondary mineralization after Fe(III) reduction by Fe (III)-reducing genes such as Clostridiaceae and Ruminococcaceae. The higher conductivity enhanced the electron transfer between the syntrophic bacteria (Geobacteraceae) and methanogens (Methanosaeta and Methanosarcina), and then improved the methanogenesis. This research provides a novel perspective on the synergism between sludge and red mud for methane production. Copyright © 2017 Elsevier Ltd. All rights reserved.

SPEEK-MO{sub 2} (M = Zr, Sn) composite membranes for direct ethanol fuel cell: an inorganic modification of proton conductive

Energy Technology Data Exchange (ETDEWEB)

Kawaguti, Carla A.; Gomes, Ailton S. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Macromoleculas Eloisa Mano], e-mail: kawagutica@gmail.com

2007-07-01

Organic-inorganic composite membranes based on sulfonated poly(ether ether ketone) (SPEEK) for application in the direct ethanol fuel cell (DEFC) were synthesized. Particle of sulfated zirconia/tin oxide (SO{sub 4}{sup 2-}/ZrO{sub 2}, SnO{sub 2}, SO{sub 3}-/SnO{sub 2}) was synthesized by sol-gel method, and composite membranes with different oxide and different oxide contents were prepared from a mixture of SO{sub 4}{sup 2-}/ZrO{sub 2} or SnO{sub 2} or SO{sub 3}-/SnO{sub 2} powder and SPEEK solution. The physico-chemical properties of the membranes were studied by water or ethanol solution uptake measurements, scanning electron microscopy (SEM), the membrane's water and ethanol permeabilities were evaluated in pervaporation experiments and the conductivity determined by impedance spectroscopy. The ethanol permeabilities were decreased by inorganic modification. At several temperatures analysed, all SPEEK-MO{sub 2} composite exhibited better ethanol solution uptake than water uptake and this sorption is decreased when inorganic particles are add. A reduction of the proton conductivity by the inorganic modification was observed. (author)

Direct-current substrate bias effects on amorphous silicon sputter-deposited films for thin film transistor fabrication

International Nuclear Information System (INIS)

Jun, Seung-Ik; Rack, Philip D.; McKnight, Timothy E.; Melechko, Anatoli V.; Simpson, Michael L.

2005-01-01

The effect that direct current (dc) substrate bias has on radio frequency-sputter-deposited amorphous silicon (a-Si) films has been investigated. The substrate bias produces a denser a-Si film with fewer defects compared to unbiased films. The reduced number of defects results in a higher resistivity because defect-mediated conduction paths are reduced. Thin film transistors (TFTs) that were completely sputter deposited were fabricated and characterized. The TFT with the biased a-Si film showed lower leakage (off-state) current, higher on/off current ratio, and higher transconductance (field effect mobility) than the TFT with the unbiased a-Si film

The decision to conduct a head-to-head comparative trial: a game-theoretic analysis.

Science.gov (United States)

Mansley, Edward C; Elbasha, Elamin H; Teutsch, Steven M; Berger, Marc L

2007-01-01

Recent Medicare legislation calls on the Agency for Healthcare Research and Quality to conduct research related to the comparative effectiveness of health care items and services, including prescription drugs. This reinforces earlier calls for head-to-head comparative trials of clinically relevant treatment alternatives. Using a game-theoretic model, the authors explore the decision of pharmaceutical companies to conduct such trials. The model suggests that an important factor affecting this decision is the potential loss in market share and profits following a result of inferiority or comparability. This hidden cost is higher for the market leader than the market follower, making it less likely that the leader will choose to conduct a trial. The model also suggests that in a full-information environment, it will never be the case that both firms choose to conduct such a trial. Furthermore, if market shares and the probability of proving superiority are similar for both firms, it is quite possible that neither firm will choose to conduct a trial. Finally, the results indicate that incentives that offset the direct cost of a trial can prevent a no-trial equilibrium, even when both firms face the possibility of an inferior outcome.

Pressure dependence of conductivity

International Nuclear Information System (INIS)

Bracewell, B.L.; Hochheimer, H.D.

1993-01-01

The overall objectives of this work were to attempt the following: (1) Measure the pressure dependence of the electrical conductivity of several quasi-one-dimensional, charge-density-wave solids, including measurements along various crystal directions. (2) Measure photocurrents in selected MX solids at ambient and elevated pressures. (3) Measure the resonance Raman spectra for selected MX solids as a function of pressure

Higher Serum Direct Bilirubin Levels Were Associated with a Lower Risk of Incident Chronic Kidney Disease in Middle Aged Korean Men

Science.gov (United States)

Ryu, Seungho; Chang, Yoosoo; Zhang, Yiyi; Woo, Hee-Yeon; Kwon, Min-Jung; Park, Hyosoon; Lee, Kyu-Beck; Son, Hee Jung; Cho, Juhee; Guallar, Eliseo

2014-01-01

Background The association between serum bilirubin levels and incident chronic kidney disease (CKD) in the general population is unknown. We aimed to examine the association between serum bilirubin concentration (total, direct, and indirect) and the risk of incident CKD. Methods and Findings Longitudinal cohort study of 12,823 Korean male workers 30 to 59 years old without CKD or proteinuria at baseline participating in medical health checkup program in a large worksite. Study participants were followed for incident CKD from 2002 through 2011. Estimated glomerular filtration rate (eGFR) was estimated by using the CKD-EPI equation. CKD was defined as eGFR bilirubin were 0.93 (95% CI 0.67–1.28), 0.88 (0.60–1.27) and 0.60 (0.42–0.88), respectively. In multivariable models, the adjusted hazard ratio for CKD comparing the highest to the lowest quartile of serum direct bilirubin levels was 0.60 (95% CI 0.41–0.87; P trend = 0.01). Neither serum total nor indirect bilirubin levels were significantly associated with the incidence of CKD. Conclusions Higher serum direct bilirubin levels were significantly associated with a lower risk of developing CKD, even adjusting for a variety of cardiometabolic parameters. Further research is needed to elucidate the mechanisms underlying this association and to establish the role of serum direct bilirubin as a marker for CKD risk. PMID:24586219

Quantized Majorana conductance

Science.gov (United States)

Zhang, Hao; Liu, Chun-Xiao; Gazibegovic, Sasa; Xu, Di; Logan, John A.; Wang, Guanzhong; van Loo, Nick; Bommer, Jouri D. S.; de Moor, Michiel W. A.; Car, Diana; Op Het Veld, Roy L. M.; van Veldhoven, Petrus J.; Koelling, Sebastian; Verheijen, Marcel A.; Pendharkar, Mihir; Pennachio, Daniel J.; Shojaei, Borzoyeh; Lee, Joon Sue; Palmstrøm, Chris J.; Bakkers, Erik P. A. M.; Sarma, S. Das; Kouwenhoven, Leo P.

2018-04-01

Majorana zero-modes—a type of localized quasiparticle—hold great promise for topological quantum computing. Tunnelling spectroscopy in electrical transport is the primary tool for identifying the presence of Majorana zero-modes, for instance as a zero-bias peak in differential conductance. The height of the Majorana zero-bias peak is predicted to be quantized at the universal conductance value of 2e2/h at zero temperature (where e is the charge of an electron and h is the Planck constant), as a direct consequence of the famous Majorana symmetry in which a particle is its own antiparticle. The Majorana symmetry protects the quantization against disorder, interactions and variations in the tunnel coupling. Previous experiments, however, have mostly shown zero-bias peaks much smaller than 2e2/h, with a recent observation of a peak height close to 2e2/h. Here we report a quantized conductance plateau at 2e2/h in the zero-bias conductance measured in indium antimonide semiconductor nanowires covered with an aluminium superconducting shell. The height of our zero-bias peak remains constant despite changing parameters such as the magnetic field and tunnel coupling, indicating that it is a quantized conductance plateau. We distinguish this quantized Majorana peak from possible non-Majorana origins by investigating its robustness to electric and magnetic fields as well as its temperature dependence. The observation of a quantized conductance plateau strongly supports the existence of Majorana zero-modes in the system, consequently paving the way for future braiding experiments that could lead to topological quantum computing.

Markov Chain model for the stochastic behaviors of wind-direction data

International Nuclear Information System (INIS)

Masseran, Nurulkamal

2015-01-01

Highlights: • I develop a Markov chain model to describe about the stochastic and probabilistic behaviors of wind direction data. • I describe some of the theoretical arguments regarding the Markov chain model in term of wind direction data. • I suggest a limiting probabilities approach to determine a dominant directions of wind blow. - Abstract: Analyzing the behaviors of wind direction can complement knowledge concerning wind speed and help researchers draw conclusions regarding wind energy potential. Knowledge of the wind’s direction enables the wind turbine to be positioned in such a way as to maximize the total amount of captured energy and optimize the wind farm’s performance. In this paper, first-order and higher-order Markov chain models are proposed to describe the probabilistic behaviors of wind-direction data. A case study is conducted using data from Mersing, Malaysia. The wind-direction data are classified according to an eight-state Markov chain based on natural geographical directions. The model’s parameters are estimated using the maximum likelihood method and the linear programming formulation. Several theoretical arguments regarding the model are also discussed. Finally, limiting probabilities are used to determine a long-run proportion of the wind directions generated. The results explain the dominant direction for Mersing’s wind in terms of probability metrics

Knowledge and attitude of general pratictioners towards direct-to-consumer genomic tests: a survey conducted in Italy

Directory of Open Access Journals (Sweden)

Anna Baroncini

2015-12-01

Full Text Available Background: Personal genomic tests (PGT offered directly-to-consumers (DTC for complex disease risk assessment have raised several concerns regarding their potential adverse impact. To mitigate worries continuing professional education has been advocated and the central gatekeeper role of family physicians has been highlighted. Nevertheless, to date, only few studies have been published on awareness, involvement and attitudes of  primary healthcare providers on DTC marketing of PGT and, to the best of our knowledge, none in Italy.Methods: An exploratory survey to achieve information about knowledge and attitudes towards DTC-PGT of a selected group of family physicians participating to courses on predictive medicine and public health genomics was conducted. Results: A total amount of 114 partially or fully filled questionnaires was obtained. The majority of the primary care providers (68,4%  expressed that they are unaware that companies are selling genomic tests directly to consumers, while 31,6% was aware.  In terms of attitudes toward testing 61,1% of the aware respondents deemed the DTC-PGT for chronic complex diseases to be ‘‘not clinically useful.’’  The overwhelming majority of our respondents (95,6% felt unprepared to answer patients’ questions on DTC-PGT. If only aware respondents are considered this percentage results obviously  lower (86,1%, though still very high. Conclusion: The low percentage of aware respondents suggests that DTC advertising in the realm of genomic testing is still limited in Italy. Should DTC-PGT become more widely used, a comprehensive education program may be necessary to increase family physicians’ awareness and help them discuss testing with their patients. 

An Innovative High Thermal Conductivity Fuel Design

Energy Technology Data Exchange (ETDEWEB)

Jamil A. Khan

2009-11-21

Thermal conductivity of the fuel in today's Light Water Reactors, Uranium dioxide, can be improved by incorporating a uniformly distributed heat conducting network of a higher conductivity material, Silicon Carbide. The higher thermal conductivity of SiC along with its other prominent reactor-grade properties makes it a potential material to address some of the related issues when used in UO2 [97% TD]. This ongoing research, in collaboration with the University of Florida, aims to investigate the feasibility and develop a formal methodology of producing the resultant composite oxide fuel. Calculations of effective thermal conductivity of the new fuel as a function of %SiC for certain percentages and as a function of temperature are presented as a preliminary approach. The effective thermal conductivities are obtained at different temperatures from 600K to 1600K. The corresponding polynomial equations for the temperature-dependent thermal conductivities are given based on the simulation results. Heat transfer mechanism in this fuel is explained using a finite volume approach and validated against existing empirical models. FLUENT 6.1.22 was used for thermal conductivity calculations and to estimate reduction in centerline temperatures achievable within such a fuel rod. Later, computer codes COMBINE-PC and VENTURE-PC were deployed to estimate the fuel enrichment required, to maintain the same burnup levels, corresponding to a volume percent addition of SiC.

An Innovative High Thermal Conductivity Fuel Design

International Nuclear Information System (INIS)

Khan, Jamil A.

2009-01-01

Thermal conductivity of the fuel in today's Light Water Reactors, Uranium dioxide, can be improved by incorporating a uniformly distributed heat conducting network of a higher conductivity material, Silicon Carbide. The higher thermal conductivity of SiC along with its other prominent reactor-grade properties makes it a potential material to address some of the related issues when used in UO2 (97% TD). This ongoing research, in collaboration with the University of Florida, aims to investigate the feasibility and develop a formal methodology of producing the resultant composite oxide fuel. Calculations of effective thermal conductivity of the new fuel as a function of %SiC for certain percentages and as a function of temperature are presented as a preliminary approach. The effective thermal conductivities are obtained at different temperatures from 600K to 1600K. The corresponding polynomial equations for the temperature-dependent thermal conductivities are given based on the simulation results. Heat transfer mechanism in this fuel is explained using a finite volume approach and validated against existing empirical models. FLUENT 6.1.22 was used for thermal conductivity calculations and to estimate reduction in centerline temperatures achievable within such a fuel rod. Later, computer codes COMBINE-PC and VENTURE-PC were deployed to estimate the fuel enrichment required, to maintain the same burnup levels, corresponding to a volume percent addition of SiC.

Complex conductivity response to silver nanoparticles in ...

Science.gov (United States)

The increase in the use of nanoscale materials in consumer products has resulted in a growing concern of their potential hazard to ecosystems and public health from their accidental or intentional introduction to the environment. Key environmental, health, and safety research needs include knowledge and methods for their detection, characterization, fate, and transport. Specifically, techniques available for the direct detection and quantification of their fate and transport in the environment are limited. Their small size, high surface area to volume ratio, interfacial, and electrical properties make metallic nanoparticles, such as silver nanoparticles, good targets for detection using electrical geophysical techniques. Here we measured the complex conductivity response to silver nanoparticles in sand columns under varying moisture conditions (0–30%), nanoparticle concentrations (0–10 mg/g), lithology (presence of clay), pore water salinity (0.0275 and 0.1000 S/m), and particle size (35, 90–210 and 1500–2500 nm). Based on the Cole-Cole relaxation models we obtained the chargeability and the time constant. We demonstrate that complex conductivity can detect silver nanoparticles in porous media with the response enhanced by higher concentrations of silver nanoparticles, moisture content, ionic strength, clay content and particle diameter. Quantification of the volumetric silver nanoparticles content in the porous media can also be obtained from complex co

Thermal conductivity in Bi0.5Sb1.5Te3+x and the role of dense dislocation arrays at grain boundaries.

Science.gov (United States)

Deng, Rigui; Su, Xianli; Zheng, Zheng; Liu, Wei; Yan, Yonggao; Zhang, Qingjie; Dravid, Vinayak P; Uher, Ctirad; Kanatzidis, Mercouri G; Tang, Xinfeng

2018-06-01

Several prominent mechanisms for reduction in thermal conductivity have been shown in recent years to improve the figure of merit for thermoelectric materials. Such a mechanism is a hierarchical all-length-scale architecturing that recognizes the role of all microstructure elements, from atomic to nano to microscales, in reducing (lattice) thermal conductivity. In this context, there have been recent claims of remarkably low (lattice) thermal conductivity in Bi 0.5 Sb 1.5 Te 3 that are attributed to seemingly ordinary grain boundary dislocation networks. These high densities of dislocation networks in Bi 0.5 Sb 1.5 Te 3 were generated via unconventional materials processing with excess Te (which formed liquid phase, thereby facilitating sintering), followed by spark plasma sintering under pressure to squeeze out the liquid. We reproduced a practically identical microstructure, following practically identical processing strategies, but with noticeably different (higher) thermal conductivity than that claimed before. We show that the resultant microstructure is anisotropic, with notable difference of thermal and charge transport properties across and along two orthonormal directions, analogous to anisotropic crystals. Thus, we believe that grain boundary dislocation networks are not the primary cause of enhanced ZT through reduction in thermal conductivity. Instead, we can reproduce the purported high ZT through a favorable but impractical and incorrect combination of thermal conductivity measured along the pressing direction of anisotropy while charge transport measured in the direction perpendicular to the anisotropic direction. We believe that our work underscores the need for consistency in charge and thermal transport measurements for unified and verifiable measurements of thermoelectric (and related) properties and phenomena.

Experimental investigation of thermal conductivity coefficient and heat exchange between fluidized bed and inclined exchange surface

Directory of Open Access Journals (Sweden)

B. Stojanovic

2009-06-01

Full Text Available The paper presents experimental research of thermal conductivity coefficients of the siliceous sand bed fluidized by air and an experimental investigation of the particle size influence on the heat transfer coefficient between fluidized bed and inclined exchange surfaces. The measurements were performed for the specific fluidization velocity and sand particle diameters d p=0.3, 0.5, 0.9 mm. The industrial use of fluidized beds has been increasing rapidly in the past 20 years owing to their useful characteristics. One of the outstanding characteristics of a fluidized bed is that it tends to maintain a uniform temperature even with nonuniform heat release. On the basis of experimental research, the influence of the process's operational parameters on the obtained values of the bed's thermal conductivity has been analyzed. The results show direct dependence of thermal conductivity on the intensity of mixing, the degree of fluidization, and the size of particles. In the axial direction, the coefficients that have been treated have values a whole order higher than in the radial direction. Comparison of experimental research results with experimental results of other authors shows good agreement and the same tendency of thermal conductivity change. It is well known in the literature that the value of the heat transfer coefficient is the highest in the horizontal and the smallest in the vertical position of the heat exchange surface. Variation of heat transfer, depending on inclination angle is not examined in detail. The difference between the values of the relative heat transfer coefficient between vertical and horizontal heater position for all particle sizes reduces by approximately 15% with the increase of fluidization rate.

Enhanced thermal conductance of polymer composites through embeddingaligned carbon nanofibers

Directory of Open Access Journals (Sweden)

Dale K. Hensley

2016-07-01

Full Text Available The focus of this work is to find a more efficient method of enhancing the thermal conductance of polymer thin films. This work compares polymer thin films embedded with randomly oriented carbon nanotubes to those with vertically aligned carbon nanofibers. Thin films embedded with carbon nanofibers demonstrated a similar thermal conductance between 40–60 μm and a higher thermal conductance between 25–40 μm than films embedded with carbon nanotubes with similar volume fractions even though carbon nanotubes have a higher thermal conductivity than carbon nanofibers.

The Growth of Higher Educators for Social Justice: Collaborative Professional Development in Higher Education

Directory of Open Access Journals (Sweden)

Molly K. Ness, PhD

2010-08-01

Full Text Available In this article, we investigate what happened when, contrary to the typical isolation of faculty in higher education, a group of higher educators from various disciplines in a graduate school of education met regularly to discuss issues related to our teaching and social justice. More specifically, we explored the following research question: How does collaboration among higher educators from various disciplines shape their beliefs and practices of teaching for social justice? Over three years of collaboration and conversation, not only did we expand our own knowledge and understandings of notions of social justice, but we began to take important steps towards increasing our social justice actions in our teaching. This article explores our efforts to create a self-directed professional development group of higher educators and provides suggestions for similarly interested higher educators.

Using Technology to Direct Learning in Higher Education: The Way Forward?

Science.gov (United States)

Turney, C. S. M.; Robinson, D.; Lee, M.; Soutar, A.

2009-01-01

Improvements in technology appear to provide an unprecedented opportunity to improve learning and teaching within the higher education system. At present, however, opinions are divided over the efficacy of such an approach and the extent to which technology should be embraced in teaching. Over a period of two years, we have developed a new…

Auroral ionospheric quiet summer time conductances

International Nuclear Information System (INIS)

Brekke, A.; Hall, C.

1988-01-01

The auroral zone E-region conductivities and conductances have been studied for 7 quiet time summer days. The Hall- and Pedersen conductances are found to follow the solar zenith variations in a rather regular fashion, and empirical formulas for these conductances are obtained. The choice of proper collision frequency models is found to be of great importance when deriving the conductances, and it is argued that some of the different results presented by other authors may be due to different models of the collision frequencies. The Hall- to Pedersen conductance ratios can only be used as an indicator of the energy of the precipitating auroral particles when the contribution from the background solar ionization is subtracted. When this is done this ratio takes much higher values than previously reported

Remarkable reduction of thermal conductivity in phosphorene phononic crystal

International Nuclear Information System (INIS)

Xu, Wen; Zhang, Gang

2016-01-01

Phosphorene has received much attention due to its interesting physical and chemical properties, and its potential applications such as thermoelectricity. In thermoelectric applications, low thermal conductivity is essential for achieving a high figure of merit. In this work, we propose to reduce the thermal conductivity of phosphorene by adopting the phononic crystal structure, phosphorene nanomesh. With equilibrium molecular dynamics simulations, we find that the thermal conductivity is remarkably reduced in the phononic crystal. Our analysis shows that the reduction is due to the depressed phonon group velocities induced by Brillouin zone folding, and the reduced phonon lifetimes in the phononic crystal. Interestingly, it is found that the anisotropy ratio of thermal conductivity could be tuned by the ‘non-square’ pores in the phononic crystal, as the phonon group velocities in the direction with larger projection of pores is more severely suppressed, leading to greater reduction of thermal conductivity in this direction. Our work provides deep insight into thermal transport in phononic crystals and proposes a new strategy to reduce the thermal conductivity of monolayer phosphorene. (paper)

7 CFR 3015.192 - Institutions of higher education.

Science.gov (United States)

2010-01-01

... 7 Agriculture 15 2010-01-01 2010-01-01 false Institutions of higher education. 3015.192 Section....192 Institutions of higher education. (a) OMB Circular No. A-21, including any amendments to the... activities conducted by institutions of higher education (other than for-profit institutions). (b) Additional...

Thermal conductivity of sputtered amorphous Ge films

International Nuclear Information System (INIS)

Zhan, Tianzhuo; Xu, Yibin; Goto, Masahiro; Tanaka, Yoshihisa; Kato, Ryozo; Sasaki, Michiko; Kagawa, Yutaka

2014-01-01

We measured the thermal conductivity of amorphous Ge films prepared by magnetron sputtering. The thermal conductivity was significantly higher than the value predicted by the minimum thermal conductivity model and increased with deposition temperature. We found that variations in sound velocity and Ge film density were not the main factors in the high thermal conductivity. Fast Fourier transform patterns of transmission electron micrographs revealed that short-range order in the Ge films was responsible for their high thermal conductivity. The results provide experimental evidences to understand the underlying nature of the variation of phonon mean free path in amorphous solids

Quantized conductance in an atom-sized point contact

DEFF Research Database (Denmark)

Olesen, L.; Laegsgaard, E.; Stensgaard, I.

1994-01-01

We present direct measurements at room temperature of the conductance of a point contact between a scanning tunneling microscope tip and Ni, Cu, and Pt surfaces. As the contact is stretched the conductance jumps in units of 2e2/h. Atomistic simulations of the stretch of the contact combined...

TEACHING MASTER STUDENTS OF THE DIRECTION «MUSICAL EDUCATION» TO CONDUCT A SCIENTIFIC DISCUSSION IN A FOREIGN LANGUAGE

Directory of Open Access Journals (Sweden)

V. V. Guzikova

2018-01-01

Full Text Available Introduction. In modern education, against the backdrop of rapidly increasing processes of informatization and globalization as well as the requirements of specialists’ mobility, one of the priorities is vocational-oriented education in foreign languages. It ensures the formation of students’ ability to communicate in foreign languages in specific professional, business, scientific spheres and situations, taking into account the peculiarities of their future profession. The aims of this article are the following: to reveal the peculiarities of the organization of teaching foreign languages in the master’s degree of a non-linguistic high school; to present effective methods, approaches, and techniques of working with master students of the direction of “Musical Education”. Methodology and research methods. In the process of the research, such theoretical scientific methods as analysis, synthesis, specification, and generalization were used. The experimental design of the present study was based on the concept of Lifelong Learning. The methods of interview, observation and testing were applied. Results and scientific novelty. The authors have developed a set of exercises for mastering the skills of conducting a scientific discussion by the master students of the direction “Music Education”. The proposed technique has a cross-disciplinary character. It is designed to teach the students how to effectively communicate with colleagues in a foreign (English language when performing professional tasks, including scientific and research activities. The samples of particular tasks are given. Practical significance. The research materials may be of interest to methodologists, educators, and teachers of the system of continuous professional education.

Study on direct determination of uranium and efficient equilibrium factor by gamma-ray spectrometer

International Nuclear Information System (INIS)

Liu Chunkui

1990-01-01

The test principle, test set and surveying methods for conducting gamma-ray spectrometry on conveyer are presented. The conversion coefficient of the spectrometer has been found by using duallinear regression analysis of uranium and radon and their higher and lower bands of gamma-ray spectra. The efficient equilibrium factor can be quickly determined, and the direct determination of uranium in the non-equilibrium condition of uranium and radium can be made

Effective Teaching Methods in Higher Education: Requirements and Barriers.

Science.gov (United States)

Shirani Bidabadi, Nahid; Nasr Isfahani, Ahmmadreza; Rouhollahi, Amir; Khalili, Roya

2016-10-01

Teaching is one of the main components in educational planning which is a key factor in conducting educational plans. Despite the importance of good teaching, the outcomes are far from ideal. The present qualitative study aimed to investigate effective teaching in higher education in Iran based on the experiences of best professors in the country and the best local professors of Isfahan University of Technology. This qualitative content analysis study was conducted through purposeful sampling. Semi-structured interviews were conducted with ten faculty members (3 of them from the best professors in the country and 7 from the best local professors). Content analysis was performed by MAXQDA software. The codes, categories and themes were explored through an inductive process that began from semantic units or direct quotations to general themes. According to the results of this study, the best teaching approach is the mixed method (student-centered together with teacher-centered) plus educational planning and previous readiness. But whenever the teachers can teach using this method confront with some barriers and requirements; some of these requirements are prerequisite in professors' behavior and some of these are prerequisite in professors' outlook. Also, there are some major barriers, some of which are associated with the professors' operation and others are related to laws and regulations. Implications of these findings for teachers' preparation in education are discussed. In the present study, it was illustrated that a good teaching method helps the students to question their preconceptions, and motivates them to learn, by putting them in a situation in which they come to see themselves as the authors of answers, as the agents of responsibility for change. But training through this method has some barriers and requirements. To have an effective teaching; the faculty members of the universities should be awarded of these barriers and requirements as a way to

Effective teaching methods in higher education: requirements and barriers

Directory of Open Access Journals (Sweden)

NAHID SHIRANI BIDABADI

2016-10-01

Full Text Available Introduction: Teaching is one of the main components in educational planning which is a key factor in conducting educational plans. Despite the importance of good teaching, the outcomes are far from ideal. The present qualitative study aimed to investigate effective teaching in higher education in Iran based on the experiences of best professors in the country and the best local professors of Isfahan University of Technology. Methods: This qualitative content analysis study was conducted through purposeful sampling. Semi-structured interviews were conducted with ten faculty members (3 of them from the best professors in the country and 7 from the best local professors. Content analysis was performed by MAXQDA software. The codes, categories and themes were explored through an inductive process that began from semantic units or direct quotations to general themes. Results: According to the results of this study, the best teaching approach is the mixed method (student-centered together with teacher-centered plus educational planning and previous readiness. But whenever the teachers can teach using this method confront with some barriers and requirements; some of these requirements are prerequisite in professors’ behavior and some of these are prerequisite in professors’ outlook. Also, there are some major barriers, some of which are associated with the professors’ operation and others are related to laws and regulations. Implications of these findings for teachers’ preparation in education are discussed. Conclusion: In the present study, it was illustrated that a good teaching method helps the students to question their preconceptions, and motivates them to learn, by putting them in a situation in which they come to see themselves as the authors of answers, as the agents of responsibility for change. But training through this method has some barriers and requirements. To have an effective teaching; the faculty members of the universities

Evaluation in Higher Education

Science.gov (United States)

Bognar, Branko; Bungic, Maja

2014-01-01

One of the means of transforming classroom experience is by conducting action research with students. This paper reports about the action research with university students. It has been carried out within a semester of the course "Methods of Upbringing". Its goal has been to improve evaluation of higher education teaching. Different forms…

Fabrication of High Thermal Conductivity NARloy-Z-Diamond Composite Combustion Chamber Liner for Advanced Rocket Engines

Science.gov (United States)

Bhat, Biliyar N.; Greene, Sandra E.; Singh, Jogender

2016-01-01

This paper describes the process development for fabricating a high thermal conductivity NARloy-Z-Diamond composite (NARloy-Z-D) combustion chamber liner for application in advanced rocket engines. The fabrication process is challenging and this paper presents some details of these challenges and approaches used to address them. Prior research conducted at NASA-MSFC and Penn State had shown that NARloy-Z-40%D composite material has significantly higher thermal conductivity than the state of the art NARloy-Z alloy. Furthermore, NARloy-Z-40 %D is much lighter than NARloy-Z. These attributes help to improve the performance of the advanced rocket engines. Increased thermal conductivity will directly translate into increased turbopump power, increased chamber pressure for improved thrust and specific impulse. Early work on NARloy-Z-D composites used the Field Assisted Sintering Technology (FAST, Ref. 1, 2) for fabricating discs. NARloy-Z-D composites containing 10, 20 and 40vol% of high thermal conductivity diamond powder were investigated. Thermal conductivity (TC) data. TC increased with increasing diamond content and showed 50% improvement over pure copper at 40vol% diamond. This composition was selected for fabricating the combustion chamber liner using the FAST technique.

Execution spaces for simple higher dimensional automata

DEFF Research Database (Denmark)

Raussen, Martin

2012-01-01

Higher dimensional automata (HDA) are highly expressive models for concurrency in Computer Science, cf van Glabbeek (Theor Comput Sci 368(1–2): 168–194, 2006). For a topologist, they are attractive since they can be modeled as cubical complexes—with an inbuilt restriction for directions of allowa......Higher dimensional automata (HDA) are highly expressive models for concurrency in Computer Science, cf van Glabbeek (Theor Comput Sci 368(1–2): 168–194, 2006). For a topologist, they are attractive since they can be modeled as cubical complexes—with an inbuilt restriction for directions...

[Evaluation of hazards caused by magnetic field emitted from magnetotherapy applicator to the users of bone conduction hearing prostheses].

