Low-temperature transport properties of TaxN thin films (0.72 <= x <= 0.83)

NASA Astrophysics Data System (ADS)

Očko, Miroslav; Žonja, Sanja; Nelson, G. L.; Freericks, J. K.; Yu, Lei; Newman, N.

2010-11-01

We report on low-temperature (4-320 K) transport properties of TaxN thin films deposited on an amorphous SiO2 substrate. In this work, TaxN thin films were restricted to a narrow range of x: 0.72 <= x <= 0.83 yet show considerable and nonmonotonic variation of their transport properties with Ta concentration. This behaviour is consistent with a local minimum in the density of electronic states at the Fermi level, as calculated for the rock salt intermetallic Ta4N5, and a rigid band model for describing the transport. The temperature dependence of the resistivity is best fit to the unusual form exp(-T/T0). Interestingly enough, the fit parameter T0 correlates well with the temperature of the maximum of the corresponding thermopower. Both of these characteristics, the fit and the correlation with the thermopower, are consistent with the Jonson-Mahan many-body formalism for charge and thermal transport when one has a nontrivial temperature dependence of the chemical potential. At the lowest temperatures measured, we have also found that the resistivity and thermopower show signatures of electron-electron interactions. We discuss also our results in the light of some theories usually used for describing transport of thin films and to other experimental investigations that have been performed on TaxN.

First-principles study of thermal transport in nitrogenated holey graphene.

PubMed

Ouyang, Tao; Xiao, Huaping; Tang, Chao; Zhang, Xiaoliang; Hu, Ming; Zhong, Jianxin

2017-01-27

Nitrogenated holey graphene (NHG), a new two-dimensional graphene variant with a large fundamental direct band gap, has recently been successfully synthesized via a simple wet-chemical reaction. Motivated by its unique geometry and novel properties, we investigated the phonon transport properties of the material by combining first-principle calculations and the phonon Boltzmann transport equation. The lattice thermal conductivity of NHG at room temperature is predicted to be about 82.22 W mK -1 , which is almost two orders of magnitude lower than that of graphene (about 3500 W mK -1 ). Deviating from the traditional understanding that thermal transport is usually largely contributed by the acoustic phonon modes for most suspended 2D materials, both out-of-plane flexural acoustic (ZA) and optical phonon modes make a more or less equal contribution, and their combination abnormally dominates the overall thermal transport in NHG. The major three-phonon process in NHG is further analyzed and the scattering between the acoustic and optical phonon modes like [Formula: see text] is the main phonon process channel. Meanwhile, the mean free path distribution of different phonon modes is calculated for the purpose of the thermal management of NHG-based devices. Our results elucidate the unusual thermal transport properties of NHG as compared with the representative case of graphene, and underpin its potential application for use by the thermal management community.

First-principles study of thermal transport in nitrogenated holey graphene

NASA Astrophysics Data System (ADS)

Ouyang, Tao; Xiao, Huaping; Tang, Chao; Zhang, Xiaoliang; Hu, Ming; Zhong, Jianxin

2017-01-01

Nitrogenated holey graphene (NHG), a new two-dimensional graphene variant with a large fundamental direct band gap, has recently been successfully synthesized via a simple wet-chemical reaction. Motivated by its unique geometry and novel properties, we investigated the phonon transport properties of the material by combining first-principle calculations and the phonon Boltzmann transport equation. The lattice thermal conductivity of NHG at room temperature is predicted to be about 82.22 W mK-1, which is almost two orders of magnitude lower than that of graphene (about 3500 W mK-1). Deviating from the traditional understanding that thermal transport is usually largely contributed by the acoustic phonon modes for most suspended 2D materials, both out-of-plane flexural acoustic (ZA) and optical phonon modes make a more or less equal contribution, and their combination abnormally dominates the overall thermal transport in NHG. The major three-phonon process in NHG is further analyzed and the scattering between the acoustic and optical phonon modes like {{ZA}}/{{TA}}/{{LA}}+{{O}}≤ftrightarrow {{O}} is the main phonon process channel. Meanwhile, the mean free path distribution of different phonon modes is calculated for the purpose of the thermal management of NHG-based devices. Our results elucidate the unusual thermal transport properties of NHG as compared with the representative case of graphene, and underpin its potential application for use by the thermal management community.

Roles of airships in economic development

NASA Technical Reports Server (NTRS)

Beier, G. J.; Hidalgo, G. C.

1975-01-01

It is proposed that airships of known and tested technology could, in some cases, perform routine transport missions more economically than conventional transport modes. If infrastructure for direct surface transport is already in place or if such infrastructure can be justified by the size of the market and there are no unusual impediments to constructing it, then the airships of tested technology cannot normally compete. If, however, the surface routes would be unusually expensive or circuitous, or if they involve several transhipments, or if the market size is too small to spread infrastructure costs of conventional transport, the airships of tested technology present a workable alternative. A series of special cases are considered. The cases, though unusual, are not unique; there are several similar possible applications which, in total, would provide a reasonably large market for airships.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Handali, Melody; Neupane, Durga P.; Roychowdhury, Hridindu

Here, ATP-binding cassette (ABC) transporters of the cluster 9 family are ubiquitous among bacteria and essential for acquiring Zn 2+ and Mn 2+ from the environment or, in the case of pathogens, from the host. These rely on a substrate-binding protein (SBP) to coordinate the relevant metal with high affinity and specificity and subsequently release it to a membrane permease for translocation into the cytoplasm. Although a number of cluster 9 SBP structures have been determined, the structural attributes conferring Zn 2+ or Mn 2+ specificity remain ambiguous. Here we describe the gene expression profile, in vitro metal binding properties,more » and crystal structure of a new cluster 9 SBP from Paracoccus denitrificans we have called AztC. Although all of our results strongly indicate Zn 2+ over Mn 2+ specificity, the Zn 2+ ion is coordinated by a conserved Asp residue only observed to date as a metal ligand in Mn 2+-specific SBPs. The unusual sequence properties of this protein are shared among close homologues, including members from the human pathogens Klebsiella pneumonia and Enterobacter aerogenes, and would seem to suggest a subclass of Zn 2+-specific transporters among the cluster 9 family. In any case, the unusual coordination environment of AztC expands the already considerable range of those available to Zn 2+-specific SBPs and highlights the presence of a His-rich loop as the most reliable indicator of Zn 2+ specificity.« less

Transport, Optical, and Magnetic Properties of the Conducting Halide Perovskite CH 3NH 3SnI 3

NASA Astrophysics Data System (ADS)

Mitzi, D. B.; Feild, C. A.; Schlesinger, Z.; Laibowitz, R. B.

1995-01-01

A low-temperature ( T ≤ 100°C) solution technique is described for the preparation of polycrystalline and single crystal samples of the conducting halide perovskite, CH 3NH 3SnI 3. Transport, Hall effect, magnetic, and optical properties are examined over the temperature range 1.8-300 K, confirming that this unusual conducting halide perovskite is a low carrier density p-type metal with a Hall hole density, 1/ RHe ≃ 2 × 10 19 cm -3. The resistivity of pressed pellet samples decreases with decreasing temperature with resistivity ratio ρ(300 K)/ρ(2 K) ≃ 3 and room temperature resistivity ρ(300 K) ≃ 7 mΩ-cm. A free-carrier infrared reflectivity spectrum with a plasma edge observed at approximately 1600 cm -1 further attests to the metallic nature of this compound and suggests a small optical effective mass, m* ≃ 0.2.

High thermoelectric properties of (Sb, Bi)2Te3 nanowire arrays by tilt-structure engineering

NASA Astrophysics Data System (ADS)

Tan, Ming; Hao, Yanming; Deng, Yuan; Chen, Jingyi

2018-06-01

In this paper, we present an innovative tilt-structure design concept for (Sb, Bi)2Te3 nanowire array assembled by high-quality nanowires with well oriented growth, utilizing a simple vacuum thermal evaporation technique. The unusual tilt-structure (Sb, Bi)2Te3 nanowire array with a tilted angle of 45° exhibits a high thermoelectric dimensionless figure-of-merit ZT = 1.72 at room temperature. The relatively high ZT value in contrast to that of previously reported (Sb, Bi)2Te3 materials and the vertical (Sb, Bi)2Te3 nanowire arrays evidently reveals the crucial role of the unique tilt-structure in favorably influencing carrier and phonon transport properties, resulting in a significantly improved ZT value. The transport mechanism of such tilt-structure is proposed and investigated. This method opens a new approach to optimize nano-structure in thin films for next-generation thermoelectric materials and devices.

Additively manufactured metallic pentamode meta-materials

NASA Astrophysics Data System (ADS)

Hedayati, R.; Leeflang, A. M.; Zadpoor, A. A.

2017-02-01

Mechanical metamaterials exhibit unusual mechanical properties that originate from their topological design. Pentamode metamaterials are particularly interesting because they could be designed to possess any thermodynamically admissible elasticity tensor. In this study, we additively manufacture the metallic pentamode metamaterials from a biocompatible and mechanically strong titanium alloy (Ti-6Al-4V) using an energy distribution method developed for the powder bed fusion techniques. The mechanical properties of the developed materials were a few orders of magnitude higher than those of the similar topologies fabricated previously from polymers. Moreover, the elastic modulus and yield stress of the presented pentamode metamaterials were decoupled from their relative density, meaning that the metallic meta-biomaterials with independently tailored elastic and mass transport (permeability) properties could be designed for tissue regeneration purposes.

Atomic layer deposition modified track-etched conical nanochannels for protein sensing.

PubMed

Wang, Ceming; Fu, Qibin; Wang, Xinwei; Kong, Delin; Sheng, Qian; Wang, Yugang; Chen, Qiang; Xue, Jianming

2015-08-18

Nanopore-based devices have recently become popular tools to detect biomolecules at the single-molecule level. Unlike the long-chain nucleic acids, protein molecules are still quite challenging to detect, since the protein molecules are much smaller in size and usually travel too fast through the nanopore with poor signal-to-noise ratio of the induced transport signals. In this work, we demonstrate a new type of nanopore device based on atomic layer deposition (ALD) Al2O3 modified track-etched conical nanochannels for protein sensing. These devices show very promising properties of high protein (bovine serum albumin) capture rate with well time-resolved transport signals and excellent signal-to-noise ratio for the transport events. Also, a special mechanism involving transient process of ion redistribution inside the nanochannel is proposed to explain the unusual biphasic waveshapes of the current change induced by the protein transport.

Interaction and Correlation Effects in Quasi Two-dimensional Materials

NASA Astrophysics Data System (ADS)

Louie, Steven G.

2015-03-01

Experimental and theoretical studies of atomically thin quasi two-dimensional materials (typically related to some parent van der Waals layered crystals) and their nanostructures have revealed that these systems can exhibit highly unusual behaviors. In this talk, we discuss some theoretical studies of the electronic, transport and optical properties of such systems. We present results on graphene and graphene nanostructures as well as other quasi-2D systems such as monolayer and few-layer transition metal dichalcogenides (e.g., MoS2, MoSe2, WS2, and WSe2) and metal monochalcogenides (such as GaSe and FeSe). Owing to their reduced dimensionality, these systems present opportunities for unusual manifestation of concepts and phenomena that may not be so prominent or have not been seen in bulk materials. Symmetry and many-body interaction effects often play a critical role in shaping qualitatively and quantitatively their properties. Several quantum phenomena are discussed, including novel and dominant exciton effects, tunable magnetism, electron supercollimation by disorder, unusual plasmon behaviors, and possible enhanced superconductivity in some of these systems. We investigate their physical origins and compare theoretical predictions with experimental data. This work was supported by DOE under Contract No. DE-AC02-05CH11231 and by NSF under Grant No. DMR10-1006184. I would like to acknowledge collaborations with members of the Louie group and the experimental groups of Crommie, Heinz, Wang, and Zhang.

Nano Titanium Monoxide Crystals and Unusual Superconductivity at 11 K.

PubMed

Xu, Jijian; Wang, Dong; Yao, Heliang; Bu, Kejun; Pan, Jie; He, Jianqiao; Xu, Fangfang; Hong, Zhanglian; Chen, Xiaobo; Huang, Fuqiang

2018-03-01

Nano TiO 2 is investigated intensely due to extraordinary photoelectric performances in photocatalysis, new-type solar cells, etc., but only very few synthesis and physical properties have been reported on nanostructured TiO or other low valent titanium-containing oxides. Here, a core-shell nanoparticle made of TiO core covered with a ≈5 nm shell of amorphous TiO 1+ x is newly constructed via a controllable reduction method to synthesize nano TiO core and subsequent soft oxidation to form the shell (TiO 1+ x ). The physical properties measurements of electrical transport and magnetism indicate these TiO@TiO 1+ x nanocrystals are a type-ІІ superconductor of a recorded T c onset = 11 K in the binary Ti-O system. This unusual superconductivity could be attributed to the interfacial effect due to the nearly linear gradient of O/Ti ratio across the outer amorphous layer. This novel synthetic method and enhanced superconductivity could open up possibilities in interface superconductivity of nanostructured composites with well-controlled interfaces. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The importance of transport property studies for battery electrolytes: revisiting the transport properties of lithium-N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide mixtures.

PubMed

Rüther, Thomas; Kanakubo, Mitsuhiro; Best, Adam S; Harris, Kenneth R

2017-04-19

Transport properties are examined in some detail for samples of the low temperature molten salt N-propyl-N-methyl pyrrolidinium bis(fluorosulfonyl)imide [Pyr 13 ][FSI] from two different commercial suppliers. A similar set of data is presented for two different concentrations of binary lithium-[Pyr 13 ][FSI] salt mixtures from one supplier. A new and significantly different production process is used for the synthesis of Li[FSI] as well as the [Pyr 13 ] + salt used in the mixtures. Results for the viscosity, conductivity, and self-diffusion coefficients, together with the density and expansivity and apparent molar volume, are reported over the temperature range of (0 to 80) °C. The data for neat [Pyr 13 ][FSI] are discussed in the context of velocity cross correlation (VCC or f ij ) and Laity resistance (r ij ) coefficients. Unusually, f +- ∼ f ++ < f -- . The three resistance coefficients are of similar magnitude indicating all three ion-ion interactions contribute to the transport properties, not just the cation-anion interaction. The composition dependence of the transport properties is compared to previously reported data for the same and related compounds: in contrast to high-temperature molten salt mixtures, this is an exponential dependence. The Nernst-Einstein parameter Δ, which contains information on the correlations of the ionic velocities and is determined by differences in the VCC for the various ion-ion combinations, was calculated for both the neat ionic liquid and its binary mixture. It increases with increasing lithium concentration. The new data set also allows some conclusions with regards to the lithium-[FSI] - coordination environment.

TOPICAL REVIEW: Electrical transport modelling in organic electroluminescent devices

NASA Astrophysics Data System (ADS)

Walker, A. B.; Kambili, A.; Martin, S. J.

2002-10-01

Organic electroluminescent devices (OEDs) emit light when an electric current is applied to a thin film section. They arise from two main technology branches - small molecules and light emitting polymers. Apart from the insight offered into the fundamentals of their physics, which is relevant to topics such as electrical transport in biological systems and molecular computers, understanding how the mobilities in these systems vary with morphology and composition enables the design of improved materials for technological requirements, e.g. fast switching speeds for active matrix displays and polymer field effect transistors. In this review, we have focussed on the models of transport in OEDs that address the unusual nature of this transport and underpin device design. The review concludes with the following point: as new materials for use in OEDs continue to appear, modelling is essential for the prediction of their transport properties, which in turn leads to the establishment of fundamental trends in the behaviour of devices employing them.

Heat perturbation spreading in the Fermi-Pasta-Ulam-β system with next-nearest-neighbor coupling: Competition between phonon dispersion and nonlinearity

NASA Astrophysics Data System (ADS)

Xiong, Daxing

2017-06-01

We employ the heat perturbation correlation function to study thermal transport in the one-dimensional Fermi-Pasta-Ulam-β lattice with both nearest-neighbor and next-nearest-neighbor couplings. We find that such a system bears a peculiar phonon dispersion relation, and thus there exists a competition between phonon dispersion and nonlinearity that can strongly affect the heat correlation function's shape and scaling property. Specifically, for small and large anharmoncities, the scaling laws are ballistic and superdiffusive types, respectively, which are in good agreement with the recent theoretical predictions; whereas in the intermediate range of the nonlinearity, we observe an unusual multiscaling property characterized by a nonmonotonic delocalization process of the central peak of the heat correlation function. To understand these multiscaling laws, we also examine the momentum perturbation correlation function and find a transition process with the same turning point of the anharmonicity as that shown in the heat correlation function. This suggests coupling between the momentum transport and the heat transport, in agreement with the theoretical arguments of mode cascade theory.

Electron transport and thermoelectric properties of layered perovskite LaBaCo(2)O(5.5).

PubMed

Kundu, Asish K; Raveau, B; Caignaert, V; Rautama, E-L; Pralong, V

2009-02-04

We have investigated systematically the physical transport properties of layered 112-type cobaltite by means of electrical resistivity, magnetoresistance and thermopower measurements. In order to understand the complex transport mechanism of LaBaCo(2)O(5.5), the data have been analysed using different theoretical models. The compound shows an electronic transition between two semiconducting states around 326 K, which coincides with the ferromagnetic transition. Interestingly, the system also depicts a significant magnetoresistance (MR) effect near the ferro/antiferromagnetic phase boundary and the highest value of MR is close to 5% at 245 K under ± 7 T. The temperature dependence of thermopower, S(T), exhibits p-type conductivity in the 60 K≤T≤320 K range and reaches a maximum value of around 303 µV K(-1) (at 120 K). In the low temperature antiferromagnetic region the unusual S(T) behaviour, generally observed for the cobaltite series LnBaCo(2)O(5.5) (Ln = rare earth), is explained by the electron magnon scattering mechanism.

Bulk and Thin film Properties of Nanoparticle-based Ionic Materials

NASA Astrophysics Data System (ADS)

Fang, Jason

2008-03-01

Nanoparticle-based ionic materials (NIMS) offer exciting opportunities for research at the forefront of science and engineering. NIMS are hybrid particles comprised of a charged oligomeric corona attached to hard, inorganic nanoparticle cores. Because of their hybrid nature, physical properties --rheological, optical, electrical, thermal - of NIMS can be tailored over an unusually wide range by varying geometric and chemical characteristics of the core and canopy and thermodynamic variables such as temperature and volume fraction. On one end of the spectrum are materials with a high core content, which display properties similar to crystalline solids, stiff waxes, and gels. At the opposite extreme are systems that spontaneously form particle-based fluids characterized by transport properties remarkably similar to simple liquids. In this poster I will present our efforts to synthesize NIMS and discuss their bulk and surface properties. In particular I will discuss our work on preparing smart surfaces using NIMS.

Use of side-chain for rational design of n-type diketopyrrolopyrrole-based conjugated polymers: what did we find out?

PubMed

Kanimozhi, Catherine; Yaacobi-Gross, Nir; Burnett, Edmund K; Briseno, Alejandro L; Anthopoulos, Thomas D; Salzner, Ulrike; Patil, Satish

2014-08-28

The primary role of substituted side chains in organic semiconductors is to increase their solubility in common organic solvents. In the recent past, many literature reports have suggested that the side chains play a critical role in molecular packing and strongly impact the charge transport properties of conjugated polymers. In this work, we have investigated the influence of side-chains on the charge transport behavior of a novel class of diketopyrrolopyrrole (DPP) based alternating copolymers. To investigate the role of side-chains, we prepared four diketopyrrolopyrrole-diketopyrrolopyrrole (DPP-DPP) conjugated polymers with varied side-chains and carried out a systematic study of thin film microstructure and charge transport properties in polymer thin-film transistors (PTFTs). Combining results obtained from grazing incidence X-ray diffraction (GIXD) and charge transport properties in PTFTs, we conclude side-chains have a strong influence on molecular packing, thin film microstructure, and the charge carrier mobility of DPP-DPP copolymers. However, the influence of side-chains on optical properties was moderate. The preferential "edge-on" packing and dominant n-channel behavior with exceptionally high field-effect electron mobility values of >1 cm(2) V(-1) s(-1) were observed by incorporating hydrophilic (triethylene glycol) and hydrophobic side-chains of alternate DPP units. In contrast, moderate electron and hole mobilities were observed by incorporation of branched hydrophobic side-chains. This work clearly demonstrates that the subtle balance between hydrophobicity and hydrophilicity induced by side-chains is a powerful strategy to alter the molecular packing and improve the ambipolar charge transport properties in DPP-DPP based conjugated polymers. Theoretical analysis supports the conclusion that the side-chains influence polymer properties through morphology changes, as there is no effect on the electronic properties in the gas phase. The exceptional electron mobility is at least partially a result of the strong intramolecular conjugation of the donor and acceptor as evidenced by the unusually wide conduction band of the polymer.

Interfacial Coupling-Induced Ferromagnetic Insulator Phase in Manganite Film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Bangmin; Wu, Lijun; Yin, Wei-Guo

Interfaces with subtle difference in atomic and electronic structures in perovskite ABO3 heterostructures often yield intriguingly different properties, yet their exact roles remain elusive. Here, we report an integrated study of unusual transport, magnetic, and structural properties of Pr0.67Sr0.33MnO3 (PSMO) film on SrTiO3 (STO) substrate. The variations in out-of-plane lattice constant and BO6 octahedral rotation across the PSMO/STO interface strongly depend on the thickness of PSMO films. In the 12-nm film, a new interface-sensitive ferromagnetic polaronic insulator (FI’) phase is formed during the cubic-to-tetragonal phase transition of STO, apparently due to enhanced electron-phonon interaction and atomic disorder in the film.more » The transport properties of the FI’ phase in the 30-nm film are masked because of the reduced interfacial effect and smaller interface-to-volume ratio. This work demonstrates how thickness-dependent interfacial coupling leads to formation of the theoretically predicted novel ferromagnetic-polaronic insulator in systems, as illustrated in a new phase diagram, that are otherwise ferromagnetic metals (FM) in bulk form.« less

Unusual Thermoelectric Behavior Indicating a Hopping to Bandlike Transport Transition in Pentacene

NASA Astrophysics Data System (ADS)

Germs, W. Chr.; Guo, K.; Janssen, R. A. J.; Kemerink, M.

2012-07-01

An unusual increase in the Seebeck coefficient with increasing charge carrier density is observed in pentacene thin film transistors. This behavior is interpreted as being due to a transition from hopping transport in static localized states to bandlike transport, occurring at temperatures below ˜250K. Such a transition can be expected for organic materials in which both static energetic disorder and dynamic positional disorder are important. While clearly visible in the temperature and density dependent Seebeck coefficient, the transition hardly shows up in the charge carrier mobility.

2:1 Charge disproportionation in perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Haichuan; Hosaka, Yoshiteru; Seki, Hayato

La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} was synthesized at a high pressure and high temperature. The compound crystallizes in a √2a×2a×√2a perovskite cell in which the La and Ca ions at the A site are disordered. At 217 K the Fe{sup 3.67+} shows charge disproportionation to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1, and this disproportionation is accompanied by transitions in magnetic and transport properties. The charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. The local electronic and magnetic environments of Fe in La{sub 1/3}Ca{sub 2/3}FeO{submore » 3} are quite similar to those of Fe in La{sub 1/3}Sr{sub 2/3}FeO{sub 3}, and the 2:1 charge disproportionation pattern of Fe{sup 3+} and Fe{sup 5+} in La{sub 1/3}Ca{sub 2/3}FeO{sub 3} is also the same as that in La{sub 1/3}Sr{sub 2/3}FeO{sub 3}. - Graphical abstract: The perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} shows charge disproportionation to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1, and the charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. - Highlights: • La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} was synthesized at a high pressure and high temperature. • At 217 K the Fe{sup 3.67+} shows charge disproportionation (CD) to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1. • The charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. • The disproportionation is accompanied by transitions in magnetic and transport properties.« less

Communication: Unusual structure and transport in ionic liquid-hexane mixtures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Min; Khatun, Sufia; Castner, Edward W., E-mail: ecastner@rci.rutgers.edu

2015-03-28

Ionic liquids having a sufficiently amphiphilic cation can dissolve large volume fractions of alkanes, leading to mixtures with intriguing properties on molecular length scales. The trihexyl(tetradecyl)phosphonium cation paired with the bis(trifluoromethylsulfonyl)amide anion provides an ionic liquid that can dissolve large mole fractions of hexane. We present experimental results on mixtures of n-C{sub 6}D{sub 14} with this ionic liquid. High-energy X-ray scattering studies reveal a persistence of the characteristic features of ionic liquid structure even for 80% dilution with n-C{sub 6}D{sub 14}. Nuclear magnetic resonance self-diffusion results reveal decidedly non-hydrodynamic behavior where the self-diffusion of the neutral, non-polar n-C{sub 6}D{sub 14}more » is on average a factor of 21 times faster than for the cation. Exploitation of the unique structural and transport properties of these mixtures may lead to new opportunities for designer solvents for enhanced chemical reactivity and interface science.« less

Communication: Unusual structure and transport in ionic liquid-hexane mixtures

DOE PAGES

Liang, Min; Khatun, Sufia; Castner, Edward W.

2015-03-28

Ionic liquids having a sufficiently amphiphilic cation can dissolve large volume fractions of alkanes, leading to mixtures with intriguing properties on molecular length scales. The trihexyl(tetradecyl)phosphonium cation paired with the bis(trifluoromethylsulfonyl)amide anion provides an ionic liquid that can dissolve large mole fractions of hexane. We present experimental results on mixtures of n-C 6D 14 with this ionic liquid. High- energy X-ray scattering studies reveal a persistence of the characteristic features of ionic liquid structure even for 80% dilution with n-C 6D 14. NMR self-diffusion results reveal decidedly non-hydrodynamic behavior where the self-diffusion of the neutral, non-polar n-C 6D 14 ismore » on average a factor of 21 times faster than for the cation. Exploitation of the unique structural and transport properties of these mixtures may lead to new opportunities for designer solvents for enhanced chemical reactivity and interface science.« less

Holistic quantum design of thermoelectric niobium oxynitride

NASA Astrophysics Data System (ADS)

Music, Denis; Bliem, Pascal; Hans, Marcus

2015-06-01

We have applied holistic quantum design to thermoelectric NbON (space group Pm-3m). Even though transport properties are central in designing efficient thermoelectrics, mechanical properties should also be considered to minimize their thermal fatigue during multiple heating/cooling cycles. Using density functional theory, elastic constants of NbON were predicted and validated by nanoindentation measurements on reactively sputtered thin films. Based on large bulk-to-shear modulus ratio and positive Cauchy pressure, ceramic NbON appears ductile. These unusual properties may be understood by analyzing the electronic structure. Nb-O bonding is of covalent-ionic nature with metallic contributions. Second neighbor O-N bonds exhibit covalent-ionic character. Upon shear loading, these O-N bonds break giving rise to easily shearable planes. Ductile NbON, together with large Seebeck coefficient and low thermal expansion, is promising for thermoelectric applications.

Itinerant magnetism in doped semiconducting β-FeSi2 and CrSi2

PubMed Central

Singh, David J.; Parker, David

2013-01-01

Novel or unusual magnetism is a subject of considerable interest, particularly in metals and degenerate semiconductors. In such materials the interplay of magnetism, transport and other Fermi liquid properties can lead to fascinating physical behavior. One example is in magnetic semiconductors, where spin polarized currents may be controlled and used. We report density functional calculations predicting magnetism in doped semiconducting β-FeSi2 and CrSi2 at relatively low doping levels particularly for n-type. In this case, there is a rapid cross-over to a half-metallic state as a function of doping level. The results are discussed in relation to the electronic structure and other properties of these compounds. PMID:24343332

Ultrapermeable, reverse-selective nanocomposite membranes.

PubMed

Merkel, T C; Freeman, B D; Spontak, R J; He, Z; Pinnau, I; Meakin, P; Hill, A J

2002-04-19

Polymer nanocomposites continue to receive tremendous attention for application in areas such as microelectronics, organic batteries, optics, and catalysis. We have discovered that physical dispersion of nonporous, nanoscale, fumed silica particles in glassy amorphous poly(4-methyl-2-pentyne) simultaneously and surprisingly enhances both membrane permeability and selectivity for large organic molecules over small permanent gases. These highly unusual property enhancements, in contrast to results obtained in conventional filled polymer systems, reflect fumed silica-induced disruption of polymer chain packing and an accompanying subtle increase in the size of free volume elements through which molecular transport occurs, as discerned by positron annihilation lifetime spectroscopy. Such nanoscale hybridization represents an innovative means to tune the separation properties of glassy polymeric media through systematic manipulation of molecular packing.

Selective accumulation of biotin in arterial chemoreceptors: requirement for carotid body exocytotic dopamine secretion

PubMed Central

Ortega‐Sáenz, Patricia; Macías, David; Levitsky, Konstantin L.; Rodríguez‐Gómez, José A.; González‐Rodríguez, Patricia; Bonilla‐Henao, Victoria; Arias‐Mayenco, Ignacio

2016-01-01

Key points Biotin, a vitamin whose main role is as a coenzyme for carboxylases, accumulates at unusually large amounts within cells of the carotid body (CB).In biotin‐deficient rats biotin rapidly disappears from the blood; however, it remains at relatively high levels in CB glomus cells. The CB contains high levels of mRNA for SLC5a6, a biotin transporter, and SLC19a3, a thiamine transporter regulated by biotin.Animals with biotin deficiency exhibit pronounced metabolic lactic acidosis. Remarkably, glomus cells from these animals have normal electrical and neurochemical properties. However, they show a marked decrease in the size of quantal dopaminergic secretory events.Inhibitors of the vesicular monoamine transporter 2 (VMAT2) mimic the effect of biotin deficiency. In biotin‐deficient animals, VMAT2 protein expression decreases in parallel with biotin depletion in CB cells.These data suggest that dopamine transport and/or storage in small secretory granules in glomus cells depend on biotin. Abstract Biotin is a water‐soluble vitamin required for the function of carboxylases as well as for the regulation of gene expression. Here, we report that biotin accumulates in unusually large amounts in cells of arterial chemoreceptors, carotid body (CB) and adrenal medulla (AM). We show in a biotin‐deficient rat model that the vitamin rapidly disappears from the blood and other tissues (including the AM), while remaining at relatively high levels in the CB. We have also observed that, in comparison with other peripheral neural tissues, CB cells contain high levels of SLC5a6, a biotin transporter, and SLC19a3, a thiamine transporter regulated by biotin. Biotin‐deficient rats show a syndrome characterized by marked weight loss, metabolic lactic acidosis, aciduria and accelerated breathing with normal responsiveness to hypoxia. Remarkably, CB cells from biotin‐deficient animals have normal electrophysiological and neurochemical (ATP levels and catecholamine synthesis) properties; however, they exhibit a marked decrease in the size of quantal catecholaminergic secretory events, which is not seen in AM cells. A similar differential secretory dysfunction is observed in CB cells treated with tetrabenazine, a selective inhibitor of the vesicular monoamine transporter 2 (VMAT2). VMAT2 is highly expressed in glomus cells (in comparison with VMAT1), and in biotin‐deficient animals VMAT2 protein expression decreases in parallel with the decrease of biotin accumulated in CB cells. These data suggest that biotin has an essential role in the homeostasis of dopaminergic transmission modulating the transport and/or storage of transmitters within small secretory granules in glomus cells. PMID:27570189

Anomalous magnetotransport behavior in Fe-doped MnNiGe alloys

NASA Astrophysics Data System (ADS)

Dutta, P.; Pramanick, S.; Singh, Vijay; Major, Dan Thomas; Das, D.; Chatterjee, S.

2016-04-01

The electrical dc transport properties of hexagonal magnetic equiatomic alloys of nominal composition Mn1 -xFexNiGe (x =0.2 and0.25 ) have been investigated experimentally as well as theoretically using first-principles electronic structure calculations. Thermal hysteresis in the magnetization data indicates that the alloys undergo a first-order martensitic transition. Both the alloys show unusual nonmetallic resistivity behavior and a noticeable amount of training effect in resistivity when thermally cycled through the first-order martensitic transition. We observe moderate negative magnetoresistance (˜-11.5 % for 150 kOe) at 5 K (well below the martensitic transition temperature) associated with clear virgin line effect for both the alloys. We have adapted different flavors of density functional theory approach to understand the experimentally observed nonmetallic transport behavior.

Vacancy and curvature effects on the phonon properties of single wall carbon nanotube

NASA Astrophysics Data System (ADS)

Hossain Howlader, Ashraful; Sherajul Islam, Md.; Tanaka, Satoru; Makino, Takayuki; Hashimoto, Akihiro

2018-02-01

Single wall carbon nanotube (SWCNT) is considered as an ideal candidate for next-generation nanoelectronics owing to its unusual properties. Here we have performed an in-depth theoretical analysis of the effect of vacancy defects and curvature on the phonon properties of (10,0) and (10,10) SWCNTs using the forced vibrational method. We report that Raman active E2g mode softens towards the low-frequency region with increasing vacancies and curvature in both types of CNTs. Vacancy induces some new peaks at low-frequency region of the phonon density of states. Phonon localization properties are also manifested. Our calculated mode pattern and localization length show that optical phonon at Raman D-band frequency is strongly localized in vacancy defected and large curved CNTs. Our findings will be helpful in explaining the thermal conductivity, specific heat capacity, and Raman spectra in vacancy type disordered CNTs, as well as electron transport properties of CNT-based nanoelectronic devices.

49 CFR 805.735-3 - Policy.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 7 2010-10-01 2010-10-01 false Policy. 805.735-3 Section 805.735-3 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL TRANSPORTATION SAFETY BOARD EMPLOYEE RESPONSIBILITIES AND CONDUCT § 805.735-3 Policy. (a) The maintenance of unusually high standards of honesty...

49 CFR 805.735-3 - Policy.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 7 2011-10-01 2011-10-01 false Policy. 805.735-3 Section 805.735-3 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL TRANSPORTATION SAFETY BOARD EMPLOYEE RESPONSIBILITIES AND CONDUCT § 805.735-3 Policy. (a) The maintenance of unusually high standards of honesty...

Lantibiotic engineering: molecular characterization and exploitation of lantibiotic-synthesizing enzymes for peptide engineering.

PubMed

Nagao, Jun-ichi; Aso, Yuji; Shioya, Kouki; Nakayama, Jiro; Sonomoto, Kenji

2007-01-01

Lanthionine-containing peptide antibiotics called lantibiotics are produced by a large number of Gram-positive bacteria. Nukacin ISK-1 produced by Staphylococcus warneri ISK-1 is type-A(II) lantibiotic. Ribosomally synthesized nukacin ISK-1 prepeptide (NukA) consists of an N-terminal leader peptide followed by a C-terminal propeptide moiety that undergoes several post-translational modification events including unusual amino acid formation by the modification enzyme NukM, cleavage of leader peptide and export by the dual functional ABC transporter NukT, finally yielding a biologically active peptide. Unusual amino acids in lantibiotics contribute to biological activity and also structural stability against proteases. Thus, lantibiotic-synthesizing enzymes have a high potentiality for peptide engineering by introduction of unusual amino acids into desired peptides with altering biological and physicochemical properties, e.g., activity and stability, termed lantibiotic engineering. We report the establishment of a heterologous expression of nukacin ISK-1 biosynthetic gene cluster by the nisin-controlled expression system and discuss our recent progress in understanding of the biosynthetic enzymes for nukacin ISK-1 such as localization, molecular interaction in biophysical and biochemical aspects. Substrate specificity of the lantibiotic-synthesizing enzymes was evaluated by complementation of the biosynthetic enzymes (LctM and LctT) of closely related lantibiotic lacticin 481 for nukacin ISK-1 biosynthesis. We further explored a rapid and powerful tool for introduction of unusual amino acids by co-expression of hexa-histidine-tagged NukA and NukM in Escherichia coli.

Giant Magnetostriction in Annealed Co1-xFex Thin-Films

DTIC Science & Technology

2011-11-01

recently proposed heterogeneous magnetostriction mechanism can be used to guide exploration of compounds with unusual magnetoelastic properties ...proposed heterogeneous magnetostriction mechanism can be used to guide exploration of compounds with unusual magnetoelastic properties . 1 Department of...mechanical properties at low fields18. These characteristics have made the Fe–Ga alloys attractive alternatives to existing rare­earth­based

Spintronics device made of topological materials

NASA Astrophysics Data System (ADS)

Wu, Jiansheng; Shi, Zhangsheng; Wang, Maoji

Topological Materials is a new state of matter of which the bulk states are gapped insulator or superconductor while the surface states are gapless metallic states. Such surface states are robust against local disorder and impurities due to its nontrivial topology. It induces unusual transport properties and shows nontrivial topological spin texture in real space. We have made use of these two exotic properties to make application in spintronics. For example, we propose to make spin-filter transistor using of 1D or 2D quantum anomalous Hall insulator or 2D topological Weyl semimetal, we also propose a device to measure the spin-polarization of current, a device to generate entangled entangled electron pairs. Startup funds of SUSTC, Shenzhen Peacock Plan, Shenzhen Free Exploration Plan with Grant Number JCYJ20150630145302225.

Unusual ordering in c-NpPd3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gofryk, Krzysztof

2010-01-01

NpPd{sub 3} exhibits two crystal structures. At room temperature, the equilibrium structure is the dhcp TiNi{sub 3}-type, but rapid cooling from melt produces the cubic AuCu{sub 3}-type structure. In both cases, the Np-Np distance is 4.1 {angstrom}, so that the Np ions are expected to be localized. Both phases of NpPd{sub 3} were first studied at the ANL in the early 1970s. Nellis et al measured the magnetic susceptibility and the electrical resistivity of cubic NpPd{sub 3}, and found evidence of magnetic ordering setting in below T{sub N} = 54 K. The magnetic order in this phase was confirmed bymore » Moessbauer and neutron studies. The neutron data revealed several magnetic Bragg peaks with an ordering wave-vector of (1/2,1/2, 1/2). In contrast, no evidence for any long-range magnetic ordering was found for dhcp NpPd{sub 3}, despite the presence of an anomaly at 30 K in the bulk magnetic data. Our recent measurements of the magnetic (magnetization, susceptibility), thermal (heat capacity) and transport (electrical resistivity, magnetoresistivity, thermopower and Hall effect) properties of cubic NpPd{sub 3} indicated highly unusual nature of the magnetic ordering. At T{sub N}, the specific heat exhibits an extremely large peak [as large as 1000 J/(mol K)] and the magnetic susceptibility shows a clear jump. The transport properties of c-NpPd{sub 3} indicate a dramatic Fermi-surface reconstruction at T{sub N}, which shows up as pronounced anomalies at this temperature in the electrical resistivity, the magnetoresistivity, the Seebeck coefficient and the Hall coefficient.« less

Ionic behavior of organic-inorganic metal halide perovskite based metal-oxide-semiconductor capacitors.

PubMed

Wang, Yucheng; Zhang, Yuming; Pang, Tiqiang; Xu, Jie; Hu, Ziyang; Zhu, Yuejin; Tang, Xiaoyan; Luan, Suzhen; Jia, Renxu

2017-05-24

Organic-inorganic metal halide perovskites are promising semiconductors for optoelectronic applications. Despite the achievements in device performance, the electrical properties of perovskites have stagnated. Ion migration is speculated to be the main contributing factor for the many unusual electrical phenomena in perovskite-based devices. Here, to understand the intrinsic electrical behavior of perovskites, we constructed metal-oxide-semiconductor (MOS) capacitors based on perovskite films and performed capacitance-voltage (C-V) and current-voltage (I-V) measurements of the capacitors. The results provide direct evidence for the mixed ionic-electronic transport behavior within perovskite films. In the dark, there is electrical hysteresis in both the C-V and I-V curves because the mobile negative ions take part in charge transport despite frequency modulation. However, under illumination, the large amount of photoexcited free carriers screens the influence of the mobile ions with a low concentration, which is responsible for the normal C-V properties. Validation of ion migration for the gate-control ability of MOS capacitors is also helpful for the investigation of perovskite MOS transistors and other gate-control photovoltaic devices.

78 FR 68986 - Special Conditions: Boeing Model 777-200, -300, and -300ER Series Airplanes; Aircraft Electronic...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-18

... The Boeing Company, will have novel or unusual design features associated with the architecture and... proposed architecture is novel or unusual for commercial transport airplanes by enabling connection to... system architecture or electronic access to aircraft systems. Furthermore, regulations and current system...

Thin-film semiconductor perspective of organometal trihalide perovskite materials for high-efficiency solar cells

DOE PAGES

Xiao, Zhengguo; Yuan, Yongbo; Wang, Qi; ...

2016-02-19

Organolead trihalide perovskites (OTPs) are arising as a new generation of low-cost active materials for solar cells with efficiency rocketing from 3.5% to over 20% within only five years. From “dye” in dye sensitized solar cells to “hole conductors” and “electron conductors” in mesoscopic heterojunction solar cells, there has been a dramatic conceptual evolution on the function of OTPs in photovoltaic devices. OTPs were originally used as dyes in Gratzel cells, achieving a high efficiency above 15% which, however, did not manifest the excellent charge transport properties of OTPs. An analogy of OTPs to traditional semiconductors was drawn after themore » demonstration of highly efficient planar heterojunction structure OTP devices and the observation of their excellent bipolar transport properties with a large diffusion length exceeding 100 nm in CH 3NH 3PbI 3 (MAPbI 3) polycrystalline thin films. Here, this review aims to provide the most recent advances in the understanding of the origin of the high OTP device efficiency. Specifically we will focus on reviewing the progress in understanding 1) the characterization of fantastic optoelectronic property of OTPs, 2) the unusual defect physics that originate the optoelectronic property; 3) morphology control of the perovskite film from fabrication process and film post-treatment, and 4) device interface and charge transport layers that dramatically impact device efficiency in the OTP thin film devices; 5) photocurrent hysteresis; 6) tandem solar cells; 7) stability of the perovskite materials and solar cell devices.« less

Selective accumulation of biotin in arterial chemoreceptors: requirement for carotid body exocytotic dopamine secretion.

PubMed

Ortega-Sáenz, Patricia; Macías, David; Levitsky, Konstantin L; Rodríguez-Gómez, José A; González-Rodríguez, Patricia; Bonilla-Henao, Victoria; Arias-Mayenco, Ignacio; López-Barneo, José

2016-12-15

Biotin, a vitamin whose main role is as a coenzyme for carboxylases, accumulates at unusually large amounts within cells of the carotid body (CB). In biotin-deficient rats biotin rapidly disappears from the blood; however, it remains at relatively high levels in CB glomus cells. The CB contains high levels of mRNA for SLC5a6, a biotin transporter, and SLC19a3, a thiamine transporter regulated by biotin. Animals with biotin deficiency exhibit pronounced metabolic lactic acidosis. Remarkably, glomus cells from these animals have normal electrical and neurochemical properties. However, they show a marked decrease in the size of quantal dopaminergic secretory events. Inhibitors of the vesicular monoamine transporter 2 (VMAT2) mimic the effect of biotin deficiency. In biotin-deficient animals, VMAT2 protein expression decreases in parallel with biotin depletion in CB cells. These data suggest that dopamine transport and/or storage in small secretory granules in glomus cells depend on biotin. Biotin is a water-soluble vitamin required for the function of carboxylases as well as for the regulation of gene expression. Here, we report that biotin accumulates in unusually large amounts in cells of arterial chemoreceptors, carotid body (CB) and adrenal medulla (AM). We show in a biotin-deficient rat model that the vitamin rapidly disappears from the blood and other tissues (including the AM), while remaining at relatively high levels in the CB. We have also observed that, in comparison with other peripheral neural tissues, CB cells contain high levels of SLC5a6, a biotin transporter, and SLC19a3, a thiamine transporter regulated by biotin. Biotin-deficient rats show a syndrome characterized by marked weight loss, metabolic lactic acidosis, aciduria and accelerated breathing with normal responsiveness to hypoxia. Remarkably, CB cells from biotin-deficient animals have normal electrophysiological and neurochemical (ATP levels and catecholamine synthesis) properties; however, they exhibit a marked decrease in the size of quantal catecholaminergic secretory events, which is not seen in AM cells. A similar differential secretory dysfunction is observed in CB cells treated with tetrabenazine, a selective inhibitor of the vesicular monoamine transporter 2 (VMAT2). VMAT2 is highly expressed in glomus cells (in comparison with VMAT1), and in biotin-deficient animals VMAT2 protein expression decreases in parallel with the decrease of biotin accumulated in CB cells. These data suggest that biotin has an essential role in the homeostasis of dopaminergic transmission modulating the transport and/or storage of transmitters within small secretory granules in glomus cells. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

Magnetic and transport properties of Ga-Mn-Co full Heusler alloy

NASA Astrophysics Data System (ADS)

Samanta, Tamalika; Bhobe, P. A.

2018-04-01

We report structural, electrical and magnetic studies of the Ga rich Heusler compound Ga48Mn25Co27. The Ga-Co-Mn compounds have been predicted to be useful candidates for spintronic applications. We found that the Ga48Mn25Co27 compound crystallizes in cubic L21 structure. It shows a very low curie temperature of 88 K and a soft magnetic behavior. We observed an unusual, non-saturating magnetic hysteresis loop where the virgin curve stays out of the loop. The origin of such behavior might lie in the fact that there exist two competing magnetic sub-lattices with different exchange interactions.

Phase coherent transport in hybrid superconductor-topological insulator devices

NASA Astrophysics Data System (ADS)

Finck, Aaron

2015-03-01

Heterostructures of superconductors and topological insulators are predicted to host unusual zero energy bound states known as Majorana fermions, which can robustly store and process quantum information. Here, I will discuss our studies of such heterostructures through phase-coherent transport, which can act as a unique probe of Majorana fermions. We have extensively explored topological insulator Josephson junctions through SQUID and single-junction diffraction patterns, whose unusual behavior give evidence for low-energy Andreev bound states. In topological insulator devices with closely spaced normal and superconducting leads, we observe prominent Fabry-Perot oscillations, signifying gate-tunable, quasi-ballistic transport that can elegantly interact with Andreev reflection. Superconducting disks deposited on the surface of a topological insulator generate Aharonov-Bohm-like oscillations, giving evidence for unusual states lying near the interface between the superconductor and topological insulator surface. Our results point the way towards sophisticated interferometers that can detect and read out the state of Majorana fermions in topological systems. This work was done in collaboration with Cihan Kurter, Yew San Hor, and Dale Van Harlingen. We acknowledge funding from Microsoft Project Q.

Superconducting properties of Ba(Fe1-xNix)2As2 thin films in high magnetic fields

NASA Astrophysics Data System (ADS)

Richter, Stefan; Kurth, Fritz; Iida, Kazumasa; Pervakov, Kirill; Pukenas, Aurimas; Tarantini, Chiara; Jaroszynski, Jan; Hänisch, Jens; Grinenko, Vadim; Skrotzki, Werner; Nielsch, Kornelius; Hühne, Ruben

2017-01-01

We report on the electrical transport properties of epitaxial Ba(Fe1-xNix)2As2 thin films grown by pulsed laser deposition in static magnetic fields up to 35 T. The thin film shows a critical temperature of 17.2 K and a critical current density of 5.7 × 105 A/cm2 in self field at 4.2 K, while the pinning is dominated by elastic pinning at two-dimensional nonmagnetic defects. Compared to the single-crystal data, we find a higher slope of the upper critical field for the thin film at a similar doping level and a small anisotropy. Also, an unusual small vortex liquid phase was observed at low temperatures, which is a striking difference to Co-doped BaFe2As2 thin films.

Electron transport properties of degenerate n-type GaN prepared by pulsed sputtering

NASA Astrophysics Data System (ADS)

Ueno, Kohei; Fudetani, Taiga; Arakawa, Yasuaki; Kobayashi, Atsushi; Ohta, Jitsuo; Fujioka, Hiroshi

2017-12-01

We report a systematic investigation of the transport properties of highly degenerate electrons in Ge-doped and Si-doped GaN epilayers prepared using the pulsed sputtering deposition (PSD) technique. Secondary-ion mass spectrometry and Hall-effect measurements revealed that the doping efficiency of PSD n-type GaN is close to unity at electron concentrations as high as 5.1 × 1020 cm-3. A record low resistivity for n-type GaN of 0.16 mΩ cm was achieved with an electron mobility of 100 cm2 V-1 s-1 at a carrier concentration of 3.9 × 1020 cm-3. We explain this unusually high electron mobility of PSD n-type GaN within the framework of conventional scattering theory by modifying a parameter related to nonparabolicity of the conduction band. The Ge-doped GaN films show a slightly lower electron mobility compared with Si-doped films with the same carrier concentrations, which is likely a consequence of the formation of a small number of compensation centers. The excellent electrical properties presented in this letter clearly demonstrate the striking advantages of the low-temperature PSD technique for growing high-quality and highly conductive n-type GaN.

Interfacial Coupling-Induced Ferromagnetic Insulator Phase in Manganite Film

DOE PAGES

Zhang, Bangmin; Wu, Lijun; Yin, Wei-Guo; ...

2016-06-08

Interfaces with subtle differences in atomic and electronic structures in perovskite ABO 3 heterostructures often yield intriguingly different properties, yet their exact roles remain elusive. Here, we report an integrated study of unusual transport, magnetic, and structural properties of Pr 0.67Sr 0.33MnO 3 film on SrTiO 3 substrate. The variations in the out-of-plane lattice constant and BO 6 octahedral rotation across the Pr 0.67Sr 0.33MnO 3/SrTiO 3 interface strongly depend on the thickness of the Pr 0.67Sr 0.33MnO 3 film. In the 12-nm film, a new interface-sensitive ferromagnetic polaronic insulator (FI') phase is formed during the cubic-to-tetragonal phase transition ofmore » SrTiO 3, apparently due to the enhanced electron–phonon interaction and atomic disorder in the film. The transport properties of the FI' phase in the 30-nm film are masked because of the reduced interfacial coupling and smaller interface-to-volume ratio. In conclusion, this work demonstrates how thickness-dependent interfacial coupling leads to the formation of a theoretically predicted ferromagnetic–polaronic insulator, as illustrated in a new phase diagram, that is otherwise ferromagnetic metal (FM) in bulk form.« less

Interfacial Coupling-Induced Ferromagnetic Insulator Phase in Manganite Film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Bangmin; Wu, Lijun; Yin, Wei-Guo

Interfaces with subtle differences in atomic and electronic structures in perovskite ABO 3 heterostructures often yield intriguingly different properties, yet their exact roles remain elusive. Here, we report an integrated study of unusual transport, magnetic, and structural properties of Pr 0.67Sr 0.33MnO 3 film on SrTiO 3 substrate. The variations in the out-of-plane lattice constant and BO 6 octahedral rotation across the Pr 0.67Sr 0.33MnO 3/SrTiO 3 interface strongly depend on the thickness of the Pr 0.67Sr 0.33MnO 3 film. In the 12-nm film, a new interface-sensitive ferromagnetic polaronic insulator (FI') phase is formed during the cubic-to-tetragonal phase transition ofmore » SrTiO 3, apparently due to the enhanced electron–phonon interaction and atomic disorder in the film. The transport properties of the FI' phase in the 30-nm film are masked because of the reduced interfacial coupling and smaller interface-to-volume ratio. In conclusion, this work demonstrates how thickness-dependent interfacial coupling leads to the formation of a theoretically predicted ferromagnetic–polaronic insulator, as illustrated in a new phase diagram, that is otherwise ferromagnetic metal (FM) in bulk form.« less

Absolute Negative Resistance Induced by Directional Electron-Electron Scattering in a Two-Dimensional Electron Gas

NASA Astrophysics Data System (ADS)

Kaya, Ismet I.

2007-03-01

A ballistic conductor is restricted to have positive three terminal resistance just as a Drude conductor. Intercarrier scattering does not influence the conductivity of the latter transport regime and does not exist in the former. However, as the electron energies increased, in the intermediate regime, single or few intercarrier scattering events starts to dominate the transport properties of a conductor with sufficiently small dimensions. A three-terminal device formed by two electrostatic barriers crossing an asymmetrically patterned two dimensional electron gas displays an unusual potential depression at the middle contact, yielding absolute negative resistance. The device displays momentum and current transfer ratios that far exceed unity. The observed reversal of the current or potential in the middle terminal is interpreted as the analog of Bernoulli's effect in a Fermi liquid. The results are explained by directional scattering of electrons in two dimensions.

5 CFR 591.304 - Criteria for determining remoteness.

Code of Federal Regulations, 2010 CFR

2010-01-01

... transportation (e.g., automobile, train, bus) is available on a daily basis and the duty post is 80 kilometers... impractical because the location of the duty post and available transportation are such that agency management... conditions of employment; or (3) Transportation may be accomplished only by boat, aircraft, or unusual...

Strain-modulated electronic and thermal transport properties of two-dimensional O-silica

NASA Astrophysics Data System (ADS)

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.

Strain-modulated electronic and thermal transport properties of two-dimensional O-silica.

PubMed

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.

Transport properties of the Ce xY 1-x Pt alloy system: Unusual concenration dependence of the Curie temperature

DOE PAGES

Očko, M.; Zadro, K.; Drobac, Đ.; ...

2016-11-16

Here, in order to study Kondo ferromagnetism of CePt, we have investigated the transport properties, resistivity and thermopower, of the Ce xY 1-xPt alloy system from 2 K to 320 K. The extracted magnetic contribution to the total resistivity cannot be scaled to the concentration and is much higher than in the Ce xLa 1-xPt alloy system. The maximum of the magnetic contribution of the resistivity moves to lower temperatures with decreasing the Ce content while the temperature of the minimum of the thermopower does not change with concentration. These two facts seem to be in contradiction. Usually one assumesmore » that these extrema represent the Kondo temperature. To the contrary, we show that the Kondo temperature increases with decreasing Ce content. The most intriguing observation in this alloy system is the linear relationship between the Curie temperature and the concentration of the Ce ions and, moreover, that it is the same as in Ce xLa 1-xPt. Lastly, this fact is in contradiction with the conventional picture of small moment Kondo magnetism.« less

Investigation of transport properties of ZnO/PbS heterojunction solar cells

NASA Astrophysics Data System (ADS)

Cheng, Yang; Whitaker, Michael D. C.; Whiteside, Vincent R.; Bumm, Lloyd A.; Sellers, Ian R.

Lead sulfide (PbS) and lead selenide (PbSe) colloidal quantum dots (CQDs) are considered as a potential candidate material for solar cell applications due to their large band gap tunability range (0.5 to 1.7 eV) and cost-effective solution based processing. A series of Glass/ITO/ZnO/PbS/MoO3/Au heterojunction solar cells were processed and analyzed. A stable (reproducible) 2% conversion efficiency under 1-sun is achieved based on the result of J - V measurements. Absorbance and external quantum efficiency (EQE) measurements clearly show photo-generated carrier extraction from PbS active layers in the solar cell. However, a non-ideal J - V behavior is observed in current-voltage measurements. This behavior may be attributed to a high density of trap states at the QD surface or defect states at the PbS/ZnO or ITO/ZnO interfaces. C-V and Impedance spectroscopy measurements are used to study this unusual behavior. These techniques could also help probe the transport properties and limitation of these heterojunction solar cells. This research is funded through NASA EPSCoR program Award # NNX13AN101A.

Mobile metallic domain walls in an all-in-all-out magnetic insulator

DOE PAGES

Ma, Eric Yue; Cui, Yong -Tao; Ueda, Kentaro; ...

2015-10-30

Magnetic domain walls are boundaries between regions with different configurations of the same magnetic order. In a magnetic insulator, where the magnetic order is tied to its bulk insulating property, it has been postulated that electrical properties are drastically different along the domain walls, where the order is inevitably disturbed. Here we report the discovery of highly conductive magnetic domain walls in a magnetic insulator, Nd 2Ir 2O 7, that has an unusual all-in-all-out magnetic order, via transport and spatially resolved microwave impedance microscopy. The domain walls have a virtually temperature-independent sheet resistance of ~1 kilohm per square, show smoothmore » morphology with no preferred orientation, are free from pinning by disorders, and have strong thermal and magnetic field responses that agree with expectations for all-in-all-out magnetic order.« less

Mobile metallic domain walls in an all-in-all-out magnetic insulator.

