Bis-aryl substituted dioxaborines as electron-transport materials: a comparative density functional theory investigation with oxadiazoles and siloles

International Nuclear Information System (INIS)

Risko, C.; Zojer, E.; Brocorens, P.; Marder, S.R.; Bredas, J.L.

2005-01-01

We report on a detailed quantum-chemical comparison of the electronic structures, vertical electron affinities, and intramolecular reorganization energies for bis-aryl substituted dioxaborine, oxadiazole, and silole derivatives. The results indicate that the HOMO and LUMO energies of the substituted compounds can be tuned on the order of 2-3 eV via minor changes in the substitution patterns, with the HOMO and LUMO levels for the dioxaborine derivatives consistently the most energy stabilized. Additionally, large vertical electron affinities and comparable intramolecular reorganization energies confirm that dioxaborine systems are interesting candidates for electron transport materials

Blue emitting 1,8-naphthalimides with electron transport properties for organic light emitting diode applications

Science.gov (United States)

Ulla, Hidayath; Kiran, M. Raveendra; Garudachari, B.; Ahipa, T. N.; Tarafder, Kartick; Adhikari, Airody Vasudeva; Umesh, G.; Satyanarayan, M. N.

2017-09-01

In this article, the synthesis, characterization and use of two novel naphthalimides as electron-transporting emitter materials for organic light emitting diode (OLED) applications are reported. The molecules were obtained by substituting electron donating chloro-phenoxy group at the C-4 position. A detailed optical, thermal, electrochemical and related properties were systematically studied. Furthermore, theoretical calculations (DFT) were performed to get a better understanding of the electronic structures. The synthesized molecules were used as electron transporters and emitters in OLEDs with three different device configurations. The devices with the molecules showed blue emission with efficiencies of 1.89 cdA-1, 0.98 lmW-1, 0.71% at 100 cdm-2. The phosphorescent devices with naphthalimides as electron transport materials displayed better performance in comparison to the device without any electron transporting material and were analogous with the device using standard electron transporting material, Alq3. The results demonstrate that the naphthalimides could play a significant part in the progress of OLEDs.

Organic n-type materials for charge transport and charge storage applications.

Science.gov (United States)

Stolar, Monika; Baumgartner, Thomas

2013-06-21

Conjugated materials have attracted much attention toward applications in organic electronics in recent years. These organic species offer many advantages as potential replacement for conventional materials (i.e., silicon and metals) in terms of cheap fabrication and environmentally benign devices. While p-type (electron-donating or hole-conducting) materials have been extensively reviewed and researched, their counterpart n-type (electron-accepting or electron-conducting) materials have seen much less popularity despite the greater need for improvement. In addition to developing efficient charge transport materials, it is equally important to provide a means of charge storage, where energy can be used on an on-demand basis. This perspective is focused on discussing a selection of representative n-type materials and the efforts toward improving their charge-transport efficiencies. Additionally, this perspective will also highlight recent organic materials for battery components and the efforts that have been made to improve their environmental appeal.

Unconventional aspects of electronic transport in delafossite oxides

Science.gov (United States)

Daou, Ramzy; Frésard, Raymond; Eyert, Volker; Hébert, Sylvie; Maignan, Antoine

2017-12-01

The electronic transport properties of the delafossite oxides ? are usually understood in terms of two well-separated entities, namely the triangular ? and (? layers. Here, we review several cases among this extensive family of materials where the transport depends on the interlayer coupling and displays unconventional properties. We review the doped thermoelectrics based on ? and ?, which show a high-temperature recovery of Fermi-liquid transport exponents, as well as the highly anisotropic metals ?, ?, and ?, where the sheer simplicity of the Fermi surface leads to unconventional transport. We present some of the theoretical tools that have been used to investigate these transport properties and review what can and cannot be learned from the extensive set of electronic structure calculations that have been performed.

Electronic and Ionic Conductors from Ordered Microporous Materials

Energy Technology Data Exchange (ETDEWEB)

Dincă, Mircea [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

2017-10-30

The proposed work aimed to establish metal-organic frameworks (MOFs) as new classes of high-surface area microporous electronic and ionic conductors. MOFs are crystalline materials with pore sizes ranging from 0.2 to ~ 2 nm (or larger for the latter) defined by inorganic or organic building blocks connected by rigid organic linkers. Myriad applications have been found or proposed for these materials, yet those that require electron transport or conductivity in combination with permanent porosity still lag behind because the vast majority of known frameworks are electrical insulators. Prior to our proposal and subsequent work, there were virtually no studies exploring the possibility of electronic delocalization in these materials. Therefore, our primary goal was to understand and control, at a fundamental level, the electron and ion transport properties of this class of materials, with no specific application proposed, although myriad applications could be envisioned for high surface area conductors. Our goals directly addressed one of the DOE-identified Grand Challenges for Basic Energy Sciences: designing perfect atom- and energy-efficient syntheses of revolutionary new forms of matter with tailored properties. Indeed, the proposed work is entirely synthetic in nature; owing to the molecular nature of the building blocks in MOFs, there is the possibility of unprecedented control over the structure and properties of solid crystalline matter. The goals also tangentially addressed the Grand Challenge of controlling materials processes at the level of electrons: the scope of our program is to create new materials where charges (electrons and/or ions) move according to predefined pathways.

Bifunctional electroluminescent and photovoltaic devices using bathocuproine as electron-transporting material and an electron acceptor

International Nuclear Information System (INIS)

Chen, L.L.; Li, W.L.; Li, M.T.; Chu, B.

2007-01-01

Electroluminescence (EL) devices, using 4, 4',4''-tris (2-methylphenyl- phenylamino) triphenylamine (m-MTDATA) as hole-transporting material and bathocuproine (BCP) as an electron-transporting material, were fabricated, which emitted bright green light peaked at 520 nm instead of the emission of m-MTDATA or BCP. It was attributed to the exciplex formation and emission at the interface of m-MTDATA and BCP. EL performance was significantly enhanced by a thin mixed layer (5 nm) of m-MTDATA and BCP inserted between the two organic layers of the original m-MTDATA/BCP bilayer device. The trilayer device showed maximum luminance of 1,205 cd/m 2 at 8 V. At a luminance of 100 cd/m 2 , the power efficiency is 1.64 cd/A. Commission International De L'Eclairoge (CIE) color coordinates of the output spectrum of the devices at 8 V are x=0.244 and y=0.464. These devices also showed photovoltaic (PV) properties, which were sensitive to UV light. The PV diode exhibits high open-circuit voltage (V oc ) of 2.10 V under illumination of 365 nm UV light with 2 mW/cm 2 . And the short-circuit current (I sc ) of 92.5x10 -6 A/cm 2 , fill factor (FF) of 0.30 and power conversion efficiency (η e ) of 2.91% are respectively achieved. It is considered that strong exciplex emission in an EL device is a good indicator of efficient charge transfer at the organic interface, which is a basic requirement for good PV performance. Both the bilayer and trilayer devices showed EL and PV properties, suggesting their potential use as multifunction devices

Study of Electron Transport and Amplification in Diamond

Energy Technology Data Exchange (ETDEWEB)

Ben-Zvi, Ilan [Stony Brook Univ., NY (United States); Muller, Erik [Stony Brook Univ., NY (United States)

2015-01-05

The development of the Diamond Amplified Photocathode (DAP) has produced significant results under our previous HEP funded efforts both on the fabrication of working devices and the understanding of the underlying physics governing its performance. The results presented here substantiate the use of diamond as both a secondary electron amplifier for high-brightness, high-average-current electron sources and as a photon and particle detector in harsh radiation environments. Very high average current densities (>10A/cm2) have been transported through diamond material. The transport has been measured as a function of incident photon energy and found to be in good agreement with theoretical models. Measurements of the charge transport for photon energies near the carbon K-edge (290 eV for sp3 bonded carbon) have provided insight into carrier loss due to diffusion; modeling of this aspect of charge transport is underway. The response of diamond to nanosecond x-ray pulses has been measured; in this regime the charge transport is as expected. Electron emission from hydrogenated diamond has been measured using both electron and x-ray generated carriers; a gain of 178 has been observed for electron-generated carriers. The energy spectrum of the emitted electrons has been measured, providing insight into the electron affinity and ultimately the thermal emittance. The origin of charge trapping in diamond has been investigated for both bulk and surface trapping

Enhanced bulk conductivity and bipolar transport in mixtures of MoOx and organic hole transport materials

International Nuclear Information System (INIS)

Tian, Baolin; Ban, Dayan; Aziz, Hany

2013-01-01

We study the conductivity of thin films of molybdenum oxide (MoO x ) mixed with an organic hole transport material, such as N,N′-bis(naphthalen-1-yl)-N,N′-bis (phenyl)benzidine or 4′,4″-tri(N-carbazolyl)triphenylamine, in lateral test devices. Contrary to previous reports, the conductivity of the mixture is found to exceed that of neat MoO x , exhibiting ∼ 5 orders of magnitude higher conductivity in comparison to the neat films. Studies also show that the mixing enhances both hole and electron transport. The higher conductivity may be attributed to a higher concentration of “free” carriers in the mixture, as a result of the formation of a charge transfer complex between the MoO x and the hole transport material. The findings shed light on the potential of hybrid composites of inorganic and organic materials in realizing enhanced conductivity. - Highlights: • We investigate the conductivity of mixtures of MoO x and hole transport material (HTM). • Materials are studied in lateral devices instead of conventional vertical devices. • Mixing MoO x with HTM brings > 5 orders of magnitude increase in bulk conductivity. • The mixture of MoO x and HTM enhances both hole and electron transport

Materials Meets Concepts in Molecule-Based Electronics

KAUST Repository

Ortmann, Frank; Radke, K. Sebastian; Gü nther, Alrun; Kasemann, Daniel; Leo, Karl; Cuniberti, Gianaurelio

2014-01-01

In this contribution, molecular materials are highlighted as an important topic in the diverse field of condensed matter physics, with focus on their particular electronic and transport properties. A better understanding of their performance

Carbon materials for enhancing charge transport in the advancements of perovskite solar cells

Science.gov (United States)

Hu, Ruiyuan; Chu, Liang; Zhang, Jian; Li, Xing'ao; Huang, Wei

2017-09-01

Organic-inorganic halide perovskite solar cells (PSCs) have become a new favorite in the photovoltaic field, due to the boosted efficiency up to 22.1%. Despite a flow of achievements, there are certain challenges to simultaneously meet high efficiency, large scale, low cost and high stability. Due to the low cost, extensive sources, high electrical conductivity and chemical stability, carbon materials have made undeniable contributions to play positive roles in developing PSCs. Carbon materials not only have the favorable conductivity but also bipolar advantage, which can transfer both electrons and holes. In this review, we will discuss how the carbon materials transfer charge or accelerate charge transport by incorporation in PSCs. Carbon materials can replace transparent conductive oxide layers, and enhance electron transport in electron transport layers. Moreover, carbon materials with continuous structure, especially carbon nanotubes and graphene, can provide direct charge transport channel that make them suitable additives or even substitutes in hole transport layers. Especially, the successful application of carbon materials as counter electrodes makes the devices full-printable, low temperature and high stability. Finally, a brief outlook is provided on the future development of carbon materials for PSCs, which are expected to devote more contributions in the future photovoltaic market.

Bifunctional electroluminescent and photovoltaic devices using bathocuproine as electron-transporting material and an electron acceptor

Energy Technology Data Exchange (ETDEWEB)

Chen, L.L. [Key Laboratory of the Excited States Process, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033 (China); Graduate School of the Chinese Academy of Sciences, Beijing, 100039 (China); Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun, 130024 (China); Li, W.L. [Key Laboratory of the Excited States Process, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033 (China)]. E-mail: wllioel@yahoo.com.cn; Li, M.T. [Key Laboratory of the Excited States Process, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033 (China); Graduate School of the Chinese Academy of Sciences, Beijing, 100039 (China); Chu, B. [Key Laboratory of the Excited States Process, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033 (China)

2007-01-15

Electroluminescence (EL) devices, using 4, 4',4''-tris (2-methylphenyl- phenylamino) triphenylamine (m-MTDATA) as hole-transporting material and bathocuproine (BCP) as an electron-transporting material, were fabricated, which emitted bright green light peaked at 520 nm instead of the emission of m-MTDATA or BCP. It was attributed to the exciplex formation and emission at the interface of m-MTDATA and BCP. EL performance was significantly enhanced by a thin mixed layer (5 nm) of m-MTDATA and BCP inserted between the two organic layers of the original m-MTDATA/BCP bilayer device. The trilayer device showed maximum luminance of 1,205 cd/m{sup 2} at 8 V. At a luminance of 100 cd/m{sup 2}, the power efficiency is 1.64 cd/A. Commission International De L'Eclairoge (CIE) color coordinates of the output spectrum of the devices at 8 V are x=0.244 and y=0.464. These devices also showed photovoltaic (PV) properties, which were sensitive to UV light. The PV diode exhibits high open-circuit voltage (V {sub oc}) of 2.10 V under illumination of 365 nm UV light with 2 mW/cm{sup 2}. And the short-circuit current (I {sub sc}) of 92.5x10{sup -6} A/cm{sup 2}, fill factor (FF) of 0.30 and power conversion efficiency ({eta} {sub e}) of 2.91% are respectively achieved. It is considered that strong exciplex emission in an EL device is a good indicator of efficient charge transfer at the organic interface, which is a basic requirement for good PV performance. Both the bilayer and trilayer devices showed EL and PV properties, suggesting their potential use as multifunction devices.

Finger-gate manipulated quantum transport in Dirac materials

International Nuclear Information System (INIS)

Kleftogiannis, Ioannis; Cheng, Shun-Jen; Tang, Chi-Shung

2015-01-01

We investigate the quantum transport properties of multichannel nanoribbons made of materials described by the Dirac equation, under an in-plane magnetic field. In the low energy regime, positive and negative finger-gate potentials allow the electrons to make intra-subband transitions via hole-like or electron-like quasibound states (QBS), respectively, resulting in dips in the conductance. In the high energy regime, double dip structures in the conductance are found, attributed to spin-flip or spin-nonflip inter-subband transitions through the QBSs. Inverting the finger-gate polarity offers the possibility to manipulate the spin polarized electronic transport to achieve a controlled spin-switch. (paper)

Parallelizing an electron transport Monte Carlo simulator (MOCASIN 2.0)

International Nuclear Information System (INIS)

Schwetman, H.; Burdick, S.

1988-01-01

Electron transport simulators are tools for studying electrical properties of semiconducting materials and devices. As demands for modeling more complex devices and new materials have emerged, so have demands for more processing power. This paper documents a project to convert an electron transport simulator (MOCASIN 2.0) to a parallel processing environment. In addition to describing the conversion, the paper presents PPL, a parallel programming version of C running on a Sequent multiprocessor system. In timing tests, models that simulated the movement of 2,000 particles for 100 time steps were executed on ten processors, with a parallel efficiency of over 97%

Electronic transport in amorphous phase-change materials

International Nuclear Information System (INIS)

Luckas, Jennifer Maria

2012-01-01

Phase change materials combine a pronounced contrast in resistivity and reflectivity between their disordered amorphous and ordered crystalline state with very fast crystallization kinetics. Due to this exceptional combination of properties phase-change materials find broad application in non-volatile optical memories such as CD, DVD or Bluray Disc. Furthermore, this class of materials demonstrates remarkable electrical transport phenomena in their disordered state, which have shown to be crucial for their application in electronic storage devices. The threshold switching phenomenon denotes the sudden decrease in resistivity beyond a critical electrical threshold field. The threshold switching phenomenon facilitates the phase transitions at practical small voltages. Below this threshold the amorphous state resistivity is thermally activated and is observed to increase with time. This effect known as resistance drift seriously hampers the development of multi-level storage devices. Hence, understanding the physical origins of threshold switching and resistance drift phenomena is crucial to improve non-volatile phase-change memories. Even though both phenomena are often attributed to localized defect states in the band gap, the defect state density in amorphous phase-change materials has remained poorly studied. Starting from a brief introduction of the physics of phase-change materials this thesis summarizes the most important models behind electrical switching and resistance drift with the aim to discuss the role of localized defect states. The centerpiece of this thesis is the investigation of defects state densities in different amorphous phase-change materials and electrical switching chalcogenides. On the basis of Modulated Photo Current (MPC) Experiments and Photothermal Deflection Spectroscopy, a sophisticated band model for the disordered phase of the binary phase-change alloy GeTe has been developed. By this direct experimental approach the band-model for a

Electronic transport in amorphous phase-change materials

Energy Technology Data Exchange (ETDEWEB)

Luckas, Jennifer Maria

2012-09-14

Phase change materials combine a pronounced contrast in resistivity and reflectivity between their disordered amorphous and ordered crystalline state with very fast crystallization kinetics. Due to this exceptional combination of properties phase-change materials find broad application in non-volatile optical memories such as CD, DVD or Bluray Disc. Furthermore, this class of materials demonstrates remarkable electrical transport phenomena in their disordered state, which have shown to be crucial for their application in electronic storage devices. The threshold switching phenomenon denotes the sudden decrease in resistivity beyond a critical electrical threshold field. The threshold switching phenomenon facilitates the phase transitions at practical small voltages. Below this threshold the amorphous state resistivity is thermally activated and is observed to increase with time. This effect known as resistance drift seriously hampers the development of multi-level storage devices. Hence, understanding the physical origins of threshold switching and resistance drift phenomena is crucial to improve non-volatile phase-change memories. Even though both phenomena are often attributed to localized defect states in the band gap, the defect state density in amorphous phase-change materials has remained poorly studied. Starting from a brief introduction of the physics of phase-change materials this thesis summarizes the most important models behind electrical switching and resistance drift with the aim to discuss the role of localized defect states. The centerpiece of this thesis is the investigation of defects state densities in different amorphous phase-change materials and electrical switching chalcogenides. On the basis of Modulated Photo Current (MPC) Experiments and Photothermal Deflection Spectroscopy, a sophisticated band model for the disordered phase of the binary phase-change alloy GeTe has been developed. By this direct experimental approach the band-model for a

Electron Transport Properties of Ge nanowires

Science.gov (United States)

Hanrath, Tobias; Khondaker, Saiful I.; Yao, Zhen; Korgel, Brian A.

2003-03-01

Electron Transport Properties of Ge nanowires Tobias Hanrath*, Saiful I. Khondaker, Zhen Yao, Brian A. Korgel* *Dept. of Chemical Engineering, Dept. of Physics, Texas Materials Institute, and Center for Nano- and Molecular Science and Technology University of Texas at Austin, Austin, Texas 78712-1062 e-mail: korgel@mail.che.utexas.edu Germanium (Ge) nanowires with diameters ranging from 6 to 50 nm and several micrometer in length were grown via a supercritical fluid-liquid-solid synthesis. Parallel electron energy loss spectroscopy (PEELS) was employed to study the band structure and electron density in the Ge nanowires. The observed increase in plasmon peak energy and peak width with decreasing nanowire diameter is attributed to quantum confinement effects. For electrical characterization, Ge nanowires were deposited onto a patterned Si/SiO2 substrate. E-beam lithography was then used to form electrode contacts to individual nanowires. The influence of nanowire diameter, surface chemistry and crystallographic defects on electron transport properties were investigated and the comparison of Ge nanowire conductivity with respect to bulk, intrinsic Ge will be presented.

Phenomenological studies of electron-beam transport in wire-plasma channels

International Nuclear Information System (INIS)

Lockwood, G.J.; Beezhold, W.

1980-01-01

Multiple electron-beam transport in air through plasma channels is an important method for delivering many intense beams to a bremsstrahlung converter system. This paper reports work intended to optimize this transport technique with emphasis on transport through curved channels and on transport efficiencies. Curved-channel transport allows accelerators such as Sandia's PROTO II and PBFA I facilities to be used as flash x-ray sources for weapon effects simulation without reconfiguring the diodes or developing advanced converters. The formation mechanisms of wire-initiated plasma channels in air were examined and the subsequent transport efficiencies of relativistic electron beams through various-length straight and curved plasma channels were determined. Electron transport efficiency through a channel was measured to be 80 to 100% of a zero length channel for 40 cm long straight channels and for curved channels which re-directed the electron beam through an angle of 90 0 . Studies of simultaneous e-beam transport along two curved channels closely spaced at the converter showed that transport efficiency remained at 80 to 100%. However, it was observed that the two e-beams were displaced towards each other. Transport efficiency was observed to depend only weakly on parameters such as wire material, wire length and shape, diode anode aperture, e-beam injection time, and wire-channel applied voltage. For off-center injection conditions the electron beam strongly perturbed the plasma channel in periodic or regularly spaced patterns even though the total energy lost by the electron beam remained small. Plasma-channel transport, when all experimental parameters have been optimized for maximum transport efficiency, is a workable method for directing electron beams to a converter target

Surface electronic transport measurements: A micro multi-point probe approach

DEFF Research Database (Denmark)

Barreto, Lucas

2014-01-01

This work is mostly focused on the study of electronic transport properties of two-dimensional materials, in particular graphene and topological insulators. To study these, we have improved a unique micro multi-point probe instrument used to perform transport measurements. Not only the experimental...... quantities are extracted, such as conductivity, carrier density and carrier mobility. • A method to insulate electrically epitaxial graphene grown on metals, based on a stepwise intercalation methodology, is developed and transport measurements are performed in order to test the insulation. • We show...... a direct measurement of the surface electronic transport on a bulk topological insulator. The surface state conductivity and mobility are obtained. Apart from transport properties, we also investigate the atomic structure of the Bi2Se3(111) surface via surface x-ray diraction and low-energy electron...

Transport of radioactive materials

International Nuclear Information System (INIS)

2013-01-01

This ninth chapter presents de CNEN-NE--5.01 norm 'Transport of radioactive material'; the specifications of the radioactive materials for transport; the tests of the packages; the requests for controlling the transport and the responsibilities during the transport of radioactive material

Paleoclassical electron heat transport

International Nuclear Information System (INIS)

Callen, J.D.

2005-01-01

Radial electron heat transport in low collisionality, magnetically-confined toroidal plasmas is shown to result from paleoclassical Coulomb collision processes (parallel electron heat conduction and magnetic field diffusion). In such plasmas the electron temperature equilibrates along magnetic field lines a long length L, which is the minimum of the electron collision length and a maximum effective half length of helical field lines. Thus, the diffusing field lines induce a radial electron heat diffusivity M ≅ L/(πR 0q ) ∼ 10 >> 1 times the magnetic field diffusivity η/μ 0 ≅ ν e (c/ω p ) 2 . The paleoclassical electron heat flux model provides interpretations for many features of 'anomalous' electron heat transport: magnitude and radial profile of electron heat diffusivity (in tokamaks, STs, and RFPs), Alcator scaling in high density plasmas, transport barriers around low order rational surfaces and near a separatrix, and a natural heat pinch (or minimum temperature gradient) heat flux form. (author)

Advanced Electron Microscopy in Materials Physics

International Nuclear Information System (INIS)

Zhu, Y.; Jarausch, K.

2009-01-01

Aberration correction has opened a new frontier in electron microscopy by overcoming the limitations of conventional round lenses, providing sub-angstrom-sized probes and extending information limits. The imaging and analytical performance of these corrector-equipped microscopes affords an unprecedented opportunity to study structure-property relationships of matter at the atomic scale. This new generation of microscopes is able to retrieve high-quality structural information comparable to neutron and synchrotron x-ray experiments, but with local atomic resolution. These advances in instrumentation are accelerating the research and development of various functional materials ranging from those for energy generation, conversion, transportation and storage to those for catalysis and nano-device applications. The dramatic improvements in electron-beam illumination and detection also present a host of new challenges for the interpretation and optimization of experiments. During 7-9 November 2007, a workshop, entitled 'Aberration Corrected Electron Microscopy in Material Physics', was convened at the Center for Functional Nanomaterials, Brookhaven National Laboratories (BNL) to address these opportunities and challenges. The workshop was co-sponsored by Hitachi High Technologies, a leader in electron microscopy instrumentation, and BNL's Institute of Advanced Electron Microscopy, a leader in materials physics research using electron microscopy. The workshop featured presentations by internationally prominent scientists working at the frontiers of electron microscopy, both on developing instrumentation and applying it in materials physics. The meeting, structured to stimulate scientific exchanges and explore new capabilities, brought together ∼100 people from over 10 countries. This special issue complies many of the advances in instrument performance and materials physics reported by the invited speakers and attendees at the workshop.

First-Principles Calculations of Electronic, Optical, and Transport Properties of Materials for Energy Applications

Science.gov (United States)

Shi, Guangsha

theoretical upper limit of the figure of merit. I also determined the electronic structures and thermoelectric properties of Mg2Si, Mg2Ge, and Mg2Sn, a family of Earth-abundant thermoelectric compounds. I uncovered the importance of quasiparticle corrections and the proper treatment of pseudopotentials in the determination of the band gaps and the thermoelectric transport properties at high temperatures. The methods and codes I developed in my research form a general predictive toolbox for the design and optimization of the functional properties of materials for energy applications.

Improved electron transport layer

DEFF Research Database (Denmark)

2012-01-01

The present invention provides: a method of preparing a coating ink for forming a zinc oxide electron transport layer, comprising mixing zinc acetate and a wetting agent in water or methanol; a coating ink comprising zinc acetate and a wetting agent in aqueous solution or methanolic solution......; a method of preparing a zinc oxide electron transporting layer, which method comprises: i) coating a substrate with the coating ink of the present invention to form a film; ii) drying the film; and iii) heating the dry film to convert the zinc acetate substantially to ZnO; a method of preparing an organic...... photovoltaic device or an organic LED having a zinc oxide electron transport layer, the method comprising, in this order: a) providing a substrate bearing a first electrode layer; b) forming an electron transport layer according to the following method: i) coating a coating ink comprising an ink according...

Monte Carlo calculations of electron diffusion in materials

International Nuclear Information System (INIS)

Schroeder, U.G.

1976-01-01

By means of simulated experiments, various transport problems for 10 Mev electrons are investigated. For this purpose, a special Monte-Carlo programme is developed, and with this programme calculations are made for several material arrangements. (orig./LN) [de

First Principles Calculations of Electronic Excitations in 2D Materials

DEFF Research Database (Denmark)

Rasmussen, Filip Anselm

electronic transport, optical and chemical properties. On the other hand it has shown to be a great starting point for a systematic pertubation theory approach to obtain the so-called quasiparticle spectrum. In the GW approximation one considers the considers the potential from a charged excitation...... as if it is being screened by the electrons in the material. This method has been very successful for calculating quasiparticle energies of bulk materials but results have been more varying for 2D materials. The reason is that the 2D confined electrons are less able to screen the added charge and some...

Correlation of electron transport and photocatalysis of nanocrystalline clusters studied by Monte-Carlo continuity random walking.

Science.gov (United States)

Liu, Baoshun; Li, Ziqiang; Zhao, Xiujian

2015-02-21

In this research, Monte-Carlo Continuity Random Walking (MC-RW) model was used to study the relation between electron transport and photocatalysis of nano-crystalline (nc) clusters. The effects of defect energy disorder, spatial disorder of material structure, electron density, and interfacial transfer/recombination on the electron transport and the photocatalysis were studied. Photocatalytic activity is defined as 1/τ from a statistical viewpoint with τ being the electron average lifetime. Based on the MC-RW simulation, a clear physical and chemical "picture" was given for the photocatalytic kinetic analysis of nc-clusters. It is shown that the increase of defect energy disorder and material spatial structural disorder, such as the decrease of defect trap number, the increase of crystallinity, the increase of particle size, and the increase of inter-particle connection, can enhance photocatalytic activity through increasing electron transport ability. The increase of electron density increases the electron Fermi level, which decreases the activation energy for electron de-trapping from traps to extending states, and correspondingly increases electron transport ability and photocatalytic activity. Reducing recombination of electrons and holes can increase electron transport through the increase of electron density and then increases the photocatalytic activity. In addition to the electron transport, the increase of probability for electrons to undergo photocatalysis can increase photocatalytic activity through the increase of the electron interfacial transfer speed.

Electron transport effects in ion induced electron emission

Energy Technology Data Exchange (ETDEWEB)

Dubus, A. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. FD Roosevelt, B-1050 Brussels (Belgium)]. E-mail: adubus@ulb.ac.be; Pauly, N. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. FD Roosevelt, B-1050 Brussels (Belgium); Roesler, M. [Karl-Pokern-Str. 12, D-12587 Berlin (Germany)

2007-03-15

Ion induced electron emission (IIEE) is usually described as a three-step process, i.e. electron excitation by the incident projectile, electron transport (and multiplication) and electron escape through the potential barrier at the surface. In many cases, the first step of the process has been carefully described. The second step of the process, i.e. electron transport and multiplication, has often been treated in a very rough way, a simple decreasing exponential law being sometimes used. It is precisely the aim of the present work to show the importance of a correct description of electron transport and multiplication in a theoretical calculation of IIEE. A short overview of the electron transport models developed for IIEE is given in this work. The so-called 'Infinite medium slowing-down model' often used in recent works is evaluated by means of Monte Carlo simulations. In particular, the importance of considering correctly the semi-infinite character of the medium and the boundary condition at the vacuum-medium interface is discussed. Quantities like the electron escape depth are also briefly discussed. This evaluation has been performed in the particular case of protons (25keV

Transport of Radioactive Materials

International Nuclear Information System (INIS)

2001-01-01

This address overviews the following aspects: concepts on transport of radioactive materials, quantities used to limit the transport, packages, types of packages, labeling, index transport calculation, tags, labeling, vehicle's requirements and documents required to authorize transportation. These requirements are considered in the regulation of transport of radioactive material that is in drafting step

Radioactive materials transport

International Nuclear Information System (INIS)

Talbi, B.

1996-01-01

The development of peaceful applications of nuclear energy results in the increase of transport operations of radioactive materials. Therefore strong regulations on transport of radioactive materials turns out to be a necessity in Tunisia. This report presents the different axes of regulations which include the means of transport involved, the radiation protection of the carriers, the technical criteria of security in transport, the emergency measures in case of accidents and penalties in case of infringement. (TEC). 12 refs., 1 fig

Multiscale Modelling of Electronic and Thermal Transport : Thermoelectrics, Turbostratic 2D Materials and Diamond/c-BN HEMT

Science.gov (United States)

Narendra, Namita

Multiscale modelling has become necessary with the advent of low dimensional devices as well as use of heterostructures which necessitates atomistic treatment of the interfaces. Multiscale methodology is able to capture the quantum mechanical atomistic details while enabling the simulation of micro-scale structures at the same time. In this thesis, multiscale modelling has been applied to study transport in thermoelectrics, turbostratic 2D MoS2/WS 2 heterostructure and diamond/c-BN high mobility electron transistor (HEMT). The possibility of enhanced thermoelectric properties through nanostructuring is investigated theoretically in a p-type Bi2Te3/Sb 2Te3 heterostructure. A multi-scale modeling approach is adopted to account for the atomistic characteristics of the interface as well as the carrier/phonon transport properties in the larger scales. The calculations clearly illustrate the desired impact of carrier energy filtering at the potential barrier by locally boosting the power factor over a sizable distance in the well region. Further, the phonon transport analysis illustrates a considerable reduction in the thermal conductivity at the heterointerface. Both effects are expected to provide an effective means to engineer higher zT in this material system. Next, power factor enhancement through resonant doping is explored in Bi2Te3 based on a detailed first-principles study. Of the dopant atoms investigated, it is found that the formation of resonant states may be achieved with In, Po and Na, leading potentially to significant increase in the thermoelectric efficiency at room temperature. While doping with Po forms twin resonant state peaks in the valence and conduction bands, the incorporation of Na or In results in the resonant states close to the valence band edge. Further analysis reveals the origin of these resonant states. Transport calculations are also carried out to estimate the anticipated level of enhancement. Next, in-plane and cross-plane transport

Electronic Interactions of n-Doped Perylene Diimide Groups Appended to Polynorbornene Chains: Implications for Electron Transport in Organic Electronics.

Science.gov (United States)

Nguyen, Minh T; Biberdorf, Joshua D; Holliday, Bradley J; Jones, Richard A

2017-11-01

A polymer consisting of a polynorbornene backbone with perylene diimide (PDI) pendant groups on each monomeric unit is synthesized via ring opening metathesis polymerization. The PDI pendant groups along the polymer backbone, studied by UV-vis absorption, fluorescence emission, and electron paramagnetic resonance spectroscopy in addition to electrochemical methods, show evidence of molecular aggregation and corresponding electronic coupling with neighboring groups, which forms pathways for efficient electron transport from one group to another in a specific reduced form. When n-doped, the title polymer shows redox conductivity of 5.4 × 10 -3 S cm -1 , comparable with crystalline PDI materials, and is therefore a promising material for use in organic electronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Coupled electron-photon radiation transport

International Nuclear Information System (INIS)

Lorence, L.; Kensek, R.P.; Valdez, G.D.; Drumm, C.R.; Fan, W.C.; Powell, J.L.

2000-01-01

Massively-parallel computers allow detailed 3D radiation transport simulations to be performed to analyze the response of complex systems to radiation. This has been recently been demonstrated with the coupled electron-photon Monte Carlo code, ITS. To enable such calculations, the combinatorial geometry capability of ITS was improved. For greater geometrical flexibility, a version of ITS is under development that can track particles in CAD geometries. Deterministic radiation transport codes that utilize an unstructured spatial mesh are also being devised. For electron transport, the authors are investigating second-order forms of the transport equations which, when discretized, yield symmetric positive definite matrices. A novel parallelization strategy, simultaneously solving for spatial and angular unknowns, has been applied to the even- and odd-parity forms of the transport equation on a 2D unstructured spatial mesh. Another second-order form, the self-adjoint angular flux transport equation, also shows promise for electron transport

Visualizing electron dynamics in organic materials: Charge transport through molecules and angular resolved photoemission

Science.gov (United States)

Kümmel, Stephan

Being able to visualize the dynamics of electrons in organic materials is a fascinating perspective. Simulations based on time-dependent density functional theory allow to realize this hope, as they visualize the flow of charge through molecular structures in real-space and real-time. We here present results on two fundamental processes: Photoemission from organic semiconductor molecules and charge transport through molecular structures. In the first part we demonstrate that angular resolved photoemission intensities - from both theory and experiment - can often be interpreted as a visualization of molecular orbitals. However, counter-intuitive quantum-mechanical electron dynamics such as emission perpendicular to the direction of the electrical field can substantially alter the picture, adding surprising features to the molecular orbital interpretation. In a second study we calculate the flow of charge through conjugated molecules. The calculations show in real time how breaks in the conjugation can lead to a local buildup of charge and the formation of local electrical dipoles. These can interact with neighboring molecular chains. As a consequence, collections of ''molecular electrical wires'' can show distinctly different characteristics than ''classical electrical wires''. German Science Foundation GRK 1640.

Polymers Containing Diphenylvinyl-Substituted Indole Rings as Charge-Transporting Materials for OLEDs

Science.gov (United States)

Grigalevicius, S.; Zostautiene, R.; Sipaviciute, D.; Stulpinaite, B.; Volyniuk, D.; Grazulevicius, J. V.; Liu, L.; Xie, Z.; Zhang, B.

2016-02-01

Monomers and polymers containing electronically isolated diphenylvinyl-substituted indole rings were synthesized and characterized by nuclear magnetic resonance (NMR) and mass spectroscopies as well as by gel permeation chromatography. The polymers represent amorphous materials with glass transition temperatures of 91-109°C and thermal decomposition starting above 307°C. Electron photoemission spectra of thin films of the synthesized polymers revealed ionization potentials of 5.54-5.58 eV. The synthesized polymers were tested as hole-transporting materials in simple electroluminescent organic light-emitting diode (OLED) devices with tris(quinolin-8-olato)aluminium (Alq3) as an emitter as well as an electron-transporting layer. A green OLED device containing a hole-transporting layer of poly[1-(2,3-epithiopropyl)-2-methyl-3-(2,2-diphenylvinyl)índole] exhibited the best overall performance with a driving voltage of 4.0 V, maximum photometric efficiency of 2.8 cd/A and maximum brightness of about 4200 cd/m2.

Transport of radioactive materials

International Nuclear Information System (INIS)

1988-07-01

The norm which establishes the requirements of radiation protection and safety related to the transport of radioactive materials, aiming to keep a suitable control level of eventual exposure of personnels, materials and environment of ionizing radiation, including: specifications on radioactive materials for transport, selection of package type; specification of requirements of the design and assays of acceptance of packages; disposal related to the transport; and liability and administrative requirements, are presented. This norm is applied to: truckage, water carriage and air service; design, fabrication, assays and mantenaince of packages; preparation, despatching, handling, loading storage in transition and reception in the ultimate storage of packages; and transport of void packages which have been contained radioactive materials. (M.C.K.) [pt

Nonlinear Ballistic Transport in an Atomically Thin Material.

Science.gov (United States)

Boland, Mathias J; Sundararajan, Abhishek; Farrokhi, M Javad; Strachan, Douglas R

2016-01-26

Ultrashort devices that incorporate atomically thin components have the potential to be the smallest electronics. Such extremely scaled atomically thin devices are expected to show ballistic nonlinear behavior that could make them tremendously useful for ultrafast applications. While nonlinear diffusive electron transport has been widely reported, clear evidence for intrinsic nonlinear ballistic transport in the growing array of atomically thin conductors has so far been elusive. Here we report nonlinear electron transport of an ultrashort single-layer graphene channel that shows quantitative agreement with intrinsic ballistic transport. This behavior is shown to be distinctly different than that observed in similarly prepared ultrashort devices consisting, instead, of bilayer graphene channels. These results suggest that the addition of only one extra layer of an atomically thin material can make a significant impact on the nonlinear ballistic behavior of ultrashort devices, which is possibly due to the very different chiral tunneling of their charge carriers. The fact that we observe the nonlinear ballistic response at room temperature, with zero applied magnetic field, in non-ultrahigh vacuum conditions and directly on a readily accessible oxide substrate makes the nanogap technology we utilize of great potential for achieving extremely scaled high-speed atomically thin devices.

Morphologically controlled ZnO nanostructures as electron transport materials in polymer-based organic solar cells

International Nuclear Information System (INIS)

Choi, Kyu-Chae; Lee, Eun-Jin; Baek, Youn-Kyoung; Lim, Dong-Chan; Kang, Yong-Cheol; Kim, Yang-Do; Kim, Ki Hyun; Kim, Jae Pil; Kim, Young-Kuk

2015-01-01

Highlights: • Enhanced efficiency of solar cells using ZnO nanocrystals for charge transport. • Morphology of the charge transport layer is controlled. • Mixture of nanoparticles and nanorods are advantageous for cell efficiency. - ABSTRACT: The morphology of ZnO electron transport layers based on ZnO nanoparticles were modified with incorporation of ZnO nanorods via their co-deposition from mixed colloidal solution of nanoparticles and nanorods. In particular, the short circuit current density and the fill factor of the constructed photovoltaic device were simultaneously improved by applying mixture of ZnO nanoparticles and nanorods. As a result, a large improvement of power conversion efficiency up to 9% for the inverted organic solar cells having a blend of low band gap polymers and fullerene derivative as an active layer was demonstrated with the morphologically controlled ZnO electron transport layer.

Electronic transport properties

International Nuclear Information System (INIS)

Young, W.H.

1985-01-01

The theory of the electron transport properties of liquid alkali metals is described. Conductivity coefficients, Boltzmann theory, Ziman theory, alkali form factors, Ziman theory and alkalis, Faber-Ziman alloy theory, Faber-Ziman theory and alkali-alkali methods, status of Ziman theory, and other transport properties, are all discussed. (UK)

Dossier: transport of radioactive materials

International Nuclear Information System (INIS)

Mignon, H.; Brachet, Y.; Turquet de Beauregard, G.; Mauny, G.; Robine, F.; Plantet, F.; Pestel Lefevre, O.; Hennenhofer, G.; Bonnemains, J.

1997-01-01

This dossier is entirely devoted to the transportation of radioactive and fissile materials of civil use. It comprises 9 papers dealing with: the organization of the control of the radioactive materials transport safety (safety and security aspects, safety regulations, safety analysis and inspection, emergency plans, public information), the technical aspects of the regulation concerning the transport of radioactive materials (elaboration of regulations and IAEA recommendations, risk assessments, defense in depth philosophy and containers, future IAEA recommendations, expertise-research interaction), the qualification of containers (regulations, test facilities), the Transnucleaire company (presentation, activity, containers for spent fuels), the packages of radioactive sources for medical use (flux, qualification, safety and transport), an example of accident during radioactive materials transportation: the Apach train derailment (February 4, 1997), the sea transport of radioactive materials (international maritime organization (OMI), international maritime dangerous goods (IMDG) code, irradiated nuclear fuel (INF) safety rules), the transport of radioactive materials in Germany, and the point of view from an external observer. (J.S.)

Molecular Engineering of Non-Halogenated Solution-Processable Bithiazole based Electron Transport Polymeric Semiconductors

KAUST Repository

Fu, Boyi

2015-04-01

The electron deficiency and trans planar conformation of bithiazole is potentially beneficial for the electron transport performance of organic semiconductors. However, the incorporation of bithiazole into polymers through a facile synthetic strategy remains a challenge. Herein, 2,2’-bithiazole was synthesized in one step and copolymerized with dithienyldiketopyrrolopyrrole to afford poly(dithienyldiketopyrrolopyrrole-bithiazole), PDBTz. PDBTz exhibited electron mobility reaching 0.3 cm2V-1s-1 in organic field-effect transistor (OFET) configuration; this contrasts with a recently discussed isoelectronic conjugated polymer comprising an electron rich bithiophene and dithienyldiketopyrrolopyrrole, which displays merely hole transport characteristics. This inversion of charge carrier transport characteristics confirms the significant potential for bithiazole in the development of electron transport semiconducting materials. Branched 5-decylheptacyl side chains were incorporated into PDBTz to enhance polymer solubility, particularly in non-halogenated, more environmentally compatible solvents. PDBTz cast from a range of non-halogenated solvents exhibited film morphologies and field-effect electron mobility similar to those cast from halogenated solvents.

Molecular Engineering of Non-Halogenated Solution-Processable Bithiazole based Electron Transport Polymeric Semiconductors

KAUST Repository

Fu, Boyi; Wang, Cheng-Yin; Rose, Bradley Daniel; Jiang, Yundi; Chang, Mincheol; Chu, Ping-Hsun; Yuan, Zhibo; Fuentes-Hernandez, Canek; Bernard, Kippelen; Bredas, Jean-Luc; Collard, David M.; Reichmanis, Elsa

2015-01-01

The electron deficiency and trans planar conformation of bithiazole is potentially beneficial for the electron transport performance of organic semiconductors. However, the incorporation of bithiazole into polymers through a facile synthetic strategy remains a challenge. Herein, 2,2’-bithiazole was synthesized in one step and copolymerized with dithienyldiketopyrrolopyrrole to afford poly(dithienyldiketopyrrolopyrrole-bithiazole), PDBTz. PDBTz exhibited electron mobility reaching 0.3 cm2V-1s-1 in organic field-effect transistor (OFET) configuration; this contrasts with a recently discussed isoelectronic conjugated polymer comprising an electron rich bithiophene and dithienyldiketopyrrolopyrrole, which displays merely hole transport characteristics. This inversion of charge carrier transport characteristics confirms the significant potential for bithiazole in the development of electron transport semiconducting materials. Branched 5-decylheptacyl side chains were incorporated into PDBTz to enhance polymer solubility, particularly in non-halogenated, more environmentally compatible solvents. PDBTz cast from a range of non-halogenated solvents exhibited film morphologies and field-effect electron mobility similar to those cast from halogenated solvents.

Mechanisms of electron transport and recombination in ZnO nanostructures for dye-sensitized solar cells.

