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Sample records for unique transport properties

  1. Additively manufactured metallic porous biomaterials based on minimal surfaces: A unique combination of topological, mechanical, and mass transport properties.

    Science.gov (United States)

    Bobbert, F S L; Lietaert, K; Eftekhari, A A; Pouran, B; Ahmadi, S M; Weinans, H; Zadpoor, A A

    2017-04-15

    Porous biomaterials that simultaneously mimic the topological, mechanical, and mass transport properties of bone are in great demand but are rarely found in the literature. In this study, we rationally designed and additively manufactured (AM) porous metallic biomaterials based on four different types of triply periodic minimal surfaces (TPMS) that mimic the properties of bone to an unprecedented level of multi-physics detail. Sixteen different types of porous biomaterials were rationally designed and fabricated using selective laser melting (SLM) from a titanium alloy (Ti-6Al-4V). The topology, quasi-static mechanical properties, fatigue resistance, and permeability of the developed biomaterials were then characterized. In terms of topology, the biomaterials resembled the morphological properties of trabecular bone including mean surface curvatures close to zero. The biomaterials showed a favorable but rare combination of relatively low elastic properties in the range of those observed for trabecular bone and high yield strengths exceeding those reported for cortical bone. This combination allows for simultaneously avoiding stress shielding, while providing ample mechanical support for bone tissue regeneration and osseointegration. Furthermore, as opposed to other AM porous biomaterials developed to date for which the fatigue endurance limit has been found to be ≈20% of their yield (or plateau) stress, some of the biomaterials developed in the current study show extremely high fatigue resistance with endurance limits up to 60% of their yield stress. It was also found that the permeability values measured for the developed biomaterials were in the range of values reported for trabecular bone. In summary, the developed porous metallic biomaterials based on TPMS mimic the topological, mechanical, and physical properties of trabecular bone to a great degree. These properties make them potential candidates to be applied as parts of orthopedic implants and/or as bone

  2. Uniqueness property for quasiharmonic functions

    Directory of Open Access Journals (Sweden)

    Sevdiyor A. Imomkulov

    2014-10-01

    Full Text Available In this paper we consider a class of continuous functions, called quasiaharmonic functions, admitting best approximations by harmonic polynomials. In this class we prove a uniqueness theorem by analogy with the analytic functions.

  3. Some unique superconductive Properties of Cuprates

    Science.gov (United States)

    Müller, K. A.

    2013-04-01

    Copper oxides are the only materials that show transition temperatures, Tc, above the boiling point of liquid nitrogen, with a maximum Tmc of 162 K under pressure. Their structure is layered, with one to several CuO2 planes, and upon hole doping, their transition temperature follows a dome-shaped curve with a maximum at Tmc. In the underdoped regime, i.e., below Tmc, a pseudogap T* is found, with T* always being larger than Tc, a property unique to the copper oxides [1]. In the superconducting state, Cooper pairs (two holes with antiparallel spins) are formed that exhibit coherence lengths on the order of a lattice distance in the CuO2 plane and one order of magnitude less perpendicular to it. Their macroscopic wave function is parallel to the CuO2 plane near 100% d at their surface, but only 75% d and 25 % s in the bulk, and near 100% s perpendicular to the plane in YBCO. There are two gaps with the same Tc [2]. As function of doping, the oxygen isotope effect is novel and can be quantitatively accounted for by a two-band vibronic theory [3] near Tmc, and underdoped below it till Tc = 0 with by a formula valid for (bi)polarons [4]. These cuprates are intrinsically heterogeneous in a dynamic way. In terms of quasiparticles, Jahn-Teller bipolarons are present at low doping, and aggregate upon cooling [1], so that probably ramified clusters and/or stripes are formed, leading over to a more Fermi-liquid-type behavior at large carrier concentrations above Tmc.

  4. Unique properties of Plasmodium falciparum porphobilinogen deaminase.

    Science.gov (United States)

    Nagaraj, Viswanathan Arun; Arumugam, Rajavel; Gopalakrishnan, Bulusu; Jyothsna, Yeleswarapu Sri; Rangarajan, Pundi N; Padmanaban, Govindarajan

    2008-01-04

    The hybrid pathway for heme biosynthesis in the malarial parasite proposes the involvement of parasite genome-coded enzymes of the pathway localized in different compartments such as apicoplast, mitochondria, and cytosol. However, knowledge on the functionality and localization of many of these enzymes is not available. In this study, we demonstrate that porphobilinogen deaminase encoded by the Plasmodium falciparum genome (PfPBGD) has several unique biochemical properties. Studies carried out with PfPBGD partially purified from parasite membrane fraction, as well as recombinant PfPBGD lacking N-terminal 64 amino acids expressed and purified from Escherichia coli cells (DeltaPfPBGD), indicate that both the proteins are catalytically active. Surprisingly, PfPBGD catalyzes the conversion of porphobilinogen to uroporphyrinogen III (UROGEN III), indicating that it also possesses uroporphyrinogen III synthase (UROS) activity, catalyzing the next step. This obviates the necessity to have a separate gene for UROS that has not been so far annotated in the parasite genome. Interestingly, DeltaPfP-BGD gives rise to UROGEN III even after heat treatment, although UROS from other sources is known to be heat-sensitive. Based on the analysis of active site residues, a DeltaPfPBGDL116K mutant enzyme was created and the specific activity of this recombinant mutant enzyme is 5-fold higher than DeltaPfPBGD. More interestingly, DeltaPfPBGDL116K catalyzes the formation of uroporphyrinogen I (UROGEN I) in addition to UROGEN III, indicating that with increased PBGD activity the UROS activity of PBGD may perhaps become rate-limiting, thus leading to non-enzymatic cyclization of preuroporphyrinogen to UROGEN I. PfPBGD is localized to the apicoplast and is catalytically very inefficient compared with the host red cell enzyme.

  5. Transport Properties for Combustion Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Brown, N.J.; Bastein, L.; Price, P.N.

    2010-02-19

    This review examines current approximations and approaches that underlie the evaluation of transport properties for combustion modeling applications. Discussed in the review are: the intermolecular potential and its descriptive molecular parameters; various approaches to evaluating collision integrals; supporting data required for the evaluation of transport properties; commonly used computer programs for predicting transport properties; the quality of experimental measurements and their importance for validating or rejecting approximations to property estimation; the interpretation of corresponding states; combination rules that yield pair molecular potential parameters for unlike species from like species parameters; and mixture approximations. The insensitivity of transport properties to intermolecular forces is noted, especially the non-uniqueness of the supporting potential parameters. Viscosity experiments of pure substances and binary mixtures measured post 1970 are used to evaluate a number of approximations; the intermediate temperature range 1 < T* < 10, where T* is kT/{var_epsilon}, is emphasized since this is where rich data sets are available. When suitable potential parameters are used, errors in transport property predictions for pure substances and binary mixtures are less than 5 %, when they are calculated using the approaches of Kee et al.; Mason, Kestin, and Uribe; Paul and Warnatz; or Ern and Giovangigli. Recommendations stemming from the review include (1) revisiting the supporting data required by the various computational approaches, and updating the data sets with accurate potential parameters, dipole moments, and polarizabilities; (2) characterizing the range of parameter space over which the fit to experimental data is good, rather than the current practice of reporting only the parameter set that best fits the data; (3) looking for improved combining rules, since existing rules were found to under-predict the viscosity in most cases; (4

  6. Unique properties of humic substances from sapropel

    Science.gov (United States)

    Rumyantsev, V. A.; Mityukov, A. S.; Kryukov, L. N.; Yaroshevich, G. S.

    2017-04-01

    Sapropel from inland Russian water reservoirs is becoming a popular raw material for medicinal purposes, production of sorbents, organomineral fertilizers, and food supplements. A comparative study of the granulometric and biological properties of humic substances obtained from sapropel in a typical way and using ultrasonic treatment of the relevant reaction masses was performed at the Institute of Limnology of the Russian Academy of Sciences. It is shown that the humic substances of sapropel with an increased content of nanoparticles used as veterinary preparations lead to a significant economic effect without using imported preparations.

  7. Is thermosensing property of RNA thermometers unique?

    Directory of Open Access Journals (Sweden)

    Premal Shah

    Full Text Available A large number of studies have been dedicated to identify the structural and sequence based features of RNA thermometers, mRNAs that regulate their translation initiation rate with temperature. It has been shown that the melting of the ribosome-binding site (RBS plays a prominent role in this thermosensing process. However, little is known as to how widespread this melting phenomenon is as earlier studies on the subject have worked with a small sample of known RNA thermometers. We have developed a novel method of studying the melting of RNAs with temperature by computationally sampling the distribution of the RNA structures at various temperatures using the RNA folding software Vienna. In this study, we compared the thermosensing property of 100 randomly selected mRNAs and three well known thermometers--rpoH, ibpA and agsA sequences from E. coli. We also compared the rpoH sequences from 81 mesophilic proteobacteria. Although both rpoH and ibpA show a higher rate of melting at their RBS compared with the mean of non-thermometers, contrary to our expectations these higher rates are not significant. Surprisingly, we also do not find any significant differences between rpoH thermometers from other gamma-proteobacteria and E. coli non-thermometers.

  8. Unique microstructure and excellent mechanical properties of ADI

    Directory of Open Access Journals (Sweden)

    Jincheng Liu

    2006-11-01

    Full Text Available Amongst the cast iron family, ADI has a unique microstructure and an excellent, optimised combination of mechanical properties. The main microstructure of ADI is ausferrite, which is a mixture ofextremely fine acicular ferrite and stable, high carbon austenite. There are two types of austenite in ADI:(1 the coarser and more equiaxed blocks of austenite between non-parallel acicular structures, which exist mainly in the last solidified area, and (2 the thin films of ustenite between the individual ferriteplatelets in the acicular structure. It is this unique microstructure, which gives ADI its excellent static and dynamic properties, and good low temperature impact toughness. The effect of microstructure on the mechanical properties is explained in more detail by examining the microstructure at the atomic scale. Considering the nanometer grain sizes, the unique microstructure, the excellent mechanical properties,good castability, (which enables near net shape components to be produced economically and in large volumes, and the fact that it can be 100% recycled, it is not overemphasized to call ADI a high-tech,nanometer and “green” material. ADI still has the potential to be further improved and its production and the number of applications for ADI will continue to grow, driven by the resultant cost savings over alternative materials.

  9. Unique microstructure and excellent mechanical properties of ADI

    Institute of Scientific and Technical Information of China (English)

    Jincheng Liu

    2006-01-01

    Amongst the cast iron family, ADI has a unique microstructure and an excellent, optimised combination of mechanical properties. The main microstructure of ADI is ausferrite, which is a mixture of extremely fine acicular ferrite and stable, high carbon austenite. There are two types of austenite in ADI:(1) the coarser and more equiaxed blocks of austenite between non-parallel acicular structures, which exist mainly in the last solidified area, and (2) the thin films of austenite between the individual ferrite platelets in the acicular structure. It is this unique microstructure, which gives ADI its excellent static and dynamic properties, and good low temperature impact toughness. The effect of microstructure on the mechanical properties is explained in more detail by examining the microstructure at the atomic scale.Considering the nanometer grain sizes the unique microstructure, the excellent mechanical properties,good castability, (which enables near net shape components to be produced economically and in large volumes), and the fact that it can be 100% recycled, it is not overemphasized to call ADI a high-tech,nanometer and "green" material. ADI still has the potential to be further improved and its production and the number of applications for ADI will continue to grow, driven by the resultant cost savings over altemative materials.

  10. Unique Properties of Heat Generation in Nanoscale Systems

    Institute of Scientific and Technical Information of China (English)

    周利玲

    2011-01-01

    We study tie unique properties of current-induced heat generation Q in nanostructures and its absence in macroscopic bulks. A lead-quantum dot-lead system is taken into consideration and it is found that its unique properties stem from energy quantization of the system and arise only under conditions of low temperature and weak dot-lead coupling. The relation of Q o I (I is the system current) fails in nanosystems, while the Q peaks align with peaks of phonon-assisted current under small bias. As a result, one can expect a large current accompanied by relatively small Q when the elastic current peak does not coincide with the phonon-assisted one, the ideal working condition for a nanostructure.%We study the unique properties of current-induced heat generation Q in nanostructures and its absence in macroscopic bulks.A lead-quantum dot-lead system is taken into consideration and it is found that its unique properties stem from energy quantization of the system and arise only under conditions of low temperature and weak dotlead coupling.The relation of Q o I(I is the system current)fails in nanosystems,while the Q peaks align with peaks of phonon-assisted current under small bias.As a result,one can expect a large current accompanied by relatively small Q when the elastic current peak does not coincide with the phonon-assisted one,the ideal working condition for a nanostructure.

  11. Control of local ion transport to create unique functional nanodevices based on ionic conductors

    Directory of Open Access Journals (Sweden)

    Kazuya Terabe, Tsuyoshi Hasegawa, Changhao Liang and Masakazu Aono

    2007-01-01

    Full Text Available The development of nanometer-scale devices operating under a new principle that could overcome the limitations of current semiconductor devices has attracted interest in recent years. We propose that nanoionic devices that operate by controlling the local transport of ions are promising in this regard. It is possible to control the local transport of ions using the solid electrochemical properties of ionic and electronic mixed conductors. As an example of this concept, here, we report a method of controlling the transport of silver ions of the mixed-conductor silver sulfide (Ag2S crystal and basic research on nanoionic devices based on this mixed conductor. These devices show unique functions such as atom deposition, resistance switching, and quantum point contact switching. The switches operate through the formation and dissolution of an atomic bridge between the electrodes, and the behavior is realized by control of the local solid-state electrochemical reaction. Potential nanoionic devices utilizing the unique functions and characters that do not exist in conventional semiconductor devices are discussed.

  12. Lipases at interfaces: unique interfacial properties as globular proteins.

    Science.gov (United States)

    Reis, P; Miller, R; Krägel, J; Leser, M; Fainerman, V B; Watzke, H; Holmberg, K

    2008-06-01

    The adsorption behavior of two globular proteins, lipase from Rhizomucor miehei and beta-lactoglobulin, at inert oil/water and air/water interfaces was studied by the pendant drop technique. The kinetics and adsorption isotherms were interpreted for both proteins in different environments. It was found that the adopted mathematical models well describe the adsorption behavior of the proteins at the studied interfaces. One of the main findings is that unique interfacial properties were observed for lipase as compared to the reference beta-lactoglobulin. A folded drop with a "skinlike" film was formed for the two proteins after aging followed by compression. This behavior is normally associated with protein unfolding and covalent cross-linking at the interface. Despite this, the lipase activity was not suppressed. By highlighting the unique interfacial properties of lipases, we believe that the presented work contributes to a better understanding of lipase interfacial activation and the mechanisms regulating lipolysis. The results indicate that the understanding of the physical properties of lipases can lead to novel approaches to regulate their activity.

  13. Digging for Treasure - Unique Fate and Transport Study

    Energy Technology Data Exchange (ETDEWEB)

    Larry Zirker; M. K. Adler-Flitton; G. A. Beitel

    2003-02-01

    In 1970, scientists at the National Bureau of Standards (NBS), now called the National Institute of Standards and Testing (NIST), implemented the most ambitious and comprehensive long-term corrosion behavior test for stainless steels in soil environments. This study had historic significance since the NBS 1957 landmark corrosion textbook compiled by Romanoff did not include stainless steels, and this 1970 research set forth to complete the missing body of knowledge. To conduct the test, NIST scientists buried 6,324 coupons from stainless steel types, specialty alloys, composite configurations, multiple material forms, and treatment conditions at six distinctive soil-type sites throughout the country. Between 1971 and 1980, four sets of coupons were removed from the six sites to establish 1-year, 2-year, 4-year, and 8- year corrosion rates data sets for different soil environments. The fifth and last set of coupons (approximately 200 at each site) remains undisturbed after 32-years, providing a virtual buried treasure of material and subsurface scientific data. These buried coupons and the surrounding soils represent an analog to the condition of buried waste and containers. Heretofore, the samples were simply pulled from the soil, measured for mass loss and the corrosion rate determined while the subsurface/fate and transport information was not considered nor gathered. Funded through an Environmental Management Science Program (EMSP) proposal, the Idaho National Engineering and Environmental Laboratory (INEEL) operated for the U.S. Department of Energy by Bechtel-BWXT Idaho, LLC (BBWI), is chartered to restart this corrosion test and concurrently capture the available subsurface/fate and transport information. Since the work of retrieving the buried metal coupons is still in the planning stage, this paper outlines the interdisciplinary team of scientists and engineers and defines the benefits of this research to long-term stewardship, subsurface science, and

  14. Digging for Treasure - Unique Fate and Transport Study

    Energy Technology Data Exchange (ETDEWEB)

    Zirker, L.R.; Adler-Flitton, M.K.; Beitel, G.A.

    2003-02-24

    In 1970, scientists at the National Bureau of Standards (NBS), now called the National Institute of Standards and Testing (NIST), implemented the most ambitious and comprehensive long-term corrosion behavior test for stainless steels in soil environments. This study had historic significance since the NBS 1957 landmark corrosion textbook compiled by Romanoff did not include stainless steels, and this 1970 research set forth to complete the missing body of knowledge. To conduct the test, NIST scientists buried 6,324 coupons from stainless steel types, specialty alloys, composite configurations, multiple material forms, and treatment conditions at six distinctive soil-type sites throughout the country. Between 1971 and 1980, four sets of coupons were removed from six sites to establish 1-year, 2-year, 4-year, and 8-year corrosion rates data sets for different soil environments. The fifth and last set of coupons (approximately 200 at each site) remains undisturbed after 32-years, providing a virtual buried treasure of material and subsurface scientific data. These buried coupons and the surrounding soils represent an analog to the condition of buried waste and containers. Heretofore, the samples were simply pulled from the soil, measured for mass loss and the corrosion rate determined while the subsurface/fate and transport information was not considered nor gathered. Funded through an Environmental Management Science Program (EMSP) proposal, the Idaho National Engineering and Environmental Laboratory (INEEL) operated for the U.S. Department of Energy by Bechtel-BWXT Idaho, LLC (BBWI), is chartered to restart this corrosion test and concurrently capture the available subsurface/fate and transport information. Since the work of retrieving the buried metal coupons is still in the planning stage, this paper outlines the interdisciplinary team of scientists and engineers and defines the benefits of this research to long-term stewardship, subsurface science, and

  15. Plant ABC transporters enable many unique aspects of a terrestrial plant's lifestyle

    DEFF Research Database (Denmark)

    Hwang, Jae-Ung; Song, Won-Yong; Hong, Daewoong

    2016-01-01

    processes and functions necessary for life on dry land. These results suggest that ABC transporters multiplied during evolution and assumed novel functions that allowed plants to adapt to terrestrial environmental conditions. Examining the literature on plant ABC transporters from this viewpoint led us......Terrestrial plants have two to four times more ATP-binding cassette (ABC) transporter genes than other organisms, including their ancestral microalgae. Recent studies found that plants harboring mutations in these transporters exhibit dramatic phenotypes, many of which are related to developmental...... to propose that diverse ABC transporters enabled many unique and essential aspects of a terrestrial plant's lifestyle, by transporting various compounds across specific membranes of the plant....

  16. Mild brain ischemia induces unique physiological properties in striatal astrocytes.

    Science.gov (United States)

    Wang, Li-Ping; Cheung, Giselle; Kronenberg, Golo; Gertz, Karen; Ji, Shengbo; Kempermann, Gerd; Endres, Matthias; Kettenmann, Helmut

    2008-07-01

    We studied the properties of GFAP-expressing cells in adult mouse striatum using acute brain slices from transgenic animals expressing EGFP under GFAP promoter. Under physiological conditions, two distinct populations of GFAP-EGFP cells could be identified: (1) brightly fluorescent cells had bushy processes, passive membrane properties, glutamate transporter activity, and high gap junction coupling rate typical for classical astrocytes; (2) weakly fluorescent cells were characterized by thin, clearly distinguishable processes, voltage-gated currents, complex responses to kainate, and low coupling rate reminiscent of an astrocyte subtype recently described in the hippocampus. Mild focal cerebral ischemia confers delayed neuronal cell death and astrogliosis in the striatum. Following middle cerebral artery occlusion and reperfusion, brightly fluorescent cells were the dominant GFAP-EGFP population observed within the ischemic lesion. Interestingly, the majority of these cells expressed voltage-gated channels, showed complex responses to kainate, and a high coupling rate exceeding that of brightly fluorescent control cells. A minority of cells had passive membrane properties and was coupled less compared with passive control cells. We conclude that, in the adult striatum, astrocytes undergo distinct pathophysiological changes after ischemic insults. The dominant population in the ischemic lesion constitutes a novel physiological phenotype unlike any normal astrocyte and generates a large syncytium which might be a neuroprotective response of reactive astrocytes.

  17. Transport properties of ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Starr, T.L.; Hablutzel, N. [Georgia Institute of Technology, Atlanta, GA (United States)

    1996-08-01

    Instrumentation and procedures have been completed for measurement of gas permeability and mass diffusivity of fiber preforms and porous materials. Results are reported for composites reinforced with Nicalon fiber in cloth lay-up and 3-D weave and with Nextel fiber in multi-layer braid. Measured permeability values range from near 100 to less than 0.1 darcies. Mass diffusivity is reported as a structure factor relating the diffusion through the porous material to that in free space. This measure is independent of the diffusing species and depends only on the pore structure of the material. Measurements are compared to predictions of a node-bond model for gas transport. Model parameters adjusted to match measured transport properties relate to physical microstructure features of the different architectures. Combination of this transport model with the CVI process model offers a predictive method to evaluate the densification behavior of various fiber preforms.

  18. Transport properties of organic liquids

    CERN Document Server

    Latini, G; Passerini, G

    2006-01-01

    The liquid state is possibly the most difficult and intriguing state of matter to model. Organic liquids are required, mainly as working fluids, in almost all industrial activities and in most appliances (e.g. in air conditioning). Transport properties (namely dynamic viscosity and thermal conductivity) are possibly the most important properties for the design of devices and appliances. The aim of this book is to present both theoretical approaches and the latest experimental advances on the issue, and to merge them into a wider approach. It concentrates on applicability of models.This book is

  19. Transport Properties of Binary Clusters

    Institute of Scientific and Technical Information of China (English)

    WAN Hai-Qing; ZHOU Yan-Hong; XU Ying

    2007-01-01

    We present first-principles studies on the transport properties of small silicon and aluminium clusters:Al2,Si2,Al4 and AISi sandwiched between two Al(100) electrodes.The variation of the equilibrium conductance as a function of contact distance for these two-probe systems is probed.Our results show that the transport properties are dependent on both the specific nanostructure and the separation distance between the central molecule and the electrodes.For equilibrium transport properties.the clusters with the similar structure show similar transmission spectra at large distances.the small difference can be explained by the electron filling.For current-voltage characteristics,all the clusters show the metallic behaviour at lower bias,however very different non-linear behaviour can be observed at higher bias.For AISi and Al2,when the distance between the central cluster and the electrodes is 3.5A.large negative differential resistance (NDR) can be found in the bias range 0.8V~1.4V.

  20. Transport properties of ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Starr, T.L. [Georgia Inst. of Technology, Atlanta, GA (United States)

    1995-08-01

    This project involves experimental and modeling investigation of the transport properties of chemical vapor infiltration (CVI) preforms and densified composites, with particular emphasis on gas permeability and mass diffusivity. The results of this work will be useful both for on-going CVI process development and for evaluation and optimization of composite materials for fossil energy applications. With preforms made with 500 filaments/tow Nicalon at 40 vol% fiber loading, permeability values are similar for square-weave cloth layup and 3-D weave at low density. At greater densification the 3-D weave permeability is lower and approaches zero with significantly more closed porosity than the cloth layup. For filament wound preforms we were unable to make reliable measurements with the available materials. A model for gas transport in these materials utilizes percolation theory concepts. The ultimate achievable density is related to the closing of a continuous gas path through the preform. As the density approaches this limit the gas permeability and diffusivity vanish exponentially. The value of this limit is controlled primarily by the preform fiber architecture. The observed difference between the cloth layup and 3-D weave materials is due to the larger pores at tow crossing points found in the 3-D weave.

  1. Boundary Unique Continuation Properties for Elliptic Operators With Singular Potentials

    Institute of Scientific and Technical Information of China (English)

    陶祥兴

    2006-01-01

    @@ 0 Introduction Because of applications to control theory, see Schmit and Weck's work in [1], the following unique continuation question (UCP) was raised in [2-3]: if u is a harmonic function in a connected Lipschitz domainΩ, vanishing continuously on an open subset Г of the boundary ( )Ω and whose normal derivative vanishes on a subset of Г of positive surface measure, does it follows that u is identically zero in Ω? On the other hand, the unique continuation problem has been focusing on second order equations in which the coefficients of the lower-order terms are allowed to be singular, which is suggested by situations of physical interest; see for instance the extensive survey papers [4-6].

  2. Vitamin D-regulated calcium transport in Caco-2 cells: unique in vitro model.

    Science.gov (United States)

    Giuliano, A R; Wood, R J

    1991-02-01

    The human colon adenocarcinoma cell line Caco-2 is the only intestinal cell line to differentiate spontaneously in culture exhibiting structural and biochemical characteristics of mature enterocytes and to possess a vitamin D receptor in the fully differentiated state. Transepithelial calcium transport was characterized in differentiated Caco-2 cells grown on permeable filters supports to assess the potential utility of this cell line as an in vitro model to study 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]-induced calcium transport. Calcium transport was increased in a dose-dependent manner by 1,25(OH)2D3. Total calcium transport at different calcium concentrations could be fitted to a modified Michaelis-Menten equation containing a linear transport component. The maximum rate of saturable calcium transport was increased by 4.3-fold (P less than 0.005) in cells treated with 10(-8) M 1,25(OH)2D3. This treatment also increased the apparent buffer calcium concentration that results in half-maximal velocity from 0.4 to 1.3 mM but had no significant effect on nonsaturable calcium transport. Caco-2 cells grown on permeable filter supports provide a unique in vitro human cell culture model to study the mechanism of vitamin D-regulated transepithelial intestinal calcium transport.

  3. The Transport Properties of Activated Carbon Fibers

    Science.gov (United States)

    di Vittorio, S. L.; Dresselhaus, M. S.; Endo, M.; Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons.

  4. Uniqueness and asymptotic stability properties of the critical solution ...

    African Journals Online (AJOL)

    This is because the non-instantaneous reaction of the state parameters is addressed. In this research, the Volterra prey/predator model system is modified by ... contraction and continuity properties of the functional on the Banach space are ...

  5. Friction Anisotropy: A unique and intrinsic property of decagonal quasicrystals

    Energy Technology Data Exchange (ETDEWEB)

    Mulleregan, Alice; Park, Jeong Young; Salmeron, Miquel; Ogetree, D.F.; Jenks, C.J.; Thiel, P.A.; Brenner, J.; Dubois, J.M.

    2008-06-25

    We show that friction anisotropy is an intrinsic property of the atomic structure of Al-Ni-Co decagonal quasicrystals and not only of clean and well-ordered surfaces that can be prepared in vacuum [J.Y. Park et al., Science (2005)]. Friction anisotropy is manifested both in nanometer size contacts obtained with sharp atomic force microscope (AFM) tips as well as in macroscopic contacts produced in pin-on-disc tribometers. We show that the friction anisotropy, which is not observed when an amorphous oxide film covers the surface, is recovered when the film is removed due to wear. Equally important is the loss of the friction anisotropy when the quasicrystalline order is destroyed due to cumulative wear. These results reveal the intimate connection between the mechanical properties of these materials and their peculiar atomic structure.

  6. Carleman estimates and unique continuation property for the anisotropic differential-operator equations

    Institute of Scientific and Technical Information of China (English)

    Veli B SHAKHMUROV

    2008-01-01

    The unique continuation theorems for the anisotropic partial differential-operator equations with variable coefficients in Banach-valued Lp-spaces are studied. To obtain the uniform maximal regularity and the Carleman type estimates for parameter depended differential-operator equations, the sufficient conditions are founded. By using these facts, the unique continuation properties are established. In the application part, the unique continuation properties and Carleman estimates for finite or infinite systems of quasielliptic partial differential equations are studied.

  7. Transport properties of alumina nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Kau-Fui Vincent; Kurma, Tarun [Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL 33124 (United States)], E-mail: kwong@miami.edu

    2008-08-27

    Recent studies have showed that nanofluids have significantly greater thermal conductivity compared to their base fluids. Large surface area to volume ratio and certain effects of Brownian motion of nanoparticles are believed to be the main factors for the significant increase in the thermal conductivity of nanofluids. In this paper all three transport properties, namely thermal conductivity, electrical conductivity and viscosity, were studied for alumina nanofluid (aluminum oxide nanoparticles in water). Experiments were performed both as a function of volumetric concentration (3-8%) and temperature (2-50 deg. C). Alumina nanoparticles with a mean diameter of 36 nm were dispersed in water. The effect of particle size was not studied. The transient hot wire method as described by Nagaska and Nagashima for electrically conducting fluids was used to test the thermal conductivity. In this work, an insulated platinum wire of 0.003 inch diameter was used. Initial calibration was performed using de-ionized water and the resulting data was within 2.5% of standard thermal conductivity values for water. The thermal conductivity of alumina nanofluid increased with both increase in temperature and concentration. A maximum thermal conductivity of 0.7351 W m{sup -1} K{sup -1} was recorded for an 8.47% volume concentration of alumina nanoparticles at 46.6 deg. C. The effective thermal conductivity at this concentration and temperature was observed to be 1.1501, which translates to an increase in thermal conductivity by 22% when compared to water at room temperature. Alumina being a good conductor of electricity, alumina nanofluid displays an increasing trend in electrical conductivity as volumetric concentration increases. A microprocessor-based conductivity/TDS meter was used to perform the electrical conductivity experiments. After carefully calibrating the conductivity meter's glass probe with platinum tip, using a standard potassium chloride solution, readings were

  8. Transport properties of alumina nanofluids.

    Science.gov (United States)

    Wong, Kau-Fui Vincent; Kurma, Tarun

    2008-08-27

    Recent studies have showed that nanofluids have significantly greater thermal conductivity compared to their base fluids. Large surface area to volume ratio and certain effects of Brownian motion of nanoparticles are believed to be the main factors for the significant increase in the thermal conductivity of nanofluids. In this paper all three transport properties, namely thermal conductivity, electrical conductivity and viscosity, were studied for alumina nanofluid (aluminum oxide nanoparticles in water). Experiments were performed both as a function of volumetric concentration (3-8%) and temperature (2-50 °C). Alumina nanoparticles with a mean diameter of 36 nm were dispersed in water. The effect of particle size was not studied. The transient hot wire method as described by Nagaska and Nagashima for electrically conducting fluids was used to test the thermal conductivity. In this work, an insulated platinum wire of 0.003 inch diameter was used. Initial calibration was performed using de-ionized water and the resulting data was within 2.5% of standard thermal conductivity values for water. The thermal conductivity of alumina nanofluid increased with both increase in temperature and concentration. A maximum thermal conductivity of 0.7351 W m(-1) K(-1) was recorded for an 8.47% volume concentration of alumina nanoparticles at 46.6 °C. The effective thermal conductivity at this concentration and temperature was observed to be 1.1501, which translates to an increase in thermal conductivity by 22% when compared to water at room temperature. Alumina being a good conductor of electricity, alumina nanofluid displays an increasing trend in electrical conductivity as volumetric concentration increases. A microprocessor-based conductivity/TDS meter was used to perform the electrical conductivity experiments. After carefully calibrating the conductivity meter's glass probe with platinum tip, using a standard potassium chloride solution, readings were taken at

  9. Rapid transport from the surface to wells in fractured rock: a unique infiltration tracer experiment.

    Science.gov (United States)

    Levison, Jana K; Novakowski, Kent S

    2012-04-01

    A unique infiltration tracer experiment was performed whereby a fluorescent dye was applied to the land surface in an agricultural field, near Perth, Ontario, Canada, to simulate the transport of solutes to two pumped monitoring wells drilled into the granitic gneiss aquifer. This experiment, interpreted using the discrete-fracture capability of the numerical model HydroGeoSphere, showed that solute transport from the surface through thin soil (less than 2m) to wells in fractured bedrock can be extremely rapid (on the order of hours). Also, it was demonstrated that maximum concentrations of contaminants originating from the ground surface will not necessarily be the highest in the shallow aquifer horizon. These are important considerations for both private and government-owned drinking water systems that draw water from shallow fractured bedrock aquifers. This research illustrates the extreme importance of protecting drinking water at the source.

  10. Nanofluidics thermodynamic and transport properties

    CERN Document Server

    Michaelides, Efstathios E (Stathis)

    2014-01-01

    This volume offers a comprehensive examination of the subject of heat and mass transfer with nanofluids as well as a critical review of the past and recent research projects in this area. Emphasis is placed on the fundamentals of the transport processes using particle-fluid suspensions, such as nanofluids. The nanofluid research is examined and presented in a holistic way using a great deal of our experience with the subjects of continuum mechanics, statistical thermodynamics, and non-equilibrium thermodynamics of transport processes. Using a thorough database, the experimental, analytical, and numerical advances of recent research in nanofluids are critically examined and connected to past research with medium and fine particles as well as to functional engineering systems. Promising applications and technological issues of heat/mass transfer system design with nanofluids are also discussed. This book also: Provides a deep scientific analysis of nanofluids using classical thermodynamics and statistical therm...

  11. Carleman estimates and unique continuation property for the anisotropic differential-operator equations

    Institute of Scientific and Technical Information of China (English)

    Veli; B; SHAKHMUROV

    2008-01-01

    The unique continuation theorems for the anisotropic partial differential-operator equations with variable coeffcients in Banach-valued Lp-spaces are studied.To obtain the uniform maximal regularity and the Carleman type estimates for parameter depended differential-operator equations,the suffcient conditions are founded.By using these facts,the unique continuation properties are established.In the application part,the unique continuation properties and Carleman estimates for finite or infinite systems of quasielliptic partial differential equations are studied.

  12. Electronic transport properties in graphene oxide frameworks

    Science.gov (United States)

    Zhu, P.; Cruz-Silva, E.; Meunier, V.

    2014-02-01

    The electronic transport properties in multiterminal graphene oxide framework (GOF) materials are investigated using a combination of theoretical and computational methods. GOFs make up four-terminal [origin=c]90H-shaped GNR-L-GNR junctions where sandwiched boronic acid molecules (L) are covalently linked to two graphene nanoribbons (GNRs) of different edge chiralities. The transport properties are governed by both tunneling and quasiresonant regimes. We determine how the presence of linker molecules affects the transport properties and establish that the through-molecule transport properties can be tuned by varying the chemical composition of the pillar molecules but are not significantly modified when changing the type of electrodes from zigzag GNRs to armchair GNRs. In addition, we find that in multilinker systems containing two parallel molecules in the device area, the coupling between the molecules can lead to both constructive and destructive quantum interferences. We also examine the inability of the classical Kirchhoff's superposition law to account for electron flow in multilinker GOF nanonetworks.

  13. Transport properties of fully screened Kondo models

    NARCIS (Netherlands)

    Hörig, Christoph B M; Mora, Christophe; Schuricht, Dirk

    2014-01-01

    We study the nonequilibrium transport properties of fully (exactly) screened Kondo quantum dots subject to a finite bias voltage or a finite temperature. First, we calculate the Fermi-liquid coefficients of the conductance for models with arbitrary spin, i.e., its leading behavior for small bias vol

  14. Transport properties of inertial confinement fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Issanova, M.K.; Kodanova, S.K.; Ramazanov, T.S. [IETP, Al-Farabi Kazakh National University, Almaty (Kazakhstan); Hoffmann, D.H.H. [Institut fuer Kernphysik, Technische Universitaet Darmstadt (Germany)

    2016-06-15

    In this paper the transport properties of non-isothermal dense deuterium-tritium plasmas were studied. Based on the effective interaction potentials between particles, the Coulomb logarithm for a two-temperature nonisothermal dense plasma was obtained. These potentials take into consideration long-range multi-particle screening effects and short-range quantum-mechanical effects in two-temperature plasmas. Transport processes in such plasmas were studied using the Coulomb logarithm. The obtained results were compared with the theoretical works of other authors and with the results of molecular dynamics simulations. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. UNIQUE CONTINUATION AND PERSISTENCE PROPERTIES OF SOLUTIONS OF THE 2-COMPONENT DEGASPERIS-PROCESI EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    Fu Ying; Qu Changzheng

    2012-01-01

    In this article,the unique continuation and persistence properties of solutions of the 2-component Degasperis-Procesi equations are discussed.It is shown that strong solutions of the 2-component Degasperis-Procesi equations,initially decaying exponentially together with its spacial derivative,must be identically equal to zero if they also decay exponentially at a later time.

  16. Effects of uniquely processed cowpea and plantain flours on wheat bread properties

    Science.gov (United States)

    The effect of incorporating uniquely processed whole-seed cowpeas or plantain flours at 10 or 20 g/100 g in all-purpose flour on paste viscosity and bread-baking properties in model bread was determined. Flours from plantains processed as follows: unblanched plantains dried at 60 degrees C (PLC), so...

  17. Unique magnetic and thermoelectric properties of chemically functionalized narrow carbon polymers

    Science.gov (United States)

    Zberecki, K.; Wierzbicki, M.; Swirkowicz, R.; Barnaś, J.

    2017-02-01

    We analyze magnetic, transport and thermoelectric properties of narrow carbon polymers, which are chemically functionalized with nitroxide groups. Numerical calculations of the electronic band structure and the corresponding transmission function are based on density functional theory. Transport and thermoelectric parameters are calculated in the linear response regime, with particular interest in charge and spin thermopowers (charge and spin Seebeck effects). Such nanoribbons are shown to have thermoelectric properties described by large thermoelectric efficiency, which makes these materials promising from the application point of view.

  18. Universal Property of Quantum Gravity implied by Uniqueness Theorem of Bekenstein-Hawking Entropy

    CERN Document Server

    Saida, Hiromi

    2011-01-01

    This paper consists of three steps. In the first, we prove that the Bekenstein-Hawking entropy is the unique expression of black hole entropy. Our proof is constructed in the framework of thermodynamics without any statistical discussion. In the second, intrinsic properties of quantum mechanics are shown, which justify the Boltzmann formula to yield a unique entropy in statistical mechanics. These properties clarify three conditions, one of which is necessary and others are sufficient for the validity of Boltzmann formula. In the third, by combining the above results, we find a reasonable suggestion from the sufficient conditions that the potential of gravitational interaction among microstates of underlying quantum gravity may not diverge to negative infinity (such as Newtonian gravity) but is bounded below at a finite length scale. In addition to that, from the necessary condition, the interaction has to be repulsive within the finite length scale. The length scale should be Planck size. Thus, quantum gravi...

  19. Thermodynamic and transport properties of gaseous tetrafluoromethane in chemical equilibrium

    Science.gov (United States)

    Hunt, J. L.; Boney, L. R.

    1973-01-01

    Equations and in computer code are presented for the thermodynamic and transport properties of gaseous, undissociated tetrafluoromethane (CF4) in chemical equilibrium. The computer code calculates the thermodynamic and transport properties of CF4 when given any two of five thermodynamic variables (entropy, temperature, volume, pressure, and enthalpy). Equilibrium thermodynamic and transport property data are tabulated and pressure-enthalpy diagrams are presented.

  20. Exploitation of Unique Properties of Zeolites in the Development of Gas Sensors

    Directory of Open Access Journals (Sweden)

    Prabir K. Dutta

    2012-04-01

    Full Text Available The unique properties of microporous zeolites, including ion-exchange properties, adsorption, molecular sieving, catalysis, conductivity have been exploited in improving the performance of gas sensors. Zeolites have been employed as physical and chemical filters to improve the sensitivity and selectivity of gas sensors. In addition, direct interaction of gas molecules with the extraframework cations in the nanoconfined space of zeolites has been explored as a basis for developing new impedance-type gas/vapor sensors. In this review, we summarize how these properties of zeolites have been used to develop new sensing paradigms. There is a considerable breadth of transduction processes that have been used for zeolite incorporated sensors, including frequency measurements, optical and the entire gamut of electrochemical measurements. It is clear from the published literature that zeolites provide a route to enhance sensor performance, and it is expected that commercial manifestation of some of the approaches discussed here will take place. The future of zeolite-based sensors will continue to exploit its unique properties and use of other microporous frameworks, including metal organic frameworks. Zeolite composites with electronic materials, including metals will lead to new paradigms in sensing. Use of nano-sized zeolite crystals and zeolite membranes will enhance sensor properties and make possible new routes of miniaturized sensors.

  1. Electronic and transport properties of kinked graphene

    DEFF Research Database (Denmark)

    Rasmussen, Jesper Toft; Gunst, Tue; Bøggild, Peter

    2013-01-01

    Local curvature, or bending, of a graphene sheet is known to increase the chemical reactivity presenting an opportunity for templated chemical functionalisation. Using first-principles calculations based on density functional theory (DFT), we investigate the reaction barrier reduction...... for the adsorption of atomic hydrogen at linear bends in graphene. We find a significant barrier lowering (≈15%) for realistic radii of curvature (≈20 Å) and that adsorption along the linear bend leads to a stable linear kink. We compute the electronic transport properties of individual and multiple kink lines......, and demonstrate how these act as efficient barriers for electron transport. In particular, two parallel kink lines form a graphene pseudo-nanoribbon structure with a semimetallic/semiconducting electronic structure closely related to the corresponding isolated ribbons; the ribbon band gap translates...

  2. Electron transport properties of cobalt doped polyaniline

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, P [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Sarkar, A [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Meikap, A K [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Chattopadhyay, S K [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Chatterjee, S K [Department of Physics, National Institute of Technology, Durgapur, Deemed University, Mahatma Gandhi Avenue, PIN-713 209, West Bengal (India); Ghosh, M [Department of Physics, Ramananda College, Bishnupur, Bankura-722 122, West Bengal (India)

    2006-07-21

    Electrical transport properties of cobalt doped polyaniline in an aqueous ethanol medium were investigated in the temperature range 77 {<=} T {<=} 300 K, applying magnetic fields up to 1 T in the frequency range 20 Hz-1 MHz. The room temperature dc resistivity increases with increase in Co content. The dc resistivity and magnetoresistivity of these samples have been interpreted in terms of the variable range hopping theory. The frequency dependence of conductivity has been described by a power law {sigma}({omega}) {approx} {omega}{sup S}. The value of s is found to be temperature dependent, which shows a decreasing trend with temperature. The correlated barrier hopping model is the most likely mechanism for the electron transport. The different physical parameters were calculated from the experimental data.

  3. TRANSPORT PROPERTIES OF THE STRONGLY CORRELATED SYSTEMS

    Directory of Open Access Journals (Sweden)

    T.Domanski

    2004-01-01

    Full Text Available The transport properties of various systems are studied here in the context of three different models. These are: - the disordered Hubbard model applicable to correlated binary alloys with a general disorder, - the Anderson model used in describing the Kondo physics of a quantum dot connected to the external superconducting leads, and - the Ranninger-Robaszkiewicz model applied to the study of optical properties of the system with preformed electron pairs above the temperature of transition to the superconducting state. We calculate the density of states, specific heat, the Wilson ratio and conductivity of the correlated binary alloy with off-diagonal disorder. We investigate the conditions under which the Kondo peak appears in the density of states and in the conductance of a dot coupled to the external superconducting leads. We analyze the effect of the pseudogap on the optical spectra in the high temperature superconductors described by the boson-fermion model.

  4. Unique properties of graphene quantum dots and their applications in photonic/electronic devices

    Science.gov (United States)

    Choi, Suk-Ho

    2017-03-01

    In recent years, graphene quantum dots (GQDs) have been recognized as an attractive building block for electronic, photonic, and bio-molecular device applications. This paper reports the current status of studies on the novel properties of GQDs and their hybrids with conventional and low-dimensional materials for device applications. In this review, more emphasis is placed on the structural, electronic, and optical properties of GQDs, and device structures based on the combination of GQDs with various semiconducting/insulating materials such as graphene, silicon dioxide, Si quantum dots, silica nanoparticles, organic materials, and so on. Because of GQDs’ unique properties, their hybrid structures are employed in high-efficiency devices, including photodetectors, solar cells, light-emitting diodes, flash memory, and sensors.

  5. PLGG1, a plastidic glycolate glycerate transporter, is required for photorespiration and defines a unique class of metabolite transporters.

    Science.gov (United States)

    Pick, Thea R; Bräutigam, Andrea; Schulz, Matthias A; Obata, Toshihiro; Fernie, Alisdair R; Weber, Andreas P M

    2013-02-19

    Photorespiratory carbon flux reaches up to a third of photosynthetic flux, thus contributes massively to the global carbon cycle. The pathway recycles glycolate-2-phosphate, the most abundant byproduct of RubisCO reactions. This oxygenation reaction of RubisCO and subsequent photorespiration significantly limit the biomass gains of many crop plants. Although photorespiration is a compartmentalized process with enzymatic reactions in the chloroplast, the peroxisomes, the mitochondria, and the cytosol, no transporter required for the core photorespiratory cycle has been identified at the molecular level to date. Using transcript coexpression analyses, we identified Plastidal glycolate glycerate translocator 1 (PLGG1) as a candidate core photorespiratory transporter. Related genes are encoded in the genomes of archaea, bacteria, fungi, and all Archaeplastida and have previously been associated with a function in programmed cell-death. A mutant deficient in PLGG1 shows WT-like growth only in an elevated carbon dioxide atmosphere. The mutant accumulates glycolate and glycerate, leading to the hypothesis that PLGG1 is a glycolate/glycerate transporter. This hypothesis was tested and supported by in vivo and in vitro transport assays and (18)O(2)-metabolic flux profiling. Our results indicate that PLGG1 is the chloroplastidic glycolate/glycerate transporter, which is required for the function of the photorespiratory cycle. Identification of the PLGG1 transport function will facilitate unraveling the role of similar proteins in bacteria, archaea, and fungi in the future.

  6. Enhanced Tensile Properties of Mg Sheets by a Unique Thermomechanical Processing Method

    Science.gov (United States)

    Bian, Mingzhe; Zeng, Zhuoran; Xu, Shiwei; Tang, Weineng; Davies, Christopher H. J.; Birbilis, Nick; Nie, Jian-feng

    2016-12-01

    A unique thermomechanical processing method combining fast rolling with large thickness reduction and short-time annealing (FR-STA) was developed to produce lower-cost magnesium (Mg) sheets with improved tensile properties. Sheets of Mg-3Al-1Zn-0.3Mn (wt pct) and Mg-1Zn-0.2Nd-0.2Zr (wt pct) were produced by FR incorporating large thickness reduction, exhibiting enhanced strength and improved ductility relative to slow rolling with small thickness reduction after STA.

  7. The Unique Photophysical Properties of the Peridinin-Chlorophyll-a-Protein

    Science.gov (United States)

    Carbonera, Donatella; Valentin, Marilena Di; Spezia, Riccardo; Mezzetti, Alberto

    2014-01-01

    Peridinin-Chlorophyll-a-Proteins (PCPs) are water-soluble light harvesting complexes from dinoflagellates. They have unique light-harvesting and energy transfer properties which have been studied in details in the last 15 years. This review aims to give an overview on all the main aspects of PCPs photophysics, with an emphasis on some aspects which have not been reviewed in details so far, such as vibrational spectroscopy studies, theoretical calculations, and magnetic resonance studies. A paragraph on the present development of PCPs towards technological applications is also included. PMID:24678668

  8. Unique pharmacological property of ISRIB in inhibition of Aβ-induced neuronal cell death

    Directory of Open Access Journals (Sweden)

    Toru Hosoi

    2016-08-01

    Full Text Available A pharmacological approach to ameliorate Alzheimer's disease (AD has not yet been established. In the present study, we investigated the pharmacological characteristics of the recently identified memory-enhancing compound, ISRIB for the amelioration of AD. ISRIB potently attenuated amyloid β-induced neuronal cell death at concentrations of 12.5–25 nM, but did not inhibit amyloid β production in the HEK293T cell line expressing the amyloid precursor protein (APP. These results suggest that ISRIB possesses the unique pharmacological property of attenuating amyloid β-induced neuronal cell death without affecting amyloid β production.

  9. Electronic transport properties of (fluorinated) metal phthalocyanine

    KAUST Repository

    Fadlallah, M M

    2015-12-21

    The magnetic and transport properties of the metal phthalocyanine (MPc) and F16MPc (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn and Ag) families of molecules in contact with S–Au wires are investigated by density functional theory within the local density approximation, including local electronic correlations on the central metal atom. The magnetic moments are found to be considerably modified under fluorination. In addition, they do not depend exclusively on the configuration of the outer electronic shell of the central metal atom (as in isolated MPc and F16MPc) but also on the interaction with the leads. Good agreement between the calculated conductance and experimental results is obtained. For M = Ag, a high spin filter efficiency and conductance is observed, giving rise to a potentially high sensitivity for chemical sensor applications.

  10. Electronic transport properties of phenylacetylene molecular junctions

    Institute of Scientific and Technical Information of China (English)

    Liu Wen; Cheng Jie; Yah Cui-Xia; Li Hai-Hong; Wang Yong-Juan; Liu De-Sheng

    2011-01-01

    Electronic transport properties of a kind of phenylacetylene compound- (4-mercaptophenyl)-phenylacetylene are calculated by the first-principles method in the framework of density functional theory and the nonequilibrium Green's function formalism.The molecular junction shows an obvious rectifying behaviour at a bias voltage larger than 1.0 V.The rectification effect is attributed to the asymmetry of the interface contacts.Moreover,at a bias voltage larger than 2.0 V,which is not referred to in a relevant experiment [Fang L,Park J Y,Ma H,Jan A K Y and Salmeron M 2007 Langmuir 23 11522],we find a negative differential resistance phenomenon.The negative differential resistance effect may originate from the change of the delocalization degree of the molecular orbitais induced by the bias.

  11. Transport Properties of the Universal Quantum Equation

    Institute of Scientific and Technical Information of China (English)

    A.I.Arbab

    2012-01-01

    The universal quantum equation (UQE) is found to describe the transport properties of the quantum particles.This equation describes a wave equation interacting with constant scalar and vector potentials propagating in spacetime.A new transformation that sends the Schr(o)dinger equation with a potential energy V =-1/2mc2 to Dirac's equation is proposed.The Cattaneo telegraph equation as well as a one-dimensional UQE are compatible with our recently proposed generalized continuity equations.Furthermore,a new wave equation resulted from the invariance of the UQE under the post-Galilean transformations is derived.This equation is found to govern a Klein Gordon's particle interacting with a photon-like vector field (ether) whose magnitude is proportional to the particle's mass.

  12. Universal Property of Quantum Gravity implied by Uniqueness Theorem of Bekenstein-Hawking Entropy

    Directory of Open Access Journals (Sweden)

    Hiromi Saida

    2011-09-01

    Full Text Available This paper consists of three parts. In the first part, we prove that the Bekenstein-Hawking entropy is the unique expression of black hole entropy. Our proof is constructed in the framework of thermodynamics without any statistical discussion. In the second part, intrinsic properties of quantum mechanics are shown, which justify the Boltzmann formula to yield a unique entropy in statistical mechanics. These properties clarify three conditions, one of which is necessary and others are sufficient for the validity of Boltzmann formula. In the third part, by combining the above results, we find a reasonable suggestion from the sufficient conditions that the potential of gravitational interaction among microstates of underlying quantum gravity may not diverge to negative infinity (such as Newtonian gravity but is bounded below at a finite length scale. In addition to that, from the necessary condition, the interaction has to be repulsive within the finite length scale. The length scale should be Planck size. Thus, quantum gravity may become repulsive at Planck length. Also, a relation of these suggestions with action integral of gravity at semi-classical level is given. These suggestions about quantum gravity are universal in the sense that they are independent of any existing model of quantum gravity.

  13. Copper-transporting P-type ATPases use a unique ion-release pathway

    DEFF Research Database (Denmark)

    Andersson, Magnus; Mattle, Daniel; Sitsel, Oleg

    2014-01-01

    Heavy metals in cells are typically regulated by PIB-type ATPases. The first structure of the class, a Cu(+)-ATPase from Legionella pneumophila (LpCopA), outlined a copper transport pathway across the membrane, which was inferred to be occluded. Here we show by molecular dynamics simulations...

  14. 4d electron Ruthenate systems: their unique and new magnetic properties

    Science.gov (United States)

    Lee, Seungran; Shin, Yeongjae; Anwar, M. S.; Sugimoto, Yusuke; Lee, Mincheol; Kang, Sungjin; Yonezawa, Shingo; Maeno, Yoshiteru; Noh, Taewon

    The Ruddlesden-Popper series (PR) of Srn+1RunO3n+1 has attract much interest of their unique physical properties. Among them, SrRuO3 (n = ∞) (SRO) is the only ferromagnetic metallic oxide especially in Ru 4d transition metal oxides. Bulk SRO has orthorhombic structure showing the Curie temperature (TC) ~ 160 K. It is well known that RuO6 octahedral distortion plays critical roles in its mangetic properties. In film systems, such RuO6 octahedra can be easily controlled by strain-engineering. In this talk, with high quality SRO films fully strained (-1.7%-1%) using various substrates, we systematically studied their structural changes and associated magnetic properties. Compared to theoretical predictions, the structural changes can be explained, while the magnetic property changes cannot be understood. Surprisingly, when SRO113 is grown on its PR series of Sr2RuO4 (n=1) (SRO214) single crystal, the exact substrate of SRO214 magnetization results in strongly enhanced magnetization (M > 3 μB/Ru, TC ~ 160 K), which has never found SRO113 (001) since the low-spin configuration of SRO113 prevent M never exceed 2 μB/Ru. The mystery of M in SRO113 (especially SRO113/SRO214) will be further discussed.

  15. Photoacoustic as a unique tool for studying multicomponent gas transport processes through rock samples

    Science.gov (United States)

    András Simon, Károly; Puskás, Sándor; Ricza, Tamás; Bozóki, Zoltán

    2017-04-01

    Improvement of natural gas extraction is one of the constant challenges of gas industry. Gas transport through the material of the reservoir is driven by two forces. Conventional diffusion driven by the concentration gradient and the Darcy flow driven by the differential pressure at the two ends of the material. Their segregated yield and their interrelation is largely influenced by the intrinsic structure of the sample so their measurement can yield important information There are multiple methods for measuring these parameters (Sander et al, 2017). We present a measurement set-up which uses photoacoustic spectroscopy for the detection of the transported components. It is a highly sensitive and selective measurement method (Bozóki et al., 2011) and can be used to measure concentration through 4-5 orders of magnitudes. Furthermore it can be operated fully automatically, has response time in the second range and outstanding long term stability. This allows us to perform measurements on a wide variety of samples either in static or in dynamic mode under different conditions and various analytes. Furthermore transport of several gas components can be measured simultaneously. Our set-up facilities measurements in a wide pressure, temperature and concentration range. Bozóki Z., Pogány A., Szabó G. (2011), Applied Spectroscopy Reviews 46, 1-37 Sander, R., Pan, Z. and Connell, Luke D. (2017), Journal of Natural Gas Science and Engineering 37, 248-279.

  16. Structural, Bioinformatic, and In Vivo Analyses of Two Treponema pallidum Lipoproteins Reveal a Unique TRAP Transporter

    Energy Technology Data Exchange (ETDEWEB)

    Deka, Ranjit K.; Brautigam, Chad A.; Goldberg, Martin; Schuck, Peter; Tomchick, Diana R.; Norgard, Michael V. (NIH); (UTSMC)

    2012-05-25

    Treponema pallidum, the bacterial agent of syphilis, is predicted to encode one tripartite ATP-independent periplasmic transporter (TRAP-T). TRAP-Ts typically employ a periplasmic substrate-binding protein (SBP) to deliver the cognate ligand to the transmembrane symporter. Herein, we demonstrate that the genes encoding the putative TRAP-T components from T. pallidum, tp0957 (the SBP), and tp0958 (the symporter), are in an operon with an uncharacterized third gene, tp0956. We determined the crystal structure of recombinant Tp0956; the protein is trimeric and perforated by a pore. Part of Tp0956 forms an assembly similar to those of 'tetratricopeptide repeat' (TPR) motifs. The crystal structure of recombinant Tp0957 was also determined; like the SBPs of other TRAP-Ts, there are two lobes separated by a cleft. In these other SBPs, the cleft binds a negatively charged ligand. However, the cleft of Tp0957 has a strikingly hydrophobic chemical composition, indicating that its ligand may be substantially different and likely hydrophobic. Analytical ultracentrifugation of the recombinant versions of Tp0956 and Tp0957 established that these proteins associate avidly. This unprecedented interaction was confirmed for the native molecules using in vivo cross-linking experiments. Finally, bioinformatic analyses suggested that this transporter exemplifies a new subfamily of TPATs (TPR-protein-associated TRAP-Ts) that require the action of a TPR-containing accessory protein for the periplasmic transport of a potentially hydrophobic ligand(s).

  17. Transport properties of supercooled confined water

    Science.gov (United States)

    Mallamace, F.; Branca, C.; Broccio, M.; Corsaro, C.; Gonzalez-Segredo, N.; Spooren, J.; Stanley, H. E.; Chen, S.-H.

    2008-07-01

    This article presents an overview of recent experiments performed on transport properties of water in the deeply supercooled region, a temperature region of fundamental importance in the science of water. We report data of nuclear magnetic resonance, quasi-elastic neutron scattering, Fourier-transform infrared spectroscopy, and Raman spectroscopy, studying water confined in nanometer-scale environments. When contained within small pores, water does not crystallise, and can be supercooled well below its homogeneous nucleation temperature Th. On this basis it is possible to carry out a careful analysis of the well known thermodynamical anomalies of water. Studying the temperature and pressure dependencies of water dynamics, we show that the liquid-liquid phase transition (LLPT) hypothesis represents a reliable model for describing liquid water. In this model, water in the liquid state is a mixture of two different local structures, characterised by different densities, namely the low density liquid (LDL) and the high-density liquid (HDL). The LLPT line should terminate at a special transition point: a low-T liquid-liquid critical point. We discuss the following experimental findings on liquid water: (i) a crossover from non-Arrhenius behaviour at high T to Arrhenius behaviour at low T in transport parameters; (ii) a breakdown of the Stokes-Einstein relation; (iii) the existence of a Widom line, which is the locus of points corresponding to maximum correlation length in the p-T phase diagram and which ends in the liquid-liquid critical point; (iv) the direct observation of the LDL phase; (v) a minimum in the density at approximately 70 K below the temperature of the density maximum. In our opinion these results represent the experimental proofs of the validity of the LLPT hypothesis.

  18. Elastic properties and electron transport in InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Migunov, Vadim

    2013-02-22

    The electron transport and elastic properties of InAs nanowires grown by chemical vapor deposition on InAs (001) substrate were studied experimentally, in-situ in a transmission electron microscope (TEM). A TEM holder allowing the measurement of a nanoforce while simultaneous imaging nanowire bending was used. Diffraction images from local areas of the wire were recorded to correlate elastic properties with the atomic structure of the nanowires. Another TEM holder allowing the application of electrical bias between the nanowire and an apex of a metallic needle while simultaneous imaging the nanowire in TEM or performing electron holography was used to detect mechanical vibrations in mechanical study or holographical observation of the nanowire inner potential in the electron transport studies. The combination of the scanning probe methods with TEM allows to correlate the measured electric and elastic properties of the nanowires with direct identification of their atomic structure. It was found that the nanowires have different atomic structures and different stacking fault defect densities that impacts critically on the elastic properties and electric transport. The unique methods, that were applied in this work, allowed to obtain dependencies of resistivity and Young's modulus of left angle 111 right angle -oriented InAs nanowires on defect density and diameter. It was found that the higher is the defect density the higher are the resistivity and the Young's modulus. Regarding the resistivity, it was deduced that the stacking faults increase the scattering of the electrons in the nanowire. These findings are consistent with the literature, however, the effect described by the other groups is not so pronounced. This difference can be attributed to the significant incompleteness of the physical models used for the data analysis. Regarding the elastic modulus, there are several mechanisms affecting the elasticity of the nanowires discussed in the thesis. It

  19. Unique self-assembly properties of a bridge-shaped protein dimer with quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jianhao; Jiang, Pengju [Changzhou University, School of Pharmaceutical Engineering and Life Science (China); Gao, Liqian; Yu, Yongsheng; Lu, Yao [The Chinese University of Hong Kong, Department of Chemistry (Hong Kong, China) (China); Qiu, Lin; Wang, Cheli [Changzhou University, School of Pharmaceutical Engineering and Life Science (China); Xia, Jiang, E-mail: jiangxia@cuhk.edu.hk [The Chinese University of Hong Kong, Department of Chemistry (Hong Kong, China) (China)

    2013-09-15

    How protein-protein interaction affects protein-nanoparticle self-assembly is the key to the understanding of biomolecular coating of nanoparticle in biological fluids. However, the relationship between protein shape and its interaction with nanoparticles is still under-exploited because of lack of a well-conceived binding system and a method to detect the subtle change in the protein-nanoparticle assemblies. Noticing this unresolved need, we cloned and expressed a His-tagged SpeA protein that adopts a bridge-shaped dimer structure, and utilized a high-resolution capillary electrophoresis method to monitor assembly formation between the protein and quantum dots (QDs, 5 nm in diameter). We observed that the bridge-shaped structure rendered a low SpeA:QD stoichiometry at saturation. Also, close monitoring of imidazole (Im) displacement of surface-bound protein revealed a unique two-step process. High-concentration Im could displace surface-bound SpeA protein and form a transient QD-protein intermediate, through a kinetically controlled displacement process. An affinity-driven equilibrium step then followed, resulting in re-assembling of the QD-protein complex in about 1 h. Through a temporarily formed intermediate, Im causes a rearrangement of His-tagged proteins on the surface. Thus, our work showcases that the synergistic interplay between QD-His-tag interaction and protein-protein interaction can result in unique properties of protein-nanoparticle assembly for the first time.

  20. Electron transport properties of carbon-based nanostructures

    Science.gov (United States)

    Diaz Pinto, Carlos A.

    Grapheme and graphene-related systems have been the focus of intensive research due to their exceptional electronic behavior. Their properties have been studied for decades, from the unique band structure predicted for a single layer of graphite, to the unexpected linear magnetoresistance observed in its bulk form. Since its experimental isolation in 2004, studies on graphene monolayer, bilayer, and few-layer systems garnered an overwhelming amount of attention from the scientific community, with studies focusing on multilayers with nanometer thicknesses paling in comparison. The main motivation of this study is to further the understanding of systems consisting of multilayer graphene and ultrathin graphite (graphitic multilayers) through electron transport experiments. Uniquely designed and fabricated devices based on carbon nanostructures were used to study the transport of charge carriers under high electric and magnetic fields. For short-channel suspended graphitic multilayer devices, the two-terminal differential conductance dI/dV as a function of drain-source bias Vd displays a pronounced dip pinned at Vd=0, explained by the hot electron effect. The dip is attenuated under high magnetic fields, likely due to intra-Landau level cyclotron phonon scattering. Also, distinct high-energy dI/dV anomalies have been observed and shown to be related to intrinsic phonon-emission processes in graphite. The evolution of such dI/dV anomalies under magnetic fields is understood as a consequence of the inter-Landau level cyclotron-phonon resonance scattering. The magnetoresistance (MR) of this system shows Shubnikov-de Haas oscillations on top of a strong positive nearly-linear background. Upon the introduction of a significant amount of short-range disorders through ion implantation, the positive MR transforms into a negative MR. The results for the MR of pure and implanted graphitic multilayers can be understood by considering a recent magneto-transport theory for two

  1. Unique pharmacological property of ISRIB in inhibition of Aβ-induced neuronal cell death.

    Science.gov (United States)

    Hosoi, Toru; Kakimoto, Mai; Tanaka, Keigo; Nomura, Jun; Ozawa, Koichiro

    2016-08-01

    A pharmacological approach to ameliorate Alzheimer's disease (AD) has not yet been established. In the present study, we investigated the pharmacological characteristics of the recently identified memory-enhancing compound, ISRIB for the amelioration of AD. ISRIB potently attenuated amyloid β-induced neuronal cell death at concentrations of 12.5-25 nM, but did not inhibit amyloid β production in the HEK293T cell line expressing the amyloid precursor protein (APP). These results suggest that ISRIB possesses the unique pharmacological property of attenuating amyloid β-induced neuronal cell death without affecting amyloid β production. Copyright © 2016 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

  2. Global and uniqueness properties of stationary and static spacetimes with outer trapped surfaces

    CERN Document Server

    Mars, Marc

    2012-01-01

    Global properties of maximal future Cauchy developments of stationary, m-dimensional asymptotically flat initial data with an outer trapped boundary are analyzed. We prove that, whenever the matter model is well posed and satisfies the null energy condition, the future Cauchy development of the data is a black hole spacetime. More specifically, we show that the future Killing development of the exterior of a sufficiently large sphere in the initial data set can be isometrically embedded in the maximal Cauchy development of the data. In the static setting we prove, by working directly on the initial data set, that all Killing prehorizons are embedded whenever the initial data set has an outer trapped boundary and satisfies the null energy condition. By combining both results we prove a uniqueness theorem for static initial data sets with outer trapped boundary.

  3. Liquid but Durable: Molecular Dynamics Simulations Explain the Unique Properties of Archaeal-Like Membranes

    Science.gov (United States)

    Chugunov, Anton O.; Volynsky, Pavel E.; Krylov, Nikolay A.; Boldyrev, Ivan A.; Efremov, Roman G.

    2014-12-01

    Archaeal plasma membranes appear to be extremely durable and almost impermeable to water and ions, in contrast to the membranes of Bacteria and Eucaryota. Additionally, they remain liquid within a temperature range of 0-100°C. These are the properties that have most likely determined the evolutionary fate of Archaea, and it may be possible for bionanotechnology to adopt these from nature. In this work, we use molecular dynamics simulations to assess at the atomistic level the structure and dynamics of a series of model archaeal membranes with lipids that have tetraether chemical nature and ``branched'' hydrophobic tails. We conclude that the branched structure defines dense packing and low water permeability of archaeal-like membranes, while at the same time ensuring a liquid-crystalline state, which is vital for living cells. This makes tetraether lipid systems promising in bionanotechnology and material science, namely for design of new and unique membrane nanosystems.

  4. Discovery of lansoprazole and its unique pharmacological properties independent from anti-secretory activity.

    Science.gov (United States)

    Satoh, Hiroshi

    2013-01-01

    The proton pump inhibitors (PPIs) lansoprazole (LPZ) and omeprazole (OPZ) have been widely used for more than 20 years in the treatment of acid-related diseases such as gastro-duodenal ulcers and reflux esophagitis. Both LPZ and OPZ are derivatives of 2-[(2- pyridylmethyl)sulfinyl]-1H-benzimidazole, but LPZ has a trifluoroethoxy group in the molecule which seems to provide unique pharmacological properties in addition to its anti-secretory effect. For example, the anti-secretory effect of LPZ in rats was roughly 2 times greater than that of OPZ but the anti-ulcer effects were more than 10 times stronger than those of OPZ in rat models of reflux esophagitis, indomethacin-induced gastric antral ulcers and mepirizole-induced duodenal ulcers. It has also been reported that LPZ has acid-independent protective effects on the gastrointestinal mucosa, anti-inflammatory effects, and anti-bacterial effects on Helicobacter pylori. In contrast, recent advances in endoscopy have revealed that non-steroidal anti-inflammatory drugs (NSAIDs) often cause ulcers not only in the stomach and duodenum, but also in the small intestine in humans. Anti-secretory drugs such as PPIs and histamine H(2)-receptor antagonists (H(2)-RAs) are commonly used for the treatment of upper gastrointestinal mucosal lesions induced by NSAIDs. However, the effects of these drugs on NSAID-induced small intestinal lesions are still not fully understood. In this article, both a brief history of the discovery of LPZ and the unique pharmacological properties of LPZ independent from its anti-secretory action are reviewed, and the effects of PPIs and H(2)-RAs on NSAID-induced small intestinal lesions are discussed.

  5. Transport properties of ruthenophanes - A theoretical insight

    Science.gov (United States)

    Garcia, Leone C.; Caramori, Giovanni F.; Bergamo, Pedro A. S.; Parreira, Renato L. T.