PubMed

Ma, Eric Yue; Cui, Yong-Tao; Ueda, Kentaro; Tang, Shujie; Chen, Kai; Tamura, Nobumichi; Wu, Phillip M; Fujioka, Jun; Tokura, Yoshinori; Shen, Zhi-Xun

2015-10-30

Magnetic domain walls are boundaries between regions with different configurations of the same magnetic order. In a magnetic insulator, where the magnetic order is tied to its bulk insulating property, it has been postulated that electrical properties are drastically different along the domain walls, where the order is inevitably disturbed. Here we report the discovery of highly conductive magnetic domain walls in a magnetic insulator, Nd2Ir2O7, that has an unusual all-in-all-out magnetic order, via transport and spatially resolved microwave impedance microscopy. The domain walls have a virtually temperature-independent sheet resistance of ~1 kilohm per square, show smooth morphology with no preferred orientation, are free from pinning by disorders, and have strong thermal and magnetic field responses that agree with expectations for all-in-all-out magnetic order. Copyright © 2015, American Association for the Advancement of Science.

High performance aluminum–cerium alloys for high-temperature applications

DOE PAGES

Sims, Zachary C.; Rios, Orlando R.; Weiss, David; ...

2017-08-01

Light-weight high-temperature alloys are important to the transportation industry where weight, cost, and operating temperature are major factors in the design of energy efficient vehicles. Aluminum alloys fill this gap economically but lack high-temperature mechanical performance. Alloying aluminum with cerium creates a highly castable alloy, compatible with traditional aluminum alloy additions, that exhibits dramatically improved high-temperature performance. These compositions display a room temperature ultimate tensile strength of 400 MPa and yield strength of 320 MPa, with 80% mechanical property retention at 240 °C. A mechanism is identified that addresses the mechanical property stability of the Al-alloys to at least 300more » °C and their microstructural stability to above 500 °C which may enable applications without the need for heat treatment. Lastly, neutron diffraction under load provides insight into the unusual mechanisms driving the mechanical strength.« less

Electronic and Optical Properties of a Semiconducting Spinel (Fe 2 CrO 4 )

DOE PAGES

Chambers, Scott A.; Droubay, Timothy C.; Kaspar, Tiffany C.; ...

2017-01-13

Epitaxial chromium ferrite (Fe 2CrO 4), prepared by state-of-the-art oxygen plasma assisted molecular beam epitaxy, is shown to exhibit unusual electronic transport properties driven by the crystallographic structure and composition of the material. By replacing 1/3 of the Fe cations with Cr converts the host ferrimagnet from a metal into a semiconductor by virtue of its fixed valence (3+); Cr substitutes for Fe at B sites in the spinel lattice. Conversely, replacing 2/3 of the Fe cations with Cr results in an insulator. Three candidate conductive paths, all involving electron hopping between Fe 2+ and Fe 3+, are identified inmore » Fe 2CrO 4. Moreover, Fe 2CrO 4 is shown to be photoconductive across the visible portion of the electromagnetic spectrum. As a result, this material is of potential interest for important photo-electrochemical processes such as water splitting.« less

Superconductivity in multiple phases of compressed GeS b2T e4

NASA Astrophysics Data System (ADS)

Greenberg, E.; Hen, B.; Layek, Samar; Pozin, I.; Friedman, R.; Shelukhin, V.; Rosenberg, Y.; Karpovski, M.; Pasternak, M. P.; Sterer, E.; Dagan, Y.; Rozenberg, G. Kh.; Palevski, A.

2017-02-01

Here we report the discovery of superconductivity in multiple phases of the compressed GeS b2T e4 (GST) phase change memory alloy, which has attracted considerable attention for the last decade due to its unusual physical properties with many potential applications. Superconductivity is observed through electrical transport measurements, both for the amorphous (a -GST) and for the crystalline (c -GST) phases. The superconducting critical temperature Tc continuously increases with applied pressure, reaching a maximum Tc=6 K at P =20 GPa for a -GST, whereas the critical temperature of the cubic phase reaches a maximum Tc=8 K at 30 GPa. This material system, exhibiting a superconductor-insulator quantum phase transition, has an advantage over disordered metals since it has a continuous control of the crystal structure and the electronic properties using pressure as an external stimulus.

Unusual magnetoresistance in cubic B20 Fe 0.85Co 0.15Si chiral magnets

DOE PAGES

Huang, S. X.; Chen, Fei; Kang, Jian; ...

2016-06-24

The B20 chiral magnets with broken inversion symmetry and C 4 rotation symmetry have attracted much attention. The broken inversion symmetry leads to the Dzyaloshinskii–Moriya that gives rise to the helical and Skyrmion states.Wereport the unusual magnetoresistance (MR) of B20 chiral magnet Fe 0.85Co 0.15Si that directly reveals the broken C 4 rotation symmetry and shows the anisotropic scattering by Skyrmions with respect to the current directions. The intimacy between unusual MR and broken symmetry is well confirmed by theoretically studying an effective Hamiltonian with spin–orbit coupling. In conclusion, the unusual MR serves as a transport signature for the Skyrmionmore » phase.« less

Transport and Magnetization in Bad Metals Itinerant Ferromagnets

NASA Astrophysics Data System (ADS)

Klein, Lior

1997-03-01

While much attention has been given to the study of itinerant ferromagnets that are good metals (k_Fl >> 1), very little is known about the transport properties of itinerant ferromagnets in the badly metallic limit (k_Fl= \\cal O ). Here we present our study of the pseudo-cubic perovskite SrRuO3 which is in the limit of k_Fl= \\cal O (1) in its purest form (e.g. single crystals) and is also an itinerant ferromagnet with Tc ~ 160 K. We findfootnote L. Klein, J. S. Dodge, C. H. Ahn, G. J. Snyder, T. H. Geballe, M. R. Beasley, and A. Kapitulnik, Phys. Rev. Lett. 77, 2774 (1996); L. Klein, J. S. Dodge, C. H. Ahn, J. W. Reiner, L. Mieville, T. H.Geballe, M. R. Beasley, and A. Kapitulnik, J. Phys. Condens. Matter 8, 10111 (1996). that while the magnetic properties of SrRuO3 in the paramagnetic phase, near the ferromagnetic phase transition and at low temperatures are normal and similar to those of iron or nickel, the transport properties sharply deviate from those of good metallic ferromagnets: a) As Tarrow T_c^+ the temperature derivative of the magnetic part of the resistivity, dρ _m/dT, diverges with an exponent on the order of 1, an order of magnitude larger than the expected specific heat exponent of ~ 0.1. b) While the critical behavior of dρ _m/dT around Tc is usually found to be symmetric, very weak divergence of dρ _m/dT is observed as Tarrow T_c^-. c) At low temperatures ρ rapidly increases in correlation with the magnetization instead of the usually observed T^2 dependence. d) At T < 4 K for low-residual-resistivity films, and at higher temperatures for high-residual-resistivity films, Kondo-like resistivity minima are observed. We conjecture that the distinct transport behavior of SrRuO3 is related to its being a 'bad metal' in the k_Fl= \\cal O (1) limit, and discuss the possible relevance of our results to the unusual transport properties of other 'bad metals' such as high-temperature superconductors, fullerenes and organic conductors.

The ATP-binding cassette transporter Cbc (choline/betaine/carnitine) recruits multiple substrate-binding proteins with strong specificity for distinct quaternary ammonium compounds

PubMed Central

Chen, Chiliang; Malek, Adel A.; Wargo, Matthew J.; Hogan, Deborah A.; Beattie, Gwyn A.

2017-01-01

Summary We identified a choline, betaine and carnitine transporter, designated Cbc, from Pseudomonas syringae and Pseudomonas aeruginosa that is unusual among members of the ATP-binding cassette (ABC) transporter family in its use of multiple periplasmic substrate-binding proteins (SBPs) that are highly specific for their substrates. The SBP encoded by the cbcXWV operon, CbcX, binds choline with a high affinity (Km, 2.6 μM) and, although it also binds betaine (Km, 24.2 μM), CbcXWV-mediated betaine uptake did not occur in the presence of choline. The CbcX orthologue ChoX from Sinorhizobium meliloti was similar to CbcX in these binding properties. The core transporter CbcWV also interacts with the carnitine-specific SBP CaiX (Km, 24 μM) and the betaine-specific SBP BetX (Km, 0.6 μM). Unlike most ABC transporter loci, caiX, betX and cbcXWV are separated in the genome. CaiX-mediated carnitine uptake was reduced by CbcX and BetX only when they were bound by their individual ligands, providing the first in vivo evidence for a higher affinity for ligand-bound than ligand-free SBPs by an ABC transporter. These studies demonstrate not only that the Cbc transporter serves as a useful model for exploring ABC transporter component interactions, but also that the orphan SBP genes common to bacterial genomes can encode functional SBPs. PMID:19919675

The ATP-binding cassette transporter Cbc (choline/betaine/carnitine) recruits multiple substrate-binding proteins with strong specificity for distinct quaternary ammonium compounds.

PubMed

Chen, Chiliang; Malek, Adel A; Wargo, Matthew J; Hogan, Deborah A; Beattie, Gwyn A

2010-01-01

We identified a choline, betaine and carnitine transporter, designated Cbc, from Pseudomonas syringae and Pseudomonas aeruginosa that is unusual among members of the ATP-binding cassette (ABC) transporter family in its use of multiple periplasmic substrate-binding proteins (SBPs) that are highly specific for their substrates. The SBP encoded by the cbcXWV operon, CbcX, binds choline with a high affinity (K(m), 2.6 microM) and, although it also binds betaine (K(m), 24.2 microM), CbcXWV-mediated betaine uptake did not occur in the presence of choline. The CbcX orthologue ChoX from Sinorhizobium meliloti was similar to CbcX in these binding properties. The core transporter CbcWV also interacts with the carnitine-specific SBP CaiX (K(m), 24 microM) and the betaine-specific SBP BetX (K(m), 0.6 microM). Unlike most ABC transporter loci, caiX, betX and cbcXWV are separated in the genome. CaiX-mediated carnitine uptake was reduced by CbcX and BetX only when they were bound by their individual ligands, providing the first in vivo evidence for a higher affinity for ligand-bound than ligand-free SBPs by an ABC transporter. These studies demonstrate not only that the Cbc transporter serves as a useful model for exploring ABC transporter component interactions, but also that the orphan SBP genes common to bacterial genomes can encode functional SBPs.

Observation of unusual topological surface states in half-Heusler compounds LnPtBi (Ln=Lu, Y)

DOE PAGES

Liu, Z. K.; Yang, L. X.; Wu, S. -C.; ...

2016-09-27

Topological quantum materials represent a new class of matter with both exotic physical phenomena and novel application potentials. Many Heusler compounds, which exhibit rich emergent properties such as unusual magnetism, superconductivity and heavy fermion behaviour, have been predicted to host non-trivial topological electronic structures. The coexistence of topological order and other unusual properties makes Heusler materials ideal platform to search for new topological quantum phases (such as quantum anomalous Hall insulator and topological superconductor). By carrying out angle-resolved photoemission spectroscopy and ab initio calculations on rare-earth half-Heusler compounds LnPtBi (Ln=Lu, Y), we directly observe the unusual topological surface states onmore » these materials, establishing them as first members with non-trivial topological electronic structure in this class of materials. Moreover, as LnPtBi compounds are non-centrosymmetric superconductors, our discovery further highlights them as promising candidates of topological superconductors.« less

Observation of unusual topological surface states in half-Heusler compounds LnPtBi (Ln=Lu, Y)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Z. K.; Yang, L. X.; Wu, S. -C.

Topological quantum materials represent a new class of matter with both exotic physical phenomena and novel application potentials. Many Heusler compounds, which exhibit rich emergent properties such as unusual magnetism, superconductivity and heavy fermion behaviour, have been predicted to host non-trivial topological electronic structures. The coexistence of topological order and other unusual properties makes Heusler materials ideal platform to search for new topological quantum phases (such as quantum anomalous Hall insulator and topological superconductor). By carrying out angle-resolved photoemission spectroscopy and ab initio calculations on rare-earth half-Heusler compounds LnPtBi (Ln=Lu, Y), we directly observe the unusual topological surface states onmore » these materials, establishing them as first members with non-trivial topological electronic structure in this class of materials. Moreover, as LnPtBi compounds are non-centrosymmetric superconductors, our discovery further highlights them as promising candidates of topological superconductors.« less

Unusual Entropy of Adsorbed Methane on Zeolite-Templated Carbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stadie, Nicholas P.; Murialdo, Maxwell; Ahn, Channing C.

2015-11-25

Methane adsorption at high pressures and across a wide range of temperatures was investigated on the surface of three porous carbon adsorbents with complementary structural properties. The measured adsorption equilibria were analyzed using a method that can accurately account for nonideal fluid properties and distinguish between absolute and excess quantities of adsorption, and that also allows the direct calculation of the thermodynamic potentials relevant to adsorption. On zeolite-templated carbon (ZTC), a material that exhibits extremely high surface area with optimal pore size and homogeneous structure, methane adsorption occurs with unusual thermodynamic properties that are greatly beneficial for deliverable gas storage:more » an enthalpy of adsorption that increases with site occupancy, and an unusually low entropy of the adsorbed phase. The origin of these properties is elucidated by comparison of the experimental results with a statistical mechanical model. The results indicate that temperature-dependent clustering (i.e., reduced configurations) of the adsorbed phase due to enhanced lateral interactions can account for the peculiarities of methane adsorbed on ZTC.« less

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

NASA Astrophysics Data System (ADS)

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

2016-03-01

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 researches in these fields.

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

PubMed

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 researches in these fields.

Functional electronic inversion layers at ferroelectric domain walls

NASA Astrophysics Data System (ADS)

Mundy, J. A.; Schaab, J.; Kumagai, Y.; Cano, A.; Stengel, M.; Krug, I. P.; Gottlob, D. M.; Doğanay, H.; Holtz, M. E.; Held, R.; Yan, Z.; Bourret, E.; Schneider, C. M.; Schlom, D. G.; Muller, D. A.; Ramesh, R.; Spaldin, N. A.; Meier, D.

2017-06-01

Ferroelectric domain walls hold great promise as functional two-dimensional materials because of their unusual electronic properties. Particularly intriguing are the so-called charged walls where a polarity mismatch causes local, diverging electrostatic potentials requiring charge compensation and hence a change in the electronic structure. These walls can exhibit significantly enhanced conductivity and serve as a circuit path. The development of all-domain-wall devices, however, also requires walls with controllable output to emulate electronic nano-components such as diodes and transistors. Here we demonstrate electric-field control of the electronic transport at ferroelectric domain walls. We reversibly switch from resistive to conductive behaviour at charged walls in semiconducting ErMnO3. We relate the transition to the formation--and eventual activation--of an inversion layer that acts as the channel for the charge transport. The findings provide new insight into the domain-wall physics in ferroelectrics and foreshadow the possibility to design elementary digital devices for all-domain-wall circuitry.

Optical properties of two-dimensional charge density wave materials

NASA Astrophysics Data System (ADS)

Sayers, Charles; Karbassi, Sara; Friedemann, Sven; da Como, Enrico

Titanium diselenide (TiSe2) is a member of the layered transition metal dichalcogenide (TMD) materials. It exhibits unusual chiral charge ordering below 190 K after undergoing an initial phase transition to a commensurate (2 x 2 x 2) charge density wave (CDW) at 200 K which is enhanced further in the monolayer. Recently, the first evidence of chirality in a CDW system was discovered in this material by scanning tunneling microscopy and time-resolved reflectivity experiments, where separate left and right handed charge-ordered domains were found to exist within a single sample. We have prepared single crystals of 1T-TiSe2 using iodine vapour transport, and confirmed their quality by x-ray analysis and charge transport measurements. Using a combination of polarised optical spectroscopy techniques in the mid to far infrared (4 to 700 meV photon energy), we have measured an anisotropy relating to the CDW gap. We discuss the results on the basis of chiral domains with different handedness and the nature of the CDW transition.

Next Generation Epigenetic Detection Technique: Identifying Methylated DNA using Graphene Nanopore

NASA Astrophysics Data System (ADS)

Ahmed, Towfiq; Haraldsen, Jason T.; Zhu, Jian-Xin; Balatsky, A. V.

2014-03-01

DNA methylation plays a pivotal role in the genetic evolution of both embryonic and adult cells.Unusual methylation on CPG islands are identified as the prime causes for silencing the tumor suppressant genes. Early detection of such methylation can diagnose the potentially harmful oncogenic evolution of cells, and provide a promising guideline for cancer prevention.We propose a detection technique and calculate the transport current through punctured graphene as the cytosine and methylated cytosine translocate through the nanopore. We also calculate the transport properties for uracil and cyano-cytosine to compare. Our calculations of transmission, current and tunneling conductance show distinct signatures in their spectrum for each molecular type. Our theoretical study provides a next generation detection technique for identifying DNA methylation using graphene based nanopore device. This work was supported by U.S. DOE Office of Basic Energy Sciences, and by VR 621-2012-2983 and ERC 321031-DM. This work was, in part, supported by the Center for Integrated Nanotechnologies, a U.S. DOE BES user facility.

Differential expression and alternative splicing of rice sulphate transporter family members regulate sulphur status during plant growth, development and stress conditions.

PubMed

Kumar, Smita; Asif, Mehar Hasan; Chakrabarty, Debasis; Tripathi, Rudra Deo; Trivedi, Prabodh Kumar

2011-06-01

Sulphur, an essential nutrient required for plant growth and development, is mainly taken up by the plants as inorganic sulphate from the soil and assimilated into the sulphur reductive pathway. The uptake and transport of sulphate in plants is carried out by transporters encoded by the sulphate transporter gene family. Plant sulphate transporters have been classified with respect to their protein sequences, kinetic properties and tissue-specific localization in Arabidopsis. Though sulphate transporter genes from few other plants have also been characterized, no detailed study with respect to the structure and expression of this family from rice has been carried out. Here, we present genome-wide identification, structural and expression analyses of the rice sulphate transporter gene family. Our analysis using microarray data and MPSS database suggests that 14 rice sulphate transporters are differentially expressed during growth and development in various tissues and during biotic and abiotic stresses. Our analysis also suggests differential accumulation of splice variants of OsSultr1;1 and OsSultr4;1 transcripts during these processes. Apart from known spliced variants, we report an unusual alternative splicing of OsSultr1;1 transcript related to sulphur supply in growth medium and during stress response. Taken together, our study suggests that differential expression and alternative splicing of members of the sulphate transporter family plays an important role in regulating cellular sulphur status required for growth and development and during stress conditions. These findings significantly advance our understanding of the posttranscriptional regulatory mechanisms operating to regulate sulphur demand by the plant.

49 CFR 174.20 - Local or carrier restrictions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 2 2011-10-01 2011-10-01 false Local or carrier restrictions. 174.20 Section 174... General Requirements § 174.20 Local or carrier restrictions. (a) When local conditions make the acceptance, transportation, or delivery of hazardous materials unusually hazardous, local restrictions may be imposed by the...

49 CFR 174.20 - Local or carrier restrictions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Local or carrier restrictions. 174.20 Section 174... General Requirements § 174.20 Local or carrier restrictions. (a) When local conditions make the acceptance, transportation, or delivery of hazardous materials unusually hazardous, local restrictions may be imposed by the...

Evidence of Electron-Hole Imbalance in WTe2 from High-Resolution Angle-Resolved Photoemission Spectroscopy

NASA Astrophysics Data System (ADS)

Wang, Chen-Lu; Zhang, Yan; Huang, Jian-Wei; Liu, Guo-Dong; Liang, Ai-Ji; Zhang, Yu-Xiao; Shen, Bing; Liu, Jing; Hu, Cheng; Ding, Ying; Liu, De-Fa; Hu, Yong; He, Shao-Long; Zhao, Lin; Yu, Li; Hu, Jin; Wei, Jiang; Mao, Zhi-Qiang; Shi, You-Guo; Jia, Xiao-Wen; Zhang, Feng-Feng; Zhang, Shen-Jin; Yang, Feng; Wang, Zhi-Min; Peng, Qin-Jun; Xu, Zu-Yan; Chen, Chuang-Tian; Zhou, Xing-Jiang

2017-08-01

WTe2 has attracted a great deal of attention because it exhibits extremely large and nonsaturating magnetoresistance. The underlying origin of such a giant magnetoresistance is still under debate. Utilizing laser-based angle-resolved photoemission spectroscopy with high energy and momentum resolutions, we reveal the complete electronic structure of WTe2. This makes it possible to determine accurately the electron and hole concentrations and their temperature dependence. We find that, with increasing the temperature, the overall electron concentration increases while the total hole concentration decreases. It indicates that the electron-hole compensation, if it exists, can only occur in a narrow temperature range, and in most of the temperature range there is an electron-hole imbalance. Our results are not consistent with the perfect electron-hole compensation picture that is commonly considered to be the cause of the unusual magnetoresistance in WTe2. We identified a flat band near the Brillouin zone center that is close to the Fermi level and exhibits a pronounced temperature dependence. Such a flat band can play an important role in dictating the transport properties of WTe2. Our results provide new insight on understanding the origin of the unusual magnetoresistance in WTe2.

UV-Vis-NIR spectroelectrochemical and in situ conductance studies of unusual stability of n- and p-doped poly(dimethyldioctylquaterthiophene-alt-oxadiazole) under high cathodic and anodic polarizations.

PubMed

Pomerantz, Z; Levi, M D; Salitra, G; Demadrille, R; Fisyuk, A; Zaban, A; Aurbach, D; Pron, A

2008-02-21

Combined CV studies and UV-Vis-NIR spectroelectrochemical investigations revealed an unusual stability of the p- and n-doped PMOThOD in the wide potential window of 4 V. The n-doping process occurs in this polymer down to -2.7 V (vs. Ag/Ag+) in a non-destructive way with the characteristic development of the omega3 transition as a function of the doping level. In situ electronic transport studies revealed a high conductivity of the n-doped polymer which implies high mobility of the negatively charged carriers in the freshly doped PMOThOD film electrodes. An increase in the cathodic polarization, long-term cycling of the film electrodes, especially of higher thickness, results in a growing contribution of the negatively charged carriers trapping to the redox properties of the PMOThOD. The trapping of the charged carriers reduces gradually the electronic conductance of the PMOThOD film, but its effect on the redox-capacity of the film (in a typical scan rates range up to 50 mV s(-1)) is only minor.

Tuning the Solid Electrolyte Interphase for Selective Li- and Na-Ion Storage in Hard Carbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soto, Fernando A.; Yan, Pengfei; Engelhard, Mark H.

Solid-electrolyte interphase (SEI) films with controllable properties are highly desirable for improving battery performance. In this paper, a combined experimental and theoretical approach is used to study SEI films formed on hard carbon in Li- and Na-ion batteries. It is shown that a stable SEI layer can be designed by precycling an electrode in a desired Li- or Na-based electrolyte, and that ionic transport can be kinetically controlled. Selective Li- and Na-based SEI membranes are produced using Li- or Na-based electrolytes, respectively. The Na-based SEI allows easy transport of Li ions, while the Li-based SEI shuts off Na-ion transport. Na-ionmore » storage can be manipulated by tuning the SEI layer with film-forming electrolyte additives, or by preforming an SEI layer on the electrode surface. The Na specific capacity can be controlled to < 25 mAh g(-1); approximate to 1/10 of the normal capacity (250 mAh g(-1)). Unusual selective/ preferential transport of Li ions is demonstrated by preforming an SEI layer on the electrode surface and corroborated with a mixed electrolyte. This work may provide new guidance for preparing good ion-selective conductors using electrochemical approaches.« less

Structure and properties during aging of an ultra-high strength Al-Cu-Li-Ag-Mg alloy

NASA Technical Reports Server (NTRS)

Gayle, Frank W.; Heubaum, Frank H.; Pickens, Joseph R.

1990-01-01

The structure and properties of the strengthening phases formed during aging in an Al-Cu-Li-Ag-Mg alloy (Weldalite 049) were elulcidated, by following the development of the microstructure by means of TEM. The results of observations showed that the Weldalite 049 alloy has a series of unusual and technologically useful combinations of mechanical properties in different aging conditions, such as natural aging without prior cold work to produce high strengths, a reversion temper of lower yield strength and unusually high ductility, a room temperature reaging of the reversion temper eventually leading to the original T4 hardness, and ultrahigh-strength T6 properties.

Unusual Sediment Transportation Processes Under Low Pressure Environments and Implications For Gullies and Recurring Slope Lineae (RSL)

NASA Astrophysics Data System (ADS)

Raack, J.; Herny, C.; Conway, S. J.; Balme, M. R.; Carpy, S.; Patel, M.

2017-12-01

Recently and presently active mass wasting features such as gullies and recurring slope lineae (RSL) are common on the surface of Mars, but their origin and triggering mechanisms are under intense debate. While several active mass wasting features have been linked to sublimation of CO2ice, dry granular flows (avalanches), or a combination of both effects, others have been more closely linked to liquid water or briny outflows (e.g. for RSL). However, liquid water on the surface of Mars is unstable under present-day low pressures and surface temperatures. Nevertheless, numerical modeling and remote sensing data have shown that maximum surface temperatures can exceed the frost point of water and that liquid water could exist on the surface of actual Mars in a transient state. But to explain the observed spatial extent of RSL and recent modification of gullies, it is estimated that relatively large amounts of liquid water are necessary. It is proving challenging to generate such quantities from the atmosphere. In this contribution we explore the potential effects of boiling water (boiling occurs at martian pressures slightly above the frost point of 273 K) on sediment transport. We will present the outcomes of a series of experiments under low surface and water temperatures (between 278 and 297 K, analogous to surface temperatures observed near RSL) and low pressures (between 8 and 11 mbar). We simulate sediment transport by boiling liquid water over a sloping bed of unconsolidated sediment. Our results reveal a suite of unusual and very reactive sediment transportation processes, which are not produced under terrestrial pressures. We will discuss the impact of these unusual sediment transport processes on estimates of water budgets for active mass wasting processes.

Unusual phonon behavior and ultra-low thermal conductance of monolayer InSe.

PubMed

Zhou, Hangbo; Cai, Yongqing; Zhang, Gang; Zhang, Yong-Wei

2017-12-21

Monolayer indium selenide (InSe) possesses numerous fascinating properties, such as high electron mobility, quantum Hall effect and anomalous optical response. However, its phonon properties, thermal transport properties and the origin of its structural stability remain unexplored. Using first-principles calculations, we show that the atoms in InSe are highly polarized and such polarization causes strong long-range dipole-dipole interaction (DDI). For acoustic modes, DDI is essential for maintaining its structural stability. For optical modes, DDI causes a significant frequency shift of its out-of-phase vibrations. Surprisingly, we observed that there were two isolated frequency regimes, which were completely separated from other frequency regimes with large frequency gaps. Within each frequency regime, only a single phonon mode exists. We further reveal that InSe possesses the lowest thermal conductance among the known two-dimensional materials due to the low cut-off frequency, low phonon group velocities and the presence of large frequency gaps. These unique behaviors of monolayer InSe can enable the fabrication of novel devices, such as thermoelectric module, single-mode phonon channel and phononic laser.

Improved thermoelectric performance of n-type Ca and Ca-Ce filled skutterudites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, Daniel R.; Liu, Chang; Ellison, Nicole D.

2014-12-28

Thermoelectric (TE) technology for use in automotive waste heat recovery is being advanced by General Motors with support from the US Department of Energy. Skutterudites are a very promising material for this application of TE technology due to their superior mechanical properties and good TE performance. Double-filled Yb{sub x}Ba{sub y}Co{sub 4}Sb{sub 12} with ZT values around 1.1 at 750 K are the best performing n-type skutterudites produced on a large scale using an economically viable approach of melt spinning (MS) in conjunction with spark plasma sintering (SPS). Another economical production method on the tons scale, the melt quench annealing (MQA) technique,more » has been recently claimed by Treibacher Industrie AG, further information is available [G. Rogl et al., Acta Mater. 76, 434–448 (2014)]. A possible hurdle to commercial implementation of these materials is the use of rare earths as the fillers to reduce thermal conductivity and improve the electrical transport properties. It will be shown herein that skutterudites double-filled with Ca and Ce, both of which are lower-cost fillers, display markedly different TE properties depending on whether they are produced by MQA or MS + SPS synthesis techniques. Ca and Ce double-filled skutterudites prepared by MS + SPS have TE properties that are superior to the same compositions prepared by MQA and that are comparable to the best performing Yb and Ba filled materials. Furthermore, the results of this study suggest that the unusually poor transport properties of MQA Ca-filled skutterudites can be ascribed to deleterious secondary phases, which is contrary to reports in the literature attempting to explain these irregularities via band structure features.« less

Improved thermoelectric performance of n-type Ca and Ca-Ce filled skutterudites

DOE PAGES

Thompson, Daniel R.; Liu, Chang; Ellison, Nicole D.; ...

2014-12-28

Thermoelectric (TE) technology for use in automotive waste heat recovery is being advanced by General Motors with support from the US Department of Energy. Skutterudites are a very promising material for this application of TE technology due to their superior mechanical properties and good TE performance. Double-filled Yb xBa yCo 4Sb 12 with ZT values around 1.1 at 750K are the best performing n-type skutterudites produced on a large scale using an economically viable approach of melt spinning (MS) in conjunction with spark plasma sintering (SPS). Another economical production method on the tons scale, the melt quench annealing (MQA) technique,more » has been recently claimed by Treibacher Industrie AG, further information is available [G. Rogl et al., Acta Mater. 76, 434-448 (2014)]. A possible hurdle to commercial implementation of these materials is the use of rare earths as the fillers to reduce thermal conductivity and improve the electrical transport properties. It will be shown herein that skutterudites double-filled with Ca and Ce, both of which are lower-cost fillers, display markedly different TE properties depending on whether they are produced by MQA or MS + SPS synthesis techniques. Finally, Ca and Ce double-filled skutterudites prepared by MS + SPS have TE properties that are superior to the same compositions prepared by MQA and that are comparable to the best performing Yb and Ba filled materials. Furthermore, the results of this study suggest that the unusually poor transport properties of MQA Ca-filled skutterudites can be ascribed to deleterious secondary phases, which is contrary to reports in the literature attempting to explain these irregularities via band structure features.« less

Unusual CoS2 ellipsoids with anisotropic tube-like cavities and their application in supercapacitors.

PubMed

Zhang, Lei; Wu, Hao Bin; Lou, Xiong Wen

2012-07-14

Unusual CoS(2) ellipsoids with anisotropic tube-like cavities have been synthesized from the simultaneous thermal decomposition and sulfidation of a preformed cobalt carbonate precursor. The as-prepared CoS(2) ellipsoids show interesting supercapacitive properties with high capacitance and good cycling performance.

48 CFR 50.104-3 - Special procedures for unusually hazardous or nuclear risks.

Code of Federal Regulations, 2010 CFR

2010-10-01

... identifying the risks insured against and the coverage extended to persons or property, or both; (C) Dollar... unusually hazardous or nuclear risks. 50.104-3 Section 50.104-3 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION CONTRACT MANAGEMENT EXTRAORDINARY CONTRACTUAL ACTIONS AND THE SAFETY ACT...

41 CFR 101-39.206 - Seasonal or unusual requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... VEHICLES 39-INTERAGENCY FLEET MANAGEMENT SYSTEMS 39.2-GSA Interagency Fleet Management System Services... requirements for vehicles or related services shall inform the GSA IFMS fleet management center as far in... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Seasonal or unusual...

Towards deployable meta-implants.

PubMed

Bobbert, F S L; Janbaz, S; Zadpoor, A A

2018-06-07

Meta-biomaterials exhibit unprecedented or rare combinations of properties not usually found in nature. Such unusual mechanical, mass transport, and biological properties could be used to develop novel categories of orthopedic implants with superior performance, otherwise known as meta-implants. Here, we use bi-stable elements working on the basis of snap-through instability to design deployable meta-implants. Deployable meta-implants are compact in their retracted state, allowing them to be brought to the surgical site with minimum invasiveness. Once in place, they are deployed to take their full-size load-bearing shape. We designed five types of meta-implants by arranging bi-stable elements in such a way to obtain a radially-deployable structure, three types of auxetic structures, and an axially-deployable structure. The intermediate stable conditions ( i.e. multi-stability features), deployment force, and stiffness of the meta-implants were found to be strongly dependent on the geometrical parameters of the bi-stable elements as well as on their arrangement.

Part-crystalline part-liquid state and electrical/thermal transport in materials with chemical-bond hierarchy

NASA Astrophysics Data System (ADS)

Zhang, Wenqng

2015-03-01

A concept of part-crystalline part-liquid state (or liquid-like), and even part-crystalline part-glass state (or glass-like), was demonstrated in some materials such as Cu3SbSe3 with chemical-bond-hierarchy, in which certain constituent species weakly bond to other part of the crystal. Such a material could intrinsically manifest the coexistence of rigid crystalline sublattices and other fluctuating noncrystalline sublattices with thermally induced large amplitude vibrations and even flow of the group of species atoms. The large-amplitude vibrations and movement of atoms can generate unusual severe phonon scattering and thermal damping due to the collective low-frequency vibrations similar to the Boson peak in amorphous or liquid materials. While different phase or state may have large energetic discrepancy, whether the thermally-induced part-crystalline state is undergoing phase transition becomes an interesting issue. In addition, our earlier work reported that second-order phase transition could induce extreme electron and phonon scattering in thermoelectrics. The above work clearly demonstrated that the unusual effect from structural fluctuations on thermal and electrical transport in thermoelectrics should be paid attention to. While materials with these structural changes can retain extremely low lattice thermal conductivity and unusual electron transport and become promising candidates for high-performance thermoelectrics, underlying mechanism is yet to be explored.

Taking their breath away: metabolic responses to low-oxygen levels in anchialine shrimps (Crustacea: Atyidae and Alpheidae).

PubMed

Havird, Justin C; Vaught, Rebecca C; Weeks, Jeffrey R; Fujita, Yoshihisa; Hidaka, Michio; Santos, Scott R; Henry, Raymond P

2014-12-01

Crustaceans generally act as oxy-regulators, maintaining constant oxygen uptake as oxygen partial pressures decrease, but when a critical low level is reached, ventilation and aerobic metabolism shut down. Cave-adapted animals, including crustaceans, often show a reduced metabolic rate possibly owing in part to the hypoxic nature of such environments. However, metabolic rates have not been thoroughly explored in crustaceans from anchialine habitats (coastal ponds and caves), which can experience variable oxygenic regimes. Here, an atypical oxy-conforming pattern of oxygen uptake is reported in the Hawaiian anchialine atyid Halocaridina rubra, along with other unusual metabolic characteristics. Ventilatory rates are near-maximal in normoxia and did not increase appreciably as PO₂ declined, resulting in a decline in VO₂ during progressive hypoxia. Halocaridina rubra maintained in anoxic waters survived for seven days (the duration of the experiment) with no measureable oxygen uptake, suggesting a reliance on anaerobic metabolism. Supporting this, lactate dehydrogenase activity was high, even in normoxia, and oxygen debts were quickly repaid by an unusually extreme increase in oxygen uptake upon exposure to normoxia. In contrast, four related anchialine shrimp species from the Ryukyu Islands, Japan, exhibited physiological properties consistent with previously studied crustaceans. The unusual respiratory patterns found in H. rubra are discussed in the context of a trade-off in gill morphology for osmoregulatory ion transport vs. diffusion of respiratory gasses. Future focus on anchialine species may offer novel insight into the diversity of metabolic responses to hypoxia and other physiological challenges experienced by crustaceans. Published by Elsevier Inc.

Drug transport by reconstituted P-glycoprotein in proteoliposomes. Effect of substrates and modulators, and dependence on bilayer phase state.

PubMed

Lu, P; Liu, R; Sharom, F J

2001-03-01

The P-glycoprotein multidrug transporter (Pgp) is an active efflux pump for chemotherapeutic drugs, natural products and hydrophobic peptides. Pgp is envisaged as a 'hydrophobic vacuum cleaner', and drugs are believed to gain access to the substrate binding sites from within the membrane, rather than from the aqueous phase. The intimate association of both Pgp and its substrates with the membrane suggests that its function may be regulated by the biophysical properties of the lipid bilayer. Using the high affinity fluorescent substrate tetramethylrosamine (TMR), we have monitored, in real time, transport in proteoliposomes containing reconstituted Pgp. The TMR concentration gradient generated by Pgp was collapsed by the addition of either the ATPase inhibitor, vanadate, or Pgp modulators. TMR transport by Pgp obeyed Michaelis--Menten kinetics with respect to both of its substrates. The Km for ATP was 0.48 mM, close to the K(m) for ATP hydrolysis, and the K(m) for TMR was 0.3 microM. TMR transport was inhibited in a concentration-dependent fashion by verapamil and cyclosporin A, and activated (probably by a positive allosteric effect) by the transport substrate colchicine. TMR transport by Pgp reconstituted into proteoliposomes composed of two synthetic phosphatidylcholines showed a highly unusual biphasic temperature dependence. The rate of TMR transport was relatively high in the rigid gel phase, reached a maximum at the melting temperature of the bilayer, and then decreased in the fluid liquid crystalline phase. This pattern of temperature dependence suggests that the rate of drug transport by Pgp may be dominated by partitioning of drug into the bilayer.

City transport of the future - the high speed pedestrian conveyor. Part 2: ergonomic considerations of complete conveyor systems.

PubMed

Browning, A C

1975-03-01

This is the second part of an article on an unusual form of passenger transport, the moving pavement or pedestrian conveyor running at speeds up to 16 km/h. Part 1, "Ergonomic considerations of acceleration, deceleration and transfer sections," was published in the December, 1974, issue.

Internal Wave Generation by Convection

NASA Astrophysics Data System (ADS)

Lecoanet, Daniel Michael

In nature, it is not unusual to find stably stratified fluid adjacent to convectively unstable fluid. This can occur in the Earth's atmosphere, where the troposphere is convective and the stratosphere is stably stratified; in lakes, where surface solar heating can drive convection above stably stratified fresh water; in the oceans, where geothermal heating can drive convection near the ocean floor, but the water above is stably stratified due to salinity gradients; possible in the Earth's liquid core, where gradients in thermal conductivity and composition diffusivities maybe lead to different layers of stable or unstable liquid metal; and, in stars, as most stars contain at least one convective and at least one radiative (stably stratified) zone. Internal waves propagate in stably stratified fluids. The characterization of the internal waves generated by convection is an open problem in geophysical and astrophysical fluid dynamics. Internal waves can play a dynamically important role via nonlocal transport. Momentum transport by convectively excited internal waves is thought to generate the quasi-biennial oscillation of zonal wind in the equatorial stratosphere, an important physical phenomenon used to calibrate global climate models. Angular momentum transport by convectively excited internal waves may play a crucial role in setting the initial rotation rates of neutron stars. In the last year of life of a massive star, convectively excited internal waves may transport even energy to the surface layers to unbind them, launching a wind. In each of these cases, internal waves are able to transport some quantity--momentum, angular momentum, energy--across large, stable buoyancy gradients. Thus, internal waves represent an important, if unusual, transport mechanism. This thesis advances our understanding of internal wave generation by convection. Chapter 2 provides an underlying theoretical framework to study this problem. It describes a detailed calculation of the internal gravity wave spectrum, using the Lighthill theory of wave excitation by turbulence. We use a Green's function approach, in which we convolve a convective source term with the Green's function of different internal gravity waves. The remainder of the thesis is a circuitous attempt to verify these analytical predictions. I test the predictions of Chapter 2 via numerical simulation. The first step is to identify a code suitable for this study. I helped develop the Dedalus code framework to study internal wave generation by convection. Dedalus can solve many different partial differential equations using the pseudo-spectral numerical method. In Chapter 3, I demonstrate Dedalus' ability to solve different equations used to model convection in astrophysics. I consider both the propagation and damping of internal waves, and the properties of low Rayleigh number convective steady states, in six different equation sets used in the astrophysics literature. This shows that Dedalus can be used to solve the equations of interest. Next, in Chapter 4, I verify the high accuracy of Dedalus by comparing it to the popular astrophysics code Athena in a standard Kelvin-Helmholtz instability test problem. Dedalus performs admirably in comparison to Athena, and provides a high standard for other codes solving the fully compressible Navier-Stokes equations. Chapter 5 demonstrates that Dedalus can simulate convective adjacent to a stably stratified region, by studying convective mixing near carbon flames. The convective overshoot and mixing is well-resolved, and is able to generate internal waves. Confident in Dedalus' ability to study the problem at hand, Chapter 6 describes simulations inspired by water experiments of internal wave generation by convection. The experiments exploit water's unusual property that its density maximum is at 4°C, rather than at 0°C. We use a similar equation of state in Dedalus, and study internal gravity waves generation by convection in a water-like fluid. We test two models of wave generation: bulk excitation (equivalent to the Lighthill theory described in Chapter 2), and surface excitation. We find the bulk excitation model accurately reproduces the waves generated in the simulations, validating the calculations of Chapter 2.

Experimental and simulation studies of pore scale flow and reactive transport associated with supercritical CO2 injection into brine-filled reservoir rocks (Invited)

NASA Astrophysics Data System (ADS)

DePaolo, D. J.; Steefel, C. I.; Bourg, I. C.

2013-12-01

This talk will review recent research relating to pore scale reactive transport effects done in the context of the Department of Energy-sponsored Energy Frontier Research Center led by Lawrence Berkeley National Laboratory with several other laboratory and University partners. This Center, called the Center for Nanoscale Controls on Geologic CO2 (NCGC) has focused effort on the behavior of supercritical CO2 being injected into and/or residing as capillary trapped-bubbles in sandstone and shale, with particular emphasis on the description of nanoscale to pore scale processes that could provide the basis for advanced simulations. In general, simulation of reservoir-scale behavior of CO2 sequestration assumes a number of mostly qualitative relationships that are defensible as nominal first-order descriptions of single-fluid systems, but neglect the many complications that are associated with a two-phase or three-phase reactive system. The contrasts in properties, and the mixing behavior of scCO2 and brine provide unusual conditions for water-rock interaction, and the NCGC has investigated the underlying issues by a combination of approaches including theoretical and experimental studies of mineral nucleation and growth, experimental studies of brine films, mineral wetting properties, dissolution-precipitation rates and infiltration patterns, molecular dynamic simulations and neutron scattering experiments of fluid properties for fluid confined in nanopores, and various approaches to numerical simulation of reactive transport processes. The work to date has placed new constraints on the thickness of brine films, and also on the wetting properties of CO2 versus brine, a property that varies between minerals and with salinity, and may also change with time as a result of the reactivity of CO2-saturated brine. Mineral dissolution is dependent on reactive surface area, which can be shown to vary by a large factor for various minerals, especially when correlated with interconnected pore space. High-resolution numerical simulations of reactive transport can ultimate lead to quantitative descriptions of pore scale chemistry and flow, and examples of recent developments will be presented. However, only a limited description of the processes can realistically be treated in such simulations, and only for chemically simple systems. Whether and when more complete simulations will be achievable is yet to be determined.

Rheological Characterization of Unusual DWPF Slurry Samples (U)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koopman, D. C.

2005-09-01

A study was undertaken to identify and clarify examples of unusual rheological behavior in Defense Waste Processing Facility (DWPF) simulant slurry samples. Identification was accomplished by reviewing sludge, Sludge Receipt and Adjustment Tank (SRAT) product, and Slurry Mix Evaporator (SME) product simulant rheological results from the prior year. Clarification of unusual rheological behavior was achieved by developing and implementing new measurement techniques. Development of these new methods is covered in a separate report, WSRC-TR-2004-00334. This report includes a review of recent literature on unusual rheological behavior, followed by a summary of the rheological measurement results obtained on a set ofmore » unusual simulant samples. Shifts in rheological behavior of slurries as the wt. % total solids changed have been observed in numerous systems. The main finding of the experimental work was that the various unusual DWPF simulant slurry samples exhibit some degree of time dependent behavior. When a given shear rate is applied to a sample, the apparent viscosity of the slurry changes with time rather than remaining constant. These unusual simulant samples are more rheologically complex than Newtonian liquids or more simple slurries, neither of which shows significant time dependence. The study concludes that the unusual rheological behavior that has been observed is being caused by time dependent rheological properties in the slurries being measured. Most of the changes are due to the effect of time under shear, but SB3 SME products were also changing properties while stored in sample bottles. The most likely source of this shear-related time dependence for sludge is in the simulant preparation. More than a single source of time dependence was inferred for the simulant SME product slurries based on the range of phenomena observed. Rheological property changes were observed on the time-scale of a single measurement (minutes) as well as on a time scale of hours to weeks. The unusual shape of the slurry flow curves was not an artifact of the rheometric measurement. Adjusting the user-specified parameters in the rheometer measurement jobs can alter the shape of the flow curve of these time dependent samples, but this was not causing the unusual behavior. Variations in the measurement parameters caused the time dependence of a given slurry to manifest at different rates. The premise of the controlled shear rate flow curve measurement is that the dynamic response of the sample to a change in shear rate is nearly instantaneous. When this is the case, the data can be fitted to a time independent rheological equation, such as the Bingham plastic model. In those cases where this does not happen, interpretation of the data is difficult. Fitting time dependent data to time independent rheological equations, such as the Bingham plastic model, is also not appropriate.« less

Glutathione Utilization by Candida albicans Requires a Functional Glutathione Degradation (DUG) Pathway and OPT7, an Unusual Member of the Oligopeptide Transporter Family

PubMed Central

Desai, Prashant Ramesh; Thakur, Anil; Ganguli, Dwaipayan; Paul, Sanjoy; Morschhäuser, Joachim; Bachhawat, Anand K.

2011-01-01

Candida albicans lacks the ability to survive within its mammalian host in the absence of endogenous glutathione biosynthesis. To examine the ability of this yeast to utilize exogenous glutathione, we exploited the organic sulfur auxotrophy of C. albicans met15Δ strains. We observed that glutathione is utilized efficiently by the alternative pathway of glutathione degradation (DUG pathway). The major oligopeptide transporters OPT1–OPT5 of C. albicans that were most similar to the known yeast glutathione transporters were not found to contribute to glutathione transport to any significant extent. A genomic library approach to identify the glutathione transporter of C. albicans yielded OPT7 as the primary glutathione transporter. Biochemical studies on OPT7 using radiolabeled GSH uptake revealed a Km of 205 μm, indicating that it was a high affinity glutathione transporter. OPT7 is unusual in several aspects. It is the most remote member to known yeast glutathione transporters, lacks the two highly conserved cysteines in the family that are known to be crucial in trafficking, and also has the ability to take up tripeptides. The transporter was regulated by sulfur sources in the medium. OPT7 orthologues were prevalent among many pathogenic yeasts and fungi and formed a distinct cluster quite remote from the Saccharomyces cerevisiae HGT1 glutathione transporter cluster. In vivo experiments using a systemic model of candidiasis failed to detect expression of OPT7 in vivo, and strains disrupted either in the degradation (dug3Δ) or transport (opt7Δ) of glutathione failed to show a defect in virulence. PMID:21994941

Unusual Enhancement in Intrinsic Thermal Conductivity of Multilayer Graphene by Tensile Strains

DOE PAGES

Kuang, Youdi; Lindsay, Lucas R.; Huang, Baoling

2015-01-01

High basal plane thermal conductivity k of multi-layer graphene makes it promising for thermal management applications. Here we examine the effects of tensile strain on thermal transport in this system. Using a first principles Boltzmann-Peierls equation for phonon transport approach, we calculate the room-temperature in-plane lattice k of multi-layer graphene (up to four layers) and graphite under different isotropic tensile strains. The calculated in-plane k of graphite, finite mono-layer graphene and 3-layer graphene agree well with previous experiments. The dimensional transitions of the intrinsic k and the extent of the diffusive transport regime from mono-layer graphene to graphite are presented.more » We find a peak enhancement of intrinsic k for multi-layer graphene and graphite with increasing strain and the largest enhancement amplitude is about 40%. In contrast the calculated intrinsic k with tensile strain decreases for diamond and diverges for graphene, we show that the competition between the decreased mode heat capacities and the increased lifetimes of flexural phonons with increasing strain contribute to this k behavior. Similar k behavior is observed for 2-layer hexagonal boron nitride systems, suggesting that it is an inherent thermal transport property in multi-layer systems assembled of purely two dimensional atomic layers. This study provides insights into engineering k of multi-layer graphene and boron nitride by strain and into the nature of thermal transport in quasi-two-dimensional and highly anisotropic systems.« less

Identification of Two Conserved Residues Involved in Copper Release from Chloroplast PIB-1-ATPases*

PubMed Central

Sautron, Emeline; Giustini, Cécile; Dang, ThuyVan; Moyet, Lucas; Salvi, Daniel; Crouzy, Serge; Rolland, Norbert; Catty, Patrice; Seigneurin-Berny, Daphné

2016-01-01

Copper is an essential transition metal for living organisms. In the plant model Arabidopsis thaliana, half of the copper content is localized in the chloroplast, and as a cofactor of plastocyanin, copper is essential for photosynthesis. Within the chloroplast, copper delivery to plastocyanin involves two transporters of the PIB-1-ATPases subfamily: HMA6 at the chloroplast envelope and HMA8 in the thylakoid membranes. Both proteins are high affinity copper transporters but share distinct enzymatic properties. In the present work, the comparison of 140 sequences of PIB-1-ATPases revealed a conserved region unusually rich in histidine and cysteine residues in the TMA-L1 region of eukaryotic chloroplast copper ATPases. To evaluate the role of these residues, we mutated them in HMA6 and HMA8. Mutants of interest were selected from phenotypic tests in yeast and produced in Lactococcus lactis for further biochemical characterizations using phosphorylation assays from ATP and Pi. Combining functional and structural data, we highlight the importance of the cysteine and the first histidine of the CX3HX2H motif in the process of copper release from HMA6 and HMA8 and propose a copper pathway through the membrane domain of these transporters. Finally, our work suggests a more general role of the histidine residue in the transport of copper by PIB-1-ATPases. PMID:27493208

Tuning the Solid Electrolyte Interphase for Selective Li- and Na-Ion Storage in Hard Carbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soto, Fernando A.; Yan, Pengfei; Engelhard, Mark H.

Solid-electrolyte interphase (SEI) with controllable properties are highly desirable to improve battery performance. In this paper, we use a combined experimental and simulation approach to study the SEI formation on hard carbon in Li and Na-ion batteries. We show that with proper additives, stable SEI can be formed on hard carbon by pre-cycling the electrode materials in Li or Na-ion electrolyte. Detailed mechanistic studies suggest that the ion transport in the SEI layer is kinetically controlled and can be tuned by the applied voltage. Selective Na and Li-ion SEI membranes are produced using the Na or Li-ion based electrolytes respectively.more » The large Na ion SEI allows easy transport of Li ions, while the small Li ion SEI shuts off the Na-ion transport. Na-ion storage can be manipulated by tuning the SEI with film-forming electrolyte additives or preforming a SEI on the electrodes’ surface. The Na specific capacity can be controlled to <25 mAh/g, ~1/10 of the normal capacity (250 mAh/g). Unusual selective/preferential transport of Li-ion is demonstrated by preforming a SEI on the electrode’s surface and corroborated with a mixed electrolyte. This work may provide new guidance for preparing good ion selective conductors using electrochemical approaches in the future.« less

Characterization of PM2.5 and identification of transported secondary and biomass burning contribution in Seoul, Korea.

PubMed

Kim, Yumi; Seo, Jihoon; Kim, Jin Young; Lee, Ji Yi; Kim, Hwajin; Kim, Bong Mann

2018-02-01

The chemical and seasonal characteristics of fine particulates in Seoul, Korea, were investigated based on 24-h integrated PM 2.5 measurements made over four 1-month periods in each season between October 2012 and September 2013. The four-season average concentration of PM 2.5 was 37 μg m -3 , and the major chemical components were secondary inorganic aerosol (SIA) species of sulfate, nitrate, and ammonium (49%), followed by organic matter (34%). The mass concentration and most of the chemical components of PM 2.5 showed clear seasonal variation, with a winter-high and summer-low pattern. The winter-to-summer sulfate ratio and the winter organic carbon (OC)-to-elemental carbon (EC) ratio were unusually high compared with those in previous studies. Strong correlations of both the sulfate level and the sulfur oxidation ratio with relative humidity, and between water-soluble OC (WSOC) and SIA in winter, suggest the importance of aqueous phase chemistry for secondary aerosols. A strong correlation between non-sea salt sulfate and Na + levels, a high Cl - /Na + ratio, and an unusual positive correlation between the nitrogen oxidation ratio and temperature during the winter indicate the influence of transported secondary emission sources from upwind urban areas and from China across the Yellow Sea. Despite the absence of local forest fires and the regulation of wood burning, a high levoglucosan concentration and its correlations with OC and WSOC indicate that Seoul was affected by biomass burning sources in the winter. The unusually high water-insoluble OC (WIOC)-to-EC ratio in winter implies additional transported combustion sources of WIOC. The strong correlation between WIOC and levoglucosan suggests the likely influence of transported biomass burning sources on the high WIOC/EC ratio during the winter.

Microfluidic systems and methods of transport and lysis of cells and analysis of cell lysate

DOEpatents

Culbertson, Christopher T.; Jacobson, Stephen C.; McClain, Maxine A.; Ramsey, J. Michael

2004-08-31

Microfluidic systems and methods are disclosed which are adapted to transport and lyse cellular components of a test sample for analysis. The disclosed microfluidic systems and methods, which employ an electric field to rupture the cell membrane, cause unusually rapid lysis, thereby minimizing continued cellular activity and resulting in greater accuracy of analysis of cell processes.

Microfluidic systems and methods for transport and lysis of cells and analysis of cell lysate

DOEpatents

Culbertson, Christopher T [Oak Ridge, TN; Jacobson, Stephen C [Knoxville, TN; McClain, Maxine A [Knoxville, TN; Ramsey, J Michael [Knoxville, TN

2008-09-02

Microfluidic systems and methods are disclosed which are adapted to transport and lyse cellular components of a test sample for analysis. The disclosed microfluidic systems and methods, which employ an electric field to rupture the cell membrane, cause unusually rapid lysis, thereby minimizing continued cellular activity and resulting in greater accuracy of analysis of cell processes.

Temporal variations in optical and microphysical properties of mineral dust and biomass burning aerosol derived from daytime Raman lidar observations over Warsaw, Poland

NASA Astrophysics Data System (ADS)

Janicka, Lucja; Stachlewska, Iwona S.; Veselovskii, Igor; Baars, Holger

2017-11-01

In July 2013, favorable weather conditions caused a severe events of advection of biomass burning particles of Canadian forest fires to Europe. The smoke layers were widely observed, especially in Western Europe. An unusual atmospheric aerosol composition was measured at the EARLINET site in Warsaw, Central Poland, during a short event that occurred between 11 and 21 UTC on 10th July 2013. Additionally to the smoke layer, mineral dust was detected in a separate layer. The long-range dust transport pathway followed an uncommon way; originating in Western Sahara, passing above middle Atlantic, and circulating over British Islands, prior to its arrival to Poland. An effective radius of 560 nm was obtained for Saharan dust over Warsaw. This relatively small effective radius is likely due to the long time of the transport. The aerosol-polarization-Raman PollyXT-UW lidar was used for a successful daytime Raman retrieval of the aerosol optical properties at selected times during this short event. The aerosol vertical structure during the inflow over Warsaw in terms of optical properties and depolarization was analyzed, indicating clear distinction of the layers. The microphysical properties were inverted from the lidar derived optical data for selected ranges as representing the smoke and the mineral dust. For smoke, the effective radius was in the range of 0.29-0.36 μm and the complex refractive index 1.36 + 0.008i, on average. For dust, the values of 0.33-0.56 μm and 1.56 + 0.004i were obtained. An evolution of the aerosol composition over Warsaw during the day was analyzed.