Science.gov (United States)

Vega-Poot, Alberto G; Macías-Montero, Manuel; Idígoras, Jesus; Borrás, Ana; Barranco, Angel; Gonzalez-Elipe, Agustín R; Lizama-Tzec, Francisco I; Oskam, Gerko; Anta, Juan A

2014-04-14

ZnO is an attractive material for applications in dye-sensitized solar cells and related devices. This material has excellent electron-transport properties in the bulk but its electron diffusion coefficient is much smaller in mesoporous films. In this work the electron-transport properties of two different kinds of dye-sensitized ZnO nanostructures are investigated by small-perturbation electrochemical techniques. For nanoparticulate ZnO photoanodes prepared via a wet-chemistry technique, the diffusion coefficient is found to reproduce the typical behavior predicted by the multiple-trapping and the hopping models, with an exponential increase with respect to the applied bias. In contrast, in ZnO nanostructured thin films of controlled texture and crystallinity prepared via a plasma chemical vapor deposition method, the diffusion coefficient is found to be independent of the electrochemical bias. This observation suggests a different transport mechanism not controlled by trapping and electron accumulation. In spite of the quite different transport features, the recombination kinetics, the electron-collection efficiency and the photoconversion efficiency are very similar for both kinds of photoanodes, an observation that indicates that surface properties rather than electron transport is the main efficiency-determining factor in solar cells based on ZnO nanostructured photoanodes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Modern electronic materials

CERN Document Server

Watkins, John B

2013-01-01

Modern Electronic Materials focuses on the development of electronic components. The book first discusses the history of electronic components, including early developments up to 1900, developments up to World War II, post-war developments, and a comparison of present microelectric techniques. The text takes a look at resistive materials. Topics include resistor requirements, basic properties, evaporated film resistors, thick film resistors, and special resistors. The text examines dielectric materials. Considerations include basic properties, evaporated dielectric materials, ceramic dielectri

Quantum transport through 3D Dirac materials

International Nuclear Information System (INIS)

Salehi, M.; Jafari, S.A.

2015-01-01

Bismuth and its alloys provide a paradigm to realize three dimensional materials whose low-energy effective theory is given by Dirac equation in 3+1 dimensions. We study the quantum transport properties of three dimensional Dirac materials within the framework of Landauer–Büttiker formalism. Charge carriers in normal metal satisfying the Schrödinger equation, can be split into four-component with appropriate matching conditions at the boundary with the three dimensional Dirac material (3DDM). We calculate the conductance and the Fano factor of an interface separating 3DDM from a normal metal, as well as the conductance through a slab of 3DDM. Under certain circumstances the 3DDM appears transparent to electrons hitting the 3DDM. We find that electrons hitting the metal-3DDM interface from metallic side can enter 3DDM in a reversed spin state as soon as their angle of incidence deviates from the direction perpendicular to interface. However the presence of a second interface completely cancels this effect

Quantum transport through 3D Dirac materials

Energy Technology Data Exchange (ETDEWEB)

Salehi, M. [Department of Physics, Sharif University of Technology, Tehran 11155-9161 (Iran, Islamic Republic of); Jafari, S.A., E-mail: jafari@physics.sharif.edu [Department of Physics, Sharif University of Technology, Tehran 11155-9161 (Iran, Islamic Republic of); Center of Excellence for Complex Systems and Condensed Matter (CSCM), Sharif University of Technology, Tehran 1458889694 (Iran, Islamic Republic of)

2015-08-15

Bismuth and its alloys provide a paradigm to realize three dimensional materials whose low-energy effective theory is given by Dirac equation in 3+1 dimensions. We study the quantum transport properties of three dimensional Dirac materials within the framework of Landauer–Büttiker formalism. Charge carriers in normal metal satisfying the Schrödinger equation, can be split into four-component with appropriate matching conditions at the boundary with the three dimensional Dirac material (3DDM). We calculate the conductance and the Fano factor of an interface separating 3DDM from a normal metal, as well as the conductance through a slab of 3DDM. Under certain circumstances the 3DDM appears transparent to electrons hitting the 3DDM. We find that electrons hitting the metal-3DDM interface from metallic side can enter 3DDM in a reversed spin state as soon as their angle of incidence deviates from the direction perpendicular to interface. However the presence of a second interface completely cancels this effect.

Magnetic field effects on runaway electron energy deposition in plasma facing materials and components

International Nuclear Information System (INIS)

Niemer, K.A.; Gilligan, J.G.

1992-01-01

This paper reports magnetic field effects on runaway electron energy deposition in plasma facing materials and components is investigated using the Integrated TIGER Series. The Integrated TIGER Series is a set of time-independent coupled electron/photon Monte Carlo transport codes which perform photon and electron transport, with or without macroscopic electric and magnetic fields. A three-dimensional computational model of 100 MeV electrons incident on a graphite block was used to simulate runawayelectrons striking a plasma facing component at the edge of a tokamak. Results show that more energy from runaway electrons will be deposited in a material that is in the presence of a magnetic field than in a material that is in the presence of no field. For low angle incident runaway electrons in a strong magnetic field, the majority of the increased energy deposition is near the material surface with a higher energy density. Electrons which would have been reflected with no field, orbit the magnetic field lines and are redeposited in the material surface, resulting in a substantial increase in surface energy deposition. Based on previous studies, the higher energy deposition and energy density will result in higher temperatures which are expected to cause more damage to a plasma facing component

The safe transport of radioactive materials

CERN Document Server

Gibson, R

1966-01-01

The Safe Transport of Radioactive Materials is a handbook that details the safety guidelines in transporting radioactive materials. The title covers the various regulations and policies, along with the safety measures and procedures of radioactive material transport. The text first details the 1963 version of the IAEA regulation for the safe transport of radioactive materials; the regulation covers the classification of radionuclides for transport purposes and the control of external radiation hazards during the transport of radioactive materials. The next chapter deals with concerns in the im

Radioactive material air transportation; Transporte aereo de material radioativo

Energy Technology Data Exchange (ETDEWEB)

Pader y Terry, Claudio Cosme [Varig Logistica (VARIGLOG), Sao Paulo, SP (Brazil)

2002-07-01

As function of the high aggregated value, safety regulations and the useful life time, the air transportation has been used more regularly because is fast, reliable, and by giving great security to the cargo. Based on the International Atomic Energy Agency (IAEA), the IATA (International Air Transportation Association) has reproduced in his dangerous goods manual (Dangerous Goods Regulations - DGR IATA), the regulation for the radioactive material air transportation. Those documents support this presentation.

Comparison between s - and d -electron mediated transport in a photoswitching dithienylethene molecule using ab initio transport methods

KAUST Repository

Odell, Anders

2011-10-03

The influence of the electrode\\'s Fermi surface on the transport properties of a photoswitching molecule is investigated with state-of-the-art ab initio transport methods. We report results for the conducting properties of the two forms of dithienylethene attached either to Ag or to nonmagnetic Ni leads. The I-V curves of the Ag/dithienylethene/Ag device are found to be very similar to those reported previously for Au. In contrast, when Ni is used as the electrode material the zero-bias transmission coefficient is profoundly different as a result of the role played by the Ni d bands in the bonding between the molecule and the electrodes. Intriguingly, despite these differences the overall conducting properties depend little on the electrode material. We thus conclude that electron transport in dithienylethene is, for the cases studied, mainly governed by the intrinsic electronic structure of the molecule. © 2011 American Physical Society.

Electron and Phonon Transport in Molecular Junctions

DEFF Research Database (Denmark)

Li, Qian

Molecular electronics provide the possibility to investigate electron and phonon transport at the smallest imaginable scale, where quantum effects can be investigated and exploited directly in the design. In this thesis, we study both electron transport and phonon transport in molecular junctions....... The system we are interested in here are π-stacked molecules connected with two semi-infinite leads. π-stacked aromatic rings, connected via π-π electronic coupling, provides a rather soft mechanical bridge while maintaining high electronic conductivity. We investigate electron transport...... transmission at the Fermi energy. We propose and analyze a way of using π   stacking to design molecular junctions to control heat transport. We develop a simple model system to identify optimal parameter regimes and then use density functional theory (DFT) to extract model parameters for a number of specific...

Quantum transport through disordered 1D wires: Conductance via localized and delocalized electrons

International Nuclear Information System (INIS)

Gopar, Víctor A.

2014-01-01

Coherent electronic transport through disordered systems, like quantum wires, is a topic of fundamental and practical interest. In particular, the exponential localization of electron wave functions-Anderson localization-due to the presence of disorder has been widely studied. In fact, Anderson localization, is not an phenomenon exclusive to electrons but it has been observed in microwave and acoustic experiments, photonic materials, cold atoms, etc. Nowadays, many properties of electronic transport of quantum wires have been successfully described within a scaling approach to Anderson localization. On the other hand, anomalous localization or delocalization is, in relation to the Anderson problem, a less studied phenomenon. Although one can find signatures of anomalous localization in very different systems in nature. In the problem of electronic transport, a source of delocalization may come from symmetries present in the system and particular disorder configurations, like the so-called Lévy-type disorder. We have developed a theoretical model to describe the statistical properties of transport when electron wave functions are delocalized. In particular, we show that only two physical parameters determine the complete conductance distribution

Transport regulation for radioactive materials

International Nuclear Information System (INIS)

Ha Vinh Phuong.

1986-01-01

Taking into account the specific dangers associated with the transport of radioactive materials (contamination, irradiation, heat, criticality), IAEA regulations concerning technical specifications and administrative procedures to ward off these dangers are presented. The international agreements related to the land transport, maritime transport and air transport of radioactive materials are also briefly reviewed

Transport of radioactive materials

International Nuclear Information System (INIS)

1991-07-01

The purpose of this Norm is to establish, relating to the TRANSPORT OF RADIOACTIVE MATERIALS, safety and radiological protection requirements to ensure an adequate control level of the eventual exposure of persons, properties and environment to the ionizing radiation comprising: specifications on radioactive materials for transport; package type selection; specification of the package design and acceptance test requirements; arrangements relating to the transport itself; administrative requirements and responsibilities. (author)

Design rules for charge-transport efficient host materials for phosphorescent organic light-emitting diodes.

Science.gov (United States)

May, Falk; Al-Helwi, Mustapha; Baumeier, Björn; Kowalsky, Wolfgang; Fuchs, Evelyn; Lennartz, Christian; Andrienko, Denis

2012-08-22

The use of blue phosphorescent emitters in organic light-emitting diodes (OLEDs) imposes demanding requirements on a host material. Among these are large triplet energies, the alignment of levels with respect to the emitter, the ability to form and sustain amorphous order, material processability, and an adequate charge carrier mobility. A possible design strategy is to choose a π-conjugated core with a high triplet level and to fulfill the other requirements by using suitable substituents. Bulky substituents, however, induce large spatial separations between conjugated cores, can substantially reduce intermolecular electronic couplings, and decrease the charge mobility of the host. In this work we analyze charge transport in amorphous 2,8-bis(triphenylsilyl)dibenzofuran, an electron-transporting material synthesized to serve as a host in deep-blue OLEDs. We show that mesomeric effects delocalize the frontier orbitals over the substituents recovering strong electronic couplings and lowering reorganization energies, especially for electrons, while keeping energetic disorder small. Admittance spectroscopy measurements reveal that the material has indeed a high electron mobility and a small Poole-Frenkel slope, supporting our conclusions. By linking electronic structure, molecular packing, and mobility, we provide a pathway to the rational design of hosts with high charge mobilities.

Highly efficient perovskite solar cells based on a nanostructured WO3-TiO2 core-shell electron transporting material

KAUST Repository

Mahmood, Khalid; Swain, Bhabani Sankar; Kirmani, Ahmad R.; Amassian, Aram

2015-01-01

Until recently, only mesoporous TiO2 and ZnO were successfully demonstrated as electron transport layers (ETL) alongside the reports of ZrO2 and Al2O3 as scaffold materials in organometal halide perovskite solar cells, largely owing to ease of processing and to high power conversion efficiency. In this article, we explore tungsten trioxide (WO3)-based nanostructured and porous ETL materials directly grown hydrothermally with different morphologies such as nanoparticles, nanorods and nanosheet arrays. The nanostructure morphology strongly influences the photocurrent and efficiency in organometal halide perovskite solar cells. We find that the perovskite solar cells based on WO3 nanosheet arrays yield significantly enhanced photovoltaic performance as compared to nanoparticles and nanorod arrays due to good perovskite absorber infiltration in the porous scaffold and more rapid carrier transport. We further demonstrate that treating the WO3 nanostructures with an aqueous solution of TiCl4 reduces charge recombination at the perovskite/WO3 interface, resulting in the highest power conversion efficiency of 11.24% for devices based on WO3 nanosheet arrays. The successful demonstration of alternative ETL materials and nanostructures based on WO3 will open up new opportunities in the development of highly efficient perovskite solar cells. This journal is © The Royal Society of Chemistry 2015.

Ballistic electron transport in mesoscopic samples

International Nuclear Information System (INIS)

Diaconescu, D.

2000-01-01

In the framework of this thesis, the electron transport in the ballistic regime has been studied. Ballistic means that the lateral sample dimensions are smaller than the mean free path of the electrons, i.e. the electrons can travel through the whole device without being scattered. This leads to transport characteristics that differ significantly from the diffusive regime which is realised in most experiments. Making use of samples with high mean free path, features of ballistic transport have been observed on samples with sizes up to 100 μm. The basic device used in ballistic electron transport is the point contact, from which a collimated beam of ballistic electrons can be injected. Such point contacts were realised with focused ion beam (FIB) implantation and the collimating properties were analysed using a two opposite point contact configuration. The typical angular width at half maximum is around 50 , which is comparable with that of point contacts defined by other methods. (orig.)

Radioactive material accidents in the transport

International Nuclear Information System (INIS)

Rodrigues, D.L.; Magalhaes, M.H.; Sanches, M.P.; Sordi, G.M.A.A.

2008-01-01

Transport is an important part of the worldwide nuclear industry and the safety record for nuclear transport across the world is excellent. The increase in the use of radioactive materials in our country requires that these materials be moved from production sites to the end user. Despite the number of packages transported, the number of incidents and accidents in which they are involved is low. In Brazil, do not be records of victims of the radiation as a result of the transport of radioactive materials and either due to the accidents happened during the transports. The absence of victims of the radiation as result of accidents during the transports is a highly significant fact, mainly to consider that annually approximately two hundred a thousand packages containing radioactive material are consigned for transport throughout the country, of which eighty a thousand are for a medical use. This is due to well-founded regulations developed by governmental and intergovernmental organizations and to the professionalism of those in the industry. In this paper, an overview is presented of the activities related to the transport of radioactive material in the state of Sao Paulo. The applicable legislation, the responsibilities and tasks of the competent authorities are discussed. The categories of radioactive materials transported and the packaging requirements for the safe transport of these radioactive materials are also described. It also presents the packages amounts of carried and the accidents occurred during the transport of radioactive materials, in the last five years. The main occurred events are argued, demonstrating that the demanded requirements of security for any transport of radioactive material are enough to guarantee the necessary control of ionizing radiation expositions to transport workers, members of general public and the environment. (author)

Electronic fitness function for screening semiconductors as thermoelectric materials

International Nuclear Information System (INIS)

Xing, Guangzong; Sun, Jifeng; Li, Yuwei; Fan, Xiaofeng

2017-01-01

Here, we introduce a simple but efficient electronic fitness function (EFF) that describes the electronic aspect of the thermoelectric performance. This EFF finds materials that overcome the inverse relationship between σ and S based on the complexity of the electronic structures regardless of specific origin (e.g., isosurface corrugation, valley degeneracy, heavy-light bands mixture, valley anisotropy or reduced dimensionality). This function is well suited for application in high throughput screening. We applied this function to 75 different thermoelectric and potential thermoelectric materials including full- and half-Heuslers, binary semiconductors, and Zintl phases. We find an efficient screening using this transport function. The EFF identifies known high-performance p- and n-type Zintl phases and half-Heuslers. In addition, we find some previously unstudied phases with superior EFF.

Effect of interfaces on electron transport properties of MoS2-Au Contacts

Science.gov (United States)

Aminpour, Maral; Hapala, Prokop; Le, Duy; Jelinek, Pavel; Rahman, Talat S.; Rahman's Group Collaboration; Nanosurf Lab Collaboration

2014-03-01

Single layer MoS2 is a promising material for future electronic devices such as transistors since it has good transport characteristics with mobility greater than 200 cm-1V-1s-1 and on-off current ratios up to 108. However, before MoS2 can become a mainstream electronic material for the semiconductor industry, the design of low resistive metal-semiconductor junctions as contacts of the electronic devices needs to be addressed and studied systematically. We have examined the effect of Au contacts on the electronic transport properties of single layer MoS2 using density functional theory in combination with the non-equilibrium Green's function method. The Schottky barrier between Au contact and MoS2, transmission spectra, and I-V curves will be reported and discussed as a function of MoS2 and Au interfaces of varying geometry. This work is supported in part by the US Department of Energy under grant DE-FG02-07ER15842.

Tuning the Transport Properties of Layered Materials for Thermoelectric Applications using First-Principles Calculations

KAUST Repository

Saeed, Yasir

2014-05-11

Thermoelectric materials can convert waste heat into electric power and thus provide a way to reduce the dependence on fossil fuels. Our aim is to model the underlying materials properties and, in particular, the transport as controlled by electrons and lattice vibrations. The goal is to develop an understanding of the thermoelectric properties of selected materials at a fundamental level. The structural, electronic, optical, and phononic properties are studied in order to tune the transport, focusing on KxRhO2, NaxRhO2, PtSb2 and Bi2Se3. The investigations are based on density functional theory as implemented in the all electron linearized augmented plane wave plus local orbitals WIEN2k and pseudo potential Quantum-ESPRESSO codes. The thermoelectric properties are derived from Boltzmann transport theory under the constant relaxation time approximation, using the BoltzTraP code. We will discuss first the changes in the electronic band structure under variation of the cation concentration in layered KxRhO2 in the 2H phase and NaxRhO2 in the 3R phase. We will also study the hydrated phase. The deformations of the RhO6 octahedra turn out to govern the thermoelectric properties, where the high Seebeck coefficient results from ”pudding mold" bands. We investigate the thermoelectric properties of electron and hole doped PtSb2, which is not a layered material but shares “pudding mold" bands. PtSb2 has a high Seebeck coefficient at room temperature, which increases significantly under As alloying by bandgap opening and reduction of the lattice thermal conductivity. Bi2Se3 (bulk and thin film) has a larger bandgap then the well-known thermoelectric material Bi2Te3, which is important at high temperature. The structural stability, electronic structure, and transport properties of one to six quintuple layers of Bi2Se3 will be discussed. We also address the effect of strain on a single quintuple layer by phonon band structures. We will analyze the electronic and transport

Electronic Structure and Transport in Solids from First Principles

Science.gov (United States)

Mustafa, Jamal Ibrahim

The focus of this dissertation is the determination of the electronic structure and trans- port properties of solids. We first review some of the theory and computational methodology used in the calculation of electronic structure and materials properties. Throughout the dissertation, we make extensive use of state-of-the-art software packages that implement density functional theory, density functional perturbation theory, and the GW approximation, in addition to specialized methods for interpolating matrix elements for extremely accurate results. The first application of the computational framework introduced is the determination of band offsets in semiconductor heterojunctions using a theory of quantum dipoles at the interface. This method is applied to the case of heterojunction formed between a new metastable phase of silicon, with a rhombohedral structure, and cubic silicon. Next, we introduce a novel method for the construction of localized Wannier functions, which we have named the optimized projection functions method (OPFM). We illustrate the method on a variety of systems and find that it can reliably construct localized Wannier functions with minimal user intervention. We further develop the OPFM to investigate a class of materials called topological insulators, which are insulating in the bulk but have conductive surface states. These properties are a result of a nontrivial topology in their band structure, which has interesting effects on the character of the Wannier functions. In the last sections of the main text, the noble metals are studied in great detail, including their electronic properties and carrier dynamics. In particular, we investigate, the Fermi surface properties of the noble metals, specifically electron-phonon scattering lifetimes, and subsequently the transport properties determined by carriers on the Fermi surface. To achieve this, a novel sampling technique is developed, with wide applicability to transport calculations

Monte Carlo electron/photon transport

International Nuclear Information System (INIS)

Mack, J.M.; Morel, J.E.; Hughes, H.G.

1985-01-01

A review of nonplasma coupled electron/photon transport using Monte Carlo method is presented. Remarks are mainly restricted to linerarized formalisms at electron energies from 1 keV to 1000 MeV. Applications involving pulse-height estimation, transport in external magnetic fields, and optical Cerenkov production are discussed to underscore the importance of this branch of computational physics. Advances in electron multigroup cross-section generation is reported, and its impact on future code development assessed. Progress toward the transformation of MCNP into a generalized neutral/charged-particle Monte Carlo code is described. 48 refs

Discussion of electron cross sections for transport calculations

International Nuclear Information System (INIS)

Berger, M.J.

1983-01-01

This paper deals with selected aspects of the cross sections needed as input for transport calculations and for the modeling of radiation effects in biological materials. Attention is centered mainly on the cross sections for inelastic interactions between electrons and water molecules and the use of these cross sections for the calculation of energy degradation spectra and of ionization and excitation yields. 40 references, 3 figures, 1 table

An electron beam induced current study of gallium nitride and diamond materials

International Nuclear Information System (INIS)

Cropper, A.D.; Moore, D.J.; Scott, C.S.; Green, R.

1995-01-01

The continual need for microelectronic devices that operate under severe electronic and environmental conditions (high temperature, high frequency, high power, and radiation tolerance) has sustained research in wide bandgap semiconductor materials. The properties suggest these wide-bandgap semiconductor materials have tremendous potential for military and commercial applications. High frequency bipolar transistors and field effect transistors, diodes, and short wavelength optical devices have been proposed using these materials. Although research efforts involving the study of transport properties in Gallium Nitride (GaN) and Diamond have made significant advances, much work is still needed to improve the material quality so that the electrophysical behavior of device structures can be further understood and exploited. Electron beam induced current (EBIC) measurements can provide a method of understanding the transport properties in Gallium Nitride (GaN) and Diamond. This technique basically consists of measuring the current or voltage transient response to the drift and diffusion of carriers created by a short-duration pulse of radiation. This method differs from other experimental techniques because it is based on a fast transient electron beam probe created from a high speed, laser pulsed photoemission system

Introduction to organic electronic and optoelectronic materials and devices

CERN Document Server

Sun, Sam-Shajing

2008-01-01

Introduction to Optoelectronic Materials, N. Peyghambarian and M. Fallahi Introduction to Optoelectronic Device Principles, J. Piprek Basic Electronic Structures and Charge Carrier Generation in Organic Optoelectronic Materials, S.-S. Sun Charge Transport in Conducting Polymers, V.N. Prigodin and A.J. Epstein Major Classes of Organic Small Molecules for Electronic and Optoelectronics, X. Meng, W. Zhu, and H. Tian Major Classes of Conjugated Polymers and Synthetic Strategies, Y. Li and J. Hou Low Energy Gap, Conducting, and Transparent Polymers, A. Kumar, Y. Ner, and G.A. Sotzing Conjugated Polymers, Fullerene C60, and Carbon Nanotubes for Optoelectronic Devices, L. Qu, L. Dai, and S.-S. Sun Introduction of Organic Superconducting Materials, H. Mori Molecular Semiconductors for Organic Field-Effect Transistors, A. Facchetti Polymer Field-Effect Transistors, H.G.O. Sandberg Organic Molecular Light-Emitting Materials and Devices, F. So and J. Shi Polymer Light-Emitting Diodes: Devices and Materials, X. Gong and ...

Influence of electron transport on the efficiency of polymer-based solar cells

Energy Technology Data Exchange (ETDEWEB)

Kuxhaus, Viktor; Jaiser, Frank; Neher, Dieter [Institute of Physics and Astronomy, University Potsdam (Germany); Voges, Frank [Merck KGaA, Darmstadt (Germany)

2010-07-01

Recently, we showed that the mobility of electrons in polymer-based solar cells has a large influence on the overall performance of such devices. Here, we investigate the correlation between electron mobility and charge generation efficiency in organic bilayer solar cells for a series of electron transporting materials (ETMs) with comparable HOMO and LUMO levels. The electron mobility was measured by transient electroluminescence. Here, a thin M3EH-PPV was used as a sensing layer. The interface between M3EH-PPV and ETM acted as a recombination zone of electrons transported through the ETM layer and holes that are blocked at the interface. Therefore, the electron mobility can easily be determined from the onset of M3EH-PPV emission which is spectrally well separated from the ETM emission. To determine the charge generation efficiency, the different ETMs were combined in bilayer solar cell with PFB as donator.

Experimental Study of Electron and Phonon Dynamics in Nanoscale Materials by Ultrafast Laser Time-Domain Spectroscopy

Science.gov (United States)

Shen, Xiaohan

With the rapid advances in the development of nanotechnology, nowadays, the sizes of elementary unit, i.e. transistor, of micro- and nanoelectronic devices are well deep into nanoscale. For the pursuit of cheaper and faster nanoscale electronic devices, the size of transistors keeps scaling down. As the miniaturization of the nanoelectronic devices, the electrical resistivity increases dramatically, resulting rapid growth in the heat generation. The heat generation and limited thermal dissipation in nanoscale materials have become a critical problem in the development of the next generation nanoelectronic devices. Copper (Cu) is widely used conducting material in nanoelectronic devices, and the electron-phonon scattering is the dominant contributor to the resistivity in Cu nanowires at room temperature. Meanwhile, phonons are the main carriers of heat in insulators, intrinsic and lightly doped semiconductors. The thermal transport is an ensemble of phonon transport, which strongly depends on the phonon frequency. In addition, the phonon transport in nanoscale materials can behave fundamentally different than in bulk materials, because of the spatial confinement. However, the size effect on electron-phonon scattering and frequency dependent phonon transport in nanoscale materials remain largely unexplored, due to the lack of suitable experimental techniques. This thesis is mainly focusing on the study of carrier dynamics and acoustic phonon transport in nanoscale materials. The weak photothermal interaction in Cu makes thermoreflectance measurement difficult, we rather measured the reflectivity change of Cu induced by absorption variation. We have developed a method to separately measure the processes of electron-electron scattering and electron-phonon scattering in epitaxial Cu films by monitoring the transient reflectivity signal using the resonant probe with particular wavelengths. The enhancement on electron-phonon scattering in epitaxial Cu films with thickness

ITS - The integrated TIGER series of coupled electron/photon Monte Carlo transport codes

International Nuclear Information System (INIS)

Halbleib, J.A.; Mehlhorn, T.A.

1985-01-01

The TIGER series of time-independent coupled electron/photon Monte Carlo transport codes is a group of multimaterial, multidimensional codes designed to provide a state-of-the-art description of the production and transport of the electron/photon cascade. The codes follow both electrons and photons from 1.0 GeV down to 1.0 keV, and the user has the option of combining the collisional transport with transport in macroscopic electric and magnetic fields of arbitrary spatial dependence. Source particles can be either electrons or photons. The most important output data are (a) charge and energy deposition profiles, (b) integral and differential escape coefficients for both electrons and photons, (c) differential electron and photon flux, and (d) pulse-height distributions for selected regions of the problem geometry. The base codes of the series differ from one another primarily in their dimensionality and geometric modeling. They include (a) a one-dimensional multilayer code, (b) a code that describes the transport in two-dimensional axisymmetric cylindrical material geometries with a fully three-dimensional description of particle trajectories, and (c) a general three-dimensional transport code which employs a combinatorial geometry scheme. These base codes were designed primarily for describing radiation transport for those situations in which the detailed atomic structure of the transport medium is not important. For some applications, it is desirable to have a more detailed model of the low energy transport. The system includes three additional codes that contain a more elaborate ionization/relaxation model than the base codes. Finally, the system includes two codes that combine the collisional transport of the multidimensional base codes with transport in macroscopic electric and magnetic fields of arbitrary spatial dependence

Evaluation of Monte Carlo electron-Transport algorithms in the integrated Tiger series codes for stochastic-media simulations

International Nuclear Information System (INIS)

Franke, B.C.; Kensek, R.P.; Prinja, A.K.

2013-01-01

Stochastic-media simulations require numerous boundary crossings. We consider two Monte Carlo electron transport approaches and evaluate accuracy with numerous material boundaries. In the condensed-history method, approximations are made based on infinite-medium solutions for multiple scattering over some track length. Typically, further approximations are employed for material-boundary crossings where infinite-medium solutions become invalid. We have previously explored an alternative 'condensed transport' formulation, a Generalized Boltzmann-Fokker-Planck (GBFP) method, which requires no special boundary treatment but instead uses approximations to the electron-scattering cross sections. Some limited capabilities for analog transport and a GBFP method have been implemented in the Integrated Tiger Series (ITS) codes. Improvements have been made to the condensed history algorithm. The performance of the ITS condensed-history and condensed-transport algorithms are assessed for material-boundary crossings. These assessments are made both by introducing artificial material boundaries and by comparison to analog Monte Carlo simulations. (authors)

The effect of electron-electron interaction induced dephasing on electronic transport in graphene nanoribbons

Energy Technology Data Exchange (ETDEWEB)

Kahnoj, Sina Soleimani; Touski, Shoeib Babaee [School of Electrical and Computer Engineering, University of Tehran, P.O. Box 14395-515, Tehran (Iran, Islamic Republic of); Pourfath, Mahdi, E-mail: pourfath@ut.ac.ir, E-mail: pourfath@iue.tuwien.ac.at [School of Electrical and Computer Engineering, University of Tehran, P.O. Box 14395-515, Tehran (Iran, Islamic Republic of); Institute for Microelectronics, TU Wien, Gusshausstrasse 27–29/E360, 1040 Vienna (Austria)

2014-09-08

The effect of dephasing induced by electron-electron interaction on electronic transport in graphene nanoribbons is theoretically investigated. In the presence of disorder in graphene nanoribbons, wavefunction of electrons can set up standing waves along the channel and the conductance exponentially decreases with the ribbon's length. Employing the non-equilibrium Green's function formalism along with an accurate model for describing the dephasing induced by electron-electron interaction, we show that this kind of interaction prevents localization and transport of electrons remains in the diffusive regime where the conductance is inversely proportional to the ribbon's length.

The transport of hazardous materials

International Nuclear Information System (INIS)

Goemmel, F.

1987-01-01

The rapid development of all kinds of transports has been leading to a continuously increasing number of accidents involving the release and escape of hazardous materials. The risks involved for men and the environment have to be realized and reduced to a minimum. Efforts in this field have meanwhile been accumulating an enormous quantity of rules, recommendations and regulations. They comprise, among others, both national and international rail transport, maritime transport, inland shipping, air and road transport regulations adding up to a total of about 5000 pages. The publication discusses the necessity and justification of the existing quantity of regulations, it deals with their possible simplification and modified user-oriented arrangement as well as with a possible international harmonization of regulations. Apart from giving a general survey of the transport of hazardous materials the author reviews the intensive efforts which are going into the safety of the transport of hazardous materials and points out technical and legal problems which have remained unsolved so far. The publication essentially contributes to clearing up the background, perspectives and prospects of the complex regulations controlling the transport of hazardous materials. (orig./HP) [de

Molecule@MOF: A New Class of Opto-electronic Materials.

Energy Technology Data Exchange (ETDEWEB)

Talin, Albert Alec [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jones, Reese E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Spataru, Dan Catalin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Leonard, Francois Leonard [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); He, Yuping [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Foster, Michael E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Allendorf, Mark D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Stavila, Vitalie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hopkins, Patrick E. [Univ. of Virginia, Charlottesville, VA (United States)

2017-09-01

Metal organic frameworks (MOFs) are extended, nanoporous crystalline compounds consisting of metal ions interconnected by organic ligands. Their synthetic versatility suggest a disruptive class of opto - electronic materials with a high degree of electrical tunability and without the property - degrading disorder of organic conductors. In this project we determined the factors controlling charge and energy transport in MOFs and evaluated their potential for thermoelectric energy conversion. Two strategies for a chieving electronic conductivity in MOFs were explored: 1) using redox active 'guest' molecules introduced into the pores to dope the framework via charge - transfer coupling (Guest@MOF), 2) metal organic graphene analogs (MOGs) with dispersive band structur es arising from strong electronic overlap between the MOG metal ions and its coordinating linker groups. Inkjet deposition methods were developed to facilitate integration of the guest@MOF and MOG materials into practical devices.

Electronic Materials Science

Science.gov (United States)

Irene, Eugene A.

2005-02-01

A thorough introduction to fundamental principles and applications From its beginnings in metallurgy and ceramics, materials science now encompasses such high- tech fields as microelectronics, polymers, biomaterials, and nanotechnology. Electronic Materials Science presents the fundamentals of the subject in a detailed fashion for a multidisciplinary audience. Offering a higher-level treatment than an undergraduate textbook provides, this text benefits students and practitioners not only in electronics and optical materials science, but also in additional cutting-edge fields like polymers and biomaterials. Readers with a basic understanding of physical chemistry or physics will appreciate the text's sophisticated presentation of today's materials science. Instructive derivations of important formulae, usually omitted in an introductory text, are included here. This feature offers a useful glimpse into the foundations of how the discipline understands such topics as defects, phase equilibria, and mechanical properties. Additionally, concepts such as reciprocal space, electron energy band theory, and thermodynamics enter the discussion earlier and in a more robust fashion than in other texts. Electronic Materials Science also features: An orientation towards industry and academia drawn from the author's experience in both arenas Information on applications in semiconductors, optoelectronics, photocells, and nanoelectronics Problem sets and important references throughout Flexibility for various pedagogical needs Treating the subject with more depth than any other introductory text, Electronic Materials Science prepares graduate and upper-level undergraduate students for advanced topics in the discipline and gives scientists in associated disciplines a clear review of the field and its leading technologies.

Nuclear materials transportation

International Nuclear Information System (INIS)

Ushakov, B.A.

1986-01-01

Various methods of nuclear materials transportation at different stages of the fuel cycle (U 3 O 8 , UF 6 production enrichment, fuel element manufacturing, storage) are considered. The advantages and drawbacks of railway, automobile, maritime and air transport are analyzed. Some types of containers are characterized

Radioactive materials' transportation main routes in Brazil. Radiation protection aspects about radioactive materials transportation

International Nuclear Information System (INIS)

Vaz, Solange dos Reis e; Andrade, Fernando de Menezes; Aleixo, Luiz Claudio Martins

2007-01-01

The heavy transportation in Brazil is generally done by highways. The radioactive material transportation follow this same rule. Whenever a radioactive material is carried by the road, by the sea or by the air, in some cases, a kind of combination of those transportation ways, the transport manager has to create a Transportation Plan and submit it to CNEN. Only after CNEN's approval, the transportation can be done. The plan must have the main action on Radiation Protection, giving responsibilities and showing all the directing that will be take. Although, the Brazilian's highways are not in good conditions, one could say that some of them are not good enough for any kind of transportation. But we are facing radioactive material use increase but the hospitals and industries, that the reason it's much more common that kind of transportation nowadays. So, because of that, a special attention by the governments must be provide to those activities. This paper goal is to show the real conditions of some important highways in Brazil in a radioactive protection's perspective and give some suggestions to adjust some of those roads to this new reality. (author)

Tunneling explains efficient electron transport via protein junctions.

Science.gov (United States)

Fereiro, Jerry A; Yu, Xi; Pecht, Israel; Sheves, Mordechai; Cuevas, Juan Carlos; Cahen, David

2018-05-15

Metalloproteins, proteins containing a transition metal ion cofactor, are electron transfer agents that perform key functions in cells. Inspired by this fact, electron transport across these proteins has been widely studied in solid-state settings, triggering the interest in examining potential use of proteins as building blocks in bioelectronic devices. Here, we report results of low-temperature (10 K) electron transport measurements via monolayer junctions based on the blue copper protein azurin (Az), which strongly suggest quantum tunneling of electrons as the dominant charge transport mechanism. Specifically, we show that, weakening the protein-electrode coupling by introducing a spacer, one can switch the electron transport from off-resonant to resonant tunneling. This is a consequence of reducing the electrode's perturbation of the Cu(II)-localized electronic state, a pattern that has not been observed before in protein-based junctions. Moreover, we identify vibronic features of the Cu(II) coordination sphere in transport characteristics that show directly the active role of the metal ion in resonance tunneling. Our results illustrate how quantum mechanical effects may dominate electron transport via protein-based junctions.

Dossier: transport of radioactive materials; Dossier: le transport des matieres radioactives

Energy Technology Data Exchange (ETDEWEB)

Mignon, H. [CEA Centre d`Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France). Direction du Cycle du Combustible; Niel, J.Ch. [CEA Centre d`Etudes Nucleaires de Fontenay-aux-Roses, 92 (France). Inst. de Protection et de Surete Nucleaire; Canton, H. [CEA Cesta, 33 - Bordeaux (France); Brachet, Y. [Transnucleaire, 75 - Paris (France); Turquet de Beauregard, G.; Mauny, G. [CIS bio international, France (France); Robine, F.; Plantet, F. [Prefecture de la Moselle (France); Pestel Lefevre, O. [Ministere de l`Equipement, des transports et du logement, (France); Hennenhofer, G. [BMU, Ministere de l`environnement, de la protection de la nature et de la surete des reacteurs (Germany); Bonnemains, J. [Association Robin des Bois (France)

1997-12-01

This dossier is entirely devoted to the transportation of radioactive and fissile materials of civil use. It comprises 9 papers dealing with: the organization of the control of the radioactive materials transport safety (safety and security aspects, safety regulations, safety analysis and inspection, emergency plans, public information), the technical aspects of the regulation concerning the transport of radioactive materials (elaboration of regulations and IAEA recommendations, risk assessments, defense in depth philosophy and containers, future IAEA recommendations, expertise-research interaction), the qualification of containers (regulations, test facilities), the Transnucleaire company (presentation, activity, containers for spent fuels), the packages of radioactive sources for medical use (flux, qualification, safety and transport), an example of accident during radioactive materials transportation: the Apach train derailment (February 4, 1997), the sea transport of radioactive materials (international maritime organization (OMI), international maritime dangerous goods (IMDG) code, irradiated nuclear fuel (INF) safety rules), the transport of radioactive materials in Germany, and the point of view from an external observer. (J.S.)

Paleoclassical transport explains electron transport barriers in RTP and TEXTOR

NARCIS (Netherlands)

Hogeweij, G. M. D.; Callen, J.D.

2008-01-01

The recently developed paleoclassical transport model sets the minimum level of electron thermal transport in a tokamak. This transport level has proven to be in good agreement with experimental observations in many cases when fluctuation-induced anomalous transport is small, i.e. in (near-) ohmic

Using Adobe Flash animations of electron transport chain to teach and learn biochemistry.

Science.gov (United States)

Teplá, Milada; Klímová, Helena

2015-01-01

Teaching the subject of the electron transport chain is one of the most challenging aspects of the chemistry curriculum at the high school level. This article presents an educational program called "Electron Transport Chain" which consists of 14 visual animations including a biochemistry quiz. The program was created in the Adobe Flash CS3 Professional animation program and is designed for high school chemistry students. Our goal is to develop educational materials that facilitate the comprehension of this complex subject through dynamic animations which show the course of the electron transport chain and simultaneously explain its nature. We record the process of the electron transport chain, including connections with oxidative phosphorylation, in such a way as to minimize the occurrence of discrepancies in interpretation. The educational program was evaluated in high schools through the administration of a questionnaire, which contained 12 opened-ended items and which required participants to evaluate the graphics of the animations, chemical content, student preferences, and its suitability for high school biochemistry teaching. © 2015 The International Union of Biochemistry and Molecular Biology.

Competition between deformability and charge transport in semiconducting polymers for flexible and stretchable electronics

International Nuclear Information System (INIS)

Printz, Adam D.; Lipomi, Darren J.

2016-01-01

The primary goal of the field concerned with organic semiconductors is to produce devices with performance approaching that of silicon electronics, but with the deformability—flexibility and stretchability—of conventional plastics. However, an inherent competition between deformability and charge transport has long been observed in these materials, and achieving the extreme (or even moderate) deformability implied by the word “plastic” concurrently with high charge transport may be elusive. This competition arises because the properties needed for high carrier mobilities—e.g., rigid chains in π-conjugated polymers and high degrees of crystallinity in the solid state—are antithetical to deformability. On the device scale, this competition can lead to low-performance yet mechanically robust devices, or high-performance devices that fail catastrophically (e.g., cracking, cohesive failure, and delamination) under strain. There are, however, some observations that contradict the notion of the mutual exclusivity of electronic and mechanical performances. These observations suggest that this problem may not be a fundamental trade-off, but rather an inconvenience that may be negotiated by a logical selection of materials and processing conditions. For example, the selection of the poly(3-alkylthiophene) with a critical side-chain length—poly(3-heptylthiophene) (n = 7)—marries the high deformability of poly(3-octylthiophene) (n = 8) with the high electronic performance (as manifested in photovoltaic efficiency) of poly(3-hexylthiophene) (n = 6). This review explores the relationship between deformability and charge transport in organic semiconductors. The principal conclusions are that reducing the competition between these two parameters is in fact possible, with two demonstrated routes being: (1) incorporation of softer, insulating material into a stiffer, semiconducting material and (2) increasing disorder in a highly ordered film, but not

Competition between deformability and charge transport in semiconducting polymers for flexible and stretchable electronics

Energy Technology Data Exchange (ETDEWEB)

Printz, Adam D.; Lipomi, Darren J., E-mail: dlipomi@ucsd.edu [Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, California 92093-0448 (United States)

2016-06-15

The primary goal of the field concerned with organic semiconductors is to produce devices with performance approaching that of silicon electronics, but with the deformability—flexibility and stretchability—of conventional plastics. However, an inherent competition between deformability and charge transport has long been observed in these materials, and achieving the extreme (or even moderate) deformability implied by the word “plastic” concurrently with high charge transport may be elusive. This competition arises because the properties needed for high carrier mobilities—e.g., rigid chains in π-conjugated polymers and high degrees of crystallinity in the solid state—are antithetical to deformability. On the device scale, this competition can lead to low-performance yet mechanically robust devices, or high-performance devices that fail catastrophically (e.g., cracking, cohesive failure, and delamination) under strain. There are, however, some observations that contradict the notion of the mutual exclusivity of electronic and mechanical performances. These observations suggest that this problem may not be a fundamental trade-off, but rather an inconvenience that may be negotiated by a logical selection of materials and processing conditions. For example, the selection of the poly(3-alkylthiophene) with a critical side-chain length—poly(3-heptylthiophene) (n = 7)—marries the high deformability of poly(3-octylthiophene) (n = 8) with the high electronic performance (as manifested in photovoltaic efficiency) of poly(3-hexylthiophene) (n = 6). This review explores the relationship between deformability and charge transport in organic semiconductors. The principal conclusions are that reducing the competition between these two parameters is in fact possible, with two demonstrated routes being: (1) incorporation of softer, insulating material into a stiffer, semiconducting material and (2) increasing disorder in a highly ordered film, but not

Monte Carlo Transport for Electron Thermal Transport

Science.gov (United States)

Chenhall, Jeffrey; Cao, Duc; Moses, Gregory

2015-11-01

The iSNB (implicit Schurtz Nicolai Busquet multigroup electron thermal transport method of Cao et al. is adapted into a Monte Carlo transport method in order to better model the effects of non-local behavior. The end goal is a hybrid transport-diffusion method that combines Monte Carlo Transport with a discrete diffusion Monte Carlo (DDMC). The hybrid method will combine the efficiency of a diffusion method in short mean free path regions with the accuracy of a transport method in long mean free path regions. The Monte Carlo nature of the approach allows the algorithm to be massively parallelized. Work to date on the method will be presented. This work was supported by Sandia National Laboratory - Albuquerque and the University of Rochester Laboratory for Laser Energetics.

Safe transport of radioactive materials

Energy Technology Data Exchange (ETDEWEB)

NONE

1977-12-31

The film shows the widespread use of radioactive materials in industry, medicine and research and explains the need for transporting nuclear material from producer to user. It shows the way in which packages containing radioactive materials are handled during transport and explains the most important provisions of the IAEA transport regulations, safety series no. 6, such as packaging design criteria and testing requirements, illustrated by various tests carried out, specimen packages and package and freight container labelling. Also illustrated are practical measures to be taken in case of an accident

Quantum Transport Simulations of Nanoscale Materials

KAUST Repository

Obodo, Tobechukwu Joshua

2016-01-07

two dipyrimidinyl-diphenyl molecules improves the rectification ratio, and tuning the asymmetry of the tandem set-up by rearranging the molecular blocks greatly enhances it. It has been recently demonstrated that the large band gap of boronitrene can be significantly reduced by carbon functionalization. We show that specific defect configurations can result in metallicity, raising interest in the material for electronic applications. In particular, we demonstrate negative differential conductance with high peak-to-valley ratios, depending on the details of the material, and identify the finite bias effects that are responsible for this behavior. Also, we studied the spin polarized transport through Mn-decorated topological line defects in graphene. Strong preferential bonding is found, which overcomes the high mobility of transition metal atoms on graphene and results in stable structures. Despite a large distance between the magnetic centers, we find a high magnetoresistance and attribute this unexpected property to very strong induced π magnetism. Finally, the results obtained herein advance the field of quantum electronic transport and provide significant insight on switches, rectification, negative differential conductance, magnetoresistance, and current-induced forces of novel nanoscale materials.