Science.gov (United States)

Zradziński, Patryk; Karpowicz, Jolanta; Gryz, Krzysztof; Leszko, Wiesław

2017-06-27

Low frequency magnetic field, inducing electrical field (Ein) inside conductive structures may directly affect the human body, e.g., by electrostimulation in the nervous system. In addition, the spatial distribution and level of Ein are disturbed in tissues neighbouring the medical implant. Numerical models of magneto-therapeutic applicator (emitting sinusoidal magnetic field of frequency 100 Hz) and the user of hearing implant (based on bone conduction: Bonebridge type - IS-BB or BAHA (bone anchorde hearing aid) type - IS-BAHA) were worked out. Values of Ein were analyzed in the model of the implant user's head, e.g., physiotherapist, placed next to the applicator. It was demonstrated that the use of IS-BB or IS-BAHA makes electromagnetic hazards significantly higher (up to 4-fold) compared to the person without implant exposed to magnetic field heterogeneous in space. Hazards for IS-BAHA users are higher than those for IS-BB users. It was found that applying the principles of directive 2013/35/EU, at exposure to magnetic field below exposure limits the direct biophysical effects of exposure in hearing prosthesis users may exceed relevant limits. Whereas applying principles and limits set up by Polish labor law or the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines, the compliance with the exposure limits also ensures the compliance with relevant limits of electric field induced in the body of hearing implant user. It is necessary to assess individually electromagnetic hazard concerning hearing implant users bearing in mind significantly higher hazards to them compared to person without implant or differences between levels of hazards faced by users of implants of various structural or technological solutions. Med Pr 2017;68(4):469-477. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Evaluation of hazards caused by magnetic field emitted from magnetotherapy applicator to the users of bone conduction hearing prostheses

Directory of Open Access Journals (Sweden)

Patryk Zradziński

2017-08-01

Full Text Available Background: Low frequency magnetic field, inducing electrical field (Ein inside conductive structures may directly affect the human body, e.g., by electrostimulation in the nervous system. In addition, the spatial distribution and level of Ein are disturbed in tissues neighbouring the medical implant. Material and Methods: Numerical models of magneto-therapeutic applicator (emitting sinusoidal magnetic field of frequency 100 Hz and the user of hearing implant (based on bone conduction: Bonebridge type – IS-BB or BAHA (bone anchorde hearing aid type – IS-BAHA were worked out. Values of Ein were analyzed in the model of the implant user’s head, e.g., physiotherapist, placed next to the applicator. Results: It was demonstrated that the use of IS-BB or IS-BAHA makes electromagnetic hazards significantly higher (up to 4-fold compared to the person without implant exposed to magnetic field heterogeneous in space. Hazards for IS-BAHA users are higher than those for IS-BB users. It was found that applying the principles of directive 2013/35/EU, at exposure to magnetic field below exposure limits the direct biophysical effects of exposure in hearing prosthesis users may exceed relevant limits. Whereas applying principles and limits set up by Polish labor law or the International Commission on Non-Ionizing Radiation Protection (ICNIRP guidelines, the compliance with the exposure limits also ensures the compliance with relevant limits of electric field induced in the body of hearing implant user. Conclusions: It is necessary to assess individually electromagnetic hazard concerning hearing implant users bearing in mind significantly higher hazards to them compared to person without implant or differences between levels of hazards faced by users of implants of various structural or technological solutions. Med Pr 2017;68(4:469–477

Low-Temperature Superionic Conductivity in Strained Yttria-Stabilized Zirconia

DEFF Research Database (Denmark)

Sillassen, Michael; Eklund, Per; Pryds, Nini

2010-01-01

Very high lateral ionic conductivities in epitaxial cubic yttria-stabilized zirconia (YSZ) synthesized on single-crystal SrTiO3 and MgO substrates by reactive direct current magnetron sputtering are reported. Superionic conductivities (i.e., ionic conductivities of the order 1 -1cm-1) are observed...... at 500 °C for 58-nm-thick films on MgO. The results indicate a superposition of two parallel contributions - one due to bulk conductivity and one attributable to conduction along the film-substrate interface. Interfacial effects dominate the conductivity at low temperatures (...

76 FR 58420 - Direct Investment Surveys: BE-12, Benchmark Survey of Foreign Direct Investment in the United States

Science.gov (United States)

2011-09-21

...] RIN 0691-AA80 Direct Investment Surveys: BE-12, Benchmark Survey of Foreign Direct Investment in the... of Foreign Direct Investment in the United States. Benchmark surveys are conducted every five years; the prior survey covered 2007. The benchmark survey covers the universe of foreign direct investment...

Empathic Accuracy in Male Adolescents with Conduct Disorder and Higher versus Lower Levels of Callous-Unemotional Traits.

Science.gov (United States)

Martin-Key, N; Brown, T; Fairchild, G

2017-10-01

Adolescents with disruptive behavior disorders are reported to show deficits in empathy and emotion recognition. However, prior studies have mainly used questionnaires to measure empathy or experimental paradigms that are lacking in ecological validity. We used an empathic accuracy (EA) task to study EA, emotion recognition, and affective empathy in 77 male adolescents aged 13-18 years: 37 with Conduct Disorder (CD) and 40 typically-developing controls. The CD sample was divided into higher callous-emotional traits (CD/CU+) and lower callous-unemotional traits (CD/CU-) subgroups using a median split. Participants watched films of actors recalling happy, sad, surprised, angry, disgusted or fearful autobiographical experiences and provided continuous ratings of emotional intensity (assessing EA), as well as naming the emotion (recognition) and reporting the emotion they experienced themselves (affective empathy). The CD and typically-developing groups did not significantly differ in EA and there were also no differences between the CD/CU+ and CD/CU- subgroups. Participants with CD were significantly less accurate than controls in recognizing sadness, fear, and disgust, all ps sadness, fear, and disgust relative to controls, all ps < 0.010, rs ≥ 0.33, whereas the CD/CU+ and CD/CU- subgroups did not differ in affective empathy. These results extend prior research by demonstrating affective empathy and emotion recognition deficits in adolescents with CD using a more ecologically-valid task, and challenge the view that affective empathy deficits are specific to CD/CU+.

Conductive hearing loss and bone conduction devices: restored binaural hearing?

Science.gov (United States)

Agterberg, Martijn J H; Hol, Myrthe K S; Cremers, Cor W R J; Mylanus, Emmanuel A M; van Opstal, John; Snik, Ad F M

2011-01-01

An important aspect of binaural hearing is the proper detection of interaural sound level differences and interaural timing differences. Assessments of binaural hearing were made in patients with acquired unilateral conductive hearing loss (UCHL, n = 11) or congenital UCHL (n = 10) after unilateral application of a bone conduction device (BCD), and in patients with bilateral conductive or mixed hearing loss after bilateral BCD application. Benefit (bilateral versus unilateral listening) was assessed by measuring directional hearing, compensation of the acoustic head shadow, binaural summation and binaural squelch. Measurements were performed after an acclimatization time of at least 10 weeks. Unilateral BCD application was beneficial, but there was less benefit in the patients with congenital UCHL as compared to patients with acquired UCHL. In adults with bilateral hearing loss, bilateral BCD application was clearly beneficial as compared to unilateral BCD application. Binaural summation was present, but binaural squelch could not be proven. To explain the poor results in the patients with congenital UCHL, two factors seemed to be important. First, a critical period in the development of binaural hearing might affect the binaural hearing abilities. Second, crossover stimulation, referring to additional stimulation of the cochlea contralateral to the BCD side, might deteriorate binaural hearing in patients with UCHL. Copyright © 2011 S. Karger AG, Basel.

The Organic Chemistry of Conducting Polymers

Energy Technology Data Exchange (ETDEWEB)

Tolbert, Laren Malcolm [Georgia Inst. of Technology, Atlanta, GA (United States)

2014-12-01

For the last several years, we have examined the fundamental principles of conduction in one-dimensional systems, i.e., molecular “wires”. It is, of course, widely recognized that such systems, as components of electronically conductive materials, function in a two- and three-dimensional milieu. Thus interchain hopping and grain-boundary resistivity are limiting conductivity factors in highly conductive materials, and overall conductivity is a function of through-chain and boundary hopping. We have given considerable attention to the basic principles underlying charge transport (the “rules of the game”) in two-dimensional systems by using model systems which allow direct observation of such processes, including the examination of tunneling and hopping as components of charge transfer. In related work, we have spent considerable effort on the chemistry of conjugated heteropolymers, most especially polythiophens, with the aim of using these most efficient of readily available electroactive polymers in photovoltaic devices.

Probing the bulk ionic conductivity by thin film hetero-epitaxial engineering

KAUST Repository

Pergolesi, Daniele; Roddatis, Vladimir; Fabbri, Emiliana; Schneider, Christof W; Lippert, Thomas; Traversa, Enrico; Kilner, John A

2015-01-01

Highly textured thin films with small grain boundary regions can be used as model systems to directly measure the bulk conductivity of oxygen ion conducting oxides. Ionic conducting thin films and epitaxial heterostructures are also widely used

Creativity in Higher Education

Science.gov (United States)

Gaspar, Drazena; Mabic, Mirela

2015-01-01

The paper presents results of research related to perception of creativity in higher education made by the authors at the University of Mostar from Bosnia and Herzegovina. This research was based on a survey conducted among teachers and students at the University. The authors developed two types of questionnaires, one for teachers and the other…

A Review of Electrospun Conductive Polyaniline Based Nanofiber Composites and Blends: Processing Features, Applications, and Future Directions

Directory of Open Access Journals (Sweden)

Saiful Izwan Abd Razak

2015-01-01

Full Text Available Electrospun polymer nanofibers with high surface area to volume ratio and tunable characteristic are formed through the application of strong electrostatic field. Electrospinning has been identified as a straight forward and viable technique to produce nanofibers from polymer solution as their initial precursor. These nanofiber materials have attracted attention of researchers due to their enhanced and exceptional nanostructural characteristics. Electrospun polyaniline (PANI based nanofiber is one of the important new materials for the rapidly growing technology development such as nanofiber based sensor devices, conductive tissue engineering scaffold materials, supercapacitors, and flexible solar cells applications. PANI however is relatively hard to process compared to that of other conventional polymers and plastics. The processing of PANI is daunting, mainly due to its rigid backbone which is related to its high level of conjugation. The challenges faced in the electrospinning processing of neat PANI have alternatively led to the development of the electrospun PANI based composites and blends. A review on the research activities of the electrospinning processing of the PANI based nanofibers, the potential prospect in various fields, and their future direction are presented.

Synchronized conductivity modulation to realize broadband lossless magnetic-free non-reciprocity.

Science.gov (United States)

Dinc, Tolga; Tymchenko, Mykhailo; Nagulu, Aravind; Sounas, Dimitrios; Alu, Andrea; Krishnaswamy, Harish

2017-10-06

Recent research has explored the spatiotemporal modulation of permittivity to break Lorentz reciprocity in a manner compatible with integrated-circuit fabrication. However, permittivity modulation is inherently weak and accompanied by loss due to carrier injection, particularly at higher frequencies, resulting in large insertion loss, size, and/or narrow operation bandwidths. Here, we show that the presence of absorption in an integrated electronic circuit may be counter-intuitively used to our advantage to realize a new generation of magnet-free non-reciprocal components. We exploit the fact that conductivity in semiconductors provides a modulation index several orders of magnitude larger than permittivity. While directly associated with loss in static systems, we show that properly synchronized conductivity modulation enables loss-free, compact and extremely broadband non-reciprocity. We apply these concepts to obtain a wide range of responses, from isolation to gyration and circulation, and verify our findings by realizing a millimeter-wave (25 GHz) circulator fully integrated in complementary metal-oxide-semiconductor technology.Optical non-reciprocity achieved through refractive index modulation can have its challenges and limitations. Here, Dinc et al. introduce the concept of non-reciprocity based on synchronized spatio-temporal modulation of conductivity to achieve different types of non-reciprocal functionality.

Proton exchange membrane materials for the advancement of direct methanol fuel-cell technology

Science.gov (United States)

Cornelius, Christopher J [Albuquerque, NM

2006-04-04

A new class of hybrid organic-inorganic materials, and methods of synthesis, that can be used as a proton exchange membrane in a direct methanol fuel cell. In contrast with Nafion.RTM. PEM materials, which have random sulfonation, the new class of materials have ordered sulfonation achieved through self-assembly of alternating polyimide segments of different molecular weights comprising, for example, highly sulfonated hydrophilic PDA-DASA polyimide segment alternating with an unsulfonated hydrophobic 6FDA-DAS polyimide segment. An inorganic phase, e.g., 0.5 5 wt % TEOS, can be incorporated in the sulfonated polyimide copolymer to further improve its properties. The new materials exhibit reduced swelling when exposed to water, increased thermal stability, and decreased O.sub.2 and H.sub.2 gas permeability, while retaining proton conductivities similar to Nafion.RTM.. These improved properties may allow direct methanol fuel cells to operate at higher temperatures and with higher efficiencies due to reduced methanol crossover.

Remarks about the Bill of 23 March 2017 of the “Directive of the Minister of Science and Higher Education, Republic of Poland, dated ………… 2017”

Directory of Open Access Journals (Sweden)

Michał Kokowski

2017-12-01

Full Text Available The article discuses the Bill of 23 March 2017 of the “Directive of the Minister of Science and Higher Education, Republic of Poland, dated ………… 2017”. It indicates serious flaws of this Bill regarding legislation and the science of science (including bibliometrics, and proposes significant amendments to the content of the provisions of this Directive.

Computational analysis of electrical conduction in hybrid nanomaterials with embedded non-penetrating conductive particles

Science.gov (United States)

Cai, Jizhe; Naraghi, Mohammad

2016-08-01

In this work, a comprehensive multi-resolution two-dimensional (2D) resistor network model is proposed to analyze the electrical conductivity of hybrid nanomaterials made of insulating matrix with conductive particles such as CNT reinforced nanocomposites and thick film resistors. Unlike existing approaches, our model takes into account the impenetrability of the particles and their random placement within the matrix. Moreover, our model presents a detailed description of intra-particle conductivity via finite element analysis, which to the authors’ best knowledge has not been addressed before. The inter-particle conductivity is assumed to be primarily due to electron tunneling. The model is then used to predict the electrical conductivity of electrospun carbon nanofibers as a function of microstructural parameters such as turbostratic domain alignment and aspect ratio. To simulate the microstructure of single CNF, randomly positioned nucleation sites were seeded and grown as turbostratic particles with anisotropic growth rates. Particle growth was in steps and growth of each particle in each direction was stopped upon contact with other particles. The study points to the significant contribution of both intra-particle and inter-particle conductivity to the overall conductivity of hybrid composites. Influence of particle alignment and anisotropic growth rate ratio on electrical conductivity is also discussed. The results show that partial alignment in contrast to complete alignment can result in maximum electrical conductivity of whole CNF. High degrees of alignment can adversely affect conductivity by lowering the probability of the formation of a conductive path. The results demonstrate approaches to enhance electrical conductivity of hybrid materials through controlling their microstructure which is applicable not only to carbon nanofibers, but also many other types of hybrid composites such as thick film resistors.

Method for Measuring Thermal Conductivity of Small Samples Having Very Low Thermal Conductivity

Science.gov (United States)

Miller, Robert A.; Kuczmarski, Maria a.

2009-01-01

This paper describes the development of a hot plate method capable of using air as a standard reference material for the steady-state measurement of the thermal conductivity of very small test samples having thermal conductivity on the order of air. As with other approaches, care is taken to ensure that the heat flow through the test sample is essentially one-dimensional. However, unlike other approaches, no attempt is made to use heated guards to block the flow of heat from the hot plate to the surroundings. It is argued that since large correction factors must be applied to account for guard imperfections when sample dimensions are small, it may be preferable to simply measure and correct for the heat that flows from the heater disc to directions other than into the sample. Experimental measurements taken in a prototype apparatus, combined with extensive computational modeling of the heat transfer in the apparatus, show that sufficiently accurate measurements can be obtained to allow determination of the thermal conductivity of low thermal conductivity materials. Suggestions are made for further improvements in the method based on results from regression analyses of the generated data.

Thermal conductivity of polymer composites with oriented boron nitride

International Nuclear Information System (INIS)

Ahn, Hong Jun; Eoh, Young Jun; Park, Sung Dae; Kim, Eung Soo

2014-01-01

Highlights: • Thermal conductivity depended on the orientation of BN in the polymer matrices. • Hexagonal boron nitride (BN) particles were treated by C 27 H 27 N 3 O 2 and C 14 H 6 O 8 . • Amphiphilic-agent-treated BN particles are more easily oriented in the composite. • BN/PVA composites with C 14 H 6 O 8 -treated BN showed the highest thermal conductivity. • Thermal conductivity of the composites was compared with several theoretical models. - Abstract: Thermal conductivity of boron nitride (BN) with polyvinyl alcohol (PVA) and/or polyvinyl butyral (PVB) was investigated as a function of the degree of BN orientation, the numbers of hydroxyl groups in the polymer matrices and the amphiphilic agents used. The composites with in-plane orientation of BN showed a higher thermal conductivity than the composites with out-of-plane orientation of BN due to the increase of thermal pathway. For a given BN content, the composites with in-plane orientation of BN/PVA showed higher thermal conductivity than the composites with in-plane orientation of BN/PVB. This result could be attributed to the improved degree of orientation of BN, caused by a larger number of hydroxyl groups being present. Those treated with C 14 H 6 O 8 amphiphilic agent demonstrated a higher thermal conductivity than those treated by C 27 H 27 N 3 O 2 . The measured thermal conductivity of the composites was compared with that predicted by the several theoretical models

Conduction anisotropy of the Bechgaard salts

International Nuclear Information System (INIS)

Kezsmarki, I.; Zamborszky, F.; Mihaly, G.; Montgomery, L.K.; Indiana Univ., Bloomington, IN

1999-01-01

We report the results of a systematic study on the temperature dependence of the normal state conductivity, measured along the a, b', and c * axis, in a representative set of Bechgaard salts. The anisotropic electron transport of four compounds are compared: (TMTSF) 2 ClO 4 , (TMTSF) 2 PF 6 , (TMTTF) 2 Br and (TMTTF) 2 PF 6 . We analyze the tendency, following this order of the compounds, of the metallic ab' plane conductivity change to a semiconductor like behavior, and we discuss the mechanism of inter- and intra-chain transport. The c * -direction conduction is determined by the nature of the counter-ion and seems to be irrelevant in this comparison. (orig.)

Effect of higher order nonlinearity, directionality and finite water depth on wave statistics: Comparison of field data and numerical simulations

Science.gov (United States)

Fernández, Leandro; Monbaliu, Jaak; Onorato, Miguel; Toffoli, Alessandro

2014-05-01

This research is focused on the study of nonlinear evolution of irregular wave fields in water of arbitrary depth by comparing field measurements and numerical simulations.It is now well accepted that modulational instability, known as one of the main mechanisms for the formation of rogue waves, induces strong departures from Gaussian statistics. However, whereas non-Gaussian properties are remarkable when wave fields follow one direction of propagation over an infinite water depth, wave statistics only weakly deviate from Gaussianity when waves spread over a range of different directions. Over finite water depth, furthermore, wave instability attenuates overall and eventually vanishes for relative water depths as low as kh=1.36 (where k is the wavenumber of the dominant waves and h the water depth). Recent experimental results, nonetheless, seem to indicate that oblique perturbations are capable of triggering and sustaining modulational instability even if khthe aim of this research is to understand whether the combined effect of directionality and finite water depth has a significant effect on wave statistics and particularly on the occurrence of extremes. For this purpose, numerical experiments have been performed solving the Euler equation of motion with the Higher Order Spectral Method (HOSM) and compared with data of short crested wave fields for different sea states observed at the Lake George (Australia). A comparative analysis of the statistical properties (i.e. density function of the surface elevation and its statistical moments skewness and kurtosis) between simulations and in-situ data provides a confrontation between the numerical developments and real observations in field conditions.

Picture perfect: The direct effect of manipulated Instagram photos on body image in adolescent girls

OpenAIRE

Kleemans, M.; Daalmans, S.; Carbaat, I.; Anschutz, D.J.

2018-01-01

This study investigates the effect of manipulated Instagram photos on adolescent girls' body image, and whether social comparison tendency moderates this relation. A between-subject experiment was conducted in which 144 girls (14-18 years old) were randomly exposed to either original or manipulated (retouched and reshaped) Instagram selfies. Results showed that exposure to manipulated Instagram photos directly led to lower body image. Especially, girls with higher social comparison tendencies...

Deposition and post-processing techniques for transparent conductive films

Energy Technology Data Exchange (ETDEWEB)

Christoforo, Mark Greyson; Mehra, Saahil; Salleo, Alberto; Peumans, Peter

2017-07-04

In one embodiment, a method is provided for fabrication of a semitransparent conductive mesh. A first solution having conductive nanowires suspended therein and a second solution having nanoparticles suspended therein are sprayed toward a substrate, the spraying forming a mist. The mist is processed, while on the substrate, to provide a semitransparent conductive material in the form of a mesh having the conductive nanowires and nanoparticles. The nanoparticles are configured and arranged to direct light passing through the mesh. Connections between the nanowires provide conductivity through the mesh.

Investigation of tDCS volume conduction effects in a highly realistic head model

Science.gov (United States)

Wagner, S.; Rampersad, S. M.; Aydin, Ü.; Vorwerk, J.; Oostendorp, T. F.; Neuling, T.; Herrmann, C. S.; Stegeman, D. F.; Wolters, C. H.

2014-02-01

Objective. We investigate volume conduction effects in transcranial direct current stimulation (tDCS) and present a guideline for efficient and yet accurate volume conductor modeling in tDCS using our newly-developed finite element (FE) approach. Approach. We developed a new, accurate and fast isoparametric FE approach for high-resolution geometry-adapted hexahedral meshes and tissue anisotropy. To attain a deeper insight into tDCS, we performed computer simulations, starting with a homogenized three-compartment head model and extending this step by step to a six-compartment anisotropic model. Main results. We are able to demonstrate important tDCS effects. First, we find channeling effects of the skin, the skull spongiosa and the cerebrospinal fluid compartments. Second, current vectors tend to be oriented towards the closest higher conducting region. Third, anisotropic WM conductivity causes current flow in directions more parallel to the WM fiber tracts. Fourth, the highest cortical current magnitudes are not only found close to the stimulation sites. Fifth, the median brain current density decreases with increasing distance from the electrodes. Significance. Our results allow us to formulate a guideline for volume conductor modeling in tDCS. We recommend to accurately model the major tissues between the stimulating electrodes and the target areas, while for efficient yet accurate modeling, an exact representation of other tissues is less important. Because for the low-frequency regime in electrophysiology the quasi-static approach is justified, our results should also be valid for at least low-frequency (e.g., below 100 Hz) transcranial alternating current stimulation.

Optical conductivity of three and two dimensional topological nodal-line semimetals

Science.gov (United States)

Barati, Shahin; Abedinpour, Saeed H.

2017-10-01

The peculiar shape of the Fermi surface of topological nodal-line semimetals at low carrier concentrations results in their unusual optical and transport properties. We analytically investigate the linear optical responses of three- and two-dimensional nodal-line semimetals using the Kubo formula. The optical conductivity of a three-dimensional nodal-line semimetal is anisotropic. Along the axial direction (i.e., the direction perpendicular to the nodal-ring plane), the Drude weight has a linear dependence on the chemical potential at both low and high carrier dopings. For the radial direction (i.e., the direction parallel to the nodal-ring plane), this dependence changes from linear into quadratic in the transition from low into high carrier concentration. The interband contribution into optical conductivity is also anisotropic. In particular, at large frequencies, it saturates to a constant value for the axial direction and linearly increases with frequency along the radial direction. In two-dimensional nodal-line semimetals, no interband optical transition could be induced and the only contribution to the optical conductivity arises from the intraband excitations. The corresponding Drude weight is independent of the carrier density at low carrier concentrations and linearly increases with chemical potential at high carrier doping.

Proton Conducting Fuel Cells where Electrochemistry Meets Material Science

DEFF Research Database (Denmark)

Li, Qingfeng

Fuel cells are electrochemical devices which directly convert the chemical energy of fuels into electrical energy. They are featured of high energy conversion efficiency and minimized pollutant emission. Proton conducting electrolytes are primarily used as separator materials for low and intermed...... science point of view including novel proton conducting materials and non-precious metal catalysts. The discussion will be made with highlights of DTU´s recent research and of course addressing a diverse technical audience.......Fuel cells are electrochemical devices which directly convert the chemical energy of fuels into electrical energy. They are featured of high energy conversion efficiency and minimized pollutant emission. Proton conducting electrolytes are primarily used as separator materials for low...... followed by a review of the state-of-the-art in terms of performance, lifetime and cost. Technically faced challenges are then outlined on a system level and traced back to fundamental issues of the proton conducting mechanisms and materials. Perspectives and future research are sketched from a materials...

Determination of thermal conductivity of magnesium-alloys

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

An indirect method, Angstroms method was adopted and an instrument was designed to determine the thermal conductivity of magnesium metal and alloys. Angstroms method is an axial periodic heat flow technique by which the thermal diffusivity can be measured directly. Then thermal conductivity can be obtained with relation to thermal diffusivity. Compared with the recommended data from the literature the fitted values of the thermal diffiusivity correspond with 3%, and the credible probability of the thermal conductivity in the range of 0-450 ℃ is about 95%. The method is applicable in the given temperature range.

High thermal conductivity of graphite fiber silicon carbide composites for fusion reactor application

International Nuclear Information System (INIS)

Snead, L.L.; Balden, M.; Causey, R.A.; Atsumi, H.

2002-01-01

The benefits of using CVI SiC/graphite fiber composites as low tritium retaining, high thermal conductivity composites for fusion applications are presented. Three-dimensional woven composites have been chemically vapor infiltrated with SiC and their thermophysical properties measured. One material used an intermediate grade graphite fiber in all directions (Amoco P55) while a second material used very high thermal conductive fiber (Amoco K-1100) in the high fiber density direction. The overall void was less than 20%. Strength as measured by four-point bending was comparable to those of SiC/SiC composite. The room temperature thermal conductivity in the high conductivity direction was impressive for both materials, with values >70 W/m K for the P-55 and >420 W/m K for the K-1100 variant. The thermal conductivity was measured as a function of temperature and exceeds the highest thermal conductivity of CVD SiC currently available at fusion relevant temperatures (>600 deg. C). Limited data on the irradiation-induced degradation in thermal conductivity is consistent with carbon fiber composite literature

Particle size effects in the thermal conductivity enhancement of copper-based nanofluids

Directory of Open Access Journals (Sweden)

Sahin Huseyin

2011-01-01

Full Text Available Abstract We present an analysis of the dispersion characteristics and thermal conductivity performance of copper-based nanofluids. The copper nanoparticles were prepared using a chemical reduction methodology in the presence of a stabilizing surfactant, oleic acid or cetyl trimethylammonium bromide (CTAB. Nanofluids were prepared using water as the base fluid with copper nanoparticle concentrations of 0.55 and 1.0 vol.%. A dispersing agent, sodium dodecylbenzene sulfonate (SDBS, and subsequent ultrasonication was used to ensure homogenous dispersion of the copper nanopowders in water. Particle size distribution of the copper nanoparticles in the base fluid was determined by dynamic light scattering. We found that the 0.55 vol.% Cu nanofluids exhibited excellent dispersion in the presence of SDBS. In addition, a dynamic thermal conductivity setup was developed and used to measure the thermal conductivity performance of the nanofluids. The 0.55 vol.% Cu nanofluids exhibited a thermal conductivity enhancement of approximately 22%. In the case of the nanofluids prepared from the powders synthesized in the presence of CTAB, the enhancement was approximately 48% over the base fluid for the 1.0 vol.% Cu nanofluids, which is higher than the enhancement values found in the literature. These results can be directly related to the particle/agglomerate size of the copper nanoparticles in water, as determined from dynamic light scattering.

Sputtered tin oxide and titanium oxide thin films as alternative transparent conductive oxides

Energy Technology Data Exchange (ETDEWEB)

Boltz, Janika

2011-12-12

Alternative transparent conductive oxides to tin doped indium oxide have been investigated. In this work, antimony doped tin oxide and niobium doped titanium oxide have been studied with the aim to prepare transparent and conductive films. Antimony doped tin oxide and niobium doped titanium oxide belong to different groups of oxides; tin oxide is a soft oxide, while titanium oxide is a hard oxide. Both oxides are isolating materials, in case the stoichiometry is SnO{sub 2} and TiO{sub 2}. In order to achieve transparent and conductive films free carriers have to be generated by oxygen vacancies, by metal ions at interstitial positions in the crystal lattice or by cation doping with Sb or Nb, respectively. Antimony doped tin oxide and niobium doped titanium oxide films have been prepared by reactive direct current magnetron sputtering (dc MS) from metallic targets. The process parameters and the doping concentration in the films have been varied. The films have been electrically, optically and structurally analysed in order to analyse the influence of the process parameters and the doping concentration on the film properties. Post-deposition treatments of the films have been performed in order to improve the film properties. For the deposition of transparent and conductive tin oxide, the dominant parameter during the deposition is the oxygen content in the sputtering gas. The Sb incorporation as doping atoms has a minor influence on the electrical, optical and structural properties. Within a narrow oxygen content in the sputtering gas highly transparent and conductive tin oxide films have been prepared. In this study, the lowest resistivity in the as deposited state is 2.9 m{omega} cm for undoped tin oxide without any postdeposition treatment. The minimum resistivity is related to a transition to crystalline films with the stoichiometry of SnO{sub 2}. At higher oxygen content the films turn out to have a higher resistivity due to an oxygen excess. After post

Improved Anode for a Direct Methanol Fuel Cell

Science.gov (United States)

Valdez, Thomas; Narayanan, Sekharipuram

2005-01-01

A modified chemical composition has been devised to improve the performance of the anode of a direct methanol fuel cell. The main feature of the modified composition is the incorporation of hydrous ruthenium oxide into the anode structure. This modification can reduce the internal electrical resistance of the cell and increase the degree of utilization of the anode catalyst. As a result, a higher anode current density can be sustained with a smaller amount of anode catalyst. These improvements can translate into a smaller fuel-cell system and higher efficiency of conversion. Some background information is helpful for understanding the benefit afforded by the addition of hydrous ruthenium oxide. The anode of a direct methanol fuel cell sustains the electro-oxidation of methanol to carbon dioxide in the reaction CH3OH + H2O--->CO2 + 6H(+) + 6e(-). An electrocatalyst is needed to enable this reaction to occur. The catalyst that offers the highest activity is an alloy of approximately equal numbers of atoms of the noble metals platinum and ruthenium. The anode is made of a composite material that includes high-surface-area Pt/Ru alloy particles and a proton-conducting ionomeric material. This composite is usually deposited onto a polymer-electrolyte (proton-conducting) membrane and onto an anode gas-diffusion/current-collector sheet that is subsequently bonded to the proton-conducting membrane by hot pressing. Heretofore, the areal density of noble-metal catalyst typically needed for high performance has been about 8 mg/cm2. However, not all of the catalyst has been utilized in the catalyzed electro-oxidation reaction. Increasing the degree of utilization of the catalyst would make it possible to improve the performance of the cell for a given catalyst loading and/or reduce the catalyst loading (thereby reducing the cost of the cell). The use of carbon and possibly other electronic conductors in the catalyst layer has been proposed for increasing the utilization of the

Single-shot optical conductivity measurement of dense aluminum plasmas

International Nuclear Information System (INIS)

Churina, I. V.; Cho, B.-I.; Bernstein, A.; Stoker, D. S.; Dalton, A.; Symes, D. R.; Ditmire, T.