    2016-10-01

    In this article, the electron transport properties of a series of ruthenophanes, 1-4, containing electron-donor and electron-acceptor substituents are studied. The electronic transmission at zero bias is mainly driven by only one eigenchannel. The substitutions constrain the energies in which the probability of electronic transmission is significant. The results suggest that the conductance at zero bias is dependent on the nature of the employed substituent. The eigenchannel wave functions show that the central molecules are preferentially coupled with right electrode. The calculated molecular projected self-consistent hamiltonian states also suggest that there is a dependence of the conductance at zero bias with the nature of the employed substituent. The current-voltage analyses suggest that the negative differential resistance effect is present in ruthenophanes, but it is dependent on both the nature of the substituent and the bias. Despite the moderate rectification ratio of the ruthenophanes, they present non-ohmic behaviour, indicating that they can be used as potential candidates in electronic molecular devices such as switches, oscillators, and frequency multipliers.

  6. Unique membrane properties and enhanced signal processing in human neocortical neurons

    Science.gov (United States)

    Eyal, Guy; Verhoog, Matthijs B; Testa-Silva, Guilherme; Deitcher, Yair; Lodder, Johannes C; Benavides-Piccione, Ruth; Morales, Juan; DeFelipe, Javier; de Kock, Christiaan PJ; Mansvelder, Huibert D; Segev, Idan

    2016-01-01

    The advanced cognitive capabilities of the human brain are often attributed to our recently evolved neocortex. However, it is not known whether the basic building blocks of the human neocortex, the pyramidal neurons, possess unique biophysical properties that might impact on cortical computations. Here we show that layer 2/3 pyramidal neurons from human temporal cortex (HL2/3 PCs) have a specific membrane capacitance (Cm) of ~0.5 µF/cm2, half of the commonly accepted 'universal' value (~1 µF/cm2) for biological membranes. This finding was predicted by fitting in vitro voltage transients to theoretical transients then validated by direct measurement of Cm in nucleated patch experiments. Models of 3D reconstructed HL2/3 PCs demonstrated that such low Cm value significantly enhances both synaptic charge-transfer from dendrites to soma and spike propagation along the axon. This is the first demonstration that human cortical neurons have distinctive membrane properties, suggesting important implications for signal processing in human neocortex. DOI: http://dx.doi.org/10.7554/eLife.16553.001 PMID:27710767

  7. Unique Bonding Properties of the Au36(SR)24 Nanocluster with FCC-Like Core.

    Science.gov (United States)

    Chevrier, Daniel M; Chatt, Amares; Zhang, Peng; Zeng, Chenjie; Jin, Rongchao

    2013-10-03

    The recent discovery on the total structure of Au36(SR)24, which was converted from biicosahedral Au38(SR)24, represents a surprising finding of a face-centered cubic (FCC)-like core structure in small gold-thiolate nanoclusters. Prior to this finding, the FCC feature was only expected for larger (nano)crystalline gold. Herein, we report results on the unique bonding properties of Au36(SR)24 that are associated with its FCC-like core structure. Temperature-dependent X-ray absorption spectroscopy (XAS) measurements at the Au L3-edge, in association with ab initio calculations, show that the local structure and electronic behavior of Au36(SR)24 are of more molecule-like nature, whereas its icosahedral counterparts such as Au38(SR)24 and Au25(SR)18 are more metal-like. Moreover, site-specific S K-edge XAS studies indicate that the bridging motif for Au36(SR)24 has different bonding behavior from the staple motif from Au38(SR)24. Our findings highlight the important role of "pseudo"-Au4 units within the FCC-like Au28 core in interpreting the bonding properties of Au36(SR)24 and suggest that FCC-like structure in gold thiolate nanoclusters should be treated differently from its bulk counterpart.

  8. Design and Preparation of a Unique Segregated Double Network with Excellent Thermal Conductive Property.

    Science.gov (United States)

    Wu, Kai; Lei, Chuxin; Huang, Rui; Yang, Weixing; Chai, Songgang; Geng, Chengzhen; Chen, Feng; Fu, Qiang

    2017-03-01

    It is still a challenge to fabricate polymer-based composites with excellent thermal conductive property because of the well-known difficulties such as insufficient conductive pathways and inefficient filler-filler contact. To address this issue, a synergistic segregated double network by using two fillers with different dimensions has been designed and prepared by taking graphene nanoplates (GNPs) and multiwalled carbon nanotubes (MWCNT) in polystyrene for example. In this structure, GNPs form the segregated network to largely increase the filler-filler contact areas while MWCNT are embedded within the network to improve the network-density. The segregated network and the randomly dispersed hybrid network by using GNPs and MWCNT together were also prepared for comparison. It was found that the thermal conductivity of segregated double network can achieve almost 1.8-fold as high as that of the randomly dispersed hybrid network, and 2.2-fold as that of the segregated network. Meanwhile, much higher synergistic efficiency (f) of 2 can be obtained, even greater than that of other synergistic systems reported previously. The excellent thermal conductive property and higher f are ascribed to the unique effect of segregated double network: (1) extensive GNPs-GNPs contact areas via overlapped interconnections within segregated GNPs network; (2) efficient synergistic effect between MWCNT network and GNPs network based on bridge effect as well as increasing the network-density.

  9. Understanding the Unique Electronic Properties of Nano Structures Using Photoemission Theory.

    Science.gov (United States)

    Kwon, Soonnam; Choi, Won Kook

    2015-12-04

    Newly emerging experimental techniques such as nano-ARPES are expected to provide an opportunity to measure the electronic properties of nano-materials directly. However, the interpretation of the spectra is not simple because it must consider quantum mechanical effects related to the measurement process itself. Here, we demonstrate a novel approach that can overcome this problem by using an adequate simulation to corroborate the experimental results. Ab initio calculation on arbitrarily-shaped or chemically ornamented nano-structures is elaborately correlated to photoemission theory. This correlation can be directly exploited to interpret the experimental results. To test this method, a direct comparison was made between the calculation results and experimental results on highly-oriented pyrolytic graphite (HOPG). As a general extension, the unique electronic structures of nano-sized graphene oxide and features from the experimental result of black phosphorous (BP) are disclosed for the first time as supportive evidence of the usefulness of this method. This work pioneers an approach to intuitive and practical understanding of the electronic properties of nano-materials.

  10. Mouse Low-Grade Gliomas Contain Cancer Stem Cells with Unique Molecular and Functional Properties

    Directory of Open Access Journals (Sweden)

    Yi-Hsien Chen

    2015-03-01

    Full Text Available The availability of adult malignant glioma stem cells (GSCs has provided unprecedented opportunities to identify the mechanisms underlying treatment resistance. Unfortunately, there is a lack of comparable reagents for the study of pediatric low-grade glioma (LGG. Leveraging a neurofibromatosis 1 (Nf1 genetically engineered mouse LGG model, we report the isolation of CD133+ multi-potent low-grade glioma stem cells (LG-GSCs, which generate glioma-like lesions histologically similar to the parent tumor following injection into immunocompetent hosts. In addition, we demonstrate that these LG-GSCs harbor selective resistance to currently employed conventional and biologically targeted anti-cancer agents, which reflect the acquisition of new targetable signaling pathway abnormalities. Using transcriptomic analysis to identify additional molecular properties, we discovered that mouse and human LG-GSCs harbor high levels of Abcg1 expression critical for protecting against ER-stress-induced mouse LG-GSC apoptosis. Collectively, these findings establish that LGG cancer stem cells have unique molecular and functional properties relevant to brain cancer treatment.

  11. Transport properties of doped BICUVOX ceramics

    Directory of Open Access Journals (Sweden)

    Yaremchenko, A. A.

    1999-12-01

    Full Text Available Polycrystalline Bi2-xLaxV0.90Cu0.10O5.5-δ (x = 0, 0.10 and 0.20 and Bi1.90Pr0.10V0.90Cu0.10O5.5-δ were prepared by the standard ceramic- synthesis technique. The total electrical conductivity of Bi1.90La0.10V0.90Cu0.10O5.5-δ at temperatures above 500 K is slightly lower than undoped BICUVOX.10, but transport properties in the temperature range 370 - 450 K are similar. Doping BICUVOX. 10 with praseodymium led to the formation of impurity phases, and to both lower conductivity and thermal expansion of ceramic samples. Oxygen-ion transference numbers of phases with moderate rare-earth dopant content (x ≤ 0.10 vary in the range 0.90 - 0.99 at 780 - 910 K and decrease with increasing temperature. Thermal expansion coefficients calculated from the dilatometric data for Bi2-xLnxV0.90Cu0.10O5.5-δ ceramics are (16.1 - 18.0 x 10-6 K-1 at 730 - 1050 K.

    Bi2-xLaxV0.90Cu0.10O5.5-δ (x = 0, 0.10 and 0.20 y Bi1.90Pr0.10V0.90Cu0.10O5.5-δ policristalinos fueron preparados por síntesis cerámica convencional. La conductividad eléctrica total de Bi2-xLaxV0.90Cu0.10O5.5-δ a temperaturas superiores a 500K es ligeramente menor que la correspondiente a BICUVOX.10 no dopada, pero las propiedades de transporte en el rango de temperaturas 370- 450K son similares. Dopando BICUVOX.10 con praseodimio produce la formación de fases secundarias y la reducción de la conductividad y la expansión térmica de las muestras cerámicas. El número de transporte del ión sin oxígeno de fases con un contenido en tierra rara moderado como dopante (x ≤ 0.10 varía en el rango 0.90-0.99 a 780-910k y disminuye con el aumento de la temperatura. Los coeficientes de expansión térmicos calculados a partir de los datos dilatométricos para cerámicas Bi2-xLnxV0.90Cu0.10O5.5-δ son (16.1 - 18.0 x 10-6 K-1 a 730 - 1050 K.

  12. Transport properties of graphene and its application

    Science.gov (United States)

    Lu, Jianming

    This thesis focuses on the transport properties of graphene, a new emerging atomically thin, two-dimensional material, with and without the application of a magnetic field. Because of its high mobility, graphene is a promising candidate for Extraordinary Magnetoresistance (EMR) devices. The magnetoresistance of an EMR device arises mainly from its geometry rather than the intrinsic response of the material itself to an applied magnetic field. As a result, the geometric parameters play an important role in its performance. Experiments employing various combinations of geometric parameters and graphene of different quality levels were conducted to determine the optimal results. We found that the optimized parameters vary for different applied magnetic fields. In a magnetic field of 9 Tesla, magnetoresistance up to 55,000% was observed. In addition, Finite Element Analysis (FEA) simulations are used to complement the experiments and explain the measured magnetoresistance. The excellent agreement between the simulations and experimental results indicates that theoretical simulation can be used as a convenient method to explore EMR devices with alternative geometries or materials. The anomalous quantum Hall effect is one of the most exciting properties of graphene. The observation of the v=0 state above a critical magnetic field is closely related to the quality of the graphene, where a higher quality reduces the critical field needed. With our high quality graphene sample, the critical field is reduced to 6.75 Tesla. Moreover, from 6.75 T to 9T, the resistance at the cross point of the metal-insulator transition (MIT) is very close to h/2e2, which resembles the case of a disordered two-dimensional electron gas (2DEG) and may indicate a similar physical mechanism. In addition to the magnetotransport measurements, the current saturation of graphene in a high electric field is studied both theoretically and experimentally. This thesis focuses primarily on bilayer graphene

  13. Transport properties and Stokes-Einstein relation in Al-rich liquid alloys

    Science.gov (United States)

    Jakse, N.; Pasturel, A.

    2016-06-01

    We use ab initio molecular dynamics simulations to study the transport properties and the validity of the Stokes-Einstein relation in Al-rich liquid alloys with Ni, Cu, and Zn as alloying elements. First, we show that the composition and temperature dependence of their transport properties present different behaviors, which can be related to their local structural ordering. Then, we evidence that the competition between the local icosahedral ordering and the local chemical ordering may cause the breakdown of the Stokes-Einstein relation even in the liquid phase. We demonstrate that this breakdown can be captured by entropy-scaling relationships developed by Rosenfeld and using the two-body excess entropy. Our findings provide a unique framework to study the relation between structure, thermodynamics, and dynamics in metallic melts and pave the way towards the explanation of various complex transport properties in metallic melts.

  14. Electronic, transport, and magnetic properties of punctured carbon nanotubes

    Science.gov (United States)

    dos Santos, Jeová Calisto; de Vasconcelos, Fabrício Morais; de Aguiar, Acrísio Lins; Alves, Tayroni Francisco de Alencar; Meunier, Vincent; Girão, Eduardo Costa

    2016-12-01

    We use a spin-polarized tight-binding model Hamiltonian and the Landauer transport formalism to investigate the electronic transport properties of carbon nanotubes where different types of holes have been drilled through their sidewalls. We focus on zigzag edged defects with different atomic configurations since these systems enable the emergence of magnetic properties. We show that a number of hole geometries, magnetic states, and electronic spins yield attractive transport properties, such as ON/OFF switching for the electronic current, and nontrivial dependence of transmission with hole size.

  15. Transport properties site descriptive model. Guidelines for evaluation and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berglund, Sten [WSP Environmental, Stockholm (Sweden); Selroos, Jan-Olof [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

    2004-04-01

    This report describes a strategy for the development of Transport Properties Site Descriptive Models within the SKB Site Investigation programme. Similar reports have been produced for the other disciplines in the site descriptive modelling (Geology, Hydrogeology, Hydrogeochemistry, Rock mechanics, Thermal properties, and Surface ecosystems). These reports are intended to guide the site descriptive modelling, but also to provide the authorities with an overview of modelling work that will be performed. The site descriptive modelling of transport properties is presented in this report and in the associated 'Strategy for the use of laboratory methods in the site investigations programme for the transport properties of the rock', which describes laboratory measurements and data evaluations. Specifically, the objectives of the present report are to: Present a description that gives an overview of the strategy for developing Site Descriptive Models, and which sets the transport modelling into this general context. Provide a structure for developing Transport Properties Site Descriptive Models that facilitates efficient modelling and comparisons between different sites. Provide guidelines on specific modelling issues where methodological consistency is judged to be of special importance, or where there is no general consensus on the modelling approach. The objectives of the site descriptive modelling process and the resulting Transport Properties Site Descriptive Models are to: Provide transport parameters for Safety Assessment. Describe the geoscientific basis for the transport model, including the qualitative and quantitative data that are of importance for the assessment of uncertainties and confidence in the transport description, and for the understanding of the processes at the sites. Provide transport parameters for use within other discipline-specific programmes. Contribute to the integrated evaluation of the investigated sites. The site descriptive

  16. Type II skeletal myofibers possess unique properties that potentiate mitochondrial H(2)O(2) generation.

    Science.gov (United States)

    Anderson, Ethan J; Neufer, P Darrell

    2006-03-01

    Mitochondrial dysfunction is implicated in a number of skeletal muscle pathologies, most notably aging-induced atrophy and loss of type II myofibers. Although oxygen-derived free radicals are thought to be a primary cause of mitochondrial dysfunction, the underlying factors governing mitochondrial superoxide production in different skeletal myofiber types is unknown. Using a novel in situ approach to measure H(2)O(2) production (indicator of superoxide formation) in permeabilized rat skeletal muscle fiber bundles, we found that mitochondrial free radical leak (H(2)O(2) produced/O(2) consumed) is two- to threefold higher (P < 0.05) in white (WG, primarily type IIB fibers) than in red (RG, type IIA) gastrocnemius or soleus (type I) myofibers during basal respiration supported by complex I (pyruvate + malate) or complex II (succinate) substrates. In the presence of respiratory inhibitors, maximal rates of superoxide produced at both complex I and complex III are markedly higher in RG and WG than in soleus muscle despite approximately 50% less mitochondrial content in WG myofibers. Duplicate experiments conducted with +/-exogenous superoxide dismutase revealed striking differences in the topology and/or dismutation of superoxide in WG vs. soleus and RG muscle. When normalized for mitochondrial content, overall H(2)O(2) scavenging capacity is lower in RG and WG fibers, whereas glutathione peroxidase activity, which is largely responsible for H(2)O(2) removal in mitochondria, is similar in all three muscle types. These findings suggest that type II myofibers, particularly type IIB, possess unique properties that potentiate mitochondrial superoxide production and/or release, providing a potential mechanism for the heterogeneous development of mitochondrial dysfunction in skeletal muscle.

  17. KCTD Hetero-oligomers Confer Unique Kinetic Properties on Hippocampal GABAB Receptor-Induced K+ Currents.

    Science.gov (United States)

    Fritzius, Thorsten; Turecek, Rostislav; Seddik, Riad; Kobayashi, Hiroyuki; Tiao, Jim; Rem, Pascal D; Metz, Michaela; Kralikova, Michaela; Bouvier, Michel; Gassmann, Martin; Bettler, Bernhard

    2017-02-01

    GABAB receptors are the G-protein coupled receptors for the main inhibitory neurotransmitter in the brain, GABA. GABAB receptors were shown to associate with homo-oligomers of auxiliary KCTD8, KCTD12, KCTD12b, and KCTD16 subunits (named after their T1 K(+)-channel tetramerization domain) that regulate G-protein signaling of the receptor. Here we provide evidence that GABAB receptors also associate with hetero-oligomers of KCTD subunits. Coimmunoprecipitation experiments indicate that two-thirds of the KCTD16 proteins in the hippocampus of adult mice associate with KCTD12. We show that the KCTD proteins hetero-oligomerize through self-interacting T1 and H1 homology domains. Bioluminescence resonance energy transfer measurements in live cells reveal that KCTD12/KCTD16 hetero-oligomers associate with both the receptor and the G-protein. Electrophysiological experiments demonstrate that KCTD12/KCTD16 hetero-oligomers impart unique kinetic properties on G-protein-activated Kir3 currents. During prolonged receptor activation (one min) KCTD12/KCTD16 hetero-oligomers produce moderately desensitizing fast deactivating K(+) currents, whereas KCTD12 and KCTD16 homo-oligomers produce strongly desensitizing fast deactivating currents and nondesensitizing slowly deactivating currents, respectively. During short activation (2 s) KCTD12/KCTD16 hetero-oligomers produce nondesensitizing slowly deactivating currents. Electrophysiological recordings from hippocampal neurons of KCTD knock-out mice are consistent with these findings and indicate that KCTD12/KCTD16 hetero-oligomers increase the duration of slow IPSCs. In summary, our data demonstrate that simultaneous assembly of distinct KCTDs at the receptor increases the molecular and functional repertoire of native GABAB receptors and modulates physiologically induced K(+) current responses in the hippocampus.

  18. Transport Properties of some Conducting TCNQ-Salts

    DEFF Research Database (Denmark)

    Mortensen, Kell; Jacobsen, C. S.; Andersen, J. R.

    1979-01-01

    An experimental decomposition of the transport properties for organic transfer salts is attempted on the basis of conductivity and thermopower measurements. A decomposition is proposed on the compound: TMTSF-DMTCNQ. Furthermore some new transport data on the organic low-temperature conductor: HMT...

  19. Computer program for calculating thermodynamic and transport properties of fluids

    Science.gov (United States)

    Hendricks, R. C.; Braon, A. K.; Peller, I. C.

    1975-01-01

    Computer code has been developed to provide thermodynamic and transport properties of liquid argon, carbon dioxide, carbon monoxide, fluorine, helium, methane, neon, nitrogen, oxygen, and parahydrogen. Equation of state and transport coefficients are updated and other fluids added as new material becomes available.

  20. Molecular properties of bacterial multidrug transporters

    NARCIS (Netherlands)

    Putman, M; van Veen, HW; Konings, WN

    2000-01-01

    One of the mechanisms that bacteria utilize to evade the toxic effects of antibiotics is the active extrusion of structurally unrelated drugs from the cell. Both intrinsic and acquired multidrug transporters play an important role in antibiotic resistance of several pathogens, including Neisseria go

  1. Transport properties and nanosensors of oxide nanowires and nanobelts

    Science.gov (United States)

    Lao, Changshi

    ZnO is one of the most important materials for electronics, optoelectronics, piezoelectricity and optics. With a wide band gap of 3.37eV and an exiton binding energy of 60meV, ZnO ID nanostructures exhibit promising properties in a lot of optical device applications. It is also an important piezoelectric material and has applications in a new category of nanodevices, nano-piezotronics. Demonstrated prototype of devices includes nanogenerators, piezoelectric-FET, and a series of evolutive devices based on the concept of nanogenerator. This is based on working principle of a semiconductor and piezoelectric coupled property. This thesis is about the growth, characterization and device fabrication of ZnO nanowires and nanobelts for sensors and UV detectors. First, the fundamental synthesis of ZnO nanostructurs is investigated, particularly polar surface dominated nanostructues, to illustrate the unique growth configurations of ZnO nanobelts, nanorings and nanosprings. Detail study in this part includes nanobelts, nanorings, nanocombs, nanonetworks, and nanodiskettes synthesis. Important factors in driving the nanostructure synthesis mechanism are analyzed, such as the chemical activities of different surface of ZnO, the abundant of available Zn ions in the vapor, and the polar surface dominated effects. These factors contribute to the large abundant available ZnO nanostructures. Then, the devices fabricated methods using individual nanowires/nanobelts and their electrical transport properties were carefully characterized. In this part, dominant factors which are critical for nanobelt device performance are investigated, such as the contact properties, interface effects, and durability testing. Also, a metal doping method is studied to explore the controlling and modification of nanowire electric and optical properties. Research results obtained here provide a basic and thoroughly understanding the control process and fabrication criteria in building a functional

  2. Transport properties of nanoperforated Nb thin films

    Energy Technology Data Exchange (ETDEWEB)

    Trezza, M., E-mail: trezza@sa.infn.i [Laboratorio Regionale SuperMat, CNR-INFM Salerno and Dipartimento di Fisica ' E. R. Caianiello' , Universita degli Studi di Salerno, Baronissi I-84081 (Italy); Cirillo, C. [Laboratorio Regionale SuperMat, CNR-INFM Salerno and Dipartimento di Fisica ' E. R. Caianiello' , Universita degli Studi di Salerno, Baronissi (Saudi Arabia) I-84081 (Italy); Prischepa, S.L. [State University of Informatics and RadioElectronics, P. Brovka Street 6, Minsk 220013 (Belarus); Attanasio, C. [Laboratorio Regionale SuperMat, CNR-INFM Salerno and Dipartimento di Fisica ' E. R. Caianiello' , Universita degli Studi di Salerno, Baronissi I-84081 (Italy)

    2010-10-01

    Porous silicon, obtained by electrochemical etching, has been used as a substrate for the growth of nanoperforated Nb thin films. The films, deposited by UHV magnetron sputtering, inherited from the Si substrates their structure, made of holes of 10 nm diameter and of 20 and 40 nm spacing, which provide an artificial pinning lattice. Commensurability effects between the Abrikosov vortex lattice and the artificial array of holes were investigated by transport measurements.

  3. Unique Nanoparticle Optical Properties Confound Fluorescent Based Assays Widely Employed in Their In Vitro Toxicity Screening and Ranking

    Science.gov (United States)

    Nanoparticles (NPs) are novel materials having at least one dimension less than 100 nm and display unique physicochemical properties due to their nanoscale size. An emphasis has been placed on developing high throughput screening (HTS) assays to characterize and rank the toxiciti...

  4. Unique Nanoparticle Properties Confound Fluorescent Based Assays Widely Employed in Their In Vitro Toxicity Testing and Ranking

    Science.gov (United States)

    Nanomaterials are a diverse collection of novel materials that exhibit at least one dimension less than 100 nm and display unique chemical and physical properties due to their nanoscale size. An emphasis has been put on developing high throughput screening (HTS) assays to charac...

  5. Physical transport properties of marine microplastic pollution

    Directory of Open Access Journals (Sweden)

    A. Ballent

    2012-12-01

    Full Text Available Given the complexity of quantitative collection, knowledge of the distribution of microplastic pollution in many regions of the world ocean is patchy, both spatially and temporally, especially for the subsurface environment. However, with knowledge of typical hydrodynamic behavior of waste plastic material, models predicting the dispersal of pelagic and benthic plastics from land sources into the ocean are possible. Here we investigate three aspects of plastic distribution and transport in European waters. Firstly, we assess patterns in the distribution of plastics found in fluvial strandlines of the North Sea and how distribution may be related to flow velocities and distance from source. Second, we model transport of non-buoyant preproduction pellets in the Nazaré Canyon of Portugal using the MOHID system after assessing the density, settling velocity, critical and depositional shear stress characteristics of such waste plastics. Thirdly, we investigate the effect of surface turbulences and high pressures on a range of marine plastic debris categories (various densities, degradation states and shapes tested in an experimental water column simulator tank and pressure laboratory. Plastics deposited on North Sea strandlines varied greatly spatially, as a function of material composition and distance from source. Model outputs indicated that such dense production pellets are likely transported up and down canyon as a function of tidal forces, with only very minor net down canyon movement. Behaviour of plastic fragments under turbulence varied greatly, with the dimensions of the material, as well as density, playing major determining roles. Pressure was shown to affect hydrodynamic behaviours of only low density foam plastics at pressures ≥ 60 bar.

  6. Physical transport properties of marine microplastic pollution

    Science.gov (United States)

    Ballent, A.; Purser, A.; Mendes, P. de Jesus; Pando, S.; Thomsen, L.

    2012-12-01

    Given the complexity of quantitative collection, knowledge of the distribution of microplastic pollution in many regions of the world ocean is patchy, both spatially and temporally, especially for the subsurface environment. However, with knowledge of typical hydrodynamic behavior of waste plastic material, models predicting the dispersal of pelagic and benthic plastics from land sources into the ocean are possible. Here we investigate three aspects of plastic distribution and transport in European waters. Firstly, we assess patterns in the distribution of plastics found in fluvial strandlines of the North Sea and how distribution may be related to flow velocities and distance from source. Second, we model transport of non-buoyant preproduction pellets in the Nazaré Canyon of Portugal using the MOHID system after assessing the density, settling velocity, critical and depositional shear stress characteristics of such waste plastics. Thirdly, we investigate the effect of surface turbulences and high pressures on a range of marine plastic debris categories (various densities, degradation states and shapes tested) in an experimental water column simulator tank and pressure laboratory. Plastics deposited on North Sea strandlines varied greatly spatially, as a function of material composition and distance from source. Model outputs indicated that such dense production pellets are likely transported up and down canyon as a function of tidal forces, with only very minor net down canyon movement. Behaviour of plastic fragments under turbulence varied greatly, with the dimensions of the material, as well as density, playing major determining roles. Pressure was shown to affect hydrodynamic behaviours of only low density foam plastics at pressures ≥ 60 bar.

  7. Statistical properties of transport in plasma turbulence

    DEFF Research Database (Denmark)

    Naulin, V.; Garcia, O.E.; Nielsen, A.H.;

    2004-01-01

    The statistical properties of the particle flux in different types of plasma turbulence models are numerically investigated using probability distribution functions (PDFs). The physics included in the models range from two-dimensional drift wave turbulence to three-dimensional MHD dynamics...

  8. Quantitative Analysis of Major Factors Affecting Black Carbon Transport and Concentrations in the Unique Atmospheric Structures of Urban Environment

    Science.gov (United States)

    Liang, Marissa Shuang

    combined contribution from both traffic and atmospheric circulation accounted for observed spatiotemporal variability in PM2.5 concentrations. Based on these experimental and quantitative analyses, a three-dimensional model is proposed for contaminant's transport in highly urbanized Cincinnati region. Furthermore this dissertation explored implications on roadside pollutant evaluation, and on the risk analysis of future fuel substitution using biodiesel. The Gaussian-type models are poor in determining the effective emission factor particularly under nocturnal thermal inversion for which the effective emission factor is a function of lapse rate in the morning. The Gaussian models are applicable in daytime after the breakdown of thermal inversion. Lastly, among three types of fuels examined, the proposed butanol-added biodiesel-diesel blend (D80B15Bu5) yielded a good compromise between black carbon and NOx emissions while maintaining proper combustion properties. It is also found that the emission contained less black carbon and had higher organic carbon (OC) and elemental (EC) ratio than tested petroleum diesel. As demonstrated in other parts of this study, the OC-enriched emission will likely affect the black carbon occurrence and PM concentrations in the urban environments. Overall, it is suggested that urban formation and biofuel usage define the environmental impacts of black carbon, and are the focus for climate change mitigation and adaptation.

  9. Transport properties of porous media from the microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Torquato, S. [Princeton Univ., NJ (United States)

    1995-12-31

    The determination of the effective transport properties of a random porous medium remains a challenging area of research because the properties depend on the microstructure in a highly complex fashion. This paper reviews recent theoretical and experimental progress that we have made on various aspects of this problem. A unified approach is taken to characterize the microstructure and the seemingly disparate properties of the medium.

  10. Stochastic functional differential equations with infinite delay: Existence and uniqueness of solutions, solution maps, Markov properties, and ergodicity

    Science.gov (United States)

    Wu, Fuke; Yin, George; Mei, Hongwei

    2017-02-01

    This work is devoted to stochastic functional differential equations (SFDEs) with infinite delay. First, existence and uniqueness of the solutions of such equations are examined. Because the solutions of the delay equations are not Markov, a viable alternative for studying further asymptotic properties is to use solution maps or segment processes. By examining solution maps, this work investigates the Markov properties as well as the strong Markov properties. Also obtained are adaptivity and continuity, mean-square boundedness, and convergence of solution maps from different initial data. This paper then examines the ergodicity of underlying processes and establishes existence of the invariant measure for SFDEs with infinite delay under suitable conditions.

  11. Unsaturated Zone and Saturated Zone Transport Properties (U0100)

    Energy Technology Data Exchange (ETDEWEB)

    J. Conca

    2000-12-20

    This Analysis/Model Report (AMR) summarizes transport properties for the lower unsaturated zone hydrogeologic units and the saturated zone at Yucca Mountain and provides a summary of data from the Busted Butte Unsaturated Zone Transport Test (UZTT). The purpose of this report is to summarize the sorption and transport knowledge relevant to flow and transport in the units below Yucca Mountain and to provide backup documentation for the sorption parameters decided upon for each rock type. Because of the complexity of processes such as sorption, and because of the lack of direct data for many conditions that may be relevant for Yucca Mountain, data from systems outside of Yucca Mountain are also included. The data reported in this AMR will be used in Total System Performance Assessment (TSPA) calculations and as general scientific support for various Process Model Reports (PMRs) requiring knowledge of the transport properties of different materials. This report provides, but is not limited to, sorption coefficients and other relevant thermodynamic and transport properties for the radioisotopes of concern, especially neptunium (Np), plutonium (Pu), Uranium (U), technetium (Tc), iodine (I), and selenium (Se). The unsaturated-zone (UZ) transport properties in the vitric Calico Hills (CHv) are discussed, as are colloidal transport data based on the Busted Butte UZTT, the saturated tuff, and alluvium. These values were determined through expert elicitation, direct measurements, and data analysis. The transport parameters include information on interactions of the fractures and matrix. In addition, core matrix permeability data from the Busted Butte UZTT are summarized by both percent alteration and dispersion.

  12. Magnetothermoelectric transport properties of multiterminal graphene nanoribbons

    Science.gov (United States)

    Wei, Miao-Miao; Zhang, Ying-Tao; Guo, Ai-Min; Liu, Jian-Jun; Xing, Yanxia; Sun, Qing-Feng

    2016-06-01

    The Peltier effect and the Ettingshausen effect are investigated in graphene nanoribbons, where charge current produces heat current along the longitudinal direction in the former case, and longitudinal charge current generates transverse heat current in the latter case. With the aid of the nonequilibrium Green's function and the Landauer-Büttiker formalism, the Peltier coefficient Πc and the Ettingshausen coefficient Ec are obtained. We found that the Kelvin relation is always valid for the longitudinal thermoelectric transport, i.e., Πc=T Sc , with T the temperature and Sc the Seebeck coefficient. In contrast, for transverse magnetothermoelectric transport, the Kelvin relation breaks down and Ec≠T Nc usually, with Nc the Nernst coefficient. In the region of weak magnetic field, the Ettingshausen effect depends strongly on device parameters. When the Fermi energy EF is close to the Dirac point, the Ettingshausen effect of the semiconducting armchair graphene nanoribbon is much stronger than that of the metallic one. When EF is far away from the Dirac point, the Ettingshausen coefficient Ec oscillates around zero. When under a strong magnetic field, Ec is independent of the device parameters and swells only near the Dirac point. Further, the dependence of Ec on EF can be scaled by EF/kBT , with a peak value of (2 ln2 ) kBT /e for the three-terminal system and (4/3 ln2 ) kBT /e for the four-terminal system. We also study the impact of disorder on the Ettingshausen effect. Regardless of the magnetic field strength, Ec is robust against moderate disorder scattering. In addition, in the strong magnetic field, Ec with additional regular oscillating structure can be caused by disorder.

  13. Unique functional properties of somatostatin-expressing GABAergic neurons in mouse barrel cortex.

    NARCIS (Netherlands)

    Gentet, L.J.; Kremer, Y.; Taniguchi, H.; Huang, Z.J.; Staiger, J.F.; Petersen, C.C.H.

    2012-01-01

    Neocortical GABAergic neurons have diverse molecular, structural and electrophysiological features, but the functional correlates of this diversity are largely unknown. We found unique membrane potential dynamics of somatostatin-expressing (SOM) neurons in layer 2/3 of the primary somatosensory

  14. Conical nanopore membranes. Preparation and transport properties.

    Science.gov (United States)

    Li, Naichao; Yu, Shufang; Harrell, C Chad; Martin, Charles R

    2004-04-01

    We have been investigating applications of nanopore membranes in analytical chemistry-specifically in membrane-based bioseparations, in electroanalytical chemistry, and in the development of new approaches to biosensor design. Membranes that have conically shaped pores (as opposed to the more conventional cylindrical shape) may offer some advantages for these applications. We describe here a simple plasma-etch method that converts cylindrical nanopores in track-etched polymeric membranes into conically shaped pores. This method allows for control of the shape of the resulting conical nanopores. For example, the plasma-etched pores may be cylindrical through most of the membrane thickness blossoming into cones at one face of the membrane (trumpet-shaped), or they may be nearly perfect cones. The key advantage of the conical pore shape is a dramatic enhancement in the rate of transport through the membrane, relative to an analogous cylindrical pore membrane. We demonstrate this here by measuring the ionic resistances of the plasma-etched conical pore membranes.

  15. Transport properties of colossal magnetoresistive materials

    CERN Document Server

    Yates, K A

    2002-01-01

    A microwave technique was developed in order to test the validity of the hypothesis that the microwave transport of polycrystalline, optimally doped, colossal magnetoresistive materials was dominated by intragranular material. The microwave surface resistance at 9GHz was compared with dc resistivity and magnetisation to study the influence of yttrium doping on the grain boundary regions of bulk polycrystalline samples of La sub 0 sub . sub 7 sub - sub x Y sub x Ca sub 0 sub . sub 3 MnO sub 3. It was found that, within the grains, the addition of yttrium causes the activation energy above T sub p to increase. A phenomenological model was introduced to explain the data in terms of the difference in structure between the grain and grain boundary regions. The technique was also used to study the influence of deoxygenation on the grain boundary regions of bulk, polycrystalline, La sub 0 sub . sub 6 sub 7 Ca sub 0 sub . sub 3 sub 3 MnO sub 3. For samples interconnected porosity, low temperature (600 deg C), short a...

  16. Transport properties of a novel molecular rotor

    Science.gov (United States)

    Xue, Mei; Wang, K. L.; Kabehie, Sanaz; Zink, Jeffrey I.

    2008-03-01

    Rotary motion around a molecular axis has been controlled by electron transfer process and by photoexcitation. The basis of the motion is intramolecular rotation of a ligand (3,8-di-ethynyltrityl-1, 10-phenanthroline) around a copper axle. The asymmetric copper system is synthesized by immobilizing a ``stator'' to a silicon support. The ``rotator,'' 3,8-di-ethynyltrityl-1, 10-phenanthroline is complexed to the metal center, Cu (I) or Cu (II) serving as an ``axle''. The Cu (I) system structure is tetrahedral, but that of Cu (II) is square planar. The interconversion of the two provides the basis for controlled, rotational motion. Hysteresis is observed in the different region of the applied voltage for different stators. The peak of the bisP-Si shifts to the left compared to that of the phen-Si stator because of the larger energy gap of phen-Si. The energy states of the Cu (I) and Cu (II) are extracted from the transport measurement results.

  17. Exploiting Unique Structural and Functional Properties of Malarial Glycolytic Enzymes for Antimalarial Drug Development

    Directory of Open Access Journals (Sweden)

    Asrar Alam

    2014-01-01

    Full Text Available Metabolic enzymes have been known to carry out a variety of functions besides their normal housekeeping roles known as “moonlighting functions.” These functionalities arise from structural changes induced by posttranslational modifications and/or binding of interacting proteins. Glycolysis is the sole source of energy generation for malaria parasite Plasmodium falciparum, hence a potential pathway for therapeutic intervention. Crystal structures of several P. falciparum glycolytic enzymes have been solved, revealing that they exhibit unique structural differences from the respective host enzymes, which could be exploited for their selective targeting. In addition, these enzymes carry out many parasite-specific functions, which could be of potential interest to control parasite development and transmission. This review focuses on the moonlighting functions of P. falciparum glycolytic enzymes and unique structural differences and functional features of the parasite enzymes, which could be exploited for therapeutic and transmission blocking interventions against malaria.

  18. Exploiting Unique Structural and Functional Properties of Malarial Glycolytic Enzymes for Antimalarial Drug Development

    Science.gov (United States)

    Neyaz, Md. Kausar; Ikramul Hasan, Syed

    2014-01-01

    Metabolic enzymes have been known to carry out a variety of functions besides their normal housekeeping roles known as “moonlighting functions.” These functionalities arise from structural changes induced by posttranslational modifications and/or binding of interacting proteins. Glycolysis is the sole source of energy generation for malaria parasite Plasmodium falciparum, hence a potential pathway for therapeutic intervention. Crystal structures of several P. falciparum glycolytic enzymes have been solved, revealing that they exhibit unique structural differences from the respective host enzymes, which could be exploited for their selective targeting. In addition, these enzymes carry out many parasite-specific functions, which could be of potential interest to control parasite development and transmission. This review focuses on the moonlighting functions of P. falciparum glycolytic enzymes and unique structural differences and functional features of the parasite enzymes, which could be exploited for therapeutic and transmission blocking interventions against malaria. PMID:25580350

  19. Industrial Requirements for Thermodynamics and Transport Properties

    DEFF Research Database (Denmark)

    Hendriks, Eric; Kontogeorgis, Georgios; Dohrn, Ralf

    2010-01-01

    . The main results are as follows. There is (still) an acute need for accurate, reliable, and thermodynamically consistent experimental data. Quality is more important than quantity. Similarly, there is a great need for reliable predictive, rather than correlative, models covering a wide range...... addressed to or written by industrial colleagues, are discussed initially. This provides the context of the survey and material with which the results of the survey can be compared. The results of the survey have been divided into the themes: data, models, systems, properties, education, and collaboration...... reactive systems (simultaneous chemical and physical equilibrium). Education in thermodynamics is perceived as key, for the future application of thermodynamics in the industry. A number of suggestions for improvement were made at all three levels (undergraduate, postgraduate, and professional development...

  20. Weak-strong uniqueness property for the full Navier-Stokes-Fourier system

    CERN Document Server

    Feireisl, Eduard

    2011-01-01

    The Navier-Stokes-Fourier system describing the motion of a compressible, viscous, and heat conducting fluid is known to possess global-in-time weak solutions for any initial data of finite energy. We show that a weak solution coincides with the strong solution, emanating from the same initial data, as long as the latter exists. In particular, strong solutions are unique within the class of weak solutions.

  1. Electronic Transport Properties of (7,0) Semiconducting Carbon Nanotube

    Institute of Scientific and Technical Information of China (English)

    SONG Jiu-Xu; YANG Yin-Wang; CHAI Chang-Chun; LIU Hong-Xia; DING Rui-Xue

    2008-01-01

    Electronic transport properties of a finite (7,0) carbon nanotube (CNT) coupled to Au (111) surfaces are investigated with a fully nonequilibrium Green's functions method combined with the density functional theory. The results show that the coupling effect between the CNT and Au electrode plays an important role in the transport properties, which leads to the formation of a high plateau in the transmission spectrum around Fermi energy. In addition, the current-voltage characteristic of the (7,0) CNT coupled to Au electrodes is different from an isolated (7,0) CNT.

  2. Prediction of transport and other physical properties of fluids

    CERN Document Server

    Bretsznajder, S

    1971-01-01

    Prediction of Transport and Other Physical Properties of Fluids reviews general methods for predicting the transport and other physical properties of fluids such as gases and liquids. Topics covered range from the theory of corresponding states and methods for estimating the surface tension of liquids to some basic concepts of the kinetic theory of gases. Methods of estimating liquid viscosity based on the principle of additivity are also described. This volume is comprised of eight chapters and opens by presenting basic information on gases and liquids as well as intermolecular forces and con

  3. Quantum-walk transport properties on graphene structures

    Science.gov (United States)

    Bougroura, Hamza; Aissaoui, Habib; Chancellor, Nicholas; Kendon, Viv

    2016-12-01

    We present numerical studies of quantum walks on C60 and related graphene structures to investigate their transport properties. Also known as a honeycomb lattice, the lattice formed by carbon atoms in the graphene phase can be rolled up to form nanotubes of various dimensions. Graphene nanotubes have many important applications, some of which rely on their unusual electrical conductivity and related properties. Quantum walks on graphs provide an abstract setting in which to study such transport properties independent of the other chemical and physical properties of a physical substance. They can thus be used to further the understanding of mechanisms behind such properties. We find that nanotube structures are significantly more efficient in transporting a quantum walk than cycles of equivalent size, provided the symmetry of the structure is respected in how they are used. We find faster transport on zigzag nanotubes compared to armchair nanotubes, which is unexpected given that for the actual materials the armchair nanotube is metallic, while the zigzag is semiconducting.

  4. Unique Medicinal Properties of Withania somnifera: Phytochemical Constituents and Protein Component.

    Science.gov (United States)

    Dar, Parvaiz A; Singh, Laishram R; Kamal, Mohammad A; Dar, Tanveer A

    2016-01-01

    Withania somnifera is an important medicinal herb that has been widely used for the treatment of different clinical conditions. The overall medicinal properties of Withania somnifera make it a viable therapeutic agent for addressing anxiety, cancer, microbial infection, immunomodulation, and neurodegenerative disorders. Biochemical constituents of Withania somnifera like withanolideA, withanolide D, withaferin A and withaniamides play an important role in its pharmacological properties. Proteins like Withania somnifera glycoprotein and withania lectin like-protein possess potent therapeutic properties like antimicrobial, anti-snake venom poison and antimicrobial. In this review, we have tried to present different pharmacological properties associated with different extract preparations, phytochemical constituents and protein component of Withania somnifera. Future insights in this direction have also been highlighted.

  5. Unique antitumor property of the Mg-Ca-Sr alloys with addition of Zn.

    Science.gov (United States)

    Wu, Yuanhao; He, Guanping; Zhang, Yu; Liu, Yang; Li, Mei; Wang, Xiaolan; Li, Nan; Li, Kang; Zheng, Guan; Zheng, Yufeng; Yin, Qingshui

    2016-02-24

    In clinical practice, tumor recurrence and metastasis after orthopedic prosthesis implantation is an intensely troublesome matter. Therefore, to develop implant materials with antitumor property is extremely necessary and meaningful. Magnesium (Mg) alloys possess superb biocompatibility, mechanical property and biodegradability in orthopedic applications. However, whether they possess antitumor property had seldom been reported. In recent years, it showed that zinc (Zn) not only promote the osteogenic activity but also exhibit good antitumor property. In our present study, Zn was selected as an alloying element for the Mg-1Ca-0.5Sr alloy to develop a multifunctional material with antitumor property. We investigated the influence of the Mg-1Ca-0.5Sr-xZn (x = 0, 2, 4, 6 wt%) alloys extracts on the proliferation rate, cell apoptosis, migration and invasion of the U2OS cell line. Our results show that Zn containing Mg alloys extracts inhibit the cell proliferation by alteration the cell cycle and inducing cell apoptosis via the activation of the mitochondria pathway. The cell migration and invasion property were also suppressed by the activation of MAPK (mitogen-activated protein kinase) pathway. Our work suggests that the Mg-1Ca-0.5Sr-6Zn alloy is expected to be a promising orthopedic implant in osteosarcoma limb-salvage surgery for avoiding tumor recurrence and metastasis.

  6. Properties of an affine transport equation and its holonomy

    Science.gov (United States)

    Vines, Justin; Nichols, David A.

    2016-10-01

    An affine transport equation was used recently to study properties of angular momentum and gravitational-wave memory effects in general relativity. In this paper, we investigate local properties of this transport equation in greater detail. Associated with this transport equation is a map between the tangent spaces at two points on a curve. This map consists of a homogeneous (linear) part given by the parallel transport map along the curve plus an inhomogeneous part, which is related to the development of a curve in a manifold into an affine tangent space. For closed curves, the affine transport equation defines a "generalized holonomy" that takes the form of an affine map on the tangent space. We explore the local properties of this generalized holonomy by using covariant bitensor methods to compute the generalized holonomy around geodesic polygon loops. We focus on triangles and "parallelogramoids" with sides formed from geodesic segments. For small loops, we recover the well-known result for the leading-order linear holonomy (˜ Riemann × area), and we derive the leading-order inhomogeneous part of the generalized holonomy (˜ Riemann × area^{3/2}). Our bitensor methods let us naturally compute higher-order corrections to these leading results. These corrections reveal the form of the finite-size effects that enter into the holonomy for larger loops; they could also provide quantitative errors on the leading-order results for finite loops.

  7. Transport Properties of Carbon-Nanotube/Cement Composites

    NARCIS (Netherlands)

    Han, B.; Yang, Z.; Shi, X.; Yu, X.

    2012-01-01

    This paper preliminarily investigates the general transport properties (i.e., water sorptivity, water permeability, and gas permeability) of carbon-nanotube/cement composites. Carboxyl multi-walled carbon nanotubes (MWNTs) are dispersed into cement mortar to fabricate the carbon nanotubes (CNTs) rei

  8. Transport Properties of the Metallic State of TMTSF-DMTCNQ

    DEFF Research Database (Denmark)

    Bechgaard, Klaus; Andersen, Jan Rud; Andrieux, A.

    1979-01-01

    The authors report the transport properties (longitudinal and transverse conductivity, magnetoresistance and thermopower) of TMTSF-DMTCNQ for pressures up to 13 kbar and temperatures down to 1.2K together with the phase diagram which results from these measurements. The most striking results are ...

  9. Transport properties of the Fermi hard-sphere system

    CERN Document Server

    Mecca, Angela; Benhar, Omar; Polls, Artur

    2015-01-01

    The transport properties of neutron star matter play an important role in a variety of astrophysical processes. We report the results of a calculation of the shear viscosity and thermal conductivity coefficients of the hard-sphere fermion system of degeneracy $\

  10. Phase Structure and Transport Properties of Dense Quark Matter

    CERN Document Server

    Schaefer, Thomas

    2010-01-01

    We provide a summary of our current knowledge of the phase structure of very dense quark matter. We concentrate on the question how the ground state at asymptotically high density -- color-flavor-locked (CFL) matter -- is modified as the density is lowered. We discuss the nature of the quasi-particle excitations, and present work on the transport properties of dense QCD matter.

  11. Technological Support of Critical Parts for Railway Transport Working Properties

    Science.gov (United States)

    Gabets, A. V.; Gabets, D. A.; Markov, A. M.; Radchenko, M. V.; Leonov, S. L.

    2017-01-01

    The materials of complex research of operational properties of a new brand cast iron CHMN-35M. Optimal chemical composition was determined. The obtained results allow to conclude about possibility of its use for the manufacture of critical parts of rolling stock of railway transport, in particular of a side bearing cap

  12. Transport Properties of Metallic Ruthenates: A DFT +DMFT Investigation

    Science.gov (United States)

    Deng, Xiaoyu; Haule, Kristjan; Kotliar, Gabriel

    2016-06-01

    We present a systematical theoretical study on the transport properties of an archetypal family of Hund's metals, Sr2RuO4 , Sr3 Ru2 O7 , SrRuO3 , and CaRuO3 , within the combination of first principles density functional theory and dynamical mean field theory. The agreement between theory and experiments for optical conductivity and resistivity is good, which indicates that electron-electron scattering dominates the transport of ruthenates. We demonstrate that in the single-site dynamical mean field approach the transport properties of Hund's metals fall into the scenario of "resilient quasiparticles." We explain why the single layered compound Sr2 RuO4 has a relative weak correlation with respect to its siblings, which corroborates its good metallicity.

  13. Curcumolide, a unique sesquiterpenoid with anti-inflammatory properties from Curcuma wenyujin.

    Science.gov (United States)

    Dong, Jianyong; Shao, Weiwei; Yan, Pengcheng; Cai, Xiaoqing; Fang, Lianglian; Zhao, Xiaowei; Lin, Weiwei; Cai, Yuan

    2015-01-15

    Curcumolide, a novel sesquiterpenoid with a unique 5/6/5 tricyclic skeleton, was isolated from Curcuma wenyujin. The structure and absolute configuration were elucidated by extensive NMR, ECD data analysis, and a single-crystal X-ray study. This molecule exhibited significant anti-inflammatory effects in LPS-induced RAW 264.7 macrophages. It suppressed LPS-induced NF-κB activation, including the nuclear translocation and DNA binding activity of NF-κB, and decreased tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), nitric oxide (NO) and reactive oxygen species (ROS) production. Therefore, Curcumolide may have therapeutic potential for treating inflammatory diseases by inhibiting NF-κB activation and pro-inflammatory mediator production. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Reaction of protein and carbohydrates with EDC for purpose of making products with unique functional properties

    Science.gov (United States)

    Prior research from this laboratory has demonstrated the feasibility of using chemical and enzymatic treatments on protein and carbohydrate waste products for the purpose of making fillers to enhance the properties of leather. These treatments (microbial transglutaminase, genipin, and polyphenols i...

  15. Metallic nanoparticles: microbial synthesis and unique properties for biotechnological applications, bioavailability and biotransformation

    NARCIS (Netherlands)

    Pereira, L.; Mehboob, F.; Stams, A.J.M.; Mota, M.M.; Rijnaarts, H.H.M.; Alves, M.M.

    2015-01-01

    The impact of nanotechnology in all areas of science and technology is evident. The expanding availability of a variety of nanostructures with properties in the nanometer size range has sparked widespread interest in their use in biotechnological systems, including the field of environmental remedia

  16. Transport properties of low-dimensional amorphous carbon films

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, Somnath [Nano-Electronics Centre, Advanced Technology Institute, School of Electronics and Physical Sciences, University of Surrey (United Kingdom)]. E-mail: s.bhattacharyya@surrey.ac.uk; Silva, S.R.P. [Nano-Electronics Centre, Advanced Technology Institute, School of Electronics and Physical Sciences, University of Surrey (United Kingdom)

    2005-06-22

    Research on amorphous carbon (a-C) to date has focused on the distinction between the sp{sup 2} and sp{sup 3} phases and understanding the properties on the basis of the sp{sup 2}-C bonded component. Recently, sufficient information on the sp{sup 2}-bonded clusters and nanoforms of carbon has helped to identify the importance of sp{sup 2}-C over sp{sup 3}-C, especially in transport properties and encouraged many groups to exploit this knowledge for device design. However, at present, few studies dedicated purely to understanding the transport properties and electronic structure of the family of a-C films as a whole is available. In this paper, we try to identify the key issues in using a-C as an unconventional semiconducting material and try to elaborate on how to overcome these hurdles in order to utilize this extremely versatile material for active device fabrication.

  17. A unique focusing property of a parabolic mirror for neutrons in the gravitational field: geometric proof

    CERN Document Server

    Masalovich, S

    2014-01-01

    An extraordinary focusing property of a parabolic mirror for ultracold neutrons in the presence of the gravitational field was first reported by A. Steyerl and co-authors. It was shown that all neutrons emitted from the focus of the mirror will be reflected back upon the same focus point passing, in between, a point of return in the gravitational field. The present note offers a complementary geometric proof of this feature and discusses some implications.

  18. Unique properties of halide perovskites as possible origins of the superior solar cell performance.

    Science.gov (United States)

    Yin, Wan-Jian; Shi, Tingting; Yan, Yanfa

    2014-07-16

    Halide perovskites solar cells have the potential to exhibit higher energy conversion efficiencies with ultrathin films than conventional thin-film solar cells based on CdTe, CuInSe2 , and Cu2 ZnSnSe4 . The superior solar-cell performance of halide perovskites may originate from its high optical absorption, comparable electron and hole effective mass, and electrically clean defect properties, including point defects and grain boundaries.

  19. Electronic properties of [core+exo]-type gold clusters: factors affecting the unique optical transitions.

    Science.gov (United States)

    Shichibu, Yukatsu; Konishi, Katsuaki

    2013-06-03

    Unusual visible absorption properties of [core+exo]-type Au6 (1), Au8 (2), and Au11 (3) clusters were studied from experimental and theoretical aspects, based on previously determined crystal structures. Unlike conventional core-only clusters having no exo gold atoms, these nonspherical clusters all showed an isolated visible absorption band in solution. Density functional theory (DFT) studies on corresponding nonphenyl models (1'-3') revealed that they had similar electronic structures with discrete highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) bands. The theoretical spectra generated by time-dependent DFT (TD-DFT) calculations agreed well with the experimentally measured properties of 1-3, allowing assignment of the characteristic visible bands to HOMO-LUMO transitions. The calculated HOMO-LUMO transition energies increased in the order Au11 exo gold atom, with the HOMO → LUMO transition occurring in the core → exo direction. The HOMO/LUMO distribution patterns of 1' and 3' were similar to each other but were markedly different from that of 2', which has longer core-to-exo distances. These findings showed that not only nuclearity (size) but also geometric structures have profound effects on electronic properties and optical transitions of the [core+exo]-type clusters.

  20. Kinetic theory of transport processes in partially ionized reactive plasma, II: Electron transport properties

    Science.gov (United States)

    Zhdanov, V. M.; Stepanenko, A. A.

    2016-11-01

    The previously obtained in (Zhdanov and Stepanenko, 2016) general transport equations for partially ionized reactive plasma are employed for analysis of electron transport properties in molecular and atomic plasmas. We account for both elastic and inelastic interaction channels of electrons with atoms and molecules of plasma and also the processes of electron impact ionization of neutral particles and three-body ion-electron recombination. The system of scalar transport equations for electrons is discussed and the expressions for non-equilibrium corrections to electron ionization and recombination rates and the diagonal part of the electron pressure tensor are derived. Special attention is paid to analysis of electron energy relaxation during collisions with plasma particles having internal degrees of freedom and the expression for the electron coefficient of inelastic energy losses is deduced. We also derive the expressions for electron vector and tensorial transport fluxes and the corresponding transport coefficients for partially ionized reactive plasma, which represent a generalization of the well-known results obtained by Devoto (1967). The results of numerical evaluation of contribution from electron inelastic collisions with neutral particles to electron transport properties are presented for a series of molecular and atomic gases.

  1. Charge carrier transport properties in layer structured hexagonal boron nitride

    Directory of Open Access Journals (Sweden)

    T. C. Doan

    2014-10-01

    Full Text Available Due to its large in-plane thermal conductivity, high temperature and chemical stability, large energy band gap (˜ 6.4 eV, hexagonal boron nitride (hBN has emerged as an important material for applications in deep ultraviolet photonic devices. Among the members of the III-nitride material system, hBN is the least studied and understood. The study of the electrical transport properties of hBN is of utmost importance with a view to realizing practical device applications. Wafer-scale hBN epilayers have been successfully synthesized by metal organic chemical deposition and their electrical transport properties have been probed by variable temperature Hall effect measurements. The results demonstrate that undoped hBN is a semiconductor exhibiting weak p-type at high temperatures (> 700 °K. The measured acceptor energy level is about 0.68 eV above the valence band. In contrast to the electrical transport properties of traditional III-nitride wide bandgap semiconductors, the temperature dependence of the hole mobility in hBN can be described by the form of μ ∝ (T/T0−α with α = 3.02, satisfying the two-dimensional (2D carrier transport limit dominated by the polar optical phonon scattering. This behavior is a direct consequence of the fact that hBN is a layer structured material. The optical phonon energy deduced from the temperature dependence of the hole mobility is ħω = 192 meV (or 1546 cm-1, which is consistent with values previously obtained using other techniques. The present results extend our understanding of the charge carrier transport properties beyond the traditional III-nitride semiconductors.

  2. Transport properties of the Fermi hard-sphere system

    Energy Technology Data Exchange (ETDEWEB)

    Mecca, Angela; Lovato, Alessandro; Benhar, Omar; Polls, Artur

    2016-03-01

    The transport properties of neutron star matter play an important role in many astrophysical processes. We report the results of a calculation of the shear viscosity and thermal conductivity coefficients of the hard-sphere fermion system of degeneracy ν = 2, that can be regarded as a model of pure neutron matter. Our approach is based on the effective interaction obtained from the formalism of correlated basis functions and the cluster expansion technique. The resulting transport coefficients show a strong sensitivity to the quasiparticle effective mass, reflecting the effect of second-order contributions to the self-energy that are not taken into account in nuclear matter studies available in the literature.

  3. Insect Cells Encode a Class II α-Mannosidase with Unique Properties*

    OpenAIRE

    Kawar, Ziad; Karaveg, Khanita; Moremen, Kelley W.; Jarvis, Donald L.

    2001-01-01

    Previously, we cloned and characterized an insect (Sf9) cell cDNA encoding a class II α-mannosidase with amino acid sequence and biochemical similarities to mammalian Golgi α-mannosidase II. Since then, it has been demonstrated that other mammalian class II α-mannosidases can participate in N-glycan processing. Thus, the present study was performed to evaluate the catalytic properties of the Sf9 class II α-mannosidase and to more clearly determine its relationship to mammalian Golgi α-mannosi...

  4. Unique chemical properties of metal-carbon bonds in metal-carboranyl and metal-carboryne complexes

    Institute of Scientific and Technical Information of China (English)

    QIU ZaoZao; XIE ZuoWei

    2009-01-01

    The metal-carbon bonds in metal-carboranyl and metal-carboryne complexes behave very differently from those in classical organometallic complexes. The unique electronic and steric properties of icosahedral carboranyl moiety make the M-C bond in metal-carboranyl complexes inert toward unsaturated molecules, and on the other hand, the sterically demanding carborane cage can induce unexpected C-C coupling reactions. The M-C bonds in metal-carboryne complexes are, however, active toward various kinds of unsaturated molecules and the reactivity patterns are dependent upon the electronic configurations of the metal ions. This account provides an overview of our recent work in this area.

  5. Unique chemical properties of metal-carbon bonds in metal-carboranyl and metal-carboryne complexes

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The metal-carbon bonds in metal-carboranyl and metal-carboryne complexes behave very differently from those in classical organometallic complexes. The unique electronic and steric properties of ico-sahedral carboranyl moiety make the M-C bond in metal-carboranyl complexes inert toward unsaturated molecules, and on the other hand, the sterically demanding carborane cage can induce unexpected C-C coupling reactions. The M-C bonds in metal-carboryne complexes are, however, active toward various kinds of unsaturated molecules and the reactivity patterns are dependent upon the electronic configurations of the metal ions. This account provides an overview of our recent work in this area.

  6. Modeling transport properties of inhomogeneous superconductor-metal composites

    Energy Technology Data Exchange (ETDEWEB)

    Borroto, A.; Altshuler, E., E-mail: ealtshuler@fisica.uh.cu [Superconductivity Laboratory and “Henri Poincarè” Group of Complex Systems, Physics Faculty-IMRE, University of Havana, 10400 Havana (Cuba); Del Río, L. [Superconductivity Laboratory and “Henri Poincarè” Group of Complex Systems, Physics Faculty-IMRE, University of Havana, 10400 Havana (Cuba); Physics Department, McGill University, Montreal, Quebec H3A 2T8 (Canada); Arronte, M. [BRALAX, S. de RL., Tampico, Tamaulipas (Mexico); Technological Laser Laboratory, IMRE, University of Havana, 10400 Havana (Cuba); Johansen, T. H. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo (Norway); Institute for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia)

    2014-11-17

    We propose a model for a superconductor-metal composite that allows to derive intrinsic transport properties of the superconducting phase based on 2D images of its cross section, and a minimal set of parameters. The method is tested experimentally by using, as model composite, a “transversal bridge” made on a Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+x} (BSCCO)-Ag multi-filamentary tape. It is shown that the approach allows to predict the measured I−〈E〉 curves of the filaments. In addition, one can determine the critical current anisotropy between the longitudinal and transverse directions of the Ag-BSCCO tape, and also of its superconducting filaments separately, which emphasizes the role of the morphology of the composite in the transport properties.

  7. Transport properties of boron nanotubes investigated by ab initio calculation

    Institute of Scientific and Technical Information of China (English)

    Guo Wei; Hu Yi-Bin; Zhang Yu-Yang; Du Shi-Xuan; Gao Hong-Jun

    2009-01-01

    We investigate atomic and electronic structures of boron nanotubes (BNTs) by using the density functional theory(DFT). The transport properties of BNTs with different diameters and chiralities are studied by the Keldysh nonequi-librium Green function (NEGF) method. It is found that the cohesive energies and conductances of BNTs decrease as their diameters decrease. It is more difficult to form (N, 0) tubes than (M, M) tubes when the diameters of the two kinds of tubes are comparable. However, the (N, 0) tubes have a higher conductance than the (M, M) tubes. When the BNTs are connected to gold electrodes, the coupling between the BNTs and the electrodes will affect the transport properties of tubes significantly.

  8. 1D-transport properties of single superconducting lead nanowires

    DEFF Research Database (Denmark)

    Michotte, S.; Mátéfi-Tempfli, Stefan; Piraux, L.

    2003-01-01

    We report on the transport properties of single superconducting lead nanowires grown by an electrodeposition technique, embedded in a nanoporous track-etched polymer membrane. The nanowires are granular, have uniform diameter of ̃40 nm and a very large aspect ratio (̃500). The diameter of the nan......We report on the transport properties of single superconducting lead nanowires grown by an electrodeposition technique, embedded in a nanoporous track-etched polymer membrane. The nanowires are granular, have uniform diameter of ̃40 nm and a very large aspect ratio (̃500). The diameter...... of the nanowire is small enough to ensure a 1D superconducting regime in a wide temperature range below T. The non-zero resistance in the superconducting state and its variation caused by fluctuations of the superconducting order parameter were measured versus temperature, magnetic field, and applied DC current...

  9. Transport properties of anyons in random topological environments

    Science.gov (United States)

    Zatloukal, V.; Lehman, L.; Singh, S.; Pachos, J. K.; Brennen, G. K.

    2014-10-01

    The quasi-one-dimensional transport of Abelian and non-Abelian anyons is studied in the presence of a random topological background. In particular, we consider the quantum walk of an anyon that braids around islands of randomly filled static anyons of the same type. Two distinct behaviors are identified. We analytically demonstrate that all types of Abelian anyons localize purely due to the statistical phases induced by their random anyonic environment. In contrast, we numerically show that non-Abelian Ising anyons do not localize. This is due to their entanglement with the anyonic environment, which effectively induces dephasing. Our study demonstrates that localization properties strongly depend on nonlocal topological interactions, and it provides a clear distinction in the transport properties of Abelian and non-Abelian anyons.

  10. Unique properties of eukaryote-type actin and profilin horizontally transferred to cyanobacteria.

    Directory of Open Access Journals (Sweden)

    Arthur Guljamow

    Full Text Available A eukaryote-type actin and its binding protein profilin encoded on a genomic island in the cyanobacterium Microcystis aeruginosa PCC 7806 co-localize to form a hollow, spherical enclosure occupying a considerable intracellular space as shown by in vivo fluorescence microscopy. Biochemical and biophysical characterization reveals key differences between these proteins and their eukaryotic homologs. Small-angle X-ray scattering shows that the actin assembles into elongated, filamentous polymers which can be visualized microscopically with fluorescent phalloidin. Whereas rabbit actin forms thin cylindrical filaments about 100 µm in length, cyanobacterial actin polymers resemble a ribbon, arrest polymerization at 5-10 µm and tend to form irregular multi-strand assemblies. While eukaryotic profilin is a specific actin monomer binding protein, cyanobacterial profilin shows the unprecedented property of decorating actin filaments. Electron micrographs show that cyanobacterial profilin stimulates actin filament bundling and stabilizes their lateral alignment into heteropolymeric sheets from which the observed hollow enclosure may be formed. We hypothesize that adaptation to the confined space of a bacterial cell devoid of binding proteins usually regulating actin polymerization in eukaryotes has driven the co-evolution of cyanobacterial actin and profilin, giving rise to an intracellular entity.

  11. Unique mechanical properties of nanostructured transparent MgAl2O4 ceramics.

    Science.gov (United States)

    Zhang, Jie; Lu, Tiecheng; Chang, Xianghui; Wei, Nian; Qi, Jianqi

    2013-06-01

    Nanoindentation tests were performed on nanostructured transparent magnesium aluminate (MgAl2O4) ceramics to determine their mechanical properties. These tests were carried out on samples at different applied loads ranging from 300 to 9,000 μN. The elastic recovery for nanostructured transparent MgAl2O4 ceramics at different applied loads was derived from the force-depth data. The results reveal a remarkable enhancement in plastic deformation as the applied load increases from 300 to 9,000 μN. After the nanoindetation tests, scanning probe microscope images show no cracking in nanostructured transparent MgAl2O4 ceramics, which confirms the absence of any cracks and fractures around the indentation. Interestingly, the flow of the material along the edges of indent impressions is clearly presented, which is attributed to the dislocation introduced. High-resolution transmission electron microscopy observation indicates the presence of dislocations along the grain boundary, suggesting that the generation and interaction of dislocations play an important role in the plastic deformation of nanostructured transparent ceramics. Finally, the experimentally measured hardness and Young's modulus, as derived from the load-displacement data, are as high as 31.7 and 314 GPa, respectively.

  12. Unique properties of eukaryote-type actin and profilin horizontally transferred to cyanobacteria.

    Science.gov (United States)

    Guljamow, Arthur; Delissen, Friedmar; Baumann, Otto; Thünemann, Andreas F; Dittmann, Elke

    2012-01-01

    A eukaryote-type actin and its binding protein profilin encoded on a genomic island in the cyanobacterium Microcystis aeruginosa PCC 7806 co-localize to form a hollow, spherical enclosure occupying a considerable intracellular space as shown by in vivo fluorescence microscopy. Biochemical and biophysical characterization reveals key differences between these proteins and their eukaryotic homologs. Small-angle X-ray scattering shows that the actin assembles into elongated, filamentous polymers which can be visualized microscopically with fluorescent phalloidin. Whereas rabbit actin forms thin cylindrical filaments about 100 µm in length, cyanobacterial actin polymers resemble a ribbon, arrest polymerization at 5-10 µm and tend to form irregular multi-strand assemblies. While eukaryotic profilin is a specific actin monomer binding protein, cyanobacterial profilin shows the unprecedented property of decorating actin filaments. Electron micrographs show that cyanobacterial profilin stimulates actin filament bundling and stabilizes their lateral alignment into heteropolymeric sheets from which the observed hollow enclosure may be formed. We hypothesize that adaptation to the confined space of a bacterial cell devoid of binding proteins usually regulating actin polymerization in eukaryotes has driven the co-evolution of cyanobacterial actin and profilin, giving rise to an intracellular entity.

  13. How van der Waals interactions determine the unique properties of water

    CERN Document Server

    Morawietz, Tobias; Dellago, Christoph; Behler, Jörg

    2016-01-01

    While the interactions between water molecules are dominated by strongly directional hydrogen bonds (HBs), it was recently proposed that relatively weak, isotropic van der Waals (vdW) forces are essential for understanding the properties of liquid water and ice. This insight was derived from ab initio computer simulations, which provide an unbiased description of water at the atomic level and yield information on the underlying molecular forces. However, the high computational cost of such simulations prevents the systematic investigation of the influence of vdW forces on the thermodynamic anomalies of water. Here we develop efficient ab initio-quality neural network potentials and use them to demonstrate that vdW interactions are crucial for the formation of water's density maximum and its negative volume of melting. Both phenomena can be explained by the flexibility of the HB network, which is the result of a delicate balance of weak vdW forces, causing e.g. a pronounced contraction of the second solvation ...