Nonequilibrium Transport and the Bernoulli Effect of Electrons in a Two-Dimensional Electron Gas

Science.gov (United States)

Kaya, Ismet I.

2013-02-01

Nonequilibrium transport of charged carriers in a two-dimensional electron gas is summarized from an experimental point of view. The transport regime in which the electron-electron interactions are enhanced at high bias leads to a range of striking effects in a two-dimensional electron gas. This regime of transport is quite different than the ballistic transport in which particles propagate coherently with no intercarrier energy transfer and the diffusive transport in which the momentum of the electron system is lost with the involvement of the phonons. Quite a few hydrodynamic phenomena observed in classical gasses have the electrical analogs in the current flow. When intercarrier scattering events dominate the transport, the momentum sharing via narrow angle scattering among the hot and cold electrons lead to negative resistance and electron pumping which can be viewed as the analog of the Bernoulli-Venturi effect observed classical gasses. The recent experimental findings and the background work in the field are reviewed.

Electron transport through supported biomembranes at the nanoscale by conductive atomic force microscopy

International Nuclear Information System (INIS)

Casuso, I; Fumagalli, L; Samitier, J; Padros, E; Reggiani, L; Akimov, V; Gomila, G

2007-01-01

We present a reliable methodology to perform electron transport measurements at the nanoscale on supported biomembranes by conductive atomic force microscopy (C-AFM). It allows measurement of both (a) non-destructive conductive maps and (b) force controlled current-voltage characteristics in wide voltage bias range in a reproducible way. Tests experiments were performed on purple membrane monolayers, a two-dimensional (2D) crystal lattice of the transmembrane protein bacteriorhodopsin. Non-destructive conductive images show uniform conductivity of the membrane with isolated nanometric conduction defects. Current-voltage characteristics under different compression conditions show non-resonant tunneling electron transport properties, with two different conduction regimes as a function of the applied bias, in excellent agreement with theoretical predictions. This methodology opens the possibility for a detailed study of electron transport properties of supported biological membranes, and of soft materials in general

Electron transport through supported biomembranes at the nanoscale by conductive atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Casuso, I [Department Electronica, Universitat de Barcelona and Laboratori de Nanobioenginyeria-IBEC, Parc CientIfic de Barcelona, Barcelona (Spain); Fumagalli, L [Department Electronica, Universitat de Barcelona and Laboratori de Nanobioenginyeria-IBEC, Parc CientIfic de Barcelona, Barcelona (Spain); Samitier, J [Department Electronica, Universitat de Barcelona and Laboratori de Nanobioenginyeria-IBEC, Parc CientIfic de Barcelona, Barcelona (Spain); Padros, E [Unitat de BiofIsica, Departamento de BioquImica i de Biologia Molecular, Facultat de Medicina i Centre d' Estudis en BiofIsica, Universitat Autonoma de Barcelona, Barcelona (Spain); Reggiani, L [CNR-INFM National Nanotechnology Laboratory, Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, Lecce (Italy); Akimov, V [CNR-INFM National Nanotechnology Laboratory, Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, Lecce (Italy); Gomila, G [Department Electronica, Universitat de Barcelona and Laboratori de Nanobioenginyeria-IBEC, Parc CientIfic de Barcelona, Barcelona (Spain)

2007-11-21

We present a reliable methodology to perform electron transport measurements at the nanoscale on supported biomembranes by conductive atomic force microscopy (C-AFM). It allows measurement of both (a) non-destructive conductive maps and (b) force controlled current-voltage characteristics in wide voltage bias range in a reproducible way. Tests experiments were performed on purple membrane monolayers, a two-dimensional (2D) crystal lattice of the transmembrane protein bacteriorhodopsin. Non-destructive conductive images show uniform conductivity of the membrane with isolated nanometric conduction defects. Current-voltage characteristics under different compression conditions show non-resonant tunneling electron transport properties, with two different conduction regimes as a function of the applied bias, in excellent agreement with theoretical predictions. This methodology opens the possibility for a detailed study of electron transport properties of supported biological membranes, and of soft materials in general.

The effects of electron and hole transport layer with the electrode work function on perovskite solar cells

Science.gov (United States)

Deng, Quanrong; Li, Yiqi; Chen, Lian; Wang, Shenggao; Wang, Geming; Sheng, Yonglong; Shao, Guosheng

2016-09-01

The effects of electron and hole transport layer with the electrode work function on perovskite solar cells with the interface defects were simulated by using analysis of microelectronic and photonic structures-one-dimensional (AMPS-1D) software. The simulation results suggest that TiO2 electron transport layer provides best device performance with conversion efficiency of 25.9% compared with ZnO and CdS. The threshold value of back electrode work function for Spiro-OMeTAD, NiO, CuI and Cu2O hole transport layer are calculated to be 4.9, 4.8, 4.7 and 4.9 eV, respectively, to reach the highest conversion efficiency. The mechanisms of device physics with various electron and hole transport materials are discussed in details. The device performance deteriorates gradually as the increased density of interface defects located at ETM/absorber or absorber/HTM. This research results can provide helpful guidance for materials and metal electrode choice for perovskite solar cells.

Transport of radioactive materials

International Nuclear Information System (INIS)

Lenail, B.

1984-01-01

Transport of radioactive materials is dependent of transport regulations. In practice integrated doses for personnel during transport are very low but are more important during loading or unloading a facility (reactor, plant, laboratory, ...). Risks occur also if packagings are used outside specifications. Recommendations to avoid these risks are given [fr

Topological materials discovery using electron filling constraints

Science.gov (United States)

Chen, Ru; Po, Hoi Chun; Neaton, Jeffrey B.; Vishwanath, Ashvin

2018-01-01

Nodal semimetals are classes of topological materials that have nodal-point or nodal-line Fermi surfaces, which give them novel transport and topological properties. Despite being highly sought after, there are currently very few experimental realizations, and identifying new materials candidates has mainly relied on exhaustive database searches. Here we show how recent studies on the interplay between electron filling and nonsymmorphic space-group symmetries can guide the search for filling-enforced nodal semimetals. We recast the previously derived constraints on the allowed band-insulator fillings in any space group into a new form, which enables effective screening of materials candidates based solely on their space group, electron count in the formula unit, and multiplicity of the formula unit. This criterion greatly reduces the computation load for discovering topological materials in a database of previously synthesized compounds. As a demonstration, we focus on a few selected nonsymmorphic space groups which are predicted to host filling-enforced Dirac semimetals. Of the more than 30,000 entires listed, our filling criterion alone eliminates 96% of the entries before they are passed on for further analysis. We discover a handful of candidates from this guided search; among them, the monoclinic crystal Ca2Pt2Ga is particularly promising.

Transportation of Hazardous Evidentiary Material.

Energy Technology Data Exchange (ETDEWEB)

Osborn, Douglas.

2005-06-01

This document describes the specimen and transportation containers currently available for use with hazardous and infectious materials. A detailed comparison of advantages, disadvantages, and costs of the different technologies is included. Short- and long-term recommendations are also provided.3 DraftDraftDraftExecutive SummaryThe Federal Bureau of Investigation's Hazardous Materials Response Unit currently has hazardous material transport containers for shipping 1-quart paint cans and small amounts of contaminated forensic evidence, but the containers may not be able to maintain their integrity under accident conditions or for some types of hazardous materials. This report provides guidance and recommendations on the availability of packages for the safe and secure transport of evidence consisting of or contaminated with hazardous chemicals or infectious materials. Only non-bulk containers were considered because these are appropriate for transport on small aircraft. This report will addresses packaging and transportation concerns for Hazardous Classes 3, 4, 5, 6, 8, and 9 materials. If the evidence is known or suspected of belonging to one of these Hazardous Classes, it must be packaged in accordance with the provisions of 49 CFR Part 173. The anthrax scare of several years ago, and less well publicized incidents involving unknown and uncharacterized substances, has required that suspicious substances be sent to appropriate analytical laboratories for analysis and characterization. Transportation of potentially hazardous or infectious material to an appropriate analytical laboratory requires transport containers that maintain both the biological and chemical integrity of the substance in question. As a rule, only relatively small quantities will be available for analysis. Appropriate transportation packaging is needed that will maintain the integrity of the substance, will not allow biological alteration, will not react chemically with the substance being

Excess electron transport in cryoobjects

CERN Document Server

Eshchenko, D G; Brewer, J H; Cottrell, S P; Cox, S F J

2003-01-01

Experimental results on excess electron transport in solid and liquid phases of Ne, Ar, and solid N sub 2 -Ar mixture are presented and compared with those for He. Muon spin relaxation technique in frequently switching electric fields was used to study the phenomenon of delayed muonium formation: excess electrons liberated in the mu sup + ionization track converge upon the positive muons and form Mu (mu sup + e sup -) atoms. This process is shown to be crucially dependent upon the electron's interaction with its environment (i.e., whether it occupies the conduction band or becomes localized in a bubble of tens of angstroms in radius) and upon its mobility in these states. The characteristic lengths involved are 10 sup - sup 6 -10 sup - sup 4 cm, the characteristic times range from nanoseconds to tens microseconds. Such a microscopic length scale sometimes enables the electron spend its entire free lifetime in a state which may not be detected by conventional macroscopic techniques. The electron transport proc...

Transportation of nuclear materials

International Nuclear Information System (INIS)

Brobst, W.A.

1977-01-01

Twenty years of almost accident-free transport of nuclear materials is pointed to as evidence of a fundamentally correct approach to the problems involved. The increased volume and new technical problems in the future will require extension of these good practices in both regulations and packaging. The general principles of safety in the transport of radioactive materials are discussed first, followed by the transport of spent fuel and of radioactive waste. The security and physical protection of nuclear shipments is then treated. In discussing future problems, the question of public understanding and acceptance is taken first, thereafter transport safeguards and the technical bases for the safety regulations. There is also said to be a need for a new technology for spent fuel casks, while a re-examination of the IAEA transport standards for radiation doses is recommended. The IAEA regulations regarding quality assurance are said to be incomplete, and more information is required on correlations between engineering analysis, scale model testing and full scale crash testing. Transport stresses on contents need to be considered while administrative controls have been neglected. (JIW)

Emergency Response to Radioactive Material Transport Accidents

International Nuclear Information System (INIS)

EL-shinawy, R.M.K.

2009-01-01

Although transport regulations issued by IAEA is providing a high degree of safety during transport opertions,transport accidents involving packages containing radioactive material have occurred and will occur at any time. Whenever a transport accident involving radioactive material accurs, and many will pose no radiation safety problems, emergency respnose actioms are meeded to ensure that radiation safety is maintained. In case of transport accident that result in a significant relesae of radioactive material , loss of shielding or loss of criticality control , that consequences should be controlled or mitigated by proper emergency response actions safety guide, Emergency Response Plamming and Prepardness for transport accidents involving radioactive material, was published by IAEA. This guide reflected all requirememts of IAEA, regulations for safe transport of radioactive material this guide provide guidance to the publicauthorites and other interested organziation who are responsible for establishing such emergency arrangements

Fabrication and electronic transport studies of single nanocrystal systems

Energy Technology Data Exchange (ETDEWEB)

Klein, David Louis [Univ. of California, Berkeley, CA (United States). Dept. of Physics

1997-05-01

Semiconductor and metallic nanocrystals exhibit interesting electronic transport behavior as a result of electrostatic and quantum mechanical confinement effects. These effects can be studied to learn about the nature of electronic states in these systems. This thesis describes several techniques for the electronic study of nanocrystals. The primary focus is the development of novel methods to attach leads to prefabricated nanocrystals. This is because, while nanocrystals can be readily synthesized from a variety of materials with excellent size control, means to make electrical contact to these nanocrystals are limited. The first approach that will be described uses scanning probe microscopy to first image and then electrically probe surfaces. It is found that electronic investigations of nanocrystals by this technique are complicated by tip-sample interactions and environmental factors such as salvation and capillary forces. Next, an atomic force microscope technique for the catalytic patterning of the surface of a self assembled monolayer is described. In principle, this nano-fabrication technique can be used to create electronic devices which are based upon complex arrangements of nanocrystals. Finally, the fabrication and electrical characterization of a nanocrystal-based single electron transistor is presented. This device is fabricated using a hybrid scheme which combines electron beam lithography and wet chemistry to bind single nanocrystals in tunneling contact between closely spaced metallic leads. In these devices, both Au and CdSe nanocrystals show Coulomb blockade effects with characteristic energies of several tens of meV. Additional structure is seen the transport behavior of CdSe nanocrystals as a result of its electronic structure.

Temperature dependent transport of two dimensional electrons in the integral quantum Hall regime

International Nuclear Information System (INIS)

Wi, H.P.

1986-01-01

This thesis is concerned with the temperature dependent electronic transport properties of a two dimensional electron gas subject to background potential fluctuations and a perpendicular magnetic field. The author carried out an extensive temperature dependent study of the transport coefficients, in the region of an integral quantum plateau, in an In/sub x/Ga/sub 1-x/As/InP heterostructure for 4.2K 10 cm -2 meV -1 ) even at the middle between two Landau levels, which is unexpected from model calculations based on short ranged randomness. In addition, the different T dependent behavior of rho/sub xx/ between the states in the tails and those near the center of a Landau level, indicates the existence of different electron states in a Landau level. Additionally, the author reports T-dependent transport measurements in the transition region between two quantum plateaus in several different materials

Effect of lithium and sodium ion adsorption on the electronic transport properties of Ti3C2 MXene

International Nuclear Information System (INIS)

Berdiyorov, G.R.

2015-01-01

Highlights: • Effect of Li and Na ion adsorption on the electronic transport in Ti 3 C 2 MXene is studied. • Fluorinated, oxidized and hydroxylated surfaces are considered. • Enhanced charge transport is obtained for fluorinated and hydroxylated samples. • Electronic transmission is reduced in the oxidized sample. • The pristine and oxidized MXene samples are found to be sensitive to the ions adsorption. - Abstract: MXenes are found to be promising electrode materials for energy storage applications. Recent theoretical and experimental studies indicate the possibility of using these novel low dimensional materials for metal-ion batteries. Herein, we use density-functional theory in combination with the nonequilibrium Green's function formalism to study the effect of lithium and sodium ion adsorption on the electronic transport properties of the MXene, Ti 3 C 2 . Oxygen, hydroxyl and fluorine terminated species are considered and the obtained results are compared with the ones for the pristine MXene. We found that the ion adsorption results in reduced electronic transport in the pristine MXene: depending on the type of the ions and the bias voltage, the current in the system can be reduced by more than 30%. On the other hand, transport properties of the oxygen terminated sample can be improved by the ion adsorption: for both types of ions the current in the system can be increased by more than a factor of 4. However, the electronic transport is less affected by the ions in fluorinated and hydroxylated samples. These two samples show enhanced electronic transport as compared to the pristine MXene. The obtained results are explained in terms of electron localization in the system.

Paleoclassical transport explains electron transport barriers in RTP and TEXTOR

Energy Technology Data Exchange (ETDEWEB)

Hogeweij, G M D [FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, PO Box 1207, NL-3430 BE Nieuwegein (Netherlands); Callen, J D [University of Wisconsin, Madison, WI 53706-1609 (United States)

2008-06-15

The recently developed paleoclassical transport model sets the minimum level of electron thermal transport in a tokamak. This transport level has proven to be in good agreement with experimental observations in many cases when fluctuation-induced anomalous transport is small, i.e. in (near-)ohmic plasmas in small to medium size tokamaks, inside internal transport barriers (ITBs) or edge transport barriers (H-mode pedestal). In this paper predictions of the paleoclassical transport model are compared in detail with data from such kinds of discharges: ohmic discharges from the RTP tokamak, EC heated RTP discharges featuring both dynamic and shot-to-shot scans of the ECH power deposition radius and off-axis EC heated discharges from the TEXTOR tokamak. For ohmically heated RTP discharges the T{sub e} profiles predicted by the paleoclassical model are in reasonable agreement with the experimental observations, and various parametric dependences are captured satisfactorily. The electron thermal ITBs observed in steady state EC heated RTP discharges and transiently after switch-off of off-axis ECH in TEXTOR are predicted very well by the paleoclassical model.

Electronic and vibrational hopping transport in boron carbides

International Nuclear Information System (INIS)

Emin, D.

1991-01-01

General concepts of hopping-type transport and localization are reviewed. Disorder, electronic correlations and atomic displacements, effects ignored in electronic band structure calculations, foster localization of electronic charge carriers. Examples are given that illustrate the efficacy of these effects in producing localization. This introduction is followed by a brief discussion of the relation between hopping-type transport and localization. The fundamentals of the formation, localization, and hopping transport of small polarons and/or bipolarons is then described. Electronic transport in boron carbides is presented as an example of the adiabatic hopping of small bipolarons. Finally, the notion of vibrational hopping is introduced. The high-temperature thermal diffusion in boron carbides is presented as a potential application of this idea

Advances in electronic materials

CERN Document Server

Kasper, Erich; Grimmeiss, Hermann G

2008-01-01

This special-topic volume, Advances in Electronic Materials, covers various fields of materials research such as silicon, silicon-germanium hetero-structures, high-k materials, III-V semiconductor alloys and organic materials, as well as nano-structures for spintronics and photovoltaics. It begins with a brief summary of the formative years of microelectronics; now the keystone of information technology. The latter remains one of the most important global technologies, and is an extremely complex subject-area. Although electronic materials are primarily associated with computers, the internet

HMPT: Basic Radioactive Material Transportation

Energy Technology Data Exchange (ETDEWEB)

Hypes, Philip A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-02-29

Hazardous Materials and Packaging and Transportation (HMPT): Basic Radioactive Material Transportation Live (#30462, suggested one time) and Test (#30463, required initially and every 36 months) address the Department of Transportation’s (DOT’s) function-specific [required for hazardous material (HAZMAT) handlers, packagers, and shippers] training requirements of the HMPT Los Alamos National Laboratory (LANL) Labwide training. This course meets the requirements of 49 CFR 172, Subpart H, Section 172.704(a)(ii), Function-Specific Training.

Self-consistent electron transport in collisional plasmas

International Nuclear Information System (INIS)

Mason, R.J.

1982-01-01

A self-consistent scheme has been developed to model electron transport in evolving plasmas of arbitrary classical collisionality. The electrons and ions are treated as either multiple donor-cell fluids, or collisional particles-in-cell. Particle suprathermal electrons scatter off ions, and drag against fluid background thermal electrons. The background electrons undergo ion friction, thermal coupling, and bremsstrahlung. The components move in self-consistent advanced E-fields, obtained by the Implicit Moment Method, which permits Δt >> ω/sub p/ -1 and Δx >> lambda/sub D/ - offering a 10 2 - 10 3 -fold speed-up over older explicit techniques. The fluid description for the background plasma components permits the modeling of transport in systems spanning more than a 10 7 -fold change in density, and encompassing contiguous collisional and collisionless regions. Results are presented from application of the scheme to the modeling of CO 2 laser-generated suprathermal electron transport in expanding thin foils, and in multi-foil target configurations

Overview of nuclear materials transportation

International Nuclear Information System (INIS)

Grella, A.W.

1986-01-01

This presentation is an overview of transportation as it relates to one specific type of material, low specific activity (LSA) material. It is the predominant type of material that fits into the low-level waste category. An attempt is made to discuss how LSA is regulated, setting forth the requirements. First the general scheme of regulations are reviewed. In addition future changes in the regulations which will affect transportation of LSA materials and, which quite likely, will have an impact on R and D needs in this area are presented

Penelope-2006: a code system for Monte Carlo simulation of electron and photon transport

International Nuclear Information System (INIS)

2006-01-01

The computer code system PENELOPE (version 2006) performs Monte Carlo simulation of coupled electron-photon transport in arbitrary materials for a wide energy range, from a few hundred eV to about 1 GeV. Photon transport is simulated by means of the standard, detailed simulation scheme. Electron and positron histories are generated on the basis of a mixed procedure, which combines detailed simulation of hard events with condensed simulation of soft interactions. A geometry package called PENGEOM permits the generation of random electron-photon showers in material systems consisting of homogeneous bodies limited by quadric surfaces, i.e. planes, spheres, cylinders, etc. This report is intended not only to serve as a manual of the PENELOPE code system, but also to provide the user with the necessary information to understand the details of the Monte Carlo algorithm. These proceedings contain the corresponding manual and teaching notes of the PENELOPE-2006 workshop and training course, held on 4-7 July 2006 in Barcelona, Spain. (author)

Impact of vacancy ordering on thermal transport in crystalline phase-change materials

International Nuclear Information System (INIS)

Siegert, K S; Lange, F R L; Sittner, E R; Volker, H; Schlockermann, C; Wuttig, M; Siegrist, T

2015-01-01

Controlling thermal transport in solids is of paramount importance for many applications. Often thermal management is crucial for a device's performance, as it affects both reliability and power consumption. A number of intricate concepts have been developed to address this challenge, such as diamond-like coatings to enhance the thermal conductivity or low symmetry complex super-structures to reduce it. Here, a different approach is pursued, where we explore the potential of solids with a high yet controllable degree of disorder. Recently, it has been demonstrated that an unconventionally high degree of structural disorder characterizes a number of crystalline phase-change materials (PCMs). This disorder strongly impacts electronic transport and even leads to disorder induced localization (Anderson localization). This raises the question how thermal transport is affected by such conditions. Here thermal transport in highly disordered crystalline Ge–Sb–Te (GST) based PCMs is investigated. Glass-like thermal properties are observed for several crystalline PCMs, which are attributed to strong scattering by disordered point defects. A systematic study of different compounds along the pseudo-binary line between GeTe and Sb 2 Te 3 reveals that disordered vacancies act as point defects responsible for pronounced phonon scattering. Annealing causes a gradual ordering of the vacancies and leads to a more ‘crystal-like’ thermal conductivity. While both vibrational and electronic degrees of freedom are affected by disorder, the consequences differ for different stoichiometries. This opens up a pathway to tune electrical and thermal transport by controlling the degree of disorder. Materials with tailored transport properties may not only help to improve power efficiency and scaling in upcoming phase-change memories but are also of fundamental interest in the field of thermoelectric materials. (key issues review)

Impact of vacancy ordering on thermal transport in crystalline phase-change materials.

Science.gov (United States)

Siegert, K S; Lange, F R L; Sittner, E R; Volker, H; Schlockermann, C; Siegrist, T; Wuttig, M

2015-01-01

Controlling thermal transport in solids is of paramount importance for many applications. Often thermal management is crucial for a device's performance, as it affects both reliability and power consumption. A number of intricate concepts have been developed to address this challenge, such as diamond-like coatings to enhance the thermal conductivity or low symmetry complex super-structures to reduce it. Here, a different approach is pursued, where we explore the potential of solids with a high yet controllable degree of disorder. Recently, it has been demonstrated that an unconventionally high degree of structural disorder characterizes a number of crystalline phase-change materials (PCMs). This disorder strongly impacts electronic transport and even leads to disorder induced localization (Anderson localization). This raises the question how thermal transport is affected by such conditions. Here thermal transport in highly disordered crystalline Ge-Sb-Te (GST) based PCMs is investigated. Glass-like thermal properties are observed for several crystalline PCMs, which are attributed to strong scattering by disordered point defects. A systematic study of different compounds along the pseudo-binary line between GeTe and Sb2Te3 reveals that disordered vacancies act as point defects responsible for pronounced phonon scattering. Annealing causes a gradual ordering of the vacancies and leads to a more 'crystal-like' thermal conductivity. While both vibrational and electronic degrees of freedom are affected by disorder, the consequences differ for different stoichiometries. This opens up a pathway to tune electrical and thermal transport by controlling the degree of disorder. Materials with tailored transport properties may not only help to improve power efficiency and scaling in upcoming phase-change memories but are also of fundamental interest in the field of thermoelectric materials.

Energy-filtered cold electron transport at room temperature.

Science.gov (United States)

Bhadrachalam, Pradeep; Subramanian, Ramkumar; Ray, Vishva; Ma, Liang-Chieh; Wang, Weichao; Kim, Jiyoung; Cho, Kyeongjae; Koh, Seong Jin

2014-09-10

Fermi-Dirac electron thermal excitation is an intrinsic phenomenon that limits functionality of various electron systems. Efforts to manipulate electron thermal excitation have been successful when the entire system is cooled to cryogenic temperatures, typically distribution corresponds to an effective electron temperature of ~45 K, can be transported throughout device components without external cooling. This is accomplished using a discrete level of a quantum well, which filters out thermally excited electrons and permits only energy-suppressed electrons to participate in electron transport. The quantum well (~2 nm of Cr2O3) is formed between source (Cr) and tunnelling barrier (SiO2) in a double-barrier-tunnelling-junction structure having a quantum dot as the central island. Cold electron transport is detected from extremely narrow differential conductance peaks in electron tunnelling through CdSe quantum dots, with full widths at half maximum of only ~15 mV at room temperature.

Theoretical investigations of molecular wires: Electronic spectra and electron transport

Science.gov (United States)

Palma, Julio Leopoldo

The results of theoretical and computational research are presented for two promising molecular wires, the Nanostar dendrimer, and a series of substituted azobenzene derivatives connected to aluminum electrodes. The electronic absorption spectra of the Nanostar (a phenylene-ethynylene dendrimer attached to an ethynylperylene chromophore) were calculated using a sequential Molecular Dynamics/Quantum Mechanics (MD/QM) method to perform an analysis of the temperature dependence of the electronic absorption process. We modeled the Nanostar as a series of connected units, and performed MD simulations for each chromophore at 10 K and 300 K to study how the temperature affected the structures and, consequently, the spectra. The absorption spectra of the Nanostar were computed using an ensemble of 8000 structures for each chromophore. Quantum Mechanical (QM) ZINDO/S calculations were performed for each conformation in the ensemble, including 16 excited states, for a total of 128,000 excitation energies. The spectral intensity was then scaled linearly with the number of conjugated units. Our calculations for both the individual chromophores and the Nanostar, are in good agreement with experiments. We explain in detail the effects of temperature and the consequences for the absorption process. The second part of this thesis presents a study of the effects of chemical substituents on the electron transport properties of the azobenzene molecule, which has been proposed recently as a component of a light-driven molecular switch. This molecule has two stable conformations (cis and trans) in its electronic ground state, with considerable differences in their conductance. The electron transport properties were calculated using first-principles methods combining non-equilibrium Green's function (NEGF) techniques with density functional theory (DFT). For the azobenzene studies, we included electron-donating groups and electron-withdrawing groups in meta- and ortho-positions with

Plasma channels for electron beam transport

International Nuclear Information System (INIS)

Schneider, R.F.; Smith, J.R.; Moffatt, M.E.; Nguyen, K.T.; Uhm, H.S.

1988-01-01

In recent years, there has been much interest in transport of intense relativistic electron beams using plasma channels. These channels are formed by either: ionization of an organic gas by UV photoionization or electron impact ionization of a low pressure gas utilizing a low energy (typically several hundred volts) electron gun. The second method is discussed here. As their electron gun, the authors used a 12 volt lightbulb filament which is biased to -400 volts with respect to the grounded 15 cm diameter drift tube. The electrons emitted from the filament are confined by an axial magnetic field of --100 Gauss to create a plasma channel which is less than 1 cm in radius. The channel density has been determined with Langmuir probes and the resulting line densities were found to be 10 11 to 10 12 per cm. When a multi-kiloamp electron beam is injected onto this channel, the beam space charge will eject the plasma electrons leaving the ions behind to charge neutralize the electron beam, hence allowing the beam to propagate. In this work, the authors performed experimental studies on the dynamics of the plasma channel. These include Langmuir probe measurements of a steady state (DC) channel, as well as time-resolved Langmuir probe studies of pulsed channels. In addition they performed experimental studies of beam propagation in these plasma channels. Specifically, they observed the behavior of current transport in these channels. Detailed results of beam transport and channel studies are presented

Safe transport of radioactive material

International Nuclear Information System (INIS)

1990-01-01

Recently the Agency redefined its policy for education and training in radiation safety. The emphasis is now on long-term strategic planning of general education and training programmes. In line with this general policy the Agency's Standing Advisory Group for the Safe Transport of Radioactive Material (SAGSTRAM) in its 7th meeting (April 1989) agreed that increased training activity should be deployed in the area of transport. SAGSTRAM specifically recommended the development of a standard training programme on this subject area, including audio-visual aids, in order to assist Member States in the implementation of the Agency's Regulations for the Safe Transport of Radioactive Material. This training programme should be substantiated by a biennial training course which is thought to be held either as an Interregional or a Regional Course depending on demand. This training manual, issued as a first publication in the Training Course Series, represents the basic text material for future training courses in transport safety. The topic areas covered by this training manual and most of the texts have been developed from the course material used for the 1987 Bristol Interregional Course on Transport Safety. The training manual is intended to give guidance to the lecturers of a course and will be provided to the participants for retention. Refs, figs and tabs

Nuclear materials transport worldwide

International Nuclear Information System (INIS)

Stellpflug, J.

1987-01-01

This Greenpeace report shows: nuclear materials transport is an extremely hazardous business. There is no safe protection against accidents, kidnapping, or sabotage. Any moment of a day, at any place, a nuclear transport accident may bring the world to disaster, releasing plutonium or radioactive fission products to the environment. Such an event is not less probable than the MCA at Chernobyl. The author of the book in hand follows the secret track of radioactive materials around the world, from uranium mines to the nuclear power plants, from reprocessing facilities to the waste repositories. He explores the routes of transport and the risks involved, he gives the names of transport firms and discloses incidents and carelessness, tells about damaged waste drums and plutonium that 'disappeared'. He also tells about worldwide, organised resistance to such nuclear transports, explaining the Greenpeace missions on the open sea, or the 'day X' operation at the Gorleben site, informing the reader about protests and actions for a world freed from the threat of nuclear energy. (orig./HP) [de

Vibrationally coupled electron transport through single-molecule junctions

Energy Technology Data Exchange (ETDEWEB)

Haertle, Rainer

2012-04-26

Single-molecule junctions are among the smallest electric circuits. They consist of a molecule that is bound to a left and a right electrode. With such a molecular nanocontact, the flow of electrical currents through a single molecule can be studied and controlled. Experiments on single-molecule junctions show that a single molecule carries electrical currents that can even be in the microampere regime. Thereby, a number of transport phenomena have been observed, such as, for example, diode- or transistor-like behavior, negative differential resistance and conductance switching. An objective of this field, which is commonly referred to as molecular electronics, is to relate these transport phenomena to the properties of the molecule in the contact. To this end, theoretical model calculations are employed, which facilitate an understanding of the underlying transport processes and mechanisms. Thereby, one has to take into account that molecules are flexible structures, which respond to a change of their charge state by a profound reorganization of their geometrical structure or may even dissociate. It is thus important to understand the interrelation between the vibrational degrees of freedom of a singlemolecule junction and the electrical current flowing through the contact. In this thesis, we investigate vibrational effects in electron transport through singlemolecule junctions. For these studies, we calculate and analyze transport characteristics of both generic and first-principles based model systems of a molecular contact. To this end, we employ a master equation and a nonequilibrium Green's function approach. Both methods are suitable to describe this nonequilibrium transport problem and treat the interactions of the tunneling electrons on the molecular bridge non-perturbatively. This is particularly important with respect to the vibrational degrees of freedom, which may strongly interact with the tunneling electrons. We show in detail that the resulting

Noncovalent Intermolecular Interactions in Organic Electronic Materials: Implications for the Molecular Packing vs Electronic Properties of Acenes

KAUST Repository

Sutton, Christopher

2015-10-30

Noncovalent intermolecular interactions, which can be tuned through the toolbox of synthetic chemistry, determine not only the molecular packing but also the resulting electronic, optical, and mechanical properties of materials derived from π-conjugated molecules, oligomers, and polymers. Here, we provide an overview of the theoretical underpinnings of noncovalent intermolecular interactions and briefly discuss the computational chemistry approaches used to understand the magnitude of these interactions. These methodologies are then exploited to illustrate how noncovalent intermolecular interactions impact important electronic properties-such as the electronic coupling between adjacent molecules, a key parameter for charge-carrier transport-through a comparison between the prototype organic semiconductor pentacene with a series of N-substituted heteropentacenes. Incorporating an understanding of these interactions into the design of organic semiconductors can assist in developing novel materials systems from this fascinating molecular class. © 2015 American Chemical Society.

Safe transport of radioactive material

International Nuclear Information System (INIS)

1994-01-01

Delivering radioactive material to where it is needed is a vital service to industry and medicine. Millions of packages are shipped all over the world by all modes of transport. The shipments pass through public places and must meet stringent safety requirements. This video explains how radioactive material is safely transported and describes the rules that carriers and handlers must follow

Model Comparison for Electron Thermal Transport

Science.gov (United States)

Moses, Gregory; Chenhall, Jeffrey; Cao, Duc; Delettrez, Jacques

2015-11-01

Four electron thermal transport models are compared for their ability to accurately and efficiently model non-local behavior in ICF simulations. Goncharov's transport model has accurately predicted shock timing in implosion simulations but is computationally slow and limited to 1D. The iSNB (implicit Schurtz Nicolai Busquet electron thermal transport method of Cao et al. uses multigroup diffusion to speed up the calculation. Chenhall has expanded upon the iSNB diffusion model to a higher order simplified P3 approximation and a Monte Carlo transport model, to bridge the gap between the iSNB and Goncharov models while maintaining computational efficiency. Comparisons of the above models for several test problems will be presented. This work was supported by Sandia National Laboratory - Albuquerque and the University of Rochester Laboratory for Laser Energetics.

Transportation of hazardous and nuclear materials

International Nuclear Information System (INIS)

Boryczka, M.; Shaver, D.

1989-01-01

Transportation of hazardous and radioactive materials is a vital part of the nation's economy. In recent years public concern over the relative safety of transporting hazardous materials has risen sharply. The United States has a long history of transporting hazardous and radioactive material; rocket propellants, commercial spent fuel, low-level and high-level radioactive waste has been shipped for years. While the track record for shipping these materials is excellent, the knowledge that hazardous materials are passing through communities raises the ire of citizens and local governments. Public outcry over shipments containing hazardous cargo has been especially prominent when shippers have attempted to transport rocket propellants or spent nuclear fuel. Studies of recent shipments have provided insight into the difficulties of shipping in a politically charged environment, the major issues of concern to citizens, and some of the more successful methods of dealing with public concerns. This paper focuses on lessons learned from these studies which include interviews with shippers, carriers, and regulators

10 CFR 71.5 - Transportation of licensed material.

Science.gov (United States)

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Transportation of licensed material. 71.5 Section 71.5 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PACKAGING AND TRANSPORTATION OF RADIOACTIVE MATERIAL General Provisions § 71.5 Transportation of licensed material. (a) Each licensee who transports licensed...

Simulation of electron thermal transport in H-mode discharges

International Nuclear Information System (INIS)

Rafiq, T.; Pankin, A. Y.; Bateman, G.; Kritz, A. H.; Halpern, F. D.

2009-01-01

Electron thermal transport in DIII-D H-mode tokamak plasmas [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] is investigated by comparing predictive simulation results for the evolution of electron temperature profiles with experimental data. The comparison includes the entire profile from the magnetic axis to the bottom of the pedestal. In the simulations, carried out using the automated system for transport analysis (ASTRA) integrated modeling code, different combinations of electron thermal transport models are considered. The combinations include models for electron temperature gradient (ETG) anomalous transport and trapped electron mode (TEM) anomalous transport, as well as a model for paleoclassical transport [J. D. Callen, Nucl. Fusion 45, 1120 (2005)]. It is found that the electromagnetic limit of the Horton ETG model [W. Horton et al., Phys. Fluids 31, 2971 (1988)] provides an important contribution near the magnetic axis, which is a region where the ETG mode in the GLF23 model [R. E. Waltz et al., Phys. Plasmas 4, 2482 (1997)] is below threshold. In simulations of DIII-D discharges, the observed shape of the H-mode edge pedestal is produced when transport associated with the TEM component of the GLF23 model is suppressed and transport given by the paleoclassical model is included. In a study involving 15 DIII-D H-mode discharges, it is found that with a particular combination of electron thermal transport models, the average rms deviation of the predicted electron temperature profile from the experimental profile is reduced to 9% and the offset to -4%.

Safe transport of radioactive material. 3. ed

Energy Technology Data Exchange (ETDEWEB)

NONE

2002-12-01

The IAEA has developed a standardized approach to transport safety training as a means of helping Member States to implement the Transport Regulations. The training manual is an anchor of this standardized approach to training: it contains all the topics presented in the sequential order recommended by the IAEA for the student to gain a thorough understanding of the body of knowledge that is needed to ensure that radioactive material ranked as Class 7 in the United Nations' nomenclature for dangerous goods - is transported safely. The explanations in the text refer, where needed, to the appropriate requirements in the IAEA's Transport Regulations; additional useful information is also provided. Thus, the training manual in addition to the Transport Regulations and their supporting documents is used by the IAEA as the basis for delivering all of its training courses on the safe transport of radioactive material. Enclosed with the training manual is a CD-ROM that contains the text of the manual as well as the visual aids that are used at the IAEA's training courses. The following topics are covered: review of radioactivity and radiation; review of radiation protection principles; regulatory terminology; basic safety concepts: materials and packages; activity limits and material restrictions; selection of optimal package type; test procedures: material and packages; requirements for transport; control of material in transport; fissile material: regulatory requirements and operational aspects; quality assurance; national competent authority; additional regulatory constraints for transport; international liability and insurance; emergency planning and preparedness; training; services provided by the IAEA.

Safe transport of radioactive material. 3. ed

International Nuclear Information System (INIS)

2002-01-01

The IAEA has developed a standardized approach to transport safety training as a means of helping Member States to implement the Transport Regulations. The training manual is an anchor of this standardized approach to training: it contains all the topics presented in the sequential order recommended by the IAEA for the student to gain a thorough understanding of the body of knowledge that is needed to ensure that radioactive material ranked as Class 7 in the United Nations' nomenclature for dangerous goods - is transported safely. The explanations in the text refer, where needed, to the appropriate requirements in the IAEA's Transport Regulations; additional useful information is also provided. Thus, the training manual in addition to the Transport Regulations and their supporting documents is used by the IAEA as the basis for delivering all of its training courses on the safe transport of radioactive material. Enclosed with the training manual is a CD-ROM that contains the text of the manual as well as the visual aids that are used at the IAEA's training courses. The following topics are covered: review of radioactivity and radiation; review of radiation protection principles; regulatory terminology; basic safety concepts: materials and packages; activity limits and material restrictions; selection of optimal package type; test procedures: material and packages; requirements for transport; control of material in transport; fissile material: regulatory requirements and operational aspects; quality assurance; national competent authority; additional regulatory constraints for transport; international liability and insurance; emergency planning and preparedness; training; services provided by the IAEA

Electron transport in wurtzite InN

Indian Academy of Sciences (India)

InN transport; mobility; energy and momentum relaxation; impurity scattering. ... future generation solar cell because the nitride alloys can cover the whole ... We apply the ensemble Monte Carlo method to investigate the electron transport in.

Safety of transport of radioactive material. Contributed papers

Energy Technology Data Exchange (ETDEWEB)

NONE

2003-07-01

Radioactive material has been transported for decades within and between countries as the use of radioactive material to benefit mankind has expanded. The transport can involve many types of materials (radionuclides and radiation sources for applications in agriculture, energy production, industry, and medicine) and all modes of transport (road, rail, sea and waterways, and air). Among the organizations in the United Nations system, the International Atomic Energy Agency (IAEA) has the statutory function to establish or adopt standards of safety for protection of health against exposure to ionizing radiation. Within its statutory mandate and pursuant to this request, in 1961, the IAEA issued Regulations for the Safe Transport of Radioactive Material (the IAEA Transport Regulations). The Transport Regulations were periodically reviewed and, as appropriate, have been amended or revised. The latest version of the Transport Regulations was issued in 2000 by the IAEA as Publication TS-R-1 (ST-1, Revised). In addition, the IAEA is entrusted by its Statute to provide for the application of its standards at the request of States. The objective of the Conference is to foster the exchange of information on issues related to the safety of transport of radioactive material by providing an opportunity for representatives from sponsoring international organizations and their Member States and from other co-operating and participating organizations to discuss critical issues relating to the safety of transport of radioactive material by all modes and to formulate recommendations, as appropriate, regarding further international co-operation in this area. The following topics have been identified by the Technical Programme Committee as the subjects to be covered in the background briefing sessions: History and Status of the IAEA Transport Regulation Development; Experience in adoption of the IAEA Transport Regulations at the international level; Implementation of the IAEA Transport

Dopant controlled trap-filling and conductivity enhancement in an electron-transport polymer

Energy Technology Data Exchange (ETDEWEB)

Higgins, Andrew, E-mail: aehiggin@princeton.edu, E-mail: kahn@princeton.edu; Kahn, Antoine, E-mail: aehiggin@princeton.edu, E-mail: kahn@princeton.edu [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544-5263 (United States); Mohapatra, Swagat K.; Barlow, Stephen; Marder, Seth R. [Center for Organic Photonics and Electronics and School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400 (United States)

2015-04-20

Charge transport in organic semiconductors is often inhibited by the presence of tail states that extend into the band gap of a material and act as traps for charge carriers. This work demonstrates the passivation of acceptor tail states by solution processing of ultra-low concentrations of a strongly reducing air-stable organometallic dimer, the pentamethylrhodocene dimer, [RhCp*Cp]{sub 2}, into the electron transport polymer poly([N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide) -2,6-diyl]-alt-5,5′-(2,2′-bithiophene)), P(NDI{sub 2}OD-T{sub 2}). Variable-temperature current-voltage measurements of n-doped P(NDI{sub 2}OD-T{sub 2}) are presented with doping concentration varied through two orders of magnitude. Systematic variation of the doping parameter is shown to lower the activation energy for hopping transport and enhance film conductivity and electron mobility.

Risks in U.S. energy material transportation

International Nuclear Information System (INIS)

Franklin, A.L.; Rhoads, R.E.; Andrews, W.B.

1982-01-01

For the past five years, the Pacific Northwest Laboratory has been conducting a programme to study the safety of transporting energy materials. The overall objectives of the programme are to develop information on the safety of transporting hazardous materials required to support the major energy cycles in the USA. This information was developed for use in making energy policy decisions; in designing and developing new or improved transportation systems for these materials; to help establish research priorities; and as an aid in developing effective transportation safety regulations. Risk analysis was selected as the methodology for performing these studies. This methodology has been applied to rail and highway shipments of nuclear fuel cycle materials and liquid and gaseous fossil fuels. Studies of the risks of transporting spent nuclear fuel by train and uranium ore concentrates (yellow cake) by truck were expected to be issued early in 1981. Analyses of the risks of transporting reactor waste and transuranic wastes are in progress. The work completed to date for nuclear material transportation makes it possible to estimate the transportation risks for the entire fuel cycle in the USA. Results of the assessment are presented in this paper. Because the risk analysis studies for the transportation of gasoline, propane and chlorine have been performed using a methodology, basic assumptions and data that are consistent with the studies that have been performed for nuclear materials, comparisons between the risks for nuclear materials and these materials can also be made. It should be noted that it is not the intention of these comparisons to judge the safety of one industry in comparison with another. These comparisons can, however, provide some insights into the regulatory philosophy for hazardous materials transportation. The remaining sections of the paper briefly review the risk-analysis methodology used in these studies, provide an overview of the systems

Phonon limited electronic transport in Pb

Science.gov (United States)

Rittweger, F.; Hinsche, N. F.; Mertig, I.

2017-09-01

We present a fully ab initio based scheme to compute electronic transport properties, i.e. the electrical conductivity σ and thermopower S, in the presence of electron-phonon interaction. We explicitly investigate the \

Radioactive material air transportation

International Nuclear Information System (INIS)

Pader y Terry, Claudio Cosme

2002-01-01

As function of the high aggregated value, safety regulations and the useful life time, the air transportation has been used more regularly because is fast, reliable, and by giving great security to the cargo. Based on the International Atomic Energy Agency (IAEA), the IATA (International Air Transportation Association) has reproduced in his dangerous goods manual (Dangerous Goods Regulations - DGR IATA), the regulation for the radioactive material air transportation. Those documents support this presentation

Auditors of safety in hazardous materials transportation

International Nuclear Information System (INIS)

Manas Lahoz, J.L.