Low-Temperature Synthesis of New Ternary Chalcogenide Compounds of Copper, Gold, and Mercury Using Alkali Metal Polychalcogenide Fluxes

NASA Astrophysics Data System (ADS)

Park, Younbong

In last two decades great efforts have been exerted to find new materials with interesting optical, electrical, and catalytic properties. Metal chalcogenides have been studied extensively because of their interesting physical properties and rich structural chemistry, among the potential materials. Prior to this work, most known metal chalcogenides had been synthesized at high temperature (T > 500^circC). Intermediate temperature synthesis in solid state chemistry was seldom pursued because of the extremely slow diffusion rates between reactants. This intermediate temperature regime could be a new synthesis condition if one looks for new materials with unusual structural features and properties. Metastable or kinetically stable compounds can be stabilized in this intermediate temperature regime, in contrast to the thermodynamically stable high temperature compounds. Molten salts, especially alkali metal polychalcogenide fluxes, can provide a route for exploring new chalcogenide materials at intermediate temperatures. These fluxes are very reactive and melt as low as 145^circC (mp of K_2S_4). Using these fluxes as reaction media, we have encountered many novel chalcogenide compounds with unusual structures and interesting electrical properties (semiconductors to metallic conductors). Low-dimensional polychalcogenide compounds of alpha-ACuQ_4 (A = K, Cs; Q = S, Se), beta -KCuS_4, KAuQ_5 (Q = S, Se), K_3AuSe_ {13}, Na_3AuSe _8, and CsAuSe_3 exhibit the beautiful structural diversity and bonding flexibility of the polychalcogenide ligands. In addition, many novel chalcogenide compounds of Cu, Hg, and Au with low-dimensional structures. The preparation of novel mixed -valence Cu compounds, K_2Cu _5Te_5, Cs _3Cu_8Te_ {10}, Na_3Cu _4Se_4, K _3Cu_8S_4 Te_2, and KCu_4 S_2Te, which show interesting metallic properties, especially underscores the enormous potential of the molten salt method for the synthesis of new chalcogenide materials with interesting physical properties. The materials prepared in this study can be classified as a new class of chalcogenide compounds due to their unique structures. In this dissertation the synthesis, characterization with emphasis on structures, charge transport properties, and magnetic susceptibilities of the materials will be illustrated.

Another Demo of the Unusual Thermal Properties of Rubber

ERIC Educational Resources Information Center

Liff, Mark I.

2010-01-01

The unusual thermal behavior of rubbers, though discovered a long time ago, can still be mind-boggling for students and teachers who encounter this class of polymeric systems. Unlike other solids, stretched elastic polymers shrink upon heating. This is a manifestation of the Gough-Joule (G-J) effect. Joule in the 1850s studied the thermal behavior…

A gravitational lens candidate with an unusually red optical counterpart

NASA Technical Reports Server (NTRS)

Hewitt, J. N.; Turner, E. L.; Lawrence, C. R.; Schneider, D. P.; Brody, J. P.

1992-01-01

The properties of the strong radio source MG0414 + 0534 are described. It is found to display many of the properties expected in a gravitational lens system. At radio wavelengths and 0.5-arcsec resolution, MG0414 + 0534 is made up of four compact components whose unusual configuration and relative flux densities are similar to those found in confirmed four-image gravitational lens systems. At optical wavelengths three objects are detected, consistent with there being optical objects at the positions of the radio components, given the lower optical resolution. The radio and optical centroid positions agree within the astrometric errors, and the relative ordering of the fluxes is the same. The colors and radiooptical spectral indices are similar, but there are differences larger than the photometric errors and the measured variability (about 30 percent). Extinction by dust might simultaneously explain the unusually red color and the absence of light from a lens.

Thermoelectric properties of low-dimensional clathrates from first principles

NASA Astrophysics Data System (ADS)

Kasinathan, Deepa; Rosner, Helge

2011-03-01

Type-I inorganic clathrates are host-guest structures with the guest atoms trapped in the framework of the host structure. From a thermoelectric point of view, they are interesting because they are semiconductors with adjustable bandgaps. Investigations in the past decade have shown that type-I clathrates X8 Ga 16 Ge 30 (X = Ba, Sr, Eu) may have the unusual property of ``phonon glass-electron crystal'' for good thermoelectric materials. Among the known clathrates, Ba 8 Ga 16 Ge 30 has the highest figure of merit (ZT~1). To enable a more widespread usage of thermoelectric technology power generation and heating/cooling applications, ZT of at least 2-3 is required. Two different research approaches have been proposed for developing next generation thermoelectric materials: one investigating new families of advanced bulk materials, and the other studying low-dimensional materials. In our work, we concentrate on understanding the thermoelectric properties of the nanostructured Ba-based clathrates. We use semi-classical Boltzmann transport equations to calculate the various thermoelectric properties as a function of reduced dimensions. We observe that there exists a delicate balance between the electrical conductivity and the electronic part of the thermal conductivity in reduced dimensions. Insights from these results can directly be used to control particle size in nanostructuring experiments.

Mechanical and thermal properties of planetologically important ices

NASA Technical Reports Server (NTRS)

Croft, Steven K.

1987-01-01

Two squences of ice composition were proposed for the icy satellites: a dense nebula model and a solar nebula model. Careful modeling of the structure, composition, and thermal history of satellites composed of these various ices requires quantitative information on the density, compressibility, thermal expansion, heat capacity, and thermal conductivity. Equations of state were fitted to the density data of the molecular ices. The unusual thermal and mechanical properties of the molecular and binary ices suggest a larger range of phenomena than previously anticipated, sufficiently complex perhaps to account for many of the unusual geologic phenomena found on the icy satellites.

On-wire lithography-generated molecule-based transport junctions: a new testbed for molecular electronics.

PubMed

Chen, Xiaodong; Jeon, You-Moon; Jang, Jae-Won; Qin, Lidong; Huo, Fengwei; Wei, Wei; Mirkin, Chad A

2008-07-02

On-wire lithography (OWL) fabricated nanogaps are used as a new testbed to construct molecular transport junctions (MTJs) through the assembly of thiolated molecular wires across a nanogap formed between two Au electrodes. In addition, we show that one can use OWL to rapidly characterize a MTJ and optimize gap size for two molecular wires of different dimensions. Finally, we have used this new testbed to identify unusual temperature-dependent transport mechanisms for alpha,omega-dithiol terminated oligo(phenylene ethynylene).

Northern Shenandoah public mobility project evaluation

DOT National Transportation Integrated Search

2003-06-01

Developing new intelligent transportation systems to meet unusual challenges in rural areas where ITS implementation is limited is difficult in part because there are few similar examples to use as guides. In such situations, it is critical to conduc...

The unusual amino acid l-ergothioneine is a physiologic cytoprotectant

PubMed Central

Paul, BD; Snyder, SH

2010-01-01

Ergothioneine (ET) is an unusual sulfur-containing derivative of the amino acid, histidine, which is derived exclusively through the diet. Although ET was isolated a century ago, its physiologic function has not been clearly established. Recently, a highly specific transporter for ET (ETT) was identified in mammalian tissues, which explains abundant tissue levels of ET and implies a physiologic role. Using RNA interference, we depleted cells of its transporter. Cells lacking ETT are more susceptible to oxidative stress, resulting in increased mitochondrial DNA damage, protein oxidation and lipid peroxidation. ETT is concentrated in mitochondria, suggesting a specific role in protecting mitochondrial components such as DNA from oxidative damage associated with mitochondrial generation of superoxide. In combating cytotoxic effects of pyrogallol, a known superoxide generator, ET is as potent as glutathione. Because of its dietary origin and the toxicity associated with its depletion, ET may represent a new vitamin whose physiologic roles include antioxidant cytoprotection. PMID:19911007

Chemical and biological characterisation of nutraceutical compounds of broccoli.

PubMed

Moreno, D A; Carvajal, M; López-Berenguer, C; García-Viguera, C

2006-08-28

People's diet offers a greater and more diverse group of plant bioactives than do drugs, and they often do not realise that many drugs are derived from the compounds originally discovered in plant foods. Numerous epidemiological studies indicate that Brassica vegetables in general, and broccoli in particular, protect humans against cancer since they are rich sources of glucosinolates as well as possessing a high content of flavonoids, vitamins and mineral nutrients. One unusual phytotherapeutic role of broccoli is for skin diseases--the juice of the leaves is used to treat warts. However, the main use of broccoli stems from its health-promoting properties. Some criteria have been proposed to evaluate the possibilities of developing new "functional foods" to reduce the risk of specific cancers; largely in broccoli, which is associated with cancer protection. Processing conditions, transport, domestic cooking, etc., affect the health-promoting properties of broccoli and these have been widely studied. This review makes an in-depth study of the chemical and biological characterization of the phytochemicals of broccoli and the effects on the bioactive composition of broccoli.

Computational Search for Specific Magnetoelectronic Characteristics

NASA Astrophysics Data System (ADS)

Pickett, Warren E.

1997-08-01

Many aspects of the coupling between magnetic state (ferro- or antiferromagnetic) and the electronic properties of a material can be predicted reliably from local spin density (LSD) calculations. Such calculations are routinely used to interpret data, but so far little actual prediction of new materials has been attempted. We present here the application of LSD methods to look for half-metallic (HM) antiferromagnetic (AFM) compounds. These materials will have unusual properties, such as 100% spin-polarized transport with no net magnetic field, and the possibility of a novel type of superconductivity. The double perovskite crystal structure was chosen, due to some experience with it and its simplicity, and magnetic ions M',M'' were chosen in the expectation that their moments in the La_2M'M''O6 compound would be equal in magnitude and could be induced to align in an antiparallel manner, giving zero total magnetization. Results for six compounds, with magnetic ions chosen from the 3d transition series, will be described. Three HM AFM states have been found, as well as several HM ferromagnetic states.

Electronic evidence of temperature-induced Lifshitz transition and topological nature in ZrTe5

PubMed Central

Zhang, Yan; Wang, Chenlu; Yu, Li; Liu, Guodong; Liang, Aiji; Huang, Jianwei; Nie, Simin; Sun, Xuan; Zhang, Yuxiao; Shen, Bing; Liu, Jing; Weng, Hongming; Zhao, Lingxiao; Chen, Genfu; Jia, Xiaowen; Hu, Cheng; Ding, Ying; Zhao, Wenjuan; Gao, Qiang; Li, Cong; He, Shaolong; Zhao, Lin; Zhang, Fengfeng; Zhang, Shenjin; Yang, Feng; Wang, Zhimin; Peng, Qinjun; Dai, Xi; Fang, Zhong; Xu, Zuyan; Chen, Chuangtian; Zhou, X. J.

2017-01-01

The topological materials have attracted much attention for their unique electronic structure and peculiar physical properties. ZrTe5 has host a long-standing puzzle on its anomalous transport properties manifested by its unusual resistivity peak and the reversal of the charge carrier type. It is also predicted that single-layer ZrTe5 is a two-dimensional topological insulator and there is possibly a topological phase transition in bulk ZrTe5. Here we report high-resolution laser-based angle-resolved photoemission measurements on the electronic structure and its detailed temperature evolution of ZrTe5. Our results provide direct electronic evidence on the temperature-induced Lifshitz transition, which gives a natural understanding on underlying origin of the resistivity anomaly in ZrTe5. In addition, we observe one-dimensional-like electronic features from the edges of the cracked ZrTe5 samples. Our observations indicate that ZrTe5 is a weak topological insulator and it exhibits a tendency to become a strong topological insulator when the layer distance is reduced. PMID:28534501

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

PubMed

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-substituting biomaterials. Bone-substituting biomaterials aim to mimic bone properties. Although mimicking some of bone properties is feasible, biomaterials that could simultaneously mimic all or most of the relevant bone properties are rare. We used rational design and additive manufacturing to develop porous metallic biomaterials that exhibit an interesting combination of topological, mechanical, and mass transport properties. The topology of the developed biomaterials resembles that of trabecular bone including a mean curvature close to zero. Moreover, the developed biomaterials show an unusual combination of low elastic modulus to avoid stress shielding and high strength to provide mechanical support. The fatigue resistance of the developed biomaterials is also exceptionally high, while their permeability is in the range of values reported for bone. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

36 CFR Appendix A to Part 800 - Criteria for Council Involvement in Reviewing Individual section 106 Cases

Code of Federal Regulations, 2013 CFR

2013-07-01

... unusual or noteworthy importance or are a rare property type; or adverse effects to large numbers of... 36 Parks, Forests, and Public Property 3 2013-07-01 2012-07-01 true Criteria for Council... Property ADVISORY COUNCIL ON HISTORIC PRESERVATION PROTECTION OF HISTORIC PROPERTIES Pt. 800, App. A...

36 CFR Appendix A to Part 800 - Criteria for Council Involvement in Reviewing Individual section 106 Cases

Code of Federal Regulations, 2011 CFR

2011-07-01

... unusual or noteworthy importance or are a rare property type; or adverse effects to large numbers of... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Criteria for Council... Property ADVISORY COUNCIL ON HISTORIC PRESERVATION PROTECTION OF HISTORIC PROPERTIES Pt. 800, App. A...

36 CFR Appendix A to Part 800 - Criteria for Council Involvement in Reviewing Individual section 106 Cases

Code of Federal Regulations, 2010 CFR

2010-07-01

... unusual or noteworthy importance or are a rare property type; or adverse effects to large numbers of... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Criteria for Council... Property ADVISORY COUNCIL ON HISTORIC PRESERVATION PROTECTION OF HISTORIC PROPERTIES Pt. 800, App. A...

36 CFR Appendix A to Part 800 - Criteria for Council Involvement in Reviewing Individual section 106 Cases

Code of Federal Regulations, 2012 CFR

2012-07-01

... unusual or noteworthy importance or are a rare property type; or adverse effects to large numbers of... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Criteria for Council... Property ADVISORY COUNCIL ON HISTORIC PRESERVATION PROTECTION OF HISTORIC PROPERTIES Pt. 800, App. A...

36 CFR Appendix A to Part 800 - Criteria for Council Involvement in Reviewing Individual section 106 Cases

Code of Federal Regulations, 2014 CFR

2014-07-01

... unusual or noteworthy importance or are a rare property type; or adverse effects to large numbers of... 36 Parks, Forests, and Public Property 3 2014-07-01 2014-07-01 false Criteria for Council... Property ADVISORY COUNCIL ON HISTORIC PRESERVATION PROTECTION OF HISTORIC PROPERTIES Pt. 800, App. A...

Arxula adeninivorans (Blastobotrys adeninivorans) — A Dimorphic Yeast of Great Biotechnological Potential

NASA Astrophysics Data System (ADS)

Böer, Erik; Steinborn, Gerhard; Florschütz, Kristina; Körner, Martina; Gellissen, Gerd; Kunze, Gotthard

The dimorphic ascomycetous yeast Arxula adeninivorans exhibits some unusual properties. Being a thermo- and halotolerant species it is able to assimilate and ferment many compounds as sole carbon and/or nitrogen source. It utilises n-alkanes and is capable of degrading starch. Due to these unusual biochemical properties A. adeninivorans can be exploited as a gene donor for the production of enzymes with attractive biotechnological characteristics. Examples of A. adeninivorans-derived genes that are overexpressed include the ALIP1 gene encoding a secretory lipase, the AINV encoding invertase, the AXDH encoding xylitol dehydrogenase and the APHY encoding a secretory phosphatase with phytase activity.

Localization Transport in Granular and Nanoporous Carbon Systems.

NASA Astrophysics Data System (ADS)

Fung, Alex Weng Pui

Porous carbon materials have long since been used in industry to make capacitors and adsorption agents because of their high specific surface area. Although their adsorption properties have been extensively studied, we have not seen the same vigor in the investigation of their physical properties, which are important not only for providing complementary characterization methods, but also for understanding the physics which underlies the manufacturing process and motivates intelligent design of these materials. The study of the new physics in these novel nanoporous materials also straddles the scientific forefronts of nanodimensional and disordered systems. In this thesis, we study the structural and electrical properties of two nanoporous carbons, namely activated carbon fibers and carbon aerogels. Specifically, we perform Raman scattering, x-ray diffraction, magnetic susceptibility, electrical transport and magnetotransport experiments. Results from other experiments reported in the literature or communicated to us by our collaborators, such as porosity and surface area measurements by adsorption methods, electron spin resonance, transmission electron microscopy, mechanical properties measurements and so on, are also frequently used in this thesis for additional characterization information. By correlating all the relevant results, we obtain the structure -property relationships in these nanoporous materials. This study shows that the transport properties of these porous materials can be used on one hand for sensitive characterization of complex materials, and on the other hand, for observing interesting and unusual physical phenomena. For example, as-prepared nanoporous carbon systems, exhibit in their low-temperature electrical conductivity a universal temperature dependence which is characteristic of a granular metallic system, despite their morphological differences. By studying further the magnetoresistance in these carbon materials, it is found that the variable-range hopping mechanism cannot be totally disregarded in the understanding of the low-temperature conduction process in some granular metals having a similar morphology. In the transport study of the heat-treated activated carbon fibers, the surprising observation of a negative magnetoresistance at room temperature has also provided some insight into the weak localization phenomenon in the percolation limit. In particular, the effects of anomalous diffusion in a percolating system is now included in the calculations of the weak-localization corrections to the conductivity and magnetoresistance, yielding a new temperature dependence of the dephasing distance. These localization phenomena in the nanoporous carbon structures studied here are mostly understandable in terms of the existing theories for disordered systems, but their detailed interpretations often indicate problems and shortcomings in some of these theories, at times because the physical properties of the nanoporous carbon materials studied here are unique among disordered materials. Hence, nanoporous carbons belong to a distinct class of disordered systems in their own rights. In the field of transport in disordered systems, porous media also seem to have been an oversight of the general research community, although theoretical percolation studies have often touched upon systems with similar morphologies. This thesis presents a study of the transport behavior in nanoporous carbons over the full spectrum of disorder, controlled by heat treatment, starting from the strong localization regime, then crossing the metal-insulator transition, and finally to the weak localization limit. In each regime of disorder, the existing theories are either adapted, and when necessary, extended to explain the observed transport behavior in these fascinating materials. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-1690.).

Collapse of ferromagnetism in itinerant-electron system: A magnetic, transport properties, and high pressure study of (Hf,Ta)Fe2 compounds

NASA Astrophysics Data System (ADS)

Diop, L. V. B.; Kastil, J.; Isnard, O.; Arnold, Z.; Kamarad, J.

2014-10-01

The magnetism and transport properties were studied for Laves (Hf,Ta)Fe2 itinerant-electron compounds, which exhibit a temperature-induced first-order transition from the ferromagnetic (FM) to the antiferromagnetic (AFM) state upon heating. At finite temperatures, the field-induced metamagnetic phase transition between the AFM and FM has considerable effects on the transport properties of these model metamagnetic compounds. A large negative magnetoresistance of about 14% is observed in accordance with the metamagnetic transition. The magnetic phase diagram is determined for the Laves Hf1-xTaxFe2 series and its Ta concentration dependence discussed. An unusual behavior is revealed in the paramagnetic state of intermediate compositions, it gives rise to the rapid increase and saturation of the local spin fluctuations of the 3d electrons. This new result is analysed in the frame of the theory of Moriya. For a chosen composition Hf0.825Ta0.175Fe2, exhibiting such remarkable features, a detailed investigation is carried out under hydrostatic pressure up to 1 GPa in order to investigate the volume effect on the magnetic properties. With increasing pressure, the magnetic transition temperature TFM-AFM from ferromagnetic to antiferromagnetic order decreases strongly non-linearly and disappears at a critical pressure of 0.75 GPa. In the pressure-induced AFM state, the field-induced first-order AFM-FM transition appears and the complex temperature dependence of the AFM-FM transition field is explained by the contribution from both the magnetic and elastic energies caused by the significant temperature variation of the amplitude of the local Fe magnetic moment. The application of an external pressure leads also to the progressive decrease of the Néel temperature TN. In addition, a large pressure effect on the spontaneous magnetization MS for pressures below 0.45 GPa, dln(Ms)/dP = -6.3 × 10-2 GPa-1 was discovered. The presented results are consistent with Moriya's theoretical predictions and can significantly help to better understand the underlying physics of itinerant electron magnetic systems nowadays widely investigated for both fundamental and applications purposes.

Hybrid Organic–Inorganic Perovskites on the Move

PubMed Central

2016-01-01

Conspectus Hybrid organic–inorganic perovskites (HOIPs) are crystals with the structural formula ABX3, where A, B, and X are organic and inorganic ions, respectively. While known for several decades, HOIPs have only in recent years emerged as extremely promising semiconducting materials for solar energy applications. In particular, power-conversion efficiencies of HOIP-based solar cells have improved at a record speed and, after only little more than 6 years of photovoltaics research, surpassed the 20% threshold, which is an outstanding result for a solution-processable material. It is thus of fundamental importance to reveal physical and chemical phenomena that contribute to, or limit, these impressive photovoltaic efficiencies. To understand charge-transport and light-absorption properties of semiconducting materials, one often invokes a lattice of ions displaced from their static positions only by harmonic vibrations. However, a preponderance of recent studies suggests that this picture is not sufficient for HOIPs, where a variety of structurally dynamic effects, beyond small harmonic vibrations, arises already at room temperature. In this Account, we focus on these effects. First, we review structure and bonding in HOIPs and relate them to the promising charge-transport and absorption properties of these materials, in terms of favorable electronic properties. We point out that HOIPs are much “softer” mechanically, compared to other efficient solar-cell materials, and that this can result in large ionic displacements at room temperature. We therefore focus next on dynamic structural effects in HOIPs, going beyond a static band-structure picture. Specifically, we discuss pertinent experimental and theoretical findings as to phase-transition behavior and molecular/octahedral rearrangements. We then discuss atomic diffusion phenomena in HOIPs, with an emphasis on the migration of intrinsic and extrinsic ionic species. From this combined perspective, HOIPs appear as highly dynamic materials, in which structural fluctuations and long-range ionic motion have an unusually strong impact on charge-transport and optical properties. We highlight the potential implications of these effects for several intriguing phenomenological observations, ranging from scattering mechanisms and lifetimes of charge carriers to light-induced structural effects and ionic conduction. PMID:26878152

Arctic Ozone Depletion from UARS MLS Measurements

NASA Technical Reports Server (NTRS)

Manney, G. L.

1995-01-01

Microwave Limb Sounder (MLS) measurements of ozone during four Arctic winters are compared. The evolution of ozone in the lower stratosphere is related to temperature, chlorine monoxide (also measured by MLS), and the evolution of the polar vortex. Lagrangian transport calculations using winds from the United Kingdom Meteorological Office's Stratosphere-Troposphere Data Assimilation system are used to estimate to what extent the evolution of lower stratospheric ozone is controlled by dynamics. Observations, along with calculations of the expected dynamical behavior, show evidence for chemical ozone depletion throughout most of the Arctic lower stratospheric vortex during the 1992-93 middle and late winter, and during all of the 1994-95 winter that was observed by MLS. Both of these winters were unusually cold and had unusually cold and had unusually strong Arctic polar vortices compared to meteorological data over the past 17 years.

Exchange-Dominated Pure Spin Current Transport in Alq3 Molecules.

PubMed

Jiang, S W; Liu, S; Wang, P; Luan, Z Z; Tao, X D; Ding, H F; Wu, D

2015-08-21

We address the controversy over the spin transport mechanism in Alq3 utilizing spin pumping in the Y3Fe5O12/Alq3/Pd system. An unusual angular dependence of the inverse spin Hall effect is found. It, however, disappears when the microwave magnetic field is fully in the sample plane, excluding the presence of the Hanle effect. Together with the quantitative temperature-dependent measurements, these results provide compelling evidence that the pure spin current transport in Alq3 is dominated by the exchange-mediated mechanism.

Reconnaissance of the water resources of the Hoh Indian Reservation and the Hoh River basin, Washington

USGS Publications Warehouse

Lum, W.E.; Nelson, L.M.

1986-01-01

Ground- and surface-water resources of the Hoh Indian Reservation and the Hoh River basin were studied from 1977 to 1980 under a cooperative agreement between the U.S. Geological Survey and the Hoh Indian Tribe. It was determined that moderate quantities of groundwater can be obtained from near-surface, river-deposited sands and gravels on the northeastern part of the reservation. Groundwater recharge (induced by pumping from a nearby oxbow lake) could supply numerous wells indefinitely with yields of 25 to 50 gallons/min. Geologic units in other areas of the reservation appear to have a low hydraulic conductivity and would yield little, if any, water to wells. At seven sites where housing construction is planned, soils were tested for infiltration rates and it was determined that soils are adequate for waste disposal in septic tanks and associated drain fields at those locations. Chalaat Creek, which flows across the reservation, provides water for salmon-rearing ponds. Except for moderately high bacteria concentrations (fecal coliform bacteria concentrations were as high as 33 colonies/100 mL), results of water quality analyses indicate no unusual or harmful concentrations of any chemical constituent or physical properties of the water that would restrict its use for most purposes. Chemical and bacteriological analyses of the Hoh River and its major tributaries downstream from the Olympic Park boundary revealed no unusual or harmful levels of constituents, with some minor exceptions. Small increases in concentrations of sodium, chloride, nitrite plus nitrate, and turbidity were measured in water samples collected from the Hoh River in a downstream direction. These increases are probably the result of natural weathering of rocks and soils in the basin. Fluvial-sediment transport of the Hoh River was 82,000 tons from March 1978 to February 1979 and 1,510,000 tons from March 1979 to February 1980. Mean annual transport was estimated to be 630 ,000 tons. About 60% of the sediment transported by the Hoh River originates from within the boundaries of the Olympic National Park, which includes about 70% of the area of the Hoh River drainage basin. (USGS)

14 CFR 29.1541 - General.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false General. 29.1541 Section 29.1541 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... safe operation of the rotorcraft if it has unusual design, operating or handling characteristics. (b...

CARBON NANOTUBES IN MICROWAVE ENVIRONMENT-IGNITION AND RECONSTRUCTION

EPA Science Inventory

The unusual property of single-walled carbon nanotubes (SWNT), multi-wall (MWNT) nanotubes and Buckminsterfullerene (C-60) is observed upon exposure to microwave-assisted ignition. Carbon nanotubes known for a range of mechanical and electronic properties because of their unique...

Non-Fermi-liquid nature and exotic thermoelectric power in the heavy-fermion superconductor UBe13

NASA Astrophysics Data System (ADS)

Shimizu, Yusei; Pourret, Alexandre; Knebel, Georg; Palacio-Morales, Alexandra; Aoki, Dai

2015-12-01

We report quite exotic thermoelectric power S in UBe13. At 0 T, the negative S /T continues to strongly enhance down to the superconducting transition temperature with no Fermi-liquid behavior. |S /T | is dramatically suppressed and becomes rather modest with increasing field. We have also obtained precise field dependencies of (i) an anomaly in S due to an exotic Kondo effect and (ii) a field-induced anomaly in S /T associated with the anomalous upward Hc 2(T ) . In contrast to the field-sensitive transport property, the normal-state specific heat is magnetically robust, indicating that the largeness of the 5 f density of states remains in high fields. This unusual behavior in UBe13 can be explained by a considerable change in the energy derivative of the conduction-electron lifetime τc(ɛ ) at the Fermi level under magnetic fields.

Lattice thermal transport in L a 3 C u 3 X 4 compounds ( X = P , As , Sb , Bi ) : Interplay of anharmonicity and scattering phase space

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

Thermal conductivities of La 3Cu 3X 4(X=P,As,Sb,Bi) compounds are examined using first-principles density functional theory and Boltzmann transport methods. We observe a trend of increasing lattice thermal conductivity (κl) with increasing atomic mass, challenging our expectations, as lighter mass systems typically have larger sound speeds and weaker intrinsic scattering. In particular, we find that La 3Cu 3P 4 has the lowest κ l, despite having larger sound speed and the most restricted available phase space for phonon-phonon scattering, an important criterion for estimating and comparing κ l among like systems. The origin of this unusual behavior lies in the strengthmore » of the individual anharmonic phonon scattering matrix elements, which are much larger in La 3Cu 3P 4 than in the heavier La 3Cu 3Bi 4 system. Lastly, our finding provides insights into the interplay of harmonic and anharmonic properties of complex, low-thermal-conductivity compounds, of potential use for thermoelectric and thermal barrier coating applications.« less

Form, shape and function: segmented blood flow in the choriocapillaris

PubMed Central

Zouache, M. A.; Eames, I.; Klettner, C. A.; Luthert, P. J.

2016-01-01

The development of fluid transport systems was a key event in the evolution of animals and plants. While within vertebrates branched geometries predominate, the choriocapillaris, which is the microvascular bed that is responsible for the maintenance of the outer retina, has evolved a planar topology. Here we examine the flow and mass transfer properties associated with this unusual geometry. We show that as a result of the form of the choriocapillaris, the blood flow is decomposed into a tessellation of functional vascular segments of various shapes delineated by separation surfaces across which there is no flow, and in the vicinity of which the transport of passive substances is diffusion-limited. The shape of each functional segment is determined by the distribution of arterioles and venules and their respective relative flow rates. We also show that, remarkably, the mass exchange with the outer retina is a function of the shape of each functional segment. In addition to introducing a novel framework in which the structure and function of the metabolite delivery system to the outer retina may be investigated in health and disease, the present work provides a general characterisation of the flow and transfers in multipole Hele-Shaw configurations. PMID:27779198

Lattice thermal transport in L a 3 C u 3 X 4 compounds ( X = P , As , Sb , Bi ) : Interplay of anharmonicity and scattering phase space

DOE PAGES

None, None

2017-06-30

Thermal conductivities of La 3Cu 3X 4(X=P,As,Sb,Bi) compounds are examined using first-principles density functional theory and Boltzmann transport methods. We observe a trend of increasing lattice thermal conductivity (κl) with increasing atomic mass, challenging our expectations, as lighter mass systems typically have larger sound speeds and weaker intrinsic scattering. In particular, we find that La 3Cu 3P 4 has the lowest κ l, despite having larger sound speed and the most restricted available phase space for phonon-phonon scattering, an important criterion for estimating and comparing κ l among like systems. The origin of this unusual behavior lies in the strengthmore » of the individual anharmonic phonon scattering matrix elements, which are much larger in La 3Cu 3P 4 than in the heavier La 3Cu 3Bi 4 system. Lastly, our finding provides insights into the interplay of harmonic and anharmonic properties of complex, low-thermal-conductivity compounds, of potential use for thermoelectric and thermal barrier coating applications.« less

Lattice thermal transport in L a3C u3X4 compounds (X =P ,As ,Sb ,Bi ) : Interplay of anharmonicity and scattering phase space

NASA Astrophysics Data System (ADS)

Pandey, Tribhuwan; Polanco, Carlos A.; Lindsay, Lucas; Parker, David S.

2017-06-01

Thermal conductivities of L a3C u3X4 (X =P ,As ,Sb ,Bi ) compounds are examined using first-principles density functional theory and Boltzmann transport methods. We observe a trend of increasing lattice thermal conductivity (κl) with increasing atomic mass, challenging our expectations, as lighter mass systems typically have larger sound speeds and weaker intrinsic scattering. In particular, we find that L a3C u3P4 has the lowest κl, despite having larger sound speed and the most restricted available phase space for phonon-phonon scattering, an important criterion for estimating and comparing κl among like systems. The origin of this unusual behavior lies in the strength of the individual anharmonic phonon scattering matrix elements, which are much larger in L a3C u3P4 than in the heavier L a3C u3B i4 system. Our finding provides insights into the interplay of harmonic and anharmonic properties of complex, low-thermal-conductivity compounds, of potential use for thermoelectric and thermal barrier coating applications.

Identifying clusters of active transportation using spatial scan statistics.

PubMed

Huang, Lan; Stinchcomb, David G; Pickle, Linda W; Dill, Jennifer; Berrigan, David

2009-08-01

There is an intense interest in the possibility that neighborhood characteristics influence active transportation such as walking or biking. The purpose of this paper is to illustrate how a spatial cluster identification method can evaluate the geographic variation of active transportation and identify neighborhoods with unusually high/low levels of active transportation. Self-reported walking/biking prevalence, demographic characteristics, street connectivity variables, and neighborhood socioeconomic data were collected from respondents to the 2001 California Health Interview Survey (CHIS; N=10,688) in Los Angeles County (LAC) and San Diego County (SDC). Spatial scan statistics were used to identify clusters of high or low prevalence (with and without age-adjustment) and the quantity of time spent walking and biking. The data, a subset from the 2001 CHIS, were analyzed in 2007-2008. Geographic clusters of significantly high or low prevalence of walking and biking were detected in LAC and SDC. Structural variables such as street connectivity and shorter block lengths are consistently associated with higher levels of active transportation, but associations between active transportation and socioeconomic variables at the individual and neighborhood levels are mixed. Only one cluster with less time spent walking and biking among walkers/bikers was detected in LAC, and this was of borderline significance. Age-adjustment affects the clustering pattern of walking/biking prevalence in LAC, but not in SDC. The use of spatial scan statistics to identify significant clustering of health behaviors such as active transportation adds to the more traditional regression analysis that examines associations between behavior and environmental factors by identifying specific geographic areas with unusual levels of the behavior independent of predefined administrative units.

Identifying Clusters of Active Transportation Using Spatial Scan Statistics

PubMed Central

Huang, Lan; Stinchcomb, David G.; Pickle, Linda W.; Dill, Jennifer; Berrigan, David

2009-01-01

Background There is an intense interest in the possibility that neighborhood characteristics influence active transportation such as walking or biking. The purpose of this paper is to illustrate how a spatial cluster identification method can evaluate the geographic variation of active transportation and identify neighborhoods with unusually high/low levels of active transportation. Methods Self-reported walking/biking prevalence, demographic characteristics, street connectivity variables, and neighborhood socioeconomic data were collected from respondents to the 2001 California Health Interview Survey (CHIS; N=10,688) in Los Angeles County (LAC) and San Diego County (SDC). Spatial scan statistics were used to identify clusters of high or low prevalence (with and without age-adjustment) and the quantity of time spent walking and biking. The data, a subset from the 2001 CHIS, were analyzed in 2007–2008. Results Geographic clusters of significantly high or low prevalence of walking and biking were detected in LAC and SDC. Structural variables such as street connectivity and shorter block lengths are consistently associated with higher levels of active transportation, but associations between active transportation and socioeconomic variables at the individual and neighborhood levels are mixed. Only one cluster with less time spent walking and biking among walkers/bikers was detected in LAC, and this was of borderline significance. Age-adjustment affects the clustering pattern of walking/biking prevalence in LAC, but not in SDC. Conclusions The use of spatial scan statistics to identify significant clustering of health behaviors such as active transportation adds to the more traditional regression analysis that examines associations between behavior and environmental factors by identifying specific geographic areas with unusual levels of the behavior independent of predefined administrative units. PMID:19589451

Terahertz Emission from Hybrid Perovskites Driven by Ultrafast Charge Separation and Strong Electron-Phonon Coupling.

PubMed

Guzelturk, Burak; Belisle, Rebecca A; Smith, Matthew D; Bruening, Karsten; Prasanna, Rohit; Yuan, Yakun; Gopalan, Venkatraman; Tassone, Christopher J; Karunadasa, Hemamala I; McGehee, Michael D; Lindenberg, Aaron M

2018-03-01

Unusual photophysical properties of organic-inorganic hybrid perovskites have not only enabled exceptional performance in optoelectronic devices, but also led to debates on the nature of charge carriers in these materials. This study makes the first observation of intense terahertz (THz) emission from the hybrid perovskite methylammonium lead iodide (CH 3 NH 3 PbI 3 ) following photoexcitation, enabling an ultrafast probe of charge separation, hot-carrier transport, and carrier-lattice coupling under 1-sun-equivalent illumination conditions. Using this approach, the initial charge separation/transport in the hybrid perovskites is shown to be driven by diffusion and not by surface fields or intrinsic ferroelectricity. Diffusivities of the hot and band-edge carriers along the surface normal direction are calculated by analyzing the emitted THz transients, with direct implications for hot-carrier device applications. Furthermore, photogenerated carriers are found to drive coherent terahertz-frequency lattice distortions, associated with reorganizations of the lead-iodide octahedra as well as coupled vibrations of the organic and inorganic sublattices. This strong and coherent carrier-lattice coupling is resolved on femtosecond timescales and found to be important both for resonant and far-above-gap photoexcitation. This study indicates that ultrafast lattice distortions play a key role in the initial processes associated with charge transport. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Terahertz Emission from Hybrid Perovskites Driven by Ultrafast Charge Separation and Strong Electron-Phonon Coupling

DOE PAGES

Guzelturk, Burak; Belisle, Rebecca A.; Smith, Matthew D.; ...

2018-01-23

Unusual photophysical properties of organic–inorganic hybrid perovskites have not only enabled exceptional performance in optoelectronic devices, but also led to debates on the nature of charge carriers in these materials. This study makes the first observation of intense terahertz (THz) emission from the hybrid perovskite methylammonium lead iodide (CH 3NH 3PbI 3) following photoexcitation, enabling an ultrafast probe of charge separation, hot–carrier transport, and carrier–lattice coupling under 1–sun–equivalent illumination conditions. Using this approach, the initial charge separation/transport in the hybrid perovskites is shown to be driven by diffusion and not by surface fields or intrinsic ferroelectricity. Diffusivities of the hotmore » and band–edge carriers along the surface normal direction are calculated by analyzing the emitted THz transients, with direct implications for hot–carrier device applications. Furthermore, photogenerated carriers are found to drive coherent terahertz–frequency lattice distortions, associated with reorganizations of the lead–iodide octahedra as well as coupled vibrations of the organic and inorganic sublattices. This strong and coherent carrier–lattice coupling is resolved on femtosecond timescales and found to be important both for resonant and far–above–gap photoexcitation. As a result, this study indicates that ultrafast lattice distortions play a key role in the initial processes associated with charge transport.« less

Work Function Engineering of Graphene

PubMed Central

Garg, Rajni; Dutta, Naba K.; Roy Choudhury, Namita

2014-01-01

Graphene is a two dimensional one atom thick allotrope of carbon that displays unusual crystal structure, electronic characteristics, charge transport behavior, optical clarity, physical & mechanical properties, thermal conductivity and much more that is yet to be discovered. Consequently, it has generated unprecedented excitement in the scientific community; and is of great interest to wide ranging industries including semiconductor, optoelectronics and printed electronics. Graphene is considered to be a next-generation conducting material with a remarkable band-gap structure, and has the potential to replace traditional electrode materials in optoelectronic devices. It has also been identified as one of the most promising materials for post-silicon electronics. For many such applications, modulation of the electrical and optical properties, together with tuning the band gap and the resulting work function of zero band gap graphene are critical in achieving the desired properties and outcome. In understanding the importance, a number of strategies including various functionalization, doping and hybridization have recently been identified and explored to successfully alter the work function of graphene. In this review we primarily highlight the different ways of surface modification, which have been used to specifically modify the band gap of graphene and its work function. This article focuses on the most recent perspectives, current trends and gives some indication of future challenges and possibilities. PMID:28344223

Interfacial coupling and polarization of perovskite ABO3 heterostructures

NASA Astrophysics Data System (ADS)

Wu, Lijun; Wang, Zhen; Zhang, Bangmin; Yu, Liping; Chow, G. M.; Tao, Jing; Han, Myung-Geun; Guo, Hangwen; Chen, Lina; Plummer, E. W.; Zhang, Jiandi; Zhu, Yimei

2017-02-01

Interfaces with subtle difference in atomic and electronic structures in perovskite ABO3 heterostructures often yield intriguingly different properties, yet their exact roles remain elusive. In this article, we report an integrated study of unusual transport, magnetic, and structural properties of Pr0.67Sr0.33MnO3 (PSMO) films and La0.67Sr0.33MnO3 (LSMO) films of various thicknesses on SrTiO3 (STO) substrate. In particular, using atomically resolved imaging and electron energy-loss spectroscopy (EELS), we measured interface related local lattice distortion, BO6 octahedral rotation and cation-anion displacement induced polarization. In the very thin PSMO film, an unexpected interface-induced ferromagnetic polaronic insulator phase was observed during the cubic-to-tetragonal phase transition of the substrate STO, due to the enhanced electron-phonon interaction and atomic disorder in the film. On the other hand, for the very thin LSMO films we observed a remarkably deep polarization in non-ferroelectric STO substrate near the interface. Combining the experimental results with first principles calculations, we propose that the observed deep polarization is induced by an electric field originating from oxygen vacancies that extend beyond a dozen unit-cells from the interface, thus providing important evidence of the role of defects in the emergent interface properties of transition metal oxides.

Work Function Engineering of Graphene.

PubMed

Garg, Rajni; Dutta, Naba K; Choudhury, Namita Roy

2014-04-03

Graphene is a two dimensional one atom thick allotrope of carbon that displays unusual crystal structure, electronic characteristics, charge transport behavior, optical clarity, physical & mechanical properties, thermal conductivity and much more that is yet to be discovered. Consequently, it has generated unprecedented excitement in the scientific community; and is of great interest to wide ranging industries including semiconductor, optoelectronics and printed electronics. Graphene is considered to be a next-generation conducting material with a remarkable band-gap structure, and has the potential to replace traditional electrode materials in optoelectronic devices. It has also been identified as one of the most promising materials for post-silicon electronics. For many such applications, modulation of the electrical and optical properties, together with tuning the band gap and the resulting work function of zero band gap graphene are critical in achieving the desired properties and outcome. In understanding the importance, a number of strategies including various functionalization, doping and hybridization have recently been identified and explored to successfully alter the work function of graphene. In this review we primarily highlight the different ways of surface modification, which have been used to specifically modify the band gap of graphene and its work function. This article focuses on the most recent perspectives, current trends and gives some indication of future challenges and possibilities.

Structure, reactivity and electronic properties of Mn doped Ni13 clusters

NASA Astrophysics Data System (ADS)

Banerjee, Radhashyam; Datta, Soumendu; Mookerjee, Abhijit

2013-06-01

In this work we have studied the structural and magnetic properties of Ni13 cluster mono- and bi-doped with Mn atoms. We have noted their tendency of being reactive toward the H2 molecule. We have found unusually enhanced stability in the mono-doped cluster (i.e. of the Ni12Mn) and the diminished stability of the corresponding chemisorbed cluster, Ni12MnH2. Our analysis of the stability and HOMO-LUMO gap explains this unusual behavior. Interestingly, we have also seen the quenching in the net magnetic moment upon H2 absorption in the doped NiMnm alloy clusters. This has been reported earlier for smaller Nin clusters [1].

Beyond the Byrd Road Act : VDOT's relationship with Virginia's urban counties.

DOT National Transportation Integrated Search

1998-01-01

Since the Byrd Road Act of 1932, the Virginia Department of Transportation (VDOT) has been responsible for secondary road maintenance and construction in all of the state's counties except two (Arlington and Henrico). Such an arrangement is unusual a...

Synthetic Vision System Commercial Aircraft Flight Deck Display Technologies for Unusual Attitude Recovery

NASA Technical Reports Server (NTRS)

Prinzel, Lawrence J., III; Ellis, Kyle E.; Arthur, Jarvis J.; Nicholas, Stephanie N.; Kiggins, Daniel

2017-01-01

A Commercial Aviation Safety Team (CAST) study of 18 worldwide loss-of-control accidents and incidents determined that the lack of external visual references was associated with a flight crew's loss of attitude awareness or energy state awareness in 17 of these events. Therefore, CAST recommended development and implementation of virtual day-Visual Meteorological Condition (VMC) display systems, such as synthetic vision systems, which can promote flight crew attitude awareness similar to a day-VMC environment. This paper describes the results of a high-fidelity, large transport aircraft simulation experiment that evaluated virtual day-VMC displays and a "background attitude indicator" concept as an aid to pilots in recovery from unusual attitudes. Twelve commercial airline pilots performed multiple unusual attitude recoveries and both quantitative and qualitative dependent measures were collected. Experimental results and future research directions under this CAST initiative and the NASA "Technologies for Airplane State Awareness" research project are described.

A Mini Resource File: Programming for Independent Maturity.

ERIC Educational Resources Information Center

Goldstein, Judith E.

1981-01-01

A selection of available resources from various agencies is presented to inform the older adult about such issues as: (1) special travel arrangements for travelers with unusual needs; (2) accommodations; (3) local transportation, (4) recreational activities; and (5) fashions for the changing body. (JN)

Structure Controlled Long-Range Sequential Tunneling in Carbon-Based Molecular Junctions.

PubMed

Morteza Najarian, Amin; McCreery, Richard L

2017-04-25

Carbon-based molecular junctions consisting of aromatic oligomers between conducting sp 2 hybridized carbon electrodes exhibit structure-dependent current densities (J) when the molecular layer thickness (d) exceeds ∼5 nm. All four of the molecular structures examined exhibit an unusual, nonlinear ln J vs bias voltage (V) dependence which is not expected for conventional coherent tunneling or activated hopping mechanisms. All molecules exhibit a weak temperature dependence, with J increasing typically by a factor of 2 over the range of 200-440 K. Fluorene and anthraquinone show linear plots of ln J vs d with nearly identical J values for the range d = 3-10 nm, despite significant differences in their free-molecule orbital energy levels. The observed current densities for anthraquinone, fluorene, nitroazobenzene, and bis-thienyl benzene for d = 7-10 nm show no correlation with occupied (HOMO) or unoccupied (LUMO) molecular orbital energies, contrary to expectations for transport mechanisms based on the offset between orbital energies and the electrode Fermi level. UV-vis absorption spectroscopy of molecular layers bonded to carbon electrodes revealed internal energy levels of the chemisorbed films and also indicated limited delocalization in the film interior. The observed current densities correlate well with the observed UV-vis absorption maxima for the molecular layers, implying a transport mechanism determined by the HOMO-LUMO energy gap. We conclude that transport in carbon-based aromatic molecular junctions is consistent with multistep tunneling through a barrier defined by the HOMO-LUMO gap, and not by charge transport at the electrode interfaces. In effect, interfacial "injection" at the molecule/electrode interfaces is not rate limiting due to relatively strong electronic coupling, and transport is controlled by the "bulk" properties of the molecular layer interior.

Bandgap Engineering of NiO-CdO

NASA Astrophysics Data System (ADS)

Francis, Christopher

A discussion of the earliest point defect and ADM theory studies then justifies the dissertation's selection of CdO--it's strong electrical properties are suitable for bandgap engineering. Investigations of previous literature involving the Group II-oxides of ZnO, MgO, and CdO lead to two key conclusions. First, few studies exist in which CdO is a primary alloying material. Second, the properties of CdO are tunable with better complementary materials such as NiO, a transition metal (TM) oxide, instead of commonly used ZnO and MgO. Given their unique properties, there is an opportunity to investigate the structure, properties, and behavior of CdO system after alloying it with NiO. Hall effect, optical reflectance and transmittance and X-ray diffraction measurements are utilized first and the structural, electrical transport and optical properties of NixCd1-xO films sputtered in argon (Ar) with radio frequency (RF) magnetron are then reported. This initial study shows that NixCd1-xO alloys are rocksalt-structured and exhibit a monotonic shift of the (220) diffraction peak to higher 2theta angles with increasing Ni concentration. The electron mobility and electron concentration decrease with increasing Ni--becoming highly resistive for Ni content greater than 43.4% Ni. This decrease in n-type conductivity is consistent with the movement expected from a virtual crystal approximation (VCA) of the conduction band minimum (CBM) from below to above the Fermi stabilization energy (EFS). The optical absorption edge of the alloys is tunable from CdO to NiO. An intrinsic, carrier-free bandgap of the alloys, Eg, was calculated from the electrical and optical measurements, accounting for Burstein-Moss carrier filling and carrier-induced bandgap correlation effects. An unusual super linear composition dependence of the intrinsic bandgap is revealed when accounting for these effects. The super linear behavior was initially attributed to an interaction between the conduction-band extended states and localized donor and acceptor d-states of Ni. To probe the mechanisms behind the anomalous electrical transport and optical behaviors of the Ar sputtered alloys a collection of experimental and modeling investigations via ion irradiation, band anticrossing (BAC) simulations and X-Ray Photoelectron Spectroscopy-Ultraviolet Photoelectron Spectroscopy (XPS-UPS) was then used. This study discovered that the introduction of a TM with two impurity levels leads to interactions that reconstruct both the conduction and valence bands of the alloy with increasing Ni. Irradiation of the films leads to a saturation of the electron concentration associated with the pinning of the Fermi level at EFS. The composition dependence of the pinned EF enables determination of the CBM energy relative to the vacuum level. There is an unusually strong deviation of this CBM energy observed from the VCA which is then explained by a BAC interaction between localized 3d states of Ni and the extended states of the NixCd1-xO alloy host. The resulting band structure is responsible for the dependence on composition of the electrical and optical properties of the alloys, the rapid reduction of the electron mobility, and previously observed positive bandgap bowing parameter. XPS-UPS studies confirm that the Gamma- and L-point valence band maxima in the Cd-rich alloys are unaffected by interactions with Ni d-states. The results from this study provide much-needed context to the previously reported, but unexplained, electrical transport and optical behavior found in NixCd 1-xO, NixMg1-xO and Ni1-xZnxO alloys--the interactions govern their measured electrical and optical properties. These breakthroughs are also applicable to metal-oxide-based semiconducting alloys with TM acting as the dopant or alloying agents--such as V-doped ZnO. With an understanding of the structure, properties, and behavior of n-type, Ar sputtered NixCd1-xO, exploratory work for applications was then conducted. First, the electrochemical modification of these alloys for electrochromic windows was completed and the resulting electrical transport and optical properties were reported. Second, separate studies on the modification of NixCd 1-xO with the percent of O2 sputtering gas were implemented to evoke p-type conductivity for p-n junctions and hole emitter applications. Following this growth method, rapid thermal annealing studies under N 2 and O2-rich environments were conducted. These studies probed the defect mechanisms and discussed the optimal processing conditions that encourage the growth of reproducible and measurable p-type conductivity in NixCd1-xO. By altering the percent of O2 in the growth ambient, NixCd1-xO films with tunable electrical transport properties and charge type are realized--the first such result of its kind.

Dramatic Changes in Thermoelectric Power of Germanium under Pressure: Printing n–p Junctions by Applied Stress

PubMed Central

Korobeinikov, Igor V.; Morozova, Natalia V.; Shchennikov, Vladimir V.; Ovsyannikov, Sergey V.

2017-01-01

Controlled tuning the electrical, optical, magnetic, mechanical and other characteristics of the leading semiconducting materials is one of the primary technological challenges. Here, we demonstrate that the electronic transport properties of conventional single-crystalline wafers of germanium may be dramatically tuned by application of moderate pressures. We investigated the thermoelectric power (Seebeck coefficient) of p– and n–type germanium under high pressure to 20 GPa. We established that an applied pressure of several GPa drastically shifts the electrical conduction to p–type. The p–type conduction is conserved across the semiconductor-metal phase transition at near 10 GPa. Upon pressure releasing, germanium transformed to a metastable st12 phase (Ge-III) with n–type semiconducting conductivity. We proposed that the unusual electronic properties of germanium in the original cubic-diamond-structured phase could result from a splitting of the “heavy” and “light” holes bands, and a related charge transfer between them. We suggested new innovative applications of germanium, e.g., in technologies of printing of n–p and n–p–n junctions by applied stress. Thus, our work has uncovered a new face of germanium as a ‘smart’ material. PMID:28290495

Single crystal, liquid crystal, and hybrid organic semiconductors

NASA Astrophysics Data System (ADS)

Twieg, Robert J.; Getmanenko, Y.; Lu, Z.; Semyonov, A. N.; Huang, S.; He, P.; Seed, A.; Kiryanov, A.; Ellman, B.; Nene, S.

2003-07-01

The synthesis and characterization of organic semiconductors is being pursued in three primary structure formats: single crystal, liquid crystal and organic-inorganic hybrid. The strategy here is to share common structures, synthesis methods and fabrication techniques across these formats and to utilize common characterization tools such as the time of flight technique. The single crystal efforts concentrate on aromatic and heteroaromatic compounds including simple benzene derivatives and derivatives of the acenes. The structure-property relationships due to incorporation of small substituents and heteroatoms are being examined. Crystals are grown by solution, melt or vapor transport techniques. The liquid crystal studies exploit their self-organizing properties and relative ease of sample preparation. Though calamitic systems tha deliver the largest mobilities are higher order smectics, even some unusual twist grain boundary phases are being studied. We are attempting to synthesize discotic acene derivatives with appropriate substitution patterns to render them mesogenic. The last format being examined is the hybrid organic-inorganic class. Here, layered materials of alternating organic and inorganic composition are designed and synthesized. Typical materials are conjugated aromatic compounds, usually functinalized with an amine or a pyridine and reacted with appropriate reactive metal derivatives to incorporate them into metal oxide or sulfide layers.

Effects of disorder on the intrinsically hole-doped iron-based superconductor KC a2F e4A s4F2 by cobalt substitution

NASA Astrophysics Data System (ADS)

Ishida, Junichi; Iimura, Soshi; Hosono, Hideo

2017-11-01

In this paper, the effects of cobalt substitution on the transport and electronic properties of the recently discovered iron-based superconductor KC a2F e4A s4F2 , with Tc=33 K , are reported. This material is an unusual superconductor showing intrinsic hole conduction (0.25 holes /F e2 + ). Upon doping of Co, the Tc of KC a2(Fe1-xC ox) 4A s4F2 gradually decreased, and bulk superconductivity disappeared when x ≥0.25 . Conversion of the primary carrier from p type to n type upon Co-doping was clearly confirmed by Hall measurements, and our results are consistent with the change in the calculated Fermi surface. Nevertheless, neither spin density wave (SDW) nor an orthorhombic phase, which are commonly observed for nondoped iron-based superconductors, was observed in the nondoped or electron-doped samples. The electron count in the 3 d orbitals and structural parameters were compared with those of other iron-based superconductors to show that the physical properties can be primarily ascribed to the effects of disorder.

41 CFR 109-43.304-1.50 - DOE reutilization screening.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Management Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS UTILIZATION AND DISPOSAL 43-UTILIZATION OF PERSONAL PROPERTY 43.3-Utilization of Excess § 109-43.304-1.50 DOE... acquisition cost is $1,000 or more. (d) In exceptional or unusual cases when time is critical, screening of...

41 CFR 109-43.304-1.50 - DOE reutilization screening.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Management Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS UTILIZATION AND DISPOSAL 43-UTILIZATION OF PERSONAL PROPERTY 43.3-Utilization of Excess § 109-43.304-1.50 DOE... acquisition cost is $1,000 or more. (d) In exceptional or unusual cases when time is critical, screening of...

Humidity Effects on Soluble Core Mechanical and Thermal Properties (Polyvinyl Alcohol/Microballoon Composite)

NASA Technical Reports Server (NTRS)

1993-01-01

This document constitutes the final report for the study of humidity effects and loading rate on soluble core (PVA/MB composite material) mechanical and thermal properties. This report describes test results, procedures employed, and any unusual occurrences or specific observations associated with this test program.

Relativistic Effects and the Chemistry of the Heaviest Main-Group Elements

ERIC Educational Resources Information Center

Thayer, John S.

2005-01-01

The chemical properties of the heaviest main-group elements often show features not found in their lighter counterparts while relativistic effects play an important role in the chemistry of these elements. The unusual properties and their relation to relativistic effects with emphasis on the new research are emphasized.

Dissolved Methane in the Sills Region of the Gulf of California

EPA Science Inventory

An unusual combination of features make the midriff islands region of the northern Gulf of California (NGC) a strong source of methane to the atmosphere. Oceanographic isolation from the rest of the NGC by a series of sills and islands along with enhanced upward transport of nutr...

76 FR 10528 - Special Conditions: Gulfstream Model GVI Airplane; Electronic Systems Security Isolation or...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-25

... conditions for the Gulfstream GVI airplane. This airplane may have novel or unusual design features... standards for these design features. These proposed special conditions contain the additional safety... transport airplane with an executive cabin interior. The maximum takeoff weight will be 99,600 pounds, with...