2009-01-01

The optical conductivity of a dense femtosecond laser-heated aluminum plasma heated to 0.1-1.5 eV was measured using frequency-domain interferometry with chirped pulses, permitting simultaneous observation of optical probe reflectivity and probe pulse phase shift. Coupled with published models of bound-electron contributions to the conductivity, these two independent experimental data yielded a direct measurement of both real and imaginary components of the plasma conductivity.

Code of ethics and conduct for European nursing.

Science.gov (United States)

Sasso, Loredana; Stievano, Alessandro; González Jurado, Máximo; Rocco, Gennaro

2008-11-01

A main identifying factor of professions is professionals' willingness to comply with ethical and professional standards, often defined in a code of ethics and conduct. In a period of intense nursing mobility, if the public are aware that health professionals have committed themselves to the drawing up of a code of ethics and conduct, they will have more trust in the health professional they choose, especially if this person comes from another European Member State. The Code of Ethics and Conduct for European Nursing is a programmatic document for the nursing profession constructed by the FEPI (European Federation of Nursing Regulators) according to Directive 2005/36/EC On recognition of professional qualifications , and Directive 2006/123/EC On services in the internal market, set out by the European Commission. This article describes the construction of the Code and gives an overview of some specific areas of importance. The main text of the Code is reproduced in Appendix 1.

Investigating the Relationship Between Self-Directed Learning Readiness and Time Management Skills in Turkish Undergraduate Nursing Students.

Science.gov (United States)

Ertuğ, Nurcan; Faydali, Saide

The aims of this study were to determine self-directed learning and time management skills of undergraduate nursing students and to investigate the relationship between the concepts. The use of self-directed learning has increased as an educational strategy in recent years. This descriptive and correlational study was conducted with 383 undergraduate nursing students in Turkey. Data were collected using a sociodemographic questionnaire, the Self-Directed Learning Readiness Scale, and Time Management Questionnaire. Mean scores were as follows: self-directed learning readiness, 159.12 (SD = 20.8); time management, 87.75 (SD = 12.1). A moderate positive correlation was found between self-directed learning readiness and time management values. Time management scores were 78.42 when self-directed learning readiness was ≤149 and 90.82 when self-directed learning readiness was ≥ 150, with a statistically significant difference (p = .000). Level of self-directed learning and academic achievement were higher in students who managed their time well.

Glucose oxidase-graphene-chitosan modified electrode for direct electrochemistry and glucose sensing

International Nuclear Information System (INIS)

Kang, Xinhuang; Wang, Jun; Wu, Hong; Aksay, Ilhan A.; Liu, Jun; Lin, Yuehe

2009-01-01

Direct electrochemistry of a glucose oxidase (GOD)/graphene/chitosan nanocomposite was studied. The immobilized enzyme retains its bioactivity, exhibits a surface confined, reversible two-proton and two-electron transfer reaction, and has good stability, activity and a fast heterogeneous electron transfer rate with the rate constant (k s ) of 2.83 s -1 . A much higher enzyme loading (1.12 x 10 -9 mol/cm 2 ) is obtained as compared to the bare glass carbon surface. This GOD/graphene/chitosan nanocomposite film can be used for sensitive detection of glucose. The biosensor exhibits a wider linearity range from 0.08 mM to 12 mM glucose with a detection limit of 0.02 mM and much higher sensitivity (37.93 (micro)A mM -1 cm -2 ) as compared with other nanostructured supports. The excellent performance of the biosensor is attributed to large surface-to-volume ratio and high conductivity of graphene, and good biocompatibility of chitosan, which enhances the enzyme absorption and promotes direct electron transfer between redox enzymes and the surface of electrodes.

78 FR 11141 - BE-577: Quarterly Survey of U.S. Direct Investment Abroad- Direct Transactions of U.S. Reporter...

Science.gov (United States)

2013-02-15

... BE-577: Quarterly Survey of U.S. Direct Investment Abroad-- Direct Transactions of U.S. Reporter With... that it is conducting the mandatory surveys titled BE-577, Quarterly Survey of U.S. Direct Investment Abroad--Direct Transactions of U.S. Reporter with Foreign Affiliate. This survey is authorized by the...

Direct Problem-Based Learning (DPBL): A Framework for Integrating Direct Instruction and Problem-Based Learning Approach

Science.gov (United States)

Winarno, Sri; Muthu, Kalaiarasi Sonai; Ling, Lew Sook

2018-01-01

Direct instruction approach has been widely used in higher education. Many studies revealed that direct instruction improved students' knowledge. The characteristics of direct instruction include the subject delivered through face-to-face interaction with the lecturers and materials that sequenced deliberately and taught explicitly. However,…

Shear-induced changes of electrical conductivity in suspensions

Energy Technology Data Exchange (ETDEWEB)

Crawshaw, John; Meeten, Gerald [Schlumberger Cambridge Research, Cambridge (United Kingdom)

2006-12-15

The effect of shear on electrical conductivity (rheo-conduction) is studied to give information about particle behaviour in suspensions. Past work is reviewed, and expressions are derived for the rheo-conduction of a suspension of nonconducting spheroids in a conducting matrix for current flow, parallel and normal to the suspension flow direction. A simple apparatus to study rheo-conduction in pipe flow is described, and measurements of steady and time-dependent effects are reported for various suspensions of colloidal particles. Suspensions of anisometric rod- and platelike particles at low concentrations showed rheo-conductive changes of sign, magnitude and relaxation that were consistent with the particle shape, concentration and interactions. The rheo-conductive response decreased with increasing volume fraction for platelike kaolinite particles, attributed to orientational jamming. Spherical latex particles gave unexpected rheo-conductive changes consistent with shear disruption of a conductive network of particles. It is concluded that rheo-conduction measurements are a useful adjunct to conventional rheometry. (orig.)

Scanning nanoscale multiprobes for conductivity measurements

DEFF Research Database (Denmark)

Bøggild, Peter; Hansen, Torben Mikael; Kuhn, Oliver

2000-01-01

We report fabrication and measurements with two- and four-point probes with nanoscale dimensions, for high spatial resolution conductivity measurements on surfaces and thin films. By combination of conventional microfabrication and additive three-dimensional nanolithography, we have obtained...... electrode spacings down to 200 nm. At the tips of four silicon oxide microcantilevers, narrow carbon tips are grown in converging directions and subsequently coated with a conducting layer. The probe is placed in contact with a conducting surface, whereby the electrode resistance can be determined....... The nanoelectrodes withstand considerable contact force before breaking. The probe offers a unique possibility to position the voltage sensors, as well as the source and drain electrodes in areas of nanoscale dimensions. ©2000 American Institute of Physics....

Magneto-acousto-electrical Measurement Based Electrical Conductivity Reconstruction for Tissues.

Science.gov (United States)

Zhou, Yan; Ma, Qingyu; Guo, Gepu; Tu, Juan; Zhang, Dong

2018-05-01

Based on the interaction of ultrasonic excitation and magnetoelectrical induction, magneto-acousto-electrical (MAE) technology was demonstrated to have the capability of differentiating conductivity variations along the acoustic transmission. By applying the characteristics of the MAE voltage, a simplified algorithm of MAE measurement based conductivity reconstruction was developed. With the analyses of acoustic vibration, ultrasound propagation, Hall effect, and magnetoelectrical induction, theoretical and experimental studies of MAE measurement and conductivity reconstruction were performed. The formula of MAE voltage was derived and simplified for the transducer with strong directivity. MAE voltage was simulated for a three-layer gel phantom and the conductivity distribution was reconstructed using the modified Wiener inverse filter and Hilbert transform, which was also verified by experimental measurements. The experimental results are basically consistent with the simulations, and demonstrate that the wave packets of MAE voltage are generated at tissue interfaces with the amplitudes and vibration polarities representing the values and directions of conductivity variations. With the proposed algorithm, the amplitude and polarity of conductivity gradient can be restored and the conductivity distribution can also be reconstructed accurately. The favorable results demonstrate the feasibility of accurate conductivity reconstruction with improved spatial resolution using MAE measurement for tissues with conductivity variations, especially suitable for nondispersive tissues with abrupt conductivity changes. This study demonstrates that the MAE measurement based conductivity reconstruction algorithm can be applied as a new strategy for nondestructive real-time monitoring of conductivity variations in biomedical engineering.

Numerical Investigation of the Thermal Conductivity of Graphite Nanofibers

Science.gov (United States)

Hakak Khadem, Masoud

was also investigated using equilibrium molecular dynamics (EMD) with GK relations. Simple Hexagonal (AAA), Bernal (ABA), and Rhombohedral (ABC) stacking forms were considered. The intralayer and interlayer thermal conductivity values were predicted in both zigzag and armchair directions to be in the range of 450-800 W/m.K and 17-55 W/m.K, respectively. Furthermore, non-equilibrium molecular dynamics (NEMD) simulations were used to investigate the thermal conductivity of herringbone graphite nanofibers (GNFs) at room temperature by breaking down the axial and transverse conductivity values into intralayer and interlayer components. The edge effect on a layer's thermal conductivity was investigated by computing the thermal conductivity values in both zigzag and armchair directions of the heat flow. The limiting case of a 90 degree crease angle was used to compare the results with those of single-layer graphene and few-layer graphene. The thermal conductivity values in the axial, transverse in the crease direction, and transverse normal to the crease directions for the case of a five-layer herringbone GNF with a 45-degree crease angle were calculated to be 27 W/m.K, 263 W/m.K, and 1500 W/m.K, respectively.

Policies for Evaluation and Regulation of Higher Education in Brazil (1995-2010), Supporting the Expansion of Private Higher Education

Science.gov (United States)

Barreyro, Gladys Beatriz; Rothen, José Carlos; Santana, Andréia da Cunha Malheiros

2014-01-01

This paper analyzes the routes of the evaluation of higher education in Brazil, from 1995 until 2010. In 1995, during Fernando Henrique Cardoso's administration, higher education began a process of expansion through private enterprise. At that time, evaluation had a key role. The focus was the evaluation of courses conducted by the Ministry of…

Electrically conductive biodegradable polymer composite for nerve regeneration: electricity-stimulated neurite outgrowth and axon regeneration.

Science.gov (United States)

Zhang, Ze; Rouabhia, Mahmoud; Wang, Zhaoxu; Roberge, Christophe; Shi, Guixin; Roche, Phillippe; Li, Jiangming; Dao, Lê H

2007-01-01

Normal and electrically stimulated PC12 cell cultures and the implantation of nerve guidance channels were performed to evaluate newly developed electrically conductive biodegradable polymer composites. Polypyrrole (PPy) doped by butane sulfonic acid showed a significantly higher number of viable cells compared with PPy doped by polystyrenesulfonate after a 6-day culture. The PC12 cells were left to proliferate for 6 days, and the PPy-coated membranes, showing less initial cell adherence, recorded the same proliferation rate as did the noncoated membranes. Direct current electricity at various intensities was applied to the PC12 cell-cultured conductive membranes. After 7 days, the greatest number of neurites appeared on the membranes with a current intensity approximating 1.7-8.4 microA/cm. Nerve guidance channels made of conductive biodegradable composite were implanted into rats to replace 8 mm of sciatic nerve. The implants were harvested after 2 months and analyzed with immunohistochemistry and transmission electron microscopy. The regenerated nerve tissue displayed myelinated axons and Schwann cells that were similar to those in the native nerve. Electrical stimulation applied through the electrically conductive biodegradable polymers therefore enhanced neurite outgrowth in a current-dependent fashion. The conductive polymers also supported sciatic nerve regeneration in rats.

Thermal conductivity of layered borides: The effect of building defects on the thermal conductivity of TmAlB4 and the anisotropic thermal conductivity of AlB2

Directory of Open Access Journals (Sweden)

X. J. Wang

2014-04-01

Full Text Available Rare earth metal borides have attracted great interest due to their unusual properties, such as superconductivity and f-electron magnetism. A recent discovery attributes the tunability of magnetism in rare earth aluminoborides to the effect of so-called “building defects.” In this paper, we report data for the effect of building defects on the thermal conductivities of α-TmAlB4 single crystals. Building defects reduce the thermal conductivity of α-TmAlB4 by ≈30%. At room temperature, the thermal conductivity of AlB2 is nearly a factor of 5 higher than that of α-TmAlB4. AlB2 single crystals are thermally anisotropic with the c-axis thermal conductivity nearly twice the thermal conductivity of the a-b plane. Temperature dependence of the thermal conductivity near and above room temperature reveals that both electrons and phonons contribute substantially to thermal transport in AlB2 with electrons being the dominant heat carriers.

Higher-order Multivariable Polynomial Regression to Estimate Human Affective States

Science.gov (United States)

Wei, Jie; Chen, Tong; Liu, Guangyuan; Yang, Jiemin

2016-03-01

From direct observations, facial, vocal, gestural, physiological, and central nervous signals, estimating human affective states through computational models such as multivariate linear-regression analysis, support vector regression, and artificial neural network, have been proposed in the past decade. In these models, linear models are generally lack of precision because of ignoring intrinsic nonlinearities of complex psychophysiological processes; and nonlinear models commonly adopt complicated algorithms. To improve accuracy and simplify model, we introduce a new computational modeling method named as higher-order multivariable polynomial regression to estimate human affective states. The study employs standardized pictures in the International Affective Picture System to induce thirty subjects’ affective states, and obtains pure affective patterns of skin conductance as input variables to the higher-order multivariable polynomial model for predicting affective valence and arousal. Experimental results show that our method is able to obtain efficient correlation coefficients of 0.98 and 0.96 for estimation of affective valence and arousal, respectively. Moreover, the method may provide certain indirect evidences that valence and arousal have their brain’s motivational circuit origins. Thus, the proposed method can serve as a novel one for efficiently estimating human affective states.

Higher Education, Academic Communities, and the Intellectual Virtues

Science.gov (United States)

Jones, Ward E.

2012-01-01

Because higher education brings members of academic communities in direct contact with students, the reflective higher education student is in an excellent position for developing two important intellectual virtues: confidence and humility. However, academic communities differ as to whether their members reach consensus, and their teaching…

Direct observation of conductive filament formation in Alq3 based organic resistive memories

Energy Technology Data Exchange (ETDEWEB)

Busby, Y., E-mail: yan.busby@unamur.be; Pireaux, J.-J. [Research Center in the Physics of Matter and Radiation (PMR), Laboratoire Interdisciplinaire de Spectroscopie Electronique (LISE), University of Namur, B-5000 Namur (Belgium); Nau, S.; Sax, S. [NanoTecCenter Weiz Forschungsgesellschaft mbH, Franz-Pichler Straße 32, A-8160 Weiz (Austria); List-Kratochvil, E. J. W. [NanoTecCenter Weiz Forschungsgesellschaft mbH, Franz-Pichler Straße 32, A-8160 Weiz (Austria); Institute of Solid State Physics, Graz University of Technology, A-8010 Graz (Austria); Novak, J.; Banerjee, R.; Schreiber, F. [Institute of Applied Physics, Eberhard-Karls-Universität Tübingen, D-72076 Tübingen (Germany)

2015-08-21

This work explores resistive switching mechanisms in non-volatile organic memory devices based on tris(8-hydroxyquinolie)aluminum (Alq{sub 3}). Advanced characterization tools are applied to investigate metal diffusion in ITO/Alq{sub 3}/Ag memory device stacks leading to conductive filament formation. The morphology of Alq{sub 3}/Ag layers as a function of the metal evaporation conditions is studied by X-ray reflectivity, while depth profile analysis with X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry is applied to characterize operational memory elements displaying reliable bistable current-voltage characteristics. 3D images of the distribution of silver inside the organic layer clearly point towards the existence of conductive filaments and allow for the identification of the initial filament formation and inactivation mechanisms during switching of the device. Initial filament formation is suggested to be driven by field assisted diffusion of silver from abundant structures formed during the top electrode evaporation, whereas thermochemical effects lead to local filament inactivation.

Excitation model of pacemaker cardiomyocytes of cardiac conduction system

Science.gov (United States)

Grigoriev, M.; Babich, L.

2015-11-01

Myocardium includes typical and atypical cardiomyocytes - pacemakers, which form the cardiac conduction system. Excitation from the atrioventricular node in normal conditions is possible only in one direction. Retrograde direction of pulses is impossible. The most important prerequisite for the work of cardiomyocytes is the anatomical integrity of the conduction system. Changes in contractile force of the cardiomyocytes, which appear periodically, are due to two mechanisms of self-regulation - heterometric and homeometric. Graphic course of the excitation pulse propagation along the heart muscle more accurately reveals the understanding of the arrhythmia mechanism. These models have the ability to visualize the essence of excitation dynamics. However, they do not have the proper forecasting function for result estimation. Integrative mathematical model enables further investigation of general laws of the myocardium active behavior, allows for determination of the violation mechanism of electrical and contractile function of cardiomyocytes. Currently, there is no full understanding of the topography of pacemakers and ionic mechanisms. There is a need for the development of direction of mathematical modeling and comparative studies of the electrophysiological arrangement of cells of atrioventricular connection and ventricular conduction system.

Higher Order Lagrange Finite Elements In M3D

International Nuclear Information System (INIS)

Chen, J.; Strauss, H.R.; Jardin, S.C.; Park, W.; Sugiyama, L.E.; Fu, G.; Breslau, J.

2004-01-01

The M3D code has been using linear finite elements to represent multilevel MHD on 2-D poloidal planes. Triangular higher order elements, up to third order, are constructed here in order to provide M3D the capability to solve highly anisotropic transport problems. It is found that higher order elements are essential to resolve the thin transition layer characteristic of the anisotropic transport equation, particularly when the strong anisotropic direction is not aligned with one of the Cartesian coordinates. The transition layer is measured by the profile width, which is zero for infinite anisotropy. It is shown that only higher order schemes have the ability to make this layer converge towards zero when the anisotropy gets stronger and stronger. Two cases are considered. One has the strong transport direction partially aligned with one of the element edges, the other doesn't have any alignment. Both cases have the strong transport direction misaligned with the grid line by some angles

Geometric model for softwood transverse thermal conductivity. Part I

Science.gov (United States)

Hong-mei Gu; Audrey Zink-Sharp

2005-01-01

Thermal conductivity is a very important parameter in determining heat transfer rate and is required for developing of drying models and in industrial operations such as adhesive cure rate. Geometric models for predicting softwood thermal conductivity in the radial and tangential directions were generated in this study based on obervation and measurements of wood...

Complex conductivity response to silver nanoparticles in partially saturated sand columns

Science.gov (United States)

Abdel Aal, Gamal; Atekwana, Estella A.; Werkema, D. Dale

2017-02-01

The increase in the use of nanoscale materials in consumer products has resulted in a growing concern of their potential hazard to ecosystems and public health from their accidental or intentional introduction to the environment. Key environmental, health, and safety research needs include knowledge and methods for their detection, characterization, fate, and transport. Specifically, techniques available for the direct detection and quantification of their fate and transport in the environment are limited. Their small size, high surface area to volume ratio, interfacial, and electrical properties make metallic nanoparticles, such as silver nanoparticles, good targets for detection using electrical geophysical techniques. Here we measured the complex conductivity response to silver nanoparticles in sand columns under varying moisture conditions (0-30%), nanoparticle concentrations (0-10 mg/g), lithology (presence of clay), pore water salinity (0.0275 and 0.1000 S/m), and particle size (35, 90-210 and 1500-2500 nm). Based on the Cole-Cole relaxation models we obtained the chargeability and the time constant. We demonstrate that complex conductivity can detect silver nanoparticles in porous media with the response enhanced by higher concentrations of silver nanoparticles, moisture content, ionic strength, clay content and particle diameter. Quantification of the volumetric silver nanoparticles content in the porous media can also be obtained from complex conductivity parameters based on the strong power law relationships.

Validity of the isotropic thermal conductivity assumption in supercell lattice dynamics

Science.gov (United States)

Ma, Ruiyuan; Lukes, Jennifer R.

2018-02-01

Superlattices and nano phononic crystals have attracted significant attention due to their low thermal conductivities and their potential application as thermoelectric materials. A widely used expression to calculate thermal conductivity, presented by Klemens and expressed in terms of the relaxation time by Callaway and Holland, originates from the Boltzmann transport equation. In its most general form, this expression involves a direct summation of the heat current contributions from individual phonons of all wavevectors and polarizations in the first Brillouin zone. In common practice, the expression is simplified by making an isotropic assumption that converts the summation over wavevector to an integral over wavevector magnitude. The isotropic expression has been applied to superlattices and phononic crystals, but its validity for different supercell sizes has not been studied. In this work, the isotropic and direct summation methods are used to calculate the thermal conductivities of bulk Si, and Si/Ge quantum dot superlattices. The results show that the differences between the two methods increase substantially with the supercell size. These differences arise because the vibrational modes neglected in the isotropic assumption provide an increasingly important contribution to the thermal conductivity for larger supercells. To avoid the significant errors that can result from the isotropic assumption, direct summation is recommended for thermal conductivity calculations in superstructures.

Soft Power and Higher Education: An Examination of China's Confucius Institutes

Science.gov (United States)

Yang, Rui

2010-01-01

China's global presence has become a significant subject. However, little attention has been directed to the role of higher education in projecting China's soft power, and little academic work has been done directly on it, despite the fact that there has been some work on related topics. Borrowing the theories of soft power and higher education…

Quantitative Mapping of Large Area Graphene Conductance

DEFF Research Database (Denmark)

Buron, Jonas Christian Due; Petersen, Dirch Hjorth; Bøggild, Peter

2012-01-01

We present quantitative mapping of large area graphene conductance by terahertz time-domain spectroscopy and micro four point probe. We observe a clear correlation between the techniques and identify the observed systematic differences to be directly related to imperfections of the graphene sheet...

Highly anisotropic conductivity of tablets pressed from polyaniline-montmorillonite nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Tokarský, Jonáš, E-mail: jonas.tokarsky@vsb.cz [Nanotechnology centre, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava—Poruba (Czech Republic); IT4Innovations Centre of Excellence, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava—Poruba (Czech Republic); Kulhánková, Lenka [Faculty of Metallurgy and Materials Engineering, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava—Poruba (Czech Republic); Neuwirthová, Lucie; Mamulová Kutláková, Kateřina [Nanotechnology centre, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava—Poruba (Czech Republic); Vallová, Silvie [Faculty of Metallurgy and Materials Engineering, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava—Poruba (Czech Republic); Stýskala, Vítězslav [Faculty of Electrical Engineering and Computer Science, VŠB-TU Ostrava, 17. listopadu 15/2172, 708 33 Ostrava—Poruba (Czech Republic); Čapková, Pavla [Faculty of Science, University of J.E. Purkyně, České mládeže 8, 400 96 Ústí nad Labem (Czech Republic)

2016-03-15

Highlights: • Montmorillonite (MMT) can be intercalated with polyaniline (PANI) chains. • Tablets pressed from PANI/MMT exhibit high anisotropy in electrical conductivity. • Pressure 28MPa is sufficient to reach the anisotropy. • Tablets pressed from pure PANI also exhibit anisotropy in electrical conductivity. - Abstract: Polyaniline-montmorillonite nanocomposite was prepared from anilinium sulfate (precursor) and ammonium peroxodisulfate (oxidizing agent) using simple one-step method. The resulting nanocomposite obtained in powder form has been pressed into tablets using various compression pressures (28–400 MPa). Electrical conductivities of tablets in two perpendicular directions, i.e. direction parallel with the main surface of tablet (σ=) and in orthogonal direction (σ⊥), and corresponding anisotropy factors (i.e., the ratio σ=/σ⊥) have been studied in dependence on compression pressure used during the preparation. Polyaniline-montmorillonite nanocomposite was characterized using X-ray diffraction analysis, raman spectroscopy, transmission electron microscopy, thermogravimetric analysis and molecular modeling which led to the understanding of the internal structure. Measurement of hardness performed on pressed tablets has been also involved. Taking into account the highest value of anisotropy factor reached (σ=/σ⊥ = 490), present study shows a chance to design conductors with nearly two-dimensional conductivity.

Highly anisotropic conductivity of tablets pressed from polyaniline-montmorillonite nanocomposite

International Nuclear Information System (INIS)

Tokarský, Jonáš; Kulhánková, Lenka; Neuwirthová, Lucie; Mamulová Kutláková, Kateřina; Vallová, Silvie; Stýskala, Vítězslav; Čapková, Pavla

2016-01-01

Highlights: • Montmorillonite (MMT) can be intercalated with polyaniline (PANI) chains. • Tablets pressed from PANI/MMT exhibit high anisotropy in electrical conductivity. • Pressure 28MPa is sufficient to reach the anisotropy. • Tablets pressed from pure PANI also exhibit anisotropy in electrical conductivity. - Abstract: Polyaniline-montmorillonite nanocomposite was prepared from anilinium sulfate (precursor) and ammonium peroxodisulfate (oxidizing agent) using simple one-step method. The resulting nanocomposite obtained in powder form has been pressed into tablets using various compression pressures (28–400 MPa). Electrical conductivities of tablets in two perpendicular directions, i.e. direction parallel with the main surface of tablet (σ=) and in orthogonal direction (σ⊥), and corresponding anisotropy factors (i.e., the ratio σ=/σ⊥) have been studied in dependence on compression pressure used during the preparation. Polyaniline-montmorillonite nanocomposite was characterized using X-ray diffraction analysis, raman spectroscopy, transmission electron microscopy, thermogravimetric analysis and molecular modeling which led to the understanding of the internal structure. Measurement of hardness performed on pressed tablets has been also involved. Taking into account the highest value of anisotropy factor reached (σ=/σ⊥ = 490), present study shows a chance to design conductors with nearly two-dimensional conductivity.

Does foreign direct investment cause higher levels of productivity or do higher levels of productivity attract foreign direct investment? A study in transforming brazilian industry

Directory of Open Access Journals (Sweden)

Nádia Campos Pereira

2013-04-01

Full Text Available DOI: http://dx.doi.org/10.5007/2175-8077.2013v15n35p82   With this research, it was aimed to investigate the factors that determine the investment decision of foreign investors in the Brazilian industry. Evidence shows that foreign investors are attracted not only by more productive and best performing sectors, but depending on the adopted strategy, they may choose investment projects in sectors that have lower performance levels which offer the potential for growth and the and improvement of efficiency levels and capacity. Granger causality test indicated that not only foreign investment gives more productivity gains, but also this productivity induces more foreign investment inputs. Foreign investors are also attracted by those sectors, which use their assets in an inefficient way in order to generate profits. These sectors may be attractive to foreign investors that want to invest in a more aggressive growth policy in order to get advantages on the availability of inefficiently used assets. These sectors may be also attractive targets to investors who seek to compete directly in relatively less competitive sectors.

Thermal Conductivity of the Potential Repository Horizon Model Report

International Nuclear Information System (INIS)

Ramsey, J.

2002-01-01

The purpose of this report is to assess the spatial variability and uncertainty of thermal conductivity in the host horizon for the proposed repository at Yucca Mountain. More specifically, the lithostratigraphic units studied are located within the Topopah Spring Tuff (Tpt) and consist of the upper lithophysal zone (Tptpul), the middle nonlithophysal zone (Tptpmn), the lower lithophysal zone (Tptpll), and the lower nonlithophysal zone (Tptpln). The Tptpul is the layer directly above the repository host layers, which consist of the Tptpmn, Tptpll, and the Tptpln. Current design plans indicate that the largest portion of the repository will be excavated in the Tptpll (Board et al. 2002 [157756]). The main distinguishing characteristic among the lithophysal and nonlithophysal units is the percentage of large scale (cm-m) voids within the rock. The Tptpul and Tptpll, as their names suggest, have a higher percentage of lithophysae than the Tptpmn and the Tptpln. Understanding the influence of the lithophysae is of great importance to understanding bulk thermal conductivity and perhaps repository system performance as well. To assess the spatial variability and uncertainty of thermal conductivity, a model is proposed that is functionally dependent on the volume fraction of lithophysae and the thermal conductivity of the matrix portion of the rock. In this model, void space characterized as lithophysae is assumed to be air-saturated under all conditions, while void space characterized as matrix may be either water- or air-saturated. Lithophysae are assumed to be air-saturated under all conditions since the units being studied are all located above the water table in the region of interest, and the relatively strong capillary forces of the matrix will, under most conditions, preferentially retain any moisture present in the rock

Deterioration in effective thermal conductivity of aqueous magnetic nanofluids

NARCIS (Netherlands)

Altan, C.L.; Gurten, B.; Sommerdijk, N.A.J.M.; Bucak, S.