  14. Unique Organic Matter and Microbial Properties in the Rhizosphere of a Wetland Soil

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, Daniel I.; Xu, Chen; Huang, Shan; Lin, Youmin; Tolic, Nikola; Roscioli, Kristyn M.; Santschi, Peter H.; Jaffe, Peter R.

    2016-04-19

    Wetlands attenuate the migration of many contaminants through a wide range of biogeochemical reactions. Recent research has shown that the rhizosphere, the zone near plant roots, in wetlands is especially effective at promoting contaminant attenuation. The objective of this study was to compare the soil organic matter (OM) composition and microbial communities of a rhizosphere soil (primarily an oxidized environment) to that of the bulk wetland soil (primarily a reduced environment). The rhizosphere had elevated C, N, Mn, and Fe concentrations and total bacteria, including Anaeromyxobacter, counts (as identified by qPCR). Furthermore, the rhizosphere contained several organic molecules that were not identified in the nonrhizosphere soil (54% of the >2200 ESI-FTICR-MS identified compounds). The rhizosphere OM molecules generally had (1) greater overall molecular weights, (2) less aromaticity, (3) more carboxylate and N-containing COO functional groups, and (4) a greater hydrophilic character. These latter two OM properties typically promote metal binding. This study showed for the first time that not only the amount but also the molecular characteristics of OM in the rhizosphere may in part be responsible for the enhanced immobilization of contaminants in wetlands. These finding have implications on the stewardship and long-term management of contaminated wetlands

  15. Unique Properties of Core Shell Ag@Au Nanoparticles for the Aptasensing of Bacterial Cells

    Directory of Open Access Journals (Sweden)

    Ezat Hamidi-Asl

    2016-08-01

    Full Text Available In this article, it is shown that the efficiency of an electrochemical aptasensing device is influenced by the use of different nanoparticles (NPs such as gold nanoparticles (Au, silver nanoparticles (Ag, hollow gold nanospheres (HGN, hollow silver nanospheres (HSN, silver–gold core shell (Ag@Au, gold–silver core shell (Au@Ag, and silver–gold alloy nanoparticles (Ag/Au. Among these nanomaterials, Ag@Au core shell NPs are advantageous for aptasensing applications because the core improves the physical properties and the shell provides chemical stability and biocompatibility for the immobilization of aptamers. Self-assembly of the NPs on a cysteamine film at the surface of a carbon paste electrode is followed by the immobilization of thiolated aptamers at these nanoframes. The nanostructured (Ag@Au aptadevice for Escherichia coli as a target shows four times better performance in comparison to the response obtained at an aptamer modified planar gold electrode. A comparison with other (core shell NPs is performed by cyclic voltammetry and differential pulse voltammetry. Also, the selectivity of the aptasensor is investigated using other kinds of bacteria. The synthesized NPs and the morphology of the modified electrode are characterized by UV-Vis absorption spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis, and electrochemical impedance spectroscopy.

  16. Stability properties of elementary dynamic models of membrane transport.

    Science.gov (United States)

    Hernández, Julio A

    2003-01-01

    Living cells are characterized by their capacity to maintain a stable steady state. For instance, cells are able to conserve their volume, internal ionic composition and electrical potential difference across the plasma membrane within values compatible with the overall cell functions. The dynamics of these cellular variables is described by complex integrated models of membrane transport. Some clues for the understanding of the processes involved in global cellular homeostasis may be obtained by the study of the local stability properties of some partial cellular processes. As an example of this approach, I perform, in this study, the neighborhood stability analysis of some elementary integrated models of membrane transport. In essence, the models describe the rate of change of the intracellular concentration of a ligand subject to active and passive transport across the plasma membrane of an ideal cell. The ligand can be ionic or nonionic, and it can affect the cell volume or the plasma membrane potential. The fundamental finding of this study is that, within the physiological range, the steady states are asymptotically stable. This basic property is a necessary consequence of the general forms of the expressions employed to describe the active and passive fluxes of the transported ligand.

  17. Molecular Dynamics Simulation on thermodynamic Properties and Transport Coefficients

    Institute of Scientific and Technical Information of China (English)

    D.X.Xiong

    1996-01-01

    Moecular dynamics simulation (MDS) is used to study the thermodynamic properties and transport coefficients of an argon system with Lennend-Jones potential.The results on the velocity distribution,mean free path,mean collison time,specific heat and self0diffusion coefficient agree well with the existing theoretical /experimental data,It shows that molecular dynamics method is another bridge to connect microworld and macreoworld.

  18. Electronic transport properties of metallic single-walled carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    曹觉先; 颜晓红; 肖杨; 丁建文

    2003-01-01

    We have calculated the differential conductance of metallic carbon nanotubes by the scatter matrix method. It is found that the differential conductance of metallic nanotube-based devices oscillates as a function of the bias voltage between the two leads and the gate voltage. Oscillation period T is directly proportional to the reciprocal of nanotube length. In addition, we found that electronic transport properties are sensitive to variation of the length of the nanotube.

  19. Transport properties of CNT/oligosilane/CNT heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Yu, J. [College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150080 (China); Zhang, G.L., E-mail: zglhrb@163.com [College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150080 (China); Shang, Y.; Wang, K.D.; Zhang, H.; Sun, M.; Liu, B.; Zeng, T. [College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150080 (China)

    2013-02-01

    Combining the non-equilibrium Green's function formalism with density functional theory, the transport properties of nine CNT/oligosilane/CNT heterojunctions were systematically studied. We have found that the incorporation of oligosilane linkage to the carbon nanotube mouth could significantly tune the transport properties compared with the pure oligosilane and pure CNT. The P- and B-dopings upon the oligosilane moiety could not only enhance the conductivity but also give rise to multiple negative differential resistance behavior for the CNT/oligosilane/CNT heterojunctions. The concentration of heteroatom plays an important role in the transport properties of the CNT/oligosilane/CNT heterojunctions, while the number of the oligosilane linkage exerts little effect on the conductivity. The B-doped CNT/oligosilane/CNT heterojunctions show higher conductivity than those of the P-doped ones. The p-n junction caused by B- and P-codopings exhibits a rectifying effect and the rectification ratio is up to 7.19.

  20. Native isolate of Trichoderma: a biocontrol agent with unique stress tolerance properties.

    Science.gov (United States)

    Mishra, N; Khan, S S; Sundari, S Krishna

    2016-08-01

    Species of Trichoderma are widely recognized for their biocontrol abilities, but seldom studied collectively, for their plant growth promotion, abiotic stress tolerance and bioremediation properties. Our study is a concentrated effort to establish the potential of native isolate Trichoderma harzianum KSNM (T103) to tolerate biotic (root pathogens) and abiotic stresses [high salt (100-1000 mM); heavy metal (chromium, nickel and zinc: 1-10 mM); pesticides: malathion (100-600 ppm), carbofuran (100-600 ppb)], along with its ability to support plant growth. In vitro growth promotion assays with T103 treated Vigna radiata, Vigna mungo and Hordeum vulgare confirmed 'non-species specific' growth promotion effects of T103. At lower metal concentration, T103 treatment was found to completely negate the impact of metal stress [60 % increase in radicle length (RL) with no significant decrease in %germination (%G)]. Even at 10 mM metal, T103 inoculation gave 80 % increase in %G and >50 % increase in RL. In vitro experiments confirmed high metal reduction capacity (47 %-Cr, 35 %-Ni and 42 %-Zn) of T103 at concentrations as high as 4 mM. At maximum residual concentrations of malathion (440 ppm) and carbofuran (100 ppb) reported in agricultural soils, T103 maintained 80 and 100 % survivability, respectively. T103 treatment has improved %G and RL in all three hosts challenged with pesticide. Isolate T103 was found to effectively suppress growth of three major root pathogens: Macrophomina phaseolina (65.83 %) followed by Sclerotium rolfsii (19.33 %) and Fusarium oxysporum (19.18 %). In the light of these observations, native T. harzianum (T103) seems to be a competent biocontrol agent for tropical agricultural soils contaminated with residual pesticides and heavy metals.

  1. Thermal Transport Properties of Dry Spun Carbon Nanotube Sheets

    Directory of Open Access Journals (Sweden)

    Heath E. Misak

    2016-01-01

    Full Text Available The thermal properties of carbon nanotube- (CNT- sheet were explored and compared to copper in this study. The CNT-sheet was made from dry spinning CNTs into a nonwoven sheet. This nonwoven CNT-sheet has anisotropic properties in in-plane and out-of-plane directions. The in-plane direction has much higher thermal conductivity than the out-of-plane direction. The in-plane thermal conductivity was found by thermal flash analysis, and the out-of-plane thermal conductivity was found by a hot disk method. The thermal irradiative properties were examined and compared to thermal transport theory. The CNT-sheet was heated in the vacuum and the temperature was measured with an IR Camera. The heat flux of CNT-sheet was compared to that of copper, and it was found that the CNT-sheet has significantly higher specific heat transfer properties compared to those of copper. CNT-sheet is a potential candidate to replace copper in thermal transport applications where weight is a primary concern such as in the automobile, aircraft, and space industries.

  2. Red cell properties after different modes of blood transportation

    Directory of Open Access Journals (Sweden)

    Asya Makhro

    2016-07-01

    Full Text Available Transportation of blood samples is unavoidable for assessment of specific parameters in blood of patients with rare anemias, blood doping testing or for research purposes. Despite the awareness that shipment may substantially alter multiple parameters, no study of that extend has been performed to assess these changes and optimize shipment conditions to reduce transportation-related artifacts. Here we investigate the changes in multiple parameters in blood of healthy donors over 72 hours of simulated shipment conditions. Three different anticoagulants (K3EDTA, Sodium Heparin and citrate-based CPDA for two temperatures (4oC and room temperature were tested to define the optimal transportation conditions. Parameters measured cover common cytology and biochemistry parameters (complete blood count, hematocrit, morphological examination, red blood cell (RBC volume, ion content and density, membrane properties and stability (hemolysis, osmotic fragility, membrane heat stability, patch-clamp investigations and formation of micro vesicles, Ca2+ handling, RBC metabolism, activity of numerous enzymes and O2 transport capacity. Our findings indicate that individual sets of parameter may require different shipment settings (anticoagulants, temperature. Most of the parameters except for ion (Na+, K+, Ca2+ handling and, possibly, reticulocytes counts, tend to favor transportation at 4oC. Whereas plasma and intraerythrocytic Ca2+ cannot be accurately measured in the presence of chelators such as citrate and EDTA, majority of Ca2+-dependent parameters are stabilized in CPDA samples. Even in blood samples from healthy donors transported using optimized shipment protocol the majority of parameters were stable within 24 hours, the condition that may not hold for the samples of patients with rare anemias. This implies for the as short as possible shipping using fast courier services to the closest expert laboratory at reach. Mobile laboratories or the travel of the

  3. Symmetry properties of macroscopic transport coefficients in porous media

    Science.gov (United States)

    Lasseux, D.; Valdés-Parada, F. J.

    2017-04-01

    We report on symmetry properties of tensorial effective transport coefficients characteristic of many transport phenomena in porous systems at the macroscopic scale. The effective coefficients in the macroscopic models (derived by upscaling (volume averaging) the governing equations at the underlying scale) are obtained from the solution of closure problems that allow passing the information from the lower to the upper scale. The symmetry properties of the macroscopic coefficients are identified from a formal analysis of the closure problems and this is illustrated for several different physical mechanisms, namely, one-phase flow in homogeneous porous media involving inertial effects, slip flow in the creeping regime, momentum transport in a fracture relying on the Reynolds model including slip effects, single-phase flow in heterogeneous porous media embedding a porous matrix and a clear fluid region, two-phase momentum transport in homogeneous porous media, as well as dispersive heat and mass transport. The results from the analysis of these study cases are summarized as follows. For inertial single-phase flow, the apparent permeability tensor is irreducibly decomposed into its symmetric (viscous) and skew-symmetric (inertial) parts; for creeping slip-flow, the apparent permeability tensor is not symmetric; for one-phase slightly compressible gas flow in the slip regime within a fracture, the effective transmissivity tensor is symmetric, a result that remains valid in the absence of slip; for creeping one-phase flow in heterogeneous media, the permeability tensor is symmetric; for two-phase flow, we found the dominant permeability tensors to be symmetric, whereas the coupling tensors do not exhibit any special symmetry property; finally for dispersive heat transfer, the thermal conductivity tensors include a symmetric and a skew-symmetric part, the latter being a consequence of convective transport only. A similar result is achieved for mass dispersion. Beyond the

  4. Influence of biofilms on transport properties in porous media

    Science.gov (United States)

    Davit, Y.

    2015-12-01

    Microbial activity and biofilm growth in porous media can drastically modify transport properties such as permeability, longitudinal and transverse dispersion or effective reaction rates. Understanding these effects has proven to be a considerable challenge. Advances in this field have been hindered by the difficulty of modeling and visualizing these multi-phase non-linear effects across a broad range of spatial and temporal scales. To address these issues, we are developing a strategy that combines imaging techniques based on x-ray micro-tomography with homogenization of pore-scale transport equations. Here, we review recent progress in x-ray imaging of biofilms in porous media, with a particular focus on the contrast agents that are used to differentiate between the fluid and biofilm phases. We further show how the 3D distribution of the different phases can be used to extract specific information about the biofilm and how effective properties can be calculated via the resolution of closure problems. These closure problems are obtained using the method of volume averaging and must be adapted to the problem of interest. In hydrological systems, we show that a generic formulation for reactive solute transport is based on a domain decomposition approach at the micro-scale yielding macro-scale models reminiscent of multi-rate mass transfer approaches.

  5. Transport properties of the rough hard sphere fluid.

    Science.gov (United States)

    Kravchenko, Olga; Thachuk, Mark

    2012-01-28

    Results are presented of a systematic study of the transport properties of the rough hard sphere fluid. The rough hard sphere fluid is a simple model consisting of spherical particles that exchange linear and angular momenta, and energy upon collision. This allows a study of the sole effect of particle rotation upon fluid properties. Molecular dynamics simulations have been used to conduct extensive benchmark calculations of self-diffusion, shear and bulk viscosity, and thermal conductivity coefficients. As well, the validity of several kinetic theory equations have been examined at various levels of approximation as a function of density and translational-rotational coupling. In particular, expressions from Enskog theory using different numbers of basis sets in the representation of the distribution function were tested. Generally Enskog theory performs well at low density but deviates at larger densities, as expected. The dependence of these expressions upon translational-rotational coupling was also examined. Interestingly, even at low densities, the agreement with simulation results was sometimes not even qualitatively correct. Compared with smooth hard sphere behaviour, the transport coefficients can change significantly due to translational-rotational coupling and this effect becomes stronger the greater the coupling. Overall, the rough hard sphere fluid provides an excellent model for understanding the effects of translational-rotational coupling upon transport coefficients.

  6. Geometry dependent transport properties of undoped InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Guenel, H. Yusuf; Bloemers, Christian; Sladek, Kamil; Penz, Andreas; Hardtdegen, Hilde; Lenk, Steffi; Schubert, Juergen; Schaepers, Thomas; Gruetzmacher, Detlev [Institute of Bio- and Nanosystems (IBN-1) and JARA-Fundamentals of Future Information Technology, Research Centre Juelich GmbH, 52425 Juelich (Germany); Luysberg, Martina [Institute of Solid State Research and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forchungszentrum Juelich, 52425 Juelich (Germany)

    2010-07-01

    In recent time nanowire (NW) structures attracted much attention, for electronics, optoelectronics and fundamental quantum properties. On account of different application purposes basic transport properties are crucially important at room temperature as well as low temperatures. In this respect InAs NWs are particularly important due to the low band gap and high carrier concentration. We characterized the basic transport parameters of undoped InAs NWs at room temperature, which were grown on GaAs(001) substrate by MOVPE without catalyst. The NWs that we used in this work had diameters ranging from 25 nm to 200 nm and lengths up to 3.5 {mu}m. Basic transport parameters, such as carrier concentration and mobility, were determined by using two- and four-terminal measurement configuration. The carrier concentration could be controlled by a SiO{sub 2} -isolated back-gate structure. By analyzing the transfer characteristics of the NW FET, we observed very good gate controllability.

  7. Upscaling flow and transport properties in synthetic porous media

    Science.gov (United States)

    Jasinski, Lukasz; Dabrowski, Marcin

    2015-04-01

    Flow and transport through the porous media has instances in nature and industry: contaminant migration in geological formations, gas/oil extraction from proppant filled hydraulic fractures and surrounding porous matrix, underground carbon dioxide sequestration and many others. We would like to understand the behavior of propagating solute front in such medium, mainly flow preferential pathways and the solute dispersion due to the porous medium geometry. The motivation of our investigation is to find connection between the effective flow and transport properties and porous media geometry in 2D and 3D for large system sizes. The challenge is to discover a good way of upscaling flow and transport processes to obtain results comparable to these calculated on pore-scale in much faster way. We study synthetic porous media made of densely packed poly-disperse disk-or spherical-shaped grains in 2D and 3D, respectively. We use various protocols such as the random sequential addition (RSA) algorithm to generate densely packed grains. Imposed macroscopic pressure gradient invokes fluid flow through the pore space of generated porous medium samples. As the flow is considered in the low Reynolds number regime, a stationary velocity field is obtained by solving the Stokes equations by means of finite element method. Void space between the grains is accurately discretized by using body-fitting triangular or tetrahedral mesh. Finally, pure advection of a front carried by the velocity field is studied. Periodicity in all directions is applied to microstructure, flow and transport processes. Effective permeability of the media can be calculated by integrating the velocity field on cross sections, whereas effective dispersion coefficient is deduced by application of centered moment methods on the concentration field of transported solute in time. The effective parameters are investigated as a function of geometrical parameters of the media, such as porosity, specific surface area

  8. Morphologic and transport properties of natural organic floc

    Science.gov (United States)

    Larsen, L.G.; Harvey, J.W.; Crimaldi, J.P.

    2009-01-01

    The morphology, entrainment, and settling of suspended aggregates ("floc") significantly impact fluxes of organic carbon, nutrients, and contaminants in aquatic environments. However, transport properties of highly organic floc remain poorly understood. In this study detrital floc was collected in the Florida Everglades from two sites with different abundances of periphyton for use in a settling column and in racetrack flume entrainment experiments. Although Everglades flocs are similar to other organic aggregates in terms of morphology and settling rates, they tend to be larger and more porous than typical mineral flocs because of biostabilization processes and relatively low prevailing shear stresses typical of wetlands. Flume experiments documented that Everglades floc was entrained at a low bed shear stress of 1.0 ?? 10-2 Pa, which is considerably smaller than the typical entrainment threshold of mineral floc. Because of similarities between Everglades floc and other organic floc populations, floc transport characteristics in the Everglades typify the behavior of floc in other organic-rich shallow-water environments. Highly organic floc is more mobile than less organic floc, but because bed shear stresses in wetlands are commonly near the entrainment threshold, wetland floc dynamics are often transport-limited rather than supply limited. Organic floc transport in these environments is therefore governed by the balance between entrainment and settling fluxes, which has implications for ecosystem metabolism, materials cycling, and even landscape evolution. Copyright 2009 by the American Geophysical Union.

  9. Structural and robustness properties of smart-city transportation networks

    Science.gov (United States)

    Zhang, Zhen-Gang; Ding, Zhuo; Fan, Jing-Fang; Meng, Jun; Ding, Yi-Min; Ye, Fang-Fu; Chen, Xiao-Song

    2015-09-01

    The concept of smart city gives an excellent resolution to construct and develop modern cities, and also demands infrastructure construction. How to build a safe, stable, and highly efficient public transportation system becomes an important topic in the process of city construction. In this work, we study the structural and robustness properties of transportation networks and their sub-networks. We introduce a complementary network model to study the relevance and complementarity between bus network and subway network. Our numerical results show that the mutual supplement of networks can improve the network robustness. This conclusion provides a theoretical basis for the construction of public traffic networks, and it also supports reasonable operation of managing smart cities. Project supported by the Major Projects of the China National Social Science Fund (Grant No. 11 & ZD154).

  10. Low temperature carrier transport properties in isotopically controlled germanium

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, K.

    1994-12-01

    Investigations of electronic and optical properties of semiconductors often require specimens with extremely homogeneous dopant distributions and precisely controlled net-carrier concentrations and compensation ratios. The previous difficulties in fabricating such samples are overcome as reported in this thesis by growing high-purity Ge single crystals of controlled {sup 75}Ge and {sup 70}Ge isotopic compositions, and doping these crystals by the neutron transmutation doping (NTD) technique. The resulting net-impurity concentrations and the compensation ratios are precisely determined by the thermal neutron fluence and the [{sup 74}Ge]/[{sup 70}Ge] ratios of the starting Ge materials, respectively. This method also guarantees unprecedented doping uniformity. Using such samples the authors have conducted four types of electron (hole) transport studies probing the nature of (1) free carrier scattering by neutral impurities, (2) free carrier scattering by ionized impurities, (3) low temperature hopping conduction, and (4) free carrier transport in samples close to the metal-insulator transition.

  11. Transport properties of zigzag graphene nanoribbon decorated with copper clusters

    Energy Technology Data Exchange (ETDEWEB)

    Berahman, M.; Sheikhi, M. H., E-mail: msheikhi@shirazu.ac.ir [School of Electrical and Computer Eng, Shiraz University, Shiraz (Iran, Islamic Republic of); Nanotechnology Research Institute, Shiraz University, Shiraz (Iran, Islamic Republic of)

    2014-09-07

    Using non-equilibrium green function with density functional theory, the present study investigates the transport properties of decorated zigzag graphene nanoribbon with a copper cluster. We have represented the decoration of zigzag graphene nanoribbon with single copper atom and cluster containing two and three copper atoms. In all the cases, copper atoms tend to occupy the edge state. In addition, we have shown that copper can alter the current-voltage characteristic of zigzag graphene nanoribbon and create new fluctuations and negative differential resistance. These alternations are made due to discontinuity in the combination of orbitals along the graphene nanoribbon. Decoration alters these discontinuities and creates more visible fluctuations. However, in low bias voltages, the changes are similar in all the cases. The study demonstrates that in the decorated zigzag graphene nanoribbon, the edge states are the main states for transporting electron from one electrode to another.

  12. Unique Reversible Crystal-to-Crystal Phase Transition – Structural and Functional Properties of Fused Ladder Thienoarenes

    KAUST Repository

    Abe, Yuichiro

    2017-08-15

    Donor-acceptor type molecules based on fused ladder thienoarenes, indacenodithiophene (IDT) and dithienocyclopenta-thienothiophene (DTCTT), coupled with benzothiadiazole, are prepared and their solid-state structures are investigated. They display a rich variety of solid phases ranging from amorphous glass states to crystalline states, upon changes in the central aromatic core and side group structures. Most notably, the DTCTT-based derivatives showed reversible crystal-to-crystal phase transitions in heating and cooling cycles. Unlike what has been seen in π−conjugated molecules variable temperature XRD revealed that structural change occurs continuously during the transition. A columnar self-assembled structure with slip-stacked π−π interaction is proposed to be involved in the solid-state. This research provides the evidence of unique structural behavior of the DTCTT-based molecules through the detailed structural analysis. This unique structural transition paves the way for these materials to have self-healing of crystal defects, leading to improved optoelectronic properties.

  13. One-Dimensional Perovskite Manganite Oxide Nanostructures: Recent Developments in Synthesis, Characterization, Transport Properties, and Applications.

    Science.gov (United States)

    Li, Lei; Liang, Lizhi; Wu, Heng; Zhu, Xinhua

    2016-12-01

    One-dimensional nanostructures, including nanowires, nanorods, nanotubes, nanofibers, and nanobelts, have promising applications in mesoscopic physics and nanoscale devices. In contrast to other nanostructures, one-dimensional nanostructures can provide unique advantages in investigating the size and dimensionality dependence of the materials' physical properties, such as electrical, thermal, and mechanical performances, and in constructing nanoscale electronic and optoelectronic devices. Among the one-dimensional nanostructures, one-dimensional perovskite manganite nanostructures have been received much attention due to their unusual electron transport and magnetic properties, which are indispensable for the applications in microelectronic, magnetic, and spintronic devices. In the past two decades, much effort has been made to synthesize and characterize one-dimensional perovskite manganite nanostructures in the forms of nanorods, nanowires, nanotubes, and nanobelts. Various physical and chemical deposition techniques and growth mechanisms are explored and developed to control the morphology, identical shape, uniform size, crystalline structure, defects, and homogenous stoichiometry of the one-dimensional perovskite manganite nanostructures. This article provides a comprehensive review of the state-of-the-art research activities that focus on the rational synthesis, structural characterization, fundamental properties, and unique applications of one-dimensional perovskite manganite nanostructures in nanotechnology. It begins with the rational synthesis of one-dimensional perovskite manganite nanostructures and then summarizes their structural characterizations. Fundamental physical properties of one-dimensional perovskite manganite nanostructures are also highlighted, and a range of unique applications in information storages, field-effect transistors, and spintronic devices are discussed. Finally, we conclude this review with some perspectives/outlook and future

  14. Electronic Transport Properties of Doped C28 Fullerene

    Directory of Open Access Journals (Sweden)

    Akshu Pahuja

    2014-01-01

    Full Text Available Endohedral doping of small fullerenes like C28 affects their electronic structure and increases their stability. The transport properties of Li@C28 sandwiched between two gold surfaces have been calculated using first-principles density functional theory and nonequilibrium Green’s function formalism. The transmission curves, IV characteristics, and molecular projected self-consistent Hamiltonian eigenstates of both pristine and doped molecule are computed. The current across the junction is found to decrease upon Li encapsulation, which can be attributed to change in alignment of molecular energy levels with bias voltage.

  15. Thermodynamic and transport properties of underdoped cuprates from ARPES data

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, T.; Zhou, X.J.; Yagi, H.; Lu, D.H.; Tanaka, K.; Fujimori, A.; Hussain, Z.; Shen, Z.-X.; Kakeshita, T.; Eisaki, H.; Uchida, S.; Segawa, Kouji; Lavrov, A.N.; Ando, Yoichi

    2004-09-15

    The relationship between photoemission spectra of high-T{sub c} cuprates and their thermodynamic and transport properties are discussed. The doping dependence of the expected quasi-particle density at the Fermi level (E{sub F}) are compared with the electronic specific heat coefficient {gamma} and that of the spectral weight at E{sub F} with the in-plane and out-of-plane superfluid density. We have estimated the electrical resistivity of underdoped cuprates from the momentum distribution curve (MDC) at E{sub F} in the nodal direction. The temperature dependence of the MDC width is also consistent with that of the electrical resistivity.

  16. Transport properties of a ladder with two random dimer chains

    Institute of Scientific and Technical Information of China (English)

    Hu Donng-Sheng; Zhu Chen-Ping; Zhang Yong-Mei

    2011-01-01

    We investigate the transport properties of a ladder with two random dimer (RD) chains. It is found that there are two extended states in the ladder with identical RD chains and a critical state regarded as an extended state in the ladder with pairing RD chains. Such a critical state is caused by the chiral symmetry. The ladder with identical RD chains can be decoupled into two isolated RD chains and the ladder with pairing RD chains can not. The analytic expressions of the extended states are presented for the ladder with identical RD chains.

  17. Transport properties in periodically modulated zigzag silicene nanoribbon

    Science.gov (United States)

    Wang, Xiao-Shuang; Shen, Man; An, Xing-Tao; Liu, Jian-Jun

    2016-04-01

    We study theoretically the electronic transport properties of zigzag silicene nanoribbon superlattices subject to a periodic electric field perpendicular to the surface of silicene. Our results show that the conductivity of the system depends on the superlattice structural parameters and show effects analogous to those found with two-dimensional semiconductor superlattices. For a superlattice with Nb barriers, a series of resonant peaks, each of which is split into (Nb - 1) subpeaks, and transmission blockade regions appear in the conductance spectrum, which indicates the formation of minibands and minigaps. These silicene-based quantum structures can provide concepts for the design nanodevices.

  18. Transport properties of Fibonacci heterostructures: a nonparabolic approach

    Science.gov (United States)

    Palomino-Ovando, M.; Cocoletzi, G. H.

    1998-07-01

    A fourth order hamiltonian is used to explore transport properties of semiconductor Fibonacci heterostructures. The tunneling current and time delay are obtained for different Fibonacci sequences constructed withGaAsandAlxGa1 - xAs. Energy minibands are calculated to study the fractal dimension and critical electronic states in quasi-periodic arrays. Results show that nonparabolic corrections produce changes in the tunneling current, time delay and fractal dimension, and a low voltage shift of the current peaks compared with the parabolic theory. The electronic states preserve their critical nature in the presence of nonparabolic effects.

  19. Transport and magnetic properties of CMR manganites with antidot arrays

    Science.gov (United States)

    Zhang, Kai; Du, Kai; Niu, Jiebin; Wei, Wengang; Chen, Jinjie; Yin, Lifeng; Shen, Jian

    2014-03-01

    We fabricated and characterized a series of manganites thin film samples with different densities of antidots. With increasing antidot density, the samples show higher MIT temperature and lower resistivity under zero and low magnetic fields. These differences become smaller and finally vanished when the magnetic field is large enough to melt the charge ordered phase in the system, which is expected in our theoretical explanations. We believe that emerging edge states at the ring of antidotes play a significant role for observed metal-insulator transition and electrical transport properties, which are of great importance of real storage and sensor device design. Magnetic property measurements and theoretical simulation also support the conclusion. These results open up new ways to control and tune the strongly correlated oxides without introduce any new material or field.

  20. Predicting the transport properties of sedimentary rocks from microgeometry

    Energy Technology Data Exchange (ETDEWEB)

    Schlueter, E.M.

    1995-02-01

    The author investigates through analysis and experiment how pore geometry, topology, and the physics and chemistry of mineral-fluid and fluid-fluid interactions affect the flow of fluids through consolidated/partially consolidated porous media. The approach is to measure fluid permeability and electrical conductivity of rock samples using single and multiple fluid phases that can be frozen in place (wetting and nonwetting) over a range of pore pressures. These experiments are analyzed in terms of the microphysics and microchemistry of the processes involved to provide a theoretical basis for the macroscopic constitutive relationships between fluid-flow and geophysical properties that the authors develop. The purpose of these experiments and their analyses is to advance the understanding of the mechanisms and factors that control fluid transport in porous media. This understanding is important in characterizing porous media properties and heterogeneities before simulating and monitoring the progress of complex flow processes at the field scale in permeable media.

  1. Electromagnetic and transport properties of QGP within PLSM approach

    CERN Document Server

    Tawfik, Abdel Nasser

    2016-01-01

    In order to study the response of the quantum chromodynamic matter to finite electromagnetic fields, we utilize the Polyakov linear - sigma model (PLSM) in mean-field approximation. Due to participants' momentum imbalance and off-center relativistic motion of the spectators' electric charges, localized, short-lived, huge electromagnetic fields are to be generated in the relativistic heavy-ion collisions. We report on various electromagnetic and transport properties of the new-state-of matter; the quark-gluon plasma (QGP) within the QCD-like approach, PLSM. We find an excellent agreement between our PLSM calculations and various recent lattice QCD simulations and notice that the magnetization and the magnetic susceptibility and the relative permeability obviously increase in the QGP phase. We predict that increasing the magnetic field remarkable decreases the viscosity, especially in hadron phase. while in QGP phase, the viscous properties seem not being affected with.

  2. Electrical transport properties of manganite powders under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, M.G. [Laboratorio de Bajas Temperaturas, Departamento de Fisica, FCEyN, UBA, and IFIBA (CONICET), Ciudad Universitaria, (C1428EHA) Buenos Aires (Argentina); Leyva, A.G. [Gerencia de Investigacion y Aplicaciones, CAC, Comision Nacional de Energia Atomica, Gral Paz 1499, 1650 San Martin, Buenos Aires (Argentina); Acha, C., E-mail: acha@df.uba.ar [Laboratorio de Bajas Temperaturas, Departamento de Fisica, FCEyN, UBA, and IFIBA (CONICET), Ciudad Universitaria, (C1428EHA) Buenos Aires (Argentina)

    2012-08-15

    We have measured the electrical resistance of micrometric to nanometric powders of the La{sub 5/8-y}Pr{sub y}Ca{sub 3/8}MnO{sub 3} (LPCMO with y=0.3) manganite for hydrostatic pressures up to 4 kbar. By applying different final thermal treatments to samples synthesized by a microwave assisted denitration process, we obtained two particular grain characteristic dimensions (40 nm and 1000 nm) which allowed us to analyze the grain size sensitivity of the electrical conduction properties of both the metal electrode interface with manganite (Pt/LPCMO) and the intrinsic intergranular interfaces formed by the LPCMO powder, conglomerate under the only effect of external pressure. We also analyzed the effects of pressure on the phase diagram of these powders. Our results indicate that different magnetic phases coexist at low temperatures and that the electrical transport properties are related to the intrinsic interfaces, as we observe evidences of a granular behavior and an electronic transport dominated by the Space Charge limited Current mechanism.

  3. Topological phases and transport properties of screened interacting quantum wires

    Science.gov (United States)

    Xu, Hengyi; Xiong, Ye; Wang, Jun

    2016-10-01

    We study theoretically the effects of long-range and on-site Coulomb interactions on the topological phases and transport properties of spin-orbit-coupled quasi-one-dimensional quantum wires imposed on a s-wave superconductor. The distributions of the electrostatic potential and charge density are calculated self-consistently within the Hartree approximation. Due to the finite width of the wires and charge repulsion, the potential and density distribute inhomogeneously in the transverse direction and tend to accumulate along the lateral edges where the hard-wall confinement is assumed. This result has profound effects on the topological phases and the differential conductance of the interacting quantum wires and their hybrid junctions with superconductors. Coulomb interactions renormalize the gate voltage and alter the topological phases strongly by enhancing the topological regimes and producing jagged boundaries. Moreover, the multicritical points connecting different topological phases are modified remarkably in striking contrast to the predictions of the two-band model. We further suggest the possible non-magnetic topological phase transitions manipulated externally with the aid of long-range interactions. Finally, the transport properties of normal-superconductor junctions are further examined, in particular, the impacts of Coulomb interactions on the zero-bias peaks related to the Majorana fermions and near zero-energy peaks.

  4. TASK 7 DEMONSTRATION OF THAMES FOR MICROSTRUCTURE AND TRANSPORT PROPERTIES

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C.; Bullard, J.; Stutzman, P.; Snyder, K.; Garboczi, E.

    2010-03-29

    The goal of the Cementitious Barriers Partnership (CBP) is to develop a reasonable and realible set of tools to reduce the uncertainty in predicting the structural, hydraulic and chemical performance of cement barriers used in nuclear applications that are exposed to dynamic environmental conditions over extended time frames. One of these tools, the responsibility of NIST, is THAMES (Thermodynamic Hydration and Microstructure Evolution Simulator), which is being developed to describe cementitious binder microstructures and calculate important engineering properties during hydration and degradation. THAMES is designed to be a 'micro-probe', used to evaluate changes in microstructure and properties occurring over time because of hydration or degradation reactions in a volume of about 0.001 mm{sup 3}. It will be used to map out microstructural and property changes across reaction fronts, for example, with spatial resolution adequate to be input into other models (e.g., STADIUM{reg_sign}, LeachSX{trademark}) in the integrated CBP package. THAMES leverages thermodynamic predictions of equilibrium phase assemblages in aqueous geochemical systems to estimate 3-D virtual microstructures of a cementitious binder at different times during the hydration process or potentially during degradation phenomena. These virtual microstructures can then be used to calculate important engineering properties of a concrete made from that binder at prescribed times. In this way, the THAMES model provides a way to calculate the time evolution of important material properties such as elastic stiffness, compressive strength, diffusivity, and permeability. Without this model, there would be no way to update microstructure and properties for the barrier materials considered as they are exposed to the environment, thus greatly increasing the uncertainty of long-term transport predictions. This Task 7 report demonstrates the current capabilities of THAMES. At the start of the CBP

  5. Unique Regulatory Properties of Heterotetrameric Inositol 1,4,5-Trisphosphate Receptors Revealed by Studying Concatenated Receptor Constructs.

    Science.gov (United States)

    Chandrasekhar, Rahul; Alzayady, Kamil J; Wagner, Larry E; Yule, David I

    2016-03-01

    The ability of inositol 1,4,5-trisphosphate receptors (IP3R) to precisely initiate and generate a diverse variety of intracellular Ca(2+) signals is in part mediated by the differential regulation of the three subtypes (R1, R2, and R3) by key functional modulators (IP3, Ca(2+), and ATP). However, the contribution of IP3R heterotetramerization to Ca(2+) signal diversity has largely been unexplored. In this report, we provide the first definitive biochemical evidence of endogenous heterotetramer formation. Additionally, we examine the contribution of individual subtypes within defined concatenated heterotetramers to the shaping of Ca(2+) signals. Under conditions where key regulators of IP3R function are optimal for Ca(2+) release, we demonstrate that individual monomers within heteromeric IP3Rs contributed equally toward generating a distinct 'blended' sensitivity to IP3 that is likely dictated by the unique IP3 binding affinity of the heteromers. However, under suboptimal conditions where [ATP] were varied, we found that one subtype dictated the ATP regulatory properties of heteromers. We show that R2 monomers within a heterotetramer were both necessary and sufficient to dictate the ATP regulatory properties. Finally, the ATP-binding site B in R2 critical for ATP regulation was mutated and rendered non-functional to address questions relating to the stoichiometry of IP3R regulation. Two intact R2 monomers were sufficient to maintain ATP regulation in R2 homotetramers. In summary, we demonstrate that heterotetrameric IP3R do not necessarily behave as the sum of the constituent subunits, and these properties likely extend the versatility of IP3-induced Ca(2+) signaling in cells expressing multiple IP3R isoforms.

  6. Unique cell adhesion and invasion properties of Yersinia enterocolitica O:3, the most frequent cause of human Yersiniosis.

    Science.gov (United States)

    Uliczka, Frank; Pisano, Fabio; Schaake, Julia; Stolz, Tatjana; Rohde, Manfred; Fruth, Angelika; Strauch, Eckhard; Skurnik, Mikael; Batzilla, Julia; Rakin, Alexander; Heesemann, Jürgen; Dersch, Petra

    2011-07-01

    Many enteric pathogens are equipped with multiple cell adhesion factors which are important for host tissue colonization and virulence. Y. enterocolitica, a common food-borne pathogen with invasive properties, uses the surface proteins invasin and YadA for host cell binding and entry. In this study, we demonstrate unique cell adhesion and invasion properties of Y. enterocolitica serotype O:3 strains, the most frequent cause of human yersiniosis, and show that these differences are mainly attributable to variations affecting the function and expression of invasin in response to temperature. In contrast to other enteric Yersinia strains, invasin production in O:3 strains is constitutive and largely enhanced compared to other Y. enterocolitica serotypes, in which invA expression is temperature-regulated and significantly reduced at 37°C. Increase of invasin levels is caused by (i) an IS1667 insertion into the invA promoter region, which includes an additional promoter and RovA and H-NS binding sites, and (ii) a P98S substitution in the invA activator protein RovA rendering the regulator less susceptible to proteolysis. Both variations were shown to influence bacterial colonization in a murine infection model. Furthermore, we found that co-expression of YadA and down-regulation of the O-antigen at 37°C is required to allow efficient internalization by the InvA protein. We conclude that even small variations in the expression of virulence factors can provoke a major difference in the virulence properties of closely related pathogens which may confer better survival or a higher pathogenic potential in a certain host or host environment.

  7. Unique cell adhesion and invasion properties of Yersinia enterocolitica O:3, the most frequent cause of human Yersiniosis.

    Directory of Open Access Journals (Sweden)

    Frank Uliczka

    2011-07-01

    Full Text Available Many enteric pathogens are equipped with multiple cell adhesion factors which are important for host tissue colonization and virulence. Y. enterocolitica, a common food-borne pathogen with invasive properties, uses the surface proteins invasin and YadA for host cell binding and entry. In this study, we demonstrate unique cell adhesion and invasion properties of Y. enterocolitica serotype O:3 strains, the most frequent cause of human yersiniosis, and show that these differences are mainly attributable to variations affecting the function and expression of invasin in response to temperature. In contrast to other enteric Yersinia strains, invasin production in O:3 strains is constitutive and largely enhanced compared to other Y. enterocolitica serotypes, in which invA expression is temperature-regulated and significantly reduced at 37°C. Increase of invasin levels is caused by (i an IS1667 insertion into the invA promoter region, which includes an additional promoter and RovA and H-NS binding sites, and (ii a P98S substitution in the invA activator protein RovA rendering the regulator less susceptible to proteolysis. Both variations were shown to influence bacterial colonization in a murine infection model. Furthermore, we found that co-expression of YadA and down-regulation of the O-antigen at 37°C is required to allow efficient internalization by the InvA protein. We conclude that even small variations in the expression of virulence factors can provoke a major difference in the virulence properties of closely related pathogens which may confer better survival or a higher pathogenic potential in a certain host or host environment.

  8. Efficient calculation of dissipative quantum transport properties in semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Greck, Peter

    2012-11-26

    We present a novel quantum transport method that follows the non-equilibrium Green's function (NEGF) framework but side steps any self-consistent calculation of lesser self-energies by replacing them by a quasi-equilibrium expression. We termed this method the multi-scattering Buettiker-Probe (MSB) method. It generalizes the so-called Buettiker-Probe model but takes into account all relevant individual scattering mechanisms. It is orders of magnitude more efficient than a fully selfconsistent non-equilibrium Green's function calculation for realistic devices, yet accurately reproduces the results of the latter method as well as experimental data. This method is fairly easy to implement and opens the path towards realistic three-dimensional quantum transport calculations. In this work, we review the fundamentals of the non-equilibrium Green's function formalism for quantum transport calculations. Then, we introduce our novel MSB method after briefly reviewing the original Buettiker-Probe model. Finally, we compare the results of the MSB method to NEGF calculations as well as to experimental data. In particular, we calculate quantum transport properties of quantum cascade lasers in the terahertz (THz) and the mid-infrared (MIR) spectral domain. With a device optimization algorithm based upon the MSB method, we propose a novel THz quantum cascade laser design. It uses a two-well period with alternating barrier heights and complete carrier thermalization for the majority of the carriers within each period. We predict THz laser operation for temperatures up to 250 K implying a new temperature record.

  9. Large-scale characterization of natural ligands explains the unique gluten-binding properties of HLA-DQ2.

    Science.gov (United States)

    Stepniak, Dariusz; Wiesner, Martina; de Ru, Arnoud H; Moustakas, Antonis K; Drijfhout, Jan Wouter; Papadopoulos, George K; van Veelen, Peter A; Koning, Frits

    2008-03-01

    Celiac disease is an enteropathy caused by intolerance to dietary gluten. The disorder is strongly associated with DQA1*0501/DQB1*0201 (HLA-DQ2) as approximately 95% of celiac patients express this molecule. HLA-DQ2 has unique Ag-binding properties that allow it to present a diverse set of gluten peptides to gluten-reactive CD4+ T cells so instigating an inflammatory reaction. Previous work has indicated that the presence of negatively charged amino acids within gluten peptides is required for specific binding. This, however, only partly explains the scale of the interaction. We have now characterized 432 natural ligands of HLA-DQ2 representing length variants of 155 distinct sequences. The sequences were aligned and the binding cores were inferred. Analysis of the amino acid distribution of these cores demonstrated that negatively charged residues in HLA-DQ2-bound peptides are favored at virtually all positions. This contrasts with a more restricted presence of such amino acids in T cell epitopes from gluten. Yet, HLA-DQ2 was also found to display a strong preference for proline at several anchor and nonanchor positions that largely match the position of proline in gluten T cell epitopes. Consequently, the bias for proline at p6 and p8 facilitates the enzymatic conversion of glutamine into glutamic acid in gluten peptides at p4 and p6, two important anchor sites. These observations provide new insights in the unique ability of HLA-DQ2 to bind a large repertoire of glutamine- and proline-rich gluten peptides. This knowledge may be an important asset in the development of future treatment strategies.

  10. Unique Path Partitions

    DEFF Research Database (Denmark)

    Bessenrodt, Christine; Olsson, Jørn Børling; Sellers, James A.

    2013-01-01

    We give a complete classification of the unique path partitions and study congruence properties of the function which enumerates such partitions.......We give a complete classification of the unique path partitions and study congruence properties of the function which enumerates such partitions....

  11. Unique Aeolian Transport Mechanisms on Mars: Respective Roles of Percussive and Repercussive Grain Populations in the Sediment Load

    Science.gov (United States)

    Marshall, John R.

    1999-01-01

    Experiments show that when sand-size grains impact a sediment surface with energy levels commensurate for Mars, small craters are formed by the ejection of several hundred grains from the bed. The experiments were conducted with a modified crossbow in which a sand-impelling sabot replaced the bolt-firing mechanism. Individual grains of sand could be fired at loose sand targets to observe ballistic effects unhindered by aerodynamic mobilization of the bed. Impact trajectories simulated the saltation process on dune surfaces. Impact craters were not elongated despite glancing (15 deg.) bed impact; the craters were very close to being circular. High-speed photography showed them to grow in both diameter and depth after the impactor had ricochetted from the crater site. The delayed response of the bed was "explosive" in nature, and created a miniature ejecta curtain spreading upward and outward for many centimeters for impact of 100-300 um-diameter grains into similar material. This behavior is explained by deposition of elastic energy in the bed by the "percussive" grain. Impact creates a subsurface stress regime or "quasi-Boussinesq" compression field. Elastic recovery of the bed occurs by dilatancy; shear stresses suddenly convert the grains to open packing and they consequently become forcefully ejected from the site. Random jostling of the grains causes radial homogenization of stress vectors and a resulting circular crater. A stress model based on repercussive bed dilatancy and interparticle adhesive forces (for smaller grains) predicts, to first order, the observed crater volumes for various impact conditions. On earth, only a few grains are mobilized by a percussive saltating grain; some grains are "knudged" along the ground, and some are partly expelled on short trajectories. These motions constitute reptation transport. On Mars, saltation and reptation become indistinct: secondary or "repercussive" trajectories have sufficient vertical impulse to create a

  12. Interface disorder and transport properties in HTC/CMR superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Haberkorn, N.; Guimpel, J.; Sirena, M.; Steren, L.B.; Campillo, G.; Saldarriaga, W.; Gomez, M.E

    2004-08-01

    The physical properties of superlattices are affected by interface disorder, like roughness and interdiffusion. X-ray diffraction allows its measurement through modeling and structure refinement. The high-T{sub c} RBa{sub 2}Cu{sub 3}O{sub 7} (RBCO) and colossal magnetoresistance La{sub x}A{sub 1-x}MnO{sub 3} (LAMO) perovskites are interesting superlattice partners given their similar lattice parameters and because the combination of magnetic and superconducting properties is interesting for both basic and applied research. We have investigated the structural and transport properties of YBCO/La{sub 2/3}Ca{sub 1/3}MnO{sub 3} and GdBCO/La{sub 0.6}Sr{sub 0.04}MnO{sub 3} superlattices grown by sputtering on (1 0 0)MgO. We find a roughness of 1 RBCO unit cell and a 30% interdiffusion in the same length from the interfaces for all samples. The superconducting behavior is found strongly dependent on the LAMO layer thickness.

  13. Electrical transport properties of single-layer WS2.

    Science.gov (United States)

    Ovchinnikov, Dmitry; Allain, Adrien; Huang, Ying-Sheng; Dumcenco, Dumitru; Kis, Andras

    2014-08-26

    We report on the fabrication of field-effect transistors based on single layers and bilayers of the semiconductor WS2 and the investigation of their electronic transport properties. We find that the doping level strongly depends on the device environment and that long in situ annealing drastically improves the contact transparency, allowing four-terminal measurements to be performed and the pristine properties of the material to be recovered. Our devices show n-type behavior with a high room-temperature on/off current ratio of ∼10(6). They show clear metallic behavior at high charge carrier densities and mobilities as high as ∼140 cm(2)/(V s) at low temperatures (above 300 cm(2)/(V s) in the case of bilayers). In the insulating regime, the devices exhibit variable-range hopping, with a localization length of about 2 nm that starts to increase as the Fermi level enters the conduction band. The promising electronic properties of WS2, comparable to those of single-layer MoS2 and WSe2, together with its strong spin-orbit coupling, make it interesting for future applications in electronic, optical, and valleytronic devices.

  14. High field transport properties of MBE processed Fe-based superconducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Iida, Kazumasa [Nagoya University (Japan); IFW Dresden (Germany)

    2015-07-01

    It has been reported that Fe-based superconductors show high upper critical fields with low anisotropies at low temperatures. Hence these materials may offer a unique possibility for high field magnet applications. However, only a few reports on high-field transport properties of Co-doped Ba-122 and Fe(Se,Te) have been published and the only one for SmFeAs(O,F) thin films to date. In order to use this material class for applications, the knowledge of in-field and its orientation dependence of transport properties in a wide range of external fields need to be clarified. In this talk, I will report on high-field (up to dc 45 T) transport properties of P-doped Ba-122, SmFeAs(O,F) and NdFeAs(O,F) thin films prepared by MBE. Although P-doped Ba-122 has the lowest T{sub c}, self-field J{sub c} of over 6 MA/cm{sup 2} at 4.2 K is recorded, which is the highest value ever reported in Fe-based superconductors. Additionally, in-field performance of P-doped Ba-122 shows comparable to those of NdFeAs(O,F) and SmFeAs(O,F) for Hc. On the other hand, both NdFeAs(O,F) and SmFeAs(O,F) exhibited higher J{sub c} for H parallel ab due to the intrinsic pinning. These results indicate that P-doped Ba-122 is the most promising candidates for high-field magnet applications.

  15. Tubuliform silk protein: A protein with unique molecular characteristics and mechanical properties in the spider silk fibroin family

    Science.gov (United States)

    Tian, M.; Lewis, R. V.

    2006-02-01

    Orb-web weavers can produce up to six different types of silk and a glue for various functions. Tubuliform silk is unique among them due to its distinct amino acid composition, specific time of production, and atypical mechanical properties. To study the protein composing this silk, tubuliform gland cDNA libraries were constructed from three orb-weaving spiders Argiope aurantia, Araneus gemmoides, and Nephila clavipes. Amino acid composition comparison between the predicted tubuliform silk protein sequence (TuSp1) and the corresponding gland protein confirms that TuSp1 is the major component in tubuliform gland in three spiders. Sequence analysis suggests that TuSp1 shares no significant similarity with its paralogues, while it has conserved sequence motifs with the most primitive spider, Euagrus chisoseus silk protein. The presence of large side-chain amino acids in TuSp1 sequence is consistent with the frustrated β-sheet crystalline structure of tubuliform silk observed in transmission electron microscopy. Repeat unit comparison within species as well as among three spiders exhibits high sequence conservation. Parsimony analysis based on carboxy terminal sequence shows that Argiope and Araneus are more closely related than either is to Nephila which is consistent with phylogenetic analysis based on morphological evidence.

  16. The study of thermodynamic properties and transport properties of multicomponent systems with chemical reactions

    Directory of Open Access Journals (Sweden)

    Samujlov E.

    2013-04-01

    Full Text Available In case of system with chemical reaction the most important properties are heat conductivity and heat capacity. In this work we have considered the equation for estimate the component of these properties caused by chemical reaction and ionization processes. We have evaluated the contribution of this part in heat conductivity and heat capacity too. At the high temperatures contribution in heat conductivity from ionization begins to play an important role. We have created a model, which describe partial and full ionization of gases and gas mixtures. In addition, in this work we present the comparison of our result with experimental data and data from numerical simulation. We was used the data about transport properties of middle composition of Russian coals and the data of thermophysical properties of natural gas for comparison.

  17. Spin transport properties in double quantum rings connected in series*

    Institute of Scientific and Technical Information of China (English)

    Du Jian; Wang Suxin; Pan Jianghong

    2011-01-01

    A new model of metal/semiconductor/metal double-quantum-ring connected in series is proposed and the transport properties in this model are theoretically studied. The results imply that the transmission coefficient shows periodic variations with increasing semiconductor ring size. The effects of the magnetic field and Rashba spin-orbit interaction on the transmission coefficient for two kinds of spin state electrons are different. The number of the transmission coefficient peaks is related to the length ratio between the upper ann and the half circumference of the ring. In addition, the transmission coefficient shows oscillation behavior with enhanced external magnetic field, and the corresponding average value is related to the two leads' relative position.

  18. Electronic transport properties of a quinone-based molecular switch

    Science.gov (United States)

    Zheng, Ya-Peng; Bian, Bao-An; Yuan, Pei-Pei

    2016-09-01

    In this paper, we carried out first-principles calculations based on density functional theory and non-equilibrium Green's function to investigate the electronic transport properties of a quinone-based molecule sandwiched between two Au electrodes. The molecular switch can be reversibly switched between the reduced hydroquinone (HQ) and oxidized quinone (Q) states via redox reactions. The switching behavior of two forms is analyzed through their I- V curves, transmission spectra and molecular projected self-consistent Hamiltonian at zero bias. Then we discuss the transmission spectra of the HQ and Q forms at different bias, and explain the oscillation of current according to the transmission eigenstates of LUMO energy level for Q form. The results suggest that this kind of a quinone-based molecule is usable as one of the good candidates for redox-controlled molecular switches.

  19. Direct method for calculating temperature-dependent transport properties

    Science.gov (United States)

    Liu, Yi; Yuan, Zhe; Wesselink, R. J. H.; Starikov, Anton A.; van Schilfgaarde, Mark; Kelly, Paul J.

    2015-06-01

    We show how temperature-induced disorder can be combined in a direct way with first-principles scattering theory to study diffusive transport in real materials. Excellent (good) agreement with experiment is found for the resistivity of Cu, Pd, Pt (and Fe) when lattice (and spin) disorder are calculated from first principles. For Fe, the agreement with experiment is limited by how well the magnetization (of itinerant ferromagnets) can be calculated as a function of temperature. By introducing a simple Debye-like model of spin disorder parameterized to reproduce the experimental magnetization, the temperature dependence of the average resistivity, the anisotropic magnetoresistance, and the spin polarization of a Ni80Fe20 alloy are calculated and found to be in good agreement with existing data. Extension of the method to complex, inhomogeneous materials as well as to the calculation of other finite-temperature physical properties within the adiabatic approximation is straightforward.

  20. Symmetry analysis of transport properties in helical superconductor junctions

    Science.gov (United States)

    Cheng, Qiang; Zhang, Yinhan; Zhang, Kunhua; Jin, Biao; Zhang, Changlian

    2017-03-01

    We study the discrete symmetries satisfied by helical p-wave superconductors with the d-vectors {{k}x}\\hat{x}+/- {{k}y}\\hat{y} or {{k}y}\\hat{x}+/- {{k}x}\\hat{y} and the transformations brought by symmetry operations to ferromagnet and spin-singlet superconductors, which show intimate associations with the transport properties in heterojunctions, including helical superconductors. In particular, the partial symmetries of the Hamiltonian under spin-rotation and gauge-rotation operations are responsible for the novel invariances of the conductance in tunnel junctions and the new selection rules for the lowest current and peculiar phase diagrams in Josephson junctions, which were reported recently. The symmetries of constructed free energies for Josephson junctions are also analyzed, and are consistent with the results from the Hamiltonian.

  1. Structure and transport properties of atomic chains and molecules

    DEFF Research Database (Denmark)

    Strange, Mikkel

    2008-01-01

    conductance properties are explained in terms of a resonating-chain model, which takes the reflection probability and phase-shift of a single bulk-chain interface as the only input. The stability of silver-oxygen chains was studied with a thermodynamic model. This model has been developed in this work...... to describe tip-suspended atomically thin chains between macroscopic size electrodes. It has been tested with the use of DFT calculations on metal chains for which good agreement with experiments was obtained. To ensure the correctness of the DFT based transport calculations presented here, and in more...... tilted bridge configuration is found, with a conductance of 0.5G0 over a wide range of electrode displacements. This is in agreement with the observed peak at 0.5G0 in the experimentally obtained conductance histogram for Pt/CO [4]. Also, for homogenous Pt point contacts and short chains good agreement...

  2. Electronic transport properties of carbon nanotube metal-semiconductor-metal

    Directory of Open Access Journals (Sweden)

    F Khoeini

    2008-07-01

    Full Text Available  In this work, we study electronic transport properties of a quasi-one dimensional pure semi-conducting Zigzag Carbon Nanotube (CNT attached to semi-infinite clean metallic Zigzag CNT leads, taking into account the influence of topological defect in junctions. This structure may behave like a field effect transistor. The calculations are based on the tight-binding model and Green’s function method, in which the local density of states(LDOS in the metallic section to semi-conducting section, and muli-channel conductance of the system are calculated in the coherent and linear response regime, numerically. Also we have introduced a circuit model for the system and investigated its current. The theoretical results obtained, can be a base, for developments in designing nano-electronic devices.

  3. Magnetic and transport properties of discontinuous metal-oxides multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Dinia, A.; Schmerber, G.; Ulhaq, C.; El Bahraoui, T

    2003-02-15

    We report on structural, magnetic and transport properties of Al{sub 2}O{sub 3}/CoFe discontinuous multilayers deposited by RF sputtering at room temperature on silicon substrate. Transmission electron microscopy observations show that these multilayers consist of discontinuous layers of CoFe particles embedded in an insulating Al{sub 2}O{sub 3} matrix. This is further supported by magnetization measurements showing the presence at room temperature of both superparamagnetic and ferromagnetic components. The current-in-plane resistivity of the discontinuous multilayers has shown a negative magnetoresistance due to a spin-dependent tunneling between the CoFe magnetic particles through the insulating Al{sub 2}O{sub 3} barrier. The magnetoresistance response gives rise to two spin-dependent tunneling contributions. A contribution at small applied fields due to ferromagnetic particles and a contribution at larger magnetic applied fields due to a superparamagnetic particles.

  4. Electronic transport properties of the armchair silicon carbide nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Song Jiuxu; Yang Yintang; Liu Hongxia [Key Laboratory of Ministry of Education for Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China); Guo Lixin [School of Science, Xidian University, Xi' an 710071 (China); Zhang Zhiyong, E-mail: songjiuxu@126.com [Information Science and Technology Institution, Northwest University, Xi' an 710069 (China)

    2010-11-15

    The electronic transport properties of the armchair silicon carbide nanotube (SiCNT) are investigated by using the combined nonequilibrium Green's function method with density functional theory. In the equilibrium transmission spectrum of the nanotube, a transmission valley of about 2.12 eV is discovered around Fermi energy, which means that the nanotube is a wide band gap semiconductor and consistent with results of first principle calculations. More important, negative differential resistance is found in its current voltage characteristic. This phenomenon originates from the variation of density of states caused by applied bias voltage. These investigations are meaningful to modeling and simulation in silicon carbide nanotube electronic devices.

  5. Electrical transport and thermoelectric properties of boron carbide nanowires

    Science.gov (United States)

    Kirihara, Kazuhiro; Mukaida, Masakazu; Shimizu, Yoshiki

    2017-04-01

    The electrical transport and thermoelectric property of boron carbide nanowires synthesized by a carbothermal method are reported. It is demonstrated that the nanowires achieve a higher Seebeck coefficient and power factor than those of the bulk samples. The conduction mechanism of the nanowires at low temperatures below 300 K is different from that of the sintered-polycrystalline and single-crystal bulk samples. In a temperature range of 200–450 K, there is a crossover between electrical conduction by variable-range hopping and phonon-assisted hopping. The inhomogeneous carbon concentration and planar defects, such as twins and stacking faults, in the nanowires are thought to modify the bonding nature and electronic structure of the boron carbide crystal substantially, causing differences in the electrical conductivity and Seebeck coefficient. The effect of boundary scattering of phonon at nanostructured surface on the thermal conductivity reduction is discussed.

  6. Transport Properties of Fluids in Micropores by Molecular Dynamics Simulation

    Institute of Scientific and Technical Information of China (English)

    LIU, Ying-Chun(刘迎春); WANG, Qi(王琦); Lü, Ling-Hong(吕玲红)

    2004-01-01

    The transport properties of fluid argon in micropores, i.e. diffusivity and viscosity, were studied by molecular dynamics simulations. The effects of pore width, temperature and density on diffusivity and viscosity were analyzed in micropores with pore widths from 0.8 to 4.0 nm. The results show that the diffusivity in micropores is much lower than the bulk diffusivity, and it decreases as the pore width decreases; but the viscosity in micropores is significantly larger than the bulk one, and it increases sharply in narrow micropores. The diffusivity in channel parallel direction is obviously larger than that in channel perpendicular direction. The temperature and density are important factors that obviously affect diffusivity and viscosity in micropores.

  7. Transport properties of highly asymmetric hard-sphere mixtures.

    Science.gov (United States)

    Bannerman, Marcus N; Lue, Leo

    2009-04-28

    The static and dynamic properties of binary mixtures of hard spheres with a diameter ratio of sigma(B)/sigma(A)=0.1 and a mass ratio of m(B)/m(A)=0.001 are investigated using event driven molecular dynamics. The contact values of the pair correlation functions are found to compare favorably with recently proposed theoretical expressions. The transport coefficients of the mixture, determined from simulation, are compared to the predictions of the revised Enskog theory using both a third-order Sonine expansion and direct simulation Monte Carlo. Overall, the Enskog theory provides a fairly good description of the simulation data, with the exception of systems at the smallest mole fraction of larger spheres (x(A)=0.01) examined. A "fines effect" was observed at higher packing fractions, where adding smaller spheres to a system of large spheres decreases the viscosity of the mixture; this effect is not captured by the Enskog theory.

  8. Research on Transport Properties of HFC-227ea

    Institute of Scientific and Technical Information of China (English)

    Lin Shi; Xiaojun Liu; Yuanyuan Duan; Lizhong Han; Mingshan Zhu

    2001-01-01

    HFC-227ea(1,1,1,2,3,3,3-heptafluoropropane) is considered as a promising refrigerant alternative, especially as a component in mixtures, to replace to CFC-12, HCFC-22 and R502. But reliable transport properties data for HFC-227ea are very limited. In this paper, experimental data of viscosity along the saturation line and gaseous thermal conductivity of HFC-227ea are given. The viscosity of HFC-227ea was measured with a capillary viscometer at temperatures between 263.15 K and 333.15 K along the saturation line and its uncertainty of the results is estimated to be no more than +3%. The thermal conductivity of gaseous HFC-227ea was also measured with a transient hot-wire instrument at temperatures between 259.28 K and 341.75 K and pressures up to 1.289MPa, and its uncertainty of the results is estimated to be less than +1%.

  9. Coarse grained modeling of transport properties in monoclonal antibody solution

    Science.gov (United States)

    Swan, James; Wang, Gang

    Monoclonal antibodies and their derivatives represent the fastest growing segment of the bio pharmaceutical industry. For many applications such as novel cancer therapies, high concentration, sub-cutaneous injections of these protein solutions are desired. However, depending on the peptide sequence within the antibody, such high concentration formulations can be too viscous to inject via human derived force alone. Understanding how heterogenous charge distribution and hydrophobicity within the antibodies leads to high viscosities is crucial to their future application. In this talk, we explore a coarse grained computational model of therapeutically relevant monoclonal antibodies that accounts for electrostatic, dispersion and hydrodynamic interactions between suspended antibodies to predict assembly and transport properties in concentrated antibody solutions. We explain the high viscosities observed in many experimental studies of the same biologics.

  10. Soil properties and preferential solute transport at the field scale

    DEFF Research Database (Denmark)

    Koestel, J K; Minh, Luong Nhat; Nørgaard, Trine

    An important fraction of water flow and solute transport through soil takes place through preferential flow paths. Although this had been already observed in the nineteenth century, it had been forgotten by the scientific community until it was rediscovered during the 1970s. The awareness...... of the relevance of preferential flow was broadly re-established in the community by the early 1990s. However, since then, the notion remains widespread among soil scientists that the occurrence and strength of preferential flow cannot be predicted from measurable proxy variables such as soil properties or land...... management practices (e.g. Beven, K., 1991, modeling preferential flow - an uncertain future, Preferential Flow, 1-11). In our study, we present evidence that disproves this notion. We evaluated breakthrough curve experiments under a constant irrigation rate of 1 cm/h conducted on 65 soil columns (20 cm...

  11. Theoretical studies of the transport property of oligosilane

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The transport mechanisms of four-conjugated systems were comparatively studied by combining ATK and Gaussian 03 calculations.It was found that the charge-doped oligosilane behaved in a different way from the boron doped and phosphorus doped oligosilanes in terms of the transmission property.The charge-doped oligosilane showed almost no conductivity owing to the damage of the electron transfer path by charge-doping.By contrast,the boron doped and phosphorus doped oligosilanes were demonstrated to be good semiconductors and NDR behavior was observed for them.This is a reasonable result after the analysis of the transmission spectra,MPSH states,energy gap,conjugation effect,and scattering effect.

  12. Electron Transport Materials: Synthesis, Properties and Device Performance

    Energy Technology Data Exchange (ETDEWEB)

    Cosimbescu, Lelia; Wang, Liang; Helm, Monte L.; Polikarpov, Evgueni; Swensen, James S.; Padmaperuma, Asanga B.

    2012-06-01

    We report the design, synthesis and characterization, thermal and photophysical properties of two silane based electron transport materials, dibenzo[b,d]thiophen-2-yltriphenylsilane (Si{phi}87) and (dibenzo[b,d]thiophen-2-yl)diphenylsilane (Si{phi}88) and their performance in blue organic light emitting devices (OLEDs). The utility of these materials in blue OLEDs with iridium (III) bis[(4,6-difluorophenyl)-pyridinato-N,C']picolinate (Firpic) as the phosphorescent emitter was demonstrated. Using the silane Si{phi}87 as the electron transport material (ETm) an EQE of 18.2% was obtained, with a power efficiency of 24.3 lm/W (5.8V at 1mA/cm{sup 2}), in a heterostructure. When Si{phi}88 is used, the EQE is 18.5% with a power efficiency of 26.0 lm/W (5.5V at 1mA/cm{sup 2}).

  13. Compaction and transport properties of newly replicated Caulobacter crescentus DNA.

    Science.gov (United States)

    Hong, Sun-Hae; McAdams, Harley H

    2011-12-01

    Upon initiating replication of the Caulobacter chromosome, one copy of the parS centromere remains at the stalked pole; the other moves to the distal pole. We identified the segregation dynamics and compaction characteristics of newly replicated Caulobacter DNA during transport (highly variable from cell to cell) using time-lapse fluorescence microscopy. The parS centromere and a length (also highly variable) of parS proximal DNA on each arm of the chromosome are segregated with the same relatively slow transport pattern as the parS locus. Newly replicated DNA further than about 100 kb from parS segregates with a different and faster pattern, while loci at 48 kb from parS segregate with the slow pattern in some cells and the fast pattern in others. The observed parS-proximal DNA compaction characteristics have scaling properties that suggest the DNA is branched. HU2-deletion strains exhibited a reduced compaction phenotype except near the parS site where only the ΔHU1ΔHU2 double mutant had a compaction phenotype. The chromosome shows speed-dependent extension during translocation suggesting the DNA polymer is under tension. While DNA segregation is highly reliable and succeeds in virtually all wild-type cells, the high degree of cell to cell variation in the segregation process is noteworthy.

  14. Transport properties of ultrathin black phosphorus on hexagonal boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Doganov, Rostislav A.; Özyilmaz, Barbaros [Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, 117546 Singapore (Singapore); Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore (Singapore); Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, 28 Medical Drive, 117456 Singapore (Singapore); Koenig, Steven P.; Yeo, Yuting [Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, 117546 Singapore (Singapore); Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore (Singapore); Watanabe, Kenji; Taniguchi, Takashi [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan)

    2015-02-23

    Ultrathin black phosphorus, or phosphorene, is a two-dimensional material that allows both high carrier mobility and large on/off ratios. Similar to other atomic crystals, like graphene or layered transition metal dichalcogenides, the transport behavior of few-layer black phosphorus is expected to be affected by the underlying substrate. The properties of black phosphorus have so far been studied on the widely utilized SiO{sub 2} substrate. Here, we characterize few-layer black phosphorus field effect transistors on hexagonal boron nitride—an atomically smooth and charge trap-free substrate. We measure the temperature dependence of the field effect mobility for both holes and electrons and explain the observed behavior in terms of charged impurity limited transport. We find that in-situ vacuum annealing at 400 K removes the p-doping of few-layer black phosphorus on both boron nitride and SiO{sub 2} substrates and reduces the hysteresis at room temperature.