42 CFR 422.113 - Special rules for ambulance services, emergency and urgently needed services, and maintenance and...

Code of Federal Regulations, 2011 CFR

2011-10-01

... means of transportation would endanger the beneficiary's health. (b) Emergency and urgently needed... temporarily absent from the MA plan's service (or, if applicable, continuation) area (or, under unusual and... organization's provider network is temporarily unavailable or inaccessible) when the services are medically...

Ultralow Thermal Conductivity in Diamond-Like Semiconductors: Selective Scattering of Phonons from Antisite Defects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gorai, Prashun; Stevanovic, Vladan; Toberer, Eric

In this work, we discover anomalously low lattice thermal conductivity (<0.25 W/mK at 300 degrees C) in the Hg-containing quaternary diamond-like semiconductors within the Cu2IIBIVTe4 (IIB: Zn, Cd, Hg) (IV: Si, Ge, Sn) set of compositions. Using high-temperature X-ray diffraction, resonant ultrasound spectroscopy, and transport properties, we uncover the critical role of the antisite defects HgCu and CuHg on phonon transport within the Hg-containing systems. Despite the differences in chemistry between Hg and Cu, the high concentration of these antisite defects emerges from the energetic proximity of the kesterite and stannite cation motifs. Our phonon calculations reveal that heavier groupmore » IIB elements not only introduce low-lying optical modes, but the subsequent antisite defects also possess unusually strong point defect phonon scattering power. The scattering strength stems from the fundamentally different vibrational modes supported by the constituent elements (e.g., Hg and Cu). Despite the significant impact on the thermal properties, antisite defects do not negatively impact the mobility (>50 cm2/(Vs) at 300 degrees C) in Hg-containing systems, leading to predicted zT > 1.5 in Cu2HgGeTe4 and Cu2HgSnTe4 under optimized doping. In addition to introducing a potentially new p-type thermoelectric material, this work provides (1) a strategy to use the proximity of phase transitions to increase point defect phonon scattering, and (2) a means to quantify the power of a given point defect through inexpensive phonon calculations.« less

Functional Interaction between the Cytoplasmic ABC Protein LptB and the Inner Membrane LptC Protein, Components of the Lipopolysaccharide Transport Machinery in Escherichia coli

PubMed Central

Martorana, Alessandra M.; Benedet, Mattia; Maccagni, Elisa A.; Sperandeo, Paola; Villa, Riccardo; Dehò, Gianni

2016-01-01

ABSTRACT The assembly of lipopolysaccharide (LPS) in the outer leaflet of the outer membrane (OM) requires the transenvelope Lpt (lipopolysaccharide transport) complex, made in Escherichia coli of seven essential proteins located in the inner membrane (IM) (LptBCFG), periplasm (LptA), and OM (LptDE). At the IM, LptBFG constitute an unusual ATP binding cassette (ABC) transporter, composed by the transmembrane LptFG proteins and the cytoplasmic LptB ATPase, which is thought to extract LPS from the IM and to provide the energy for its export across the periplasm to the cell surface. LptC is a small IM bitopic protein that binds to LptBFG and recruits LptA via its N- and C-terminal regions, and its role in LPS export is not completely understood. Here, we show that the expression level of lptB is a critical factor for suppressing lethality of deletions in the C-terminal region of LptC and the functioning of a hybrid Lpt machinery that carries Pa-LptC, the highly divergent LptC orthologue from Pseudomonas aeruginosa. We found that LptB overexpression stabilizes C-terminally truncated LptC mutant proteins, thereby allowing the formation of a sufficient amount of stable IM complexes to support growth. Moreover, the LptB level seems also critical for the assembly of IM complexes carrying Pa-LptC which is otherwise defective in interactions with the E. coli LptFG components. Overall, our data suggest that LptB and LptC functionally interact and support a model whereby LptB plays a key role in the assembly of the Lpt machinery. IMPORTANCE The asymmetric outer membrane (OM) of Gram-negative bacteria contains in its outer leaflet an unusual glycolipid, the lipopolysaccharide (LPS). LPS largely contributes to the peculiar permeability barrier properties of the OM that prevent the entry of many antibiotics, thus making Gram-negative pathogens difficult to treat. In Escherichia coli the LPS transporter (the Lpt machine) is made of seven essential proteins (LptABCDEFG) that form a transenvelope complex. Here, we show that increased expression of the membrane-associated ABC protein LptB can suppress defects of LptC, which participates in the formation of the periplasmic bridge. This reveals functional interactions between these two components and supports a role of LptB in the assembly of the Lpt machine. PMID:27246575

Soil heating and evaporation under extreme conditions: Forest fires and slash pile burns

NASA Astrophysics Data System (ADS)

Massman, W. J.

2011-12-01

Heating any soil during a sufficiently intense wild fire or prescribed burn can alter soil irreversibly, resulting in many significant and well known, long term biological, chemical, and hydrological effects. To better understand how fire impacts soil, especially considering the increasing probability of wildfires that is being driven by climate change and the increasing use of prescribe burns by land managers, it is important to better understand the dynamics of the coupled heat and moisture transport in soil during these extreme heating events. Furthermore, improving understanding of heat and mass transport during such extreme conditions should also provide insights into the associated transport mechanisms under more normal conditions as well. Here I describe the development of a new model designed to simulate soil heat and moisture transport during fires where the surface heating often ranges between 10,000 and 100,000 Wm-2 for several minutes to several hours. Model performance is tested against laboratory measurements of soil temperature and moisture changes at several depths during controlled heating events created with an extremely intense radiant heater. The laboratory tests employed well described soils with well known physical properties. The model, on the other hand, is somewhat unusual in that it employs formulations for temperature dependencies of the soil specific heat, thermal conductivity, and the water retention curve (relation between soil moisture and soil moisture potential). It also employs a new formulation for the surface evaporation rate as a component of the upper boundary condition, as well as the Newton-Raphson method and the generalized Thomas algorithm for inverting block tri-diagonal matrices to solve for soil temperature and soil moisture potential. Model results show rapid evaporation rates with significant vapor transfer not only to the free atmosphere above the soil, but to lower depths of the soil, where the vapor re-condenses ahead of the heating front. Consequently the trajectory of the solution (soil volumetric water content versus soil temperature) is very unusual and highly nonlinear, which may explain why more traditional methods (i.e., those based on finite difference or finite element approaches) tend to show more numerical instabilities than the Newton-Raphson method when used to model these extreme conditions. But, despite the intuitive and qualitative appeal of the model's numerical solution, it underestimates the rate of soil moisture loss observed during the laboratory trials, although the soil temperatures are reasonably well simulated.

Topological interlocking provides stiffness to stochastically micro-cracked materials beyond the transport percolation limit

NASA Astrophysics Data System (ADS)

Pal, Anirban; Picu, Catalin; Lupulescu, Marian V.

We study the mechanical behavior of two-dimensional, stochastically microcracked continua in the range of crack densities close to, and above the transport percolation threshold. We show that these materials retain stiffness up to crack densities much larger than the transport percolation threshold, due to topological interlocking of sample sub-domains. Even with a linear constitutive law for the continuum, the mechanical behavior becomes non-linear in the range of crack densities bounded by the transport and stiffness percolation thresholds. The effect is due to the fractal nature of the fragmentation process and is not linked to the roughness of individual cracks. We associate this behavior to that of itacolumite, a sandstone that exhibits unusual flexibility.

Investigation of diamond deposition by chemical vapor transport with hydrogen

NASA Astrophysics Data System (ADS)

Piekarczyk, Wladyslaw; Messier, Russell F.; Roy, Rustum; Engdahl, Chris

1990-12-01

The carbon-hydrogen chemical vapor transport system was examined in accordance with a four-stage transport model. A result of this examination is that graphite co-deposition could be avoided when diamond is deposited from gas solutions under-saturated with respect to diamond. Actual deposition experiments showed that this unusual requirement can be fulfilled but only for the condition that the transport distance between the carbon source and the substrate surface is short. In such a case diamond can be deposited equally from super-saturated as well as from under-saturated gas solutions. On the basis of thermodynamic considerations a possible explanation of this unusual phenomenon is given. It is shown that there is a possibility of deposition of diamond from both super-saturated as well as under-saturated gas solutions but only on the condition that they are in a non-equilibrium state generally called the activated state. A model of the diamond deposition process consisting of two steps is proposed. In the first step diamond and graphite are deposited simultaneously. The most important carbon deposition reaction is C2H2(g) + 2 H(g) C(diamond graphite) + CH(g). The amount of co-deposited graphite is not a direct function of the saturation state of the gas phase. In the second step graphite is etched according to the most probable reaction C(graphite) + 4 H(g) CH4(g). Atomic hydrogen in a super-equilibrium concentration is necessary not only to etch graphite but also to precipitate and graphite. 1.

Diamond deposition by chemical vapor transport with hydrogen in a closed system

NASA Astrophysics Data System (ADS)

Piekarczyk, W.; Messier, R.; Roy, R.; Engdahl, C.

1990-11-01

The carbon-hydrogen chemical vapor transport system was examined in accordance with a four-stage transport model. A result of this examination is that graphite co-deposition could be avoided when diamond is deposited from gas solutions undersaturated with regard to diamond. Actual deposition experiments showed that this unusual requirement can be fulfilled but only for the condition that the transport distance between the carbon source and the substrate surface is short. In such a case diamond can be deposited equally from supersaturated as well as from undersaturated gas solutions. On the basis of thermodynamic considerations, a possible explanation of this unusual phenomenon is given. It is shown that there is a possibility of deposition of diamond from both supersaturated and undersaturated gas solutions but only on the condition that they are in a non-equilibrium state generally called the activated state. A model of the diamond deposition process consisting of two steps is proposed. In the first step diamond and graphite are deposited simultaneously. The most important carbon deposition reaction is C 2H 2(g)+2H(g) = C(diamond+graphite) +CH 4(g). The amount of co-deposited graphite is not a direct function of the saturation state of the gas phase. In the second step graphite is etched according to the most probable reaction C(graphite)+4H(g) = CH 4(g). Atomic hydrogen in a concentration exceeding equilibrium is necessary not only to etch graphite, but also to precipitate diamond and graphite.

Mechanism behind the high thermoelectric power factor of SrTiO3 by calculating the transport coefficients

NASA Astrophysics Data System (ADS)

Shirai, Koun; Yamanaka, Kazunori

2013-02-01

The thermoelectric power factor of SrTiO3 is unusually high with respect to its mobility and band gap. Good thermoelectrics usually have high mobility and a narrow band gap, but such properties are not found in SrTiO3. We have determined the mechanism behind the high power factor by calculating the transport coefficients. The key to understanding the power factor is that different effective masses contribute to different transport phenomena. The discrepancy between the effective mass for the conductivity and the thermoelectric power showed that the conductivity and thermoelectric power are conveyed by electrons with different effective masses in the Brillouin zone. Light electrons were responsible for the high conductivity, whereas heavy electrons were responsible for the high thermoelectric power. The high carrier concentrations of more than 1020 cm-3 did not reduce the thermoelectric power of SrTiO3 above the classical limit. This indicates that the electrons carrying the thermoelectric power were not degenerate. This is achieved by a decrease in the Fermi energy and the contribution of the heavy electrons to the Seebeck coefficient. The strong dielectric screening also contributed to the high power factor. The Coulomb scattering by ionized impurities, which would usually reduce the carrier mobility, was effectively screened. These results clarify the mechanism behind the contribution of different types of electrons, and show that high thermoelectric power does not necessarily reduce conductivity. Our findings provide a new direction for the band engineering of thermoelectric materials.

NREL Researchers Create New Materials With Unusual Properties | News | NREL

Science.gov Websites

show how such new low-density materials can be made - with unique properties remarkably different from compounds with atomic structures that didn't match, the researchers theorized that mixing two different high manganese telluride (MnTe) that have different crystal structures - the approach known as heterostructural

Spectroscopic imaging scanning tunneling microscopy of a Dirac line node material ZrSiS

NASA Astrophysics Data System (ADS)

Zhou, Lihui; He, Qingyu; Queiroz, Raquel; Grüneis, Andreas; Schnyder, Andreas; Ast, Christian; Schoop, Leslie; Takagi, Hide; Rost, Andreas

3D Dirac materials are an intensive area of current condensed matter research. The related Dirac line node materials have come into focus due to many shared properties such as unconventional magneto-transport and the potential to host topologically nontrivial phases. ZrSiS is one of the first discovered materials of this new family, hosting a nodal line and an unconventional surface state. Spectroscopic imaging scanning tunneling microscopy (SI-STM) detects quasiparticle interference and has been extensively used to study the scattering mechanism and the band structures of exotic materials with high energy resolution at the atomic scale. Here in this presentation, we report the investigation of ZrSiS by SI-STM at the atomic scale, in combination with DFT calculations. We succeeded in visualizing the Dirac nodal line both in real and momentum space, adding key pieces of evidences confirming the existence of a nodal line in this material and highlighting its exceptional properties. The breaking of a non-symmorphic symmetry at the surface induces an unusual surface state whose dispersion was mapped. In particular, we observed spectroscopic signatures of a type-II Dirac fermion hosted by the surface state. Our data as seen by SI-STM has impact beyond ZrSiS providing crucial insights into the properties of Dirac line node materials in particular and non-symmorphic crystals in general.

pH-dependent pore-forming activity of OmpATb from Mycobacterium tuberculosis and characterization of the channel by peptidic dissection.

PubMed

Molle, Virginie; Saint, Nathalie; Campagna, Sylvie; Kremer, Laurent; Lea, Edward; Draper, Philip; Molle, Gérard

2006-08-01

Mycobacteria are characterized by an unusual cell wall that controls nutrient and small hydrophilic compound permeability. Porin-like proteins are necessary to ensure the transport of molecules into the cell. Here, we investigated the pore-forming properties of OmpATb, a porin from Mycobacterium tuberculosis, in lipid bilayers. Multi-channel experiments showed an asymmetric behaviour with channel closures at negative critical voltages (Vc) and a strong decrease in Vc at acidic pH. Single-channel experiments gave conductance values of about 850 +/- 80 pS in 1 M KCl and displayed a weak cationic selectivity in 4-8 pH range. The production and characterization of a series of truncated OmpATb proteins, showed that the central domain (OmpATb73-220) was sufficient to induce the ion channel properties of the native protein in lipid bilayers, i.e. asymmetric insertion, pH-dependent voltage closure, cationic selectivity and similar conductance values in 1 M KCl. Western blot analysis suggests that the presence of OmpATb is only restricted to certain pathogenic species. Therefore, the propensity of channels of native OmpATb to close at low pH may represent an intrinsic property allowing pathogenic mycobacteria to adapt and survive to mildly acidic conditions, such as those encountered within the macrophage phagosome.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mun, Eundeok; Bud'ko, Sergey L.; Canfield, Paul C.

We present the magnetic field dependencies of transport properties for RPtBi ( R = Gd, Dy, Tm, and Lu) half-Heusler compounds. Temperature- and field-dependent resistivity measurements of high-quality RPtBi single crystals reveal an unusually large, nonsaturating magnetoresistance (MR) up to 300 K under a moderate magnetic field of H = 140 kOe. At 300 K, the large MR effect decreases as the rare earth is traversed from Gd to Lu and the magnetic field dependence of MR shows a deviation from the conventional H2 behavior. The Hall coefficient ( RH) for R = Gd indicates a sign change around 120more » K, whereas RH curves for R = Dy, Tm, and Lu remain positive for all measured temperatures. At 300 K, the Hall resistivity reveals a deviation from the linear field dependence for all compounds. Thermoelectric power measurements on this family show strong temperature and magnetic field dependencies which are consistent with resistivity measurements. A highly enhanced thermoelectric power under applied magnetic field is observed as high as ~100 μV/K at 140 kOe. Furthermore, analysis of the transport data in this series reveals that the rare-earth-based half-Heusler compounds provide opportunities to tune MR effect through lanthanide contraction and to elucidate the mechanism of nontrivial MR.« less

Diagnostic Value of Run Chart Analysis: Using Likelihood Ratios to Compare Run Chart Rules on Simulated Data Series

PubMed Central

Anhøj, Jacob

2015-01-01

Run charts are widely used in healthcare improvement, but there is little consensus on how to interpret them. The primary aim of this study was to evaluate and compare the diagnostic properties of different sets of run chart rules. A run chart is a line graph of a quality measure over time. The main purpose of the run chart is to detect process improvement or process degradation, which will turn up as non-random patterns in the distribution of data points around the median. Non-random variation may be identified by simple statistical tests including the presence of unusually long runs of data points on one side of the median or if the graph crosses the median unusually few times. However, there is no general agreement on what defines “unusually long” or “unusually few”. Other tests of questionable value are frequently used as well. Three sets of run chart rules (Anhoej, Perla, and Carey rules) have been published in peer reviewed healthcare journals, but these sets differ significantly in their sensitivity and specificity to non-random variation. In this study I investigate the diagnostic values expressed by likelihood ratios of three sets of run chart rules for detection of shifts in process performance using random data series. The study concludes that the Anhoej rules have good diagnostic properties and are superior to the Perla and the Carey rules. PMID:25799549

76 FR 10529 - Special Conditions: Gulfstream Model GVI Airplane; Electronic Systems Security Protection From...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-25

... Gulfstream GVI airplane. This airplane will have novel or unusual design features associated with the... not contain adequate or appropriate safety standards for these design features. These proposed special... will be an all-new, two- engine jet transport airplane with an executive cabin interior. The maximum...

78 FR 41684 - Special Conditions: Embraer S.A. Model EMB-550 Airplanes, Sudden Engine Stoppage

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2013-07-11

... airplane has novel or unusual design features as compared to the state of technology envisioned in the airworthiness standards for transport-category airplanes. These design features include engine size and the... contain adequate or appropriate safety standards for this design feature. These special conditions contain...

78 FR 76252 - Special Conditions: Airbus, Model A350-900 Series Airplane; Isolation or Protection of the...

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2013-12-17

..., business, labor union, etc.). DOT's complete Privacy Act Statement can be found in the Federal Register... unusual design feature: an electronics network system architecture which is new and novel for commercial... series architecture is new and novel for commercial transport airplanes because it allows connection to...

THE SWIFT BAT SURVEY DETECTS TWO OPTICAL BROAD LINE, X-RAY HEAVILY OBSCURED ACTIVE GALAXIES: NVSS 193013+341047 AND IRAS 05218-1212

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hogg, J. Drew; Winter, Lisa M.; Mushotzky, Richard F.

2012-06-20

The Swift Burst Alert Telescope (BAT) is discovering interesting new objects while monitoring the sky in the 14-195 keV band. Here we present the X-ray properties and spectral energy distributions (SEDs) for two unusual active galactic nucleus sources. Both NVSS 193013+341047 and IRAS 05218-1212 are absorbed, Compton-thin, but heavily obscured (N{sub H} {approx} 10{sup 23} cm{sup -2}), X-ray sources at redshifts <0.1. The SEDs reveal these galaxies to be very red, with high extinction in the optical and UV. A similar SED is seen for the extremely red objects (EROs) detected in the higher redshift universe. This suggests that thesemore » unusual BAT-detected sources are a low-redshift (z << 1) analog to EROs, which recent evidence suggests are a class of the elusive type II quasars. Studying the multi-wavelength properties of these sources may reveal the properties of their high-redshift counterparts.« less

Doubly unusual 3D lattice honeycomb displaying simultaneous negative and zero Poisson’s ratio properties

NASA Astrophysics Data System (ADS)

Chen, Yu; Zheng, Bin-Bin; Fu, Ming-Hui; Lan, Lin-Hua; Zhang, Wen-Zhi

2018-04-01

In this paper, a novel three-dimensional (3D) lattice honeycomb is developed based on a two-dimensional (2D) accordion-like honeycomb. A combination of theoretical and numerical analysis is carried out to gain a deeper understanding of the elastic behavior of the new honeycomb and its dependence on the geometric parameters. The results show that the proposed new honeycomb can simultaneously achieve an in-plane negative Poisson’s ratio (NPR) effect and an out-of-plane zero Poisson’s ratio (ZPR) effect. This unique property may be very promising in some important fields, like aerospace, piezoelectric sensors and biomedicine engineering. The results also show that the geometric parameters, such as the slant angle, the strut thickness and the relative density, have a significant effect on the mechanical properties. Additionally, different dominant deformation models of the new honeycomb when compressed along the x (or y) and z directions are identified. This work provides a new concept for the design of honeycombs with a doubly unusual performance.

Thermodynamic and Kinetic Properties of Metal Hydrides from First-Principles Calculations

NASA Astrophysics Data System (ADS)

Michel, Kyle Jay

In an effort to minimize the worldwide dependence on fossil fuels, much research has focused on the development of hydrogen fuel cell vehicles. Among the many challenges currently facing the transition to such an alternative energy economy is the storage of hydrogen in an economical and practical way. One class of materials that has presented itself as a possible candidate is solid metal hydrides. These materials chemically bind hydrogen and on heating, release the gas which can then be used to generate power as needed for the vehicle. In order to meet guidelines that have been set for such a storage system, hydrogen must be released rapidly in a narrow temperature range of -40 to 80°C with all reactions being reversible. This sets both thermodynamic and kinetic requirements for the design of candidate metal hydrides. First-principles calculations are well-suited for the task of exploring reactions involving metal hydrides. Here, density-functional theory is used to calculate properties of these materials at the quantum mechanical level of accuracy. In particular, three systems have been investigated: 1. Li-Mg-N-H. Reactions between all known compounds in this system are systematically investigated in order to predict thermodynamically allowed reactions that release hydrogen. The properties of these reactions are compared to the requirements set for hydrogen storage systems. Additionally, ground-state structures are predicted for Li2Mg(NH)2 and Li 4Mg(NH)3. 2. Na-Al-H. The kinetics of mass transport during the (de)hydrogenation of the well-known metal hydride NaAlH4 are investigated. A model is developed to study the flux of native defects through phases involved in these reactions. Since it is also known that titanium is an effective catalyst for both dehydrogenation and rehydrogenation, the effect of Ti substitution in bulk lattices on the kinetics of mass transport is investigated. Results are compared to experiments in order to determine if mass transport represents the rate-limiting process during de- or rehydrogenation and what the effect of Ti may be. 3. Si-H. Properties of the recently synthesized compound SiH4(H 2)2 are investigated. Under high pressures, hydrogen binding to SiH4 exhibits characteristics of both physical and chemical bonds. A ground-state structure is predicted for this phase and the vibrational and bonding properties are investigated in order to determine the origin of the unusual binding between H2 and SiH4.

Transport pathways for Asian pollution outflow over the Pacific: Interannual and seasonal variations

NASA Astrophysics Data System (ADS)

Liu, Hongyu; Jacob, Daniel J.; Bey, Isabelle; Yantosca, Robert M.; Duncan, Bryan N.; Sachse, Glen W.

2003-10-01

The meteorological pathways contributing to Asian pollution outflow over the Pacific are examined with a global three-dimensional model analysis of CO observations from the Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission (February-April 2001). The model is used also to place the TRACE-P observations in an interannual (1994-2001) and seasonal context. The major process driving Asian pollution outflow in spring is frontal lifting ahead of southeastward-moving cold fronts (the leading edge of cold surges) and transport in the boundary layer behind the cold fronts. Orographic lifting over central and eastern China combines with the cold fronts to promote the transport of Chinese pollution to the free troposphere. Outflow of seasonal biomass burning in Southeast Asia during spring takes place mostly by deep convection but also by northeastward transport and frontal lifting, mixing with the anthropogenic outflow. Boundary layer outflow over the western Pacific is largely devoid of biomass burning influence. European and African (biomass burning) plumes in Asian outflow during TRACE-P were weak (<60 ppbv and 20 ppbv CO, respectively) and were not detectable in the observations because of superposition of the much larger Asian pollution signal. Spring 2001 (La Niña) was characterized by unusually frequent cold surge events in the Asian Pacific rim and strong convection in Southeast Asia, leading to unusually strong boundary layer outflow of anthropogenic emissions and convective outflow of biomass burning emissions in the upper troposphere. The Asian outflow flux of CO to the Pacific is found to vary seasonally by a factor of 3-4 (maximum in March and minimum in summer). The March maximum results from frequent cold surge events and seasonal biomass burning emissions.

Transport Pathways for Asian Pollution Outflow Over the Pacific: Interannual and Seasonal Variations

NASA Technical Reports Server (NTRS)

Liu, Hong-Yu; Jacob, Daniel J.; Bey, Isabelle; Yantosca, Robert M.; Duncan, Bryan N.; Sachse, Glen W.

2003-01-01

The meteorological pathways contributing to Asian pollution outflow over the Pacific are examined with a global three-dimensional model analysis of CO observations from the Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission (February-April 2001). The model is used also to place the TRACE-P observations in an interannual (1994-2001) and seasonal context. The major process driving Asian pollution outflow in spring is frontal lifting ahead of southeastward-moving cold fronts (the leading edge of cold surges) and transport in the boundary layer behind the cold fronts. Orographic lifting over central and eastern China combines with the cold fronts to promote the transport of Chinese pollution to the free troposphere. Outflow of seasonal biomass burning in Southeast Asia during spring takes place mostly by deep convection but also by northeastward transport and frontal lifting, mixing with the anthropogenic outflow. Boundary layer outflow over the western Pacific is largely devoid of biomass burning influence. European and African (biomass burning) plumes in Asian outflow during TRACE-P were weak (less than 60 ppbv and 20 ppbv CO, respectively) and were not detectable in the observations because of superposition of the much larger Asian pollution signal. Spring 2001 (La Nina) was characterized by unusually frequent cold surge events in the Asian Pacific rim and strong convection in Southeast Asia, leading to unusually strong boundary layer outflow of anthropogenic emissions and convective outflow of biomass burning emissions in the upper troposphere. The Asian outflow flux of CO to the Pacific is found to vary seasonally by a factor of 3-4 (maximum in March and minimum in summer). The March maximum results from frequent cold surge events and seasonal biomass burning emissions.

Liquid-like cationic sub-lattice in copper selenide clusters

NASA Astrophysics Data System (ADS)

White, Sarah L.; Banerjee, Progna; Jain, Prashant K.

2017-02-01

Super-ionic solids, which exhibit ion mobilities as high as those in liquids or molten salts, have been employed as solid-state electrolytes in batteries, improved thermoelectrics and fast-ion conductors in super-capacitors and fuel cells. Fast-ion transport in many of these solids is supported by a disordered, `liquid-like' sub-lattice of cations mobile within a rigid anionic sub-lattice, often achieved at high temperatures or pressures via a phase transition. Here we show that ultrasmall clusters of copper selenide exhibit a disordered cationic sub-lattice under ambient conditions unlike larger nanocrystals, where Cu+ ions and vacancies form an ordered super-structure similar to the bulk solid. The clusters exhibit an unusual cationic sub-lattice arrangement wherein octahedral sites, which serve as bridges for cation migration, are stabilized by compressive strain. The room-temperature liquid-like nature of the Cu+ sub-lattice combined with the actively tunable plasmonic properties of the Cu2Se clusters make them suitable as fast electro-optic switches.

Topologically protected refraction of robust kink states in valley photonic crystals

NASA Astrophysics Data System (ADS)

Gao, Fei; Xue, Haoran; Yang, Zhaoju; Lai, Kueifu; Yu, Yang; Lin, Xiao; Chong, Yidong; Shvets, Gennady; Zhang, Baile

2018-02-01

Recently discovered valley photonic crystals (VPCs) mimic many of the unusual properties of two-dimensional (2D) gapped valleytronic materials. Of the utmost interest to optical communications is their ability to support topologically protected chiral edge (kink) states at the internal domain wall between two VPCs with opposite valley-Chern indices. Here we experimentally demonstrate valley-polarized kink states with polarization multiplexing in VPCs, designed from a spin-compatible four-band model. When the valley pseudospin is conserved, we show that the kink states exhibit nearly perfect out-coupling efficiency into directional beams, through the intersection between the internal domain wall and the external edge separating the VPCs from ambient space. The out-coupling behaviour remains topologically protected even when we break the spin-like polarization degree of freedom (DOF), by introducing an effective spin-orbit coupling in one of the VPC domains. This also constitutes the first realization of spin-valley locking for topological valley transport.

Stereochemistry and function of oxaloacetate keto-enol tautomerase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Creighton, D.J.; Johnson, J.D.; Lambert, M.R.

1986-05-01

Oxaloacetate keto-enol tautomerase, partially purified from porcine kidney, catalyzes the conversions of enol- to keto-oxaloacetate by a mechanism in which solvent protons end up equally distributed between the two prochiral positions at C3 of keto-oxaloacetate. This conclusion is based upon the observation that when enzyme catalyzed ketonization is conducted in /sup 3/H/sub 2/O in the presence of excess malate dehydrogenase and NADH, only 50% of the /sup 3/H in the isolated (2S)-(3-/sup 3/H)malate is labilized to solvent upon treatment with fumarase. Either the tautomerase operates on the basis of a highly unusual stereomechanistic principle or tautomerase activity is not anmore » evolved property of the enzyme protein. As a result of an attempt to clarify the physiological importance of oxaloacetate tautomerase activity, keto-oxaloacetate was demonstrated to be directly transported across the inner membrane of rat liver mitochrondria, on the basis of the results of kinetic and isotope-trapping experiments.« less

Investigating the Origin of the Supernova Remnant W49B

NASA Astrophysics Data System (ADS)

Crum, Ryan Matthew; Frank, Kari A.; Dwarkadas, Vikram; Burrows, David N.

2018-01-01

W49B is a Galactic supernova remnant whose origin is still debated. Is it the remains of an unusual asymmetric Type 1a supernova or of a jet-driven core collapse supernova? Using the X-ray analysis method, Smoothed Particle Inference (SPI), we dig deeper into understanding the complex properties of SNR W49B. We do this by characterizing the temperatures and abundance ratios throughout the remnant. We will compare the results with a wide variety of supernova nucleosynthesis models in order to constrain the mechanism behind this unusual supernova remnant.

44 CFR Appendix A(1) to Part 61 - Appendix A(1) to Part 61

Code of Federal Regulations, 2011 CFR

2011-10-01

... only: 1. A non-condominium residential building designed for principal use as a dwelling place of one... properties (one of which is your property) from: a. Overflow of inland or tidal waters, b. Unusual and rapid... premium payment must accompany the application. 4. Base Flood. A flood having a one percent chance of...

44 CFR Appendix A(1) to Part 61 - Appendix A(1) to Part 61

Code of Federal Regulations, 2013 CFR

2013-10-01

... only: 1. A non-condominium residential building designed for principal use as a dwelling place of one... properties (one of which is your property) from: a. Overflow of inland or tidal waters, b. Unusual and rapid... premium payment must accompany the application. 4. Base Flood. A flood having a one percent chance of...

44 CFR Appendix A(1) to Part 61 - Appendix A(1) to Part 61

Code of Federal Regulations, 2012 CFR

2012-10-01

... only: 1. A non-condominium residential building designed for principal use as a dwelling place of one... properties (one of which is your property) from: a. Overflow of inland or tidal waters, b. Unusual and rapid... premium payment must accompany the application. 4. Base Flood. A flood having a one percent chance of...

44 CFR Appendix A(1) to Part 61 - Appendix A(1) to Part 61

Code of Federal Regulations, 2010 CFR

2010-10-01

... only: 1. A non-condominium residential building designed for principal use as a dwelling place of one... properties (one of which is your property) from: a. Overflow of inland or tidal waters, b. Unusual and rapid... premium payment must accompany the application. 4. Base Flood. A flood having a one percent chance of...

44 CFR Appendix A(1) to Part 61 - Appendix A(1) to Part 61

Code of Federal Regulations, 2014 CFR

2014-10-01

... only: 1. A non-condominium residential building designed for principal use as a dwelling place of one... properties (one of which is your property) from: a. Overflow of inland or tidal waters, b. Unusual and rapid... premium payment must accompany the application. 4. Base Flood. A flood having a one percent chance of...

76 FR 24787 - Blocking Property of Certain Persons With Respect to Human Rights Abuses in Syria

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-03

... Order 13572 of April 29, 2011 Blocking Property of Certain Persons With Respect to Human Rights Abuses..., finding that the Government of Syria's human rights abuses, including those related to the repression of... have engaged in human rights abuses, constitute an unusual and extraordinary threat to the national...

Unconventional transport in ultraclean graphene constriction devices

NASA Astrophysics Data System (ADS)

Pita Vidal, Marta; Ma, Qiong; Watanabe, Kenji; Taniguchi, Takashi; Jarillo-Herrero, Pablo

Under mesoscopic conditions, strong electron-electron interactions and weak electron-phonon coupling in graphene lead to hydrodynamic behavior of electrons, resulting in unusual and unexpected transport phenomena. Specifically, this hydrodynamical collective cooperation of electrons is predicted to enhance the flow of electrical current, leading to a striking higher-than-ballistic conductance through a narrow geometrical constriction. To access the hydrodynamic regime, we fabricated high-quality, low-disorder graphene nano-constriction devices encapsulated by hexagonal boron nitride, where electron-electron scattering dominates impurity scattering. We will report on our systematic four-probe conductance measurements on devices with different constriction widths as a function of number density and temperature. The observation of quantum transport phenomena that are inconsistent with the non-interacting ballistic free-fermion model would suggest a macroscopic transport signature of electron viscosity.

Unusual electron-dense dome associates with compound plasmodesmata in the embryo-suspensor of genus Sedum (Crassulaceae).

PubMed

Kozieradzka-Kiszkurno, Małgorzata; Bohdanowicz, Jerzy

2010-11-01

Plasmodesmata ensure the continuity of cytoplasm between plant cells and play an important part in the intercellular communication and signal transduction. During the development of the suspensor of both Sedum acre L. and Sedum hispanicum L., changes in the ultrastructure of plasmodesmata and adjoining cytoplasm are observed. Numerous simple plasmodesmata are present in the inner wall of the two-celled embryo separating the basal cell from the apical cell. From the early-globular to the torpedo stage of embryo development, the part of the wall separating the basal cell from the first layer of the chalazal suspensor cells is perforated by unusual, compound plasmodesmata. The role and the sort of transport through these plasmodesmata are discussed.

Tunable magneto-optical effects in hole-doped group-IIIA metal-monochalcogenide monolayers

NASA Astrophysics Data System (ADS)

Feng, Wanxiang; Guo, Guang-Yu; Yao, Yugui

2017-03-01

Because of unusual properties and fascinating prospects for next-generation device applications, two-dimensional (2D) materials have attracted enormous attention since graphene was discovered in 2004. Among the 2D materials beyond graphene, group-IIIA metal-monochalcogenide (MX) monolayers (MLs), are receiving increasing interests because their excellent applications on electronics and optoelectronics. Recently, ferromagnetism and half-metallicity have been predicted in hole-doped GaS and GaSe MLs, which promise exciting potentials for semiconductor spintronics. Detection and measurement of spontaneous magnetization in these 2D materials will be essential for their spintronic applications. The magneto-optical (MO) effects not only are a powerful probe of magnetism in 2D materials but also have valuable applications in high-density data-storage technology. Furthermore, anomalous Hall effect is not only an ideal transport probe of itinerant magnetism but also of considerable current interest because of its topological nature. Here we perform a systematic first-principles density functional study on the MO Kerr and Faraday effects as well as such important magnetic and transport properties as magneto-crystalline anisotropy energy (MAE) and anomalous Hall conductivity (AHC) of all hole-doped MX (M = Ga, In; X = S, Se, Te) MLs. In this paper, we report the following important findings: (a) gate-tunable MO effects in MX MLs in a broad range of hole concentration; (b) large Kerr and Faraday rotation angles with Kerr angles comparable to well-known MO 3d-transition-metal multilayers and Faraday angles being among the largest ones reported; (c) tunable MAE and large AHC, making MX MLs suitable for magnetic memory devices current-driven via spin-transfer torque and also promising materials for magnetic field nanosensors with high sensitivity. Superior MO characteristics, together with the other interesting properties, would make MX MLs an excellent family of 2D materials for semiconductor MO and spintronic nanodevices.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bozovic, I.; Wu, J.; He, X.

Over the course of three decades of intense study, apart from the exceptionally high critical temperature, many unusual properties of cuprates have been discovered, notably including resistivity linear in temperature, electronic Raman continuum and optical absorption extending throughout the infrared region, pseudogap, hour-glass spin excitation spectrum, etc. However, each of these features have been also observed in other materials, including some that are not even superconducting at all. Here, we describe an extensive experiment in which over 2,000 films of the La 2-xSr xCuO 4 have been synthesized and studied in detail over the course of the last twelve years.more » We argue here that, uniquely, in the cuprates an unusual superconducting state, that defies the standard BCS description, develops from an unusual metallic state, in which the rotational symmetry of the electron fluid is spontaneously broken.« less

Crystal structure of the Alcanivorax borkumensis YdaH transporter reveals an unusual topology

NASA Astrophysics Data System (ADS)

Bolla, Jani Reddy; Su, Chih-Chia; Delmar, Jared A.; Radhakrishnan, Abhijith; Kumar, Nitin; Chou, Tsung-Han; Long, Feng; Rajashankar, Kanagalaghatta R.; Yu, Edward W.

2015-04-01

The potential of the folic acid biosynthesis pathway as a target for the development of antibiotics has been clinically validated. However, many pathogens have developed resistance to these antibiotics, prompting a re-evaluation of potential drug targets within the pathway. The ydaH gene of Alcanivorax borkumensis encodes an integral membrane protein of the AbgT family of transporters for which no structural information was available. Here we report the crystal structure of A. borkumensis YdaH, revealing a dimeric molecule with an architecture distinct from other families of transporters. YdaH is a bowl-shaped dimer with a solvent-filled basin extending from the cytoplasm to halfway across the membrane bilayer. Each subunit of the transporter contains nine transmembrane helices and two hairpins that suggest a plausible pathway for substrate transport. Further analyses also suggest that YdaH could act as an antibiotic efflux pump and mediate bacterial resistance to sulfonamide antimetabolite drugs.

76 FR 63823 - Special Conditions: Gulfstream Aerospace LP (GALP) Model G280 Airplane Pilot-Compartment View...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-14

... DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 25 [Docket No. NM457; Notice No. 25-449-SC] Special Conditions: Gulfstream Aerospace LP (GALP) Model G280 Airplane Pilot... Gulfstream Aerospace LP (GALP) Model G280 airplane. This airplane will have a novel or unusual design feature...

Unusual distribution of floating seaweeds in the East China Sea in the early spring of 2012.

PubMed

Komatsu, Teruhisa; Mizuno, Shizuha; Natheer, Alabsi; Kantachumpoo, Attachai; Tanaka, Kiyoshi; Morimoto, Akihiko; Hsiao, Sheng-Tai; Rothäusler, Eva A; Shishidou, Hirotoshi; Aoki, Masakazu; Ajisaka, Tetsuro

2014-01-01

Floating seaweeds play important ecological roles in offshore waters. Recently, large amounts of rafting seaweed have been observed in the East China Sea. In early spring, juveniles of commercially important fish such as yellowtail accompany these seaweed rafts. Because the spatial distributions of seaweed rafts in the spring are poorly understood, research cruises were undertaken to investigate them in 2010, 2011, and 2012. Floating seaweed samples collected from the East China Sea during the three surveys contained only Sargassum horneri . In 2010 and 2011, seaweed rafts were distributed only in the continental shelf and the Kuroshio Front because they had become trapped in the convergence zone of the Kuroshio Front. However, in 2012, seaweed was also distributed in the Kuroshio Current and its outer waters, and massive strandings of seaweed rafts were observed on the northern coast of Taiwan and on Tarama Island in the Ryukyu Archipelago. Environmental data (wind, currents, and sea surface height) were compared among the surveys of 2010, 2011, and 2012. Two factors are speculated to have caused the unusual distribution in 2012. First, a continuous strong north wind produced an Ekman drift current that transported seaweed southwestward to the continental shelf and eventually stranded seaweed rafts on the coast of Taiwan. Second, an anticyclonic eddy covering northeast Taiwan and the Kuroshio Current west of Taiwan generated a geostrophic current that crossed the Kuroshio Current and transported the rafts to the Kuroshio Current and its outer waters. Such unusual seaweed distributions may influence the distribution of fauna accompanying the rafts.

Unusual photoelectric behaviors of Mo-doped TiO2 multilayer thin films prepared by RF magnetron co-sputtering: effect of barrier tunneling on internal charge transfer

NASA Astrophysics Data System (ADS)

Yan, B. X.; Luo, S. Y.; Mao, X. G.; Shen, J.; Zhou, Q. F.

2013-01-01

Mo-doped TiO2 multilayer thin films were prepared by RF magnetron co-sputtering. Microstructures, crystallite parameters and the absorption band were investigated with atomic force microscopy, X-ray diffraction and ultraviolet-visible spectroscopy. Internal carrier transport characteristics and the photoelectric property of different layer-assemble modes were examined on an electrochemical workstation under visible light. The result indicates that the double-layer structure with an undoped surface layer demonstrated a red-shifted absorption edge and a much stronger photocurrent compared to the uniformly doped sample, signifying that the electric field implanted at the interface between particles in different layers accelerated internal charge transfer effectively. However, a heavily doped layer implanted at the bottom of the three-layer film merely brought about negative effects on the photoelectric property, mainly because of the Schottky junction existing above the substrate. Nevertheless, this obstacle was successfully eliminated by raising the Mo concentration to 1020 cm-3, where the thickness of the depletion layer fell into the order of angstroms and the tunneling coefficient manifested a dramatic increase. Under this circumstance, the Schottky junction disappeared and the strongest photocurrent was observed in the three-layer film.

The Shape of Things: The Origin of Young Children's Knowledge of the Names and Properties of Geometric Forms

ERIC Educational Resources Information Center

Verdine, Brian N.; Lucca, Kelsey R.; Golinkoff, Roberta M.; Hirsh-Pasek, Kathryn; Newcombe, Nora S.

2016-01-01

How do toddlers learn the names of geometric forms? Previous work suggests that preschoolers have fragmentary knowledge and that defining properties are not understood until well into elementary school. The current study investigated when children first begin to understand shape names and how they apply those labels to unusual instances. We tested…

Exploding Water Drops

ERIC Educational Resources Information Center

Reich, Gary

2016-01-01

Water has the unusual property that it expands on freezing, so that ice has a specific gravity of 0.92 compared to 1.0 for liquid water. The most familiar demonstration of this property is ice cubes floating in a glass of water. A more dramatic demonstration is the ice bomb shown in Fig. 1. Here a cast iron flask is filled with water and tightly…

?-BiPd: a clean noncentrosymmetric superconductor

NASA Astrophysics Data System (ADS)

Ramakrishnan, Srinivasan; Joshi, Bhanu; Thamizhavel, A.

2017-12-01

We present a comprehensive review of the normal and superconducting state properties of a high-quality single crystal of monoclinic BiPd (?-BiPd, space group ?). The superconductivity of this crystal below 3.8 K is established by measuring its properties using bulk as well as spectroscopic techniques. BiPd is one of the cleanest noncentrosymmetric superconductors that display superconductivity with multiple energy gaps. Evidence of multiple energy gaps was found in heat capacity, point contact (PC) spectroscopy, penetration depth, muon spin rotation, small angle neutron scattering and NMR/NQR measurements. Moreover, Muon spin rotation measurements also suggest strong field dependence of the penetration depth of this superconductor. Unusual superconducting properties due to possible s and p wave mixing are shown by the observation of Andreev bound state in PC measurements as well as the suppressed coherence peak in the temperature dependence of the spin-lattice relaxation in the NQR measurements. This surmise is at variance with the recent STM measurements (different crystal). The observed unusual properties and multiband superconductivity are extremely sensitive to disorder in BiPd. Finally, there is a possibility of tuning the electron correlations by selective substitution in BiPd, thus making it an important system for further investigations.

A comparison of blood nitric oxide metabolites and hemoglobin functional properties among diving mammals.

PubMed

Fago, Angela; Parraga, Daniel Garcia; Petersen, Elin E; Kristensen, Niels; Giouri, Lea; Jensen, Frank B

2017-03-01

The ability of marine mammals to hunt prey at depth is known to rely on enhanced oxygen stores and on selective distribution of blood flow, but the molecular mechanisms regulating blood flow and oxygen transport remain unresolved. To investigate the molecular mechanisms that may be important in regulating blood flow, we measured concentration of nitrite and S-nitrosothiols (SNO), two metabolites of the vasodilator nitric oxide (NO), in the blood of 5 species of marine mammals differing in their dive duration: bottlenose dolphin, South American sea lion, harbor seal, walrus and beluga whale. We also examined oxygen affinity, sensitivity to 2,3-diphosphoglycerate (DPG) and nitrite reductase activity of the hemoglobin (Hb) to search for possible adaptive variations in these functional properties. We found levels of plasma and red blood cells nitrite similar to those reported for terrestrial mammals, but unusually high concentrations of red blood cell SNO in bottlenose dolphin, walrus and beluga whale, suggesting enhanced SNO-dependent signaling in these species. Purified Hbs showed similar functional properties in terms of oxygen affinity and sensitivity to DPG, indicating that reported large variations in blood oxygen affinity among diving mammals likely derive from phenotypic variations in red blood cell DPG levels. The nitrite reductase activities of the Hbs were overall slightly higher than that of human Hb, with the Hb of beluga whale, capable of longest dives, having the highest activity. Taken together, these results underscore adaptive variations in circulatory NO metabolism in diving mammals but not in the oxygenation properties of the Hb. Copyright © 2016 Elsevier Inc. All rights reserved.

Graphene-based composite materials.

PubMed

Stankovich, Sasha; Dikin, Dmitriy A; Dommett, Geoffrey H B; Kohlhaas, Kevin M; Zimney, Eric J; Stach, Eric A; Piner, Richard D; Nguyen, SonBinh T; Ruoff, Rodney S

2006-07-20

Graphene sheets--one-atom-thick two-dimensional layers of sp2-bonded carbon--are predicted to have a range of unusual properties. Their thermal conductivity and mechanical stiffness may rival the remarkable in-plane values for graphite (approximately 3,000 W m(-1) K(-1) and 1,060 GPa, respectively); their fracture strength should be comparable to that of carbon nanotubes for similar types of defects; and recent studies have shown that individual graphene sheets have extraordinary electronic transport properties. One possible route to harnessing these properties for applications would be to incorporate graphene sheets in a composite material. The manufacturing of such composites requires not only that graphene sheets be produced on a sufficient scale but that they also be incorporated, and homogeneously distributed, into various matrices. Graphite, inexpensive and available in large quantity, unfortunately does not readily exfoliate to yield individual graphene sheets. Here we present a general approach for the preparation of graphene-polymer composites via complete exfoliation of graphite and molecular-level dispersion of individual, chemically modified graphene sheets within polymer hosts. A polystyrene-graphene composite formed by this route exhibits a percolation threshold of approximately 0.1 volume per cent for room-temperature electrical conductivity, the lowest reported value for any carbon-based composite except for those involving carbon nanotubes; at only 1 volume per cent, this composite has a conductivity of approximately 0.1 S m(-1), sufficient for many electrical applications. Our bottom-up chemical approach of tuning the graphene sheet properties provides a path to a broad new class of graphene-based materials and their use in a variety of applications.

Coatings and Biodegradable and Bioabsorbable Films

DTIC Science & Technology

2006-09-01

Properties Properties (Latex) Properties (Paint) M1. 726-39 Sodium lauryl sulfate 2.27 phi Control APS Viscous caossy, some Acceptablecracks, fo a y" l...SS 726-49 Sodium laufyl sulfate 2.17 phr Control APS Viscous, foamy Cracks in film Foam SIS 726-51 Sodium lauryl sulfate 2.17 phi Control APS Crashed...Not Formulated Not Formulated SS 726-35 Sodium lauryl sulfate 2.17 phr Control APS Acceptable Glossy with some Unusually foamy ________ _______fo am

Narrow Groove and Restricted Anchors of MHC Class I Molecule BF2*0401 Plus Peptide Transporter Restriction can Explain Disease Susceptibility of B4 Chickens

PubMed Central

Zhang, Jianhua; Chen, Yong; Qi, Jianxun; Gao, Feng; Liu, Yanjie; Liu, Jun; Zhou, Xuyu; Kaufman, Jim; Xia, Chun; Gao, George F.

2016-01-01

The major histocompatibility complex (MHC) has genetic associations with many diseases, often due to differences in presentation of antigenic peptides by polymorphic MHC molecules to T lymphocytes of the immune system. In chickens, only a single classical class I molecule in each MHC haplotype is expressed well due to co-evolution with the polymorphic transporters associated with antigen presentation (TAPs), which means that resistance and susceptibility to infectious pathogens are particularly easy to observe. Previously, structures of chicken MHC class I molecule BF2*2101 from B21 haplotype showed an unusually large peptide-binding groove that accommodates a broad spectrum of peptides to present as epitopes to cytotoxic T lymphocytes (CTL), explaining the MHC-determined resistance of B21 chickens to Marek's disease. Here, we report the crystal structure of BF2*0401 from the B4 (also known as B13) haplotype, showing a highly positively-charged surface hitherto unobserved in other MHC molecules, as well as a remarkably narrow groove due to the allele-specific residues with bulky side chains. Together, these properties limit the number of epitope peptides that can bind this class I molecule. However, peptide-binding assays show that in vitro BF2*0401 can bind a wider variety of peptides than are found on the surface of B4 cells. Thus, a combination of the specificities of the polymorphic TAP transporter and the MHC results in a very limited set of BF2*0401 peptides with negatively charged anchors to be presented to T lymphocytes. PMID:23041567

Physiological and molecular triggers for SARS-CoV membrane fusion and entry into host cells.

PubMed

Millet, Jean Kaoru; Whittaker, Gary R

2018-04-01

During viral entry, enveloped viruses require the fusion of their lipid envelope with host cell membranes. For coronaviruses, this critical step is governed by the virally-encoded spike (S) protein, a class I viral fusion protein that has several unique features. Coronavirus entry is unusual in that it is often biphasic in nature, and can occur at or near the cell surface or in late endosomes. Recent advances in structural, biochemical and molecular biology of the coronavirus S protein has shed light on the intricacies of coronavirus entry, in particular the molecular triggers of coronavirus S-mediated membrane fusion. Furthermore, characterization of the coronavirus fusion peptide (FP), the segment of the fusion protein that inserts to a target lipid bilayer during membrane fusion, has revealed its particular attributes which imparts some of the unusual properties of the S protein, such as Ca 2+ -dependency. These unusual characteristics can explain at least in part the biphasic nature of coronavirus entry. In this review, using severe acute respiratory syndrome coronavirus (SARS-CoV) as model virus, we give an overview of advances in research on the coronavirus fusion peptide with an emphasis on its role and properties within the biological context of host cell entry. Copyright © 2017 Elsevier Inc. All rights reserved.

Emergent structures in reaction-advection-diffusion systems on a sphere.

PubMed

Krause, Andrew L; Burton, Abigail M; Fadai, Nabil T; Van Gorder, Robert A

2018-04-01

We demonstrate unusual effects due to the addition of advection into a two-species reaction-diffusion system on the sphere. We find that advection introduces emergent behavior due to an interplay of the traditional Turing patterning mechanisms with the compact geometry of the sphere. Unidirectional advection within the Turing space of the reaction-diffusion system causes patterns to be generated at one point of the sphere, and transported to the antipodal point where they are destroyed. We illustrate these effects numerically and deduce conditions for Turing instabilities on local projections to understand the mechanisms behind these behaviors. We compare this behavior to planar advection which is shown to only transport patterns across the domain. Analogous transport results seem to hold for the sphere under azimuthal transport or away from the antipodal points in unidirectional flow regimes.

Emergent structures in reaction-advection-diffusion systems on a sphere

NASA Astrophysics Data System (ADS)

Krause, Andrew L.; Burton, Abigail M.; Fadai, Nabil T.; Van Gorder, Robert A.

2018-04-01

We demonstrate unusual effects due to the addition of advection into a two-species reaction-diffusion system on the sphere. We find that advection introduces emergent behavior due to an interplay of the traditional Turing patterning mechanisms with the compact geometry of the sphere. Unidirectional advection within the Turing space of the reaction-diffusion system causes patterns to be generated at one point of the sphere, and transported to the antipodal point where they are destroyed. We illustrate these effects numerically and deduce conditions for Turing instabilities on local projections to understand the mechanisms behind these behaviors. We compare this behavior to planar advection which is shown to only transport patterns across the domain. Analogous transport results seem to hold for the sphere under azimuthal transport or away from the antipodal points in unidirectional flow regimes.

A new simple tiling, with unusual properties, by a polyhedron with 14 faces.

PubMed

Gabbrielli, Ruggero; O'Keeffe, Michael

2008-05-01

A monotypic simple tiling by a 14-face polyhedron that does not admit an isohedral tiling is described. The tiling is triclinic and contains four distinct, but combinatorially equivalent, kinds of tile.

Biopsy

MedlinePlus

... report). The biopsy test is not an exact science. In cases of difficult or unusual problems, second opinions can be helpful. Back to Index The medical information provided in this site is for educational purposes only and is the property of the American ...

Landau quantization of Dirac fermions in graphene and its multilayers

NASA Astrophysics Data System (ADS)

Yin, Long-Jing; Bai, Ke-Ke; Wang, Wen-Xiao; Li, Si-Yu; Zhang, Yu; He, Lin

2017-08-01

When electrons are confined in a two-dimensional (2D) system, typical quantum-mechanical phenomena such as Landau quantization can be detected. Graphene systems, including the single atomic layer and few-layer stacked crystals, are ideal 2D materials for studying a variety of quantum-mechanical problems. In this article, we review the experimental progress in the unusual Landau quantized behaviors of Dirac fermions in monolayer and multilayer graphene by using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). Through STS measurement of the strong magnetic fields, distinct Landau-level spectra and rich level-splitting phenomena are observed in different graphene layers. These unique properties provide an effective method for identifying the number of layers, as well as the stacking orders, and investigating the fundamentally physical phenomena of graphene. Moreover, in the presence of a strain and charged defects, the Landau quantization of graphene can be significantly modified, leading to unusual spectroscopic and electronic properties.

A putative vesicular transporter expressed in Drosophila mushroom bodies that mediates sexual behavior may define a novel neurotransmitter system

PubMed Central

Brooks, Elizabeth S.; Greer, Christina L.; Romero-Calderón, Rafael; Serway, Christine N.; Grygoruk, Anna; Haimovitz, Jasmine M.; Nguyen, Bac T.; Najibi, Rod; Tabone, Christopher J.; de Belle, J. Steven; Krantz, David E.

2011-01-01

Summary Storage and release of classical and amino acid neurotransmitters requires vesicular transporters. Some neurons lack known vesicular transporters, suggesting additional neurotransmitter systems remain unidentified. Insect mushroom bodies (MBs) are critical for several behaviors, including learning, but the neurotransmitters released by the intrinsic Kenyon cells (KCs) remain unknown. Likewise, KCs do not express a known vesicular transporter. We report the identification of a novel Drosophila gene portabella (prt) that is structurally similar to known vesicular transporters. Both larval and adult brains express PRT in the KCs of the MBs. Additional PRT cells project to the central complex and optic ganglia. prt mutation causes an olfactory learning deficit and an unusual defect in the male’s position during copulation that is rescued by expression in KCs. Since prt is expressed in neurons that lack other known vesicular transporters or neurotransmitters, it may define a previously unknown neurotransmitter system responsible for sexual behavior and a component of olfactory learning. PMID:22017990

Fitting Transporter Activities to Cellular Drug Concentrations and Fluxes: Why the Bumblebee Can Fly

PubMed Central

Mendes, Pedro; Oliver, Stephen G.; Kell, Douglas B.

2015-01-01

A recent paper in this journal argued that reported expression levels, kcat and Km for drug transporters could be used to estimate the likelihood that drug fluxes through Caco-2 cells could be accounted for solely by protein transporters. It was in fact concluded that if five such transporters contributed ‘randomly’ they could account for the flux of the most permeable drug tested (verapamil) 35% of the time. However, the values of permeability cited for verapamil were unusually high; this and other drugs have much lower permeabilities. Even for the claimed permeabilities, we found that a single ‘random’ transporter could account for the flux 42% of the time, and that two transporters can achieve 10 · 10−6 cm·s−1 90% of the time. Parameter optimisation methods show that even a single transporter can account for Caco-2 drug uptake of the most permeable drug. Overall, the proposal that ‘phospholipid bilayer diffusion (of drugs) is negligible’ is not disproved by the calculations of ‘likely’ transporter-based fluxes. PMID:26538313

Harnessing out-of-plane deformation to design 3D architected lattice metamaterials with tunable Poisson's ratio.