2014-01-01

Common heat transfer fluids have low thermal conductivities, which decrease their efficiency in many applications. On the other hand, solids have much higher thermal conductivity values. Previously, it was shown that the addition of different nanoparticles to various base fluids increases the

Thermal conductivity of highly porous mullite material

International Nuclear Information System (INIS)

Barea, Rafael; Osendi, Maria Isabel; Ferreira, Jose M.F.; Miranzo, Pilar

2005-01-01

The thermal diffusivity of highly porous mullite materials (35-60 vol.% porosity) has been measured up to 1000 deg C by the laser flash method. These materials were fabricated by a direct consolidation method based on the swelling properties of starch granules in concentrated aqueous suspensions and showed mainly spherical shaped pores of about 30 μm in diameter. From the point of view of heat conduction, they behave as a bi-phase material of voids dispersed in the continuous mullite matrix. The temperature dependence of thermal conductivity for the different porosities was modeled by a simple equation that considers the contribution to heat conduction of the mullite matrix and the gas inside the pores, as well as the radiation. The thermal conductivity of the matrix was taken from the measurements done in a dense mullite while the conductivity in the voids was assumed to be that of the testing atmosphere

Smart Surface Chemistries of Conducting Polymers

DEFF Research Database (Denmark)

Lind, Johan Ulrik

In this thesis we investigate post-polymerization covalent modifications of poly(3,4-dioxythiophene (PEDOT)-type conducting polymers. The aim of the modifications is to gain specific control of the interaction between the material and living mammalian cells. The use of “click-chemistry” to modify...... a straightforward and in-expensive method for patterning conducting polymer thin films into microelectrodes, without losing control of the surface chemistry of the samples. On the contrary, the method provides direct control of the surface chemistry of both the fabricated micro-electrodes and the gaps between them....... The method is based on locally removing PEDOTtype polymers to expose underlying non-conducting functional polymer substrates. Thereby, multifunctional substrates are obtained. By applying this method, we are able to fabricate allpolymer micro-systems with multiple types of localized functional (bio...

The conductivity of neonatal piglet skulls

International Nuclear Information System (INIS)

Pant, Shilpa; Te, Tang; Tucker, Aaron; Sadleir, Rosalind J

2011-01-01

We report the first measured values of conductivities for neonatal mammalian skull samples. We measured the average radial (normal to the skull surface) conductivity of fresh neonatal piglet skull samples at 1 kHz and found it to be around 30 mS m −1 at ambient room temperatures of about 23 °C. Measurements were made on samples of either frontal or parietal cranial bone, using a saline-filled cell technique. The conductivity value we observed was approximately twice the values reported for adult skulls (Oostendorp et al 2000 IEEE Trans. Biomed. Eng. 47 1487–92) using a similar technique, but at a frequency of around 5 Hz. Further, we found that the conductivity of skull fragments increased linearly with thickness. We found evidence that this was related to differences in composition between the frontal and parietal bone samples tested, which we believe is because frontal bones contained a larger fraction of higher conductivity cancellous bone material

Effect of directional solidification rate on the microstructure and properties of deformation-processed Cu–7Cr–0.1Ag in situ composites

Energy Technology Data Exchange (ETDEWEB)

Liu, Keming [Jiangxi Key Laboratory for Advanced Copper and Tungsten Materials, Jiangxi Academy of Sciences, Nanchang 330029 (China); School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Jiang, Zhengyi; Zhao, Jingwei [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Zou, Jin; Chen, Zhibao [Jiangxi Key Laboratory for Advanced Copper and Tungsten Materials, Jiangxi Academy of Sciences, Nanchang 330029 (China); Lu, Deping, E-mail: llludp@163.com [Jiangxi Key Laboratory for Advanced Copper and Tungsten Materials, Jiangxi Academy of Sciences, Nanchang 330029 (China)

2014-11-05

Highlights: • Effect of directional solidification (DS) rate on a Cu–Cr–Ag in situ composite. • The microstructure and properties of the DS in situ composite were investigated. • The second-phase Cr grains were parallel to drawing direction, and were finer. • The tensile strength was higher and the combination of properties was better. - Abstract: The influence of directional solidification rate on the microstructure, mechanical properties and conductivity of deformation-processed Cu–7Cr–0.1Ag in situ composites produced by thermo-mechanical processing was systematically investigated. The microstructure was analyzed by optical microscopy and scanning electronic microscopy. The mechanical properties and conductivity were evaluated by tensile-testing machine and micro-ohmmeter, respectively. The results indicate that the size, shape and distribution of second-phase Cr grains are significantly different in the Cu–7Cr–0.1Ag alloys with different growth rates. At a growth rate of 200 μm s{sup −1}, the Cr grains transform into fine Cr fiber-like grains parallel to the pulling direction from the Cr dendrites. The tensile strength of the Cu–7Cr–0.1Ag in situ composites from the directional solidification (DS) alloys is significantly higher than that from the as-cast alloy, while the conductivity of the in situ composites from the DS alloys is slightly lower than that from the as-cast alloy. The following combinations of tensile strength, elongation to fracture and conductivity of the Cu–7Cr–0.1Ag in situ composites from the DS alloy with a growth rate of 200 μm s{sup −1} and a cumulative cold deformation strain of 8 after isochronic aging treatment for 1 h can be obtained respectively as: (i) 1067 MPa, 2.9% and 74.9% IACS; or (ii) 1018 MPa, 3.0%, and 76.0% IACS or (iii) 906 MPa, 3.3% and 77.6% IACS.

Conductivity of oriented bis-azo polymer films

DEFF Research Database (Denmark)

Apitz, D.; Bertram, R.P.; Benter, N.

2006-01-01

The conductivity properties of electro-optic photoaddressable, dense bis-ozo chromophore polymer films are investigated by using samples corona poled at various temperatures. A dielectric spectrometer is applied to measure the frequency dependence of the conductivity at different temperatures...... before and after heating the material to above the glass transition temperature. The results show that the orientation of the chromophores changes the charge-carrier mobility. Ionic conductivity dominates in a more disordered configuration of the material, while the competing process of hole hopping...... takes over as a transition to a liquid-crystalline phase occurs when the material is heated to much higher than the gloss transition temperature. Such micro-crystallization strongly enhances the conductivity....

Towards Practical Application of Paper based Printed Circuits: Capillarity Effectively Enhances Conductivity of the Thermoplastic Electrically Conductive Adhesives

Science.gov (United States)

Wu, Haoyi; Chiang, Sum Wai; Lin, Wei; Yang, Cheng; Li, Zhuo; Liu, Jingping; Cui, Xiaoya; Kang, Feiyu; Wong, Ching Ping

2014-09-01

Direct printing nanoparticle-based conductive inks onto paper substrates has encountered difficulties e.g. the nanoparticles are prone to penetrate into the pores of the paper and become partially segmented, and the necessary low-temperature-sintering process is harmful to the dimension-stability of paper. Here we prototyped the paper-based circuit substrate in combination with printed thermoplastic electrically conductive adhesives (ECA), which takes the advantage of the capillarity of paper and thus both the conductivity and mechanical robustness of the printed circuitsweredrastically improved without sintering process. For instance, the electrical resistivity of the ECA specimen on a pulp paper (6 × 10-5Ω.cm, with 50 wt% loading of Ag) was only 14% of that on PET film than that on PET film. This improvement has been found directly related to the sizing degree of paper, in agreement with the effective medium approximation simulation results in this work. The thermoplastic nature also enables excellent mechanical strength of the printed ECA to resist repeated folding. Considering the generality of the process and the wide acceptance of ECA technique in the modern electronic packages, this method may find vast applications in e.g. circuit boards, capacitive touch pads, and radio frequency identification antennas, which have been prototyped in the manuscript.

Characterization and Conduction Mechanism of Highly Conductive Vanadate Glass

Directory of Open Access Journals (Sweden)

Tetsuaki Nishida

2015-12-01

Full Text Available This paper reviews recent studies of highly conductive barium iron vanadate glass with a composition of 20 BaO ∙ 10 Fe2O3 ∙ 70 V2O5 (in mol %. Isothermal annealing of the vanadate glass for several ten minutes at a given temperature, higher than glass transition temperature or crystallization temperature, caused an increase in σ. Substitution of CuI (3d10, ZnII (3d10 and CuII (3d9 for FeIII (3d5 was investigated to elucidate the effect of electron configuration on the conductivity (σ. A marked decrease in the activation energy of conduction (Ea was also observed after the annealing. Values of Ea were correlated to the energy gap between the donor level and the conduction band (CB in the n-type semiconductor model. Isothermal annealing of ZnII-substituted vanadate glass (20 BaO ∙ 5 ZnO ∙ 5 Fe2O3 ∙ 70 V2O5 at 450 °C for 30 min showed an increase in σ from 2.5 × 10–6 to 2.1 × 10–1 S cm–1, which was one order of magnitude larger than that of non-substituted vanadate glass (3.4 × 10–2 S cm–1. Under the same annealing condition, σ’s of 2.0 × 10–1 and 3.2 × 10–1 S cm–1 were observed for 20 BaO ∙ 5 Cu2O ∙ 5 Fe2O3 ∙ 70 V2O5 and 20 BaO ∙ 5 CuO ∙ 5 Fe2O3 ∙ 70 V2O5 glasses, respectively. These results demonstrate an increase in the carrier (electron density in the CB, primarily composed of anti-bonding 4s-orbitals.

Hydrothermal industrialization: direct heat development. Final report

Energy Technology Data Exchange (ETDEWEB)

1982-05-01

A description of hydrothermal resources suitable for direct applications, their associated temperatures, geographic distribution and developable capacity are given. An overview of the hydrothermal direct-heat development infrastructure is presented. Development activity is highlighted by examining known and planned geothermal direct-use applications. Underlying assumptions and results for three studies conducted to determine direct-use market penetration of geothermal energy are discussed.

Dielectric fluid directional spreading under the action of corona discharge

Science.gov (United States)

Zhou, Shangru; Liu, Jie; Hu, Qun; Jiang, Teng; Yang, Jinchu; Liu, Sheng; Zheng, Huai

2018-01-01

Liquid spreading is a very common nature phenomenon and of significant importance for a broad range of applications. In this study, a dielectric fluid directional spreading phenomenon is presented. Under the action of corona discharge, a dielectric fluid, here a typical silicone directionally spreads along conductive patterns on conductive/nonconductive substrates. Directional spreading behaviors of silicone were experimentally observed on different conductive patterns in detail. Spreading speeds were analyzed at different driving voltages, which induced the corona discharge. The presented phenomenon may be useful to inspire several techniques of manipulating liquid transportation and fabricating micropatterns.

Electric Conductivity of Phosphorus Nanowires

International Nuclear Information System (INIS)

Jing-Xiang, Zhang; Hui, Li; Xue-Qing, Zhang; Kim-Meow, Liew

2009-01-01

We present the structures and electrical transport properties of nanowires made from different strands of phosphorus chains encapsulated in carbon nanotubes. Optimized by density function theory, our results indicate that the conductance spectra reveal an oscillation dependence on the size of wires. It can be seen from the density of states and current-voltage curves that the structure of nanowires affects their properties greatly. Among them, the DNA-like double-helical phosphorus nanowire exhibits the distinct characteristic of an approximately linear I – V relationship and has a higher conductance than others. The transport properties of phosphorus nanowires are highly correlated with their microstructures. (condensed matter: structure, mechanical and thermal properties)

Room temperature Compton profiles of conduction electrons in α-Ga ...

Indian Academy of Sciences (India)

Room temperature Compton profiles of momentum distribution of conduction electrons in -Ga metal are calculated in band model. For this purpose, the conduction electron wave functions are determined in a temperature-dependent non-local model potential. The profiles calculated along the crystallographic directions, ...

INTERNATIONALIZATION IN HIGHER EDUCATION

Directory of Open Access Journals (Sweden)

Catalina Crisan-Mitra

2016-03-01

Full Text Available Internationalization of higher education is one of the key trends of development. There are several approaches on how to achieve competitiveness and performance in higher education and international academic mobility; students’ exchange programs, partnerships are some of the aspects that can play a significant role in this process. This paper wants to point out the student’s perception regarding two main directions: one about the master students’ expectation regarding how an internationalized master should be organized and should function, and second the degree of satisfaction of the beneficiaries of internationalized master programs from Babe-Bolyai University. This article is based on an empirical qualitative research that was implemented to students of an internationalized master from the Faculty of Economics and Business Administration. This research can be considered a useful example for those preoccupied to increase the quality of higher education and conclusions drawn have relevance both theoretically and especially practically.

Analysis of Lithuanian Direct Investment into European Union Countries

Directory of Open Access Journals (Sweden)

Evelina Zigmantavičiūtė

2015-05-01

Full Text Available In this paper the valuation of macroeconomic factors influencing the Lithuanian direct investment into European Union was conducted. The problem of this paper is the different chosen macroeconomic factors influencing foreign direct investment. The object of this paper is Lithuanian direct investment. The methods of this paper include: comparative literature analysis, correlation regression analysis, paired regression analysis. After conducting a research of dependency of Lithuanian direct investment to EU countries from price changes, government sector income, gross domestic product, inflation, jobless rate results, it is found that gross domestic product and government sector income have the most influence on the changes of Lithuanian direct investment.

Uncertainties Involved in the Iopospheric Conductivity Estimation

Directory of Open Access Journals (Sweden)

Young-Sil Kwak

2002-12-01

Full Text Available Various uncertainties involved in ionospheric conductivity estimation utilizing the electron density profile obtained from the Sondrestrom incoherent scatter radar are examined. First, we compare the conductivity which is based on raw electron density and the one based on corrected electron density that takes into account the effects of the difference between the electron and ion temperatures and the Debye length. The corrected electron density yields higher Pedersen and Hall conductivities than the raw electron density does. Second, the dependence of collision frequency model on the conductivity estimation is examined. Below 110 km conductivity does not depend significantly on collision frequency models. Above 110 km, however, the collision models affect the conductivity estimation. Third, the influence of the electron and ion temperatures on the conductivity estimation is examined. Electron and ion temperatures carrying an error of about 10% do not seem to affect significantly the conductivity estimation. Fourth, also examined is the effect of the choice of the altitude range of integration in calculating the height-integrated conductivity, conductance. It has been demonstrated that the lower and upper boundaries of the integration are quite sensitive to the estimation of the Hall and Pedersen conductances, respectively.

A Nafion-Ceria Composite Membrane Electrolyte for Reduced Methanol Crossover in Direct Methanol Fuel Cells

Directory of Open Access Journals (Sweden)

Parthiban Velayutham

2017-02-01

Full Text Available An alternative Nafion composite membrane was prepared by incorporating various loadings of CeO2 nanoparticles into the Nafion matrix and evaluated its potential application in direct methanol fuel cells (DMFCs. The effects of CeO2 in the Nafion matrix were systematically studied in terms of surface morphology, thermal and mechanical stability, proton conductivity and methanol permeability. The composite membrane with optimum filler content (1 wt. % CeO2 exhibits a proton conductivity of 176 mS·cm−1 at 70 °C, which is about 30% higher than that of the unmodified membrane. Moreover, all the composite membranes possess a much lower methanol crossover compared to pristine Nafion membrane. In a single cell DMFC test, MEA fabricated with the optimized composite membrane delivered a peak power density of 120 mW·cm−2 at 70 °C, which is about two times higher in comparison with the pristine Nafion membrane under identical operating conditions.

Studies of protonic self-diffusion and conductivity in 12-tungstophophoric acid hydrates by pulsed field gradient 1H NMR and ac Conductivity

International Nuclear Information System (INIS)

Slade, R.C.; Pressman, H.A.; Barker, J.; Strange, J.H.

1988-01-01

Temperature dependent protonic conductivities σ and 1/H self-diffusion coefficients, D, are reported for polycrystalline hydrates of 12-tungstophosphoric acid (TPA). Conductivities were measured using ac admittane spectrometry and diffusion coefficients by the pulsed field gradient NMR technique. Conductivities for the hydrates TPA.nH 2 O (n=6, 14, 21) increase with n. Examination of σ and D values and of activation techniques shows self-diffusion and conduction to occur by different mechanisms in the higher hydrates. 25 refs.; 14 figs.; 1 table

Photo-modulation of the spin Hall conductivity of mono-layer transition metal dichalcogenides

Energy Technology Data Exchange (ETDEWEB)

Sengupta, Parijat; Bellotti, Enrico [Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215 (United States)

2016-05-23

We report on a possible optical tuning of the spin Hall conductivity in mono-layer transition metal dichalcogenides. Light beams of frequencies much higher than the energy scale of the system (the off-resonant condition) do not excite electrons but rearrange the band structure. The rearrangement is quantitatively established using the Floquet formalism. For such a system of mono-layer transition metal dichalcogenides, the spin Hall conductivity (calculated with the Kubo expression in presence of disorder) exhibits a drop at higher frequencies and lower intensities. Finally, we compare the spin Hall conductivity of the higher spin-orbit coupled WSe{sub 2} to MoS{sub 2}; the spin Hall conductivity of WSe{sub 2} was found to be larger.

Finding low-conductance sets with dense interactions (FLCD) for better protein complex prediction.

Science.gov (United States)

Wang, Yijie; Qian, Xiaoning

2017-03-14

Intuitively, proteins in the same protein complexes should highly interact with each other but rarely interact with the other proteins in protein-protein interaction (PPI) networks. Surprisingly, many existing computational algorithms do not directly detect protein complexes based on both of these topological properties. Most of them, depending on mathematical definitions of either "modularity" or "conductance", have their own limitations: Modularity has the inherent resolution problem ignoring small protein complexes; and conductance characterizes the separability of complexes but fails to capture the interaction density within complexes. In this paper, we propose a two-step algorithm FLCD (Finding Low-Conductance sets with Dense interactions) to predict overlapping protein complexes with the desired topological structure, which is densely connected inside and well separated from the rest of the networks. First, FLCD detects well-separated subnetworks based on approximating a potential low-conductance set through a personalized PageRank vector from a protein and then solving a mixed integer programming (MIP) problem to find the minimum-conductance set within the identified low-conductance set. At the second step, the densely connected parts in those subnetworks are discovered as the protein complexes by solving another MIP problem that aims to find the dense subnetwork in the minimum-conductance set. Experiments on four large-scale yeast PPI networks from different public databases demonstrate that the complexes predicted by FLCD have better correspondence with the yeast protein complex gold standards than other three state-of-the-art algorithms (ClusterONE, LinkComm, and SR-MCL). Additionally, results of FLCD show higher biological relevance with respect to Gene Ontology (GO) terms by GO enrichment analysis.

A wind-tunnel investigation of parameters affecting helicopter directional control at low speeds in ground effect

Science.gov (United States)

Yeager, W. T., Jr.; Young, W. H., Jr.; Mantay, W. R.

1974-01-01

An investigation was conducted in the Langley full-scale tunnel to measure the performance of several helicopter tail-rotor/fin configurations with regard to directional control problems encountered at low speeds in ground effect. Tests were conducted at wind azimuths of 0 deg to 360 deg in increments of 30 deg and 60 deg and at wind speeds from 0 to 35 knots. The results indicate that at certain combinations of wind speed and wind azimuth, large increases in adverse fin force require correspondingly large increases in the tail-rotor thrust, collective pitch, and power required to maintain yaw trim. Changing the tail-rotor direction of rotation to top blade aft for either a pusher tail rotor (tail-rotor wake blowing away from fin) or a tractor tail rotor (tail-rotor wake blowing against fin) will alleviate this problem. For a pusher tail rotor at 180 deg wind azimuth, increases in the fin/tail-rotor gap were not found to have any significant influence on the overall vehicle directional control capability. Changing the tail rotor to a higher position was found to improve tail-rotor performance for a fin-off configuration at a wind azimuth of 180 deg. A V-tail configuration with a pusher tail rotor with top blade aft direction of rotation was found to be the best configuration with regard to overall directional control capability.

Co-Creation in Higher Education

DEFF Research Database (Denmark)

The main purpose of this book is to disseminate new research on co-creative approaches to teaching and learning in Higher Education (HE). The cases presented draw from a Danish cultural and educational context and have a special focus on collaborative, co-creative and distributed perspectives......-led learning, arts-based approaches to higher educational research and teaching, collaborative practices. We believe that these perspectives are still in need of further investigation through theories and practices. We understand co-creation as the process of creative, original and valuable generation...... of shared meaning and development. This collected volume offers novel empirical documentation and original theoretical reflections on the application of co-creative processes in higher education. This can be directly relevant for educators and the ways in which they design education, but also for students...

A novel approach to determine the in-plane thermal conductivity of gas diffusion layers in proton exchange membrane fuel cells

Science.gov (United States)

Sadeghi, E.; Djilali, N.; Bahrami, M.

Heat transfer through the gas diffusion layer (GDL) is a key process in the design and operation of a proton exchange membrane (PEM) fuel cell. The analysis of this process requires determination of the effective thermal conductivity. This transport property differs significantly in the through-plane and in-plane directions due to the anisotropic micro-structure of the GDL. A novel test bed that allows separation of in-plane effective thermal conductivity and thermal contact resistance in GDLs is described in this paper. Measurements are performed using Toray carbon paper TGP-H-120 samples with varying polytetrafluoroethylene (PTFE) content at a mean temperature of 65-70 °C. The measurements are complemented by a compact analytical model that achieves good agreement with experimental data. The in-plane effective thermal conductivity is found to remain approximately constant, k ≈ 17.5 W m -1 K -1, over a wide range of PTFE content, and its value is about 12 times higher than that for through-plane conductivity.

Six Conductivity Values to Use in the Bidomain Model of Cardiac Tissue.

Science.gov (United States)

Johnston, Barbara M

2016-07-01

The aim of this work is to produce a consistent set of six conductivity values for use in the bidomain model of cardiac tissue. Studies in 2007 by Hooks et al. and in 2009 by Caldwell et al. have found that, in the directions longitudinal:transverse:normal (l:t:n) to the cardiac fibers, ratios of bulk conductivities and conduction velocities are each approximately in the ratio 4:2:1. These results are used here as the basis for a method that can find sets of six normalized bidomain conductivity values. It is found that the ratios involving transverse and normal conductivities are quite consistent, allowing new light to be shed on conductivity in the normal direction. For example, it is found that the ratio of transverse to normal conductivity is much greater in the intracellular (i) than the extracellular (e) domain. Using parameter values from experimental studies leads to the proposal of a new nominal six conductivity dataset: gil=2.4, gel=2.4, git=0.35, get=2.0, gin=0.08, and gen=1.1 (all in mS/cm). When it is used to model partial thickness ischaemia, this dataset produces epicardial potential distributions in accord with experimental studies in an animal model. It is, therefore, suggested that the dataset is suitable for use in numerical simulations. Since the bidomain approach is the most commonly used method for modeling cardiac electrophysiological phenomena, new information about conductivity in the normal direction, as well as a consistent set of six conductivity values, is valuable for researchers who perform simulation studies.

Physical meaning of conductivity spectra for ZnO ceramics

Institute of Scientific and Technical Information of China (English)

Cheng Peng-Fei; Li Sheng-Tao; Li Jian-Ying; Ding Can; Yang Yan

2012-01-01

With the help of broadband dielectric spectroscopy in a wide temperature and frequency range,the conductivity spectra of ZnO polycrystalline ceramics are measured and the direct-current-like (DC-like) conductivity and relaxation polarization conductivity are observed successively along the frequency axis.According to the classical Debye theory and Cole-Cole equation,the physical meanings of the two conductivities are discussed.It is found that the DC-like conductivity corresponds to electron transportation over the Schottky barrier at the grainboundary.The relaxation polarization conductivity corresponds to electronic trap relaxation of intrinsic point defects (zinc interstitial and oxygen vacancy).When in the high frequency region,the relaxation conductivity obeys the universal law with the index n equal to the index α in the Cole-Cole equation as an indictor of disorder degree.

Whole plantar nerve conduction study with disposable strip electrodes.

Science.gov (United States)

Hemmi, Shoji; Kurokawa, Katsumi; Nagai, Taiji; Okamoto, Toshio; Murakami, Tatsufumi; Sunada, Yoshihide

2016-02-01

A new method to evaluate whole plantar nerve conduction with disposable strip electrodes (DSEs) is described. Whole plantar compound nerve action potentials (CNAPs) were recorded at the ankle. DSEs were attached to the sole for simultaneous stimulation of medial and lateral plantar nerves. We also conducted medial plantar nerve conduction studies using an established method and compared the findings. Whole plantar CNAPs were recorded bilaterally from 32 healthy volunteers. Mean baseline to peak amplitude for CNAPs was 26.9 ± 11.8 μV, and mean maximum conduction velocity was 65.8 ± 8.3 m/s. The mean amplitude of CNAPs obtained by our method was 58.2% higher than that of CNAPs obtained by the Saeed method (26.9 μV vs. 17.0 μV; P < 0.0001). The higher mean amplitude of whole plantar CNAPs obtained by our method suggests that it enables CNAPs to be obtained easily, even in elderly people. © 2015 Wiley Periodicals, Inc.

Methodological issues involved in conducting qualitative research ...

African Journals Online (AJOL)

The purpose of this article is to describe the methodological issues involved in conducting qualitative research to explore and describe nurses' experience of being directly involved with termination of pregnancies and developing guidelines for support for these nurses. The article points out the sensitivity and responsibility ...

Problematic internet users' skin conductance and anxiety increase after exposure to the internet.

Science.gov (United States)

Romano, Michela; Roaro, Alessandra; Re, Federica; Osborne, Lisa A; Truzoli, Roberto; Reed, Phil

2017-12-01

To examine the impact of cessation of an internet session on skin conductance responses and anxiety of higher and lower problem internet users, in order to explore possible physiological withdrawal effects. Participants were measured in terms of their skin conductance before (15min), during (15min), and after (15min) an internet session, and completed self-report measures of state anxiety and problematic internet use. Higher, but not lower, problem users showed increased skin conductance after internet use was stopped, relative to before their internet session. Higher problem users' GSR scores increased, as the time from internet cessation became longer. Higher problem users also showed increased levels of anxiety, following their internet session, which correlated with their skin conductance scores. These results suggest that, following termination of an internet session, withdrawal-like effects are seen, both psychologically and physiologically. Copyright © 2017 Elsevier Ltd. All rights reserved.

Noninvasive electrical conductivity measurement by MRI: a test of its validity and the electrical conductivity characteristics of glioma.

Science.gov (United States)

Tha, Khin Khin; Katscher, Ulrich; Yamaguchi, Shigeru; Stehning, Christian; Terasaka, Shunsuke; Fujima, Noriyuki; Kudo, Kohsuke; Kazumata, Ken; Yamamoto, Toru; Van Cauteren, Marc; Shirato, Hiroki

2018-01-01

This study noninvasively examined the electrical conductivity (σ) characteristics of diffuse gliomas using MRI and tested its validity. MRI including a 3D steady-state free precession (3D SSFP) sequence was performed on 30 glioma patients. The σ maps were reconstructed from the phase images of the 3D SSFP sequence. The σ histogram metrics were extracted and compared among the contrast-enhanced (CET) and noncontrast-enhanced tumour components (NCET) and normal brain parenchyma (NP). Difference in tumour σ histogram metrics among tumour grades and correlation of σ metrics with tumour grades were tested. Validity of σ measurement using this technique was tested by correlating the mean tumour σ values measured using MRI with those measured ex vivo using a dielectric probe. Several σ histogram metrics of CET and NCET of diffuse gliomas were significantly higher than NP (Bonferroni-corrected p ≤ .045). The maximum σ of NCET showed a moderate positive correlation with tumour grade (r = .571, Bonferroni-corrected p = .018). The mean tumour σ measured using MRI showed a moderate positive correlation with the σ measured ex vivo (r = .518, p = .040). Tissue σ can be evaluated using MRI, incorporation of which may better characterise diffuse gliomas. • This study tested the validity of noninvasive electrical conductivity measurements by MRI. • This study also evaluated the electrical conductivity characteristics of diffuse glioma. • Gliomas have higher electrical conductivity values than the normal brain parenchyma. • Noninvasive electrical conductivity measurement can be helpful for better characterisation of glioma.

Electrical conduction along dislocations in plastically deformed GaN

Energy Technology Data Exchange (ETDEWEB)

Kamimura, Y; Yokoyama, T; Oiwa, H; Edagawa, K [Institute of Industrial Science, the University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Yonenaga, I, E-mail: yasushi@iis.u-tokyo.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577 (Japan)

2009-07-15

Electrical conduction along dislocations in plastically deformed n-GaN single crystals has been investigated by scanning spread resistance microscopy (SSRM). In the SSRM images, many conductive spots have been observed, which correspond to electrical conduction along the dislocations introduced by deformation. Here, the introduced dislocations are b=(a/3)<1overline 210> edge dislocations parallel to the [0001] direction. The current values at the spots normalized to the background current value are larger than 100. Previous works have shown that grown-in edge dislocations in GaN are nonconductive. The high conductivity of the deformation-introduced edge dislocations in the present work suggests that the conductivity depends sensitively on the dislocation core structure.

Valid Competency Assessment in Higher Education

Directory of Open Access Journals (Sweden)

Olga Zlatkin-Troitschanskaia

2017-01-01

Full Text Available The aim of the 15 collaborative projects conducted during the new funding phase of the German research program Modeling and Measuring Competencies in Higher Education—Validation and Methodological Innovations (KoKoHs is to make a significant contribution to advancing the field of modeling and valid measurement of competencies acquired in higher education. The KoKoHs research teams assess generic competencies and domain-specific competencies in teacher education, social and economic sciences, and medicine based on findings from and using competency models and assessment instruments developed during the first KoKoHs funding phase. Further, they enhance, validate, and test measurement approaches for use in higher education in Germany. Results and findings are transferred at various levels to national and international research, higher education practice, and education policy.

Predicting photosynthesis and transpiration responses to ozone: decoupling modeled photosynthesis and stomatal conductance

Directory of Open Access Journals (Sweden)

D. Lombardozzi

2012-08-01

Full Text Available Plants exchange greenhouse gases carbon dioxide and water with the atmosphere through the processes of photosynthesis and transpiration, making them essential in climate regulation. Carbon dioxide and water exchange are typically coupled through the control of stomatal conductance, and the parameterization in many models often predict conductance based on photosynthesis values. Some environmental conditions, like exposure to high ozone (O₃ concentrations, alter photosynthesis independent of stomatal conductance, so models that couple these processes cannot accurately predict both. The goals of this study were to test direct and indirect photosynthesis and stomatal conductance modifications based on O₃ damage to tulip poplar (Liriodendron tulipifera in a coupled Farquhar/Ball-Berry model. The same modifications were then tested in the Community Land Model (CLM to determine the impacts on gross primary productivity (GPP and transpiration at a constant O₃ concentration of 100 parts per billion (ppb. Modifying the V_cmax parameter and directly modifying stomatal conductance best predicts photosynthesis and stomatal conductance responses to chronic O₃ over a range of environmental conditions. On a global scale, directly modifying conductance reduces the effect of O₃ on both transpiration and GPP compared to indirectly modifying conductance, particularly in the tropics. The results of this study suggest that independently modifying stomatal conductance can improve the ability of models to predict hydrologic cycling, and therefore improve future climate predictions.

