78 FR 64894 - Airworthiness Directives; B-N Group Ltd. Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-30

... requires a one-time inspection and functional test of the engine control cables and, depending on findings... Airworthiness Directives; B-N Group Ltd. Airplanes AGENCY: Federal Aviation Administration (FAA), Department of... airworthiness directive (AD) for B-N Group Ltd. Models BN-2, BN-2A, BN-2A-2, BN-2A-3, BN-2A-6, BN-2A-8, BN- 2A-9...

Chemically stabilized epitaxial wurtzite-BN thin film

NASA Astrophysics Data System (ADS)

Vishal, Badri; Singh, Rajendra; Chaturvedi, Abhishek; Sharma, Ankit; Sreedhara, M. B.; Sahu, Rajib; Bhat, Usha; Ramamurty, Upadrasta; Datta, Ranjan

2018-03-01

We report on the chemically stabilized epitaxial w-BN thin film grown on c-plane sapphire by pulsed laser deposition under slow kinetic condition. Traces of no other allotropes such as cubic (c) or hexagonal (h) BN phases are present. Sapphire substrate plays a significant role in stabilizing the metastable w-BN from h-BN target under unusual PLD growth condition involving low temperature and pressure and is explained based on density functional theory calculation. The hardness and the elastic modulus of the w-BN film are 37 & 339 GPa, respectively measured by indentation along <0001> direction. The results are extremely promising in advancing the microelectronic and mechanical tooling industry.

78 FR 21072 - Airworthiness Directives; B-N Group Ltd. Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-09

... Airworthiness Directives; B-N Group Ltd. Airplanes AGENCY: Federal Aviation Administration (FAA), Department of... airworthiness directive (AD) for B-N Group Ltd. Models BN-2, BN-2A, BN2A MK. III, BN2A MK. III-2, BN2A MK. III-3... further information by examining the MCAI in the AD docket. Relevant Service Information B-N Group Limited...

Ab initio multireference study of the BN molecule

NASA Technical Reports Server (NTRS)

Martin, J. M. L.; Lee, Timothy J.; Scuseria, Gustavo E.; Taylor, Peter R.

1992-01-01

The lowest 1Sigma(+) and 3Pi states of the BN molecule are studied using multireference configuration interaction (MRCI) and averaged coupled-pair functional (ACPF) methods and large atomic natural orbital (ANO) basis sets, as well as several coupled cluster methods. Our calculations strongly support a 3Pi ground state, but the a1Sigma(+) state lies only 381 +/- 100/cm higher. The a1Sigma(+) state wave function exhibits strong multireference character and, consequently, the predictions of the perturbationally-based single-reference CCSD(T) coupled cluster method are not as reliable in this case as the multireference results. The theoretical predictions for the spectroscopic constants of BN are in good agreement with experiment for the Chi3Pi state, but strongly suggest a misassignment of the fundamental vibrational frequency for the a1Sigma(+) state.

Tunable localized surface plasmon resonances in one-dimensional h-BN/graphene/h-BN quantum-well structure

NASA Astrophysics Data System (ADS)

Kaibiao, Zhang; Hong, Zhang; Xinlu, Cheng

2016-03-01

The graphene/hexagonal boron-nitride (h-BN) hybrid structure has emerged to extend the performance of graphene-based devices. Here, we investigate the tunable plasmon in one-dimensional h-BN/graphene/h-BN quantum-well structures. The analysis of optical response and field enhancement demonstrates that these systems exhibit a distinct quantum confinement effect for the collective oscillations. The intensity and frequency of the plasmon can be controlled by the barrier width and electrical doping. Moreover, the electron doping and the hole doping lead to very different results due to the asymmetric energy band. This graphene/h-BN hybrid structure may pave the way for future optoelectronic devices. Project supported by the National Natural Science Foundation of China (Grant Nos. 11474207 and 11374217) and the Scientific Research Fund of Sichuan University of Science and Engineering, China (Grant No. 2014PY07).

Micrometric BN powders used as catalyst support: influence of the precursor on the properties of the BN ceramic

NASA Astrophysics Data System (ADS)

Perdigon-Melon, José Antonio; Auroux, Aline; Guimon, Claude; Bonnetot, Bernard

2004-02-01

Thin powders and foams of boron nitride have been prepared from molecular precursors for use as noble metal supports in the catalytic conversion of methane. Different precursors originating from borazines have been tested. The best results were obtained using a precursor derived from trichloroborazine (TCB) which, after reacting with ammonia at room temperature and then thermolyzing up to 1800°C, led to BN powders with a specific area of more than 300 m 2 g -1 and a micrometric spherical texture. Comparable results were obtained using polyborazylene under similar conditions. Aminoborazine-derived precursors did not yield such high specific area ceramics but the BN microstructure resembled a foam with a crystallized skin and amorphous internal part. These differences were related to the chemical mechanism of the conversion of the precursor into BN. Polyhaloborazines and polyborazines yielded BN through gas-solid reactions whereas aminoborazine polymers could be kept waxy up to high temperatures, which favored the glassy foam. Catalysts composed of BN support and platinum have been prepared using two routes: from a mixture of precursor or by impregnation of a BN powder leading to very different catalysts.

Electrophoretic Deposition of Chitosan/h-BN and Chitosan/h-BN/TiO₂ Composite Coatings on Stainless Steel (316L) Substrates.

PubMed

Raddaha, Namir S; Cordero-Arias, Luis; Cabanas-Polo, Sandra; Virtanen, Sannakaisa; Roether, Judith A; Boccaccini, Aldo R

2014-03-04

This article presents the results of an experimental investigation designed to deposit chitosan/hexagonal boron nitride (h-BN) and chitosan/h-BN/titania (TiO₂) composites on SS316L substrates using electrophoretic deposition (EPD) for potential antibacterial applications. The influence of EPD parameters (voltage and deposition time) and relative concentrations of chitosan, h-BN and TiO₂ in suspension on deposition yield was studied. The composition and structure of deposited coatings were investigated by FTIR, XRD and SEM. It was observed that h-BN and TiO₂ particles were dispersed in the chitosan matrix through simultaneous deposition. The adhesion between the electrophoretic coatings and the stainless steel substrates was tested by using tape test technique, and the results showed that the adhesion strength corresponded to 3B and 4B classes. Corrosion resistance was evaluated by electrochemical polarization curves, indicating enhanced corrosion resistance of the chitosan/h-BN/TiO₂ and chitosan/h-BN coatings compared to the bare stainless steel substrate. In order to investigate the in-vitro inorganic bioactivity, coatings were immersed in simulated body fluid (SBF) for 28 days. FTIR and XRD results showed no formation of hydroxyapatite on the surface of chitosan/h-BN/TiO₂ and chitosan/h-BN coatings, which are therefore non bioactive but potentially useful as antibacterial coatings.

Diamond- cBN alloy: A universal cutting material

DOE PAGES

Wang, Pei; He, Duanwei; Wang, Liping; ...

2015-09-08

Diamond and cubic boron nitride ( cBN) as conventional superhard materials have found widespread industrial applications, but both have inherent limitations. Diamond is not suitable for high-speed cutting of ferrous materials due to its poor chemical inertness, while cBN is only about half as hard as diamond. Because of their affinity in structural lattices and covalent bonding character, diamond and cBN could form alloys that can potentially fill the performance gap. However, the idea has never been demonstrated because samples obtained in the previous studies were too small to be tested for their practical performance. Here, we report the synthesismore » and characterization of transparent bulk diamond- cBN alloy compacts whose diameters (3 mm) are sufficiently large for them to be processed into cutting tools. The testing results show that the diamond- cBN alloy has superior chemical inertness over polycrystalline diamond and higher hardness than single crystal cBN. In conclusion, high-speed cutting tests on hardened steel and granite suggest that diamond- cBN alloy is indeed a universal cutting material.« less

Diamond-cBN alloy: A universal cutting material

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

Wang, Pei; High Pressure Science and Engineering Center and Department of Physics and Astronomy, University of Nevada Las Vegas, Las Vegas, Nevada 89154; He, Duanwei, E-mail: duanweihe@scu.edu.cn

Diamond and cubic boron nitride (cBN) as conventional superhard materials have found widespread industrial applications, but both have inherent limitations. Diamond is not suitable for high-speed cutting of ferrous materials due to its poor chemical inertness, while cBN is only about half as hard as diamond. Because of their affinity in structural lattices and covalent bonding character, diamond and cBN could form alloys that can potentially fill the performance gap. However, the idea has never been demonstrated because samples obtained in the previous studies were too small to be tested for their practical performance. Here, we report the synthesis andmore » characterization of transparent bulk diamond-cBN alloy compacts whose diameters (3 mm) are sufficiently large for them to be processed into cutting tools. The testing results show that the diamond-cBN alloy has superior chemical inertness over polycrystalline diamond and higher hardness than single crystal cBN. High-speed cutting tests on hardened steel and granite suggest that diamond-cBN alloy is indeed a universal cutting material.« less

Diamond- cBN alloy: A universal cutting material

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

Wang, Pei; He, Duanwei; Wang, Liping

Diamond and cubic boron nitride ( cBN) as conventional superhard materials have found widespread industrial applications, but both have inherent limitations. Diamond is not suitable for high-speed cutting of ferrous materials due to its poor chemical inertness, while cBN is only about half as hard as diamond. Because of their affinity in structural lattices and covalent bonding character, diamond and cBN could form alloys that can potentially fill the performance gap. However, the idea has never been demonstrated because samples obtained in the previous studies were too small to be tested for their practical performance. Here, we report the synthesismore » and characterization of transparent bulk diamond- cBN alloy compacts whose diameters (3 mm) are sufficiently large for them to be processed into cutting tools. The testing results show that the diamond- cBN alloy has superior chemical inertness over polycrystalline diamond and higher hardness than single crystal cBN. In conclusion, high-speed cutting tests on hardened steel and granite suggest that diamond- cBN alloy is indeed a universal cutting material.« less

Electron Excess Doping and Effective Schottky Barrier Reduction on the MoS2/h-BN Heterostructure.

PubMed

Joo, Min-Kyu; Moon, Byoung Hee; Ji, Hyunjin; Han, Gang Hee; Kim, Hyun; Lee, Gwanmu; Lim, Seong Chu; Suh, Dongseok; Lee, Young Hee

2016-10-12

Layered hexagonal boron nitride (h-BN) thin film is a dielectric that surpasses carrier mobility by reducing charge scattering with silicon oxide in diverse electronics formed with graphene and transition metal dichalcogenides. However, the h-BN effect on electron doping concentration and Schottky barrier is little known. Here, we report that use of h-BN thin film as a substrate for monolayer MoS 2 can induce ∼6.5 × 10 11 cm -2 electron doping at room temperature which was determined using theoretical flat band model and interface trap density. The saturated excess electron concentration of MoS 2 on h-BN was found to be ∼5 × 10 13 cm -2 at high temperature and was significantly reduced at low temperature. Further, the inserted h-BN enables us to reduce the Coulombic charge scattering in MoS 2 /h-BN and lower the effective Schottky barrier height by a factor of 3, which gives rise to four times enhanced the field-effect carrier mobility and an emergence of metal-insulator transition at a much lower charge density of ∼1.0 × 10 12 cm -2 (T = 25 K). The reduced effective Schottky barrier height in MoS 2 /h-BN is attributed to the decreased effective work function of MoS 2 arisen from h-BN induced n-doping and the reduced effective metal work function due to dipole moments originated from fixed charges in SiO 2 .

Stability and electronic properties of Gex(BN)y monolayers

NASA Astrophysics Data System (ADS)

Freitas, A.; Machado, L. D.; Tromer, R. M.; Bezerra, C. G.; Azevedo, S.

2017-10-01

In this work, we employ ab initio simulations to propose a new class of monolayers with stoichiometry Gex(BN)y . These monolayers belong to a family of 2D materials combining B, N and group IV atoms, such as BxCyNz and SixByNz . We calculated the formation energy for ten atomic arrangements, and found that it increases when the number of Bsbnd Ge and Nsbnd Ge bonds increases, and decreases when the number of Bsbnd N and Gesbnd Ge bonds increases. We found that the lowest energy monolayer presented a Ge2 BN stoichiometry, and maximized the number of Bsbnd N and Gesbnd Ge bonds. This structure also presented mixed sp2 and sp3 bonds and out-of-plane buckling. Moreover, it remained stable in our ab initio molecular dynamics simulations carried out at T = 300 K. The calculated electronic properties revealed that Gex(BN)y monolayers might present conductor or semiconductor behavior, with band gaps ranging from 0.0 to 0.74 eV, depending on atomic arrangement. Tunable values of band gap can be useful in applications. In optoelectronics, for instance, this property might be employed to control absorbed light wavelengths. Our calculations add a new class of monolayers to the increasing library of 2D materials.

Synthesis and Characterization of Quenched and Crystalline Phases: Q-Carbon, Q-BN, Diamond and Phase-Pure c-BN

NASA Astrophysics Data System (ADS)

Bhaumik, Anagh; Narayan, Jagdish

2018-04-01

We report the synthesis and characterization of quenched (Q-carbon and Q-BN) and crystalline (diamond and c-BN) phases using a non-equilibrium technique. These phases are formed as a result of the melting and subsequent quenching of amorphous carbon and nanocrystalline h-BN in a super undercooled state by using high-power nanosecond laser pulses. Pulsed laser annealing also leads to the formation of nanoneedles, microneedles and single-crystal thin films of diamond and c-BN. This formation is dependent on the nucleation and growth times, which are controlled by laser energy density and thermal conductivities of substrate and as-deposited thin film. The diamond nuclei present in the Q-carbon structure ( 80% sp 3) can also be grown to larger sizes using the equilibrium hot filament chemical vapor deposition process. The texture of diamond and c-BN crystals is <111> under epitaxial growth and <110> under rapid unseeded crystallization. Our nanosecond laser processing opens up a roadmap to the fabrication of novel phases on heat-sensitive substrates.

Electrophoretic Deposition of Chitosan/h-BN and Chitosan/h-BN/TiO2 Composite Coatings on Stainless Steel (316L) Substrates

PubMed Central

Raddaha, Namir S.; Cordero-Arias, Luis; Cabanas-Polo, Sandra; Virtanen, Sannakaisa; Roether, Judith A.; Boccaccini, Aldo R.

2014-01-01

This article presents the results of an experimental investigation designed to deposit chitosan/hexagonal boron nitride (h-BN) and chitosan/h-BN/titania (TiO2) composites on SS316L substrates using electrophoretic deposition (EPD) for potential antibacterial applications. The influence of EPD parameters (voltage and deposition time) and relative concentrations of chitosan, h-BN and TiO2 in suspension on deposition yield was studied. The composition and structure of deposited coatings were investigated by FTIR, XRD and SEM. It was observed that h-BN and TiO2 particles were dispersed in the chitosan matrix through simultaneous deposition. The adhesion between the electrophoretic coatings and the stainless steel substrates was tested by using tape test technique, and the results showed that the adhesion strength corresponded to 3B and 4B classes. Corrosion resistance was evaluated by electrochemical polarization curves, indicating enhanced corrosion resistance of the chitosan/h-BN/TiO2 and chitosan/h-BN coatings compared to the bare stainless steel substrate. In order to investigate the in-vitro inorganic bioactivity, coatings were immersed in simulated body fluid (SBF) for 28 days. FTIR and XRD results showed no formation of hydroxyapatite on the surface of chitosan/h-BN/TiO2 and chitosan/h-BN coatings, which are therefore non bioactive but potentially useful as antibacterial coatings. PMID:28788541

Structure and luminescence properties of 10-BN sheets

NASA Astrophysics Data System (ADS)

Han, Wei-Qiang; Liu, Lijia; Sham, T. K.; Liu, Zhenxian

2012-10-01

Isotopic 10BN sheets were first prepared using graphene sheets as templates to react with 10B2O3. The edge-areas of BN sheets have much higher oxygen-doping ratios compared to other areas. The emission peak of X-ray excited optical luminescence spectra of the 10BN-sheets is broader and red-shifted because of the isotopic effect. A broad violet-blue emission at a wavelength centered at ~400 nm is assigned to the defect emission due to oxygen-doping and defects in the BN network.