1993-01-01

The author describes the methodology for safety auditory and control, prevention, risks of hazardous materials transport through ship, airplane, rail, etc. In this way, The author presents the classification of damage materials transport, characteristic damage and different transport methods

Regulations for the safe transport of radioactive materials

International Nuclear Information System (INIS)

Kgogo, Obonye

2016-04-01

The report provides insight and investigates whether Transport Regulations in Botswana follow international standards for transport of radioactive material. Radioactive materials are very useful in most of our activities and are manufactured in different countries, therefore end up traversing from one country to another and being transported in national roads .The IAEA regulation for the Transport of radioactive material is used as the reference guideline in this study. The current Regulations for Transport of radioactive material in Botswana do not cover all factors which need to be considered when transporting radioactive although they refer to IAEA regulations. Basing on an inadequacy of the regulations and category of radioactive materials in the country recommendations were made concerning security, packaging and worker training's. The regulations for the Transport of radioactive material in Botswana need to be reviewed and updated so that they can relate to international standard. (au)

Measurements of Electron Transport in Foils Irradiated with a Picosecond Time Scale Laser Pulse

International Nuclear Information System (INIS)

Brown, C. R. D.; Hoarty, D. J.; James, S. F.; Swatton, D.; Hughes, S. J.; Morton, J. W.; Guymer, T. M.; Hill, M. P.; Chapman, D. A.; Andrew, J. E.; Comley, A. J.; Shepherd, R.; Dunn, J.; Chen, H.; Schneider, M.; Brown, G.; Beiersdorfer, P.; Emig, J.

2011-01-01

The heating of solid foils by a picosecond time scale laser pulse has been studied by using x-ray emission spectroscopy. The target material was plastic foil with a buried layer of a spectroscopic tracer material. The laser pulse length was either 0.5 or 2 ps, which resulted in a laser irradiance that varied over the range 10 16 -10 19 W/cm 2 . Time-resolved measurements of the buried layer emission spectra using an ultrafast x-ray streak camera were used to infer the density and temperature conditions as a function of laser parameters and depth of the buried layer. Comparison of the data to different models of electron transport showed that they are consistent with a model of electron transport that predicts the bulk of the target heating is due to return currents.

Ordered materials for organic electronics and photonics.

Science.gov (United States)

O'Neill, Mary; Kelly, Stephen M

2011-02-01

We present a critical review of semiconducting/light emitting, liquid crystalline materials and their use in electronic and photonic devices such as transistors, photovoltaics, OLEDs and lasers. We report that annealing from the mesophase improves the order and packing of organic semiconductors to produce state-of-the-art transistors. We discuss theoretical models which predict how charge transport and light emission is affected by the liquid crystalline phase. Organic photovoltaics and OLEDs require optimization of both charge transport and optical properties and we identify the various trade-offs involved for ordered materials. We report the crosslinking of reactive mesogens to give pixellated full-colour OLEDs and distributed bi-layer photovoltaics. We show how the molecular organization inherent to the mesophase can control the polarization of light-emitting devices and the gain in organic, thin-film lasers and can also provide distributed feedback in chiral nematic mirrorless lasers. We update progress on the surface alignment of liquid crystalline semiconductors to obtain monodomain devices without defects or devices with spatially varying properties. Finally the significance of all of these developments is assessed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spiers memorial lecture. Organic electronics: an organic materials perspective.

Science.gov (United States)

Wudl, Fred

2014-01-01

This Introductory Lecture is intended to provide a background to Faraday Discussion 174: "Organic Photonics and Electronics" and will consist of a chronological, subjective review of organic electronics. Starting with "ancient history" (1888) and history (1950-present), the article will take us to the present. The principal developments involved the processes of charge carrier generation and charge transport in molecular solids, starting with insulators (photoconductors) and moving to metals, to semiconductors and ending with the most popular semiconductor devices, such as organic light-emitting diodes (OLEDs), organic field effect transistors (OFETs) and organic photovoltaics (OPVs). The presentation will be from an organic chemistry/materials point of view.

The safe transport of radioactive materials

International Nuclear Information System (INIS)

Swindell, G.E.

1975-01-01

In the course of transport by road, rail, sea and air, consignments of radioactive material are in close proximity to ordinary members of the public and in most cases they are loaded and unloaded by transport workers who have no special training or experience in the handling of radioactive substances. The materials being transported cover a wide variety - ranging from small batches of short-lived radionuclides used in medical practice which can be transported in small sealed lead pots in cardboard boxes, to large, extremely radioactive consignments of irradiated nuclear fuel in flasks weighing many tons. With the growing development of nuclear power programmes the transport of irradiated fuel is likely to increase markedly. It is clear that unless adequate regulations concerning the design and assembly of the packages containing these materials are precisely set down and strictly carried out, there would be a high probability that some of the radioactive contents would be released, leading to contamination of other transported goods and the general environment, and to the delivery of a radiation dose to the transport workers and the public. An additional requirement is that the transport should proceed smoothly and without delay. This is particularly important for radioactive materials of short half-life, which would lose significant amounts of their total activity in unnecessary delays at international boundaries. Therefore, it is essential that the regulations are also enforced, to ensure that the radioactive material is contained and the surrounding radiation level reduced to a value which poses no threat to other sensitive goods such as photographic film, or to transport workers and other passengers. These regulations should be as uniform as possible on an international basis, so that consignments can move freely from one country to another with as little delay as possible at the frontiers. (author)

Packaging and transportation of radioactive materials

Energy Technology Data Exchange (ETDEWEB)

None

1978-01-01

The presentations made at the Symposium on Packaging and Transportation of Radioactive Materials are included. The purpose of the meeting was for the interchange of information on the technology and politics of radioactive material transportation. Separate abstracts were prepared for individual items. (DC)

Packaging and transportation of radioactive materials

International Nuclear Information System (INIS)

1978-01-01

The presentations made at the Symposium on Packaging and Transportation of Radioactive Materials are included. The purpose of the meeting was for the interchange of information on the technology and politics of radioactive material transportation. Separate abstracts were prepared for individual items

Innovative electron transport methods in EGS5

International Nuclear Information System (INIS)

Bielajew, A.F.; Wilderman, S.J.

2000-01-01

The initial formulation of a Monte Carlo scheme for the transport of high-energy (>≅ 100 keV) electrons was established by Berger in 1963. Calling his method the 'condensed history theory', Berger combined the theoretical results of the previous generation of research into developing approximate solutions of the Boltzmann transport equation with numerical algorithms for exploiting the power of computers to permit iterative, piece-wise solution of the transport equation in a computationally intensive but much less approximate fashion. The methods devised by Berger, with comparatively little modification, provide the foundation of all present day Monte Carlo electron transport simulation algorithms. Only in the last 15 years, beginning with the development and publication of the PRESTA algorithm, has there been a significant revisitation of the problem of simulating electron transport within the condensed history framework. Research in this area is ongoing, highly active, and far from complete. It presents an enormous challenge, demanding derivation of new analytical transport solutions based on underlying fundamental interaction mechanisms, intuitive insight in the development of computer algorithms, and state of the art computer science skills in order to permit deployment of these techniques in an efficient manner. The EGS5 project, a modern ground-up rewrite of the EGS4 code, is now in the design phase. EGS5 will take modern photon and electron transport algorithms and deploy them in an easy-to-maintain, modern computer language-ANSI-standard C ++. Moreover, the well-known difficulties of applying EGS4 to practical geometries (geometry code development, tally routine design) should be made easier and more intuitive through the use of a visual user interface being designed by Quantum Research, Inc., work that is presented elsewhere in this conference. This report commences with a historical review of electron transport models culminating with the proposal of a

Manipulation of electron transport in graphene by nanopatterned electrostatic potential on an electret

Science.gov (United States)

Wang, Xiaowei; Wang, Rui; Wang, Shengnan; Zhang, Dongdong; Jiang, Xingbin; Cheng, Zhihai; Qiu, Xiaohui

2018-01-01

The electron transport characteristics of graphene can be finely tuned using local electrostatic fields. Here, we use a scanning probe technique to construct a statically charged electret gate that enables in-situ fabrication of graphene devices with precisely designed potential landscapes, including p-type and n-type unipolar graphene transistors and p-n junctions. Electron dynamic simulation suggests that electron beam collimation and focusing in graphene can be achieved via periodic charge lines and concentric charge circles. This approach to spatially manipulating carrier density distribution may offer an efficient way to investigate the novel electronic properties of graphene and other low-dimensional materials.

Unique electron transport in ultrathin black phosphorene: Ab-initio study

International Nuclear Information System (INIS)

Srivastava, Anurag; Khan, Md. Shahzad; Gupta, Sanjeev Kumar; Pandey, Ravindra

2015-01-01

Graphical abstract: Charge transfer configuration for NH 3 and NO 2 adsorbed 2D black-phospherene. - Highlights: • Ultrathin black phosphorene has been investigated, in terms of its optical and ballistic quantum transport properties. • The device performance subtaintially increases in armchair direction of black phosphorene. • Maximum reflectivity (43%) is observed at 1.85 eV (670 nm) and the reflective spectrum dispersed in visible range. • At low bias semiconducting and higher bias ohmic nature pointing black phospherene a promising material for high perfomrance device applications. • For NO 2 gas, this quasi 2D-black phosphorene surface shows strong affinity followed with substantial charge tranfer. - Abstract: We present first principle structural, electronic, optical and transport analysis of black phosphorene a 2D layered material. The studied configuration shows semiconducting nature and the states around the Fermi energy are mainly contributed by the p-orbitals of atoms. In optical properties, the reflective spectrum is approximately dispersed in visible range suggesting that this 2D-nanostructure can be considered as shielding for visible region. Due to the anisotropy of the electronic structure of black phosphorene, the device performance is subtaintially preferable in armchair direction. Zero-bias transmission shows no conductance channel near Fermi level but in far region prominent spectra for the same is observed for black-phospherene. The studied configurations show non-linear current–voltage (I–V) characteristics. The sensitivity for NH 3 and NO 2 gas molecule is explored using electronic and current–voltage (I–V) characteristics. Investigations show that the black phosphorene has strong affinity for electron seeking NO 2 molecule, thus providing an opportunity for its sensor application.

Unique electron transport in ultrathin black phosphorene: Ab-initio study

Energy Technology Data Exchange (ETDEWEB)

Srivastava, Anurag, E-mail: profanurag@gmail.com [Advanced Materials Research Group, Computational Nanoscience & Technology Lab, ABV-Indian Institute of Information Technology and Management, Gwalior (M.P.) 474010 India (India); Khan, Md. Shahzad [Advanced Materials Research Group, Computational Nanoscience & Technology Lab, ABV-Indian Institute of Information Technology and Management, Gwalior (M.P.) 474010 India (India); Gupta, Sanjeev Kumar [Department of Physics, St. Xavier' s College, Ahmedabad 380009 (India); Pandey, Ravindra [Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 (United States)

2015-11-30

Graphical abstract: Charge transfer configuration for NH{sub 3} and NO{sub 2} adsorbed 2D black-phospherene. - Highlights: • Ultrathin black phosphorene has been investigated, in terms of its optical and ballistic quantum transport properties. • The device performance subtaintially increases in armchair direction of black phosphorene. • Maximum reflectivity (43%) is observed at 1.85 eV (670 nm) and the reflective spectrum dispersed in visible range. • At low bias semiconducting and higher bias ohmic nature pointing black phospherene a promising material for high perfomrance device applications. • For NO{sub 2} gas, this quasi 2D-black phosphorene surface shows strong affinity followed with substantial charge tranfer. - Abstract: We present first principle structural, electronic, optical and transport analysis of black phosphorene a 2D layered material. The studied configuration shows semiconducting nature and the states around the Fermi energy are mainly contributed by the p-orbitals of atoms. In optical properties, the reflective spectrum is approximately dispersed in visible range suggesting that this 2D-nanostructure can be considered as shielding for visible region. Due to the anisotropy of the electronic structure of black phosphorene, the device performance is subtaintially preferable in armchair direction. Zero-bias transmission shows no conductance channel near Fermi level but in far region prominent spectra for the same is observed for black-phospherene. The studied configurations show non-linear current–voltage (I–V) characteristics. The sensitivity for NH{sub 3} and NO{sub 2} gas molecule is explored using electronic and current–voltage (I–V) characteristics. Investigations show that the black phosphorene has strong affinity for electron seeking NO{sub 2} molecule, thus providing an opportunity for its sensor application.

Excess electron transport in cryoobjects

International Nuclear Information System (INIS)

Eshchenko, D.G.; Storchak, V.G.; Brewer, J.H.; Cottrell, S.P.; Cox, S.F.J.

2003-01-01

Experimental results on excess electron transport in solid and liquid phases of Ne, Ar, and solid N 2 -Ar mixture are presented and compared with those for He. Muon spin relaxation technique in frequently switching electric fields was used to study the phenomenon of delayed muonium formation: excess electrons liberated in the μ + ionization track converge upon the positive muons and form Mu (μ + e - ) atoms. This process is shown to be crucially dependent upon the electron's interaction with its environment (i.e., whether it occupies the conduction band or becomes localized in a bubble of tens of angstroms in radius) and upon its mobility in these states. The characteristic lengths involved are 10 -6 -10 -4 cm, the characteristic times range from nanoseconds to tens microseconds. Such a microscopic length scale sometimes enables the electron spend its entire free lifetime in a state which may not be detected by conventional macroscopic techniques. The electron transport processes are compared in: liquid and solid helium (where electron is localized in buble); liquid and solid neon (where electrons are delocalized in solid and the coexistence of localized and delocalized electrons states was found in liquid recently); liquid and solid argon (where electrons are delocalized in both phases); orientational glass systems (solid N 2 -Ar mixtures), where our results suggest that electrons are localized in orientational glass. This scaling from light to heavy rare gases enables us to reveal new features of excess electron localization on microscopic scale. Analysis of the experimental data makes it possible to formulate the following tendency of the muon end-of-track structure in condensed rare gases. The muon-self track interaction changes from the isolated pair (muon plus the nearest track electron) in helium to multi-pair (muon in the vicinity of tens track electrons and positive ions) in argon

Hazardous Material Packaging and Transportation

Energy Technology Data Exchange (ETDEWEB)

Hypes, Philip A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-02-04

This is a student training course. Some course objectives are to: recognize and use standard international and US customary units to describe activities and exposure rates associated with radioactive material; determine whether a quantity of a single radionuclide meets the definition of a class 7 (radioactive) material; determine, for a given single radionuclide, the shipping quantity activity limits per 49 Code of Federal Regulations (CFR) 173.435; determine the appropriate radioactive material hazard class proper shipping name for a given material; determine when a single radionuclide meets the DOT definition of a hazardous substance; determine the appropriate packaging required for a given radioactive material; identify the markings to be placed on a package of radioactive material; determine the label(s) to apply to a given radioactive material package; identify the entry requirements for radioactive material labels; determine the proper placement for radioactive material label(s); identify the shipping paper entry requirements for radioactive material; select the appropriate placards for a given radioactive material shipment or vehicle load; and identify allowable transport limits and unacceptable transport conditions for radioactive material.

Colloid transport in model fracture filling materials

Science.gov (United States)

Wold, S.; Garcia-Garcia, S.; Jonsson, M.

2010-12-01

Colloid transport in model fracture filling materials Susanna Wold*, Sandra García-García and Mats Jonsson KTH Chemical Science and Engineering Royal Institute of Technology, SE-100 44 Stockholm, Sweden *Corresponding author: E-mail: wold@kth.se Phone: +46 8 790 6295 In colloid transport in water-bearing fractures, the retardation depends on interactions with the fracture surface by sorption or filtration. These mechanisms are difficult to separate. A rougher surface will give a larger area available for sorption, and also when a particle is physically hindered, it approaches the surface and enables further sorption. Sorption can be explained by electrostatics were the strongest sorption on minerals always is observed at pH below pHpzc (Filby et al., 2008). The adhesion of colloids to mineral surfaces is related to the surface roughness according to a recent study (Darbha et al., 2010). There is a large variation in the characteristics of water-bearing fractures in bedrock in terms of aperture distribution, flow velocity, surface roughness, mineral distributions, presence of fracture filling material, and biological and organic material, which is hard to implement in modeling. The aim of this work was to study the transport of negatively charged colloids in model fracture filling material in relation to flow, porosity, mineral type, colloid size, and surface charge distribution. In addition, the impact on transport of colloids of mixing model fracture filling materials with different retention and immobilization capacities, determined by batch sorption experiments, was investigated. The transport of Na-montmorillonite colloids and well-defined negatively charged latex microspheres of 50, 100, and 200 nm diameter were studied in either columns containing quartz or quartz mixed with biotite. The ionic strength in the solution was exclusively 0.001 and pH 6 or 8.5. The flow rates used were 0.002, 0.03, and 0.6 mL min-1. Sorption of the colloids on the model fracture

Nanoscale electron transport at the surface of a topological insulator

Science.gov (United States)

Bauer, Sebastian; Bobisch, Christian A.

2016-04-01

The use of three-dimensional topological insulators for disruptive technologies critically depends on the dissipationless transport of electrons at the surface, because of the suppression of backscattering at defects. However, in real devices, defects are unavoidable and scattering at angles other than 180° is allowed for such materials. Until now, this has been studied indirectly by bulk measurements and by the analysis of the local density of states in close vicinity to defect sites. Here, we directly measure the nanoscale voltage drop caused by the scattering at step edges, which occurs if a lateral current flows along a three-dimensional topological insulator. The experiments were performed using scanning tunnelling potentiometry for thin Bi2Se3 films. So far, the observed voltage drops are small because of large contributions of the bulk to the electronic transport. However, for the use of ideal topological insulating thin films in devices, these contributions would play a significant role.

Electron heat transport analysis of low-collisionality plasmas in the neoclassical-transport-optimized configuration of LHD

International Nuclear Information System (INIS)

Murakami, Sadayoshi; Yamada, Hiroshi; Wakasa, Arimitsu

2002-01-01

Electron heat transport in low-collisionality LHD plasma is investigated in order to study the neoclassical transport optimization effect on thermal plasma transport with an optimization level typical of so-called ''advanced stellarators''. In the central region, a higher electron temperature is obtained in the optimized configuration, and transport analysis suggests the considerable effect of neoclassical transport on the electron heat transport assuming the ion-root level of radial electric field. The obtained experimental results support future reactor design in which the neoclassical and/or anomalous transports are reduced by magnetic field optimization in a non-axisymmetric configuration. (author)

Electron transport and improved confinement on Tore Supra

International Nuclear Information System (INIS)

Hoang, G.T.; Bourdelle, C.; Garbet, X.; Aniel, T.; Giruzzi, G.; Ottaviani, M.; Horton, W.; Zhu, P.; Budny, R.V.

2001-01-01

Magnetic shear is found to play an important role for triggering various improved confinement regimes through the electron channel. A wide database of hot electron plasmas (T e >2T i ) heated by fast wave electron heating (FWEH) is analyzed for electron thermal transport. A critical gradient is clearly observed. It is found that the critical gradient linearly increases with the ratio between local magnetic shear (s) and safety factor (q). The Horton model, based on the electromagnetic turbulence driven by the electron temperature gradient (ETG) mode, is found to be a good candidate for electron transport modeling. (author)

Electron transport in erbium arsenide:indium gallium(aluminum)arsenide metal/semiconductor nanocomposites for thermoelectric power generation

Science.gov (United States)

Bahk, Je-Hyeong

Electron transport in thin film ErAs:InGa(Al)As metal/semiconductor nanocomposite materials grown by molecular beam epitaxy is investigated experimentally and theoretically for efficient thermoelectric power generation. Thermoelectric properties such as the Seebeck coefficient, the electrical conductivity, and the thermal conductivity are measured for the various compositions of the material up to 840 K. A special sample preparation method is proposed to protect the thin films from damage and/or decomposition, and prevent the parasitic substrate conduction effect during the high temperature measurements. The sample preparation method includes surface passivation, high temperature metallization with a diffusion barrier, and the covalent oxide bonding technique for substrate removal. The experimental results for the nanocomposite materials are analyzed using the Boltzmann transport equation under the relaxation time approximation. The scattering characteristics of free electrons in the InGa(Al)As is defined by four major scattering mechanisms such as the polar optical phonon scattering, the ionized impurity scattering, the alloy scattering, and the acoustic phonon deformation potential scattering. Combining these scattering mechanisms, the electron transport model successfully fits the temperature-dependent thermoelectric properties of Si-doped InGaAlAs materials, and predicts the figure of merits at various doping levels in various Al compositions. The nanoparticle-electron interaction is modeled as a momentum scattering for free electrons caused by the electrostatic potential perturbation around nanoparticles and the band offset at the interface. The ErAs nanoparticles are assumed to be semi-metals that can donate electrons to the matrix, and positively charged after the charge transfer to build up the screened coulomb potential outside them. The nanoparticle scattering rate is calculated for this potential profile using the partial wave method, and used to analyze

Ab-initio quantum transport simulation of self-heating in single-layer 2-D materials

Science.gov (United States)

Stieger, Christian; Szabo, Aron; Bunjaku, Teutë; Luisier, Mathieu

2017-07-01

Through advanced quantum mechanical simulations combining electron transport and phonon transport from first-principles, self-heating effects are investigated in n-type transistors with single-layer MoS2, WS2, and black phosphorus as channel materials. The selected 2-D crystals all exhibit different phonon-limited mobility values, as well as electron and phonon properties, which have a direct influence on the increase in their lattice temperature and on the power dissipated inside their channel as a function of the applied gate voltage and electrical current magnitude. This computational study reveals (i) that self-heating plays a much more important role in 2-D materials than in Si nanowires, (ii) that it could severely limit the performance of 2-D devices at high current densities, and (iii) that black phosphorus appears less sensitive to this phenomenon than transition metal dichalcogenides.

Mode-selective vibrational modulation of charge transport in organic electronic devices

KAUST Repository

Bakulin, Artem A.

2015-08-06

The soft character of organic materials leads to strong coupling between molecular, nuclear and electronic dynamics. This coupling opens the way to influence charge transport in organic electronic devices by exciting molecular vibrational motions. However, despite encouraging theoretical predictions, experimental realization of such approach has remained elusive. Here we demonstrate experimentally that photoconductivity in a model organic optoelectronic device can be modulated by the selective excitation of molecular vibrations. Using an ultrafast infrared laser source to create a coherent superposition of vibrational motions in a pentacene/C60 photoresistor, we observe that excitation of certain modes in the 1,500–1,700 cm−1 region leads to photocurrent enhancement. Excited vibrations affect predominantly trapped carriers. The effect depends on the nature of the vibration and its mode-specific character can be well described by the vibrational modulation of intermolecular electronic couplings. This presents a new tool for studying electron–phonon coupling and charge dynamics in (bio)molecular materials.

Mode-selective vibrational modulation of charge transport in organic electronic devices

KAUST Repository

Bakulin, Artem A.; Lovrincic, Robert; Yu, Xi; Selig, Oleg; Bakker, Huib J.; Rezus, Yves L. A.; Nayak, Pabitra K.; Fonari, Alexandr; Coropceanu, Veaceslav; Bredas, Jean-Luc; Cahen, David

2015-01-01

The soft character of organic materials leads to strong coupling between molecular, nuclear and electronic dynamics. This coupling opens the way to influence charge transport in organic electronic devices by exciting molecular vibrational motions. However, despite encouraging theoretical predictions, experimental realization of such approach has remained elusive. Here we demonstrate experimentally that photoconductivity in a model organic optoelectronic device can be modulated by the selective excitation of molecular vibrations. Using an ultrafast infrared laser source to create a coherent superposition of vibrational motions in a pentacene/C60 photoresistor, we observe that excitation of certain modes in the 1,500–1,700 cm−1 region leads to photocurrent enhancement. Excited vibrations affect predominantly trapped carriers. The effect depends on the nature of the vibration and its mode-specific character can be well described by the vibrational modulation of intermolecular electronic couplings. This presents a new tool for studying electron–phonon coupling and charge dynamics in (bio)molecular materials.

Electron transport in the presence of a Coulomb field

International Nuclear Information System (INIS)

Burgdoerfer, J.; Gibbons, J.

1990-01-01

We analyze the modifications of the transport behavior of electrons in dense media due to the presence of a strong Coulomb field generated by an ion moving initially in close phase-space correlation with the electrons. These modifications play a profound role in convoy electron emission in ion-solid collisions. The transport behavior is studied within the framework of a classical phase-space master equation. The nonseparable master equation is solved numerically using test-particle discretization and Monte Carlo sampling. In the limit of vanishing Coulomb forces the master equation becomes separable and can be reduced to standard one-dimensional kinetic equations for free-electron transport that can be solved exactly. The comparison to free-electron transport is used to gauge both the reliability of test-particle discretization and the significance of Coulomb distortion of the distribution functions. Applications to convoy-electron emission are discussed

Electronic structure and transport properties of Ba2Cd2Pn3 (Pn = As and Sb): An efficient materials for energy conversion

International Nuclear Information System (INIS)

Reshak, A.H.

2016-01-01

The full potential method within the recently modified Becke-Johnson potential explore that the Ba 2 Cd 2 Pn 3 (Pn = As and Sb) compounds are narrow band gap semiconductors of about 0.49 and 0.32 eV, which confute the finding of the previous TB-LMTO-ASA calculation that Ba 2 Cd 2 Sb 3 is a poor metal. It has been found that there are subtle difference in band desperations of the two compounds, resulting in significant influence on the electronic and transport properties, taking into account the size and the electro-negativity differences between As and Sb atoms. Calculation show that there exists a strong hybridization between the orbitals which may lead to form covalent bonding which is more favorable for the transport of the carriers than ionic one. The electronic structure, the anisotropy and the inter-atomic interactions are further analyzed by calculating the valence electronic charge density distribution in two crystallographic planes. The semi-classical Boltzmann theory as incorporated in BoltzTraP code was used to calculate the transport properties of Ba 2 Cd 2 As 3 and Ba 2 Cd 2 Sb 3 at different temperatures and chemical potentials to ascertain the influence of temperatures and substituting As by Sb on the transport properties. The carries mobility decreases with increasing the temperature also with increasing the carriers concentration. We have observed that substituting As by Sb lead to increase the carries mobility of Ba 2 Cd 2 Sb 3 along the whole temperature interval and the carries concentration range. It has been found that Ba 2 Cd 2 As 3 exhibit higher carriers concentration, electronic electrical conductivity and Seebeck coefficient than that of Ba 2 Cd 2 Sb 3 along the investigated temperature range. The highest value of Seebeck coefficient occurs at 300 K, which show good agreement with the experimental data. The power factor increases linearly with increasing the temperature and Ba 2 Cd 2 As 3 exhibit a bit higher power factor than that of Ba

Fast electron transport study for inertial confinement fusion

International Nuclear Information System (INIS)

Touati, Michael

2015-01-01

A new hybrid reduced model for relativistic electron beam transport in solids and dense plasmas is presented. It is based on the two first angular moments of the relativistic kinetic equation completed with the Minerbo maximum angular entropy closure. It takes into account collective effects with the self-generated electromagnetic fields as well as collisional effects with the slowing down of the electrons in collisions with plasmons, bound and free electrons and their angular scattering on both ions and electrons. This model allows for fast computations of relativistic electron beam transport while describing the kinetic distribution function evolution. Despite the loss of information concerning the angular distribution of the electron beam, the model reproduces analytical estimates in the academic case of a collimated and monoenergetic electron beam propagating through a warm and dense Hydrogen plasma and hybrid PIC simulation results in a realistic laser-generated electron beam transport in a solid target. The model is applied to the study of the emission of Kα photons in laser-solid experiments and to the generation of shock waves. (author) [fr

Penelope - a code system for Monte Carlo simulation of electron and photon transport

International Nuclear Information System (INIS)

2003-01-01

Radiation is used in many applications of modern technology. Its proper handling requires competent knowledge of the basic physical laws governing its interaction with matter. To ensure its safe use, appropriate tools for predicting radiation fields and doses, as well as pertinent regulations, are required. One area of radiation physics that has received much attention concerns electron-photon transport in matter. PENELOPE is a modern, general-purpose Monte Carlo tool for simulating the transport of electrons and photons, which is applicable for arbitrary materials and in a wide energy range. PENELOPE provides quantitative guidance for many practical situations and techniques, including electron and X-ray spectroscopies, electron microscopy and microanalysis, biophysics, dosimetry, medical diagnostics and radiotherapy, as well as radiation damage and shielding. These proceedings contain the extensively revised teaching notes of the second workshop/training course on PENELOPE held in 2003, along with a detailed description of the improved physic models, numerical algorithms and structure of the code system. (author)

Electron tunneling transport across heterojunctions between europium sulfide and indium arsenide

Science.gov (United States)

Kallaher, Raymond L.

This dissertation presents research done on utilizing the ferromagnetic semiconductor europium sulfide (EuS) to inject spin polarized electrons into the non-magnetic semiconductor indium arsenide (InAs). There is great interest in expanding the functionality of modern day electronic circuits by creating devices that depend not only on the flow of charge in the device, but also on the transport of spin through the device. Within this mindset, there is a concerted effort to establish an efficient means of injecting and detecting spin polarized electrons in a two dimensional electron system (2DES) as the first step in developing a spin based field effect transistor. Thus, the research presented in this thesis has focused on the feasibility of using EuS, in direct electrical contact with InAs, as a spin injecting electrode into an InAs 2DES. Doped EuS is a concentrated ferromagnetic semiconductor, whose conduction band undergoes a giant Zeeman splitting when the material becomes ferromagnetic. The concomitant difference in energy between the spin-up and spin-down energy bands makes the itinerant electrons in EuS highly spin polarized. Thus, in principle, EuS is a good candidate to be used as an injector of spin polarized electrons into non-magnetic materials. In addition, the ability to adjust the conductivity of EuS by varying the doping level in the material makes EuS particularly suited for injecting spins into non-magnetic semiconductors and 2DES. For this research, thin films of EuS have been grown via e-beam evaporation of EuS powder. This growth technique produces EuS films that are sulfur deficient; these sulfur vacancies act as intrinsic electron donors and the resulting EuS films behave like heavily doped ferromagnetic semiconductors. The growth parameters and deposition procedures were varied and optimized in order to fabricate films that have minimal crystalline defects. Various properties and characteristics of these EuS films were measured and compared to

Accidents during transport of radioactive material

International Nuclear Information System (INIS)

Agarwal, S.P.

2008-01-01

Radioactive materials are a part of modern technology and life. They are used in medicine, industry, agriculture, research and electrical power generation. Tens of millions of packages containing radioactive materials are consigned for transport each year throughout the world. In India, about 80000 packages containing radioactive material are transported every year. The amount of radioactive material in these packages varies from negligible amounts used in consumer products to very large amounts in shipment of irradiator sources and spent nuclear fuel

Experimental study of fast electron transport in dense plasmas

International Nuclear Information System (INIS)

Vaisseau, Xavier

2014-01-01

The framework of this PhD thesis is the inertial confinement fusion for energy production, in the context of the electron fast ignition scheme. The work consists in a characterization of the transport mechanisms of fast electrons, driven by intense laser pulses (10 19 - 10 20 W/cm 2 ) in both cold-solid and warm-dense matter. The first goal was to study the propagation of a fast electron beam, characterized by a current density ≥ 10 11 A/cm 2 , in aluminum targets initially heated close to the Fermi temperature by a counter-propagative planar shock. The planar compression geometry allowed us to discriminate the energy losses due to the resistive mechanisms from collisional ones by comparing solid and compressed targets of the same initial areal densities. We observed for the first time a significant increase of resistive energy losses in heated aluminum samples. The confrontation of the experimental data with the simulations, including a complete characterization of the electron source, of the target compression and of the fast electron transport, allowed us to study the time-evolution of the material resistivity. The estimated resistive electron stopping power in a warm-compressed target is of the same order as the collisional one. We studied the transport of the fast electrons generated in the interaction of a high-contrast laser pulse with a hollow copper cone, buried into a carbon layer, compressed by a counter-propagative planar shock. A X-ray imaging system allowed us to visualize the coupling of the laser pulse with the cone at different moments of the compression. This diagnostic, giving access to the fast electron spatial distribution, showed a fast electron generation in the entire volume of the cone for late times of compression, after shock breakout from the inner cone tip. For earlier times, the interaction at a high-contrast ensured that the source was contained within the cone tip, and the fast electron beam was collimated into the target depth by

Physical protection of radioactive material in transport

International Nuclear Information System (INIS)

1975-01-01

Safety in the transport of radioactive material is ensured by enclosing the material, when necessary, in packaging which prevents its dispersal and which absorbs to any adequate extent any radiation emitted by the material. Transport workers, the general public and the environment are thus protected against the harmful effects of the radioactive material. The packaging also serves the purpose of protecting its contents against the effects of rough handling and mishaps under normal transport conditions, and against the severe stresses and high temperatures that could be encountered in accidents accompanied by fires. If the radioactive material is also fissile, special design features are incorporated to prevent any possibility of criticality under normal transport conditions and in accidents. The safe transport requirements are designed to afford protection against unintentional opening of packages in normal handling and transport conditions and against damage in severe accident conditions; whereas the physical protection requirements are designed to prevent intentional opening of packages and deliberate damage. This clearly illustrates the difference in philosophical approach underlying the requirements for safe transport and for physical protection during transport. This difference in approach is, perhaps, most easily seen in the differing requirements for marking of consignments. While safety considerations dictate that packages be clearly labelled, physical protection considerations urge restraint in the use of special labels. Careful consideration must be given to such differences in approach in any attempt to harmonize the safety and physical protection aspects of transport. (author)

Effect of room temperature lattice vibration on the electron transport in graphene nanoribbons

Science.gov (United States)

Liu, Yue-Yang; Li, Bo-Lin; Chen, Shi-Zhang; Jiang, Xiangwei; Chen, Ke-Qiu

2017-09-01

We observe directly the lattice vibration and its multifold effect on electron transport in zigzag graphene nanoribbons in simulation by utilizing an efficient combined method. The results show that the electron transport fluctuates greatly due to the incessant lattice vibration of the nanoribbons. More interestingly, the lattice vibration behaves like a double-edged sword that it boosts the conductance of symmetric zigzag nanoribbons (containing an even number of zigzag chains along the width direction) while weakens the conductance of asymmetric nanoribbons. As a result, the reported large disparity between the conductances of the two kinds of nanoribbons at 0 K is in fact much smaller at room temperature (300 K). We also find that the spin filter effect that exists in perfect two-dimensional symmetric zigzag graphene nanoribbons is destroyed to some extent by lattice vibrations. Since lattice vibrations or phonons are usually inevitable in experiments, the research is very meaningful for revealing the important role of lattice vibrations play in the electron transport properties of two-dimensional materials and guiding the application of ZGNRs in reality.

Transportation of radioactive materials. Safety and regulation

International Nuclear Information System (INIS)

Niel, Jean-Christophe

2013-01-01

This engineering-oriented publication first presents fluxes and risks related to the transportation of radioactive materials: fluxes, risks, in-depth defence, and parcel typology. The author then describes the elaboration process for transportation regulations: IAEA recommendations for the transportation of radioactive materials and their review process, IAEA recommendations for modal regulations. He presents the French transportation regulation framework: evolutions of IAEA recommendations, case of aerial transport, and case of maritime transport. The next part addresses the specific case of the transportation of uranium hexafluoride. The last part addresses incidents and accidents occurring during transportation: declarations to be made, brief presentations of several examples of incidents and accidents

Transport of radioactive materials

Energy Technology Data Exchange (ETDEWEB)

NONE

1960-04-15

The increasing use of radioactive substances, not only in reactor operations but also in medicine, industry and other fields, is making the movement of these materials progressively wider, more frequent and larger in volume. Although regulations for the safe transport of radioactive materials have been in existence for many years, it has now become necessary to modify or supplement the existing provisions on an international basis. It is essential that the regulations should be applied uniformly by all countries. It is also desirable that the basic regulations should be uniform for all modes of transport so as to simplify the procedures to be complied with by shippers and carriers

Replacing Electron Transport Cofactors with Hydrogenases

KAUST Repository

Laamarti, Rkia

2016-12-01

Enzymes have found applications in a broad range of industrial production processes. While high catalytic activity, selectivity and mild reaction conditions are attractive advantages of the biocatalysts, particularly costs arising from required cofactors pose a sever limitation. While cofactor-recycling systems are available, their use implies constraints for process set-up and conditions, which are a particular problem e.g. for solid-gas-phase reactions. Several oxidoreductases are able to directly exchange electrons with electrodes. Hence, the co-immobilization of both, an electron-utilizing and an electron-generating oxidoreductase on conductive nanoparticles should facilitate the direct electron flow from an enzymatic oxidation to a reduction reaction circumventing redox-cofactors requirements. In such a set-up, hydrogenases could generate and provide electrons directly form gaseous hydrogen. This thesis describes the co-immobilization of the oxygen tolerant hydrogenases from C. eutropha or C. metallidurans and cytochrome P450BM3 as test system. Conductive material in the form of carbon nanotubes (CNT) serves as a suitable support. A combination of the hydrogenase and the catalytic domain of P450BM3 immobilized on carbon nanotubes were tested for the oxidation of lauric acid in the presence of hydrogen instead of an electron-transport cofactor. The GC-MS analysis reveals the conversion of 4% of lauric acid (LA) into three products, which correspond to the hydroxylated lauric acid in three different positions with a total turnover (TON) of 34. The product distribution is similar to that obtained when using the wildtype P450BM3 with the nicotinamide adenine dinucleotide phosphate (NADPH) cofactor. Such electronic coupling couldn’t be achieved for the conversion of other substrates such as propane and cyclohexane, probably due to the high uncoupling rate within the heme-domain of cytochrome P450BM3 when unnatural substrates are introduced.

Achromatic and isochronous electron beam transport for tunable free electron lasers

International Nuclear Information System (INIS)

Bengtsson, J.; Kim, K.J.

1991-09-01

We have continued the study of a suitable electron beam transport line, which is both isochronous and achromatic, for the free electron laser being designed at Lawrence Berkeley Laboratory. A refined version of the beam transport optics is discussed that accommodates two different modes of FEL wavelength tuning. For the fine tuning involving a small change of the electron beam energy, sextupoles are added to cancel the leading nonlinear dispersion. For the main tuning involving the change of the undulator gap, a practical solution of maintaining the beam matching condition is presented. Calculation of the higher order aberrations is facilitated by a newly developed code. 11 refs., 4 figs., 3 tabs

Multi-scale modelling and numerical simulation of electronic kinetic transport

International Nuclear Information System (INIS)

Duclous, R.

2009-11-01

This research thesis which is at the interface between numerical analysis, plasma physics and applied mathematics, deals with the kinetic modelling and numerical simulations of the electron energy transport and deposition in laser-produced plasmas, having in view the processes of fuel assembly to temperature and density conditions necessary to ignite fusion reactions. After a brief review of the processes at play in the collisional kinetic theory of plasmas, with a focus on basic models and methods to implement, couple and validate them, the author focuses on the collective aspect related to the free-streaming electron transport equation in the non-relativistic limit as well as in the relativistic regime. He discusses the numerical development and analysis of the scheme for the Vlasov-Maxwell system, and the selection of a validation procedure and numerical tests. Then, he investigates more specific aspects of the collective transport: the multi-specie transport, submitted to phase-space discontinuities. Dealing with the multi-scale physics of electron transport with collision source terms, he validates the accuracy of a fast Monte Carlo multi-grid solver for the Fokker-Planck-Landau electron-electron collision operator. He reports realistic simulations for the kinetic electron transport in the frame of the shock ignition scheme, the development and validation of a reduced electron transport angular model. He finally explores the relative importance of the processes involving electron-electron collisions at high energy by means a multi-scale reduced model with relativistic Boltzmann terms

Magnetic turbulent electron transport in a reversed field pinch

International Nuclear Information System (INIS)

Schoenberg, K.; Moses, R.

1990-01-01

A model of magnetic turbulent electron transport is presented. The model, based on the thermal conduction theory of Rechester and Rosenbluth, entails a Boltzmann description of electron dynamics in the long mean-free-path limit and quantitatively describes the salient features of superthermal electron measurements in the RFP edge plasma. Included are predictions of the mean superthermal electron energy, current density, and power flux asymmetry. A discussion of the transport model, the assumptions implicit in the model, and the relevance of this work to more general issue of magnetic turbulent transport in toroidal systems is presented. 32 refs., 3 figs

Electronic transport properties of fullerene functionalized carbon nanotubes: Ab initio and tight-binding calculations

DEFF Research Database (Denmark)

Fürst, Joachim Alexander; Hashemi, J.; Markussen, Troels

2009-01-01

Fullerene functionalized carbon nanotubes-NanoBuds-form a novel class of hybrid carbon materials, which possesses many advantageous properties as compared to the pristine components. Here, we report a theoretical study of the electronic transport properties of these compounds. We use both ab init...

Electron transport chains in organohalide-respiring bacteria and bioremediation implications.

Science.gov (United States)

Wang, Shanquan; Qiu, Lan; Liu, Xiaowei; Xu, Guofang; Siegert, Michael; Lu, Qihong; Juneau, Philippe; Yu, Ling; Liang, Dawei; He, Zhili; Qiu, Rongliang

2018-04-06

In situ remediation employing organohalide-respiring bacteria represents a promising solution for cleanup of persistent organohalide pollutants. The organohalide-respiring bacteria conserve energy by utilizing H 2 or organic compounds as electron donors and organohalides as electron acceptors. Reductive dehalogenase (RDase), a terminal reductase of the electron transport chain in organohalide-respiring bacteria, is the key enzyme that catalyzes halogen removal. Accumulating experimental evidence thus far suggests that there are distinct models for respiratory electron transfer in organohalide-respirers of different lineages, e.g., Dehalococcoides, Dehalobacter, Desulfitobacterium and Sulfurospirillum. In this review, to connect the knowledge in organohalide-respiratory electron transport chains to bioremediation applications, we first comprehensively review molecular components and their organization, together with energetics of the organohalide-respiratory electron transport chains, as well as recent elucidation of intramolecular electron shuttling and halogen elimination mechanisms of RDases. We then highlight the implications of organohalide-respiratory electron transport chains in stimulated bioremediation. In addition, major challenges and further developments toward understanding the organohalide-respiratory electron transport chains and their bioremediation applications are identified and discussed. Copyright © 2018 Elsevier Inc. All rights reserved.

Monte Carlo Simulation of Electron Transport in 4H- and 6H-SiC

International Nuclear Information System (INIS)

Sun, C. C.; You, A. H.; Wong, E. K.

2010-01-01

The Monte Carlo (MC) simulation of electron transport properties at high electric field region in 4H- and 6H-SiC are presented. This MC model includes two non-parabolic conduction bands. Based on the material parameters, the electron scattering rates included polar optical phonon scattering, optical phonon scattering and acoustic phonon scattering are evaluated. The electron drift velocity, energy and free flight time are simulated as a function of applied electric field at an impurity concentration of 1x10 18 cm 3 in room temperature. The simulated drift velocity with electric field dependencies is in a good agreement with experimental results found in literature. The saturation velocities for both polytypes are close, but the scattering rates are much more pronounced for 6H-SiC. Our simulation model clearly shows complete electron transport properties in 4H- and 6H-SiC.

Problems of linear electron (polaron) transport theory in semiconductors

CERN Document Server

Klinger, M I

1979-01-01

Problems of Linear Electron (Polaron) Transport Theory in Semiconductors summarizes and discusses the development of areas in electron transport theory in semiconductors, with emphasis on the fundamental aspects of the theory and the essential physical nature of the transport processes. The book is organized into three parts. Part I focuses on some general topics in the theory of transport phenomena: the general dynamical theory of linear transport in dissipative systems (Kubo formulae) and the phenomenological theory. Part II deals with the theory of polaron transport in a crystalline semicon

Transportation of hazardous materials (hazmat) a literature survey

OpenAIRE

Zafer YILMAZ; Serpil EROL; Hakan Soner APLAK

2016-01-01

ransportation has a great role in logistics. Many researchers have studied on transportation and vehicle routing problems. Transportation of hazardous materials (hazmat) is a special subject for logistics. Causalities due to the accidents caused by trucks carrying hazardous materials will be intolerable. Many researchers have studied on risk assessment of hazmat transportation to find ways for reducing hazardous material transportation risks. Some researchers have studied routing of hazmat tr...