  15. Electronic transport properties of copper and gold at atomic scale

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadzadeh, Saeideh

    2010-11-23

    The factors governing electronic transport properties of copper and gold atomic-size contacts are theoretically examined in the present work. A two-terminal conductor using crystalline electrodes is adopted. The non-equilibrium Green's function combined with the density functional tight-binding method is employed via gDFTB simulation tool to calculate the transport at both equilibrium and non-equilibrium conditions. The crystalline orientation, length, and arrangement of electrodes have very weak influence on the electronic characteristics of the considered atomic wires. The wire width is found to be the most effective geometric aspect determining the number of conduction channels. The obtained conductance oscillation and linear current-voltage curves are interpreted. To analyze the conduction mechanism in detail, the transmission channels and their decomposition to the atomic orbitals are calculated in copper and gold single point contacts. The presented results offer a possible explanation for the relation between conduction and geometric structure. Furthermore, the results are in good agreement with available experimental and theoretical studies. (orig.)

  16. Transport properties of liquid metal hydrogen under high pressures

    Science.gov (United States)

    Brown, R. C.; March, N. H.

    1972-01-01

    A theory is developed for the compressibility and transport properties of liquid metallic hydrogen, near to its melting point and under high pressure. The interionic force law is assumed to be of the screened Coulomb type, because hydrogen has no core electrons. The random phase approximation is used to obtain the structure factor S(k) of the system in terms of the Fourier transform of this force law. The long wavelenth limit of the structure factor S(o) is related to the compressibility, which is much lower than that of alkali metals at their melting points. The diffusion constant at the melting point is obtained in terms of the Debye frequency, using a frequency spectrum analogous with the phonon spectrum of a solid. A similar argument is used to obtain the combined shear and bulk viscosities, but these depend also on S(o). The transport coefficients are found to be about the same size as those of alkali metals at their melting points.

  17. Predicting the transport properties of sedimentary rocks from microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Schlueter, Erika M. [Univ. of California, Berkeley, CA (United States)

    1995-01-01

    Understanding transport properties of sedimentary rocks, including permeability, relative permeability, and electrical conductivity, is of great importance for petroleum engineering, waste isolation, environmental restoration, and other applications. These transport properties axe controlled to a great extent by the pore structure. How pore geometry, topology, and the physics and chemistry of mineral-fluid and fluid-fluid interactions affect the flow of fluids through consolidated/partially consolidated porous media are investigated analytically and experimentally. Hydraulic and electrical conductivity of sedimentary rocks are predicted from the microscopic geometry of the pore space. Cross-sectional areas and perimeters of individual pores are estimated from two-dimensional scanning electron microscope (SEM) photomicrographs of rock sections. Results, using Berea, Boise, Massilon, and Saint-Gilles sandstones show close agreement between the predicted and measured permeabilities. Good to fair agreement is found in the case of electrical conductivity. In particular, good agreement is found for a poorly cemented rock such as Saint-Gilles sandstone, whereas the agreement is not very good for well-cemented rocks. The possible reasons for this are investigated. The surface conductance contribution of clay minerals to the overall electrical conductivity is assessed. The effect of partial hydrocarbon saturation on overall rock conductivity, and on the Archie saturation exponent, is discussed. The region of validity of the well-known Kozeny-Carman permeability formulae for consolidated porous media and their relationship to the microscopic spatial variations of channel dimensions are established. It is found that the permeabilities predicted by the Kozeny-Carman equations are valid within a factor of three of the observed values methods.

  18. Soil Microbial Activity Elucidates Unique Soil Carbon Transport Patterns within Resource Islands on Semi-Arid Hillslopes

    Science.gov (United States)

    McLain, J. E.; Lohse, K. A.; Harman, C. J.

    2012-12-01

    . Net CO2 evolution patterns showed positive correlations with soil organic matter in the 0-5 cm layer. Our research used several methods to show that slope-dependent transport processes may play a significant role in shaping the spatial distribution of vegetation and ecosystem processes on hillslopes by inverting the flow of resources from inter-space sources to vegetated sinks, disrupting the reinforcing feedback that maintains the separation between these areas.

  19. Material simulation of charge carrier transport properties of polymer dielectrics

    Science.gov (United States)

    Unge, Mikael; Christen, Thomas; Törnkvist, Christer; ABB Corporate Research Team

    To understand electron and hole transport in solid material requires to know its electronic properties, i.e. the density of states (DOS) and whether the states are spatially localized or delocalized. The states closest to the band edges may be localized, states further away can be delocalized. This transition from localized to delocalized states determines the mobility edge, above the mobility edge the mobility is expected to be high. A real polymer is never perfect; it contains a number of oxidative states, bonding defects and molecular impurities. These imperfections yield electronic states that can appear in the band gap of the polymer, traps. Traps can be shallow, i.e. close to the band edges, from these states the charge carrier easily can jump to a state in the band edge or another shallow state. Other traps can be deep, in these states it is likely that the charge carrier remains and become immobile. All these properties related to the electronic structure of the polymer, including its defects, affects the conductivity of the polymer. Linear scaling Density Functional Theory has been applied to calculate electronic structure of amorphous polyethylene. In particular DOS, trap levels and mobility edges are studied.

  20. Optical and Transport Properties of Organic Molecules: Methods and Applications

    Science.gov (United States)

    Strubbe, David Alan

    Organic molecules are versatile and tunable building blocks for technology, in nanoscale and bulk devices. In this dissertation, I will consider some important applications for organic molecules involving optical and transport properties, and develop methods and software appropriate for theoretical calculations of these properties. Specifically, we will consider second-harmonic generation, a nonlinear optical process; photoisomerization, in which absorption of light leads to mechanical motion; charge transport in junctions formed of single molecules; and optical excitations in pentacene, an organic semiconductor with applications in photovoltaics, optoelectronics, and flexible electronics. In the Introduction (Chapter 1), I will give an overview of some phenomenology about organic molecules and these application areas, and discuss the basics of the theoretical methodology I will use: density-functional theory (DFT), time-dependent density-functional theory (TDDFT), and many-body perturbation theory based on the GW approximation. In the subsequent chapters, I will further discuss, develop, and apply this methodology. 2. I will give a pedagogical derivation of the methods for calculating response properties in TDDFT, with particular focus on the Sternheimer equation, as will be used in subsequent chapters. I will review the many different response properties that can be calculated (dynamic and static) and the appropriate perturbations used to calculate them. 3. Standard techniques for calculating response use either integer occupations (as appropriate for a system with an energy gap) or fractional occupations due to a smearing function, used to improve convergence for metallic systems. I will present a generalization which can be used to compute response for a system with arbitrary fractional occupations. 4. Chloroform (CHCl3) is a small molecule commonly used as a solvent in measurements of nonlinear optics. I computed its hyperpolarizability for second

  1. Elastic and transport properties in polycrystals of crackedgrains: Cross-property relations and microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, J.G.

    2007-10-02

    Some arguments of Bristow (1960) concerning the effects of cracks on elastic and transport (i.e., electrical or thermal conduction) properties of cold-worked metals are reexamined. The discussion is posed in terms of a modern understanding of bounds and estimates for physical properties of polycrystals--in contrast to Bristow's approach using simple mixture theory. One type of specialized result emphasized here is the cross-property estimates and bounds that can be obtained using the methods presented. Our results ultimately agree with those of Bristow, i.e., confirming that microcracking is not likely to be the main cause of the observed elastic behavior of cold-worked metals. However, it also becomes clear that the mixture theory approach to the analysis is too simple and that crack-crack interactions are necessary for proper quantitative study of Bristow's problem.

  2. Self-Assembled Magnetic Metallic Nanopillars in Ceramic Matrix with Anisotropic Magnetic and Electrical Transport Properties.

    Science.gov (United States)

    Su, Qing; Zhang, Wenrui; Lu, Ping; Fang, Shumin; Khatkhatay, Fauzia; Jian, Jie; Li, Leigang; Chen, Fanglin; Zhang, Xinghang; MacManus-Driscoll, Judith L; Chen, Aiping; Jia, Quanxi; Wang, Haiyan

    2016-08-10

    Ordered arrays of metallic nanopillars embedded in a ceramic matrix have recently attracted considerable interest for their multifunctionality in advanced devices. A number of hurdles need to be overcome for achieving practical devices, including selections of metal-ceramic combination, creation of tunable and ordered structure, and control of strain state. In this article, we demonstrate major advances to create such a fine nanoscale structure, i.e., epitaxial self-assembled vertically aligned metal-ceramic composite, in one-step growth using pulsed laser deposition. Tunable diameter and spacing of the nanopillars can be achieved by controlling the growth parameters such as deposition temperature. The magnetic metal-ceramic composite thin films demonstrate uniaxial anisotropic magnetic properties and enhanced coercivity compared to that of bulk metal. The system also presents unique anisotropic electrical transport properties under in-plane and out-of-plane directions. This work paves a new avenue to fabricate epitaxial metal-ceramic nanocomposites, which can simulate broader future explorations in nanocomposites with novel magnetic, optical, electrical, and catalytical properties.

  3. Carbon materials with quasi-graphene layers: The dielectric, percolation properties and the electronic transport mechanism

    Institute of Scientific and Technical Information of China (English)

    Lu Ming-Ming; Yuan Jie; Wen Bo; Liu Jia; Cao Wen-Qiang; Cao Mao-Sheng

    2013-01-01

    We investigate the dielectric properties of muhi-walled carbon nanotubes (MWCNTs) and graphite filling in SiO2 with the filling concentration of 2-20 wt.% in the frequency range of 102-107 Hz.M WCNTs and graphite have general electrical properties and percolation phenomena owing to their quasi-structure made up of graphene layers.Both permittivity ε and conductivity σ exhibit jumps around the percolation threshold.Variations of dielectric properties of the composites are in agreement with the percolation theory.All the percolation phenomena are determined by hopping and migrating electrons,which are attributed to the special electronic transport mechanism of the fillers in the composites.However,the twin-percolation phenomenon exists when the concentration of MWCNTs is between 5-10 wt.% and 15-20 wt.% in the MWCNTs/SiO2 composites,while in the graphite/SiO2 composites,there is only one percolation phenomenon in the graphite concentration of 10-15 wt.%.The unique twin-percolation phenomenon of MWCNTs/SiO2 is described and attributed to the electronic transfer mechanism,especially the network effect of MWCNTs in the composites.The network formation plays an essential role in determining the second percolation threshold of MWCNTs/SiO2.

  4. Transport properties of damaged materials. Cementitious barriers partnership

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2014-11-01

    The objective of the Cementitious Barriers Partnership (CBP) project is to develop tools to improve understanding and prediction of the long-term structural, hydraulic, and chemical performance of cementitious barriers used in low-level waste storage applications. One key concern for the long-term durability of concrete is the degradation of the cementitious matrix, which occurs as a result of aggressive chemical species entering the material or leaching out in the environment, depending on the exposure conditions. The objective of the experimental study described in this report is to provide experimental data relating damage in cementitious materials to changes in transport properties, which can eventually be used to support predictive model development. In order to get results within a reasonable timeframe and to induce as much as possible uniform damage level in materials, concrete samples were exposed to freezing and thawing (F/T) cycles. The methodology consisted in exposing samples to F/T cycles and monitoring damage level with ultrasonic pulse velocity measurements. Upon reaching pre-selected damage levels, samples were tested to evaluate changes in transport properties. Material selection for the study was motivated by the need to get results rapidly, in order to assess the relevance of the methodology. Consequently, samples already available at SIMCO from past studies were used. They consisted in three different concrete mixtures cured for five years in wet conditions. The mixtures had water-to-cement ratios of 0.5, 0.65 and 0.75 and were prepared with ASTM Type I cement only. The results showed that porosity is not a good indicator for damage caused by the formation of microcracks. Some materials exhibited little variations in porosity even for high damage levels. On the other hand, significant variations in tortuosity were measured in all materials. This implies that damage caused by internal pressure does not necessarily create additional pore space in

  5. Cementitious barriers partnership transport properties of damaged materials

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2014-11-01

    The objective of the Cementitious Barriers Partnership (CBP) project is to develop tools to improve understanding and prediction of the long-term structural, hydraulic, and chemical performance of cementitious barriers used in low level waste storage applications. One key concern for the long-term durability of concrete is the degradation of the cementitious matrix, which occurs as a result of aggressive chemical species entering the material or leaching out in the environment, depending on the exposure conditions. The objective of the experimental study described in this report is to provide experimental data relating damage in cementitious materials to changes in transport properties, which can eventually be used to support predictive model development. In order to get results within a reasonable timeframe and to induce as much as possible uniform damage level in materials, concrete samples were exposed to freezing and thawing (F/T) cycles. The methodology consisted in exposing samples to F/T cycles and monitoring damage level with ultrasonic pulse velocity measurements. Upon reaching pre-selected damage levels, samples were tested to evaluate changes in transport properties. Material selection for the study was motivated by the need to get results rapidly, in order to assess the relevance of the methodology. Consequently, samples already available at SIMCO from past studies were used. They consisted in three different concrete mixtures cured for five years in wet conditions. The mixtures had water-to-cement ratios of 0.5, 0.65 and 0.75 and were prepared with ASTM Type I cement only. The results showed that porosity is not a good indicator for damage caused by the formation of microcracks. Some materials exhibited little variations in porosity even for high damage levels. On the other hand, significant variations in tortuosity were measured in all materials. This implies that damage caused by internal pressure do not necessarily creates additional pore space in

  6. Transport properties of ion implanted poly (p-phenylene vinylene)

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, B. (LEPOFI, Faculte des Sciences, 87 Limoges (France)); Ratier, B. (LEPOFI, Faculte des Sciences, 87 Limoges (France)); Moliton, A. (LEPOFI, Faculte des Sciences, 87 Limoges (France)); Moreau, C. (Cavendish Lab., Univ. of Cambridge, Cambridge (United Kingdom)); Friend, R.H. (Cavendish Lab., Univ. of Cambridge, Cambridge (United Kingdom))

    1993-04-19

    We have studied the effect of ion implantation on transport properties (thermopower S, dc conductivity [sigma], ac conductivity [sigma][sub T]) of poly (p-phenylene vinylene). We have noticed that the thermopower sign is characteristic of the implanted ion (S > 0 for halogen, S < 0 for alkali) at low implantation energy (E [<=] 50 keV). The slope of [sigma] = f (T[sup -1]) varies, with values for activation energy between 32 meV (D = 10[sup 16] ions/cm[sup 2]) and 57 meV (D = 10[sup 15] ions/cm[sup 2]): the activation energy falls as the fluence increases in the case of implantation at low energy (E [<=] 50 keV). AC conductivity has been studied as a function of frequency v (v = 20 Hz - 1 MHz) and of temperatures T (T = 100 K - 380 K). For lower fluences (D = 2.10[sup 15] ions/cm[sup 2]), at low temperatures the ac conductivity shows hopping behaviour, switching to activated behaviour at higher temperatures. For higher fluences (D = 2.10[sup 16] ions/cm[sup 2]) the main processes are thermally activated. Thus for a high implantation energy (E = 250 keV), the related conductivity is less thermally activated and the curve [sigma][sub T] = f (1/T) slightly depends on temperature (hopping mechanism). (orig.)

  7. Transport properties of C and O in UN fuels

    Science.gov (United States)

    Schuler, Thomas; Lopes, Denise Adorno; Claisse, Antoine; Olsson, Pär

    2017-03-01

    Uranium nitride fuel is considered for fast reactors (GEN-IV generation and space reactors) and for light water reactors as a high-density fuel option. Despite this large interest, there is a lack of information about its behavior for in-pile and out-of-pile conditions. From the present literature, it is known that C and O impurities have significant influence on the fuel performance. Here we perform a systematic study of these impurities in the UN matrix using electronic-structure calculations of solute-defect interactions and microscopic jump frequencies. These quantities were calculated in the DFT +U approximation combined with the occupation matrix control scheme, to avoid convergence to metastable states for the 5 f levels. The transport coefficients of the system were evaluated with the self-consistent mean-field theory. It is demonstrated that carbon and oxygen impurities have different diffusion properties in the UN matrix, with O atoms having a higher mobility, and C atoms showing a strong flux coupling anisotropy. The kinetic interplay between solutes and vacancies is expected to be the main cause for surface segregation, as incorporation energies show no strong thermodynamic segregation preference for (001) surfaces compared with the bulk.

  8. Structural and transport properties of directly assembled nanowires

    Science.gov (United States)

    Ozturk, Birol

    Scope and method of study. In this work, we present a systematic study on the assembly and characterization of nanostructures. We employed self and directed assembly methods in order to organize nanostructures. Quantitative film balance studies of self-assembled semiconductor nanoparticles enabled the determination of their effective interparticle potential. As a directed-assembly method, dielectrophoresis was used in the fabrication of interconnects from dispersions of nanostructures between targeted points in external circuitry. Directed electrochemical nanowire assembly (DENA) was developed and used in the fabrication of metallic nanowires from simple salt solutions. The structural and charge transport properties of the assembled nanostructures and the DENA-grown nanowires were characterized. Findings and conclusions. The CdSe nanoparticles of a given diameter were found to behave like hard-disks with significantly smaller diameters. This behavior was attributed to an attractive contribution to the interparticle potential, such as the dipolar potential. We found that nanoparticulate CdS converts to bulk CdS during dielectrophoretic interconnect fabrication. We demonstrated that the dielectrophoretic interconnects fabricated from gold nanorods are nanostructured, limiting their conductivity. DENA technique enabled the single-step growth and low-resistance interconnecting of crystalline diameter-tunable metallic nanowires. The preliminary results of the diameter-dependent resistivity studies with the DENA-grown gold nanowires were consistent with the predicted behavior.

  9. Thermodynamic and transport properties of superconducting Mg10B2.

    Science.gov (United States)

    Finnemore, D K; Ostenson, J E; Bud'ko, S L; Lapertot, G; Canfield, P C

    2001-03-12

    Transport and thermodynamic properties of a sintered pellet of the newly discovered MgB2 superconductor have been measured to determine the characteristic critical magnetic fields and critical current densities. Both resistive transition and magnetization data give similar values of the upper critical field, Hc2, with magnetization data giving dHc2/dT = 0.44 T/K at the transition temperature of Tc = 40.2 K. Close to the transition temperature, magnetization curves are thermodynamically reversible, but at low temperatures the trapped flux can be on the order of 1 T. The value of dHc/dT at Tc is estimated to be about 12 mT/K, a value similar to classical superconductors like Sn. Hence, the Ginzburg-Landau parameter kappa approximately 26. Estimates of the critical supercurrent density, Jc, using hysteresis loops and the Bean model, give critical current densities on the order of 10(5) A/cm2. Hence the supercurrent coupling through the grain boundaries is comparable to intermetallics like Nb3Sn.

  10. Nanostructured semiconductors for thermoelectric energy conversion: Synthesis and transport properties

    Science.gov (United States)

    Sahoo, Pranati

    Increasing energy demands and decreasing natural energy resources have sparked search for alternative clean and renewable energy sources. For instance, currently there is a tremendous interest in thermoelectric and photovoltaic solar energy production technologies. Half-Heusler (HH) alloys are among the most popular material systems presently under widespread investigations for high temperature thermoelectric energy conversion. Approaches to increase the thermoelectric figure of merit (ZT) of HH range from (1) chemical substitution of atoms with different masses within the same atomic position in the crystal structure to optimize carrier concentration and enhance phonon scattering via mass fluctuation and (2) embedding secondary phonon scattering centers in the matrix (nanostructuring) to further reduce thermal conductivity. This work focuses on three material systems. The first part describes the synthesis and properties (thermal conductivity, electrical conductivity, magnetic) of various oxide nanostructures (NiO, Co3O4) which were subsequently used as inclusion phases in a HH matrix to reduce the thermal conductivity. Detailed reviews of the past efforts along with the current effort to optimize synthetic routes are presented. The effects of the synthesis conditions on the thermoelectric properties of compacted pellets of NiO and Co3O4 are also discussed. The second part of the work discusses the development of synthetic strategies for the fabrication of p-type and n-type bulk nanostructured thermoelectric materials made of a half-Heusler matrix based on (Ti,Hf)CoSb, containing nanostructures with full-Heusler (FH) compositions and structures coherently embedded inside the half-Heusler matrix. The role of the nanostructures in the regulation of phonon and charge carrier transports within the half-heusler matrix is extensively discussed by combining transport data and electron microscopy images. It was found that the FH nanoinclusions form staggered

  11. Method for the unique identification of hyperelastic material properties using full-field measures. Application to the passive myocardium material response.

    Science.gov (United States)

    Perotti, Luigi E; Ponnaluri, Aditya V S; Krishnamoorthi, Shankarjee; Balzani, Daniel; Ennis, Daniel B; Klug, William S

    2017-01-18

    Quantitative measurement of the material properties (eg, stiffness) of biological tissues is poised to become a powerful diagnostic tool. There are currently several methods in the literature to estimating material stiffness, and we extend this work by formulating a framework that leads to uniquely identified material properties. We design an approach to work with full-field displacement data-ie, we assume the displacement field due to the applied forces is known both on the boundaries and also within the interior of the body of interest-and seek stiffness parameters that lead to balanced internal and external forces in a model. For in vivo applications, the displacement data can be acquired clinically using magnetic resonance imaging while the forces may be computed from pressure measurements, eg, through catheterization. We outline a set of conditions under which the least-square force error objective function is convex, yielding uniquely identified material properties. An important component of our framework is a new numerical strategy to formulate polyconvex material energy laws that are linear in the material properties and provide one optimal description of the available experimental data. An outcome of our approach is the analysis of the reliability of the identified material properties, even for material laws that do not admit unique property identification. Lastly, we evaluate our approach using passive myocardium experimental data at the material point and show its application to identifying myocardial stiffness with an in silico experiment modeling the passive filling of the left ventricle. Copyright © 2017 John Wiley & Sons, Ltd.

  12. The synthesis and transport properties of the complex salt /TMPD/ /TCNQ/2

    Science.gov (United States)

    Somoano, R.; Hadek, V.; Yen, S. P. S.; Rembaum, A.; Deck, R.

    1975-01-01

    The syntheses and transport properties of the complex salt /TMPD/ /TCNQ/2 are described. At high temperatures, the complex is a magnetic semiconductor with transport properties intermediate between those found in the highly conducting and poorly conducting TCNQ salts. The complex undergoes a transition below 50-60 K to a state exhibiting singlet-triplet behavior with weakly alternating exchange coupling.

  13. Opto-electronic and quantum transport properties of semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Sabathil, M.

    2005-01-01

    In this work a novel and efficient method for the calculation of the ballistic transport properties of open semiconductor nanostructures connected to external reservoirs is presented. It is based on the Green's function formalism and reduces the effort to obtain the transmission and the carrier density to a single solution of a hermitian eigenvalue problem with dimensions proportional to the size of the decoupled device and the multiple inversion of a small matrix with dimensions proportional to the size of the contacts to the leads. Using this method, the 4-band GaAs hole transport through a 2-dimensional three-terminal T-junction device, and the resonant tunneling current through a 3-dimensional InAs quantum dot molecule embedded into an InP heterostructure have been calculated. The further extension of the method into a charge self-consistent scheme enables the efficient prediction of the IV-characteristics of highly doped nanoscale field effect transistors in the ballistic regime, including the influence of quasi bound states and the exchange-correlation interaction. Buettiker probes are used to emulate the effect of inelastic scattering on the current for simple 1D devices, systematically analyzing the dependence of the density of states and the resulting self-consistent potential on the scattering strength. The second major topic of this work is the modeling of the optical response of quantum confined neutral and charged excitons in single and coupled self-assembled InGaAs quantum dots. For this purpose the existing device simulator nextnano{sup 3} has been extended to incorporate particle-particle interactions within the means of density functional theory in local density approximation. In this way the exciton transition energies for neutral and charged excitons as a function of an externally applied electric field have been calculated, revealing a systematic reduction of the intrinsic dipole with the addition of extra holes to the exciton, a finding

  14. Possible Evidence for Stripes in the Transport Properties of PLCCO

    Science.gov (United States)

    Ando, Yoichi

    2004-03-01

    It is now recognized that the charged stripes exist surely in La_1.6-xNd_0.4Sr_xCuO_4, probably in La_2-xSr_xCuO4 (LSCO), and possibly in YBa_2Cu_3O_y. It is also recognized that an intrinsic electronic inhomogeneity exists in Bi_2Sr_2CaCu_2O_8. These observations naturally lead to a notion that some form of electron self-organization might be fundamentally related to the high-Tc superconductivity. In this context, of particular interest is whether stripes (or some electron self-organizations) exist in electron-doped cuprates as well. To investigate this issue, we took notice of two peculiar features in lightly hole-doped LSCO: (1) It was demonstrated that the anisotropic phonon heat transport is a good probe of the stripe formation in lightly-doped LSCO; namely, the spin stripes in this system are well-ordered in the CuO2 planes but are disordered along the c axis, which causes the c-axis phonons alone to be anomalously scattered [X. F. Sun et al., PRB 67, 104503 (2003)]. (2) It was also demonstrated that the in-plane resistivity ρ_ab of lightly-doped LSCO crystals shows metallic behavior (dρ_ab/dT > 0) even in the long-range-ordered Néel state, where the hole mobility is surprisingly similar to that in optimally-doped samples; such an unusual metallic behavior can naturally be understood if doped holes form self-organized ``rivers" whose distance changes with doping [Y. Ando et al., PRL 87, 017001 (2001)]. Taking these features as signatures of stripes, we examined the transport properties of lightly electron-doped Pr_1.3-xLa_0.7Ce_xCuO4 (PLCCO). It was found that both of the above unusual features are observed also in lightly-doped PLCCO, which gives possible evidence for stripes in electron-doped cuprates.

  15. Transport properties of multicomponent thermal plasmas: Grad method versus Chapman-Enskog method

    Energy Technology Data Exchange (ETDEWEB)

    Porytsky, P. [Institute for Nuclear Research, 03680 Kyiv (Ukraine); Krivtsun, I.; Demchenko, V. [Paton Welding Institute, 03680 Kyiv (Ukraine); Reisgen, U.; Mokrov, O.; Zabirov, A. [RWTH Aachen University, ISF-Welding and Joining Institute, 52062 Aachen (Germany); Gorchakov, S.; Timofeev, A.; Uhrlandt, D. [Leibniz Institute for Plasma Science and Technology (INP Greifswald), 17489 Greifswald (Germany)

    2013-02-15

    Transport properties (thermal conductivity, viscosity, and electrical conductivity) for multicomponent Ar-Fe thermal plasmas at atmospheric pressure have been determined by means of two different methods. The transport coefficients set based on Grad's method is compared with the data obtained when using the Chapman-Enskog's method. Results from both applied methods are in good agreement. It is shown that the Grad method is suitable for the determination of transport properties of the thermal plasmas.

  16. Electrical Transport Properties of Ni95Ti5 Catalyzed Multi wall Carbon Nanotubes Film

    Directory of Open Access Journals (Sweden)

    Zishan Husain Khan

    2009-01-01

    Full Text Available Carbon nanotubes (CNTs can be understood as one or more graphite sheets rolled up into a seamless cylinder. CNTs have gained much attention and scientific interest due to their unique properties and potential applications since their discovery in 1991. In the present work, we have deposited Ni95Ti5 film using thermal deposition method. Finally, the Ni95Ti5 catalyzed multi wall carbon nanotubes (MWNTs are grown on silicon substrate using low pressure chemical vapor deposition (LPCVD method and the electrical transport properties of this MWNTs film are studied over a temperature range (284–4K to explain the conduction mechanism. We have suggested two types of conduction mechanism for the entire temperature range. For the temperature region (284–220K, the conduction is due to thermally activated process, whereas the conduction takes place via variable range hopping (VRH for the temperature range of (220–4K. The VRH mechanism changes from three dimensions to two dimensions as we move down to the temperature below 50K. Therefore, the data for the temperature region (220–50K is plotted for three dimensional variable range hopping (3D VRH model and the two dimensional variable range hopping (2D VRH for lower temperature range of (50–4K. These VRH models give a good fit to the experimental data. Using these models, we have calculated various interesting electrical parameters such as activation energy, density of states, hopping distance and hopping energy.

  17. High field transport properties of a bilayer graphene

    Science.gov (United States)

    Bhargavi, K. S.; Kubakaddi, S. S.

    2014-02-01

    The high electric field transport properties namely, hot electron energy loss rate P, momentum loss rate Q, electron temperature Te and drift velocity Vd are studied theoretically in a bilayer graphene (BLG) by employing the momentum and energy balance technique. P and Q are investigated as a function of Te by considering the electron interaction with the acoustic phonons (APs) and the surface polar phonons (SPPs). In the Bloch-Grüneisen regime P (Q) due to APs is ~Te4 (Te2.5), with a new feature of a kink appearing due to the chiral nature of the electrons. The predicted Te4 is consistent with the recent experimental observation of heat resistance (Yan et al. Nature Nanotechnology 3 (2012) 472 [35]). Hot phonon effect is taken into account for SPPs. A dip has been observed in the hot phonon distribution of SPPs, a new feature, which is not found in conventional two-dimensional electron gas, and this can be attributed to the chiral nature of the electrons. P (Q) due to SPPs is found to be dominant at about Te>150 (180) K for a lattice temperature T=4.2 K. It is observed that the hot phonon effect is found to reduce P and Q due to SPPs significantly. Te and Vd are calculated as a function of the electric field E by taking into account the additional channels for momentum relaxation due to Coulomb impurity (CI) and short-range disorder (SD). Te is found to increase with the increasing electric field and is significantly enhanced by the hot phonon effect. Low field Vd is found to be limited by CI, SD and APs and in the high field region it reaches a near saturation value. The hot phonon effect tends to reduce the value of Vd. The presence of disorders CI and SD reduces Vd significantly and in clean samples larger saturation velocity can be achieved at a relatively smaller E.

  18. Preduction of transport properties of gases using classical nonspherical models

    Energy Technology Data Exchange (ETDEWEB)

    Verlin, J.D.

    1976-01-01

    The general formulation of the classical kinetic theory, which is needed to predict transport properties of gases in situations where the hydrodynamic equations are valid, is reviewed. A rigid convex model of tetrahedral symmetry is used to predict the Senftleben-Beenakker effect of a static magnetic field on the thermal conductivity and viscosity of pure CH/sub 4/, CD/sub 4/ and CF/sub 4/. The parameters of the model are optimized and are found to assume physically reasonable values. The calculations agree with experiment to a degree comparable to that of similar work on diatomic molecules. A generalized scattering cross section, ..gamma.., is defined which can be evaluated exactly for the limiting cases of a spherical soft potential and rigid ovaloids. For a general soft nonspherical interaction of the Kihara type, a suitable approximation for the momentum dependence is made with the following attributes: ..gamma.. reduces to the form for soft sphere and rigid ovaloid in the limits and the resulting matrix elements of the collision operator can be written in terms of the familiar ..cap omega..* integrals. This formulation is used to investigate thermal diffusion in binary isotopic mixtures of CO. Calculations are made in an 80/sup 0/K to 300/sup 0/K range which includes the inversion temperatures for all mixtures studied. Thermal conductivity and diffusion coefficients of CO are also calculated. The parameters of the model can be adjusted to account for the major features of the experimental data. The physical significance of the parameters is discussed. (auth)

  19. A unique magnesium-based 3D MOF with nanoscale cages and temperature dependent selective gas sorption properties.

    Science.gov (United States)

    Huang, Yong-Liang; Gong, Yun-Nan; Jiang, Long; Lu, Tong-Bu

    2013-02-28

    A porous Mg-based 3D metal-organic framework with unique nanoscale cages and two-fold interpenetrating pcu nets has been synthesized and characterized. It shows gas-uptake capacities for N(2), H(2), O(2) and CO(2) at low temperatures and selective adsorption of CO(2) over O(2) and N(2) at room temperature.

  20. Structural Properties of the Brazilian Air Transportation Network.

    Science.gov (United States)

    Couto, Guilherme S; da Silva, Ana Paula Couto; Ruiz, Linnyer B; Benevenuto, Fabrício

    2015-09-01

    The air transportation network in a country has a great impact on the local, national and global economy. In this paper, we analyze the air transportation network in Brazil with complex network features to better understand its characteristics. In our analysis, we built networks composed either by national or by international flights. We also consider the network when both types of flights are put together. Interesting conclusions emerge from our analysis. For instance, Viracopos Airport (Campinas City) is the most central and connected airport on the national flights network. Any operational problem in this airport separates the Brazilian national network into six distinct subnetworks. Moreover, the Brazilian air transportation network exhibits small world characteristics and national connections network follows a power law distribution. Therefore, our analysis sheds light on the current Brazilian air transportation infrastructure, bringing a novel understanding that may help face the recent fast growth in the usage of the Brazilian transport network.

  1. Unique Gene-Silencing and Structural Properties of 2;#8242;-Fluoro-Modified siRNAs

    Energy Technology Data Exchange (ETDEWEB)

    Manoharan, Muthiah; Akinc, Akin; Pandey, Rajendra K.; Qin, June; Hadwiger, Philipp; John, Matthias; Mills, Kathy; Charisse, Klaus; Maier, Martin A.; Nechev, Lubomir; Greene, Emily M.; Pallan, Pradeep S.; Rozners, Eriks; Rajeev, Kallanthottathil G.; Egli, Martin (Binghamton); (Alnylam Pharm.); (Vanderbilt)

    2015-10-15

    With little or no negative impact on the activity of small interfering RNAs (siRNAs), regardless of the number of modifications or the positions within the strand, the 2'-deoxy-2'-fluoro (2'-F) modification is unique. Furthermore, the 2'-F-modified siRNA (see crystal structure) was thermodynamically more stable and more nuclease-resistant than the parent siRNA, and produced no immunostimulatory response.

  2. Computer program for calculation of thermodynamic and transport properties of complex chemical systems

    Science.gov (United States)

    Svehla, R. A.; Mcbride, B. J.

    1973-01-01

    Program performs calculations such as chemical equilibrium for assigned thermodynamic states, theoretical rocket performance for both equilibrium and frozen compositions during expansion, incident and reflected shock properties, and Chapman-Jouget detonation properties. Features include simplicity of input and storage of all thermodynamic and transport property data on master tape.

  3. Understanding hopping transport and thermoelectric properties of conducting polymers

    OpenAIRE

    Ihnatsenka, Siarhei; Crispin, Xavier; Zozoulenko, Igor

    2015-01-01

    We calculate the conductivity sigma and the Seebeck coefficient S for the phonon-assisted hopping transport in conducting polymers poly(3,4-ethylenedioxythiophene) or PEDOT, experimentally studied by Bubnova et al. [J. Am. Chem. Soc. 134, 16456 (2012)]. We use the Monte Carlo technique as well as the semianalytical approach based on the transport energy concept. We demonstrate that both approaches show a good qualitative agreement for the concentration dependence of sigma and S. At the same t...

  4. Charge and discharge curves: a unique reliable evidence for the electrochemical properties of LiCoO2

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    X-ray diffraction (XRD), the traditional characterization method to detect the electrochemical properties of LiCoO2, was doubted. The XRD patterns of three types of LiCoO2, with similar electrochemical properties, present differences. For the same type of LiCoO2, different XRD patterns were obtained when the sample preparing methods were different, because of preferred orientation. The nonstandard method to prepare XRD powder samples can eliminate preferred orientation. The reliable evidence to detect electrochemical properties is still charge and discharge curves.

  5. Detecting the local transport properties and the dimensionality of transport of epitaxial graphene by a multi-point probe approach

    DEFF Research Database (Denmark)

    Barreto, Lucas; Perkins, Edward; Johannsen, Jens;

    2013-01-01

    The electronic transport properties of epitaxial monolayer graphene (MLG) and hydrogen-intercalated quasi free-standing bilayer graphene (QFBLG) on SiC(0001) are investigated by micro multi-point probes. Using a probe with 12 contacts, we perform four-point probe measurements with the possibility...

  6. Analysis Of Transport Properties of Mechanically Alloyed Lead Tin Telluride

    Science.gov (United States)

    Krishna, Rajalakshmi

    these inclusions would not be less than that expected in alloys without these inclusions while the portion of the thermal conductivity that is not due to charge carriers (the lattice thermal conductivity) would be less than what would be expected from alloys that do not have these inclusions. Furthermore, it would be possible to approximate the observed changes in the electrical and thermal transport properties using existing physical models for the scattering of electrons and phonons by small inclusions. The approach taken to investigate this hypothesis was to first experimentally characterize the mobile carrier concentration at room temperature along with the extent and type of secondary phase inclusions present in a series of three mechanically alloyed Pb1-xSnxTe alloys with different Sn content. Second, the physically based computational model was developed. This model was used to determine what the electronic conductivity, Seebeck coefficient, total thermal conductivity, and the portion of the thermal conductivity not due to mobile charge carriers would be in these particular Pb1-x SnxTe alloys if there were to be no secondary phase inclusions. Third, the electronic conductivity, Seebeck coecient and total thermal conductivity was experimentally measured for these three alloys with inclusions present at elevated temperatures. The model predictions for electrical conductivity and Seebeck coefficient were directly compared to the experimental elevated temperature electrical transport measurements. The computational model was then used to extract the lattice thermal conductivity from the experimentally measured total thermal conductivity. This lattice thermal conductivity was then compared to what would be expected from the alloys in the absence of secondary phase inclusions. Secondary phase inclusions were determined by X-ray diraction analysis to be present in all three alloys to a varying extent. The inclusions were found not to significantly degrade electrical

  7. State-to-state kinetics and transport properties of electronically excited N and O atoms

    Science.gov (United States)

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

    2016-11-01

    A theoretical model of transport properties in electronically excited atomic gases in the state-to-state approach is developed. Different models for the collision diameters of atoms in excited states are discussed, and it is shown that the Slater-like models can be applied for the state-resolved transport coefficient calculations. The influence of collision diameters of N and O atoms with electronic degrees of freedom on the transport properties is evaluated. Different distributions on the electronic energy are considered for the calculation of transport coefficients. For the Boltzmann-like distributions at temperatures greater than 15000 K, an important effect of electronic excitation on the thermal conductivity and viscosity coefficients is found; the coefficients decrease significantly when many electronic states are taken into account. It is shown that under hypersonic reentry conditions the impact of collision diameters on the transport properties is not really important since the populations of high levels behind the shock waves are low.

  8. Facile synthesis and electron transport properties of NiO nanostructures investigated by scanning tunneling microscopy

    Directory of Open Access Journals (Sweden)

    Govind Mallick

    2017-08-01

    Full Text Available Due to their unique chemical, thermal, electronic and photonic properties, low -dimensional transition metal oxides, especially NiO, have attracted great deal of attention for potential applications in a wide range of technologies, such as, sensors, electrochromic coatings and self-healing materials. However, their synthesis involves multi-step complex procedures that in addition to being expensive, further introduce impurities. Here we present a low cost facile approach to synthesize uniform size NiO nanoparticles (NPs from hydrothermally grown Ni(OH2. Detailed transmission electron microscopic analysis reveal the average size of NiO NPs to be around 29 nm. The dimension of NiO NP is also corroborated by the small area scanning tunneling microscope (STM measurements. Further, we investigate electron transport characteristics of newly synthesized Ni(OH2 and NiO nanoparticles on p-type Si substrate using scanning tunneling microscopy. The conductivity of Ni(OH2 and NiO are determined to be 1.46x10-3 S/cm and 2.37x10-5 S/cm, respectively. The NiO NPs exhibit a lower voltage window (∼0.7 V electron tunneling than the parent Ni(OH2.

  9. A New Star-shaped Carbazole Derivative with Polyhedral Oligomeric Silsesquioxane Core: Crystal Structure and Unique Photoluminescence Property.

    Science.gov (United States)

    Xu, Zixuan; Yu, Tianzhi; Zhao, Yuling; Zhang, Hui; Zhao, Guoyun; Li, Jianfeng; Chai, Lanqin

    2016-01-01

    A new inorganic–organic hybrid material based on polyhedral oligomeric silsesquioxane (POSS) capped with carbazolyl substituents, octakis[3-(carbazol-9-yl)propyldimethylsiloxy]-silsesquioxane (POSS-8Cz), was successfully synthesized and characterized. The X-ray crystal structure of POSS-8Cz were described. The photophysical properties of POSS-8Cz were investigated by using UV–vis,photoluminescence spectroscopic analysis. The hybrid material exhibits blue emission in the solution and the solid film.The morphology and thermal stablity properties were measured by X-ray diffraction (XRD) and TG-DTA analysis.

  10. Transport properties of topological insulators films and nanowires

    Institute of Scientific and Technical Information of China (English)

    Liu Yi; Ma Zheng; Zhao Yan-Fei; Meenakshi Singh; Wang Jian

    2013-01-01

    The last several years have witnessed the rapid developments in the study and understanding of topological insulators.In this review,after a brief summary of the history of topological insulators,we focus on the recent progress made in transport experiments on topological insulator films and nanowires.Some quantum phenomena,including the weak antilocalization,the Aharonov-Bohm effect,and the Shubnikov-de Haas oscillations,observed in these nanostructures are described.In addition,the electronic transport evidence of the superconducting proximity effect as well as an anomalous resistance enhancement in topological insulator/superconductor hybrid structures is included.

  11. INVESTIGATION OF TURBULENCE STRUCTURES AND TURBULENT COUNTER-GRADIENT TRANSPORT PROPERTIES IN STRATIFIED FLOWS

    Institute of Scientific and Technical Information of China (English)

    QIU Xiang

    2006-01-01

    Turbulence structures and turbulent Counter-Gradient Transport(CGT) properties in the stratified flows with a sharp temperature interface are investigated by experimental measurements using LIF and PIV, by LES and by correlation analysis.

  12. Electron transport and electrocatalytic properties of MWCNT/nickel nanocomposites: hydrazine and diethylaminoethanethiol as analytical probes

    CSIR Research Space (South Africa)

    Adekunle, AS

    2010-06-01

    Full Text Available This work describes the electron transport and electrocatalytic properties of chemically-synthesized nickel (Ni) and nickel oxide (NiO) nanoparticles supported on multi-walled carbon nanotubes (MWCNT) platforms. Successful modification...

  13. Magnetic and Transport Properties of Ferromagnetic Semiconductor GaDyN Thin Film

    Institute of Scientific and Technical Information of China (English)

    LI Xi-Jun; ZHOU YI-Kai; KIM M.; KIMURA S.; TERAGUCHI N.; EMURA S.; HASEGAWA S.; ASAHI H.

    2005-01-01

    @@ Magnetic properties and temperature dependence of electrical transport properties of rare-earth-metal Dy-doped GaN thin film are experimentally studied with a superconducting quantum interference device magnetometer and van der Pauw method. It was found that this thin nitride film has both semiconductor properties and ferromagnetism from 10K to room temperature. The dopant-band (conducting band due to doping) electron conduction dominates the transport properties of this film at low temperatures. These results indicate that Dy-doped GaN is an n-type ferromagnetic semiconductor at room temperature.

  14. Physicochemical properties and transport of steroids across Caco-2 cells

    NARCIS (Netherlands)

    Faassen, F.; Kelder, J.; Lenders, J.; Onderwater, R.; Vromans, H.

    2003-01-01

    Purpose. The purpose of this work was to study the relevant physicochemical properties for the absorption of steroids. Methods. Various physicochemical properties of steroids were calculated (molecular weight, ClogP, static polar surface area [PSA], etc.). Within this series of steroids, different p

  15. The transport properties of silicon and carbon nanotubes at the atomic scale: a first-principles study.

    Science.gov (United States)

    Ma, Tengying; Wen, Shizheng; Yan, Likai; Wu, Caixia; Zhang, Chunmei; Zhang, Min; Su, Zhongmin

    2016-08-24

    Nanotubes are one of the most promising functional materials in nanotechnology. Silicon nanotubes (SiNTs) have been experimentally validated; they are unique puckered nanotubular structures unlike carbon nanotubes (CNTs). Although the electronic and optical properties of SiNTs have been previously studied, their structure-related capability for electron transport has not been investigated. Here we report a comparative study of the intrinsic electronic and transport properties of four pairs of SiNTs and CNTs (one armchair nanotubes (3,3) and three zigzag nanotubes (5,0), (6,0) and (7,0)) using density functional theory (DFT) combined with the nonequilibrium Green's function (NEGF) method. All our investigated systems of SiNTs and CNTs are conductors. Both the armchair SiNTs and CNTs possess superior electron transport performance to their zigzag counterparts. Compared with CNTs, SiNTs have more advantages in the high bias voltage region. Especially, Si(3,3) possesses around double the potential charge capacity of C(3,3) under the bias voltage of 2.0 V. In particular, the CNT(6,0) exhibits distinct negative differential resistance (NDR) behavior and the peak-valley ratio (PVR) for C(6,0) is about 1.2.

  16. Direct method for calculating temperature-dependent transport properties

    NARCIS (Netherlands)

    Liu, Y.; Yuan, Z.; Wesselink, R.J.H.; Starikov, A.A.; Schilfgaarde, van M.; Kelly, P.J.

    2015-01-01

    We show how temperature-induced disorder can be combined in a direct way with first-principles scattering theory to study diffusive transport in real materials. Excellent (good) agreement with experiment is found for the resistivity of Cu, Pd, Pt (and Fe) when lattice (and spin) disorder are calcula

  17. Magnetic and electronic transport properties of the monophosphate tungsten bronze (PO 2) 4(WO 3) 2 m, m = 2

    Science.gov (United States)

    Teweldemedhin, Z. S.; Ramanujachary, K. V.; Greenblatt, M.

    1991-11-01

    Large plate-like dark-brown crystals of monophosphate tungsten bronze (PO 2) 4(WO 3) 2 m, m = 2 or PWO 5 were prepared by reacting stoichiometric mixtures of P 2O 5, WO 3, and W at 1200°C. The temperature dependence of electrical resistivity along each of the three unique crystallographic axes of a single crystal shows semiconducting behavior down to 50 K with an activation energy of ˜0.084 eV. The room temperature resistivitity along the direction of corner sharing WO 6 octahedra is 5 × 10 -3 Ω · cm and about one to two orders of magnitude lower than along other unique directions, which implies quasi one-dimensional behavior. The magnetization study made on a batch of crystals in the temperature range of 2 to 300 K is indicative of antiferromagnetic ordering with a maximum at 15 K. An earlier theoretical study on the band electronic structure of (PO 2) 4(WO 3) 4 predicted both localized and delocalized electrons in narrow and dispersive bands, respectively. The observed magnetic moment of PWO 5 is consistent with the theoretical prediction, but the observed semiconductivity behavior is not. The difference in the observed electronic transport properties of PWO 5 from that of theoretically predicted behavior, as well as the anomalous magnetic and transport properties compared to the higher members of the series of the monophosphate tungsten bronzes {(PO 2) 4(WO 3) 2 m, m = 4, 6}, is discussed in terms of the unique structure of PWO 5.

  18. A novel psychrophilic lipase from Pseudomonas fluorescens with unique property in chiral resolution and biodiesel production via transesterification

    Energy Technology Data Exchange (ETDEWEB)

    Luo Yu; Zheng Yitao; Jiang Zhengbing; Ma Yushu; Wei Dongzhi [East China Univ. of Science and Tech., Shanghai (China). State Key Lab. of Bioreactor Engineering

    2006-11-15

    A lipase-producing bacterium strain B68 screened from soil samples of China was identified as Pseudomonas fluorescens. With GenomeWalker, the open reading frame of lipase gene lipB68, encoding 476 amino acids, was cloned and expressed in Escherichia coli BL21 (DE3). By affinity chromatography, the recombinant LipB68 protein was purified to the purity of 95%. As a member of lipase subfamily I.3, LipB68 has a unique optimum temperature of 20 C, which was the lowest in this subfamily. In chiral resolution, LipB68 effectively catalyzed the transesterification of both a-phenylethanol and a-phenylpropanol at 20 C, achieving E values greater than 100 and 60 after 120 h, respectively. Among all the known catalysts in biodiesel production, LipB68 produced biodiesel with a yield of 92% after 12 h, at the lowest temperature of 20 C, and is the first one of the I.3 lipase subfamily reported to be capable of catalyzing the transesterification reaction of biodiesel production. Since lipasemediated biodiesel production is normally carried out at 35-50 C, the availability of a highly active lipase with a low optimal temperature can provide substantial savings in energy consumption. Thus, this novel psychrophilic lipase (LipB68) may represent a highly competitive energy-saving biocatalyst. (orig.)

  19. Investigation of mass transport properties of microfibrillated cellulose (MFC) films

    DEFF Research Database (Denmark)

    Minelli, Matteo; Baschetti, Marco Giacinti; Doghieri, Ferruccio

    2010-01-01

    sorption experiments confirmed the hydrophilic character of these cellulosic materials and showed a dual effect of glycerol which reduced the water uptake at low water activity while enhancing it at high relative humidity. The water diffusion in dry samples was remarkably slow for a porous material...... was observed in permeation experiments. Dry MFC films showed excellent oxygen barrier properties; however, a dramatic decrease in these properties was observed when the water content in the samples was increased....

  20. Understanding hopping transport and thermoelectric properties of conducting polymers

    Science.gov (United States)

    Ihnatsenka, S.; Crispin, X.; Zozoulenko, I. V.

    2015-07-01

    We calculate the conductivity σ and the Seebeck coefficient S for the phonon-assisted hopping transport in conducting polymers poly(3,4-ethylenedioxythiophene) or PEDOT, experimentally studied by Bubnova et al. [J. Am. Chem. Soc. 134, 16456 (2012)], 10.1021/ja305188r. We use the Monte Carlo technique as well as the semianalytical approach based on the transport energy concept. We demonstrate that both approaches show a good qualitative agreement for the concentration dependence of σ and S . At the same time, we find that the semianalytical approach is not in a position to describe the temperature dependence of the conductivity. We find that both Gaussian and exponential density of states (DOS) reproduce rather well the experimental data for the concentration dependence of σ and S giving similar fitting parameters of the theory. The obtained parameters correspond to a hopping model of localized quasiparticles extending over 2-3 monomer units with typical jumps over a distance of 3-4 units. The energetic disorder (broadening of the DOS) is estimated to be 0.1 eV. Using the Monte Carlo calculation we reproduce the activation behavior of the conductivity with the calculated activation energy close to the experimentally observed one. We find that for a low carrier concentration a number of free carriers contributing to the transport deviates strongly from the measured oxidation level. Possible reasons for this behavior are discussed. We also study the effect of the dimensionality on the charge transport by calculating the Seebeck coefficient and the conductivity for the cases of three-, two-, and one-dimensional motion.

  1. Systematic characterization of porosity and mass transport and mechanical properties of porous polyurethane scaffolds.

    Science.gov (United States)

    Wang, Yu-Fu; Barrera, Carlos M; Dauer, Edward A; Gu, Weiyong; Andreopoulos, Fotios; Huang, C-Y Charles

    2017-01-01

    One of the key challenges in porous scaffold design is to create a porous structure with desired mechanical function and mass transport properties which support delivery of biofactors and development of function tissue substitute. In recent years, polyurethane (PU) has become one of the most popular biomaterials in various tissue engineering fields. However, there are no studies fully investigating the relations between porosity and both mass transport and mechanical properties of PU porous scaffolds. In this paper, we fabricated PU scaffolds by combining phase inversion and salt (sodium chloride) leaching methods. The tensile and compressive moduli were examined on PU scaffolds fabricated with different PU concentrations (25%, 20% and 15% w/v) and salt/PU weight ratios (9/1, 6/1, 3/1 and 0/1). The mass transport properties of PU scaffolds including hydraulic permeability and glucose diffusivity were also measured. Furthermore, the relationships between the porosity and mass transport and mechanical properties of porous PU scaffold were systemically investigated. The results demonstrated that porosity is a key parameter which governs both mass transport and mechanical properties of porous PU scaffolds. With similar pore sizes, the mass transport and mechanical properties of porous PU scaffold can be described as single functions of porosity regardless of initial PU concentration. The relationships between scaffold porosity and properties can be utilized to facilitate porous PU scaffold fabrication with specific mass transport and mechanical properties. The systematic approach established in this study can be applied to characterization of other biomaterials for scaffold design and fabrication.

  2. Spiro-fused six-membered N-heterocyclic carbene: a new scaffold toward unique properties and activities.

    Science.gov (United States)

    Yang, Bin-Miao; Xiang, Kai; Tu, Yong-Qiang; Zhang, Shi-Heng; Yang, Deng-Tao; Wang, Shao-Hua; Zhang, Fu-Ming

    2014-07-11

    A six-membered N-heterocyclic carbene fused with a spiro-scaffold is designed. The new NHC shows stronger σ-donation ability than typical 5-membered NHCs. This property leads to interesting reactivities of this spiro-fused six-membered NHC. For example, the NHC-BF3 Lewis pair complex can be readily prepared by using LiBF4 as the BF3 source, or through a direct bond-reconstruction of the tetrafluoroborate salt NHC·HBF4.

  3. Thermodynamical and microscopic properties of turbulent transport in the edge plasma

    Science.gov (United States)

    Ghendrih, Ph; Norscini, C.; Hasenbeck, F.; Dif-Pradalier, G.; Abiteboul, J.; Cartier-Michaud, T.; Garbet, X.; Grandgirard, V.; Marandet, Y.; Sarazin, Y.; Tamain, P.; Zarzoso, D.

    2012-12-01

    Edge plasma turbulence modelled with 2D interchange is shown to exhibit convective transport at the microscale level. This transport property is related to avalanche like transport in such a flux-driven system. Correlation functions and source modulation are used to analyse the transport properties but do not allow one to recover the Fick law that must characterise the system at large scales. Coarse graining is then introduced to average out the small scales in order to recover the Fick law. One finds that the required space averaging is comparable to the system size while the time averaging is comparable to the confinement time. The system is then reduced to a single reservoir such that transport is characterised by a single scalar, either the diffusion coefficient of the Fick law or a characteristic evolution time constant.

  4. Synthesis and characterization of polymer electrolyte membranes with controlled ion transport properties

    Science.gov (United States)

    Xu, Kui

    2011-12-01

    conductivity at the same order of magnitude as Nafion. This unique transport feature gave rise to exceedingly higher electrochemical selectivity in relation to Nafion. The selectivity characteristics have been rationalized based on the formation of restrained ionic domains and the state of the absorbed water within the membranes. A series of new Nafion-based composite membranes were prepared via an in situ sol-gel reaction of 3-(trihydroxylsilyl) propane-1-sulfonic acid and solution casting method. The morphological structure, ion-exchange capacity, water uptake, proton conductivity, and methanol permeability of the resulting composite membranes were extensively investigated as functions of the content of sulfopropylated polysilsesquioxane filler, temperature, and relative humidity. Unlike the conventional Nafion/silica composites, the prepared membranes exhibit an increased water uptake and associated enhancement in proton conductivity compared to unmodified Nafion. In particular, considerably high proton conductivities at 80 and 120 °C under 30% relative humidity were demonstrated in the composite membranes, which are over 2 times greater than that of Nafion. In addition to a remarkable improvement in proton conductivity, the composite membranes displayed lower methanol permeability and superior electrochemical selectivity in comparison to the pure Nafion membrane. A versatile and facile synthetic approach was developed for the preparation of a family of new ionomers with rigid aromatic backbones and pendant perfluorinated sulfonic acid groups. Variation in the chemical composition and structure of the new aromatic ionomers were performed to optimize PEM properties and fuel cell performance. The ionomers prepared from condensation polymerization of Sodium 1,1,2,2-tetrafluoro-2-(2',3',5',6'-tetrafluoro-phenoxy)- ethane sulfonate and bisphenol monomers, e.g. hydroquinone, 4,4'-biphenol, or their mixture with appropriate ratio, exhibited comparable or greater proton

  5. The effect of mucolytic agents on the rheologic and transport properties of canine tracheal mucus.

    Science.gov (United States)

    Martin, R; Litt, M; Marriott, C

    1980-03-01

    The effect of several sulfhydryl and other agents on the rheologic and mucociliary transport properties of a model secretion, reconstituted canine tracheal mucus, was investigated. The mucus was obtained via the canine tracheal pouch. Rheologic properties were determined by mirorheometry, and the ciliary transport rate was determined using the frog palate technique. It was found that N-acetyl cysteine decreased the elastic modulus, leading to improved mucociliary transport at concentrations such that the mucin did not precipitate. S-carboxymethyl cysteine had no effect on either mucus properties or mucociliary transport rate, and its reported effectiveness in vivo must be due to some mechanism other than solubilization of mucin. Similar results were found with other blocked sulfhydryl compounds. Urea and potassium iodide to decrease mucus elasticity, but are harmful to cilia at the concentrations needed.

  6. RECQL5 has unique strand annealing properties relative to the other human RecQ helicase proteins.

    Science.gov (United States)

    Khadka, Prabhat; Croteau, Deborah L; Bohr, Vilhelm A

    2016-01-01

    The RecQ helicases play important roles in genome maintenance and DNA metabolism (replication, recombination, repair, and transcription). Five different homologs are present in humans, three of which are implicated in accelerated aging genetic disorders: Rothmund Thomson (RECQL4), Werner (WRN), and Bloom (BLM) syndromes. While the DNA helicase activities of the 5 human RecQ helicases have been extensively characterized, much less is known about their DNA double strand annealing activities. Strand annealing is an important integral enzymatic activity in DNA metabolism, including DNA repair. Here, we have characterized the strand annealing activities of all five human RecQ helicase proteins and compared them. Interestingly, the relative strand annealing activities of the five RecQ proteins are not directly (inversely) related to their helicase activities. RECQL5 possesses relatively strong annealing activity on long or small duplexed substrates compared to the other RecQs. Additionally, the strand annealing activity of RECQL5 is not inhibited by the presence of ATP, unlike the other RecQs. We also show that RECQL5 efficiently catalyzes annealing of RNA to DNA in vitro in the presence or absence of ATP, revealing a possible new function for RECQL5. Additionally, we investigate how different known RecQ interacting proteins, RPA, Ku, FEN1 and RAD51, regulate their strand annealing activity. Collectively, we find that the human RecQ proteins possess differential DNA double strand annealing activities and we speculate on their individual roles in DNA repair. This insight is important in view of the many cellular DNA metabolic actions of the RecQ proteins and elucidates their unique functions in the cell.

  7. Hydrogenation-controlled phase transition on two-dimensional transition metal dichalcogenides and their unique physical and catalytic properties

    Science.gov (United States)

    Qu, Yuanju; Pan, Hui; Kwok, Chi Tat

    2016-09-01

    Two-dimensional (2D) transition metal dichalcogenides (TMDs) have been widely used from nanodevices to energy harvesting/storage because of their tunable physical and chemical properties. In this work, we systematically investigate the effects of hydrogenation on the structural, electronic, magnetic, and catalytic properties of 33 TMDs based on first-principles calculations. We find that the stable phases of TMD monolayers can transit from 1T to 2H phase or vice versa upon the hydrogenation. We show that the hydrogenation can switch their magnetic and electronic states accompanying with the phase transition. The hydrogenation can tune the magnetic states of TMDs among non-, ferro, para-, and antiferro-magnetism and their electronic states among semiconductor, metal, and half-metal. We further show that, out of 33 TMD monolayers, 2H-TiS2 has impressive catalytic ability comparable to Pt in hydrogen evolution reaction in a wide range of hydrogen coverages. Our findings would shed the light on the multi-functional applications of TMDs.

  8. Influence of deformation on the fluid transport properties of salt rocks

    NARCIS (Netherlands)

    Peach, C.J.

    1991-01-01

    While the fluid transport properties of rocks are well understood under hydrostatic conditions, little is known regarding these properties in rocks undergoing crystal plastic deformation. However, such data are needed as input in the field of radioactive waste disposal in salt formations. They are a

  9. Influence of deformation on the fluid transport properties of salt rocks

    NARCIS (Netherlands)

    Peach, C.J.

    1991-01-01

    While the fluid transport properties of rocks are well understood under hydrostatic conditions, little is known regarding these properties in rocks undergoing crystal plastic deformation. However, such data are needed as input in the field of radioactive waste disposal in salt formations. They are a

  10. Microsphere-chain waveguides: Focusing and transport properties

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Kenneth W., E-mail: kallen62@uncc.edu; Astratov, Vasily N., E-mail: astratov@uncc.edu [Department of Physics and Optical Science, Center for Optoelectronics and Optical Communications, University of North Carolina at Charlotte, Charlotte, North Carolina 28223-0001 (United States); Air Force Research Laboratory, Sensors Directorate, Wright Patterson AFB, Ohio 45433 (United States); Darafsheh, Arash; Abolmaali, Farzaneh [Department of Physics and Optical Science, Center for Optoelectronics and Optical Communications, University of North Carolina at Charlotte, Charlotte, North Carolina 28223-0001 (United States); Mojaverian, Neda; Limberopoulos, Nicholaos I. [Air Force Research Laboratory, Sensors Directorate, Wright Patterson AFB, Ohio 45433 (United States); Lupu, Anatole [Institut d' Electronique Fondamentale, UMR 8622 CNRS, Universite Paris-Sud XI, 91405 Orsay (France)

    2014-07-14

    It is shown that the focusing properties of polystyrene microsphere-chain waveguides (MCWs) formed by sufficiently large spheres (D ≥ 20λ, where D is the sphere diameter and λ is the wavelength of light) scale with the sphere diameter as predicted by geometrical optics. However, this scaling behavior does not hold for mesoscale MCWs with D ≤ 10λ resulting in a periodical focusing with gradually reducing beam waists and in extremely small propagation losses. The observed effects are related to properties of nanojet-induced and periodically focused modes in such structures. The results can be used for developing focusing microprobes, laser scalpels, and polarization filters.

  11. Transport Properties of the Tomato Fruit Tonoplast : III. Temperature Dependence of Calcium Transport.

    Science.gov (United States)

    Joyce, D C; Cramer, G R; Reid, M S; Bennett, A B

    1988-12-01

    Calcium transport into tomato (Lycopersicon esculentum Mill, cv Castlemart) fruit tonoplast vesicles was studied. Calcium uptake was stimulated approximately 10-fold by MgATP. Two ATP-dependent Ca(2+) transport activities could be resolved on the basis of sensitivity to nitrate and affinity for Ca(2+). A low affinity Ca(2+) uptake system (K(m) > 200 micromolar) was inhibited by nitrate and ionophores and is thought to represent a tonoplast localized H(+)/Ca(2+) antiport. A high affinity Ca(2+) uptake system (K(m) = 6 micromolar) was not inhibited by nitrate, had reduced sensitivity to ionophores, and appeared to be associated with a population of low density endoplasmic reticulum vesicles that contaminated the tonoplast-enriched membrane fraction. Arrhenius plots of the temperature dependence of Ca(2+) transport in tomato membrane vesicles showed a sharp increase in activation energy at temperatures below 10 to 12 degrees C that was not observed in red beet membrane vesicles. This low temperature effect on tonoplast Ca(2+)/H(+) antiport activity could only by partially ascribed to an effect of low temperature on H(+)-ATPase activity, ATP-dependent H(+) transport, passive H(+) fluxes, or passive Ca(2+) fluxes. These results suggest that low temperature directly affects Ca(2+)/H(+) exchange across the tomato fruit tonoplast, resulting in an apparent change in activation energy for the transport reaction. This could result from a direct effect of temperature on the Ca(2+)/H(+) exchange protein or by an indirect effect of temperature on lipid interactions with the Ca(2+)/H(+) exchange protein.

  12. Transport properties of partially ionized and unmagnetized plasmas

    Science.gov (United States)

    Magin, Thierry E.; Degrez, Gérard

    2004-10-01

    This work is a comprehensive and theoretical study of transport phenomena in partially ionized and unmagnetized plasmas by means of kinetic theory. The pros and cons of different models encountered in the literature are presented. A dimensional analysis of the Boltzmann equation deals with the disparity of mass between electrons and heavy particles and yields the epochal relaxation concept. First, electrons and heavy particles exhibit distinct kinetic time scales and may have different translational temperatures. The hydrodynamic velocity is assumed to be identical for both types of species. Second, at the hydrodynamic time scale the energy exchanged between electrons and heavy particles tends to equalize both temperatures. Global and species macroscopic fluid conservation equations are given. New constrained integral equations are derived from a modified Chapman-Enskog perturbative method. Adequate bracket integrals are introduced to treat thermal nonequilibrium. A symmetric mathematical formalism is preferred for physical and numerical standpoints. A Laguerre-Sonine polynomial expansion allows for systems of transport to be derived. Momentum, mass, and energy fluxes are associated to shear viscosity, diffusion coefficients, thermal diffusion coefficients, and thermal conductivities. A Goldstein expansion of the perturbation function provides explicit expressions of the thermal diffusion ratios and measurable thermal conductivities. Thermal diffusion terms already found in the Russian literature ensure the exact mass conservation. A generalized Stefan-Maxwell equation is derived following the method of Kolesnikov and Tirskiy. The bracket integral reduction in terms of transport collision integrals is presented in Appendix for the thermal nonequilibrium case. A simple Eucken correction is proposed to deal with the internal degrees of freedom of atoms and polyatomic molecules, neglecting inelastic collisions. The authors believe that the final expressions are

  13. Transport Properties of III-N Hot Electron Transistors

    Science.gov (United States)

    Suntrup, Donald J., III

    Unipolar hot electron transistors (HETs) represent a tantalizing alternative to established bipolar transistor technologies. During device operation electrons are injected over a large emitter barrier into the base where they travel along the device axis with very high velocity. Upon arrival at the collector barrier, high-energy electrons pass over the barrier and contribute to collector current while low-energy electrons are quantum mechanically reflected back into the base. Designing the base with thickness equal to or less than the hot electron mean free path serves to minimize scattering events and thus enable quasi-ballistic operation. Large current gain is achieved by increasing the ratio of transmitted to reflected electrons. Although III-N HETs have undergone substantial development in recent years, there remain ample opportunities to improve key device metrics. In order to engineer improved device performance, a deeper understanding of the operative transport physics is needed. Fortunately, the HET provides fertile ground for studying several prominent electron transport phenomena. In this thesis we present results from several studies that use the III-N HET as both emitter and analyzer of hot electron momentum states. The first provides a measurement of the hot electron mean free path and the momentum relaxation rate in GaN; the second relies on a new technique called electron injection spectroscopy to investigate the effects of barrier height inhomogeneity in the emitter. To supplement our analysis we develop a comprehensive theory of coherent electron transport that allows us to model the transfer characteristics of complex heterojunctions. Such a model provides a theoretical touchstone with which to compare our experimental results. While these studies are of potential interest in their own right, we interpret the results with an eye toward improving next-generation device performance.

  14. FORTRAN 4 computer program for calculation of thermodynamic and transport properties of complex chemical systems

    Science.gov (United States)

    Svehla, R. A.; Mcbride, B. J.

    1973-01-01

    A FORTRAN IV computer program for the calculation of the thermodynamic and transport properties of complex mixtures is described. The program has the capability of performing calculations such as:(1) chemical equilibrium for assigned thermodynamic states, (2) theoretical rocket performance for both equilibrium and frozen compositions during expansion, (3) incident and reflected shock properties, and (4) Chapman-Jouguet detonation properties. Condensed species, as well as gaseous species, are considered in the thermodynamic calculation; but only the gaseous species are considered in the transport calculations.

  15. Corresponding-states principle and its practice thermodynamic, transport and surface properties of fluids

    CERN Document Server

    Xiang, Hong Wei

    2005-01-01

    The corresponding-states principle helps the understanding and calculating of thermodynamic, transport, and surface properties of substances in various states, required by our modern lifestyle. The Corresponding-States Principle and its Practice: Thermodynamic, Transport and Surface Properties of Fluids describes the origins and applications of the principle from a universal point of view with comparisons to experimental data where possible. It uses the universal theory to explain present theories. Emphasis is on the properties of pure systems, and the corresponding-states theory can also be e

  16. Optical and transport properties of complex molecular systems

    OpenAIRE

    2009-01-01

    Esta Tesis presenta el estudio de las propiedades ópticas y de transporte de sistemas de baja dimensionalidad a través de modelos de enlace fuerte. Nuestro trabajo se centra en dos tipos de sistemas: agregados moleculares lineales y moléculas de ADN.En los Capítulos 2, 3 y 4 se estudian las propiedades de localización de un Hamiltoniano de Frenkel desordenado unidimensional. El desorden se introduce en las energías de sitio y es correlacionado de largo alcance. Para correlaciones fuertes, se ...