Strain, stabilities and electronic properties of hexagonal BN bilayers

NASA Astrophysics Data System (ADS)

Fujimoto, Yoshitaka; Saito, Susumu

Hexagonal boron nitride (h-BN) atomic layers have been regarded as fascinating materials both scientifically and technologically due to the sizable band gap. This sizable band-gap nature of the h-BN atomic layers would provide not only new physical properties but also novel nano- and/or opto-electronics applications. Here, we study the first-principles density-functional study that clarifies the biaxial strain effects on the energetics and the electronic properties of h-BN bilayers. We show that the band gaps of the h-BN bilayers are tunable by applying strains. Furthermore, we show that the biaxial strains can produce a transition from indirect to direct band gaps of the h-BN bilayer. We also discuss that both AA and AB stacking patterns of h-BN bilayer become feasible structures because h-BN bilayers possess two different directions in the stacking patterns. Supported by MEXT Elements Strategy Initiative to Form Core Research Center through Tokodai Institute for Element Strategy, JSPS KAKENHI Grant Numbers JP26390062 and JP25107005.

How lithium atoms affect the first hyperpolarizability of BN edge-doped graphene.

PubMed

Song, Yao-Dong; Wu, Li-Ming; Chen, Qiao-Ling; Liu, Fa-Kun; Tang, Xiao-Wen

2016-01-01

How do lithium atoms affect the first hyperpolarizability (β0) of boron-nitrogen (BN) edge-doped graphene. In this work, using pentacene as graphene model, Lin@BN-1 edge-doped pentacene and Lin@BN-2 edge-doped pentacene (n = 1, 5) were designed to study this problem. First, two models (BN-1 edge-doped pentacene, and BN-2 edge-doped pentacene ) were formed by doping the BN into the pentacene with different order, and then Li@BN-1 edge-doped pentacene and Li@ BN-2 edge-doped pentacene were obtained by substituting the H atom in BN edge-doped pentacene with a Li atom. The results show that the first hyperpolarizabilities of BN-1 edge-doped pentacene and Li@BN-1 edge-doped pentacene were 4059 a.u. and 6249 a.u., respectively; the first hyperpolarizabilities of BN-2 edge-doped pentacene and Li@BN-2 edge-doped pentacene were 2491 a.u. and 4265 a.u., respectively. The results indicate that the effect of Li substitution is to greatly increase the β0 value. To further enhance the first hyperpolarizability, Li5@ BN-1 edge-doped pentacene and Li5@BN-2 edge-doped pentacene were designed, and were found to exhibit considerably larger first hyperpolarizabilities (β0) (12,112 a.u. and 7921a.u., respectively). This work may inspire further study of the nonlinear properties of BN edge-doped graphene.

Boron Nitride Obtained from Molecular Precursors: Aminoboranes Used as a BN Source for Coatings, Matrix, and Si 3N 4-BN Composite Ceramic Preparation

NASA Astrophysics Data System (ADS)

Thévenot, F.; Doche, C.; Mongeot, H.; Guilhon, F.; Miele, P.; Cornu, D.; Bonnetot, B.

1997-10-01

Aminoboranes, pure or partially converted into aminoborazines using thermal or aminolysis polymerization, have been used as boron nitride precursors. An amorphous BN preceramic is obtained when pyrolysed up to 1000°C that can be stabilized using further annealing up to 1400°C or crystallized into h-BN above 1700°C. These molecular precursors have been used to prepare carbon fiber/BN matrix microcomposites to get an efficient BN coating on graphite and as a BN source in Si3N4/BN composite ceramic. The properties of these new types of samples have been compared with those obtained by classical processes. The boron nitride obtained from these precursors is a good sintering agent during the hot-pressing of the samples. However, the crystallinity of BN, even sintered up to 1800°C, remains poor. In fact, most of the mechanical properties of the composite ceramic (density, porosity, hardness) are clearly improved and the aminoboranes can be considered as convenient boron nitride sources and helpful sintering agents in hot-pressing technology.

Nanostructured BN-Mg composites: features of interface bonding and mechanical properties.

PubMed

Kvashnin, Dmitry G; Krasheninnikov, Arkady V; Shtansky, Dmitry; Sorokin, Pavel B; Golberg, Dmitri

2016-01-14

Magnesium (Mg) is one of the lightest industrially used metals. However, wide applications of Mg-based components require a substantial enhancement of their mechanical characteristics. This can be achieved by introducing small particles or fibers into the metal matrix. Using first-principles calculations, we investigate the stability and mechanical properties of a nanocomposite made of magnesium reinforced with boron nitride (BN) nanostructures (BN nanotubes and BN monolayers). We show that boron vacancies at the BN/Mg interface lead to a substantial increase in BN/Mg bonding establishing an efficient route towards the development of BN/Mg composite materials with enhanced mechanical properties.

Electronic structure of graphene- and BN-supported phosphorene

NASA Astrophysics Data System (ADS)

Davletshin, Artur R.; Ustiuzhanina, Svetlana V.; Kistanov, Andrey A.; Saadatmand, Danial; Dmitriev, Sergey V.; Zhou, Kun; Korznikova, Elena A.

2018-04-01

By using first-principles calculations, the effects of graphene and boron nitride (BN) substrates on the electronic properties of phosphorene are studied. Graphene-supported phosphorene is found to be metallic, while the BN-supported phosphorene is a semiconductor with a moderate band gap of 1.02 eV. Furthermore, the effects of the van der Waals interactions between the phosphorene and graphene or BN layers by means of the interlayer distance change are investigated. It is shown that the interlayer distance change leads to significant band gap size modulations and direct-indirect band gap transitions in the phosphorene-BN heterostructure. The presented band gap engineering of phosphorene may be a powerful technique for the fabrication of high-performance phosphorene-based nanodevices.

Thermal Shock Resistance of Si3N4/h -BN Composites Prepared via Catalytic Reaction-Bonding Route

NASA Astrophysics Data System (ADS)

Yang, Wanli; Peng, Zhigang; Dai, Lina; Shi, Zhongqi; Jin, Zhihao

2017-09-01

Si3N4/h-BN ceramic matrix composites were prepared via a catalytic reaction-bonding route by using ZrO2 as nitridation catalyst, and the water quenching (fast cooling) and molten aluminum quenching tests (fast heating) were carried out to evaluate the thermal shock resistance of the composites. The results showed that the thermal shock resistance was improved obviously with the increase in h-BN content, and the critical thermal shock temperature difference (Δ T c) reaches as high as 780 °C when the h-BN content was 30 wt.%. The improvement of thermal shock resistance of the composites was mainly due to the crack tending to quasi static propagating at weak bonding interface between Si3N4 and h-BN with the increase in h-BN content. For the molten aluminum quenching test, the residual strength showed no obvious decrease compared with water quenching test, which could be caused by the mild stress condition on the surface. In addition, a calculated parameter, volumetric crack density ( N f), was presented to quantitative evaluating the thermal shock resistance of the composites in contrast to the conventional R parameter.

Tunable magnetotransport in Fe/hBN/graphene/hBN/Pt(Fe) epitaxial multilayers

NASA Astrophysics Data System (ADS)

Magnus Ukpong, Aniekan

2018-03-01

Theoretical and computational analysis of the magnetotransport properties and spin-transfer torque field-induced switching of magnetization density in vertically-stacked multilayers is presented. Using epitaxially-capped free layers of Pt and Fe, atom-resolved magnetic moments and spin-transfer torques are computed at finite bias. The calculations are performed within linear response approximation to the spin-density reformulation of the van der Waals density functional theory. Dynamical spin excitations are computed as a function of a spin-transfer torque induced magnetic field along the magnetic easy axis, and the corresponding spin polarization perpendicular to the easy axis is obtained. Bias-dependent giant anisotropic magnetoresistance of up to 3200% is obtained in the nonmagnetic-metal-capped Fe/hBN/graphene/hBN/Pt multilayer architecture. Since this specific heterostructure is not yet fabricated and characterized, the predicted high performance has not been demonstrated experimentally. Nevertheless, similar calculations performed on the Fe/hBN/Co stack show that the tunneling magnetoresistance obtained at the Fermi-level is in excellent agreement with results of recent magnetotransport measurements on magnetic tunnel junctions that contain the monolayer hBN tunnel region. The magnitude of the spin-transfer torque is found to increase as the tunneling spin current increases, and this activates the magnetization switching process due to increased charge accumulation. This mechanism causes substantial spin backflow, which manifests as rapid undulations in the bias-dependent tunneling spin currents. The implication of these findings on the design of nanoscale spintronic devices with spin-transfer torque tunable magnetization density is discussed. Insights derived from this study are expected to enhance the prospects for developing and integrating artificially assembled van der Waals multilayer heterostructures as the preferred material platform for efficient

What's Going on Around BN

NASA Technical Reports Server (NTRS)

Erickson, Edwin; Colgan, S. W. J.; Schultz, A. S. B.; Simpson, J. P.; Burton, M. G.; Kaufman, M. J.; Young, E. T.; Stolovy, S.

2005-01-01

The Becklin-Neugebauer object, discovered in observations made by Eric Becklin as a graduate student, is the brightest mid-infrared source outside the solar system, and a beacon in the nearest region of massive star formation. Using NICMOS on HST, we have obtained near infrared photometric, spectroscopic, and polarimetric images of the region immediately around BN. These images, with resolutions < -0.2", reveal remarkable morphologies, shock details, new young stellar objects, faint stars with variable intensities, and outflow features. We will summarize these results and inferences regarding the shock properties, illuminating sources of the nebulosity, and IRc sources near BN.

Side-gate modulation effects on high-quality BN-Graphene-BN nanoribbon capacitors

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

Wang, Yang; Chen, Xiaolong; Ye, Weiguang

High-quality BN-Graphene-BN nanoribbon capacitors with double side-gates of graphene have been experimentally realized. The double side-gates can effectively modulate the electronic properties of graphene nanoribbon capacitors. By applying anti-symmetric side-gate voltages, we observed significant upward shifting and flattening of the V-shaped capacitance curve near the charge neutrality point. Symmetric side-gate voltages, however, only resulted in tilted upward shifting along the opposite direction of applied gate voltages. These modulation effects followed the behavior of graphene nanoribbons predicted theoretically for metallic side-gate modulation. The negative quantum capacitance phenomenon predicted by numerical simulations for graphene nanoribbons modulated by graphene side-gates was not observed,more » possibly due to the weakened interactions between the graphene nanoribbon and side-gate electrodes caused by the Ga{sup +} beam etching process.« less

Electronic Properties of Curved and Defective 2-D BN Nanostructures

NASA Astrophysics Data System (ADS)

Beach, Kory; Terrones, Humberto; Raeliarijaona, Aldo; Siegel, Ross; Florio, Fred

Density functional theory (DFT) with local density approximation (LDA) pseudopotentials is used to calculate the band structure and density of states of various novel 2-D BN nanostructures. Three types of systems are studied: Schwarzites, a Haeckelite, and an h-BN monolayer. Schwarzites are negatively curved structures in which the curvature is due to the introduction of octagonal rings of alternating boron and nitrogen atoms. In particular, three families of Schwarzites are analyzed: P, G and IWP. The Haeckelites on the other hand, are flat layers composed of squares and octagons of BN. It is found that all these BN allotropes are metastable in which the band gap is direct and smaller than the most stable system, h-BN. National Science Foundation (EFRI-1433311).

Radiometric characterization of an LWIR, type-II strained layer superlattice pBiBn photodetector

NASA Astrophysics Data System (ADS)

Treider, L. A.; Morath, C. P.; Cowan, V. M.; Tian, Z. B.; Krishna, S.

2015-05-01

Type-II Strained Layer Superlattice (T2SLS) infrared photodetectors have been in development over the last decade. T2SLS offers a theoretically longer Auger recombination lifetime than traditional mercury cadmium telluride (MCT), which presumably translates to infrared detectors with lower dark-current and higher operating temperatures. However, these improvements did not materialize due to the presence of Shockley-Read-Hall (SRH) defects in T2SLSs, which limits the recombination lifetime well below the Auger-limit. With the recent introduction of the pBiBn, and other similar unipolar barrier detectors, T2SLS material has seen renewed interest since these designs ideally eliminate the SRH-generation and surface currents while retaining the other potential advantages of T2SLS: reduced manufacturing cost, better availability of a durable state-side manufacturing base, ability to tune the cutoff wavelength, and better uniformity. Here, an electrical and optical characterization of a long-wave, pBiBn detector with a T2SLS absorber is presented. Dark-current, spectral response and optical response were measured as functions of temperature and bias. Activation energy was then determined as a function of bias from the dark-current measurements. Quantum efficiency was also determined as a function of bias from the optical response measurements. Additionally, noise spectrum measurements were taken as a function of bias.

The FTD-like syndrome causing TREM2 T66M mutation impairs microglia function, brain perfusion, and glucose metabolism.

PubMed

Kleinberger, Gernot; Brendel, Matthias; Mracsko, Eva; Wefers, Benedikt; Groeneweg, Linda; Xiang, Xianyuan; Focke, Carola; Deußing, Maximilian; Suárez-Calvet, Marc; Mazaheri, Fargol; Parhizkar, Samira; Pettkus, Nadine; Wurst, Wolfgang; Feederle, Regina; Bartenstein, Peter; Mueggler, Thomas; Arzberger, Thomas; Knuesel, Irene; Rominger, Axel; Haass, Christian

2017-07-03

Genetic variants in the triggering receptor expressed on myeloid cells 2 (TREM2) increase the risk for several neurodegenerative diseases including Alzheimer's disease and frontotemporal dementia (FTD). Homozygous TREM2 missense mutations, such as p.T66M, lead to the FTD-like syndrome, but how they cause pathology is unknown. Using CRISPR/Cas9 genome editing, we generated a knock-in mouse model for the disease-associated Trem2 p.T66M mutation. Consistent with a loss-of-function mutation, we observe an intracellular accumulation of immature mutant Trem2 and reduced generation of soluble Trem2 similar to patients with the homozygous p.T66M mutation. Trem2 p.T66M knock-in mice show delayed resolution of inflammation upon in vivo lipopolysaccharide stimulation and cultured macrophages display significantly reduced phagocytic activity. Immunohistochemistry together with in vivo TSPO small animal positron emission tomography (μPET) demonstrates an age-dependent reduction in microglial activity. Surprisingly, perfusion magnetic resonance imaging and FDG-μPET imaging reveal a significant reduction in cerebral blood flow and brain glucose metabolism. Thus, we demonstrate that a TREM2 loss-of-function mutation causes brain-wide metabolic alterations pointing toward a possible function of microglia in regulating brain glucose metabolism. © 2017 The Authors.

Pnma-BN: Another Boron Nitride Polymorph with Interesting Physical Properties

PubMed Central

Ma, Zhenyang; Han, Zheng; Liu, Xuhong; Yu, Xinhai; Wang, Dayun; Tian, Yi

2016-01-01

Structural, mechanical, electronic properties, and stability of boron nitride (BN) in Pnma structure were studied using first-principles calculations by Cambridge Serial Total Energy Package (CASTEP) plane-wave code, and the calculations were performed with the local density approximation and generalized gradient approximation in the form of Perdew–Burke–Ernzerhof. This BN, called Pnma-BN, contains four boron atoms and four nitrogen atoms buckled through sp3-hybridized bonds in an orthorhombic symmetry unit cell with Space group of Pnma. Pnma-BN is energetically stable, mechanically stable, and dynamically stable at ambient pressure and high pressure. The calculated Pugh ratio and Poisson’s ratio revealed that Pnma-BN is brittle, and Pnma-BN is found to turn brittle to ductile (~94 GPa) in this pressure range. It shows a higher mechanical anisotropy in Poisson’s ratio, shear modulus, Young’s modulus, and the universal elastic anisotropy index AU. Band structure calculations indicate that Pnma-BN is an insulator with indirect band gap of 7.18 eV. The most extraordinary thing is that the band gap increases first and then decreases with the increase of pressure from 0 to 60 GPa, and from 60 to 100 GPa, the band gap increases first and then decreases again. PMID:28336837

78 FR 38544 - Airworthiness Directives; B-N Group Ltd. Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-27

... Airworthiness Directives; B-N Group Ltd. Airplanes AGENCY: Federal Aviation Administration (FAA), Department of Transportation (DOT). ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for all B-N... adding the following new AD: 2013-13-02 B-N Group Ltd.: Amendment 39-17490; Docket No. FAA-2013- 0314...