PubMed

Li, Tiantian; Hu, Xiaoyi; Chen, Yanyu; Wang, Lifeng

2017-08-21

Auxetic materials exhibiting a negative Poisson's ratio are of great research interest due to their unusual mechanical responses and a wide range of potential deployment. Efforts have been devoted to exploring novel 2D and 3D auxetic structures through rational design, optimization, and taking inspiration from nature. Here we report a 3D architected lattice system showing a negative Poisson's ratio over a wide range of applied uniaxial stretch. 3D printing, experimental tests, numerical simulation, and analytical modeling are implemented to quantify the evolution of the Poisson's ratio and reveal the underlying mechanisms responsible for this unusual behavior. We further show that the auxetic behavior can be controlled by tailoring the geometric features of the ligaments. The findings reported here provide a new routine to design architected metamaterial systems exhibiting unusual properties and having a wide range of potential applications.

Study of an Unusual Advanced Glycation End-Product (AGE) Derived from Glyoxal Using Mass Spectrometry

NASA Astrophysics Data System (ADS)

Lopez-Clavijo, Andrea F.; Duque-Daza, Carlos A.; Romero Canelon, Isolda; Barrow, Mark P.; Kilgour, David; Rabbani, Naila; Thornalley, Paul J.; O'Connor, Peter B.

2014-04-01

Glycation is a post-translational modification (PTM) that affects the physiological properties of peptides and proteins. In particular, during hyperglycaemia, glycation by α-dicarbonyl compounds generate α-dicarbonyl-derived glycation products also called α-dicarbonyl-derived advanced glycation end products. Glycation by the α-dicarbonyl compound known as glyoxal was studied in model peptides by MS/MS using a Fourier transform ion cyclotron resonance mass spectrometer. An unusual type of glyoxal-derived AGE with a mass addition of 21.98436 Da is reported in peptides containing combinations of two arginine-two lysine, and one arginine-three lysine amino acid residues. Electron capture dissociation and collisionally activated dissociation results supported that the unusual glyoxal-derived AGE is formed at the guanidino group of arginine, and a possible structure is proposed to illustrate the 21.9843 Da mass addition.

What is really extraordinary in cuprate superconductors?

DOE PAGES

Bozovic, I.; Wu, J.; He, X.; ...

2018-03-07

Over the course of three decades of intense study, apart from the exceptionally high critical temperature, many unusual properties of cuprates have been discovered, notably including resistivity linear in temperature, electronic Raman continuum and optical absorption extending throughout the infrared region, pseudogap, hour-glass spin excitation spectrum, etc. However, each of these features have been also observed in other materials, including some that are not even superconducting at all. Here, we describe an extensive experiment in which over 2,000 films of the La 2-xSr xCuO 4 have been synthesized and studied in detail over the course of the last twelve years.more » We argue here that, uniquely, in the cuprates an unusual superconducting state, that defies the standard BCS description, develops from an unusual metallic state, in which the rotational symmetry of the electron fluid is spontaneously broken.« less

Unusual solar energetic proton fluxes at 1 AU within an interplanetary CME

NASA Astrophysics Data System (ADS)

Mulligan, T.; Blake, J. B.; Mewaldt, R. A.

In mid December 2006 several flares on the Sun occurred in rapid succession, spawning several CMEs and bathing the Earth in multiple solar energetic particle (SEP) events. One such SEP occurring on December 15th was observed at the Earth just as an interplanetary CME (ICME) from a previous flare on December 13th was transiting the Earth. Although solar wind observations during this time show typical energetic proton fluxes from the prior SEP and IP shock driven ahead of the ICME, as the ICME passes the Earth unusual energetic particle signatures are observed. Measurements from ACE, Wind, and STEREO show unusual proton flux variations at energies ranging from ~3 MeV up to greater than 70 MeV. Within the Earth’s magnetosphere Polar HIST also sees unusual proton flux variations at energies greater than 10 MeV while crossing open field lines in the southern polar cap. However, no such variation in the energetic proton flux is observed at the GOES 10 or GOES 11 spacecraft in geosynchronous orbit. Differential fluxes observed at GOES 12 in the 15-40 MeV energy range show some variation. However, the overall energetic particle signature within the ICME at GEO orbits remains unclear. This event illustrates the need for caution when using GEO data in statistical studies of SEP events and in interplanetary models of energetic particle transport to 1 AU.

Anomalously Soft Non-Euclidean Springs

NASA Astrophysics Data System (ADS)

Levin, Ido; Sharon, Eran

2016-01-01

In this work we study the mechanical properties of a frustrated elastic ribbon spring—the non-Euclidean minimal spring. This spring belongs to the family of non-Euclidean plates: it has no spontaneous curvature, but its lateral intrinsic geometry is described by a non-Euclidean reference metric. The reference metric of the minimal spring is hyperbolic, and can be embedded as a minimal surface. We argue that the existence of a continuous set of such isometric minimal surfaces with different extensions leads to a complete degeneracy of the bulk elastic energy of the minimal spring under elongation. This degeneracy is removed only by boundary layer effects. As a result, the mechanical properties of the minimal spring are unusual: the spring is ultrasoft with a rigidity that depends on the thickness t as t7 /2 and does not explicitly depend on the ribbon's width. Moreover, we show that as the ribbon is widened, the rigidity may even decrease. These predictions are confirmed by a numerical study of a constrained spring. This work is the first to address the unusual mechanical properties of constrained non-Euclidean elastic objects.

Computer predictions on Rh-based double perovskites with unusual electronic and magnetic properties

NASA Astrophysics Data System (ADS)

Halder, Anita; Nafday, Dhani; Sanyal, Prabuddha; Saha-Dasgupta, Tanusri

2018-03-01

In search for new magnetic materials, we make computer prediction of structural, electronic and magnetic properties of yet-to-be synthesized Rh-based double perovskite compounds, Sr(Ca)2BRhO6 (B=Cr, Mn, Fe). We use combination of evolutionary algorithm, density functional theory, and statistical-mechanical tool for this purpose. We find that the unusual valence of Rh5+ may be stabilized in these compounds through formation of oxygen ligand hole. Interestingly, while the Cr-Rh and Mn-Rh compounds are predicted to be ferromagnetic half-metals, the Fe-Rh compounds are found to be rare examples of antiferromagnetic and metallic transition-metal oxide with three-dimensional electronic structure. The computed magnetic transition temperatures of the predicted compounds, obtained from finite temperature Monte Carlo study of the first principles-derived model Hamiltonian, are found to be reasonably high. The prediction of favorable growth condition of the compounds, reported in our study, obtained through extensive thermodynamic analysis should be useful for future synthesize of this interesting class of materials with intriguing properties.

Hinge-like structure induced unusual properties of black phosphorus and new strategies to improve the thermoelectric performance

PubMed Central

Qin, Guangzhao; Yan, Qing-Bo; Qin, Zhenzhen; Yue, Sheng-Ying; Cui, Hui-Juan; Zheng, Qing-Rong; Su, Gang

2014-01-01

We systematically investigated the geometric, electronic and thermoelectric (TE) properties of bulk black phosphorus (BP) under strain. The hinge-like structure of BP brings unusual mechanical responses such as anisotropic Young's modulus and negative Poisson's ratio. A sensitive electronic structure of BP makes it transform among metal, direct and indirect semiconductors under strain. The maximal figure of merit ZT of BP is found to be 0.72 at 800 K that could be enhanced to 0.87 by exerting an appropriate strain, revealing BP could be a potential medium-high temperature TE material. Such strain-induced enhancements of TE performance are often observed to occur at the boundary of the direct-indirect band gap transition, which can be attributed to the increase of degeneracy of energy valleys at the transition point. By comparing the structure of BP with SnSe, a family of potential TE materials with hinge-like structure are suggested. This study not only exposes various novel properties of BP under strain, but also proposes effective strategies to seek for better TE materials. PMID:25374306

75 FR 50688 - Special Conditions: Erickson Air-Crane Incorporated S-64E and S-64F Rotorcraft

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-17

...) model S-64E and S-64F rotorcraft. These rotorcraft have novel or unusual design features associated with being transport category rotorcraft designed only for use in heavy external-load operations. At the time...) Powerplant Instruments. At the time of original certification, the S-64 had a novel design of being powered...

Biosynthesis of Bacterial Cell Walls.

DTIC Science & Technology

amino acid accumulation level in Lactobacillus plantarum and Streptococcus faecalis despite a normal initial transport rate. In the course of these...biosynthesis of a dipeptide, D-alanylcysteine; A demonstration that a pantothenic acid deficiency renders L. plantarum unusually sensitive to lysozyme digestion...A quantitative description of the lipid constituents of S. faecalis and L. plantarum ; An investigation of the biochemical basis of a marked lytic

ELLIPSOMETRY OF ELECTROCHEMICAL SURFACE LAYERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muller, R.H.

1977-06-01

Ellipsometry is concerned with the analysis and interpretation of changes in the state of polarization caused by reflection. The technique has found increasing interest in recent years for the measurement of thin films because it is unusually sensitive, disturbs the object minimally and can be applied to surfaces contained in any optically transparent medium. Film thicknesses amenable to measurement range from fractional monoatomic coverage to microscopic thicknesses. The measurement of changes in the state of polarization of light due to reflection provides an unusually sensitive tool for observing surface layers in any optically transparent environment. A fast, self-compensating ellipsometer hasmore » been used to observe the electrochemical formation of reacted surface layers. The optical effect of mass-transport boundary layers and component imperfections have been taken into account in the interpretation of results.« less

A Preliminary Attempt at Sintering an Ultrafine Alumina Powder Using Microwaves

DTIC Science & Technology

1994-09-01

and unusual properties [Ref. B4]. Dielectric properties of individual ceramic phases differ depending on parameters such as compositicn...useful parameter is an estimate of the amount of power dissipated into a dielectric with a known effective loss factor. For a high frequency electric...cavities, and their influence in ceramic samples must be considered. Therefore scattering, diffraction, interference, and reflection and refraction

Robust tunability of magnetoresistance in half-Heusler R PtBi ( R = Gd , Dy, Tm, and Lu) compounds

DOE PAGES

Mun, Eundeok; Bud'ko, Sergey L.; Canfield, Paul C.

2016-03-15

We present the magnetic field dependencies of transport properties for RPtBi ( R = Gd, Dy, Tm, and Lu) half-Heusler compounds. Temperature- and field-dependent resistivity measurements of high-quality RPtBi single crystals reveal an unusually large, nonsaturating magnetoresistance (MR) up to 300 K under a moderate magnetic field of H = 140 kOe. At 300 K, the large MR effect decreases as the rare earth is traversed from Gd to Lu and the magnetic field dependence of MR shows a deviation from the conventional H2 behavior. The Hall coefficient ( RH) for R = Gd indicates a sign change around 120more » K, whereas RH curves for R = Dy, Tm, and Lu remain positive for all measured temperatures. At 300 K, the Hall resistivity reveals a deviation from the linear field dependence for all compounds. Thermoelectric power measurements on this family show strong temperature and magnetic field dependencies which are consistent with resistivity measurements. A highly enhanced thermoelectric power under applied magnetic field is observed as high as ~100 μV/K at 140 kOe. Furthermore, analysis of the transport data in this series reveals that the rare-earth-based half-Heusler compounds provide opportunities to tune MR effect through lanthanide contraction and to elucidate the mechanism of nontrivial MR.« less

Intestinal absorption of the acetamiprid neonicotinoid by Caco-2 cells: transepithelial transport, cellular uptake and efflux.

PubMed

Brunet, Jean-Luc; Maresca, Marc; Fantini, Jacques; Belzunces, Luc P

2008-01-01

The human intestinal absorption of acetamiprid (AAP) using the Caco-2 cell line reveals that AAP flux was active in a bidirectional mode with an apparent permeability coefficient of 26 x 10(-6) cm x s(-1) at 37 degrees C. Apical uptake was concentration-dependent and unsaturated for AAP concentrations up to 200 micro M. AAP cell preloading demonstrated the involvement of active transport mechanisms. Arrhenius plot analysis revealed an unusual profile with two apparent activation energies suggesting two transport processes. Uptake Vi studies indicated the involvement of a sodium-dependent transporter, the presence of a common transporter of AAP and nicotine and the involvement of Ti-sensitive ATP-dependent efflux transporters. Apical efflux investigations showed the involvement of inward active transporter(s). Whereas vincristine had no effect on intracellular accumulation, taxol and daunorubicin treatments unexpectedly led to 10% and 23% reductions respectively, suggesting that the latter shared a common inward transporter with AAP. All these results suggest full and express AAP absorption in vivo with transport involving both inward and outward, passive and active mechanisms. Thus, AAP or its metabolites could be representative of a risk for human health after its ingestion in food.

Transport properties in the atmosphere of Jupiter

NASA Technical Reports Server (NTRS)

Biolsi, L., Jr.

1979-01-01

Activities reported include: (1) testing of the computer program used to obtain transport properties for the Hulburt-Hirschfelder potential; (2) calculation of transport properties for the C2-C interaction; (3) preliminary calculations for the C2-C2 interaction; (4) calculation of transport properties for the C2H-He interaction; (5) consideration of the effect of inelastic collisions on the transport properties; and (6) the use of the Hulburt-Hirschfelder potential to model ion-atom interactions.

Decoupling catalytic activity from biological function of the ATPase that powers lipopolysaccharide transport

PubMed Central

Sherman, David J.; Lazarus, Michael B.; Murphy, Lea; Liu, Charles; Walker, Suzanne; Ruiz, Natividad; Kahne, Daniel

2014-01-01

The cell surface of Gram-negative bacteria contains lipopolysaccharides (LPS), which provide a barrier against the entry of many antibiotics. LPS assembly involves a multiprotein LPS transport (Lpt) complex that spans from the cytoplasm to the outer membrane. In this complex, an unusual ATP-binding cassette transporter is thought to power the extraction of LPS from the outer leaflet of the cytoplasmic membrane and its transport across the cell envelope. We introduce changes into the nucleotide-binding domain, LptB, that inactivate transporter function in vivo. We characterize these residues using biochemical experiments combined with high-resolution crystal structures of LptB pre- and post-ATP hydrolysis and suggest a role for an active site residue in phosphate exit. We also identify a conserved residue that is not required for ATPase activity but is essential for interaction with the transmembrane components. Our studies establish the essentiality of ATP hydrolysis by LptB to power LPS transport in cells and suggest strategies to inhibit transporter function away from the LptB active site. PMID:24639492

A dual-porosity model for simulating solute transport in oil shale

USGS Publications Warehouse

Glover, K.C.

1987-01-01

A model is described for simulating three-dimensional groundwater flow and solute transport in oil shale and associated geohydrologic units. The model treats oil shale as a dual-porosity medium by simulating flow and transport within fractures using the finite-element method. Diffusion of solute between fractures and the essentially static water of the shale matrix is simulated by including an analytical solution that acts as a source-sink term to the differential equation of solute transport. While knowledge of fracture orientation and spacing is needed to effectively use the model, it is not necessary to map the locations of individual fractures. The computer program listed in the report incorporates many of the features of previous dual-porosity models while retaining a practical approach to solving field problems. As a result the theory of solute transport is not extended in any appreciable way. The emphasis is on bringing together various aspects of solute transport theory in a manner that is particularly suited to the unusual groundwater flow and solute transport characteristics of oil shale systems. (Author 's abstract)

When is a cell not a cell? A theory relating coenocytic structure to the unusual electrophysiology of Ventricaria ventricosa (Valonia ventricosa).

PubMed

Shepherd, V A; Beilby, M J; Bisson, M A

2004-06-01

Ventricaria ventricosa and its relatives have intrigued cell biologists and electrophysiologists for over a hundred years. Historically, electrophysiologists have regarded V. ventricosa as a large single plant cell with unusual characteristics including a small and positive vacuole-to-outside membrane potential difference. However, V. ventricosa has a coenocytic construction, with an alveolate cytoplasm interpenetrated by a complex vacuole containing sulphated polysaccharides. We present a theory relating the coenocytic structure to the unusual electrophysiology of V. ventricosa. The alveolate cytoplasm of V. ventricosa consists of a collective of uninucleate cytoplasmic domains interconnected by fine cytoplasmic strands containing microtubules. The cytoplasm is capable of disassociating into single cytoplasmic domains or aggregations of domains that can regenerate new coenocytes. The cytoplasmic domains are enclosed by outer (apical) and inner (basolateral) faces of a communal membrane with polarised K(+)-transporting functions, stabilised by microtubules and resembling a tissue such as a polarised epithelium. There is evidence for membrane trafficking through endocytosis and exocytosis and so "plasmalemma" and "tonoplast" do not have fixed identities. Intra- and extracellular polysaccharide mucilage has effects on electrophysiology through reducing the activity of water and through ion exchange. The vacuole-to-outside potential difference, at which the cell membrane conductance is maximal, reverses its sign from positive under hypertonic conditions to negative under hypotonic conditions. The marked mirror symmetry of the characteristics of current as a function of voltage and conductance as a function of voltage is interpreted as a feature of the communal membrane with polarised K(+) transport. The complex inhomogeneous structure of the cytoplasm places in doubt previous measurements of cytoplasm-to-outside potential difference.

Proton movement and coupling in the POT family of peptide transporters

PubMed Central

Parker, Joanne L.; Li, Chenghan; Brinth, Allete; Wang, Zhi; Vogeley, Lutz; Solcan, Nicolae; Ledderboge-Vucinic, Gregory; Swanson, Jessica M. J.; Caffrey, Martin; Voth, Gregory A.

2017-01-01

POT transporters represent an evolutionarily well-conserved family of proton-coupled transport systems in biology. An unusual feature of the family is their ability to couple the transport of chemically diverse ligands to an inwardly directed proton electrochemical gradient. For example, in mammals, fungi, and bacteria they are predominantly peptide transporters, whereas in plants the family has diverged to recognize nitrate, plant defense compounds, and hormones. Although recent structural and biochemical studies have identified conserved sites of proton binding, the mechanism through which transport is coupled to proton movement remains enigmatic. Here we show that different POT transporters operate through distinct proton-coupled mechanisms through changes in the extracellular gate. A high-resolution crystal structure reveals the presence of ordered water molecules within the peptide binding site. Multiscale molecular dynamics simulations confirm proton transport occurs through these waters via Grotthuss shuttling and reveal that proton binding to the extracellular side of the transporter facilitates a reorientation from an inward- to outward-facing state. Together these results demonstrate that within the POT family multiple mechanisms of proton coupling have likely evolved in conjunction with variation of the extracellular gate. PMID:29180426

Proton movement and coupling in the POT family of peptide transporters.

PubMed

Parker, Joanne L; Li, Chenghan; Brinth, Allete; Wang, Zhi; Vogeley, Lutz; Solcan, Nicolae; Ledderboge-Vucinic, Gregory; Swanson, Jessica M J; Caffrey, Martin; Voth, Gregory A; Newstead, Simon

2017-12-12

POT transporters represent an evolutionarily well-conserved family of proton-coupled transport systems in biology. An unusual feature of the family is their ability to couple the transport of chemically diverse ligands to an inwardly directed proton electrochemical gradient. For example, in mammals, fungi, and bacteria they are predominantly peptide transporters, whereas in plants the family has diverged to recognize nitrate, plant defense compounds, and hormones. Although recent structural and biochemical studies have identified conserved sites of proton binding, the mechanism through which transport is coupled to proton movement remains enigmatic. Here we show that different POT transporters operate through distinct proton-coupled mechanisms through changes in the extracellular gate. A high-resolution crystal structure reveals the presence of ordered water molecules within the peptide binding site. Multiscale molecular dynamics simulations confirm proton transport occurs through these waters via Grotthuss shuttling and reveal that proton binding to the extracellular side of the transporter facilitates a reorientation from an inward- to outward-facing state. Together these results demonstrate that within the POT family multiple mechanisms of proton coupling have likely evolved in conjunction with variation of the extracellular gate. Copyright © 2017 the Author(s). Published by PNAS.

Dirac dispersion generates unusually large Nernst effect in Weyl semimetals

NASA Astrophysics Data System (ADS)

Watzman, Sarah J.; McCormick, Timothy M.; Shekhar, Chandra; Wu, Shu-Chun; Sun, Yan; Prakash, Arati; Felser, Claudia; Trivedi, Nandini; Heremans, Joseph P.

2018-04-01

Weyl semimetals contain linearly dispersing electronic states, offering interesting features in transport yet to be thoroughly explored thermally. Here we show how the Nernst effect, combining entropy with charge transport, gives a unique signature for the presence of Dirac bands and offers a diagnostic to determine if trivial pockets play a role in this transport. The Nernst thermopower of NbP exceeds its conventional thermopower by a 100-fold, and the temperature dependence of the Nernst effect has a pronounced maximum. The charge-neutrality condition dictates that the Fermi level shifts with increasing temperature toward the energy that has the minimum density of states (DOS). In NbP, the agreement of the Nernst and Seebeck data with a model that assumes this minimum DOS resides at the Dirac points is taken as strong experimental evidence that the trivial (non-Dirac) bands play no role in high-temperature transport.

49 CFR 19.37 - Property trust relationship.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 1 2011-10-01 2011-10-01 false Property trust relationship. 19.37 Section 19.37 Transportation Office of the Secretary of Transportation UNIFORM ADMINISTRATIVE REQUIREMENTS FOR GRANTS AND... Requirements Property Standards § 19.37 Property trust relationship. Real property, equipment, intangible...

Biochemical Regulatory Features of Activation-Induced Cytidine Deaminase Remain Conserved from Lampreys to Humans

PubMed Central

King, Justin J.; Amemiya, Chris T.; Hsu, Ellen

2017-01-01

ABSTRACT Activation-induced cytidine deaminase (AID) is a genome-mutating enzyme that initiates class switch recombination and somatic hypermutation of antibodies in jawed vertebrates. We previously described the biochemical properties of human AID and found that it is an unusual enzyme in that it exhibits binding affinities for its substrate DNA and catalytic rates several orders of magnitude higher and lower, respectively, than a typical enzyme. Recently, we solved the functional structure of AID and demonstrated that these properties are due to nonspecific DNA binding on its surface, along with a catalytic pocket that predominantly assumes a closed conformation. Here we investigated the biochemical properties of AID from a sea lamprey, nurse shark, tetraodon, and coelacanth: representative species chosen because their lineages diverged at the earliest critical junctures in evolution of adaptive immunity. We found that these earliest-diverged AID orthologs are active cytidine deaminases that exhibit unique substrate specificities and thermosensitivities. Significant amino acid sequence divergence among these AID orthologs is predicted to manifest as notable structural differences. However, despite major differences in sequence specificities, thermosensitivities, and structural features, all orthologs share the unusually high DNA binding affinities and low catalytic rates. This absolute conservation is evidence for biological significance of these unique biochemical properties. PMID:28716949

Sustaining the Light-Heavy Brigade

DTIC Science & Technology

1991-06-07

of the combined arms concept. In the twentieth century technology made a significant impact on how units were organized and fought. One of these...34Support personnel must use innovation , suspend normal procedures when necessary, take advantage of unusual sources of supply and transportation and take...designed to be broken out to individual task forces. Therefore, support planners must be innovative in developing a solution that best supports the

Unusual Carrier Thermalization in a Dilute GaAs1-xNx Alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, P. H.; Xu, Z. Y.; Luo, X. D.

2007-01-01

Photoluminescence (PL) properties of the E{sub 0}, E{sub 0} + {Delta}{sub 0}, and E{sub +} bands in an x=0.62% GaAs{sub 1-x}N{sub x} alloy were investigated in detail, including their peak position, linewidth, and line shape dependences on the excitation energy, excitation power, and temperature, using micro-PL. The hot electrons within the E{sub +} band are found to exhibit highly unusual thermalization, which results in a large blueshift in its PL peak energy by >2k{sub B}T, suggesting peculiar density of states and carrier dynamics of the E{sub +} band.

Crystal structure of the Alcanivorax borkumensis YdaH transporter reveals an unusual topology

DOE PAGES

Bolla, Jani Reddy; Su, Chih-Chia; Delmar, Jared A.; ...

2015-04-20

The potential of the folic acid biosynthesis pathway as a target for the development of antibiotics has been clinically validated. However, many pathogens have developed resistance to these antibiotics, prompting a re-evaluation of potential drug targets within the pathway. The ydaH gene of Alcanivorax borkumensis encodes an integral membrane protein of the AbgT family of transporters for which no structural information was available. Here we report the crystal structure of A. borkumensis YdaH, revealing a dimeric molecule with an architecture distinct from other families of transporters. YdaH is a bowl-shaped dimer with a solvent-filled basin extending from the cytoplasm tomore » halfway across the membrane bilayer. Each subunit of the transporter contains nine transmembrane helices and two hairpins that suggest a plausible pathway for substrate transport. Further analyses also suggest that YdaH could act as an antibiotic efflux pump and mediate bacterial resistance to sulfonamide antimetabolite drugs.« less

Origami-based cellular metamaterial with auxetic, bistable, and self-locking properties

NASA Astrophysics Data System (ADS)

Kamrava, Soroush; Mousanezhad, Davood; Ebrahimi, Hamid; Ghosh, Ranajay; Vaziri, Ashkan

2017-04-01

We present a novel cellular metamaterial constructed from Origami building blocks based on Miura-ori fold. The proposed cellular metamaterial exhibits unusual properties some of which stemming from the inherent properties of its Origami building blocks, and others manifesting due to its unique geometrical construction and architecture. These properties include foldability with two fully-folded configurations, auxeticity (i.e., negative Poisson’s ratio), bistability, and self-locking of Origami building blocks to construct load-bearing cellular metamaterials. The kinematics and force response of the cellular metamaterial during folding were studied to investigate the underlying mechanisms resulting in its unique properties using analytical modeling and experiments.

Origami-based cellular metamaterial with auxetic, bistable, and self-locking properties

PubMed Central

Kamrava, Soroush; Mousanezhad, Davood; Ebrahimi, Hamid; Ghosh, Ranajay; Vaziri, Ashkan

2017-01-01

We present a novel cellular metamaterial constructed from Origami building blocks based on Miura-ori fold. The proposed cellular metamaterial exhibits unusual properties some of which stemming from the inherent properties of its Origami building blocks, and others manifesting due to its unique geometrical construction and architecture. These properties include foldability with two fully-folded configurations, auxeticity (i.e., negative Poisson’s ratio), bistability, and self-locking of Origami building blocks to construct load-bearing cellular metamaterials. The kinematics and force response of the cellular metamaterial during folding were studied to investigate the underlying mechanisms resulting in its unique properties using analytical modeling and experiments. PMID:28387345

Computational approaches for deciphering the equilibrium and kinetic properties of iron transport proteins.

PubMed

Abdizadeh, H; Atilgan, A R; Atilgan, C; Dedeoglu, B

2017-11-15

With the advances in three-dimensional structure determination techniques, high quality structures of the iron transport proteins transferrin and the bacterial ferric binding protein (FbpA) have been deposited in the past decade. These are proteins of relatively large size, and developments in hardware and software have only recently made it possible to study their dynamics using standard computational resources. We review computational techniques towards understanding the equilibrium and kinetic properties of iron transport proteins under different environmental conditions. At the level of detail that requires quantum chemical treatments, the octahedral geometry around iron has been scrutinized and it has been established that the iron coordinating tyrosines are in an unusual deprotonated state. At the atomistic level, both the N-lobe and the full bilobal structure of transferrin have been studied under varying conditions of pH, ionic strength and binding of other metal ions by molecular dynamics (MD) simulations. These studies have allowed questions to be answered, among others, on the function of second shell residues in iron release, the role of synergistic anions in preparing the active site for iron binding, and the differences between the kinetics of the N- and the C-lobe. MD simulations on FbpA have led to the detailed observation of the binding kinetics of phosphate to the apo form, and to the conformational preferences of the holo form under conditions mimicking the environmental niches provided by the periplasmic space. To study the dynamics of these proteins with their receptors, one must resort to coarse-grained methodologies, since these systems are prohibitively large for atomistic simulations. A study of the complex of human transferrin (hTf) with its pathogenic receptor by such methods has revealed a potential mechanistic explanation for the defense mechanism that arises in evolutionary warfare. Meanwhile, the motions in the transferrin receptor bound hTf have been shown to disfavor apo hTf dissociation, explaining why the two proteins remain in complex during the recycling process from the endosome to the cell surface. Open problems and possible technological applications related to metal ion binding-release in iron transport proteins that may be handled by hybrid use of quantum mechanical, MD and coarse-grained approaches are discussed.

Shape memory alloys: Properties and biomedical applications

NASA Astrophysics Data System (ADS)

Mantovani, Diego

2000-10-01

Shape memory alloys provide new insights for the design of biomaterials in bioengineering for the design of artificial organs and advanced surgical instruments, since they have specific characteristics and unusual properties. This article will examine (a) the four properties of shape memory alloys, (b) medical applications with high potential for improving the present and future quality of life, and (c) concerns regarding the biocom-patibility properties of nickel-titanium alloys. In particular, the long-term challenges of using shape memory alloys will be discussed, regarding corrosion and potential leakage of elements and ions that could be toxic to cells, tissues and organs.

Three dimensional Origami-based metamaterial

NASA Astrophysics Data System (ADS)

Kamrava, Soroush; Mousanezhad, Davood; Ebrahimi, Hamid; Ghosh, Ranajay; Vaziri, Ashkan; High Performance Materials; Structures Labratory Team

We present a novel cellular metamaterial constructed from Origami building blocks based on Miura-ori fold. The proposed cellular metamaterial exhibits unusual properties some of which stemming from the inherent properties of its Origami building blocks, and others manifesting due to its unique geometrical construction and architecture. These properties include foldability with two fully-folded configurations, auxeticity (i.e., negative Poisson's ratio), bistability, and self-locking of Origami building blocks to construct load-bearing cellular metamaterials. The kinematics and force response of the cellular metamaterial during folding were studied to investigate the underlying mechanisms resulting in its unique properties using analytical modeling and experiments.

Reverse Genetic Analysis of Ourmiaviruses Reveals the Nucleolar Localization of the Coat Protein in Nicotiana benthamiana and Unusual Requirements for Virion Formation ▿ † ‡

PubMed Central

Crivelli, Giulia; Ciuffo, Marina; Genre, Andrea; Masenga, Vera; Turina, Massimo

2011-01-01

Ourmia melon virus (OuMV) is the type member of the genus Ourmiavirus. These viruses have a trisegmented genome, each part of which encodes a single protein. Ourmiaviruses share a distant similarity with other plant viruses only in their movement proteins (MP), whereas their RNA-dependent RNA polymerase (RdRP) shares features only with fungal viruses of the family Narnaviridae. Thus, ourmiaviruses are in a unique phylogenetic position among existing plant viruses. Here, we developed an agroinoculation system to launch infection in Nicotiana benthamiana plants. Using different combinations of the three segments, we demonstrated that RNA1 is necessary and sufficient for cis-acting replication in the agroinfiltrated area. RNA2 and RNA3, encoding the putative movement protein and the coat protein (CP), respectively, are both necessary for successful systemic infection of N. benthamiana. The CP is dispensable for long-distance transport of the virus through vascular tissues, but its absence prevents efficient systemic infection at the exit sites. Virion formation occurred only when the CP was translated from replication-derived RNA3. Transient expression of a green fluorescent protein-MP (GFP-MP) fusion via agroinfiltration showed that the MP is present in cytoplasmic connections across plant cell walls; in protoplasts the GFP-MP fusion stimulates the formation of tubular protrusions. Expression through agroinfiltration of a GFP-CP fusion displays most of the fluorescence inside the nucleus and within the nucleolus in particular. Nuclear localization of the CP was also confirmed through Western blot analysis of purified nuclei. The significance of several unusual properties of OuMV for replication, virion assembly, and movement is discussed in relation to other positive-strand RNA viruses. PMID:21411534

Beryllium in the environment: a review.

PubMed

Taylor, Tammy P; Ding, Mei; Ehler, Deborah S; Foreman, Trudi M; Kaszuba, John P; Sauer, Nancy N

2003-02-01

Beryllium is an important industrial metal because of its unusual material properties: it is lighter than aluminum and six times stronger than steel. Often alloyed with other metals such as copper, beryllium is a key component of materials used in the aerospace and electronics industries. Beryllium has a small neutron cross-section, which makes it useful in the production of nuclear weapons and in sealed neutron sources. Unfortunately, beryllium is one of the most toxic elements in the periodic table. It is responsible for the often-fatal lung disease, Chronic Beryllium Disease (CBD) or berylliosis, and is listed as a Class A EPA carcinogen. Coal-fired power plants, industrial manufacturing and nuclear weapons production and disposal operations have released beryllium to the environment. This contamination has the potential to expose workers and the public to beryllium. Despite the increasing use of beryllium in industry, there is surprisingly little published information about beryllium fate and transport in the environment. This information is crucial for the development of strategies that limit worker and public exposure. This review summarizes the current understanding of beryllium health hazards, current regulatory mandates, environmental chemistry, geochemistry and environmental contamination.

Trade-Offs in Thin Film Solar Cells with Layered Chalcostibite Photovoltaic Absorbers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Welch, Adam W.; Baranowski, Lauryn L.; Peng, Haowei

Discovery of novel semiconducting materials is needed for solar energy conversion and other optoelectronic applications. However, emerging low-dimensional solar absorbers often have unconventional crystal structures and unusual combinations of optical absorption and electrical transport properties, which considerably slows down the research and development progress. Here, the effect of stronger absorption and weaker carrier collection of 2D-like absorber materials are studied using a high-throughput combinatorial experimental approach, complemented by advanced characterization and computations. It is found that the photoexcited charge carrier collection in CuSbSe 2 solar cells is enhanced by drift in an electric field, addressing a different absorption/collection balance. Themore » resulting drift solar cells efficiency is <5% due to inherent J SC/ V OC trade-off, suggesting that improved carrier diffusion and better contacts are needed to further increase the CuSbSe 2 performance. Furthermore, this study also illustrates the advantages of high-throughput experimental methods for fast optimization of the optoelectronic devices based on emerging low-dimensional semiconductor materials.« less

Trade-Offs in Thin Film Solar Cells with Layered Chalcostibite Photovoltaic Absorbers

DOE PAGES

Welch, Adam W.; Baranowski, Lauryn L.; Peng, Haowei; ...

2017-01-25

Discovery of novel semiconducting materials is needed for solar energy conversion and other optoelectronic applications. However, emerging low-dimensional solar absorbers often have unconventional crystal structures and unusual combinations of optical absorption and electrical transport properties, which considerably slows down the research and development progress. Here, the effect of stronger absorption and weaker carrier collection of 2D-like absorber materials are studied using a high-throughput combinatorial experimental approach, complemented by advanced characterization and computations. It is found that the photoexcited charge carrier collection in CuSbSe 2 solar cells is enhanced by drift in an electric field, addressing a different absorption/collection balance. Themore » resulting drift solar cells efficiency is <5% due to inherent J SC/ V OC trade-off, suggesting that improved carrier diffusion and better contacts are needed to further increase the CuSbSe 2 performance. Furthermore, this study also illustrates the advantages of high-throughput experimental methods for fast optimization of the optoelectronic devices based on emerging low-dimensional semiconductor materials.« less

Metamagnetism, sign reversal and low temperature magnetocaloric effect in single-crystalline EuV2Al20

NASA Astrophysics Data System (ADS)

Ramesh Kumar, K.; Nair, Harikrishnan S.; Bhattacharyya, A.; Thamizhavel, A.; Strydom, André M.

2018-04-01

The Frank-Kasper cage compound EuV2Al20 crystallizes in the cubic structure with Fd 3 ‾ m space group and exhibits unusual magnetic and transport properties. The system undergoes an antiferromagnetic transition below 5.6 K wherein the Eu2+ moments are aligned anti-parallel along 〈1 1 1〉 direction and the system exhibits a weak metamagetic transition at the field of 1 T. Arrott plots (M2 vs H / M) show a "S" shaped variation in the low fields below TN and the plausible reason for the occurrence of negative slope is discussed. Isothermal magnetic entropy change is estimated from both magnetization and heat capacity measurements invoking the Maxwell's thermodynamic relations. Temperature variation of ΔSm showed a weak negative minimum and a sign reversal at the field value of 1 T due to field induced metamagnetic transition. Universal master curve is constructed by rescaling the ΔSm vs T curves in the context of analysing the nature of the magnetic transition.

Field-Driven Quantum Criticality in the Spinel Magnet ZnCr2 Se4

NASA Astrophysics Data System (ADS)

Gu, C. C.; Zhao, Z. Y.; Chen, X. L.; Lee, M.; Choi, E. S.; Han, Y. Y.; Ling, L. S.; Pi, L.; Zhang, Y. H.; Chen, G.; Yang, Z. R.; Zhou, H. D.; Sun, X. F.

2018-04-01

We report detailed dc and ac magnetic susceptibilities, specific heat, and thermal conductivity measurements on the frustrated magnet ZnCr2 Se4 . At low temperatures, with an increasing magnetic field, this spinel material goes through a series of spin state transitions from the helix spin state to the spiral spin state and then to the fully polarized state. Our results indicate a direct quantum phase transition from the spiral spin state to the fully polarized state. As the system approaches the quantum criticality, we find strong quantum fluctuations of the spins with behaviors such as an unconventional T2 -dependent specific heat and temperature-independent mean free path for the thermal transport. We complete the full phase diagram of ZnCr2 Se4 under the external magnetic field and propose the possibility of frustrated quantum criticality with extended densities of critical modes to account for the unusual low-energy excitations in the vicinity of the criticality. Our results reveal that ZnCr2 Se4 is a rare example of a 3D magnet exhibiting a field-driven quantum criticality with unconventional properties.

Electron tunneling characteristics of a cubic quantum dot, (PbS){sub 32}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Sanjeev K., E-mail: sanjeevg@mtu.edu, E-mail: haiying.he@valpo.edu; Banyai, Douglas; Pandey, Ravindra

The electron transport properties of the cubic quantum dot, (PbS){sub 32}, are investigated. The stability of the quantum dot has been established by recent scanning tunneling microscope experiments [B. Kiran, A. K. Kandalam, R. Rallabandi, P. Koirala, X. Li, X. Tang, Y. Wang, H. Fairbrother, G. Gantefoer, and K. Bowen, J. Chem. Phys. 136(2), 024317 (2012)]. In spite of the noticeable energy band gap (∼2 eV), a relatively high tunneling current for (PbS){sub 32} is predicted affirming the observed bright images for (PbS){sub 32}. The calculated I-V characteristics of (PbS){sub 32} are predicted to be substrate-dependent; (PbS){sub 32} on themore » Au (001) exhibits the molecular diode-like behavior and the unusual negative differential resistance effect, though this is not the case with (PbS){sub 32} on the Au (110). Appearance of the conduction channels associated with the hybridized states of quantum dot and substrate together with their asymmetric distribution at the Fermi level seem to determine the tunneling characteristics of the system.« less

Eco-Friendly Magnetic Iron Oxide Pillared Montmorillonite for Advanced Catalytic Degradation of Dichlorophenol

EPA Science Inventory

Eco-friendly pillared montmorillonites, in which the pillars consist of iron oxide are expected to have interesting and unusual magnetic properties that are applicable for environmental decontamination. Completely “green” and effective composite was synthesized using mild reactio...

Thermochromic platinum complexes

DOEpatents

Kostic, Nenad M.; Zhou, Xia-Ying

1990-05-29

Thermochromic compounds containing the [Pt(dipic)Cl].sup.- anion. These compounds are yellow and monomeric at high temperatures or in low concentrations and abruptly change to red and polymeric at low temperatures or higher solution concentrations. This unusual property allows them to be used as temperature sensors.

Thermochromic platinum complexes

DOEpatents

Kostic, Nenad M.; Zhou, Xia-Ying

1989-08-15

Thermochromic compounds containing the [Pt(dipic)Cl].sup.- anion. These compounds are yellow and monomeric at high temperatures or in low concentrations and abruptly change to red and polymeric at low temperatures or higher solution concentrations. This unusual property allows them to be used as temperature sensors.

48 CFR 245.7302-5 - Mailing lists.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Mailing lists. (a) The plant clearance officer will ensure the contractor solicits a sufficient number of bidders to obtain adequate competition. (b) When large quantities of property, special commodities, or unusual geographic locations are involved, the plant clearance officer is encouraged to obtain additional...

An analysis of high fine aerosol loading episodes in north-central Spain in the summer 2013 - Impact of Canadian biomass burning episode and local emissions

NASA Astrophysics Data System (ADS)

Burgos, M. A.; Mateos, D.; Cachorro, V. E.; Toledano, C.; de Frutos, A. M.; Calle, A.; Herguedas, A.; Marcos, J. L.

2018-07-01

This work presents an evaluation of a surprising and unusual high turbidity summer period in 2013 recorded in the north-central Iberian Peninsula (IP). The study is made up of three main pollution episodes characterized by very high aerosol optical depth (AOD) values with the presence of fine aerosol particles: the strongest long-range transport Canadian Biomass Burning (BB) event recorded, one of the longest-lasting European Anthropogenic (A) episodes and an extremely strong regional BB. The Canadian BB episode was unusually strong with maximum values of AOD(440 nm) ∼ 0.8, giving rise to the highest value recorded by photometer data in the IP with a clearly established Canadian origin. The anthropogenic pollution episode originated in Europe is mainly a consequence of the strong impact of Canadian BB events over north-central Europe. As regards the local episode, a forest fire in the nature reserve near the Duero River (north-central IP) impacted on the population over 200 km away from its source. These three episodes exhibited fingerprints in different aerosol columnar properties retrieved by sun-photometers of the AErosol RObotic NETwork (AERONET) as well as in particle mass surface concentrations, PMx, measured by the European Monitoring and Evaluation Programme (EMEP). Main statistics, time series and scatterplots relate aerosol loads (aerosol optical depth, AOD and particulate matter, PM) with aerosol size quantities (Ångström Exponent and PM ratio). More detailed microphysical/optical properties retrieved by AERONET inversion products are analysed in depth to describe these events: contribution of fine and coarse particles to AOD and its ratio (the fine mode fraction), volume particle size distribution, fine volume fraction, effective radius, sphericity fraction, single scattering albedo and absorption optical depth. Due to its relevance in climate studies, the aerosol radiative effect has been quantified for the top and bottom of the atmosphere, obtaining mean daily values for this extraordinary summer period of -14.5 and -47.5 Wm-2, respectively.

Metal-insulator transitions

NASA Astrophysics Data System (ADS)

Imada, Masatoshi; Fujimori, Atsushi; Tokura, Yoshinori

1998-10-01

Metal-insulator transitions are accompanied by huge resistivity changes, even over tens of orders of magnitude, and are widely observed in condensed-matter systems. This article presents the observations and current understanding of the metal-insulator transition with a pedagogical introduction to the subject. Especially important are the transitions driven by correlation effects associated with the electron-electron interaction. The insulating phase caused by the correlation effects is categorized as the Mott Insulator. Near the transition point the metallic state shows fluctuations and orderings in the spin, charge, and orbital degrees of freedom. The properties of these metals are frequently quite different from those of ordinary metals, as measured by transport, optical, and magnetic probes. The review first describes theoretical approaches to the unusual metallic states and to the metal-insulator transition. The Fermi-liquid theory treats the correlations that can be adiabatically connected with the noninteracting picture. Strong-coupling models that do not require Fermi-liquid behavior have also been developed. Much work has also been done on the scaling theory of the transition. A central issue for this review is the evaluation of these approaches in simple theoretical systems such as the Hubbard model and t-J models. Another key issue is strong competition among various orderings as in the interplay of spin and orbital fluctuations. Experimentally, the unusual properties of the metallic state near the insulating transition have been most extensively studied in d-electron systems. In particular, there is revived interest in transition-metal oxides, motivated by the epoch-making findings of high-temperature superconductivity in cuprates and colossal magnetoresistance in manganites. The article reviews the rich phenomena of anomalous metallicity, taking as examples Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Ru compounds. The diverse phenomena include strong spin and orbital fluctuations, mass renormalization effects, incoherence of charge dynamics, and phase transitions under control of key parameters such as band filling, bandwidth, and dimensionality. These parameters are experimentally varied by doping, pressure, chemical composition, and magnetic fields. Much of the observed behavior can be described by the current theory. Open questions and future problems are also extracted from comparison between experimental results and theoretical achievements.

Climate, not conflict, explains extreme Middle East dust storm

DOE PAGES

Parolari, Anthony J.; Li, Dan; Bou-Zeid, Elie; ...

2016-11-08

The recent dust storm in the Middle East (Sepember 2015) was publicized in the media as a sign of an impending 'Dust Bowl.' Its severity, demonstrated by extreme aerosol optical depth in the atmosphere in the 99th percentile compared to historical data, was attributed to the ongoing regional conflict. However, surface meteorological and remote sensing data, as well as regional climate model simulations, support an alternative hypothesis: the historically unprecedented aridity played a more prominent role, as evidenced by unusual climatic and meteorological conditions prior to and during the storm. Remotely sensed normalized difference vegetation index demonstrates that vegetation covermore » was high in 2015 relative to the prior drought and conflict periods, suggesting that agricultural activity was not diminished during that year, thus negating the media narrative. Instead, meteorological simulations using the Weather Research and Forecasting (WRF) model show that the storm was associated with a cyclone and 'Shamal' winds, typical for dust storm generation in this region, that were immediately followed by an unusual wind reversal at low levels that spread dust west to the Mediterranean Coast. These unusual meteorological conditions were aided by a significant reduction in the critical shear stress due to extreme dry and hot conditions, thereby enhancing dust availability for erosion during this storm. Concluding, unusual aridity, combined with unique synoptic weather patterns, enhanced dust emission and westward long-range transport across the region, thus generating the extreme storm.« less

Climate, not conflict, explains extreme Middle East dust storm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parolari, Anthony J.; Li, Dan; Bou-Zeid, Elie

The recent dust storm in the Middle East (Sepember 2015) was publicized in the media as a sign of an impending 'Dust Bowl.' Its severity, demonstrated by extreme aerosol optical depth in the atmosphere in the 99th percentile compared to historical data, was attributed to the ongoing regional conflict. However, surface meteorological and remote sensing data, as well as regional climate model simulations, support an alternative hypothesis: the historically unprecedented aridity played a more prominent role, as evidenced by unusual climatic and meteorological conditions prior to and during the storm. Remotely sensed normalized difference vegetation index demonstrates that vegetation covermore » was high in 2015 relative to the prior drought and conflict periods, suggesting that agricultural activity was not diminished during that year, thus negating the media narrative. Instead, meteorological simulations using the Weather Research and Forecasting (WRF) model show that the storm was associated with a cyclone and 'Shamal' winds, typical for dust storm generation in this region, that were immediately followed by an unusual wind reversal at low levels that spread dust west to the Mediterranean Coast. These unusual meteorological conditions were aided by a significant reduction in the critical shear stress due to extreme dry and hot conditions, thereby enhancing dust availability for erosion during this storm. Concluding, unusual aridity, combined with unique synoptic weather patterns, enhanced dust emission and westward long-range transport across the region, thus generating the extreme storm.« less

An anomalous African dust event and its impact on aerosol radiative forcing on the Southwest Atlantic coast of Europe in February 2016.

PubMed

Sorribas, M; Adame, J A; Andrews, E; Yela, M

2017-04-01

A desert dust (DD) event that had its origin in North Africa occurred on the 20th-23rd of February 2016. The dust transport phenomenon was exceptional because of its unusual intensity during the coldest season. A historical dataset (2006-2015) of February meteorological scenarios using ECMWF fields, meteorological parameters, aerosol optical properties, surface O 3 and AOD retrieved from MODIS at the El Arenosillo observatory (southwestern Spain) were analysed and compared with the levels during the DD event to highlight its exceptionality. Associated with a low-pressure system in western North Africa, flows transported air from the Sahel to Algeria and consequently increased temperatures from the surface to 700hPa by up to 7-9°C relative to the last decade. These conditions favoured the formation of a Saharan air layer. Dust was transported to the north and reached the Western Mediterranean Basin and the Iberian Peninsula. The arrival of the DD event at El Arenosillo did not affect the surface weather conditions or ozone but did impact the aerosol radiative forcing at the top of atmosphere (RF TOA ). Aerosol radiative properties did not change relative to historical; however, the particle size and the amount of the aerosol were significantly higher. The DD event caused an increase (in absolute terms) of the mean aerosol RF TOA to a value of -8.1Wm -2 (long-term climatological value ~-1.5Wm -2 ). The aerosol RF TOA was not very large relative other DD episodes; however, our analysis of the historical data concluded that the importance of this DD event lay in the month of occurrence. European phenological datasets related to extreme atmospheric events predominantly reflect changes that are probably associated with climate change. This work is an example of this phenomenon, showing an event that occurred in a hotspot, the Saharan desert, and its impact two thousand km away. Copyright © 2017 Elsevier B.V. All rights reserved.

Facile synthesis of gold nanomaterials with unusual crystal structures.

PubMed

Fan, Zhanxi; Huang, Xiao; Chen, Ye; Huang, Wei; Zhang, Hua

2017-11-01

Gold (Au) nanomaterials have attracted wide research attention, owing to their high chemical stability, promising catalytic properties, excellent biocompatibility, unique electronic structure and outstanding localized surface plasmon resonance (LSPR) absorption properties; all of which are closely related to their size and shape. Recently, crystal-phase-controlled synthesis of noble metal nanomaterials has emerged as a promising strategy to tune their physicochemical properties. This protocol describes the detailed experimental procedures for the crystal-phase-controlled syntheses of Au nanomaterials with unusual crystal structures under mild conditions. Briefly, pure hexagonal close-packed (hcp) Au square sheets (AuSSs) with a thickness of ∼2.4 nm are synthesized using a graphene-oxide-assisted method in which HAuCl 4 is reduced by oleylamine in a mixture of hexane and ethanol. By using pure hexane as the solvent, well-dispersed ultrathin hcp/face-centered cubic (fcc) Au nanowires with a diameter of ∼1.6 nm on graphene oxide can be obtained. Meanwhile, hcp/fcc Au square-like plates with a side length of 200-400 nm are prepared via the secondary growth of Au on the hcp AuSSs. Remarkably, hexagonal (4H) Au nanoribbons with a thickness of 2.0-6.0 nm can be synthesized with a one-pot colloidal method in which HAuCl 4 is reduced by oleylamine in a mixed solvent of hexane and 1,2-dichloropropane. It takes 17-37 h for the synthesis of these Au nanomaterials with unusual crystal structures. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) are used to characterize the resultant Au nanomaterials, which could have many promising applications, such as biosensing, near-IR photothermal therapy, catalysis and surface-enhanced Raman scattering (SERS).

Effects of nanoscale aggregation on mechanical properties and local dynamics of precise acid- and ion-containing polymers

NASA Astrophysics Data System (ADS)

Middleton, Luri Robert

Acid- and ion-containing polymers have interchain interactions that alter polymer behavior at the nano, micro, and bulk length scales. Strong secondary-bonds act as thermo-reversible physical crosslinks between chains which drive self-assembly. Tuning theses interactions can modify bulk polymer properties including stiffness, toughness, melt viscosity, resilience, clarity, abrasion resistance and puncture resistance. Furthermore, understanding and improving the relevant factors that control transport properties would have vast implications on developing solid polymer electrolytes (SPEs) for technologically important applications including water desalination, ion exchange membranes and microelectronics. This thesis explores the structure - processing - morphology - property relationships of acid and ionic functionalized polymers. Improvements in synthetic techniques and advancements in characterization methods have enabled new studies of associating polymer systems. Synthesis of entangled, high molecular weight, linear polyethylene (PE) chains functionalized with interacting pendant groups (acidic or ionic) placed periodically along the polymer backbone represent a new class of associating polymers. These polymers with periodic distributions of acid groups are much more homogenous than the commercially available polymers. Previous studies of these polymers with greater structural homogeneity revealed great variety in morphologies of the nano-aggregated polar groups within the non-polar polymer matrix. This thesis correlated the morphologies with bulk properties through real-time X-ray scattering and tensile deformation at a range of temperatures and sample compositions. New, transient morphologies and hierarchical morphologies were observed which coincided with unusual tensile strain hardening. These results indicate that improvements in synthetic control of polymers can enhance physical properties such as tensile strain-hardening, through cooperative bonding between chains. The structural regularity of precise polyethylenes also enables robust comparisons between experiments and computer simulations. At pico- to nano-seconds time scales and length scales of polymer and aggregate dynamics, neutron scattering and molecular dynamics simulations were combined to extend the knowledge of the molecular-level aggregated polymer dynamics. These experiments provide a baseline for future studies of ion-conduction in associating polymer melts.

Masses, Radii, and Cloud Properties of the HR 8799 Planets

NASA Technical Reports Server (NTRS)

Marley, Mark S.; Saumon, Didier; Cushing, Michael; Ackerman, Andrew S.; Fortney, Jonathan J.; Freedman, Richard

2012-01-01

The near-infrared colors of the planets directly imaged around the A star HR 8799 are much redder than most field brown dwarfs of the same effective temperature. Previous theoretical studies of these objects have compared the photometric and limited spectral data of the planets to the predictions of various atmosphere and evolution models and concluded that the atmospheres of planets b, c, and d are unusually cloudy or have unusual cloud properties. Most studies have also found that the inferred radii of some or all of the planets disagree with expectations of standard giant planet evolution models. Here we compare the available data to the predictions of our own set of atmospheric and evolution models that have been extensively tested against field L and T dwarfs, including the reddest L dwarfs. Unlike almost all previous studies we specify mutually self-consistent choices for effective temperature, gravity, cloud properties, and planetary radius. This procedure yields plausible and self-consistent values for the masses, effective temperatures, and cloud properties of all three planets. We find that the cloud properties of the HR 8799 planets are in fact not unusual but rather follow previously recognized trends including a gravity dependence on the temperature of the L to T spectral transition, some reasons for which we discuss. We find that the inferred mass of planet b is highly sensitive to the H and K band spectrum. Solutions for planets c and particularly d are less certain but are consistent with the generally accepted constraints on the age of the primary star and orbital dynamics. We also confirm that as for L and T dwarfs and solar system giant planets, non-equilibrium chemistry driven by atmospheric mixing is also important for these objects. Given the preponderance of data suggesting that the L to T spectral type transition is gravity dependent, we present a new evolution calculation that predicts cooling tracks on the near-infrared color-magnitude diagram. Finally we argue that the range of uncertainty conventionally quoted for the bolometric luminosity of all three planets is too small.

Ambient Stable Radical Cations, Diradicaloid π-Dimeric Dications, Closed-Shell Dications, and Diradical Dications of Methylthio-Capped Rylenes.

PubMed

Qi, Qingbiao; Burrezo, Paula Mayorga; Phan, Hoa; Herng, Tun Seng; Gopalakrishna, Tullimilli Y; Zeng, Wangdong; Ding, Jun; Casado, Juan; Wu, Jishan

2017-06-01

Radical cations and dications of π-conjugated systems play vital roles in organic electronic devices, organic conductors, and conducting polymers. Their structures, charge and spin distribution, and mechanism of charge transport are of great interest. In this article, radical cations and dications of a series of newly synthesized methylthio-capped rylenes were synthesized and isolated. Their ground-state structures, physical properties, and solid-state packing were systematically investigated by various experimental methods, such as X-ray crystallographic analysis, UV/Vis/NIR absorption spectroscopy, (spectro-)electrochemistry, nuclear magnetic resonance spectroscopy, electron spin resonance spectroscopy, superconducting quantum interference device, and Raman spectroscopy, assisted by DFT calculations. It was found that all the charged species show an exceptional stability under ambient air and light conditions due to the efficient spin and charge delocalization over the whole rylene backbone. The dication of hexarylene turned out to have an unusual open-shell singlet rather than closed-shell ground state, thus it can be described as a diradical dication. Dimerization was observed for the radical cations and even the dications in crystals due to the strong intermolecular antiferromagnetic spin-spin interaction and π-π interaction, which result in unique magnetic properties. Such intermolecular association was also observed in solution. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Measurements of Charging of Apollo 17 Lunar Dust Grains by Electron Impact

NASA Technical Reports Server (NTRS)

Abbas, Mian M.; Tankosic, Dragana; Spann, James F.; Dube, Michael J.