  17. Electronic transport properties of graphene doped by gallium

    Science.gov (United States)

    Mach, J.; Procházka, P.; Bartošík, M.; Nezval, D.; Piastek, J.; Hulva, J.; Švarc, V.; Konečný, M.; Kormoš, L.; Šikola, T.

    2017-10-01

    In this work we present the effect of low dose gallium (Ga) deposition (graphene grown by chemical vapor deposition. In situ graphene transport measurements performed with a graphene field-effect transistor structure show that at low Ga coverages a graphene layer tends to be strongly n-doped with an efficiency of 0.64 electrons per one Ga atom, while the further deposition and Ga cluster formation results in removing electrons from graphene (less n-doping). The experimental results are supported by the density functional theory calculations and explained as a consequence of distinct interaction between graphene and Ga atoms in case of individual atoms, layers, or clusters.

  18. Density functional theory calculations of charge transport properties of ‘plate-like’ coronene topological structures

    Indian Academy of Sciences (India)

    ZIRAN CHEN; ZHANRONG HE; YOUHUI XU; WENHAO YU

    2017-09-01

    Charge transport rate is one of the key parameters determining the performance of organic electronic devices. In this paper, we used density functional theory (DFT) at the M06-2X/6−31+G(d) level to compute the charge transport rates of nine coronene topological structures. The results show that the energy gap of these nine coronene derivatives is in the range 2.90–3.30 eV, falling into the organic semiconductor category. The size of the conjugate ring has a large influence on the charge transport properties. Incorporation of methyl groupson the rigid core of tetrabenzocoronene and hexabenzocoronene is more conducive to the hole transport of the molecule than incorporating methoxyl groups. The derivatisation of a ‘long plate-like’ coronene with methoxylgroups facilitates both hole and electron transport. This class of molecules can thus be used in the design of ambipolar transport semiconductor materials.

  19. Correlation of Crystalline Structure with Magnetic and Transport Properties of Glass-Coated Microwires

    Directory of Open Access Journals (Sweden)

    Arcady Zhukov

    2017-02-01

    Full Text Available We overviewed the correlation between the structure, magnetic and transport properties of magnetic microwires prepared by the Taylor-Ulitovsky method involving rapid quenching from the melt and drawing of the composite (metallic core, glass coated wire. We showed that this method can be useful for the preparation of different families of magnetic microwires: soft magnetic microwires displaying Giant magnetoimpedance (GMI effect, semi-hard magnetic microwires, microwires with granular structure exhibiting Giant Magnetoresistance (GMR effect and Heusler-type microwires. Magnetic and transport properties of magnetic microwires depend on the chemical composition of metallic nucleus and on the structural features (grain size, precipitating phases of prepared microwires. In all families of crystalline microwires, their structure, magnetic and transport properties are affected by internal stresses induced by the glass coating, depending on the quenching rate. Therefore, properties of glass-coated microwires are considerably different from conventional bulk crystalline alloys.

  20. Studies of Transport Properties of Fractures: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Stephen R. Brown

    2006-06-30

    We proposed to study several key factors controlling the character and evolution of fracture system permeability and transport processes. We suggest that due to surface roughness and the consequent channeling in single fractures and in fracture intersections, the tendency of a fracture system to plug up, remain permeable, or for permeability to increase due to chemical dissolution/precipitation conditions will depend strongly on the instantaneous flow channel geometry. This geometry will change as chemical interaction occurs, thus changing the permeability through time. To test this hypothesis and advance further understanding toward a predictive capability, we endeavored to physically model and analyze several configurations of flow and transport of inert and chemically active fluids through channels in single fractures and through fracture intersections. This was an integrated program utilizing quantitative observations of fractures and veins in drill core, quantitative and visual observations of flow and chemical dissolution and precipitation within replicas of real rough-walled fractures and fracture intersections, and numerical modeling via lattice Boltzmann methods.

  1. Electrical Transport Properties of Polymorphic MoS2.

    Science.gov (United States)

    Kim, Jun Suk; Kim, Jaesu; Zhao, Jiong; Kim, Sungho; Lee, Jin Hee; Jin, Youngjo; Choi, Homin; Moon, Byoung Hee; Bae, Jung Jun; Lee, Young Hee; Lim, Seong Chu

    2016-08-23

    The engineering of polymorphs in two-dimensional layered materials has recently attracted significant interest. Although the semiconducting (2H) and metallic (1T) phases are known to be stable in thin-film MoTe2, semiconducting 2H-MoS2 is locally converted into metallic 1T-MoS2 through chemical lithiation. In this paper, we describe the observation of the 2H, 1T, and 1T' phases coexisting in Li-treated MoS2, which result in unusual transport phenomena. Although multiphase MoS2 shows no transistor-gating response, the channel resistance decreases in proportion to the temperature, similar to the behavior of a typical semiconductor. Transmission electron microscopy images clearly show that the 1T and 1T' phases are randomly distributed and intervened with 2H-MoS2, which is referred to as the 1T and 1T' puddling phenomenon. The resistance curve fits well with 2D-variable range-hopping transport behavior, where electrons hop over 1T domains that are bounded by semiconducting 2H phases. However, near 30 K, electrons hop over charge puddles. The large temperature coefficient of resistance (TCR) of multiphase MoS2, -2.0 × 10(-2) K(-1) at 300 K, allows for efficient IR detection at room temperature by means of the photothermal effect.

  2. Interpreting equilibrium-conductivity and conductivity-relaxation measurements to establish thermodynamic and transport properties for multiple charged defect conducting ceramics.

    Science.gov (United States)

    Zhu, Huayang; Ricote, Sandrine; Coors, W Grover; Kee, Robert J

    2015-01-01

    A model-based interpretation of measured equilibrium conductivity and conductivity relaxation is developed to establish thermodynamic, transport, and kinetics parameters for multiple charged defect conducting (MCDC) ceramic materials. The present study focuses on 10% yttrium-doped barium zirconate (BZY10). In principle, using the Nernst-Einstein relationship, equilibrium conductivity measurements are sufficient to establish thermodynamic and transport properties. However, in practice it is difficult to establish unique sets of properties using equilibrium conductivity alone. Combining equilibrium and conductivity-relaxation measurements serves to significantly improve the quantitative fidelity of the derived material properties. The models are developed using a Nernst-Planck-Poisson (NPP) formulation, which enables the quantitative representation of conductivity relaxations caused by very large changes in oxygen partial pressure.

  3. Changes of the Unique Odontogenic Properties of Rat Apical Bud Cells under the Developing Apical Complex Microenvironment

    Institute of Scientific and Technical Information of China (English)

    Jun Fang; Liang Tang; Xiao-hui Liu; Ling-ying Wen; Yan Jin

    2009-01-01

    Aim To characterize the odontogenic capability of apical bud and phenotypical change of apical bud cells (ABCs) in different microenvironment. Methodology Incisor apical bud tissues from neonatal SD rat were dissected and transplanted into the renal capsules to determine their odontogenic capability. Meanwhile ABCs were cultured and purified by repeated differential trypsinization. Then ABCs were cultured with conditioned medium from developing apical complex cells (DAC-CM). Immunocytochemistry, reverse transcriptase polymerase chain reaction (RT-PCR) and scanning electron microscope (SEM) were performed to compare the biological change of ABC treated with or without DAC-CM. Results First we confirmed the ability of apical bud to form crown-like structure ectopically. Equally important, by using the developing apical complex (DAC) conditioned medium, we found the microenvironment created by root could abrogate the "crown" features of ABCs and promote their proliferation and differentiation. Conclusion ABCs possess odontogenic capability to form crown-like tissues and this property can be affected by root-produced microenvironment.

  4. Unique virulence properties of Yersinia enterocolitica O:3--an emerging zoonotic pathogen using pigs as preferred reservoir host.

    Science.gov (United States)

    Valentin-Weigand, Peter; Heesemann, Jürgen; Dersch, Petra

    2014-10-01

    Enteropathogenic Yersinia enterocolitica bioserotype 4/O:3 are the most frequent cause of human yersiniosis worldwide with symptoms ranging from mild diarrhea to severe complications of mesenteric lymphadenitis, liver abscesses and postinfectious extraintestinal sequelae. The main reservoir host of 4/O:3 strains are pigs, which represent a substantial disease-causing potential for humans, as they are usually asymptomatic carriers. Y. enterocolitica O:3 initiates infections by tight attachment to the intestinal mucosa. Colonization of the digestive tract is frequently followed by invasion of the intestinal layer primarily at the follicle-associated epithelium, allowing the bacteria to propagate in the lamina propria and disseminate into deeper tissues. Molecular characterization of Y. enterocolitica O:3 isolates led to the identification of (i) alternative virulence and fitness factors and (ii) small genetic variations which cause profound changes in their virulence gene expression pattern (e.g. constitutive expression of the primary invasion factor InvA). These changes provoke a major difference in the virulence properties, i.e. reduced colonization of intestinal tissues in mice, but improved long-term colonization in the pig intestine. Y. enterocolitica O:3 strains cause also a considerably lower level of proinflammatory cytokine IL-8 and higher levels of the anti-inflammatory cytokine IL-10 in porcine primary macrophages, as compared to murine macrophages, which could contribute to limiting inflammation, immunopathology and severity of the infection in pigs. Copyright © 2014 Elsevier GmbH. All rights reserved.

  5. Unique properties of multiple tandem copies of the M26 recombination hotspot in mitosis and meiosis in Schizosaccharomyces pombe.

    Science.gov (United States)

    Steiner, Walter W; Recor, Chelsea L; Zakrzewski, Bethany M

    2016-11-15

    The M26 hotspot of the fission yeast Schizosaccharomyces pombe is one of the best-characterized eukaryotic hotspots of recombination. The hotspot requires a seven bp sequence, ATGACGT, that serves as a binding site for the Atf1-Pcr1 transcription factor, which is also required for activity. The M26 hotspot is active in meiosis but not mitosis and is active in some but not all chromosomal contexts and not on a plasmid. A longer palindromic version of M26, ATGACGTCAT, shows significantly greater activity than the seven bp sequence. Here, we tested whether the properties of the seven bp sequence were also true of the longer sequence by placing one, two, or three copies of the sequence into the ade6 gene, where M26 was originally discovered. These constructs were tested for activity when located on a plasmid or on a chromosome in mitosis and meiosis. We found that two copies of the 10bp M26 motif on a chromosome were significantly more active for meiotic recombination than one, but no further increase was observed with three copies. However, three copies of M26 on a chromosome created an Atf1-dependent mitotic recombination hotspot. When located on a plasmid, M26 also appears to behave as a mitotic recombination hotspot; however, this behavior most likely results from Atf1-dependent inter-allelic complementation between the plasmid and chromosomal ade6 alleles.

  6. SiCO-doped carbon fibers with unique dual superhydrophilicity/superoleophilicity and ductile and capacitance properties.

    Science.gov (United States)

    Lu, Ping; Huang, Qing; Mukherjee, Amiya; Hsieh, You-Lo

    2010-12-01

    Silicon oxycarbide (SiCO) glass-doped carbon fibers with an average diameter of 163 nm were successfully synthesized by electrospinning polymer mixtures of preceramic precursor polyureasilazane (PUS) and carbon precursor polyacrylonitrile (PAN) into fibers then converting to ceramic/carbon hybrid via cross-linking, stabilization, and pyrolysis at temperatures up to 1000 °C. The transformation of PUS/PAN polymer precursors to SiCO/carbon structures was confirmed by EDS and FTIR. Both carbon and SiCO/carbon fibers were amorphous and slightly oxidized. Doping with SiCO enhanced the thermal stability of carbon fibers and acquired new ductile behavior in the SiCO/carbon fibers with significantly improved flexibility and breaking elongation. Furthermore, the SiCO/carbon fibers exhibited dual superhydrophilicity and superoleophilicity with water and decane absorbing capacities of 873 and 608%, respectively. The cyclic voltammetry also showed that SiCO/carbon composite fibers possess better capacitor properties than carbon fibers.

  7. Impact of carbonation on the durability of cementitious materials: water transport properties characterization

    Directory of Open Access Journals (Sweden)

    Le Bescop P.

    2013-07-01

    Full Text Available Within the context of long-lived intermediate level radioactive waste geological disposal, reinforced concrete would be used. In service life conditions, the concrete structures would be subjected to drying and carbonation. Carbonation relates to the reaction between carbon dioxide (CO2 and the main hydrates of the cement paste (portlandite and C-S-H. Beyond the fall of the pore solution pH, indicative of steel depassivation, carbonation induces mineralogical and microstructural changes (due to portlandite and C-S-H dissolution and calcium carbonate precipitation. This results in the modification of the transport properties, which can impact the structure durability. Because concrete durability depends on water transport, this study focuses on the influence of carbonation on water transport properties. In fact, the transport properties of sound materials are known but they still remain to be assessed for carbonated ones. An experimental program has been designed to investigate the transport properties in carbonated materials. Four hardened cement pastes, differing in mineralogy, are carbonated in an accelerated carbonation device (in controlled environmental conditions at CO2 partial pressure of about 3%. Once fully carbonated, all the data needed to describe water transport, using a simplified approach, will be evaluated.

  8. Transport properties of graphene under periodic and quasiperiodic magnetic superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Wei-Tao, E-mail: luweitao@lyu.edu.cn [School of Science, Linyi University, 276005 Linyi (China); Institute of Condensed Matter Physics, Linyi University, 276005 Linyi (China); Wang, Shun-Jin [Department of Physics, Sichuan University, 610064 Chengdu (China); Wang, Yong-Long; Jiang, Hua [School of Science, Linyi University, 276005 Linyi (China); Institute of Condensed Matter Physics, Linyi University, 276005 Linyi (China); Li, Wen [School of Science, Linyi University, 276005 Linyi (China)

    2013-08-15

    We study the transmission of Dirac electrons through the one-dimensional periodic, Fibonacci, and Thue–Morse magnetic superlattices (MS), which can be realized by two different magnetic blocks arranged in certain sequences in graphene. The numerical results show that the transmission as a function of incident energy presents regular resonance splitting effect in periodic MS due to the split energy spectrum. For the quasiperiodic MS with more layers, they exhibit rich transmission patterns. In particular, the transmission in Fibonacci MS presents scaling property and fragmented behavior with self-similarity, while the transmission in Thue–Morse MS presents more perfect resonant peaks which are related to the completely transparent states. Furthermore, these interesting properties are robust against the profile of MS, but dependent on the magnetic structure parameters and the transverse wave vector.

  9. Electrical Transport Properties of Carbon Nanotube Metal-Semiconductor Heterojunction

    Science.gov (United States)

    Talukdar, Keka; Shantappa, Anil

    2016-10-01

    Carbon nanotubes (CNTs) have been proved to have promising applicability in various fields of science and technology. Their fascinating mechanical, electrical, thermal, optical properties have caught the attention of today’s world. We have discussed here the great possibility of using CNTs in electronic devices. CNTs can be both metallic and semiconducting depending on their chirality. When two CNTs of different chirality are joined together via topological defects, they may acquire rectifying diode property. We have joined two tubes of different chiralities through circumferential Stone-Wales defects and calculated their density of states by nearest neighbor tight binding approximation. Transmission function is also calculated to analyze whether the junctions can be used as electronic devices. Different heterojunctions are modeled and analyzed in this study. Internal stresses in the heterojunctions are also calculated by molecular dynamics simulation.

  10. Electrical transport properties of CaB6

    Science.gov (United States)

    Stankiewicz, Jolanta; Sesé, Javier; Balakrishnan, Geetha; Fisk, Zachary

    2014-10-01

    We report results from a systematic electron-transport study in a broad temperature range on 12 CaB6 single crystals. None of the crystals were intentionally doped. The different carrier densities observed presumably arise from slight variations in the Ca:B stoichiometry. In these crystals, the variation of the electrical resistivity and of the Hall effect with temperature can be consistently accounted for by the model we propose, in which B-antisite defects (B atom replacing Ca atom) are "amphoteric." The magnetotransport measurements reveal that most of the samples we have studied are close to a metal-insulator transition at low temperatures. The magnetoresistance changes smoothly from negative—for weakly metallic samples—to positive values—for samples in a localized regime.

  11. Low temperature transport properties of pyrolytic graphite sheet

    Science.gov (United States)

    Nakamura, Sachiko; Miyafuji, Daisuke; Fujii, Takenori; Matsui, Tomohiro; Fukuyama, Hiroshi

    2017-09-01

    We have made thermal and electrical transport measurements of uncompressed pyrolytic graphite sheet (uPGS), a mass-produced thin graphite sheet with various thicknesses between 10 and 100 μ m, at temperatures between 2 and 300 K. Compared to exfoliated graphite sheets like Grafoil, uPGS has much higher conductivities by an order of magnitude because of its high crystallinity confirmed by X-ray diffraction and Raman spectroscopy. This material is advantageous as a thermal link of light weight in a wide temperature range particularly above 60 K where the thermal conductivity is much higher than common thermal conductors such as copper and aluminum alloys. We also found a general relationship between thermal and electrical conductivities in graphite-based materials which have highly anisotropic conductivities. This would be useful to estimate thermal conductance of a cryogenic part made of these materials from its electrical conductance more easily measurable at low temperature.

  12. Bottom-up processing and low temperature transport properties of polycrystalline SnSe

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Zhen-Hua; Wei, Kaya; Lewis, Hutton [Department of Physics, University of South Florida, Tampa, FL 33620 (United States); Martin, Joshua [Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Nolas, George S., E-mail: gnolas@usf.edu [Department of Physics, University of South Florida, Tampa, FL 33620 (United States)

    2015-05-15

    A hydrothermal approach was employed to efficiently synthesize SnSe nanorods. The nanorods were consolidated into polycrystalline SnSe by spark plasma sintering for low temperature electrical and thermal properties characterization. The low temperature transport properties indicate semiconducting behavior with a typical dielectric temperature dependence of the thermal conductivity. The transport properties are discussed in light of the recent interest in this material for thermoelectric applications. The nanorod growth mechanism is also discussed in detail. - Graphical abstract: SnSe nanorods were synthesized by a simple hydrothermal method through a bottom-up approach. Micron sized flower-like crystals changed to nanorods with increasing hydrothermal temperature. Low temperature transport properties of polycrystalline SnSe, after SPS densification, were reported for the first time. This bottom-up synthetic approach can be used to produce phase-pure dense polycrystalline materials for thermoelectrics applications. - Highlights: • SnSe nanorods were synthesized by a simple and efficient hydrothermal approach. • The role of temperature, time and NaOH content was investigated. • SPS densification allowed for low temperature transport properties measurements. • Transport measurements indicate semiconducting behavior.

  13. Unique functional properties of conserved arginine residues in the lentivirus lytic peptide domains of the C-terminal tail of HIV-1 gp41.

    Science.gov (United States)

    Kuhlmann, Anne-Sophie; Steckbeck, Jonathan D; Sturgeon, Timothy J; Craigo, Jodi K; Montelaro, Ronald C

    2014-03-14

    A previous study from our laboratory reported a preferential conservation of arginine relative to lysine in the C-terminal tail (CTT) of HIV-1 envelope (Env). Despite substantial overall sequence variation in the CTT, specific arginines are highly conserved in the lentivirus lytic peptide (LLP) motifs and are scarcely substituted by lysines, in contrast to gp120 and the ectodomain of gp41. However, to date, no explanation has been provided to explain the selective incorporation and conservation of arginines over lysines in these motifs. Herein, we address the functions in virus replication of the most conserved arginines by performing conservative mutations of arginine to lysine in the LLP1 and LLP2 motifs. The presence of lysine in place of arginine in the LLP1 motif resulted in significant impairment of Env expression and consequently virus replication kinetics, Env fusogenicity, and incorporation. By contrast, lysine exchanges in LLP2 only affected the level of Env incorporation and fusogenicity. Our findings demonstrate that the conservative lysine substitutions significantly affect Env functional properties indicating a unique functional role for the highly conserved arginines in the LLP motifs. These results provide for the first time a functional explanation to the preferred incorporation of arginine, relative to lysine, in the CTT of HIV-1 Env. We propose that these arginines may provide unique functions for Env interaction with viral or cellular cofactors that then influence overall Env functional properties.

  14. Investigation of boron modified graphene nanostructures; optoelectronic properties of graphene nanoparticles and transport properties of graphene nanosheets

    Science.gov (United States)

    Armaković, Stevan; Armaković, Sanja J.

    2016-11-01

    In this work we investigated optoelectronic properties of graphene nanoparticles and transport properties of graphene nanosheets and the consequences on these properties after modifications with boron atoms. Within the framework of density functional theory (DFT) several important optoelectronic quantities have been calculated for graphene nanoparticles: oxidation and reduction potentials, hole and electron reorganization energies, while thermally activated delayed fluorescence was assessed by calculations of energy separation between the lowest excited singlet (S1) and triplet (T1) state, Δ E (S1 -T1) . Obtained results show that optoelectronic properties of graphene nanoparticles are significantly improved by the modification with boron atoms and that investigated structures can be considered as a promising organic light emitting diode (OLED) materials. Influence of boron atoms to charge and heat transport properties of graphene nanosheets was investigated as well, employing the self-consistent non-equilibrium Green's functions with DFT. On the other side it is shown that charge transport of graphene nanosheets is not influenced by the introduction of boron atoms, while influence to the phonon subsystem is minimal.

  15. Correlating substituent parameter values to electron transport properties of molecules

    Science.gov (United States)

    Vedova-Brook, Natalie; Matsunaga, Nikita; Sohlberg, Karl

    2004-03-01

    There are a vast number of organic compounds that could be considered for use in molecular electronics. Because of this, the need for efficient and economical screening tools has emerged. We demonstrate that the substituent parameter values ( σ), commonly found in advanced organic chemistry textbooks, correlate strongly with features of the charge migration process, establishing them as useful indicators of electronic properties. Specifically, we report that ab initio derived electronic charge transfer values for 16 different substituted aromatic molecules for molecular junctions correlate to the σ values with a correlation coefficient squared ( R2) of 0.863.

  16. Random lasing in structures with multi-scale transport properties

    CERN Document Server

    Leonetti, Marco

    2013-01-01

    In a random laser (RL), a system possessing in itself both resonator and amplifying medium while lacking of a macroscopic cavity, the feedback is provided by the scattering, which forces light to travel across very long random paths. Here we demonstrate that RL properties may be tuned by the topology of the scattering system retaining unchanged scattering strength and gain efficiency. This is possible in a system based on sparse clusters, possessing two relevant structural lengths: the macroscopic inter cluster separation and the mesoscopic intra-cluster mean free path.

  17. Magnetic colloid by PLA: Optical, magnetic and thermal transport properties

    Science.gov (United States)

    Pandey, B. K.; Shahi, A. K.; Gopal, Ram

    2015-08-01

    Ferrofluids of cobalt and cobalt oxide nanoparticles (NPs) have been successfully synthesized using liquid phase-pulse laser ablation (LP-PLA) in ethanol and double distilled water, respectively. The mechanism of laser ablation in liquid media and formation process for Co target in double distilled water (DDW) and ethanol are speculated based on the reactions between laser generated highly nascent cobalt species and vaporized solvent media in a confined high temperature and pressure at the plume-surrounding liquid interface region. Optical absorption, emission, vibrational and rotational properties have been investigated using UV-vis absorption, photoluminescence (PL) and Fourier transform-infra red (FT-IR) spectroscopy, respectively. In this study optical band gap of cobalt oxide ferrofluids has been engineered using different pulse energy of Nd:YAG laser in the range of (2.80-3.60 eV). Vibrating sample magnetometer (VSM) is employed to determine the magnetic properties of ferrofluids of cobalt and cobalt oxide NPs while their thermal conductivities are examined using rotating disc method. Ferrofluids have gained enormous curiosity due to many technological applications, i.e. drug delivery, coolant and heating purposes.

  18. Transport properties of stripe-ordered high Tc cuprates

    Science.gov (United States)

    Jie, Qing; Han, Su Jung; Dimitrov, Ivo; Tranquada, J. M.; Li, Qiang

    2012-11-01

    Transport measurements provide important characterizations of the nature of stripe order in the cuprates. Initial studies of systems such as La1.6-xNd0.4SrxCuO4 demonstrated the strong anisotropy between in-plane and c-axis resistivities, but also suggested that stripe order results in a tendency towards insulating behavior within the planes at low temperature. More recent work on La2-xBaxCuO4 with x = 1/8 has revealed the occurrence of quasi-two-dimensional superconductivity that onsets with spin-stripe order. The suppression of three-dimensional superconductivity indicates a frustration of the interlayer Josephson coupling, motivating a proposal that superconductivity and stripe order are intertwined in a pair-density-wave state. Complementary characterizations of the low-energy states near the Fermi level are provided by measurements of the Hall and Nernst effects, each revealing intriguing signatures of stripe correlations and ordering. We review and discuss this work.

  19. Spin-polarized quantum transport properties through flexible phosphorene

    Science.gov (United States)

    Chen, Mingyan; Yu, Zhizhou; Xie, Yiqun; Wang, Yin

    2016-10-01

    We report a first-principles study on the tunnel magnetoresistance (TMR) and spin-injection efficiency (SIE) through phosphorene with nickel electrodes under the mechanical tension and bending on the phosphorene region. Both the TMR and SIE are largely improved under these mechanical deformations. For the uniaxial tension (ɛy) varying from 0% to 15% applied along the armchair transport (y-)direction of the phosphorene, the TMR ratio is enhanced with a maximum of 107% at ɛy = 10%, while the SIE increases monotonously from 8% up to 43% with the increasing of the strain. Under the out-of-plane bending, the TMR overall increases from 7% to 50% within the bending ratio of 0%-3.9%, and meanwhile the SIE is largely improved to around 70%, as compared to that (30%) of the flat phosphorene. Such behaviors of the TMR and SIE are mainly affected by the transmission of spin-up electrons in the parallel configuration, which is highly dependent on the applied mechanical tension and bending. Our results indicate that the phosphorene based tunnel junctions have promising applications in flexible electronics.

  20. Study on the Electronic Transport Properties of Zigzag GaN Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Li Enling; Wang Xiqiang; Hou Liping; Zhao Danna; Dai Yuanbin [Sciences School, Xi' an University of Technology, Xi' an, China 710054 (China); Wang Xuewen [Electronic Information Science and Technology, Northwest University, Xi' an, China 710068 (China)

    2011-02-01

    The electronic transport properties of zigzag GaN nanotubes (n, 0) (4 {<=} n {<=} 9) have been calculated using the density functional theory and non-equilibrium Green's functions method. Firstly, the density functional theory (DFT) is used to optimize and calculate the electronic structure of GaNNTs (n, 0) (4{<=}n{<=}9). Secondly, DFT and non-equilibrium Green function (NEGF) method are also used to predict the electronic transport properties of GaNNTs two-probe system. The results showed: there is a corresponding relation between the electronic transport properties and the valley of state density of each GaNNT. In addition, the volt-ampere curve of GaNNT is approximately linear.

  1. Transport properties of iron-porphyrin molecule sandwiched between Au surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, Hisashi [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)], E-mail: KONDO.Hisashi@nims.go.jp; Kino, Hiori; Nara, Jun [CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Ohno, Takahisa [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); CMSC, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); MANA, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2008-09-30

    The transport properties of an iron-porphyrin molecule sandwiched between Au(1 1 1) electrodes are investigated using the non-equilibrium Green's function method based on the density functional theory, and in particular, the dependence on a terminal-atom position is studied. We consider four models for terminal-atom positions. It is found that the transport properties of the junction system are very sensitive to a terminal-atom position. We also find that the contribution of the d-orbitals of the Fe atom to the transport properties around the Fermi energy strongly changes, depending on a terminal-atom position. From these results, we propose a suitable terminal-atom position for the molecular sensor discussed in the other paper.

  2. High field transport properties of InAs/AlGaSb quantum wires

    Science.gov (United States)

    Sasa, S.; Sugihara, T.; Tada, K.; Izumiya, S.; Yamamoto, Y.; Inoue, M.

    1996-09-01

    We demonstrate the successful fabrication of multiple quantum wire structures using InAs/AlGaSb heterostructures and report on their transport properties. We have performed magnetotransport measurements on the various width of the wires ranging between 0.2 and 0.4 μm. One-dimensional transport properties confirmed by magnetic depopulation were observed up to 0.4-μm-wide wires, and the sublevel spacing was as large as 5.9 meV for 0.2-μm-wide wires. This demonstrates the advantageous feature of InAs/AlGaSb heterostructures for realizing quantum devices operating at higher temperatures. High field transport properties also reveal their advantageous features.

  3. Transport Properties of Two-Dimensional Electron Gases in Antiparallel Magnetic-Electric Barrier Structures

    Institute of Scientific and Technical Information of China (English)

    PING Yun-Xia; CHENG Ze

    2006-01-01

    We study theoretically transport properties of two-dimensional electron gases through antiparallel magnetic electric barrier structures. Two kinds of magnetic barrier configurations are employed: one is that the strength of the double δ-function in opposite directions is equal and the other is that the strength is unequal. Similarities and differences of electronic transports are presented. It is found that the transmission and the conductance depend strongly on the shape of the magnetic barrier and the height of the electric barrier. The results indicate that this system does not possess any spin filtering and spin polarization and electron gases can realize perfect resonant tunneling and wave-vector filtering properties. Moreover, the strength of the effect of the inhomogeneous magnetic field on the transport properties is discussed.

  4. Tuning of Transport and Magnetic Properties in Epitaxial LaMnO3+δ Thin Films

    Directory of Open Access Journals (Sweden)

    J. Chen

    2014-01-01

    Full Text Available The effect of compressive strain on the transport and magnetic properties of epitaxial LaMnO3+δ thin films has been investigated. It is found that the transport and magnetic properties of the LaMnO3+δ thin films grown on the LaAlO3 substrates can be tuned by the compressive strain through varying film thickness. And the insulator-metal transition, charge/orbital ordering transition, and paramagnetic-ferromagnetic transition are suppressed by the compressive strain. Consequently, the related electronic and magnetic transition temperatures decrease with an increase in the compressive strain. The present results can be explained by the strain-controlled lattice deformation and the consequent orbital occupation. It indicates that the lattice degree of freedom is crucial for understanding the transport and magnetic properties of the strongly correlated LaMnO3+δ.

  5. Electrochemical setup - a unique chance to simultaneously control orbital energies and vibrational properties of single-molecule junctions with unprecedented efficiency

    CERN Document Server

    Baldea, Ioan

    2015-01-01

    Impressive advances in nanoscience permit nowadays to manipulate single molecules and broadly control many of their properties. Still, tuning the molecular charge and vibrational properties of single molecules embedded in nanojunctions in broad ranges escaped so far to an efficient control. By combining theoretical results with recent experimental data, we show that, under electrochemical control, it is possible to continuously drive a redox molecule (viologen) between almost perfect oxidized and reduced states. This yields an unprecedentedly efficient control on both vibrational frequencies and the surface-enhanced Raman scattering (SERS) intensities. The broad tuning achieved under electrochemical control by varying the overpotential ("gate potential") within experimentally accessible ranges contrasts to the case of two-terminal setups that require high biases, which real nanojunctions cannot withstand. The present study aim at stimulating concurrent transport and SERS measurements in electrochemical setup....

  6. Charge Transport Properties of Tetrabenz[a,c,h,jl-anthracene Derivatives

    Institute of Scientific and Technical Information of China (English)

    CHEN Zi-Ran; YU Wen-Hao; LI Quan

    2012-01-01

    Charge transport properties of F, OH, OCH3, SH and SCH3-substituted tetra- benz[a,c,h,j]- anthracene derivative molecules have been investigated theoretically at the B3LYP/6-31G** level using Marcus theory. The results showed that at 300 K, the hole or electron transport capability of F or SH-substituted molecules was better obviously than that of OH or OCH3-substituted molecules, The electron transport capability of SCH3-substituted and F or SH-substituted molecules was superior to their hole transport capability, respectively. F, SH or SCH3-substituted tetrabenz[a,c,h,j]-anthracene derivative molecules can be used as electron transport materials.

  7. Effect of Cd ions on transport properties of orthomanganites

    CERN Document Server

    Troyanchuk, I O; Pastushonok, S N

    1998-01-01

    Magnetic and magnetotransport measurements have been used to study the compositional dependence of the electronic properties of the solid solutions La sub 0 sub . sub 7 (Pb sub 0 sub . sub 3 sub - sub x Cd sub x)MnO sub 3 and Nd sub 0 sub . sub 7 (Pb sub 0 sub . sub 3 sub - sub x Cd sub x)MnO sub 3. It was found that these compounds are ferromagnets and have the rhombohedrally or orthorhombically distorted perovskite structure. The substitution of Pb ions by Cd leads to the transition from the metallic to the insulating state. The intermediate compositions exhibit two peaks of the resistivity and magnetoresistance. The high-temperature peak is associated with the Curie temperature whereas there is no magnetic anomaly in the temperature interval of the second peak. We suppose that Cd ions participate in the formation of the narrow impurity band limiting the mobility of charge carriers. (author)

  8. Exceptional transport property in a rolled-up germanium tube

    Science.gov (United States)

    Guo, Qinglei; Wang, Gang; Chen, Da; Li, Gongjin; Huang, Gaoshan; Zhang, Miao; Wang, Xi; Mei, Yongfeng; Di, Zengfeng

    2017-03-01

    Tubular germanium (Ge) resistors are demonstrated by rolling-up thin Ge nanomembranes (NMs, 50 nm in thickness) with electrical contacts. The strain distribution of rolled-up Ge microtubes along the radial direction is investigated and predicted by utilizing micro-Raman scattering spectroscopy with two different excitation lasers. Electrical properties are characterized for both unreleased GeNMs and released/rolled-up Ge microtubes. The conductivities of GeNMs significantly decrease after rolling-up into tubular structures, which can be attributed to surface charging states on the conductance, band bending, and piezo-resistance effect. When illuminated with a light source, facilitated by the suppressed dark current of rolled-up Ge tubes, the corresponding signal-to-noise ratio can be dramatically enhanced compared with that of planar GeNMs.

  9. Electronic transport properties of Ir-decorated graphene.

    Science.gov (United States)

    Wang, Yilin; Xiao, Shudong; Cai, Xinghan; Bao, Wenzhong; Reutt-Robey, Janice; Fuhrer, Michael S

    2015-10-28

    Graphene decorated with 5d transitional metal atoms is predicted to exhibit many intriguing properties; for example iridium adatoms are proposed to induce a substantial topological gap in graphene. We extensively investigated the conductivity of single-layer graphene decorated with iridium deposited in ultra-high vacuum at low temperature (7 K) as a function of Ir concentration, carrier density, temperature, and annealing conditions. Our results are consistent with the formation of Ir clusters of ~100 atoms at low temperature, with each cluster donating a single electronic charge to graphene. Annealing graphene increases the cluster size, reducing the doping and increasing the mobility. We do not observe any sign of an energy gap induced by spin-orbit coupling, possibly due to the clustering of Ir.

  10. Effect of vertical-strain-induced symmetry breaking on transport properties of zigzag graphene nanoribbons

    Science.gov (United States)

    Zou, Dongqing; Zhao, Wenkai; Fang, Changfeng; Cui, Bin; Liu, Desheng

    2017-02-01

    Using density functional theory combined with nonequilibrium Green's function formalism, we investigate the transport properties of zigzag graphene nanoribbons (ZGNRs) under vertical strain. Our calculations show that localized state induced by vertical strain will inhibit the electronic transport of the systems at zero bias, but at nonzero bias, the localized state can enhance the electronic transport behavior if ZGNRs are symmetry with respect to the mid-plane between two edges. This is because the localized state produces an asymmetry electron density distribution which break the current suppression. These findings may be useful for the application of strain-induced ZGNR based molecular devices.

  11. An overview of heavy oil properties and its recovery and transportation methods

    Directory of Open Access Journals (Sweden)

    R. G. Santos

    2014-09-01

    Full Text Available Unconventional oils - mainly heavy oils, extra heavy oils and bitumens - represent a significant share of the total oil world reserves. Oil companies have expressed interest in unconventional oil as alternative resources for the energy supply. These resources are composed usually of viscous oils and, for this reason, their use requires additional efforts to guarantee the viability of the oil recovery from the reservoir and its subsequent transportation to production wells and to ports and refineries. This review describes the main properties of high-viscosity crude oils, as well as compares traditional and emergent methods for their recovery and transportation. The main characteristics of viscous oils are discussed to highlight the oil properties that affect their flowability in the processes of recovery and pipeline transportation. Chemical composition is the starting point for the oil characterization and it has major impact on other properties, including key properties for their dynamics, such as density and viscosity. Next, enhanced oil recovery (EOR methods are presented, followed by a discussion about pipeline and transportation methods. In addition, the main challenges to achieve viable recovery and transportation of unconventional oils are compared for the different alternatives proposed. The work is especially focused on the heavy oils, while other hydrocarbon solid sources, such as oil sands and shale oil, are outside of the scope of this review.

  12. The Effect of Twin Grain Boundary Tuned by Temperature on the Electrical Transport Properties of Monolayer MoS2

    OpenAIRE

    Luojun Du; Hua Yu; Li Xie; Shuang Wu; Shuopei Wang; Xiaobo Lu; Mengzhou Liao; Jianling Meng; Jing Zhao; Jing Zhang; Jianqi Zhu; Peng Chen; Guole Wang; Rong Yang; Dongxia Shi

    2016-01-01

    Theoretical calculation and experimental measurement have shown that twin grain boundary (GB) of molybdenum disulphide (MoS2) exhibits extraordinary effects on transport properties. Precise transport measurements need to verify the transport mechanism of twin GB in MoS2. Here, monolayer molybdenum disulphide with a twin grain boundary was grown in our developed low-pressure chemical vapor deposition (CVD) system, and we investigated how the twin GB affects the electrical transport properties ...

  13. Fluctuation theory for transport properties in multicomponent mixtures: thermodiffusion and heat conductivity

    DEFF Research Database (Denmark)

    Shapiro, Alexander

    2004-01-01

    The theory of transport properties in multicomponent gas and liquid mixtures, which was previously developed for diffusion coefficients, is extended onto thermodiffusion coefficients and heat conductivities. The derivation of the expressions for transport properties is based on the general...... statistical theory of fluctuations around an equilibrium state. The Onsager matrix of phenomenological coefficients is expressed in terms of the penetration lengths, including the newly introduced penetration length for the energy transfer. As an example, this penetration length is found from the known value...... of the heat conductivity coefficient for ideal gas. (C) 2003 Elsevier B.V. All rights reserved....

  14. Electrical transport properties of graphene on SiO2 with specific surface structures

    OpenAIRE

    Nagashio, K.; Yamashita, T; Nishimura, T.; K. Kita; Toriumi, A.

    2011-01-01

    The mobility of graphene transferred on a SiO2/Si substrate is limited to ~10,000 cm2/Vs. Without understanding the graphene/SiO2 interaction, it is difficult to improve the electrical transport properties. Although surface structures on SiO2 such as silanol and siloxane groups are recognized, the relation between the surface treatment of SiO2 and graphene characteristics has not yet been elucidated. This paper discusses the electrical transport properties of graphene on specific surface stru...

  15. Electronic structure and quantum transport properties of metallic and semiconducting nanowires

    Science.gov (United States)

    Simbeck, Adam J.

    The future of the semiconductor industry hinges upon new developments to combat the scaling issues that currently afflict two main chip components: transistors and interconnects. For transistors this means investigating suitable materials to replace silicon for both the insulating gate and the semiconducting channel in order to maintain device performance with decreasing size. For interconnects this equates to overcoming the challenges associated with copper when the wire dimensions approach the confinement limit, as well as continuing to develop low-k dielectric materials that can assure minimal cross-talk between lines. In addition, such challenges make it increasingly clear that device design must move from a top-down to a bottom-up approach in which the desired electronic characteristics are tailored from first-principles. It is with such fundamental hurdles in mind that ab initio calculations on the electronic and quantum transport properties of nanoscale metallic and semiconducting wires have been performed. More specifically, this study seeks to elaborate on the role played by confinement, contacts, dielectric environment, edge decoration, and defects in altering the electronic and transport characteristics of such systems. As experiments continue to achieve better control over the synthesis and design of nanowires, these results are expected to become increasingly more important for not only the interpretation of electronic and transport trends, but also in engineering the electronic structure of nanowires for the needs of the devices of the future. For the metallic atomic wires, the quantum transport properties are first investigated by considering finite, single-atom chains of aluminum, copper, gold, and silver sandwiched between gold contacts. Non-equilibrium Green's function based transport calculations reveal that even in the presence of the contact the conductivity of atomic-scale aluminum is greater than that of the other metals considered. This is

  16. Transport Properties of Complex Oxides: New Ideas and Insights from Theory and Simulation

    Science.gov (United States)

    Benedek, Nicole

    Complex oxides are one of the largest and most technologically important materials families. The ABO3 perovskite oxides in particular display an unparalleled variety of physical properties. The microscopic origin of these properties (how they arise from the structure of the material) is often complicated, but in many systems previous research has identified simple guidelines or `rules of thumb' that link structure and chemistry to the physics of interest. For example, the tolerance factor is a simple empirical measure that relates the composition of a perovskite to its tendency to adopt a distorted structure. First-principles calculations have shown that the tendency towards ferroelectricity increases systematically as the tolerance factor of the perovskite decreases. Can we uncover a similar set of simple guidelines to yield new insights into the ionic and thermal transport properties of perovskites? I will discuss recent research from my group on the link between crystal structure and chemistry, soft phonons and ionic transport in a family of layered perovskite oxides, the Ln2NiO4+δ Ruddlesden-Popper phases. In particular, we show how the lattice dynamical properties of these materials (their tendency to undergo certain structural distortions) can be correlated with oxide ion transport properties. Ultimately, we seek new ways to understand the microscopic origins of complex transport processes and to develop first-principles-based design rules for new materials based on our understanding.

  17. Oligomers Modulate Interfibril Branching and Mass Transport Properties of Collagen Matrices

    Science.gov (United States)

    Whittington, Catherine F.; Brandner, Eric; Teo, Ka Yaw; Han, Bumsoo; Nauman, Eric; Voytik-Harbin, Sherry L.

    2013-01-01

    Mass transport within collagen-based matrices is critical to tissue development, repair, and pathogenesis as well as the design of next generation tissue engineering strategies. This work shows how collagen precursors, specified by intermolecular cross-link composition, provide independent control of collagen matrix mechanical and transport properties. Collagen matrices were prepared from tissue-extracted monomers or oligomers. Viscoelastic behavior was measured in oscillatory shear and unconfined compression. Matrix permeability and diffusivity were measured using gravity-driven permeametry and integrated optical imaging, respectively. Both collagen types showed an increase in stiffness and permeability hindrance with increasing collagen concentration (fibril density); however, different physical property-concentration relationships were noted. Diffusivity wasn’t affected by concentration for either collagen type over the range tested. In general, oligomer matrices exhibited a substantial increase in stiffness and only a modest decrease in transport properties when compared to monomer matrices prepared at the same concentration. The observed differences in viscoelastic and transport properties were largely attributed to increased levels of interfibril branching within oligomer matrices. The ability to relate physical properties to relevant microstructure parameters, including fibril density and interfibril branching, is expected to advance the understanding of cell-matrix signaling as well as facilitate model-based prediction and design of matrix-based therapeutic strategies. PMID:23842082

  18. High-field thermal transports properties of REBCO coated conductors

    CERN Document Server

    Bonura, M

    2015-01-01

    The use of REBCO coated conductors is envisaged for many applications, extending from power cables to high-field magnets. Whatever the case, thermal properties of REBCO tapes play a key role for the stability of superconducting devices. In this work, we present the first study on the longitudinal thermal conductivity (k) of REBCO coated conductors in magnetic fields up to 19 T applied both parallelly and perpendicularly to the thermal-current direction. Copper-stabilized tapes from six industrial manufacturers have been investigated. We show that zero-field k of coated conductors can be calculated with an accuracy of ‡ 15% from the residual resistivity ratio of the stabilizer and the Cu/non-Cu ratio. Measurements performed at high fields have allowed us to evaluate the consistency of the procedures generally used for estimating in-field k in the framework of the Wiedemann-Franz law from an electrical characterization of the materials. In-field data are intended to provide primary ingredients for the ...

  19. Structure and transport properties of polymer grafted nanoparticles

    KAUST Repository

    Goyal, Sushmit

    2011-01-01

    We perform molecular dynamics simulations on a bead-spring model of pure polymer grafted nanoparticles (PGNs) and of a blend of PGNs with a polymer melt to investigate the correlation between PGN design parameters (such as particle core concentration, polymer grafting density, and polymer length) and properties, such as microstructure, particle mobility, and viscous response. Constant strain-rate simulations were carried out to calculate viscosities and a constant-stress ensemble was used to calculate yield stresses. The PGN systems are found to have less structural order, lower viscosity, and faster diffusivity with increasing length of the grafted chains for a given core concentration or grafting density. Decreasing grafting density causes depletion effects associated with the chains leading to close contacts between some particle cores. All systems were found to shear thin, with the pure PGN systems shear thinning more than the blend; also, the pure systems exhibited a clear yielding behavior that was absent in the blend. Regarding the mechanism of shear thinning at the high shear rates examined, it was found that the shear-induced decrease of Brownian stresses and increase in chain alignment, both correlate with the reduction of viscosity in the system with the latter being more dominant. A coupling between Brownian stresses and chain alignment was also observed wherein the non-equilibrium particle distribution itself promotes chain alignment in the direction of shear. © 2011 American Institute of Physics.

  20. Magneto-optical transport properties of monolayer WSe2

    Science.gov (United States)

    Tahir, M.; Vasilopoulos, P.

    2016-07-01

    The recent experimental realization of a high quality WSe2 leads to the possibility of magneto-optical measurements and the manipulation of the spin and valley degrees of freedom. We study the influence of the very strong spin-orbit coupling and of the anisotropic lifting of the valley pseudospin degeneracy on its magnetotransport properties. The energy spectrum of WSe2 is derived and discussed in the presence of a perpendicular magnetic field B . Correspondingly we evaluate the magneto-optical Hall conductivity and the optical longitudinal conductivity as functions of the frequency, magnetic field, and Fermi energy. They are strongly influenced by the field B and the strong spin splitting. The former exhibits valley polarization and the latter beatings of oscillations. The magneto-optical responses can be tuned in two different regimes: the microwave-to-terahertz regime and the visible-frequency one. The absorption peaks involving the n =0 LL appear in between these two regimes and show a magnetic control of the spin and valley splittings. We also evaluate the power absorption spectrum.

  1. Modifying zirconia solid electrolyte surface property to enhance oxide transport

    Energy Technology Data Exchange (ETDEWEB)

    Liaw, B.Y.; Song, S.Y. [Univ. of Hawaii, Honolulu, HI (United States)

    1996-12-31

    Bismuth-strontium-calcium-copper oxide (Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, BSCCO) is known for its high T{sub c} superconducting behavior and mixed conducting property. The applicability of similar high T{sub c} cuprates for intermediate-temperature solid oxide fuel cell (SOFC) application has been studied recently. We investigated the electrochemical behavior of several Ag{vert_bar}BSCCO{vert_bar}10 mol% yttria-stabilized zirconia (YSZ){vert_bar}Ag and Ag{vert_bar}YSZ{vert_bar}Ag cells using complex impedance spectroscopy. A highly uniform and porous microstructure was observed at the interface of the YSZ and BSCCO. The ionic conductivity determined from the Nyquest plots in the temperature range of 200-700{degrees}C agrees with the values reported in the literature. The specific resistance of the BSCCO{vert_bar}YSZ interface was also determined to be lower than those of the conventional manganite electrode, suggesting that BSCCO seems attractive for cathode applications in SOFC.

  2. Investigations of electrical transport properties of individual carbon nanotubes with nanoprober

    Science.gov (United States)

    Feng, Wei; Hayama, Kazumi; Akinaga, Hiroyuki

    2016-06-01

    We investigated and discussed quantitatively the transport properties of individual multiwalled (MW) carbon nanotubes (CNTs) by four-terminal measurement using a nanoprobing system. The homogeneity of the CNT was visibly examined using the electron beam absorbed current function of the nanoprober. The observed ohmic properties of the current-voltage characteristics and metallic transport properties of the CNTs proved that reliable contact of four probes was achieved on the outermost shell of MWCNTs. The experimental methodology was validated for the intrinsic properties of individual CNTs. Lower resistance per unit length was evaluated for thicker CNT. The measured resistance per unit length was lower than those reported by other researchers, but higher than ideally expected.

  3. Coupled light transport-heat diffusion model for laser dosimetry with dynamic optical properties

    Energy Technology Data Exchange (ETDEWEB)

    London, R.A.; Glinsky, M.E.; Zimmerman, G.B.; Eder, D.C. [Lawrence Livermore National Lab., CA (United States); Jacques, S.L. [Texas Univ., Houston, TX (United States). M.D. Anderson Cancer Center

    1995-03-01

    The effect of dynamic optical properties on the spatial distribution of light in laser therapy is studied via numerical simulations. A two-dimensional, time dependent computer program called LATIS is used. Laser light transport is simulated with a Monte Carlo technique including anisotropic scattering and absorption. Thermal heat transport is calculated with a finite difference algorithm. Material properties are specified on a 2-D mesh and can be arbitrary functions of space and time. Arrhenius rate equations are solved for tissue damage caused by elevated temperatures. Optical properties are functions of tissue damage, as determined by previous measurements. Results are presented for the time variation of the light distribution and damage within the tissue as the optical properties of the tissue are altered.

  4. The FupA/B protein uniquely facilitates transport of ferrous iron and siderophore-associated ferric iron across the outer membrane of Francisella tularensis live vaccine strain

    Science.gov (United States)

    Sen, Bhaswati

    2014-01-01

    Francisella tularensis is a highly infectious Gram-negative pathogen that replicates intracellularly within the mammalian host. One of the factors associated with virulence of F. tularensis is the protein FupA that mediates high-affinity transport of ferrous iron across the outer membrane. Together with its paralogue FslE, a siderophore–ferric iron transporter, FupA supports survival of the pathogen in the host by providing access to the essential nutrient iron. The FupA orthologue in the attenuated live vaccine strain (LVS) is encoded by the hybrid gene fupA/B, the product of an intergenic recombination event that significantly contributes to attenuation of the strain. We used 55Fe transport assays with mutant strains complemented with the different paralogues to show that the FupA/B protein of LVS retains the capacity for high-affinity transport of ferrous iron, albeit less efficiently than FupA of virulent strain Schu S4. 55Fe transport assays using purified siderophore and siderophore-dependent growth assays on iron-limiting agar confirmed previous findings that FupA/B also contributes to siderophore-mediated ferric iron uptake. These assays further demonstrated that the LVS FslE protein is a weaker siderophore–ferric iron transporter than the orthologue from Schu S4, and may be a result of the sequence variation between the two proteins. Our results indicate that iron-uptake mechanisms in LVS differ from those in Schu S4 and that functional differences in the outer membrane iron transporters have distinct effects on growth under iron limitation. PMID:24307666

  5. The unique axon trajectory of the accessory nerve is determined by intrinsic properties of the neural tube in the avian embryo.

    Science.gov (United States)

    Bai, Zhongtian; Pu, Qin; Haque, Ziaul; Wang, Jianlin; Huang, Ruijin

    2016-05-01

    The accessory nerve is a cranial nerve, composed of only motor axons, which control neck muscles. Its axons ascend many segments along the lateral surface of the cervical spinal cord and hindbrain. At the level of the first somite, they pass ventrally through the somitic mesoderm into the periphery. The factors governing the unique root trajectory are unknown. Ablation experiments at the accessory nerve outlet points have shown that somites do not regulate the trajectory of the accessory nerve fibres. Factors from the neural tube that may control the longitudinal pathfinding of the accessory nerve fibres were tested by heterotopic transplantations of an occipital neural tube to the cervical and thoracic level. These transplantations resulted in a typical accessory nerve trajectory in the cervical and thoracic spinal cord. In contrast, cervical neural tube grafts were unable to give rise to the typical accessory nerve root pattern when transplanted to occipital level. Our results show that the formation of the unique axon root pattern of the accessory nerve is an intrinsic property of the neural tube.

  6. Formulating gels for decreased mucociliary transport using rheologic properties: Polyacrylic acids

    OpenAIRE

    Shah, Ankur J.; Donovan, Maureen D.

    2007-01-01

    The purpose of these studies was to identify the rheologic properties of polyacrylic acid gels necessary for optimal reductions in mucociliary clearance. The mucociliary transport of 2 bioadhesive polyacrylic acid polymers, polycarbophil and carbopol, was assessed in vitro by measuring their clerance rates across explants of ciliated bovine tracheal tissue. The viscoelastic properties of polymer gels were measured in the presence of mucus using controlled stress rheometry. Combinations of app...

  7. Structure and transport properties of ethylcellulose membranes with different types and granulation of magnetic powder

    Science.gov (United States)

    Krasowska, Monika; Strzelewicz, Anna; Rybak, Aleksandra; Dudek, Gabriela; Cieśla, Michał

    2016-06-01

    Structure and transport properties of ethylcellulose membranes with dispersed magnetic powder were investigated. The study mainly focused on diffusion, which is one of the transport mechanisms. The transport properties depend on many parameters like: polymeric matrix used, type of powder, its amount and granulation. The structure of the pattern formed by magnetic particles in the membrane matrix was studied. Description of the system was based on the phenomenological and molecular (random walk on a fractal lattice) approaches. Two parameters were calculated: the fractal dimension of random walk dw, and the fractal dimension of membrane structure df. The knowledge of both parameters made it possible to use the generalized equation of diffusion on the fractal structure obtained by Metzler et al. The research was carried out to determine the influence of magnetic powder granulation on the transport properties. The results showed that the random walk within the membranes of the smallest magnetic powder granulation was of the most subdiffusive character. Detailed investigation and quantitative description of gas transport through the membranes enables designing the membranes to be used in air oxygen enrichment.

  8. One-pot synthesis of biocompatible Te-phenol formaldehyde resin core-shell nanowires with uniform size and unique fluorescent properties by a synergized soft-hard template process

    Energy Technology Data Exchange (ETDEWEB)

    Qian Haisheng; Zhu Enbo; Zheng Shunji; Yang Xingyun; Li Liangchao; Tong Guoxiu [Department of Chemistry, College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004 (China); Li Zhengquan; Hu Yong; Guo Changfa [Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004 (China); Guo Huichen, E-mail: shqian@zjnu.cn, E-mail: ghch-2004@hotmail.com [State Key Laboratory of Veterinary Etiological Biology and Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 11, Lanzhou, Gansu 730046 (China)

    2010-12-10

    One-pot hydrothermal process has been developed to synthesize uniform Te-phenol formaldehyde resin core-shell nanowires with unique fluorescent properties. A synergistic soft-hard template mechanism has been proposed to explain the formation of the core-shell nanowires. The Te-phenol formaldehyde resin core-shell nanowires display unique fluorescent properties, which give strong luminescent emission in the blue-violet and green regions with excitation wavelengths of 270 nm and 402 nm, respectively.

  9. Seismic properties of volcanic rocks from Montagne Pelée (Martinique, Lesser Antilles) and their relations to transport properties

    Science.gov (United States)

    Bernard, M.-L.; Zamora, M.

    2012-04-01

    Numerous laboratory and theoretical studies on the physical properties of rocks and their relationships - lead mainly in the framework of petroleum exploration - show that rock physics is necessary for an accurate quantitative interpretation of geophysical observations. Moreover joint inversion of different geophysical datasets is emerging as an important tool to enhance resolution and decrease inversion artifacts in imaging of structurally complex areas such as volcanoes. In many cases, the coupling between the inverted parameters is based on empirical or theoretical relationships derived from laboratory data. Consequently rock physics can be used to: interpret simultaneously several geophysical datasets on volcanoes when they are available, improve the imaging of volcano structures, and better understand the coupled processes that can occur during volcanic unrest. It's in this context that we lead a laboratory study on the transport properties (permeability, thermal and electrical conductivities) and seismic properties (velocity and attenuation of P and S waves) of volcanic rocks representative of Montagne Pelée (Martinique) deposits. In this presentation we will focus on (1) the seismic properties and (2) the relations between seismic and transport properties. The 43 samples collected are representative of the main lithological units of this volcano: vesicular lava blocks and indurated ashed from indurated block-and-ash flows also called breccias, vesicular lava blocks from "Pelean nuee ardente" flows, scoriae from scoria flows, pumices from ash-and-pumices flows, and dense lava blocks from lava flows and lava domes. Their total porosity varies over a wide range from 4 to 73%. Since the samples present similar chemical and mineralogical compositions (andesites), the main difference between the samples comes from their pore structure and reflects differences in the mechanisms of magma degassing and vesiculation during their formation (Bernard et al., 2007). This

  10. Aerosol properties and radiative forcing for three air masses transported in Summer 2011 to Sopot, Poland

    Science.gov (United States)

    Rozwadowska, Anna; Stachlewska, Iwona S.; Makuch, P.; Markowicz, K. M.; Petelski, T.; Strzałkowska, A.; Zieliński, T.

    2013-05-01

    Properties of atmospheric aerosols and solar radiation reaching the Earth's surface were measured during Summer 2011 in Sopot, Poland. Three cloudless days, characterized by different directions of incoming air-flows, which are typical transport pathways to Sopot, were used to estimate a radiative forcing due to aerosols present in each air mass.

  11. A whole range hygric material model: Modelling liquid and vapour transport properties in porous media

    DEFF Research Database (Denmark)

    Scheffler, Gregor Albrecht; Plagge, Rudolf

    2010-01-01

    This paper addresses the modelling of hygric material coefficients bridging the gap between measured material properties and the non-linear storage and transport coefficients in the transfer equation. The conductivity approach and a bundle of tubes model are the basis. By extending this model...

  12. Transport and Phase Equilibria Properties for Steam Flooding of Heavy Oils

    Energy Technology Data Exchange (ETDEWEB)

    Gabitto, Jorge; Barrufet, Maria

    2001-12-18

    The objectives of this research included experimental determination and rigorous modeling and computation of phase equilibria, volumetric, and transport properties of hydrocarbon/CO2/water mixtures at pressures and temperatures typical of steam injection processes for thermal recovery of heavy oils.

  13. Predicting Soil-Air and Soil-Water Transport Properties During Soil Vapor Extraction

    DEFF Research Database (Denmark)

    Poulsen, Tjalfe

    designing and operating remediation systems. Simple and accurate models for estimating soil properties from soil parameters that are easy to measure are useful in connection with preliminary remedial investigations and evaluation of remedial technologies. In this work simple models for predicting transport...

  14. Transport and Phase Equilibria Properties for Steam Flooding of Heavy Oils

    Energy Technology Data Exchange (ETDEWEB)

    Gabitto, Jorge; Barufet, Maria

    2002-11-20

    The objectives of this research included experimental determination and rigorous modeling and computation of phase equilibrium diagrams, volumetric, and transport properties of hydrocarbon/CO2/water mixtures at pressures and temperatures typical of steam injection processes for thermal recovery of heavy oils.

  15. A law of mixtures for transport properties in binary particulate composites

    Science.gov (United States)

    Duncan, K. L.; Lodenquai, J. F.; Wagh, A. S.; Goretta, K. C.

    1998-09-01

    A connected-grain model was developed earlier to explain mechanical and thermal properties of porous ceramics and sedimentary rocks. We have now generalized this model for binary particulate composites, based on simulation of a connected-grain structure of individual components of the composites by randomly selecting individual grains and shrinking them. Repetition of this procedure results in a structure of a binary particulate composite that contains channels of individual components, through which transport occurs. We developed a generalized law of mixtures in which transport properties are expressed as scaling relationships that depend on the shrinking parameter expressed as an exponent. This parameter provides the skewness of the distribution of the grains. The model is compared with various transport properties of binary composites reported in the literature. In addition, the model is tested on YBa2Cu3Ox superconductors and Ag composites that were fabricated in our laboratory and tested for electrical conductivity and elastic modulus. This test demonstrates how the model predicts two entirely different transport properties through their common microstructure and grain-size distribution.

  16. Quark Transport Properties in the Region of Coexistence of Both Hadronic and QGP Phases

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiang-Jun; LI Hong; WANG Gang; ZHANG Wei-Ning; HUO Lei

    2001-01-01

    The physical picture of coexistence of both hadronic and QGP phases is given by Friedberg and T.D. Lee's nontopology soliton model. The transport properties of quark in color space and spin space in a system of two-phase coexistence are investigated from both quantum and classical theories.

  17. Ab initio description of the thermoelectric properties of heterostructures in the diffusive limit of transport

    DEFF Research Database (Denmark)

    Hinsche, Nicki Frank; Rittweger, Florian; Hölzer, Martin

    2016-01-01

    -principles calculations a consistent and convenient method is presented to fully describe the thermoelectric properties in the diffusive limit of transport for bulk systems and their associated heterostructures. While fundamentals of the functionality of phonon-blocking and electron-transmitting superlattices could...

  18. Transport and Phase Equilibria Properties for Steam Flooding of Heavy Oils

    Energy Technology Data Exchange (ETDEWEB)

    Gabitto, Jorge; Barrufet, Maria

    2002-11-20

    The objectives of this research included experimental determination and rigorous modeling and computation of phase equilibrium diagrams, volumetric, and transport properties of hydrocarbon/CO2/water mixtures at pressures and temperatures typical of steam injection processes for thermal recovery of heavy oils.

  19. Electrical transport properties of oligothiophene based molecular films studied by current sensing Atomic Force Microscopy

    NARCIS (Netherlands)

    Hendriksen, Bas L.M.; Martin, Florent; Qi, Yabing; Qi, Y.; Mauldin, Clayton; Vukmirovic, Nenad; Ren, JunFeng; Wormeester, Herbert; Katan, Allard J.; Altoe, Virginia; Aloni, Shaul; Frechet, Jean M.J.; Wang, Lin-Wang; Salmeron, Miquel

    2011-01-01

    Using conducting probe atomic force microscopy (CAFM) we have investigated the electrical conduction properties of monolayer films of a pentathiophene derivative on a SiO2/Si-p+ substrate. By a combination of current–voltage spectroscopy and current imaging we show that lateral charge transport

  20. Quantum transport properties of the three-dimensional Dirac semimetal Cd3As2 single crystals

    Science.gov (United States)

    He, Lan-Po; Li, Shi-Yan

    2016-11-01

    The discovery of the three-dimensional Dirac semimetals have expanded the family of topological materials, and attracted massive attentions in recent few years. In this short review, we briefly overview the quantum transport properties of a well-studied three-dimensional Dirac semimetal, Cd3As2. These unusual transport phenomena include the unexpected ultra-high charge mobility, large linear magnetoresistivity, remarkable Shubnikov-de Hass oscillations, and the evolution of the nontrivial Berry’s phase. These quantum transport properties not only reflect the novel electronic structure of Dirac semimetals, but also give the possibilities for their future device applications. Project supported by the National Basic Research Program of China (Grant Nos. 2012CB821402 and 2015CB921401), the National Natural Science Foundation of China, the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, and STCSM of China (Grant No. 15XD1500200).

  1. Theoretical study on charge injection and transport properties of six emitters with push-pull structure

    Science.gov (United States)

    Lin, Tao; Liu, Xiaojun; Lou, Zhidong; Hou, Yanbing; Teng, Feng

    2014-08-01

    The charge injection and transport properties of six organic light-emitting molecules with push-pull structures were studied by theoretical calculations. The ground-state geometries for the neutral, cationic and anionic states were optimized using density functional theory. Subsequently, the ionization potentials and electron affinities were calculated. We computed the reorganization energies and the transfer integrals based on the Marcus electron transfer theory. It was found that in addition to being emitters the six compounds are multifunctional materials being capable of transport for both holes and electrons. Moreover, the double-branched compound DCDPC2 was found to have higher charge injection ability and better balanced charge transport properties than single-branched compounds.

  2. Transport properties of zigzag graphene nanoribbons adsorbed with single iron atom

    Institute of Scientific and Technical Information of China (English)

    杨玉娥; 肖杨; 颜晓红; 戴昌杰

    2015-01-01

    We have performed density-functional calculations of the transport properties of the zigzag graphene nanoribbon (ZGNR) adsorbed with a single iron atom. Two adsorption configurations are considered, i.e., iron adsorbed on the edge and on the interior of the nanoribbon. The results show that the transport features of the two configurations are similar. However, the transport properties are modified due to the scattering effects induced by coupling of the ZGNR band states to the localized 3d-orbital state of the iron atom. More importantly, one can find that several dips appear in the transmission curve, which is closely related to the above mentioned coupling. We expect that our results will have potential applications in graphene-based spintronic devices.

  3. State-specific transport properties of partially ionized flows of electronically excited atomic gases

    Science.gov (United States)

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

    2017-03-01

    State-to-state approach for theoretical study of transport properties in atomic gases with excited electronic degrees of freedom of both neutral and ionized species is developed. The dependence of atomic radius on the electronic configuration of excited atoms is taken into account in the transport algorithm. Different cutoff criteria for increasing atomic radius are discussed and the limits of applicability for these criteria are evaluated. The validity of a Slater-like model for the calculation of state-resolved transport coefficients in neutral and ionized atomic gases is shown. For ionized flows, a method of evaluation for effective cross-sections of resonant charge-transfer collisions is suggested. Accurate kinetic theory algorithms for modelling the state-specific transport properties are applied for the prediction of transport coefficients in shock heated flows. Based on the numerical observations, different distributions over electronic states behind the shock front are considered. For the Boltzmann-like distributions at temperatures greater than 14,000 K, an important effect of electronic excitation on the partial thermal conductivity and viscosity coefficients is found for both neutral and ionized atomic gases: increasing radius of excited atoms causes a strong decrease in these transport coefficients. Similarly, the presence of electronically excited states with increased atomic radii leads to reduced diffusion coefficients. Nevertheless the overall impact of increasing effective cross-sections on the transport properties just behind the shock front under hypersonic reentry conditions is found to be minor since the populations of high-lying electronic energy levels behind the shock waves are low.

  4. Schisandra chinensis Peptidoglycan-Assisted Transmembrane Transport of Lignans Uniquely Altered the Pharmacokinetic and Pharmacodynamic Mechanisms in Human HepG2 Cell Model

    Science.gov (United States)

    Chyau, Charng-Cherng; Ker, Yaw-Bee; Chang, Chi-Huang; Huang, Shiau-Huei; Wang, Hui-Er; Peng, Chiung-Chi; Peng, Robert Y.

    2014-01-01

    Schisandra chinensis (Turz Baill) (S. chinensis) (SC) fruit is a hepatoprotective herb containing many lignans and a large amount of polysaccharides. A novel polysaccharide (called SC-2) was isolated from SC of MW 841 kDa, which exhibited a protein-to-polysaccharide ratio of 0.4089, and showed a characteristic FTIR spectrum of a peptidoglycan. Powder X-ray diffraction revealed microcrystalline structures within SC-2. SC-2 contained 10 monosaccharides and 15 amino acids (essential amino acids of 78.12%w/w). In a HepG2 cell model, SC-2 was shown by MTT and TUNEL assay to be completely non-cytotoxic. A kinetic analysis and fluorescence-labeling technique revealed no intracellular disposition of SC-2. Combined treatment of lignans with SC-2 enhanced the intracellular transport of schisandrin B and deoxyschisandrin but decreased that of gomisin C, resulting in alteration of cell-killing bioactivity. The Second Law of Thermodynamics allows this type of unidirectional transport. Conclusively, SC-2 alters the transport and cell killing capability by a “Catcher-Pitcher Unidirectional Transport Mechanism”. PMID:24475039

  5. Schisandra chinensis peptidoglycan-assisted transmembrane transport of lignans uniquely altered the pharmacokinetic and pharmacodynamic mechanisms in human HepG2 cell model.

    Directory of Open Access Journals (Sweden)

    Charng-Cherng Chyau

    Full Text Available Schisandra chinensis (Turz Baill (S. chinensis (SC fruit is a hepatoprotective herb containing many lignans and a large amount of polysaccharides. A novel polysaccharide (called SC-2 was isolated from SC of MW 841 kDa, which exhibited a protein-to-polysaccharide ratio of 0.4089, and showed a characteristic FTIR spectrum of a peptidoglycan. Powder X-ray diffraction revealed microcrystalline structures within SC-2. SC-2 contained 10 monosaccharides and 15 amino acids (essential amino acids of 78.12%w/w. In a HepG2 cell model, SC-2 was shown by MTT and TUNEL assay to be completely non-cytotoxic. A kinetic analysis and fluorescence-labeling technique revealed no intracellular disposition of SC-2. Combined treatment of lignans with SC-2 enhanced the intracellular transport of schisandrin B and deoxyschisandrin but decreased that of gomisin C, resulting in alteration of cell-killing bioactivity. The Second Law of Thermodynamics allows this type of unidirectional transport. Conclusively, SC-2 alters the transport and cell killing capability by a "Catcher-Pitcher Unidirectional Transport Mechanism".