Investigation on two abnormal phenomena about thermal conductivity enhancement of BN/EG nanofluids.

PubMed

Li, Yanjiao; Zhou, Jing'en; Luo, Zhifeng; Tung, Simon; Schneider, Eric; Wu, Jiangtao; Li, Xiaojing

2011-07-09

The thermal conductivity of boron nitride/ethylene glycol (BN/EG) nanofluids was investigated by transient hot-wire method and two abnormal phenomena was reported. One is the abnormal higher thermal conductivity enhancement for BN/EG nanofluids at very low-volume fraction of particles, and the other is the thermal conductivity enhancement of BN/EG nanofluids synthesized with large BN nanoparticles (140 nm) which is higher than that synthesized with small BN nanoparticles (70 nm). The chain-like loose aggregation of nanoparticles is responsible for the abnormal increment of thermal conductivity enhancement for the BN/EG nanofluids at very low particles volume fraction. And the difference in specific surface area and aspect ratio of BN nanoparticles may be the main reasons for the abnormal difference between thermal conductivity enhancements for BN/EG nanofluids prepared with 140- and 70-nm BN nanoparticles, respectively.

Overexpression of BnWRKY33 in oilseed rape enhances resistance to Sclerotinia sclerotiorum.

PubMed

Wang, Zheng; Fang, Hedi; Chen, Yu; Chen, Keping; Li, Guanying; Gu, Shoulai; Tan, Xiaoli

2014-09-01

Sclerotinia sclerotiorum causes a devastating disease in oilseed rape (Brassica napus) resulting in a tremendous yield loss worldwide. Studies on various host-pathogen interactions have shown that plant WRKY transcription factors are essential for defence. For the B. napus-S. sclerotiorum interaction, little direct evidence has been found with regard to the biological roles of specific WRKY genes in host resistance. In this study, we isolated a B. napus WRKY gene, BnWRKY33, and found that the gene is highly responsive to S. sclerotiorum infection. Transgenic B. napus plants overexpressing BnWRKY33 showed markedly enhanced resistance to S. sclerotiorum, constitutive activation of the expression of BnPR1 and BnPDF1.2, and inhibition of H2 O2 accumulation in response to pathogen infection. Further, we isolated a mitogen-activated protein (MAP) kinase substrate gene, BnMKS1, and found that not only can BnWRKY33 interact with BnMKS1, which can also interact with BnMPK4, using the yeast two-hybrid assay, consistent with their collective nuclear localization, but also BnWRKY33, BnMKS1 and BnMPK4 are substantially and synergistically expressed in response to S. sclerotiorum infection. In contrast, the three genes showed differential expression in response to phytohormone treatments. Together, these results suggest that BnWRKY33 plays an important role in B. napus defence to S. sclerotiorum, which is most probably associated with the activation of the salicylic acid (SA)- and jasmonic acid (JA)-mediated defence response and inhibition of H2 O2 accumulation, and we propose a potential mechanism in which BnMPK4-BnMKS1-BnWRKY33 exist in a nuclear localized complex to regulate resistance to S. sclerotiorum in oilseed rape. © 2014 BSPP AND JOHN WILEY & SONS LTD.

Wafer scale BN on sapphire substrates for improved graphene transport.

PubMed

Vangala, Shivashankar; Siegel, Gene; Prusnick, Timothy; Snure, Michael

2018-06-11

Wafer scale (2") BN grown by metal organic chemical vapor deposition (MOCVD) on sapphire was examined as a weakly interacting dielectric substrate for graphene, demonstrating improved transport properties over conventional sapphire and SiO 2 /Si substrates. Chemical vapor deposition grown graphene was transferred to BN/sapphire substrates for evaluation of more than 30 samples using Raman and Hall effects measurements. A more than 2x increase in Hall mobility and 10x reduction in sheet carrier density was measured for graphene on BN/sapphire compared to sapphire substrates. Through control of the MOCVD process, BN films with roughness ranging from <0.1 nm to >1 nm were grown and used to study the effects of substrate roughness on graphene transport. Arrays of graphene field effect transistors were fabricated on 2" BN/sapphire substrates demonstrating scalability and device performance enhancement.

Purification and characterization of the bacteriocin Thuricin Bn1 produced by Bacillus thuringiensis subsp. kurstaki Bn1 isolated from a hazelnut pest.

PubMed

Ugras, Serpil; Sezen, Kazim; Kati, Hatice; Demirbag, Zihni

2013-02-01

A novel bioactive molecule produced by Bacillus thuringiensis subsp. kurstaki Bn1 (Bt-Bn1), isolated from a common pest of hazelnut, Balaninus nucum L. (Coleoptera: Curculionidae), was determined, purified, and characterized in this study. The Bt-Bn1 strain was investigated for antibacterial activity with an agar spot assay and well diffusion assay against B. cereus, B. weinhenstephenensis, L. monocytogenes, P. savastanoi, P. syringae, P. lemoignei, and many other B. thuringiensis strains. The production of bioactive molecule was determined at the early logarithmic phase in the growth cycle of strain Bt-Bn1 and its production continued until the beginning of the stationary phase. The mode of action of this molecule displayed bacteriocidal or bacteriolytic effect depending on the concentration. The bioactive molecule was purified 78-fold from the bacteria supernatant with ammonium sulfate precipitation, dialysis, ultrafiltration, gel filtration chromatography, and HPLC, respectively. The molecular mass of this molecule was estimated via SDS-PAGE and confirmed by the ESI-TOFMS as 3,139 Da. The bioactive molecule was also determined to be a heat-stable, pH-stable (range 6-8), and proteinase K sensitive antibacterial peptide, similar to bacteriocins. Based on all characteristics determined in this study, the purified bacteriocin was named as thuricin Bn1 because of the similarities to the previously identified thuricin-like bacteriocin produced by the various B. thuringiensis strains. Plasmid elution studies showed that gene responsible for the production of thuricin Bn1 is located on the chromosome of Bt-Bn1. Therefore, it is a novel bacteriocin and the first recorded one produced by an insect originated bacterium. It has potential usage for the control of many different pathogenic and spoilage bacteria in the food industry, agriculture, and various other areas.

On the Stability of c-BN-Reinforcing Particles in Ceramic Matrix Materials

PubMed Central

Wolfrum, Anne-Kathrin; Michaelis, Alexander; Herrmann, Mathias

2018-01-01

Cubic boron nitride (c-BN) composites produced at high pressures and temperatures are widely used as cutting tool materials. The advent of new, effective pressure-assisted densification methods, such as spark plasma sintering (SPS), has stimulated attempts to produce these composites at low pressures. Under low-pressure conditions, however, transformation of c-BN to the soft hexagonal BN (h-BN) phase can occur, with a strong deterioration in hardness and wear. In the present work, the influence of secondary phases (B2O3, Si3N4, and oxide glasses) on the transformation of c-BN was studied in the temperature range between 1100 °C and 1575 °C. The different heat treated c-BN particles and c-BN composites were analyzed by SEM, X-ray diffraction, and Raman spectroscopy. The transformation mechanism was found to be kinetically controlled solution–diffusion–precipitation. Given a sufficiently low liquid phase viscosity, the transformation could be observed at temperatures as low as 1200 °C for the c-BN–glass composites. In contrast, no transformation was found at temperatures up to 1575 °C when no liquid oxide phase is present in the composite. The results were compared with previous studies concerning the c-BN stability and the c-BN phase diagram. PMID:29414847

Deposition Of Cubic BN On Diamond Interlayers

NASA Technical Reports Server (NTRS)

Ong, Tiong P.; Shing, Yuh-Han

1994-01-01

Thin films of polycrystalline, pure, cubic boron nitride (c-BN) formed on various substrates, according to proposal, by chemical vapor deposition onto interlayers of polycrystalline diamond. Substrate materials include metals, semiconductors, and insulators. Typical substrates include metal-cutting tools: polycrystalline c-BN coats advantageous for cutting ferrous materials and for use in highly oxidizing environments-applications in which diamond coats tend to dissolve in iron or be oxidized, respectively.

Theoretical analysis of nBn infrared photodetectors

NASA Astrophysics Data System (ADS)

Ting, David Z.; Soibel, Alexander; Khoshakhlagh, Arezou; Gunapala, Sarath D.

2017-09-01

The depletion and surface leakage dark current suppression properties of unipolar barrier device architectures such as the nBn have been highly beneficial for III-V semiconductor-based infrared detectors. Using a one-dimensional drift-diffusion model, we theoretically examine the effects of contact doping, minority carrier lifetime, and absorber doping on the dark current characteristics of nBn detectors to explore some basic aspects of their operation. We found that in a properly designed nBn detector with highly doped excluding contacts the minority carriers are extracted to nonequilibrium levels under reverse bias in the same manner as the high operating temperature (HOT) detector structure. Longer absorber Shockley-Read-Hall (SRH) lifetimes result in lower diffusion and depletion dark currents. Higher absorber doping can also lead to lower diffusion and depletion dark currents, but the benefit should be weighted against the possibility of reduced diffusion length due to shortened SRH lifetime. We also briefly examined nBn structures with unintended minority carrier blocking barriers due to excessive n-doping in the unipolar electron barrier, or due to a positive valence band offset between the barrier and the absorber. Both types of hole blocking structures lead to higher turn-on bias, although barrier n-doping could help suppress depletion dark current.

One-pot synthesis of h-BN fullerenes usinsg a graphene oxide template

NASA Astrophysics Data System (ADS)

Kim, Sang Sub; Khai, Tran Van; Kwon, Yong Jung; Katoch, Akash; Wu, Ping; Kim, Hyoun Woo

2015-09-01

Hexagonal-boron nitride ( h-BN) fullerenes were synthesized from a graphene oxide (GO) template by simultaneously heating the GO and B2O3 in the presence of NH3 gas. Transmission electron microscopy (TEM) observations revealed that a considerable amount of product had a fullerene-like nanostructure. Typical BN fullerenes have a polyhedral shape, being hollow nanocages. Lattice-resolved TEM and X-ray diffraction consistently demonstrated the formation of h-BN fullerenes. The FTIR spectrum exhibited absorption bands at approximately 800 and 1378 cm-1, which were related to the h-BN structure. The Raman spectra exhibited peaks at 1368 and 1399 cm-1, which can be related to BN sheets and BN fullerenes, respectively. The photoluminescence spectrum of the h-BN fullerenes taken at 8 K exhibited intense white-light emission. To reveal the origin of the broad emission band, which could be a superimposition of several peaks, we used a deconvolution procedure based on Gaussian functions. We proposed a growth mechanism of the h-BN fullerenes and verified it with a thermodynamic calculation. This work provides a cost-effective approach to synthesize fullerene-type boron nitride on a production scale.

Microstructures of BN/SiC coatings on nicalon fibers

NASA Technical Reports Server (NTRS)

Dickerson, R. M.; Singh, M.

1995-01-01

The microstructures of Nicalon silicon carbide (SiC) fibers and layered coatings of boron nitride (BN) followed by chemical vapor infiltrated silicon carbide (CVI-SiC) were characterized using optical and electron microscopy. Two different precursors and reactions were used to produce the BN layers while the deposition of CVI silicon carbide was nearly identical. Coated tows were examined in cross-section to characterize the chemistry and structures of the constituents and the interfaces. One BN precursor yielded three sublayers while the other gave a relatively homogeneous nanocrystalline layer.

Raman spectroscopy and time-resolved photoluminescence of BN and BxCyNz nanotubes

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

Wu, J.; Han, Wei-Qiang; Walukiewicz, W.

2004-01-21

We report Raman and time-resolved photoluminescence spectroscopic studies of multiwalled BN and B{sub x}C{sub y}N{sub z} nanotubes. The Raman spectroscopy shows that the as-grown B{sub x}C{sub y}N{sub z} charge recombination, respectively. Comparison of the photoluminescence of BN nanotubes to that decay process is characterized by two time constants that are attributed to intra- and inter-BN sheet nanotubes as predicted by theory. nanotubes are radially phase separated into BN shells and carbon shells. The photoluminescence of hexagonal BN is consistent with the existence of a spatially indirect band gap in multi-walled BN.

I-V characteristics of graphene nanoribbon/h-BN heterojunctions and resonant tunneling.

PubMed

Wakai, Taiga; Sakamoto, Shoichi; Tomiya, Mitsuyoshi

2018-07-04

We present the first principle calculations of the electrical properties of graphene sheet/h-BN heterojunction (GS/h-BN) and 11-armchair graphene nanoribbon/h-BN heterojunction (11-AGNR/h-BN), which are carried out using the density functional theory (DFT) method and the non-equilibrium Green's function (NEGF) technique. Since 11-AGNR belongs to the conductive (3n-1)-family of AGNR, both are metallic nanomaterials with two transverse arrays of h-BN, which is a wide-gap semi-conductor. The two h-BN arrays act as double barriers. The transmission functions (TF) and I-[Formula: see text] characteristics of GS/h-BN and 11-AGNR/h-BN are calculated by DFT and NEGF, and they show that quantum double barrier tunneling occurs. The TF becomes very spiky in both materials, and it leads to step-wise I-[Formula: see text] characteristics rather than negative resistance, which is the typical behavior of double barriers in semiconductors. The results of our first principle calculations are also compared with 1D Dirac equation model for the double barrier system. The model explains most of the peaks of the transmission functions nearby the Fermi energy quite well. They are due to quantum tunneling.

Ultrahard stitching of nanotwinned diamond and cubic boron nitride in C 2-BN composite

DOE PAGES

Liu, Xiaobing; Chen, Xin; Ma, Hong-An; ...

2016-07-27

Materials combining the hardness and strength of diamond with the higher thermal stability of cubic boron nitride (cBN) have broad potential value in science and engineering. Reacting nanodiamond with cBN at moderate pressures and high temperatures provides a pathway to such materials. Here we report the fabrication of C x-BN nanocomposites, measuring up to 10 mm in longest dimension, by reacting nanodiamond with pre-synthesized cBN in a large-volume press. The nanocomposites consist of randomly-oriented diamond and cBN domains stitched together by sp 3-hybridized C-B and C-N bonds, leading to p-type semiconductivity. Dislocations near the sutures accommodate lattice mismatch between diamondmore » and cBN. Nanotwinning within both diamond and cBN domains further contributes to a bulk hardness ~50% higher than sintered cBN. We find the nanocomposite of C 2-BN exhibits p-type semiconductivity with low activation energy and high thermal stability, making it a functional,ultrahard substance.« less

Phonovoltaic. III. Electron-phonon coupling and figure of merit of graphene:BN

NASA Astrophysics Data System (ADS)

Melnick, Corey; Kaviany, Massoud

2016-12-01

The phonovoltaic cell harvests optical phonons like a photovoltaic harvests photons, that is, a nonequilibrium (hot) population of optical phonons (at temperature Tp ,O) more energetic than the band gap produces electron-hole pairs in a p -n junction, which separates these pairs to produce power. A phonovoltaic material requires an optical phonon mode more energetic than its band gap and much more energetic than the thermal energy (Ep ,O>Δ Ee ,g≫kBT ), which relaxes by generating electrons and power (at rate γ˙e -p) rather than acoustic phonons and heat (at rate γ˙p -p). Graphene (h-C) is the most promising material candidate: when its band gap is tuned to its optical phonon energy without greatly reducing the electron-phonon (e -p ) coupling, it reaches a substantial figure of merit [ZpV=Δ Ee ,gγ˙e -p/Ep ,O(γ˙e -p+γ˙p -p) ≈0.8 ] . A simple tight-binding (TB) model presented here predicts that lifting the sublattice symmetry of graphene in order to open a band gap proscribes the e -p interaction at the band edge, such that γ˙e -p→0 as Δ Ee ,g→Ep ,O . However, ab initio (DFT-LDA) simulations of layered h-C/BN and substitutional h-C:BN show that the e -p coupling remains substantial in these asymmetric crystals. Indeed, h-C:BN achieves a high figure of merit (ZpV≈0.6 ). At 300 K and for a Carnot limit of 0.5 (Tp ,O=600 K) , a h-C:BN phonovoltaic can reach an efficiency of ηpV≈0.2 , double the thermoelectric efficiency (Z T ≈1 ) under similar conditions.