Phonon limited electronic transport in Pb

DEFF Research Database (Denmark)

Rittweger, Florian; Hinsche, Nicki Frank; Mertig, Ingrid

2017-01-01

We present a fully ab initio based scheme to compute electronic transport properties, i.e. the electrical conductivity σ and thermopower S, in the presence of electron-phonon interaction. We explicitly investigate the k-dependent structure of the Éliashberg spectral function, the coupling strength...

Fast electron generation and transport in a turbulent, magnetized plasma

International Nuclear Information System (INIS)

Stoneking, W.R.

1994-05-01

The nature of fast electron generation and transport in the Madison Symmetric Torus (MST) reversed field pinch (RFP) is investigated using two electron energy analyzer (EEA) probes and a thermocouple calorimeter. The parallel velocity distribution of the fast electron population is well fit by a drifted Maxwellian distribution with temperature of about 100 eV and drift velocity of about 2 x 10 6 m/s. Cross-calibration of the EEA with the calorimeter provides a measurement of the fast electron perpendicular temperature of 30 eV, much lower than the parallel temperature, and is evidence that the kinetic dynamo mechanism (KDT) is not operative in MST. The fast electron current is found to match to the parallel current at the edge, and the fast electron density is about 4 x 10 11 cm -3 independent of the ratio of the applied toroidal electric field to the critical electric field for runaways. First time measurements of magnetic fluctuation induced particle transport are reported. By correlating electron current fluctuations with radial magnetic fluctuations the transported flux of electrons is found to be negligible outside r/a∼0.9, but rises the level of the expected total particle losses inside r/a∼0.85. A comparison of the measured diffusion coefficient is made with the ausilinear stochastic diffusion coefficient. Evidence exists that the reduction of the transport is due to the presence of a radial ambipolar electric field of magnitude 500 V/m, that acts to equilibrate the ion and electron transport rates. The convective energy transport associated with the measured particle transport is large enough to account for the observed magnetic fluctuation induced energy transport in MST

Compression of pulsed electron beams for material tests

Science.gov (United States)

Metel, Alexander S.

2018-03-01

In order to strengthen the surface of machine parts and investigate behavior of their materials exposed to highly dense energy fluxes an electron gun has been developed, which produces the pulsed beams of electrons with the energy up to 300 keV and the current up to 250 A at the pulse width of 100-200 µs. Electrons are extracted into the accelerating gap from the hollow cathode glow discharge plasma through a flat or a spherical grid. The flat grid produces 16-cm-diameter beams with the density of transported per one pulse energy not exceeding 15 J·cm-2, which is not enough even for the surface hardening. The spherical grid enables compression of the beams and regulation of the energy density from 15 J·cm-2 up to 15 kJ·cm-2, thus allowing hardening, pulsed melting of the machine part surface with the further high-speed recrystallization as well as an explosive ablation of the surface layer.

Transportation of hazardous materials (hazmat a literature survey

Directory of Open Access Journals (Sweden)

Zafer YILMAZ

2016-02-01

Full Text Available ransportation has a great role in logistics. Many researchers have studied on transportation and vehicle routing problems. Transportation of hazardous materials (hazmat is a special subject for logistics. Causalities due to the accidents caused by trucks carrying hazardous materials will be intolerable. Many researchers have studied on risk assessment of hazmat transportation to find ways for reducing hazardous material transportation risks. Some researchers have studied routing of hazmat trucks. The emergency response models and network design problems for hazmat transportation were also studied by some researchers. The transportation of hazmats can also be classified according to the mode of transport. Mainly roads are used for hazmat transportation but some shipments are intermodal. There has been a great amount of effort spent to find convenient ways for hazmat transportation. In this study, a literature survey for the articles about hazmat transportation is prepared. After pointing out the importance of hazmat transportation by the example of US hazmat transportation data, the studies on hazmat transportation since 2005 have been examined. Totally 88 articles are classified as risk, routing, routing and scheduling, emergency response, network design and accident analysis. What can be studied in future researches is pointed out.Keywords: Hazardous materials, Network design, Transportation, Routing, Risk assessment

Transport of radioactive material in Canada

International Nuclear Information System (INIS)

1997-09-01

In this report, the Advisory Committee on Nuclear Safety (ACNS) presents the results of its study on how the system of the transport of radioactive material (TRM) in Canada is regulated, how it operates, and how it performs. The report deals with the transport of packages, including Type B packages which are used to carry large quantities of radioactive material, but not with the transport of spent nuclear fuel or with the transport of low-level historical waste. The ACNS has examined the Canadian experience in the TRM area, the regulatory framework in Canada with respect to the TRM some relevant aspects of training workers and monitoring compliance with regulatory requirements, the state of the emergency preparedness of organizations involved in the TRM and the process of updating present regulations by the Atomic Energy Control Board (AECB). As a result of this study, the ACNS concludes that the current Canadian regulatory system in the TRM is sound and that the TRM is, for the most part, conducted safely. However, improvements can be made in a number of areas, such as: determining the exposures of workers who transport radioactive material; rewording the proposed Transport Regulations in plain language; training all appropriate personnel regarding the AECB and Transport Canada (TC) Regulations; enforcing compliance with the regulations; and increasing the level of cooperation between the federal agencies and provincial authorities involved in the inspection and emergency preparedness aspects of the TRM. It is also noted that Bill C-23, the Nuclear Safety and Control Act, imposes a new requirement, subject to the Regulations, for a licence for a carrier to transport some types of radioactive material

Transport of radioactive material in Canada

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-09-01

In this report, the Advisory Committee on Nuclear Safety (ACNS) presents the results of its study on how the system of the transport of radioactive material (TRM) in Canada is regulated, how it operates, and how it performs. The report deals with the transport of packages, including Type B packages which are used to carry large quantities of radioactive material, but not with the transport of spent nuclear fuel or with the transport of low-level historical waste. The ACNS has examined the Canadian experience in the TRM area, the regulatory framework in Canada with respect to the TRM some relevant aspects of training workers and monitoring compliance with regulatory requirements, the state of the emergency preparedness of organizations involved in the TRM and the process of updating present regulations by the Atomic Energy Control Board (AECB). As a result of this study, the ACNS concludes that the current Canadian regulatory system in the TRM is sound and that the TRM is, for the most part, conducted safely. However, improvements can be made in a number of areas, such as: determining the exposures of workers who transport radioactive material; rewording the proposed Transport Regulations in plain language; training all appropriate personnel regarding the AECB and Transport Canada (TC) Regulations; enforcing compliance with the regulations; and increasing the level of cooperation between the federal agencies and provincial authorities involved in the inspection and emergency preparedness aspects of the TRM. It is also noted that Bill C-23, the Nuclear Safety and Control Act, imposes a new requirement, subject to the Regulations, for a licence for a carrier to transport some types of radioactive material.

Legal aspects of radioactice materials transport

International Nuclear Information System (INIS)

Frejman, Eh.S.

1986-01-01

The main statements of the Safety rules for radioactive materials transport PBTRV-73 applied in the USSR are considered. The rules cover the whole complex of security measures at all the stages of radioactive materials transprt including requirements to packaging, radiation monitoring, measures of individual protection and personal hygiene, measures at accidents and fires. Separate rules for radioactive materials handling when using rail, air, maritime and road transports are developed on the basis of this document

Monte Carlo transport of electrons and positrons through thin foils

International Nuclear Information System (INIS)

Legarda, F.; Idoeta, R.

2000-01-01

In the different measurements made with electrons traversing matter it becomes useful the knowledge of its transmission through that medium, their paths and their angular distribution through matter so as to process and get information about the traversed medium and to improve and innovate the techniques that employ electrons, as medical applications or materials irradiation. This work presents a simulation of the transport of beams of electrons and positrons through thin foils using an analog Monte Carlo code that simulates in a detailed way every electron movement or interaction in matter. As those particles penetrate thin absorbers it has been assumed that they interact with matter only through elastic scattering, with negligible energy loss. This type of interaction has been described quite precisely because its angular form influences very much the angular distribution of electrons and positrons in matter. With this code it has been calculated the number of particles, with energies between 100 and 3000 keV, that are transmitted through different media of various thicknesses as well as its angular distribution, showing a good agreement with experimental data. The discrepancies are less than 5% for thicknesses lower than about 30% of the corresponding range in the tested material. As elastic scattering is very anisotropic, angular distributions resemble a collimated incident beam for very thin foils becoming slowly more isotropic when absorber thickness is increased. (author)

Transport of radioactive material in Bangladesh: a regulatory perspective

International Nuclear Information System (INIS)

Mollah, A.S.

2004-01-01

Radioactive material is transported in Bangladesh in various types of packages and by different modes of transport. The transport of radioactive materials involves a risk both for the workers and members of the public. The safe transport of radioactive material is ensured in Bangladesh by compliance with Nuclear Safety and Radiation Control (NSRC) Act-93 and NSRC Rules-97. The Bangladesh Atomic Energy Commission (BAEC) is the competent authority for the enforcement of the NSRC act and rules. The competent authority has established regulatory control at each stage to ensure radiation safety to transport workers, members of general public and the environment. An overview is presented of the activities related to the transport of radioactive material in Bangladesh. In particular, the applicable legislation, the scope of authority and the regulatory functions of the competent authority are discussed. The categories of radioactive materials transported and the packaging requirements for the safe transport of these radioactive materials are also described. (author)

Ontario hydro radioactive material transportation field guide

International Nuclear Information System (INIS)

Howe, W.

1987-01-01

The recent introduction of both the AECB Transport Packaging of Radioactive Material Regulations and Transport Canada's Transportation of Dangerous Goods Regulations have significantly altered the requirements for transporting radioactive material in Canada. Extensive additional training as well as certification of several hundred Ontario Hydro employees has been necessary to ensure compliance with the additional and revised regulatory requirements. To assist in the training of personnel, an 'active' corporate Ontario Hydro Field Guide for Radioactive Material Transport document has been developed and published. The contents of this Field Guide identify current Ontario Hydro equipment and procedures as well as the updated relevant regulatory requirements within Canada. In addition, to satisfying Ontario Hydro requirements for this type of information over two thousand of these Field Guides have been provided to key emergency response personnel throughout the province of Ontario to assist in their transportation accident response training

Study of transmission function and electronic transport in one dimensional silver nanowire: Ab-initio method using density functional theory (DFT)

Science.gov (United States)

Thakur, Anil; Kashyap, Rajinder

2018-05-01

Single nanowire electrode devices have their application in variety of fields which vary from information technology to solar energy. Silver nanowires, made in an aqueous chemical reduction process, can be reacted with gold salt to create bimetallic nanowires. Silver nanowire can be used as electrodes in batteries and have many other applications. In this paper we investigated structural and electronic transport properties of Ag nanowire using density functional theory (DFT) with SIESTA code. Electronic transport properties of Ag nanowire have been studied theoretically. First of all an optimized geometry for Ag nanowire is obtained using DFT calculations, and then the transport relations are obtained using NEGF approach. SIESTA and TranSIESTA simulation codes are used in the calculations respectively. The electrodes are chosen to be the same as the central region where transport is studied, eliminating current quantization effects due to contacts and focusing the electronic transport study to the intrinsic structure of the material. By varying chemical potential in the electrode regions, an I-V curve is traced which is in agreement with the predicted behavior. Bulk properties of Ag are in agreement with experimental values which make the study of electronic and transport properties in silver nanowires interesting because they are promising materials as bridging pieces in nanoelectronics. Transmission coefficient and V-I characteristic of Ag nano wire reveals that silver nanowire can be used as an electrode device.

Fast Crystallization and improved Stability of Perovskite Solar Cells with Zn 2 SnO 4 Electron Transporting Layer: Interface Matters

KAUST Repository

Bera, Ashok

2015-12-03

Here we report that mesoporous ternary oxide Zn2SnO4 can significantly promotes the crystallization of hybrid perovskite layers and serves as an efficient electron transporting material in perovskite solar cells. Such devices exhibit an energy conversion efficiency of 13.34%, which is even higher than that achieved with the commonly used TiO2 in the similar experimental conditions (9.1%). Simple one-step spin coating of CH3NH3PbI3−xClx on Zn2SnO4 is found to lead to rapidly crystalized bilayer perovskite structure without any solvent engineering. Furthermore, ultrafast transient absorption measurement reveals efficient charge transfer at the Zn2SnO4/perovskite interface. Most importantly, solar cells with Zn2SnO4 as the electron-transporting material exhibit negligible electrical hysteresis and exceptionally high stability without encapsulation for over one month. Besides underscoring Zn2SnO4 as a highly promising electron transporting material for perovskite solar cells, our results demonstrate the significant role of interfaces on improving the perovskite crystallization and photovoltaic performance.

Attosecond Electron Processes in Materials: Excitons, Plasmons, and Charge Dynamics

Science.gov (United States)

2015-05-19

focused using a f=1.5 m lens into a 250 micron hollow core fiber (HCF) filled with neon gas at atmospheric pressure to stretch the pulse spectrum from... insulator to metal transition. Introduction: The goal of this work was to understand the generation, transport, and manipulation of electronic charge...chemically sensitive probe pulse utilizing specific core level transitions in atoms that are part of a material under study. The measurements follow

The safety of radioactive materials transport

International Nuclear Information System (INIS)

Niel, J.Ch.

1997-01-01

Five accidents in radioactive materials transport have been studied; One transport accident by road, one by ship, one by rail, and the two last in handling materials from ships in Cherbourg port and Le Havre port. All these accidents were without any important consequences in term of radiation protection, but they were sources of lessons to improve the safety. (N.C.)

Electronic materials

CERN Document Server

Kwok, H L

2010-01-01

The electronic properties of solids have become of increasing importance in the age of information technology. The study of solids and materials, while having originated from the disciplines of physics and chemistry, has evolved independently over the past few decades. The classical treatment of solid-state physics, which emphasized classifications, theories and fundamental physical principles, is no longer able to bridge the gap between materials advances and applications. In particular, the more recent developments in device physics and technology have not necessarily been driven by new conc

Electron thermal transport in tokamak plasmas

Energy Technology Data Exchange (ETDEWEB)

Konings, J A

1994-11-30

The process of fusion of small nuclei thereby releasing energy, as it occurs continuously in the sun, is essential for the existence of mankind. The same process applied in a controlled way on earth would provide a clean and an abundant energy source, and be the long term solution of the energy problem. Nuclear fusion requires an extremely hot (10{sup 8} K) ionized gas, a plasma, that can only be maintained if it is kept insulated from any material wall. In the so called `tokamak` this is achieved by using magnetic fields. The termal insulation, which is essential if one wants to keep the plasma at the high `fusion` temperature, can be predicted using basic plasma therory. A comparison with experiments in tokamaks, however, showed that the electron enery losses are ten to hundred times larger than this theory predicts. This `anomalous transport` of thermal energy implies that, to reach the condition for nuclear fusion, a fusion reactor must have very large dimensions. This may put the economic feasibility of fusion power in jeopardy. Therefore, in a worldwide collaboration, physicists study tokamak plasmas in an attempt to understand and control the energy losses. From a scientific point of view, the mechanisms driving anomalous transport are one of the challenges in fudamental plasma physics. In Nieuwegein, a tokamak experiment (the Rijnhuizen Tokamak Project, RTP) is dedicated to the study of anomalous transport, in an international collaboration with other laboratories. (orig./WL).

Sputter Deposited TiOx Thin-Films as Electron Transport Layers in Organic Solar Cells

DEFF Research Database (Denmark)

Mirsafaei, Mina; Bomholt Jensen, Pia; Lakhotiya, Harish

transparency and favorable energy-level alignment with many commonly used electron-acceptor materials. There are several methods available for fabricating compact TiOx thin-films for use in organic solar cells, including sol-gel solution processing, spray pyrolysis and atomic-layer deposition; however...... of around 7%, by incorporating sputter deposited TiOx thin-films as electron-transport and exciton-blocking layers. In the work, we report on the effect of different TiOx deposition temperatures and thicknesses on the organic-solar-cell device performance. Besides optical characterization, AFM and XRD...... analyses are performed to characterize the morphology and crystal structure of the films, and external quantum efficiency measurements are employed to shed further light on the device performance. Our study presents a novel method for implementation of TiOx thin-films as electron-transport layer in organic...

Epitaxial Graphene: A New Material for Electronics

Science.gov (United States)

de Heer, Walt A.

2007-10-01

Graphene multilayers are grown epitaxially on single crystal silicon carbide. This system is composed of several graphene layers of which the first layer is electron doped due to the built-in electric field and the other layers are essentially undoped. Unlike graphite the charge carriers show Dirac particle properties (i.e. an anomalous Berry's phase, weak anti-localization and square root field dependence of the Landau level energies). Epitaxial graphene shows quasi-ballistic transport and long coherence lengths; properties that may persists above cryogenic temperatures. Paradoxically, in contrast to exfoliated graphene, the quantum Hall effect is not observed in high mobility epitaxial graphene. It appears that the effect is suppressed due to absence of localized states in the bulk of the material. Epitaxial graphene can be patterned using standard lithography methods and characterized using a wide array of techniques. These favorable features indicate that interconnected room temperature ballistic devices may be feasible for low dissipation high-speed nano-electronics.

Lipid Bilayer Formation on Organic Electronic Materials

KAUST Repository

Zhang, Yi

2018-04-23

The lipid bilayer is the elemental structure of cell membrane, forming a stable barrier between the interior and exterior of the cell while hosting membrane proteins that enable selective transport of biologically important compounds and cellular recognition. Monitoring the quality and function of lipid bilayers is thus essential and can be performed using electrically active substrates that allow for transduction of signals. Such a promising electronic transducer material is the conducting polymer poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) which has provided a plethora of novel bio transducing architectures. The challenge is however in assembling a bilayer on the conducting polymer surface, which is defect-free and has high mobility. Herein, we investigate the fusion of zwitterionic vesicles on a variety of PEDOT:PSS films, but also on an electron transporting, negatively charged organic semiconductor, in order to understand the surface properties that trigger vesicle fusion. The PEDOT:PSS films are prepared from dispersions containing different concentrations of ethylene glycol included as a formulation additive, which gives a handle to modulate surface physicochemical properties without a compromise on the chemical composition. The strong correlation between the polarity of the surface, the fusion of vesicles and the mobility of the resulting bilayer aides extracting design principles for the development of future conducting polymers that will enable the formation of lipid bilayers.

Electron transport through monovalent atomic wires

DEFF Research Database (Denmark)

Lee, Y. J.; Brandbyge, Mads; Puska, M. J.

2004-01-01

at the chain determine the conductance. As a result, the conductance for noble-metal chains is close to one quantum of conductance, and it oscillates moderately so that an even number of chain atoms yields a higher value than an odd number. The conductance oscillations are large for alkali-metal chains......Using a first-principles density-functional method we model electron transport through linear chains of monovalent atoms between two bulk electrodes. For noble-metal chains the transport resembles that for free electrons over a potential barrier whereas for alkali-metal chains resonance states...... and their phase is opposite to that of noble-metal chains....

Transport anomalies and quantum criticality in electron-doped cuprate superconductors

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xu; Yu, Heshan; He, Ge; Hu, Wei; Yuan, Jie; Zhu, Beiyi [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Jin, Kui, E-mail: kuijin@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100190 (China)

2016-06-15

Highlights: • Electrical transport and its complementary thermal transport on electron-doped cuprates are reviewed. • The common features of electron-doped cuprates are sorted out and shown in the last figure. • The complex superconducting fluctuations and quantum fluctuations are distinguished. - Abstract: Superconductivity research is like running a marathon. Three decades after the discovery of high-T{sub c} cuprates, there have been mass data generated from transport measurements, which bring fruitful information. In this review, we give a brief summary of the intriguing phenomena reported in electron-doped cuprates from the aspect of electrical transport as well as the complementary thermal transport. We attempt to sort out common features of the electron-doped family, e.g. the strange metal, negative magnetoresistance, multiple sign reversals of Hall in mixed state, abnormal Nernst signal, complex quantum criticality. Most of them have been challenging the existing theories, nevertheless, a unified diagram certainly helps to approach the nature of electron-doped cuprates.

Regulations related to the transport of radioactive material in Brazil

International Nuclear Information System (INIS)

Sahyun, Adelia; Sordi, Gian-Maria A.A.; Sanches, Matias P.

2001-01-01

The transport of radioactive material has raised great interest on the part of national regulatory authorities, thus resulting in a safety measures improvement for all kinds of transportation. The transport of radioactive material is regulated by safety criteria much more than those applied to conventional hazardous material. All radioactive material transportation run in Brazilian territory must be in accordance with what is established by the CNEN-NE 5.01 - Transport of Radioactive Material. There are other national and international regulations for radioactive material transportation, which have to be accomplished with and adopted during the operation of radioactive material transportation. The aim of this paper is to verify the criteria set up in the existing regulations and propose a consensus for all the intervening organizations in the regulation process for land, air or sea transportation. This kind of transportation can not depend on the efforts of only one person, a group of workers or even any governmental body, but must be instead a shared responsibility among workers, transport firms and all regulative transportation organizations. (author)

Regulations related to the transport of radioactive material in Brazil

Energy Technology Data Exchange (ETDEWEB)

Sahyun, Adelia; Sordi, Gian-Maria A.A. [ATOMO Radioprotecao e Seguranca Nuclear, Sao Paulo, SP (Brazil)]. E-mail: atomo@atomo.com.br; Sanches, Matias P. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: msanches@net.ipen.br

2001-07-01

The transport of radioactive material has raised great interest on the part of national regulatory authorities, thus resulting in a safety measures improvement for all kinds of transportation. The transport of radioactive material is regulated by safety criteria much more than those applied to conventional hazardous material. All radioactive material transportation run in Brazilian territory must be in accordance with what is established by the CNEN-NE 5.01 - Transport of Radioactive Material. There are other national and international regulations for radioactive material transportation, which have to be accomplished with and adopted during the operation of radioactive material transportation. The aim of this paper is to verify the criteria set up in the existing regulations and propose a consensus for all the intervening organizations in the regulation process for land, air or sea transportation. This kind of transportation can not depend on the efforts of only one person, a group of workers or even any governmental body, but must be instead a shared responsibility among workers, transport firms and all regulative transportation organizations. (author)

Graphene for amino acid biosensing: Theoretical study of the electronic transport

Science.gov (United States)

Rodríguez, S. J.; Makinistian, L.; Albanesi, E. A.

2017-10-01

The study of biosensors based on graphene has increased in the last years, the combination of excellent electrical properties and low noise makes graphene a material for next generation electronic devices. This work discusses the application of a graphene-based biosensor for the detection of amino acids histidine (His), alanine (Ala), aspartic acid (Asp), and tyrosine (Tyr). First, we present the results of modeling from first principles the adsorption of the four amino acids on a graphene sheet, we calculate adsorption energy, substrate-adsorbate distance, equilibrium geometrical configurations (upon relaxation) and densities of states (DOS) for each biomolecule adsorbed. Furthermore, in order to evaluate the effects of amino acid adsorption on the electronic transport of graphene, we modeled a device using first-principles calculations with a combination of Density Functional Theory (DFT) and Nonequilibrium Greens Functions (NEGF). We provide with a detailed discussion in terms of transmission, current-voltage curves, and charge transfer. We found evidence of differences in the electronic transport through the graphene sheet due to amino acid adsorption, reinforcing the possibility of graphene-based sensors for amino acid sequencing of proteins.

Sub-electron transport in single-electron-tunneling arrays

Science.gov (United States)

Kaplan, Daniel; Sverdlov, Viktor; Korotkov, Alexander; Likharev, Konstantin

2002-03-01

We have analyzed quasi-continuous charge transport in two-dimensional tunnel junction arrays with a special distribution of background charges, providing a complete suppression of Coulomb blockade thresholds of tunneling between any pair of islands. Numerical simulations show that at low currents the dc I-V curve is indeed linear, while the shot noise is strongly suppressed and approaches 1/N of the Schottky value (where N is the array length). Thus both conditions of quasi-continuous transport, formulated earlier by Matsuoka and Likharev (Phys. Rev. B, v57, 15613, 1998), are satisfied. At higher fields the electron-hole pair production begins, and shot noise grows sharply. At higher voltages still, the array enters the "plasma" regime (with nearly balanced number of electrons and holes) and the Fano factor drops to 1/N once again. We have studied the resulting shot noise peak in detail, and concluded that its physics is close to that of critical opalescence.

Radioactive Material (Road Transport) Act 1991

International Nuclear Information System (INIS)

1991-01-01

This Act came into force on 27 August 1991. It replaces earlier legislation dating from 1948 and enables the United Kingdom to give effect to the International Atomic Energy Agency's (IAEA) latest recommended Regulations for the Safe Transport of Radioactive Material. The new Act clarifies and extends the power of the Secretary of State to make regulations regarding, among other things, the design, labelling, handling, transport and delivery of packages containing radioactive material and the placarding of vehicles transporting such packages. The Act gives the Secretary of State the power to appoint inspectors to assist him in enforcing the regulations. (NEA)

Storage and transport of hazardous materials

International Nuclear Information System (INIS)

Jaeger, P.; Haferkamp, K.

1986-01-01

The attempt has been made to characterise the present risk scenario, and to set out approaches or methods for remedy and risk control. For this purpose, a retrospective analysis has been made of accidents, damage and consequential damage that occurred in the past either during storage of hazardous materials, or during road transport. A risk-benefit model facilitates assessment of accident frequency. The history of accidents during storage or transport allows assessment of the dangerousness of various materials. Another important aspect discussed is the property and behaviour of containers used for storage or transport. (DG) [de

Electron-hole collision limited transport in charge-neutral bilayer graphene

Science.gov (United States)

Nam, Youngwoo; Ki, Dong-Keun; Soler-Delgado, David; Morpurgo, Alberto F.

2017-12-01

Ballistic transport occurs whenever electrons propagate without collisions deflecting their trajectory. It is normally observed in conductors with a negligible concentration of impurities, at low temperature, to avoid electron-phonon scattering. Here, we use suspended bilayer graphene devices to reveal a new regime, in which ballistic transport is not limited by scattering with phonons or impurities, but by electron-hole collisions. The phenomenon manifests itself in a negative four-terminal resistance that becomes visible when the density of holes (electrons) is suppressed by gate-shifting the Fermi level in the conduction (valence) band, above the thermal energy. For smaller densities, transport is diffusive, and the measured conductivity is reproduced quantitatively, with no fitting parameters, by including electron-hole scattering as the only process causing velocity relaxation. Experiments on a trilayer device show that the phenomenon is robust and that transport at charge neutrality is governed by the same physics. Our results provide a textbook illustration of a transport regime that had not been observed previously and clarify the nature of conduction through charge-neutral graphene under conditions in which carrier density inhomogeneity is immaterial. They also demonstrate that transport can be limited by a fully electronic mechanism, originating from the same microscopic processes that govern the physics of Dirac-like plasmas.

Safe Transport of Radioactive Material, Philosophy and Overview

Energy Technology Data Exchange (ETDEWEB)

EL-Shinawy, R M.K. [Radiation Protection Dept., Nuclear Rasearch Center, Atomic Energy Authority, Cairo (Egypt)

2008-07-01

Safe transport of radioactive material regulations issued by IAEA since 1961, provide standards for insuring a high level of safety of people,transport workers, property and environment against radiation, contamination and criticality hazards as well as thermal effects associated with the transport of the radioactive wastes and material. The history ,development, philosophy and scope of these international and national regulations were mentioned as well as the different supporting documents to the regulations for safe transport of radioactive material were identified.The first supporting document , namely TS - G-1.1(ST-2) ,Advisory material is also issued by the IAEA.It contains both the advisory and explanatory materials previously published in safety series Nos 7and 37 and therefore TS-G-1.1 (ST-2) will supersede safety series Nos 7 and 37. The second supporting document namely TS-G-1.2 (ST-3), planning and preparing for emergency response to transport accidents involving radioactive material ,which will supersede safety series No 87. In addition to quality assurance (SS no.113), compliance assurance (SS no. 112), the training manual and others.

Safe Transport of Radioactive Material, Philosophy and Overview

International Nuclear Information System (INIS)

EL-Shinawy, R.M.K.

2008-01-01

Safe transport of radioactive material regulations issued by IAEA since 1961, provide standards for insuring a high level of safety of people,transport workers, property and environment against radiation, contamination and criticality hazards as well as thermal effects associated with the transport of the radioactive wastes and material. The history ,development, philosophy and scope of these international and national regulations were mentioned as well as the different supporting documents to the regulations for safe transport of radioactive material were identified.The first supporting document , namely TS - G-1.1(ST-2) ,Advisory material is also issued by the IAEA.It contains both the advisory and explanatory materials previously published in safety series Nos 7and 37 and therefore TS-G-1.1 (ST-2) will supersede safety series Nos 7 and 37. The second supporting document namely TS-G-1.2 (ST-3), planning and preparing for emergency response to transport accidents involving radioactive material ,which will supersede safety series No 87. In addition to quality assurance (SS no.113), compliance assurance (SS no. 112), the training manual and others

Electron transport and nonlinear optical properties of substituted aryldimesityl boranes: a DFT study.

Directory of Open Access Journals (Sweden)

Altaf Hussain Pandith

Full Text Available A comprehensive theoretical study was carried out on a series of aryldimesityl borane (DMB derivatives using Density Functional theory. Optimized geometries and electronic parameters like electron affinity, reorganization energy, frontiers molecular contours, polarizability and hyperpolarizability have been calculated by employing B3PW91/6-311++G (d, p level of theory. Our results show that the Hammett function and geometrical parameters correlates well with the reorganization energies and hyperpolarizability for the series of DMB derivatives studied in this work. The orbital energy study reveals that the electron releasing substituents increase the LUMO energies and electron withdrawing substituents decrease the LUMO energies, reflecting the electron transport character of aryldimesityl borane derivatives. From frontier molecular orbitals diagram it is evident that mesityl rings act as the donor, while the phenylene and Boron atom appear as acceptors in these systems. The calculated hyperpolarizability of secondary amine derivative of DMB is 40 times higher than DMB (1. The electronic excitation contributions to the hyperpolarizability studied by using TDDFT calculation shows that hyperpolarizability correlates well with dipole moment in ground and excited state and excitation energy in terms of the two-level model. Thus the results of these calculations can be helpful in designing the DMB derivatives for efficient electron transport and nonlinear optical material by appropriate substitution with electron releasing or withdrawing substituents on phenyl ring of DMB system.

Electronic transport in organometallic perovskite CH{sub 3}NH{sub 3}PbI{sub 3}: The role of organic cation orientations

Energy Technology Data Exchange (ETDEWEB)

Berdiyorov, G. R., E-mail: gberdiyorov@qf.org.qa; El-Mellouhi, F.; Madjet, M. E.; Rashkeev, S. N. [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, Doha (Qatar); Alharbi, F. H. [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, Doha (Qatar); College of Science and Engineering, Hamad Bin Khalifa University, Doha (Qatar)

2016-02-01

Density functional theory in combination with the nonequilibrium Green's function formalism is used to study the electronic transport properties of methylammonium lead-iodide perovskite CH{sub 3}NH{sub 3}PbI{sub 3}. Electronic transport in homogeneous ferroelectric and antiferroelectric phases, both of which do not contain any charged domain walls, is quite similar. The presence of charged domain wall drastically (by about an order of magnitude) enhances the electronic transport in the lateral direction. The increase of the transmission originates from the smaller variation of the electrostatic potential profile along the charged domain walls. This fact may provide a tool for tuning transport properties of such hybrid materials by manipulating molecular cations having dipole moment.

Molecular electronics: some views on transport junctions and beyond.

Science.gov (United States)

Joachim, Christian; Ratner, Mark A

2005-06-21

The field of molecular electronics comprises a fundamental set of issues concerning the electronic response of molecules as parts of a mesoscopic structure and a technology-facing area of science. We will overview some important aspects of these subfields. The most advanced ideas in the field involve the use of molecules as individual logic or memory units and are broadly based on using the quantum state space of the molecule. Current work in molecular electronics usually addresses molecular junction transport, where the molecule acts as a barrier for incoming electrons: This is the fundamental Landauer idea of "conduction as scattering" generalized to molecular junction structures. Another point of view in terms of superexchange as a guiding mechanism for coherent electron transfer through the molecular bridge is discussed. Molecules generally exhibit relatively strong vibronic coupling. The last section of this overview focuses on vibronic effects, including inelastic electron tunneling spectroscopy, hysteresis in junction charge transport, and negative differential resistance in molecular transport junctions.

Transportation accidents/incidents involving radioactive materials (1971--1991)

International Nuclear Information System (INIS)

Cashwell, C.E.; McClure, J.D.

1992-01-01

The Radioactive Materials Incident Report (RMIR) database contains information on transportation-related accidents and incidents involving radioactive materials that have occurred in the United States. The RMIR was developed at Sandia National Laboratories (SNL) to support its research and development program efforts for the US Department of Energy (DOE). This paper will address the following topics: background information on the regulations and process for reporting a hazardous materials transportation incident, overview data of radioactive materials transportation accidents and incidents, and additional information and summary data on how packagings have performed in accident conditions

Safe transport of radioactive materials in Egypt

International Nuclear Information System (INIS)

El-Shinawy, R.M.K.

1994-01-01

In Egypt the national regulations for safe transport of radioactive materials (RAM) are based on the International Atomic Energy Agency (IAEA) regulations. In addition, regulations for the safe transport of these materials through the Suez Canal (SC) were laid down by the Egyptian Atomic Energy Authority (EAEA) and the Suez Canal Authority (SCA). They are continuously updated to meet the increased knowledge and the gained experience. The technical and protective measures taken during transport of RAM through SC are mentioned. Assessment of the impact of transporting radioactive materials through the Suez Canal using the INTERTRAN computer code was carried out in cooperation with IAEA. The transported activities and empty containers, the number of vessels carrying RAM through the canal from 1963 and 1991 and their nationalities are also discussed. The protective measures are mentioned. A review of the present situation of the radioactive wastes storage facilities at the Atomic Energy site at Inshas is given along with the regulation for safe transportation and disposal of radioactive wastes. (Author)

Temperature gradient driven electron transport in NSTX and Tore Supra

International Nuclear Information System (INIS)

Horton, W.; Wong, H.V.; Morrison, P.J.; Wurm, A.; Kim, J.H.; Perez, J.C.; Pratt, J.; Hoang, G.T.; LeBlanc, B.P.; Ball, R.

2005-01-01

Electron thermal fluxes are derived from the power balance for Tore Supra (TS) and NSTX discharges with centrally deposited fast wave electron heating. Measurements of the electron temperature and density profiles, combined with ray tracing computations of the power absorption profiles, allow detailed interpretation of the thermal flux versus temperature gradient. Evidence supporting the occurrence of electron temperature gradient turbulent transport in the two confinement devices is found. With control of the magnetic rotational transform profile and the heating power, internal transport barriers are created in TS and NSTX discharges. These partial transport barriers are argued to be a universal feature of transport equations in the presence of invariant tori that are intrinsic to non-monotonic rotational transforms in dynamical systems

Procedures for the Safe Transport of Radioactive Material

Energy Technology Data Exchange (ETDEWEB)

Kim, Jang Lyul; Chung, K. K.; Lee, J. I.; Chang, S. Y.; Lee, T. Y

2007-11-15

This technical report describes the procedure and work responsibility along with the regulation and standard necessary for the safe transport of radioactive or contaminated materials. This report, therefore, can be effectively used to secure the public safety as well as to prevent the disastrous event which might be resulted from the transport process of radioactive materials by establishing a procedure and method on the safe packing, handling and transport of radioactive materials.

Anticipated development in radioactive materials packaging and transport systems

International Nuclear Information System (INIS)

Williams, L.D.; Rhoads, R.E.; Hall, R.J.

1976-07-01

Closing the light water reactor fuel cycle and the use of mixed oxide fuels will produce materials such as solidified high level waste, cladding hulls and plutonium from Pu recycle fuel that have not been transported extensively in the past. Changes in allowable gaseous emissions from fuel cycle facilities may require the collection and transportation of radioactive noble gases and tritium. Although all of these materials could be transported in existing radioactive material packaging, economic considerations will make it desirable to develop new packaging specifically designed for each material. Conceptual package designs for these materials are reviewed. Special Nuclear Material transportation safeguards are expected to have a significant impact on future fuel cycle transportation. This subject is reviewed briefly. Other factors that could affect fuel cycle transportation are also discussed. Development of new packaging for radioactive materials is not believed to require the development of new technologies. New package designs will be primarily an adaptation of existing technology to fit the changing needs of a growing nuclear power industry. 23 references

Current trends in nuclear material transportation

International Nuclear Information System (INIS)

Ravenscroft, Norman; Oshinowo, Franchone

1997-01-01

The business of radioactive material transportation has evolved considerably in the past 40 years. Current practices reflect extensive international experience in handling radioactive cargo within a mature and tested regulatory framework. Nevertheless, new developments continue to have an impact on how shipments of nuclear material are planned and carried out. Entities involved in the transport of radioactive materials must keep abreast of these developments and work together to find innovative solutions to ensure that safe, smooth transport activities may continue. Several recent trends in the regulatory environment and political atmosphere require attention. There are four key trends that we'll be examining today: 1) the reduction in the pool of available commercial carriers; 2) routing restrictions; 3) package validation issues; and 4) increasing political sensitivities. Careful planning and cooperative measures are necessary to alleviate problems in each of these areas. (author)

Electron thermal transport in tokamak: ETG or TEM turbulences?

International Nuclear Information System (INIS)

Lin, Z.; Chen, L.; Nishimura, Y.; Qu, H.; Hahm, T.S.; Lewandowski, J.; Rewoldt, G.; Wang, W.X.; Diamond, P.H.; Holland, C.; Zonca, F.; Li, Y.

2005-01-01

This paper reports progress on numerical and theoretical studies of electron transport in tokamak including: (1) electron temperature gradient turbulence; (2) trapped electron mode turbulence; and (3) a new finite element solver for global electromagnetic simulation. In particular, global gyrokinetic particle simulation and nonlinear gyrokinetic theory find that electron temperature gradient (ETG) instability saturates via nonlinear toroidal couplings, which transfer energy successively from unstable modes to damped modes preferably with longer poloidal wavelengths. The electrostatic ETG turbulence is dominated by nonlinearly generated radial streamers. The length of streamers scales with the device size and is much longer than the distance between mode rational surfaces or electron radial excursions. Both fluctuation intensity and transport level are independent of the streamer size. These simulations with realistic plasma parameters find that the electron heat conductivity is much smaller than the experimental value and in contrast with recent findings of flux-tube simulations that ETG turbulence is responsible for the anomalous electron thermal transport in fusion plasmas. The nonlinear toroidal couplings represent a new paradigm for the spectral cascade in plasma turbulence. (author)

The safe transport of radioactive materials

International Nuclear Information System (INIS)

Messenger, W. de L.M.

1979-02-01

The hazards of radioactive materials in transport are surveyed. The system whereby they are safely transported between nuclear establishments in the United Kingdom and overseas is outlined. Several popular misconceptions are dealt with. (author)

Regulations of safe transport of radioactive material

International Nuclear Information System (INIS)

Patel, R.J.; Sumathi, E.

2017-01-01

BARC is a multi-disciplinary nuclear research organisation with facilities located at various parts of the country. The nuclear and radiological facilities in BARC include fuel fabrication facilities, nuclear research reactors, radiological laboratories, nuclear recycle facilities, waste management facilities and other associated facilities. RAdioactive Material (RAM) such as fresh nuclear fuel, irradiated fuel, radioactive sources, vitrified high level wastes, special nuclear material etc., are transported between these facilities either within the controlled premises or in public domain. In BARC the regulatory approval for the packages used for transport of RAM is issued by BARC Safety Council (BSC). Competent Authority for issuing the design approval for the BARC packages in public domain is Director, BARC. In this aspect BSC is assisted by Safety Review Committee-Transport of Radioactive Material (SRC-TRM) constituted by BSC entrusted with the mandate to ensure the packages are designed, manufactured and transported in accordance with the current regulations. This article summarizes the regulatory requirements for transport of RAM and experience in BARC facilities

Legal aspects of transport of nuclear materials

International Nuclear Information System (INIS)

Jacobsson, Mans.

The Paris Convention and the Brussels Supplementary Convention are briefly discussed and other conventions in the field of civil liability for nuclear damage are mentioned: the Vienna Convention, the Nuclear Ships Convention and the 1971 Convention relating to civil liability in the field of maritime carriage of nuclear material. Legislation on civil liability in the Nordic countries, which is based on the Paris Convention and the Supplementary Convention is discussed, notably the principle of channelling of liability and exceptions from that principle due to rules of liability in older transport conventions and certain problems due to the limited geographical scope of the Paris Convention and the Supplementary Convention. Insurance problems arising in connection with transport of nuclear materials are surveyed and an outline is given of the administrative provisions concerning transport (based on the IAEA transport regulations) which govern transport of radioactive materials by different means: road, rail, sea and air. Finally, the 1968 Treaty on the Non-Proliferation of Nuclear Weapons is discussed. (NEA) [fr

Charge transport through DNA based electronic barriers

Science.gov (United States)

Patil, Sunil R.; Chawda, Vivek; Qi, Jianqing; Anantram, M. P.; Sinha, Niraj

2018-05-01

We report charge transport in electronic 'barriers' constructed by sequence engineering in DNA. Considering the ionization potentials of Thymine-Adenine (AT) and Guanine-Cytosine (GC) base pairs, we treat AT as 'barriers'. The effect of DNA conformation (A and B form) on charge transport is also investigated. Particularly, the effect of width of 'barriers' on hole transport is investigated. Density functional theory (DFT) calculations are performed on energy minimized DNA structures to obtain the electronic Hamiltonian. The quantum transport calculations are performed using the Landauer-Buttiker framework. Our main findings are contrary to previous studies. We find that a longer A-DNA with more AT base pairs can conduct better than shorter A-DNA with a smaller number of AT base pairs. We also find that some sequences of A-DNA can conduct better than a corresponding B-DNA with the same sequence. The counterions mediated charge transport and long range interactions are speculated to be responsible for counter-intuitive length and AT content dependence of conductance of A-DNA.

Transportation of radioactive materials - a utility view

International Nuclear Information System (INIS)

Futter, J.L.

1979-01-01

Local restrictions to transportation of radioactive materials have proliferated, and the reasons for this are described. Some of the measures which could be undertaken to counteract this trend are discussed. People should speak out on the need for nuclear power in general and for transportation of nuclear materials in particular

Transport of radioactive materials by post

International Nuclear Information System (INIS)

1984-11-01

The objective of the Seminar was to encourage safe and efficient carriage of radioactive material by post. Adequate, up-to-date regulations for international and domestic shipment of radioactive material by all modes of transport, including by mail, have been published by the IAEA. UPU, ICAO, IATA and other international organizations as well as a majority of the countries of the world have adopted most sections of the Agency's Regulations for the Safe Transport of Radioactive Material. Although there is an apparent need for shipping radioactive material by mail, some countries allow only domestic shipments and the postal regulations applied in these countries often differs from the international regulations. Only about 25 countries are known to allow international (as well as domestic) shipments. From the discussions and comments at the Seminar, it appears that the option of shipment by post would be advantageous to enhance both the safety and economy of transporting, as well as to increase availability of, radioactive materials. The Agency's Regulations for transport by post as adopted by the UPU and ICAO are considered to provide a high level of safety and ensure a negligible element of risk. A more uniform application of these regulations within UPU Member States should be encouraged. The competent authority for implementation of the other parts of the Agency's Regulations in each of the Member States should be invited to advise the Postal Administrators and assist in applying the requirements to national as well as international postal shipments

Nonequilibrium statistical operator in hot-electron transport theory

International Nuclear Information System (INIS)

Xing, D.Y.; Liu, M.