  6. Peptides actively transported across the tympanic membrane: Functional and structural properties

    Science.gov (United States)

    Kurabi, Arwa; Beasley, Kerry A.; Chang, Lisa; McCann, James; Pak, Kwang; Ryan, Allen F.

    2017-01-01

    Otitis media (OM) is the most common infectious disease of children under six, causing more antibiotic prescriptions and surgical procedures than any other pediatric condition. By screening a bacteriophage (phage) library genetically engineered to express random peptides on their surfaces, we discovered unique peptides that actively transport phage particles across the intact tympanic membrane (TM) and into the middle ear (ME). Herein our goals were to characterize the physiochemical peptide features that may underlie trans-TM phage transport; assess morphological and functional effects of phage peptides on the ME and inner ear (IE); and determine whether peptide-bearing phage transmigrate from the ME into the IE. Incubation of five peptide-bearing phage on the TM for over 4hrs resulted in demonstrably superior transport of one peptide, in level and in exponential increase over time. This suggests a preferred peptide motif for TM active transport. Functional and structural comparisons revealed unique features of this peptide: These include a central lysine residue, isoelectric point of 0.0 at physiological pH and a hydrophobic C-terminus. When the optimal peptide was applied to the TM independent of phage, similar transport was observed, indicating that integration into phage is not required. When 109 particles of the four different trans-TM phage were applied directly into the ME, no morphological effects were detected in the ME or IE when compared to saline or wild-type (WT) phage controls. Comparable, reversible hearing loss was observed for saline controls, WT phage and trans-TM peptide phage, suggesting a mild conductive hearing loss due to ME fluid. Perilymph titers after ME incubation established that few copies of trans-TM peptide phage crossed into the IE. The results suggest that, within the parameters tested, trans-TM peptides are safe and could be used as potential agents for noninvasive delivery of drugs, particles and gene therapy vectors to the ME

  7. Nearly a Decade of CALIPSO Observations of Asian and Saharan Dust Properties near Source and Transport Regions

    Science.gov (United States)

    Omar, A. H.; Tackett, J. L.; Liu, Z.; Vaughan, M. A.; Trepte, C. R.; Winker, D. M.; Yu, H.

    2015-12-01

    The lidar on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission, makes robust measurements of dust and has generated a length of record that is significant both seasonally and inter-annually. We exploit this record to determine a multi-year climatology of the properties of Asian and Saharan dust, in particular seasonal optical depths, layer frequencies, and layer heights of dust gridded in accordance with the Level 3 data products protocol between 2006 and 2015. The data are screened using standard CALIPSO quality assurance flags, cloud aerosol discrimination (CAD) scores, overlying features and layer properties. To evaluate the effects of transport on small-scale phenomena such as morphology, vertical extent and size of the dust layers, we compare probability distribution functions of the layer integrated volume depolarization ratios, geometric depths and integrated attenuated color ratios near the source to the same distributions in the far field or transport region. CALIPSO is collaboration between NASA and Centre National d'Études Spatiales (CNES), was launched in April 2006 to provide vertically resolved measurements of cloud and aerosol distributions. The primary instrument on the CALIPSO satellite is the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), a near-nadir viewing two-wavelength polarization-sensitive instrument. The unique nature of CALIOP measurements make it quite challenging to validate backscatter profiles, aerosol type, and cloud phase, all of which are used to retrieve extinction and optical depth. To evaluate the uncertainty in the lidar ratios, we compare the values computed from dust layers overlying opaque water clouds, considered nominal, with the constant lidar ratio value used in the CALIOP algorithms for dust. We also explore the effects of noise on the CALIOP retrievals at daytime by comparing the distributions of the properties at daytime to the nighttime distributions.

  8. Transport properties of room temperature ionic liquids from classical molecular dynamics

    CERN Document Server

    Andreussi, Oliviero

    2012-01-01

    Room Temperature Ionic Liquids (RTILs) have attracted much of the attention of the scientific community in the past decade due the their novel and highly customizable properties. Nonetheless their high viscosities pose serious limitations to the use of RTILs in practical applications. To elucidate some of the physical aspects behind transport properties of RTILs, extensive classical molecular dynamics (MD) calculations are reported. Bulk viscosities and ionic conductivities of butyl-methyl-imidazole based RTILs are presented over a wide range of temperatures. The dependence of the properties of the liquids on simulation parameters, e.g. system size effects and choice of the interaction potential, is analyzed.

  9. 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

    techniques and tight-binding calculations to illustrate these materials' transmission properties and give physical arguments to interpret the numerical results. Specifically, above the Fermi energy we find a strong reduction in electron transmission due to localized states in certain regions of the structure......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 initio...

  10. Tribological properties of epoxy composite materials for marine and river transport

    Science.gov (United States)

    Buketov, A. V.; Maruschak, P. O.; Brailo, N. V.; Akimov, A. V.; Kobelnik, O. S.; Panin, S. V.

    2016-11-01

    Tribological properties of epoxy composites filled with thermoplastics and dispersed particles under sea water environment were analyzed. It has been revealed that the composition, sliding friction conditions, as well as the marine environment, substantially affect the tribological properties of the materials. The improvement of tribological properties of epoxycomposite thermosetting plastics after their filling with thermoplastic polyamide PA-6 granules under friction in sea water environment has been proved. The recommendations on applying the developed material in friction parts for marine and river transport were formulated.

  11. A Genetic Algorithm for Simultaneous Determination of Thin Films Thermal Transport Properties and Contact Resistance

    Institute of Scientific and Technical Information of China (English)

    Zhengxing HUANG; Zhen'an TANG; Ziqiang XU; Haitao DING; Yuqin GU

    2006-01-01

    A genetic algorithm (GA) was studied to simultaneously determine the thermal transport properties and the contact resistance of thin films deposited on a thick substrate. A pulsed photothermal reflectance (PPR) system was employed for the measurements. The GA was used to extract the thermal properties. Measurements were performed on SiO2 thin films of different thicknesses on silicon substrate. The results show that the GA accompanied with the PPR system is useful for the simultaneous determination of thermal properties of thin films on a substrate.

  12. Surface and transport properties of Cu-Sn-Ti liquid alloys

    Institute of Scientific and Technical Information of China (English)

    R. Novakovic; E. Ricci; S. Amore; T. Lanata

    2006-01-01

    The lack of experimental data and / or limited experimental information concerning both surface and transport properties of liquid alloys often require the prediction of these quantities. An attempt has been made to link the thermophysical properties of a ternary Cu-Sn-Ti system and its binary Cu-Sn, Cu-Ti and Sn-Ti subsystems with the bulk through the study of the concentration dependence of various thermodynamic, structural, surface and dynamic properties in the frame of the statistical mechanical theory in conjunction with the quasi-lattce theory (QLT). This formalism provides valuable qualitative insight into mixing processes that occur in molten alloys.

  13. Applications of asymmetric nanotextured parylene surface using its wetting and transport properties

    Science.gov (United States)

    Sekeroglu, Koray

    In this thesis, basic digital fluidics devices were introduced using polymeric nanorods (nano-PPX) inspired from nature. Natural inspiration ignited this research by observing butterfly wings, water strider legs, rye grass leaves, and their asymmetric functions. Nano-PPX rods, manufactured by an oblique angle polymerization (OAP) method, are asymmetrically aligned structures that have unidirectional wetting properties. Nano-PPX demonstrates similar functions to the directional textured surfaces of animals and plants in terms of wetting, adhesion, and transport. The water pin-release mechanism on the asymmetric nano-PPX surface with adhesion function provides a great transport property. How the asymmetry causes transport is discussed in terms of hysteresis and interface contact of water droplets. In this study, the transport property of nano-PPX rods is used to guide droplets as well as transporting cargo such as microgels. With the addition of tracks on the nano-PPX rods, the surfaces were transformed into basic digital fluidics devices. The track-assisted nano-PPX has been employed to applications (i.e. sorting, mixing, and carrying cargo particles). Thus, digital fluidics devices fabricated on nano-PPX surface is a promising pathway to assemble microgels in the field of bioengineering. The characterization of the nano textured surface was completed using methods such as Scanning Electron Microscopy, Atomic Force Microscopy, Contact Angle Goniometry, and Fourier Transform Infra-Red Spectroscopy. These methods helped to understand the physical and chemical properties of nano-PPX. Parameters such as advancing and receding contact angles, nanorod tilt angle, and critical drop volumes were utilized to investigate the anisotropic wetting properties of nano-PPX surface. This investigation explained the directional wetting behavior of the surface as well as approaching new design parameters for adjusting surface properties. The nanorod tilt angle was a key parameter

  14. Unique properties of the classical bovine spongiform encephalopathy strain and its emergence from H-type bovine spongiform encephalopathy substantiated by VM transmission studies.

    Science.gov (United States)

    Bencsik, Anna; Leboidre, Mikael; Debeer, Sabine; Aufauvre, Claire; Baron, Thierry

    2013-03-01

    In addition to classical bovine spongiform encephalopathy (C-BSE), which is recognized as being at the origin of the human variant form of Creutzfeldt-Jakob disease, 2 rare phenotypes of BSE (H-type BSE [H-BSE] and L-type BSE [L-BSE]) were identified in 2004. H-type BSE and L-BSE are considered to be sporadic forms of prion disease in cattle because they differ from C-BSE with respect to incubation period, vacuolar pathology in the brain, and biochemical properties of the protease-resistant prion protein (PrP) in natural hosts and in some mouse models that have been tested. Recently, we showed that H-BSE transmitted to C57Bl/6 mice resulted in a dissociation of the phenotypic features, that is, some mice showed an H-BSE phenotype, whereas others had a C-BSE phenotype. Here, these 2 phenotypes were further studied in VM mice and compared with cattle C-BSE, H-BSE, and L-BSE. Serial passages from the C-BSE-like phenotype on VM mice retained similarities with C-BSE. Moreover, our results indicate that strains 301V and 301C derived from C-BSE transmitted to VM and C57Bl/6 mice, respectively, are fundamentally the same strain. These VM transmission studies confirm the unique properties of the C-BSE strain and support the emergence of a strain that resembles C-BSE from H-BSE.

  15. Transport and mechanical properties of self consolidating concrete with high volume fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Mustafa Sahmaran; Ismail O. Yaman; Mustafa Tokyay [Gaziantep University, Gaziantep (Turkey). Department of Civil Engineering

    2009-02-15

    This paper presents the transport and mechanical properties of self consolidating concrete that contain high percentages of low-lime and high-lime fly ash (FA). Self consolidating concretes (SCC) containing five different contents of high-lime FA and low-lime FA as a replacement of cement (30, 40, 50, 60 and 70 by weight of total cementitious material) are examined. For comparison, a control SCC mixture without any FA was also produced. The fresh properties of the SCCs were observed through, slump flow time and diameter, V-funnel flow time, L-box height ratio, and segregation ratio. The hardened properties included the compressive strength, split tensile strength, drying shrinkage and transport properties (absorption, sorptivity and rapid chloride permeability tests) up to 365 days. Test results confirm that it is possible to produce SCC with a 70% of cement replacement by both types of FA. The use of high volumes of FA in SCC not only improved the workability and transport properties but also made it possible to produce concretes between 33 and 40 MPa compressive strength at 28 days, which exceeds the nominal compressive strength for normal concrete (30 MPa).

  16. The electronic transport properties of graphene-like beryllium sulfide nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    An, Yipeng, E-mail: ypan@htu.edu.cn; Wang, Tianxing; Fu, Zhaoming; Chu, Xingli; Xu, Guoliang

    2015-09-11

    The electronic transport properties of zigzag beryllium sulfide nanoribbons (ZBeSNRs) are investigated by first-principles calculations. The results indicate that the electrons flow mainly through the two edges of ZBeSNRs. The electron transmission pathways are analyzed in detail. The ZBeSNRs show the remarkable negative differential resistance (NDR) properties, which are independent of the nanoribbon width due to their very similar band structures. The NDR behavior can be maintained by introducing a Be or S atom vacancy defect. The H-passivated ZBeSNR presents the interesting current-limited effect. The ZBeSNRs could be the promising candidates for the future nano devices, such as NDR devices. - Highlights: • The electronic transport properties of zigzag BeS nanoribbons (ZBeSNRs) are investigated. • The ZBeSNRs show the remarkable negative differential resistance (NDR) properties. • The electronic transport properties of ZBeSNRs are independent of the nanoribbon width. • The NDR behavior can be maintained by introducing a Be or S atom vacancy defect. • The H-passivated ZBeSNR presents the interesting current-limited effect.

  17. Modulation of the electron transport properties in graphene nanoribbons doped with BN chains

    Directory of Open Access Journals (Sweden)

    Wu Liu

    2014-06-01

    Full Text Available Using density-functional theory and the non-equilibrium Green's function method, the electron transport properties of zigzag graphene nanoribbons (ZGNRs doped with BN chains are studied by systematically calculating the energy band structure, density of states and the transmission spectra for the systems. The BN chains destroyed the electronic transport properties of the ZGNRs, and an energy gap appeared for the ZGNRs, and displayed variations from a metal to a wide-gap semiconductor. With an increase in the number of BN chains, the band gap increased gradually in the band structure and the transmission coefficient decreased near the Fermi surface. Additionally, the doping position had a significant effect on the electronic properties of the ZGNRs.

  18. Electron transport properties in InAs four-terminal ballistic junctions under weak magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Koyama, M.; Fujiwara, K.; Amano, N.; Maemoto, T.; Sasa, S.; Inoue, M. [Nanomaterials Microdevices Research Center, Osaka Institute of Technology (JP)u, Osaka 535-8585 (Japan)

    2009-06-15

    We report on the electron transport properties based on ballistic electrons under magnetic fields in four-terminal ballistic junctions fabricated on an InAs/AlGaSb heterostructure. The four-terminal junction structure is composed of two longitudinal stems with two narrow wires slanted with 30 degree from the perpendicular axis. The electron focusing peak was obtained with the bend resistance measurement. Then it was investigated the nonlinear electron transport property of potential difference between longitudinal stems due to ballistic electrons with applying direct current from narrow wires. Observed nonlinearity showed clear rectification effects which have negative polarity regardless of input voltage polarity. Although this nonlinearity was qualitatively changed due to the Lorentz force under magnetic fields, the degradation of ballistic effects on nonlinear properties were observed when the current increased to higher strength. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Graphene transport properties upon exposure to PMMA processing and heat treatments

    DEFF Research Database (Denmark)

    Gammelgaard, Lene; Caridad, Jose; Cagliani, Alberto

    2014-01-01

    , allowing us to measure the evolution of the electrical transport properties during individual processing steps from the initial as-exfoliated to the PMMA-processed graphene. Heating generally promotes the conformation of graphene to SiO2 and is found to play a major role for the electrical properties......The evolution of graphene's electrical transport properties due to processing with the polymer polymethyl methacrylate (PMMA) and heat are examined in this study. The use of stencil (shadow mask) lithography enables fabrication of graphene devices without the usage of polymers, chemicals or heat...... of graphene while PMMA residues are found to be surprisingly benign. In accordance with this picture, graphene devices with initially high carrier mobility tend to suffer a decrease in carrier mobility, while in contrast an improvement is observed for low carrier mobility devices. We explain this by noting...

  20. Transport properties of pyroclastic rocks from Montagne Pelée volcano (Martinique, Lesser Antilles)

    Science.gov (United States)

    Bernard, Marie-Lise; Zamora, Maria; GéRaud, Yves; Boudon, Georges

    2007-05-01

    The hydraulic and electrical properties of pyroclastic rocks have been investigated in laboratory on a representative sampling of Montagne Pelée (Martinique, France) deposits with renewed interest in geophysical applications. This sampling covers all the lithologic units of this volcano: lava dome and lava flows, pumices from ash-and-pumice fall and flow deposits, lava blocks from block-and-ash flow and Peléean "nuées ardentes" deposits, scoriae from scoria flow deposits. The connected porosity varies over a wide range from 3 to 62%. The unconnected porosity is important only on pumices where it can reach 15%. The permeability covers more than 5 orders of magnitude, ranging from 10-16 to 35 × 10-12 m2. The higher values are obtained on lava blocks and the scoriae, even if these rocks are less porous than the pumices. The formation factor ranges from 7 to 1139. The transport properties of these rocks are slightly correlated with porosity. This indicates that these properties are not only controlled by the connected porosity. To connect the transport properties to the textural characteristics of the pore network of pyroclastic rocks, different models, based on geometrical considerations or percolation theory, were tested. The pore access radius distribution and the tortuosity control the transport properties of pyroclastic rocks. Consequently, the models (electric and hydraulic) based on the concept of percolation (e.g., the models of Katz and Thompson), apply better than the equivalent channel model of Kozeny-Carman. In addition, the difference in transport properties observed on lava blocks and pumices confirms that the mechanisms of degassing and vesiculation are different for these two types of rock.

  1. Functionalization of boron diiminates with unique optical properties: multicolor tuning of crystallization-induced emission and introduction into the main chain of conjugated polymers.

    Science.gov (United States)

    Yoshii, Ryousuke; Hirose, Amane; Tanaka, Kazuo; Chujo, Yoshiki

    2014-12-31

    In this article, we report the unique optical characteristics of boron diiminates in the solid states. We synthesized the boron diiminates exhibiting aggregation-induced emission (AIE). From the series of optical measurements, it was revealed that the optical properties in the solid state should be originated from the suppression of the molecular motions of the boron diiminate units. The emission colors were modulated by the substitution effects (λ(PL,crystal) = 448-602 nm, λ(PL,amorphous) = 478-645 nm). Strong phosphorescence was observed from some boron diiminates deriving from the effects of two imine groups. Notably, we found some of boron diiminates showed crystallization-induced emission (CIE) properties derived from the packing differences from crystalline to amorphous states. The 15-fold emission enhancement was observed by the crystallization (Φ(PL,crystal) = 0.59, Φ(PL,amorphous) = 0.04). Next, we conjugated boron diiminates with fluorene. The synthesized polymers showed good solubility in the common solvents, film formability, and thermal stability. In addition, because of the expansion of main-chain conjugation, the peak shifts to longer wavelength regions were observed in the absorption/emission spectra of the polymers comparing to those of the corresponding boron diiminate monomers (λ(abs) = 374-407 nm, λ(PL) = 509-628 nm). Furthermore, the absorption and the emission intensities were enhanced via the light-harvesting effect by the conjugation with fluorene. Finally, we also demonstrated the dynamic reversible alterations of the optical properties of the polymer thin films by exposing to acidic or basic vapors.

  2. Using non-invasive molecular spectroscopic techniques to detect unique aspects of protein Amide functional groups and chemical properties of modeled forage from different sourced-origins.

    Science.gov (United States)

    Ji, Cuiying; Zhang, Xuewei; Yu, Peiqiang

    2016-03-05

    The non-invasive molecular spectroscopic technique-FT/IR is capable to detect the molecular structure spectral features that are associated with biological, nutritional and biodegradation functions. However, to date, few researches have been conducted to use these non-invasive molecular spectroscopic techniques to study forage internal protein structures associated with biodegradation and biological functions. The objectives of this study were to detect unique aspects and association of protein Amide functional groups in terms of protein Amide I and II spectral profiles and chemical properties in the alfalfa forage (Medicago sativa L.) from different sourced-origins. In this study, alfalfa hay with two different origins was used as modeled forage for molecular structure and chemical property study. In each forage origin, five to seven sources were analyzed. The molecular spectral profiles were determined using FT/IR non-invasive molecular spectroscopy. The parameters of protein spectral profiles included functional groups of Amide I, Amide II and Amide I to II ratio. The results show that the modeled forage Amide I and Amide II were centered at 1653 cm(-1) and 1545 cm(-1), respectively. The Amide I spectral height and area intensities were from 0.02 to 0.03 and 2.67 to 3.36 AI, respectively. The Amide II spectral height and area intensities were from 0.01 to 0.02 and 0.71 to 0.93 AI, respectively. The Amide I to II spectral peak height and area ratios were from 1.86 to 1.88 and 3.68 to 3.79, respectively. Our results show that the non-invasive molecular spectroscopic techniques are capable to detect forage internal protein structure features which are associated with forage chemical properties.

  3. Using non-invasive molecular spectroscopic techniques to detect unique aspects of protein Amide functional groups and chemical properties of modeled forage from different sourced-origins

    Science.gov (United States)

    Ji, Cuiying; Zhang, Xuewei; Yu, Peiqiang

    2016-03-01

    The non-invasive molecular spectroscopic technique-FT/IR is capable to detect the molecular structure spectral features that are associated with biological, nutritional and biodegradation functions. However, to date, few researches have been conducted to use these non-invasive molecular spectroscopic techniques to study forage internal protein structures associated with biodegradation and biological functions. The objectives of this study were to detect unique aspects and association of protein Amide functional groups in terms of protein Amide I and II spectral profiles and chemical properties in the alfalfa forage (Medicago sativa L.) from different sourced-origins. In this study, alfalfa hay with two different origins was used as modeled forage for molecular structure and chemical property study. In each forage origin, five to seven sources were analyzed. The molecular spectral profiles were determined using FT/IR non-invasive molecular spectroscopy. The parameters of protein spectral profiles included functional groups of Amide I, Amide II and Amide I to II ratio. The results show that the modeled forage Amide I and Amide II were centered at 1653 cm- 1 and 1545 cm- 1, respectively. The Amide I spectral height and area intensities were from 0.02 to 0.03 and 2.67 to 3.36 AI, respectively. The Amide II spectral height and area intensities were from 0.01 to 0.02 and 0.71 to 0.93 AI, respectively. The Amide I to II spectral peak height and area ratios were from 1.86 to 1.88 and 3.68 to 3.79, respectively. Our results show that the non-invasive molecular spectroscopic techniques are capable to detect forage internal protein structure features which are associated with forage chemical properties.

  4. Structure-dependent optical and electrical transport properties of nanostructured Al-doped ZnO.

    Science.gov (United States)

    Gondoni, P; Ghidelli, M; Di Fonzo, F; Carminati, M; Russo, V; Li Bassi, A; Casari, C S

    2012-09-14

    The structure-property relation of nanostructured Al-doped ZnO thin films has been investigated in detail through a systematic variation of structure and morphology, with particular emphasis on how they affect optical and electrical properties. A variety of structures, ranging from compact polycrystalline films to mesoporous, hierarchically organized cluster assemblies, are grown by pulsed laser deposition at room temperature at different oxygen pressures. We investigate the dependence of functional properties on structure and morphology and show how the correlation between electrical and optical properties can be studied to evaluate energy gap, conduction band effective mass and transport mechanisms. Understanding these properties opens up opportunities for specific applications in photovoltaic devices, where optimized combinations of conductivity, transparency and light scattering are required.

  5. Nanostructured ZnO films: A study of molecular influence on transport properties by impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sappia, Luciano D.; Trujillo, Matias R. [Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET, Chacabuco 461, T4000ILI San Miguel de Tucumán (Argentina); Laboratorio de Medios e Interfases (LAMEIN), Departamento de Bioingeniería, Fac. de Cs. Exactas y Tecnología, Universidad Nacional de Tucumán, Av. Independencia 1800, 4000 San Miguel de Tucumán (Argentina); Lorite, Israel [Division of Superconductivity and Magnetism, Institute for Experimental Physics II, University of Leipzig, Linnéstrasse 5, 04103 Leipzig (Germany); Madrid, Rossana E., E-mail: rmadrid@herrera.unt.edu.ar [Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET, Chacabuco 461, T4000ILI San Miguel de Tucumán (Argentina); Laboratorio de Medios e Interfases (LAMEIN), Departamento de Bioingeniería, Fac. de Cs. Exactas y Tecnología, Universidad Nacional de Tucumán, Av. Independencia 1800, 4000 San Miguel de Tucumán (Argentina); Tirado, Monica [NanoProject and Laboratorio de Nanomateriales y Propiedades Dieléctricas, Departamento de Física, Universidad Nacional de Tucumán, Avenida Independencia 1800, Tucumán (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); and others

    2015-10-15

    Graphical abstract: - Highlights: • We study electrical transport in nanostructured ZnO films by impedance spectroscopy. • Bioaggregates on the surface produce strong changes in film transport properties. • This behavior is explained by modeling data with RC parallel circuits. • Electrical responses of ZnO films to aggregates are promising for biosensing. - Abstract: Nanomaterials based on ZnO have been used to build glucose sensors due to its high isoelectric point, which is important when a protein like Glucose Oxidase (GOx) is attached to a surface. It also creates a biologically friendly environment to preserve the activity of the enzyme. In this work we study the electrical transport properties of ZnO thin films (TFs) and single crystals (SC) in contact with different solutions by using impedance spectroscopy. We have found that the composition of the liquid, by means of the charge of the ions, produces strong changes in the transport properties of the TF. The enzyme GOx and phosphate buffer solutions have the major effect in the conduction through the films, which can be explained by the entrapment of carriers at the grain boundaries of the TFs. These results can help to design a new concept in glucose biosensing.

  6. Electronic transport properties of molecular junctions based on the direct binding of aromatic ring to electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Tran Nguyen, E-mail: lantran@ims.ac.jp

    2014-01-15

    Highlights: • Transport properties of molecular junction having direct binding of aromatic ring to electrode have been investigated. • The conductance of junction with sp-type electrode is higher than that of junction with sd-type electrode. • The rectifying mechanism critically depends on the nature of benzene–electrode coupling. • The p–n junction-like can be obtained even without heteroatom doping. • The negative differential resistance effect was observed for the case of sp-type electrode. - Abstract: We have used the non-equilibrium Green’s function in combination with the density functional theory to investigate the quantum transport properties of the molecular junctions including a terminated benzene ring directly coupled to surface of metal electrodes (physisorption). The other side of molecule was connected to electrode via thiolate bond (chemisorption). Two different electrodes have been studied, namely Cu and Al. Rectification and negative differential resistance behavior have been observed. We found that the electron transport mechanism is affected by the nature of benzene–electrode coupling. In other words, the transport mechanism depends on the nature of metallic electrode. Changing from sp- to sd-metallic electrode, the molecular junction changes from the Schottky to p–n junction-like diode. The transmission spectra, projected density of state, molecular projected self-consistent Hamiltonian, transmission eigenchannel, and Muliken population have been analyzed for explanation of electronic transport properties. Understanding the transport mechanism in junction having direct coupling of π-conjugate to electrode will be useful to design the future molecular devices.

  7. 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

  8. Electronic Transport Properties through Gold-Dithiol-Molecule-Gold Junctions in Equilibrium

    Institute of Scientific and Technical Information of China (English)

    NING Zhan-Yu; CHEN Jing-Zhe; HOU Shi-Min; ZHANG Jia-Xing; LIANG Zhen-Yu; ZHANG Jin; HAN Ru-Shan

    2005-01-01

    @@ We consider the electronic transport through gold-dithiol-molecule-gold junctions. We used an atomicallycontacted extended molecule model for the description of such systems. The calculations are based on the matrix Green function method combined with the hybrid tight-binding density functional theory. In order to determine the position of Fermi level, we referenced the experimental results from ultraviolet photoelectron spectroscopy.Our calculation of molecular conductance near the Fermi level qualitatively reproduces the experimental values measured previously [Science 301 (2003) 1221; J. Am. Chem. Soc. 125 (2003) 16164; Nano Lett. 4 (2004) 267].In addition, we discuss the relationship between different molecular electronic structures and transport properties.

  9. Magnetically Controlled Electronic Transport Properties of a Ferromagnetic Junction on the Surface of a Topological Insulator

    Science.gov (United States)

    Liu, Zheng-Qin; Wang, Rui-Qiang; Deng, Ming-Xun; Hu, Liang-Bin

    2015-06-01

    We have investigated the transport properties of the Dirac fermions through a ferromagnetic barrier junction on the surface of a strong topological insulator. The current-voltage characteristic curve and the tunneling conductance are calculated theoretically. Two interesting transport features are predicted: observable negative differential conductances and linear conductances tunable from unit to nearly zero. These features can be magnetically manipulated simply by changing the spacial orientation of the magnetization. Our results may contribute to the development of high-speed switching and functional applications or electrically controlled magnetization switching. Supported by National Natural Science Foundation of China under Grant Nos. 11174088, 11175067, 11274124

  10. Laser patterning: A new approach to measure local magneto-transport properties in multifilamentary superconducting tapes

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Valdes, C.F. [Superconductivity Laboratory, Magnetism Laboratory, IMRE-Physics Faculty, University of Havana, 10400 Havana (Cuba); Perez-Penichet, C. [Superconductivity Laboratory, Magnetism Laboratory, IMRE-Physics Faculty, University of Havana, 10400 Havana (Cuba); Noda, C. [Superconductivity Laboratory, Magnetism Laboratory, IMRE-Physics Faculty, University of Havana, 10400 Havana (Cuba); Arronte, M. [Laser Technology Laboratory, CICATA-IPN, ALTAMIRA, Altamira 89600, TAMPS (Mexico); Batista-Leyva, A.J. [Department of General Physics and Mathematics, InSTEC, 10400 Havana (Cuba); Haugen, O. [Department of Physics, University of Oslo, Blindern, N-0316 Oslo (Norway); Johansen, T.H. [Department of Physics, University of Oslo, Blindern, N-0316 Oslo (Norway); Han, Z. [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China); Altshuler, E. [Superconductivity Laboratory, Magnetism Laboratory, IMRE-Physics Faculty, University of Havana, 10400 Havana (Cuba)]. E-mail: ea@infomed.sld.cu

    2007-09-15

    The determination of inter- and intra-filament characteristics in superconducting composites such as BSCCO-Ag tapes is of great importance for material evaluation towards applications. Most attempts to separate the two contributions have relied on indirect methods based on magnetic measurements such as SQUID or magneto-optic imaging techniques. Here we show that laser patterning of superconducting BSCCO-Ag tapes constitutes a simple approach to measure local transport properties in a direct way, even able to separate inter- and intra-filament contributions to the overall transport behavior of the sample.

  11. Vibrational energy transport in molecules and the statistical properties of vibrational modes

    Science.gov (United States)

    Pandey, Hari Datt; Leitner, David M.

    2017-01-01

    Statistical properties of the eigenmodes computed for two molecules, dodecane and perfluorododecane, are examined and compared with predictions of random matrix theory. The eigenmode statistics of the heat carrying modes of perfluorododecane correspond to Porter-Thomas statistics, whereas those for dodecane do not. Vibrational energy transport in the two molecules is also computed and found to be diffusive in perfluorododecane but not in dodecane, consistent with recent experiments. The correspondence between eigenmode statistics and vibrational energy transport dynamics in molecules as well as thermalization in molecules are discussed.

  12. Synthesis and quantum transport properties of Bi₂Se₃ topological insulator nanostructures.

    Science.gov (United States)

    Yan, Yuan; Liao, Zhi-Min; Zhou, Yang-Bo; Wu, Han-Chun; Bie, Ya-Qing; Chen, Jing-Jing; Meng, Jie; Wu, Xiao-Song; Yu, Da-Peng

    2013-01-01

    Bi₂Se₃ nanocrystals with various morphologies, including nanotower, nanoplate, nanoflake, nanobeam and nanowire, have been synthesized. Well-distinguished Shubnikov-de Haas (SdH) oscillations were observed in Bi₂Se₃ nanoplates and nanobeams. Careful analysis of the SdH oscillations suggests the existence of Berry's phase π, which confirms the quantum transport of the surface Dirac fermions in both Bi₂Se₃ nanoplates and nanobeams without intended doping. The observation of the singular quantum transport of the topological surface states implies that the high-quality Bi₂Se₃ nanostructures have superiorities for investigating the novel physical properties and developing the potential applications.

  13. Poly(o-aminophenol) film electrodes synthesis, transport properties and practical applications

    CERN Document Server

    Tucceri, Ricardo

    2014-01-01

    This review book is concerned with the synthesis, charge transport properties and practical applications of poly (o-aminophenol) (POAP) film electrodes. It is divided into three parts. The first one has a particular emphasis on problems of synthesis and structure of POAP. The second part deals with the mechanism of charge transfer and charge transport processes occurring in the course of the redox reactions of POAP. The third part describes the promising applications of POAP in the different fields of sensors, electrocatalysis, bioelectrochemistry, corrosion protection, among others. This review covers the literature on POAP in the time period comprised between 1987 and 2013.

  14. Charge transport and memristive properties of graphene quantum dots embedded in poly(3-hexylthiophene) matrix

    Energy Technology Data Exchange (ETDEWEB)

    Cosmin Obreja, Alexandru; Cristea, Dana; Radoi, Antonio; Gavrila, Raluca; Comanescu, Florin; Kusko, Cristian, E-mail: cristian.kusko@imt.ro [National Institute for R and D in Microtechnologies, 72996, Bucharest (Romania); Mihalache, Iuliana [National Institute for R and D in Microtechnologies, 72996, Bucharest (Romania); Physics Department, University Bucharest, P.O. Box MG-11, 077125 Bucharest (Romania)

    2014-08-25

    We show that graphene quantum dots (GQD) embedded in a semiconducting poly(3-hexylthiophene) polymeric matrix act as charge trapping nanomaterials. In plane current-voltage (I-V) measurements of thin films realized from this nanocomposite deposited on gold interdigitated electrodes revealed that the GQD enhanced dramatically the hole transport. I-V characteristics exhibited a strong nonlinear behavior and a pinched hysteresis loop, a signature of a memristive response. The transport properties of this nanocomposite were explained in terms of a trap controlled space charge limited current mechanism.

  15. Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean

    Science.gov (United States)

    Denjean, C.; Cassola, F.; Mazzino, A.; Triquet, S.; Chevaillier, S.; Grand, N.; Bourrianne, T.; Momboisse, G.; Sellegri, K.; Schwarzenbock, A.; Freney, E.; Mallet, M.; Formenti, P.

    2016-02-01

    This study presents in situ aircraft measurements of Saharan mineral dust transported over the western Mediterranean basin in June-July 2013 during the ChArMEx/ADRIMED (the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) airborne campaign. Dust events differing in terms of source region (Algeria, Tunisia and Morocco), time of transport (1-5 days) and height of transport were sampled. Mineral dust were transported above the marine boundary layer, which conversely was dominated by pollution and marine aerosols. The dust vertical structure was extremely variable and characterized by either a single layer or a more complex and stratified structure with layers originating from different source regions. Mixing of mineral dust with pollution particles was observed depending on the height of transport of the dust layers. Dust layers carried a higher concentration of pollution particles below 3 km above sea level (a.s.l.) than above 3 km a.s.l., resulting in a scattering Ångström exponent up to 2.2 below 3 km a.s.l. However, the optical properties of the dust plumes remained practically unchanged with respect to values previously measured over source regions, regardless of the altitude. Moderate absorption of light by the dust plumes was observed with values of aerosol single scattering albedo at 530 nm ranging from 0.90 to 1.00. Concurrent calculations from the aerosol chemical composition revealed a negligible contribution of pollution particles to the absorption properties of the dust plumes that was due to a low contribution of refractory black carbon in regards to the fraction of dust and sulfate particles. This suggests that, even in the presence of moderate pollution, likely a persistent feature in the Mediterranean, the optical properties of the dust plumes could be assumed similar to those of native dust in radiative transfer simulations, modelling studies and satellite retrievals

  16. Quantum Size Effects in Transport Properties of Bi2Te3 Topological Insulator Thin Films

    Science.gov (United States)

    Rogacheva, E. I.; Budnik, A. V.; Nashchekina, O. N.; Meriuts, A. V.; Dresselhaus, M. S.

    2017-07-01

    Bi2Te3 compound and Bi2Te3-based solid solutions have attracted much attention as promising thermoelectric materials for refrigerating devices. The possibility of enhancing the thermoelectric efficiency in low-dimensional structures has stimulated studies of Bi2Te3 thin films. Now, interest in studying the transport properties of Bi2Te3 has grown sharply due to the observation of special properties characteristic of three-dimensional (3D) topological insulators in Bi2Te3. One of the possible manifestations of quantum size effects in two-dimensional structures is an oscillatory behavior of the dependences of transport properties on film thickness, d. The goal of this work is to summarize our earlier experimental results on the d-dependences of transport properties of Bi2Te3 thin films obtained by thermal evaporation in a vacuum on glass substrates, and to present our new results of theoretical calculations of the oscillations periods within the framework of the model of an infinitely deep potential well, which takes into account the dependence of the Fermi energy on d and the contribution of all energy subbands below the Fermi level to the conductivity. On the basis of the data obtained, some general regularities and specificity of the quantum size effects manifestation in 3D topological insulators are established.

  17. Calculation of thermodynamic and transport properties of thermal plasmas based on the Cantera software toolkit

    Science.gov (United States)

    Doiron, Charles; Hencken, Kai

    2013-09-01

    Computational fluid-dynamic simulations nowadays play a central role in the development of new gas circuit breakers. For these simulations to be reliable, a good knowledge of the pressure and temperature-dependence of the thermodynamic and transport properties of ionized gases is required. A key ingredient in the calculation of thermodynamic properties of thermal plasmas is the calculation of the chemical equilibrium composition of the gas. The general-purpose, open-source software toolkit Cantera provides most functionality required to carry out such thermodynamic calculations. In this contribution, we explain how we tailored Cantera specifically to calculate material properties of plasmas. The highly modular architecture of this framework made it possible to add support for Debye-Hückel non-ideality corrections in the calculation of the chemical equilibrium mixture, as well as to enable the calculation of the key transport parameters needed in CFD-based electric arc simulations: electrical and thermal conductivity, viscosity, and diffusion coefficients. As an example, we discuss the thermodynamic and transport properties of mixtures of carbon dioxide and copper vapor.

  18. Correlation of microstructure and thermo-mechanical properties of a novel hydrogen transport membrane

    Science.gov (United States)

    Zhang, Yongjun

    A key part of the FutureGen concept is to support the production of hydrogen to fuel a "hydrogen economy," with the use of clean burning hydrogen in power-producing fuel cells, as well as for use as a transportation fuel. One of the key technical barriers to FutureGen deployment is reliable and efficient hydrogen separation technology. Most Hydrogen Transport Membrane (HTM) research currently focuses on separation technology and hydrogen flux characterization. No significant work has been performed on thermo-mechanical properties of HTMs. The objective of the thesis is to understand the structure-property correlation of HTM and to characterize (1) thermo mechanical properties under different reducing environments and thermal cycles (thermal shock), and (2) evaluate the stability of the novel HTM material. A novel HTM cermet bulk sample was characterized for its physical and mechanical properties at both room temperature and at elevated temperature up to 1000°C. Micro-structural properties and residual stresses were evaluated in order to understand the changing mechanism of the microstructure and its effects on the mechanical properties of materials. A correlation of the microstructural and thermo mechanical properties of the HTM system was established for both HTM and the substrate material. Mechanical properties of both selected structural ceramics and the novel HTM cermet bulk sample are affected mainly by porosity and microstructural features, such as grain size and pore size-distribution. The Young's Modulus (E-value) is positively correlated to the flexural strength for materials with similar crystallographic structure. However, for different crystallographic materials, physical properties are independent of mechanical properties. Microstructural properties, particularly, grain size and crystallographic structure, and thermodynamic properties are the main factors affecting the mechanical properties at both room and high temperatures. The HTM cermet behaves

  19. Estimation of fluid flow and mass transport properties in a natural fracture using laboratory testing system on mass transport in fractured rock (LABROCK)

    Energy Technology Data Exchange (ETDEWEB)

    Yoshino, Naoto; Uchida, Masahiro [Japan Nuclear Cycle Development Inst., Tokai Works, Tokai, Ibaraki (Japan); Satou, Hisashi [Inspection Development Company Ltd., Tokai, Ibaraki (Japan)

    2003-03-01

    The understanding of mass transport and fluid flow properties in natural rock fractures is important for safety assessment of geological disposal of high level nuclear waste. The authors developed advanced tracer test equipment in which a 50-cm cubic scale rock sample was feasible. The mass transport and fluid flow properties in a single fracture were also examined. The relation among hydraulic, transport and mass balance apertures of a natural single fracture were obtained. Heterogeneity of the aperture distribution was evident, as was the possibility of some major flow line perpendicular to the flow direction. Additionally, the relation between normal stress and each aperture was also obtained by loading normal stress on the fracture. In future, measuring the aperture distribution and establishing the model considering fluid flow and mass transport properties in natural rock fractures will be conducted. (author)

  20. Impact of defects on the electrical transport, optical properties and failure mechanisms of GaN nanowires.

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Andrew M.; Aubry, Sylvie; Shaner, Eric Arthur; Siegal, Michael P.; Li, Qiming; Jones, Reese E.; Westover, Tyler; Wang, George T.; Zhou, Xiao Wang; Talin, Albert Alec; Bogart, Katherine Huderle Andersen; Harris, C. Thomas; Huang, Jian Yu

    2010-09-01

    We present the results of a three year LDRD project that focused on understanding the impact of defects on the electrical, optical and thermal properties of GaN-based nanowires (NWs). We describe the development and application of a host of experimental techniques to quantify and understand the physics of defects and thermal transport in GaN NWs. We also present the development of analytical models and computational studies of thermal conductivity in GaN NWs. Finally, we present an atomistic model for GaN NW electrical breakdown supported with experimental evidence. GaN-based nanowires are attractive for applications requiring compact, high-current density devices such as ultraviolet laser arrays. Understanding GaN nanowire failure at high-current density is crucial to developing nanowire (NW) devices. Nanowire device failure is likely more complex than thin film due to the prominence of surface effects and enhanced interaction among point defects. Understanding the impact of surfaces and point defects on nanowire thermal and electrical transport is the first step toward rational control and mitigation of device failure mechanisms. However, investigating defects in GaN NWs is extremely challenging because conventional defect spectroscopy techniques are unsuitable for wide-bandgap nanostructures. To understand NW breakdown, the influence of pre-existing and emergent defects during high current stress on NW properties will be investigated. Acute sensitivity of NW thermal conductivity to point-defect density is expected due to the lack of threading dislocation (TD) gettering sites, and enhanced phonon-surface scattering further inhibits thermal transport. Excess defect creation during Joule heating could further degrade thermal conductivity, producing a viscous cycle culminating in catastrophic breakdown. To investigate these issues, a unique combination of electron microscopy, scanning luminescence and photoconductivity implemented at the nanoscale will be used in

  1. Unique structural properties of 2,4,6-tri-tert-butylanilide: isomerization and switching between separable amide rotamers through the reaction of anilide enolates.

    Science.gov (United States)

    Tsukagoshi, Shiori; Ototake, Nobutaka; Ohnishi, Yusuke; Shimizu, Mayu; Kitagawa, Osamu

    2013-05-17

    Herein, we report a unique structural property of 2,4,6-tri-tert-butylanilide, which can be separated into its amide rotamers at room temperature. Interconversion between the rotamers of anilide enolates occurs readily at room temperature and their reaction with electrophiles gives mixtures of the rotamers in a ratio that depends on the reactivity of the corresponding electrophile. That is, the reaction of the 2,4,6-tri-tert-butylacetanilide enolate with reactive electrophiles, such as allyl bromide or protic acids, gives mixtures of the anilide rotamers in which the E rotamer is the major component, whereas less-reactive electrophiles, such as 1-bromopropane and 2-iodopropane, yield mixtures of the rotamers in which the Z rotamer is the major component. The rotameric ratio of the product is also strongly dependent on the reactivity of the anilide enolate. Switching between the anilide rotamers can be achieved through protonation of a less-reactive enolate by a less-reactive protic acid and thermal isomerization of the anilide.

  2. Interactive FORTRAN IV computer programs for the thermodynamic and transport properties of selected cryogens (fluids pack)

    Science.gov (United States)

    Mccarty, R. D.

    1980-01-01

    The thermodynamic and transport properties of selected cryogens had programmed into a series of computer routines. Input variables are any two of P, rho or T in the single phase regions and either P or T for the saturated liquid or vapor state. The output is pressure, density, temperature, entropy, enthalpy for all of the fluids and in most cases specific heat capacity and speed of sound. Viscosity and thermal conductivity are also given for most of the fluids. The programs are designed for access by remote terminal; however, they have been written in a modular form to allow the user to select either specific fluids or specific properties for particular needs. The program includes properties for hydrogen, helium, neon, nitrogen, oxygen, argon, and methane. The programs include properties for gaseous and liquid states usually from the triple point to some upper limit of pressure and temperature which varies from fluid to fluid.

  3. A Review of Hydrothermal Liquefaction Bio-Crude Properties and Prospects for Upgrading to Transportation Fuels

    Directory of Open Access Journals (Sweden)

    Jerome A. Ramirez

    2015-07-01

    Full Text Available Hydrothermal liquefaction (HTL presents a viable route for converting a vast range of materials into liquid fuel, without the need for pre-drying. Currently, HTL studies produce bio-crude with properties that fall short of diesel or biodiesel standards. Upgrading bio-crude improves the physical and chemical properties to produce a fuel corresponding to diesel or biodiesel. Properties such as viscosity, density, heating value, oxygen, nitrogen and sulphur content, and chemical composition can be modified towards meeting fuel standards using strategies such as solvent extraction, distillation, hydrodeoxygenation and catalytic cracking. This article presents a review of the upgrading technologies available, and how they might be used to make HTL bio-crude into a transportation fuel that meets current fuel property standards.

  4. The determination of ionic transport properties at high pressures in a diamond anvil cell

    Science.gov (United States)

    Wang, Qinglin; Liu, Cailong; Han, Yonghao; Gao, Chunxiao; Ma, Yanzhang

    2016-12-01

    A two-electrode configuration was adopted in an in situ impedance measurement system to determine the ionic conductivity at high pressures in a diamond anvil cell. In the experimental measurements, Mo thin-films were specifically coated on tops of the diamond anvils to serve as a pair of capacitance-like electrodes for impedance spectrum measurements. In the spectrum analysis, a Warburg impedance element was introduced into the equivalent circuit to reveal the ionic transport property among other physical properties of a material at high pressures. Using this method, we were able to determine the ionic transport character including the ionic conductivity and the diffusion coefficient of a sodium azide solid to 40 GPa.

  5. Modeling the transport properties of epitaxially grown thermoelectric oxide thin films using spectroscopic ellipsometry

    KAUST Repository

    Sarath Kumar, S. R.

    2012-02-01

    The influence of oxygen vacancies on the transport properties of epitaxial thermoelectric (Sr,La)TiO3 thin films is determined using electrical and spectroscopic ellipsometry (SE) measurements. Oxygen vacancy concentration was varied by ex-situ annealing in Ar and Ar/H2. All films exhibited degenerate semiconducting behavior, and electrical conductivity decreased (258–133 S cm−1) with increasing oxygen content. Similar decrease in the Seebeck coefficient is observed and attributed to a decrease in effective mass (7.8–3.2 me ), as determined by SE. Excellent agreement between transport properties deduced from SE and direct electrical measurements suggests that SE is an effective tool for studying oxide thin film thermoelectrics.

  6. Evaluation of collective transport properties of ionic melts from molecular dynamics simulations

    Indian Academy of Sciences (India)

    Manish Agarwal; Charusita Chakravarty

    2009-09-01

    Molecular dynamics simulations of beryllium fluoride (BeF2) have been carried out in the canonical (NVT) ensemble using a rigid-ion potential model. The Green-Kubo formalism has been applied to compute viscosities and ionic conductivities of BeF2 melt. The computational parameters critical for reliably estimating these collective transport properties are shown to differ significantly for viscosity and ionic conductivity. In addition to the equilibrium values of these transport properties, structural relaxation times as well as high-frequency IR-active modes are computed from the pressure and charge-flux auto correlation functions (ACFs) respectively. It is shown that a network-forming ionic melt, such as BeF2, will display persistent oscillatory behaviour of the integral of the charge-flux ACF. By suitable Fourier transformation, one can show that these persistent oscillations correspond to highfrequency, infra-red active vibrations associated with local modes of the network.

  7. Ab initio study of transport properties in defected carbon nanotubes: an O(N) approach

    Energy Technology Data Exchange (ETDEWEB)

    Biel, Blanca; GarcIa-Vidal, F J; Flores, Fernando [Departamento de Fisica Teorica de la Materia Condensada, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Rubio, Angel [European Theoretical Spectroscopy Facility (ETSF), Departamento de Fisica de Materiales, Universidad PaIs Vasco, Edificio Korta, Avenida Tolosa 72, 20018 San Sebastian (Spain)], E-mail: blanca.biel@cea.fr

    2008-07-23

    A combination of ab initio simulations and linear-scaling Green's functions techniques is used to analyze the transport properties of long (up to 1 {mu}m) carbon nanotubes with realistic disorder. The energetics and the influence of single defects (monovacancies and divacancies) on the electronic and transport properties of single-walled armchair carbon nanotubes are analyzed as a function of the tube diameter by means of the local orbital first-principles Fireball code. Efficient O(N) Green's functions techniques framed within the Landauer-Buettiker formalism allow a statistical study of the nanotube conductance averaged over a large sample of defected tubes and thus extraction of the nanotube localization length. The cases of zero and room temperature are both addressed.

  8. Crystallization and Transport Properties of Amorphous Cr-Si Thin Film Thermoelectrics

    Science.gov (United States)

    Novikov, S. V.; Burkov, A. T.; Schumann, J.

    2014-06-01

    We studied the thermoelectric properties, crystallization, and stability of amorphous and nanocrystalline states in Cr-Si composite films. Amorphous films, prepared by magnetron sputtering, were transformed into the nanocrystalline state by annealing with in situ thermopower and electrical resistivity measurements. We have found that the amorphous state is stable in these film composites to about 550 K. Prior to crystallization, the amorphous films undergo a structural relaxation, detected by peculiarities in the temperature dependences of the transport properties, but not visible in x-ray or electron diffraction. The magnitude and temperature dependences of electrical conductivity and thermopower indicate that electron transport in the amorphous films is through extended states. The amorphous films are crystallized at annealing temperatures above 550 K into a nanocrystalline composite with an average grain size of 10-20 nm.

  9. Crystal structure and electrical transport properties of single layered perovskite LaSrCoO4

    Science.gov (United States)

    Ahad, Abdul; Shukla, D. K.; Rahman, F.; Majid, S.; Tarachand; Okram, G. S.; Phase, D. M.

    2016-10-01

    We present here investigations on the influence of structure on electrical transport properties of polycrystalline LaSrCoO4 that is single layered perovskite with K2NiF4 type structure synthesized using solid state reaction route. Using Reitveld refinement of X-ray diffraction (XRD) data, it is found that the sample is in single phase with tetragonal structure (space group I4/mmm). Electrical resistivity performed in the temperature range 140-300K shows semiconducting character of the sample. Considerable contrasts in the Co-O bond length is associated with the intermediate spin (IS) state of Co ion that correlates the structural and transport properties. Detailed analysis indicates that the temperature dependent electrical resistivity follows the three-dimensional variable range hopping (VRH) model in low temperature region below 225K. The high temperature (225-300K) resistivity data has been found to follow the thermally activated behaviour.

  10. Theoretical study of electronic transport properties of a graphene-silicene bilayer

    Science.gov (United States)

    Berdiyorov, G. R.; Bahlouli, H.; Peeters, F. M.

    2015-06-01

    Electronic transport properties of a graphene-silicene bilayer system are studied using density-functional theory in combination with the nonequilibrium Green's function formalism. Depending on the energy of the electrons, the transmission can be larger in this system as compared to the sum of the transmissions of separated graphene and silicene monolayers. This effect is related to the increased electron density of states in the bilayer sample. At some energies, the electronic states become localized in one of the layers, resulting in the suppression of the electron transmission. The effect of an applied voltage on the transmission becomes more pronounced in the layered sample as compared to graphene due to the larger variation of the electrostatic potential profile. Our findings will be useful when creating hybrid nanoscale devices where enhanced transport properties will be desirable.

  11. On the statistical and transport properties of a non-dissipative Fermi-Ulam model

    Energy Technology Data Exchange (ETDEWEB)

    Livorati, André L. P. [Departamento de Física, UNESP - Univ. Estadual Paulista, Ave. 24A, 1515, Bela Vista, 13506-900 Rio Claro, SP (Brazil); Instituto de Física, IFUSP - Universidade de São Paulo, Rua do Matão, Tr.R 187, Cidade Universitária, 05314-970 São Paulo, SP (Brazil); School of Mathematics, University of Bristol, Bristol BS8 1TW (United Kingdom); Dettmann, Carl P. [School of Mathematics, University of Bristol, Bristol BS8 1TW (United Kingdom); Caldas, Iberê L. [Instituto de Física, IFUSP - Universidade de São Paulo, Rua do Matão, Tr.R 187, Cidade Universitária, 05314-970 São Paulo, SP (Brazil); Leonel, Edson D. [Departamento de Física, UNESP - Univ. Estadual Paulista, Ave. 24A, 1515, Bela Vista, 13506-900 Rio Claro, SP (Brazil); Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, 34151 Trieste (Italy)

    2015-10-15

    The transport and diffusion properties for the velocity of a Fermi-Ulam model were characterized using the decay rate of the survival probability. The system consists of an ensemble of non-interacting particles confined to move along and experience elastic collisions with two infinitely heavy walls. One is fixed, working as a returning mechanism of the colliding particles, while the other one moves periodically in time. The diffusion equation is solved, and the diffusion coefficient is numerically estimated by means of the averaged square velocity. Our results show remarkably good agreement of the theory and simulation for the chaotic sea below the first elliptic island in the phase space. From the decay rates of the survival probability, we obtained transport properties that can be extended to other nonlinear mappings, as well to billiard problems.

  12. Effective Heat and Mass Transport Properties of Anisotropic Porous Ceria for Solar Thermochemical Fuel Generation

    Directory of Open Access Journals (Sweden)

    Sophia Haussener

    2012-01-01

    Full Text Available High-resolution X-ray computed tomography is employed to obtain the exact 3D geometrical configuration of porous anisotropic ceria applied in solar-driven thermochemical cycles for splitting H2O and CO2. The tomography data are, in turn, used in direct pore-level numerical simulations for determining the morphological and effective heat/mass transport properties of porous ceria, namely: porosity, specific surface area, pore size distribution, extinction coefficient, thermal conductivity, convective heat transfer coefficient, permeability, Dupuit-Forchheimer coefficient, and tortuosity and residence time distributions. Tailored foam designs for enhanced transport properties are examined by means of adjusting morphologies of artificial ceria samples composed of bimodal distributed overlapping transparent spheres in an opaque medium.

  13. Effective Heat and Mass Transport Properties of Anisotropic Porous Ceria for Solar Thermochemical Fuel Generation.

    Science.gov (United States)

    Haussener, Sophia; Steinfeld, Aldo

    2012-01-19

    High-resolution X-ray computed tomography is employed to obtain the exact 3D geometrical configuration of porous anisotropic ceria applied in solar-driven thermochemical cycles for splitting H2O and CO2. The tomography data are, in turn, used in direct pore-level numerical simulations for determining the morphological and effective heat/mass transport properties of porous ceria, namely: porosity, specific surface area, pore size distribution, extinction coefficient, thermal conductivity, convective heat transfer coefficient, permeability, Dupuit-Forchheimer coefficient, and tortuosity and residence time distributions. Tailored foam designs for enhanced transport properties are examined by means of adjusting morphologies of artificial ceria samples composed of bimodal distributed overlapping transparent spheres in an opaque medium.

  14. The influence of inner hydrophobisation on water transport properties of modified lime plasters

    Science.gov (United States)

    Pavlíková, Milena; Pavlík, Zbyšek; Pernicová, Radka; Černý, Robert

    2016-06-01

    The effect of hydrophobic agent admixture on water vapour and liquid water transport properties of newly designed lime plasters is analysed in the paper. The major part of physico - chemical building deterioration is related to the penetration of moisture and soluble salts into the building structure. For that reason, the modified lime plasters were in the broad range of basic material properties tested. From the quantitative point of view, the measured results clearly demonstrate the big differences in the behaviour of studied materials depending on applied modifying admixtures. From the practical point of view, plaster made of lime hydrate, metakaolin, zinc stearate and air-entraining agent can be recommended for renovation purposes. The accessed material parameters will be used as input data for computational modelling of moisture transport in this type of porous building materials and will be stored in material database.

  15. Electronic structure and transport properties of the Heusler compound Co{sub 2}TiAl

    Energy Technology Data Exchange (ETDEWEB)

    Graf, Tanja; Fecher, Gerhard H; Barth, Joachim; Winterlik, Juergen; Felser, Claudia, E-mail: fecher@uni-mainz.d [Johannes Gutenberg Universitaet, Institut fuer Analytische und Anorganische Chemie, 55099 Mainz (Germany)

    2009-04-21

    The properties of the Heusler compound Co{sub 2}TiAl were investigated in detail by experimental techniques and theoretical methods. X-ray diffraction measurements indicate that as-cast samples of the compound exhibit the L2{sub 1} structure with a small amount of B2-type disorder. This leads to a reduced saturation magnetization per formula unit of 0.747 {mu}{sub B}. The Curie temperature is approximately 120 K. The transport properties are influenced by the change in the electronic structure at the Curie temperature, as revealed experimentally by conductivity, thermal transport and specific heat measurements. Different theoretical models based on ab initio calculations of the electronic structure are used to explain the experimental observations.

  16. Transport properties of boron-doped single-walled silicon carbide nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y.T. [Key laboratory of Ministry of Education for Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China); Ding, R.X., E-mail: rx_ding@163.co [Key laboratory of Ministry of Education for Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China); Song, J.X. [Key laboratory of Ministry of Education for Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China); School of Electronic Engineering, Xi' an Shiyou University, Xi' an 710075 (China)

    2011-01-15

    The doped boron (B) atom in silicon carbide nanotube (SiCNT) can substitute carbon or silicon atom, forming two different structures. The transport properties of both B-doped SiCNT structures are investigated by the method combined non-equilibrium Green's function with density functional theory (DFT). As the bias ranging from 0.8 to 1.0 V, the negative differential resistance (NDR) effect occurs, which is derived from the great difficulty for electrons tunneling from one electrode to another with the increasing of localization of molecular orbital. The high similar transport properties of both B-doped SiCNT indicate that boron is a suitable impurity for fabricating nano-scale SiCNT electronic devices.

  17. Magnetization and electric transport properties of single-crystal MgB2 nanowires.

    Science.gov (United States)

    Wu, Cen-Shawn; Chang, Yu-Cheng; Chen, Weimeng; Chen, Chinping; Feng, Qingrong

    2012-11-23

    High quality single-crystal magnesium diboride (MgB(2)) nanowires with lengths exceeding 10 μm were successfully synthesized by hybrid physical chemical vapor deposition. The magnetization and electrical transport properties of single-crystal MgB(2) nanowires (NWs) were measured. The superconducting transition temperature of the NWs was 37 K, as confirmed by magnetization measurements. The disordered behavior of the nanowires was observed by four-terminal current-voltage characteristic measurements of an individual NW from T = 10 to 300 K. The temperature-dependent resistivity curves for seven NWs collapsed into a universal curve described by the variable range hopping model, showing intrinsic nonmetallic transport properties. This implies that the granular superconducting defect states are critical to the superconductivity of the individual MgB(2) NWs.

  18. Thermal transport properties of thermally sprayed coatings: An integrated study of materials, processing and microstructural effects

    Science.gov (United States)

    Chi, Weiguang

    The complex microstructures of thermally sprayed coatings are very sensitive to processing conditions and have a significant influence on the properties. The thermal transport property is a very important design parameter for thermally sprayed coatings. Despite considerable progress in this area, there is continued need to clarify the interrelationships among processing, microstructure and thermal transport properties. This has been enabled through continued advancements in processing science and control, enhancements in microstructural characterization and new methods of property characterization. The purpose of this research is to seek a successive pathway to prior efforts in understanding the effect of microstructural defects on the thermal transport property of thermally sprayed coatings. Relationship between microstructure and thermal conductivity is investigated for three sets of plasma sprayed yttria stabilized zirconia (YSZ) coating systems made using different morphology powders, different particle size distribution and controlled modification of particle states via plasma torch parameters. By integrating the results, maps of the thermal conductivity-porosity relationship have been established. Such maps highlight the role of splat thickness and interfaces in thermal conductivity. Furthermore, a new microstructural parameter termed "effective porosity" is proposed which considers the dominating role of interlamellar pores on through thickness thermal transport in thermally sprayed coatings. This effective porosity is rationalized based on the heat transport mechanism and enables better understanding of microstructure-thermal transport property correlation. An inverse linear model and a percolation model are established which can serve as predictive tools for understanding microstructure-thermal conductivity relationships. In addition, a systematic assessment of thermal conductivity anisotropy has been carried out for YSZ, Al2O 3 and several metallic

  19. Theoretical study of electronic transport properties of a graphene-silicene bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Berdiyorov, G. R. [Qatar Environment and Energy Research Institute, Qatar Foundation, P.O. Box 5825, Doha (Qatar); Bahlouli, H. [Department of Physics, King Fahd University of Petroleum and Minerals, 31261 Dhahran (Saudi Arabia); Saudi Center for Theoretical Physics, 31261 Dhahran (Saudi Arabia); Peeters, F. M. [Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)

    2015-06-14

    Electronic transport properties of a graphene-silicene bilayer system are studied using density-functional theory in combination with the nonequilibrium Green's function formalism. Depending on the energy of the electrons, the transmission can be larger in this system as compared to the sum of the transmissions of separated graphene and silicene monolayers. This effect is related to the increased electron density of states in the bilayer sample. At some energies, the electronic states become localized in one of the layers, resulting in the suppression of the electron transmission. The effect of an applied voltage on the transmission becomes more pronounced in the layered sample as compared to graphene due to the larger variation of the electrostatic potential profile. Our findings will be useful when creating hybrid nanoscale devices where enhanced transport properties will be desirable.

  20. Transport Properties of Amine/Carbon Dioxide Reactive Mixtures and Implications to Carbon Capture Technologies.

    Science.gov (United States)

    Turgman-Cohen, Salomon; Giannelis, Emmanuel P; Escobedo, Fernando A

    2015-08-19

    The structure and transport properties of physisorbed and chemisorbed CO2 in model polyamine liquids (hexamethylenediamine and diethylenetriamine) are studied via molecular dynamics simulations. Such systems are relevant to CO2 absorption processes where nonaqueous amines are used as absorbents (e.g., when impregnated or grafted onto mesoporous media or misted in the gas phase). It is shown that accounting for the ionic speciation resulting from CO2 chemisorption enabled us to capture the qualitative changes in extent of absorption and fluidity with time that are observed in thermogravimetric experiments. Simulations reveal that high enough concentration of reacted CO2 leads to strong intermolecular ionic interactions and the arrest of molecular translations. The transport properties obtained from the simulations of the ionic speciated mixtures are also used to construct an approximate continuum-level model for the CO2 absorption process that mimics thermogravimetric experiments.

  1. Transport Properties in a One-Dimensional Chain with Randomly Side-Coupled Impurities

    Institute of Scientific and Technical Information of China (English)

    胡冬生; 张桂平; 熊诗杰

    2002-01-01

    We investigate the transport properties of a one-dimensional (1D) chain with randomly side-coupled impurities.By using the transfer matrix technique, we present numerical results of the transmission coefficient as a function of the electron energy. It is found that an extended state will be shown in such a random 1D system if the impurities are side-coupled to the chain with not only the nearest-neighbour bonds but also the next-nearest-neighbour bonds. We present an analytical expression for the energy of this extended state, which is determined by the strength of the nearest and next-nearest couplings between the impurities and the chain. The obtained results can be used to explain the transport properties of DNA chains and other quasi-lD organic structures.

  2. Electronic and transport properties of a molecular junction with asymmetric contacts

    Science.gov (United States)

    Tsai, M.-H.; Lu, T.-H.

    2010-02-01

    Asymmetric molecular junctions have been shown experimentally to exhibit a dual-conductance transport property with a pulse-like current-voltage characteristic, by Reed and co-workers. Using a recently developed first-principles integrated piecewise thermal equilibrium current calculation method and a gold-benzene-1-olate-4-thiolate-gold model molecular junction, this unusual transport property has been reproduced. Analysis of the electrostatics and the electronic structure reveals that the high-current state results from subtle bias induced charge transfer at the electrode-molecule contacts that raises molecular orbital energies and enhances the current-contributing molecular density of states and the probabilities of resonance tunneling of conduction electrons from one electrode to another.

  3. Volumetric and Transport Properties of Aqueous NaB(OH)4 Solutions

    Institute of Scientific and Technical Information of China (English)

    周永全; 房春晖; 房艳; 朱发岩

    2013-01-01

    Density, pH, viscosity, conductivity and the Raman spectra of aqueous NaB(OH)4 solutions precisely measured as functions of concentration at different temperatures (293.15, 298.15, 303.15, 313.15 and 323.15 K) are presented. Polyborate distributions in aqueous NaB(OH)4 solution were calculated, covering all the concentration range, 4B(OH)− is the most dominant species, other polyborate anions are less than 5.0%. The volumetric and the transport properties were discussed in detail, both of these properties indicate that 4B(OH)− behaves as a struc-ture-disordered anion.

  4. Effect of the molecular chain orientation on carrier transport and optical properties of polymer blends

    Science.gov (United States)

    Kažukauskas, V.; Čyras, V.; Pranaitis, M.; Apostoluk, A.; Rocha, L.; Sicot, L.; Raimond, P.; Sentein, C.

    2007-03-01

    We have investigated properties of poly(9-vinylcarbazole) (PVK) doped with 30% wt 4-dibutylamino-4'-nitrostilbene (DBANS), depending on the orientation of the polar DBANS molecules. Appearance of the orientation-induced built-in electrical field was proven optically by the Solid Electric Field Induced Second Harmonic Generation and electrically by Current-Voltage characterization. Modification of optical properties was evidenced by the spectral dependencies of absorption coefficient. The Thermally Stimulated Currents spectra demonstrated that carrier transport and trapping are affected, too. This paper has been presented at “ECHOS06”, Paris, 28 30 juin 2006.

  5. Strain Modulation of Electronic and Heat Transport Properties of Bilayer Boronitrene

    Science.gov (United States)

    Yang, Ming; Sun, Fang-Yuan; Wang, Rui-Ning; Zhang, Hang; Tang, Da-Wei

    2017-10-01

    Strain engineering has been proven as an effective approach to modify electronic and thermal properties of materials. Recently, strain effects on two-dimensional materials have become important relevant topics in this field. We performed density functional theory studies on the electronic and heat transport properties of bilayer boronitrene samples under an isotropic strain. We demonstrate that the strain will reduce the band gap width but keep the band gap type robust and direct. The strain will enhance the thermal conductivity of the system because of the increase in specific heat. The thermal conductivity was studied as a function of the phonon mean-free path.

  6. Transport properties of photonic topological insulators based on microring resonator array

    CERN Document Server

    Jiang, Xiaohui; Yin, Chenxuan; Zhang, Yanfeng; Chen, Hui; Yu, Siyuan

    2016-01-01

    An array of ring resonators specifically designed can perform as a topological insulator. We conduct simulations using both Tight-Binding Model (TBM) and Transfer Matrix Method (TMM) to analyze the transport properties of such optical structure, verifying the presence of robust topological edge states which is immune to disorder and defect. We have also made a comparison between these two methods, of which results suggesting that TBM is only applicable under weakly-coupling condition while TMM is more rigorous. Finally we compared the structure with common microring array and coupled resonator optical waveguide (CROW) to demonstrate that it has desired transmission properties with wide and flat spectral response.