Development of unidirectional C/C composite with high thermal conductivity and its application to plasma facing materials

International Nuclear Information System (INIS)

Ioki, Kimihiro; Onozuka, Masanori; Ikeda, Takeshi; Akiba, Masato.

1994-01-01

Unidirectional C/C composite named 'MFC-1' with high conductivity was developed, and full-scale armor tiles were fabricated. The thermal conductivity in the direction perpendicular to the plasma-side surface is more than 300-500 W/m·degC, which is higher than those of other C/C composites ever made, even superior to that of pyrolytic carbon. It was shown by high heat load tests done using an electron beam test facility that the unidirectional C/C composite was very resistant against both surface erosion as well as severe thermal shock. The 'MFC-1' was successfully brazed to copper substrate, and its high thermal shock resistance was observed in heat load tests (20 MW/m 2 , 3s, not cooled). A functionally gradient material has been also developed as compliant layer for the MFC-1 bonded to copper. (author)

Research Productivity and Its Policy Implications in Higher Education Institutions

Science.gov (United States)

Quimbo, Maria Ana T.; Sulabo, Evangeline C.

2014-01-01

Responding to the Commission on Higher Education's development plan of enhancing research culture among higher education institutions, this study was conducted to analyze the research productivity of selected higher education institutions. It covered five state universities in the Philippines where a total of 377 randomly selected faculty members…

A new proton conducting membrane based on copolymer of methyl methacrylate and 2-acrylamido-2-methyl-1-propanesulfonic acid for direct methanol fuel cells

International Nuclear Information System (INIS)

Shen, Yi; Xi, Jingyu; Qiu, Xinping; Zhu, Wentao

2007-01-01

In this paper, a new kind of copolymer methyl methacrylate and 2-acrylamido-2-methyl-1-propanesulfonic acid (PAMPS-co-MMA) was synthesized by free radical polymerization. IR-spectrum and 1 H NMR were used to confirm the structure of the copolymers, and the thermal character of the copolymers was investigated with TGA and DSC. Flexible and transparent membranes based on this kind of copolymer were prepared by solution casting method. The physical properties including ionic exchange capability (IEC), water uptake, proton conductivity, methanol permeability and morphology of the membranes were investigated. These membranes showed higher water uptake though they had lower IEC compared with Nafion-117. The proton conductivity of the membrane with IEC of 0.9 mmol/g was 1.14 x 10 -2 S/cm and its methanol permeability coefficient was 5.46 x 10 -7 cm 2 /s, much lower than that of Nafion-117. Tests on cells were also carried out to measure the performance of the membrane

Direct electroplating of plastic for advanced electrical applications

DEFF Research Database (Denmark)

Islam, Aminul; Hansen, Hans Nørgaard; Tang, Peter Torben

2017-01-01

Electrodeposition or electroplating is predominantly applied to metallic components. Electroplating of plastics is possible in some cases where an initial electroless plating layer of nickel or copper is made to provide a conductive surface on the plastic part. This paper proposes a method...... for direct electroplating of plastic eliminating the need for slow and expensive processes like electroless metal deposition, PVD coating, painting with conductive inks etc. The results obtained from the test demonstrate the potential of direct electroplating of plastic to enhance the electrical conductivity...... and the use of electroplated plastics for advanced applications like Moulded Interconnect Devices (MIDs)....

Novel Rear Side Metallization Route for Si Solar Cells Using a Transparent Conducting Adhesive: Preprint

Energy Technology Data Exchange (ETDEWEB)

Schnabel, Manuel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Klein, Talysa [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lee, Benjamin G [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nemeth, William M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); LaSalvia, Vincenzo A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Van Hest, Marinus F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Stradins, Paul [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2018-03-14

The rear side metallization of Si solar cells comes with a number of inherent losses and trade-offs: a larger metallized area fraction improves fill factor at the expense of open-circuit voltage, depositing directly on textured Si leads to low contact resistivity at the expense of short-circuit current, and some metallization processes create defects in Si. To mitigate many of these losses we have developed a novel approach for rear side metallization of Si solar cells, utilizing a transparent conducting adhesive (TCA) to metallize Si without exposing the wafer to the metal deposition process. The TCA consists of an insulating adhesive loaded with conductive microspheres. This approach leads to virtually no loss in implied open-circuit voltage upon metallization. Electrical measurements showed that contact resistivities of 3-9 ..omega.. cm2 were achieved, and an analysis of the transit resistance per microsphere showed that less than 1 ..omega.. cm2 should be achievable with higher microsphere loading of the TCA.

Cost and Price Increases in Higher Education: Evidence of a Cost Disease on Higher Education Costs and Tuition Prices and the Implications for Higher Education Policy

Science.gov (United States)

Trombella, Jerry

2011-01-01

As concern over rapidly rising college costs and tuition sticker prices have increased, a variety of research has been conducted to determine potential causes. Most of this research has focused on factors unique to higher education. In contrast, cost disease theory attempts to create a comparative context to explain cost increases in higher…

Thermal Conductivity of Epoxy Resin Composites Filled with Combustion Synthesized h-BN Particles

Directory of Open Access Journals (Sweden)

Shyan-Lung Chung

2016-05-01

Full Text Available The thermal conductivity of epoxy resin composites filled with combustion-synthesized hexagonal boron nitride (h-BN particles was investigated. The mixing of the composite constituents was carried out by either a dry method (involving no use of solvent for low filler loadings or a solvent method (using acetone as solvent for higher filler loadings. It was found that surface treatment of the h-BN particles using the silane 3-glycidoxypropyltrimethoxysilane (GPTMS increases the thermal conductivity of the resultant composites in a lesser amount compared to the values reported by other studies. This was explained by the fact that the combustion synthesized h-BN particles contain less –OH or active sites on the surface, thus adsorbing less amounts of GPTMS. However, the thermal conductivity of the composites filled with the combustion synthesized h-BN was found to be comparable to that with commercially available h-BN reported in other studies. The thermal conductivity of the composites was found to be higher when larger h-BN particles were used. The thermal conductivity was also found to increase with increasing filler content to a maximum and then begin to decrease with further increases in this content. In addition to the effect of higher porosity at higher filler contents, more horizontally oriented h-BN particles formed at higher filler loadings (perhaps due to pressing during formation of the composites were suggested to be a factor causing this decrease of the thermal conductivity. The measured thermal conductivities were compared to theoretical predictions based on the Nielsen and Lewis theory. The theoretical predictions were found to be lower than the experimental values at low filler contents (< 60 vol % and became increasing higher than the experimental values at high filler contents (> 60 vol %.

Sintered stabilized zirconia microstructure and conductivity

International Nuclear Information System (INIS)

Bernard, Herve.

1981-04-01

The elaboration of a stabilized zirconia powder which sinters at 1300 0 C and the influence of the sintered polycristal microstructure on its ionic conductivity have been studied. Among three investigated powder preparation processes, coprecipitation in an ammoniacal solution was chosen. After sintering at 1300 0 C, the pellet density was higher than 93% of the theoretical density. It even approached up to 98% TD with addition of less than 0,5 mole % Al 2 O 3 to the initial powder. The overall electrolyte conductivity and the inter and intragranular contributions have been determined by complex impedance spectroscopy. ZrO 2 -Y 2 O 3 solid solution conductivity was scarcely improved by Y 2 O 3 exchange with Yb 2 O 3 or Gd 2 O 3 . This conductivity greatly increases with grain size, its improvement with decreasing porosity, which has been quantified, is less sensible. Moreover, two original properties were noticed: small amounts of Al 2 O 3 and quenching greatly enhanced the overall conductivity. At temperatures below 500 0 C, grain boundaries only insured a partial migration of conductive ions. A parallel type electrical equivalent circuit suited well with this blocking effect [fr

DC bias effect on alternating current electrical conductivity of poly(ethylene terephthalate)/alumina nanocomposites

Science.gov (United States)

Nikam, Pravin N.; Deshpande, Vineeta D.

2016-05-01

Polymer nanocomposites based on metal oxide (ceramic) nanoparticles are a new class of materials with unique properties and designed for various applications such as electronic device packaging, insulation, fabrication and automotive industries. Poly(ethylene terephthalate) (PET)/alumina (Al2O3) nanocomposites with filler content between 1 wt% and 5 wt% were prepared by melt compounding method using co-rotating twin screw extruder and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and precision LCR meter techniques. The results revealed that proper uniform dispersion at lower content up to 2 wt% of nano-alumina observed by using TEM. Aggregation of nanoparticles was observed at higher content of alumina examined by using SEM and TEM. The frequency dependences of the alternating current (AC) conductivity (σAC) of PET/alumina nanocomposites on the filler content and DC bias were investigated in the frequency range of 20Hz - 1MHz. The results showed that the AC and direct current (DC) conductivity increases with increasing DC bias and nano-alumina content upto 3 wt%. It follows the Jonscher's universal power law of solids. It revealed that σAC of PET/alumina nanocomposites can be well characterized by the DC conductivity (σDC), critical frequency (ωc), critical exponent of the power law (s). Roll of DC bias potential led to an increase of DC conductivity (σDC) due to the creation of additional conducting paths with the polymer nanocomposites and percolation behavior achieved through co-continuous morphology.

Conductance in double quantum well systems

International Nuclear Information System (INIS)

Hasbun, J E

2003-01-01

The object of this paper is to review the electronic conductance in double quantum well systems. These are quantum well structures in which electrons are confined in the z direction by large band gap material barrier layers, yet form a free two-dimensional Fermi gas within the sandwiched low band gap material layers in the x-y plane. Aspects related to the conductance in addition to the research progress made since the inception of such systems are included. While the review focuses on the tunnelling conductance properties of double quantum well devices, the longitudinal conductance is also discussed. Double quantum well systems are a more recent generation of structures whose precursors are the well known double-barrier resonant tunnelling systems. Thus, they have electronic signatures such as negative differential resistance, in addition to resonant tunnelling, whose behaviours depend on the wavefunction coupling between the quantum wells. As such, the barrier which separates the quantum wells can be tailored in order to provide better control of the device's electronic properties over their single well ancestors. (topical review)

Layered thermal metamaterials for the directing and harvesting of conductive heat

Directory of Open Access Journals (Sweden)

P. R. Bandaru

2015-05-01

Full Text Available The utility of a metamaterial, assembled from two layers of nominally isotropic materials, for thermal energy re-orientation and harvesting is examined. A study of the underlying phenomena related to heat flux manipulation, exploiting the anisotropy of the thermal conductivity tensor, is a focus. The notion of the assembled metamaterial as an effective thermal medium forms the basis for many of these investigations and will be probed. An overarching aim is to implement in such thermal metamaterials, functionalities well known from light optics, such as reflection and refraction, which in turn may yield insights on efficient thermal lensing. Consequently, the harness and dissipation of heat, which are for example, of much importance in energy conservation and improving electrical device performance, may be accomplished. The possibilities of energy harvesting, through exploiting anisotropic thermopower in the metamaterials is also examined. The review concludes with a brief survey of the outstanding issues and insights needed for further progress.

A Review of the Chinese Higher Education Evaluation Center

Science.gov (United States)

Luo, Laura Pan; Dehai, Wang

2007-01-01

The authors discuss the Higher Education Evaluation Center, the administrative body under the auspices of the Chinese Ministry of Education responsible for organizing and conducting evaluation of baccalaureate and associate degree programs offered at different universities and colleges in China. The Center also conducts research on regulations and…

Discovering Interdisciplinary Uses of Online Technologies in Higher Education

Directory of Open Access Journals (Sweden)

Mary Caton-Rosser

2014-06-01

Full Text Available Recent research shows both students and professors rushing to adapt learning and teaching activities accessing ever-upgrading digital and social media formats like Facebook, Twitter, YouTube, Pinterest and Prezi. Many institutions of higher education are embracing social media as viable, student-centered-classroom communication tools in a full range of subject disciplines, as well as in emerging interdisciplinary activities that prepare students for current trends in the job force. The new communication channels offer students a direct voice in discussion of topics of subject matter and current events, avenues for expedited exchange of information, and also introduction to skills needed to operate mobile computing devices, such as tablets and portable hand-held devices. The advancing tools of online technology are also being used creatively in general communication across college campuses in higher education following standardized-use policies. The use of social media, for example, is effective in recruiting and interacting with prospective students and their parents or in expedited sharing of news or updated policies and procedures. The current endorsement of new technologies in various higher-education settings aligns with historical enthusiasm in education for interactive classroom dialogue. Over the years, progressive and pragmatic educators, such as John Dewey, Paulo Freire, Elliot Eisner and Larry Cuban have promoted interactive, inclusive pedagogical communication and experiential education since the early 1900s to the present. For the past year-and-a-half, three faculty members at Black Hills State University have been conducting qualitative and quantitative research on the use of digital and social media in higher education. Since the beginning, the central goal has been to create awareness of digital technologies and social media as inter-subjective tools. More recently, the focus has become measurement of the learning experience and

Political struggles in disability’s visibilization: direct actions, counter-conducts and resistance

Directory of Open Access Journals (Sweden)

Alejandro Martín Contino

2013-12-01

Full Text Available Since the examination of the current situation of persons under disability, the hypothesis of conceiving disability as a device is carried out, according to the French philosopher Michel Foucault. Thus, the negative aspects experienced by subjects in situation of disability, not implying malfunction of public policy, would be logical and expected effects, the typical function of a disability device that works according to the guidelines of the Medical-Individual model. This article intends to present the tactics of counter-conduct as ways of subjectivation that resist current governmentality, becoming the visibilization of such actions, a key aspect of any strategy of political transformation.

12 CFR 612.2140 - Directors-prohibited conduct.

Science.gov (United States)

2010-01-01

... 612.2140 Banks and Banking FARM CREDIT ADMINISTRATION FARM CREDIT SYSTEM STANDARDS OF CONDUCT AND... participated in the deliberations or decision to foreclose or to dispose of the property or in establishing the terms of the sale. (g) Directly or indirectly borrow from, lend to, or become financially obligated with...

Effective Self-Regulatory Processes in Higher Education: Research Findings and Future Directions. A Systematic Review

Science.gov (United States)

de Bruijn-Smolders, Monique; Timmers, Caroline F.; Gawke, Jason C. L.; Schoonman, Wouter; Born, Marise Ph.

2016-01-01

Although self-regulated learning (SRL) is assumed to benefit learning outcomes, gaps in the literature make it difficult to describe what constitutes effective SRL in higher education. That is, SRL that relates positively to learning outcomes. In accordance, at present it is unclear how to train effective SRL in higher education. The current…

Anomalous Stretchable Conductivity Using an Engineered Tricot Weave.

Science.gov (United States)

Lee, Yong-Hee; Kim, Yoonseob; Lee, Tae-Ik; Lee, Inhwa; Shin, Jaeho; Lee, Hyun Soo; Kim, Taek-Soo; Choi, Jang Wook

2015-12-22

Robust electric conduction under stretching motions is a key element in upcoming wearable electronic devices but is fundamentally very difficult to achieve because percolation pathways in conductive media are subject to collapse upon stretching. Here, we report that this fundamental challenge can be overcome by using a parameter uniquely available in textiles, namely a weaving structure. A textile structure alternately interwoven with inelastic and elastic yarns, achieved via a tricot weave, possesses excellent elasticity (strain up to 200%) in diagonal directions. When this textile is coated with conductive nanomaterials, proper textile engineering allows the textile to obtain an unprecedented 7-fold conductivity increase, with conductivity reaching 33,000 S cm(-1), even at 130% strain, due to enhanced interyarn contacts. The observed stretching conductivity can be described well using a modified 3D percolation theory that reflects the weaving effect and is also utilized for stretchable electronic interconnects and supercapacitors with high performance.

Higher order Lie-Baecklund symmetries of evolution equations

International Nuclear Information System (INIS)

Roy Chowdhury, A.; Roy Chowdhury, K.; Paul, S.

1983-10-01

We have considered in detail the analysis of higher order Lie-Baecklund symmetries for some representative nonlinear evolution equations. Until now all such symmetry analyses have been restricted only to the first order of the infinitesimal parameter. But the existence of Baecklund transformation (which can be shown to be an overall sum of higher order Lie-Baecklund symmetries) makes it necessary to search for such higher order Lie-Baecklund symmetries directly without taking recourse to the Baecklund transformation or inverse scattering technique. (author)

Ion heat conduction losses in Extrap

International Nuclear Information System (INIS)

Tennfors, E.

1989-08-01

The classical ion heat conduction losses in Extrap discharges are calculated using polynomial magnetic field profiles and compared to the power input. For polynomials matched to magnetic field profiles measured in present experiments, these losses are small. By varying the coefficients of the polynomials, a region is found, where the power input can balance the classical heat conduction losses. Each set of coefficients corresponds to values of the parameters F and Θ used in RFP physics. The region determines a region in an F-Θ diagram, including the usual RFP region but extending to higher values of Θ and βΘ

Conductance Peaks in Open Quantum Dots

International Nuclear Information System (INIS)

Ramos, J. G. G. S.; Bazeia, D.; Hussein, M. S.; Lewenkopf, C. H.

2011-01-01

We present a simple measure of the conductance fluctuations in open ballistic chaotic quantum dots, extending the number of maxima method originally proposed for the statistical analysis of compound nuclear reactions. The average number of extreme points (maxima and minima) in the dimensionless conductance T as a function of an arbitrary external parameter Z is directly related to the autocorrelation function of T(Z). The parameter Z can be associated with an applied gate voltage causing shape deformation in quantum dot, an external magnetic field, the Fermi energy, etc. The average density of maxima is found to be Z >=α Z /Z c , where α Z is a universal constant and Z c is the conductance autocorrelation length, which is system specific. The analysis of Z > does not require large statistic samples, providing a quite amenable way to access information about parametric correlations, such as Z c .

Investment Management in Higher Education Institutions

Directory of Open Access Journals (Sweden)

Jelena Stankevičienė

2015-05-01

Full Text Available Recently, the higher education sector faces a series of changes, such as increased competition, globalization, limited funding. Limited funding does not reveal the full potential of the higher education, too little funding restricts research performance, diminishes the quality of higher education, worsen the conditions for learning and this has important implications for sustainable value creation. The article explores relationship between education, sustainability and financial indicators in order to evaluate the situation and advancement in the European countries, applied multi-criteria evaluation method MULTIMOORA. This method aims to prove that the more encourage investment in higher education and research, the more sustainable the state is and creates sustainable value. The results revealed that the more financially stronger and stable country is, the better position by assessing both the scientific and the sustainability indicators. Financially stable country can give higher investment in education, to promote the conduct of research, create conditions for the formation of high-quality R&D, to prepare highly qualified specialists.

Heat treatment of a direct composite resin: influence on flexural strength

Directory of Open Access Journals (Sweden)

Caroline Lumi Miyazaki

2009-09-01

Full Text Available The purpose of this study was to evaluate the flexural strength of a direct composite, for indirect application, that received heat treatment, with or without investment. One indirect composite was used for comparison. For determination of the heat treatment temperature, thermogravimetric analysis (TGA and differential scanning calorimetry (DSC were performed, considering the initial weight loss temperature and glass transition temperature (Tg. Then, after photoactivation (600 mW/cm² - 40 s, the specimens (10 x 2 x 2 mm were heat-treated following these conditions: 170ºC for 5, 10 or 15 min, embedded or not embedded in investment. Flexural strength was assessed as a means to evaluate the influence of different heat treatment periods and investment embedding on mechanical properties. The data were analyzed by ANOVA and Tukey's test (α = 0.05. TGA showed an initial weight loss temperature of 180ºC and DSC showed a Tg value of 157°C. Heat treatment was conducted in an oven (Flli Manfredi, Italy, after 37°C storage for 48 h. Flexural strength was evaluated after 120 h at 37°C storage. The results showed that different periods and investment embedding presented similar statistical values. Nevertheless, the direct composite resin with treatments presented higher values (178.7 MPa compared to the indirect composite resin (146.0 MPa and the same direct composite submitted to photoactivation only (151.7 MPa. Within the limitations of this study, it could be concluded that the heat treatment increased the flexural strength of the direct composite studied, leading to higher mechanical strength compared to the indirect composite.

Correlation between structure and conductivity in stretched Nafion

Science.gov (United States)

Allahyarov, Elshad; Taylor, Philip

2008-03-01

We have used coarse-grained simulation methods to investigate the effect of stretching-induced structure orientation on the proton conductivity of Nafion-like polyelectrolyte membranes. Recent experimental data on the morphology of ionomers describe Nafion as an aggregation of polymeric backbone chains forming elongated objects embedded in a continuous ionic medium. Uniaxial stretching of a recast Nafion film causes a preferential orientation of these objects in the direction of stretching. Our simulations of humid Nafion show that this has a strong effect on the proton conductivity, which is enhanced along the stretching direction, while the conductivity perpendicular to the stretched polymer backbone is strongly reduced. Stretching also causes the perfluorinated side chains to orient perpendicular to the stretching axis. The sulphonate multiplets shrink in diameter as the stretching is increased and show a spatially periodic ordering in their distribution. This in turn affects the distribution of contained water at low water contents. The water forms a continuous network with narrow bridges between small water clusters absorbed in head-group multiplets. We find the morphological changes in the stretched Nafion to be retained upon removal of the uniaxial stress.

Electrolytic conductivity-the hopping mechanism of the proton and beyond

International Nuclear Information System (INIS)

Gileadi, E.; Kirowa-Eisner, E.

2006-01-01

The hopping mechanism of electrolytic conductivity is analyzed, employing mixtures of two solvents: one that sustains the hopping mechanism and the other that does not inhibit it directly, but interferes with it by diluting the solvent that sustains hopping. Measurement of the equivalent conductivity shows that the excess proton conductivities of H 3 O + and OH - increases with increasing temperature, although the number of hydrogen bonds is known to decrease. In mixtures of acetonitrile with water, proton hopping does not start until a threshold concentration of about 20 vol.% water has been reached, while no such threshold concentration is observed upon addition of methanol to acetonitrile. It is concluded that in the former the proton is transferred to a cluster of water molecules, which can be formed only if there is enough water in the solvent mixture. This observation leads to the concept of mono-water, which is the state of water molecules when they constitute a small minority in the solvent mixtures, as opposed to bulk water, which consists of clusters of variable sizes. Systems in which a hopping mechanism of heavy ions has been observed include Br - /Br 2 and I - /I 2 . In these cases the triple ions Br 3 - and I 3 - , respectively are formed, and serve as the mediators for the transfer of the simple halogen ion. A very large increase of conductivity was observed upon solidification of the Br - /Br 3 - system, probably caused by favorable linear alignment of ions in the solid. The conductivity of acidified methanol decreases upon addition of water, because the affinity of the proton to water is higher than to methanol, thus water can act as a scavenger for protons. This behavior exemplifies a general observation, namely that conductivity by hopping can only occur when the Gibbs energy of the system does not change significantly following ion transfer; otherwise the ions would be trapped in the more stable state, hindering further propagation by hopping

Examining Multimedia Competencies for Educational Technologists in Higher Education

Science.gov (United States)

Iqdami, Muhammad Nazil; Branch, Robert Maribe

2016-01-01

The authors investigated educational technology multimedia competencies for professionals who work in higher education institutions. Similar studies have been proposed, but none of them have focused on competencies required in the context of higher education. An online survey adapting sixteen competency factors from a study conducted by Rizhaupt…

A New Typology for Analyzing the Direction of Movement in Higher Education Internationalization

Science.gov (United States)

Wu, Hantian; Zha, Qiang

2018-01-01

This article proposes a new typology of "inward- and outward-oriented" higher education (HE) internationalization based on the spread of innovations that involve knowledge, culture, HE models, and norms. It reviews existing typologies related to HE internationalization; discusses theories of world system, soft power, and knowledge…

Thermal Conductivity of Epoxy Resin Composites Filled with Combustion Synthesized h-BN Particles.

Science.gov (United States)

Chung, Shyan-Lung; Lin, Jeng-Shung

2016-05-20

The thermal conductivity of epoxy resin composites filled with combustion-synthesized hexagonal boron nitride (h-BN) particles was investigated. The mixing of the composite constituents was carried out by either a dry method (involving no use of solvent) for low filler loadings or a solvent method (using acetone as solvent) for higher filler loadings. It was found that surface treatment of the h-BN particles using the silane 3-glycidoxypropyltrimethoxysilane (GPTMS) increases the thermal conductivity of the resultant composites in a lesser amount compared to the values reported by other studies. This was explained by the fact that the combustion synthesized h-BN particles contain less -OH or active sites on the surface, thus adsorbing less amounts of GPTMS. However, the thermal conductivity of the composites filled with the combustion synthesized h-BN was found to be comparable to that with commercially available h-BN reported in other studies. The thermal conductivity of the composites was found to be higher when larger h-BN particles were used. The thermal conductivity was also found to increase with increasing filler content to a maximum and then begin to decrease with further increases in this content. In addition to the effect of higher porosity at higher filler contents, more horizontally oriented h-BN particles formed at higher filler loadings (perhaps due to pressing during formation of the composites) were suggested to be a factor causing this decrease of the thermal conductivity. The measured thermal conductivities were compared to theoretical predictions based on the Nielsen and Lewis theory. The theoretical predictions were found to be lower than the experimental values at low filler contents ( 60 vol %).

Studies on electrical conductivity of poly phenylene vinylene

International Nuclear Information System (INIS)

Khattab, Asaad F.; Ahmad, Saddam M.

2009-01-01

Four Pp polymers have been synthesized through Wit ting reaction, 1 poly(p-phenylene vinylene), 2 = poly(p phenylene vinylene-co-m-phenylene vinylene), 3 = poly(p-phenylene vinylene-co-o-phenylene vinylene) and 4 poly(p-phenylene-1,5-hexadiene). Electrical conductivity measurements show that the conductivity of polymer 3 is higher than that of polymers 1 and 2. The dihedral angle measurements indicates that the irregularity of polymer chains is the main reason for this fact. The interruption of chain conjugation by aliphatic segments (polymer 4) will increase the conductivity by increasing the chain mobility.The electrical conductivity of the polymers is increased by doping with iodine and by raising the temperature. The effect of annealing with different temperatures on conductivity was studied; the results show that structural conformation of polymeric chain is the main factor affecting electrical conductivity. (author)

New membrane structures with proton conducting properties

DEFF Research Database (Denmark)

Nørgaard, Casper Frydendal

if higher operating temperature is enabled. One approach to obtain improved membranes in the aspects of applicable operating temperature and methanol permeability, which has attracted considerable attention, is the formation of composites by distributing inorganic fillers into Nafion or alternative polymers...... temperature and high relative humidity can cause excessive swelling of the membranes, yielding insufficient mechanical properties and breakdown of membrane function. Moreover, in the case of the Direct Methanol Fuel Cell (DMFC), their significant methanol permeability causes loss of efficiency. Higher...

Crystal structure and ionic conduction path of solid electrolytic materials by high temperature neutron diffraction method

International Nuclear Information System (INIS)

Yashima, Masatomo; Nomura, Katsuhiro

2005-01-01

Research of the distribution of oxide ions and the ionic conduction path of bismuth oxide (Bi 2 O 3 ), cerium oxide (CeO 2 ) and lanthanum gallate ((La 0.8 Sr 0.2 )(Ga 0.8 Mg 0.15 Co 0.05 )O 3-δ ) is stated. The high temperature neutron diffraction method, analytical method such as Rietveld method, crystal structure analysis of ionic conductor and MEM (Maximum- Entropy Method) are explained. The nuclear density distribution of oxide ions in bismuth oxide showed so larger distribution in the direction of and than Bi ions that the oxide ions conducted these direction in the crystal. The nuclear density distribution of oxide ions of cerium oxide indicated larger distribution in the direction of than Ce ions and its tendency was remarkable at high temperature. Accordingly, the oxide ions conducted in the direction of and . The oxide ions distribution in lanthanum gallate compound was larger and complicated than positive ions. The oxide ions conducted to by describing an arc between the two stable positions. The nuclear density on the conduction path increased with increasing temperature. This above result corresponded to increase of oxide ion conductivity in the area. (S.Y.)

Synthesis of Conductive Polymeric Nanocomposites for Applications in Responsive Materials

Science.gov (United States)

Chavez, Jessica

The development of next generation "smart" textiles has emerged with significant interest due to the immense demand for high-performance wearable technology. The economic market for wearable technologies is predicted to increase significantly in both volume and value. In the next four years, the wearable technology market will be valued at $34 billion. This large demand has opened up a new research area involving smart wearable devices and conductive fabrics. Many research groups have taken various paths to study and ultimately fabricate wearable devices. Due to the limiting capabilities of conventional conductors, researchers have centered their research on the integration of conductive polymers into textile materials for applications involving responsive material. Conducive polymers are very unique organic molecules that have the ability to transfer electrons across their molecular structure due to the excess presence of pi-electrons. Conductive polymers are favored over conventional conductors because they can be easily manipulated and integrated into flexible material. Two very common conductive polymers are polyaniline (PANI) and polypyrrole (PPY) because of their large favorability in literature, high conductance values, and environmental stability. Common commercial fibers were coated via the chemical polymerization of PANI or PPY. A series of reactions were done to study the polymerization process of each polymer. The conductive efficiency of each conducting polymer is highly dependent on the type of reactants used, the acidic nature of the reaction, and the temperature of the reaction. The coated commercial fiber nanocomposites produced higher conductivity values when the polymerization reaction was run using ammonium peroxydisulfate (APS) as the oxidizing agent, run in an acidic environment, and run at very low temperatures. Other factors that improved the overall efficiency of the coated commercial fiber nanocomposites was the increase in polymer

Developmental Pathways to Conduct Disorder: Implications for Future Directions in Research, Assessment, and Treatment

Science.gov (United States)

Frick, Paul J.