1991-09-01

The Nonequilibrium Statistical Operator method developed by Zubarev is generalized and applied to the study of hot-electron transport in semiconductors. The steady-state balance equations for momentum and energy are derived to the lowest order in the electron-lattice coupling. We show that the derived balance equations are exactly the same as those obtained by Lei and Ting. This equivalence stems from the fact that to the linear order in the electron-lattice coupling, two statistical density matrices have identical effect when they are used to calculate the average value of a dynamical operator. The application to the steady-state and transient hot-electron transport in multivalley semiconductors is also discussed. (author). 28 refs, 1 fig

Electron-vibron coupling effects on electron transport via a single-molecule magnet

Science.gov (United States)

McCaskey, Alexander; Yamamoto, Yoh; Warnock, Michael; Burzurí, Enrique; van der Zant, Herre S. J.; Park, Kyungwha

2015-03-01

We investigate how the electron-vibron coupling influences electron transport via an anisotropic magnetic molecule, such as a single-molecule magnet (SMM) Fe4, by using a model Hamiltonian with parameter values obtained from density-functional theory (DFT). The magnetic anisotropy parameters, vibrational energies, and electron-vibron coupling strengths of the Fe4 are computed using DFT. A giant spin model is applied to the Fe4 with only two charge states, specifically a neutral state with a total spin S =5 and a singly charged state with S =9 /2 , which is consistent with our DFT result and experiments on Fe4 single-molecule transistors. In sequential electron tunneling, we find that the magnetic anisotropy gives rise to new features in the conductance peaks arising from vibrational excitations. In particular, the peak height shows a strong, unusual dependence on the direction as well as magnitude of applied B field. The magnetic anisotropy also introduces vibrational satellite peaks whose position and height are modified with the direction and magnitude of applied B field. Furthermore, when multiple vibrational modes with considerable electron-vibron coupling have energies close to one another, a low-bias current is suppressed, independently of gate voltage and applied B field, although that is not the case for a single mode with a similar electron-vibron coupling. In the former case, the conductance peaks reveal a stronger B -field dependence than in the latter case. The new features appear because the magnetic anisotropy barrier is of the same order of magnitude as the energies of vibrational modes with significant electron-vibron coupling. Our findings clearly show the interesting interplay between magnetic anisotropy and electron-vibron coupling in electron transport via the Fe4. Similar behavior can be observed in transport via other anisotropic magnetic molecules.

One-Dimensional Electron Transport Layers for Perovskite Solar Cells

Directory of Open Access Journals (Sweden)

Ujwal K. Thakur

2017-04-01

Full Text Available The electron diffusion length (Ln is smaller than the hole diffusion length (Lp in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D structures such as nanowires (NWs and nanotubes (NTs as electron transport layers (ETLs is a promising method of achieving high performance halide perovskite solar cells (HPSCs. ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge transport but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs. Photoconversion efficiencies (PCEs as high as 18% have been demonstrated for HPSCs using 1D ETLs. Despite the advantages of 1D ETLs, there are still challenges that need to be overcome to achieve even higher PCEs, such as better methods to eliminate or passivate surface traps, improved understanding of the hetero-interface and optimization of the morphology (i.e., length, diameter, and spacing of NWs/NTs. This review introduces the general considerations of ETLs for HPSCs, deposition techniques used, and the current research and challenges in the field of 1D ETLs for perovskite solar cells.

One-Dimensional Electron Transport Layers for Perovskite Solar Cells

Science.gov (United States)

Thakur, Ujwal K.; Kisslinger, Ryan; Shankar, Karthik

2017-01-01

The electron diffusion length (Ln) is smaller than the hole diffusion length (Lp) in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D) structures such as nanowires (NWs) and nanotubes (NTs) as electron transport layers (ETLs) is a promising method of achieving high performance halide perovskite solar cells (HPSCs). ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge transport but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs. Photoconversion efficiencies (PCEs) as high as 18% have been demonstrated for HPSCs using 1D ETLs. Despite the advantages of 1D ETLs, there are still challenges that need to be overcome to achieve even higher PCEs, such as better methods to eliminate or passivate surface traps, improved understanding of the hetero-interface and optimization of the morphology (i.e., length, diameter, and spacing of NWs/NTs). This review introduces the general considerations of ETLs for HPSCs, deposition techniques used, and the current research and challenges in the field of 1D ETLs for perovskite solar cells. PMID:28468280

Analytic approach to auroral electron transport and energy degradation

International Nuclear Information System (INIS)

Stamnes, K.

1980-01-01

The interaction of a beam of auroral electrons with the atmosphere is described by the linear transport equation, encompassing discrete energy loss, multiple scattering, and secondary electrons. A solution to the transport equation provides the electron intensity as a function of altitude, pitch angle (with respect to the geomagnetic field) and energy. A multi-stream (discrete ordinate) approximation to the transport equation is developed. An analytic solution is obtained in this approximation. The computational scheme obtained by combining the present transport code with the energy degradation method of Swartz (1979) conserves energy identically. The theory provides a framework within which angular distributions can be easily calculated and interpreted. Thus, a detailed study of the angular distributions of 'non-absorbed' electrons (i.e., electrons that have lost just a small fraction of their incident energy) reveals a systematic variation with incident angle and energy, and with penetration depth. The present approach also gives simple yet accurate solutions in low order multi-stream approximations. The accuracy of the four-stream approximation is generally within a few per cent, whereas two-stream results for backscattered mean intensities and fluxes are accurate to within 10-15%. (author)

Electron fluence correction factors for various materials in clinical electron beams

International Nuclear Information System (INIS)

Olivares, M.; Blois, F. de; Podgorsak, E.B.; Seuntjens, J.P.

2001-01-01

Relative to solid water, electron fluence correction factors at the depth of dose maximum in bone, lung, aluminum, and copper for nominal electron beam energies of 9 MeV and 15 MeV of the Clinac 18 accelerator have been determined experimentally and by Monte Carlo calculation. Thermoluminescent dosimeters were used to measure depth doses in these materials. The measured relative dose at d max in the various materials versus that of solid water, when irradiated with the same number of monitor units, has been used to calculate the ratio of electron fluence for the various materials to that of solid water. The beams of the Clinac 18 were fully characterized using the EGS4/BEAM system. EGSnrc with the relativistic spin option turned on was used to optimize the primary electron energy at the exit window, and to calculate depth doses in the five phantom materials using the optimized phase-space data. Normalizing all depth doses to the dose maximum in solid water stopping power ratio corrected, measured depth doses and calculated depth doses differ by less than ±1% at the depth of dose maximum and by less than 4% elsewhere. Monte Carlo calculated ratios of doses in each material to dose in LiF were used to convert the TLD measurements at the dose maximum into dose at the center of the TLD in the phantom material. Fluence perturbation correction factors for a LiF TLD at the depth of dose maximum deduced from these calculations amount to less than 1% for 0.15 mm thick TLDs in low Z materials and are between 1% and 3% for TLDs in Al and Cu phantoms. Electron fluence ratios of the studied materials relative to solid water vary between 0.83±0.01 and 1.55±0.02 for materials varying in density from 0.27 g/cm3 (lung) to 8.96 g/cm3 (Cu). The difference in electron fluence ratios derived from measurements and calculations ranges from -1.6% to +0.2% at 9 MeV and from -1.9% to +0.2% at 15 MeV and is not significant at the 1σ level. Excluding the data for Cu, electron fluence

Ballistic transport and electronic structure

NARCIS (Netherlands)

Schep, Kees M.; Kelly, Paul J.; Bauer, Gerrit E.W.

1998-01-01

The role of the electronic structure in determining the transport properties of ballistic point contacts is studied. The conductance in the ballistic regime is related to simple geometrical projections of the Fermi surface. The essential physics is first clarified for simple models. For real

Electronic Monitoring Of Storage And Transport Temperatures Of ...

African Journals Online (AJOL)

Electronic Monitoring Of Storage And Transport Temperatures Of Thermostable Newcastle ... 22) were monitored during storage and transport from vaccine production laboratory in Temeke, Dar es ... EMAIL FULL TEXT EMAIL FULL TEXT

Runaway-electron-materials interaction studies

International Nuclear Information System (INIS)

Bolt, H.; Miyahara, A.

1990-03-01

During the operation of magnetic fusion devices it has been frequently observed that runaway electrons can cause severe damage to plasma facing components. The energy of the runaway electrons could possibly reach several 100 MeV in a next generation device with an energy content in the plasma in the order of 100 MJ. In this study effects of high energy electron - materials interaction were determined by laboratory experiments using particle beam facilities, i.e. the Electron Linear Accelerator of the Institute of Scientific and Industrial Research of Osaka University and the 10 MW Neutral Beam Injection Test Stand of the National Institute for Fusion Science. The experiments and further analyses lead to a first assessment of the damage thresholds of plasma facing materials and components under runaway electron impact. It was found that metals (stainless steel, molybdenum, tungsten) showed grain growth, crack formation and/or melting already below the threshold for crack initiation on graphite (14-33 MJ/m 2 ). Strong erosion of carbon materials would occur above 100 MJ/m 2 . Damage to metal coolant channels can occur already below an energy deposition of 100 MJ/m 2 . The energy deposited in the metal coolant channels depends on the thickness of the plasma facing carbon material D, with the shielding efficiency S of carbon approximately as S∼D 1.15 . (author) 304 refs. 12 tabs. 59 figs

Radiation doses from the transport of radioactive materials

International Nuclear Information System (INIS)

Shaw, K.B.; Holyoak, B.

1983-01-01

A summary is given of a study on radiation exposure resulting from the transport of radioactive materials within the United Kingdom. It was concluded that the transport of technetium generators for hospital use accounts for about 49% of the occupational exposure for the normal transport of radioactive materials. Other isotopes for medical and industrial use contribute about 38% of the occupational exposure and the remainder can be attributed to transportation as a result of the nuclear fuel cycle including the transport of irradiated nuclear fuel. The occupational collective dose for all modes of transport is estimated at 1 man Sv y -1 . (UK)

Noncovalent Interactions in Organic Electronic Materials

KAUST Repository

Ravva, Mahesh Kumar

2017-06-29

In this chapter, we provide an overview of how noncovalent interactions, determined by the chemical structure of π-conjugated molecules and polymers, govern essential aspects of the electronic, optical, and mechanical characteristics of organic semiconductors. We begin by describing general aspects of materials design, including the wide variety of chemistries exploited to control the electronic and optical properties of these materials. We then discuss explicit examples of how the study of noncovalent interactions can provide deeper chemical insights that can improve the design of new generations of organic electronic materials.

Transport of radioactive material in Sudan practice and regulations

International Nuclear Information System (INIS)

Abdalla, M. K. E.

2010-12-01

In the last couple of decades there has been an impressive increase in applications of radioactive material. Such an extensive and widely spread usage of radioactive materials demands safe transportation of radioactive material from the production site to the application location, as well as quick and effective response in a case of an unexpected transportation event according to Sudan Atomic Energy Commission (SAEC) regulation. The thesis described the local practice for transport of radioactive material as compared to the international standards for radiation protection, and also discussed the emergency procedures that must be follow in case of accident during transport of radioactive material. Furthermore, the objective of this study was also to set proposals for how to cope in the event of a radiological accident. The study methods included survey of current literature on safe transport of radioactive material, survey of national regulations on the subjects in additional to case studies aimed at investigating the practical issues pertinent to transport of radioactive materials in Sudan. A comprehensive review was presented on how to classification of radioactive packages and general requirement for all packaging and packages according to international standard. transport of number of radioactive sources from Khartoum airport to the field was evaluated with regard transport index, category of source, type of package, dose rate around the source, time to destination and means of transport of doses to public, worker are be made. All results were within the limit specified in the national as well as international regulation. The study has addressed for the first time the practice of transport of radioactive material in Sudan. It is anticipated that the results will encourage national organizational and professional bodies to enhance radiation protection and safety of radioactive sources. (Author)

Response matrix Monte Carlo based on a general geometry local calculation for electron transport

International Nuclear Information System (INIS)

Ballinger, C.T.; Rathkopf, J.A.; Martin, W.R.

1991-01-01

A Response Matrix Monte Carlo (RMMC) method has been developed for solving electron transport problems. This method was born of the need to have a reliable, computationally efficient transport method for low energy electrons (below a few hundred keV) in all materials. Today, condensed history methods are used which reduce the computation time by modeling the combined effect of many collisions but fail at low energy because of the assumptions required to characterize the electron scattering. Analog Monte Carlo simulations are prohibitively expensive since electrons undergo coulombic scattering with little state change after a collision. The RMMC method attempts to combine the accuracy of an analog Monte Carlo simulation with the speed of the condensed history methods. Like condensed history, the RMMC method uses probability distributions functions (PDFs) to describe the energy and direction of the electron after several collisions. However, unlike the condensed history method the PDFs are based on an analog Monte Carlo simulation over a small region. Condensed history theories require assumptions about the electron scattering to derive the PDFs for direction and energy. Thus the RMMC method samples from PDFs which more accurately represent the electron random walk. Results show good agreement between the RMMC method and analog Monte Carlo. 13 refs., 8 figs

Truck transportation of radioactive materials

International Nuclear Information System (INIS)

Madsen, M.M.; Wilmot, E.L.

1983-01-01

Analytical models in RADTRAN II are used to calculate risks to population subgroups such as people along transport routes, people at stops, and crewman. The stops model, which calculates the dose to persons adjacent to the transport vehicle while it is stopped, frequently provides the largest contribution to incident-free radiological impacts. Components such as distances from the vehicle containing radioactive material to nearby people at stops, stop duration, and number of crew members are required for the stops model as well as other incident-free models. To provide supporting data for RADTRAN II based on operational experience, selected truck shipments of radioactive material were observed from origin to destination. Other important aspects of this program were to correlate package size to effective shipment transport index (TI) using radiological surveys and to characterize population distributions and proximities of people to the shipment at a generic truck stop

Radiological impact of radioactive materials transport in France

International Nuclear Information System (INIS)

Hamard, J.

1987-01-01

Radiation doses of personnel and populations are estimated between 1983 and 1985 during road transport of radiopharmaceuticals, spent fuels, wastes and other radioactive materials. Dose equivalent received by air transport and others are difficult to know. Results are summed up in 8 tables. Radioactive materials transport represents less than 1% of exposures related to the fuel cycle [fr

A ballistic transport model for electronic excitation following particle impact

Science.gov (United States)

Hanke, S.; Heuser, C.; Weidtmann, B.; Wucher, A.

2018-01-01

We present a ballistic model for the transport of electronic excitation energy induced by keV particle bombardment onto a solid surface. Starting from a free electron gas model, the Boltzmann transport equation (BTE) is employed to follow the evolution of the temporal and spatial distribution function f (r → , k → , t) describing the occupation probability of an electronic state k → at position r → and time t. Three different initializations of the distribution function are considered: i) a thermal distribution function with a locally and temporally elevated electron temperature, ii) a peak excitation at a specific energy above the Fermi level with a quasi-isotropic distribution in k-space and iii) an anisotropic peak excitation with k-vectors oriented in a specific transport direction. While the first initialization resembles a distribution function which may, for instance, result from electronic friction of moving atoms within an ion induced collision cascade, the peak excitation can in principle result from an autoionization process after excitation in close binary collisions. By numerically solving the BTE, we study the electronic energy exchange along a one dimensional transport direction to obtain a time and space resolved excitation energy distribution function, which is then analyzed in view of general transport characteristics of the chosen model system.

Investigating the effect of acene-fusion and trifluoroacetyl substitution on the electronic and charge transport properties by density functional theory

Directory of Open Access Journals (Sweden)

Ahmad Irfan

2016-05-01

Full Text Available We designed novel derivatives of 4,6-di(thiophen-2-ylpyrimidine (DTP. Two benchmark strategies including mesomerically deactivating group, as well as the extension of π-conjugation bridge (acene-fusion have been employed to enhance the electrical and charge transport properties. The density functional theory (DFT and time dependent DFT methods have been used to get optimized geometries in ground and first excited state, respectively. The structural properties (geometric parameters, electronic properties (frontier molecular orbitals; highest occupied and lowest unoccupied molecular orbitals, photophysical properties (absorption, fluorescence and phosphorescence, and important charge transport properties are discussed to establish a molecular level structure–property relationship among these derivatives. Our calculated electronic spectra i.e., absorption, fluorescence and phosphorescence have been found in good semi-quantitative agreement with available experimental data. All the newly designed derivatives displayed significantly improved electron injection ability than those of the parent molecule. The values of reorganization energy and transfer integral elucidate that DTP is a potential hole transport material. Based on our present investigation, it is expected that the naphtho and anthra derivatives of DTP are better hole transporters than those of some well-known charge transporter materials like naphthalene, anthracene, tetracene and pentacene.

Electron beam induced electronic transport in alkyl amine-intercalated VOx nanotubes

International Nuclear Information System (INIS)

O'Dwyer, C.; Lavayen, V.; Clavijo-Cedeno, C.; Torres, C.M.S.

2008-01-01

The electron beam induced electronic transport in primary alkyl amine-intercalated V 2 O 5 nanotubes is investigated where the organic amine molecules are employed as molecular conductive wires to an aminosilanized substrate surface and contacted to Au interdigitated electrode contacts. The results demonstrate that the high conductivity of the nanotubes is related to the non-resonant tunnelling through the amine molecules and a reduced polaron hopping conduction through the vanadium oxide itself. Both nanotube networks and individual nanotubes exhibit similarly high conductivities where the minority carrier transport is bias dependent and nanotube diameter invariant. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Relative consequences of transporting hazardous materials

International Nuclear Information System (INIS)

Fullwood, R.R.; Rhyne, W.R.; Simmons, J.A.; Reese, R.T.

1980-01-01

The objective of this paper is to discuss methods under study at Transportation Technology Center to develop a perspective on how technical measures of hazard and risk relate to perception of hazards, harm, and risks associated with transporting hazardous materials. This paper is concerned with two major aspects of the relative hazards problem. The first aspect is the analyses of the possible effects associated with exposure to hazardous materials as contained in the following two parts: outlines of possible problems and controversies that could be encountered in the evaluation and comparisons of hazards and risks; and description of the various measures of harm (hazards or dangers) and subsequent comparisons thereof. The second aspect of this paper leads into a presentation of the results of a study which had the following purposes: to develop analytical techniques for a consistent treatment of the phenomenology of the consequences of a release of hazardous materials; to reduce the number of variables in the consequence analyses by development of transportation accident scenarios which have the same meteorological conditions, demography, traffic and population densities, geographical features and other appropriate conditions and to develop consistent methods for presenting the results of studies and analyses that describe the phenomenology and compare hazards. The results of the study are intended to provide a bridge between analytical certainty and perception of the hazards involved. Understanding the differences in perception of hazards resulting from transport of various hazardous materials is fraught with difficulties in isolating the qualitative and quantitative features of the problem. By relating the quantitative impacts of material hazards under identical conditions, it is hoped that the perceived differences in material hazards can be delineated and evaluated

Transport of hazardous materials in the Amazon area; Transporte de produtos perigosos na regiao Amazonica

Energy Technology Data Exchange (ETDEWEB)

Cunha, Wallace de Castro [FURNAS Centrais Eletricas S.A., Rio de Janeiro, RJ (Brazil); Fernandes, Elton; Nassi, Carlos David [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE)

2008-07-01

Amongst several exploratory sources of the subject 'hazardous materials transport', it is distinguished: 'the threat to the environment'. This paper presents an exploratory investigation of this subject line in the Amazon region. In view of the diversity of 'existing hazardous materials' and the raised dimension of the oil transport and its derivatives in this context, this paper focused in these products. Regarding to the geographic region, the approach was given to the State of Amazon, considering the amplitude of this State in the Amazon region and the availability of data. Therefore, this work explores and analyzes macro aspects inherent to the State of Amazon pertinent to the oil transport and its derivatives. In the macro context, it is observed the necessity of a higher control in the transport of hazardous materials in the region. The absence of registered data and the unfamiliarity on the risks related to the transport of hazardous materials by authorities and transporters indicate a relative absence of qualification in the region to deal with the monitoring of the transport of hazardous materials. So far, it is not possible up till now to make any evaluation of the environment threats of accidents with transport of hazardous materials in the Amazon region.(author)

Transport of hazardous materials in the Amazon area; Transporte de produtos perigosos na regiao Amazonica

Energy Technology Data Exchange (ETDEWEB)

Cunha, Wallace de Castro [FURNAS Centrais Eletricas S.A., Rio de Janeiro, RJ (Brazil); Fernandes, Elton; Nassi, Carlos David [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE)

2008-07-01

Amongst several exploratory sources of the subject 'hazardous materials transport', it is distinguished: 'the threat to the environment'. This paper presents an exploratory investigation of this subject line in the Amazon region. In view of the diversity of 'existing hazardous materials' and the raised dimension of the oil transport and its derivatives in this context, this paper focused in these products. Regarding to the geographic region, the approach was given to the State of Amazon, considering the amplitude of this State in the Amazon region and the availability of data. Therefore, this work explores and analyzes macro aspects inherent to the State of Amazon pertinent to the oil transport and its derivatives. In the macro context, it is observed the necessity of a higher control in the transport of hazardous materials in the region. The absence of registered data and the unfamiliarity on the risks related to the transport of hazardous materials by authorities and transporters indicate a relative absence of qualification in the region to deal with the monitoring of the transport of hazardous materials. So far, it is not possible up till now to make any evaluation of the environment threats of accidents with transport of hazardous materials in the Amazon region.(author)

Emergency preparedness and response in transport of radioactive material

International Nuclear Information System (INIS)

Takani, Michio

2008-01-01

Nuclear power has been providing clean, affordable electricity in many parts of the world for nearly half a century. The national and international transport of nuclear fuel cycle materials is essential to support this activity. To sustain the nuclear power industry, fuel cycle materials have to be transported safely and efficiently. The nature of the industry is such that most countries with large-scale nuclear power industries cannot provide all the necessary fuel services themselves and consequently nuclear fuel cycle transport activities are international. The radioactive material transport industry has an outstanding safety record spanning over 45 years; however the transport of radioactive materials cannot and most not be taken for granted. Efficient emergency preparedness and response in the transport of radioactive material is an important element to ensure the maximum safety in accident conditions. The World Nuclear Transport Institute (WNTI), founded by International Nuclear Services (INS) of the United Kingdom, AREVA of France an the Federation of Electric Power Companies (FEPC) of Japan, represents the collective interest of the radioactive material transport sector, and those who rely on safe, effective and reliable transport. As part of its activities, WNTI has conducted two surveys through its members on emergency preparedness and response in the transport of radioactive material and emergency exercises. After recalling the International Atomic Energy Agency approach on emergency response, this paper will be discussing the main conclusion of surveys, in particular the national variations in emergency response and preparedness on the national and local levels of regulations, the emergency preparedness in place, the emergency response organisation (who and how), communication and exercises. (author)

Insights into the post-transcriptional regulation of the mitochondrial electron transport chain.

Science.gov (United States)

Sirey, Tamara M; Ponting, Chris P

2016-10-15

The regulation of the mitochondrial electron transport chain is central to the control of cellular homeostasis. There are significant gaps in our understanding of how the expression of the mitochondrial and nuclear genome-encoded components of the electron transport chain are co-ordinated, and how the assembly of the protein complexes that constitute the electron transport chain are regulated. Furthermore, the role post-transcriptional gene regulation may play in modulating these processes needs to be clarified. This review summarizes the current knowledge regarding the post-transcriptional gene regulation of the electron transport chain and highlights how noncoding RNAs may contribute significantly both to complex electron transport chain regulatory networks and to mitochondrial dysfunction. © 2016 The Author(s).

The safe transport of radioactive material in South Africa

International Nuclear Information System (INIS)

Jutle, K.K.

1997-01-01

An overview is presented of the activities related to the transport of radioactive material in South Africa. In particular, the applicable legislation, the scope of authority and regulatory functions of the Competent Authority are discussed. The categories of radioactive materials transported and the packaging requirements for the safe transport of these radioactive materials are also described. (Author)

The safe transport of radioactive material in South Africa

International Nuclear Information System (INIS)

Jutle, K.K.

2000-01-01

An overview is presented of the activities related to the transport of radioactive material in South Africa. In particular, the applicable legislation, the scope of authority and the regulatory functions of the Competent Authority are discussed. The categories of radioactive materials transported and the packaging requirements for the safe transport of these radioactive materials are also described. (author)

Virtual screening of electron acceptor materials for organic photovoltaic applications

International Nuclear Information System (INIS)

D Halls, Mathew; Giesen, David J; Goldberg, Alexander; Djurovich, Peter J; Sommer, Jonathan; McAnally, Eric; Thompson, Mark E

2013-01-01

Virtual screening involves the generation of structure libraries, automated analysis to predict properties related to application performance and subsequent screening to identify lead systems and estimate critical structure–property limits across a targeted chemical design space. This approach holds great promise for informing experimental discovery and development efforts for next-generation materials, such as organic semiconductors. In this work, the virtual screening approach is illustrated for nitrogen-substituted pentacene molecules to identify systems for development as electron acceptor materials for use in organic photovoltaic (OPV) devices. A structure library of tetra-azapentacenes (TAPs) was generated by substituting four nitrogens for CH at 12 sites on the pentacene molecular framework. Molecular properties (e.g. E LUMO , E g and μ) were computed for each candidate structure using hybrid DFT at the B3LYP/6-311G** level of theory. The resulting TAPs library was then analyzed with respect to intrinsic properties associated with OPV acceptor performance. Marcus reorganization energies for charge transport for the most favorable TAP candidates were then calculated to further determine suitability as OPV electron acceptors. The synthesis, characterization and OPV device testing of TAP materials is underway, guided by these results. (paper)

Electronic repository and standardization of processes and electronic documents in transport

Directory of Open Access Journals (Sweden)

Tomasz DĘBICKI

2007-01-01

Full Text Available The article refers to the idea of the use of electronic repository to store standardised scheme of processes between a Logistics Service Provider and its business partners. Application of repository for automatic or semi-automatic configuration of interoperability in electronic data interchange between information systems of differentcompanies based on transport (road, rail, sea and combined related processes. Standardisation includes processes, scheme of cooperation and related to them, electronic messages.

Computational methods of electron/photon transport

International Nuclear Information System (INIS)

Mack, J.M.

1983-01-01

A review of computational methods simulating the non-plasma transport of electrons and their attendant cascades is presented. Remarks are mainly restricted to linearized formalisms at electron energies above 1 keV. The effectiveness of various metods is discussed including moments, point-kernel, invariant imbedding, discrete-ordinates, and Monte Carlo. Future research directions and the potential impact on various aspects of science and engineering are indicated

Radiation induced low-energy electron transport in a tissue environment

International Nuclear Information System (INIS)

Toburen, L.H.; Dingfelder, M.; Ozturk, N.; Christou, C.; Shinpaugh, J.L.; Friedland, W.; Wilson, W.E.; Paretzke, H.G.

2003-01-01

Monte Carlo (MC) track simulation codes are used extensively in radiobiology to quantify the spatial distributions of interactions initiated by the absorption of ionizing radiation. The spatial patterns of ionization and excitation are instrumental for assessing the formation of damage clusters in DNA and chromosomes leading to such biologic endpoints as cellular transformation and mutation. The MC codes rely on an extensive database of elastic and inelastic scattering cross sections to follow the production and slowing of secondary electrons. Because of inherent uncertainties in this database we are exploring the sensitivity of MC results to the details of the cross sections used with emphasis on low-energy electrons, i.e., track ends, that are anticipated to play a dominant role in damage cluster formation. Simulations of electron transport using gas or liquid based interaction cross sections illustrate substantial difference in the spectra of electrons with energies less than about 50 eV. In addition, the electron yields from MC simulations appear to be nearly a factor of five larger than our recent measurements of electron transport spectra in water (ice) at electron energies of about 10 eV. Examples of the changes in electron transport spectra for variations in the electron scattering cross sections used for the MC calculations will be illustrated and compared with an evolving database of measured spectra of electrons from ion induced secondary electron transport in thin foils. These measurements provide guidance for assessment of elastic and elastic cross sections appropriate to condensed phase transport. This work is supported in part by the U.S. Department of Energy, Grant No. DE-FG02-01ER-63233; the National Cancer Institute, Grant No. 1R01CA93351-01A1; and the European Community under Contract No. FIGH-CT-1999-00005

Electron-vibron coupling effects on electron transport via a single-molecule magnet

NARCIS (Netherlands)

McCaskey, A.; Yamamoto, Y.; Warnock, M.; Burzuri, E.; Van der Zant, H.S.J.; Park, K.

2015-01-01

We investigate how the electron-vibron coupling influences electron transport via an anisotropic magnetic molecule, such as a single-molecule magnet (SMM) Fe4, by using a model Hamiltonian with parameter values obtained from density-functional theory (DFT). The magnetic anisotropy parameters,

State statutes and regulations on radioactive materials transportation

International Nuclear Information System (INIS)

Foster, B.

1981-11-01

The transport of radioactive material is controlled by numerous legislative and regulatory actions at the federal, state, and local levels. This document is a compilation of the state level laws and regulations. The collected material is abstracted and indexed by states. Each state section contains three divisions: (1) abstracts of major statutes, (2) legislative rules, and (3) photocopies of relevant paragraphs from the law or regulation. This document was prepared for use by individuals who are involved in the radioactive material transportation process. This document will not be updated. The legislative rules section contains the name of the state agency primarily responsible for monitoring the transport of radioactive materials

RADTRAN3, Risk of Radioactive Material Transport

International Nuclear Information System (INIS)

Madsen, M.M.; Taylor, J.M.; Ostmeyer, R.M.; Reardon, P.C.

2001-01-01

1 - Description of program or function: RADTRAN3 is a flexible analytical tool for calculating both the incident-free and accident impacts of transporting radioactive materials. The consequences from incident-free shipments are apportioned among eight population sub- groups and can be calculated for several transport modes. The radiological accident risk (probability times consequence summed over all postulated accidents) is calculated in terms of early fatalities, early morbidities, latent cancer fatalities, genetic effects, and economic impacts. Ground-shine, ingestion, inhalation, direct exposure, resuspension, and cloud-shine dose pathways are modeled to calculate the radiological health risks from accidents. Economic impacts are evaluated based on costs for emergency response, cleanup, evacuation, income loss, and land use. RADTRAN3 can be applied to specific scenario evaluations (individual transport modes or specified combinations), to compare alternative modes or to evaluate generic radioactive material shipments. Unit-risk factors can easily be evaluated to aid in performing generic analyses when several options must be compared with the amount of travel as the only variable. RADTRAN4 offers advances in the handling of route-related data and in the treatment of multiple-isotope materials. 2 - Method of solution: There are several modes used in the transporting of radioactive material such as trucks, passenger vans, passenger airplanes, rail and others. With these modes of transport come several shipment scenarios. The RADTRAN4 methodology uses material, transportation, population distribution, and health effects models to treat the incident-free case. To handle the vehicle accident impacts, accident severity and package release, meteorological dispersion, and economic models are also employed. 3 - Restrictions on the complexity of the problem: There are no apparent limitations due to programming dimensions

Computational Materials Science | Materials Science | NREL

Science.gov (United States)

Computational Materials Science Computational Materials Science An image of interconnecting, sphere science capabilities span many research fields and interests. Electronic, Optical, and Transport Properties of Photovoltaic Materials Material properties and defect physics of Si, CdTe, III-V, CIGS, CZTS

An optimization model for transportation of hazardous materials

International Nuclear Information System (INIS)

Seyed-Hosseini, M.; Kheirkhah, A. S.

2005-01-01

In this paper, the optimal routing problem for transportation of hazardous materials is studied. Routing for the purpose of reducing the risk of transportation of hazardous materials has been studied and formulated by many researcher and several routing models have been presented up to now. These models can be classified into the categories: the models for routing a single movement and the models for routing multiple movements. In this paper, according to the current rules and regulations of road transportations of hazardous materials in Iran, a routing problem is designed. In this problem, the routs for several independent movements are simultaneously determined. To examine the model, the problem the transportations of two different dangerous materials in the road network of Mazandaran province in the north of Iran is formulated and solved by applying Integer programming model

Taking an electron-magnon duality shortcut from electron to magnon transport

Science.gov (United States)

Mook, Alexander; Göbel, Börge; Henk, Jürgen; Mertig, Ingrid

2018-04-01

The quasiparticles in insulating magnets are the charge-neutral magnons, whose magnetic moments couple to electromagnetic fields. For collinear easy-axis magnets, this coupling can be mapped elegantly onto the scenario of charged particles in electromagnetic fields. From this mapping we obtain equations of motion for magnon wave packets equal to those of electron wave packets in metals. Thus, well-established electronic transport phenomena can be carried over to magnons: this duality shortcut facilitates the discussion of magnon transport. We identify the magnon versions of normal and anomalous Hall, Nernst, Ettingshausen, and Righi-Leduc effects. They are discussed for selected types of easy-axis magnets: ferromagnets, antiferromagnets, and ferrimagnets. Besides a magnon Wiedemann-Franz law and the magnon counterpart of the negative magnetoresistance of electrons in Weyl semimetals, we predict that certain low-symmetry ferrimagnets exhibit a nonlinear version of the anomalous magnon Hall-effect family.

The Electron Transport Chain: An Interactive Simulation

Science.gov (United States)

Romero, Chris; Choun, James

2014-01-01

This activity provides students an interactive demonstration of the electron transport chain and chemiosmosis during aerobic respiration. Students use simple, everyday objects as hydrogen ions and electrons and play the roles of the various proteins embedded in the inner mitochondrial membrane to show how this specific process in cellular…

Technical regulations for road transport of radioactive materials

International Nuclear Information System (INIS)

Juul-Jensen, P.; Ulbak, K.

1990-01-01

The technical regulations for the transport of radioactive materials in Denmark are set down by the (Danish) National Board of Health in collaboration with the (Danish) National Institute for Radiation Hygiene in accordance with paragraph 3 of the Danish Ministry of Justice's Executive Order no. 2 of 2, January 1985 on the national road transport of dangerous goods by road, as amended by exutive order no. 251 of April 29th 1987 and no. 704 of November 1989. These regulations are presented here. They are almost identical, with only very few exceptions indicated in the publication, with the rules for Class 7 of the European convention on international transport of dangerous goods by road (ADR). In addition to the aforementioned regulations for national road transport of radioactive materials the general rules for the transport of radioactive materials found in the National Board of Health's executive order no. 721 of November 27th 1989 on the transport of radioactive materials are valid. The abovementioned executive orders, with the exception of certain supplements which are not part of the technical regulations, are also contained in this publication. (AB)

Institutional issues affecting transportation of nuclear materials

International Nuclear Information System (INIS)

Reese, R.T.; Luna, R.E.

1980-01-01

The institutional issues affecting transportation of nuclear materials in the United States represent significant barriers to meeting future needs in the transport of radioactive waste materials to their ultimate repository. While technological problems which must be overcome to perform such movements seem to be within the state-of-the-art, the timely resolution of these institutional issues seems less assured. However, the definition of these issues, as attempted in this paper, together with systematic analysis of cause and possible solutions are the essential elements of the Transportation Technology Center's Institutional Issues Program

NMR studies of transmembrane electron transport in human erythrocytes

International Nuclear Information System (INIS)

Kennett, E.C.; Bubb, W.A.; Kuchel, P.W.

2002-01-01

Full text: Electron transport systems exist in the plasma membranes of all cells. These systems appear to play a role in cell growth and proliferation, intracellular signalling, hormone responses, apoptotic events, cell defence and perhaps most importantly they enable the cell to respond to changes in the redox state of both the intra- and extracellular environments. Previously, 13 C NMR has been used to study transmembrane electron transport in human erythrocytes, specifically the reduction of extracellular 13 C-ferricyanide. NMR is a particularly useful tool for studying such systems as changes in the metabolic state of the cell can be observed concomitantly with extracellular reductase activity. We investigated the oxidation of extracellular NADH by human erythrocytes using 1 H and 31 P NMR spectroscopy. Recent results for glucose-starved human erythrocytes indicate that, under these conditions, extracellular NADH can be oxidised at the plasma membrane with the electron transfer across the membrane resulting in reduction of intracellular NAD + . The activity is inhibited by known trans-plasma membrane electron transport inhibitors (capsaicin and atebrin) and is unaffected by inhibition of the erythrocyte Band 3 anion transporter. These results suggest that electron import from extracellular NADH allows the cell to re-establish a reducing environment after the normal redox balance is disturbed

Basic transport phenomena in materials engineering

CERN Document Server

Iguchi, Manabu

2014-01-01

This book presents the basic theory and experimental techniques of transport phenomena in materials processing operations. Such fundamental knowledge is highly useful for researchers and engineers in the field to improve the efficiency of conventional processes or develop novel technology. Divided into four parts, the book comprises 11 chapters describing the principles of momentum transfer, heat transfer, and mass transfer in single phase and multiphase systems. Each chapter includes examples with solutions and exercises to facilitate students’ learning. Diagnostic problems are also provided at the end of each part to assess students’ comprehension of the material.  The book is aimed primarily at students in materials science and engineering. However, it can also serve as a useful reference text in chemical engineering as well as an introductory transport phenomena text in mechanical engineering. In addition, researchers and engineers engaged in materials processing operations will find the material use...

Secondary electron emission and self-consistent charge transport in semi-insulating samples

Energy Technology Data Exchange (ETDEWEB)

Fitting, H.-J. [Institute of Physics, University of Rostock, Universitaetsplatz 3, D-18051 Rostock (Germany); Touzin, M. [Unite Materiaux et Transformations, UMR CNRS 8207, Universite de Lille 1, F-59655 Villeneuve d' Ascq (France)

2011-08-15

Electron beam induced self-consistent charge transport and secondary electron emission (SEE) in insulators are described by means of an electron-hole flight-drift model (FDM) now extended by a certain intrinsic conductivity (c) and are implemented by an iterative computer simulation. Ballistic secondary electrons (SE) and holes, their attenuation to drifting charge carriers, and their recombination, trapping, and field- and temperature-dependent detrapping are included. As a main result the time dependent ''true'' secondary electron emission rate {delta}(t) released from the target material and based on ballistic electrons and the spatial distributions of currents j(x,t), charges {rho}(x,t), field F(x,t), and potential V(x,t) are obtained where V{sub 0} = V(0,t) presents the surface potential. The intrinsic electronic conductivity limits the charging process and leads to a conduction sample current to the support. In that case the steady-state total SE yield will be fixed below the unit: i.e., {sigma} {eta} + {delta} < 1.

Molecular structure, photoluminescent and electroluminescent properties of bis(2-(4-methyl-2-hydroxyphenyl)benzothiazolate) zinc with excellent electron-transport characteristics

International Nuclear Information System (INIS)

Xu Huixia; Xu Bingshe; Fang Xiaohong; Yue Yan; Chen Liuqing; Wang Hua; Hao Yuying

2011-01-01

Highlights: → The synthesis, crystal structure and photophysical properties of Zn(4-MeBTZ) 2 were reported. → The electron-transport property was investigated by theoretical calculations and experimental. → We found that Zn(4-MeBTZ) 2 has a higher electron mobility than that of [Zn(BTZ) 2 ] 2 and the devices based on it have a lower turn-on voltage. - Abstract: In this article, the molecular structure, photoluminescent and electroluminescent properties of bis(2-(4-methyl-2-hydroxyphenyl) benzothiazolate) zinc (Zn(4-MeBTZ) 2 ) with good electron-transport characteristics were reported. This complex was identified as triclinic structure with the strong intermolecular π-π stacking interactions between the benzothiazolate/phenoxido rings and weak intramolecular hydrogen bonds by X-ray single-crystal diffraction. Quantum chemical method has been employed to investigate electron structure and charge transport property. The blue-green light emission was observed by fabricating double-layer devices using Zn(4-MeBTZ) 2 as electron-transport and NPB as hole-transport material. The performance of organic light-emitting devices based on Zn(4-MeBTZ) 2 is much better than that of the devices based on [Zn(BTZ) 2 ] 2 .

Regulation on the transport of nuclear fuel materials by vehicles

International Nuclear Information System (INIS)

1984-01-01

The regulations applying to the transport of nuclear fuel materials by vehicles, mentioned in the law for the regulations of nuclear source materials, nuclear fuel materials and reactors. The transport is for outside of the factories and the site of enterprises by such modes of transport as rail, trucks, etc. Covered are the following: definitions of terms, places of fuel materials handling, loading methods, limitations on mix loading with other cargo, radiation dose rates concerning the containers and the vehicles, transport indexes, signs and indications, limitations on train linkage during transport by rail, security guards, transport of empty containers, etc. together with ordinary rail cargo and so on. (Mori, K.)

Electron and impurity transport studies in the TCV Tokamak

Energy Technology Data Exchange (ETDEWEB)

Wagner, D.

2013-05-15

In this thesis electron and impurity transport are studied in the Tokamak à Configuration Variable (TCV) located at CRPP-EPFL in Lausanne. Understanding particle transport is primordial for future nuclear fusion power plants. Modeling of experiments in many specific plasma scenarios can help to understand the common elements of the physics at play and to interpret apparently contradictory experiments on the same machine and across different machines. The first part of this thesis deals with electron transport in TCV high confinement mode plasmas. It was observed that the electron density profile in these plasmas flatten when intense electron heating is applied, in contrast to observations on other machines where the increase of the profile peakedness was reported. It is shown with quasi-linear gyrokinetic simulations that this effect, usually interpreted as collisionality dependence, stems from the combined effect of many plasma parameters. The influence of the collisionality, electron to ion temperature ratio, the ratio of temperature gradients, and the Ware-pinch are studied with detailed parameter scans. It is shown that the complex interdependence of the various plasma parameters is greatly simplified when the simulation results are interpreted as a function of the average frequency of the main modes contributing to radial transport. In this way the model is able to explain the experimental results. It was also shown that the same basic understanding is at play in L-modes, H-modes and electron internal transport barriers. The second part of the thesis is devoted to impurity transport. A multi-purpose gas injection system is developed, commissioned and calibrated. It is shown that the system is capable of massive gas injections to provoke disruptions and delivering small puffs of gaseous impurities for perturbative transport experiments. This flexible tool is exploited in a series of impurity transport measurements with argon and neon injections. The impurities

Electron and impurity transport studies in the TCV Tokamak

International Nuclear Information System (INIS)

Wagner, D.

2013-05-01

In this thesis electron and impurity transport are studied in the Tokamak à Configuration Variable (TCV) located at CRPP-EPFL in Lausanne. Understanding particle transport is primordial for future nuclear fusion power plants. Modeling of experiments in many specific plasma scenarios can help to understand the common elements of the physics at play and to interpret apparently contradictory experiments on the same machine and across different machines. The first part of this thesis deals with electron transport in TCV high confinement mode plasmas. It was observed that the electron density profile in these plasmas flatten when intense electron heating is applied, in contrast to observations on other machines where the increase of the profile peakedness was reported. It is shown with quasi-linear gyrokinetic simulations that this effect, usually interpreted as collisionality dependence, stems from the combined effect of many plasma parameters. The influence of the collisionality, electron to ion temperature ratio, the ratio of temperature gradients, and the Ware-pinch are studied with detailed parameter scans. It is shown that the complex interdependence of the various plasma parameters is greatly simplified when the simulation results are interpreted as a function of the average frequency of the main modes contributing to radial transport. In this way the model is able to explain the experimental results. It was also shown that the same basic understanding is at play in L-modes, H-modes and electron internal transport barriers. The second part of the thesis is devoted to impurity transport. A multi-purpose gas injection system is developed, commissioned and calibrated. It is shown that the system is capable of massive gas injections to provoke disruptions and delivering small puffs of gaseous impurities for perturbative transport experiments. This flexible tool is exploited in a series of impurity transport measurements with argon and neon injections. The impurities

Techniques to reduce memory requirements for coupled photon-electron transport

International Nuclear Information System (INIS)

Turcksin, Bruno; Ragusa, Jean; Morel, Jim

2011-01-01

In this work, we present two methods to decrease memory needs while solving the photon- electron transport equation. The coupled transport of electrons and photons is of importance in radiotherapy because it describes the interactions of X-rays with matter. One of the issues of discretized electron transport is that the electron scattering is highly forward peaked. A common approximation is to represent the peak in the scattering cross section by a Dirac distribution. This is convenient, but the integration over all angles of this distribution requires the use of Galerkin quadratures. By construction these quadratures impose that the number of flux moments be equal to the number of directions (number of angular fluxes), which is very demanding in terms of memory. In this study, we show that even if the number of moments is not as large as the number of directions, an accurate solution can be obtained when using Galerkin quadratures. Another method to decrease the memory needs involves choosing an appropriate reordering of the energy groups. We show in this paper that an appropriate alternation of photons/electrons groups allows to rewrite one transport problem of n groups as gcd successive transport problems of n/gcd groups where gcd is the greatest common divisor between the number of photon groups and the number of electron groups. (author)

Risk management of onsite transportation of hazardous materials

International Nuclear Information System (INIS)

Wang, O.S.; Field, J.G.