  7. Structural, magnetic and transport properties of discontinuous granular multi-layers

    Energy Technology Data Exchange (ETDEWEB)

    Denardin, J.C. [Instituto de Fisica Gleb Wataghin (IFGW), Universidade Estadual de Campinas (UNICAMP), C.P. 6165, Campinas SP (Brazil); Knobel, M. [Instituto de Fisica Gleb Wataghin (IFGW), Universidade Estadual de Campinas (UNICAMP), C.P. 6165, Campinas SP (Brazil)]. E-mail: knobel@ifi.unicamp.br; Dorneles, L.S. [Departamento de Fisica, CCNE, UFSM 97105-900, Santa Maria RS (Brazil); Schelp, L.F. [Departamento de Fisica, CCNE, UFSM 97105-900, Santa Maria RS (Brazil)

    2005-07-15

    Results of structural, magnetic and transport properties of magnetic Co/SiO{sub 2} discontinuous multi-layers produced by sequential deposition are presented. Transmission electron microscopy (TEM) images show that the samples that are close to metal-insulation transition are composed by a connected network of metallic paths, and display an enhanced Hall Effect. The granular samples are composed by an almost periodic array of Co nanoparticles, and after annealing these samples show a clear evolution in the nanostructure, with increasing average Co grain sizes and decreasing size dispersion. Relationships between the nanostructure and magnetotransport properties are discussed and compared with previous results obtained in cosputtered films.

  8. Anisotropic surface hole-transport property of triphenylamine-derivative single crystal prepared by solution method

    Science.gov (United States)

    Umeda, Minoru; Katagiri, Mitsuhiko; Shironita, Sayoko; Nagayama, Norio

    2016-12-01

    This paper reports the anisotropic hole transport at the triphenylamine-derivative single crystal surface prepared by a solution method. Triphenylamine derivatives are commonly used in a hole-transport material for organic photoconductors of laser-beam printers, in which the materials are used as an amorphous form. For developing organic photovoltaics using the photoconductor's technology, preparation of a single crystal seems to be a specific way by realizing the high mobility of an organic semiconductor. In this study, a single crystal of 4-(2,2-diphenylethenyl)-N,N-bis(4-methylphenyl)-benzenamine (TPA) was prepared and its anisotropic hole-transport property measured. First, the hole-transport property of the TPA was investigated based on its chemical structure and electrochemical redox characteristics. Next, a large-scale single crystal formation at a high rate was developed by employing a solution method based on its solubility and supersolubility curves. The grown TPA was found to be a single crystal based on the polarization micrograph observation and crystallographic analysis. For the TPA single crystal, an anisotropic surface conduction was found, which was well explained by its molecular stack structure. The measured current in the long-axis direction is one order of magnitude greater than that of amorphous TPA.

  9. Effect of Yield Power Law Fluid Rheological Properties on Cuttings Transport in Eccentric Horizontal Narrow Annulus

    Directory of Open Access Journals (Sweden)

    Titus Ntow Ofei

    2016-01-01

    Full Text Available Narrow annular drilling such as casing-while-drilling technique is gaining popularity due to its ability to mitigate nonproductive time during oil and gas drilling operations. However, very little is known about the flow dynamics in narrow annular drilling. In this study, the Eulerian-Eulerian two-fluid model was used to examine the influence of Yield Power Law fluid rheological properties on cuttings transport in eccentric horizontal narrow annulus. The flow was assumed as fully developed, laminar, and transient state. The present simulation model was validated against experimental data, where a mean percent error of −1.2% was recorded. Results revealed an increase in the radial distribution of cuttings transport velocity in the wide annular region as the consistency index, K, and the flow behavior index, n, increase. Nonetheless, increasing the yield stress, τo, had insignificant effect on the cuttings transport velocity. Three-dimensional profiles showed how cuttings preferred to travel in less resistant flow area, whereas cuttings concentration builds up in the narrow annular region. Furthermore, annular frictional pressure losses also increased as K, n, and τo increased. This study serves as a guide to properly optimize drilling fluid rheological properties for efficient cuttings transport and equivalent circulating density (ECD management in narrow annular drilling.

  10. The Influence of Calcium Chloride Salt Solution on the Transport Properties of Cementitious Materials

    Directory of Open Access Journals (Sweden)

    Yaghoob Farnam

    2015-01-01

    Full Text Available The chemical interaction between calcium chloride (CaCl2 and cementitious binder may alter the transport properties of concrete which are important in predicting the service life of infrastructure elements. This paper presents a series of fluid and gas transport measurements made on cementitious mortars before and after exposure to various solutions with concentrations ranging from 0% to 29.8% CaCl2 by mass. Fluid absorption, oxygen diffusivity, and oxygen permeability were measured on mortar samples prepared using Type I and Type V cements. Three primary factors influence the transport properties of mortar exposed to CaCl2: (1 changes in the degree of saturation, (2 calcium hydroxide leaching, and (3 formation of chemical reaction products (i.e., Friedel’s salt, Kuzel’s salt, and calcium oxychloride. It is shown that an increase in the degree of saturation decreases oxygen permeability. At lower concentrations (~12%, the formation of chemical reaction products (mainly calcium oxychloride is a dominant factor decreasing the fluid and gas transport in concrete.

  11. Modeling the Thermodynamic and Transport Properties of Decahydronaphthalene/Propane Mixtures: Phase Equilibria, Density, and Viscosity

    Science.gov (United States)

    2011-01-01

    Modeling the Thermodynamic and Transport Properties of Decahydronaphthalene/Propane Mixtures: Phase Equilibria , Density, and Viscosity Nathaniel...Decahydronaphthalene/Propane Mixtures: Phase Equilibria , Density, And Viscosity 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Keywords: phase equilibria ; modified Sanchez-Lacombe equation of state

  12. Size distribution and optical properties of African mineral dust after intercontinental transport

    Science.gov (United States)

    Denjean, Cyrielle; Formenti, Paola; Desboeufs, Karine; Chevaillier, Servanne; Triquet, Sylvain; Maillé, Michel; Cazaunau, Mathieu; Laurent, Benoit; Mayol-Bracero, Olga L.; Vallejo, Pamela; Quiñones, Mariana; Gutierrez-Molina, Ian E.; Cassola, Federico; Prati, Paolo; Andrews, Elisabeth; Ogren, John

    2016-06-01

    The transatlantic transport of mineral dust from Africa is a persistent atmospheric phenomenon, clue for understanding the impacts of dust at the global scale. As part of the DUST Aging and Transport from Africa to the Caribbean (Dust-ATTACk) intensive field campaign, the size distribution and optical properties of mineral dust were measured in June-July 2012 on the east coast of Puerto Rico, more than 5000 km from the west coast of Africa. During the recorded dust events, the PM10 (particulate matter 10 micrometers or less in diameter) concentrations increased from 20 to 70 µg m-3. Remote sensing observations and modeling analysis were used to identify the main source regions, which were found in the Western Sahara, Mauritania, Algeria, Niger, and Mali. The microphysical and optical properties of the dust plumes were almost independent of origin. The size distribution of mineral dust after long-range transport may have modal diameters similar to those on the eastern side of the Atlantic short time after emission, possibly depending on height of transport. Additional submicron particles of anthropogenic absorbing aerosols (likely from regional marine traffic activities) can be mixed within the dust plumes, without affecting in a significant way the PM10 absorption properties of dust observed in Puerto Rico. The Dust-ATTACk experimental data set may be useful for modeling the direct radiative effect of dust. For accurate representation of dust optical properties over the Atlantic remote marine region, we recommend mass extinction efficiency (MEE) and single-scattering albedo values in the range 1.1-1.5 m2 g-1 and 0.97-0.98, respectively, for visible wavelengths.

  13. Transport Properties of Aqueous Glycerol and Aqueous Mannitol through the Zirconium Oxide Membrane

    Science.gov (United States)

    Blokhra; Sharma; Blokhra

    1997-08-15

    The transport properties of aqueous glycerol and aqueous mannitol across a zirconium oxide membrane are, investigated from the point of view of irreversible thermodynamics. The data on hydrodynamic permeability are analyzed in terms of frictional coefficients and entropy of activation. The phenomenological coefficient characterizing the electroosmotic flow and the membrane characteristics are also estimated for the various solutions with the object of determining the efficiencies of electrokinetic energy conversion and zeta potential. Copyright 1997Academic Press

  14. Influence of Microstructure and Sintering Routes on Transport Properties of Apatite Materials for Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    A.Chesnaud; C.Estournes; G.Dezannau

    2007-01-01

    1 Results Oxy-apatite materials are thought as zirconia-substitutes in Solid Oxide Fuel Cells due to their fast ionic conduction. However, the well known difficulties related to their densification prevent them from being used as such. This study presents strategies to obtain oxy-apatite dense materials and the influence of elaboration route on transport properties. Particular emphasis is put on the microstructure effect on ion conduction. By the combined use of freeze-drying and conventional or spark p...

  15. Electronic properties of mesoscopic graphene structures: Charge confinement and control of spin and charge transport

    Energy Technology Data Exchange (ETDEWEB)

    Rozhkov, A.V., E-mail: arozhkov@gmail.co [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences, 125412, Moscow (Russian Federation); Giavaras, G. [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Bliokh, Yury P. [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Department of Physics, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Freilikher, Valentin [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Department of Physics, Bar-Ilan University, Ramat-Gan 52900 (Israel); Nori, Franco [Advanced Science Institute, RIKEN, Wako-shi, Saitama, 351-0198 (Japan); Department of Physics, University of Michigan, Ann Arbor, MI 48109-1040 (United States)

    2011-06-15

    This brief review discusses electronic properties of mesoscopic graphene-based structures. These allow controlling the confinement and transport of charge and spin; thus, they are of interest not only for fundamental research, but also for applications. The graphene-related topics covered here are: edges, nanoribbons, quantum dots, pn-junctions, pnp-structures, and quantum barriers and waveguides. This review is partly intended as a short introduction to graphene mesoscopics.

  16. Mass transport properties of Pu/DT mixtures from orbital free molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Kress, Joel David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ticknor, Christopher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Collins, Lee A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-09-16

    Mass transport properties (shear viscosity and diffusion coefficients) for Pu/DT mixtures were calculated with Orbital Free Molecular Dynamics (OFMD). The results were fitted to simple functions of mass density (for ρ=10.4 to 62.4 g/cm3) and temperature (for T=100 up to 3,000 eV) for Pu/DT mixtures consisting of 100/0, 25/75, 50/50, and 75/25 by number.

  17. A computational study of the quantum transport properties of a Cu-CNT composite.

    Science.gov (United States)

    Ghorbani-Asl, Mahdi; Bristowe, Paul D; Koziol, Krzysztof

    2015-07-28

    The quantum transport properties of a Cu-CNT composite are studied using a non-equilibrium Green's function approach combined with the self-consistent-charge density-functional tight-binding method. The results show that the electrical conductance of the composite depends strongly on CNT density and alignment but more weakly on chirality. Alignment with the applied bias is preferred and the conductance of the composite increases as its mass density increases.

  18. Impact of lux gene insertion on bacterial surface properties and transport.

    Science.gov (United States)

    Chen, Gang; Srinivasa Ranga, Vijay Penagonda; Mao, Yongjun; Chen, Kevin; Qiao, Hanzi

    2008-03-01

    Genetic markers have been in popular use for tracing microbial movement in the environment. However, the impact of genetic marker insertion on microbial surface properties and consequent transport is often ignored. For this research, we investigated the impact of luminescence-based genetic marker insertion on bacterial surface properties and transport. Typical Gram-positive bacterial strains of Lactobacillus casei, Streptococcus mitis and Micrococcus luteus were used as model bacterial strains in this research. We manipulated gene transfer to observe the impact of lux gene insertion on bacterial surface properties based on contact angle measurements, and we conducted column experiments to evaluate the impact of lux gene insertion on bacterial transport. After lux gene insertion, bacterial interactions with the porous media increased, demonstrating stronger deposition potential in the porous media. Accordingly, retention of the daughter strains increased. Lux gene insertion also resulted in an increase in bacterial dispersion and equilibrium adsorption in the porous media. The bacterial deposition coefficient was found to correlate with the free energy of interactions between bacteria and the porous media.

  19. Predictive model of transport properties of fuel cell membrane : from microscopic to macroscopic level

    Energy Technology Data Exchange (ETDEWEB)

    Colinart, T.; Lottin, O.; Maranzana, G.; Didierjean, S.; Moyne, C. [Nancy-Univ., Vandoeuvre-les-Nancy (France). Laboratoire d' Energetique et de Mecanique Theorique et Appliquee

    2007-07-01

    Because of their attractiveness as efficient and clean energy producers, proton exchange membrane fuel cells (PEMFC) can be used in automotive and small stationary applications. The electrochemical reaction takes place on two electrodes separated by a ionomer membrane. An important component of fuel cell water management and a problem for fuel cell performances involves the transport of protons from the anode to the cathode as its' transport properties are highly water dependent. Nafion membranes are widely used as an electrolyte for PEMFC. This paper presented a model to predict transport properties of polymer membranes such as Nafion used as electrolytes in a low temperature fuel cell. The paper discussed the electrical double layer that was used to determine surface charge density. The paper then discussed the analytical solution to the physical problem in the diffuse part of a cylindrical pore which involved solving the Poisson-Boltzmann, the Navier-Stokes and the Nernst-Planck equations. The properties of the electrolytic solution were equal to those of water and they were considered to be constant within the pore. A literature comparison with other models was also presented. It was concluded that in order to supplement the model, it is necessary to investigate the mechanics of the membrane, particularly the swelling behaviour, and the adsorption phenomena of the ions in the stern layer. 15 refs., 1 tab., 3 figs.

  20. Transport properties of the topological Kondo insulator SmB6 under the irradiation of light

    Science.gov (United States)

    Zhu, Guo-Bao; Yang, Hui-Min

    2016-10-01

    In this paper, we study transport properties of the X point in the Brillouin zone of the topological Kondo insulator SmB6 under the application of a circularly polarized light. The transport properties at high-frequency regime and low-frequency regime as a function of the ratio (κ) of the Dresselhaus-like and Rashba-like spin-orbit parameter are studied based on the Floquet theory and Boltzmann equation respectively. The sign of Hall conductivity at high-frequency regime can be reversed by the ratio κ and the amplitude of the light. The amplitude of the current can be enhanced by the ratio κ. Our findings provide a way to control the transport properties of the Dirac materials at low-frequency regime. Project supported by the National Natural Science Foundation of China (Grant Nos. 11504095 and 11447145), the Foundation of Heze University (Grant Nos. XY14B002 and XYPY01), and the Project funded by the Higher Educational Science and Technology Program of Shandong Province, China (Grant No. J15LJ55).

  1. Formulating gels for decreased mucociliary transport using rheologic properties: polyacrylic acids.

    Science.gov (United States)

    Shah, Ankur J; Donovan, Maureen D

    2007-04-20

    The purpose of these studies was to identify the rheologic properties of polyacrylic acid gels necessary for optimal reductions in mucociliary clearance. The mucociliary transport of 2 bioadhesive polyacrylic acid polymers, polycarbophil and carbopol, was assessed in vitro by measuring their clearance rates across explants of ciliated bovine tracheal tissue. The viscoelastic properties of polymer gels were measured in the presence of mucus using controlled stress rheometry. Combinations of apparent viscosity (eta) and complex modulus (G*) were found to be the most useful parameters in the identification of polyacrylic acid formulations capable of decreasing mucociliary transport rate (MTR). A narrow range of eta and G* values suitable for reducing mucociliary clearance, while remaining sufficiently fluid for intranasal administration, were identified. The correlations between the rheologic parameters of the polycarbophil gels and their mucociliary transport rates were used to identify other polyacrylic acid gels that also had suitable mucociliary clearance properties, demonstrating that these parameters can be used to direct the optimization of formulations using simple in vitro rheologic testing.

  2. Calculation of effective transport properties of partially saturated gas diffusion layers

    Science.gov (United States)

    Bednarek, Tomasz; Tsotridis, Georgios

    2017-02-01

    A large number of currently available Computational Fluid Dynamics numerical models of Polymer Electrolyte Membrane Fuel Cells (PEMFC) are based on the assumption that porous structures are mainly considered as thin and homogenous layers, hence the mass transport equations in structures such as Gas Diffusion Layers (GDL) are usually modelled according to the Darcy assumptions. Application of homogenous models implies that the effects of porous structures are taken into consideration via the effective transport properties of porosity, tortuosity, permeability (or flow resistance), diffusivity, electric and thermal conductivity. Therefore, reliable values of those effective properties of GDL play a significant role for PEMFC modelling when employing Computational Fluid Dynamics, since these parameters are required as input values for performing the numerical calculations. The objective of the current study is to calculate the effective transport properties of GDL, namely gas permeability, diffusivity and thermal conductivity, as a function of liquid water saturation by using the Lattice-Boltzmann approach. The study proposes a method of uniform water impregnation of the GDL based on the "Fine-Mist" assumption by taking into account the surface tension of water droplets and the actual shape of GDL pores.

  3. Comparison of transport properties models for numerical simulations of Mars entry vehicles

    Science.gov (United States)

    Hao, Jiaao; Wang, Jingying; Gao, Zhenxun; Jiang, Chongwen; Lee, Chunhian

    2017-01-01

    Effects of two different models for transport properties, including the approximate model and the collision integral model, on hypersonic flow simulations of Mars entry vehicles are numerically investigated. A least square fitting is firstly performed using the best-available data of collision integrals for Martian atmosphere species within the temperature range of 300-20,000 K. Then, the performance of these two transport properties models are compared for an equilibrium Martian atmosphere gas mixture at 10 kPa and temperatures ranging from 1000 to 10,000 K. Finally, four flight conditions chosen from the trajectory of the Mars Pathfinder entry vehicle are numerically simulated. It is indicated that the approximate model is capable of accurately providing the distributions of species mass fractions and temperatures in the flowfield. Both models give similar translational-rotational and vibrational heat fluxes. However, the chemical diffusion heat fluxes predicted by the approximate model are significantly larger than the results computed by the collision integral model, particularly in the vicinity of the forebody stagnation point, whose maximum relative error of 15% for the super-catalytic case. The diffusion model employed in the approximate model is responsible to the discrepancy. In addition, the wake structure is largely unaffected by the transport properties models.

  4. Dispersion stability and electrokinetic properties of intrinsic plutonium colloids: implications for subsurface transport.

    Science.gov (United States)

    Abdel-Fattah, Amr I; Zhou, Dongxu; Boukhalfa, Hakim; Tarimala, Sowmitri; Ware, S Doug; Keller, Arturo A

    2013-06-04

    Subsurface transport of plutonium (Pu) may be facilitated by the formation of intrinsic Pu colloids. While this colloid-facilitated transport is largely governed by the electrokinetic properties and dispersion stability (resistance to aggregation) of the colloids, reported experimental data is scarce. Here, we quantify the dependence of ζ-potential of intrinsic Pu(IV) colloids on pH and their aggregation rate on ionic strength. Results indicate an isoelectric point of pH 8.6 and a critical coagulation concentration of 0.1 M of 1:1 electrolyte at pH 11.4. The ζ-potential/pH dependence of the Pu(IV) colloids is similar to that of goethite and hematite colloids. Colloid interaction energy calculations using these values reveal an effective Hamaker constant of the intrinsic Pu(IV) colloids in water of 1.85 × 10(-19) J, corresponding to a relative permittivity of 6.21 and refractive index of 2.33, in agreement with first principles calculations. This relatively high Hamaker constant combined with the positive charge of Pu(IV) colloids under typical groundwater aquifer conditions led to two contradicting hypotheses: (a) the Pu(IV) colloids will exhibit significant aggregation and deposition, leading to a negligible subsurface transport or (b) the Pu(IV) colloids will associate with the relatively stable native groundwater colloids, leading to a considerable subsurface transport. Packed column transport experiments supported the second hypothesis.

  5. 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.

  6. Unique gating properties of C. elegans ClC anion channel splice variants are determined by altered CBS domain conformation and the R-helix linker.

    Science.gov (United States)

    Dave, Sonya; Sheehan, Jonathan H; Meiler, Jens; Strange, Kevin

    2010-01-01

    All eukaryotic and some prokaryotic ClC anion transport proteins have extensive cytoplasmic C-termini containing two cystathionine-β-synthase (CBS) domains. CBS domain secondary structure is highly conserved and consists of two α-helices and three β-strands arranged as β1-α1-β2-β3-α2. ClC CBS domain mutations cause muscle and bone disease and alter ClC gating. However, the precise functional roles of CBS domains and the structural bases by which they regulate ClC function are poorly understood. CLH-3a and CLH-3b are C. elegans ClC anion channel splice variants with strikingly different biophysical properties. Splice variation occurs at cytoplasmic N- and C-termini and includes several amino acids that form α2 of the second CBS domain (CBS2). We demonstrate that interchanging α2 between CLH-3a and CLH-3b interchanges their gating properties. The "R-helix" of ClC proteins forms part of the ion-conducting pore and selectivity filter and is connected to the cytoplasmic C-terminus via a short stretch of cytoplasmic amino acids termed the "R-helix linker". C-terminus conformation changes could cause R-helix structural rearrangements via this linker. X-ray structures of three ClC protein cytoplasmic C-termini suggest that α2 of CBS2 and the R-helix linker could be closely apposed and may therefore interact. We found that mutating apposing amino acids in α2 and the R-helix linker of CLH-3b was sufficient to give rise to CLH-3a-like gating. We postulate that the R-helix linker interacts with CBS2 α2, and that this putative interaction provides a pathway by which cytoplasmic C-terminus conformational changes induce conformational changes in membrane domains that in turn modulate ClC function.

  7. REPRESENTING AEROSOL DYNAMICS AND PROPERTIES IN CHEMICAL TRANSPORT MODELS BY THE METHOD OF MOMENTS.

    Energy Technology Data Exchange (ETDEWEB)

    SCHWARTZ, S.E.; MCGRAW, R.; BENKOVITZ, C.M.; WRIGHT, D.L.

    2001-04-01

    Atmospheric aerosols, suspensions of solid or liquid particles, are an important multi-phase system. Aerosols scatter and absorb shortwave (solar) radiation, affecting climate (Charlson et al., 1992; Schwartz, 1996) and visibility; nucleate cloud droplet formation, modifying the reflectivity of clouds (Twomey et al., 1984; Schwartz and Slingo, 1996) as well as contributing to composition of cloudwater and to wet deposition (Seinfeld and Pandis, 1998); and affect human health through inhalation (NRC, 1998). Existing and prospective air quality regulations impose standards on concentrations of atmospheric aerosols to protect human health and welfare (EPA, 1998). Chemical transport and transformation models representing the loading and geographical distribution of aerosols and precursor gases are needed to permit development of effective and efficient strategies for meeting air quality standards, and for examining aerosol effects on climate retrospectively and prospectively for different emissions scenarios. Important aerosol properties and processes depend on their size distribution: light scattering, cloud nucleating properties, dry deposition, and penetration into airways of lungs. The evolution of the mass loading itself depends on particle size because of the size dependence of growth and removal processes. For these reasons it is increasingly recognized that chemical transport and transformation models must represent not just the mass loading of atmospheric particulate matter but also the aerosol microphysical properties and the evolution of these properties if aerosols are to be accurately represented in these models. If the size distribution of the aerosol is known, a given property can be evaluated as the integral of the appropriate kernel function over the size distribution. This has motivated the approach of determining aerosol size distribution, and of explicitly representing this distribution and its evolution in chemical transport models.

  8. Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean

    Directory of Open Access Journals (Sweden)

    C. Denjean

    2015-08-01

    Full Text Available This study presents in situ aircraft measurements of Saharan mineral dust transported over the western Mediterranean basin in June–July 2013 during the ChArMEx/ADRIMED (the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region airborne campaign. Dust events differing in terms of source region (Algeria, Tunisia and Morocco, time of tranport (1–5 days and height of transport were sampled. Mineral dust were transported above the marine boundary layer, which conversely was dominated by pollution and marine aerosols. The dust vertical structure was extremely variable and characterized by either a single layer or a more complex and stratified structure with layers originating from different source regions. Mixing of mineral dust with pollution particles was observed depending on the height of transport of the dust layers. Dust layers carried higher concentration of pollution particles at intermediate altitude (1–3 km than at elevated altitude (> 3 km, resulting in scattering Angstrom exponent up to 2.2 within the intermediate altitude. However, the optical properties of the dust plumes remained practically unchanged with respect to values previously measured over source regions, regardless of the altitude. Moderate light absorption of the dust plumes was observed with values of aerosol single scattering albedo at 530 nm ranging from 0.90 to 1.00 ± 0.04. Concurrent calculations from the aerosol chemical composition revealed a negligible contribution of pollution particles to the absorption properties of the dust plumes that was due to a low contribution of refractory black carbon in regards to the fraction of dust and sulfate particles. This suggests that, even in the presence of moderate pollution, likely a persistent feature in the Mediterranean, the optical properties of the dust plumes could be assimilated to those of native dust in radiative transfer simulations

  9. Representative equations for the thermodynamic and transport properties of fluids near the gas-liquid critical point

    Science.gov (United States)

    Sengers, J. V.; Basu, R. S.; Sengers, J. M. H. L.

    1981-01-01

    A survey is presented of representative equations for various thermophysical properties of fluids in the critical region. Representative equations for the transport properties are included. Semi-empirical modifications of the theoretically predicted asymtotic critical behavior that yield simple and practical representations of the fluid properties in the critical region are emphasized.

  10. The effects of surface functionalization on rheology, structure and transport properties of nanocomposites

    Science.gov (United States)

    Ranka, Moulik A.

    In this thesis, the effects of surface functionalization using hydrophobic silanes on properties of nanocomposites comprising 42 nm silica particles suspended in a melt of polyethylene-glycol (PEG) are studied using rheological, static and dynamic x-ray scattering studies. The nanocomposites are studied in the low molecular weight unentangled (PEG-400) and high molecular weight entangled (PEG-20000) regimes. We find no differences in the properties of the bare and silanized particles in the low volume fraction regime up to where the interparticle separation distance h > 6Rg. In the region of 6Rg > h > 3Rg (5Rg > h > 3Rg, in case of entangled melts), we find substantial differences in the rheological, structure and transport properties when comparing the bare and silanized particles. In the unentangled melts, we observe up to four orders of magnitude drop in the viscosity of the composites at the highest levels of silanization and observe shear thinning behavior that is unlike what is universally seen for hard spheres. For the entangled melts, a yield stress is observed for the silanized particles that is absent in the case of the bare particles and there is a divergence in the elastic modulus in comparison to bare particles. We observe an anomalous speed up in the density relaxations and an associated maxima in structure properties in the case of unentangled melts which has been reported previously for particles experiencing soft repulsive potentials. A clear reentrant behavior in structure and transport properties is observed for bare particles in the entangled melts that have been previously reported for particles interacting with soft repulsive potentials such as square shoulder and ramp potentials. In the silanized systems, the density relaxation times although lower than bare particles, is ii unaffected by increasing volume fraction up to h ~ 3Rg and is decoupled from the structure properties which are non-monotonic similar to bare particles. In the region of

  11. Constitutive Relations for Reactive Transport Modeling: Effects of Chemical Reactions on Multi-Phase Flow Properties

    Science.gov (United States)

    Zhang, S.; Liu, H. H.; van Dijke, M. I.; Geiger, S.; Agar, S. M.

    2016-12-01

    The relationship between flow properties and chemical reactions is key to modeling subsurface reactive transport. This study develops closed-form equations to describe the effects of mineral precipitation and dissolution on multiphase flow properties (capillary pressure and relative permeabilities) of porous media. The model accounts for the fact that precipitation/dissolution only takes place in the water-filled part of pore space. The capillary tube concept was used to connect pore-scale changes to macroscopic hydraulic properties. Precipitation/dissolution induces changes in the pore radii of water-filled pores and consequently in the pore-size distribution. The updated pore-size distribution is converted back to a new capillary pressure-water saturation relation from which the new relative permeabilities are calculated. Pore network modeling is conducted on a Berea sandstone to validate the new continuum-scale relations. The pore network modeling results are satisfactorily predicted by the new closed-form equations. Currently the effects of chemical reactions on flow properties are represented as a relation between permeability and porosity in reactive transport modeling. Porosity is updated after chemical calculations from the change of mineral volumes, then permeability change is calculated from the porosity change using an empirical permeability-porosity relation, most commonly the Carman-Kozeny relation, or the Verma-Pruess relation. To the best of our knowledge, there are no closed-form relations available yet for the effects of chemical reactions on multi-phase flow properties, and thus currently these effects cannot be accounted for in reactive transport modeling. This work presents new constitutive relations to represent how chemical reactions affect multi-phase flow properties on the continuum scale based on the conceptual model of parallel capillary tubes. The parameters in our new relations are either pre-existing input in a multi-phase flow

  12. Large eddy simulation of turbulent statistical and transport properties in stably stratified flows

    Institute of Scientific and Technical Information of China (English)

    Xiang QIU; Yong-xiang HUANG; Zhi-ming LU; Yu-lu LIU

    2009-01-01

    Three dimensional large eddy simulation (LES) is performed in the inves-tigation of stably stratified turbulence with a sharp thermal interface. Main results are focused on the turbulent characteristic scale, statistical properties, transport properties,and temporal and spatial evolution of the scalar field. Results show that the buoyancy scale increases first, and then goes to a certain constant value. The stronger the mean shear, the larger the buoyancy scale. The overturning scale increases with the flow, and the mean shear improves the overturning scale. The flatness factor of temperature de-parts from the Ganssian distribution in a fairly large region, and its statistical properties are clearly different from those of the velocity fluctuations in strong stratified cases. Tur-bulent mixing starts from small scale motions, and then extends to large scale motions.

  13. Atomistic Force Field for Pyridinium-Based Ionic Liquids: Reliable Transport Properties

    DEFF Research Database (Denmark)

    Voroshylova, I. V.; Chaban, V. V.

    2014-01-01

    Reliable force field (FF) is a central issue in successful prediction of physical chemical properties via computer simulations. This work introduces refined FF parameters for six popular ionic liquids (ILs) of the pyridinium family (butylpyridinium tetrafluoroborate, bis(trifluoromethanesulfonyl)......Reliable force field (FF) is a central issue in successful prediction of physical chemical properties via computer simulations. This work introduces refined FF parameters for six popular ionic liquids (ILs) of the pyridinium family (butylpyridinium tetrafluoroborate, bis......(trifluoromethanesulfonyl)imide, dicyanamide, hexafluorophosphate, triflate, chloride). We elaborate a systematic procedure, which allows accounting for specific cationanion interactions in the liquid phase. Once these interactions are described accurately, all experimentally determined transport properties can be reproduced. We prove...

  14. Spin resonance transport properties of a single Au atom in S-Au-S junction and Au-Au-Au junction

    Science.gov (United States)

    Fangyuan, Wang; Guiqin, Li

    2016-07-01

    The spin transport properties of S-Au-S junction and Au-Au-Au junction between Au nanowires are investigated with density functional theory and the non-equilibrium Green's function. We mainly focus on the spin resonance transport properties of the center Au atom. The breaking of chemical bonds between anchor atoms and center Au atom significantly influences their spin transmission characteristics. We find the 0.8 eV orbital energy shift between anchor S atoms and the center Au atom can well protect the spin state stored in the S-Au-S junction and efficiently extract its spin state to the current by spin resonance mechanism, while the spin interaction of itinerant electrons and the valence electron of the center Au atom in the Au-Au-Au junction can extract the current spin information into the center Au atom. Fermi energy drift and bias-dependent spin filtering properties of the Au-Au-Au junction may transform information between distance, bias, and electron spin. Those unique properties make them potential candidates for a logical nanocircuit. Project supported by the National Basic Research Program of China (Grants No. 2011CB921602) and the National Natural Science Foundation of China (Grants No. 20121318158).

  15. Strain-modulated electronic and thermal transport properties of two-dimensional O-silica

    Science.gov (United States)

    Han, Yang; Qin, Guangzhao; Jungemann, Christoph; Hu, Ming

    2016-07-01

    Silica is one of the most abundant materials in the Earth’s crust and is a remarkably versatile and important engineering material in various modern science and technology. Recently, freestanding and well-ordered two-dimensional (2D) silica monolayers with octahedral (O-silica) building blocks were found to be theoretically stable by (Wang G et al 2015 J. Phys. Chem. C 119 15654-60). In this paper, by performing first-principles calculations, we systematically investigated the electronic and thermal transport properties of 2D O-silica and also studied how these properties can be tuned by simple mechanical stretching. Unstrained 2D O-silica is an insulator with an indirect band gap of 6.536 eV. The band gap decreases considerably with bilateral strain up to 29%, at which point a semiconductor-metal transition occurs. More importantly, the in-plane thermal conductivity of freestanding 2D O-silica is found to be unusually high, which is around 40 to 50 times higher than that of bulk α-quartz and more than two orders of magnitude higher than that of amorphous silica. The thermal conductivity of O-silica decreases by almost two orders of magnitude when the bilateral stretching strain reaches 10%. By analyzing the mode-dependent phonon properties and phonon-scattering channel, the phonon lifetime is found to be the dominant factor that leads to the dramatic decrease of the lattice thermal conductivity under strain. The very sensitive response of both band gap and phonon transport properties to the external mechanical strain will enable 2D O-silica to easily adapt to the different environment of realistic applications. Our study is expected to stimulate experimental exploration of further physical and chemical properties of 2D silica systems, and offers perspectives on modulating the electronic and thermal properties of related low-dimensional structures for applications such as thermoelectric, photovoltaic, and optoelectronic devices.

  16. GaAs nanowires: from manipulation of defect formation to controllable electronic transport properties.

    Science.gov (United States)

    Han, Ning; Hou, Jared J; Wang, Fengyun; Yip, SenPo; Yen, Yu-Ting; Yang, Zai-Xing; Dong, Guofa; Hung, TakFu; Chueh, Yu-Lun; Ho, Johnny C

    2013-10-22

    Reliable control in the crystal quality of synthesized III-V nanowires (NWs) is particularly important to manipulate their corresponding electronic transport properties for technological applications. In this report, a "two-step" growth process is adopted to achieve single-crystalline GaAs NWs, where an initial high-temperature nucleation process is employed to ensure the formation of high Ga supersaturated Au7Ga3 and Au2Ga alloy seeds, instead of the low Ga supersaturated Au7Ga2 seeds observed in the conventional "single-step" growth. These two-step NWs are long (>60 μm) and thick (>80 nm) with the minimal defect concentrations and uniform growth orientations. Importantly, these NWs exhibit p-type conductivity as compared to the single-step grown n-type NWs for the same diameter range. This NW conductivity difference (p- versus n-channel) is shown to originate from the donor-like crystal defects, such as As precipitates, induced by the low Ga supersaturated multicrystalline Au7Ga2 alloy seeds. Then the well-controlled crystal quality for desired electronic properties is further explored in the application of large-scale p-type GaAs NW parallel array FETs as well as the integration of both p- and n-type GaAs NWs into CMOS inverters. All these illustrate the successful control of NW crystal defects and corresponding electronic transport properties via the manipulation of Ga supersaturation in the catalytic alloy tips with different preparation methods. The understanding of this relationship between NW crystal quality and electronic transport properties is critical and preferential to the future development of nanoelectronic materials, circuit design, and fabrication.

  17. Transport mechanism and regulatory properties of the human amino acid transporter ASCT2 (SLC1A5).

    Science.gov (United States)

    Scalise, Mariafrancesca; Pochini, Lorena; Panni, Simona; Pingitore, Piero; Hedfalk, Kristina; Indiveri, Cesare

    2014-11-01

    The kinetic mechanism of the transport catalyzed by the human glutamine/neutral amino acid transporter hASCT2 over-expressed in P. pastoris was determined in proteoliposomes by pseudo-bi-substrate kinetic analysis of the Na(+)-glutamineex/glutaminein transport reaction. A random simultaneous mechanism resulted from the experimental analysis. Purified functional hASCT2 was chemically cross-linked to a stable dimeric form. The oligomeric structure correlated well with the kinetic mechanism of transport. Half-saturation constants (Km) of the transporter for the other substrates Ala, Ser, Asn and Thr were measured both on the external and internal side. External Km were much lower than the internal ones confirming the asymmetry of the transporter. The electric nature of the transport reaction was determined imposing a negative inside membrane potential generated by K(+) gradients in the presence of valinomycin. The transport reaction resulted to be electrogenic and the electrogenicity originated from external Na(+). Internal Na(+) exerted a stimulatory effect on the transport activity which could be explained by a regulatory, not a counter-transport, effect. Native and deglycosylated hASCT2 extracted from HeLa showed the same transport features demonstrating that the glycosyl moiety has no role in transport function. Both in vitro and in vivo interactions of hASCT2 with the scaffold protein PDZK1 were revealed.

  18. Research Update: Structural and transport properties of (Ca,LaFeAs2 single crystal

    Directory of Open Access Journals (Sweden)

    F. Caglieris

    2016-02-01

    Full Text Available Structural and transport properties in the normal and superconducting states are investigated in a Ca0.8La0.2FeAs2 single crystal with Tc = 27 K, belonging to the newly discovered 112 family of iron based superconductors. The transport critical current density Jc for both field directions measured in a focused ion beam patterned microbridge reveals a weakly field dependent and low anisotropic behaviour with a low temperature value as high as Jc(B = 0 ∼ 105 A/cm2. This demonstrates not only bulk superconductivity but also the potential of 112 superconductors towards applications. Interestingly, this superconducting compound undergoes a structural transition below 100 K which is evidenced by temperature-dependent X-ray diffraction measurements. Data analysis of Hall resistance and magnetoresistivity indicate that magnetotransport properties are largely dominated by an electron band, with a change of regime observed in correspondence of the onset of a structural transition. In the low temperature regime, the contribution of a hole band to transport is suggested, possibly playing a role in determining the superconducting state.

  19. Research Update: Structural and transport properties of (Ca,La)FeAs{sub 2} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Caglieris, F.; Pallecchi, I.; Lamura, G.; Putti, M. [CNR-SPIN and Università di Genova, Via Dodecaneso 33, I-16146 Genova (Italy); Sala, A. [CNR-SPIN and Università di Genova, Via Dodecaneso 33, I-16146 Genova (Italy); Department of Applied Chemistry, The University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565 (Japan); Fujioka, M. [National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047 (Japan); Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan); Hummel, F.; Johrendt, D. [Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstr. 5-13, 81377 München (Germany); Takano, Y. [National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047 (Japan); Ishida, S.; Iyo, A.; Eisaki, H. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565 (Japan); Ogino, H.; Yakita, H. [Department of Applied Chemistry, The University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); Shimoyama, J. [Department of Applied Chemistry, The University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258 (Japan)

    2016-02-01

    Structural and transport properties in the normal and superconducting states are investigated in a Ca{sub 0.8}La{sub 0.2}FeAs{sub 2} single crystal with T{sub c} = 27 K, belonging to the newly discovered 112 family of iron based superconductors. The transport critical current density J{sub c} for both field directions measured in a focused ion beam patterned microbridge reveals a weakly field dependent and low anisotropic behaviour with a low temperature value as high as J{sub c}(B = 0) ∼ 10{sup 5} A/cm{sup 2}. This demonstrates not only bulk superconductivity but also the potential of 112 superconductors towards applications. Interestingly, this superconducting compound undergoes a structural transition below 100 K which is evidenced by temperature-dependent X-ray diffraction measurements. Data analysis of Hall resistance and magnetoresistivity indicate that magnetotransport properties are largely dominated by an electron band, with a change of regime observed in correspondence of the onset of a structural transition. In the low temperature regime, the contribution of a hole band to transport is suggested, possibly playing a role in determining the superconducting state.

  20. Effects of Climate Changes on Firn Properties and Gas Transport in Firn

    Science.gov (United States)

    Stevens, C.; Lundin, J.; Vo, H.; Yoon, M.; Waddington, E. D.

    2014-12-01

    Knowledge of the physics of firn-density evolution and gas transport in firn has several important applications in glaciology, including (1) correcting for firn air content when estimating ice-sheet mass-balance changes from satellite altimetry and (2) determining the ice-age/gas-age difference for paleoclimate interpretations of ice-core records. The firn-physics group at the University of Washington is developing modular and open-source community models describing evolution of firn density, temperature, diffusivity, and other structural properties affecting gas transport. A novel aspect is that the gas model can be coupled to the density model, allowing bubble-close-off depth, lock-in depth, depth-integrated porosity, and effective diffusivity to evolve in the gas-transport model. This feature allows us to investigate changes in firn physical properties and the evolving impacts of those changes on gas diffusion, thermal and gravitational fractionation, and the mixing ratio of gasses in bubbles trapped in firn during climate change events. Here, we use ice-core derived and synthetic climate data to show the scope of these impacts for gradual and abrupt climate changes.

  1. Research Update: Structural and transport properties of (Ca,La)FeAs2 single crystal

    Science.gov (United States)

    Caglieris, F.; Sala, A.; Fujioka, M.; Hummel, F.; Pallecchi, I.; Lamura, G.; Johrendt, D.; Takano, Y.; Ishida, S.; Iyo, A.; Eisaki, H.; Ogino, H.; Yakita, H.; Shimoyama, J.; Putti, M.

    2016-02-01

    Structural and transport properties in the normal and superconducting states are investigated in a Ca0.8La0.2FeAs2 single crystal with Tc = 27 K, belonging to the newly discovered 112 family of iron based superconductors. The transport critical current density Jc for both field directions measured in a focused ion beam patterned microbridge reveals a weakly field dependent and low anisotropic behaviour with a low temperature value as high as Jc(B = 0) ˜ 105 A/cm2. This demonstrates not only bulk superconductivity but also the potential of 112 superconductors towards applications. Interestingly, this superconducting compound undergoes a structural transition below 100 K which is evidenced by temperature-dependent X-ray diffraction measurements. Data analysis of Hall resistance and magnetoresistivity indicate that magnetotransport properties are largely dominated by an electron band, with a change of regime observed in correspondence of the onset of a structural transition. In the low temperature regime, the contribution of a hole band to transport is suggested, possibly playing a role in determining the superconducting state.

  2. The influence of doping on the electronic transport properties of InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wirths, Stephan; Weis, Karl; Volk, Christian; Alagha, Shima; Akabori, Masashi; Sladek, Kamil; Trellenkamp, Stefan; Lueth, Hans; Schaepers, Thomas; Hardtdegen, Hilde; Gruetzmacher, Detlev [Institut fuer Bio- und Nanosysteme (IBN-1), Forschungszentrum Juelich (Germany); JARA, Fundamentals of Future Information Technology (Germany)

    2010-07-01

    The investigation of the electrical conductivity of semiconductor nanowires is a crucial step on the road to zero-dimensional electronic systems. Especially the effect of Si-doping on the resistivity plays an important role and has not been investigated, yet. We study the electronic transport properties of n-doped InAs:Si nanowires grown by metal organic vapor phase epitaxy. Nominally undoped wires and Si-doped wires with four different dopant concentrations are examined. Two- and four-terminal transport measurements are performed both at room temperature and at low temperatures down to 4 K. In addition, by using a SiO{sub 2} back gate, we yield field effect transistor characteristics. Hence, the depending of conductivity on the gate voltage is determined. Moreover, we investigate the temperature dependency of transport properties. For the lowest dopant concentration we quantify {rho}=(3.8{+-}0.8) x 10{sup -4} {omega}m and {rho}=(1.8{+-}0.4) x 10{sup -5} {omega}m for the highest dopant concentration. The values of {rho} were averaged over approximately 10 to 30 wires. We can conclude, that Si-doping decreases the resistivity.

  3. Theory of Band Warping and its Effects on Thermoelectronic Transport Properties

    Science.gov (United States)

    Mecholsky, Nicholas; Resca, Lorenzo; Pegg, Ian; Fornari, Marco

    2015-03-01

    Transport properties of materials depend upon features of band structures near extrema in the BZ. Such features are generally described in terms of quadratic expansions and effective masses. Such expansions, however, are permissible only under strict conditions that are sometimes violated by materials. Suggestive terms such as ``band warping'' have been used to refer to such situations and ad hoc methods have been developed to treat them. We develop a generally applicable theory, based on radial expansions, and a corresponding definition of angular effective mass which also accounts for effects of band non-parabolicity and anisotropy. Further, we develop precise procedures to evaluate band warping quantitatively and as an example we analyze the warping features of valence bands in silicon using first-principles calculations and we compare those with semi-empirical models. We use our theory to generalize derivations of transport coefficients for cases of either single or multiple electronic bands, with either quadratically expansible or warped energy surfaces. We introduce the transport-equivalent ellipsoid and illustrate the drastic effects that band warping can induce on thermoelectric properties using multi-band models. Vitreous State Laboratory and Samsung's GRO program.

  4. Electrical Transport Properties of Mn doped Bi2Se3 Thin Films

    Science.gov (United States)

    Babakiray, Sercan; Johnson, Trent; Borisov, Pavel; Lederman, David

    2015-03-01

    Magnetic impurity doping in topological insulators manifest itself with a gap opening in the Dirac cone as a result of breaking the time reversal symmetry. Moreover, the magnetic impurities affect the structural and quantum transport properties of topological insulators by increasing the disorder and by changing the bulk charge carrier type, charge carrier density and Hall mobility. Here, we investigated the effect of Mn doping on the structural and electrical transport properties of Bi2-xMnxSe3 thin films which are 12 quintuple layers thick and grown on Al2O3 (0001) single crystal substrates via molecular beam epitaxy (MBE). Hikami-Larkin-Nagaoka (HLN) formalism was used to study the weak antilocalization (WAL). Increasing Mn doping concentration was found to increase the bulk charge carrier density and to decrease the Hall mobility. A decrease was also observed in the phase coherence length related to WAL as a function of Mn content x. Values of another WAL parameter, the pre-factor alpha, showed that the top and bottom surfaces were coupled through the bulk conducting channels. The temperature dependence of phase coherence length indicated the electrical transport was dominated by 2D electron-electron scattering for the undoped, and by bulk weak localization effects for the Mn doped samples, respectively.

  5. Literature Survey of Crude Oil Properties Relevant to Handling and Fire Safety in Transport.

    Energy Technology Data Exchange (ETDEWEB)

    Lord, David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Luketa, Anay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wocken, Chad [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schlasner, Steve [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Aulich, Ted [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Allen, Ray [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rudeen, David Keith [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    Several fiery rail accidents in 2013-2015 in the U.S. and Canada carrying crude oil produced from the Bakken region of North Dakota have raised questions at many levels on the safety of transporting this, and other types of crude oil, by rail. Sandia National Laboratories was commissioned by the U.S. Department of Energy to investigate the material properties of crude oils, and in particular the so-called "tight oils" like Bakken that comprise the majority of crude oil rail shipments in the U.S. at the current time. The current report is a literature survey of public sources of information on crude oil properties that have some bearing on the likelihood or severity of combustion events that may occur around spills associated with rail transport. The report also contains background information including a review of the notional "tight oil" field operating environment, as well a basic description of crude oils and potential combustion events in rail transport. This page intentionally blank

  6. Effects of functional group mass variance on vibrational properties and thermal transport in graphene

    Science.gov (United States)

    Lindsay, L.; Kuang, Y.

    2017-03-01

    Intrinsic thermal resistivity critically depends on features of phonon dispersions dictated by harmonic interatomic forces and masses. Here we present the effects of functional group mass variance on vibrational properties and thermal conductivity (κ ) of functionalized graphene from first-principles calculations. We use graphane, a buckled graphene backbone with covalently bonded hydrogen atoms on both sides, as the base material and vary the mass of the hydrogen atoms to simulate the effect of mass variance from other functional groups. We find nonmonotonic behavior of κ with increasing mass of the functional group and an unusual crossover from acoustic-dominated to optic-dominated thermal transport behavior. We connect this crossover to changes in the phonon dispersion with varying mass which suppress acoustic phonon velocities, but also give unusually high velocity optic modes. Further, we show that out-of-plane acoustic vibrations contribute significantly more to thermal transport than in-plane acoustic modes despite breaking of a reflection-symmetry-based scattering selection rule responsible for their large contributions in graphene. This work demonstrates the potential for manipulation and engineering of thermal transport properties in two-dimensional materials toward targeted applications.

  7. Property Valuation and Radioactive Materials Transportation: A Legal, Economic and Public Perception Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Holm, J. A.; Thrower, A. W.; Widmayer, D. A.; Portner, W.

    2003-02-26

    The shipment of transuranic (TRU) radioactive waste to the Waste Isolation Pilot Plant (WIPP) in New Mexico raised a serious socioeconomic issue - the potential devaluation of property values due to the transportation of TRU waste from generator sites to the disposal facility. In 1992, the New Mexico Supreme Court held in City of Santa Fe v. Komis that a loss in value from public perception of risk was compensable. This issue has become an extremely important one for the development of the Yucca Mountain repository in Nevada for disposal of spent nuclear fuel and high-level radioactive waste. Much research has been conducted about the potential impacts of transportation of spent fuel and radioactive waste. This paper examines the pertinent studies conducted since the Komis case. It examines how the public debate on radioactive materials transportation continues and is now focused on transportation of high-level waste and spent nuclear fuel to the proposed Yucca Mountain repository. Finally, the paper suggests a path forward DOE can take to address this issue.

  8. Charge transport properties of bulk Ta3N5 from first principles

    Science.gov (United States)

    Morbec, Juliana M.; Galli, Giulia

    2016-01-01

    Tantalum nitride is considered a promising material for photoelectrochemical water splitting, however, its charge transport properties remain poorly understood. We investigated polaronic and band transport in Ta3N5 using first-principles calculations. We first studied the formation of small polarons using density-functional theory (DFT) including DFT +U and hybrid functionals. We found that electron small polarons may occur but hole polarons are not energetically favorable. The estimated polaronic mobility for electrons is at least three orders of magnitude smaller than that measured in Ta3N5 films, suggesting that the main transport mechanism for both electrons and holes is bandlike. Since band transport is strongly affected by the carrier effective masses, and Ta3N5 is known to have large electron and hole effective masses, we also investigated whether substitutional impurities or strain may help lower the effective masses. We found a significant reduction in both electron and hole effective masses (up to 17% for electrons and 39% for holes) under applied strain, which may lead to a substantial improvement (up to 30% for electrons and 15% for holes) in the carrier mobilities.

  9. Transport, geometrical, and topological properties of stealthy disordered hyperuniform two-phase systems.

    Science.gov (United States)

    Zhang, G; Stillinger, F H; Torquato, S

    2016-12-28

    Disordered hyperuniform many-particle systems have attracted considerable recent attention, since they behave like crystals in the manner in which they suppress large-scale density fluctuations, and yet also resemble statistically isotropic liquids and glasses with no Bragg peaks. One important class of such systems is the classical ground states of "stealthy potentials." The degree of order of such ground states depends on a tuning parameter χ. Previous studies have shown that these ground-state point configurations can be counterintuitively disordered, infinitely degenerate, and endowed with novel physical properties (e.g., negative thermal expansion behavior). In this paper, we focus on the disordered regime (0 two-phase media by circumscribing each point with a possibly overlapping sphere of a common radius a: the "particle" and "void" phases are taken to be the space interior and exterior to the spheres, respectively. The hyperuniformity of such two-phase media depends on the sphere sizes: While it was previously analytically proven that the resulting two-phase media maintain hyperuniformity if spheres do not overlap, here we show numerically that they lose hyperuniformity whenever the spheres overlap. We study certain transport properties of these systems, including the effective diffusion coefficient of point particles diffusing in the void phase as well as static and time-dependent characteristics associated with diffusion-controlled reactions. Besides these effective transport properties, we also investigate several related structural properties, including pore-size functions, quantizer error, an order metric, and percolation thresholds. We show that these transport, geometrical, and topological properties of our two-phase media derived from decorated stealthy ground states are distinctly different from those of equilibrium hard-sphere systems and spatially uncorrelated overlapping spheres. As the extent of short-range order increases, stealthy disordered

  10. Computation of thermodynamic and transport properties to predict thermophoretic effects in an argon-krypton mixture.

    Science.gov (United States)

    Miller, Nicholas A T; Daivis, Peter J; Snook, Ian K; Todd, B D

    2013-10-14

    Thermophoresis is the movement of molecules caused by a temperature gradient. Here we report the results of a study of thermophoresis using non-equilibrium molecular dynamics simulations of a confined argon-krypton fluid subject to two different temperatures at thermostated walls. The resulting temperature profile between the walls is used along with the Soret coefficient to predict the concentration profile that develops across the channel. We obtain the Soret coefficient by calculating the mutual diffusion and thermal diffusion coefficients. We report an appropriate method for calculating the transport coefficients for binary systems, using the Green-Kubo integrals and radial distribution functions obtained from equilibrium molecular dynamics simulations of the bulk fluid. Our method has the unique advantage of separating the mutual diffusion and thermal diffusion coefficients, and calculating the sign and magnitude of their individual contributions to thermophoresis in binary mixtures.

  11. An Assessment of Transport Property Estimation Methods for Ammonia–Water Mixtures and Their Influence on Heat Exchanger Size

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Modi, Anish; Jensen, Jonas Kjær

    2015-01-01

    are considered: a flue-gas-based heat recovery boiler for a combined cycle power plant and a hot-oil-based boiler for a solar thermal power plant. The different transport property methods resulted in larger differences at high pressures and temperatures, and a possible discontinuous first derivative, when using...... the interpolative methods in contrast to the corresponding state methods. Nevertheless, all possible mixture transport property combinations used herein resulted in a heat exchanger size within 4.3 % difference for the flue-gas heat recovery boiler, and within 12.3 % difference for the oil-based boiler.......Transport properties of fluids are indispensable for heat exchanger design. The methods for estimating the transport properties of ammonia–water mixtures are not well established in the literature. The few existent methods are developed from none or limited, sometimes inconsistent experimental...

  12. Electrical and thermal transport property studies of high-temperature thermoelectric materials

    Science.gov (United States)

    Bates, J. L.

    1984-12-01

    High-temperature materials that exhibit small polaron conduction appear to exhibit the highest figures of merit. A thermoelectric model based on small polaron transport has been developed. The model predicts that broad-band semiconductors with small polarons hopping along inequivalent sites of distorted sublattices can result in increases in both the electrical conductivity and the Seeback coefficient with increasing temperature without significant increases in thermal conductivity. High figures of merit (ZT), greater than 1 at 1000K, that increase with increasing temperatures are predicted. The model is being applied to the divalent metal containing (Y,LA)Cr0(3) systems with an ABO(3) perovskite structure. Transport properties have been determined for various doping elements and for different compositions. These data are being used for the evaluation of this model.

  13. Transport properties of non-conformal gluonic matter from compactified D4 branes

    CERN Document Server

    Wu, Chao; Huang, Mei

    2015-01-01

    We investigate non-conformal transport properties of gluonic matter via the fluid/gravity correspondence from compactified D4 branes. The D4-D6 model and the Sakai-Sugimoto (SS) model are two non-conformal holographic QCD models from top- down, whose background is the compactified D4 black branes under the near horizon limit. By using the dimensional reduction technique, we derive a 5D Einstein gravity minimally coupled with 3 scalar fields from the 10D D4 brane background. Following the boundary derivative expansion formalism of fluid/gravity correspondence, we obtain for the first time all the first order transport coefficients separately for non-conformal gluonic matter, and the ratio of the bulk to shear viscosity and the sound speed are consistent with former studies.

  14. Transport properties of hydrogen passivated silicon nanotubes and silicon nanotube field effect transistors

    KAUST Repository

    Montes Muñoz, Enrique

    2017-01-24

    We investigate the electronic transport properties of silicon nanotubes attached to metallic electrodes from first principles, using density functional theory and the non-equilibrium Green\\'s function method. The influence of the surface termination is studied as well as the dependence of the transport characteristics on the chirality, diameter, and length. Strong electronic coupling between nanotubes and electrodes is found to be a general feature that results in low contact resistance. The conductance in the tunneling regime is discussed in terms of the complex band structure. Silicon nanotube field effect transistors are simulated by applying a uniform potential gate. Our results demonstrate very high values of transconductance, outperforming the best commercial silicon field effect transistors, combined with low values of sub-threshold swing.

  15. Naphthodipyrrolidone (NDP) Based Conjugated Polymers with High Electron Mobility and Ambipolar Transport Properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haichang; Zhang, Shuo; Mao, Yifan; Liu, Kewei; Chen, Yu-Ming; Jiang, Zhang; Strzalka, Joseph; Yang, Wenjun; Wang, Chien-Lung; Zhu, Yu

    2017-06-07

    Two novel donor-acceptor pi-conjugated polymers based on naphthodipyrrolidone (NDP) were synthesized and characterized. The polymers possess low band gaps and suitable molecular orbital levels as ambipolar semiconductors. The thin film organic field effect transistor of NDP polymers exhibited ambipolar transport properties with a high electron mobility up to 0.67 cm(2) V-1 s(-1). The grazing-incidence wide-angle X-ray scattering (GIWAXS) studies demonstrated that the polymer molecules pack into a long-range-ordered lamellar structure with isotropically oriented crystalline domains. Thermal annealing promoted edge-on lamellar stacking as evidenced by the increased diffraction intensity along the out-of-plane direction. The polymer with NDP and bithiophene units achieved the best edge-on lamellar stacking after thermal annealing, which yielded the best electron transport performance in this work.

  16. Electronic and Quantum Transport Properties of Atomically Identified Si Point Defects in Graphene.

    Science.gov (United States)

    Lopez-Bezanilla, Alejandro; Zhou, Wu; Idrobo, Juan-Carlos

    2014-05-15

    We report high-resolution scanning transmission electron microscopy images displaying a range of inclusions of isolated silicon atoms at the edges and inner zones of graphene layers. Whereas the incorporation of Si atoms to a graphene armchair edge involves no reconstruction of the neighboring carbon atoms, the inclusion of a Si atom to a zigzag graphene edge entails the formation of five-membered carbon rings. In all the observed atomic edge terminations, a Si atom is found bridging two C atoms in a 2-fold coordinated configuration. The atomic-scale observations are underpinned by first-principles calculations of the electronic and quantum transport properties of the structural anomalies. Experimental estimations of Si-doped graphene band gaps realized by means of transport measurements may be affected by a low doping rate of 2-fold coordinated Si atoms at the graphene edges, and 4-fold coordinated at inner zones due to the apparition of mobility gaps.

  17. Photo-transport properties of Pb2CrO5 single crystals

    Science.gov (United States)

    Mondal, P. S.; Okazaki, R.; Taniguchi, H.; Terasaki, I.

    2014-11-01

    We report photo-thermoelectric transport phenomena in Pb2CrO5 single crystals. Without illumination, this material exhibits an insulating behavior characterized by an activation-type temperature variation of the electrical conductivity. The Seebeck coefficient contrastingly shows a crossover from high-temperature insulating to low-temperature metallic behavior, which is attributed to degenerate carriers in a donor level. We have found that under illumination, both the conductivity and the Seebeck coefficient increase in magnitude with increasing photon flux density in the degenerate-conduction regime. This result is difficult to understand within a simple photo-doping effect, which usually leads to a decrease in the Seebeck coefficient under illumination. The observed phenomenon is discussed in terms of a two-carrier contribution to the transport properties.

  18. Photo-transport properties of Pb{sub 2}CrO{sub 5} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, P. S.; Okazaki, R., E-mail: okazaki.ryuji@cc.nagoya-u.ac.jp; Taniguchi, H.; Terasaki, I. [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)

    2014-11-21

    We report photo-thermoelectric transport phenomena in Pb{sub 2}CrO{sub 5} single crystals. Without illumination, this material exhibits an insulating behavior characterized by an activation-type temperature variation of the electrical conductivity. The Seebeck coefficient contrastingly shows a crossover from high-temperature insulating to low-temperature metallic behavior, which is attributed to degenerate carriers in a donor level. We have found that under illumination, both the conductivity and the Seebeck coefficient increase in magnitude with increasing photon flux density in the degenerate-conduction regime. This result is difficult to understand within a simple photo-doping effect, which usually leads to a decrease in the Seebeck coefficient under illumination. The observed phenomenon is discussed in terms of a two-carrier contribution to the transport properties.

  19. Effect of substitutional impurities on the electronic transport properties of graphene

    Science.gov (United States)

    Berdiyorov, G. R.; Bahlouli, H.; Peeters, F. M.

    2016-10-01

    Density-functional theory in combination with the nonequilibrium Green's function formalism is used to study the effect of substitutional doping on the electronic transport properties of hydrogen passivated zig-zag graphene nanoribbon devices. B, N and Si atoms are used to substitute carbon atoms located at the center or at the edge of the sample. We found that Si-doping results in better electronic transport as compared to the other substitutions. The transmission spectrum also depends on the location of the substitutional dopants: for single atom doping the largest transmission is obtained for edge substitutions, whereas substitutions in the middle of the sample give larger transmission for double carbon substitutions. The obtained results are explained in terms of electron localization in the system due to the presence of impurities.

  20. A comparative study of proton transport properties of zirconium phosphate and its metal exchanged phases

    Indian Academy of Sciences (India)

    Rakesh Thakkar; Heemanshu Patel; Uma Chudasama

    2007-06-01

    A new phase of amorphous zirconium phosphate (ZrP), an inorganic ion exchanger of the class of tetravalent metal acid (TMA) salt, is synthesized by sol–gel method. The protons present in the structural hydroxyl groups indicate good potential for TMA salts to exhibit solid state proton conduction. Cu2+ and Li+ are exchanged onto ZrP to yield CuZrP and LiZrP exchanged phases. All these materials were characterized for elemental analysis (ICP–AES), thermal analysis (TGA, DSC), X-ray analysis and FTIR spectroscopy. The transport properties of these materials were explored and compared by measuring conductance at different temperatures using an impedance analyser. It is observed that conductivity decreases with increasing temperature in all cases and mechanism of transportation is proposed to be Grotthuss type. Conductivity performance of ZrP, CuZrP and LiZrP is discussed based on conductivity data and activation energy.

  1. Fundamental investigation of the transport properties of superacids in aqueous and non-aqueous media

    Science.gov (United States)

    Suarez, Sophia

    In the quest to develop more efficient energy providers one of the main focus of research has been on the improvement of ion transport. In lithium battery research this has led to the incorporation of various lithium salts, ceramics and plasticizers into the poly(ethylene)oxide (PEO) matrix, the polymer most used In Proton Conduction Membrane (PCM) fuel cell research this has led to the development of new membranes, which are designed with to replicate Nafion's ((c)DuPont) proton transport but also improve upon its deficiency of transporting intact fuel molecules and its dependence upon the presence of solvating water molecules. To better understand the process of ion transport, NMR was used to investigate dynamic properties such as D (self-diffusion coefficient) and T1 (spin-lattice relaxation time) of various proton and lithium ion-conducting systems. Ionic conductivity and viscosity measurements were also performed. The systems studied includes aqueous superacid solutions (trifluoromethanesulfonic (TFSA), para-toluenesulfonic (PTSA) and bis(trifluoromethanesulfonyl)imide (TFSI)); nano-porous (NP-) PCM's incorporating various ceramics and 3M fuel/2M H2SO4 solutions; and P(EO)20LiBETI (LiN(SO 2CF2CF3)2 composite incorporating SiO 2 ceramic nano particles. The objective of the study of the superacid solutions was to determine the effect of concentration on the transport. It was found that beyond the ionic conductivity maximum, fluctuations in both D and T1 supports the existence of local ordering in the ionic network, caused by the reduced solvent dielectric coefficient and increasing viscosity. Of the three superacids TFSA was the most conductive and most affected by reduced solvent concentration. For the P(EO)20LiBETI composite the aim was to determine the effect of the ceramic on the ion transport of the composite in a solvent free environment. Results show that the ceramic causes only modest increase in the lithium transport below 90°C. The objective in the

  2. Transmission and transport properties in Cantor graphene structures: The case of magnetoelectric modulation

    Science.gov (United States)

    Rodríguez-González, R.; Rodríguez-Vargas, I.

    2017-04-01

    We discuss theoretically the transmission and transport properties of Dirac electrons in a Cantor graphene system under magnetoelectric effects. The transfer matrix method and the Landauer-Büttiker formalism have been implemented to compute the transmittance and the linear-regime conductance, respectively. The fractal order of Cantor type together with the magnetic and electric field are used to distribute and generate the magnetoelectric barriers. This system give us the possibility of compare the mentioned physical properties for magnetic and magnetoelectric barriers. We found a bifurcation process in the transmission spectra which is observable when the generation increases. Also, an asymmetrical and symmetrical behavior is presented for magnetic and magnetoelectric barriers, respectively. In general, an oscillatory behavior is manifested in the conductance. Moreover, we can describe the peaks (form and location) that give rise to the oscillations through the contour plots of the transmittance in the (E ,ky) space. Likewise, by increasing the generation of the system the conductance is enhanced, the oscillations reduced and less pronounced. In short, the magnetoelectric modulation along with the fractal order can be used to control the transmission and transport properties in graphene-based structures.

  3. Magnetic, transport and structural properties of Co/Ir multilayers grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Colis, S.; Dinia, A.; Ulhaq-Bouillet, C.; Panissod, P.; Meny, C.; Schmerber, G.; Arabski, J. [IPCMS-GEMME (UMR 7504 du CNRS), 23 rue du Loess, BP 34, F-67034 Strasbourg Cedex 2 (France)

    2003-09-01

    We report on the structural properties of a [Co{sub 30}/Ir{sub 10}]{sub 10} {sub x} (A) superlattice, as well as on the magnetic and transport properties of a Co{sub 15}/Ir{sub 5}/Co{sub 30} (A) artificial ferrimagnetic system. The samples were grown by molecular beam epitaxy (MBE) on MgO(001) substrates covered with a Ir{sub 130} (A) buffer layer. High resolution cross section and plan view transmission electron microscopy (TEM) images present a high quality epitaxial stack [100]MgO(001) parallel [100]Ir(001) parallel [100]Co(001), with a tetragonalization of the Co fcc structure, due to strains induced by the Ir buffer. TEM images also show that the Co/Ir interfaces are flat, while the layers are continuous and free of bridges. These observations are consistent with zero field nuclear magnetic resonance measurements which indicate an fcc structure of the Co layers, and an interface mixing between Co and Ir limited to one atomic layer. As a consequence the antiferromagnetically coupled Co/Ir/Co sandwich presents large saturation and coercive fields which exceed 20 kOe and 220 Oe, respectively. Annealing made on the same sandwich indicate that the magnetic and transport properties are stable up to 300 C. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Pressure tuning of the electrical transport properties of the Weyl semimetal NbP

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Ricardo dos; Ajeesh, M.O.; Sun, Yan; Shekhar, Chandra; Schmidt, Marcus; Felser, Claudia; Yan, Binghai; Nicklas, Michael [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany)

    2016-07-01

    Recently enormous attention has been given to a class of material called Weyl semimetal (WSM) due to the prediction of many exotic phenomena, in particular exceptional transport properties, making these systems not only interesting for fundamental research, but also promising materials for novel applications. WSM can be viewed as the hybrid of 3D graphene and topological insulators. The band crossing point, the so-called Weyl point, acts as a magnetic monopole (a singular point of Berry curvature) in momentum space, which always comes in a pairs. If the time-reversal and inversion symmetries are respected, a pair of Weyl points is degenerate in energy, forming another topological phase called Dirac semimetal. Owing this complex band structure the details of the electronic structure can play a significant role in the electrical transport properties of these materials. In this context, external pressure is an important control parameter to effectively tune lattice structures and the corresponding electronic states in a systematic fashion, avoiding the complexity brought by chemical doping. Here, we present a high pressure study of the magnetotransport properties of the Weyl semimetal NbP, which are particularly important to explore novel phenomena and understand the physics behind.

  5. Transport Properties of the Organic Conductor (TMTSF)2BrO4: Evidence of Variable Range Hopping

    DEFF Research Database (Denmark)

    Mortensen, Kell; Jacobsen, Claus Schelde; Bechgaard, Klaus

    1984-01-01

    A study of d.c. and microwave conductivity and thermoelectric power of the organic conductor (TMTSF)2BrO4 is presented. The transport properties are in qualitative agreement with charge transport via variable-range hopping among localized states. The localization is attributed to the anions, which...