2012-01-01

Research has indicated that there are several common pathways through which children and adolescents develop conduct disorder, each with different risk factors and each with different underlying developmental mechanisms leading to the child's aggressive and antisocial behavior. The current article briefly summarizes research on these pathways,…

Inkjet printing of silver citrate conductive ink on PET substrate

International Nuclear Information System (INIS)

Nie Xiaolei; Wang Hong; Zou Jing

2012-01-01

Highlights: ► A direct synthesis method of silver conductive film on PET substrate was presented. ► A stable particle-free conductive ink was prepared. ► Formation of silver-amine complex reduced the thermal decomposition temperature. ► Conductive patterns for flexible electronics were fabricated by inkjet printing. ► Silver film on PET substrate possessed highest adhesion rating even without polymer. - Abstract: Direct synthesis of silver conductive film on PET substrate by inkjet printing silver citrate conductive ink was presented in this paper. This kind of conductive ink contained silver citrate as silver precursor, 1,2-diaminopropane as complex agent dissolving the silver salt and methanol and isopropanol as a media adjusting the viscosity and surface tension. The formation of silver-amine complex reduced the decomposition temperature from 180 °C to 135 °C, thus the ink could be cured at relatively low temperature. The film reached the lowest resistivity of 17 μΩ cm after cured at 150 °C for 50 min, 3.1 μΩ cm at 230 °C and possessed high reflection and excellent adhesive property. Electrical conductivity, surface morphology and composition were investigated by four-point probe method, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). It is demonstrated how the cured condition affects the silver film. Moreover, radio-frequency identification (RFID) antenna was fabricated by inkjet printing, which opens up routes for the flexible electronics fabrication.

Atomistic Modeling of Thermal Conductivity of Epoxy Nanotube Composites

Science.gov (United States)

Fasanella, Nicholas A.; Sundararaghavan, Veera

2016-05-01

The Green-Kubo method was used to investigate the thermal conductivity as a function of temperature for epoxy/single wall carbon nanotube (SWNT) nanocomposites. An epoxy network of DGEBA-DDS was built using the `dendrimer' growth approach, and conductivity was computed by taking into account long-range Coulombic forces via a k-space approach. Thermal conductivity was calculated in the direction perpendicular to, and along the SWNT axis for functionalized and pristine SWNT/epoxy nanocomposites. Inefficient phonon transport at the ends of nanotubes is an important factor in the thermal conductivity of the nanocomposites, and for this reason discontinuous nanotubes were modeled in addition to long nanotubes. The thermal conductivity of the long, pristine SWNT/epoxy system is equivalent to that of an isolated SWNT along its axis, but there was a 27% reduction perpendicular to the nanotube axis. The functionalized, long SWNT/epoxy system had a very large increase in thermal conductivity along the nanotube axis (~700%), as well as the directions perpendicular to the nanotube (64%). The discontinuous nanotubes displayed an increased thermal conductivity along the SWNT axis compared to neat epoxy (103-115% for the pristine SWNT/epoxy, and 91-103% for functionalized SWNT/epoxy system). The functionalized system also showed a 42% improvement perpendicular to the nanotube, while the pristine SWNT/epoxy system had no improvement over epoxy. The thermal conductivity tensor is averaged over all possible orientations to see the effects of randomly orientated nanotubes, and allow for experimental comparison. Excellent agreement is seen for the discontinuous, pristine SWNT/epoxy nanocomposite. These simulations demonstrate there exists a threshold of the SWNT length where the best improvement for a composite system with randomly oriented nanotubes would transition from pristine SWNTs to functionalized SWNTs.

Direct speech constructions in aphasic Dutch narratives

NARCIS (Netherlands)

Groenewold, Rimke; Bastiaanse, Roelien; Huiskes, Mike

2013-01-01

Background: Previous studies have shown that individuals with aphasia are usually able to produce direct reported speech constructions. So far these studies have mainly been conducted in English. The results show that direct speech is beneficial for aphasic speakers for various reasons. In Dutch the

Thermal conductivity and retention characteristics of composites made of boron carbide and carbon fibers with extremely high thermal conductivity for first wall armour

Science.gov (United States)

Jimbou, R.; Kodama, K.; Saidoh, M.; Suzuki, Y.; Nakagawa, M.; Morita, K.; Tsuchiya, B.

1997-02-01

The thermal conductivity of the composite hot-pressed at 2100°C including B 4C and carbon fibers with a thermal conductivity of 1100 W/ m· K was nearly the same as that of the composite including carbon fibers with a thermal conductivity of 600 W/ m· K. This resulted from the higher amount of B diffused into the carbon fibers through the larger interface. The B 4C content in the composite can be reduced from 35 to 20 vol% which resulted from the more uniform distribution of B 4C by stacking the flat cloth woven of carbon fibers (carbon fiber plain fabrics) than in the composite with 35 vol% B 4C including curled carbon fiber plain fabrics. The decrease in the B 4C content does not result in the degradation of D (deuterium)-retention characteristics or D-recycling property, but will bring about the decreased amount of the surface layer to be melted under the bombardment of high energy hydrogen ions such as disruptions because of higher thermal conduction of the composite.

Reinforced Conductive Polyaniline-Paper Composites

Directory of Open Access Journals (Sweden)

Jinhua Yan

2015-05-01

Full Text Available A method for direct aniline interfacial polymerization on polyamideamine-epichlorohydrin (PAE-reinforced paper substrate is introduced in this paper. Cellulose-based papers with and without reinforcement were considered. The polyaniline (PANI-paper composites had surface resistivity lower than 100 Ω/sq after more than 3 polymerizations. Their mechanical strength and thermal stability were analyzed by tensile tests and thermogravimetric analysis (TGA. Fourier transform infrared (FTIR results revealed that there was strong interaction between NH groups in aniline monomers and OH groups in fibers, which did not disappear until after 3 polymerizations. Scanning electron microscopy (SEM and field emission (FE SEM images showed morphological differences between composites using reinforced and untreated base papers. Conductive composites made with PAE-reinforced base paper had both good thermal stability and good mechanical strength, with high conductivity and a smaller PANI amount.

Collective Nostalgia Is Associated With Stronger Outgroup-Directed Anger and Participation in Ingroup-Favoring Collective Action

Directory of Open Access Journals (Sweden)

Wing-Yee Cheung

2017-08-01

Full Text Available Collective nostalgia refers to longing for the way society used to be. We tested whether collective nostalgia is associated with ingroup-favoring collective action and whether this association is mediated by outgroup-directed anger and outgroup-directed contempt. We conducted an online study of Hong Kong residents (N = 111 during a large-scale democratic social movement, the Umbrella Movement, that took place in Hong Kong in 2014 in response to proposed electoral reforms by the Chinese government in Mainland China. Reported collective nostalgia for Hong Kong’s past was high in our sample and collective nostalgia predicted stronger involvement in ingroup-favoring collective action, and it did so indirectly via higher intensity of outgroup-directed anger (but not through outgroup-directed contempt. We argue that collective nostalgia has implications for strengthening ingroup-serving collective action, and we highlight the importance of arousal of group-based emotions in this process.

The Conflict of Commodification of Traditional Higher Education Institutions

Science.gov (United States)

Plante, Jarrad

2016-01-01

Moving into the 21st century, the landscape of the traditional higher education institution has changed, including its model of conducting business. Students in the millennial generation see higher education as a commodity, where learning can be acquired through different delivery systems. It is imperative that organizational leaders, like those…

In Pursuit of Excellence? Discursive Patterns in European Higher Education Research

Science.gov (United States)

Ramirez, Francisco O.; Tiplic, Dijana

2014-01-01

European higher education is awash with educational reform initiatives that purport to transform universities into better-managed higher quality organizations that more directly contribute to national development. This exploratory study examines patterns of research discourse in higher education in Europe. We argue that these patterns are changing…

Building Bridges: Seeking Structure and Direction for Higher Education Motivated Learning Strategy Models

Science.gov (United States)

Fryer, Luke K.

2017-01-01

Many of our current higher education (HE) learning strategy models intersect at important points. At the same time, these theories also often demonstrate important unique perspectives on student learning within HE. Currently, research with one learning strategy model rarely leads to developments in others, as each group of researchers works in…

Identification of an Actual Strain-Induced Effect on Fast Ion Conduction in a Thin-Film Electrolyte.

Science.gov (United States)

Ahn, Junsung; Jang, Ho Won; Ji, Hoil; Kim, Hyoungchul; Yoon, Kyung Joong; Son, Ji-Won; Kim, Byung-Kook; Lee, Hae-Weon; Lee, Jong-Ho

2018-05-09

Strain-induced fast ion conduction has been a research area of interest for nanoscale energy conversion and storage systems. However, because of significant discrepancies in the interpretation of strain effects, there remains a lack of understanding of how fast ionic transport can be achieved by strain effects and how strain can be controlled in a nanoscale system. In this study, we investigated strain effects on the ionic conductivity of Gd 0.2 Ce 0.8 O 1.9-δ (100) thin films under well controlled experimental conditions, in which errors due to the external environment could not intervene during the conductivity measurement. In order to avoid any interference from perpendicular-to-surface defects, such as grain boundaries, the ionic conductivity was measured in the out-of-plane direction by electrochemical impedance spectroscopy analysis. With varying film thickness, we found that a thicker film has a lower activation energy of ionic conduction. In addition, careful strain analysis using both reciprocal space mapping and strain mapping in transmission electron microscopy shows that a thicker film has a higher tensile strain than a thinner film. Furthermore, the tensile strain of thicker film was mostly developed near a grain boundary, which indicates that intrinsic strain is dominant rather than epitaxial or thermal strain during thin-film deposition and growth via the Volmer-Weber (island) growth mode.

Perceived parental acceptance/rejection, some family characteristics and conduct disorder in adolescents.

Science.gov (United States)

Kostić, Jelena; Nešić, Milkica; Stanković, Miodrag; Zikić, Olivera

2014-10-01

Conduct disorder is characterized by repetitive and persistent presence of dissocial, aggressive and defiant behavioral patterns, thus represents important public issue with comprehensive and far-reaching consequences both for the individual and society. The aim of this study was to investigate the differences in sociodemographic family characteristics and the prominence of parental acceptance/rejection dimensions in groups of adolescents with and without conduct disorder, as well as to examine the connection between parental acceptance/rejection dimensions and externalizing symptoms in the group of adolescents with conduct disorder. This research was conducted on 134 adolescents, aged 15 to 18, using the Parental Acceptance/Rejection Questionnaire (PARQ child), Youth Self-Report (YSR), and a questionnaire constructed for the purpose of this survey. The results showed that the number of adolescents with conduct disorder coming from divorced families was significandy higher than from complete families (44.8% vs 13.4%, respectively; p disorders compared to the controls (31.3% vs 8.9%; respectively; p = 0.001). The perceived rejection dimension and the total index of maternal acceptance/rejection were significantly higher in adolescents with conduct disorder than in those with no such disorder (132.30 ± 38.05 vs 93.91 ± 26.29 respectively; p conduct disorder and severe perceived maternal and paternal rejection showed a significantly higher average score on the subscale of externalizing symptoms (14.55 ± 4.45 and 13.27 + 5.05) compared to adolescents with conduct disorder and lower total index of parental acceptance/rejection (8.32 ± 5.05 and 8.28 ± 5.08). The results suggest that adolescents with conduct disorder perceive their parents as more rejecting and less warm and supportive compared to adolescents without conduct disorder. The perception of significant and severe parental rejection was associated with a significantly higher averaged score on the subscale

Ionomers for Ion-Conducting Energy Materials

Science.gov (United States)

Colby, Ralph

For ionic actuators and battery separators, it is vital to utilize single-ion conducting ionomers that avoid the detrimental polarization of other ions. Single-ion conducting ionomers are synthesized based on DFT calculations, with low glass transition temperatures (facile dynamics) to prepare ion-conducting membranes for battery separators that conduct Li+ or Na+. Characterization by X-ray scattering, dielectric spectroscopy, FTIR, NMR and linear viscoelasticity collectively develop a coherent picture of ionic aggregation and both counterion and polymer dynamics. 7Li NMR diffusion measurements find that diffusion is faster than expected by conductivity using the Nernst-Einstein equation, which means that the majority of Li diffusion occurs by ion pairs moving with the polymer segmental motion. Segmental motion only contributes to ionic conduction in the rare event that one of these ion pairs has an extra Li (a positive triple ion). This leads us to a new metric for ion-conducting soft materials, the product of the cation number density p0 and their diffusion coefficient D; p0D is the diffusive flux of lithium ions. This new metric has a maximum at intermediate ion content that corresponds to the overlap of ion pair polarizability volumes. At higher ion contents, the ion pairs interact strongly and form larger aggregation states that retard segmental motion of both mobile ion pairs and triple ions.

Development of unidirectional C/C composite with high thermal conductivity and its application to plasma facing materials

Energy Technology Data Exchange (ETDEWEB)

Ioki, Kimihiro (Mitsubishi Atomic Power Industries, Inc., Tokyo (Japan)); Onozuka, Masanori; Ikeda, Takeshi; Akiba, Masato

1994-03-01

Unidirectional C/C composite named 'MFC-1' with high conductivity was developed, and full-scale armor tiles were fabricated. The thermal conductivity in the direction perpendicular to the plasma-side surface is more than 300-500 W/m[center dot]degC, which is higher than those of other C/C composites ever made, even superior to that of pyrolytic carbon. It was shown by high heat load tests done using an electron beam test facility that the unidirectional C/C composite was very resistant against both surface erosion as well as severe thermal shock. The 'MFC-1' was successfully brazed to copper substrate, and its high thermal shock resistance was observed in heat load tests (20 MW/m[sup 2], 3s, not cooled). A functionally gradient material has been also developed as compliant layer for the MFC-1 bonded to copper. (author).

Fabrication of Biosensors Based on Nanostructured Conducting Polyaniline (NSPANI

Directory of Open Access Journals (Sweden)

Deepshikha SAINI

2011-11-01

Full Text Available In this study, glucose and hydrogen peroxide (H2O2 biosensors based on nanostructured conducting polyaniline (NSPANI (synthesized using sodiumdodecyl sulphate (SDS as structure directing agent were developed. Because of the large specific surface area, excellent conductivity of NSPANI, horseradish peroxidase (HRP and glucose oxidase (GOx could be easily immobilized with high loading and activity. In addition the small dimensions and the high surface-to-volume ratio of the NSCP allow the rapid transmission of electron and enhance current response. The linear dynamic range of optical glucose and H2O2 biosensors is 5–40 mM for glucose and 1–50 mM for H2O2, respectively where as the bulk PANI exhibits linearity between 5-20 mM/l. The miniature optical glucose biosensor also exhibits good reproducibility. The storage stability of optical glucose and H2O2 biosensors is two weeks for glucose and five days for H2O2. The high response value of NSPANI based biosensors as compared to bulk PANI based biosensor reflects higher enzymatic affinity of GOx/NSPANI and HRP/NSPANI with glucose and H2O2 due to biocompatibility, active surface area and high electron communication capability of nanobiopolymer film. In conclusion, the NSPANI based biosensors proposed herein have many advantages such as a low response time, high reproducibility, high sensitivity, stable and wide dynamic range.

Radiation-grafted membranes based on polyethylene for direct methanol fuel cells

Energy Technology Data Exchange (ETDEWEB)

Sherazi, Tauqir A. [Department of Chemistry, Government College University, Lahore 54000 (Pakistan); Institute for Chemical Process and Environmental Technology, National Research Council Canada, 1200 Montreal Road, Ottawa, ON K1A 0R6 (Canada); Guiver, Michael D.; Kingston, David; Xue, Xinzhong [Institute for Chemical Process and Environmental Technology, National Research Council Canada, 1200 Montreal Road, Ottawa, ON K1A 0R6 (Canada); Ahmad, Shujaat [PIEAS/PINSTECH, P O Nilore, Islamabad 45650 (Pakistan); Kashmiri, M. Akram [Department of Chemistry, Government College University, Lahore 54000 (Pakistan); Board of Intermediate and Secondary Education, Lahore 54000 (Pakistan)

2010-01-01

Styrene was grafted onto ultrahigh molecular weight polyethylene powder (UHMWPE) by gamma irradiation using a {sup 60}Co source. Compression moulded films of selected pre-irradiated styrene-grafted ultrahigh molecular weight polyethylene (UHMWPE-g-PS) were post-sulfonated to the sulfonic acid derivative (UHMWPE-g-PSSA) for use as proton exchange membranes (PEMs). The sulfonation was confirmed by X-ray photoelectron spectroscopy (XPS). The melting and flow properties of UHMWPE and UHMWPE-g-PS are conducive to forming homogeneous pore-free membranes. Both the ion conductivity and methanol permeability coefficient increased with degree of grafting, but the grafted membranes showed comparable or higher ion conductivity and lower methanol permeability than Nafion {sup registered} 117 membrane. One UHMWPE-g-PS membrane was fabricated into a membrane-electrode assembly (MEA) and tested as a single cell direct methanol fuel cell (DMFC). Low membrane cost and acceptable fuel cell performance indicate that UHMWPE-g-PSSA membranes could offer an alternative approach to perfluorosulfonic acid-type membranes for DMFC. (author)

Ionic conductivity in oxide heterostructures: the role of interfaces

Directory of Open Access Journals (Sweden)

Emiliana Fabbri, Daniele Pergolesi and Enrico Traversa

2010-01-01

Full Text Available Rapidly growing attention is being directed to the investigation of ionic conductivity in oxide film heterostructures. The main reason for this interest arises from interfacial phenomena in these heterostructures and their applications. Recent results revealed that heterophase interfaces have faster ionic conduction pathways than the bulk or homophase interfaces. This finding can open attractive opportunities in the field of micro-ionic devices. The influence of the interfaces on the conduction properties of heterostructures is becoming increasingly important with the miniaturization of solid-state devices, which leads to an enhanced interface density at the expense of the bulk. This review aims to describe the main evidence of interfacial phenomena in ion-conducting film heterostructures, highlighting the fundamental and technological relevance and offering guidelines to understanding the interface conduction mechanisms in these structures.

Highly Conductive Nano-Silver Circuits by Inkjet Printing

Science.gov (United States)

Zhu, Dongbin; Wu, Minqiang

2018-06-01

Inkjet technology has become popular in the field of printed electronics due to its superior properties such as simple processes and printable complex patterns. Electrical conductivity of the circuits is one of the key factors in measuring the performance of printed electronics, which requires great material properties and a manufactured process. With excellent conductivity and ductility, silver is an ideal material as the wire connecting components. This review summarizes the progress of conductivity studies on inkjet printed nano-silver lines, including ink composition and nanoparticle morphology, deposition of nano-silver lines with uniform and high aspect ratios, sintering mechanisms and alternative methods of thermal sintering. Finally, the research direction on inkjet printed electronics is proposed.

Science and Higher Education in Korea.

Science.gov (United States)

Lee, Sungho

The role and contribution of academic science to national development in the Republic of Korea is discussed. After an overview on the development of the Korean system of higher education, attention is directed to the national research system and its articulation with the academic system. Consideration is given to: factors that contributed to the…

Direct FuelCell/Turbine Power Plant

Energy Technology Data Exchange (ETDEWEB)

Hossein Ghezel-Ayagh

2008-09-30

This report summarizes the progress made in development of Direct FuelCell/Turbine (DFC/T{reg_sign}) power plants for generation of clean power at very high efficiencies. The DFC/T system employs an indirectly heated Turbine Generator to supplement fuel cell generated power. The concept extends the high efficiency of the fuel cell by utilizing the fuel cell's byproduct heat in a Brayton cycle. Features of the DFC/T system include: electrical efficiencies of up to 75% on natural gas, minimal emissions, reduced carbon dioxide release to the environment, simplicity in design, direct reforming internal to the fuel cell, and potential cost competitiveness with existing combined cycle power plants. Proof-of-concept tests using a sub-MW-class DFC/T power plant at FuelCell Energy's (FCE) Danbury facility were conducted to validate the feasibility of the concept and to measure its potential for electric power production. A 400 kW-class power plant test facility was designed and retrofitted to conduct the tests. The initial series of tests involved integration of a full-size (250 kW) Direct FuelCell stack with a 30 kW Capstone microturbine. The operational aspects of the hybrid system in relation to the integration of the microturbine with the fuel cell, process flow and thermal balances, and control strategies for power cycling of the system, were investigated. A subsequent series of tests included operation of the sub-MW Direct FuelCell/Turbine power plant with a Capstone C60 microturbine. The C60 microturbine extended the range of operation of the hybrid power plant to higher current densities (higher power) than achieved in initial tests using the 30kW microturbine. The proof-of-concept test results confirmed the stability and controllability of operating a fullsize (250 kW) fuel cell stack in combination with a microturbine. Thermal management of the system was confirmed and power plant operation, using the microturbine as the only source of fresh air supply

Thermal conductivity predictions of herringbone graphite nanofibers using molecular dynamics simulations.

Science.gov (United States)

Khadem, Masoud H; Wemhoff, Aaron P

2013-02-28

Non-equilibrium molecular dynamics (NEMD) simulations are used to investigate the thermal conductivity of herringbone graphite nanofibers (GNFs) at room temperature by breaking down the axial and transverse conductivity values into intralayer and interlayer components. The optimized Tersoff potential is used to account for intralayer carbon-carbon interactions while the Lennard-Jones potential is used to model the interlayer carbon-carbon interactions. The intralayer thermal conductivity of the graphene layers near room temperature is calculated for different crease angles and number of layers using NEMD with a constant applied heat flux. The edge effect on a layer's thermal conductivity is investigated by computing the thermal conductivity values in both zigzag and armchair directions of the heat flow. The interlayer thermal conductivity is also predicted by imposing hot and cold Nosé-Hoover thermostats on two layers. The limiting case of a 90° crease angle is used to compare the results with those of single-layer graphene and few-layer graphene. The axial and transverse thermal conductivities are then calculated using standard trigonometric conversions of the calculated intralayer and interlayer thermal conductivities, along with calculations of few-layer graphene without a crease. The results show a large influence of the crease angle on the intralayer thermal conductivity, and the saturation of thermal conductivity occurs when number of layers is more than three. The axial thermal conductivity, transverse thermal conductivity in the crease direction, and transverse thermal conductivity normal to the crease for the case of a five-layer herringbone GNF with a 45° crease angle are calculated to be 27 W∕m K, 263 W∕m K, and 1500 W∕m K, respectively, where the axial thermal conductivity is in good agreement with experimental measurements.

An overview of high thermal conductive hot press forming die material development

Directory of Open Access Journals (Sweden)

A.R. Zulhishamuddin

2015-12-01

Full Text Available Most of the automotive industries are using high strength steel components, which are produced via hot press forming process. This process requires die material with high thermal conductivity that increases cooling rate during simultaneous quenching and forming stage. Due to the benefit of high quenching rate, thermal conductive die materials were produced by adding carbide former elements. This paper presents an overview of the modification of alloying elements in tool steel for high thermal conductivity properties by transition metal elements addition. Different types of manufacturing processes involved in producing high thermal conductive materials were discussed. Methods reported were powder metallurgy hot press, direct metal deposition, selective laser melting, direct metal laser sintering and spray forming. Elements likes manganese, nickel, molybdenum, tungsten and chromium were proven to increase thermal conductivity properties. Thermal conductivity properties resulted from carbide network presence in the steel microstructure. To develop feasible and low cost hot press forming die material, casting of Fe-based alloy with carbide former composition can be an option. Current thermal conductivity properties of hot press forming die material range between 25 and 66 W/m.K. The wide range of thermal conductivity varies the mechanical properties of the resulting components and lifetime of HPF dies.

Sensing the water content of honey from temperature-dependent electrical conductivity

International Nuclear Information System (INIS)

Guo, Wenchuan; Liu, Yi; Zhu, Xinhua; Zhuang, Hong

2011-01-01

In order to predict the water content in honey, electrical conductivity was measured on blossom honey types milk-vetch, jujube and yellow-locust with the water content of 18–37% between 5 and 40 °C. The regression models of electrical conductivity were developed as functions of water content and temperature. The results showed that increases in either water content or temperature resulted in an increase in the electrical conductivity of honey with greater changes at higher water content and/or higher temperature. The linear terms of water content and temperature, a quadratic term of water content, and the interaction effect of water content and temperature had significant influence on the electrical conductivity of honey (p < 0.0001). Regardless of blossom honey type, the linear coefficient of the determination of measured and calculated electrical conductivities was 0.998 and the range error ratio was larger than 100. These results suggest that the electrical conductivity of honey might be used to develop a detector for rapidly predicting the water content in blossom honey

Structure, ionic Conductivity and mobile Carrier Density in Fast Ionic Conducting Chalcogenide Glasses

International Nuclear Information System (INIS)

Wenlong Yao

2006-01-01

This thesis consists of six sections. The first section gives the basic research background on the ionic conduction mechanism in glass, polarization in the glass, and the method of determining the mobile carrier density in glass. The proposed work is also included in this section. The second section is a paper that characterizes the structure of MI + M 2 S + (0.1 Ga 2 S 3 + 0.9 GeS 2 ) (M = Li, Na, K and Cs) glasses using Raman and IR spectroscopy. Since the ionic radius plays an important role in determining the ionic conductivity in glasses, the glass forming range for the addition of different alkalis into the basic glass forming system 0.1 Ga 2 S 3 + 0.9 GeS 2 was studied. The study found that the change of the alkali radius for the same nominal composition causes significant structure change to the glasses. The third section is a paper that investigates the ionic conductivity of MI + M 2 S + (0.1Ga 2 S 3 + 0.9 GeS 2 ) (M = Li, Na, K and Cs) glasses system. Corresponding to the compositional changes in these fast ionic conducting glasses, the ionic conductivity shows changes due to the induced structural changes. The ionic radius effect on the ionic conductivity in these glasses was investigated. The fourth section is a paper that examines the mobile carrier density based upon the measurements of space charge polarization. For the first time, the charge carrier number density in fast ionic conducting chalcogenide glasses was determined. The experimental impedance data were fitted using equivalent circuits and the obtained parameters were used to determine the mobile carrier density. The influence of mobile carrier density and mobility on the ionic conductivity was separated. The fifth section is a paper that studies the structures of low-alkali-content Na 2 S + B 2 S 3 (x (le) 0.2) glasses by neutron and synchrotron x-ray diffraction. Similar results were obtained both in neutron and synchrotron x-ray diffraction experiments. The results provide direct

Thermal conductivity of hyperstoichiometric SIMFUEL

Energy Technology Data Exchange (ETDEWEB)

Lucuta, P G; Verrall, R A [Chalk River Labs., AECL Research, Chalk River, ON (Canada); Matzke, H [CEC Joint Research Centre, Karlsruhe (Germany)

1997-08-01

At extended burnup, reduction in fuel thermal conductivity occurs as fission-gas bubble, solid fission-product (dissolved and precipitated) build-up, and the oxygen-to-uranium ratio (O/U) possible increases. The effects of solid fission products and the deviation from stoichiometry can be investigated using SIMFUEL (SIMulated high-burnup UO{sub 2} FUEL). The reduction in fuel conductivity due to solid fission products was assessed and reported previously. In this paper, thermal conductivity measurements on hyperstoichiometric SIMFUEL and UO{sub 2+x} investigating the effect of the excess of oxygen on fuel thermal properties, are reported. The thermal diffusivity, specific heat and density of hyperstorichiometric SIMFUEL and UO{sub 2+x}, annealed at the same oxygen potential, were measured to obtain thermal conductivity. The excess of oxygen lowered to the thermal diffusivity, but did not significantly affect the specific heat. The thermal conductivity of UO{sub 2+x} (no fission products present) decreases with an increasing O/U ratio; a reduction of 15%, 37% and 56% at 600 deg. C, and 11%, 23% and 33% at 1500 deg. C, was found for O/U ratios of 2.007, 2.035 and 2.084, respectively. For the SIMFUEL annealed at {Delta}Go{sub 2} = -245 kJ/mol (corresponding to UO{sub 2,007}), the thermal conductivity was practically unchanged, although for the higher oxygen potentials ({Delta}Go{sub 2} {>=} -205 kJ/mol) a reduction in thermal conductivity of the same order as in UO{sub 2+x} W as measured. For SIMFUEL, annealed in reducing conditions, the fission products lowered thermal conductivity significantly. However, for high oxygen potentials ({Delta}Go{sub 2} {>=} -205 kJ/mol), the thermal conductivities of UO{sub 2+x} and SIMFUEL were found to be approximately equal in the temperature range of 600 to 1500 deg. C. Consequently, excess oxygen is the dominant factor contributing to thermal conductivity degradation at high oxygen potentials. (author). 9 figs, 2 tabs.

Thermal conductivity of hyperstoichiometric SIMFUEL

International Nuclear Information System (INIS)

Lucuta, P.G.; Verrall, R.A.; Matzke, H.

1997-01-01

At extended burnup, reduction in fuel thermal conductivity occurs as fission-gas bubble, solid fission-product (dissolved and precipitated) build-up, and the oxygen-to-uranium ratio (O/U) possible increases. The effects of solid fission products and the deviation from stoichiometry can be investigated using SIMFUEL (SIMulated high-burnup UO 2 FUEL). The reduction in fuel conductivity due to solid fission products was assessed and reported previously. In this paper, thermal conductivity measurements on hyperstoichiometric SIMFUEL and UO 2+x investigating the effect of the excess of oxygen on fuel thermal properties, are reported. The thermal diffusivity, specific heat and density of hyperstorichiometric SIMFUEL and UO 2+x , annealed at the same oxygen potential, were measured to obtain thermal conductivity. The excess of oxygen lowered to the thermal diffusivity, but did not significantly affect the specific heat. The thermal conductivity of UO 2+x (no fission products present) decreases with an increasing O/U ratio; a reduction of 15%, 37% and 56% at 600 deg. C, and 11%, 23% and 33% at 1500 deg. C, was found for O/U ratios of 2.007, 2.035 and 2.084, respectively. For the SIMFUEL annealed at ΔGo 2 = -245 kJ/mol (corresponding to UO 2,007 ), the thermal conductivity was practically unchanged, although for the higher oxygen potentials (ΔGo 2 ≥ -205 kJ/mol) a reduction in thermal conductivity of the same order as in UO 2+x W as measured. For SIMFUEL, annealed in reducing conditions, the fission products lowered thermal conductivity significantly. However, for high oxygen potentials (ΔGo 2 ≥ -205 kJ/mol), the thermal conductivities of UO 2+x and SIMFUEL were found to be approximately equal in the temperature range of 600 to 1500 deg. C. Consequently, excess oxygen is the dominant factor contributing to thermal conductivity degradation at high oxygen potentials. (author). 9 figs, 2 tabs

Reflections on evaluative practice in higher education: an experience collaborative

Directory of Open Access Journals (Sweden)

Suênya Marley Mourão Batista

2016-12-01

Full Text Available This article aims to reflect on the evaluation practice of higher education teachers generated from research conducted as part of a private higher education institution. The objective of this study is to characterize the assessment practices of teachers who work in higher education and collaborate in order to facilitate the expansion of dynamic assessment practices were used as theoretical and methodological support the studies of Vygotsky (2007, Liberali (2008, Ibiapina (2007, 2008, Meier (2007, Campione (2002 and Hoffmann (2011. Field research was conducted in a qualitative approach to collaborative type with 3 (three in higher education using the reflective interview as data collection tool to promote critical thinking about assessment practices to develop. The results showed the prevalence of use of traditional assessment practices by teachers and the possibility of performing dynamic assessment practices from the understanding of these nurtured by the research and training process.