Interplay between intercalated oxygen superstructures and monolayer h -BN on Cu(100)

DOE PAGES

Ma, Chuanxu; Park, Jewook; Liu, Lei; ...

2016-08-18

The confinement effect of intercalated atoms in van der Waals heterostructures can lead to interesting interactions between the confined atoms or molecules and the overlaying two-dimensional (2D) materials. In this paper, we report the formation of ordered Cu(100) p(2×2) oxygen superstructures by oxygen intercalation under the monolayer hexagonal boron nitride (h-BN) on Cu after annealing. By using scanning tunneling microscopy and x-ray photoelectron spectroscopy, we identify the superstructure and reveal its roles in passivating the exposed Cu surfaces, decoupling h-BN and Cu, and disintegrating h-BN monolayers. The oxygen superstructure appears as a 2D pattern on the exposed Cu surface ormore » quasi-1D stripes of paired oxygen intercalated in the interface of h-BN and Cu predominantly oriented along the moiré modulations. The oxygen superstructure is shown to etch the overlaying h-BN monolayer in a thermal annealing process. After extended annealing, the h-BN monolayer disintegrates into nanoislands with zigzag edges. Finally, we discuss the implications of these findings on the stability and oxidation resistance of h-BN and relate them to challenges in process integration and 2D heterostructures.« less

BnNHL18A shows a localization change by stress-inducing chemical treatments

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

Lee, Suk-Bae; Ham, Byung-Kook; Park, Jeong Mee

2006-01-06

The two genes, named BnNHL18A and BnNHL18B, showing sequence homology with Arabidopsis NDR1/HIN1-like (NHL) genes, were isolated from cDNA library prepared with oilseed rape (Brassica napus) seedlings treated with NaCl. The transcript level of BnNHL18A was increased by sodium chloride, ethephon, hydrogen peroxide, methyl jasmonate, or salicylic acid treatment. The coding regions of BnNHL18A and BnNHL18B contain a sarcolipin (SLN)-like sequence. Analysis of the localization of smGFP fusion proteins showed that BnNHL18A is mainly localized to endoplasmic reticulum (ER). This result suggests that the SLN-like sequence plays a role in retaining proteins in ER membrane in plants. In response tomore » NaCl, hydrogen peroxide, ethephon, and salicylic acid treatments, the protein localization of BnNHL18A was changed. Our findings suggest a common function of BnNHL18A in biotic and abiotic stresses, and demonstrate the presence of the shared mechanism of protein translocalization between the responses to plant pathogen and to osmotic stress.« less

Sensitivity of BN nano-cages to caffeine and nicotine molecules

NASA Astrophysics Data System (ADS)

Soltani, Alireza; Baei, Mohammad T.; Tazikeh Lemeski, E.; Shahini, Malihe

2014-12-01

Adsorption of caffeine and nicotine molecules over B12N12 and B16N16 nano-cages were investigated by using first-principles calculations to define whether BN nano-cages are applicable for filtering or sensing caffeine and nicotine molecules. The chemisorption energy of nicotine molecule on BN nano-cages is very stronger than caffeine molecule. Upon the adsorption of caffeine and nicotine molecules, the electronic properties of the BN nano-cages can be significantly changed, being too much sensitized on the caffeine and nicotine adsorptions.

19 CFR 141.66 - Bond for missing documents.

Code of Federal Regulations, 2011 CFR

2011-04-01

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2013-04-01

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2010-04-01

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Code of Federal Regulations, 2014 CFR

2014-04-01

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Code of Federal Regulations, 2012 CFR

2012-04-01

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Phase stability limit of c-BN under hydrostatic and non-hydrostatic pressure conditions

NASA Astrophysics Data System (ADS)

Xiao, Jianwei; Du, Jinglian; Wen, Bin; Melnik, Roderick; Kawazoe, Yoshiyuki; Zhang, Xiangyi

2014-04-01

Phase stability limit of cubic boron nitride (c-BN) has been investigated by the crystal structure search technique. It indicated that this limit is ˜1000 GPa at hydrostatic pressure condition. Above this pressure, c-BN turns into a metastable phase with respect to rocksalt type boron nitride (rs-BN). However, rs-BN cannot be retained at 0 GPa owing to its instability at pressure below 250 GPa. For non-hydrostatic pressure conditions, the phase stability limit of c-BN is substantially lower than that under hydrostatic pressure conditions and it is also dramatically different for other pressure mode.

Phase stability limit of c-BN under hydrostatic and non-hydrostatic pressure conditions

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

Xiao, Jianwei; Du, Jinglian; Wen, Bin, E-mail: wenbin@ysu.edu.cn

2014-04-28

Phase stability limit of cubic boron nitride (c-BN) has been investigated by the crystal structure search technique. It indicated that this limit is ∼1000 GPa at hydrostatic pressure condition. Above this pressure, c-BN turns into a metastable phase with respect to rocksalt type boron nitride (rs-BN). However, rs-BN cannot be retained at 0 GPa owing to its instability at pressure below 250 GPa. For non-hydrostatic pressure conditions, the phase stability limit of c-BN is substantially lower than that under hydrostatic pressure conditions and it is also dramatically different for other pressure mode.

Electrical and Thermal Transport in Coplanar Polycrystalline Graphene-hBN Heterostructures.

PubMed

Barrios-Vargas, José Eduardo; Mortazavi, Bohayra; Cummings, Aron W; Martinez-Gordillo, Rafael; Pruneda, Miguel; Colombo, Luciano; Rabczuk, Timon; Roche, Stephan

2017-03-08

We present a theoretical study of electronic and thermal transport in polycrystalline heterostructures combining graphene (G) and hexagonal boron nitride (hBN) grains of varying size and distribution. By increasing the hBN grain density from a few percent to 100%, the system evolves from a good conductor to an insulator, with the mobility dropping by orders of magnitude and the sheet resistance reaching the MΩ regime. The Seebeck coefficient is suppressed above 40% mixing, while the thermal conductivity of polycrystalline hBN is found to be on the order of 30-120 Wm -1 K -1 . These results, agreeing with available experimental data, provide guidelines for tuning G-hBN properties in the context of two-dimensional materials engineering. In particular, while we proved that both electrical and thermal properties are largely affected by morphological features (e.g., by the grain size and composition), we find in all cases that nanometer-sized polycrystalline G-hBN heterostructures are not good thermoelectric materials.

Rapid Changes in the Structure of the BN Object

NASA Technical Reports Server (NTRS)

Danchi, William C.; Gezari, D. Y.; Greenhill, L. J.; Najita, J.; Monnier, J. D.; Tuthill, P. G.; Wishnow, E. H.; Townes, C. H.; Fisher, Richard R. (Technical Monitor)

2001-01-01

The BN/KL region in Orion is the archetypal region of high-mass star formation, radiating approx. 10(sup)5 Lsun and displaying promininent bulk outflows. In particular, there is no certain identification of the sources responsible for the high luminosity and outflows, and is the origin of a major explosive event (Shultz et al. 1999, ApJ, 511, 282). Using 18.7 and 12.5 micron data from observations in December 1999 and October 2000 made at the Keck I telescope, we discovered that the BN Object has a companion previously seen only at radio wavelengths (Menten & Reid 1995, ApJ, 445, L157). We call this companion B2 and it is about 1.5 arcsec West of the bright component. We also see changes in the shape of BN and the emission of "blobs" or "bullets" of material. While B2 remains unchanged and in the same place between the two epochs, there is an additional structure in BN to the South-South-East and the North-East, as well as a finger of material pointing North from B2 itself. Such a change has not been seen before in the infrared. We have looked very carefully at these images, calibrator images taken within a few minutes of the source images, as well as our previous images and cannot find any technical faults with the data. We explore the implications of these results, in particular, can these features be connected with previously observed "bullets" or "fingers" (see Allen & Burton 1993, for example), making BN a source for the bullets, implying they are not from IRc2 as previously thought? Or could they be produced by an interaction between material from BN and other sources such as IRc2?

Electronic structure properties of deep defects in hBN

NASA Astrophysics Data System (ADS)

Dev, Pratibha; Prdm Collaboration

In recent years, the search for room-temperature solid-state qubit (quantum bit) candidates has revived interest in the study of deep-defect centers in semiconductors. The charged NV-center in diamond is the best known amongst these defects. However, as a host material, diamond poses several challenges and so, increasingly, there is an interest in exploring deep defects in alternative semiconductors such as hBN. The layered structure of hBN makes it a scalable platform for quantum applications, as there is a greater potential for controlling the location of the deep defect in the 2D-matrix through careful experiments. Using density functional theory-based methods, we have studied the electronic and structural properties of several deep defects in hBN. Native defects within hBN layers are shown to have high spin ground states that should survive even at room temperature, making them interesting solid-state qubit candidates in a 2D matrix. Partnership for Reduced Dimensional Material (PRDM) is part of the NSF sponsored Partnerships for Research and Education in Materials (PREM).

Comparison of trapped charges and hysteresis behavior in hBN encapsulated single MoS2 flake based field effect transistors on SiO2 and hBN substrates.

PubMed

Lee, Changhee; Rathi, Servin; Khan, Muhammad Atif; Lim, Dongsuk; Kim, Yunseob; Yun, Sun Jin; Youn, Doo-Hyeb; Watanabe, Kenji; Taniguchi, Takashi; Kim, Gil-Ho

2018-08-17

Molybdenum disulfide (MoS 2 ) based field effect transistors (FETs) are of considerable interest in electronic and opto-electronic applications but often have large hysteresis and threshold voltage instabilities. In this study, by using advanced transfer techniques, hexagonal boron nitride (hBN) encapsulated FETs based on a single, homogeneous and atomic-thin MoS 2 flake are fabricated on hBN and SiO 2 substrates. This allows for a better and a precise comparison between the charge traps at the semiconductor-dielectric interfaces at MoS 2 -SiO 2 and hBN interfaces. The impact of ambient environment and entities on hysteresis is minimized by encapsulating the active MoS 2 layer with a single hBN on both the devices. The device to device variations induced by different MoS 2 layer is also eliminated by employing a single MoS 2 layer for fabricating both devices. After eliminating these additional factors which induce variation in the device characteristics, it is found from the measurements that the trapped charge density is reduced to 1.9 × 10 11 cm -2 on hBN substrate as compared to 1.1 × 10 12 cm -2 on SiO 2 substrate. Further, reduced hysteresis and stable threshold voltage are observed on hBN substrate and their dependence on gate sweep rate, sweep range, and gate stress is also studied. This precise comparison between encapsulated devices on SiO 2 and hBN substrates further demonstrate the requirement of hBN substrate and encapsulation for improved and stable performance of MoS 2 FETs.

Effect of substrate temperature in the synthesis of BN nanostructures

NASA Astrophysics Data System (ADS)

Sajjad, M.; Zhang, H. X.; Peng, X. Y.; Feng, P. X.

2011-06-01

Boron nitride (BN) nanostructures were grown on molybdenum discs at different substrate temperatures using the short-pulse laser plasma deposition technique. Large numbers of randomly oriented nanorods of fiber-like structures were obtained. The variation in the length and diameter of the nanorods as a function of the substrate temperature was systematically studied. The surface morphologies of the samples were studied using scanning electron microscopy. Energy dispersive x-ray spectroscopy confirmed that both the elements boron and nitrogen are dominant in the nanostructure. The x-ray diffraction (XRD) technique was used to analyse BN phases. The XRD peak that appeared at 26° showed the presence of hexagonal BN phase, whereas the peak at 44° was related to cubic BN content in the samples. Raman spectroscopic analysis showed vibrational modes of sp2- and sp3-type bonding in the sample. The Raman spectra agreed well with XRD results.

Structural analysis of graphene and h-BN: A molecular dynamics approach

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

Thomas, Siby; Ajith, K. M., E-mail: ajith@nitk.ac.in; Valsakumar, M. C.

2016-05-06

Classical molecular dynamics simulation is employed to analyze pair correlations in graphene and h-BN at various temperatures to explore the integrity of their respective structures. As the temperature increases, the height fluctuations in the out-of-plane direction of both graphene and h-BN are found to increase. The positional spread of atoms also increases with temperature. Thus the amplitude of the peak positions in the radial distribution function (RDF) decreases with temperature. It is found that FWHM of peaks in the RDF of h-BN is smaller as compared to those of graphene which implies that the structure of h-BN is more robustmore » as compared to that of graphene with respect to their respective empirical potential.« less

High Temperature Si-doped BN Interphases for Woven SiC/SiC Composites

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.; Hurwitz, Frances; Yun, Hee Mann; Gray, Hugh R. (Technical Monitor)

2002-01-01

The hydrolytic stability of high-temperature deposited Si-doped BN has been shown in the past to be superior in comparison to "pure" BN processed at similar or even higher temperatures. This type of material would be very desirable as a SiC/SiC composite interphase that is formed by chemical infiltration into multi-ply woven preform. However, due to rapid deposition on the preform outer surface at the high processing temperature, this has proven very difficult. To overcome this issue, single plies of woven fabric were infiltrated with Si-doped BN. Three composite panels of different SiC fiber types were fabricated with Si-doped BN interphases including Sylramic, Hi-Nicalon Type S and Sylramic-iBN fiber-types. The latter fiber-type possesses a thin in-situ grown BN layer on the fiber surface. High Si contents (approx. 7 to 10 a/o) and low oxygen contents (less than 1 a/o) were achieved. All three composite systems demonstrated reasonable debonding and sliding properties. The coated Sylramic fabric and composites were weak due to fiber degradation apparently caused during interphase processing by the formation of TiN crystals on the fiber surface. The Hi-Nicalon Type S composites with Si-doped BN interphase were only slightly weaker than Hi-Nicalon Type S composites with conventional BN when the strength on the load-bearing fibers at failure was compared. On the other hand, the Sylramic-iBN fabric and composites with Si-doped BN showed excellent composite and intermediate temperature stress-rupture properties. Most impressive was the lack of any significant interphase oxidation on the fracture surface of stress-ruptured specimens tested well above matrix cracking at 815C.

Theranostic pretargeted radioimmunotherapy of colorectal cancer xenografts in mice using picomolar affinity Y-86- or Lu-177-DOTA-Bn binding scFv C825/GPA33 IgG bispecific immunoconjugates

PubMed Central

Cheal, Sarah M.; Xu, Hong; Guo, Hong-fen; Lee, Sang-gyu; Punzalan, Blesida; Chalasani, Sandhya; Fung, Edward K.; Jungbluth, Achim; Zanzonico, Pat B.; Carrasquillo, Jorge A.; O’Donoghue, Joseph; Smith-Jones, Peter M.; Wittrup, K. Dane; Cheung, Nai-Kong V.; Larson, Steven M.