2008-01-01

It is well known since the Apollo missions that the lunar surface is covered with a thick layer of micron size dust grains with unusually high adhesive characteristics. The dust grains observed to be levitated and transported on the lunar surface are believed to have a hazardous impact on the robotic and human missions to the Moon. The observed dust phenomena are attributed to the lunar dust being charged positively during the day by UV photoelectric emissions, and negatively during the night by the solar wind electrons. The current dust charging and the levitation models, however, do not fully explain the observed phenomena, with the uncertainty of dust charging processes and the equilibrium potentials of the individual dust grains. It is well recognized that the charging properties of individual dust grains are substantially different from those determined from measurements made on bulk materials that are currently available. An experimental facility has been developed in the Dusty Plasma Laboratory at MSFC for investigating the charging and optical properties of individual micron/sub-micron size positively or negatively charged dust grains by levitating them in an electrodynamic balance in simulated space environments. In this paper, we present the laboratory measurements on charging of Apollo 17 individual lunar dust grains by a low energy electron beam. The charging rates and the equilibrium potentials produced by direct electron impact and by secondary electron emission process are discussed.

Fullerene materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malhotra, R.; Ruoff, R.S.; Lorents, D.C.

1995-04-01

Fullerenes are all-carbon cage molecules. The most celebrated fullerene is the soccer-ball shaped C{sub 60}, which is composed of twenty hexagons and twelve pentagons. Because its structure is reminiscent of the geodesic domes of architect R. Buckminster Fuller, C{sub 60} is called buckminsterfullerene, and all the materials in the family are designated fullerenes. Huffman and Kraetschmer`s discovery unleashed activity around the world as scientists explored production methods, properties, and potential uses of fullerenes. Within a short period, methods for their production in electric arcs, plasmas, and flames were discovered, and several companies began selling fullerenes to the research market. Whatmore » is remarkable is that in all these methods, carbon atoms assemble themselves into cage structures. The capability for self-assembly points to some inherent stability of these structures that allows their formation. The unusual structure naturally leads to unusual properties. Among them are ready solubility in solvents and a relatively high vapor pressure for a pure carbon material. The young fullerene field has already produced a surprising array of structures for the development of carbon-base materials having completely new and different properties from any that were previously possible.« less

41 CFR 102-118.10 - What is a transportation audit?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What is a transportation audit? 102-118.10 Section 102-118.10 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION...

41 CFR 102-118.15 - What is a transportation payment?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What is a transportation payment? 102-118.15 Section 102-118.15 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION...

New Gold Nanostructures for Sensor Applications: A Review

PubMed Central

Zhang, Yuanchao; Chu, Wendy; Foroushani, Alireza Dibaji; Wang, Hongbin; Li, Da; Liu, Jingquan; Barrow, Colin J.; Wang, Xin; Yang, Wenrong

2014-01-01

Gold based structures such as nanoparticles (NPs) and nanowires (NWs) have widely been used as building blocks for sensing devices in chemistry and biochemistry fields because of their unusual optical, electrical and mechanical properties. This article gives a detailed review of the new properties and fabrication methods for gold nanostructures, especially gold nanowires (GNWs), and recent developments for their use in optical and electrochemical sensing tools, such as surface enhanced Raman spectroscopy (SERS). PMID:28788124

EDITORIAL: Carbon-based nanoscience and nanotechnology: where are we, where are we heading? Carbon-based nanoscience and nanotechnology: where are we, where are we heading?

NASA Astrophysics Data System (ADS)

Soukiassian, Patrick G.; Ramachandra Rao, M. S.

2010-09-01

'Without carbon, life cannot exist', the saying goes, and not only life. For technological development, carbon was the ultimate material of the 19th century. It allowed the beginnings of the industrial revolution, enabling the rise of the steel and chemical industries, it made the railways run, and it played a major role in the development of naval transportation. Silicon, another very interesting material which makes up a quarter of the earth's crust, became the material of the 20th century in its turn. It gave us the development of high performance electronics and photovoltaics with large fields of applications and played a pivotal role in the evolution of computer technology. The increased device performance of information and data processing systems is changing our lives on a daily basis, producing scientific innovations for a new industrial era. However, success breeds its own problems, and there is ever more data to be handled—which requires a nanoscience approach. This cluster aims to address various aspects, prospects and challenges in this area of great interest for all our futures. Carbon exists in various allotropic forms that are intensively investigated for their unusual and fascinating properties, from both fundamental and applied points of view. Among them, the sp2 (fullerenes, nanotubes and graphene) and sp3 (diamond) bonding configurations are of special interest since they have outstanding and, in some cases, unsurpassed properties compared to other materials. These properties include very high mechanical resistance, very high hardness, high resistance to radiation damage, high thermal conductivity, biocompatibility and superconductivity. Graphene, for example, possesses very uncommon electronic structure and a high carrier mobility, with charge carriers of zero mass moving at constant velocity, just like photons. All these characteristics have put carbon and carbon-related nanomaterials in the spotlight of science and technology research. The main challenges for future understanding include i) material growth, ii) fundamental properties, and iii) developing advanced applications. The reviews in this Cluster Issue of Journal of Physics D: Applied Physics cover carbon nanoparticles and nanotubes, graphene, nano-diamond and films. They address the most current aspects and issues related to their fundamental and outstanding properties, and describe various classes of high-tech applications based on these promising materials. Future prospects, difficulties and challenges are addressed. Important issues include growth, morphology, atomic and electronic structure, transport properties, superconductivity, doping, nanochemistry using hydrogen, chemical and bio-sensors, and bio-imaging, allowing readers to evaluate this very interesting topic and draw perspectives for the future.

Technology-Enhanced Discovery

ERIC Educational Resources Information Center

Harrow, Chris; Chin, Lillian

2014-01-01

Exploration, innovation, proof: For students, teachers, and others who are curious, keeping an open mind and being ready to investigate unusual or unexpected properties will always lead to learning something new. Technology can further this process, allowing various behaviors to be analyzed that were previously memorized or poorly understood. This…

Rise and Persistence of Global M1T1 Clone of Streptococcus pyogenes

PubMed Central

Kotb, Malak

2008-01-01

The resurgence of severe invasive group A streptococcal infections in the 1980s is a typical example of the reemergence of an infectious disease. We found that this resurgence is a consequence of the diversification of particular strains of the bacteria. Among these strains is a highly virulent subclone of serotype M1T1 that has exhibited unusual epidemiologic features and virulence, unlike all other streptococcal strains. This clonal strain, commonly isolated from both noninvasive and invasive infection cases, is most frequently associated with severe invasive diseases. Because of its unusual prevalence, global spread, and increased virulence, we investigated the unique features that likely confer its unusual properties. In doing so, we found that the increased virulence of this clonal strain can be attributed to its diversification through phage mobilization and its ability to sense and adapt to different host environments; accordingly, the fittest members of this diverse bacterial community are selected to survive and invade host tissue. PMID:18826812

49 CFR 805.735-9 - Use of Government property.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 7 2011-10-01 2011-10-01 false Use of Government property. 805.735-9 Section 805.735-9 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL TRANSPORTATION SAFETY BOARD EMPLOYEE RESPONSIBILITIES AND CONDUCT § 805.735-9 Use of Government property. Members and...

Knowledge and understanding of dissolved solids in the Rio Grande–San Acacia, New Mexico, to Fort Quitman, Texas, and plan for future studies and monitoring

USGS Publications Warehouse

Moyer, Douglas; Anderholm, Scott K.; Hogan, James F.; Phillips, Fred M.; Hibbs, Barry J.; Witcher, James C.; Matherne, Anne Marie; Falk, Sarah E.

2013-01-01

-Focused Hydrogeology Studies at Inflow Sources: Map dissolved-solids concentrations in the Rio Grande and underlying alluvial aquifer; perform hydrogeologic characterization of subsurface areas containing unusually high concentrations of dissolved solids. -Modeling of Dissolved Solids: Develop models to simulate the transport and storage of dissolved solids in both surface-water and groundwater systems.

Biaxial tensile strain tuned up-and-down behavior on lattice thermal conductivity in β-AsP monolayer

NASA Astrophysics Data System (ADS)

Guo, San-Dong; Dong, Jun

2018-07-01

Various two-dimensional (2D) materials with a graphene-like buckled structure have emerged, and the β-phase AsP monolayer has been recently proposed to be thermodynamically stable from first-principles calculations. The studies of thermal transport are very useful for these 2D materials-based nano-electronics devices. Motivated by this, a comparative study of strain-dependent phonon transport of AsP monolayers is performed by solving the linearized phonon Boltzmann equation within the single-mode relaxation time approximation (RTA). It is found that the lattice thermal conductivity () of the AsP monolayer is very close to the one of As monolayer with a similar buckled structure, which is due to neutralization between the reduction of phonon lifetimes and group velocity enhancement from As to AsP monolayer. The corresponding room-temperature sheet thermal conductance of AsP monolayer is 152.5 . It is noted that the increasing tensile strain can harden a long wavelength out-of-plane (ZA) acoustic mode, and soften the in-plane longitudinal acoustic (LA) and transversal acoustic (TA) modes. Calculated results show that of AsP monolayer presents a nonmonotonic up-and-down behavior with increased strain. The unusual strain dependence is due to the competition among the reduction of phonon group velocities, improved phonon lifetimes of ZA mode and nonmonotonic up-and-down phonon lifetimes of TA/LA mode. It is found that acoustic branches dominate the in the considered strain range, and the contribution from ZA branch increases with increased strain, while it is opposite for TA/LA branch. By analyzing cumulative with respect to phonon mean free path, tensile strain can modulate effectively the size effects on in the AsP monolayer. Our work enriches the studies of thermal transports of 2D materials with graphene-like buckled structures, and strengthens the idea to engineer thermal transport properties by simple mechanical strain, and stimulates further experimental works to synthesize AsP monolayers.

Thermodynamic and transport properties of gaseous tetrafluoromethane in chemical equilibrium

NASA Technical Reports Server (NTRS)

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abbas, M. M.; Craven, P. D.; LeClair, A. C.

2010-08-01

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

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

NASA Technical Reports Server (NTRS)

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

2010-01-01

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

Wax Layers on Cosmos bipinnatus Petals Contribute Unequally to Total Petal Water Resistance1[OPEN

PubMed Central

Buschhaus, Christopher; Hager, Dana; Jetter, Reinhard

2015-01-01

Cuticular waxes coat all primary aboveground plant organs as a crucial adaptation to life on land. Accordingly, the properties of waxes have been studied in much detail, albeit with a strong focus on leaf and fruit waxes. Flowers have life histories and functions largely different from those of other organs, and it remains to be seen whether flower waxes have compositions and physiological properties differing from those on other organs. This work provides a detailed characterization of the petal waxes, using Cosmos bipinnatus as a model, and compares them with leaf and stem waxes. The abaxial petal surface is relatively flat, whereas the adaxial side consists of conical epidermis cells, rendering it approximately 3.8 times larger than the projected petal area. The petal wax was found to contain unusually high concentrations of C22 and C24 fatty acids and primary alcohols, much shorter than those in leaf and stem waxes. Detailed analyses revealed distinct differences between waxes on the adaxial and abaxial petal sides and between epicuticular and intracuticular waxes. Transpiration resistances equaled 3 × 104 and 1.5 × 104 s m−1 for the adaxial and abaxial surfaces, respectively. Petal surfaces of C. bipinnatus thus impose relatively weak water transport barriers compared with typical leaf cuticles. Approximately two-thirds of the abaxial surface water barrier was found to reside in the epicuticular wax layer of the petal and only one-third in the intracuticular wax. Altogether, the flower waxes of this species had properties greatly differing from those on vegetative organs. PMID:25413359

14 CFR 291.2 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... REGULATIONS CARGO OPERATIONS IN INTERSTATE AIR TRANSPORTATION General § 291.2 Definitions. All-cargo air transportation means the transportation by aircraft in interstate air transportation of only property or only mail, or both. Interstate air transportation means the transportation of passengers or property by...

41 CFR 101-27.507 - Transportation and other costs.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Transportation and other costs. 101-27.507 Section 101-27.507 Public Contracts and Property Management Federal Property... MANAGEMENT 27.5-Return of GSA Stock Items § 101-27.507 Transportation and other costs. Transportation costs...

41 CFR 101-27.507 - Transportation and other costs.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 41 Public Contracts and Property Management 2 2014-07-01 2012-07-01 true Transportation and other costs. 101-27.507 Section 101-27.507 Public Contracts and Property Management Federal Property... MANAGEMENT 27.5-Return of GSA Stock Items § 101-27.507 Transportation and other costs. Transportation costs...

41 CFR 101-27.507 - Transportation and other costs.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 41 Public Contracts and Property Management 2 2011-07-01 2007-07-01 true Transportation and other costs. 101-27.507 Section 101-27.507 Public Contracts and Property Management Federal Property... MANAGEMENT 27.5-Return of GSA Stock Items § 101-27.507 Transportation and other costs. Transportation costs...

41 CFR 102-117.5 - What is transportation management?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What is transportation management? 102-117.5 Section 102-117.5 Public Contracts and Property Management Federal Property Management... General § 102-117.5 What is transportation management? Transportation management is agency oversight of...

41 CFR 102-117.5 - What is transportation management?

Code of Federal Regulations, 2014 CFR

2014-01-01

... 41 Public Contracts and Property Management 3 2014-01-01 2014-01-01 false What is transportation management? 102-117.5 Section 102-117.5 Public Contracts and Property Management Federal Property Management... General § 102-117.5 What is transportation management? Transportation management is agency oversight of...

A cell stabilization factor for transport of experimental cell cultures to and from the International Space Station

NASA Astrophysics Data System (ADS)

Fattaey, Heideh K.; Consigli, Richard A.; Grenz, Ladonna; Johnson, Terry C.

2000-01-01

The requirement for long term storage of cell cultures previous to arrival on the International Space Station (ISS), as well as culture maintenance after the conduct of experiment in microgravity, necessitates inhibition of cell proliferation and metabolism pending return to earth-based laboratories. Transport of cells in a nonstabilized condition can lead to a loss of cell viability and/or a source of selection pressures for survival that can alter the overall cell population. We have isolated in our laboratory a reversible inhibitor of cell proliferation, a cell regulatory sialoglycopeptide (CeReS-18), that has the capability of stabilizing cells isolated from a wide phylogenetic range by arresting them in the G1 phase of the cell cycle. We show here that CeReS-18 is unusually stable and can be stored at ambient temperatures for weeks without a measurable loss in its biological activity. In addition we demonstrate that CeReS-18 is a superior cell-stabilizing agent as compared to other methods deployed for cell stabilization purposes, such as, decrease in the incubation temperature and serum down shifts. We also discovered that hybridoma cultures stabilized in their proliferative cycle by CeReS-18 produced 150%-300% more antibody per cell than that measured in the proliferating control cultures. The reversible inhibitory activity of CeReS-18, together with its unusual stability, as well as its wide target range lend themselves to use of this inhibitor as a cell stabilizing agent for cell transport to and storage on the ISS. .

Catalytic and transport cycles of ABC exporters.

PubMed

Al-Shawi, Marwan K

2011-09-07

ABC (ATP-binding cassette) transporters are arguably the most important family of ATP-driven transporters in biology. Despite considerable effort and advances in determining the structures and physiology of these transporters, their fundamental molecular mechanisms remain elusive and highly controversial. How does ATP hydrolysis by ABC transporters drive their transport function? Part of the problem in answering this question appears to be a perceived need to formulate a universal mechanism. Although it has been generally hoped and assumed that the whole superfamily of ABC transporters would exhibit similar conserved mechanisms, this is proving not to be the case. Structural considerations alone suggest that there are three overall types of coupling mechanisms related to ABC exporters, small ABC importers and large ABC importers. Biochemical and biophysical characterization leads us to the conclusion that, even within these three classes, the catalytic and transport mechanisms are not fully conserved, but continue to evolve. ABC transporters also exhibit unusual characteristics not observed in other primary transporters, such as uncoupled basal ATPase activity, that severely complicate mechanistic studies by established methods. In this chapter, I review these issues as related to ABC exporters in particular. A consensus view has emerged that ABC exporters follow alternating-access switch transport mechanisms. However, some biochemical data suggest that alternating catalytic site transport mechanisms are more appropriate for fully symmetrical ABC exporters. Heterodimeric and asymmetrical ABC exporters appear to conform to simple alternating-access-type mechanisms.

Tolyporphin-An Unusual Green Chlorin-like Dioxobacteriochlorin.

PubMed

Brückner, Christian

2017-10-01

The tolyporphins, a family of green tetrapyrrolic pigments isolated from a cyanobacterium-microbial ecological unit, possess unique carbohydrate-derivatized dioxobacteriochlorin frameworks. A brief overview over the history, synthesis, chemistry and biological properties of the tolyporphins forms the backdrop for highlighting the contribution by Hood et al. (Photochem. Photobiol., 2017, https://doi.org/10.1111/php.12781) who demonstrate the optical properties of tolyporphins to be more similar to those of chlorins than of bacteriochlorins. This property could be correlated with the presence of β-oxo-functionalities. The study continues to clarify the structure, properties and possible roles of these intriguing chromophores with a range of biomedical properties. © 2017 The American Society of Photobiology.

Understanding Williams Syndrome: Behavioral Patterns and Interventions.

ERIC Educational Resources Information Center

Semel, Eleanor; Rosner, Sue R.

This guide to Williams syndrome (WS), a congenital disorder characterized by developmental/cognitive limitations but relatively high verbal and social skills, explains the strengths, difficulties and variations found among individuals with the condition and offers guidelines for intervention in the unusual properties of the WS behavioral profile.…

Susceptibility of sweetpotato (Ipomoea batatas) peel proteins to digestive enzymes

USDA-ARS?s Scientific Manuscript database

Sweet potato proteins have been shown to possess antioxidant and antidiabetic properties in vivo. The ability of a protein to exhibit systemic effects is somewhat unusual as proteins are typically susceptible to digestive enzymes. This study was undertaken to better understand how digestive enzymes ...

Some Unusual Expressions for the Inradius of a Triangle

ERIC Educational Resources Information Center

Osler, Thomas J.; Chandrupatla, Tirupathi R.

2005-01-01

Several formulae for the inradius of various types of triangles are derived. Properties of the inradius and trigonometric functions of the angles of Pythagorean and Heronian triangles are also presented. The entire presentation is elementary and suitable for classes in geometry, precalculus mathematics and number theory.

Comprehensive Analysis of Transport Proteins Encoded Within the Genome of Bdellovibrio bacteriovorus

PubMed Central

Barabote, Ravi D.; Rendulic, Snjezana; Schuster, Stephan C.; Saier, Milton H.

2012-01-01

Bdellovibrio bacteriovorus is a bacterial parasite with an unusual lifestyle. It grows and reproduces in the periplasm of a host prey bacterium. The complete genome sequence of B. bacteriovorus has recently been reported. We have reanalyzed the transport proteins encoded within the B. bacteriovorus genome according to the current content of the transporter classification database (TCDB). A comprehensive analysis is given on the types and numbers of transport systems that B. bacteriovorus has. In this regard, the potential protein secretory capabilities of at least 4 types of inner membrane secretion systems and 5 types for outer membrane secretion are described. Surprisingly, B. bacteriovorus has a disproportionate percentage of cytoplasmic membrane channels and outer membrane porins. It has far more TonB/ExbBD-type systems and MotAB-type systems for energizing outer membrane transport and motility than does E. coli. Analysis of probable substrate specificities of its transporters provides clues to its metabolic preferences. Interesting examples of gene fusions and of potentially overlapping genes were also noted. Our analyses provide a comprehensive, detailed appreciation of the transport capabilities of B. bacteriovorus. They should serve as a guide for functional experimental analyses. PMID:17706914

High surface conductivity of Fermi-arc electrons in Weyl semimetals

NASA Astrophysics Data System (ADS)

Resta, Giacomo; Pi, Shu-Ting; Wan, Xiangang; Savrasov, Sergey Y.

2018-02-01

Weyl semimetals (WSMs), a new type of topological condensed matter, are currently attracting great interest due to their unusual electronic states and intriguing transport properties such as chiral anomaly induced negative magnetoresistance, a semiquantized anomalous Hall effect, and the debated chiral magnetic effect. These systems are close cousins of topological insulators (TIs) which are known for their disorder-tolerant surface states. Similarly, WSMs exhibit unique topologically protected Fermi-arc surface states. Here, we analyze electron-phonon scattering, a primary source of resistivity in metals at finite temperatures, as a function of the shape of the Fermi arc where we find that the impact on surface transport is significantly dependent on the arc curvature and disappears in the limit of a straight arc. Next, we discuss the effect of strong surface disorder on the resistivity by numerically simulating a tight-binding model with the presence of quenched surface vacancies using the coherent potential approximation and Kubo-Greenwood formalism. We find that the limit of a straight arc geometry is remarkably disorder tolerant, producing surface conductivity that is one to two orders of magnitude larger than a comparable setup with surface states of TI. This is primarily attributed to a significantly different hybridization strength of the surface states with the remaining electrons in two systems. Finally, a simulation of the effects of surface vacancies on TaAs is presented, illustrating the disorder tolerance of the topological surface states in a recently discovered WSM material.

Transport Optical and Magnetic Properties of Solids.

DTIC Science & Technology

Solid state physics, Band theory of solids, Semiconductors, Strontium compounds, Superconductors, Magnetic properties, Chalcogens, Transport properties, Optical properties, Bibliographies, Scientific research, Magnons

Trifluoromethyl ethers – synthesis and properties of an unusual substituent

PubMed Central

Manteau, Baptiste; Vors, Jean-Pierre; Pazenok, Sergiy

2008-01-01

Summary After nitrogen, fluorine is probably the next most favorite hetero-atom for incorporation into small molecules in life science-oriented research. This review focuses on a particular fluorinated substituent, the trifluoromethoxy group, which is finding increased utility as a substituent in bioactives, but it is still perhaps the least well understood fluorine substituent in currency. The present review will give an overview of the synthesis, properties and reactivity of this important substituent. PMID:18941485

Electrical and Thermal Transport Property Studies of High-Temperature Thermoelectric Materials.

DTIC Science & Technology

1984-12-15

Transport Property Studies of High-Temperature Thermoelectric Mateial 12. PERSONAL AUTHIOR(S) 113. TYPE OF REPORT 13b. TIME COVERED Ai DATE OF REPORtT (Yr...with an ABO(3 perovskite structure. Transport properties have been determined for various doping ele- ments and for different compositions. These data...THERMAL TRANSPORT PROPERTY STUDIES Unannounced [j OF HIGH-TEMPERATURE THERMOELECTRIC MATERIALS Justi±icI iou. CONTRACT F-49620-83-0109 DEF By-- Battelle

Electronic transport properties of nanostructured MnSi-films

NASA Astrophysics Data System (ADS)

Schroeter, D.; Steinki, N.; Scarioni, A. Fernández; Schumacher, H. W.; Süllow, S.; Menzel, D.

2018-05-01

MnSi, which crystallizes in the cubic B20 structure, shows intriguing magnetic properties involving the existence of skyrmions in the magnetic phase diagram. Bulk MnSi has been intensively investigated and thoroughly characterized, in contrast to MnSi thin film, which exhibits widely varying properties in particular with respect to electronic transport. In this situation, we have set out to reinvestigate the transport properties in MnSi thin films by means of studying nanostructure samples. In particular, Hall geometry nanostructures were produced to determine the intrinsic transport properties.

Plant seeds as sources of potential industrial chemicals, pharmaceuticals and pest control agents

USDA-ARS?s Scientific Manuscript database

Investigations of natural products isolated from seeds have resulted in a remarkable variety of compounds having unusual structures and properties. Seeds of many species contained uncommon fatty acids and lipids, some of which have found uses in the cosmetic industry or as renewable (non-petroleum ...

41 CFR 101-39.407 - Accident records.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 41 Public Contracts and Property Management 2 2011-07-01 2007-07-01 true Accident records. 101-39...-INTERAGENCY FLEET MANAGEMENT SYSTEMS 39.4-Accidents and Claims § 101-39.407 Accident records. If GSA's records of vehicle accidents indicate that a particular activity has had an unusually high accident frequency...

How to Learn and Have Fun with Poly(Vinyl Alcohol) and White Glue.

ERIC Educational Resources Information Center

de Zea Bermudez, V.; Passos de Almeida, P.; Feria Seita, J.

1998-01-01

Presents a classroom guide for a simple theoretical approach to the study of certain fluids. Discusses background information, followed by experimental procedures for the preparation of two popular viscoelastic materials ("Slime" and "Silly Putty") that exhibit unusual flow properties. Also lists student discussion questions…

Effect of blood viscosity on oxygen transport in residual stenosed artery following angioplasty.

PubMed

Kwon, Ohwon; Krishnamoorthy, Mahesh; Cho, Young I; Sankovic, John M; Banerjee, Rupak K

2008-02-01

The effect of blood viscosity on oxygen transport in a stenosed coronary artery during the postangioplasty scenario is studied. In addition to incorporating varying blood viscosity using different hematocrit (Hct) concentrations, oxygen consumption by the avascular wall and its supply from vasa vasorum, nonlinear oxygen binding capacity of the hemoglobin, and basal to hyperemic flow rate changes are included in the calculation of oxygen transport in both the lumen and the avascular wall. The results of this study show that oxygen transport in the postangioplasty residual stenosed artery is affected by non-Newtonian shear-thinning property of the blood viscosity having variable Hct concentration. As Hct increases from 25% to 65%, the diminished recirculation zone for the increased Hct causes the commencement of pO(2) decrease to shift radially outward by approximately 20% from the center of the artery for the basal flow, but by approximately 10% for the hyperemic flow at the end of the diverging section. Oxygen concentration increases from a minimum value at the core of the recirculation zone to over 90 mm Hg before the lumen-wall interface at the diverging section for the hyperemic flow, which is attributed to increased shear rate and thinner lumen boundary layer for the hyperemic flow, and below 90 mm Hg for the basal flow. As Hct increases from 25% to 65%, the average of pO(2,min) beyond the diverging section drops by approximately 25% for the basal flow, whereas it increases by approximately 15% for the hyperemic flow. Thus, current results with the moderate stenosed artery indicate that reducing Hct might be favorable in terms of increasing O(2) flux and pO(2,min), in the medial region of the wall for the basal flow, while higher Hct is advantageous for the hyperemic flow beyond the diverging section. The results of this study not only provide significant details of oxygen transport under varying pathophysiologic blood conditions such as unusually high blood viscosity and flow rate, but might also be extended to offer implications for drug therapy related to blood-thinning medication and for blood transfusion and hemorrhage.

41 CFR 303-70.301 - Are there any limitations on the baggage we may transport?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 41 Public Contracts and Property Management 4 2011-07-01 2011-07-01 false Are there any limitations on the baggage we may transport? 303-70.301 Section 303-70.301 Public Contracts and Property... on the baggage we may transport? Yes. You may only transport government property and the employee's...

41 CFR 303-70.301 - Are there any limitations on the baggage we may transport?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 4 2010-07-01 2010-07-01 false Are there any limitations on the baggage we may transport? 303-70.301 Section 303-70.301 Public Contracts and Property... on the baggage we may transport? Yes. You may only transport government property and the employee's...

49 CFR 369.1 - Annual reports of motor carriers of property, motor carriers of household goods, and dual...

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 5 2014-10-01 2014-10-01 false Annual reports of motor carriers of property, motor carriers of household goods, and dual property carriers. 369.1 Section 369.1 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL MOTOR CARRIER...

Liquid Structure with Nano-Heterogeneity Promotes Cationic Transport in Concentrated Electrolytes.

PubMed

Borodin, Oleg; Suo, Liumin; Gobet, Mallory; Ren, Xiaoming; Wang, Fei; Faraone, Antonio; Peng, Jing; Olguin, Marco; Schroeder, Marshall; Ding, Michael S; Gobrogge, Eric; von Wald Cresce, Arthur; Munoz, Stephen; Dura, Joseph A; Greenbaum, Steve; Wang, Chunsheng; Xu, Kang

2017-10-24

Using molecular dynamics simulations, small-angle neutron scattering, and a variety of spectroscopic techniques, we evaluated the ion solvation and transport behaviors in aqueous electrolytes containing bis(trifluoromethanesulfonyl)imide. We discovered that, at high salt concentrations (from 10 to 21 mol/kg), a disproportion of cation solvation occurs, leading to a liquid structure of heterogeneous domains with a characteristic length scale of 1 to 2 nm. This unusual nano-heterogeneity effectively decouples cations from the Coulombic traps of anions and provides a 3D percolating lithium-water network, via which 40% of the lithium cations are liberated for fast ion transport even in concentration ranges traditionally considered too viscous. Due to such percolation networks, superconcentrated aqueous electrolytes are characterized by a high lithium-transference number (0.73), which is key to supporting an assortment of battery chemistries at high rate. The in-depth understanding of this transport mechanism establishes guiding principles to the tailored design of future superconcentrated electrolyte systems.

Small molecule induced oligomerization, clustering and clathrin-independent endocytosis of the dopamine transporter

PubMed Central

Sorkina, Tatiana; Ma, Shiqi; Larsen, Mads Breum; Watkins, Simon C

2018-01-01

Clathrin-independent endocytosis (CIE) mediates internalization of many transmembrane proteins but the mechanisms of cargo recruitment during CIE are poorly understood. We found that the cell-permeable furopyrimidine AIM-100 promotes dramatic oligomerization, clustering and CIE of human and mouse dopamine transporters (DAT), but not of their close homologues, norepinephrine and serotonin transporters. All effects of AIM-100 on DAT and the occupancy of substrate binding sites in the transporter were mutually exclusive, suggesting that AIM-100 may act by binding to DAT. Surprisingly, AIM-100-induced DAT endocytosis was independent of dynamin, cholesterol-rich microdomains and actin cytoskeleton, implying that a novel endocytic mechanism is involved. AIM-100 stimulated trafficking of internalized DAT was also unusual: DAT accumulated in early endosomes without significant recycling or degradation. We propose that AIM-100 augments DAT oligomerization through an allosteric mechanism associated with the DAT conformational state, and that oligomerization-triggered clustering leads to a coat-independent endocytosis and subsequent endosomal retention of DAT. PMID:29630493

The effect of high-pressure torsion on the microstructure and properties of magnesium

NASA Astrophysics Data System (ADS)

Figueiredo, Roberto B.; Sabbaghianrad, Shima; Langdon, Terence G.

2017-05-01

High-pressure torsion provides the opportunity to introduce significant plastic strain at room temperature in magnesium and its alloys. It is now established that this processing operation produces ultrafine-grained structures and changes the properties of these materials. The present paper shows that the mechanism of grain refinement differs from f.c.c. and b.c.c. materials. It is shown that fine grains are formed at the grain boundaries of coarse grains and gradually consume the whole structure. Also, the processed material exhibits unusual mechanical properties due to the activation of grain boundary sliding at room temperature.

Phase transitions and thermodynamic properties of antiferromagnetic Ising model with next-nearest-neighbor interactions on the Kagomé lattice

NASA Astrophysics Data System (ADS)

Ramazanov, M. K.; Murtazaev, A. K.; Magomedov, M. A.; Badiev, M. K.

2018-06-01

We study phase transitions and thermodynamic properties in the two-dimensional antiferromagnetic Ising model with next-nearest-neighbor interaction on a Kagomé lattice by Monte Carlo simulations. A histogram data analysis shows that a second-order transition occurs in the model. From the analysis of obtained data, we can assume that next-nearest-neighbor ferromagnetic interactions in two-dimensional antiferromagnetic Ising model on a Kagomé lattice excite the occurrence of a second-order transition and unusual behavior of thermodynamic properties on the temperature dependence.

41 CFR 302-7.10 - Is property acquired en route eligible for transportation at Government expense?

Code of Federal Regulations, 2010 CFR

2010-07-01

... PROPERTY 7-TRANSPORTATION AND TEMPORARY STORAGE OF HOUSEHOLD GOODS AND PROFESSIONAL BOOKS, PAPERS, AND EQUIPMENT (PBP&E) General Rules § 302-7.10 Is property acquired en route eligible for transportation at...

Probing Mitotic CENP-E Kinesin with the Tethered Cargo Motion Assay and Laser Tweezers.

PubMed

Gudimchuk, Nikita; Tarasovetc, Ekaterina V; Mustyatsa, Vadim; Drobyshev, Alexei L; Vitre, Benjamin; Cleveland, Don W; Ataullakhanov, Fazly I; Grishchuk, Ekaterina L

2018-06-05

Coiled-coil stalks of various kinesins differ significantly in predicted length and structure; this is an adaption that helps these motors carry out their specialized functions. However, little is known about the dynamic stalk configuration in moving motors. To gain insight into the conformational properties of the transporting motors, we developed a theoretical model to predict Brownian motion of a microbead tethered to the tail of a single, freely walking molecule. This approach, which we call the tethered cargo motion (TCM) assay, provides an accurate measure of the mechanical properties of motor-cargo tethering, verified using kinesin-1 conjugated to a microbead via DNA links in vitro. Applying the TCM assay to the mitotic kinesin CENP-E unexpectedly revealed that when walking along a microtubule track, this highly elongated molecule with a contour length of 230 nm formed a 20-nm-long tether. The stalk of a walking CENP-E could not be extended fully by application of sideways force with optical tweezers (up to 4 pN), implying that CENP-E carries its cargo in a compact configuration. Assisting force applied along the microtubule track accelerates CENP-E walking, but this increase does not depend on the presence of the CENP-E stalk. Our results suggest that the unusually large stalk of CENP-E has little role in regulating its function as a transporter. The adjustable stalk configuration may represent a regulatory mechanism for controlling the physical reach between kinetochore-bound CENP-E and spindle microtubules, or it may assist localizing various kinetochore regulators in the immediate vicinity of the kinetochore-embedded microtubule ends. The TCM assay and underlying theoretical framework will provide a general guide for determining the dynamic configurations of various molecular motors moving along their tracks, freely or under force. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Prospects of Two-Dimensional Devices: Electrical and Optical Characterization of Transition Metal Dichalcogenide Films

NASA Astrophysics Data System (ADS)

Klee, Velveth

Understanding the electrical and optical properties of 2D materials down to their monolayer limit is important for establishing their potential for novel applications. Prominent among 2D materials are transition metal dichalcogenides (TMDs), such as MoS2 and MoSe2. These materials have attracted attention because of their intriguing properties, such as a transition from an indirect bandgap for few layers to a direct bandgap for monolayers. New synthetic routes like chemical vapor deposition (CVD) allow for high-quality, centimeter-scale growth and tuning of the direct optical gap continuously between the values of single-layer MoS2 (1.87eV) and MoSe 2 (1.55eV). In the first part of this work, we perform optoelectronic measurements of alloy devices fabricated on CVD-grown, monolayer MoS2, MoS 2(1-x)Se2x, and MoSe2 islands. For all alloy compositions there is an unusual superlinear dependence of the photocurrent on light intensity. We also establish the photoconductive nature of the photoresponse, with the photocurrent originating from recombination and field-induced carrier separation in the channel. The study of transport characteristics of TMDs is extended to explore the effects of devices on a piezoelectric substrate as a route towards establishing fabrication processes suited for industry. In this work, we show that CVD-growth of MoS2 monolayer films onto periodically poled lithium niobate is possible while maintaining the substrate polarization pattern. Electrical transport measurements indicate an inversion of the MoS2 from n-type to p-type behavior under application of an external voltage depending on the domain orientation of the ferroelectric substrate. Sensitivity to ferroelectric substrate polarization opens the possibility for ferroelectric nonvolatile gating of TMDs in scalable devices fabricated free of exfoliation and transfer. Optimizing CVD techniques allows for preparation of TMD films in different phases that are reported to exhibit semiconducting and metallic properties. Here, we show optical and electronic characterization of few-layer films of MoTe2 in three distinct structural phases: 2H, 1T' and 1T. Depending on process parameters, either of the phases can be prepared using MoO3 and elemental tellurium precursors. Experimental and computed Raman spectra are presented for each phase. Transport measurements validate predictions from DFT-based band structure calculations on the metallic character of the centrosymmetric 1T phase.

Triton's surface properties - A preliminary analysis from ground-based, Voyager photopolarimeter subsystem, and laboratory measurements

NASA Technical Reports Server (NTRS)

Buratti, B. J.; Lane, A. L.; Gibson, J.; Burrows, H.; Nelson, R. M.; Bliss, D.; Smythe, W.; Garkanian, V.; Wallis, B.

1991-01-01

The surface properties of Triton were investigated using data from the ground-based and Voyager photopolarimeter subsystem (PPS) observations of Triton's phase curve. The results indicate that Triton has a high single-scattering albedo (0.96 +/-0.01 at 0.75 micron) and an unusually compacted surface, possibly similar to that of Europa. Results also suggest that Triton's single-particle phase function and the macroscopically rough character of its surface are similar to those of most other icy satellites.

Structural and magnetic properties of two- and three-dimensional molecule-based magnets (cat) +[M IIM III(C 2O 4) 3] -

NASA Astrophysics Data System (ADS)

Ovanesyan, Nikolai S.; Shilov, Gena V.; Pyalling, Alex A.; Train, Cyrille; Gredin, Patrick; Gruselle, Michel; Kiss, László F.; Bottyán, László

2004-05-01

We discuss the different structural arrangements of NBu 4[Fe IICr III(C 2O 4) 3] layered compounds in their racemic and enantiomeric forms and related magnetic properties. For [Mn IIFe III(C 2O 4) 3] networks of dimensionalities 2 and 3 Mössbauer spectroscopy was applied to study the Fe III sublattice magnetization. Unusual magnetic relaxation phenomena below TN were observed for both 2D and 3D networks.

New Quasi Low-Dimensional 4d and 5d Transition Metal Oxides with Correlated Electronic Properties - Synthesis and Characterizations

DTIC Science & Technology

2016-02-17

high pressure (HP) and high temperature ( HT ) synthesis to find new interesting and potentially useful polar materials. As will be shown here, we have...of general formula A2BB’O6. In addition, HP and HT were also used to prepare new metastable double perovskites and quadruple perovskites with unusual...transition metals and exotic correlated electronic properties was used in parallel with the HP/ HT projects. As the results enumerated below show, a

41 CFR 102-118.290 - Must every electronic and paper transportation bill undergo a prepayment audit?

Code of Federal Regulations, 2010 CFR

2010-07-01

... and paper transportation bill undergo a prepayment audit? 102-118.290 Section 102-118.290 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT Prepayment Audits of Transportation...

Growth dynamics and gas transport mechanism of nanobubbles in graphene liquid cells.

PubMed

Shin, Dongha; Park, Jong Bo; Kim, Yong-Jin; Kim, Sang Jin; Kang, Jin Hyoun; Lee, Bora; Cho, Sung-Pyo; Hong, Byung Hee; Novoselov, Konstantin S

2015-02-02

Formation, evolution and vanishing of bubbles are common phenomena in nature, which can be easily observed in boiling or falling water, carbonated drinks, gas-forming electrochemical reactions and so on. However, the morphology and the growth dynamics of the bubbles at nanoscale have not been fully investigated owing to the lack of proper imaging tools that can visualize nanoscale objects in the liquid phase. Here, we demonstrate for the first time that the nanobubbles in water encapsulated by graphene membrane can be visualized by in-situ ultra-high vacuum transmission electron microscopy. Our microscopic results indicate two distinct growth mechanisms of merging nanobubbles and the existence of a critical radius of nanobubbles that determines the unusually long stability of nanobubbles. Interestingly, the gas transport through ultrathin water membranes at nanobubble interface is free from dissolution, which is clearly different from conventional gas transport that includes condensation, transmission and evaporation.

Non-scaling behavior of electroosmotic flow in voltage-gated nanopores

DOE PAGES

Lian, Cheng; Gallegos, Alejandro; Liu, Honglai; ...

2016-11-17

Ionic transport through nanopores is of fundamental importance for the design and development of nanofiltration membranes and novel electrochemical devices including supercapacitors, fuel cells and batteries. Recent experiments have shown an unusual variation of electrical conductance with the pore size and the electrolyte parameters that defies conventional scaling relations. Here ionic transport through voltage-gated nanopores was studied by using the classical density functional theory for ion distributions in combination with the Navier–Stokes equation for the electroosmotic flow. We also identified a significant influence of the gating potential on the scaling behavior of the conductance with changes in the pore sizemore » and the salt concentration. Finally, for ion transport in narrow pores with a high gating voltage, the conductivity shows an oscillatory dependence on the pore size owing to the strong overlap of electric double layers.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Cheng-Long; Xu, Su-Yang; Belopolski, Ilya

Weyl semimetals provide the realization of Weyl fermions in solid-state physics. Among all the physical phenomena that are enabled by Weyl semimetals, the chiral anomaly is the most unusual one. Here, we report signatures of the chiral anomaly in the magneto-transport measurements on the first Weyl semimetal TaAs. We show negative magnetoresistance under parallel electric and magnetic fields, that is, unlike most metals whose resistivity increases under an external magnetic field, we observe that our high mobility TaAs samples become more conductive as a magnetic field is applied along the direction of the current for certain ranges of the fieldmore » strength. We present systematically detailed data and careful analyses, which allow us to exclude other possible origins of the observed negative magnetoresistance. Finally, our transport data, corroborated by photoemission measurements, first-principles calculations and theoretical analyses, collectively demonstrate signatures of the Weyl fermion chiral anomaly in the magneto-transport of TaAs.« less

Martian dunite NWA 2737: Integrated spectroscopic analyses of brown olivine

NASA Astrophysics Data System (ADS)

Pieters, Carle M.; Klima, Rachel L.; Hiroi, Takahiro; Dyar, M. Darby; Lane, Melissa D.; Treiman, Allan H.; Noble, Sarah K.; Sunshine, Jessica M.; Bishop, Janice L.

2008-06-01

A second Martian meteorite has been identified that is composed primarily of heavily shocked dunite, Northwest Africa (NWA) 2737. This meteorite has several similarities to the Chassigny dunite cumulate, but the olivine is more Mg rich and, most notably, is very dark and visually brown. Carefully coordinated analyses of NWA 2737 whole-rock and olivine separates were undertaken using visible and near-infrared reflectance, midinfrared emission and reflectance, and Mössbauer spectroscopic studies of the same samples along with detailed petrography, chemistry, scanning electron microscopy, and transmission electron microscopy analyses. Midinfrared spectra of this sample indicate that the olivine is fully crystalline and that its molecular structure remains intact. The unusual color and spectral properties that extend from the visible through the near-infrared part of the spectrum are shown to be due to nanophase metallic iron particles dispersed throughout the olivine during a major shock event on Mars. Although a minor amount of Fe3+ is present, it cannot account for the well-documented unusual optical properties of Martian meteorite NWA 2737. Perhaps unique to the Martian environment, this ``brown'' olivine exhibits spectral properties that can potentially be used to remotely explore the pressure-temperature history of surface geology as well as assess surface composition.

Anomalously soft non-Euclidean spring

NASA Astrophysics Data System (ADS)

Levin, Ido; Sharon, Eran

In this work we study the mechanical properties of a frustrated elastic ribbon spring - the non-Euclidean minimal spring. This spring belongs to the family of non-Euclidean plates: it has no spontaneous curvature, but its lateral intrinsic geometry is described by a non-Euclidean reference metric. The reference metric of the minimal spring is hyperbolic, and can be embedded as a minimal surface. We argue that the existence of a continuous set of such isometric minimal surfaces with different extensions leads to a complete degeneracy of the bulk elastic energy of the minimal spring under elongation. This degeneracy is removed only by boundary layer effects. As a result, the mechanical properties of the minimal spring are unusual: the spring is ultra-soft with rigidity that depends on the thickness, t , as t raise 0 . 7 ex 7 7 2 lower 0 . 7 ex 2, and does not explicitly depend on the ribbon's width. These predictions are confirmed by a numerical study of a constrained spring. This work is the first to address the unusual mechanical properties of constrained non-Euclidean elastic objects. We also present a novel experimental system that is capable of constructing such objects, along with many other non-Euclidean plates.

Evaluation of transport conditions for autologous bone marrow-derived mesenchymal stromal cells for therapeutic application in horses

PubMed Central

Espina, Miguel; Jülke, Henriette; Brehm, Walter; Ribitsch, Iris; Winter, Karsten

2016-01-01

Background. Mesenchymal stromal cells (MSCs) are increasingly used for clinical applications in equine patients. For MSC isolation and expansion, a laboratory step is mandatory, after which the cells are sent back to the attending veterinarian. Preserving the biological properties of MSCs during this transport is paramount. The goal of the study was to compare transport-related parameters (transport container, media, temperature, time, cell concentration) that potentially influence characteristics of culture expanded equine MSCs. Methods. The study was arranged in three parts comparing (I) five different transport containers (cryotube, two types of plastic syringes, glass syringe, CellSeal), (II) seven different transport media, four temperatures (4 °C vs. room temperature; −20 °C vs. −80 °C), four time frames (24 h vs. 48 h; 48 h vs. 72 h), and (III) three MSC concentrations (5 × 106, 10 × 106, 20 × 106 MSC/ml). Cell viability (Trypan Blue exclusion; percent and total number viable cell), proliferation and trilineage differentiation capacity were assessed for each test condition. Further, the recovered volume of the suspension was determined in part I. Each condition was evaluated using samples of six horses (n = 6) and differentiation protocols were performed in duplicates. Results. In part I of the study, no significant differences in any of the parameters were found when comparing transport containers at room temperature. The glass syringe was selected for all subsequent evaluations (highest recoverable volume of cell suspension and cell viability). In part II, media, temperatures, or time frames had also no significant influence on cell viability, likely due to the large number of comparisons and small sample size. Highest cell viability was observed using autologous bone marrow supernatant as transport medium, and “transport” at 4 °C for 24 h (70.6% vs. control group 75.3%); this was not significant. Contrary, viability was unacceptably low (<40%) for all freezing protocols at −20 °C or −80 °C, particularly with bone marrow supernatant or plasma and DMSO. In part III, various cell concentrations also had no significant influence on any of the evaluated parameters. Chondrogenic differentiation showed a trend towards being decreased for all transport conditions, compared to control cells. Discussion. In this study, transport conditions were not found to impact viability, proliferation or ability for trilineage differentiation of MSCs, most likely due to the small sample size and large number of comparisons. The unusual low viability after all freezing protocols is in contrast to previous equine studies. Potential causes are differences in the freezing, but also in thawing method. Also, the selected container (glass syringe) may have impacted viability. Future research may be warranted into the possibly negative effect of transport on chondrogenic differentiation. PMID:27019778

TRANSPORT PROPERTY MEASUREMENTS OF HFC-236EA

EPA Science Inventory

The report gives results of an evaluation of transport properties of 1,1,1,2,3,3,-hexafluoropropane (HFC-236ea), with liquid viscosity and thermal conductivity being the two main transport properties of interest. In addition, the specific heat and density of refrigerant/lubrican...

Ionothermal synthesis, characterization of a new layered gallium phosphate with an unusual heptamer SBU

NASA Astrophysics Data System (ADS)

Gao, Fan; Huang, Liangliang; Ma, Yike; Jiao, Shufei; Jiang, Yansong; Bi, Yanfeng

2017-10-01

A new layered gallium phosphate Ga3(PO4)4(C2N2H8)·(H2C2N2H8)2·Cl (compound 1), has been ionothermally synthesized in the presence of deep eutectic solvent (DES) comprising mixtures of choline chloride and 2-imidazolidone (IMI). Single-crystal X-ray diffraction analysis reveals that compound 1 shows 2D layered framework with 10-ring windows, which is constructed from unusual heptamer second building units (SBUs). The ethylenediamine (en) units deriving from the decomposition of IMI, play a dual role as bidentate ligands coordinated with 6-fold coordinate gallium atoms and the templates. Additionally, compound 1 shows photoluminescence property in solid state at room temperature.

41 CFR 102-118.425 - Is my agency allowed to perform a postpayment audit on our transportation bills?

Code of Federal Regulations, 2010 CFR

2010-07-01

... perform a postpayment audit on our transportation bills? 102-118.425 Section 102-118.425 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT Postpayment Transportation Audits § 102-118...

41 CFR 109-40.113 - Insurance against transportation hazards.

Code of Federal Regulations, 2012 CFR

2012-01-01

... transportation hazards. 109-40.113 Section 109-40.113 Public Contracts and Property Management Federal Property..., TRANSPORTATION, AND MOTOR VEHICLES 40-TRANSPORTATION AND TRAFFIC MANAGEMENT 40.1-General Provision § 109-40.113 Insurance against transportation hazards. The policy of the Government with respect to insurance of its...

41 CFR 109-40.113 - Insurance against transportation hazards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... transportation hazards. 109-40.113 Section 109-40.113 Public Contracts and Property Management Federal Property..., TRANSPORTATION, AND MOTOR VEHICLES 40-TRANSPORTATION AND TRAFFIC MANAGEMENT 40.1-General Provision § 109-40.113 Insurance against transportation hazards. The policy of the Government with respect to insurance of its...

Crystal Structure of Cockroach Allergen Bla g 2, an Unusual Zinc Binding Aspartic Protease with a Novel Mode of Self-inhibition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gustchina, Alla; Li, Mi; Wunschmann, Sabina

2010-07-19

The crystal structure of Bla g 2 was solved in order to investigate the structural basis for the allergenic properties of this unusual protein. This is the first structure of an aspartic protease in which conserved glycine residues, in two canonical DTG triads, are substituted by different amino acid residues. Another unprecedented feature revealed by the structure is the single phenylalanine residue insertion on the tip of the flap, with the side-chain occupying the S1 binding pocket. This and other important amino acid substitutions in the active site region of Bla g 2 modify the interactions in the vicinity ofmore » the catalytic aspartate residues, increasing the distance between them to {approx}4 {angstrom} and establishing unique direct contacts between the flap and the catalytic residues. We attribute the absence of substantial catalytic activity in Bla g 2 to these unusual features of the active site. Five disulfide bridges and a Zn-binding site confer stability to the protein, which may contribute to sensitization at lower levels of exposure than other allergens.« less

Origin of Unusual Dependencies of LUMO Levels on Conjugation Length in Quinoidal Fused Oligosiloles

NASA Astrophysics Data System (ADS)

Misawa, Nana; Fujii, Mikiya; Shintani, Ryo; Tsuda, Tomohiro; Nozaki, Kyoko; Yamashita, Koichi

Quinoidal fused oligosiloles, a new family of silicon-bridged π-conjugated compounds, have been synthesized and their physical properties showed a unique trend in their LUMO levels, which become higher with longer π-conjugation. Although this trend was reproduced by the DFT calculations, its origin remained to be discussed. In this work we performed quantum chemical calculations and discovered that the unusual LUMO trend is attributable to the π-frameworks. We elucidated its origin by orbital correlation diagrams based on classical Hückel calculations, essentially. However, LUMO trends cannot fully be explained only by Hückel calculations because of the lack of the consideration of geometries. In the case of quinoidal fused oligosiloles, judging from DFT calculation results, the presence of silole fused structure play an important role in fixing the bond angles of the linear polyenes as an interior angle of siloles, leading to the unusual LUMO behavior. The qualitative but essential understanding of these LUMO trend would provide new insight into molecular design of π-conjugated compounds for tuning their LUMO levels.

Optical Emission Associated with the Galactic Supernova Remnant G179.0+2.6

NASA Astrophysics Data System (ADS)

How, Thomas G.; Fesen, Robert A.; Neustadt, Jack M. M.; Black, Christine S.; Outters, Nicolas

2018-04-01

Narrow passband optical images of the large Galactic supernova remnant G179.0+2.6 reveal a faint but nearly complete emission shell dominated by strong [O 3] 4959,5007 Å line emission. The remnant's optical emission, which consists of both diffuse and filamentary features, is brightest along its southern and northeastern limbs. Deep Hα images detect little coincidence emission indicating an unusually high [O 3]/Hα emission ratio for such a large and apparently old remnant. Low-dispersion optical spectra of several regions confirm large [O 3]/Hα line ratios with typical values around 10. The dominance of [O 3] emission for the majority of the remnant's optical filaments suggests shock velocities above 100 km s-1 are present throughout most of the remnant, likely reflecting a relatively low density ambient ISM. The remnant's unusually strong [O 3] emission adds to the remnant's interesting set of properties which include a thick radio emission shell, radial polarization of its radio emission like that typically seen in young supernova remnants, and an unusually slow-rotating gamma-ray pulsar with a characteristic spin-down age ≃ 50 kyr.

Contribution of the Individual Small Intestinal α-Glucosidases to Digestion of Unusual α-Linked Glycemic Disaccharides.

PubMed

Lee, Byung-Hoo; Rose, David R; Lin, Amy Hui-Mei; Quezada-Calvillo, Roberto; Nichols, Buford L; Hamaker, Bruce R

2016-08-24

The mammalian mucosal α-glucosidase complexes, maltase-glucoamylase (MGAM) and sucrase-isomaltase (SI), have two catalytic subunits (N- and C-termini). Concurrent with the desire to modulate glycemic response, there has been a focus on di-/oligosaccharides with unusual α-linkages that are digested to glucose slowly by these enzymes. Here, we look at disaccharides with various possible α-linkages and their hydrolysis. Hydrolytic properties of the maltose and sucrose isomers were determined using rat intestinal and individual recombinant α-glucosidases. The individual α-glucosidases had moderate to low hydrolytic activities on all α-linked disaccharides, except trehalose. Maltase (N-terminal MGAM) showed a higher ability to digest α-1,2 and α-1,3 disaccharides, as well as α-1,4, making it the most versatile in α-hydrolytic activity. These findings apply to the development of new glycemic oligosaccharides based on unusual α-linkages for extended glycemic response. It also emphasizes that mammalian mucosal α-glucosidases must be used in in vitro assessment of digestion of such carbohydrates.

41 CFR 101-6.2108 - How does the Administrator provide States an opportunity to comment on proposed Federal financial...

Code of Federal Regulations, 2010 CFR

2010-07-01

... Federal development? 101-6.2108 Section 101-6.2108 Public Contracts and Property Management Federal... assistance and direct Federal development? (a) Except in unusual circumstances, the Administrator gives State processes or directly affected State, areawide, regional and local officials and entities at least: (1...

(abstract) Dynamics of Meteor Trails Deposited in the Equatorial Electrojet

NASA Technical Reports Server (NTRS)

Chapin, Elaine; Kudeki, Erhan

1996-01-01

Previously we reported that the meteor echoes detected at the Jicamarca Radio Observatory exhibit some unusual properties. In summary, the echo durations are very long ..., radio wave scattering is non-specular ..., and the doppler spectra of the scattered signals contain components that are red-shifted ... immediately after the onset of the echoes.

An Evidence-Based Environmental Perspective Of Manufactured Silver Nanoparticle In Syntheses And Applications: A Systematic Review And Critical Appraisal Of Peer-Reviewed Scientific Papers

EPA Science Inventory

Most recently, renewed interest has arisen in manufactured silver nanoparticles because of their unusually enhanced physiochemical properties and biological activities compared to the bulk parent materials. A wide range of applications has emerged in consumer products ranging fr...

The Effect of Microgravity on the Growth of Silica Nanostructures

NASA Technical Reports Server (NTRS)

Smith, D. D.; Sibille, L.; Cronise, R.; Oldenburg, S. J.; Wolfe, D.; Halas, N. J.

2001-01-01

The process of the formation of structures from coagulating ensembles is fundamentally important since the collective behavior of the constituents often results in dramatically improved or unusual mechanical, thermal, chemical, and optical properties. In this study we examine the effect of microgravity on the formation of silica structures, specifically particles and gels.