Electrical and thermal conductivities of Stycast 1266 epoxy/graphite composites

International Nuclear Information System (INIS)

Tien, Hoang; Park, Joonkyu; Han, Sanga; Ahmad, Muneer; Seo, Yongho; Shin, Koo

2011-01-01

Nanocomposites composed of graphene flakes and epoxy resin (Stycast 1266) were produced with different concentrations of graphene in the range of 0 to 15 wt.%. The direct-current conductivity of the composites complied with percolation behavior. The percolation threshold concentration pc from the conductivity measurement was estimated as 8 wt.%, and the critical exponent as t = 1.85 ± 0.23. The alternating-current conductivity of the composite increased monotonically as the frequency was increased in the range from 1 to 10 MHz. The thermal conductivity k also exhibited a similar percolation behavior, with highest value of k = 0.73 W/m·K for the 12-wt.% composite, which corresponds to a 350% enhancement of the thermal conductivity.

Patterning of self-assembled monolayers based on differences in molecular conductance.

Science.gov (United States)

Shen, Cai; Buck, Manfred

2009-06-17

Scanning tunneling microscopy (STM) is used for replacement patterning of self-assembled monolayers (SAMs) of thiols on a sub-10 nm scale. Contrasting other schemes of scanning probe patterning of SAMs, the exchange of molecules relies on differences in conductance and, thus, occurs under tunneling conditions where the resolution of the tip is maintained. Exchange takes place at the boundary between different thiols but only when the tip moves from areas of lower to higher conductance. In combination with SAMs which exhibit excellent structural quality, patterns with a contour definition of +/- 1 molecule, lines as thin as 2.5 nm and islands with an area of less than 20 nm2 are straightforwardly produced. It is suggested that the shear force exerted onto the molecules with the lower conductance triggers displacement of the one with higher conductance.

Contemporary Didactics in Higher Education in Russia

Science.gov (United States)

Shershneva, Victoria A.; Shkerina, Lyudmila V.; Sidorov, Valery N.; Sidorova, Tatiana V.; Safonov, Konstantin V.

2016-01-01

The article presents the theoretical framework for a competency-based approach in higher education. It shows that the general didactic principles of professional direction, interdisciplinary connections, fundamentalization and informatization form the didactic basis for the competency-based training in university. The article also actualizes the…

Low-temperature thermal conductivity of terbium-gallium garnet

International Nuclear Information System (INIS)

Inyushkin, A. V.; Taldenkov, A. N.

2010-01-01

Thermal conductivity of paramagnetic Tb 3 Ga 5 O 12 (TbGG) terbium-gallium garnet single crystals is investigated at temperatures from 0.4 to 300 K in magnetic fields up to 3.25 T. A minimum is observed in the temperature dependence κ(T) of thermal conductivity at T min = 0.52 K. This and other singularities on the κ(T) dependence are associated with scattering of phonons from terbium ions. The thermal conductivity at T = 5.1 K strongly depends on the magnetic field direction relative to the crystallographic axes of the crystal. Experimental data are considered using the Debye theory of thermal conductivity taking into account resonance scattering of phonons from Tb 3+ ions. Analysis of the temperature and field dependences of the thermal conductivity indicates the existence of a strong spin-phonon interaction in TbGG. The low-temperature behavior of the thermal conductivity (field and angular dependences) is mainly determined by resonance scattering of phonons at the first quasi-doublet of the electron spectrum of Tb 3+ ion.

Measurement of thermal conductivity of the oxide coating on autoclaved monel-400

International Nuclear Information System (INIS)

Dua, A.K.; George, V.C.; Agarwala, R.P.

1982-01-01

Thermal conductivity of the oxide coating on monel-400 has been measured by a direct method. The oxide coating is applied on an electrically conducting wire having stable characteristics. The wire is placed in a constant temperature bath and a constant direct current is passed through it. The wire gets heated and loses heat to the surrounding. Temperature is measured by considering it as a resistance thermometer. A convection heat transfer coefficient, which is difficult to measure experimentally but is involved in the analytical expression for thermal conductivity, is eliminated by connecting a second uncoated wire of a noble metal having similar surface finish as that of the coated wire in series with it. The accuracy of the method is nearly six percent. However, the method is not easily applicable for very thin (thickness <= 1μ), highly porous coatings and materials having relatively large thermal conductivity. (M.G.B.)

Active Bone Conduction Prosthesis: BonebridgeTM

Directory of Open Access Journals (Sweden)

Zernotti, Mario E.

2015-10-01

Full Text Available Introduction Bone conduction implants are indicated for patients with conductive and mixed hearing loss, as well as for patients with single-sided deafness (SSD. The transcutaneous technology avoids several complications of the percutaneous bone conduction implants including skin reaction, skin growth over the abutment, and wound infection. The Bonebridge (MED-EL, Austria prosthesis is a semi-implantable hearing system: the BCI (Bone Conduction Implant is the implantable part that contains the Bone Conduction-Floating Mass Transducer (BC-FMT, which applies the vibrations directly to the bone; the external component is the audio processor Amadé BB (MED-EL, Austria, which digitally processes the sound and sends the information through the coil to the internal part. Bonebridge may be implanted through three different approaches: the transmastoid, the retrosigmoid, or the middle fossa approach. Objective This systematic review aims to describe the world́s first active bone conduction implant system, Bonebridge, as well as describe the surgical techniques in the three possible approaches, showing results from implant centers in the world in terms of functional gain, speech reception thresholds and word recognition scores. Data Synthesis The authors searched the MEDLINE database using the key term Bonebridge. They selected only five publications to include in this systematic review. The review analyzes 20 patients that received Bonebridge implants with different approaches and pathologies. Conclusion Bonebridge is a solution for patients with conductive/mixed hearing loss and SSD with different surgical approaches, depending on their anatomy. The system imparts fewer complications than percutaneous bone conduction implants and shows proven benefits in speech discrimination and functional gain.

New lithium-ion conducting perovskite oxides related to (Li, La)TiO3

Indian Academy of Sciences (India)

Unknown

We describe the synthesis and lithium-ion conductivity of new perovskite-related oxides ... work on lithium-ion conducting perovskite oxides containing d0 cations. Keywords. ..... On the other hand, Nb/Ta compounds show a higher conductivity.

Effects of Anisotropic Thermal Conductivity in Magnetohydrodynamics Simulations of a Reversed-Field Pinch

International Nuclear Information System (INIS)

Onofri, M.; Malara, F.; Veltri, P.

2010-01-01

A compressible magnetohydrodynamics simulation of the reversed-field pinch is performed including anisotropic thermal conductivity. When the thermal conductivity is much larger in the direction parallel to the magnetic field than in the perpendicular direction, magnetic field lines become isothermal. As a consequence, as long as magnetic surfaces exist, a temperature distribution is observed displaying a hotter confined region, while an almost uniform temperature is produced when the magnetic field lines become chaotic. To include this effect in the numerical simulation, we use a multiple-time-scale analysis, which allows us to reproduce the effect of a large parallel thermal conductivity. The resulting temperature distribution is related to the existence of closed magnetic surfaces, as observed in experiments. The magnetic field is also affected by the presence of an anisotropic thermal conductivity.

Development of Conductivity Method as an Alternative to Titration for Hydrolytic Resistance Testing Used for Evaluation of Glass Vials Used in Pharmaceutical Industry.

Science.gov (United States)

Fujimori, Kiyoshi; Lee, Hans; Phillips, Joseph; Nashed-Samuel, Yasser

glass vial quality utilizes acid titration of vial extract pools to determine hydrolytic resistance or alkalinity. As an alternative to the European Pharmacopoeia method, the vial extracts were analyzed for conductivity, which directly determines the level of ions that were readily extracted from the vial surfaces. Lower quality glass would have greater surface defects that lead to higher ions extracted and higher conductivity value. The conductivity method was found to be suitable to measure the ions in water extracts and showed strong correlation with alkalinity. The advantage of the conductivity method over the alkalinity method was greater ease, lower volume requirements, stability, and flexibility in analysis. © PDA, Inc. 2017.

DC bias effect on alternating current electrical conductivity of poly(ethylene terephthalate)/alumina nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Nikam, Pravin N., E-mail: pravinya26@gmail.com; Deshpande, Vineeta D., E-mail: drdeshpandevd@gmail.com [Department of Physics, Institute of Chemical Technology, Matunga, Mumbai-400019, Maharashtra (India)

2016-05-06

Polymer nanocomposites based on metal oxide (ceramic) nanoparticles are a new class of materials with unique properties and designed for various applications such as electronic device packaging, insulation, fabrication and automotive industries. Poly(ethylene terephthalate) (PET)/alumina (Al{sub 2}O{sub 3}) nanocomposites with filler content between 1 wt% and 5 wt% were prepared by melt compounding method using co-rotating twin screw extruder and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and precision LCR meter techniques. The results revealed that proper uniform dispersion at lower content up to 2 wt% of nano-alumina observed by using TEM. Aggregation of nanoparticles was observed at higher content of alumina examined by using SEM and TEM. The frequency dependences of the alternating current (AC) conductivity (σ{sub AC}) of PET/alumina nanocomposites on the filler content and DC bias were investigated in the frequency range of 20Hz - 1MHz. The results showed that the AC and direct current (DC) conductivity increases with increasing DC bias and nano-alumina content upto 3 wt%. It follows the Jonscher’s universal power law of solids. It revealed that σ{sub AC} of PET/alumina nanocomposites can be well characterized by the DC conductivity (σ{sub DC}), critical frequency (ω{sub c}), critical exponent of the power law (s). Roll of DC bias potential led to an increase of DC conductivity (σ{sub DC}) due to the creation of additional conducting paths with the polymer nanocomposites and percolation behavior achieved through co-continuous morphology.

DC bias effect on alternating current electrical conductivity of poly(ethylene terephthalate)/alumina nanocomposites

International Nuclear Information System (INIS)

Nikam, Pravin N.; Deshpande, Vineeta D.

2016-01-01

Polymer nanocomposites based on metal oxide (ceramic) nanoparticles are a new class of materials with unique properties and designed for various applications such as electronic device packaging, insulation, fabrication and automotive industries. Poly(ethylene terephthalate) (PET)/alumina (Al_2O_3) nanocomposites with filler content between 1 wt% and 5 wt% were prepared by melt compounding method using co-rotating twin screw extruder and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and precision LCR meter techniques. The results revealed that proper uniform dispersion at lower content up to 2 wt% of nano-alumina observed by using TEM. Aggregation of nanoparticles was observed at higher content of alumina examined by using SEM and TEM. The frequency dependences of the alternating current (AC) conductivity (σ_A_C) of PET/alumina nanocomposites on the filler content and DC bias were investigated in the frequency range of 20Hz - 1MHz. The results showed that the AC and direct current (DC) conductivity increases with increasing DC bias and nano-alumina content upto 3 wt%. It follows the Jonscher’s universal power law of solids. It revealed that σ_A_C of PET/alumina nanocomposites can be well characterized by the DC conductivity (σ_D_C), critical frequency (ω_c), critical exponent of the power law (s). Roll of DC bias potential led to an increase of DC conductivity (σ_D_C) due to the creation of additional conducting paths with the polymer nanocomposites and percolation behavior achieved through co-continuous morphology.

Ion transport study in polymer-nanocomposite films by dielectric spectroscopy and conductivity scaling

Energy Technology Data Exchange (ETDEWEB)

Tripathi, Namrata, E-mail: ntripat@ilstu.edu [Department of Physics, Illinois State University, Normal, IL 61790 (United States); Thakur, Awalendra K. [Department of Physics, Indian Institute of Technology Patna, Bihar 800013 (India); Shukla, Archana [Department of Metallurgical Engineering & Materials Science, Indian Institute of Technology, Bombay 721302 (India); Marx, David T. [Department of Physics, Illinois State University, Normal, IL 61790 (United States)

2015-07-15

The dielectric and conductivity response of polymer nanocomposite electrolytes (films of PMMA{sub 4}LiClO{sub 4} dispersed with nano-CeO{sub 2} powder) have been investigated. The dielectric behavior was analyzed via the dielectric permittivity (ε′) and dissipation factor (tan δ) of the samples. The analysis has shown the presence of space charge polarization at lower frequencies. The real part of ac conductivity spectra of materials obeys the Jonscher power law. Parameters such as dc conductivity, hopping rate, activation energies and the concentration of charge carriers were determined from conductivity data using the Almond West formalism. It is observed that the higher ionic conductivity at higher temperature is due to increased thermally-activated hopping rates accompanied by a significant increase in carrier concentration. The contribution of carrier concentration to the total conductivity is also confirmed from activation energy of migration conduction and from Summerfield scaling. The ac conductivity results are also well correlated with TEM results.

Ion transport study in polymer-nanocomposite films by dielectric spectroscopy and conductivity scaling

Science.gov (United States)

Tripathi, Namrata; Thakur, Awalendra K.; Shukla, Archana; Marx, David T.

2015-07-01

The dielectric and conductivity response of polymer nanocomposite electrolytes (films of PMMA4LiClO4 dispersed with nano-CeO2 powder) have been investigated. The dielectric behavior was analyzed via the dielectric permittivity (ε‧) and dissipation factor (tan δ) of the samples. The analysis has shown the presence of space charge polarization at lower frequencies. The real part of ac conductivity spectra of materials obeys the Jonscher power law. Parameters such as dc conductivity, hopping rate, activation energies and the concentration of charge carriers were determined from conductivity data using the Almond West formalism. It is observed that the higher ionic conductivity at higher temperature is due to increased thermally-activated hopping rates accompanied by a significant increase in carrier concentration. The contribution of carrier concentration to the total conductivity is also confirmed from activation energy of migration conduction and from Summerfield scaling. The ac conductivity results are also well correlated with TEM results.

Resonance-induced sensitivity enhancement method for conductivity sensors

Science.gov (United States)

Tai, Yu-Chong (Inventor); Shih, Chi-yuan (Inventor); Li, Wei (Inventor); Zheng, Siyang (Inventor)

2009-01-01

Methods and systems for improving the sensitivity of a variety of conductivity sensing devices, in particular capacitively-coupled contactless conductivity detectors. A parallel inductor is added to the conductivity sensor. The sensor with the parallel inductor is operated at a resonant frequency of the equivalent circuit model. At the resonant frequency, parasitic capacitances that are either in series or in parallel with the conductance (and possibly a series resistance) is substantially removed from the equivalent circuit, leaving a purely resistive impedance. An appreciably higher sensor sensitivity results. Experimental verification shows that sensitivity improvements of the order of 10,000-fold are possible. Examples of detecting particulates with high precision by application of the apparatus and methods of operation are described.

Applications of oligomers for nanostructured conducting polymers.

Science.gov (United States)

Wang, Yue; Tran, Henry D; Kaner, Richard B

2011-01-03

This Feature Article provides an overview of the distinctive nanostructures that aniline oligomers form and the applications of these oligomers for shaping the nanoscale morphologies and chirality of conducting polymers. We focus on the synthetic methods for achieving such goals and highlight the underlying mechanisms. The clear advantages of each method and their possible drawbacks are discussed. Assembly and applications of these novel organic (semi)conducting nanomaterials are also outlined. We conclude this article with our perspective on the main challenges, new opportunities, and future directions for this nascent yet vibrant field of research. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of Polyethylene-Graft-Sulfonated Polyarylsulfone Proton Exchange Membranes for Direct Methanol Fuel Cell Applications.

Science.gov (United States)

Kim, Hyung Kyu; Zhang, Gang; Nam, Changwoo; Chung, T C Mike

2015-12-04

This paper examines polymer film morphology and several important properties of polyethylene-graft-sulfonated polyarylene ether sulfone (PE-g-s-PAES) proton exchange membranes (PEMs) for direct methanol fuel cell applications. Due to the extreme surface energy differences between a semi-crystalline and hydrophobic PE backbone and several amorphous and hydrophilic s-PAES side chains, the PE-g-s-PAES membrane self-assembles into a unique morphology, with many proton conductive s-PAES channels embedded in the stable and tough PE matrix and a thin hydrophobic PE layer spontaneously formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength >30 MPa, Young's modulus >1400 MPa) and low water swelling (λ 3 mmol/g in the s-PAES domains. On the surface, the thin hydrophobic and semi-crystalline PE layer shows some unusual barrier (protective) properties. In addition to exhibiting higher through-plane conductivity (up to 160 mS/cm) than in-plane conductivity, the PE surface layer minimizes methanol cross-over from anode to cathode with reduced fuel loss, and stops the HO• and HO₂• radicals, originally formed at the anode, entering into PEM matrix. Evidently, the thin PE surface layer provides a highly desirable protecting layer for PEMs to reduce fuel loss and increase chemical stability. Overall, the newly developed PE-g-s-PAES membranes offer a desirable set of PEM properties, including conductivity, selectivity, mechanical strength, stability, and cost-effectiveness for direct methanol fuel cell applications.

Globalisation and the internationalisation of higher education in sub-Saharan Africa

Directory of Open Access Journals (Sweden)

Kuzvinetsa Peter Dzvimbo

2013-01-01

Full Text Available In a shrinking world, in which a neo-liberal discourse has permeated sub-Saharan African higher education, critical reflection is required to assess the merits and demerits of globalisation. Research, intensive discussion and hearings conducted over a two-year period by the Task Force on Higher Education and Society, convened by the World Bank and United Nations Educational, Scientific, and Cultural Organization (UNESCO for the purpose of exploring the future of higher education in the developing world, led to the conclusion that without more and better higher education, developing countries would find it increasingly difficult to benefit from the global knowledge economy. A decade later, we argue for a radical change in the traditional discourse on globalisation because of the emergence of countries such as China, South Africa, India, and Brazil as global players in the world economy. These emerging global powers, reframe the political and imperial philosophy at the epicentre of globalisation discourse - an economic creed, through their mutual consultation and coordination on significant political issues. Their economic and military capabilities enable them to influence the trade regime and thereby strengthen the voice of the developing world as a whole. In relation to this paper's inquiry, the cooperation of these emerging powers gives the free enfranchised people of the world an opportunity to choose a different path of international relations (internationalisation formed on more liberal lines, as opposed to the neo-liberal economic rationality of globalisation. This paper therefore examines globalisation and internationalisation of higher education in sub-Saharan Africa, a field in which increased knowledge production and distribution open up opportunities for users, institutions and societies. Against a background of chronic economic uncertainty we examine the influence of major international institutions on the direction of higher

Integrated test plan for directional boring

International Nuclear Information System (INIS)

Volk, B.W.

1993-01-01

This integrated test plan describes the field testing of the DITCH WITCH Directional Boring System. DITCH WITCH is a registered trademark of The Charles Machine Works, Inc., Perry, Oklahoma. The test is being conducted as a coordinated effort between Charles Machine Works (CMW), Sandia National Laboratories (SNL), and the Westinghouse Hanford Company (WHC). Funding for the WHC portion of the project is through the Volatile Organic Compound-Arid Integrated Demonstration (VOC-Arid ID). The purpose of the test is to evaluate the performance of the directional boring system for possible future use on environmental restoration projects at Hanford and other Department of Energy (DOE) sites. The test will be conducted near the 200 Areas Fire Station located between the 200 East and 200 West Area of the Hanford Site. The directional boring system will be used to drill and complete (with fiberglass casing) two horizontal boreholes. A third borehole will be drilled to test sampling equipment but will not be completed with casing

Composition and conductance distributions of single GeSi quantum rings studied by conductive atomic force microscopy combined with selective chemical etching.

Science.gov (United States)

Lv, Y; Cui, J; Jiang, Z M; Yang, X J

2013-02-15

Atomic force microscopy imaging combined with selective chemical etching is employed to quantitatively investigate three-dimensional (3D) composition distributions of single GeSi quantum rings (QRs). In addition, the 3D quantitative composition distributions and the corresponding conductance distributions are simultaneously obtained on the same single GeSi QRs by conductive atomic force microscopy combined with selective chemical etching, allowing us to investigate the correlations between the conductance and composition distributions of single QRs. The results show that the QRs' central holes have higher Ge content, but exhibit lower conductance, indicating that the QRs' conductance distribution is not consistent with their composition distribution. By comparing the topography, composition and conductance profiles of the same single QRs before and after different etching processes, it is found that the conductance distributions of GeSi QRs do not vary with the change of composition distribution. Instead, the QRs' conductance distributions are found to be consistent with their topographic shapes, which can be supposed to be due to the shape determined electronic structures.

Inkjet printing of silver citrate conductive ink on PET substrate

Energy Technology Data Exchange (ETDEWEB)

Nie Xiaolei [Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Wang Hong, E-mail: hongwang@tju.edu.cn [Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Zou Jing [Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

2012-11-15

Highlights: Black-Right-Pointing-Pointer A direct synthesis method of silver conductive film on PET substrate was presented. Black-Right-Pointing-Pointer A stable particle-free conductive ink was prepared. Black-Right-Pointing-Pointer Formation of silver-amine complex reduced the thermal decomposition temperature. Black-Right-Pointing-Pointer Conductive patterns for flexible electronics were fabricated by inkjet printing. Black-Right-Pointing-Pointer Silver film on PET substrate possessed highest adhesion rating even without polymer. - Abstract: Direct synthesis of silver conductive film on PET substrate by inkjet printing silver citrate conductive ink was presented in this paper. This kind of conductive ink contained silver citrate as silver precursor, 1,2-diaminopropane as complex agent dissolving the silver salt and methanol and isopropanol as a media adjusting the viscosity and surface tension. The formation of silver-amine complex reduced the decomposition temperature from 180 Degree-Sign C to 135 Degree-Sign C, thus the ink could be cured at relatively low temperature. The film reached the lowest resistivity of 17 {mu}{Omega} cm after cured at 150 Degree-Sign C for 50 min, 3.1 {mu}{Omega} cm at 230 Degree-Sign C and possessed high reflection and excellent adhesive property. Electrical conductivity, surface morphology and composition were investigated by four-point probe method, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). It is demonstrated how the cured condition affects the silver film. Moreover, radio-frequency identification (RFID) antenna was fabricated by inkjet printing, which opens up routes for the flexible electronics fabrication.

Direct contamination - seasonality

International Nuclear Information System (INIS)

Aarkrog, A.

1994-01-01

Direct contamination is the primary pathway to terrestrial vegetation in the first period after an activity release to the atmosphere. All radionuclides are able to be transferred via this pathway. Deposition, interception and retention are the three processes involved in direct contamination of crops. Wet deposition is more important than dry deposition in temperature regions. Resuspension and rainsplash both belong to secondary direct deposition and became evident for e.g. radiocaesium after the Chernobyl accident. Seasonality is the varying response to radioactive contamination of crops according to the time of the year when the contamination occurs. Shortlived radionuclides (as 131 I) and those that mainly enter the foodchain by direct contamination (e.g. 137 Cs) are especially important in this connection. In particular, the contamination of cereal crops is influenced by seasonality. As a result of seasonality the impact of the Chernobyl accident on the radioactive contamination of human diet was for the same deposition density higher in southern than in northern Europe. (orig.)

Higher Education Language Policy

DEFF Research Database (Denmark)

Lauridsen, Karen M.

2013-01-01

Summary of recommendations HEIs are encouraged, within the framework of their own societal context, mission, vision and strategies, to develop the aims and objectives of a Higher Education Language Policy (HELP) that allows them to implement these strategies. In this process, they may want......: As the first step in a Higher Education Language Policy, HEIs should determine the relative status and use of the languages employed in the institution, taking into consideration the answers to the following questions:  What is/are the official language(s) of the HEI?  What is/are the language...... and the level of internationalisation the HEI has or wants to have, and as a direct implication of that, what are the language proficiency levels expected from the graduates of these programme?  Given the profile of the HEI and its educational strategies, which language components are to be offered within...

Quality of higher education: organisational or educational?

DEFF Research Database (Denmark)

Zou, Yihuan; Du, Xiangyun; Rasmussen, Palle

2012-01-01

Based on a study of Chinese university self-evaluation reports, this paper argues that higher education institutions are trying to manage the tensions between educational and organisational quality and the increasing and worldwide concerns about quality assurance. After 30 years of dramatic...... remain an important basis for external review. In an attempt to examine the institutional understanding of quality in higher education, the authors conducted a content analysis study of 53 self-evaluation reports written by a wide range of higher education institutions in China. This study concludes...... educational reform, China has established a nationwide evaluation system for assessing its higher education institutions. This comprehensive system includes a series of procedures for both internal self-evaluation and external peer reviewing, among which self-evaluation reports prepared by each institution...

Thermal conductivity of niobium single crystals in a magnetic field

International Nuclear Information System (INIS)

Gladun, C.; Vinzelberg, H.

1980-01-01

The thermal conductivity in longitudinal magnetic fields up to 5 T and in the temperature range 3.5 to 15 K is measured in two high purity niobium single crystals having residual resistivity ratios of 22700 and 19200 and orientations of the rod axis [110] and [100]. The investigations show that by means of the longitudinal magnetic field the thermal conductivity may decrease only to a limiting value. In the crystal directions [110] and [100] for the ratio of the thermal conductivity in zero field and the thermal conductivity in the saturation field the temperature-independent factors 1.92 and 1.27, respectively, are determined. With the aid of these factors the thermal conductivity in the normal state is evaluated from the measured values of thermal conductivity below Tsub(c) in the magnetic field. The different conduction and scattering mechanisms are discussed. (author)

Quantum size effects on the thermal and potential conductivities of ideal gases

International Nuclear Information System (INIS)

Ozturk, Z F; Sisman, A

2009-01-01

Thermal and potential conductivities of ideal Maxwellian, Fermi and Bose gases are derived by considering the small corrections due to the wave character of gas particles. Potential conductivity is regarded as conductivity due to any potential gradient like electrical, gravitational or chemical ones. A long rectangular channel is considered as a transport domain. The size of the domain in the transport direction is much longer than the mean free path of particles l while the sizes in transverse directions are shorter than l. On the other hand, all sizes of the domain are assumed to be larger than the thermal de Broglie wavelength of particles. Therefore, quantum size effects (QSE) are weak enough to be considered as small corrections on conventional terms. Corrections on thermal and potential conductivities are examined. It is seen that the size and shape of the transport domain become additional control parameters on both conductivities. Since the size dependencies of thermal and electrical conductivities are different, the Lorenz number becomes size and shape dependent and deviations from the Wiedemann-Franz law may be expected in nanoscale due to QSE. Variations of the corrections with chemical potential are analysed.

Execution spaces for simple higher dimensional automata

DEFF Research Database (Denmark)

Raussen, Martin

Higher Dimensional Automata (HDA) are highly expressive models for concurrency in Computer Science, cf van Glabbeek [26]. For a topologist, they are attractive since they can be modeled as cubical complexes - with an inbuilt restriction for directions´of allowable (d-)paths. In Raussen [25], we...

A Collection of Studies Conducted in Education about "Global Warming" Problem

Science.gov (United States)

Bozdogan, Aykut Emre

2011-01-01

The studies global warming problem conducted in education discipline in the world and in Turkey were analysed for this study. The literature was reviewed extensively especially through the articles in the indexed journals of Ebsco Host, Science Direct, Taylor and Francis and Web of Science databases and this study was conducted according to the…

Electrochemical Switching of Conductance with Diarylethene-Based Redox-Active Polymers

DEFF Research Database (Denmark)

Logtenberg, Hella; van der Velde, Jasper H. M.; de Mendoza, Paula

2012-01-01

Reversible switching of conductance using redox triggered switching of a polymer-modified electrode is demonstrated. A bifunctional monomer comprising a central electroswitchable core and two bithiophene units enables formation of a film through anodic electropolymerization. The conductivity...... of the polymer can be switched electrochemically in a reversible manner by redox triggered opening and closing of the diarylethene unit. In the closed state, the conductivity of the modified electrode is higher than in the open state....

Thermal and electrical conductivities of Cd-Zn alloys

International Nuclear Information System (INIS)

Saatci, B; Ari, M; Guenduez, M; Meydaneri, F; Bozoklu, M; Durmus, S

2006-01-01

The composition and temperature dependences of the thermal and electrical conductivities of three different Cd-Zn alloys have been investigated in the temperature range of 300-650 K. Thermal conductivities of the Cd-Zn alloys have been determined by using the radial heat flow method. It has been found that the thermal conductivity decreases slightly with increasing temperature and the data of thermal conductivity are shifting together to the higher values with increasing Cd composition. In addition, the electrical measurements were determined by using a standard DC four-point probe technique. The resistivity increases linearly and the electrical conductivity decreases exponentially with increasing temperature. The resistivity and electrical conductivity are independent of composition of Cd and Zn. Also, the temperature coefficient of Cd-Zn alloys has been determined, which is independent of composition of Cd and Zn. Finally, Lorenz number has been calculated using the thermal and electrical conductivity values at 373 and 533 K. The results satisfy the Wiedemann-Franz (WF) relation at T 373 K), the WF relation could not hold and the phonon component contribution of thermal conductivity dominates the thermal conduction

Laser Processing of Carbon Nanotube Transparent Conducting Films

Science.gov (United States)

Mann, Andrew

Transparent conducting films, or TCFs, are 2D electrical conductors with the ability to transmit light. Because of this, they are used in many popular electronics including smart phones, tablets, solar panels, and televisions. The most common material used as a TCF is indium tin oxide, or ITO. Although ITO has great electrical and optical characteristics, it is expensive, brittle, and difficult to pattern. These limitations have led researchers toward other materials for the next generation of displays and touch panels. The most promising material for next generation TCFs is carbon nanotubes, or CNTs. CNTs are cylindrical tubes of carbon no more than a few atoms thick. They have different electrical and optical properties depending on their atomic structure, and are extremely strong. As an electrode, they conduct electricity through an array of randomly dispersed tubes. The array is highly transparent because of gaps between the tubes, and size and optical properties of the CNTs. Many research groups have tried making CNT TCFs with opto-electric properties similar to ITO but have difficultly achieving high conductivity. This is partly attributed to impurities from fabrication and a mix of different tube types, but is mainly caused by low junction conductivity. In functionalized nanotubes, junction conductivity is impaired by covalently bonded molecules added to the sidewalls of the tubes. The addition of this molecule, known as functionalization, is designed to facilitate CNT dispersion in a solvent by adding properties of the molecule to the CNTs. While necessary for a good solution, functionalization decreases the conductivity in the CNT array by creating defects in the tube's structures and preventing direct inter-carbon bonding. This research investigates removing the functional coating (after tube deposition) by laser processing. Laser light is able to preferentially heat the CNTs because of their optical and electrical properties. Through local conduction

THE EFFECT OF GRAIN ANGLE AND SPECIES ON THERMAL CONDUCTIVITY OF SOME SELECTED WOOD SPECIES

Directory of Open Access Journals (Sweden)

Rasit Esen

2011-06-01

Full Text Available In this study the thermal conductivity of different wood materials was determined. For this purpose, Scots pine (Pinus sylvestris L., Uludag fir (Abies Bornmülleriana Matff, Oriental beech (Fagus orientalis L, Oak (Quercus robur L., and Chestnut of Anatolia (Castanea sativa Mill. woods were used. In the test, the thermal conductivity of the woods was measured according to procedure of ASTM C 1113-99 standards. The lowest thermal conductivity was obtained in the perpendicular direction of Scots pine samples as 0.156 Kcal/mh°C. The highest thermal conductivity was obtained from perpendicular direction of samples in Oriental beech as 0.331 Kcal/mh°C.