2015-01-01

Purpose GPA33 is a colorectal cancer (CRC) antigen with unique retention properties after huA33-mediated tumor targeting. We tested a pre-targeted radioimmunotherapy (PRIT) approach for CRC using a tetravalent bispecific antibody with dual specificity for GPA33 tumor antigen and DOTA-Bn (radiolanthanide metal) complex. Methods PRIT was optimized in vivo by titrating sequential intravenous doses of huA33-C825, the dextran-based clearing agent (CA), and the C825-haptens 177Lu-or 86Y-DOTA-Bn in mice bearing the SW1222 subcutaneous (s.c.) CRC xenograft model. Results Using optimized PRIT, therapeutic indices (TIs) for tumor radiation absorbed dose of 73 (tumor/blood) and 12 (tumor/kidney) were achieved. Estimated absorbed doses (cGy/MBq) to tumor, blood, liver, spleen, and kidney for single-cycle PRIT were 65.8, 0.9 (TI: 73), 6.3 (TI: 10), 6.6 (TI: 10), and 5.3 (TI: 12), respectively. Two cycles of PRIT treatment (66.6 or 111 MBq 177Lu-DOTA-Bn) were safe and effective, with 9/9 complete responses of established s.c. tumors (100–700 mm3) and 2/9 alive without recurrence >140 d. Tumor log kill in this model was estimated to be 2.1–3.0 based time to 500-mm3 tumor recurrence. In addition, PRIT dosimetry/diagnosis was performed by PET imaging of the positron-emitting DOTA-hapten 86Y-DOTA-Bn. Conclusions We have developed anti-GPA33 PRIT, as a triple-step theranostic strategy for pre-clinical detection, dosimetry and safe targeted radiotherapy of established human colorectal mouse xenografts. PMID:26596724

Dielectric Properties of Boron Nitride-Ethylene Glycol (BN-EG) Nanofluids

NASA Astrophysics Data System (ADS)

Fal, Jacek; Cholewa, Marian; Gizowska, Magdalena; Witek, Adam; ŻyŁa, GaweŁ

2017-02-01

This paper presents the results of experimental investigation of the dielectric properties of ethylene glycol (EG) with various load of boron nitride (BN) nanoparticles. The nanofuids were prepared by using a two-step method on the basis of commercially available BN nanoparticles. The measurements were carried out using the Concept 80 System (NOVOCONTROL Technologies GmbH & Co. KG, Montabaur, Germany) in a frequency range from 10 Hz to 10 MHz and temperatures from 278.15 K to 328.15 K. The frequency-dependent real (ɛ ^' }) and imaginary (ɛ ^' ' }) parts of the complex permittivity (ɛ ^*) and the alternating current (AC) conductivity are presented. Also, the effect of temperature and mass concentrations on the dielectric properties of BN-EG nanofluids are demonstrated. The results show that the most significant increase can be achieved for 20 wt.% of BN nanoparticles at 283.15 K and 288.15 K, that is eleven times larger than in the case of pure EG.

Thermally activated hysteresis in high quality graphene/h-BN devices

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

Cadore, A. R., E-mail: alissoncadore@gmail.com, E-mail: lccampos@fisica.ufmg.br; Mania, E.; Lacerda, R. G.

2016-06-06

We report on gate hysteresis of resistance in high quality graphene/hexagonal boron nitride (h-BN) devices. We observe a thermally activated hysteretic behavior in resistance as a function of the applied gate voltage at temperatures above 375 K. In order to investigate the origin of the hysteretic phenomenon, we compare graphene/h-BN heterostructure devices with SiO{sub 2}/Si back gate electrodes to devices with graphite back gate electrodes. The gate hysteretic behavior of the resistance is present only in devices with an h-BN/SiO{sub 2} interface and is dependent on the orientation of the applied gate electric field and sweep rate. We describe a phenomenologicalmore » model which captures all of our findings based on charges trapped at the h-BN/SiO{sub 2} interface. Such hysteretic behavior in graphene resistance must be considered in high temperature applications for graphene devices and may open new routes for applications in digital electronics and memory devices.« less

Additive Interaction of MTHFR C677T and MTRR A66G Polymorphisms with Being Overweight/Obesity on the Risk of Type 2 Diabetes.

PubMed

Zhi, Xueyuan; Yang, Boyi; Fan, Shujun; Li, Yongfang; He, Miao; Wang, Da; Wang, Yanxun; Wei, Jian; Zheng, Quanmei; Sun, Guifan

2016-12-15

Although both methylenetetrahydrofolate reductase ( MTHFR ) C677T and methionine synthase reductase ( MTRR ) A66G polymorphisms have been associated with type 2 diabetes (T2D), their interactions with being overweight/obesity on T2D risk remain unclear. To evaluate the associations of the two polymorphisms with T2D and their interactions with being overweight/obesity on T2D risk, a case-control study of 180 T2D patients and 350 healthy controls was conducted in northern China. Additive interaction was estimated using relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP) and synergy index (S). After adjustments for age and gender, borderline significant associations of the MTHFR C677T and MTRR A66G polymorphisms with T2D were observed under recessive (OR = 1.43, 95% CI: 0.98-2.10) and dominant (OR = 1.43, 95% CI: 1.00-2.06) models, respectively. There was a significant interaction between the MTHFR 677TT genotype and being overweight/obesity on T2D risk (AP = 0.404, 95% CI: 0.047-0.761), in addition to the MTRR 66AG/GG genotypes (RERI = 1.703, 95% CI: 0.401-3.004; AP = 0.528, 95% CI: 0.223-0.834). Our findings suggest that individuals with the MTHFR 677TT or MTRR 66AG/GG genotypes are more susceptible to the detrimental effect of being overweight/obesity on T2D. Further large-scale studies are still needed to confirm our findings.

Vibration responses of h-BN sheet to charge doping and external strain

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

Yang, Wei; Yang, Yu; Zheng, Fawei

2013-12-07

Based on density functional theory and density functional perturbation theory calculations, we systematically investigate the vibration responses of h-BN sheet to charge doping and external strains. It is found that under hole doping, the phonon frequencies of the ZO and TO branches at different wave vector q shift linearly with different slopes. Under electron doping, although the phonon frequencies shift irregularly, the shifting values are different at different phonon wave vectors. Interestingly, we find that external strain can restrain the irregular vibration responses of h-BN sheet to electron doping. The critical factor is revealed to be the relative position ofmore » the nearly free electron and boron p{sub z} states of h-BN sheet. Under external strains, the vibration responses of h-BN sheet are also found to be highly dependent on the phonon branches. Different vibration modes at different q points are revealed to be responsible for the vibration responses of h-BN sheet to charge doping and external strain. Our results point out a new way to detect the doping or strain status of h-BN sheet by measuring the vibration frequencies at different wave vector.« less

One-Shot Multiple Borylation toward BN-Doped Nanographenes.

PubMed

Matsui, Kohei; Oda, Susumu; Yoshiura, Kazuki; Nakajima, Kiichi; Yasuda, Nobuhiro; Hatakeyama, Takuji

2018-01-31

One-shot double, triple, and quadruple borylation reactions of triarylamines were developed through a judicious choice of boron source and Brønsted base. With the aid of borylation reactions, a variety of BN-doped nanographenes were synthesized in two steps from commercially available starting materials. An organic light-emitting diode device employing BN-doped nanographene as an emitter exhibited deep pure-blue emission at 460 nm, with CIE coordinates of (0.13, 0.11), and an external quantum efficiency of 18.3%.

Extended Tersoff potential for boron nitride: Energetics and elastic properties of pristine and defective h -BN

NASA Astrophysics Data System (ADS)

Los, J. H.; Kroes, J. M. H.; Albe, K.; Gordillo, R. M.; Katsnelson, M. I.; Fasolino, A.

2017-11-01

We present an extended Tersoff potential for boron nitride (BN-ExTeP) for application in large scale atomistic simulations. BN-ExTeP accurately describes the main low energy B, N, and BN structures and yields quantitatively correct trends in the bonding as a function of coordination. The proposed extension of the bond order, added to improve the dependence of bonding on the chemical environment, leads to an accurate description of point defects in hexagonal BN (h -BN) and cubic BN (c -BN). We have implemented this potential in the molecular dynamics LAMMPS code and used it to determine some basic properties of pristine 2D h -BN and the elastic properties of defective h -BN as a function of defect density at zero temperature. Our results show that there is a strong correlation between the size of the static corrugation induced by the defects and the weakening of the in-plane elastic moduli.

Graphene/h-BN/GaAs sandwich diode as solar cell and photodetector.

PubMed

Li, Xiaoqiang; Lin, Shisheng; Lin, Xing; Xu, Zhijuan; Wang, Peng; Zhang, Shengjiao; Zhong, Huikai; Xu, Wenli; Wu, Zhiqian; Fang, Wei

2016-01-11

In graphene/semiconductor heterojunction, the statistic charge transfer between graphene and semiconductor leads to decreased junction barrier height and limits the Fermi level tuning effect in graphene, which greatly affects the final performance of the device. In this work, we have designed a sandwich diode for solar cells and photodetectors through inserting 2D hexagonal boron nitride (h-BN) into graphene/GaAs heterostructure to suppress the static charge transfer. The barrier height of graphene/GaAs heterojunction can be increased from 0.88 eV to 1.02 eV by inserting h-BN. Based on the enhanced Fermi level tuning effect with interface h-BN, through adopting photo-induced doping into the device, power conversion efficiency (PCE) of 10.18% has been achieved for graphene/h-BN/GaAs compared with 8.63% of graphene/GaAs structure. The performance of graphene/h-BN/GaAs based photodetector is also improved with on/off ratio increased by one magnitude compared with graphene/GaAs structure.

Catalytic activity of Cu4-cluster to adsorb H2S gas: h-BN nanosheet

NASA Astrophysics Data System (ADS)

Kansara, Shivam; Gupta, Sanjeev K.; Sonvane, Yogesh

2018-05-01

We have investigated the electronic properties, adsorptions strength and charge transfer using first principles calculations using density functional theory (DFT). The hexagonal boron nitride (h-BN) substrate shows metallic behavior, which helps to enhance the absorption process. The adsorption of three different orientations (S, D and T) of the H2S gas molecules to analyze the maximum adsorption strength from them onto a copper cluster (Cu4) based on h-BN nanosheet. The maximum adsorption energy of the H2S gas molecule is -1.50 eV for the S orientation and for D and U, it is -0.71 eV and -0.78 eV, respectively. The results show that Cu4 cluster helps to capture H2S gas from the environment and results are useful for the cleaning environment from the toxic gases.

Interlayer electron-phonon coupling in WSe2/hBN heterostructures

NASA Astrophysics Data System (ADS)

Jin, Chenhao; Kim, Jonghwan; Suh, Joonki; Shi, Zhiwen; Chen, Bin; Fan, Xi; Kam, Matthew; Watanabe, Kenji; Taniguchi, Takashi; Tongay, Sefaattin; Zettl, Alex; Wu, Junqiao; Wang, Feng

2017-02-01

Engineering layer-layer interactions provides a powerful way to realize novel and designable quantum phenomena in van der Waals heterostructures. Interlayer electron-electron interactions, for example, have enabled fascinating physics that is difficult to achieve in a single material, such as the Hofstadter's butterfly in graphene/boron nitride (hBN) heterostructures. In addition to electron-electron interactions, interlayer electron-phonon interactions allow for further control of the physical properties of van der Waals heterostructures. Here we report an interlayer electron-phonon interaction in WSe2/hBN heterostructures, where optically silent hBN phonons emerge in Raman spectra with strong intensities through resonant coupling to WSe2 electronic transitions. Excitation spectroscopy reveals the double-resonance nature of such enhancement, and identifies the two resonant states to be the A exciton transition of monolayer WSe2 and a new hybrid state present only in WSe2/hBN heterostructures. The observation of an interlayer electron-phonon interaction could open up new ways to engineer electrons and phonons for device applications.

Draft genome sequence of the docosahexaenoic acid producing thraustochytrid Aurantiochytrium sp. T66.

PubMed

Liu, Bin; Ertesvåg, Helga; Aasen, Inga Marie; Vadstein, Olav; Brautaset, Trygve; Heggeset, Tonje Marita Bjerkan

2016-06-01

Thraustochytrids are unicellular, marine protists, and there is a growing industrial interest in these organisms, particularly because some species, including strains belonging to the genus Aurantiochytrium, accumulate high levels of docosahexaenoic acid (DHA). Here, we report the draft genome sequence of Aurantiochytrium sp. T66 (ATCC PRA-276), with a size of 43 Mbp, and 11,683 predicted protein-coding sequences. The data has been deposited at DDBJ/EMBL/Genbank under the accession LNGJ00000000. The genome sequence will contribute new insight into DHA biosynthesis and regulation, providing a basis for metabolic engineering of thraustochytrids.

Flattening and manipulation of the electronic structure of h-BN/Rh(111) nanomesh upon Sn intercalation

NASA Astrophysics Data System (ADS)

Sugiyama, Yuya; Bernard, Carlo; Okuyama, Yuma; Ideta, Shin-ichiro; Tanaka, Kiyohisa; Greber, Thomas; Hirahara, Toru

2018-06-01

We have deposited Sn on corrugated hexagonal boron nitride (h-BN) nanomeshs formed on Rh(111) and found that Sn atoms are intercalated between h-BN and Rh, flattening the h-BN. Our reflection high-energy electron diffraction (RHEED) analysis showed that the average in-plane lattice constant of h-BN increases due to the loss of the corrugation. Furthermore, electronic structure measurements based on angle-resolved photoemission spectroscopy (ARPES) showed that the h-BN π band width increases significantly while the σ band width does not change as much. These behaviors were partly different from previous reports on the intercalation of h-BN/Rh system. Our results offer a novel, simple method to control the electronic structure of h-BN.

Hybrid surface-phonon-plasmon polariton modes in graphene/monolayer h-BN heterostructures.

PubMed

Brar, Victor W; Jang, Min Seok; Sherrott, Michelle; Kim, Seyoon; Lopez, Josue J; Kim, Laura B; Choi, Mansoo; Atwater, Harry

2014-07-09

Infrared transmission measurements reveal the hybridization of graphene plasmons and the phonons in a monolayer hexagonal boron nitride (h-BN) sheet. Frequency-wavevector dispersion relations of the electromagnetically coupled graphene plasmon/h-BN phonon modes are derived from measurement of nanoresonators with widths varying from 30 to 300 nm. It is shown that the graphene plasmon mode is split into two distinct optical modes that display an anticrossing behavior near the energy of the h-BN optical phonon at 1370 cm(-1). We explain this behavior as a classical electromagnetic strong-coupling with the highly confined near fields of the graphene plasmons allowing for hybridization with the phonons of the atomically thin h-BN layer to create two clearly separated new surface-phonon-plasmon-polariton (SPPP) modes.

An antagonistic monoclonal antibody (B-N6) specific for the human neurotensin receptor-1.

PubMed

Ovigne, J M; Vermot-Desroches, C; Lecron, J C; Portier, M; Lupker, J; Pecceu, F; Wijdenes, J

1998-06-01

The neuropeptide neurotensin (NT) interacts with two types of human receptors (hNTR) termed hNTR-1 and hNTR-2. This study describes a monoclonal antibody (MAb) specific for hNTR-1, B-N6. This MAb binds specifically to hNTR-1, but not to hNTR-2 transfected CHO cells. B-N6 and NT display a reciprocal competition and react in a similar way to trypsin, suggesting that the B-N6 epitope is at or close to the NT binding site on the third extracellular loop. Unlike B-N6, NT induces hNTR-1 internalization. Although neither NT-FITC nor B-N6 binding was detected by flow cytometry on different human cells, specific mRNA expression for hNTR-1 was detected in these cells. In CHO cells expressing hNTR-1 and a luciferase gene coupled to the krox24 reporter, B-N6 and the antagonist SR 48692 inhibited NT-induced intracellular activation of krox24 in a dose-dependent manner. From these results it is concluded that B-N6 is an antagonistic anti-hNTR-1 MAb.

44Sc-DOTA-BN[2-14]NH2 in comparison to 68Ga-DOTA-BN[2-14]NH2 in pre-clinical investigation. Is 44Sc a potential radionuclide for PET?