Topological mechanics: from metamaterials to active matter

NASA Astrophysics Data System (ADS)

Vitelli, Vincenzo

2015-03-01

Mechanical metamaterials are artificial structures with unusual properties, such as negative Poisson ratio, bistability or tunable acoustic response, which originate in the geometry of their unit cell. At the heart of such unusual behavior is often a mechanism: a motion that does not significantly stretch or compress the links between constituent elements. When activated by motors or external fields, these soft motions become the building blocks of robots and smart materials. In this talk, we discuss topological mechanisms that possess two key properties: (i) their existence cannot be traced to a local imbalance between degrees of freedom and constraints (ii) they are robust against a wide range of structural deformations or changes in material parameters. The continuum elasticity of these mechanical structures is captured by non-linear field theories with a topological boundary term similar to topological insulators and quantum Hall systems. We present several applications of these concepts to the design and experimental realization of 2D and 3D topological structures based on linkages, origami, buckling meta-materials and lastly active media that break time-reversal symmetry.

Multiple copies of genes coding for electron transport proteins in the bacterium Nitrosomonas europaea.

PubMed

McTavish, H; LaQuier, F; Arciero, D; Logan, M; Mundfrom, G; Fuchs, J A; Hooper, A B

1993-04-01

The genome of Nitrosomonas europaea contains at least three copies each of the genes coding for hydroxylamine oxidoreductase (HAO) and cytochrome c554. A copy of an HAO gene is always located within 2.7 kb of a copy of a cytochrome c554 gene. Cytochrome P-460, a protein that shares very unusual spectral features with HAO, was found to be encoded by a gene separate from the HAO genes.

Equations of state and transport properties of mixtures in the warm dense regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hou, Yong; Dai, Jiayu; Kang, Dongdong

2015-02-15

We have performed average-atom molecular dynamics to simulate the CH and LiH mixtures in the warm dense regime, and obtained equations of state and the ionic transport properties. The electronic structures are calculated by using the modified average-atom model, which have included the broadening of energy levels, and the ion-ion pair potentials of mixtures are constructed based on the temperature-dependent density functional theory. The ionic transport properties, such as ionic diffusion and shear viscosity, are obtained through the ionic velocity correlation functions. The equations of state and transport properties for carbon, hydrogen and lithium, hydrogen mixtures in a wide regionmore » of density and temperature are calculated. Through our computing the average ionization degree, average ion-sphere diameter and transition properties in the mixture, it is shown that transport properties depend not only on the ionic mass but also on the average ionization degree.« less

41 CFR 102-118.25 - Does GSA still require my agency to submit its overall transportation policies for approval?

Code of Federal Regulations, 2010 CFR

2010-07-01

... Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT General Introduction... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Does GSA still require...

41 CFR 102-117.100 - What business rules must I consider before acquiring transportation or related services?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What business rules must... Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 117-TRANSPORTATION MANAGEMENT Business Rules To Consider...

41 CFR 102-118.440 - What are the postpayment audit responsibilities and roles of the GSA Audit Division?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 41 Public Contracts and Property Management 3 2013-07-01 2013-07-01 false What are the postpayment... Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT Postpayment Transportation Audits...

41 CFR 102-118.440 - What are the postpayment audit responsibilities and roles of the GSA Audit Division?

Code of Federal Regulations, 2012 CFR

2012-01-01

... 41 Public Contracts and Property Management 3 2012-01-01 2012-01-01 false What are the postpayment... Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT Postpayment Transportation Audits...

41 CFR 102-118.440 - What are the postpayment audit responsibilities and roles of the GSA Audit Division?

Code of Federal Regulations, 2011 CFR

2011-01-01

... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false What are the postpayment... Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT Postpayment Transportation Audits...

41 CFR 102-118.440 - What are the postpayment audit responsibilities and roles of the GSA Audit Division?

Code of Federal Regulations, 2014 CFR

2014-01-01

... 41 Public Contracts and Property Management 3 2014-01-01 2014-01-01 false What are the postpayment... Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT Postpayment Transportation Audits...

41 CFR 102-118.525 - What are my agency's responsibilities for verifying the correct amount of transportation charges?

Code of Federal Regulations, 2010 CFR

2010-07-01

... Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT Claims and Appeal Procedures... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What are my agency's...

75 FR 37435 - Fact Finding Investigation No. 27; Potentially Unlawful, Unfair or Deceptive Ocean Transportation...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-29

... problems with their international household goods or personal property shipments. Between 2005 and 2009... Deceptive Ocean Transportation Practices Related to the Movement of Household Goods or Personal Property in... transporting household goods or personal property between various locations in the United States and foreign...

Chemistry and Transport Properties for Jet Fuel Combustion

DTIC Science & Technology

2013-04-01

AFRL-OSR-VA-TR-2013-0168 Chemistry and Transport Properties for Jet Fuel Combustion Angela Violi University of Michigan...5a. CONTRACT NUMBER (U) Chemistry and Transport Properties for Jet Fuel Combustion 5b. GRANT NUMBER FA9550-09-1-0021 5c...combustors.   Although,  chemical  kinetic  mechanisms  of  hydrocarbons  have  been  widely  studied,  molecular   transport

Charge Fractionalization in the Two-Channel Kondo Effect

NASA Astrophysics Data System (ADS)

Landau, L. Aviad; Cornfeld, Eyal; Sela, Eran

2018-05-01

The phenomenon of charge fractionalization describes the emergence of novel excitations with fractional quantum numbers, as predicted in strongly correlated systems such as spin liquids. We elucidate that precisely such an unusual effect may occur in the simplest possible non-Fermi liquid, the two-channel Kondo effect. To bring this concept down to experimental test, we study nonequilibrium transport through a device realizing the charge two-channel Kondo critical point in a recent experiment by Iftikhar et al. [Nature (London) 526, 233 (2015), 10.1038/nature15384]. The shot noise at low voltages is predicted to result in a universal Fano factor e*/e =1 /2 . This allows us to experimentally identify elementary transport processes of emergent fermions carrying half-integer charge.

Technical Report: Understanding Functional Lyotropic Liquid Crystal Network Phase Self-Assembly and the Properties of Nanoconfined Water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahanthappa, Mahesh K; Yethiraj, Arun

Through the synergistic interplay of molecular dynamics (MD) simulations, chemical synthesis, and materials characterization by X-ray and neutron scattering techniques, this project investigated the phase behaviors of new classes of aqueous lyotropic liquid crystals (LLCs) and the properties of water nanoconfined within their pores. A portion of our studies focused on the synthesis of new classes of alkylsulfonic acid and alkylphosphonate amphiphiles, which were shown to undergo water-induced self-assembly to form a wide variety of nanostructured morphologies with unusually high degrees of long-range translational order observed by small- angle X-ray scattering (SAXS). Sample LLC morphologies that were observed include themore » lamellar (L!), tricontinuous double gyroid (G), hexagonally-packed cylinders (H), and low symmetry discontinuous micellar (I) Frank-Kasper phases. Since the G and H phases are the most promising for the development of selective ion transporting membranes for energy applications, we sought the characterize the structure and dynamics of water confined within the sub-3 nm pores of these LLCs using wide-angle neutron diffraction (WAND) and quasielastic neutron scattering (QENS) experiments performed at the Spallation Neutron Source at Oak Ridge National Laboratory. Using molecular dynamics (MD) simulations, we validated models for analyzing this QENS data to obtain water self-diffusion coefficients in LLC G and H phases of carboxylate and sulfonate surfactant LLCs as a function of the identities of their charge compensating counterions.« less

Cryo-protective effect of an ice-binding protein derived from Antarctic bacteria.

PubMed

Mangiagalli, Marco; Bar-Dolev, Maya; Tedesco, Pietro; Natalello, Antonino; Kaleda, Aleksei; Brocca, Stefania; de Pascale, Donatella; Pucciarelli, Sandra; Miceli, Cristina; Braslavsky, Ido; Lotti, Marina

2017-01-01

Cold environments are populated by organisms able to contravene deleterious effects of low temperature by diverse adaptive strategies, including the production of ice binding proteins (IBPs) that inhibit the growth of ice crystals inside and outside cells. We describe the properties of such a protein (EfcIBP) identified in the metagenome of an Antarctic biological consortium composed of the ciliate Euplotes focardii and psychrophilic non-cultured bacteria. Recombinant EfcIBP can resist freezing without any conformational damage and is moderately heat stable, with a midpoint temperature of 66.4 °C. Tested for its effects on ice, EfcIBP shows an unusual combination of properties not reported in other bacterial IBPs. First, it is one of the best-performing IBPs described to date in the inhibition of ice recrystallization, with effective concentrations in the nanomolar range. Moreover, EfcIBP has thermal hysteresis activity (0.53 °C at 50 μm) and it can stop a crystal from growing when held at a constant temperature within the thermal hysteresis gap. EfcIBP protects purified proteins and bacterial cells from freezing damage when exposed to challenging temperatures. EfcIBP also possesses a potential N-terminal signal sequence for protein transport and a DUF3494 domain that is common to secreted IBPs. These features lead us to hypothesize that the protein is either anchored at the outer cell surface or concentrated around cells to provide survival advantage to the whole cell consortium. © 2016 Federation of European Biochemical Societies.

Complex Role of Secondary Electron Emissions in Dust Grain Charging in Space Environments: Measurements on Apollo 11 and 17 Dust Grains

NASA Technical Reports Server (NTRS)

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

2010-01-01

Dust grains in various astrophysical environments are generally charged electrostatically by photoelectric emissions with radiation from nearby sources, or by electron/ion collisions by sticking or secondary electron emissions. Knowledge of the dust grain charges and equilibrium potentials is important for understanding of a variety of physical and dynamical processes in the interstellar medium (ISM), and heliospheric, interplanetary, planetary, and lunar environments. The high vacuum environment on the lunar surface leads to some unusual physical and dynamical phenomena involving dust grains with high adhesive characteristics, and levitation and transportation over long distances. It has been well recognized that the charging properties of individual micron/submicron size dust grains are expected to be substantially different from the corresponding values for bulk materials and theoretical models. In this paper we present experimental results on charging of individual dust grains selected from Apollo 11 and Apollo 17 dust samples by exposing them to mono-energetic electron beams in the 10- 400 eV energy range. The charging rates of positively and negatively charged particles of approximately 0.2 to 13 microns diameters are discussed in terms of the secondary electron emission (SEE) process, which is found to be a complex charging process at electron energies as low as 10-25 eV, with strong particle size dependence. The measurements indicate substantial differences between dust charging properties of individual small size dust grains and of bulk materials.

Wax layers on Cosmos bipinnatus petals contribute unequally to total petal water resistance.

PubMed

Buschhaus, Christopher; Hager, Dana; Jetter, Reinhard

2015-01-01

Cuticular waxes coat all primary aboveground plant organs as a crucial adaptation to life on land. Accordingly, the properties of waxes have been studied in much detail, albeit with a strong focus on leaf and fruit waxes. Flowers have life histories and functions largely different from those of other organs, and it remains to be seen whether flower waxes have compositions and physiological properties differing from those on other organs. This work provides a detailed characterization of the petal waxes, using Cosmos bipinnatus as a model, and compares them with leaf and stem waxes. The abaxial petal surface is relatively flat, whereas the adaxial side consists of conical epidermis cells, rendering it approximately 3.8 times larger than the projected petal area. The petal wax was found to contain unusually high concentrations of C(22) and C(24) fatty acids and primary alcohols, much shorter than those in leaf and stem waxes. Detailed analyses revealed distinct differences between waxes on the adaxial and abaxial petal sides and between epicuticular and intracuticular waxes. Transpiration resistances equaled 3 × 10(4) and 1.5 × 10(4) s m(-1) for the adaxial and abaxial surfaces, respectively. Petal surfaces of C. bipinnatus thus impose relatively weak water transport barriers compared with typical leaf cuticles. Approximately two-thirds of the abaxial surface water barrier was found to reside in the epicuticular wax layer of the petal and only one-third in the intracuticular wax. Altogether, the flower waxes of this species had properties greatly differing from those on vegetative organs. © 2015 American Society of Plant Biologists. All Rights Reserved.

Influence of disorder on the superconducting critical temperature in indium-opal nanocomposites

NASA Astrophysics Data System (ADS)

Zakharchuk, I.; Januzaj, A.; Mikhailin, N. Yu.; Traito, K. B.; Chernyaev, A. V.; Romanov, S. G.; Safonchik, M.; Shamshur, D. V.; Lähderanta, E.

2018-06-01

Transport properties of bulk indium-opal and indium-porous glass superconducting nanocomposites possessing moderate and strong disorder are investigated. A strongly nonmonotonous dependence of the global critical temperature Tc versus normal state conductivity of samples is found. The maximum, which is observed at moderate disorder, has Tc higher than that of clean bulk indium. The increasing part can be explained by the Eliashberg equations with disorder and an additional mechanism of interaction between superconducting and dielectric granules. The descending part of the maximum at higher disorder can be explained by the increasing of long-range Coulomb repulsion due to diffusion of charges. Negative slope in magnetic field dependence of resistivity and a peak in the temperature dependence of resistivity, observed in the sample near the proximity to the disorder-induced superconductor-insulator transition (SIT). A large difference between the onset temperature of superconducting fluctuations, Tcon , and global critical temperature Tc is found and considered in the framework of the weak multifractal theory. Slow time-logarithmic relaxation of the resistivity between Tc and Tcon is observed, which assumes existence of the precursor state near the SIT. This unusual state is discussed in the scope of the many-body localization theory.

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

NASA Astrophysics Data System (ADS)

Barati, Shahin; Abedinpour, Saeed H.

2017-10-01

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

Sound propagation in light-modulated carbon nanosponge suspensions

NASA Astrophysics Data System (ADS)

Zhou, W.; Tiwari, R. P.; Annamalai, R.; Sooryakumar, R.; Subramaniam, V.; Stroud, D.

2009-03-01

Single-walled carbon nanotube bundles dispersed in a highly polar fluid are found to agglomerate into a porous structure when exposed to low levels of laser radiation. The phototunable nanoscale porous structures provide an unusual way to control the acoustic properties of the suspension. Despite the high sound speed of the nanotubes, the measured speed of longitudinal-acoustic waves in the suspension decreases sharply with increasing bundle concentration. Two possible explanations for this reduction in sound speed are considered. One is simply that the sound speed decreases because of fluid heat induced by laser light absorption by the carbon nanotubes. The second is that this decrease results from the smaller sound velocity of fluid confined in a porous medium. Using a simplified description of convective heat transport, we estimate that the increase in temperature is too small to account for the observed decrease in sound velocity. To test the second possible explanation, we calculate the sound velocity in a porous medium, using a self-consistent effective-medium approximation. The results of this calculation agree qualitatively with experiment. In this case, the observed sound wave would be the analog of the slow compressional mode of porous solids at a structural length scale of order of 100 nm.

Superconducting quantum spin-Hall systems with giant orbital g-factors

NASA Astrophysics Data System (ADS)

Hankiewicz, Ewelina; Reinthaler, Rolf; Tkachov, Grigory

Topological aspects of superconductivity in quantum spin-Hall systems (QSHSs) such as thin layers of three-dimensional topological insulators (3D Tis) or two-dimensional Tis are in the focus of current research. Here, we describe a novel superconducting quantum spin-Hall effect (quantum spin Hall system in the proximity to the s-wave superconductor and in the orbital in-plane magnetic field), which is protected against elastic backscattering by combined time-reversal and particle-hole symmetry. This effect is characterized by spin-polarized edge states, which can be manipulated in weak magnetic fields due to a giant effective orbital g-factor, allowing the generation of spin currents. The phenomenon provides a novel solution to the outstanding challenge of detecting the spin-polarization of the edge states. Here we propose the detection of the edge polarization in the three-terminal junction using unusual transport properties of superconducting quantum Hall-effect: a non-monotonic excess current and a zero-bias conductance splitting. We thank for the financial support the German Science Foundation (DFG), Grants No HA 5893/4-1 within SPP 1666, HA5893/5-2 within FOR1162 and TK60/1-1 (G.T.), as well the ENB graduate school ``Topological insulators''.

A Route to Dirac Liquid Theory: A Fermi Liquid Description for Dirac Materials

NASA Astrophysics Data System (ADS)

Gochan, Matthew; Bedell, Kevin

Since the pioneering work developed by L.V. Landau sixty years ago, Fermi Liquid Theory has seen great success in describing interacting Fermi systems. While much interest has been generated over the study of non-Fermi Liquid systems, Fermi Liquid theory serves as a formidable model for many systems and offers a rich amount of of results and insight. The recent classification of Dirac Materials, and the lack of a unifying theoretical framework for them, has motivated our study. Dirac materials are a versatile class of materials in which an abundance of unique physical phenomena can be observed. Such materials are found in all dimensions, with the shared property that their low-energy fermionic excitations behave as massless Dirac fermions and are therefore governed by the Dirac equation. The most popular Dirac material, graphene, is the focus of this work. We present our Fermi Liquid description of Graphene. We find many interesting results, specifically in the transport and dynamics of the system. Additionally, we expand on previous work regarding the Virial Theorem and its impact on the Fermi Liquid parameters in graphene. Finally, we remark on viscoelasticity of Dirac Materials and other unusual results that are consequences of AdS-CFT.

Self-Assembled Formation of Well-Aligned Cu-Te Nano-Rods on Heavily Cu-Doped ZnTe Thin Films

NASA Astrophysics Data System (ADS)

Liang, Jing; Cheng, Man Kit; Lai, Ying Hoi; Wei, Guanglu; Yang, Sean Derman; Wang, Gan; Ho, Sut Kam; Tam, Kam Weng; Sou, Iam Keong

2016-11-01

Cu doping of ZnTe, which is an important semiconductor for various optoelectronic applications, has been successfully achieved previously by several techniques. However, besides its electrical transport characteristics, other physical and chemical properties of heavily Cu-doped ZnTe have not been reported. We found an interesting self-assembled formation of crystalline well-aligned Cu-Te nano-rods near the surface of heavily Cu-doped ZnTe thin films grown via the molecular beam epitaxy technique. A phenomenological growth model is presented based on the observed crystallographic morphology and measured chemical composition of the nano-rods using various imaging and chemical analysis techniques. When substitutional doping reaches its limit, the extra Cu atoms favor an up-migration toward the surface, leading to a one-dimensional surface modulation and formation of Cu-Te nano-rods, which explain unusual observations on the reflection high energy electron diffraction patterns and apparent resistivity of these thin films. This study provides an insight into some unexpected chemical reactions involved in the heavily Cu-doped ZnTe thin films, which may be applied to other material systems that contain a dopant having strong reactivity with the host matrix.

Thermoelectricity in correlated narrow-gap semiconductors

NASA Astrophysics Data System (ADS)

Tomczak, Jan M.

2018-05-01

We review many-body effects, their microscopic origin, as well as their impact on thermoelectricity in correlated narrow-gap semiconductors. Members of this class—such as FeSi and FeSb2—display an unusual temperature dependence in various observables: insulating with large thermopowers at low temperatures, they turn bad metals at temperatures much smaller than the size of their gaps. This insulator-to-metal crossover is accompanied by spectral weight-transfers over large energies in the optical conductivity and by a gradual transition from activated to Curie–Weiss-like behaviour in the magnetic susceptibility. We show a retrospective of the understanding of these phenomena, discuss the relation to heavy-fermion Kondo insulators—such as Ce3Bi4Pt3 for which we present new results—and propose a general classification of paramagnetic insulators. From the latter, FeSi emerges as an orbital-selective Kondo insulator. Focussing on intermetallics such as silicides, antimonides, skutterudites, and Heusler compounds we showcase successes and challenges for the realistic simulation of transport properties in the presence of electronic correlations. Further, we explore new avenues in which electronic correlations may contribute to the improvement of thermoelectric performance.

Unusual strategies for using indium gallium nitride grown on silicon (111) for solid-state lighting

PubMed Central

Kim, Hoon-sik; Brueckner, Eric; Song, Jizhou; Li, Yuhang; Kim, Seok; Lu, Chaofeng; Sulkin, Joshua; Choquette, Kent; Huang, Yonggang; Nuzzo, Ralph G.; Rogers, John A.

2011-01-01

Properties that can now be achieved with advanced, blue indium gallium nitride light emitting diodes (LEDs) lead to their potential as replacements for existing infrastructure in general illumination, with important implications for efficient use of energy. Further advances in this technology will benefit from reexamination of the modes for incorporating this materials technology into lighting modules that manage light conversion, extraction, and distribution, in ways that minimize adverse thermal effects associated with operation, with packages that exploit the unique aspects of these light sources. We present here ideas in anisotropic etching, microscale device assembly/integration, and module configuration that address these challenges in unconventional ways. Various device demonstrations provide examples of the capabilities, including thin, flexible lighting “tapes” based on patterned phosphors and large collections of small light emitters on plastic substrates. Quantitative modeling and experimental evaluation of heat flow in such structures illustrates one particular, important aspect of their operation: small, distributed LEDs can be passively cooled simply by direct thermal transport through thin-film metallization used for electrical interconnect, providing an enhanced and scalable means to integrate these devices in modules for white light generation. PMID:21666096

Unusual behaviour of (Np,Pu)B2C

NASA Astrophysics Data System (ADS)

Klimczuk, Tomasz; Boulet, Pascal; Griveau, Jean-Christophe; Colineau, Eric; Bauer, Ernst; Falmbigl, Matthias; Rogl, Peter; Wastin, Franck

2015-02-01

Two transuranium metal boron carbides, NpB2C and PuB2C have been synthesized by argon arc melting. The crystal structures of the {Np,Pu}B2C compounds were determined from single-crystal X-ray data to be isotypic with the ThB2C-type (space group ?, a = 0.6532(2) nm; c = 1.0769(3) nm for NpB2C and a = 0.6509(2) nm; c = 1.0818(3) nm for PuB2C; Z = 9). Physical properties have been derived from polycrystalline bulk material in the temperature range from 2 to 300 K and in magnetic fields up to 9 T. Magnetic susceptibility and heat capacity data indicate the occurrence of antiferromagnetic ordering for NpB2C with a Neel temperature TN = 68 K. PuB2C is a Pauli paramagnet most likely due to a strong hybridization of s(p,d) electrons with the Pu-5f states. A pseudo-gap, as concluded from the Sommerfeld value and the electronic transport, is thought to be a consequence of the hybridization. The magnetic behaviour of {Np,Pu}B2C is consistent with the criterion of Hill.

Elastic Properties of Orthoenstatite at Simultaneous High Pressure-Temperature Conditions and the Implication for the Origin of Low VP/VS Zones in the Mantle Wedge

NASA Astrophysics Data System (ADS)

Qian, W.; Wang, W.; Zou, F.; Wu, Z.

2017-12-01

The compositions of the Earth's interiors are critical in understanding the origin and evolution of the Earth and its geodynamics. Orthopyroxene is an important component for the upper mantle both in pyrolite model and in piclogite model. Furthermore, many evidences suggest the local enrichment of opx in the upper mantle. Therefore, its thermodynamic and elastic properties are fundamental for understanding of chemical compositions and dynamics of the upper mantle. We obtain the elastic properties of orthoenstatite (MgSiO3), Mg end-member orthopyroxene with space group Pbca, up to 20 GPa and 2000 K using first principles calculations with local density approximation (LDA). The calculated results are in good agreement with previous available experimental measurements and theoretical results. Both bulk and shear modulus show noticeable nonlinear pressure dependence, and the softening of shear wave velocities is prominent at high pressure. Meanwhile, orthoenstatite exhibits a negative temperature derivate of VP/VS ratios. This is different from other upper mantle minerals, such as olivine, ringwoodite and garnet, whose VP/VS increase with the increasing of the temperature. Compared to other major minerals in the upper mantle, orthoenstatite shows the lowest compressional velocities, shear velocities, and VP/VS (<1.7) ratio up to the depth of 200 km. Recently, many seismic studies have observed unusual low VP/VS (below 1.72) zones in subduction mantle wedge and orthopyroxene has been proposed to be a possible interpretation of this unusual observed. However, this explanation is still under debate because no experimental or calculated elastic data at the conditions of the upper mantle are available before. Our calculations show that VS and VP/VS ratio of orthoenstatite under the mantle wedge conditions (2-3 GPa and 1073-1723 K) are consistent of the unusual seismic observations of VP/VS in subduction mantle wedge. Therefore, the enrichment of orthopyroxene may potentially account for the observed low VP/VS in the mantle wedge.

Comparing contribution of flexural and planar modes to thermodynamic properties

NASA Astrophysics Data System (ADS)

Mann, Sarita; Rani, Pooja; Jindal, V. K.

2017-05-01

Graphene, the most studied and explored 2D structure has unusual thermal properties such as negative thermal expansion, high thermal conductivity etc. We have already studied the thermal expansion behavior and various thermodynamic properties of pure graphene like heat capacity, entropy and free energy. The results of thermal expansion and various thermodynamic properties match well with available theoretical studies. For a deeper understanding of these properties, we analyzed the contribution of each phonon branch towards the total value of the individual property. To compute these properties, the dynamical matrix was calculated using VASP code where the density functional perturbation theory (DFPT) is employed under quasi-harmonic approximation in interface with phonopy code. It is noticed that transverse mode has major contribution to negative thermal expansion and all branches have almost same contribution towards the various thermodynamic properties with the contribution of ZA mode being the highest.

Wave-packet approach to transport properties of carrier coupled with intermolecular and intramolecular vibrations of organic semiconductors

NASA Astrophysics Data System (ADS)

Ishii, Hiroyuki; Honma, Keisuke; Kobayashi, Nobuhiko; Hirose, Kenji

2012-06-01

We present a methodology to study the charge-transport properties of organic semiconductors by the time-dependent wave-packet diffusion method, taking the polaron effects into account. As an example, we investigate the transport properties of single-crystal pentacene organic semiconductors coupled with inter- and intramolecular vibrations within the mixed Holstein and Peierls model, which describes both hopping and bandlike transport behaviors due to small and large polaron formations. Taking into account static disorders, which inevitably exist in the molecular crystals, we present the temperature dependence of charge-transport properties in competition among the thermal fluctuation of molecular motions, the polaron formation, and the static disorders.

The role of macromolecular crowding in the evolution of lens crystallins with high molecular refractive index.

PubMed

Zhao, Huaying; Magone, M Teresa; Schuck, Peter

2011-08-01

Crystallins are present in the lens at extremely high concentrations in order to provide transparency and generate a high refractive power of the lens. The crystallin families prevalent in the highest density lens tissues are γ-crystallins in vertebrates and S-crystallins in cephalopods. As shown elsewhere, in parallel evolution, both have evolved molecular refractive index increments 5-10% above those of most proteins. Although this is a small increase, it is statistically very significant and can be achieved only by very unusual amino acid compositions. In contrast, such a molecular adaptation to aid in the refractive function of the lens did not occur in crystallins that are preferentially located in lower density lens tissues, such as vertebrate α-crystallin and taxon-specific crystallins. In the current work, we apply a model of non-interacting hard spheres to examine the thermodynamic contributions of volume exclusion at lenticular protein concentrations. We show that the small concentration decrease afforded by the higher molecular refractive index increment of crystallins can amplify nonlinearly to produce order of magnitude differences in chemical activities, and lead to reduced osmotic pressure and the reduced propensity for protein aggregation. Quantitatively, this amplification sets in only at protein concentrations as high as those found in hard lenses or the nucleus of soft lenses, in good correspondence to the observed crystallin properties in different tissues and different species. This suggests that volume exclusion effects provide the evolutionary driving force for the unusual refractive properties and the unusual amino acid compositions of γ-crystallins and S-crystallins.

The role of macromolecular crowding in the evolution of lens crystallins with high molecular refractive index

PubMed Central

Zhao, Huaying; Magone, M. Teresa; Schuck, Peter

2011-01-01

Crystallins are present in the lens at extremely high concentrations in order to provide transparency and generate a high refractive power of the lens. The crystallin families prevalent in the highest density lens tissues are γ crystallins in vertebrates and S crystallins in cephalopods. In parallel evolution, both have evolved molecular refractive index increments 5 – 10 % above those of most proteins. Although this is a small increase, it is statistically very significant and can be achieved only by very unusual amino acid compositions. In contrast, such a molecular adaptation to aid in the refractive function of the lens did not occur in crystallins that are preferentially located in lower density lens tissues, such as vertebrate α crystallin and taxon specific crystallins. In the current work, we apply a model of non-interacting hard spheres to examine the thermodynamic contributions of volume exclusion at lenticular protein concentrations. We show that the small concentration decrease afforded by the higher molecular refractive index increment of crystallins can amplify nonlinearly to produce order of magnitude differences in chemical activities, and lead to reduced osmotic pressure and the reduced propensity for protein aggregation. Quantitatively, this amplification sets in only at protein concentrations as high as those found in hard lenses or the nucleus of soft lenses, in good correspondence to the observed crystalline properties in different tissues and different species. This suggests that volume exclusion effects provide the evolutionary driving force for the unusual refractive properties and the unusual amino acid compositions of γ crystallins and S crystallins. PMID:21566271

New trends in chemistry and materials science in extremely tight space

DOE PAGES

Song, Yang; Manaa, M. Riad

2012-01-26

Pressure plays a critical role in regulating the structures and properties of materials. Since Percy Bridgeman was recognized by the 1946 Nobel Prize in Physics for his contribution in high-pressure physics, high-pressure research has remained an interdisciplinary scientific frontier with many extraordinary breakthroughs. Over the past decade or so, in particular, high-pressure chemistry and materials research has undergone major advances with the discovery of numerous exotic structures and properties. Furthermore, brand new classes of inorganic materials of unusual stoichiometries and crystal structures, which have a wide range of optical, mechanical, electronic and magnetic properties, have been produced at high pressures.

New trends in chemistry and materials science in extremely tight space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Yang; Manaa, M. Riad

Pressure plays a critical role in regulating the structures and properties of materials. Since Percy Bridgeman was recognized by the 1946 Nobel Prize in Physics for his contribution in high-pressure physics, high-pressure research has remained an interdisciplinary scientific frontier with many extraordinary breakthroughs. Over the past decade or so, in particular, high-pressure chemistry and materials research has undergone major advances with the discovery of numerous exotic structures and properties. Furthermore, brand new classes of inorganic materials of unusual stoichiometries and crystal structures, which have a wide range of optical, mechanical, electronic and magnetic properties, have been produced at high pressures.

Electrical and Thermal Transport Property Studies of High-Temperature Thermoelectric Materials.

DTIC Science & Technology

1985-06-01

THERMAL TRANSPORT PROPERTY STUDIES OF HIGH-TEMPERATURE THERMOELECTRIC MATERIALS: INTERIM TECHNICAL REPORT FOR THE PERIOD MAY 15, 1984 TO MAY 15, 1985 J. L...transport property data base has been expanded oy continued measurements in several systems under study, and a theoretical model for thermoelectric ...6.0 REFERENCES . . . . . . . . . . . . 6.1 APPENDIX A - THERMOELECTRIC PROPERTY DATA . . . . . . . A. I 1l FIGURES 3.1 Dimensionless Figure of Merit

41 CFR 109-40.103-1 - Domestic transportation.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 41 Public Contracts and Property Management 3 2013-07-01 2013-07-01 false Domestic transportation... Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS AVIATION, TRANSPORTATION, AND MOTOR VEHICLES 40-TRANSPORTATION AND TRAFFIC MANAGEMENT 40.1-General Provision § 109-40.103-1...

41 CFR 109-40.103-1 - Domestic transportation.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 41 Public Contracts and Property Management 3 2012-01-01 2012-01-01 false Domestic transportation... Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS AVIATION, TRANSPORTATION, AND MOTOR VEHICLES 40-TRANSPORTATION AND TRAFFIC MANAGEMENT 40.1-General Provision § 109-40.103-1...

41 CFR 109-40.103-1 - Domestic transportation.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 41 Public Contracts and Property Management 3 2014-01-01 2014-01-01 false Domestic transportation... Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS AVIATION, TRANSPORTATION, AND MOTOR VEHICLES 40-TRANSPORTATION AND TRAFFIC MANAGEMENT 40.1-General Provision § 109-40.103-1...

41 CFR 109-40.103-1 - Domestic transportation.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false Domestic transportation... Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS AVIATION, TRANSPORTATION, AND MOTOR VEHICLES 40-TRANSPORTATION AND TRAFFIC MANAGEMENT 40.1-General Provision § 109-40.103-1...

41 CFR 102-117.120 - To what extent must I equally distribute orders for transportation and related services among TSPs?

Code of Federal Regulations, 2010 CFR

2010-07-01

....120 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 117-TRANSPORTATION MANAGEMENT Business Rules To Consider... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false To what extent must I...

The Transport Properties of Activated Carbon Fibers

DOE R&D Accomplishments Database

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.

41 CFR 102-118.455 - What is the time limit for a TSP to file a transportation claim against my agency?

Code of Federal Regulations, 2010 CFR

2010-07-01

... Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT Claims and Appeal Procedures... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What is the time limit...

41 CFR 102-118.450 - Can a TSP file a transportation claim against my agency?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Can a TSP file a transportation claim against my agency? 102-118.450 Section 102-118.450 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION...

41 CFR 102-117.85 - What is the difference between a Government bill of lading (GBL) and a bill of lading?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What is the difference... Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 117-TRANSPORTATION MANAGEMENT Acquiring Transportation or Related...

41 CFR 109-40.103-3 - International transportation.

Code of Federal Regulations, 2014 CFR

2014-01-01

... transportation. 109-40.103-3 Section 109-40.103-3 Public Contracts and Property Management Federal Property..., TRANSPORTATION, AND MOTOR VEHICLES 40-TRANSPORTATION AND TRAFFIC MANAGEMENT 40.1-General Provision § 109-40.103-3 International transportation. See 4 CFR 52.2 for a certificate required in nonuse of U.S. flag vessels or U.S...

49 CFR 19.32 - Real property.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 1 2010-10-01 2010-10-01 false Real property. 19.32 Section 19.32 Transportation... Requirements Property Standards § 19.32 Real property. Each Federal awarding agency shall prescribe requirements for recipients concerning the use and disposition of real property acquired in whole or in part...

49 CFR 19.32 - Real property.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 1 2011-10-01 2011-10-01 false Real property. 19.32 Section 19.32 Transportation... Requirements Property Standards § 19.32 Real property. Each Federal awarding agency shall prescribe requirements for recipients concerning the use and disposition of real property acquired in whole or in part...

49 CFR 19.32 - Real property.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 1 2012-10-01 2012-10-01 false Real property. 19.32 Section 19.32 Transportation... Requirements Property Standards § 19.32 Real property. Each Federal awarding agency shall prescribe requirements for recipients concerning the use and disposition of real property acquired in whole or in part...

49 CFR 19.32 - Real property.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 1 2013-10-01 2013-10-01 false Real property. 19.32 Section 19.32 Transportation... Requirements Property Standards § 19.32 Real property. Each Federal awarding agency shall prescribe requirements for recipients concerning the use and disposition of real property acquired in whole or in part...

49 CFR 19.32 - Real property.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 1 2014-10-01 2014-10-01 false Real property. 19.32 Section 19.32 Transportation... Requirements Property Standards § 19.32 Real property. Each Federal awarding agency shall prescribe requirements for recipients concerning the use and disposition of real property acquired in whole or in part...

Electronic transport properties of 4f shell elements of liquid metal using hard sphere Yukawa system

NASA Astrophysics Data System (ADS)

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

2018-04-01

The electronic transport properties are analyzed for 4f shell elements of liquid metals. To examine the electronic transport properties like electrical resistivity (ρ), thermal conductivity (σ) and thermo electrical power (Q), we used our own parameter free model potential with the Hard Sphere Yukawa (HSY) reference system. The screening effect on aforesaid properties has been examined by using different screening functions like Hartree (H), Taylor (T) and Sarkar (S). The correlations of our resultsand other data with available experimental values are intensely promising. Also, we conclude that our newly constructed parameter free model potential is capable of explaining the above mentioned electronic transport properties.

ms2: A molecular simulation tool for thermodynamic properties

NASA Astrophysics Data System (ADS)

Deublein, Stephan; Eckl, Bernhard; Stoll, Jürgen; Lishchuk, Sergey V.; Guevara-Carrion, Gabriela; Glass, Colin W.; Merker, Thorsten; Bernreuther, Martin; Hasse, Hans; Vrabec, Jadran

2011-11-01

This work presents the molecular simulation program ms2 that is designed for the calculation of thermodynamic properties of bulk fluids in equilibrium consisting of small electro-neutral molecules. ms2 features the two main molecular simulation techniques, molecular dynamics (MD) and Monte-Carlo. It supports the calculation of vapor-liquid equilibria of pure fluids and multi-component mixtures described by rigid molecular models on the basis of the grand equilibrium method. Furthermore, it is capable of sampling various classical ensembles and yields numerous thermodynamic properties. To evaluate the chemical potential, Widom's test molecule method and gradual insertion are implemented. Transport properties are determined by equilibrium MD simulations following the Green-Kubo formalism. ms2 is designed to meet the requirements of academia and industry, particularly achieving short response times and straightforward handling. It is written in Fortran90 and optimized for a fast execution on a broad range of computer architectures, spanning from single processor PCs over PC-clusters and vector computers to high-end parallel machines. The standard Message Passing Interface (MPI) is used for parallelization and ms2 is therefore easily portable to different computing platforms. Feature tools facilitate the interaction with the code and the interpretation of input and output files. The accuracy and reliability of ms2 has been shown for a large variety of fluids in preceding work. Program summaryProgram title:ms2 Catalogue identifier: AEJF_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJF_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Special Licence supplied by the authors No. of lines in distributed program, including test data, etc.: 82 794 No. of bytes in distributed program, including test data, etc.: 793 705 Distribution format: tar.gz Programming language: Fortran90 Computer: The simulation tool ms2 is usable on a wide variety of platforms, from single processor machines over PC-clusters and vector computers to vector-parallel architectures. (Tested with Fortran compilers: gfortran, Intel, PathScale, Portland Group and Sun Studio.) Operating system: Unix/Linux, Windows Has the code been vectorized or parallelized?: Yes. Message Passing Interface (MPI) protocol Scalability. Excellent scalability up to 16 processors for molecular dynamics and >512 processors for Monte-Carlo simulations. RAM:ms2 runs on single processors with 512 MB RAM. The memory demand rises with increasing number of processors used per node and increasing number of molecules. Classification: 7.7, 7.9, 12 External routines: Message Passing Interface (MPI) Nature of problem: Calculation of application oriented thermodynamic properties for rigid electro-neutral molecules: vapor-liquid equilibria, thermal and caloric data as well as transport properties of pure fluids and multi-component mixtures. Solution method: Molecular dynamics, Monte-Carlo, various classical ensembles, grand equilibrium method, Green-Kubo formalism. Restrictions: No. The system size is user-defined. Typical problems addressed by ms2 can be solved by simulating systems containing typically 2000 molecules or less. Unusual features: Feature tools are available for creating input files, analyzing simulation results and visualizing molecular trajectories. Additional comments: Sample makefiles for multiple operation platforms are provided. Documentation is provided with the installation package and is available at http://www.ms-2.de. Running time: The running time of ms2 depends on the problem set, the system size and the number of processes used in the simulation. Running four processes on a "Nehalem" processor, simulations calculating VLE data take between two and twelve hours, calculating transport properties between six and 24 hours.

41 CFR 101-42.405 - Transportation of hazardous materials.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Transportation of... Destruction of Surplus Hazardous Materials and Certain Categories of Property § 101-42.405 Transportation of hazardous materials. The transportation of hazardous materials is governed by the hazardous materials...

41 CFR 101-42.405 - Transportation of hazardous materials.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 41 Public Contracts and Property Management 2 2014-07-01 2012-07-01 true Transportation of... Destruction of Surplus Hazardous Materials and Certain Categories of Property § 101-42.405 Transportation of hazardous materials. The transportation of hazardous materials is governed by the hazardous materials...

41 CFR 101-42.405 - Transportation of hazardous materials.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 41 Public Contracts and Property Management 2 2011-07-01 2007-07-01 true Transportation of... Destruction of Surplus Hazardous Materials and Certain Categories of Property § 101-42.405 Transportation of hazardous materials. The transportation of hazardous materials is governed by the hazardous materials...

An ab initio electronic transport database for inorganic materials.

PubMed

Ricci, Francesco; Chen, Wei; Aydemir, Umut; Snyder, G Jeffrey; Rignanese, Gian-Marco; Jain, Anubhav; Hautier, Geoffroy

2017-07-04

Electronic transport in materials is governed by a series of tensorial properties such as conductivity, Seebeck coefficient, and effective mass. These quantities are paramount to the understanding of materials in many fields from thermoelectrics to electronics and photovoltaics. Transport properties can be calculated from a material's band structure using the Boltzmann transport theory framework. We present here the largest computational database of electronic transport properties based on a large set of 48,000 materials originating from the Materials Project database. Our results were obtained through the interpolation approach developed in the BoltzTraP software, assuming a constant relaxation time. We present the workflow to generate the data, the data validation procedure, and the database structure. Our aim is to target the large community of scientists developing materials selection strategies and performing studies involving transport properties.

Extraordinary trace-element accumulations in roadside cedars near Centerville, Missouri

DOE Office of Scientific and Technical Information (OSTI.GOV)

Connor, J.J.; Shacklette, H.T.; Erdman, J.A.

1971-01-01

Unusually high concentrations of lead, copper, zinc, and cadmium were found in samples of cedar (Juniperus virginiana L.) collected on the roadside of State Highway 21-72 about 4 miles northeast of Centerville, Mo. For 15 samples, geometric mean concentrations for these elements in cedar ash were, in parts per million: Pb, 5,800; Cu, 190; An, 940; and Cd, 12. The high concentrations are thought to reflect vehicular transport of lead-bearing ores from mine to smelter, rather than mineralized rock at depth.

An unusual photosensitizer: dyad of eosin-tris(2,2'-bipyridine)Ru(II).

PubMed

Jing, Bingwen; Zhang, Manhua; Shen, Tao

2003-10-02

[structure: see text] A dyad of eosin and tris(2,2'-bipyridine)Ru(II) was prepared, and its photophysical properties were investigated. The photosensitization of eosin is greatly enhanced by introduction of tris(2,2'-bipyridine)Ru(II), which is verified via photooxygenation of anthracene derivatives. The electron-transfer mechanism of photosensitization is also discussed.

Definite Markers, Phi-Features, and Agreement: A Morphosyntactic Investigation of the Amharic DP

ERIC Educational Resources Information Center

Kramer, Ruth

2009-01-01

This dissertation has two inter-related goals: (i) to describe and provide novel analyses of three types of important and difficult phenomena within Amharic DPs and (ii) to explore the properties of the syntax-morphology interface. The core phenomena explicated are the unusual distribution of the definite marker, the gender system (which relies…

The laser lightning rod system: thunderstorm domestication.

PubMed

Ball, L M

1974-10-01

An unusual application of the laser, namely protection of life and property from lightning, is described. The device relies on multiphoton ionization in mode-locked beams, rather than on collisional (avalanche) electron production. Feasibility is demonstrated numerically, and relevant principles explained. A method of mobile deployment is mentioned, by which economic (as opposed to scientific) feasibility might be achieved.

Model-Driven Study of Visual Memory

DTIC Science & Technology

2004-12-01

dimensional stimuli (synthetic human faces ) afford important insights into episodic recognition memory. The results were well accommodated by a summed...the unusual properties of the z-transformed ROCS. 15. SUBJECT TERMS Memory, visual memory, computational model, human memory, faces , identity 16...3 Accomplishments/New Findings 3 Work on Objective One: Recognition Memory for Synthetic Faces . 3 Experim ent 1

46 CFR 90.05-1 - Vessels subject to requirements of this subchapter.

Code of Federal Regulations, 2010 CFR

2010-10-01

...(a) and to all such foreign-flag vessels which carry 12 or fewer passengers from any port in the... operation involves potential unusual risks shall be subject to inspection to the extent necessary to safeguard life and property in United States ports, as further provided by § 2.01-13 of subchapter A...

46 CFR 50.05-15 - Vessels subject to regulations in this subchapter.

Code of Federal Regulations, 2010 CFR

2010-10-01

... from any port in the United States except as follows: (1) Any vessel of a foreign nation signatory to... involves potential unusual risks shall be subject to inspection to the extent necessary to safeguard life and property in U.S. ports, as further provided by § 2.01-13 in subchapter A (Procedures Applicable to...

The Psychometric Properties of a New Measure of Sensory Behaviors in Autistic Children

ERIC Educational Resources Information Center

Neil, Louise; Green, Dido; Pellicano, Elizabeth

2017-01-01

Unusual reactions to sensory input became part of the diagnostic criteria for autism spectrum disorder in the DSM-5. Measures accurately assessing these symptoms are important for clinical decisions. This study examined the reliability and validity of the Sensory Behavior Questionnaire, a parent-report scale designed to assess frequency and impact…

Phytochemical study of Helichrysum italicum (Roth) G. Don: Spectroscopic elucidation of unusual amino-phlorogucinols and antimicrobial assessment of secondary metabolites from medium-polar extract.

PubMed

D'Abrosca, Brigida; Buommino, Elisabetta; Caputo, Pina; Scognamiglio, Monica; Chambery, Angela; Donnarumma, Giovanna; Fiorentino, Antonio

2016-12-01

Three unusual amino-phloroglucinols, named helichrytalicines A-C, along with seventeen known compounds including acetophenones, tremetrone derivatives, low-molecular weight phenols, flavonol glucosides, have been isolated from the medium-polar extract of Helichrysum italicum (Roth) G. Don, a medicinal plant typical of the Mediterranean vegetation. The structures of the compounds have been elucidated based on extensive 2D-NMR spectroscopic analyses, including COSY, TOCSY, HSQC, CIGAR-HMBC, H2BC and HSQC-TOCSY, along with Q-TOF HRMS 2 analysis. Stereostructure of the new compounds has been elucidated by Mosher's method and NOESY experiment. Antimicrobial properties against Staphylococcus epidermidis of selected compounds have been evaluated. Copyright © 2016 Elsevier Ltd. All rights reserved.

Crystal structure of guanidinium hexafluoridovanadate(III), (CN3H6)3[VF6]: an unusual hybrid compound related to perovskite.

PubMed

Black, Cameron; Lightfoot, Philip

2017-03-01

Vanadium fluorides with novel crystal-chemical features and interesting physical properties can be prepared by solvothermal synthetic routes. The title compound, guanidinium hexafluoridovanadate(III), has a cubic structure (space group Pa-3), exhibiting isolated regular VF 6 octahedral units, which are hydrogen bonded to protonated guanidinium moieties. Although the VF 6 octahedral units are not linked directly together, there are structural similarities between this crystal structure and those of the wider family of perovskite materials, in particular, hybrid perovskites based on extended ligands such as cyanide. In this context, the octahedral tilt system of the present compound is of interest and demonstrates that unusual tilt systems can be mediated via `molecular' linkers which allow only supramolecular rather than covalent interactions.

Interesting properties of ferroelectric Pb(Zr0.5Ti0.5)O3 nanotube array embedded in matrix medium

NASA Astrophysics Data System (ADS)

Adhikari, Rajendra; Fu, Huaxiang

2013-07-01

Finite-temperature first-principles based simulations are used to determine the structural and polarization properties of ferroelectric Pb(Zr0.5Ti0.5)O3 (PZT) nanotube array embedded in matrix medium of different ferroelectric strengths. Various interesting properties are found, including (i) that the system can behave either 3D-like, or 2D-like, or 1D-like; and (ii) the existence of an unusual structural phase in which 180° stripe domain coexists with vortex. Furthermore, we show in PZT tube array that a vortex phase can spontaneously transform into a ferroelectric phase of polarization by temperature alone, without applying external electric fields. Microscopic insights for understanding these properties are provided.

Properties and actions of bridged diphenyl acaricides.

PubMed Central

March, R B

1976-01-01

The properties and actions of the bridged diphenyl acaricides are discussed. These pesticides, which are more or less structurally related to DDT, were the first of the specific acaricides to be developed. They exhibit remarkable properties of specificity, being primarily toxic to phytophagous mites but of very low toxicity to most nontarget species, including insects, fish, birds, and mammals. Although many important facets of their broad mode of action are understood, virtually nothing is known of their primary mode of action or the underlying bases of their specificities. In most ways they are model compounds for integrated control and pest management activities and thus merit greater attention than they have received to elucidate the fundamentals underlying their unusual properties and actions. PMID:789071

41 CFR 102-118.430 - What information must be on my agency's transportation bills submitted for a postpayment audit?

Code of Federal Regulations, 2010 CFR

2010-07-01

... on my agency's transportation bills submitted for a postpayment audit? 102-118.430 Section 102-118.430 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT Postpayment...

41 CFR 102-118.320 - What information must be on transportation bills that have completed my agency's prepayment audit?

Code of Federal Regulations, 2010 CFR

2010-07-01

... on transportation bills that have completed my agency's prepayment audit? 102-118.320 Section 102-118.320 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT Prepayment Audits of...

Teaching the Role of Mitochondrial Transport in Energy Metabolism

ERIC Educational Resources Information Center

Passarella, Salvatore; Atlante, Anna

2007-01-01

Studies from our laboratories over recent years have uncovered the existence, and established the properties of a variety of mitochondrial transporters. The properties of these transporters throw light on a variety of biochemical phenomena that were previously poorly understood. In particular the role of mitochondrial transport in energy…

Structural properties and magic structures in hydrogenated finite and infinite silicon nanowires

NASA Astrophysics Data System (ADS)

Zdetsis, A. D.; Koukaras, E. N.; Garoufalis, C. S.

2007-11-01

Unusual effects such as bending and "canting," related with the stability, have been identified by ab initio real-space calculations for hydrogenated silicon nanowires. We have examined in detail the electronic and structural properties of finite and infinite nanowires as a function of length (and width) and have developed stability and bending rules, demonstrating that "magic" wires do not bend. Reconstructed 2×1 nanowires are practically as stable as the magic ones. Our calculations are in good agreement with the experimental data of Ma et al. [Science 299, 1874 (2003).].

Molecules with enhanced electronic polarizabilities based on defect-like states in conjugated polymers

NASA Technical Reports Server (NTRS)

Beratan, David N. (Inventor)

1991-01-01

Highly conjugated organic polymers typically have large non-resonant electronic susceptibilities, which give the molecules unusual optical properties. To enhance these properties, defects are introduced into the polymer chain. Examples include light doping of the conjugated polymer and synthesis, conjugated polymers which incorporate either electron donating or accepting groups, and conjugated polymers which contain a photoexcitable species capable of reversibly transferring its electron to an acceptor. Such defects in the chain permit enhancement of the second hyperpolarizability by at least an order of magnitude.

Processing and property evaluation of metal matrix superconducting materials

NASA Technical Reports Server (NTRS)

Rao, Appajosula S.

1995-01-01

Metal - superconductor (YBCO) systems have been prepared and characterized by resistivity, ac susceptibility and dc SQUID magnetic moment measurements. The silver composites showed superconducting transition for all the composites processed and the superconducting transition temperature tends to depend upon the concentration of the silver in the composite. Aluminum composites showed an unusual resistivity results with two transitions around 90 K and 120 K. The superconducting property of silver composites can be explained qualitatively in terms of the proximity theory that has been suggested for the low temperature superconductors.

Dancing partners at the synapse: auxiliary subunits that shape kainate receptor function

PubMed Central

Copits, Bryan A.; Swanson, Geoffrey T.

2012-01-01

Kainate receptors are a family of ionotropic glutamate receptors whose physiological roles differ from those of other subtypes of glutamate receptors in that they predominantly serve as modulators, rather than mediators, of synaptic transmission. Neuronal kainate receptors exhibit unusually slow kinetic properties that have been difficult to reconcile with the behaviour of recombinant kainate receptors. Recently, however, the neuropilin and tolloid-like 1 (NETO1) and NETO2 proteins were identified as auxiliary kainate receptor subunits that shape both the biophysical properties and synaptic localization of these receptors. PMID:22948074

Electrical Resistivity Measurements: a Review

NASA Astrophysics Data System (ADS)

Singh, Yadunath

World-wide interest on the use of ceramic materials for aerospace and other advanced engineering applications, has led to the need for inspection techniques capable of detecting unusually electrical and thermal anomalies in these compounds. Modern ceramic materials offer many attractive physical, electrical and mechanical properties for a wide and rapidly growing range of industrial applications; moreover specific use may be made of their electrical resistance, chemical resistance, and thermal barrier properties. In this review, we report the development and various techniques for the resistivity measurement of solid kind of samples.

Suspended sediments of the modern Amazon and Orinoco rivers

USGS Publications Warehouse

Meade, R.H.

1994-01-01

The Amazon and Orinoco Rivers are massive transcontinental conveyance systems for suspended sediment. They derive about 90% of their sediment from the Andes that support their western headwaters, transport it for thousands of kilometers across the breadth of the continent and deposit it in the coastal zones of the Atlantic. At their points of maximum suspended-sediment discharge, the Amazon transports an average of 1100-1300 ?? 106 tons per year and the Orinoco transports about 150 ?? 106 tons per year. Relations of sediment discharge to water discharge are complicated by unusual patterns of seasonal storage and remobilization, increased storage and reduced transport of sediment in the middle Orinoco during periods of peak water discharge, and storage of suspended sediment in the lower Amazon during rising discharge and resuspension during falling discharge. Spatial distributions of suspended sediment in cross-sections of both rivers are typically heterogeneous, not only in the vertical sense but also in the lateral. The cross-channel mixing of tributary inputs into the mainstem waters is a slow process that requires several hundred kilometers of downriver transport to complete. Considerable fine-grained sediment is exchanged between rivers and floodplains by the combination of overbank deposition and bank erosion. ?? 1994.

Magnolia Waco Properties, LLC Residential Property Renovation Rule Settlement Information Sheet

EPA Pesticide Factsheets

MarkWest is engaged in the gathering, transportation, and processing of natural gas, the transportation, fractionation, marketing, and storage of natural gas liquids, and the gathering and transportation of crude oil.

The Unusual Minimum of Cycle 23: Observations and Interpretation

NASA Astrophysics Data System (ADS)

Martens, Petrus C.; Nandy, D.; Munoz-Jaramillo, A.

2009-05-01

The current minimum of cycle 23 is unusual in its long duration, the very low level to which Total Solar Irradiance (TSI) has fallen, and the small flux of the open polar fields. The deep minimum of TSI seems to be related to an unprecedented dearth of polar faculae, and hence to the small amount of open flux. Based upon surface flux transport models it has been suggested that the causes of these phenomena may be an unusually vigorous meridional flow, or even a deviation from Joy's law resulting in smaller Joy angles than usual for emerging flux in cycle 23. There is also the possibility of a connection with the recently inferred emergence in polar regions of bipoles that systematically defy Hale's law. Much speculation has been going on as to the consequences of this exceptional minimum: are we entering another global minimum, is this the end of the 80 year period of exceptionally high solar activity, or is this just a statistical hiccup? Dynamo simulations are underway that may help answer this question. As an aside it must be mentioned that the current minimum of TSI puts an upper limit in the TSI input for global climate simulations during the Maunder minimum, and that a possible decrease in future solar activity will result in a very small but not insignificant reduction in the pace of global warming.

Simulator study of flight characteristics of a large twin-fuselage cargo transport airplane during approach and landing

NASA Technical Reports Server (NTRS)

Grantham, W. D.; Deal, P. L.; Keyser, G. L., Jr.; Smith, P. M.

1983-01-01

A six degree-of-freedom, ground-based simulator study was conducted to evaluate the low speed flight characteristics of a twin fuselage cargo transport airplane and to compare these characteristics with those of a large, single fuselage (reference) transport configuration which was similar to the Lockheed C-5C airplane. The primary piloting task was the approach and landing. The results indicated that in order to achieve "acceptable' low speed handling qualities on the twin fuselage concept, considerable stability and control augmentation was required, and although the augmented airplane could be landed safely under adverse conditions, the roll performance of the aircraft had to be improved appreciably before the handling qualities were rated as being "satisfactory.' These ground-based simulation results indicated that a value of t sub phi = 30 (time required to bank 30 deg) less than 6 sec should result in "acceptable' roll response characteristics, and when t sub phi = 30 is less than 3.8 sec, "satisfactory' roll response should be attainable on such large and unusually configured aircraft as the subject twin fuselage cargo transport concept.