1992-10-01

The US Department of Energy's (DOE) Hanford Site has recently undergone a significant change in its mission. The focus of site-wide operations has been shifted from production to environmental restoration. As a result, there is a significant increase in quantities of the radioactive wastes and other hazardous materials to be packaged and transported onsite. In response to the elevated transportation activities, the operations and engineering contractor for the Hanford Site, Westinghouse Hanford Company (Westinghouse Hanford), is proposing an integrated risk assessment methodology and risk management strategy to further enhance the safe operations of the onsite packaging and transportation activities involving radioactive and other hazardous materials. This paper summarizes Westinghouse Hanford's proposed risk assessment and risk management methodology for onsite transportation of hazardous materials. The proposed Westinghouse Hanford risk assessment and management methodology for onsite packaging and transportation has three integral parts: risk assessment, risk acceptance criteria, and risk minimization process. The purposes are to ensure that the risk for each ongoing transportation activity is acceptable, and to further reduce the overall risk for current and future onsite transportation activities

Center for Electrocatalysis, Transport Phenomena, and Materials (CETM) for Innovative Energy Storage - Final Report

Energy Technology Data Exchange (ETDEWEB)

Soloveichik, Grigorii [GE Global Research, Niskayuna, New York (United States)

2015-11-30

EFRC vision. The direct use of organic hydrides in fuel cells as virtual hydrogen carriers that generate stable organic molecules, protons, and electrons upon electro-oxidation and can be electrochemically charged by re-hydrogenating the oxidized carrier was the major focus of the Center for Electrocatalysis, Transport Phenomena and Materials for Innovative Energy Storage (EFRC-ETM). Compared to a hydrogen-on-demand design that includes thermal decomposition of organic hydrides in a catalytic reactor, the proposed approach is much simpler and does not require additional dehydrogenation catalysts or heat exchangers. Further, this approach utilizes the advantages of a flow battery (i.e., separation of power and energy, ease of transport and storage of liquid fuels) with fuels that have system energy densities similar to current hydrogen PEM fuel cells. EFRC challenges. Two major EFRC challenges were electrocatalysis and transport phenomena. The electrocatalysis challenge addresses fundamental processes which occur at a single molecular catalyst (microscopic level) and involve electron and proton transfer between the hydrogen rich and hydrogen depleted forms of organic liquid fuel and the catalyst. To form stable, non-radical dehydrogenation products from the organic liquid fuel, it is necessary to ensure fast transport of at least two electrons and two protons (per double bond formation). The same is true for the reverse hydrogenation reaction. The transport phenomena challenge addresses transport of electrons to/from the electrocatalyst and the current collector as well as protons across the polymer membrane. Additionally it addresses prevention of organic liquid fuel, water and oxygen transport through the PEM. In this challenge, the transport of protons or molecules involves multiple sites or a continuum (macroscopic level) and water serves as a proton conducting medium for the majority of known sulfonic acid based PEMs. Proton transfer in the presence of

The role of electron-impact vibrational excitation in electron transport through gaseous tetrahydrofuran

Energy Technology Data Exchange (ETDEWEB)

Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Do, T. P. T. [School of Education, Can Tho University, Campus II, 3/2 Street, Xuan Khanh, Ninh Kieu, Can Tho City (Viet Nam); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Konovalov, D. A.; White, R. D. [College of Science, Technology and Engineering, James Cook University, Townsville (Australia); Brunger, M. J., E-mail: michael.brunger@flinders.edu.au, E-mail: darryl.jones@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Jones, D. B., E-mail: michael.brunger@flinders.edu.au, E-mail: darryl.jones@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia)

2015-03-28

In this paper, we report newly derived integral cross sections (ICSs) for electron impact vibrational excitation of tetrahydrofuran (THF) at intermediate impact energies. These cross sections extend the currently available data from 20 to 50 eV. Further, they indicate that the previously recommended THF ICS set [Garland et al., Phys. Rev. A 88, 062712 (2013)] underestimated the strength of the electron-impact vibrational excitation processes. Thus, that recommended vibrational cross section set is revised to address those deficiencies. Electron swarm transport properties were calculated with the amended vibrational cross section set, to quantify the role of electron-driven vibrational excitation in describing the macroscopic swarm phenomena. Here, significant differences of up to 17% in the transport coefficients were observed between the calculations performed using the original and revised cross section sets for vibrational excitation.

Humidity effects on the electronic transport properties in carbon based nanoscale device

International Nuclear Information System (INIS)

He, Jun; Chen, Ke-Qiu

2012-01-01

By applying nonequilibrium Green's functions in combination with the density functional theory, we investigate the effect of humidity on the electronic transport properties in carbon based nanoscale device. The results show that different humidity may form varied localized potential barrier, which is a very important factor to affect the stability of electronic transport in the nanoscale system. A mechanism for the humidity effect is suggested. -- Highlights: ► Electronic transport in carbon based nanoscale device. ► Humidity affects the stability of electronic transport. ► Different humidity may form varied localized potential barrier.

State-specific transport properties of electronically excited Ar and C

Science.gov (United States)

Istomin, V. A.; Kustova, E. V.

2018-05-01

In the present study, a theoretical model of state-resolved transport properties in electronically excited atomic species developed earlier is applied to argon and carbon atomic species. It is shown that for Ar and C, similarly to the case of atomic nitrogen and oxygen, the Slater-like models can be applied to calculate diameters of electronically excited atoms. Using the Slater-like model it is shown that for half-filled N (2 px1py1pz1) and full-filled Ar (3 px2py2pz2) electronic shells the growth of atomic radius goes slowly compared to C (2 px1py1) and O (2 px2py1pz1). The effect of collision diameters on the transport properties of Ar and C is evaluated. The influence of accounted number of electronic levels on the transport coefficients is examined for the case of Boltzmann distributions over electronic energy levels. It is emphasized that in the temperature range 1000-14000 K, for Boltzmann-like distributions over electronic states the number of accounted electronic levels do not influence the transport coefficients. Contrary to this, for higher temperatures T > 14000 K this effect becomes of importance, especially for argon.

Electron transport code theoretical basis

International Nuclear Information System (INIS)

Dubi, A.; Horowitz, Y.S.

1978-04-01

This report mainly describes the physical and mathematical considerations involved in the treatment of the multiple collision processes. A brief description is given of the traditional methods used in electron transport via Monte Carlo, and a somewhat more detailed description, of the approach to be used in the presently developed code

Electrochemical and Electronic Charge Transport Properties of Ni-Doped LiMn2O4 Spinel Obtained from Polyol-Mediated Synthesis

Directory of Open Access Journals (Sweden)

Shuo Yang

2018-05-01

Full Text Available LiNi0.5Mn1.5O4 (LNMO spinel has been extensively investigated as one of the most promising high-voltage cathode candidates for lithium-ion batteries. The electrochemical performance of LNMO, especially its rate performance, seems to be governed by its crystallographic structure, which is strongly influenced by the preparation methods. Conventionally, LNMO materials are prepared via solid-state reactions, which typically lead to microscaled particles with only limited control over the particle size and morphology. In this work, we prepared Ni-doped LiMn2O4 (LMO spinel via the polyol method. The cycling stability and rate capability of the synthesized material are found to be comparable to the ones reported in literature. Furthermore, its electronic charge transport properties were investigated by local electrical transport measurements on individual particles by means of a nanorobotics setup in a scanning electron microscope, as well as by performing DFT calculations. We found that the scarcity of Mn3+ in the LNMO leads to a significant decrease in electronic conductivity as compared to undoped LMO, which had no obvious effect on the rate capability of the two materials. Our results suggest that the rate capability of LNMO and LMO materials is not limited by the electronic conductivity of the fully lithiated materials.

Transport of radioactive materials: the need for radiation protection programmes

International Nuclear Information System (INIS)

Masinza, S.A.

2004-01-01

The increase in the use of radioactive materials worldwide requires that these materials be moved from production sites to the end user or in the case of radioactive waste, from the waste generator to the repository. Tens of millions of packages containing radioactive material are consigned for transport each year throughout the world. The amount of radioactive material in these packages varies from negligible quantities in shipments of consumer products to very large quantities of shipments of irradiated nuclear fuel. Transport is the main way in which the radioactive materials being moved get into the public domain. The public is generally unaware of the lurking danger when transporting these hazardous goods. Thus radiation protection programmes are important to assure the public of the certainty of their safety during conveyance of these materials. Radioactive material is transported by land (road and rail), inland waterways, sea/ocean and air. These modes of transport are regulated by international 'modal' regulations. The international community has formulated controls to reduce the number of accidents and mitigate their consequences should they happen. When accidents involving the transport of radioactive material occur, it could result in injury, loss of life and pollution of the environment. In order to ensure the safety of people, property and the environment, national and international transport regulations have been developed. The appropriate authorities in each state utilise them to control the transport of radioactive material. Stringent measures are required in these regulations to ensure adequate containment, shielding and the prevention of criticality in all spheres of transport, i.e. routine, minor incidents and accident conditions. Despite the extensive application of these stringent safety controls, transport accidents involving packages containing radioactive material have occurred and will continue to occur. When a transport accident occurs, it

Trap-mediated electronic transport properties of gate-tunable pentacene/MoS2 p-n heterojunction diodes.

Science.gov (United States)

Kim, Jae-Keun; Cho, Kyungjune; Kim, Tae-Young; Pak, Jinsu; Jang, Jingon; Song, Younggul; Kim, Youngrok; Choi, Barbara Yuri; Chung, Seungjun; Hong, Woong-Ki; Lee, Takhee

2016-11-10

We investigated the trap-mediated electronic transport properties of pentacene/molybdenum disulphide (MoS 2 ) p-n heterojunction devices. We observed that the hybrid p-n heterojunctions were gate-tunable and were strongly affected by trap-assisted tunnelling through the van der Waals gap at the heterojunction interfaces between MoS 2 and pentacene. The pentacene/MoS 2 p-n heterojunction diodes had gate-tunable high ideality factor, which resulted from trap-mediated conduction nature of devices. From the temperature-variable current-voltage measurement, a space-charge-limited conduction and a variable range hopping conduction at a low temperature were suggested as the gate-tunable charge transport characteristics of these hybrid p-n heterojunctions. Our study provides a better understanding of the trap-mediated electronic transport properties in organic/2-dimensional material hybrid heterojunction devices.

Discrete-ordinates electron transport calculations using standard neutron transport codes

International Nuclear Information System (INIS)

Morel, J.E.

1979-01-01

The primary purpose of this work was to develop a method for using standard neutron transport codes to perform electron transport calculations. The method is to develop approximate electron cross sections which are sufficiently well-behaved to be treated with standard S/sub n/ methods, but which nonetheless yield flux solutions which are very similar to the exact solutions. The main advantage of this approach is that, once the approximate cross sections are constructed, their multigroup Legendre expansion coefficients can be calculated and input to any standard S/sub n/ code. Discrete-ordinates calculations were performed to determine the accuracy of the flux solutions for problems corresponding to 1.0-MeV electrons incident upon slabs of aluminum and gold. All S/sub n/ calculations were compared with similar calculations performed with an electron Monte Carlo code, considered to be exact. In all cases, the discrete-ordinates solutions for integral flux quantities (i.e., scalar flux, energy deposition profiles, etc.) are generally in agreement with the Monte Carlo solutions to within approximately 5% or less. The central conclusion is that integral electron flux quantities can be efficiently and accurately calculated using standard S/sub n/ codes in conjunction with approximate cross sections. Furthermore, if group structures and approximate cross section construction are optimized, accurate differential flux energy spectra may also be obtainable without having to use an inordinately large number of energy groups. 1 figure

US perspective of transporting radioactive materials by sea

International Nuclear Information System (INIS)

Chitwood, R.B.

1978-01-01

The reason for the US interest in transportation of radioactive materials by sea is discussed. The national and international institutional considerations related to this subject are covered. Some economic aspects in transporting these materials, particularly spent fuels, by sea are also presented

Electrons in a positive-ion beam with solenoid or quadrupole magnetic transport

International Nuclear Information System (INIS)

Molvik, A.W.; Kireeff Covo, M.; Cohen, R.; Coleman, J.; Sharp, W.; Bieniosek, F.; Friedman, A.; Roy, P.K.; Seidl, P.; Lund, S.M.; Faltens, A.; Vay, J.L.; Prost, L.

2007-01-01

The High Current Experiment (HCX) is used to study beam transport and accumulation of electrons in quadrupole magnets and the Neutralized Drift-Compression Experiment (NDCX) to study beam transport through and accumulation of electrons in magnetic solenoids. We find that both clearing and suppressor electrodes perform as intended, enabling electron cloud densities to be minimized. Then, the measured beam envelopes in both quadrupoles and solenoids agree with simulations, indicating that theoretical beam current transport limits are reliable, in the absence of electrons. At the other extreme, reversing electrode biases with the solenoid transport effectively traps electrons; or, in quadrupole magnets, grounding the suppressor electrode allows electron emission from the end wall to flood the beam, in both cases producing significant degradation in the beam

The recent international situation on the transport of radioactive material and IAEA 2003 transport conference

International Nuclear Information System (INIS)

Tani, Hiroshi

2003-01-01

Since the creation of the United Nations, the international community initiated efforts to harmonize international practices for the safe transport of hazardous goods, including radioactive material. And, IAEA is playing a key role in fostering the establishment of transport regulations on radioactive material. This current worldwide system of regulatory control has achieved an excellent safety record. However, some concerns still remain regarding the transport of radioactive material, as the discussion of this topic at IAEA General Conferences in the last few years. IAEA Transport conference planed as a forum in which to better understand these concerns, and to answer relevant underlying questions. At the same time, outside these technical areas, discussions also covered related issues such as liability resulting from an accident during the transport and communication between concerned governments, and between these governments and the public at large. The International Conference on the Safety of Transport of Radioactive Material took place in Vienna, Austria, from 7 to 11 July 2003. There were 534 nominated participants from 82 States, 9 intergovernmental organizations (IGOs), and 5 non-governmental organizations (NGOs), and there were 132 contributed and invited papers. By this report, I report the recent international situation on the transport of radioactive material and result of the IAEA 2003 Transport Conference. (author)

Transport of a nonneutral electron plasma due to electron collisions with neutral atoms

International Nuclear Information System (INIS)

Douglas, M.H.; O'Neil, T.M.

1978-01-01

Transport of a nonneutral electron plasma across a magnetic field is caused by electron scattering from ambient neutral atoms. A theoretical model of such transport is presented, assuming the plasma is quiescent and the scattering is elastic scattering from infinite mass scattering centers of constant momentum transfer cross section. This model is motivated by recent experiments. A reduced transport equation is obtained by expanding the Boltzmann equation for the electron distribution in inverse powers of the magnetic field. The equation together with Poisson's equation for the radial electric field, which must exist in a nonneutral column, determine the evolution of the system. When these two equations are properly scaled, they contain only a single parameter: the ratio of initial Debye length to initial column radius. For cases where this parameter is either large or small, analytical solutions, or at least partial solutions, are obtained. For intermediate values of the parameter, numerical solutions are obtained

Safe transport of radioactive material. Second edition

International Nuclear Information System (INIS)

1991-01-01

The transport of radioactive material embraces the carriage of radioisotopes for industrial, medical and research uses, and the movement of waste, in addition to consignments of nuclear fuel cycle material. It has been estimated that between eighteen and thirty-eight million package shipments take place each year. On the recommendation of the Standing Advisory Group on the Safe Transport of Radioactive Material (SAGSTRAM), which enjoys wide representations from the Agency's Member States and international organizations, the Secretariat is preparing a training kit comprising this training manual and complementary visual aids. The kit is intended to be the basis for an extensive course on the subject and can be used in whole or in part for inter-regional, regional and even national training purposes. Member States can thus benefit from the material either through training courses sponsored by the Agency, or, alternatively, organized by themselves. As a step towards achieving that goal, the current training manual was compiled using material from the first Inter-Regional Training Course on the Safe Transport of Radioactive material that was held in co-operation with the Nuclear Power Training Centre of the then Central Electricity Generating Board at Bristol, United Kingdom. This Manual was initially published in 1990. On the recommendation of the Agency's Standing Advisory Group on the Safe Transport of Radioactive Material (SAGSTRAM), the Manual has since been expanded and updated in time for the second Inter-Regional Training Course, that will in 1991 similarly be held in Bristol. Refs, figs, tabs

The Transport of Radioactive Materials under special arrangement

International Nuclear Information System (INIS)

Biaggio, A.L.; Vietri, J.R.L.

1993-01-01

The Agency's Regulations for the Safe Transport of Radioactive Material rule the international transport of these materials and provide the basis of national and regional regulations. The Regulations establish the technical, operational and administrative requirements which shall be accomplished to carry out the transport of radioactive materials (RAM). They also allow the transport in different conditions of those currently applicable and, in such cases, establish that the transport shall be made under special arrangement. To approve a transport under special arrangement the involved Competent Authority shall be satisfied that the alternative provisions are adequate to ensure that the overall level of safety in transport and in-transit storage is at least equivalent to that which would be provided if all the applicable requirements had been met (para. 2ll of the International Atomic Energy Agency Safety Series No. 6). This paper explains some difficulties the Argentine Competent. Authority has experienced trying by comparing the equivalence between the level of safety resulting from the compliance with current requirements and the overall level of safety which is provided by the application of alternative provisions. As most of the experience gained come from the transport of RAM by road, only this mode of transport is considered. (J.P.N.)

Transport of bundles and equipment which contain radioactive material

International Nuclear Information System (INIS)

1987-01-01

This norm settles down: 1) The requirements that should be completed in relation to safety precautions and protection against ionizing radiations during the transport radioactive material and/or equipment containing it, in order to avoid risks to the collective and the environment. 2) The basic information on procedures that will be completed in the event of happening accidents during the transport or the transit storage of radioactive material and/or equipment that contain it. 3) The measures of security and physical protection during the transport of radioactive material and/or equipment containing it. This norm is applied: 1) To all the ways of transport (by air, by ground and by ship, fluvial and marine) of radioactive material and/or equipment that contain it. 2) To all natural or legal, public or private person, devoted to install, produce, trade, market, import or export radioactive materials and/or equipment containing it, and that needs to transport them as main or secondary activity [es

Radioactive material transport

International Nuclear Information System (INIS)

White, M.C.

1979-10-01

All movements of radioactive materials in Canada are governed by a comprehensive body of regqlations, both national and international. These regulations are designed to maximize shielding to the public and transport workers, allow for heat dissipation, and to prevent criticality accidents, by prescribing specific packaging arrangements, administrative controls, labelling and storage measures. This report describes in some detail specific requirements and summarizes some incidents that occurred between 1974 and 1978

Electron and ion beam transport to fusion targets

International Nuclear Information System (INIS)

Freeman, J.R.; Baker, L.; Miller, P.A.; Mix, L.P.; Olsen, J.N.; Poukey, J.W.; Wright, T.P.

1979-01-01

ICF reactors have been proposed which incorporate a gas-filled chamber to reduce x-ray and debris loading of the first wall. Focused beams of either electrons or ions must be transported efficiently for 2-4 m to a centrally located fusion target. Laser-initiated current-carrying plasma discharge channels provide the guiding magnetic field and the charge- and current-neutralizing medium required for beam propagation. Computational studies of plasma channel formation in air using a 1-D MHD model with multigroup radiation diffusion have provided a good comparison with the expansions velocity and time dependent refractivity profile determined by holographic interferometry. Trajectory calculations have identified a beam expansion mechanism which combines with the usual ohmic dissipation to reduce somewhat the transported beam fluence for electrons. Additional trajectory calculations have been performed for both electrons and light ions to predict the limits on the particle current density which can be delivered to a central target by overlapping the many independently-generated beams. Critical features of the use of plasma channels for transport and overlap of charged particle beams are being tested experimentally with up to twelve electron beams from the Proto II accelerator

Colligative thermoelectric transport properties in n-type filled CoSb3 determined by guest electrons in a host lattice

International Nuclear Information System (INIS)

Lim, Young Soo; Park, Kwan-Ho; Tak, Jang Yeul; Lee, Soonil; Seo, Won-Seon; Park, Cheol-Hee; Kim, Tae Hoon; Park, PumSuk; Kim, Il-Ho; Yang, Jihui

2016-01-01

Among many kinds of thermoelectric materials, CoSb 3 has received exceptional attention for automotive waste heat recovery. Its cage structure provides an ideal framework for the realization of phonon-glass electron-crystal strategy, and there have been numerous reports on the enhanced thermoelectric performance through the independent control of the thermal and electrical conductivity by introducing fillers into its cage sites. Herein, we report colligative thermoelectric transport properties in n-type CoSb 3 from the viewpoint of “guest electrons in a host lattice.” Both the Seebeck coefficient and the charge transport properties are fundamentally determined by the concentration of the guest electrons, which are mostly donated by the fillers, in the conduction band of the host CoSb 3 . Comparing this observation to our previous results, colligative relations for both the Seebeck coefficient and the mobility were deduced as functions of the carrier concentration, and thermoelectric transport constants were defined to predict the power factor in filled CoSb 3 . This discovery not only increases the degree of freedom for choosing a filler but also provides the predictability of power factor in designing and engineering the n-type filled CoSb 3 materials.

Test for radioactive material transport package safety

International Nuclear Information System (INIS)

Li Guoqiang; Zhao Bing; Zhang Jiangang; Wang Xuexin; Ma Anping

2012-01-01

Regulations on radioactive material transport in China were introduced. Test facilities and data acquiring instruments for radioactive material package in China Institute for Radiation Protection were also introduced in this paper, which were used in drop test and thermal test. Test facilities were constructed according to the requirements of IAEA's 'Regulations for the Safe Transport of Radioactive Material' (TS-R-l) and Chinese 'Regulations for the Safe Transport of Radioactive Material' (GB 11806-2004). Drop test facilities were used in free drop test, penetration test, mechanical test (free drop test Ⅰ, free drop test Ⅱ and free drop test Ⅲ) of type A and type B packages weighing less than thirteen tons. Thermal test of type B packages can be carried out in the thermal test facilities. Certification tests of type FCo70-YQ package, type 30A-HB-01 package, type SY-I package and type XAYT-I package according to regulations were done using these facilities. (authors)

Safe transport of radioactive material. 4. ed

International Nuclear Information System (INIS)

2006-01-01

The IAEA has been publishing Regulations for the Safe Transport of Radioactive Material since 1961. Meeting its statutory obligation to foster the exchange and training of scientists and experts in the field of peaceful uses of atomic energy, the IAEA has developed a standardized approach to transport safety training. This training manual is an anchor of the standardized approach to training. It is a compendium of training modules for courses related to the different aspects of safety of transport of radioactive material. Keeping in view the specific needs of the potential users, the manual includes material that can be used for a variety of training programmes of duration ranging from half-a-day to ten days, for specific audiences such as competent authority personnel, public authorities, emergency response personnel and cargo handlers

Kinetic Theory of Electronic Transport in Random Magnetic Fields

Science.gov (United States)

Lucas, Andrew

2018-03-01

We present the theory of quasiparticle transport in perturbatively small inhomogeneous magnetic fields across the ballistic-to-hydrodynamic crossover. In the hydrodynamic limit, the resistivity ρ generically grows proportionally to the rate of momentum-conserving electron-electron collisions at large enough temperatures T . In particular, the resulting flow of electrons provides a simple scenario where viscous effects suppress conductance below the ballistic value. This new mechanism for ρ ∝T2 resistivity in a Fermi liquid may describe low T transport in single-band SrTiO3 .

Multidimensional electron-photon transport with standard discrete ordinates codes

International Nuclear Information System (INIS)

Drumm, C.R.

1995-01-01

A method is described for generating electron cross sections that are compatible with standard discrete ordinates codes without modification. There are many advantages of using an established discrete ordinates solver, e.g. immediately available adjoint capability. Coupled electron-photon transport capability is needed for many applications, including the modeling of the response of electronics components to space and man-made radiation environments. The cross sections have been successfully used in the DORT, TWODANT and TORT discrete ordinates codes. The cross sections are shown to provide accurate and efficient solutions to certain multidimensional electronphoton transport problems

A computer code package for electron transport Monte Carlo simulation

International Nuclear Information System (INIS)

Popescu, Lucretiu M.

1999-01-01

A computer code package was developed for solving various electron transport problems by Monte Carlo simulation. It is based on condensed history Monte Carlo algorithm. In order to get reliable results over wide ranges of electron energies and target atomic numbers, specific techniques of electron transport were implemented such as: Moliere multiscatter angular distributions, Blunck-Leisegang multiscatter energy distribution, sampling of electron-electron and Bremsstrahlung individual interactions. Path-length and lateral displacement corrections algorithms and the module for computing collision, radiative and total restricted stopping powers and ranges of electrons are also included. Comparisons of simulation results with experimental measurements are finally presented. (author)

Nonlinear electron transport in magnetized laser plasmas

International Nuclear Information System (INIS)

Kho, T.H.; Haines, M.G.

1986-01-01

Electron transport in a magnetized plasma heated by inverse bremsstrahlung is studied numerically using a nonlinear Fokker--Planck model with self-consistent E and B fields. The numerical scheme is described. Nonlocal transport is found to alter many of the transport coefficients derived from linear transport theory, in particular, the Nernst and Righi--Leduc effects, in addition to the perpendicular heat flux q/sub perpendicular/, are substantially reduced near critical surface. The magnetic field, however, remains strongly coupled to the nonlinear q/sub perpendicular/ and, as has been found in hydrosimulations, convective amplification of the magnetic field occurs in the overdense plasma

Low energy electron transport in furfural

OpenAIRE

Lozano, Ana I.; Krupa, K.; Ferreira da Silva, F.; Limao-Vieira, Paulo; Blanco, Francisco; Muñoz, Antonio; Jones, D. B.; Brunger, M. J.; García, Gustavo

2017-01-01

We report on an initial investigation into the transport of electrons through a gas cell containing 1 mTorr of gaseous furfural. Results from our Monte Carlo simulation are implicitly checked against those from a corresponding electron transmission measurement. To enable this simulation a self-consistent cross section data base was constructed. This data base is benchmarked through new total cross section measurements which are also described here. In addition, again to facilitate the simulat...

Modelling of electron transport and of sawtooth activity in tokamaks

International Nuclear Information System (INIS)

Angioni, C.

2001-10-01

Transport phenomena in tokamak plasmas strongly limit the particle and energy confinement and represent a crucial obstacle to controlled thermonuclear fusion. Within the vast framework of transport studies, three topics have been tackled in the present thesis: first, the computation of neoclassical transport coefficients for general axisymmetric equilibria and arbitrary collisionality regime; second, the analysis of the electron temperature behaviour and transport modelling of plasma discharges in the Tokamak a configuration Variable (TCV); third, the modelling and simulation of the sawtooth activity with different plasma heating conditions. The work dedicated to neoclassical theory has been undertaken in order to first analytically identify a set of equations suited for implementation in existing Fokker-Planck codes. Modifications of these codes enabled us to compute the neoclassical transport coefficients considering different realistic magnetic equilibrium configurations and covering a large range of variation of three key parameters: aspect ratio, collisionality, and effective charge number. A comparison of the numerical results with an analytical limit has permitted the identification of two expressions for the trapped particle fraction, capable of encapsulating the geometrical effects and thus enabling each transport coefficient to be fitted with a single analytical function. This has allowed us to provide simple analytical formulae for all the neoclassical transport coefficients valid for arbitrary aspect ratio and collisionality in general realistic geometry. This work is particularly useful for a correct evaluation of the neoclassical contribution in tokamak scenarios with large bootstrap cur- rent fraction, or improved confinement regimes with low anomalous transport and for the determination of the plasma current density profile, since the plasma conductivity is usually assumed neoclassical. These results have been included in the plasma transport code

Ion beam processing of advanced electronic materials

International Nuclear Information System (INIS)

Cheung, N.W.; Marwick, A.D.; Roberto, J.B.

1989-01-01

This report contains research programs discussed at the materials research society symposia on ion beam processing of advanced electronic materials. Major topics include: shallow implantation and solid-phase epitaxy; damage effects; focused ion beams; MeV implantation; high-dose implantation; implantation in III-V materials and multilayers; and implantation in electronic materials. Individual projects are processed separately for the data bases

Perceptions, perspectives, proportions: Radioactive material transport

International Nuclear Information System (INIS)

1985-01-01

Nearly a hundred years ago in 1893 - when railroads still monopolized land transport, the first set of international rules governing shipments of hazardous materials were issued to cover their movement by rail. Since then, more than a dozen international bodies, and scores of national regulatory agencies, have published regulations directed at the carriage of dangerous goods by road, sea, air, as well as rail. The regulatory network today covers virtually all kinds of substances and commodities that are used for beneficial purposes, but that under certain conditions are potentially harmful to people and the environment. 'The Problems Encountered by International Road Transport in Multimodal Transport Operations', by M. Marmy, paper presented at the 8th International Symposium on the Transport and Handling of Dangerous Goods by Sea and Associated Modes, Havana, Cuba, 1984. These include the chemical fertilizers farmers spread on their fields, the nuclear fuel now powering electricity plants in some two dozen countries, the drugs physicians use to diagnose and treat illnesses, and the fossil fuels, such as gasoline, routinely used in transport vehicles. All told today, about 21 different international labels are required to identify separate classes of dangerous goods among them, explosives, corrosives, and flammables. Another separate class radioactive materials is the specific subject of feature articles in this issue of the IAEA Bulletin. The evolving regulatory system reflects at once the growth in traffic of hazardous materials, essentially a post-World War II trend. Since the mid-1940s, for example, the transport of all dangerous goods just on the seas has grown 1000%. based on reports at a recent international conference. Overall, years ahead will see further increases

Understanding the effects of electronic polarization and delocalization on charge-transport levels in oligoacene systems

KAUST Repository

Sutton, Christopher; Tummala, Naga Rajesh; Kemper, Travis; Aziz, Saadullah G.; Sears, John; Coropceanu, Veaceslav; Bredas, Jean-Luc

2017-01-01

Electronic polarization and charge delocalization are important aspects that affect the charge-transport levels in organic materials. Here, using a quantum mechanical/ embedded-charge (QM/EC) approach based on a combination of the long-range corrected omega B97X-D exchange-correlation functional (QM) and charge model 5 (CM5) point-charge model (EC), we evaluate the vertical detachment energies and polarization energies of various sizes of crystalline and amorphous anionic oligoacene clusters. Our results indicate that QM/EC calculations yield vertical detachment energies and polarization energies that compare well with the experimental values obtained from ultraviolet photoemission spectroscopy measurements. In order to understand the effect of charge delocalization on the transport levels, we considered crystalline naphthalene systems with QM regions including one or five-molecules. The results for these systems show that the delocalization and polarization effects are additive; therefore, allowing for electron delocalization by increasing the size of the QM region leads to the additional stabilization of the transport levels. Published by AIP Publishing.

Understanding the effects of electronic polarization and delocalization on charge-transport levels in oligoacene systems

KAUST Repository

Sutton, Christopher

2017-06-13

Electronic polarization and charge delocalization are important aspects that affect the charge-transport levels in organic materials. Here, using a quantum mechanical/ embedded-charge (QM/EC) approach based on a combination of the long-range corrected omega B97X-D exchange-correlation functional (QM) and charge model 5 (CM5) point-charge model (EC), we evaluate the vertical detachment energies and polarization energies of various sizes of crystalline and amorphous anionic oligoacene clusters. Our results indicate that QM/EC calculations yield vertical detachment energies and polarization energies that compare well with the experimental values obtained from ultraviolet photoemission spectroscopy measurements. In order to understand the effect of charge delocalization on the transport levels, we considered crystalline naphthalene systems with QM regions including one or five-molecules. The results for these systems show that the delocalization and polarization effects are additive; therefore, allowing for electron delocalization by increasing the size of the QM region leads to the additional stabilization of the transport levels. Published by AIP Publishing.

30 CFR 75.1403-2 - Criteria-Hoists transporting materials; brakes.

Science.gov (United States)

2010-07-01

... Mantrips § 75.1403-2 Criteria—Hoists transporting materials; brakes. Hoists and elevators used to transport materials should be equipped with brakes capable of stopping and holding the fully loaded platform, cage... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Criteria-Hoists transporting materials; brakes...

Electron heat transport in shaped TCV L-mode plasmas

International Nuclear Information System (INIS)

Camenen, Y; Pochelon, A; Bottino, A; Coda, S; Ryter, F; Sauter, O; Behn, R; Goodman, T P; Henderson, M A; Karpushov, A; Porte, L; Zhuang, G

2005-01-01

Electron heat transport experiments are performed in L-mode discharges at various plasma triangularities, using radially localized electron cyclotron heating to vary independently both the electron temperature T e and the normalized electron temperature gradient R/L T e over a large range. Local gyro-fluid (GLF23) and global collisionless gyro-kinetic (LORB5) linear simulations show that, in the present experiments, trapped electron mode (TEM) is the most unstable mode. Experimentally, the electron heat diffusivity χ e is shown to decrease with increasing collisionality, and no dependence of χ e on R/L T e is observed at high R/L T e values. These two observations are consistent with the predictions of TEM simulations, which supports the fact that TEM plays a crucial role in electron heat transport. In addition, over the broad range of positive and negative triangularities investigated, the electron heat diffusivity is observed to decrease with decreasing plasma triangularity, leading to a strong increase of plasma confinement at negative triangularity

Thermal transport in phosphorene and phosphorene-based materials: A review on numerical studies

Science.gov (United States)

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

2018-03-01

The recently discovered two-dimensional (2D) layered material phosphorene has attracted considerable interest as a promising p-type semiconducting material. In this article, we review the recent advances in numerical studies of the thermal properties of monolayer phosphorene and phosphorene-based heterostructures. We first briefly review the commonly used first-principles and molecular dynamics (MD) approaches to evaluate the thermal conductivity and interfacial thermal resistance of 2D phosphorene. Principles of different steady-state and transient MD techniques have been elaborated on in detail. Next, we discuss the anisotropic thermal transport of phosphorene in zigzag and armchair chiral directions. Subsequently, the in-plane and cross-plane thermal transport in phosphorene-based heterostructures such as phosphorene/silicon and phosphorene/graphene is summarized. Finally, the numerical research in the field of thermal transport in 2D phosphorene is highlighted along with our perspective of potentials and opportunities of 2D phosphorenes in electronic applications such as photodetectors, field-effect transistors, lithium ion batteries, sodium ion batteries, and thermoelectric devices.

Subthreshold electrical transport in amorphous phase-change materials

International Nuclear Information System (INIS)

Gallo, Manuel Le; Kaes, Matthias; Sebastian, Abu; Krebs, Daniel

2015-01-01

Chalcogenide-based phase-change materials play a prominent role in information technology. In spite of decades of research, the details of electrical transport in these materials are still debated. In this article, we present a unified model based on multiple-trapping transport together with 3D Poole–Frenkel emission from a two-center Coulomb potential. With this model, we are able to explain electrical transport both in as-deposited phase-change material thin films, similar to experimental conditions in early work dating back to the 1970s, and in melt-quenched phase-change materials in nanometer-scale phase-change memory devices typically used in recent studies. Experimental measurements on two widely different device platforms show remarkable agreement with the proposed mechanism over a wide range of temperatures and electric fields. In addition, the proposed model is able to seamlessly capture the temporal evolution of the transport properties of the melt-quenched phase upon structural relaxation. (paper)

INES- French application to radioactive material transport

International Nuclear Information System (INIS)

Sowinski, S.; Strawa, S.; Aguilar, J.

2004-01-01

After gaining control of radioactive material transport in June 1997, the French Nuclear Safety Authority (ASN) decided to apply the International Nuclear Event Scale (INES scale) to transport events. The Directorate General for Nuclear Safety and Radioprotection (DGSNR) requests that radioactive material package consignors declare any event occurring during transport, and has introduced the use of the INES scale adapted to classify transport events in order to inform the public and to have feedback. The INES scale is applicable to events arising in nuclear installations associated with the civil nuclear industry and events occurring during the transport of radioactive materials to and from them. The INES scale consists of seven levels. It is based on the successive application of three types of criterion (off-site impact, on-site impact and degradation of defence in depth) and uses the maximum level to determine the rating of an accident. As the transport in question takes place on public thoroughfares, only the off-site impact criteria and degradation of defence in-depth criteria apply. This paper deals with DGSNR's feedback during the past 7 years concerning the French application of the INES scale. Significant events that occurred during transport are presented. The French experience was used by the International Atomic Energy Agency (IAEA) to develop a draft guide in 2002 and the IAEA asked countries to use a new draft for a trial period in July 2004. (author)

Hybrid transport and diffusion modeling using electron thermal transport Monte Carlo SNB in DRACO

Science.gov (United States)

Chenhall, Jeffrey; Moses, Gregory

2017-10-01

The iSNB (implicit Schurtz Nicolai Busquet) multigroup diffusion electron thermal transport method is adapted into an Electron Thermal Transport Monte Carlo (ETTMC) transport method to better model angular and long mean free path non-local effects. Previously, the ETTMC model had been implemented in the 2D DRACO multiphysics code and found to produce consistent results with the iSNB method. Current work is focused on a hybridization of the computationally slower but higher fidelity ETTMC transport method with the computationally faster iSNB diffusion method in order to maximize computational efficiency. Furthermore, effects on the energy distribution of the heat flux divergence are studied. Work to date on the hybrid method will be presented. This work was supported by Sandia National Laboratories and the Univ. of Rochester Laboratory for Laser Energetics.

The Safe Transportation of Radioactive Materials

International Nuclear Information System (INIS)

Megrahi, Abdulhafeed; Abu-Ali, Giuma; Enhaba; Ahmed

2008-01-01

In this paper, we present the essential conditions that should be required for transporting the radioactive materials. We demonstrate the procedure for transporting the radioactive iodine-131 from the Centre of Renewable Energies and Desalination of Water in Tajoura, Libya to Tripoli Medical Center. The safe measures were taken during the process of the transportation of the isotope produced in the centre including dosimetry analysis and the thickness of the container. (author)

The transport of radioactive materials - Future challenges

International Nuclear Information System (INIS)

Wilkinson, W.L.

2008-01-01

The International Atomic Energy Agency (IAEA) Regulations for the Safe Transport of Radioactive Materials, TS-R-1, set the standards for the packages used in the transport of radioactive materials under both normal and accident conditions. Transport organisations are also required to implement Radiation Protection Programmes to control radiation dose exposure to both workers and the public. The industry has now operated under this regulatory regime safely and efficiently for nearly 50 years. It is vital that this record be maintained in the future when the demands on the transport industry are increasing. Nuclear power is being called upon more and more to satisfy the world's growing need for sustainable, clean and affordable electricity and there will be a corresponding demand for nuclear fuel cycle services. There will also be a growing need for other radioactive materials, notably large sources such as Cobalt 60 sources for a range of important medical and industrial uses, as well as radio-pharmaceuticals. A reliable transport infrastructure is essential to support all these industry sectors and the challenge will be to ensure that this can be maintained safely and securely in a changing world where public and political concerns are increasing. This paper will discuss the main issues which need to be addressed. The demand for uranium has led to increased exploration and the development of mines in new locations far removed from the demand centres. This inevitably leads to more transport, sometimes from areas potentially lacking in transport infrastructure, service providers, and experience. The demand for sources for medical applications will also increase, particularly from the rapidly developing regions and this will also involve new transport routes and increased traffic. This raises a variety of issues concerning the ability of the transport infrastructure to meet the future challenge, particularly in an environment where there already exists reluctance on

Angular dependent transport of auroral electrons in the upper atmosphere

International Nuclear Information System (INIS)

Lummerzheim, D.; Rees, M.H.

1989-01-01

The transport of auroral electrons through the upper atmosphere is analyzed. The transport equation is solved using a discrete ordinate method including elastic and inelastic scattering of electrons resulting in changes of pitch angle, and degradation in energy as the electrons penetrate into the atmosphere. The transport equation is solved numerically for the electron intensity as a function of altitude, pitch angle, and energy. In situ measurements of the pitch angle and energy distribution of precipitating electrons over an auroral arc provide boundary conditions for the calculation. The electron spectra from various locations over the aurora present a variety of anisotropic pitch angle distributions and energy spectra. Good agreement is found between the observed backscattered electron energy spectra and model predictions. Differences occur at low energies (below 500 eV) in the structure of the pitch angle distribution. Model calculations were carried out with various different phase functions for elastic and inelastic collisions to attempt changing the angular scattering, but the observed pitch angle distributions remain unexplained. We suggest that mechanisms other than collisional scattering influence the angular distribution of auroral electrons at or below 300 km altitude in the low energy domain. (author)

Transport of radioactive materials

International Nuclear Information System (INIS)

Huck, W.

1992-01-01

The book presents a systematic survey of the legal provisions governing the transport of radioactive materials, placing emphasis on the nuclear licensing provisions of sections 4, 4b of the Atomic Energy, Act (AtG) and sections 8-10 of the Radiation Protection Ordinance (StrlSchV), also considering the provisions of the traffic law governing the carriage of hazardous goods. The author's goal is to establish a systematic basis by comparative analysis of the licensing regulations under atomic energy law, for the purpose of formulating a proposed amendment to the law, for the sake of clarity. The author furthermore looks for and develops criteria that can be of help in distinguishing the regulations governing the carriage of hazardous goods from the nuclear regulatory provisions. He also examines whether such a differentiation is detectable, particularly in those amendments to the StrlSchV which came after the Act on Carriage of Hazardous Goods. The regulations governing the transport of radioactive materials under the AtG meet with the problem of different classification systems being applied, to radioactive materials in the supervisory regulations on the one hand, and to nuclear materials in Annex 1 to the AtG on the other hand. A classification of natural, non-nuclear grade uranium e.g. by the financial security provisions is difficult as a result of these differences in the laws. The author shows that the transport regulations of the StrlSchV represent an isolated supervisory instrument that has no connecting factor to the sections 28 ff StrlSchV, as radiation protection is provided for by the regulations of the Act on Carriage of Hazardous Goods. The author suggests an amendment of existing law incorporating the legal intent of sections 8-10 StrlSchV and of sections 4, 4b AtG into two sections, and abolishing the supervisory provisions of the StrlSchV altogether. (orig./HP) [de

Regulation of Transportation of Radioactive Material in Indonesia

International Nuclear Information System (INIS)

Nirwono, Muttaqin Margo; Choi, Kwang Sik

2011-01-01

1.1. Background Indonesia is a biggest archipelago country with 17,508 islands in 33 provinces. In transportation Indonesia has large number of airports, railways, roadways, waterways, and merchant marines. Since nuclear and radiation utilizations are expanding on whole country, the mobilization of these is usually placed outside of controlled facilities, in the public domain, and often entails movement between countries. The Indonesian Nuclear Energy Regulatory Agency (BAPETEN) is responsible for supervision and also authorization of the transport of radioactive material (TRM). TRM is the specific movement of a radioactive material consignment from origin to destination by public transportation (road or rail, water and air). This study aims to determine whether national regulation is harmonized with international practice in ensuring safety and security of TRM. The finding of this study will provide recommendation for enhancement of regulation on TRM. 1.2. Regulation of TRM in Indonesia Government Regulation (GR) No. 26, 2002 on the Safe Transport of Radioactive Material is implemented pursuant to Act 10, 1997 on Nuclear Energy. This GR was repealed GR 13, 1975 on TRM. The GR 26 consist of 16 chapters and 39 articles, included licensing: authority and responsibilities: packaging: radiation protection programme; training: quality assurance programme: type and activity limit of radioactive materials: radioactive materials with other dangerous properties: emergency preparedness: administrative sanction: and penal provisions. Principally, this GR adopted IAEA-TS-R-1, 'Regulations for the Safe Transport of Radioactive Material', 1996's Edition

Effect of electronic contribution on temperature-dependent thermal transport of antimony telluride thin film

Energy Technology Data Exchange (ETDEWEB)

Lee, Won-Yong; Park, No-Won [Department of Physics, Chung-Ang University, Seoul 156-756 (Korea, Republic of); Hong, Ji-Eun [Department of Materials Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Yoon, Soon-Gil, E-mail: sgyoon@cnu.ac.kr [Department of Materials Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Koh, Jung-Hyuk [School of Electrical and Electronics Engineering, Chung-Ang University, Seoul 156-756 (Korea, Republic of); Lee, Sang-Kwon, E-mail: sangkwonlee@cau.ac.kr [Department of Physics, Chung-Ang University, Seoul 156-756 (Korea, Republic of)

2015-01-25

Highlights: • We investigated thermal transport of the antimony telluride thin films. • The contribution of the electronic thermal conductivity increased up to ∼77% at 300 K. • We theoretically analyze and explain the high contribution of electronic component. - Abstract: We study the theoretical and experimental characteristics of thermal transport of 100 nm and 500 nm-thick antimony telluride (Sb{sub 2}Te{sub 3}) thin films prepared by radio frequency magnetron sputtering. The thermal conductivity was measured at temperatures ranging from 20 to 300 K, using four-point-probe 3-ω method. Out-of-plane thermal conductivity of the Sb{sub 2}Te{sub 3} thin film was much lesser in comparison to the bulk material in the entire temperature range, confirming that the phonon- and electron-boundary scattering are enhanced in thin films. Moreover, we found that the contribution of the electronic thermal conductivity (κ{sub e}) in total thermal conductivity (κ) linearly increased up to ∼77% at 300 K with increasing temperature. We theoretically analyze and explain the high contribution of electronic component of thermal conductivity towards the total thermal conductivity of the film by a modified Callaway model. Further, we find the theoretical model predictions to correspond well with the experimental results.