PubMed

Koumarianou, E; Loktionova, N S; Fellner, M; Roesch, F; Thews, O; Pawlak, D; Archimandritis, S C; Mikolajczak, R

2012-12-01

In the present study we demonstrate the in vitro and in vivo comparison of the (44)Sc and (68)Ga labeled DOTA-BN[2-14]NH(2). (44)Sc is a positron emitter with a half life of 3.92 h. Hence it could be used for PET imaging with ligands requiring longer observation time than in the case of (68)Ga. The binding affinity of (nat)Sc-DOTA-BN[2-14]NH(2) and (nat)Ga-DOTA-BN[2-14]NH(2) to GRP receptors was studied in competition to [(125)I-Tyr(4)]-Bombesin in the human prostate cancer cell line PC-3. A preliminary biodistribution in normal rats was performed, while first microPET images were assessed in male Copenhagen rats bearing the androgen-independent Dunning R-3327-AT-1 prostate cancer tumor. The affinity to GRP receptors in the PC-3 cell line was higher for (nat)Ga-DOTA-BN[2-14]NH(2) (IC(50)(nM)=0.85 ± 0.06) than that of (nat)Sc-DOTA-BN[2-14]NH(2) (IC(50) (nM)=6.49 ± 0.13). The internalization rate of (68)Ga labeled DOTA-BN[2-14]NH(2) was slower than that of (44)Sc, but their final internalization percents were comparable. (68)Ga-DOTA-BN[2-14]NH(2) was externalized faster than (44)Sc-DOTA-BN[2-14]NH(2). The biodistribution of (44)Sc-DOTA-BN[2-14]NH(2) and (68)Ga-DOTA-BN[2-14]NH(2) in normal rats revealed a higher uptake in target organs and tissues of the first one while both excreted mainly through urinary tract. In microPET images both tracers were accumulated in the tumor with similar uptake patterns. Despite the differences in the receptor affinity both the (68)Ga- and the (44)Sc-labeled DOTA-BN[2-14]NH(2) tracers showed comparable distribution and similar time constants of uptake and elimination. Moreover no differences in tumor accumulation (neither in the overall uptake nor in the dynamics) were observed from the microPet imaging. From that perspective the use of either (44)Sc or (68)Ga for detecting tumors with GRP receptors is equivalent. Copyright © 2012 Elsevier Ltd. All rights reserved.

Mechanical Properties and Plasma Erosion Resistance of ZrO2p(3Y)/BN-SiO2 Ceramic Composites under Different Sintering Temperature

NASA Astrophysics Data System (ADS)

Zhou, Yu; Duan1, Xiaoming; Jia, Dechang; Yang, Zhihua; Meng, Qingchang; Yu, Yang; Yu, Daren; Ding, Yongjie

2011-10-01

ZrO2p(3Y)/BN-SiO2 ceramic composites were hot pressed under different sintering temperature. The ceramic composites were composed by BN, m-ZrO2, t-ZrO2 and SiO2. The relative density, bending strength, elastic modulus and fracture toughness increase with the sintering temperature increasing, the maximum value of which at the sintering temperature of 1800°C are 97.5%, 229.9MPa, 60.8GPa and 3.55MPam1/2, respectively. The erosion resistance ability of ZrO2p(3Y)/BN-SiO2 ceramic composites rise gradually with the sintering temperature increasing, and the erosion rate of the ceramic composite sintered at 1800°C is 8.03×10-3mm/h.

Theranostic pretargeted radioimmunotherapy of colorectal cancer xenografts in mice using picomolar affinity ⁸⁶Y- or ¹⁷⁷Lu-DOTA-Bn binding scFv C825/GPA33 IgG bispecific immunoconjugates.

PubMed

Cheal, Sarah M; Xu, Hong; Guo, Hong-Fen; Lee, Sang-Gyu; Punzalan, Blesida; Chalasani, Sandhya; Fung, Edward K; Jungbluth, Achim; Zanzonico, Pat B; Carrasquillo, Jorge A; O'Donoghue, Joseph; Smith-Jones, Peter M; Wittrup, K Dane; Cheung, Nai-Kong V; Larson, Steven M

2016-05-01

GPA33 is a colorectal cancer (CRC) antigen with unique retention properties after huA33-mediated tumor targeting. We tested a pretargeted radioimmunotherapy (PRIT) approach for CRC using a tetravalent bispecific antibody with dual specificity for GPA33 tumor antigen and DOTA-Bn-(radiolanthanide metal) complex. PRIT was optimized in vivo by titrating sequential intravenous doses of huA33-C825, the dextran-based clearing agent, and the C825 haptens (177)Lu-or (86)Y-DOTA-Bn in mice bearing the SW1222 subcutaneous (s.c.) CRC xenograft model. Using optimized PRIT, therapeutic indices (TIs) for tumor radiation-absorbed dose of 73 (tumor/blood) and 12 (tumor/kidney) were achieved. Estimated absorbed doses (cGy/MBq) to tumor, blood, liver, spleen, and kidney for single-cycle PRIT were 65.8, 0.9 (TI 73), 6.3 (TI 10), 6.6 (TI 10), and 5.3 (TI 12), respectively. Two cycles of PRIT (66.6 or 111 MBq (177)Lu-DOTA-Bn) were safe and effective, with a complete response of established s.c. tumors (100 - 700 mm(3)) in nine of nine mice, with two mice alive without recurrence at >140 days. Tumor log kill in this model was estimated to be 2.1 - 3.0 based on time to 500-mm(3) tumor recurrence. In addition, PRIT dosimetry/diagnosis was performed by PET imaging of the positron-emitting DOTA hapten (86)Y-DOTA-Bn. We have developed anti-GPA33 PRIT as a triple-step theranostic strategy for preclinical detection, dosimetry, and safe targeted radiotherapy of established human colorectal mouse xenografts.

BnSGS3 Has Differential Effects on the Accumulation of CMV, ORMV and TuMV in Oilseed Rape

PubMed Central

Chen, Quan; Wang, Jie; Hou, Mingsheng; Liu, Shengyi; Huang, Junyan; Cai, Li

2015-01-01

Virus diseases greatly affect oilseed rape (Brassica napus) production. Investigating antiviral genes may lead to the development of disease-resistant varieties of oilseed rape. In this study, we examined the effects of the suppressor of gene silencing 3 in Brassica napus (BnSGS3, a putative antiviral gene) with different genus viruses by constructing BnSGS3-overexpressing (BnSGS3-Ov) and BnSGS3-silenced (BnSGS3-Si) oilseed rape (cv. Zhongshuang No. 6) plants. These three viruses are Oilseed rape mosaic virus (ORMV), Turnip mosaic virus (TuMV) and Cucumber mosaic virus (CMV). The native BnSGS3 expressed in all examined tissues with the highest expression in siliques. All three viruses induced BnSGS3 expression, but ORMV induced a dramatic increase in the BnSGS3-Ov plants, followed by TuMV and CMV. Upon inoculation with three different viruses, transcript abundance of BnSGS3 gene follows: BnSGS3-Ov > non-transgenic plants > BnSGS3-Si. The accumulation quantities of ORMV and TuMV exhibited a similar trend. However, CMV accumulation showed an opposite trend where virus accumulations were negatively correlated with BnSGS3 expression. The results suggest that BnSGS3 selectively inhibits CMV accumulation but promotes ORMV and TuMV accumulation. BnSGS3 should be used in different ways (up- and down-regulation) for breeding virus-resistant oilseed rape varieties. PMID:26225990

Facile synthesis, microstructure and photophysical properties of core-shell nanostructured (SiCN)/BN nanocomposites

PubMed Central

Zhang, Qian; Jia, Dechang; Yang, Zhihua; Cai, Delong; Laine, Richard M.; Li, Qian; Zhou, Yu

2017-01-01

Increasing structural complexity at nanoscale can permit superior control over photophysical properties in the precursor-derived semiconductors. We demonstrate here the synthesis of silicon carbonitride (SiCN)/boron nitride (BN) nanocomposites via a polymer precursor route wherein the cobalt polyamine complexes used as the catalyst, exhibiting novel composite structures and photophysical properties. High Resolution Transmission Electron Microscopy (HRTEM) analysis shows that the diameters of SiCN−BN core−shell nanocomposites and BN shells are 50‒400 nm and 5‒25 nm, respectively. BN nanosheets (BNNSs) are also observed with an average sheet size of 5‒15 nm. The photophysical properties of these nanocomposites are characterized using the UV-Vis and photoluminescence (PL) analyses. The as-produced composites have emission behavior including an emission lifetime of 2.5 ns (±20 ps) longer observed in BN doped SiCN than that seen for SiC nanoparticles. Our results suggest that the SiCN/BN nanocomposites act as semiconductor displaying superior width photoluminescence at wavelengths spanning the visible to near-infrared (NIR) spectral range (400‒700 nm), owing to the heterojunction of the interface between the SiC(N) nanowire core and the BN nanosheet shell. PMID:28084300

Enhancing the mechanical properties of BN nanosheet-polymer composites by uniaxial drawing

NASA Astrophysics Data System (ADS)

Jan, Rahim; May, Peter; Bell, Alan P.; Habib, Amir; Khan, Umar; Coleman, Jonathan N.

2014-04-01

We have used liquid exfoliation of hexagonal Boron-Nitride (BN) to prepare composites of BN nanosheets of three different sizes in polyvinylchloride matrices. These composites show low levels of reinforcement, consistent with poor alignment of the nanosheets as-described by a modified version of Halpin-Tsai theory. However, drawing of the composites to 300% strain results in a considerable increase in mechanical properties with the maximum composite modulus and strength both ~×3 higher than that of the pristine polymer. In addition, the rate of increase of modulus with BN volume fraction was up to 3-fold larger than for the unstrained composites. This is higher than can be explained by drawing-induced alignment using Halpin-Tsai theory. However, the data was consistent with a combination of alignment and strain-induced de-aggregation of BN multilayers.

Enhancing the mechanical properties of BN nanosheet-polymer composites by uniaxial drawing.

PubMed

Jan, Rahim; May, Peter; Bell, Alan P; Habib, Amir; Khan, Umar; Coleman, Jonathan N

2014-05-07

We have used liquid exfoliation of hexagonal Boron-Nitride (BN) to prepare composites of BN nanosheets of three different sizes in polyvinylchloride matrices. These composites show low levels of reinforcement, consistent with poor alignment of the nanosheets as-described by a modified version of Halpin-Tsai theory. However, drawing of the composites to 300% strain results in a considerable increase in mechanical properties with the maximum composite modulus and strength both ∼×3 higher than that of the pristine polymer. In addition, the rate of increase of modulus with BN volume fraction was up to 3-fold larger than for the unstrained composites. This is higher than can be explained by drawing-induced alignment using Halpin-Tsai theory. However, the data was consistent with a combination of alignment and strain-induced de-aggregation of BN multilayers.

Protective effect of high concentration of BN52021 on retinal contusion in cat eyes.

PubMed

Huang, Jin-Feng; Zhao, Hai-Peng; Yang, Yan-Feng; Huang, Hui-Min; Yao, Yi; Wang, Zhi-Jun

2015-05-09

Blunt injuries/contusion on eyes might cause retina blunt trauma. This study is to evaluate the protective function of BN52021 against retinal trauma. A total of 70 cats, 6 months old, were divided into six groups: Group A to E (n = 12) and normal control (N) group (n = 10). The right eyes in Group A to E were contused. All experiments were performed under general anesthetization. Retrobulbar injections of medication in right eyes were performed. Cats were administrated with 0.5 mL of normal saline (NS), dimethyl sulphoxide, 0.2 g/L BN52021, 1 g/L BN52021 and 5 g/L BN52021, respectively. Cats in Group N were administrated with 0.5 mL of NS. Intraocular pressure (IOP), flash electroretinogram (ERG), and retinal nerve fiber layer (RNFL) thickness were measured. Hematoxylin and eosin (HE) staining and transmission electron microscope (TEM) were detected. No significant difference was observed in IOP levels among groups. Comparing with cats in Group N, those in Group A to E showed significant lower amplitudes of rod a- and b-waves (P < 0.05). Amplitudes of rod a- and b-waves were increased by administration of high concentration of BN52021 (≥ 1 g/L). Moreover, high concentration of BN52021 decreased the RNFL thickness increased by contusion. Axons in RNFL in Group E arranged neatly at 7 days after modeling. The degenerated axons caused by contusion were repaired by BN52021. The administration of high concentration of (≥ 1 g/L) BN52021 could partially repair retinal function in contused cat eyes.

Quantum size and electric field modulations on electronic structures of SnS2/BN hetero-multilayers

NASA Astrophysics Data System (ADS)

Xia, Congxin; Zhang, Qian; Xiao, Wenbo; Du, Juan; Li, Xueping; Li, Jingbo

2018-05-01

Through first-principles calculations, we study the stability, band structures, band alignment, and interlayer charge transfer of SnS2/BN hetero-multilayers, considering quantum size and electric field effects. We find that SnS2/BN hetero-multilayers possess the characteristics of direct band structures and type-II band alignment. Moreover, increasing the BN layer number can decrease the band gap value and work function. Additionally, type-II can be tuned to type-I band alignment in the presence of an electric field. These results indicate that the SnS2/BN system is different from that of other BN-based hybrid materials, such as MoS2/BN with type-I band alignment, which is promising for optoelectronic device applications.

Anticorrosive performance of waterborne epoxy coatings containing water-dispersible hexagonal boron nitride (h-BN) nanosheets

NASA Astrophysics Data System (ADS)

Cui, Mingjun; Ren, Siming; Chen, Jia; Liu, Shuan; Zhang, Guangan; Zhao, Haichao; Wang, Liping; Xue, Qunji

2017-03-01

Homogenous dispersion of hexagonal boron nitride (h-BN) nanosheets in solvents or in the polymer matrix is crucial to initiate their many applications. Here, homogeneous dispersion of hexagonal boron nitride (h-BN) in epoxy matrix was achieved with a water-soluble carboxylated aniline trimer derivative (CAT-) as a dispersant, which was attributed to the strong π-π interaction between h-BN and CAT-, as proved by Raman and UV-vis spectra. Transmission electron microscopy (TEM) analysis confirmed a random dispersion of h-BN nanosheets in the waterborne epoxy coatings. The deterioration process of water-borne epoxy coating with and without h-BN nanosheets during the long-term immersion in 3.5 wt% NaCl solution was investigated by electrochemical measurements and water absorption test. Results implied that the introduction of well dispersed h-BN nanosheets into waterborne epoxy system remarkably improved the corrosion protection performance to substrate. Moreover, 1 wt% BN/EP composite coated substrate exhibited higher impedance modulus (1.3 × 106 Ω cm2) and lower water absorption (4%) than those of pure waterborne epoxy coating coated electrode after long-term immersion in 3.5 wt% NaCl solution, demonstrating its superior anticorrosive performance. This enhanced anticorrosive performance was mainly ascribed to the improved water barrier property of epoxy coating via incorporating homogeneously dispersed h-BN nanosheets.

Characterization of BN rich layer on ammonia treated Nextel{trademark}312 fibers

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

Khasgiwale, N.R.; Butler, E.P.; Tsakalakos, L.