Luting of CAD/CAM ceramic inlays: direct composite versus dual-cure luting cement.

Science.gov (United States)

Kameyama, Atsushi; Bonroy, Kim; Elsen, Caroline; Lührs, Anne-Katrin; Suyama, Yuji; Peumans, Marleen; Van Meerbeek, Bart; De Munck, Jan

2015-01-01

The aim of this study was to investigate bonding effectiveness in direct restorations. A two-step self-etch adhesive and a light-cure resin composite was compared with luting with a conventional dual-cure resin cement and a two-step etch and rinse adhesive. Class-I box-type cavities were prepared. Identical ceramic inlays were designed and fabricated with a computer-aided design/computer-aided manufacturing (CAD/CAM) device. The inlays were seated with Clearfil SE Bond/Clearfil AP-X (Kuraray Medical) or ExciTE F DSC/Variolink II (Ivoclar Vivadent), each by two operators (five teeth per group). The inlays were stored in water for one week at 37°C, whereafter micro-tensile bond strength testing was conducted. The micro-tensile bond strength of the direct composite was significantly higher than that from conventional luting, and was independent of the operator (P<0.0001). Pre-testing failures were only observed with the conventional method. High-power light-curing of a direct composite may be a viable alternative to luting lithium disilicate glass-ceramic CAD/CAM restorations.

A study of phonon anisotropic scattering effect on silicon thermal conductivity at nanoscale

International Nuclear Information System (INIS)

Bong, Victor N-S; Wong, Basil T.

2015-01-01

Previous studies have shown that anisotropy in phonon transport exist because of the difference in phonon dispersion relation due to different lattice direction, as observed by a difference in in-plane and cross-plane thermal conductivity. The directional preference (such as forward or backward scattering) in phonon propagation however, remains a relatively unexplored frontier. Our current work adopts a simple scattering probability in radiative transfer, which is called Henyey and Greenstein probability density function, and incorporates it into the phonon Monte Carlo simulation to investigate the effect of directional scattering in phonon transport. In this work, the effect of applying the anisotropy scattering is discussed, as well as its impact on the simulated thermal conductivity of silicon thin films. While the forward and backward scattering will increase and decrease thermal conductivity respectively, the extent of the effect is non-linear such that forward scattering has a more obvious effect than backward scattering

A study of phonon anisotropic scattering effect on silicon thermal conductivity at nanoscale

Energy Technology Data Exchange (ETDEWEB)

Bong, Victor N-S; Wong, Basil T. [Swinburne Sarawak Research Centre for Sustainable Technologies, Faculty of Engineering, Computing & Science, Swinburne University of Technology Sarawak Campus, 93350 Kuching, Sarawak (Malaysia)

2015-08-28

Previous studies have shown that anisotropy in phonon transport exist because of the difference in phonon dispersion relation due to different lattice direction, as observed by a difference in in-plane and cross-plane thermal conductivity. The directional preference (such as forward or backward scattering) in phonon propagation however, remains a relatively unexplored frontier. Our current work adopts a simple scattering probability in radiative transfer, which is called Henyey and Greenstein probability density function, and incorporates it into the phonon Monte Carlo simulation to investigate the effect of directional scattering in phonon transport. In this work, the effect of applying the anisotropy scattering is discussed, as well as its impact on the simulated thermal conductivity of silicon thin films. While the forward and backward scattering will increase and decrease thermal conductivity respectively, the extent of the effect is non-linear such that forward scattering has a more obvious effect than backward scattering.

Multi-sphere unit cell model to calculate the effective thermal conductivity in pebble bed reactors

International Nuclear Information System (INIS)

Van Antwerpen, W.; Rousseau, P.G.; Du Toit, C.G.

2010-01-01

A proper understanding of the mechanisms of heat transfer, fluid flow and pressure drop through a packed bed of spheres is of utmost importance in the design of a high temperature Pebble Bed Reactor (PBR). While the gas flows predominantly in the axial direction through the bed, the total effective thermal conductivity is a lumped parameter that characterises the total heat transfer in the radial direction through the packed bed. The study of the effective thermal conductivity is important because it forms an intricate part of the self-acting decay heat removal chain, which is directly related to the PBR safety case. The effective thermal conductivity is the summation of various heat transport phenomena. These are the enhanced thermal conductivity due to turbulent mixing as the fluid passes through the voids between pebbles, heat transfer due to the movement of the solid spheres and thermal conduction and thermal radiation between the spheres in a stagnant fluid environment. In this study, the conduction and radiation between the spheres are investigated. Firstly, existing correlations for the effective thermal conductivity are investigated, with particular attention given to its applicability in the near-wall region. Several phenomena in particular are examined namely: conduction through the spheres, conduction through the contact area between the spheres, conduction through the gas phase and radiation between solid surfaces. A new approach to simulate the effective thermal conductivity for randomly packed beds is then presented, namely the so-called Multi-sphere Unit Cell Model. The model is validated by comparing the results with that obtained in experiments. (authors)

Electrical conductivity of uranium-antimony oxide catalysts

International Nuclear Information System (INIS)

Golunski, S.E.; Nevell, T.G.; Hucknall, D.J.

1985-01-01

The relative ionic and electronic contributions to the electrical conductivity of a uranium-antimony oxide catalyst and of USbO 5 have been determined from measurements of a.c. and d.c. conductance. Under inert atmospheres (390 to 775 K) conduction in the catalyst (predominantly USb 3 O 10 together with small proportions of Sb 2 O 4 and USbO 5 ) is associated with both electronic and effectively charged atomic point defects. Only electronic conduction occurs in USbO 5 . Under oxygen (10 to 70 kPa, 493 to 682 K) both materials are n-type semiconductors at higher temperatures, but at lower temperatures semiconducting behaviour varies with the pressure of oxygen. Heating USbO 5 in oxygen induces an ionic contribution to conductivity. Ionic conduction in the catalyst is eliminated by heating in hydrogen or propene at 470 K but is restored by heating in oxygen. It is suggested that both charged oxygen vacancies and interstitial oxide ions are involved in interactions of gaseous components with uranium-antimony oxides. With alkenes, interstitial oxide ions give rise to the products of selective partial oxidation. (author)

Electrical conductivity of uranium-antimony oxide catalysts

Energy Technology Data Exchange (ETDEWEB)

Golunski, S.E.; Nevell, T.G. (Portsmouth Polytechnic (UK)); Hucknall, D.J. (Southampton Univ. (UK). Dept. of Chemistry)

1985-05-01

The relative ionic and electronic contributions to the electrical conductivity of a uranium-antimony oxide catalyst and of USbO/sub 5/ have been determined from measurements of a.c. and d.c. conductance. Under inert atmospheres (390 to 775 K) conduction in the catalyst (predominantly USb/sub 3/O/sub 10/ together with small proportions of Sb/sub 2/O/sub 4/ and USbO/sub 5/) is associated with both electronic and effectively charged atomic point defects. Only electronic conduction occurs in USbO/sub 5/. Under oxygen (10 to 70 kPa, 493 to 682 K) both materials are n-type semiconductors at higher temperatures, but at lower temperatures semiconducting behaviour varies with the pressure of oxygen. Heating USbO/sub 5/ in oxygen induces an ionic contribution to conductivity. Ionic conduction in the catalyst is eliminated by heating in hydrogen or propene at 470 K but is restored by heating in oxygen. It is suggested that both charged oxygen vacancies and interstitial oxide ions are involved in interactions of gaseous components with uranium-antimony oxides. With alkenes, interstitial oxide ions give rise to the products of selective partial oxidation.

Oxadiazole telechelics immobilized on silica for proton conductive membranes

Energy Technology Data Exchange (ETDEWEB)

Treekamol, Yaowapa; Schieda, Mauricio [GKSS-Forschungszentrum Geesthacht GmbH (Germany); Nunes, Suzana [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Schulte, Karl [Technische Univ. Hamburg-Harburg, Hamburg (Germany)

2010-07-01

Functionalized silica and layered silicates have been used in our group to prepare proton conductive membranes with applications to direct methanol fuel cells. We report recent results on the use of silica with amphoteric functionalization in proton conductive membranes working at low humidity levels. Aerosil silica was functionalized by reacting it subsequently with bromophenyltrimethoxysilane and with aromatic bishydroxy terminated oxadiazole oligomers. We have prepared proton conductive membranes including as fillers a series of different sulfonated and non-sulfonated telechelics, synthesized with diphenylsulfone, diphenylether and fluorinated oxadiazole segments. We will present a comparison between fillers with different functionalization and how they affect the conductivity of a proton conductive polymer matrix. The functionalized fillers present the possibility of improving water retention and increasing the maximum doping level with phosphoric acid. Furthermore, the oligomer segments, containing both basic nitrogen and acid sulfonic groups, give an amphoteric character to the membrane, improving the proton conductivity in low humidity conditions. (orig.)

24 CFR 291.210 - Direct sales procedures.

Science.gov (United States)

2010-04-01

... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Direct sales procedures. 291.210... URBAN DEVELOPMENT HUD-OWNED PROPERTIES DISPOSITION OF HUD-ACQUIRED SINGLE FAMILY PROPERTY Sales Procedures § 291.210 Direct sales procedures. When HUD conducts the sales listed in § 291.90(c), it will sell...

High through-plane thermal conduction of graphene nanoflake filled polymer composites melt-processed in an L-shape kinked tube.

Science.gov (United States)

Jung, Haejong; Yu, Seunggun; Bae, Nam-Seok; Cho, Suk Man; Kim, Richard Hahnkee; Cho, Sung Hwan; Hwang, Ihn; Jeong, Beomjin; Ryu, Ji Su; Hwang, Junyeon; Hong, Soon Man; Koo, Chong Min; Park, Cheolmin

2015-07-22

Design of materials to be heat-conductive in a preferred direction is a crucial issue for efficient heat dissipation in systems using stacked devices. Here, we demonstrate a facile route to fabricate polymer composites with directional thermal conduction. Our method is based on control of the orientation of fillers with anisotropic heat conduction. Melt-compression of solution-cast poly(vinylidene fluoride) (PVDF) and graphene nanoflake (GNF) films in an L-shape kinked tube yielded a lightweight polymer composite with the surface normal of GNF preferentially aligned perpendicular to the melt-flow direction, giving rise to a directional thermal conductivity of approximately 10 W/mK at 25 vol % with an anisotropic thermal conduction ratio greater than six. The high directional thermal conduction was attributed to the two-dimensional planar shape of GNFs readily adaptable to the molten polymer flow, compared with highly entangled carbon nanotubes and three-dimensional graphite fillers. Furthermore, our composite with its density of approximately 1.5 g/cm(3) was mechanically stable, and its thermal performance was successfully preserved above 100 °C even after multiple heating and cooling cycles. The results indicate that the methodology using an L-shape kinked tube is a new way to achieve polymer composites with highly anisotropic thermal conduction.

Social Conduct Scale (SCS: a psychometric investigation

Directory of Open Access Journals (Sweden)

Caroline Tozzi Reppold

2016-01-01

Full Text Available Abstract The social conduct of an individual comprises all the interpersonal behaviors that he or she exhibits in the social contexts he or she is exposed to. The Social Conduct Scale (SCS is a self-report instrument developed to provide researchers and clinicians with information on prosocial, antisocial and oppositional-defiant tendencies of Portuguese-speaking children and adolescents. In the present study, we conducted an analysis of the criterion validity of the SCS by comparing the scores obtained from a large population-based sample (N= 1,172 against an offender (N= 129, a scholar (N= 31, and a clinic-referred (N= 24 sample of adolescents with marked previous conduct problems. As expected, antisocial youths had significantly higher means on antisocial behaviors and lower means on prosocial tendencies when compared to the population-based sample. Overall, findings supported the hypothesized criterion validity of the SCS. The instrument might play a role as a helpful resource for researchers, clinicians and practitioners interested in assessing the social conduct of Brazilian children and adolescents.

Synthesis, characterization and AC conductivity studies of silver doped conducting polyaniline/graphene/SrTiO3 composites

Science.gov (United States)

Vinay, K.; Shivakumar, K.; Ravikiran, Y. T.; Revanasiddappa, M.

2018-05-01

The present work is an investigation of ac conduction behaviour and dielectric response of Polyaniline/Ag/Graphene/SrTiO3 (PAGS) composite prepared by in-situ chemical oxidative interfacial polymerization using (NH4)2S2O8 as an oxidising agent at 0-5°C. The structural characterization of the samples was examined using FT-IR and XRD techniques. The ac conductivity and dielectric response of synthesized polymer composites were investigated at room temperature in the frequency range varying from 5 × 101 - 5 × 106 Hz using HIOKI make 3532-50 LCR Hi-tester. The ac conductivity increases with increase in frequency and follows the regular trend, the real dielectric constant (ɛ') and imaginary dielectric constant (ɛ'') decreases with increase in frequency and exhibits almost zero dielectric loss at higher frequencies, which suggests that the composite is a lossless material at frequencies beyond 3Hz.

Analysis of the electrical conduction in CdHgTe crystals

International Nuclear Information System (INIS)

Dziuba, Z.

1987-01-01

The electrical conduction versus magnetic field in p-like CdHgTe samples at 77 K is investigated by analysing the conductivity tensor components. The electrical conduction is mainly due to electrons in the conduction band and low-mobility carriers in an impurity band. In the investigated samples Cd/sub x/Hg/sub 1-x/Te with the composition x approximately 0.17 the concentration of electrons in the conduction band is higher than the intrinsic one and in samples with the composition close to HgTe the concentration of electrons in the conduction band is equal to or lower than the intrinsic one. The model of a half-filled impurity band situated close to the bottom of the conduction band is proposed to account for the concentration of electrons in the conduction band. (author)

Hybrid hydrogels containing vertically aligned carbon nanotubes with anisotropic electrical conductivity for muscle myofiber fabrication.

Science.gov (United States)

Ahadian, Samad; Ramón-Azcón, Javier; Estili, Mehdi; Liang, Xiaobin; Ostrovidov, Serge; Shiku, Hitoshi; Ramalingam, Murugan; Nakajima, Ken; Sakka, Yoshio; Bae, Hojae; Matsue, Tomokazu; Khademhosseini, Ali

2014-03-19

Biological scaffolds with tunable electrical and mechanical properties are of great interest in many different fields, such as regenerative medicine, biorobotics, and biosensing. In this study, dielectrophoresis (DEP) was used to vertically align carbon nanotubes (CNTs) within methacrylated gelatin (GelMA) hydrogels in a robust, simple, and rapid manner. GelMA-aligned CNT hydrogels showed anisotropic electrical conductivity and superior mechanical properties compared with pristine GelMA hydrogels and GelMA hydrogels containing randomly distributed CNTs. Skeletal muscle cells grown on vertically aligned CNTs in GelMA hydrogels yielded a higher number of functional myofibers than cells that were cultured on hydrogels with randomly distributed CNTs and horizontally aligned CNTs, as confirmed by the expression of myogenic genes and proteins. In addition, the myogenic gene and protein expression increased more profoundly after applying electrical stimulation along the direction of the aligned CNTs due to the anisotropic conductivity of the hybrid GelMA-vertically aligned CNT hydrogels. We believe that platform could attract great attention in other biomedical applications, such as biosensing, bioelectronics, and creating functional biomedical devices.

Ionic conducting poly-benzimidazoles

International Nuclear Information System (INIS)

Jouanneau, J.

2006-11-01

Over the last years, many research works have been focused on new clean energy systems. Hydrogen fuel cell seems to be the most promising one. However, the large scale development of this technology is still limited by some key elements. One of them is the polymer electrolyte membrane 'Nafion' currently used, for which the ratio performance/cost is too low. The investigations we carried out during this thesis work are related to a new class of ionic conducting polymer, the sulfonated poly-benzimidazoles (sPBI). Poly-benzimidazoles (PBI) are aromatic heterocyclic polymers well-known for their excellent thermal and chemical stability. Ionic conduction properties are obtained by having strong acid groups (sulfonic acid SO 3 H) on the macromolecular structure. For that purpose, we first synthesized sulfonated monomers. Their poly-condensation with an appropriate non-sulfonated co-monomer yields to sPBI with sulfonation range from 0 to 100 per cent. Three different sPBI structures were obtained, and verified by appropriate analytical techniques. We also showed that the protocol used for the synthesis resulted in high molecular weights polymers. We prepared ionic conducting membrane by casting sPBI solutions on glass plates. Their properties of stability, water swelling and ionic conductivity were investigated. Surprisingly, the behaviour of sPBI was quite different from the other sulfonated aromatic polymers with same amount of SO 3 H, their stability was much higher, but their water swelling and ionic conductivity were quite low. We attributed these differences to strong ionic interactions between the sulfonic acid groups and the basic benzimidazole groups of our polymers. However, we managed to solve this problem synthesizing very highly sulfonated PBI, obtaining membranes with a good balance between all the properties necessary. (author)

water infiltration, conductivity and runoff under fallow

African Journals Online (AJOL)

Measurements of runoff was done during the long rains of. 2003 and short rains of 2004. Infiltration was invariably higher under agroforestry systems (P<0.001) than sole cropping, particularly under Alnus and Calliandra systems. A similar pattern was observed for saturated hydraulic conductivity (Ksat), which was greater in ...

Decoupling ion conductivity and fluid permeation through optimizing hydrophilic channel morphology

Energy Technology Data Exchange (ETDEWEB)

Chu, Peter Po-Jen, E-mail: pjchu@cc.ncu.edu.tw; Fang, Yu-Shin; Tseng, Yu-Chen [Department of Chemistry, National Central University, No. 300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan (R.O.C.) (China)

2016-05-18

Approaches to improve membrane ion conductivity usually leads to higher degree of swelling, more serious fuel cross-over and often sacrificed membrane mechanical strength. Preserving all three main membrane properties is a tough challenge in searching high ion conducting fuel cell membrane. The long standing dilemma is resolved by decoupling ion conduction and fluid permeation property by creating optimized channel morphology using external electric field poling. Success of this approach is demonstrated in the proton conducting membrane composed of poly(ether sulfones) (PES) and sulfonated poly(ether ether ketone) (sPEEK, degree of sulfonation=50%) composites prepared under electric field poling condition. The external field enhanced the aromatic chain ordering from both sPEEK and PES and improved the miscibility. This induced interaction is conducive to the formation of more densely packed amorphous domains that eventually leads to preferentially ordered hydrophilic proton conducting channels having a average dimension (3 nm) smaller than that in generic sPEEK or Nafion. The narrower but more ordered channel displayed much lower methanol permeability (3.17×10{sup −7} cm{sup 2}/s), and lower swelling ratio (31.20%), while the conductivity (~10{sup −1} S/cm) is higher than that of Nafion, or sPEEK at higher (64%) degree of sulfonation. The composite is chemically stable and highly durable with improved membrane mechanical strength. Nearly 50% increase of DMFC power output is observed using this membrane, and the best power density is recorded at 155 mA/cm{sup 2} (80 °C, 1M Methanol).

The Impact of Foreign Direct Investment (FDI on the Environment: Market Perspectives and Evidence from China

Directory of Open Access Journals (Sweden)

Jiajia Zheng

2017-03-01

Full Text Available Foreign direct investment (FDI may have a positive effect on the level of pollution in host countries, as described by the pollution haven hypothesis (PHH. However, this kind of effect may depend on the economic conditions in host countries. In this study, we conduct research on the FDI’s effect on China’s CO2 emissions during the market-oriented reform. The results are as follows. Firstly, FDI directly promotes China’s CO2 emissions. Secondly, with market-oriented reform, this positive effect from FDI is lowering year by year, which indicates that the market-oriented reform could alleviate the positive effect of FDI on China’s CO2 emissions. Thirdly, as China’s market-oriented reform was implemented gradually from experimental zones to the whole country, regional market development is uneven, and as such so is FDI’s effect on local CO2 emissions. Provinces in the eastern area generally evidenced higher market development and lower CO2 emissions from FDI, while four provinces in west area evidenced both lower market development and higher CO2 emissions from FDI.

A comparative analysis on combustion and emissions of some next generation higher-alcohol/diesel blends in a direct-injection diesel engine

International Nuclear Information System (INIS)

Rajesh Kumar, B.; Saravanan, S.; Rana, D.; Nagendran, A.

2016-01-01

Highlights: • Four higher-alcohols namely, iso-butanol, n-pentanol, n-hexanol and n-octanol, were used. • Iso-butanol/diesel blend presented longest ignition delay, highest peak pressures and peak heat release rates. • NOx emissions were high for n-pentanol/diesel and n-hexanol/diesel blends at high load conditions. • Smoke opacity is highest for n-octanol/diesel blend and lowest for iso-butanol/diesel blend. • HC emissions are high for iso-butanol/diesel and n-pentanol/diesel blends. - Abstract: Higher alcohols are attractive next generation biofuels that can be extracted from sugary, starchy and ligno-cellulosic biomass feedstocks using sustainable pathways. Their viability for use in diesel engines has greatly improved ever since extended bio-synthetic pathways have achieved substantial yields of these alcohols using engineered micro-organisms. This study sets out to compare and analyze the effects of some higher alcohol/diesel blends on combustion and emission characteristics of a direct-injection diesel engine. Four test fuels containing 30% by vol. of iso-butanol, n-pentanol, n-hexanol and n-octanol (designated as ISB30, PEN30, HEX30 and OCT30 respectively) in ultra-low sulfur diesel (ULSD) were used. Results indicated that ISB30 experienced longest ignition delay and produced highest peaks of pressure and heat release rates (HRR) compared to other higher-alcohol blends. The ignition delay, peak pressure and peak HRR are found to be in the order of (from highest to lowest): ISB30 > PEN30 > HEX30 > OCT30 > ULSD. The combustion duration (CD) for all test fuels is in the sequence (from shortest to longest): ISB30 OCT30 > HEX30 > PEN30 > ISB30. HC emissions are high for ISB30 and PEN30 while it decreased favorably for HEX30 and OCT30. It was of the order (from highest to lowest): ISB30 > PEN30 > ULSD > HEX30 > OCT30. CO emissions of the blends followed the trend of smoke emissions and remained lower than ULSD with the following order (from highest to

Authentic Assessment and Pedagogical Strategies in Higher Education

OpenAIRE

Chan Yuen Fook; Gurnam Kaur Sidhu

2010-01-01

Problem statement: Researchers have noted that there is a mismatch between curriculum content and assessment practices in higher education. At the moment, the focus is still on the assessment of learning and not much on assessment for learning. Therefore, this study was conducted to examine the implementation of authentic assessment in higher education in Malaysia. Approach: The study employed a qualitative research method and involved the use of instruments such as interviews, document analy...

Workplace Harassment among Staff in Higher Education: A Systematic Review

Science.gov (United States)

Henning, Marcus A.; Zhou, Chen; Adams, Peter; Moir, Fiona; Hobson, Jennifer; Hallett, Charlene; Webster, Craig S.

2017-01-01

Workplace harassment in higher education adversely impacts workforce productivity and has deleterious health effects on victims. The aim of this study was to review the literature pertaining to workplace harassment in higher education. This systematic literature search was conducted in December 2013 and completed in January 2014. Refereed journal…

Direct sulfation of limestone based on oxy-fuel combustion technology

Energy Technology Data Exchange (ETDEWEB)

Chen, C.M.; Zhao, C.S.; Liu, S.T.; Wang, C.B. [North China Electric Power University, Baoding (China)

2009-10-15

With limestone as the sorbent, the sulfation reaction can proceed via two different routes depending on whether calcination of the limestone takes place under the given reaction conditions. The direct sulfation reaction is defined as the sulfation reaction between sulfur dioxide (SO{sub 2}) and limestone in an uncalcined state. This reaction, based on oxyfuel combustion technology, was studied by thermogravimetric analysis. Surface morphologies of the limestone particles after sulfation were examined by a scanning electron microscope. Results show that there are more pores or gaps in the product layer formed by direct sulfation of limestone than by indirect sulfation, which can be attributed to the generation of carbon dioxide (CO{sub 2}) at a reaction interface. Compared with indirect sulfation, direct sulfation of limestone can yield much higher conversion and has a much higher reaction rate. For direct sulfation, the greater porosity in the product layer greatly reduces the solid-state ion diffusion distance, resulting in a higher reaction rate and higher conversion.

Piezoelectric power converter with bi-directional power transfer

DEFF Research Database (Denmark)

2014-01-01

The present invention relates to a bi-directional piezoelectric power converter com¬ prising a piezoelectric transformer. The piezoelectric transformer comprises an input electrode electrically coupled to a primary section of the piezoelectric transformer and an output electrode electrically...... coupled to an output section of the piezoelectric transformer to provide a transformer output signal. A bi-directional switching circuit is coupled between the output electrode and a DC or AC output voltage of the power converter. Forward and reverse current conducting periods of the bi......, a reverse current is conducted through the bi-directional switching circuit from the DC or AC output voltage to the output electrode to discharge the DC or AC output voltage and return power to the primary section of the piezoelectric transformer....

Exposure to maternal pre- and postnatal depression and anxiety symptoms: risk for major depression, anxiety disorders, and conduct disorder in adolescent offspring.

Science.gov (United States)

Glasheen, Cristie; Richardson, Gale A; Kim, Kevin H; Larkby, Cynthia A; Swartz, Holly A; Day, Nancy L

2013-11-01

This study evaluated whether exposure to maternal pre- or postnatal depression or anxiety symptoms predicted psychopathology in adolescent offspring. Growth mixture modeling was used to identify trajectories of pre- and postnatal depression and anxiety symptoms in 577 women of low socioeconomic status selected from a prenatal clinic. Logistic regression models indicated that maternal pre- and postnatal depression trajectory exposure was not associated with offspring major depression, anxiety, or conduct disorder, but exposure to the high depression trajectory was associated with lower anxiety symptoms in males. Exposure to medium and high pre- and postnatal anxiety was associated with the risk of conduct disorder among offspring. Male offspring exposed to medium and high pre- and postnatal anxiety had higher odds of conduct disorder than did males with low exposure levels. Females exposed to medium or high pre- and postnatal anxiety were less likely to meet conduct disorder criteria than were females with lower exposure. To the best of our knowledge, this is the first study to examine the effect of pre- and postnatal anxiety trajectories on the risk of conduct disorder in offspring. These results suggest new directions for investigating the etiology of conduct disorder with a novel target for intervention.

Effect of the type of metal on the electrical conductivity and thermal properties of metal complexes: The relation between ionic radius of metal complexes and electrical conductivity

Science.gov (United States)

Morgan, Sh. M.; El-Ghamaz, N. A.; Diab, M. A.

2018-05-01

Co(II) complexes (1-4) and Ni(II) complexes (5-8) were prepared and characterized by elemental analysis, IR spectra and thermal analysis data. Thermal decomposition of all complexes was discussed using thermogravimetric analysis. The dielectric properties and alternating current conductivity were investigated in the frequency range 0.1-100 kHz and temperature range 300-660 K. The thermal activation energies of electrical conductivity (ΔE1 and ΔE2) values for complexes were calculated and discussed. The values of ΔE1 and ΔE2 for complexes (1-8) were found to decrease with increasing the frequency. Ac electrical conductivity (σac) values increases with increasing temperatures and the values of σac for Co(II) complexes are greater than Ni(II) complexes. Co(II) complexes showed a higher conductivity than other Ni(II) complexes due to the higher crystallinity as confirmed by X-ray diffraction analysis.

A MODEL FOR HIGHER EDUCATION CAMPUS HEALTH SERVICES

African Journals Online (AJOL)

2010-03-17

Mar 17, 2010 ... generation was used to develop a holistic healthcare model for a higher education campus' health service. It became ... innovative. Health plays a .... conducted will set the tone for the interactive process of holistic healthcare.

Magnetic field mediated conductance oscillation in graphene p–n junctions

Science.gov (United States)

Cheng, Shu-Guang

2018-04-01

The electronic transport of graphene p–n junctions under perpendicular magnetic field is investigated in theory. Under low magnetic field, the transport is determined by the resonant tunneling of Landau levels and conductance versus magnetic field shows a Shubnikov–de Haas oscillation. At higher magnetic field, the p–n junction subjected to the quasi-classical regime and the formation of snake states results in periodical backscattering and transmission as magnetic field varies. The conductance oscillation pattern is mediated both by magnetic field and the carrier concentration on bipolar regions. For medium magnetic field between above two regimes, the combined contributions of resonant tunneling, snake states oscillation and Aharanov–Bohm interference induce irregular oscillation of conductance. At very high magnetic field, the system is subjected to quantum Hall regime. Under disorder, the quantum tunneling at low magnetic field is slightly affected and the oscillation of snake states at higher magnetic field is suppressed. In the quantum Hall regime, the conductance is a constant as predicted by the mixture rule.

Thermal conductivity of 238PuO2 powder, intermediates, and dense fuel forms

International Nuclear Information System (INIS)

Bickford, D.F.; Crain, B. Jr.

1975-10-01

The thermal conductivities of porous 238 PuO 2 powder (calcined oxalate), milled powder, and high-density granules were calculated from direct measurements of steady-state temperature profiles resulting from self-heating. Thermal conductivities varied with density, temperature, and gas content of the pores. Errors caused by thermocouple heat conduction were less than 5 percent when the dimensions of the thermal conductivity cell and the thermocouple were properly selected