5-D simulation study of suprathermal electron transport in non-axisymmetric plasmas

International Nuclear Information System (INIS)

Murakami, S.; Idei, H.; Kubo, S.; Nakajima, N.; Okamoto, M.; Gasparino, U.; Maassberg, H.; Rome, M.; Marushchenko, N.

2000-01-01

ECRH driven transport of suprathermal electrons is studied in non-axisymmetric plasmas using a new Monte Carlo simulation technique in 5-D phase space. Two different phases of the ECRH driven transport of suprathermal electrons can be seen. The first is a rapid convective phase due to the direct radial motion of trapped electrons and the second is a slower phase due to the collisional transport. The important role of the radial transport of suprathermal electrons in the broadening of the ECRH deposition profile in W7-AS is clarified. The ECRH driven flux is also evaluated and considered in relation to the 'electron root' feature recently observed in W7-AS. It is found that, at low collisionalities, the ECRH driven flux due to the suprathermal electrons can play a dominant role in the condition of ambipolarity, and thus the observed electron root feature in W7-AS is thought to be driven by the radial (convective) flux of ECRH generated suprathermal electrons. A possible scenario for this type of electron root is considered for the LHD plasma. (author)

5D simulation study of suprathermal electron transport in non-axisymmetric plasmas

International Nuclear Information System (INIS)

Murakami, S.; Idei, H.; Kubo, S.; Nakajima, N.; Okamoto, M.; Gasparino, U.; Maassberg, H.; Rome, M.; Marushchenko, N.

1999-01-01

ECRH-driven transport of suprathermal electrons is studied in non-axisymmetric plasmas using a new Monte Carlo simulation technique in 5D phase space. Two different phases of the ECRH-driven transport of suprathermal electrons can be seen; one is a rapid convective phase due to the direct radial motion of trapped electrons and the other is a slower phase due to the collisional transport. The important role of the radial transport of suprathermal electrons in the broadening of the ECRH deposition profile is clarified in W7-AS. The ECRH driven flux is also evaluated and put in relation with the 'electron root' feature recently observed in W7-AS. It is found that, at low collisionalities, the ECRH driven flux due to the suprathermal electrons can play a dominant role in the condition of ambipolarity and, thus, the observed 'electron root' feature in W7-AS is thought to be driven by the radial (convective) flux of ECRH generated suprathermal electrons. The possible scenario of this 'ECRH-driven electron root' is considered in the LHD plasma. (author)

Role of electron-electron scattering on spin transport in single layer graphene

Directory of Open Access Journals (Sweden)

Bahniman Ghosh

2014-01-01

Full Text Available In this work, the effect of electron-electron scattering on spin transport in single layer graphene is studied using semi-classical Monte Carlo simulation. The D’yakonov-P’erel mechanism is considered for spin relaxation. It is found that electron-electron scattering causes spin relaxation length to decrease by 35% at 300 K. The reason for this decrease in spin relaxation length is that the ensemble spin is modified upon an e-e collision and also e-e scattering rate is greater than phonon scattering rate at room temperature, which causes change in spin relaxation profile due to electron-electron scattering.

Modified Monte Carlo method for study of electron transport in degenerate electron gas in the presence of electron-electron interactions, application to graphene

Science.gov (United States)

Borowik, Piotr; Thobel, Jean-Luc; Adamowicz, Leszek

2017-07-01

Standard computational methods used to take account of the Pauli Exclusion Principle into Monte Carlo (MC) simulations of electron transport in semiconductors may give unphysical results in low field regime, where obtained electron distribution function takes values exceeding unity. Modified algorithms were already proposed and allow to correctly account for electron scattering on phonons or impurities. Present paper extends this approach and proposes improved simulation scheme allowing including Pauli exclusion principle for electron-electron (e-e) scattering into MC simulations. Simulations with significantly reduced computational cost recreate correct values of the electron distribution function. Proposed algorithm is applied to study transport properties of degenerate electrons in graphene with e-e interactions. This required adapting the treatment of e-e scattering in the case of linear band dispersion relation. Hence, this part of the simulation algorithm is described in details.

International Regulations for Transport of Radioactive Materials, History and Security

International Nuclear Information System (INIS)

EL-Shinawy, R.M.K.

2013-01-01

International Regulations for the transport of radioactive materials have been published by International Atomic Energy Agency (IAEA) since 1961. These Regulations have been widely adopted into national Regulations. Also adopted into different modal Regulations such as International Air Transport Association (IATA) and International Martime Organization (IMO). These Regulations provide standards for insuring a high level of safety of general public, transport workers, property and environment against radiation, contamination, criticality hazard and thermal effects associated with the transport of radioactive wastes and materials. Several reviews conducted in consultation with Member States (MS) and concerned international organizations, resulted in comprehensive revisions till now. Radioactive materials are generally transported by specialized transport companies and experts. Shippers and carriers have designed their transport operations to comply with these international Regulations. About 20 million consignments of radioactive materials take place around the world each year. These materials were used in different fields such as medicine, industry, agriculture, research, consumer product and electric power generation. After September 11,2001, the IAEA and MS have worked together to develop a new guidance document concerning the security in the transport of radioactive materials. IAEA have initiated activities to assist MS in addressing the need for transport security in a comprehensive manner. The security guidance and measures were mentioned and discussed. The transport security becomes more developed and integrated into national Regulations of many countries beside the safety Regulations. IAEA and other International organizations are working with MS to implement transport security programs such as guidance, training, security assessments and upgrade assistance in these fields.

Epitaxial graphene electronic structure and transport

International Nuclear Information System (INIS)

De Heer, Walt A; Berger, Claire; Wu Xiaosong; Sprinkle, Mike; Hu Yike; Ruan Ming; First, Phillip N; Stroscio, Joseph A; Haddon, Robert; Piot, Benjamin; Faugeras, Clement; Potemski, Marek; Moon, Jeong-Sun

2010-01-01

Since its inception in 2001, the science and technology of epitaxial graphene on hexagonal silicon carbide has matured into a major international effort and is poised to become the first carbon electronics platform. A historical perspective is presented and the unique electronic properties of single and multilayered epitaxial graphenes on electronics grade silicon carbide are reviewed. Early results on transport and the field effect in Si-face grown graphene monolayers provided proof-of-principle demonstrations. Besides monolayer epitaxial graphene, attention is given to C-face grown multilayer graphene, which consists of electronically decoupled graphene sheets. Production, structure and electronic structure are reviewed. The electronic properties, interrogated using a wide variety of surface, electrical and optical probes, are discussed. An overview is given of recent developments of several device prototypes including resistance standards based on epitaxial graphene quantum Hall devices and new ultrahigh frequency analogue epitaxial graphene amplifiers.

Spin dependent transport of hot electrons through ultrathin epitaxial metallic films

Energy Technology Data Exchange (ETDEWEB)

Heindl, Emanuel

2010-06-23

In this work relaxation and transport of hot electrons in thin single crystalline metallic films is investigated by Ballistic Electron Emission Microscopy. The electron mean free paths are determined in an energy interval of 1 to 2 eV above the Fermi level. While fcc Au-films appear to be quite transmissive for hot electrons, the scattering lengths are much shorter for the ferromagnetic alloy FeCo revealing, furthermore, a strong spin asymmetry in hot electron transport. Additional information is gained from temperature dependent studies in combination with golden rule approaches in order to disentangle the impact of several relaxation and transport properties. It is found that bcc Fe-films are much less effective in spin filtering than films made of the FeCo-alloy. (orig.)

Radiation safety in sea transport of radioactive material in Japan

International Nuclear Information System (INIS)

Odano, N.; Yanagi, H.

2004-01-01

Radiation safety for sea transport of radioactive material in Japan has been discussed based on records of the exposed dose of sea transport workers and measured data of dose rate equivalents distribution inboard exclusive radioactive material shipping vessels. Recent surveyed records of the exposed doses of workers who engaged in sea transport operation indicate that exposed doses of transport workers are significantly low. Measured distribution of the exposed dose equivalents inboard those vessels indicates that dose rate equivalents inside those vessels are lower than levels regulated by the transport regulations of Japan. These facts clarify that radiation safety of inboard environment and handling of transport casks in sea transport of radioactive material in Japan are assured

Radiation safety in sea transport of radioactive material in Japan

Energy Technology Data Exchange (ETDEWEB)

Odano, N. [National Maritime Research Inst., Tokyo (Japan); Yanagi, H. [Nuclear Fuel Transport Co., Ltd., Tokyo (Japan)

2004-07-01

Radiation safety for sea transport of radioactive material in Japan has been discussed based on records of the exposed dose of sea transport workers and measured data of dose rate equivalents distribution inboard exclusive radioactive material shipping vessels. Recent surveyed records of the exposed doses of workers who engaged in sea transport operation indicate that exposed doses of transport workers are significantly low. Measured distribution of the exposed dose equivalents inboard those vessels indicates that dose rate equivalents inside those vessels are lower than levels regulated by the transport regulations of Japan. These facts clarify that radiation safety of inboard environment and handling of transport casks in sea transport of radioactive material in Japan are assured.

Status of radioactive material transport

International Nuclear Information System (INIS)

Kueny, Laurent

2012-01-01

As about 900.000 parcels containing radioactive materials are transported every year in France, the author recalls the main risks and safety principles associated with such transport. He indicates the different types of parcels defined by the regulation: excepted parcels, industrial non fissile parcels (type A), type B and fissile parcels, and highly radioactive type C parcels. He briefly presents the Q-system which is used to classify the parcels. He describes the role of the ASN in the control of transport safety, and indicates the different contracts existing between France or Areva and different countries (Germany, Japan, Netherlands, etc.) for the processing of used fuels in La Hague

The regulation concerning transportation of radioactive materials by vehicles

International Nuclear Information System (INIS)

1978-01-01

The Regulation is established on the basis of The law for the regulations of nuclear source materials, nuclear fuel materials and reactors'' and the ''Law for the prevention of radiation injuries due to radioisotopes.'' The prescriptions cover the transport of radioactive materials by railway, street rail way, ropeway, trolley buses, motorcars and light vehicles. Terms are explained, such as nuclear fuel materials, radioisotopes, radioactive substances, transported radioactive things, transported fissile things, vehicles, containers, exclusive loading, surrounding inspection area. Four types of transported radioactive things are specified, L and A types being less dangerous and BM and BU being more dangerous. Transported fissile things are classified to three kinds according to the safety to criticality of such things. Transported radioactive things except those of L type and containers with transported fissile things shall not be loaded or unloaded at the places where persons other than those concerned come in usually. Loading and unloading of such things shall be carried out so that the safety of such things is not injured. The maximum dose rate of radiation of the containers with transported radioactive things shall not be more than 200 millirem per hour on the surface and 10 millirem per hour at the distance of 1 meter. Specified transported radioactive things shall be particularly marked by the letter of ''radioactive'' or other signs indicating as such. (Okada, K.)

Edge modulation of electronics and transport properties of cliff-edge phosphorene nanoribbons

Science.gov (United States)

Guo, Caixia; Wang, Tianxing; Xia, Congxin; Liu, Yufang

2017-12-01

Based on the first-principles calculations, we study the electronic structures and transport properties of cliff-like edge phosphorene nanoribbons (CPNRs), considering different types of edge passivation. The band structures of bare CPNRs possess the metallic features; while hydrogen (H), fluorine (F), chlorine (Cl) and oxygen (O) atoms-passivated CPNRs are semiconductor materials, and the band gap values monotonically decrease when the ribbon width increases. Moreover, the H and F-passivated CPNRs exhibit the direct band gap characteristics, while the Cl and O-passivated cases show the features of indirect band gap. In addition, the edge passivated CPNRs are more energetically stable than bare edge case. Meanwhile, our results also show that the transport properties of the CPNRs can be obviously influenced by the different edge passivation.

Transportation legislative data base : state radioactive materials transportation statute compilation, 1989-1993

Science.gov (United States)

1994-04-30

The Transportation Legislative Data Base (TLDB) is a computer-based information service containing summaries of federal, state and certain local government statutes and regulations relating to the transportation of radioactive materials in the United...

Development of an expert system for radioactive material transportation

International Nuclear Information System (INIS)

Tamanoi, K.; Ishitobi, M.; Shinohara, Y.

1990-01-01

An expert system to deal with radioactive material transportation was developed. This expert system is based on 'Regulations for the Safe Transport of Radioactive Material' by IAEA issued 1985. IAEA published the regulations under such environments that safety transportation has become increasingly being focused as uses of radioactive materials are more pervasive, not only in nuclear field but also in non-nuclear purposes. Attentions are payed for operators and environment to establish safety in handling radioactive materials. In the 1985 regulations, detailed categorization of radioactive materials and, correspondingly, new classification of packages are introduced. This categorization is more complicated than old regulations, leading us to develop an expert system to evaluate easily the packages categorization. (author)

HA and MAVL technical dialogue - Seminar - Transports of radioactive materials

International Nuclear Information System (INIS)

Charron, Sylvie; Eckert, Benoit; Lizot, Marie-Therese; Moutarde, Marianne; Mermaz, Frederic; Brisson, Nicolas; Sene, Monique; Demet, Michel; Jacquet, Benoit; Tran-Thien, Vivien; Ferran, Ghislain; Michel, Maurice; Barbey, Pierre; Miquel, Thierry-Paul; Monot, Bernard; Syren, Julien; Quintin, Christophe; Gilbert, Alain; Lhuillier, Daniel; Domeneghetti, Bertrand; LOURTIE, Guy; Manessier, Joffray

2016-03-01

This document gathers the content of a debate and Power Point presentations as contributions to this seminar on transports of nuclear materials. After an introduction, the different sessions addressed the actors of the transport of nuclear materials (regulation, parcel design, organisation on the shipper side and on the transporter side), transport safety and radiation protection (returns on experience by different actors and on event follow-up), the follow-up and safety of transports of nuclear materials (protection against malevolent acts, operational follow-up, case of rail transport), and issues related to crisis management (organisation in case of crisis, means of intervention implemented by the IRSN, return on experience for two accidents)

Low resistivity ZnO-GO electron transport layer based CH3NH3PbI3 solar cells

Directory of Open Access Journals (Sweden)

Muhammad Imran Ahmed

2016-06-01

Full Text Available Perovskite based solar cells have demonstrated impressive performances. Controlled environment synthesis and expensive hole transport material impede their potential commercialization. We report ambient air synthesis of hole transport layer free devices using ZnO-GO as electron selective contacts. Solar cells fabricated with hole transport layer free architecture under ambient air conditions with ZnO as electron selective contact achieved an efficiency of 3.02%. We have demonstrated that by incorporating GO in ZnO matrix, low resistivity electron selective contacts, critical to improve the performance, can be achieved. We could achieve max efficiency of 4.52% with our completed devices for ZnO: GO composite. Impedance spectroscopy confirmed the decrease in series resistance and an increase in recombination resistance with inclusion of GO in ZnO matrix. Effect of temperature on completed devices was investigated by recording impedance spectra at 40 and 60 oC, providing indirect evidence of the performance of solar cells at elevated temperatures.

Safe transport of radioactive material. Second edition

International Nuclear Information System (INIS)

1996-01-01

In 1991, the International Atomic Energy Agency published Training Course Series No. 1 (TCS-1), a training manual that provides in 20 chapters a detailed discussion of the background, philosophy, technical bases and requirements and implementation aspects of the Regulations for the Safe Transport of Radioactive Material. The Transport Regulations are widely implemented by the IAEA's Member States and are also used as the bases for radioactive material transport requirements of modal organisations such as the International Maritime Organization and the International Civil Aviation Organization. This document is a supplement of TCS-1 to provide additional material in the form of learning aids and new exercises, that have been developed with the use of TCS-1 at succeeding IAEA training courses. The learning aids in the first part of the supplement are hitherto unpublished material that provide detailed guidance useful in solving the exercises presented in the second part. Solutions to the exercises are on field at the IAEA Secretariat and are available by arrangement to lectures presenting IAEA training courses. 4 refs, 1 fig., 6 tabs

Safe and secure: transportation of radioactive materials

International Nuclear Information System (INIS)

Howe, D.

2015-01-01

Western Waste Management Facility is Central Transportation Facility for Low and Intermediate waste materials. Transportation support for Stations: Reactor inspection tools and heavy water between stations and reactor components and single bundles of irradiated fuel to AECL-Chalk River for examination. Safety Track Record: 3.2 million kilometres safely travelled and no transportation accident - resulting in a radioactive release.

Saturated bonds and anomalous electronic transport in transition-metal aluminides

Energy Technology Data Exchange (ETDEWEB)

Schmidt, T.

2006-05-22

This thesis deals with the special electronic properties of the transition-metal aluminides. Following quasicrystals and their approximants it is shown that even materials with small elementary cells exhibit the same surprising effects. So among the transition-metal aluminides also semi-metallic and semiconducting compounds exist, although if they consist of classic-metallic components like Fe, Al, or Cr. These properties are furthermore coupled with a deep pseusogap respectively gap in the density of states and strongly covalent bonds. Bonds are described in this thesis by two eseential properties. First by the bond charge and second by the energetic effect of the bond. It results that in the caes of semiconducting transition-metal aluminides both a saturation of certain bonds and a bond-antibond alteration in the Fermi level is present. By the analysis of the near-order in form of the so-calles coordination polyeders it has been succeeded to establish a simple rule for semiconductors, the five-fold coordination for Al. This rule states that aluminium atoms with their three valence electrons are not able to build more than five saturated bonds to their nearest transition-metal neighbours. In excellent agreement with the bond angles predicted theoretically under assumption of equal-type bonds it results that all binary transition-element aluminide semiconductors exhibit for the Al atoms the same near order. Typical values for specific resistances of the studied materials at room temperature lie in the range of some 100 {mu}{omega}cm, which is farly larger than some 10 {mu}{omega}cm as in the case of the unalloyed metals. SUrprising is furthermore a high transport anisotropy with a ratio of the specific resistances up to 3.0. An essential result of this thesis can be seen in the coupling of the properties of the electronic transport and the bond properties. The small conducitivities could be explained by small values in the density of states and a bond

Investigation of electronic transport properties of some liquid transition metals

Science.gov (United States)

Patel, H. P.; Sonvane, Y. A.; Thakor, P. B.

2018-04-01

We investigated electronic transport properties of some liquid transition metals (V, Cr, Mn, Fe, Co and Pt) using Ziman formalism. Our parameter free model potential which is realized on ionic and atomic radius has been incorporated with the Hard Sphere Yukawa (HSY) reference system to study the electronic transport properties like electrical resistivity (ρ), thermal conductivity (σ) and thermo electrical power (Q). The screening effect on aforesaid properties has been studied by using different screening functions. The correlations of our results and others data with in addition experimental values are profoundly promising to the researchers working in this field. Also, we conclude that our newly constructed parameter free model potential is capable to explain the aforesaid electronic transport properties.

Electron transport in InAs/AlGaSb ballistic rectifiers

International Nuclear Information System (INIS)

Maemoto, Toshihiko; Koyama, Masatoshi; Furukawa, Masashi; Takahashi, Hiroshi; Sasa, Shigehiko; Inoue, Masataka

2006-01-01

Nonlinear transport properties of a ballistic rectifier fabricated from InAs/AlGaSb heterostructures are reported. The operation of the ballistic rectifier is based on the guidance of carriers by a square anti-dot structure. The structure was defined by electron beam lithography and wet chemical etching. The DC characteristics and magneto-transport properties of the ballistic rectifier have been measured at 77 K and 4.2 K. Rectification effects relying on the ballistic transport were observed. From the four-terminal resistance measured at low magnetic fields, we also observed magneto-resistance fluctuations corresponding to the electron trajectories and symmetry-breaking electron scattering, which are influenced by the magnetic field strength

5D simulation study of suprathermal electron transport in non-axisymmetric plasmas

International Nuclear Information System (INIS)

Murakami, S.; Idei, H.; Kubo, S.; Nakajima, N.; Okamoto, M.; Gasparino, U.; Maassberg, H.; Rome, M.; Marushchenko, N.

2001-01-01

ECRH-driven transport of is studied in using a new Monte Carlo simulation technique in 5D phase space. Two different phases of the ECRH-driven transport of suprathermal electrons can be seen; one is a rapid convective phase due to the direct radial motion of trapped electrons and the other is a slower phase due to the collisional transport. The important role of the radial transport of suprathermal electrons in the broadening of the ECRH deposition profile is clarified in W7-AS. The ECRH driven flux is also evaluated and put in relation with the ''electron root'' feature recently observed in W7-AS. It is found that, at low collisionalities, the ECRH driven flux due to the suprathermal electrons can play a dominant role in the condition of ambipolarity and, thus, the observed ''electron root'' feature in W7-AS is thought to be driven by the radial (convective) flux of ECRH generated suprathermal electrons. The possible scenario of this ''ECRH-driven electron root'' is considered in the LHD plasma. (author)

Molecular electronics: insight from first-principles transport simulations.

Science.gov (United States)

Paulsson, Magnus; Frederiksen, Thomas; Brandbyge, Mads

2010-01-01

Conduction properties of nanoscale contacts can be studied using first-principles simulations. Such calculations give insight into details behind the conductance that is not readily available in experiments. For example, we may learn how the bonding conditions of a molecule to the electrodes affect the electronic transport. Here we describe key computational ingredients and discuss these in relation to simulations for scanning tunneling microscopy (STM) experiments with C60 molecules where the experimental geometry is well characterized. We then show how molecular dynamics simulations may be combined with transport calculations to study more irregular situations, such as the evolution of a nanoscale contact with the mechanically controllable break-junction technique. Finally we discuss calculations of inelastic electron tunnelling spectroscopy as a characterization technique that reveals information about the atomic arrangement and transport channels.

The safety of radioactive materials transport; La surete des transports de matieres radioactives

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-07-01

The rule of the radioactive materials transport contains two different objectives: the safety, or physical protection, consists in preventing the losses, the disappearances, the thefts and the diversions of the nuclear materials (useful materials for weapons); the high civil servant of defence near the Minister of Economy, Finance and Industry is the responsible authority; the safety consists in mastering the risks of irradiation, contamination and criticality presented by the radioactive and fissile materials transport, in order that man and environment do not undergo the nuisances. The control of the safety is within the competence of the Asn. (N.C.)

STM and transport measurements of highly charged ion modified materials

International Nuclear Information System (INIS)

Pomeroy, J.M.; Grube, H.; Perrella, A.C.; Gillaspy, J.D.

2007-01-01

Careful measurements of highly charged ions (HCIs) colliding with gases and surfaces have provided glimpses of intense electronic interactions, but a comprehensive model for the interaction mechanisms, time scales, and resultant nano-features that bridges materials systems is yet to be realized. At the National Institute of Standards and Technology (NIST) electron beam ion trap (EBIT) facility, new apparatus is now connected to the HCI beamline to allow preparation of clean, atomically flat surfaces of single crystals, e.g. gold, tungsten and silicon, and deposition and patterning of thin films, e.g. high resistivity oxides, ferromagnetic metals, normal metals and superconductors. Experiments reported here focus on the electronic and morphological structure of HCI induced nano-features. Current activities are focused on using in situ scanning tunneling microscope (STM) on Au(1 1 1) and (separately) ex situ transport measurements to study electronic properties within HCI modified magnetic multilayer systems. Specifically, we are fabricating magnetic multilayers similar to magnetic tunnel junctions (MTJs) (important in advanced magnetic field sensors and superconducting Josephson junction devices) and using HCIs to adjust critical electronic properties. The electrical response of the tunnel junction to HCIs provides a novel approach to performing HCI-induced nanostructure ensemble measurements

INES scale: French application to radioactive material transport

International Nuclear Information System (INIS)

Sowinski, S.; Strawa, S.; Aguilar, J.

2004-01-01

After getting the control of radioactive material transport in June 1997, the French safety Authority (ASN) decided to apply the INES scale to transport events. DGSNR (Directorate General for Nuclear Safety and Radioprotection) requests that radioactive material package consignors declare any event occurring during transportation, and has introduced the use of the INES scale adapted to classify transport events in order to inform the public and to have feedback. This paper deals with DGSNR's feedback during the past seven years concerning the french application of the INES scale. Significant events that occurred during transportation are presented. The French experience was used by IAEA to develop a draft guide in 2002 and IAEA asked countries to use a new draft for a trial period in July 2004

Electron cyclotron waves, transport and instabilities in hot plasmas

International Nuclear Information System (INIS)

Westerhof, E.

1987-01-01

A number of topics relevant to the magnetic confinement approach to the thermonuclear fusion is addressed. The absorption and emission of electron cyclotron waves in a thermal plasma with a small population of supra-thermal, streaming electrons is examined and the properties of electron cyclotron waves in a plasma with a pure loss-cone distribution are studied. A report is given on the 1-D transport code simulations that were performed to assist the interpretation of the electron cyclotron heating experiments on the TFR tokamak. Transport code simulations of sawteeth discharges in the T-10 tokamak are discussed in order to compare the predictions of different models for the sawtooth oscillations with the experimental findings. 149 refs.; 69 figs.; 7 tabs

Tailoring atomic structure to control the electronic transport in zigzag graphene nanoribbon

International Nuclear Information System (INIS)

Zeng, Hui; Zhao, Jun; Wei, Jianwei; Zeng, Xianliang; Xu, Yang

2012-01-01

We have performed ab initio density functional theory calculation to study the electronic transport properties of the tailored zigzag-edged graphene nanoribbon (ZGNR) with particular electronic transport channels. Our results demonstrated that tailoring the atomic structure had significantly influenced the electronic transport of the defective nanostructures, and could lead to the metal-semiconducting transition when sufficient atoms are tailored. The asymmetric I–V characteristics as a result of symmetry breaking have been exhibited, which indicates the route to utilize GNR as a basic component for novel nanoelectronics. -- Highlights: ► M–S transition induced by tailoring nanostructure. ► Asymmetric I–V curve due to symmetry breaking. ► Controllable electron transport by designing nanofiguration.

Tailoring atomic structure to control the electronic transport in zigzag graphene nanoribbon

Energy Technology Data Exchange (ETDEWEB)

Zeng, Hui [College of Physical Science and Technology, Yangtze University, Jingzhou, Hubei 434023 (China); Zhao, Jun, E-mail: zhaojun@yangtzeu.edu.cn [College of Physical Science and Technology, Yangtze University, Jingzhou, Hubei 434023 (China); Wei, Jianwei [College of Optoelectronic Information, Chongqing University of Technology, Chongqing 400054 (China); Zeng, Xianliang [College of Physical Science and Technology, Yangtze University, Jingzhou, Hubei 434023 (China); Xu, Yang [Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

2012-10-01

We have performed ab initio density functional theory calculation to study the electronic transport properties of the tailored zigzag-edged graphene nanoribbon (ZGNR) with particular electronic transport channels. Our results demonstrated that tailoring the atomic structure had significantly influenced the electronic transport of the defective nanostructures, and could lead to the metal-semiconducting transition when sufficient atoms are tailored. The asymmetric I–V characteristics as a result of symmetry breaking have been exhibited, which indicates the route to utilize GNR as a basic component for novel nanoelectronics. -- Highlights: ► M–S transition induced by tailoring nanostructure. ► Asymmetric I–V curve due to symmetry breaking. ► Controllable electron transport by designing nanofiguration.

Sea transport of radioactive materials in Egypt (invited paper)

International Nuclear Information System (INIS)

El-Shinawy, R.M.K.; Gomaa, M.A.

1998-01-01

In Egypt the national regulations for safe transport of radioactive materials (RAM) are based on the International Atomic Energy Agency (IAEA) regulations. In addition, regulations for the safe transport of these materials through the Suez Canal (SC) were laid down by the Egyptian Atomic Energy Authority (EAEA) and the Suez Canal Authority (SCA). They are continuously updated to meet the increased knowledge and the experience gained. The technical and protective measures taken during transport of RAM through SC are mentioned. Assessment of the impact of transporting radioactive materials through the Suez Canal using the INTERTRAN computer code was carried out in cooperation with IAEA. The transported activities and empty containers, the number of vessels carrying RAM through the Canal from 1963 to 1996 and their nationalities are also discussed. The protective measures are mentioned. (author)

Legislative developments in radioactive materials transportation, September 1993--June 1994

International Nuclear Information System (INIS)

Worthley, J.A.; Reed, J.B.; Cummins, J.

1994-07-01

This is the eighth report prepared by the National Conference of State Legislatures (NCSL) on developments in radioactive materials transportation. It updates information contained in the September 1993 report on Legislative Developments in Radioactive Materials Transportation and describes activities for the period September 1, 1993--June 30, 1994. NCSL currently is updating an on-line data base that contains abstracts of federal, state and local laws and regulations relating to the transportation of radioactive materials. The data base will be operated by NCSL under a cooperative agreement with the Department of Energy's (DOE) Office of Civilian Radioactive Waste Management. Availability of on-line capability is anticipated by the end of August 1994. Users approved by DOE and NCSL will have access to the data base. This report contains the current status of legislation introduced in the 1993 and 1994 state legislative sessions, not previously reviewed in past reports. Bills that address nuclear materials transportation and the broader area of hazardous materials transportation are grouped by state according to their status--enacted, pending or failed. In addition, bills that deal with emergency preparedness are described. (General nuclear waste legislation with no transportation element is no longer tracked.) Also included are Federal Register notices and changes in federal regulations pertinent to radioactive waste and hazardous materials transportation

Hydrogenated TiO2 Thin Film for Accelerating Electron Transport in Highly Efficient Planar Perovskite Solar Cells.

Science.gov (United States)

Yao, Xin; Liang, Junhui; Li, Yuelong; Luo, Jingshan; Shi, Biao; Wei, Changchun; Zhang, Dekun; Li, Baozhang; Ding, Yi; Zhao, Ying; Zhang, Xiaodan

2017-10-01

Intensive studies on low-temperature deposited electron transport materials have been performed to improve the efficiency of n-i-p type planar perovskite solar cells to extend their application on plastic and multijunction device architectures. Here, a TiO 2 film with enhanced conductivity and tailored band edge is prepared by magnetron sputtering at room temperature by hydrogen doping (HTO), which accelerates the electron extraction from perovskite photoabsorber and reduces charge transfer resistance, resulting in an improved short circuit current density and fill factor. The HTO film with upward shifted Fermi level guarantees a smaller loss on V OC and facilitates the growth of high-quality absorber with much larger grains and more uniform size, leading to devices with negligible hysteresis. In comparison with the pristine TiO 2 prepared without hydrogen doping, the HTO-based device exhibits a substantial performance enhancement leading to an efficiency of 19.30% and more stabilized photovoltaic performance maintaining 93% of its initial value after 300 min continuous illumination in the glove box. These properties permit the room-temperature magnetron sputtered HTO film as a promising electron transport material for flexible and tandem perovskite solar cell in the future.

Transport of secondary electrons and reactive species in ion tracks

Science.gov (United States)

Surdutovich, Eugene; Solov'yov, Andrey V.

2015-08-01

The transport of reactive species brought about by ions traversing tissue-like medium is analysed analytically. Secondary electrons ejected by ions are capable of ionizing other molecules; the transport of these generations of electrons is studied using the random walk approximation until these electrons remain ballistic. Then, the distribution of solvated electrons produced as a result of interaction of low-energy electrons with water molecules is obtained. The radial distribution of energy loss by ions and secondary electrons to the medium yields the initial radial dose distribution, which can be used as initial conditions for the predicted shock waves. The formation, diffusion, and chemical evolution of hydroxyl radicals in liquid water are studied as well. COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy.

Does menaquinone participate in brain astrocyte electron transport?

Science.gov (United States)

Lovern, Douglas; Marbois, Beth

2013-10-01

Quinone compounds act as membrane resident carriers of electrons between components of the electron transport chain in the periplasmic space of prokaryotes and in the mitochondria of eukaryotes. Vitamin K is a quinone compound in the human body in a storage form as menaquinone (MK); distribution includes regulated amounts in mitochondrial membranes. The human brain, which has low amounts of typical vitamin K dependent function (e.g., gamma carboxylase) has relatively high levels of MK, and different regions of brain have different amounts. Coenzyme Q (Q), is a quinone synthesized de novo, and the levels of synthesis decline with age. The levels of MK are dependent on dietary intake and generally increase with age. MK has a characterized role in the transfer of electrons to fumarate in prokaryotes. A newly recognized fumarate cycle has been identified in brain astrocytes. The MK precursor menadione has been shown to donate electrons directly to mitochondrial complex III. Vitamin K compounds function in the electron transport chain of human brain astrocytes. Copyright © 2013 Elsevier Ltd. All rights reserved.

Environmental risk analysis of hazardous material rail transportation

Energy Technology Data Exchange (ETDEWEB)

Saat, Mohd Rapik, E-mail: mohdsaat@illinois.edu [Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 1243 Newmark Civil Engineering Laboratory, 205 North Mathews Avenue, Urbana, IL 61801 (United States); Werth, Charles J.; Schaeffer, David [Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 1243 Newmark Civil Engineering Laboratory, 205 North Mathews Avenue, Urbana, IL 61801 (United States); Yoon, Hongkyu [Sandia National Laboratories, Albuquerque, NM 87123 (United States); Barkan, Christopher P.L. [Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 1243 Newmark Civil Engineering Laboratory, 205 North Mathews Avenue, Urbana, IL 61801 (United States)

2014-01-15

Highlights: • Comprehensive, nationwide risk assessment of hazardous material rail transportation. • Application of a novel environmental (i.e. soil and groundwater) consequence model. • Cleanup cost and total shipment distance are the most significant risk factors. • Annual risk varies from $20,000 to $560,000 for different products. • Provides information on the risk cost associated with specific product shipments. -- Abstract: An important aspect of railroad environmental risk management involves tank car transportation of hazardous materials. This paper describes a quantitative, environmental risk analysis of rail transportation of a group of light, non-aqueous-phase liquid (LNAPL) chemicals commonly transported by rail in North America. The Hazardous Materials Transportation Environmental Consequence Model (HMTECM) was used in conjunction with a geographic information system (GIS) analysis of environmental characteristics to develop probabilistic estimates of exposure to different spill scenarios along the North American rail network. The risk analysis incorporated the estimated clean-up cost developed using the HMTECM, route-specific probability distributions of soil type and depth to groundwater, annual traffic volume, railcar accident rate, and tank car safety features, to estimate the nationwide annual risk of transporting each product. The annual risk per car-mile (car-km) and per ton-mile (ton-km) was also calculated to enable comparison between chemicals and to provide information on the risk cost associated with shipments of these products. The analysis and the methodology provide a quantitative approach that will enable more effective management of the environmental risk of transporting hazardous materials.

Environmental risk analysis of hazardous material rail transportation

International Nuclear Information System (INIS)

Saat, Mohd Rapik; Werth, Charles J.; Schaeffer, David; Yoon, Hongkyu; Barkan, Christopher P.L.

2014-01-01

Highlights: • Comprehensive, nationwide risk assessment of hazardous material rail transportation. • Application of a novel environmental (i.e. soil and groundwater) consequence model. • Cleanup cost and total shipment distance are the most significant risk factors. • Annual risk varies from $20,000 to $560,000 for different products. • Provides information on the risk cost associated with specific product shipments. -- Abstract: An important aspect of railroad environmental risk management involves tank car transportation of hazardous materials. This paper describes a quantitative, environmental risk analysis of rail transportation of a group of light, non-aqueous-phase liquid (LNAPL) chemicals commonly transported by rail in North America. The Hazardous Materials Transportation Environmental Consequence Model (HMTECM) was used in conjunction with a geographic information system (GIS) analysis of environmental characteristics to develop probabilistic estimates of exposure to different spill scenarios along the North American rail network. The risk analysis incorporated the estimated clean-up cost developed using the HMTECM, route-specific probability distributions of soil type and depth to groundwater, annual traffic volume, railcar accident rate, and tank car safety features, to estimate the nationwide annual risk of transporting each product. The annual risk per car-mile (car-km) and per ton-mile (ton-km) was also calculated to enable comparison between chemicals and to provide information on the risk cost associated with shipments of these products. The analysis and the methodology provide a quantitative approach that will enable more effective management of the environmental risk of transporting hazardous materials

Perspective on transporting nuclear materials

International Nuclear Information System (INIS)

Wymer, R.G.

1975-01-01

An evaluation is made of the material flow to be expected up to the year 2000 to and from the various steps in the nuclear cycle. These include the reactors, reprocessing plants, enrichment plants, U mills, U conversion plants, and fuel fabrication plants. A somewhat more-detailed discussion is given of the safety engineering that goes into the design of containers and packages and the selection of the mode of transportation. The relationship of shipping to siting and transportation accidents is considered briefly

Radioactive materials transporting container and vehicles

International Nuclear Information System (INIS)

Reese, S.L.

1980-01-01

A container and vehicle therefor for transporting radioactive materials is provided. The container utilizes a removable system of heat conducting fins made of a light weight highly heat conductive metal, such as aluminum or aluminum alloys. This permits a substantial reduction in the weight of the container during transport, increases the heat dissipation capability of the container and substantially reduces the scrubbing operation after loading and before unloading the radioactive material from the container. The vehicle utilizes only a pair of horizontal side beams interconnecting a pair of yoke members to support the container and provide the necessary strength and safety with a minimum of weight

Regulations for the safe transport of radioactive materials. 1973 rev. ed

International Nuclear Information System (INIS)

1973-01-01

The purpose of these Regulations is to establish standards of safety which provide an acceptable level of control of the radiation hazards to persons, property and the environment that are associated with the transport of radioactive material. These Regulations shall apply to the transport by land, water or air, including transport on own account, of radioactive material other than that which is an integral part of the means of transport. Transport shall be deemed to include any operation incidental to the whole course of carriage, such as loading, unloading and storage in transit. The term includes both normal transport and that under accident conditions. These Regulations do not apply within establishments where the radioactive material is produced, used or stored, other than in the course of transport, and in respect of which other appropriate safety regulations are in force. In the transport of radioactive materials, any other hazardous characteristics of these materials such as explosiveness, inflammability, pyrophoricity, chemical toxicity, and corrosiveness must be taken into account in such a manner as to be in compliance with the relevant transport regulations for dangerous goods of each of the countries through or into which the materials will be transported, as well as in compliance with these Regulations.

Amorphous electron-accepting materials for organic optoelectronics

NARCIS (Netherlands)

Ganesan, P.

2007-01-01

The importance of organic materials for use in electronic devices such as OLEDs, OFETs and photovoltaic cells has increased significantly over the past decade. Organic materials have been attractive candidates for such electronic devices because of their compatibility with high-throughput,

Conjugated material self-assembly : towards supramolecular electronics

NARCIS (Netherlands)

Leclère, P.E.L.G.; Surin, M.; Cavallini, M.; Jonkheijm, P.; Henze, O.; Schenning, A.P.H.J.; Biscarini, F.; Grimsdale, A.C.; Feast, W.J.; Meijer, E.W.; Müllen, K.; Brédas, J.L.; Lazzaroni, R.

2004-01-01

Properties of organic electronic materials in solid-state are determined as individual molecules and molecular assembly. It is essential to optimize conjugated materials to control performance of molecular assembly that constitute electronic devices such as light-emitting diodes and solar cells, and

Environmental effects associated with the transportation of radioactive material

International Nuclear Information System (INIS)

McClure, J.D.; Pope, R.B.; Yoshimura, H.R.

1979-01-01

The primary aim of this paper has been to describe some of the background information concerning nuclear materials transportation systems, accident statistics, accident severities, and test information - all of which when combined yield an environmental statement of the risks associated with the transportation of radioactive materials. The results of the ultimate risk analysis are expressed in terms of numbers of fatalities and, in that sense at least, tend to be an absolute measure of risk. When these risks are compared with other accepted societal risks, the relative risks associated with radioactive material transportation can be established. This information can be used to make decisions at the governmental level and to inform an interested public about these risks. It can be concluded that the risks associated with the transportation of radioactive material are low relative to the other risks that society has already accepted

Distribution of tunnelling times for quantum electron transport

International Nuclear Information System (INIS)

Rudge, Samuel L.; Kosov, Daniel S.

2016-01-01

In electron transport, the tunnelling time is the time taken for an electron to tunnel out of a system after it has tunnelled in. We define the tunnelling time distribution for quantum processes in a dissipative environment and develop a practical approach for calculating it, where the environment is described by the general Markovian master equation. We illustrate the theory by using the rate equation to compute the tunnelling time distribution for electron transport through a molecular junction. The tunnelling time distribution is exponential, which indicates that Markovian quantum tunnelling is a Poissonian statistical process. The tunnelling time distribution is used not only to study the quantum statistics of tunnelling along the average electric current but also to analyse extreme quantum events where an electron jumps against the applied voltage bias. The average tunnelling time shows distinctly different temperature dependence for p- and n-type molecular junctions and therefore provides a sensitive tool to probe the alignment of molecular orbitals relative to the electrode Fermi energy.

Radial transport in the Elmo Bumpy Torus in collisionless electron regimes

International Nuclear Information System (INIS)

Jaeger, E.F.; Hedrick, C.L.; Spong, D.A.

1979-01-01

One important area of disagreement between radial transport theory and the ELMO Bumpy Torus (EBT) experiment has been the degree of collisionality of the toroidal plasma electrons. Experiment shows relatively warm electrons (kTsub(e) approximately 300-600eV) and collisionless scaling, i.e. energy confinement increasing with temperature. But results of early one-dimensional (1-D), neoclassical transport models with radially inward pointing electric fields are limited to relatively cool electrons (kTsub(e) approximately 100-200eV) and collisional scaling. In this paper these early results are extended to include lowest-order effects of ion diffusion in regions where poloidal drift frequencies are small. The effects of direct, or non-diffusive, losses in such regions are neglected along with the effects of finite radial electric fields on electron transport coefficients and of self-consistent poloidal electric fields on ion transport coefficients. Results show that solutions in the collisionless electron regime do exist. Furthermore, when the effects of finite electron ring beta on magnetic fields near the plasma edge are included, these solutions occur at power levels consistent with experiment. (author)

Polymer electronic devices and materials.

Energy Technology Data Exchange (ETDEWEB)

Schubert, William Kent; Baca, Paul Martin; Dirk, Shawn M.; Anderson, G. Ronald; Wheeler, David Roger

2006-01-01

Polymer electronic devices and materials have vast potential for future microsystems and could have many advantages over conventional inorganic semiconductor based systems, including ease of manufacturing, cost, weight, flexibility, and the ability to integrate a wide variety of functions on a single platform. Starting materials and substrates are relatively inexpensive and amenable to mass manufacturing methods. This project attempted to plant the seeds for a new core competency in polymer electronics at Sandia National Laboratories. As part of this effort a wide variety of polymer components and devices, ranging from simple resistors to infrared sensitive devices, were fabricated and characterized. Ink jet printing capabilities were established. In addition to promising results on prototype devices the project highlighted the directions where future investments must be made to establish a viable polymer electronics competency.

Accurate transport simulation of electron tracks in the energy range 1 keV-4 MeV