A BN rich layer grown on Nextel{trademark}312 fibers by appropriate ammonia treatments was evaluated using various complimentary techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM)/Parallel Electron Energy Loss Spectroscopy (PEELS in TEM). Three different ammonia treatments were studied. Ammonia treatment resulted in crystallization of the Nextel{trademark}312 fiber. The BN rich surface layer formed due to ammonia treatment was clearly detected in XPS and PEELS both before and after oxidation. The layer thickness was estimated to be between 5--10 nm. The layer was stable after oxidation treatment at 600 C formore » 100 hours. High resolution TEM observations of the fiber surface revealed a variable BN rich layer thickness. Patches of turbostratic BN were observed under certain conditions, however mostly the layer appeared to be amorphous.« less

Graphene hot-electron light bulb: incandescence from hBN-encapsulated graphene in air

NASA Astrophysics Data System (ADS)

Son, Seok-Kyun; Šiškins, Makars; Mullan, Ciaran; Yin, Jun; Kravets, Vasyl G.; Kozikov, Aleksey; Ozdemir, Servet; Alhazmi, Manal; Holwill, Matthew; Watanabe, Kenji; Taniguchi, Takashi; Ghazaryan, Davit; Novoselov, Kostya S.; Fal'ko, Vladimir I.; Mishchenko, Artem

2018-01-01

The excellent electronic and mechanical properties of graphene allow it to sustain very large currents, enabling its incandescence through Joule heating in suspended devices. Although interesting scientifically and promising technologically, this process is unattainable in ambient environment, because graphene quickly oxidises at high temperatures. Here, we take the performance of graphene-based incandescent devices to the next level by encapsulating graphene with hexagonal boron nitride (hBN). Remarkably, we found that the hBN encapsulation provides an excellent protection for hot graphene filaments even at temperatures well above 2000 K. Unrivalled oxidation resistance of hBN combined with atomically clean graphene/hBN interface allows for a stable light emission from our devices in atmosphere for many hours of continuous operation. Furthermore, when confined in a simple photonic cavity, the thermal emission spectrum is modified by a cavity mode, shifting the emission to the visible range spectrum. We believe our results demonstrate that hBN/graphene heterostructures can be used to conveniently explore the technologically important high-temperature regime and to pave the way for future optoelectronic applications of graphene-based systems.

Modulation of band gap by an applied electric field in BN-based heterostructures

NASA Astrophysics Data System (ADS)

Luo, M.; Xu, Y. E.; Zhang, Q. X.

2018-05-01

First-principles density functional theory (DFT) calculations are performed on the structural and electronic properties of the SiC/BN van der Waals (vdW) heterostructures under an external electric field (E-field). Our results reveal that the SiC/BN vdW heterostructure has a direct band gap of 2.41 eV in the raw. The results also imply that electrons are likely to transfer from BN to SiC monolayer due to the deeper potential of BN monolayer. It is also observed that, by applying an E-field, ranging from -0.50 to +0.65 V/Å, the band gap decreases from 2.41 eV to zero, which presents a parabola-like relationship around 0.0 V/Å. Through partial density of states (PDOS) plots, it is revealed that, p orbital of Si, C, B, and N atoms are responsible for the significant variations of band gap. These obtained results predict that, the electric field tunable band gap of the SiC/BN vdW heterostructures carries potential applications for nanoelectronics and spintronic device applications.

The effect of incorporated self-lubricated BN(h) particles on the tribological properties of Ni-P/BN(h) composite coatings

NASA Astrophysics Data System (ADS)

Hsu, Chih-I.; Hou, Kung-Hsu; Ger, Ming-Der; Wang, Gao-Liang

2015-12-01

Ni-P/BN(h) composite coatings are prepared by means of the conventional electroless plating from the bath containing up to 10.0 g/l of hexagonal boron nitride particles with size 0.5 μm. The Ni-P coating is also prepared as a comparison. Cationic surfactant cetyltrimethylammonium bromide (CTAB) is used to stabilize the electrolyte, and the optimum CTAB concentration resulting in a nonagglomerated dispersion of particles is obtained using a dispersion stability analyzer. Morphology of the coatings and the effect of incorporated particles on coating structure and composition are investigated via scanning electron microscopy, field emission electron probe micro-analyzer and X-ray diffraction analysis. Hardness, roughness, friction coefficient and wear resistance of the coatings are also evaluated using Vickers microhardness tester, atomic force microscopy and ball-on disk machine. The presence of CTAB in the depositing bath has a positive effect on the surface roughness and performance of Ni-P/BN(h) composite coatings. The friction and wear tests results show that incorporation of 14.5 vol% BN(h) particles into the Ni-P coating lowers the coating friction coefficient by about 75% and the wear resistance of the Ni-P composites is approximately 10 times higher than Ni-P coating.

Spin-polarized electron transport in hybrid graphene-BN nanoribbons

NASA Astrophysics Data System (ADS)

Gao, Song; Lu, Wei; Zheng, Guo-Hui; Jia, Yalei; Ke, San-Huang

2017-05-01

The experimental realization of hybrid graphene and h-BN provides a new way to modify the electronic and transport properties of graphene-based materials. In this work, we investigate the spin-polarized electron transport in hybrid graphene-BN zigzag nanoribbons by performing first-principles nonequilibrium Green’s function method calculations. A 100% spin-polarized electron transport in a large energy window around the Fermi level is found and this behavior is independent of the ribbon width as long as there contain 3 zigzag carbon chains. This behavior may be useful in making perfect spin filters.

STM/STS study of graphene directly grown on h-BN films on Cu foils

NASA Astrophysics Data System (ADS)

Jang, Won-Jun; Wang, Min; Jang, Seong-Gyu; Kim, Minwoo; Park, Seong-Yong; Kim, Sang-Woo; Kahng, Se-Jong; Choi, Jae-Young; Song, Young; Lee, Sungjoo; Sanit Collaboration; Department Of Physics, Korea University Collaboration; Graphene Research Center, Samsung Advanced Institute Of Technology Collaboration

2013-03-01

Graphene-based devices on standard SiO2 substrate commonly exhibit inferior characteristics relative to the expected intrinsic properties of graphene, due to the disorder existing at graphene-SiO2 interface. Recently, it has been shown that exfoliated and chemical vapor deposition (CVD) graphene transferred onto hexagonal boron nitride (h-BN) possesses significantly reduced charge inhomogeneity, and yields improved device performance. Here we report the scanning tunneling microscopy (STM) and spectroscopy (STS) results obtained from a graphene layer directly grown on h-BN insulating films on Cu foils. STS measurements illustrate that graphene/h-BN film is charge neutral without electronic perturbation from h-BN/Cu substrate. Corresponding Author

Process-Induced Carbon and Sub-Layer in SiC/BN/SiC Composites: Characterization and Consequences

NASA Technical Reports Server (NTRS)

Ogbuji, L. U. J. T; Wheeler, D. R.; McCue, T. R.

2001-01-01

Following our detection of films of elemental carbon in the Hi-Nicalon TM/BN/SiC composite and its deleterious effect on oxidative durability, we have examined other SiC/BN/SiC systems. The problem is pervasive, and significant residues of free carbon are confirmed in Sylramic /BN/SiC materials. Effective techniques for routine detection and characterization of adventitious carbon in SiC/BN/SiC composites are discussed.

In situ synthesis of Fe-based alloy clad coatings containing TiB2-TiN-(h-BN)

NASA Astrophysics Data System (ADS)

Jiang, Shao-qun; Wang, Gang; Ren, Qing-wen; Yang, Chuan-duo; Wang, Ze-hua; Zhou, Ze-hua

2015-06-01

Fe-based alloy coatings containing TiB2-TiN-(h-BN) were synthesized in situ on Q235 steel substrates by a plasma cladding process using the powders of Fe901 alloy, Ti, and h-BN as raw materials. The effects of Ti/h-BN mass ratio on interfacial bonds between the coating and substrate along with the microstructures and microhardnesses of the coatings were investigated. The results show that the Ti/h-BN mass ratio is a vital factor in the formation of the coatings. Free h-BN can be introduced into the coatings by adding an excess amount of h-BN into the precursor. Decreases in the Ti/h-BN mass ratio improve the microstructural uniformity and compactness and enhance the interfacial bonds of the coatings. At a Ti/h-BN mass ratio of 10/20, the coating is free of cracks and micropores, and mainly consists of Fe-Cr, Fe3B, TiB2, TiN, Ti2N, TiB, FeN, FeB, Fe2B, and h-BN phases. Its average microhardness in the zone between 0.1-2.8 mm from the coating surface is about Hv0.2 551.5.

A66G and C524T polymorphisms of methionine synthase reductase gene are linked to the development of acyanotic congenital heart diseases in Egyptian children.

PubMed

Hassan, Fahima M; Khattab, Ahmad A; Abo El Fotoh, Wafaa Moustafa M; Zidan, Reham S

2017-09-20

Methionine synthase reductase (MTRR) is one of the main regulatory enzymes in the homocysteine/folate pathway. Genes involved in this pathway may play an important role in the development of congenital heart diseases (CHDs). C524T and A66G polymorphisms of MTRR gene may play an imperative role in the development of acyanotic CHDs. This study carried out on 200 children equally divided into 2 groups: group I: 100 children with acyanotic CHDs; and group II: 100 healthy children served as controls. PCR-RFLP method carried out to amplify the A66G and C524T polymorphisms of MTRR gene digested with Xho1and NdeI enzymes. A significant difference(P=0.015) in genotype frequencies of C524T polymorphism between cases and controls, where CC, CT, and TT were 14.0%, 40.0% and 46.0% in patients compared to 38.0,36.0% and 26.0% in controls. Again, a significant difference (P=0.010) in genotype frequencies of A66G polymorphism between the two groups as AA, AG and GG were 26.0%, 32.0% and42.0% in patients compared to 48.0, 36.0% and 16.0% in controls. Also, MTRR A66G and C524T polymorphisms were associated with a higher CHD risk in the homozygote comparison of wild and mutant genotypes and also in heterozygote and mutant comparison. So A66G and C524T polymorphisms of MTRR gene are associated with increased risk of acyanotic CHDs. Copyright © 2017 Elsevier B.V. All rights reserved.

Near-field heat transfer between graphene/hBN multilayers

NASA Astrophysics Data System (ADS)

Zhao, Bo; Guizal, Brahim; Zhang, Zhuomin M.; Fan, Shanhui; Antezza, Mauro

2017-06-01

We study the radiative heat transfer between multilayer structures made by a periodic repetition of a graphene sheet and a hexagonal boron nitride (hBN) slab. Surface plasmons in a monolayer graphene can couple with hyperbolic phonon polaritons in a single hBN film to form hybrid polaritons that can assist photon tunneling. For periodic multilayer graphene/hBN structures, the stacked metallic/dielectric array can give rise to a further effective hyperbolic behavior, in addition to the intrinsic natural hyperbolic behavior of hBN. The effective hyperbolicity can enable more hyperbolic polaritons that enhance the photon tunneling and hence the near-field heat transfer. However, the hybrid polaritons on the surface, i.e., surface plasmon-phonon polaritons, dominate the near-field heat transfer between multilayer structures when the topmost layer is graphene. The effective hyperbolic regions can be well predicted by the effective medium theory (EMT), thought EMT fails to capture the hybrid surface polaritons and results in a heat transfer rate much lower compared to the exact calculation. The chemical potential of the graphene sheets can be tuned through electrical gating and results in an additional modulation of the heat transfer. We found that the near-field heat transfer between multilayer structures does not increase monotonously with the number of layers in the stack, which provides a way to control the heat transfer rate by the number of graphene layers in the multilayer structure. The results may benefit the applications of near-field energy harvesting and radiative cooling based on hybrid polaritons in two-dimensional materials.

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

PubMed

Chung, Shyan-Lung; Lin, Jeng-Shung

2016-05-20

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

Modification of the electronic properties of hexagonal boron-nitride in BN/graphene vertical heterostructures

DOE PAGES

Pan, Minghu; Liang, Liangbo; Lin, Wenzhi; ...

2016-09-28

Van der Waals (vdW) heterostructures consist of isolated atomic planar structures, assembled layer- by-layer into desired structures in a well-defined sequence. Graphene deposited on hexagonal boron nitride (h-BN) has been first considered as a testbed system for vdW heterostructures, and many others have been demonstrated both theoretically and experimentally, revealing many attractive properties and phenomena. However, much less emphasis has been placed on how graphene actively affects h-BN properties. Here, we perform local probe measurements on single-layer h-BN grown over graphene and highlight the manifestation of a proximity effect that significantly affects the electronic properties of h-BN due to itsmore » coupling with the underlying graphene. We find electronic states originating from the graphene layer and the Cu substrate to be injected into the wide electronic gap of the h-BN top layer. Such proximity effect is further confirmed in a study of the variation of h-BN in-gap states with interlayer couplings, elucidated using a combination of topographical/ spectroscopic measurements and first-principles density functional theory calculations. In conclusion, the findings of this work indicate the potential of mutually engineering electronic properties of the components of vdW heterostructures.« less

Theoretical predictions for hexagonal BN based nanomaterials as electrocatalysts for the oxygen reduction reaction.

PubMed

Lyalin, Andrey; Nakayama, Akira; Uosaki, Kohei; Taketsugu, Tetsuya

2013-02-28

The catalytic activity for the oxygen reduction reaction (ORR) of both the pristine and defect-possessing hexagonal boron nitride (h-BN) monolayer and H-terminated nanoribbon have been studied theoretically using density functional theory. It is demonstrated that an inert h-BN monolayer can be functionalized and become catalytically active by nitrogen doping. It is shown that the energetics of adsorption of O(2), O, OH, OOH, and H(2)O on N atom impurities in the h-BN monolayer (N(B)@h-BN) is quite similar to that known for a Pt(111) surface. The specific mechanism of destructive and cooperative adsorption of ORR intermediates on the surface point defects is discussed. It is demonstrated that accounting for entropy and zero-point energy (ZPE) corrections results in destabilization of the ORR intermediates adsorbed on N(B)@h-BN, while solvent effects lead to their stabilization. Therefore, entropy, ZPE and solvent effects partly cancel each other and have to be taken into account simultaneously. Analysis of the free energy changes along the ORR pathway allows us to suggest that a N-doped h-BN monolayer can demonstrate catalytic properties for the ORR under the condition that electron transport to the catalytically active center is provided.

A comparative DFT study on the interaction of cathinone drug with BN nanotubes, nanocages, and nanosheets

NASA Astrophysics Data System (ADS)

Nejati, Kamellia; Hosseinian, Akram; Vessally, Esmail; Bekhradnia, Ahmadreza; Edjlali, Ladan

2017-11-01

Cathinone is an organic stimulant which is classified as psychoactive drug and its abuse has been linked to many deaths worldwide. Here, we studied the electronic sensitivity of a BN cage, a zigzag (6, 0) BN nanotube, and a BN nanosheet toward cathinone using density functional theory calculations. The B3LYP-D functional predicts that the order of magnitude of electrical conductivity of BN nanostructures is as follows tube > sheet > cage. The cathinone drug prefers to be adsorbed on the BN nanostructures via its sbnd NH2 group rather than O-head with adsorption energy about -16.1, -14.0 and -5.0 kcal/mol for cage, tube, and sheet, respectively. Our results indicate that by increasing the p-character of the hybridization of the adsorbing B atom in the BN nanostructures, the interaction is strengthened. Based on the density of states analysis, it was demonstrated that the electrical conductivity of the BN nanostructures is decreased by the drug adsorption, indicating that they can be used in the cathinone sensors. The order of magnitude of the sensitivity is as follows: SCage > STube > SSheet. This trend corresponds to the decrease of the structural curvature in the BN nanostructures. Finally, a short recovery time of about 0.54 s, 0.02 s and 4.4 ns is predicted for cage, tube and sheet, respectively, at 298 K.

Pressure-induced shift of T c and structural transition in “122” type pnictide superconductor Ca 0.34Na 0.66Fe 2As 2

DOE PAGES

Zhang, Sijia; Zhao, Kan; Yu, Xiaohui; ...