Effects of a television drama about environmental exposure to toxic substances.

PubMed

Kennedy, May G; Turf, Elizabeth Eustis; Wilson-Genderson, Maureen; Wells, Kristen; Huang, Grace C; Beck, Vicki

2011-01-01

This study assessed short-term outcomes of viewing an episode of a prime-time television drama in which a child developed cancer after environmental exposure to an illegal pesticide. The study explored the effects among viewers of feeling transported into a narrative world. Respondents (n = 2,139) to a post-episode Internet panel survey were asked if they had seen the show and asked questions about their demographic information, their frequency of viewing the television show, the degree to which they had felt transported into a narrative world created by the drama, and their knowledge and beliefs about the health effects of environmental exposure. Conversations with key informants from federal agencies and advocacy groups were also held. Episode viewing and narrative transportation were positively associated with knowledge of toxic exposure effects, and transported viewers reported being more likely to report an unusually high number of cancer cases to authorities. The show also appeared to have prompted a clarification of federal pesticide-testing policy. Entertainment Education is a promising strategy for disseminating key points of information about environmental health.

Effects of a Television Drama about Environmental Exposure to Toxic Substances

PubMed Central

Kennedy, May G.; Eustis Turf, Elizabeth; Wilson-Genderson, Maureen; Wells, Kristen; Huang, Grace C.; Beck, Vicki

2011-01-01

Objective. This study assessed short-term outcomes of viewing an episode of a prime-time television drama in which a child developed cancer after environmental exposure to an illegal pesticide. The study explored the effects among viewers of feeling transported into a narrative world. Methods. Respondents (n=2,139) to a post-episode Internet panel survey were asked if they had seen the show and asked questions about their demographic information, their frequency of viewing the television show, the degree to which they had felt transported into a narrative world created by the drama, and their knowledge and beliefs about the health effects of environmental exposure. Conversations with key informants from federal agencies and advocacy groups were also held. Results. Episode viewing and narrative transportation were positively associated with knowledge of toxic exposure effects, and transported viewers reported being more likely to report an unusually high number of cancer cases to authorities. The show also appeared to have prompted a clarification of federal pesticide-testing policy. Conclusions. Entertainment Education is a promising strategy for disseminating key points of information about environmental health. PMID:21563723

Sediment transport by fishes in Harrington Sound, Bermuda

NASA Astrophysics Data System (ADS)

Alheit, Jürgen

1983-11-01

Harrington Sound, Bermuda, is a shallow subtropical lagoon with carbonate sediments. The most important fishes in this lagoon, in terms of biomass, are grunts (Haemulon aurolineatum, H. flavolineatum, H. sciurus) and a sea-bream (Diplodus bermudensis). These undertake diel feeding migrations from the shallow rocky zone towards the deeper sand and mud zones. When feeding on zoobenthos they cannot avoid swallowing carbonate sediment particles. These sediment particles pass through the alimentary canal of the fishes and are deposited again, after digestion of the food, as faeces in the shallow zones. Thus, the fishes transport the sediment in an unusual direction, from the deep to the shallow zones, in effect against the force of gravity. By recording the fish stock densities, digestion rates, and calcium carbonate content of fish stomach and guts, it was possible to estimate the amount of sediment transported by the fishes. In Harrington Sound, this amounts annually to 4530 kg calcium carbonate, 40% of which is deposited in the very shallow areas. The pH-values measured in fish stomachs seem to be acidic enough for the dissolution of carbonate sediment particles when transported by fishes.

Estimating the microbiological risks associated with inland flood events: Bridging theory and models of pathogen transport

PubMed Central

Collender, Philip A.; Cooke, Olivia C.; Bryant, Lee D.; Kjeldsen, Thomas R.; Remais, Justin V.

2017-01-01

Flooding is known to facilitate infectious disease transmission, yet quantitative research on microbiological risks associated with floods has been limited. Pathogen fate and transport models provide a framework to examine interactions between landscape characteristics, hydrology, and waterborne disease risks, but have not been widely developed for flood conditions. We critically examine capabilities of current hydrological models to represent unusual flow paths, non-uniform flow depths, and unsteady flow velocities that accompany flooding. We investigate the theoretical linkages between hydrodynamic processes and spatio-temporally variable suspension and deposition of pathogens from soils and sediments; pathogen dispersion in flow; and concentrations of constituents influencing pathogen transport and persistence. Identifying gaps in knowledge and modeling practice, we propose a research agenda to strengthen microbial fate and transport modeling applied to inland floods: 1) development of models incorporating pathogen discharges from flooded sources (e.g., latrines), effects of transported constituents on pathogen persistence, and supply-limited pathogen transport; 2) studies assessing parameter identifiability and comparing model performance under varying degrees of process representation, in a range of settings; 3) development of remotely sensed datasets to support modeling of vulnerable, data-poor regions; and 4) collaboration between modelers and field-based researchers to expand the collection of useful data in situ. PMID:28757789

Low-temperature dependence of the thermomagnetic transport properties of the SrTiO3/LaAlO3 interface

NASA Astrophysics Data System (ADS)

Lerer, S.; Ben Shalom, M.; Deutscher, G.; Dagan, Y.

2011-08-01

Transport measurements are reported, including Hall, Seebeck, and Nernst effects. All of these transport properties exhibit anomalous field and temperature dependencies, with a change of behavior observed at H˜1.5 T and T˜15 K. The low-temperature, low-field behaviors of all transport properties were reconciled using a simple two-band analysis. A more detailed model is required in order to explain the high-magnetic-field regime.

The properties of electromagnetic responses and optical modulation in terahertz metamaterials

NASA Astrophysics Data System (ADS)

Chen, Wei; Shi, Yulei; Wang, Wei; Zhou, Qingli; Zhang, Cunlin

2016-11-01

Metamaterials with subwavelength structural features show unique electromagnetic responses that are unattainable with natural materials. Recently, the research on these artificial materials has been pushed forward to the terahertz (THz) region because of potential applications in biological fingerprinting, security imaging, and high frequency magnetic and electric resonant devices. Furthermore, active control of their properties could further facilitate and open up new applications in terms of modulation and switching. In our work, we will first present our studies of dipole arrays at terahertz frequencies. Then in experimental and theoretical studies of terahertz subwavelength L-shaped structure, we proposed an unusual-mode current resonance responsible for low-frequency characteristic dip in transmission spectra. Comparing spectral properties of our designed simplified structures with that of split-ring resonators, we attribute this unusual mode to the resonance coupling and splitting under the broken symmetry of the structure. Finally, we use optical pump-terahertz probe method to investigate the spectral and dynamic behaviour of optical modulation in the split-ring resonators. We have observed the blue-shift and band broadening in the spectral changes of transmission under optical excitation at different delay times. The calculated surface currents using finite difference time domain simulation are presented to characterize these resonances, and the blue-shift can be explained by the changed refractive index and conductivity in the photoexcited semiconductor substrate.

41 CFR 302-10.400 - What policies must we establish for authorizing transportation of a mobile home?

Code of Federal Regulations, 2010 CFR

2010-07-01

... and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 10-ALLOWANCES FOR TRANSPORTATION OF MOBILE HOMES AND BOATS USED AS A PRIMARY RESIDENCE...

Origin of unusual bandgap shift and dual emission in organic-inorganic lead halide perovskites

PubMed Central

Dar, M. Ibrahim; Jacopin, Gwénolé; Meloni, Simone; Mattoni, Alessandro; Arora, Neha; Boziki, Ariadni; Zakeeruddin, Shaik Mohammed; Rothlisberger, Ursula; Grätzel, Michael

2016-01-01

Emission characteristics of metal halide perovskites play a key role in the current widespread investigations into their potential uses in optoelectronics and photonics. However, a fundamental understanding of the molecular origin of the unusual blueshift of the bandgap and dual emission in perovskites is still lacking. In this direction, we investigated the extraordinary photoluminescence behavior of three representatives of this important class of photonic materials, that is, CH3NH3PbI3, CH3NH3PbBr3, and CH(NH2)2PbBr3, which emerged from our thorough studies of the effects of temperature on their bandgap and emission decay dynamics using time-integrated and time-resolved photoluminescence spectroscopy. The low-temperature (<100 K) photoluminescence of CH3NH3PbI3 and CH3NH3PbBr3 reveals two distinct emission peaks, whereas that of CH(NH2)2PbBr3 shows a single emission peak. Furthermore, irrespective of perovskite composition, the bandgap exhibits an unusual blueshift by raising the temperature from 15 to 300 K. Density functional theory and classical molecular dynamics simulations allow for assigning the additional photoluminescence peak to the presence of molecularly disordered orthorhombic domains and also rationalize that the unusual blueshift of the bandgap with increasing temperature is due to the stabilization of the valence band maximum. Our findings provide new insights into the salient emission properties of perovskite materials, which define their performance in solar cells and light-emitting devices. PMID:27819049

Origin of unusual bandgap shift and dual emission in organic-inorganic lead halide perovskites.

PubMed

Dar, M Ibrahim; Jacopin, Gwénolé; Meloni, Simone; Mattoni, Alessandro; Arora, Neha; Boziki, Ariadni; Zakeeruddin, Shaik Mohammed; Rothlisberger, Ursula; Grätzel, Michael

2016-10-01

Emission characteristics of metal halide perovskites play a key role in the current widespread investigations into their potential uses in optoelectronics and photonics. However, a fundamental understanding of the molecular origin of the unusual blueshift of the bandgap and dual emission in perovskites is still lacking. In this direction, we investigated the extraordinary photoluminescence behavior of three representatives of this important class of photonic materials, that is, CH 3 NH 3 PbI 3 , CH 3 NH 3 PbBr 3 , and CH(NH 2 ) 2 PbBr 3 , which emerged from our thorough studies of the effects of temperature on their bandgap and emission decay dynamics using time-integrated and time-resolved photoluminescence spectroscopy. The low-temperature (<100 K) photoluminescence of CH 3 NH 3 PbI 3 and CH 3 NH 3 PbBr 3 reveals two distinct emission peaks, whereas that of CH(NH 2 ) 2 PbBr 3 shows a single emission peak. Furthermore, irrespective of perovskite composition, the bandgap exhibits an unusual blueshift by raising the temperature from 15 to 300 K. Density functional theory and classical molecular dynamics simulations allow for assigning the additional photoluminescence peak to the presence of molecularly disordered orthorhombic domains and also rationalize that the unusual blueshift of the bandgap with increasing temperature is due to the stabilization of the valence band maximum. Our findings provide new insights into the salient emission properties of perovskite materials, which define their performance in solar cells and light-emitting devices.

An ab initio electronic transport database for inorganic materials

DOE PAGES

Ricci, Francesco; Chen, Wei; Aydemir, Umut; ...

2017-07-04

Electronic transport in materials is governed by a series of tensorial properties such as conductivity, Seebeck coefficient, and effective mass. These quantities are paramount to the understanding of materials in many fields from thermoelectrics to electronics and photovoltaics. Transport properties can be calculated from a material’s band structure using the Boltzmann transport theory framework. We present here the largest computational database of electronic transport properties based on a large set of 48,000 materials originating from the Materials Project database. Our results were obtained through the interpolation approach developed in the BoltzTraP software, assuming a constant relaxation time. We present themore » workflow to generate the data, the data validation procedure, and the database structure. In conclusion, our aim is to target the large community of scientists developing materials selection strategies and performing studies involving transport properties.« less

An ab initio electronic transport database for inorganic materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ricci, Francesco; Chen, Wei; Aydemir, Umut

Electronic transport in materials is governed by a series of tensorial properties such as conductivity, Seebeck coefficient, and effective mass. These quantities are paramount to the understanding of materials in many fields from thermoelectrics to electronics and photovoltaics. Transport properties can be calculated from a material’s band structure using the Boltzmann transport theory framework. We present here the largest computational database of electronic transport properties based on a large set of 48,000 materials originating from the Materials Project database. Our results were obtained through the interpolation approach developed in the BoltzTraP software, assuming a constant relaxation time. We present themore » workflow to generate the data, the data validation procedure, and the database structure. In conclusion, our aim is to target the large community of scientists developing materials selection strategies and performing studies involving transport properties.« less

41 CFR 105-53.112 - General statement of functions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... contracting; real and personal property management; transportation, public transportation, public utilities... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false General statement of functions. 105-53.112 Section 105-53.112 Public Contracts and Property Management Federal Property...

41 CFR 302-7.100 - How are the charges of transporting HHG, and temporary storage calculated?

Code of Federal Regulations, 2010 CFR

2010-07-01

... transporting HHG, and temporary storage calculated? 302-7.100 Section 302-7.100 Public Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 7-TRANSPORTATION AND TEMPORARY STORAGE OF HOUSEHOLD GOODS AND PROFESSIONAL BOOKS, PAPERS, AND EQUIPMENT (PBP&E...

41 CFR 102-5.35 - Who is authorized home-to-work transportation?

Code of Federal Regulations, 2011 CFR

2011-01-01

... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false Who is authorized home... Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION GENERAL 5-HOME-TO-WORK TRANSPORTATION Authorizing Home-to-Work Transportation § 102-5.35 Who is authorized home-to-work transportation...

41 CFR 102-5.35 - Who is authorized home-to-work transportation?

Code of Federal Regulations, 2014 CFR

2014-01-01

... 41 Public Contracts and Property Management 3 2014-01-01 2014-01-01 false Who is authorized home... Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION GENERAL 5-HOME-TO-WORK TRANSPORTATION Authorizing Home-to-Work Transportation § 102-5.35 Who is authorized home-to-work transportation...

49 CFR 395.3 - Maximum driving time for property-carrying vehicles.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 5 2014-10-01 2014-10-01 false Maximum driving time for property-carrying vehicles. 395.3 Section 395.3 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION FEDERAL MOTOR CARRIER SAFETY REGULATIONS HOURS OF SERVICE OF DRIVERS § 395.3...

Metabolic Control of Vesicular Glutamate Transport and Release

PubMed Central

Juge, Narinobu; Gray, John A.; Omote, Hiroshi; Miyaji, Takaaki; Inoue, Tsuyoshi; Hara, Chiaki; Uneyama, Hisayuki; Edwards, Robert H.; Nicoll, Roger A.; Moriyama, Yoshinori

2010-01-01

Fasting has been used to control epilepsy since antiquity, but the mechanism of coupling between metabolic state and excitatory neurotransmission remains unknown. Previous work has shown that the vesicular glutamate transporters (VGLUTs) required for exocytotic release of glutamate undergo an unusual form of regulation by Cl−. Using functional reconstitution of the purified VGLUTs into proteoliposomes, we now show that Cl− acts as an allosteric activator, and the ketone bodies that increase with fasting inhibit glutamate release by competing with Cl− at the site of allosteric regulation. Consistent with these observations, acetoacetate reduced quantal size at hippocampal synapses, and suppresses glutamate release and seizures evoked with 4-aminopyridine in the brain. The results indicate an unsuspected link between metabolic state and excitatory neurotransmission through anion-dependent regulation of VGLUT activity. PMID:20920794

Conductance signatures of odd-frequency superconductivity in quantum spin Hall systems using a quantum point contact

NASA Astrophysics Data System (ADS)

Fleckenstein, C.; Ziani, N. Traverso; Trauzettel, B.

2018-04-01

Topological superconductors give rise to unconventional superconductivity, which is mainly characterized by the symmetry of the superconducting pairing amplitude. However, since the symmetry of the superconducting pairing amplitude is not directly observable, its experimental identification is rather difficult. In our work, we propose a system, composed of a quantum point contact and proximity-induced s -wave superconductivity at the helical edge of a two-dimensional topological insulator, for which we demonstrate the presence of odd-frequency pairing and its intimate connection to unambiguous transport signatures. Notably, our proposal requires no time-reversal symmetry breaking terms. We discover the domination of crossed Andreev reflection over electron cotunneling in a wide range of parameter space, which is a quite unusual transport regime.

The hovercraft environment.

PubMed

Lovesey, E J

1970-06-01

In just over a decade the hovercraft has progressed from first prototype to a successful commercial form of transport which also has the ability to penetrate many environments hitherto virtually inaccessible to manned vehicles. Comparison with rival short range vehicles such as the helicopter and hydrofoil show that the hovercraft has become one of the most versatile forms of transport available. This versatility and ability to operate in unusual or extreme environments has been accompanied by the problems of control and of protection of the occupants of the hovercraft from the hazards associated with these environments. Several of these problems are discussed, together with their possible solutions. This article is based on a paper given to the Nederlands Vereniging Voor Ergonomie/Ergonomics Research Society joint conference at Noordwijk in Holland, 11-13 June, 1969.

41 CFR 302-9.503 - Under what condition may we authorize transportation of a POV to a post of duty?

Code of Federal Regulations, 2010 CFR

2010-07-01

... and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 9-ALLOWANCES FOR TRANSPORTATION AND EMERGENCY STORAGE OF A PRIVATELY OWNED VEHICLE...

41 CFR 302-10.206 - May my agency assume direct responsibility for the costs of preparing and transporting my mobile...

Code of Federal Regulations, 2010 CFR

2010-07-01

...-10.206 Public Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 10-ALLOWANCES FOR TRANSPORTATION OF MOBILE HOMES AND BOATS...

41 CFR 302-10.402 - What costs must we pay a commercial carrier for transporting a mobile home?

Code of Federal Regulations, 2010 CFR

2010-07-01

... Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 10-ALLOWANCES FOR TRANSPORTATION OF MOBILE HOMES AND BOATS USED AS A PRIMARY RESIDENCE Agency...

Transport Properties of Ionic Liquid Mixtures Containing Heterodications

DOE PAGES

Lall-Ramnarine, S.; Fernandez, E.; Rodriguez, C.; ...

2016-08-30

This report discusses the transport properties of ionic liquid mixtures that incorporate a series of asymmetrical dications, including heterodications. The dicationic ILs combine either triphenylphosphonium and trimethylammonium cationic sites that are bridged to methylimidazolium or methylpyrrolidinium cationic sites. Mixtures were made of the dicationic bis(trifluoromethylsulfonyl)amide ionic liquids with N-ethoxyethyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide. The IL mixtures were characterized for their transport properties (temperature dependent conductivity and viscosity) and thermal properties (melting point and glass transition point).

A Review of the Thermodynamic, Transport, and Chemical Reaction Rate Properties of High-temperature Air

NASA Technical Reports Server (NTRS)

Hansen, C Frederick; Heims, Steve P

1958-01-01

Thermodynamic and transport properties of high temperature air, and the reaction rates for the important chemical processes which occur in air, are reviewed. Semiempirical, analytic expressions are presented for thermodynamic and transport properties of air. Examples are given illustrating the use of these properties to evaluate (1) equilibrium conditions following shock waves, (2) stagnation region heat flux to a blunt high-speed body, and (3) some chemical relaxation lengths in stagnation region flow.

Effect of sulfur doping on thermoelectric properties of Sodium Tantalate - A first principles study

NASA Astrophysics Data System (ADS)

Chowdary, Bharadwaj; Jayaraman, Kaushik; Molli, Muralikrishna

2018-05-01

In this work, we report the thermoelectric (TE) transport properties of perovskite-like Sodium Tantalate and studied the effect of Sulfur doping on TE properties of Sodium Tantalate. The band structures are calculated in the purview of density functional theory using the mBJ exchange correlation potential. The transport properties are evaluated using the Boltzmann transport theory in the constant relaxation time approximation. Our results suggest that Sulfur doped Sodium Tantalate is better n-type thermoelectric compared to Sodium Tantalate.

Functional significance of the E loop, a novel motif conserved in the lantibiotic immunity ATP-binding cassette transport systems.

PubMed

Okuda, Ken-ichi; Yanagihara, Sae; Sugayama, Tomomichi; Zendo, Takeshi; Nakayama, Jiro; Sonomoto, Kenji

2010-06-01

Lantibiotics are peptide-derived antibacterial substances produced by some Gram-positive bacteria and characterized by the presence of unusual amino acids, like lanthionines and dehydrated amino acids. Because lantibiotic producers may be attacked by self-produced lantibiotics, they express immunity proteins on the cytoplasmic membrane. An ATP-binding cassette (ABC) transport system mediated by the LanFEG protein complex is a major system in lantibiotic immunity. Multiple-sequence alignment analysis revealed that LanF proteins contain the E loop, a variant of the Q loop, which is a well-conserved motif in the nucleotide-binding domains (NBDs) of general ABC transporters. To elucidate E loop function, we introduced a mutation in the NukF protein, which is involved in the nukacin-ISK-1 immunity system. Amino acid replacement of glutamic acid in the E loop with glutamine (E85Q) resulted in slight decreases in the immunity level and transport activity. Additionally, the E85A mutation severely impaired the immunity level and transport activity. On the other hand, ATPase activities of purified E85Q and E85A mutants were almost similar to that of the wild type. These results suggested that the E loop found in ABC transporters involved in lantibiotic immunity plays a significant role in the function of these transporters, especially in the structural change of transmembrane domains.

Computation of electron transport and relaxation properties in gases based on improved multi-term approximation of Boltzmann equation

NASA Astrophysics Data System (ADS)

Cai, X. J.; Wang, X. X.; Zou, X. B.; Lu, Z. W.

2018-01-01

An understanding of electron kinetics is of importance in various applications of low temperature plasmas. We employ a series of model and real gases to investigate electron transport and relaxation properties based on improved multi-term approximation of the Boltzmann equation. First, a comparison of different methods to calculate the interaction integrals has been carried out; the effects of free parameters, such as vmax, lmax, and the arbitrary temperature Tb, on the convergence of electron transport coefficients are analyzed. Then, the modified attachment model of Ness et al. and SF6 are considered to investigate the effect of attachment on the electron transport properties. The deficiency of the pulsed Townsend technique to measure the electron transport and reaction coefficients in electronegative gases is highlighted when the reduced electric field is small. In order to investigate the effect of external magnetic field on the electron transport properties, Ar plasmas in high power impulse sputtering devices are considered. In the end, the electron relaxation properties of the Reid model under the influence of electric and magnetic fields are demonstrated.

Identification of two novel mutations in the SLC45A2 gene in a Hungarian pedigree affected by unusual OCA type 4.

PubMed

Tóth, Lola; Fábos, Beáta; Farkas, Katalin; Sulák, Adrienn; Tripolszki, Kornélia; Széll, Márta; Nagy, Nikoletta

2017-03-15

Oculocutaneous albinism (OCA) is a clinically and genetically heterogenic group of pigmentation abnormalities. OCA type IV (OCA4, OMIM 606574) develops due to homozygous or compound heterozygous mutations in the solute carrier family 45, member 2 (SLC45A2) gene. This gene encodes a membrane-associated transport protein, which regulates tyrosinase activity and, thus, melanin content by changing melanosomal pH and disrupting the incorporation of copper into tyrosinase. Here we report two Hungarian siblings affected by an unusual OCA4 phenotype. After genomic DNA was isolated from peripheral blood of the patients, the coding regions of the SLC45A2 gene were sequenced. In silico tools were applied to identify the functional impact of the newly detected mutations. Direct sequencing of the SLC45A2 gene revealed two novel, heterozygous mutations, one missense (c.1226G > A, p.Gly409Asp) and one nonsense (c.1459C > T, p.Gln437*), which were present in both patients, suggesting the mutations were compound heterozygous. In silico tools suggest that these variations are disease causing mutations. The newly identified mutations may affect the transmembrane domains of the protein, and could impair transport function, resulting in decreases in both melanosomal pH and tyrosinase activity. Our study provides expands on the mutation spectrum of the SLC45A2 gene and the genetic background of OCA4.

Fatigue performance of additively manufactured meta-biomaterials: The effects of topology and material type.

PubMed

Ahmadi, S M; Hedayati, R; Li, Y; Lietaert, K; Tümer, N; Fatemi, A; Rans, C D; Pouran, B; Weinans, H; Zadpoor, A A

2018-01-01

Additive manufacturing (AM) techniques enable fabrication of bone-mimicking meta-biomaterials with unprecedented combinations of topological, mechanical, and mass transport properties. The mechanical performance of AM meta-biomaterials is a direct function of their topological design. It is, however, not clear to what extent the material type is important in determining the fatigue behavior of such biomaterials. We therefore aimed to determine the isolated and modulated effects of topological design and material type on the fatigue response of metallic meta-biomaterials fabricated with selective laser melting. Towards that end, we designed and additively manufactured Co-Cr meta-biomaterials with three types of repeating unit cells and three to four porosities per type of repeating unit cell. The AM meta-biomaterials were then mechanically tested to obtain their normalized S-N curves. The obtained S-N curves of Co-Cr meta-biomaterials were compared to those of meta-biomaterials with same topological designs but made from other materials, i.e. Ti-6Al-4V, tantalum, and pure titanium, available from our previous studies. We found the material type to be far more important than the topological design in determining the normalized fatigue strength of our AM metallic meta-biomaterials. This is the opposite of what we have found for the quasi-static mechanical properties of the same meta-biomaterials. The effects of material type, manufacturing imperfections, and topological design were different in the high and low cycle fatigue regions. That is likely because the cyclic response of meta-biomaterials depends not only on the static and fatigue strengths of the bulk material but also on other factors that may include strut roughness, distribution of the micro-pores created inside the struts during the AM process, and plasticity. Meta-biomaterials are a special class of metamaterials with unusual or unprecedented combinations of mechanical, physical (e.g. mass transport), and biological properties. Topologically complex and additively manufactured meta-biomaterials have been shown to improve bone regeneration and osseointegration. The mechanical properties of such biomaterials are directly related to their topological design and material type. However, previous studies of such biomaterials have largely neglected the effects of material type, instead focusing on topological design. We show here that neglecting the effects of material type is unjustified. We studied the isolated and combined effects of topological design and material type on the normalized S-N curves of metallic bone-mimicking biomaterials and found them to be more strongly dependent on the material type than topological design. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Organic matter and the geotechnical properties of submarine sediments

NASA Astrophysics Data System (ADS)

Keller, George H.

1982-09-01

Continental slope deposits off Peru and Oregon where coastal upwelling is a pronounced oceanographic process possess significant concentrations of organic carbon. Geotechnical properties are altered to varying degrees by the organic matter. Organic matter absorbs water and causes clay-size particles to aggregate forming an open fabric. This causes unusually high water contents and plasticity and exceptionally low wet bulk densities. Some of these deposits show notable increases in shear strength, sensitivity and degree of apparent overconsolidation. Owing to the unique geotechnical properties, sediment stability characteristics are considered to be poor in situations of excess pore pressures. Failure appears to take the form of a fluidized flow somewhat similar to the quick clays of Scandinavia.

Optical transitions in two-dimensional topological insulators with point defects

NASA Astrophysics Data System (ADS)

Sablikov, Vladimir A.; Sukhanov, Aleksei A.

2016-12-01

Nontrivial properties of electronic states in topological insulators are inherent not only to the surface and boundary states, but to bound states localized at structure defects as well. We clarify how the unusual properties of the defect-induced bound states are manifested in optical absorption spectra in two-dimensional topological insulators. The calculations are carried out for defects with short-range potential. We find that the defects give rise to the appearance of specific features in the absorption spectrum, which are an inherent property of topological insulators. They have the form of two or three absorption peaks that are due to intracenter transitions between electron-like and hole-like bound states.

The Weak Nuclear Force: Through the Looking Glass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lincoln, Don

Of all of the known subatomic forces, the weak force is in many ways unique. One particularly interesting facet is that the force differentiates between a particle that is rotating clockwise and counterclockwise. In this video, Fermilab’s Dr. Don Lincoln describes this unusual property and introduces some of the historical figures who played a role in working it all out.

The Perfect Storm: How Policy, Research, and Assessment Will Transform Public Education

ERIC Educational Resources Information Center

McMillan, James H.

2011-01-01

In the 2000 movie "The Perfect Storm," there is an unusual convergence of several critical weather factors that set the stage for a destructive outcome that takes both property and lives. It has become a popular metaphor to describe how events come together in a unique way to have an exceptional influence on something, typically a negative impact.…

41 CFR 302-9.8 - What type of POV may I be authorized to transport, and if necessary, store under emergency...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 302-9.8 Public Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 9-ALLOWANCES FOR TRANSPORTATION AND EMERGENCY STORAGE OF A...

41 CFR 302-9.101 - In what situations may my agency authorize transportation of a POV to my post of duty?

Code of Federal Regulations, 2010 CFR

2010-07-01

... Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 9-ALLOWANCES FOR TRANSPORTATION AND EMERGENCY STORAGE OF A PRIVATELY OWNED VEHICLE...

RELATIONSHIP BETWEEN CELL SURFACE PROPERTIES AND TRANSPORT OF BACTERIA THROUGH SOIL

EPA Science Inventory

A study was conducted to relate the properties of Enterobacter, Pseudomonas, Bacillus, Achromobacter, Flavobacterium, and Arthrobacter strains to their transport with water moving through soil. the bacteria differed markedly in their extent of transport; their hydrophobicity, as...

41 CFR 102-118.265 - What is a prepayment audit?

Code of Federal Regulations, 2010 CFR

2010-07-01

... audit? 102-118.265 Section 102-118.265 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT Prepayment Audits of Transportation Services Agency Requirements for Prepayment Audits...

41 CFR 302-10.203 - What are my allowances when a mobile home is transported partly by commercial carrier and partly...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 302-10.203 Public Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 10-ALLOWANCES FOR TRANSPORTATION OF MOBILE HOMES AND BOATS...

41 CFR 302-10.401 - Are the allowances for transporting a mobile home in addition to the allowances for per diem...

Code of Federal Regulations, 2010 CFR

2010-07-01

... Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 10-ALLOWANCES FOR TRANSPORTATION OF MOBILE HOMES AND BOATS USED AS A PRIMARY RESIDENCE Agency...

41 CFR 302-10.202 - Am I entitled to any other allowances when I transport my mobile home by POV?

Code of Federal Regulations, 2010 CFR

2010-07-01

... and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 10-ALLOWANCES FOR TRANSPORTATION OF MOBILE HOMES AND BOATS USED AS A PRIMARY RESIDENCE...

41 CFR 302-10.300 - May I receive an advance of funds when a commercial carrier transports the mobile home?

Code of Federal Regulations, 2010 CFR

2010-07-01

... Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 10-ALLOWANCES FOR TRANSPORTATION OF MOBILE HOMES AND BOATS USED AS A PRIMARY RESIDENCE...

41 CFR 302-10.201 - What is the mileage allowance when you transport a mobile home overland by a POV?

Code of Federal Regulations, 2010 CFR

2010-07-01

... and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 10-ALLOWANCES FOR TRANSPORTATION OF MOBILE HOMES AND BOATS USED AS A PRIMARY RESIDENCE...

14 CFR 296.2 - Applicability.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS INDIRECT AIR TRANSPORTATION OF PROPERTY General § 296.2 Applicability. This part applies to air transportation of property by indirect cargo air carriers, and to persons entering into control relationships...

Testing anthropic selection: a climate change example.

PubMed

Waltham, Dave

2011-03-01

Planetary anthropic selection, the idea that Earth has unusual properties since, otherwise, we would not be here to observe it, is a controversial idea. This paper proposes a methodology by which to test anthropic proposals by comparison of Earth to synthetic populations of Earth-like planets. The paper illustrates this approach by investigating possible anthropic selection for high (or low) rates of Milankovitch-driven climate change. Three separate tests are investigated: (1) Earth-Moon properties and their effect on obliquity; (2) Individual planet locations and their effect on eccentricity variation; (3) The overall structure of the Solar System and its effect on eccentricity variation. In all three cases, the actual Earth/Solar System has unusually low Milankovitch frequencies compared to similar alternative systems. All three results are statistically significant at the 5% or better level, and the probability of all three occurring by chance is less than 10(-5). It therefore appears that there has been anthropic selection for slow Milankovitch cycles. This implies possible selection for a stable climate, which, if true, undermines the Gaia hypothesis and also suggests that planets with Earth-like levels of biodiversity are likely to be very rare. © Mary Ann Liebert, Inc.

Topological modes bound to dislocations in mechanical metamaterials

NASA Astrophysics Data System (ADS)

Paulose, Jayson; Chen, Bryan Gin-Ge; Vitelli, Vincenzo

2015-02-01

Mechanical metamaterials are artificial structures with unusual properties, such as negative Poisson ratio, bistability or tunable vibrational properties, that originate in the geometry of their unit cell. Often at the heart of such unusual behaviour is a soft mode: a motion that does not significantly stretch or compress the links between constituent elements. When activated by motors or external fields, soft modes become the building blocks of robots and smart materials. Here, we demonstrate the existence of topological soft modes that can be positioned at desired locations in a metamaterial while being robust against a wide range of structural deformations or changes in material parameters. These protected modes, localized at dislocations in deformed kagome and square lattices, are the mechanical analogue of topological states bound to defects in electronic systems. We create physical realizations of the topological modes in prototypes of kagome lattices built out of rigid triangular plates. We show mathematically that they originate from the interplay between two Berry phases: the Burgers vector of the dislocation and the topological polarization of the lattice. Our work paves the way towards engineering topologically protected nanomechanical structures for molecular robotics or information storage and read-out.

41 CFR 302-7.101 - Where can the commuted rate schedules for the transportation of HHG, and temporary storage be found?

Code of Federal Regulations, 2010 CFR

2010-07-01

... rate schedules for the transportation of HHG, and temporary storage be found? 302-7.101 Section 302-7.101 Public Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 7-TRANSPORTATION AND TEMPORARY STORAGE OF HOUSEHOLD GOODS AND PROFESSIONAL...

41 CFR 302-9.7 - Must my agency authorize transportation or emergency storage of my POV?

Code of Federal Regulations, 2010 CFR

2010-07-01

... transportation or emergency storage of my POV? 302-9.7 Section 302-9.7 Public Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 9-ALLOWANCES FOR TRANSPORTATION AND EMERGENCY STORAGE OF A PRIVATELY OWNED VEHICLE General Rules § 302-9.7 Must my...

41 CFR 302-9.502 - What governing policies must we establish for the allowances for transportation and emergency...

Code of Federal Regulations, 2010 CFR

2010-07-01

... must we establish for the allowances for transportation and emergency storage of a POV? 302-9.502 Section 302-9.502 Public Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 9-ALLOWANCES FOR TRANSPORTATION AND EMERGENCY STORAGE OF A...

41 CFR 302-9.11 - May I receive an advance of funds for transportation and emergency storage of my POV?

Code of Federal Regulations, 2010 CFR

2010-07-01

... of funds for transportation and emergency storage of my POV? 302-9.11 Section 302-9.11 Public Contracts and Property Management Federal Travel Regulation System RELOCATION ALLOWANCES TRANSPORTATION AND STORAGE OF PROPERTY 9-ALLOWANCES FOR TRANSPORTATION AND EMERGENCY STORAGE OF A PRIVATELY OWNED VEHICLE...

Unconventional aspects of electronic transport in delafossite oxides

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Atmospheric organochlorine pesticides in the western Canadian Arctic: Evidence of transpacific transport

NASA Astrophysics Data System (ADS)

Bailey, R.; Barrie, L. A.; Halsall, C. J.; Fellin, P.; Muir, D. C. G.

2000-05-01

Concentrations of hexachlorocyclohexanes (HCHs), chlordane, and dichlorodiphenyltrichloroethane (DDT) were measured in ambient air samples on a weekly basis between December 1992 and January 1995 at Tagish Yukon, Canada. In winter, unusually high air concentrations of HCHs, DDT, and chlordanes at Tagish were predominantly influenced by transpacific long-range atmospheric transport from eastern Asia that generally occurred within 5 days. HCH and heptachlor epoxide concentrations were correlated with the time that air spent over eastern Asia prior to arrival at Tagish. Chlordane and DDT, which also increase with transpacific transport, do not show a correlation with the time the upwind airshed included Asia as the composition of these pesticides in the atmosphere is affected by differences in usage patterns, application methods, variable composition of parent pesticides and metabolites in the soil, and rates of volatilization. Air masses originating from North America had the highest concentrations of HCHs and chlordanes when the 5-day upwind airshed included the western United States. Concentrations of HCHs may also be influenced by lindane usage in Canada.

Evidence of thermal transport anisotropy in stable glasses of vapor deposited organic molecules

NASA Astrophysics Data System (ADS)

Ràfols-Ribé, Joan; Dettori, Riccardo; Ferrando-Villalba, Pablo; Gonzalez-Silveira, Marta; Abad, Llibertat; Lopeandía, Aitor F.; Colombo, Luciano; Rodríguez-Viejo, Javier

2018-03-01

Vapor deposited organic glasses are currently in use in many optoelectronic devices. Their operation temperature is limited by the glass transition temperature of the organic layers and thermal management strategies become increasingly important to improve the lifetime of the device. Here we report the unusual finding that molecular orientation heavily influences heat flow propagation in glassy films of small molecule organic semiconductors. The thermal conductivity of vapor deposited thin-film semiconductor glasses is anisotropic and controlled by the deposition temperature. We compare our data with extensive molecular dynamics simulations to disentangle the role of density and molecular orientation on heat propagation. Simulations do support the view that thermal transport along the backbone of the organic molecule is strongly preferred with respect to the perpendicular direction. This is due to the anisotropy of the molecular interaction strength that limits the transport of atomic vibrations. This approach could be used in future developments to implement small molecule glassy films in thermoelectric or other organic electronic devices.

Unfolding of a ClC chloride transporter retains memory of its evolutionary history.

PubMed

Min, Duyoung; Jefferson, Robert E; Qi, Yifei; Wang, Jing Yang; Arbing, Mark A; Im, Wonpil; Bowie, James U

2018-05-01

ClC chloride channels and transporters are important for chloride homeostasis in species from bacteria to human. Mutations in ClC proteins cause genetically inherited diseases, some of which are likely to involve folding defects. The ClC proteins present a challenging and unusual biological folding problem because they are large membrane proteins possessing a complex architecture, with many reentrant helices that go only partway through membrane and loop back out. Here we were able to examine the unfolding of the Escherichia coli ClC transporter, ClC-ec1, using single-molecule forced unfolding methods. We found that the protein could be separated into two stable halves that unfolded independently. The independence of the two domains is consistent with an evolutionary model in which the two halves arose from independently folding subunits that later fused together. Maintaining smaller folding domains of lesser complexity within large membrane proteins may be an advantageous strategy to avoid misfolding traps.

Signatures of the Adler–Bell–Jackiw chiral anomaly in a Weyl fermion semimetal

DOE PAGES

Zhang, Cheng-Long; Xu, Su-Yang; Belopolski, Ilya; ...

2016-02-25

Weyl semimetals provide the realization of Weyl fermions in solid-state physics. Among all the physical phenomena that are enabled by Weyl semimetals, the chiral anomaly is the most unusual one. Here, we report signatures of the chiral anomaly in the magneto-transport measurements on the first Weyl semimetal TaAs. We show negative magnetoresistance under parallel electric and magnetic fields, that is, unlike most metals whose resistivity increases under an external magnetic field, we observe that our high mobility TaAs samples become more conductive as a magnetic field is applied along the direction of the current for certain ranges of the fieldmore » strength. We present systematically detailed data and careful analyses, which allow us to exclude other possible origins of the observed negative magnetoresistance. Finally, our transport data, corroborated by photoemission measurements, first-principles calculations and theoretical analyses, collectively demonstrate signatures of the Weyl fermion chiral anomaly in the magneto-transport of TaAs.« less

Revealing an outward-facing open conformational state in a CLC Cl –/H + exchange transporter

DOE PAGES

Khantwal, Chandra M.; Abraham, Sherwin J.; Han, Wei; ...

2016-01-22

CLC secondary active transporters exchange Cl - for H + . Crystal structures have suggested that the conformational change from occluded to outward-facing states is unusually simple, involving only the rotation of a conserved glutamate (Glu ex ) upon its protonation. Using 19 F NMR, we show that as [H + ] is increased to protonate Glu ex and enrich the outward-facing state, a residue ~20 Å away from Glu ex , near the subunit interface, moves from buried to solvent-exposed. Consistent with functional relevance of this motion, constriction via inter-subunit cross-linking reduces transport. Molecular dynamics simulations indicate that themore » cross-link dampens extracellular gate-opening motions. In support of this model, mutations that decrease steric contact between Helix N (part of the extracellular gate) and Helix P (at the subunit interface) remove the inhibitory effect of the cross-link. Together, these results demonstrate the formation of a previously uncharacterized 'outward-facing open' state, and highlight the relevance of global structural changes in CLC function.« less

49 CFR 18.31 - Real property.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 1 2014-10-01 2014-10-01 false Real property. 18.31 Section 18.31 Transportation... Real property. (a) Title. Subject to the obligations and conditions set forth in this section, title to real property acquired under a grant or subgrant will vest upon acquisition in the grantee or...

49 CFR 18.31 - Real property.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 1 2012-10-01 2012-10-01 false Real property. 18.31 Section 18.31 Transportation... Real property. (a) Title. Subject to the obligations and conditions set forth in this section, title to real property acquired under a grant or subgrant will vest upon acquisition in the grantee or...

49 CFR 18.31 - Real property.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 1 2011-10-01 2011-10-01 false Real property. 18.31 Section 18.31 Transportation... Real property. (a) Title. Subject to the obligations and conditions set forth in this section, title to real property acquired under a grant or subgrant will vest upon acquisition in the grantee or...

49 CFR 18.31 - Real property.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 1 2013-10-01 2013-10-01 false Real property. 18.31 Section 18.31 Transportation... Real property. (a) Title. Subject to the obligations and conditions set forth in this section, title to real property acquired under a grant or subgrant will vest upon acquisition in the grantee or...

49 CFR 18.31 - Real property.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 1 2010-10-01 2010-10-01 false Real property. 18.31 Section 18.31 Transportation... Real property. (a) Title. Subject to the obligations and conditions set forth in this section, title to real property acquired under a grant or subgrant will vest upon acquisition in the grantee or...

41 CFR 102-117.125 - How detailed must I describe property for shipment when communicating to a TSP?

Code of Federal Regulations, 2010 CFR

2010-07-01

... Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 117-TRANSPORTATION MANAGEMENT Business Rules To Consider Before Shipping... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false How detailed must I...

41 CFR 109-38.301-1.50 - Authorization for transportation between residence and place of employment.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false Authorization for... Contracts and Property Management Federal Property Management Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS AVIATION, TRANSPORTATION, AND MOTOR VEHICLES 38-MOTOR EQUIPMENT...

41 CFR 109-38.301-1.50 - Authorization for transportation between residence and place of employment.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Authorization for... Contracts and Property Management Federal Property Management Regulations System (Continued) DEPARTMENT OF ENERGY PROPERTY MANAGEMENT REGULATIONS AVIATION, TRANSPORTATION, AND MOTOR VEHICLES 38-MOTOR EQUIPMENT...

Bioinspired ion-transport properties of solid-state single nanochannels and their applications in sensing.

PubMed

Tian, Ye; Wen, Liping; Hou, Xu; Hou, Guanglei; Jiang, Lei

2012-07-16

Biological ion channels are able to control ion-transport processes precisely because of their intriguing properties, such as selectivity, rectification, and gating. Learning from nature, scientists have developed a promising system--solid-state single nanochannels--to mimic biological ion-transport properties. These nanochannels have many impressive properties, such as excess surface charge, making them selective; the ability to be produced or modified asymmetrically, endowing them with rectification; and chemical reactivity of the inner surface, imparting them with desired gating properties. Based on these unique characteristics, solid-state single nanochannels have been explored in various applications, such as sensing. In this context, we summarize recent developments of bioinspired solid-state single nanochannels with ion-transport properties that resemble their biological counterparts, including selectivity, rectification, and gating; their applications in sensing are also introduced briefly. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A survey for variable young stars with small telescopes: First results from HOYS-CAPS

NASA Astrophysics Data System (ADS)

Froebrich, D.; Campbell-White, J.; Scholz, A.; Eislöffel, J.; Zegmott, T.; Billington, S. J.; Donohoe, J.; Makin, S. V.; Hibbert, R.; Newport, R. J.; Pickard, R.; Quinn, N.; Rodda, T.; Piehler, G.; Shelley, M.; Parkinson, S.; Wiersema, K.; Walton, I.

2018-05-01

Variability in Young Stellar Objects (YSOs) is one of their primary characteristics. Long-term, multi-filter, high-cadence monitoring of large YSO samples is the key to understand the partly unusual light-curves that many of these objects show. Here we introduce and present the first results of the HOYS-CAPScitizen science project which aims to perform such monitoring for nearby (d < 1 kpc) and young (age < 10 Myr) clusters and star forming regions, visible from the northern hemisphere, with small telescopes. We have identified and characterised 466 variable (413 confirmed young) stars in 8 young, nearby clusters. All sources vary by at least 0.2 mag in V, have been observed at least 15 times in V, R and I in the same night over a period of about 2 yrs and have a Stetson index of larger than 1. This is one of the largest samples of variable YSOs observed over such a time-span and cadence in multiple filters. About two thirds of our sample are classical T-Tauri stars, while the rest are objects with depleted or transition disks. Objects characterised as bursters show by far the highest variability. Dippers and objects whose variability is dominated by occultations from normal interstellar dust or dust with larger grains (or opaque material) have smaller amplitudes. We have established a hierarchical clustering algorithm based on the light-curve properties which allows the identification of the YSOs with the most unusual behaviour, and to group sources with similar properties. We discuss in detail the light-curves of the unusual objects V2492 Cyg, V350 Cep and 2MASS J21383981+5708470.

Rapid X-ray variability properties during the unusual very hard state in neutron-star low-mass X-ray binaries

NASA Astrophysics Data System (ADS)

Wijnands, R.; Parikh, A. S.; Altamirano, D.; Homan, J.; Degenaar, N.

2017-11-01

Here, we study the rapid X-ray variability (using XMM-Newton observations) of three neutron-star low-mass X-ray binaries (1RXS J180408.9-342058, EXO 1745-248 and IGR J18245-2452) during their recently proposed very hard spectral state. All our systems exhibit a strong to very strong noise component in their power density spectra (rms amplitudes ranging from 34 per cent to 102 per cent) with very low characteristic frequencies (as low as 0.01 Hz). These properties are more extreme than what is commonly observed in the canonical hard state of neutron-star low-mass X-ray binaries observed at X-ray luminosities similar to those we observe from our sources. This suggests that indeed the very hard state is a spectral-timing state distinct from the hard state, although we argue that the variability behaviour of IGR J18245-2452 is very extreme and possibly this source was in a very unusual state. We also compare our results with the rapid X-ray variability of the accreting millisecond X-ray pulsars IGR J00291+5934 and Swift J0911.9-6452 (also using XMM-Newton data) for which previously similar variability phenomena were observed. Although their energy spectra (as observed using the Swift X-ray telescope) were not necessarily as hard (i.e. for Swift J0911.9-6452) as for our other three sources, we conclude that likely both sources were also in very similar state during their XMM-Newton observations. This suggests that different sources that are found in this new state might exhibit different spectral hardness and one has to study both the spectral and the rapid variability to identify this unusual state.

Study on the Electronic Transport Properties of Zigzag GaN Nanotubes

NASA Astrophysics Data System (ADS)

Li, Enling; Wang, Xiqiang; Hou, Liping; Zhao, Danna; Dai, Yuanbin; Wang, Xuewen

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.

Broadband dielectric response of CaCu3Ti4O12 : From dc to the electronic transition regime

NASA Astrophysics Data System (ADS)

Kant, Ch.; Rudolf, T.; Mayr, F.; Krohns, S.; Lunkenheimer, P.; Ebbinghaus, S. G.; Loidl, A.

2008-01-01

We report on phonon properties and electronic transitions in CaCu3Ti4O12 , a material which reveals a colossal dielectric constant at room temperature without any ferroelectric transition. The results of far- and midinfrared measurements are compared to those obtained by broadband dielectric and millimeter-wave spectroscopy on the same single crystal. The unusual temperature dependence of phonon eigenfrequencies, dampings, and ionic plasma frequencies of low-lying phonon modes is analyzed and discussed in detail. Electronic excitations below 4eV are identified as transitions between full and empty hybridized oxygen-copper bands and between oxygen-copper and unoccupied Ti3d bands. The unusually small band gap determined from the dc conductivity (˜200meV) compares well with the optical results.

Reversible dilatancy in entangled single-wire materials.

PubMed

Rodney, David; Gadot, Benjamin; Martinez, Oriol Riu; du Roscoat, Sabine Rolland; Orgéas, Laurent

2016-01-01

Designing structures that dilate rapidly in both tension and compression would benefit devices such as smart filters, actuators or fasteners. This property however requires an unusual Poisson ratio, or Poisson function at finite strains, which has to vary with applied strain and exceed the familiar bounds: less than 0 in tension and above 1/2 in compression. Here, by combining mechanical tests and discrete element simulations, we show that a simple three-dimensional architected material, made of a self-entangled single long coiled wire, behaves in between discrete and continuum media, with a large and reversible dilatancy in both tension and compression. This unusual behaviour arises from an interplay between the elongation of the coiled wire and rearrangements due to steric effects, which, unlike in traditional discrete media, are hysteretically reversible when the architecture is made of an elastic fibre.

Thermal Analysis of Unusual Local-scale Features on the Surface of Vesta

NASA Technical Reports Server (NTRS)

Tosi, F.; Capria, M. T.; DeSanctis, M. C.; Capaccioni, F.; Palomba, E.; Zambon, F.; Ammannito, E.; Blewett, D. T.; Combe, J.-Ph.; Denevi, B. W.;

Unusual 4-hydroxybenzaldehyde synthase activity from tissue cultures of the vanilla orchid Vanilla planifolia.

PubMed

Podstolski, Andrzej; Havkin-Frenkel, Daphna; Malinowski, Jacek; Blount, Jack W; Kourteva, Galina; Dixon, Richard A

2002-11-01

Tissue cultures of the vanilla orchid, Vanilla planifolia, produce the flavor compound vanillin (4-hydroxy-3-methoxybenzaldehyde) and vanillin precursors such as 4-hydroxybenzaldehyde. A constitutively expressed enzyme activity catalyzing chain shortening of a hydroxycinnamic acid, believed to be the first reaction specific for formation of vanilla flavor compounds, was identified in these cultures. The enzyme converts 4-coumaric acid non-oxidatively to 4-hydroxybenzaldehyde in the presence of a thiol reagent but with no co-factor requirement. Several forms of this 4-hydroxybenzaldehyde synthase (4HBS) were resolved and partially purified by a combination of hydrophobic interaction, ion exchange and gel filtration chromatography. These forms appear to be interconvertible. The unusual properties of the 4HBS, and its appearance in different protein fractions, raise questions as to its physiological role in vanillin biosynthesis in vivo.

Unusual Thermal Hall Effect in a Kitaev Spin Liquid Candidate α -RuCl3

NASA Astrophysics Data System (ADS)

Kasahara, Y.; Sugii, K.; Ohnishi, T.; Shimozawa, M.; Yamashita, M.; Kurita, N.; Tanaka, H.; Nasu, J.; Motome, Y.; Shibauchi, T.; Matsuda, Y.

2018-05-01

The Kitaev quantum spin liquid displays the fractionalization of quantum spins into Majorana fermions. The emergent Majorana edge current is predicted to manifest itself in the form of a finite thermal Hall effect, a feature commonly discussed in topological superconductors. Here we report on thermal Hall conductivity κx y measurements in α -RuCl3 , a candidate Kitaev magnet with the two-dimensional honeycomb lattice. In a spin-liquid (Kitaev paramagnetic) state below the temperature characterized by the Kitaev interaction JK/kB˜80 K , positive κx y develops gradually upon cooling, demonstrating the presence of highly unusual itinerant excitations. Although the zero-temperature property is masked by the magnetic ordering at TN=7 K , the sign, magnitude, and T dependence of κx y/T at intermediate temperatures follows the predicted trend of the itinerant Majorana excitations.

Nanoscale ferromagnetism in phase-separated manganites

NASA Astrophysics Data System (ADS)

Mori, S.; Horibe, Y.; Asaka, T.; Matsui, Y.; Chen, C. H.; Cheong, S. W.

2007-03-01

Magnetic domain structures in phase-separated manganites were investigated by low-temperature Lorentz electron microscopy, in order to understand some unusual physical properties such as a colossal magnetoresistance (CMR) effect and a metal-to-insulator transition. In particular, we examined a spatial distribution of the charge/orbital-ordered (CO/OO) insulator state and the ferromagnetic (FM) metallic one in phase-separated manganites; Cr-doped Nd0.5Ca0.5MnO3 and ( La1-xPrx)CaMnO3 with x=0.375, by obtaining both the dark-field images and Lorentz electron microscopic ones. It is found that an unusual coexistence of the CO/OO and FM metallic states below a FM transition temperature in the two compounds. The present experimental results clearly demonstrated the coexisting state of the two distinct ground states in manganites.

Trigonal warping induced unusual spin texture and strong spin polarization in graphene with the Rashba effect

NASA Astrophysics Data System (ADS)

Ma, Da-Shuai; Yu, Zhi-Ming; Pan, Hui; Yao, Yugui

2018-02-01

We study the electronic and scattering properties of graphene with moderate Rashba spin-orbit coupling (SOC). The Rashba SOC in graphene tends to distort the band structure and gives rise to a trigonally warped Fermi surface. For electrons at a pronouncedly warped Fermi surface, the spin direction exhibits a staircase profile as a function of the momentum, making an unusual spin texture. We also study the spin-resolved scattering on a Rashba barrier and find that the trigonal warping is essential for producing spin polarization of the transmitted current. Particularly, both the direction and strength of the spin polarization can be controlled by kinds of electric methods. Our work unveils that not only SOC but also the geometry of the Fermi surface is important for generating spin polarization.

Structural insight into lipopolysaccharide transport from the Gram-negative bacterial inner membrane to the outer membrane.

PubMed

Dong, Haohao; Tang, Xiaodi; Zhang, Zhengyu; Dong, Changjiang

2017-11-01

Lipopolysaccharide (LPS) is an important component of the outer membrane (OM) of Gram-negative bacteria, playing essential roles in protecting bacteria from harsh environments, in drug resistance and in pathogenesis. LPS is synthesized in the cytoplasm and translocated to the periplasmic side of the inner membrane (IM), where it matures. Seven lipopolysaccharide transport proteins, LptA-G, form a trans‑envelope complex that is responsible for LPS extraction from the IM and transporting it across the periplasm to the OM. The LptD/E of the complex transports LPS across the OM and inserts it into the outer leaflet of the OM. In this review we focus upon structural and mechanistic studies of LPS transport proteins, with a particular focus upon the LPS ABC transporter LptB 2 FG. This ATP binding cassette transporter complex consists of twelve transmembrane segments and has a unique mechanism whereby it extracts LPS from the periplasmic face of the IM through a pair of lateral gates and then powers trans‑periplasmic transport to the OM through a slide formed by either of the periplasmic domains of LptF or LptG, LptC, LptA and the N-terminal domain of LptD. The structural and functional studies of the seven lipopolysaccharide transport proteins provide a platform to explore the unusual mechanisms of LPS extraction, transport and insertion from the inner membrane to the outer membrane. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop. Copyright © 2017 Elsevier B.V. All rights reserved.

41 CFR 102-118.270 - Must my agency establish a prepayment audit program?

Code of Federal Regulations, 2010 CFR

2010-07-01

... a prepayment audit program? 102-118.270 Section 102-118.270 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT Prepayment Audits of Transportation Services Agency Requirements...

41 CFR 102-118.410 - Can GSA suspend my agency's prepayment audit program?

Code of Federal Regulations, 2010 CFR

2010-07-01

... agency's prepayment audit program? 102-118.410 Section 102-118.410 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION TRANSPORTATION 118-TRANSPORTATION PAYMENT AND AUDIT Prepayment Audits of Transportation Services Suspension of...