  6. Quantitative characterization of the microstructure and transport properties of biopolymer networks

    Science.gov (United States)

    Jiao, Yang; Torquato, Salvatore

    2012-06-01

    Biopolymer networks are of fundamental importance to many biological processes in normal and tumorous tissues. In this paper, we employ the panoply of theoretical and simulation techniques developed for characterizing heterogeneous materials to quantify the microstructure and effective diffusive transport properties (diffusion coefficient De and mean survival time τ) of collagen type I networks at various collagen concentrations. In particular, we compute the pore-size probability density function P(δ) for the networks and present a variety of analytical estimates of the effective diffusion coefficient De for finite-sized diffusing particles, including the low-density approximation, the Ogston approximation and the Torquato approximation. The Hashin-Strikman upper bound on the effective diffusion coefficient De and the pore-size lower bound on the mean survival time τ are used as benchmarks to test our analytical approximations and numerical results. Moreover, we generalize the efficient first-passage-time techniques for Brownian-motion simulations in suspensions of spheres to the case of fiber networks and compute the associated effective diffusion coefficient De as well as the mean survival time τ, which is related to nuclear magnetic resonance relaxation times. Our numerical results for De are in excellent agreement with analytical results for simple network microstructures, such as periodic arrays of parallel cylinders. Specifically, the Torquato approximation provides the most accurate estimates of De for all collagen concentrations among all of the analytical approximations we consider. We formulate a universal curve for τ for the networks at different collagen concentrations, extending the work of Torquato and Yeong (1997 J. Chem. Phys. 106 8814). We apply rigorous cross-property relations to estimate the effective bulk modulus of collagen networks from a knowledge of the effective diffusion coefficient computed here. The use of cross-property relations

  7. Linking aquifer spatial properties and non-Fickian transport in mobile-immobile like alluvial settings

    Science.gov (United States)

    Zhang, Yong; Green, Christopher T.; Baeumer, Boris

    2014-01-01

    Time-nonlocal transport models can describe non-Fickian diffusion observed in geological media, but the physical meaning of parameters can be ambiguous, and most applications are limited to curve-fitting. This study explores methods for predicting the parameters of a temporally tempered Lévy motion (TTLM) model for transient sub-diffusion in mobile–immobile like alluvial settings represented by high-resolution hydrofacies models. The TTLM model is a concise multi-rate mass transfer (MRMT) model that describes a linear mass transfer process where the transfer kinetics and late-time transport behavior are controlled by properties of the host medium, especially the immobile domain. The intrinsic connection between the MRMT and TTLM models helps to estimate the main time-nonlocal parameters in the TTLM model (which are the time scale index, the capacity coefficient, and the truncation parameter) either semi-analytically or empirically from the measurable aquifer properties. Further applications show that the TTLM model captures the observed solute snapshots, the breakthrough curves, and the spatial moments of plumes up to the fourth order. Most importantly, the a priori estimation of the time-nonlocal parameters outside of any breakthrough fitting procedure provides a reliable “blind” prediction of the late-time dynamics of subdiffusion observed in a spectrum of alluvial settings. Predictability of the time-nonlocal parameters may be due to the fact that the late-time subdiffusion is not affected by the exact location of each immobile zone, but rather is controlled by the time spent in immobile blocks surrounding the pathway of solute particles. Results also show that the effective dispersion coefficient has to be fitted due to the scale effect of transport, and the mean velocity can differ from local measurements or volume averages. The link between medium heterogeneity and time-nonlocal parameters will help to improve model predictability for non

  8. Scaling of plant size and age emerges from linked aboveground and belowground transport network properties

    Science.gov (United States)

    Manzoni, S.; Hunt, A. G.

    2016-12-01

    Vegetation growth modulates cycling of water, carbon, and nutrients at local-to-global scales. It is therefore critical to quantify plant growth rates and how they are constrained by environmental conditions (especially limited resource availability). Various theoretical approaches have been proposed to this aim. Specifically, allometric theory provides a powerful tool to describe plant growth form and function, but it is focused on the properties of plant xylem networks, neglecting any role played by soils in supplying water to plants. On the other hand, percolation theory addresses physical constraints imposed by the soil pore network to water and nutrient transport, neglecting roles of root networks and vegetation taking up soil resources. In this contribution, we merge these two perspectives to derive scaling relations between plant size (namely height) and age. Our guiding hypothesis is that the root network expands in the soil at a rate sufficient to match the rate of transport of water and nutrients in an idealized optimal fractal pore network, as predicted by percolation theory; with nutrient transport distance vs. time scaling exponent 0.82, and water transport (saturated conditions) distance vs. time scaling exponent 1. The root expansion rate is mirrored by growth aboveground, as in allometric theory, which predicts an isometric relation between root extension and plant height. Building on these results, we predict that the scaling of plant height and age should also have exponent 0.82 in natural systems where nutrients are heterogeneously distributed, and 1 in fertilized systems where nutrients are homogeneously distributed. These predictions are successfully tested with extensive datasets covering major plant functional types worldwide, showing that soil and root network properties constrain vegetation growth by setting limits to the rates of water and nutrient supply to plants.

  9. The Effect of Twin Grain Boundary Tuned by Temperature on the Electrical Transport Properties of Monolayer MoS2

    Directory of Open Access Journals (Sweden)

    Luojun Du

    2016-09-01

    Full Text Available Theoretical calculation and experimental measurement have shown that twin grain boundary (GB of molybdenum disulphide (MoS2 exhibits extraordinary effects on transport properties. Precise transport measurements need to verify the transport mechanism of twin GB in MoS2. Here, monolayer molybdenum disulphide with a twin grain boundary was grown in our developed low-pressure chemical vapor deposition (CVD system, and we investigated how the twin GB affects the electrical transport properties of MoS2 by temperature-dependent transport studies. At low temperature, the twin GB can increase the in-plane electrical conductivity of MoS2 and the transport exhibits variable-range hopping (VRH, while at high temperature, the twin GB impedes the electrical transport of MoS2 and the transport exhibits nearest-neighbor hopping (NNH. Our results elucidate carrier transport mechanism of twin GB and give an important indication of twin GB in tailoring the electronic properties of MoS2 for its applications in next-generation electronics and optoelectronic devices.

  10. The influence of stoichiometry on electrical properties of silicon carbide grown by physical vapor transport process

    Science.gov (United States)

    Li, Qiang

    The purposes of this thesis were to investigate the influence of the vapor phase stoichiometry in the ambient on electrical properties of silicon carbide grown by physical vapor transport (PVT) process in order to provide a better understanding of the nature of the compensation mechanisms in semi-insulating SiC crystals. Standard PVT and hydrogen-assisted PVT processes have been used to grow SiC single crystals. Chemical elemental analysis, contactless resistivity mapping (COREMA), temperature dependent Hall measurements (TDH), deep level transient spectroscopy (DLTS), and minority diffusion length measurements were performed to characterize the properties of SiC wafers. The nitrogen contamination, the net carrier concentrations, and the concentrations of the major deep traps in the undoped and nitrogen-doped SiC crystals were found to substantially decrease during the standard PVT growth when moving from seed to tail of the crystal. Addition of hydrogen to the growth ambient changed all the properties in the same direction. As a consequence of the doping and deep traps variations, the electrical properties including resistivity, Fermi energy, and minority carrier lifetime continuously changed during the growth. The results of the hydrogen-assisted PVT growth and the virtual reactor growth modeling indicated that the electrical properties change as a function of stoichiometry in the vapor phase, and the carbon transport efficiency can be enhanced by the reactions of hydrogen with the SiC charge material and the graphite parts of the crucible. Thermodynamic calculation of the vapor phase stoichiometry and the studies of the properties of H2-assisted PVT-grown crystals have shown that hydrogen can be used as a key factor controlling the vapor phase stoichiometry in the PVT process; in this manner the purity, electrical uniformities and the yield of the semi-insulating wafers can be improved to a great extent. The electron mobility values were found unusually low in

  11. Transport and Fatigue Properties of Ferroelectric Polymer P(VDF-TrFE) For Nonvolatile Memory Applications

    KAUST Repository

    Hanna, Amir

    2012-06-01

    Organic ferroelectrics polymers have recently received much interest for use in nonvolatile memory devices. The ferroelectric copolymer poly(vinylidene fluoride- trifluoroethylene) , P(VDF-TrFE), is a promising candidate due to its relatively high remnant polarization, low coercive field, fast switching times, easy processability, and low Curie transition. However, no detailed study of charge injection and current transport properties in P(VDF-TrFE) have been reported in the literature yet. Charge injection and transport are believed to affect various properties of ferroelectric films such as remnant polarization values and polarization fatigue behavior.. Thus, this thesis aims to study charge injection in P(VDF-TrFE) and its transport properties as a function of electrode material. Injection was studied for Al, Ag, Au and Pt electrodes. Higher work function metals such as Pt have shown less leakage current compared to lower work function metals such as Al for more than an order of magnitude. That implied n-type conduction behavior for P(VDF-TrFE), as well as electrons being the dominant injected carrier type. Charge transport was also studied as a function of temperature, and two major transport regimes were identified: 1) Thermionic emission over a Schottky barrier for low fields (E < 25 MV/m). 2) Space-Charge-Limited regime at higher fields (25 < E <120 MV/m). We have also studied the optical imprint phenomenon, the polarization fatigue resulting from a combination of broad band optical illumination and DC bias near the switching field. A setup was designed for the experiment, and validated by reproducing the reported effect in polycrystalline Pb(Zr,Ti)O3 , PZT, film. On the other hand, P(VDF-TrFE) film showed no polarization fatigue as a result of optical imprint test, which could be attributed to the large band gap of the material, and the low intensity of the UV portion of the arc lamp white light used for the experiment. Results suggest using high work

  12. The Effect of Fluid Properties on Field-Scale Anion Transport During Intermittent Unsaturated Flow

    Science.gov (United States)

    Ward, A.; Gee, G. W.; Zhang, Z. F.

    2001-12-01

    Laboratory-scale experiments suggest that the properties of hypersaline fluids may influence transport behavior, to extent of finger formation, though an interaction between fluid and hydraulic properties. Yet, the importance of these mechanisms to field-scale transport is largely unknown, thereby limiting the accuracy of contaminant transport predictions. To assess the importance of these interactions in field-scale solute transport, tank leaks were simulated by performing a series of injections, using solute-free and hypersaline waters, in two consecutive years. Starting in May 2000, five 4000-L injections of Columbia River water were made with no-flow periods occurring every 3-5 days. The third injection contained 1000 ppm of Br- and a suite of isotopic tracers. In May 2001, the experiment was repeated with five 4000-L injections of saturated sodium thiosulfate containing 2500 ppm of Cl- with no-flow periods occurring every 3-5 days. Water content distributions were measured by neutron probe in 32 wells (18 m deep) arranged in a concentric pattern extending to 16 m in diameter. Water extracts from soil cores were analyzed for anions including Fl-, Cl-, Br-, NO3{-}, PO42-, SO42-, and S2O32-. Differences in the location of the wetting and solute fronts were apparent with the magnitude dependent on fluid constitution. Resident concentration profiles were generally asymmetric with a large mass occurring at 5-7 m, and a smaller mass at 10-12 m. Fine-textured layers at 6 and 11 m caused a substantial increase in lateral solute convection and confined longitudinal spreading to 12 m, except at one location where solute was detected at 16 m. The locations of multiple peaks were coincident with the finer-textured lenses, emphasizing the need to consider local-scale textural discontinuities in conceptual models of field-scale transport at the Hanford Site. Results show no evidence of fingering due to fluid properties. Pacific Northwest National Laboratory is operated for

  13. Regional analysis techniques for integrating experimental and numerical measurements of transport properties of reservoir rocks

    Science.gov (United States)

    Alizadeh, S. M.; Latham, S.; Middleton, J.; Limaye, A.; Senden, T. J.; Arns, C. H.

    2017-02-01

    Assessing the mechanisms of micro-structural change and their effect on transport properties using digital core analysis requires balancing field of view and resolution. This typically leads to the compromise of working with relatively small samples, where boundary effects can be substantial. A direct comparison with experiment, as e.g. desirable to eliminate unknown parameters and integrate numerical and physical experiments, needs to consider these boundary effects. Here we develop a workflow to define measuring windows within a sample where these boundary effects are minimised allowing the integration of physical and numerical experiment. We consider in particular sleeve leakage and use a radial partitioning of the solutions to various transport equations to derive relevant regional measures, which may be used for the development of cross-correlations between physical properties. Samples of Bentheimer and Castlegate sandstone as well as Mt. Gambier limestone and a sucrosic dolomite are considered. The sample plugs are encased in rubber sleeves and micro-CT images acquired at ambient conditions. Using these high-resolution images we calculate transport properties, namely permeability and electrical conductivity, and analyse the resulting field solutions with regard to flux across different regions of interest. The latter are selected on the basis of distance to the sample sleeve inner surface. Clear bypassing at the sleeve-sample interface in terms of elevated fluxes is observed for all samples, although to different extent. We consider different sleeve boundary conditions to define a measuring window minimising these effects, use the procedure to compare flux averages defined over these measuring windows with conventional choices of simulation domains, and compare resulting physical cross-correlations.

  14. Controlling In–Ga–Zn–O thin films transport properties through density changes

    Energy Technology Data Exchange (ETDEWEB)

    Kaczmarski, Jakub, E-mail: kaczmarski@ite.waw.pl [Institute of Electron Technology, al. Lotników 32/46, 02-668 Warsaw (Poland); Boll, Torben [Department of Applied Physics, Chalmers University of Technology, Fysikgränd 3, SE-412 96 Gothenburg (Sweden); Borysiewicz, Michał A. [Institute of Electron Technology, al. Lotników 32/46, 02-668 Warsaw (Poland); Taube, Andrzej [Institute of Electron Technology, al. Lotników 32/46, 02-668 Warsaw (Poland); Institute of Microelectronics & Optoelectronics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warsaw (Poland); Thuvander, Mattias; Law, Jia Yan [Department of Applied Physics, Chalmers University of Technology, Fysikgränd 3, SE-412 96 Gothenburg (Sweden); Kamińska, Eliana [Institute of Electron Technology, al. Lotników 32/46, 02-668 Warsaw (Poland); Stiller, Krystyna [Department of Applied Physics, Chalmers University of Technology, Fysikgränd 3, SE-412 96 Gothenburg (Sweden)

    2016-06-01

    In the following study we investigate the effect of the magnetron cathode current (I{sub c}) during reactive sputtering of In–Ga–Zn–O (a-IGZO) on thin-films nanostructure and transport properties. All fabricated films are amorphous, according to X-ray diffraction measurements. However, High Resolution Transmission Electron Microscopy revealed the a-IGZO fabricated at I{sub C} = 70 mA to contain randomly-oriented nanocrystals dispersed in amorphous matrix, which disappear in films deposited at higher cathode current. These nanocrystals have the same composition as the amorphous matrix. One can observe that, while I{sub C} is increased from 70 to 150 mA, the carrier mobility improves from μ{sub Hall} = 6.9 cm{sup 2}/Vs to μ{sub Hall} = 9.1 cm{sup 2}/Vs. Additionally, the increase of I{sub C} caused a reduction of the depletion region trap states density of the Ru–Si–O/In–Ga–Zn–O Schottky barrier. This enhancement in transport properties is attributed to the greater overlapping of s-orbitals of the film-forming cations caused by increased density, evidenced by X-ray reflectivity, at a fixed chemical composition, regardless nanostructure of thin films. - Highlights: • Magnetron cathode current (I{sub C}) controls the transport properties of In–Ga–Zn–O (IGZO). • Low I{sub C} results in IGZO films with nanocrystalline inclusions in amorphous matrix. • High I{sub C} reduces the number of trap states in depletion region of Schottky contacts.

  15. The phase diagram and transport properties of MgO from theory and experiment

    Science.gov (United States)

    Shulenburger, Luke

    2013-06-01

    Planetary structure and the formation of terrestrial planets have received tremendous interest due to the discovery of so called super-earth exoplanets. MgO is a major constituent of Earth's mantle, the rocky cores of gas giants and is a likely component of the interiors of many of these exoplanets. The high pressure - high temperature behavior of MgO directly affects equation of state models for planetary structure and formation. In this work, we examine MgO under extreme conditions using experimental and theoretical methods to determine its phase diagram and transport properties. Using plate impact experiments on Sandia's Z facility the solid-solid phase transition from B1 to B2 is clearly determined. The melting transition, on the other hand, is subtle, involving little to no signal in us-up space. Theoretical work utilizing density functional theory (DFT) provides a complementary picture of the phase diagram. The solid-solid phase transition is identified through a series of quasi-harmonic phonon calculations and thermodynamic integration, while the melt boundary is found using phase coexistence calculations. One issue of particular import is the calculation of reflectivity along the Hugoniot and the influence of the ionic structure on the transport properties. Particular care is necessary because of the underestimation of the band gap and attendant overestimation of transport properties due to the use of semi-local density functional theory. We will explore the impact of this theoretical challenge and its potential solutions in this talk. The integrated use of DFT simulations and high-accuracy shock experiments together provide a comprehensive understanding of MgO under extreme conditions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. DOE's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  16. Influence of metallic vapours on thermodynamic and transport properties of two-temperature air plasma

    Science.gov (United States)

    Zhong, Linlin; Wang, Xiaohua; Cressault, Yann; Teulet, Philippe; Rong, Mingzhe

    2016-09-01

    The metallic vapours (i.e., copper, iron, and silver in this paper) resulting from walls and/or electrode surfaces can significantly affect the characteristics of air plasma. Different from the previous works assuming local thermodynamic equilibrium, this paper investigates the influence of metallic vapours on two-temperature (2 T) air plasma. The 2 T compositions of air contaminated by Cu, Fe, and Ag are first determined based on Saha's and Guldberg-Waage's laws. The thermodynamic properties (including mass density, specific enthalpy, and specific heat) are then calculated according to their definitions. After determining the collision integrals for each pair of species in air-metal mixtures using the newly published methods and source data, the transport coefficients (including electrical conductivity, viscosity, and thermal conductivity) are calculated for air-Cu, air-Fe, and air-Ag plasmas with different non-equilibrium degree θ (Te/Th). The influences of metallic contamination as well as non-equilibrium degree are discussed. It is found that copper, iron, and silver exist mainly in the form of Cu2, FeO, and AgO at low temperatures. Generally, the metallic vapours increase mass density at most temperatures, reduce the specific enthalpy and specific heat in the whole temperature range, and affect the transport properties remarkably from 5000 K to 20 000 K. The effect arising from the type of metals is little except for silver at certain temperatures. Besides, the departure from thermal equilibrium results in the delay of dissociation and ionization reactions, leading to the shift of thermodynamic and transport properties towards a higher temperature.

  17. H(+)-coupled divalent metal-ion transporter-1: functional properties, physiological roles and therapeutics.

    Science.gov (United States)

    Shawki, Ali; Knight, Patrick B; Maliken, Bryan D; Niespodzany, Eric J; Mackenzie, Bryan

    2012-01-01

    Divalent metal-ion transporter-1 (DMT1) is a widely expressed, iron-preferring membrane transport protein. Animal models establish that DMT1 plays indispensable roles in intestinal nonheme-iron absorption and iron acquisition by erythroid precursor cells. Rare mutations in human DMT1 result in severe microcytic-hypochromic anemia. When we express DMT1 in RNA-injected Xenopus oocytes, we observe rheogenic Fe(2+) transport that is driven by the proton electrochemical potential gradient. In that same preparation, DMT1 also transports cadmium and manganese but not copper. Whether manganese metabolism relies upon DMT1 remains unclear but DMT1 contributes to the effects of overexposure to cadmium and manganese in some tissues. There exist at least four DMT1 isoforms that arise from variant transcription of the SLC11A2 gene. Whereas these isoforms display identical functional properties, N- and C-terminal variations contain cues that direct the cell-specific targeting of DMT1 isoforms to discrete subcellular compartments (plasma membrane, endosomes, and lysosomes). An iron-responsive element (IRE) in the mRNA 3'-untranslated region permits the regulation of some isoforms by iron status, and additional mechanisms by which DMT1 is regulated are emerging. Natural-resistance-associated macrophage protein-1 (NRAMP1)-the only other member of the mammalian SLC11 gene family-contributes to antimicrobial function by extruding from the phagolysosome divalent metal ions (e.g. Mn(2+)) that may be essential cofactors for bacteria-derived enzymes or required for bacterial growth. The principal or only intestinal nonheme-iron transporter, DMT1 is a validated therapeutic target in hereditary hemochromatosis (HHC) and other iron-overload disorders.

  18. Influence of Oxygen Vacancy on Transport Property in Perovskite Oxide Heterostructures

    Institute of Scientific and Technical Information of China (English)

    HAN Peng; JIN Kui-Juan; Lü Hui-Bin; JIA Jin-Feng; QIU Jie; HU Chun-Lian; YANG Guo-Zhen

    2009-01-01

    Effect of oxygen vacancy on transport property of perovskite microstructures is studied theoretically. Compared with calculated and measured I-V curves, it is revealed that electron conduction plays an important role in the oxygen nonstoichiometry perovskite heterostructures even with hole-doped or un-doped material due to the oxygen vacancies. In addition, a detailed understanding of the influence of oxygen vacancy concentration and temperature on the conduction characteristics of oxide heterojunction with both forward and reverse biases is obtained by calculation.

  19. Fast preparation and thermal transport property of TiCoSb-based half-Heusler compounds

    Institute of Scientific and Technical Information of China (English)

    Xie Wen-Jie; Tang Xin-Feng; Zhang Qing-Jie

    2007-01-01

    TiCoSb-based half-Heusler compounds with the substitution of Zr for Ti have been prepared quickly by combining high-energy ball milling method with spark plasma sintering technique, and their thermal transport properties have been investigated. With the increase of the concentration of Zr, the thermal conductivity of Ti1-xZrxCoSb compounds decreases significantly. Compared with the thermal conductivity of TiCoSb compound, that of Ti0.5Zr0.5CoSb decreases by 200% at 1000 K.

  20. Electron transport property of cobalt-centered porphyrin-armchair graphene nanoribbon (AGNR) junction

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Rajkumar; Sarkar, Utpal, E-mail: utpalchemiitkgp@yahoo.com [Department of Physics, Assam University, Silchar-788011 (India)

    2015-06-24

    We have investigated the electron transport properties of Cobalt-centered (Co-centered) porphyrin molecule using the density functional theory and non-equilibrium greens function method. Here we have reported transmission coefficient as well as current voltage characteristics of Co-centered porphyrine molecule connected between armchair graphene nanoribbons. It has been found that at low bias region i.e., 0 V to 0.3 V it does not contribute any current. Gradual increase of bias voltage results different order of magnitude of current in different bias region.

  1. Improved Electric Transport Properties of a Multi-wall carbon Nanotube

    Institute of Scientific and Technical Information of China (English)

    李秋红; 王太宏

    2003-01-01

    Up to now quantized conductance of the carbon nanotube has only been observed by replacing the tip of a scanning probe microscope with the tube and putting the other end of the tube in a liquid metal [Science 280(1998) 1744]. Probably cleaning the tube by the liquid metal has improved its quality and gives rise to the quantized conductance. We report on a new method to improve the electric transport properties of a single multi-wall carbon nanotube by Joule heating. Our experiment indicates that the conductance of the tube can be greatly improved just by repeated scanning the bias voltage in vacuum.

  2. Study of structural and electronic transport properties of Ce-doped LaMnO3

    Indian Academy of Sciences (India)

    Shahid Husain; R J Choudhary; Ravi Kumar; S I Patil; J P Srivastava

    2002-05-01

    The structural and electronic transport properties of La1-CeMnO3 (=0.0-1.0) have been studied. All the samples exhibit orthorhombic crystal symmetry and the unit cell volume decreases with Ce doping. They also make a metal–insulator transition (MIT) and transition temperature increases with increase in Ce concentration up to 50% doping. The system La0.5Ce0.5MnO3 also exhibits MIT instead of charge-ordered state as observed in the hole doped systems of the same composition.

  3. Atomic transport properties of Ag xSn 1-x liquid binary alloys

    Science.gov (United States)

    Bhuiyan, E. H.; Ziauddin Ahmed, A. Z.; Bhuiyan, G. M.; Shahjahan, M.

    2008-05-01

    Atomic transport properties, in particular the shear viscosity and diffusion constants for Ag xSn 1-x less simple liquid binary alloys are theoretically studied from a statistical mechanical theory called the distribution function method. The essential ingredients of this theory are the interionic interaction and the pair distribution function for hard spheres. The interionic interaction are described from a local pseudopotential model and the effective hard sphere diameters are obtained from the thermodynamic perturbative method known as the linearized Weeks-Chandler-Andersen (LWCA). Results of calculations for shear viscosities agree well with the available experimental data.

  4. Abrasion properties of homogenous and blended fill materials during pressure hydraulic transport

    Energy Technology Data Exchange (ETDEWEB)

    Turchaninov, S.P.

    1978-03-01

    A description is given of tests conducted to determine the abrasive properties of small and large-grain free-flowing fill materials during hydraulic transport of the materials under pressure. Data are given on the size, density, abrasiveness of various sized varieties of rock, sand, and blends comprising homogenous materials, simple and complex mixtures, and on the physical characteristics of various fill materials in relation to the trafficability and parameters of pipelines. Technical specifications are given for fill steel pipes. The study indicates that the durability of hydraulic fill pipelines largely depends on the abrasiveness of the fill materials. 3 references, 2 figures, 2 tables.

  5. Structural and transport properties of orthorhombic GdMnO3

    Science.gov (United States)

    Modi, Anchit; Thakur, Rajesh K.; Thakur, Rasna; Gaur, N. K.; Kaurav, N.; Okram, G. S.

    2013-06-01

    We report structural and transport properties of the polycrystalline orthorhombic GdMnO3 compound synthesized by using conventional solid state reaction method. The XRD pattern reveals the single phase formation of the reported compound in orthorhombic crystal structure with space group Pbnm (JCPDS: 25-0337). The temperature dependent resistivity study indicates the highly resistive nature of the compound especially in the low temperature region. The effect of low temperature magnetic ordering can be clearly understood from the resistivity versus temperature plot. The calculated activation energy by using Arrhenius equation fitting are found slightly lesser than the reported value which indicates the lesser dense nature of the prepared compound.

  6. Modelling the optical properties of aerosols in a chemical transport model

    Science.gov (United States)

    Andersson, E.; Kahnert, M.

    2015-12-01

    According to the IPCC fifth assessment report (2013), clouds and aerosols still contribute to the largest uncertainty when estimating and interpreting changes to the Earth's energy budget. Therefore, understanding the interaction between radiation and aerosols is both crucial for remote sensing observations and modelling the climate forcing arising from aerosols. Carbon particles are the largest contributor to the aerosol absorption of solar radiation, thereby enhancing the warming of the planet. Modelling the radiative properties of carbon particles is a hard task and involves many uncertainties arising from the difficulties of accounting for the morphologies and heterogeneous chemical composition of the particles. This study aims to compare two ways of modelling the optical properties of aerosols simulated by a chemical transport model. The first method models particle optical properties as homogeneous spheres and are externally mixed. This is a simple model that is particularly easy to use in data assimilation methods, since the optics model is linear. The second method involves a core-shell internal mixture of soot, where sulphate, nitrate, ammonia, organic carbon, sea salt, and water are contained in the shell. However, by contrast to previously used core-shell models, only part of the carbon is concentrated in the core, while the remaining part is homogeneously mixed with the shell. The chemical transport model (CTM) simulations are done regionally over Europe with the Multiple-scale Atmospheric Transport and CHemistry (MATCH) model, developed by the Swedish Meteorological and Hydrological Institute (SMHI). The MATCH model was run with both an aerosol dynamics module, called SALSA, and with a regular "bulk" approach, i.e., a mass transport model without aerosol dynamics. Two events from 2007 are used in the analysis, one with high (22/12-2007) and one with low (22/6-2007) levels of elemental carbon (EC) over Europe. The results of the study help to assess the

  7. Theoretical investigation of the thermoelectric transport properties of BaSi2

    Institute of Scientific and Technical Information of China (English)

    Peng Hua; Wang Chun-Lei; Li Ji-Chao; Zhang Rui-Zhi; Wang Hong-Chao; Sun Yi

    2011-01-01

    The full-potential linear augmented plane wave method based on density functional theory is employed to investigate the electronic structure of BaSi2 With the constant relaxation time and rigid band approximation, the electrical conductivity, Seebeck coefficient and figure of merit are calculated by using Boltzmann transport theory, further evaluated as a function of carrier concentration. We find that the Seebeck coefficient is more anisotropic than electrical conductivity. The figure of merit of BaSi2 is predicted to be quite high at room temperature, implying that optimal doping may be an effective way to improve thermoelectric properties.

  8. Transport Properties near Quantum Critical Point in 2D Hubbard Model

    Science.gov (United States)

    Chen, Kuang-Shing; Pathak, Sandeep; Yang, Shuxiang; Su, Shi-Quan; Galanakis, Dimitris; Mikelsons, Karlis; Moreno, Juana; Jarrell, Mark

    2011-03-01

    We obtain high quality estimates of the self energy Σ (K , ω) by direct analytic continuation of Σ (K , iωn) obtained from Continuous-Time Quantum Monte Carlo. We use these results to investigate the transport properties near the quantum critical point found in the 2D Hubbard model at finite doping. Resistivity, thermal conductivity, Wiedemann-Franz Law, and thermopower are examined in the Fermi liquid, Marginal Fermi liquid (MFL), and pseudo-gap regions. Σ (k , ω) with k along the nodal direction displays temperature-dependent scaling similar to that seen in the experiment. A next-nearest neighbor hopping tOISE-0730290.

  9. Electronic transport properties of an (8,0) carbon/silicon-carbide nanotube heterojunction

    Institute of Scientific and Technical Information of China (English)

    Liu Hongxia; Zhang Heming; Zhang Zhiyong

    2009-01-01

    A two-probe system of the heterojunction formed by an (8,0) carbon nanotube(CNT) and an (8,0)silicon carbide nanotube (SiCNT) was established based on its optimized structure. By using a method combining nonequilibrium Green's function (NEGF) with density functional theory (DFT), the transport properties of the heterojunction were investigated. Our study reveals that the highest occupied molecular orbital (HOMO) has a higher electron density on the CNT section and the lowest unoccupied molecular orbital (LUMO) mainly concentrates on the interface and the SiCNT section. The positive and negative threshold voltages are1.8 and-2.2 V, respectively.

  10. Resilient quasiparticles in Ruthenates: transport properties within LDA+DMFT method

    Science.gov (United States)

    Deng, Xiaoyu; Haule, Kristjan; Kotliar, Gabriel

    2015-03-01

    Many Rutheniums are strongly correlated metals with Fermi Liquid behavior found only a small temperature scale. Non-Fermi signatures appear in both their resistivity and optical conductivity. We study the transport properties of a set of Ruthenates within first principle methods in combination with dynamical mean field theory and find reasonable agreement with experimental findings. The non-Fermi-liquid features are attributed to the temperature dependence of resilient quasiparticles, which survives above the Fermi liquid temperature scale and exhibits a strong temperature dependence in their effective mass enhancement and scattering rate.

  11. Effect of Secondary Doping Using Sorbitol on Structure and Transport Properties of PEDOT-PSS Thin Films

    Science.gov (United States)

    Khasim, Syed; Pasha, Apsar; Roy, Aashish S.; Parveen, Ameena; Badi, Nacer

    2017-03-01

    Poly(3,4-ethylene dioxythiophene):poly(styrenesulphonate) (PEDOT-PSS) in the recent past has emerged as one of the most fascinating conducting polymers for many device applications. The unique feature of PEDOT-PSS is its transparency in the entire visible spectrum with excellent thermal stability. The PEDOT-PSS as prepared as an aqueous dispersion has very low conductivity, and it hinders the performance of a device. In this work we report the conductivity enhancement of PEDOT-PSS thin films through secondary doping using a polar organic solvent such as sorbitol. The mechanism of conductivity enhancement was studied through various physical and chemical characterizations. The effect of sorbitol concentration on structure and transport properties of PEDOT-PSS thin films was investigated in detail. The structural and morphological modifications in PEDOT-PSS due to the addition of sorbitol was studied through Fourier transform spectroscopy, Ultra Violet-visible spectroscopy, theromogravimetric analysis, scanning electron microscopy and atomic force microscopy. The interactions resulting from conformational changes of PEDOT chains that changes from coiled to linear structure due to the sorbitol treatment significantly improves the conductivity of PEDOT-PSS films. The secondary doping of sorbitol reduces the energy barrier that facilitates the charge carrier hopping leading to enhanced conductivity. We have observed that the conductivity of PEDOT-PSS thin films was increased by two fold due to sorbitol treatment when compared to conductivity of pure PEDOT-PSS. We have carried out detailed analysis of dielectric parameters of sorbitol-treated PEDOT-PSS films and found that sorbitol treatment has a significant effect on various dielectric attributes of PEDOT-PSS films. Hence, secondary doping using sorbitol could be a useful way to effectively tailor the conductivity and dielectric properties of PEDOT-PSS thin films that can be used as flexible electrodes in

  12. Insights into molecular properties of the human monocarboxylate transporter 8 by combining functional with structural information

    Directory of Open Access Journals (Sweden)

    Kleinau Gunnar

    2011-08-01

    Full Text Available Abstract Background The monocarboxylate transporter 8 (MCT8 is a member of the major facilitator superfamily (MFS and transports specificly iodothyronines. MCT8 mutations are the underlying cause of a syndrome of severe X-linked psychomotor retardation known as the Allan-Herndon-Dudley syndrome. This syndrome is characterized by abnormally high T3, low/normal T4 serum levels and slightly elevated serum TSH. To date, more than 25 pathogenic mutations in hMCT8 are known and they are valuable indicators of important regions for structural and functional MCT8 properties. Methods We designed a structural human MCT8 model and studied reported pathogenic missense mutations with focus on the estimation of those amino acid positions which are probably sensitive for substrate transport. Furthermore, assuming similarities between determinants of T3 binding observed in the published crystal structure of the thyroid hormone receptor beta occupied by its ligand T3 and the structural MCT8 model, we explore potential T3 binding sites in the MCT8 substrate channel cavity. Results We found that all known pathogenic missense mutations are located exclusively in the transmembrane helices and to a high degree at conserved residues among the MCT family. Furthermore, mutations either of or to prolines/glycines are located mainly at helices 9-12 and are expected to cause steric clashes or structural misfolding. In contrast, several other mutations are close to the potential substrate channel and affected amino acids are likely involved in the switching mechanism between different transporter conformations. Finally, three potential substrate binding sites are predicted for MCT8. Conclusions Naturally occurring mutations of MCT8 provide molecular insights into protein regions important for protein folding, substrate binding and the switching mechanism during substrate transport. Future studies guided by this information should help to clarify structure

  13. Electrical transport measurements and emission properties of freestanding single crystalline CVD diamond samples

    Energy Technology Data Exchange (ETDEWEB)

    Deferme, W.; Bogdan, A.; Bogdan, G. [Hasselt University, Institute for Materials Research (IMO), Diepenbeek (Belgium); Haenen, K.; Ceuninck, W. de [Hasselt University, Institute for Materials Research (IMO), Diepenbeek (Belgium); IMEC vzw, Division IMOMEC, Diepenbeek (Belgium); Nesladek, M. [Hasselt University, Institute for Materials Research (IMO), Diepenbeek (Belgium); IMEC vzw, Division IMOMEC, Diepenbeek (Belgium); CEA/Saclay, LIST (CEA-Recherche Technologique)/DETECS/SSTM/LTD, Gif-sur-Yvette (France)

    2007-09-15

    In this work time-of-flight (TOF) measurements are performed on freestanding single crystalline (100) CVD diamond layers with different surface terminations. The transit properties and electron and hole mobility are measured for completely oxidised and completely hydrogenated diamonds. The results clearly show that the different terminations of the diamond surface have an influence on the electrical transport properties. Furthermore, evidence is given that oxygen-induced surface states influence the TOF spectra. Light emission at 235 nm and around 430 nm is observed when applying a pulsed electric field on the diamond. The small peak at 235 nm is attributed to free exciton recombination while the broad band at 430 nm is contributed to A-band luminescence. Emission spectra at voltages as high as 1.4 V/{mu}m are given and compared. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Identifying the Critical Links in Road Transportation Networks: Centrality-based approach utilizing structural properties

    Energy Technology Data Exchange (ETDEWEB)

    Chinthavali, Supriya [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-04-01

    Surface transportation road networks share structural properties similar to other complex networks (e.g., social networks, information networks, biological networks, and so on). This research investigates the structural properties of road networks for any possible correlation with the traffic characteristics such as link flows those determined independently. Additionally, we define a criticality index for the links of the road network that identifies the relative importance in the network. We tested our hypotheses with two sample road networks. Results show that, correlation exists between the link flows and centrality measures of a link of the road (dual graph approach is followed) and the criticality index is found to be effective for one test network to identify the vulnerable nodes.

  15. Calculation of electrical transport properties and electron entanglement in inhomogeneous quantum wires

    Directory of Open Access Journals (Sweden)

    A A Shokri

    2013-10-01

    Full Text Available In this paper, we have investigated the spin-dependent transport properties and electron entanglement in a mesoscopic system, which consists of two semi-infinite leads (as source and drain separated by a typical quantum wire with a given potential. The properties studied include current-voltage characteristic, electrical conductivity, Fano factor and shot noise, and concurrence. The calculations are based on the transfer matrix method within the effective mass approximation. Using the Landauer formalism and transmission coefficient, the dependence of the considered quantities on type of potential well, length and width of potential well, energy of transmitted electron, temperature and the voltage have been theoretically studied. Also, the effect of the above-mentioned factors has been investigated in the nanostructure. The application of the present results may be useful in designing spintronice devices.

  16. Electrical transport properties of nanocrystalline nonstoichiometric nickel ferrite at and above room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Choudhury, S. [Department of Physics, National Institute of Technology, Durgapur 713209, West Bengal (India); Sinha, M. [Department of Physics, University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India); Mandal, M.K. [Department of Physics, National Institute of Technology, Durgapur 713209, West Bengal (India); Pradhan, S.K. [Department of Physics, University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India); Meikap, A.K., E-mail: meikapnitd@yahoo.com [Department of Physics, National Institute of Technology, Durgapur 713209, West Bengal (India)

    2015-01-15

    The electrical transport properties of chemically prepared nanocrystalline nonstoichiometric nickel ferrite followed by high energy ball milling have been reported. The dc conductivity of the samples shows semiconducting behavior. The adiabatic small polaron model is most suitable for analyzing the dc conductivity at higher temperature, whereas at lower temperature Schnakenberg acoustical one phonon assisted hopping model is suitable. The frequency dependent conductivity has been described by power law σ{sup /}(f)∝f{sup s} and a maximum has been observed in the temperature behavior of ‘s’. The dielectric properties of the samples have been explained in terms of electric modulus vector. Both dc and ac activation energy have been measured for different samples. The metallic electrode and semiconductor junction formed Schottky diode and the diode parameters have been extracted from the capacitance–voltage characteristics.

  17. Effect of morphology on the electrical transport properties of polyaniline films for electronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Hardaker, S.S.; Eaiprasertsak, K.; Yon, J.; Gregory, R.V.; Tessema, G.X.

    1998-07-01

    Although it is well known that the oxidation state of polyaniline is an important characteristic, there are few reports of its influence on the development of morphology and electrical properties in fibers and films. In this work, differential scanning calorimetry is used in conjunction with measurements of temperature dependence of conductivity and thermoelectric power to elucidate the intimate relationship between structure and properties. By increasing the amount of chemical reduction of polyaniline solutions, films are repaired which exhibit a thermal transition between 300 and 385 C, indicative of melting. Increasing the chemical reduction also increases the conductivity of iodine doped films. The most reduced film exhibited a semiconductor transport mechanism, while the other films could be modeled with a quasi-one dimensional variable range hopping mechanism. The temperature dependence of conductivity also showed increasing order for increasing reduction, consistent with the DSC results.

  18. Equation of state and transport properties of silicates under extreme conditions

    Science.gov (United States)

    Qi, T.; Hamel, S.

    2014-12-01

    Understanding the physical properties of silicates under high temperature and pressure is fundamental to an accurate description of planetary interiors and evolution models. For example, earth's mantle is a rocky silicate shell constituting about 84% of Earth's volume. Possible chemical compositions include SiO2 and some other silicates such as MgSiO3 and CaSiO3. Moreover, Moon forming scenarios often invoke giant impacts between silicate-rich objects.Similarly, the existence of a rocky core or mantle with silicate as the major component is frequently assumed in models of giant planets, such as Jupiter or Saturn and Uranus and Neptune.Consequently, constructing planetary interior and evolution models requires knowledge of silicate's equation of state and its optical and transport properties at high pressures and temperatures.

  19. Magnetic structure and magnetic transport properties of graphene nanoribbons with sawtooth zigzag edges.

    Science.gov (United States)

    Wang, D; Zhang, Z; Zhu, Z; Liang, B

    2014-12-23

    The magnetic structure and magnetic transport properties of hydrogen-passivated sawtooth zigzag-edge graphene nanoribbons (STGNRs) are investigated theoretically. It is found that all-sized ground-state STGNRs are ferromagnetic and always feature magnetic semiconductor properties, whose spin splitting energy gap E(g) changes periodically with the width of STGNRs. More importantly, for the STGNR based device, the dual spin-filtering effect with the perfect (100%) spin polarization and high-performance dual spin diode effect with a rectification ratio about 10(10) can be predicted. Particularly, a highly effective spin-valve device is likely to be realized, which displays a giant magnetoresistace (MR) approaching 10(10)%, which is three orders magnitude higher than the value predicted based on the zigzag graphene nanoribbons and six orders magnitude higher than previously reported experimental values for the MgO tunnel junction. Our findings suggest that STGNRs might hold a significant promise for developing spintronic devices.

  20. Electrical transport and magnetic properties of epitaxial LSMO films grown on STO substrates

    Science.gov (United States)

    Yuan, Wei; Zhao, Yuelei; Su, Tang; Song, Qi; Han, Wei; Shi, Jing

    2015-03-01

    La0.7Sr0.3MnO3 (LSMO) is a very attractive material for spintronics due to its half-metallic ferromagnetic properties. The LSMO films are epitaxially grown on STO (100) substrates using pulsed laser deposition. The effects of substrate temperature, laser power, oxygen pressure, and annealing on the LSMO growth are systematically investigated by the reflection high energy electron diffraction and atomic force microscopy. Under the optimized growth condition, we have achieved atomically flat LSMO thin films with a wide terrace width of more than 5 micro-meters. The electrical transport properties of LSMO thin films of various thicknesses ranging from 8 to 20 monolayers are studied by measuring the resistivity as a function of temperature. We find that the growth condition plays an important role in the critical film thickness for the metal-insulator transition and the Curie temperature. The Ministry of Science and Technology of China.

  1. Equilibrium and Transport Properties of Primary, Secondary and Tertiary Amines by Molecular Simulation

    Directory of Open Access Journals (Sweden)

    Orozco Gustavo A.

    2014-09-01

    Full Text Available Using molecular simulation techniques such as Monte Carlo (MC and molecular dynamics (MD, we present several simulation results of thermodynamic and transport properties for primary, secondary and tertiary amines. These calculations are based on a recently proposed force field for amines that follows the Anisotropic United Atom approach (AUA. Different amine molecules have been studied, including n-ButylAmine, di-n-ButylAmine, tri-n-ButylAmine and 1,4-ButaneDiAmine for primary, secondary, tertiary and multi-functional amines respectively. For the transport properties, we have calculated the viscosity coefficients as a function of temperature using the isothermal-isobaric (NPT ensemble. In the case of the pure components, we have investigated different thermodynamic properties using NVT Gibbs ensemble simulations such as liquid-vapor phase equilibrium diagrams, vaporization enthalpies, vapor pressures, normal boiling points, critical temperatures and critical densities. We have also calculated the excess enthalpies for water-n-ButylAmine and n-heptane-n-ButylAmine mixtures using Monte Carlo simulations in the NPT ensemble. In addition, we present the calculation of liquid-vapor surface tensions of n-ButylAmine using a two-phase NVT simulation as well as the radial distribution functions. Finally, we have investigated the physical Henry constants of nitrous oxide (N2O and nitrogen (N2 in an aqueous solutions of n-ButylAmine. In general, we found a good agreement between the available experimental information and our simulation results for all the studied properties, ratifying the predictive capability of the AUA force field for amines.

  2. Pollution of soils and ecosystems by a permanent toxic organochlorine pesticide: chlordecone—numerical simulation of allophane nanoclay microstructure and calculation of its transport properties

    Directory of Open Access Journals (Sweden)

    Thierry Woignier

    2015-06-01

    Full Text Available Pest control technology was introduced into the tropics without considering the specificity of their ecosystems and the risk of pollution was underestimated. Some volcanic soils (andosols contain nanoclay (allophane with a unique structure and porous properties compared to crystalline clays. Andosols are characterized by large pore volume and pore size distribution, a high specific surface area, and a fractal structure. These soils are more polluted than the other kinds of tropical soils but release less pollutants (chlordecone to water and plants. The literature shows that the allophane microstructure favors accumulation and sequestration of chlordecone, an organochlorine pesticide, in andosols.We used a numerical model to simulate the structure of allophane aggregates. The algorithm is based on a cluster-cluster aggregation model. From the simulated data, we derived the structural features, pore volume and tortuosity, and its transport properties, hydraulic conductivity and diffusion. We show that transport properties decrease because of the presence of allophane. We propose that low hydraulic conductivity and diffusion are important parameters to explain the high concentrations and trapping of pollutants in andosols.

  3. Theoretical modeling and experimental validation of transport and separation properties of carbon nanotube electrospun membrane distillation

    KAUST Repository

    Lee, Jung-Gil

    2016-12-27

    Developing a high flux and selective membrane is required to make membrane distillation (MD) a more attractive desalination process. Amongst other characteristics membrane hydrophobicity is significantly important to get high vapor transport and low wettability. In this study, a laboratory fabricated carbon nanotubes (CNTs) composite electrospun (E-CNT) membrane was tested and has showed a higher permeate flux compared to poly(vinylidene fluoride-co-hexafluoropropylene) (PH) electrospun membrane (E-PH membrane) in a direct contact MD (DCMD) configuration. Only 1% and 2% of CNTs incorporation resulted in an enhanced permeate flux with lower sensitivity to feed salinity while treating a 35 and 70 g/L NaCl solutions. Experimental results and the mechanisms of E-CNT membrane were validated by a proposed new step-modeling approach. The increased vapor transport in E-CNT membranes could not be elucidated by an enhancement of mass transfer only at a given physico-chemical properties. However, the theoretical modeling approach considering the heat and mass transfers simultaneously enabled to explain successfully the enhanced flux in the DCMD process using E-CNT membranes. This indicates that both mass and heat transfers improved by CNTs are attributed to the enhanced vapor transport in the E-CNT membrane.

  4. System of elastic hard spheres which mimics the transport properties of a granular gas.

    Science.gov (United States)

    Santos, Andrés; Astillero, Antonio

    2005-09-01

    The prototype model of a fluidized granular system is a gas of inelastic hard spheres (IHS) with a constant coefficient of normal restitution alpha. Using a kinetic theory description we investigate the two basic ingredients that a model of elastic hard spheres (EHS) must have in order to mimic the most relevant transport properties of the underlying IHS gas. First, the EHS gas is assumed to be subject to the action of an effective drag force with a friction constant equal to half the cooling rate of the IHS gas, the latter being evaluated in the local equilibrium approximation for simplicity. Second, the collision rate of the EHS gas is reduced by a factor (1/2)(1+alpha), relative to that of the IHS gas. Comparison between the respective Navier-Stokes transport coefficients shows that the EHS model reproduces almost perfectly the self-diffusion coefficient and reasonably well the two transport coefficients defining the heat flux, the shear viscosity being reproduced within a deviation less than 14% (for alpha > or = 0.5). Moreover, the EHS model is seen to agree with the fundamental collision integrals of inelastic mixtures and dense gases. The approximate equivalence between IHS and EHS is used to propose kinetic models for inelastic collisions as simple extensions of known kinetic models for elastic collisions.

  5. Confined Water Determines Transport Properties of Guest Molecules in Narrow Pores.

    Science.gov (United States)

    Phan, Anh; Cole, David R; Weiß, R Gregor; Dzubiella, Joachim; Striolo, Alberto

    2016-08-23

    We computed the transport of methane through 1 nm wide slit-shaped pores carved out of solid substrates. Models for silica, magnesium oxide, and alumina were used as solid substrates. The pores were filled with water. The results show that the methane permeability through the hydrated pores is strongly dependent on the solid substrate. Detailed analysis of the simulated systems reveals that local properties of confined water, including its structure, and more importantly, evolution of solvation free energy and hydrogen bond structure are responsible for the pronounced differences observed. The simulations are extended to multicomponent systems representative of natural gas, containing methane, ethane, and H2S. The results show that all pores considered have high affinity for H2S, moderate affinity for methane, and low affinity for ethane. The H2S/methane transport selectivity through the hydrated alumina pore is comparable, or superior, to that reported for existing commercial membranes. A multiscale approach was then implemented to demonstrate that a Smoluchowski one-dimensional model is able to reproduce the molecular-level results for short pores when appropriate values for the local self-diffusion coefficients are used as input parameters. We propose that the model can be extended to predict methane transport through uniform hydrated pores of macroscopic length. When verified by experiments, our simulation results could have important implications in applications such as natural gas sweetening and predictions of methane migration through hydraulically fractured shale formations.

  6. Ion Transport and Structural Properties of Polymeric Electrolytes and Ionic Liquids from Molecular Dynamics Simulations

    Science.gov (United States)

    Borodin, Oleg

    2010-03-01

    Molecular dynamics simulations are well suited for exploring electrolyte structure and ion transport mechanisms on the nanometer length scale and the nanosecond time scales. In this presentation we will describe how MD simulations assist in answering fundamental questions about the lithium transport mechanisms in polymeric electrolytes and ionic liquids. In particular, in the first part of the presentation the extent of ion aggregation, the structure of ion aggregates and the lithium cation diffusion in binary polymeric electrolytes will be compared with that of single-ion conducting polymers. In the second part of the talk, the lithium transport in polymeric electrolytes will be compared with that of three ionic liquids ( [emim][FSI] doped with LiFSI , [pyr13][FSI] doped with LiFSI, [emim][BF4] doped with LiBF4). The relation between ionic liquid self-diffusion, conductivity and thermodynamic properties will be discussed in details. A number of correlations between heat of vaporization Hvap, cation-anion binding energy (E+/-), molar volume (Vm), self-diffusion coefficient (D) and ionic conductivity for 29 ionic liquids have been investigated using MD simulations. A significant correlation between D and Hvap has been found, while best correlation was found for -log((D Vm)) vs. Hvap+0.28E+/-. A combination of enthalpy of vaporization and a fraction of the cation-anion binding energy was suggested as a measure of the effective cohesive energy for ionic liquids.

  7. Analysis of current transport properties in nonpolar a-plane ZnO-based Schottky diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hogyoung [Seoul National University of Science and Technology, Seoul (Korea, Republic of); Kim, Haeri; Kim, Dongwook [Ewha Womans University, Seoul (Korea, Republic of)

    2014-09-15

    Using current-voltage (I - V) measurements, we investigated the temperature-dependent transport properties in Ag/nonpolar a-plane ZnO Schottky diodes. The bias-dependent ideality factors were altered by the different temperatures and showed a hump at lower temperatures. The series resistance of the diode depended on the temperatures, which was related to the number of free carriers contributing to the series resistance. For high forward bias, the slope m obtained from the lnI - lnV curves decreased with increasing temperature, assuring the space-charge-limited-current (SCLC) model controlled by an exponential distribution of traps. The reverse-biased current transport was associated with the Schottky effect, with a thermally-assisted tunneling for lower voltages and the Poole-Frenkel effect for higher voltages. The density of localized states (N{sub t}) was obtained by applying the theory of SCLC transport, which yielded a N{sub t} value of 8.32 x 10{sup 11} eV{sup -1}cm{sup -3}.

  8. Understanding the structure, dynamics, and mass transport properties of self assembling peptide hydrogels for injectable, drug delivery applications

    Science.gov (United States)

    Branco, Monica Cristina

    Advances in biotechnology have led to the rapid development of small protein and antibody therapeutics. However, several limitations remain in the preparation and delivery of these drugs due to the susceptibility of proteins to degrade during storage and upon administration. To address this problem, hydrogels have been used as delivery devices for these protein drugs. We have designed a class of self-assembling peptides, MAX1 and MAX8, that undergo triggered hydrogelation in response to physiological pH and salt conditions (pH 7.4, 150 mM NaCl). These peptides adopt a random coil conformation in aqueous pH 7.4 solutions and are freely soluble. However, when a physiological relevant concentration of NaCl (150 mM) is added, the peptides fold into a beta-hairpin confirmation, and subsequently, self-assemble to form a rigid hydrogel stabilized by non-covalent cross-links. For these peptides, it is possible to control the folding and assembly kinetics to form hydrogels with different mechanical rigidities. These changes affect the porous morphology (i.e., mesh size) within the hydrogel system, and subsequently influence the rate of macromolecular diffusion within the peptide fibrillar network. Another unique characteristic of these hydrogels is that under applied shear, the hydrogel will shear-thin into a low-viscosity gel; however, the gel quickly resets and recovers its initial mechanical rigidity after the applied shear is removed. This property allows hydrogels encapsulating therapeutics to be administered via syringe to target sites for eventual delivery. The objective of this thesis work is to investigate the potential of MAX1 and MAX8 hydrogels as controlled release, drug delivery vehicles for macromolecular therapeutics. First, the differences in the folding and self assembly kinetics, as well as the resultant material properties, of MAX1 and MAX8 are assessed to yield a physical model of the nanoscale topology and dynamics of the self-assembled peptide

  9. Field scale variability of solute transport parameters and related soil properties

    Directory of Open Access Journals (Sweden)

    B. Lennartz

    1997-01-01

    Full Text Available The spatial variability of transport parameters has to be taken into account for a reliable assessment of solute behaviour in natural field soils. Two field sites were studied by collecting 24 and 36 small undisturbed soil columns at an uniform grid of 15 m spacing. Displacement experiments were conducted in these columns with bromide traced water under unsaturated steady state transport conditions. Measured breakthrough curves (BTCs were evaluated with the simple convective-dispersive equation (CDE. The solute mobility index (MI calculated as the ratio of measured to fitted pore water velocity and the dispersion coefficient (D were used to classify bromide breakthrough behaviour. Experimental BTCs were classified into two groups: type I curves expressed classical solute behaviour while type II curves were characterised by the occurrence of a bromide concentration maximum before 0.35 pore volumes of effluent (MI<0.35 resulting from preferential flow conditions. Six columns from site A and 8 from site B were identified as preferential. Frequency distributions of the transport parameters (MI and D of both sites were either extremely skewed or bimodal. Log-transformation did not lead to a normal distribution in any case. Contour maps of bromide mass flux at certain time steps indicated the clustering of preferential flow regions at both sites. Differences in the extent of preferential flow between sites seemed to be governed by soil structure. Linear cross correlations among transport parameters and independently measured soil properties revealed relations between solute mobility and volumetric soil water content at time of sampling, texture and organic carbon content. The volumetric field soil water content, a simple measure characterising the soil hydraulic behaviour at the sampling location, was found to be a highly sensitive parameter with respect to solute mobility and preferential flow situations. Almost no relation was found between solute

  10. Magnetoelectric and transport properties of (GaMn)Sb thin films: A ferrimagnetic phase in dilute alloys

    Science.gov (United States)

    Calderón, Jorge A.; Mesa, F.; Dussan, A.

    2017-02-01

    We studied the electrical, magnetic, and transport properties of (GaMn)Sb thin films fabricated by the direct current magnetron co-sputtering method. Using X-ray powder diffraction measurements, we identified the presence of ferrimagnetic (Mn2Sb) and ferromagnetic (Mn2Sb2) phases within the films. We also measured the magnetization of the films versus an applied magnetic field as well as their hysteresis curves at room temperature. We determined the electrical and transport properties of the films through temperature-dependent resistivity measurements using the Van Der Pauw method. The main contribution to the transport process was variable range hopping. Hopping parameters were calculated using percolation theory and refined using the diffusional model. In addition, we determined that all samples had p type semiconductor behavior, that there was an increase in the density of localized states near the Fermi level, and that the binary magnetic phases influenced the electrical properties and transport mechanisms.

  11. Analysis on Topological Properties of Dalian Hazardous Materials Road Transportation Network

    Directory of Open Access Journals (Sweden)

    Pengyun Chong

    2015-01-01

    Full Text Available To analyze the topological properties of hazardous materials road transportation network (HMRTN, this paper proposed two different ways to construct the cyberspace of HMRTN and constructed their complex network models, respectively. One was the physical network model of HMRTN based on the primal approach and the other was the service network model of HMRTN based on neighboring nodes. The two complex network models were built by using the case of Dalian HMRTN. The physical network model contained 154 nodes and 238 edges, and the statistical analysis results showed that (1 the cumulative node degree of physical network was subjected to exponential distribution, showing the network properties of random network and that (2 the HMRTN had small characteristic path length and large network clustering coefficient, which was a typical small-world network. The service network model contained 569 nodes and 1318 edges, and the statistical analysis results showed that (1 the cumulative node degree of service network was subjected to power-law distribution, showing the network properties of scale-free network and that (2 the relationship between nodes strength and their descending order ordinal and the relationship between nodes strength and cumulative nodes strength were both subjected to power-law distribution, also showing the network properties of scale-free network.

  12. Theoretical study of Kondo effect and related transport properties in topological insulator systems

    Science.gov (United States)

    Xin, Xianhao

    This thesis presents theoretical studies of the Kondo effect and related transport properties in topological insulator systems. The thesis mainly covers two topics: the Kondo effect on the surface of a bulk topological insulator material and the Kondo effect in a topological insulator quantum dot. Other relevant background knowledge and theoretical techniques for the transport calculations are also discussed in the thesis. For the first topic, we investigate the role of magnetic impurities in the transport properties of a three-dimensional topological insulator's surface states. First, we combine the second-order perturbation theory and the Boltzmann transport equation to calculate the magnetically induced resistivity in a topological insulator. Our result shows a non-perturbative behavior when conduction electrons and magnetic impurities' spins are antiferromagnetically coupled. The surface resistivity is found to display an oscillatory rather than isotropic behavior compared to the conventional Kondo effect. Both the variational method and renormalization group (RG) analysis are employed to compute the Kondo temperature, through which the non-perturbative behavior is confirmed. We further study the RG flows and demonstrate that the RG trajectories eventually flow into a strong coupling regime if the coupling is antiferromagnetic. This work is motivated by the recent transport experiments, in which surface currents were detected in topological insulators. The calculation is shown to be qualitatively consistent with the low temperature dip observed in the experimental R - T curve, and it might be one of the possible origins of the dip. For the second main topic, we investigate theoretically the nonequilibrium transport properties of a topological insulator quantum dot (TIQD) in the Coulomb blockade and Kondo regime. An Anderson impurity model is applied to a TIQD system coupled to two external leads, and we show that the model realizes the spin-orbital Kondo effect

  13. Ionic structures and transport properties of hot dense W and U plasmas

    Science.gov (United States)

    Hou, Yong; Yuan, Jianmin

    2016-10-01

    We have combined the average-atom model with the hyper-netted chain approximation (AAHNC) to describe the electronic and ionic structure of uranium and tungsten in the hot dense matter regime. When the electronic structure is described within the average-atom model, the effects of others ions on the electronic structure are considered by the correlation functions. And the ionic structure is calculated though using the hyper-netted chain (HNC) approximation. The ion-ion pair potential is calculated using the modified Gordon-Kim model based on the electronic density distribution in the temperature-depended density functional theory. And electronic and ionic structures are determined self-consistently. On the basis of the ion-ion pair potential, we perform the classical (CMD) and Langevin (LMD) molecular dynamics to simulate the ionic transport properties, such as ionic self-diffusion and shear viscosity coefficients, through the ionic velocity correlation functions. Due that the free electrons become more and more with increasing the plasma temperature, the influence of the electron-ion collisions on the transport properties become more and more important.

  14. Three dimensional stagnation point flow of bionanofluid with variable transport properties

    Directory of Open Access Journals (Sweden)

    N.A. Amirsom

    2016-09-01

    Full Text Available Bionanofluid is a nanofluid in which bioconvection occurs. This paper studies the three dimensional steady stagnation point flow of a bionanofluid with variable transport properties. All the transport properties are dependent on the concentration. Zero mass flux and thermal convective boundary conditions are taken into account. The governing equations of the problem are nondimensionalized and transformed into a set of similarity equations using similarity transformation generated by Lie group analysis. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order numerical method (RKF45. The solutions depend on the viscosity parameter, thermal conductive parameter, mass diffusivity parameter, microorganism diffusivity parameter, Schmidt number, bioconvection Schmidt number and Péclet number. These controlling parameters affect the dimensionless velocity, temperature, nanoparticle volume fraction, microorganisms, the skin friction coefficient, the local Nusselt number and the Sherwood number as well as the motile microorganism rate and are displayed graphically. The results were found to be in good agreement with previous related studies.

  15. Transport properties of as-grown MgB{sub 2} films using micro-bridge

    Energy Technology Data Exchange (ETDEWEB)

    Iriuda, H. [Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Harada, Y. [Iwate Industry Promotion Center, 3-35-2 Iiokashinden, Morioka, Iwate 020-0852 (Japan)]. E-mail: yharada@luck.ocn.ne.jp; Goto, S. [Lightom, 95-2 Sugo, Takizawa 020-0173 (Japan); Shimizu, T. [Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Takahashi, T. [Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Kuroha, M. [Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Oba, T. [Faculty of Materials science and Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Seki, M. [Faculty of Materials science and Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Nakanishi, Y. [Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Yoshizawa, M. [Iwate Industry Promotion Center, 3-35-2 Iiokashinden, Morioka, Iwate 020-0852 (Japan)

    2006-10-01

    The intermetallic superconductor magnesium diboride (MgB{sub 2}) is a promising candidate for use in superconducting electronic devices due to its high transition temperature (T{sub c}) and simple AlB{sub 2} type structure. Its application requires the development of a high-quality film fabrication process. We have previously reported the growth of MgB{sub 2} films deposited on MgO (1 0 0), SrTiO{sub 3} (1 0 0) and Al{sub 2}O{sub 3} (0 0 0 1) substrate using a co-evaporation method combined with a molecular beam epitaxy (MBE) apparatus. In this paper, we report on the details of the transport properties of these as-grown MgB{sub 2} films. These film's basal properties were investigated by XRD, RHEED, SQUID and the dc-4 probe method. Micro-bridges made using micro-processing methods such as photolithography and dry etching were used for transport measurements. All bridges were 10 {mu}m wide x 30 {mu}m long to allow estimation of their critical current density using the dc-4 probe method. We discuss the relationship between critical current densities and the substrates used.

  16. Gray free-energy multiphase lattice Boltzmann model with effective transport and wetting properties.

    Science.gov (United States)

    Zalzale, Mohamad; Ramaioli, M; Scrivener, K L; McDonald, P J

    2016-11-01

    The paper shows that it is possible to combine the free-energy lattice Boltzmann approach to multiphase modeling of fluids involving both liquid and vapor with the partial bounce back lattice Boltzmann approach to modeling effective media. Effective media models are designed to mimic the properties of porous materials with porosity much finer than the scale of the simulation lattice. In the partial bounce-back approach, an effective media parameter or bounce-back fraction controls fluid transport. In the combined model, a wetting potential is additionally introduced that controls the wetting properties of the fluid with respect to interfaces between free space (white nodes), effective media (gray nodes), and solids (black nodes). The use of the wetting potential combined with the bounce-back parameter gives the model the ability to simulate transport and sorption of a wide range of fluid in material systems. Results for phase separation, permeability, contact angle, and wicking in gray media are shown. Sorption is explored in small sections of model multiscale porous systems to demonstrate two-step desorption, sorption hysteresis, and the ink-bottle effect.

  17. Transport properties of zeolite Na-X-Nafion membranes: effect of zeolite loadings and particle size

    Energy Technology Data Exchange (ETDEWEB)

    Lavorgna, M. [Institute of Composite and Biomedical Materials, National Research Council, Portici (Italy); Sansone, L.; Scherillo, G. [Department of Materials and Production, University of Napoli Federico II, Napoli (Italy); Gu, R.; Baker, A.P. [Department of Materials Science and Engineering, HIT Graduate School, Xili, Shenzhen (China)

    2011-12-15

    Na-X zeolites particles, synthesized in two size ranges, namely 200-300 nm and 30-100 nm, were used to prepare Nafion/Na-X zeolite composite membranes by recast method. The physical, chemical, and morphological properties of the zeolite powders and composite membranes were examined by XRD, N{sub 2} adsorption isotherms, FTIR, SEM, and SAXS analysis. Furthermore, the effect of zeolite particles size and loadings (i.e., 5 and 10% w/w) on the water, methanol, and proton transport properties was investigated. It has been found that the size of the Na-X zeolite particles plays a key role in the proton and methanol transport behavior since it rules the zeolite hydrophilic behavior, the morphology of polymer-filler interphase, and also the nature of water established in the composite membrane. The results show that the membranes loaded with a 5% w/w of submicron-sized Na-X zeolite exhibit a proton conductivity and selectivity significantly higher than Nafion. In particular the proton conductivity at 120 C is around eight times and the selectivity at 25 C is around 40% higher than those exhibited by recast Nafion. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Electrical transport properties of graphene nanowalls grown at low temperature using plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Zhao, Rong; Ahktar, Meysam; Alruqi, Adel; Dharmasena, Ruchira; Jasinski, Jacek B.; Thantirige, Rukshan M.; Sumanasekera, Gamini U.

    2017-05-01

    In this work, we report the electrical transport properties of uniform and vertically oriented graphene (graphene nanowalls) directly synthesized on multiple substrates including glass, Si/SiO2 wafers, and copper foils using radio-frequency plasma enhanced chemical vapor deposition (PECVD) with methane (CH4) as the precursor at relatively low temperatures. The temperature for optimum growth was established with the aid of transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy. This approach offers means for low-cost graphene nanowalls growth on an arbitrary substrate with the added advantage of transfer-free device fabrication. The temperature dependence of the electrical transport properties (resistivity and thermopower) were studied in the temperature range, 30-300 K and analyzed with a combination of 2D-variable range hopping (VRH) and thermally activated (TA) conduction mechanisms. An anomalous temperature dependence of the thermopower was observed for all the samples and explained with a combination of a diffusion term having a linear temperature dependence plus a term with an inverse temperature dependence.

  19. Electronic Transport Properties of an Anthraquinone-Based Molecular Switch with Carbon Nanotube Electrodes

    Institute of Scientific and Technical Information of China (English)

    ZHAO Peng; LIU De-Sheng

    2012-01-01

    Based on the nonequilibrium Green's function method and density functional theory calculations,we theoretically investigate the electronic transport properties of an anthraquinone-based molecular switch with carbon nanotube electrodes.The molecules that comprise the switch can convert between reduced hydroquinone (HQ) and oxidized anthraquinne (AQ) states via redox reactions.Our results show that the on-off ratio is increased one order of magnitude when compared to the case of gold electrodes.Moreover,an obvious negative differential resistance behavior at much low bias (0.07 V) is observed in the HQ form.%Based on the nonequilihrium Green's function method and density functional theory calculations, we theoretically investigate the electronic transport properties of an anthraquinone-based molecular switch with carbon nanotube electrodes. The molecules that comprise the switch can convert between reduced hydroquinone (HQ) and oxidized anthraquinne (AQ) states via redox reactions. Our results show that the on-off ratio is increased one order of magnitude when compared to the case of gold electrodes. Moreover, an obvious negative differential resistance behavior at much low bias (0.07 V) is observed in the HQ form.

  20. Evaluation of transport properties of nanofiltration membranes exposed to radioactive liquid waste

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Elizabeth E.M.; Barbosa, Celina C.R.; Bastos, Edna T.R., E-mail: eemo@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeira, RJ (Brazil); Afonso, Julio C., E-mail: Julio@iq.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Quimica. Dept. de Quimica Analitica

    2011-07-01

    The application of membrane separation processes (PSM) for treatment of radioactive waste requires the selection of a suitable membrane for the treatment of waste, as the membrane will be directly exposed to the radioactive liquid waste, and also exposed to ionizing radiation. The nanofiltration membrane is most suitable for treatment of radioactive waste, since it has high rejection of multivalent ions. Usually the membranes are made of polymers and depending on the composition of the waste, type and dose of radiation absorbed may be changes in the structure of the membrane, resulting in loss of its transport properties. We tested two commercial nanofiltration membranes: NF and SW Dow/Filmtec. The waste liquid used was obtained in the process of conversion of uranium hexafluoride gas to solid uranium dioxide, known as 'carbonated water'. The membranes were characterized as their transport properties (hydraulic permeability, permeate flux and salt rejection) before and after their immersion in the waste for 24 hours. The surface of the membranes was also evaluated by SEM and FTIR. It was observed that in both the porosity of the membrane selective layer was altered, but not the membrane surface charge, which is responsible for the selectivity of the membrane. The NF membranes and SW showed uranium ion rejection of 64% and 55% respectively. (author)