2016-07-11

Here, the effect of pressure on superconductivity of “122” type Ca 1-xNa xFe 2As 2 (x=0.66 single crystal is investigated through the temperature dependence of resistanc measurement. Optimal Na doped (Ca 0.34Na 0.66)Fe 2As 2 shows a superconductin transition with T c ~ 33 K at ambient pressure. With application of pressure, T decreases nearly linearly with d Tc/d P ~ -1.7K/GPa at pressures lower than 2 GPa and disappears gradually at higher pressure. The disappearance of superconductivit is also companied with the recovery of standard Fermi liquid behaviors of th normal-state transport properties. Moreover, (Ca 0.34Na 0.66)Fe 2As 2more » exhibits a tetragona (T) to collapsed-tetragonal (c T) transition at about 3 GPa. The evolution o non-Fermi liquid behaviors and superconductivity under pressure are both relate to the interband fluctuations.« less

Negative Refraction with Superior Transmission in Graphene-Hexagonal Boron Nitride (hBN) Multilayer Hyper Crystal

PubMed Central

Sayem, Ayed Al; Rahman, Md. Masudur; Mahdy, M. R. C.; Jahangir, Ifat; Rahman, Md. Saifur

2016-01-01

In this article, we have theoretically investigated the performance of graphene-hexagonal Boron Nitride (hBN) multilayer structure (hyper crystal) to demonstrate all angle negative refraction along with superior transmission. hBN, one of the latest natural hyperbolic materials, can be a very strong contender to form a hyper crystal with graphene due to its excellence as a graphene-compatible substrate. Although bare hBN can exhibit negative refraction, the transmission is generally low due to its high reflectivity. Whereas due to graphene’s 2D nature and metallic characteristics in the frequency range where hBN behaves as a type-I hyperbolic material, we have found graphene-hBN hyper-crystals to exhibit all angle negative refraction with superior transmission. Interestingly, superior transmission from the whole structure can be fully controlled by the tunability of graphene without hampering the negative refraction originated mainly from hBN. We have also presented an effective medium description of the hyper crystal in the low-k limit and validated the proposed theory analytically and with full wave simulations. Along with the current extensive research on hybridization of graphene plasmon polaritons with (hyperbolic) hBN phonon polaritons, this work might have some substantial impact on this field of research and can be very useful in applications such as hyper-lensing. PMID:27146561

Growth of h-BN on copper (110) in a LEEM

NASA Astrophysics Data System (ADS)

Herrmann, Christoph; Omelchenko, Pavlo; Kavanagh, Karen L.

2018-03-01

Hexagonal boron nitride (h-BN) was grown by borazine vapour deposition on single crystalline Cu (110) substrates at 740 °C. The growth was investigated in situ using a Low-Energy Electron Microscope (LEEM). Substrates were prepared ex situ by mechanical and electrochemical methods and once in the LEEM system, by annealing in a H2 atmosphere resulting in a reconstructed surface. Exposure to borazine vapour resulted in the nucleation of well-aligned trigonal h-BN islands, which merged to ribbons along surface steps, and into larger, more irregularly shaped features. A coverage of up to 60% was achieved with an exposure of 3900 L. A diffraction ring in the low energy electron diffraction pattern was observed with a preferential alignment along the Cu 〈 111 〉 directions of the underlying substrate. Low-energy electron reflectivity scans, as well as x-ray photoelectron and Raman spectroscopies, confirmed the presence of a partial monolayer of h-BN on the surface.

Study of electronic and magnetic properties of h-BN on Ni surfaces: A DFT approach

NASA Astrophysics Data System (ADS)

Sahoo, M. R.; Sahu, S.; Kushwaha, A. K.; Nayak, S.

2018-04-01

Hexagonal boron nitride (h-BN) is a promising material for implementation in spintronics due to large band gap, low spin-orbit coupling, and a small lattice mismatch to graphene and close-packedsurfaces of fcc-Ni(111). Electronic and magnetic properties of single layer hexagonal Boron Nitride (h-BN) on Ni (111) surface have been studied with density functional calculation. Since lattice constants of nickel surfaces are very close to that of h-BN, nickel acts as a good substrate. We found that the interaction between 2Pz - 3dz2 orbitals leads to change in electronic band structure as well as density of states which results spin polarization in h-BN.

CBT4BN versus CBTF2F: Comparison of Online versus Face-To-FaceTreatment for Bulimia Nervosa

PubMed Central

Bulik, Cynthia M.; Marcus, Marsha D.; Zerwas, Stephanie; Levine, Michele D.; Hofmeier, Sara; Trace, Sara E.; Hamer, Robert M.; Zimmer, Benjamin; Moessner, Markus; Kordy, Hans

2012-01-01

Cognitive-behavioral therapy (CBT) is currently the “gold standard” for treatment of bulimia nervosa (BN), and is effective for approximately 40–60% of individuals receiving treatment; however, the majority of individuals in need of care do not have access to CBT. New strategies for service delivery of CBT and for maximizing maintenance of treatment benefits are critical for improving our ability to treat BN. This clinical trial is comparing an Internet-based version of CBT (CBT4BN) in which group intervention is conducted via therapeutic chat group with traditional group CBT (CBTF2F) for BN conducted via face-to-face therapy group. The purpose of the trial is to determine whether manualized CBT delivered via the Internet is not inferior to the gold standard of manualized group CBT. In this two-site randomized controlled trial, powered for non-inferiority analyses, 180 individuals with BN are being randomized to either CBT4BN or CBTF2F. We hypothesize that CBT4BN will not be inferior to CBTF2F and that participants will value the convenience of an online intervention. If not inferior, CBT4BN may be a cost-effective approach to service delivery for individuals requiring treatment for BN. PMID:22659072

Knowledge of Pest Resistance in SiC/BN/SiC Composites Improved

NASA Technical Reports Server (NTRS)

Thomas-Ogbuji, Linus U.

2002-01-01

Ceramic-matrix composites (CMC's) consisting of a silicon carbide matrix reinforced with boron-nitride- (BN-) coated silicon carbide (SiC) fibers are strong contenders for commercial and aerospace applications (in particular, the hot sections of high-performance turbine engines in advanced aircraft and generators). They have very good mechanical properties below approximately 600 C and above approximately 1000 C. Between those temperatures, however, the BN coating oxidizes easily, and the oxidation of the SiC matrix is too sluggish to seal off the composite with a protective layer of silica. In that temperature interval, the preferential oxidation of the BN weakens and embrittles the composite. That phenomenon, referred to as "pest" degradation, is the focus of this work, which aims to identify the causes of and remedies for pesting. Previous work established that pesting in Hi-Nicalon (Nippon Carbon Co., Ltd., Japan)/SiC composites was caused by a layer of free carbon that undermined the oxidation resistance of the BN. New work suggests that composites containing a source of carbon are prone to severe pesting and that those that are free of elemental carbon are resistant pesting. Pest resistance was assessed by exposing machined samples for 100 to 150 hr in an atmospheric burner rig at 600 to 1100 C, followed by a tensile fracture test to measure residual mechanical properties and by characterization of the interphase microstructure. Whether the elemental carbon came from intrinsic or extrinsic sources, its presence induced the tensile strength to drop by over 50 percent in the burner rig, with an even more severe loss of fracture strain. A likely mechanism by which burnoff of the carbon layer exposes the BN to accelerated flank attack by ambient oxidants is shown. The BN is replaced with borosilicates that attack the fiber, and ultimately with silica that embrittles the composites by rigidly bonding components. Thus, the study has shown that pesting can be

Elastic and Plastic Behavior of an Ultrafine-Grained Mg Reinforced with BN Nanoparticles

NASA Astrophysics Data System (ADS)

Trojanová, Zuzanka; Dash, Khushbu; Máthis, Kristián; Lukáč, Pavel; Kasakewitsch, Alla

2018-04-01

Pure microcrystalline magnesium (µMg) was reinforced with hexagonal boron nitride (hBN) nanoparticles and was fabricated by powder metallurgy process followed by hot extrusion. For comparison pure magnesium powder was consolidated by hot extrusion too. Both materials exhibited a significant fiber texture. Mg-hBN nanocomposites (nc) and pure Mg specimens were deformed between room temperature and 300 °C under tension and compression mode. The yield strength and ultimate tensile and compression strength as well as characteristic stresses were evaluated and reported. The tensile and compressive strengths of Mg-hBN nc are quiet superior in values compared to monolithic counterpart as well as Mg alloys. The compressive yield strength of µMg was recorded as 90 MPa, whereas the Mg-hBN nancomposite shows 125 MPa at 200 °C. The tensile yield strength of µMg was computed as 67 MPa which is quite lower as compared to Mg-hBN nanocomposite's value which was recorded as 157 MPa at 200 °C. Under tensile stress the true stress-strain curves are flat in nature, whereas the stress-strain curves observed in compression at temperatures up to 100 °C exhibited small local maxima at the onset of deformation followed by a significant work hardening.

111In-BnDTPA-F3: an Auger electron-emitting radiotherapeutic agent that targets nucleolin

PubMed Central

2012-01-01

Introduction The F3 peptide (KDEPQRRSARLSAKPAPPKPEPKPKKAPAKK), a fragment of the human high mobility group protein 2, binds nucleolin. Nucleolin is expressed in the nuclei of normal cells but is also expressed on the membrane of some cancer cells. The goal was to investigate the use of 111In-labeled F3 peptide for Auger electron-targeted radiotherapy. Methods F3 was labeled with fluorescein isothiocyanate (FITC) for confocal microscopy and conjugated to p-SCN-benzyl-diethylenetriaminepentaacetic acid (BnDTPA) for labeling with 111In to form 111In-BnDTPA-F3. MDA-MB-231-H2N (231-H2N) human breast cancer cells were exposed to 111In-BnDTPA-F3 and used in cell fractionation, γH2AX immunostaining (a marker of DNA double-strand breaks), and clonogenic assays. In vivo, biodistribution studies of 111In-BnDTPA-F3 were performed in 231-H2N xenograft-bearing mice. In tumor growth delay studies, 111In-BnDTPA-F3 (3 μg, 6 MBq/μg) was administered intravenously to 231-H2N xenograft-bearing mice once weekly for 3 weeks. Results Membrane-binding of FITC-F3 was observed in 231-H2N cells, and there was co-localization of FITC-F3 with nucleolin in the nuclei. After exposure of 231-H2N cells to 111In-BnDTPA-F3 for 2 h, 1.7% of 111In added to the medium was membrane-bound. Of the bound 111In, 15% was internalized, and of this, 37% was localized in the nucleus. Exposure of 231-H2N cells to 111In-BnDTPA-F3 (1 μM, 6 MBq/μg) resulted in a dose-dependent increase in γH2AX foci and in a significant reduction of clonogenic survival compared to untreated cells or cells exposed to unlabeled BnDTPA-F3 (46 ± 4.1%, 100 ± 1.8%, and 132 ± 7.7%, respectively). In vivo, tumor uptake of 111In-BnDTPA-F3 (3 μg, 6 MBq/μg) at 3-h post-injection was 1% of the injected dose per gram (%ID/g), and muscle uptake was 0.5%ID/g. In tumor growth delay studies, tumor growth rate was reduced 19-fold compared to untreated or unlabeled BnDTPA-F3-treated mice (p = 0.023). Conclusion 111In-BnDTPA-F3 is

111In-BnDTPA-F3: an Auger electron-emitting radiotherapeutic agent that targets nucleolin.

PubMed

Cornelissen, Bart; Waller, Andrew; Target, Carol; Kersemans, Veerle; Smart, Sean; Vallis, Katherine A

2012-02-20

The F3 peptide (KDEPQRRSARLSAKPAPPKPEPKPKKAPAKK), a fragment of the human high mobility group protein 2, binds nucleolin. Nucleolin is expressed in the nuclei of normal cells but is also expressed on the membrane of some cancer cells. The goal was to investigate the use of 111In-labeled F3 peptide for Auger electron-targeted radiotherapy. F3 was labeled with fluorescein isothiocyanate (FITC) for confocal microscopy and conjugated to p-SCN-benzyl-diethylenetriaminepentaacetic acid (BnDTPA) for labeling with 111In to form 111In-BnDTPA-F3. MDA-MB-231-H2N (231-H2N) human breast cancer cells were exposed to 111In-BnDTPA-F3 and used in cell fractionation, γH2AX immunostaining (a marker of DNA double-strand breaks), and clonogenic assays. In vivo, biodistribution studies of 111In-BnDTPA-F3 were performed in 231-H2N xenograft-bearing mice. In tumor growth delay studies, 111In-BnDTPA-F3 (3 μg, 6 MBq/μg) was administered intravenously to 231-H2N xenograft-bearing mice once weekly for 3 weeks. Membrane-binding of FITC-F3 was observed in 231-H2N cells, and there was co-localization of FITC-F3 with nucleolin in the nuclei. After exposure of 231-H2N cells to 111In-BnDTPA-F3 for 2 h, 1.7% of 111In added to the medium was membrane-bound. Of the bound 111In, 15% was internalized, and of this, 37% was localized in the nucleus. Exposure of 231-H2N cells to 111In-BnDTPA-F3 (1 μM, 6 MBq/μg) resulted in a dose-dependent increase in γH2AX foci and in a significant reduction of clonogenic survival compared to untreated cells or cells exposed to unlabeled BnDTPA-F3 (46 ± 4.1%, 100 ± 1.8%, and 132 ± 7.7%, respectively). In vivo, tumor uptake of 111In-BnDTPA-F3 (3 μg, 6 MBq/μg) at 3-h post-injection was 1% of the injected dose per gram (%ID/g), and muscle uptake was 0.5%ID/g. In tumor growth delay studies, tumor growth rate was reduced 19-fold compared to untreated or unlabeled BnDTPA-F3-treated mice (p = 0.023). 111In-BnDTPA-F3 is internalized into 231-H2N cells and translocates

Effect of substrate temperature and gas flow ratio on the nanocomposite TiAlBN coating

NASA Astrophysics Data System (ADS)

Rosli, Z. M.; Kwan, W. L.; Juoi, J. M.

2016-07-01

Nanocomposite TiAlBN (nc-TiAlBN) coatings were successfully deposited via RF magnetron sputtering by varying the nitrogen-to-total gas flow ratio (RN), and substrate temperature (TS). All coatings were deposited on AISI 316 substrates using single Ti-Al-BN hot-pressed disc as a target. The grain size, phases, and chemical composition of the coatings were evaluated using glancing angle X-ray diffraction analysis (GAXRD) and X-ray photoelectron spectroscopy (XPS). Results showed that the grains size of the deposited nc-TiAlBN coatings were in the range of 3.5 to 5.7 nm and reached a nitride saturation state as early as 15 % RN. As the nitrogen concentration decreases, boron concentration increased from 9 at.% to 16.17 at.%. and thus, increase the TiB2 phase within the coatings. The TS, however, showed no significant effect either on the crystallographic structure, grain size, or in the chemical composition of the deposited nc-TiAlBN coating.

DFT simulation on H2 adsorption over Ni-decorated defective h-BN nanosheets

NASA Astrophysics Data System (ADS)

Zhou, Xuan; Chu, Wei; Zhou, Yanan; Sun, Wenjing; Xue, Ying

2018-05-01

Nickel doped defective h-BN nanosheets and their potential application on hydrogen storage were explored by density functional theory (DFT) calculation. Three types of defective h-BN (SW defect, VB and VN substrates) were modeled. In comparison with the SW defect, the B or N vacancy can improve the interaction between Ni atom and h-BN nanosheet strikingly. Furthermore, the Ni-doped SW defect sheet shows chemisorption on H2 molecules, and the Hsbnd H bond is partially dissociated. While on the VB sheet, Ni adatom interacts with H2 in the range of physisorption. However, the Ni-functionalized VN sheet exhibits a desirable adsorption on H2, and the corresponding energy varies from -0.40 to -0.51 eV, which is favorable for H2 adsorption and release at ambient conditions. As a result, the VN substrate is expected to a desirable support for H2 storage. Our work provides an insight into H2 storage on Ni-functionalized defective h-BN monolayer.

The modulation of Schottky barriers of metal-MoS2 contacts via BN-MoS2 heterostructures.

PubMed

Su, Jie; Feng, Liping; Zhang, Yan; Liu, Zhengtang

2016-06-22

Using first-principles calculations within density functional theory, we systematically studied the effect of BN-MoS2 heterostructure on the Schottky barriers of metal-MoS2 contacts. Two types of FETs are designed according to the area of the BN-MoS2 heterostructure. Results show that the vertical and lateral Schottky barriers in all the studied contacts, irrespective of the work function of the metal, are significantly reduced or even vanish when the BN-MoS2 heterostructure substitutes the monolayer MoS2. Only the n-type lateral Schottky barrier of Au/BN-MoS2 contact relates to the area of the BN-MoS2 heterostructure. Notably, the Pt-MoS2 contact with n-type character is transformed into a p-type contact upon substituting the monolayer MoS2 by a BN-MoS2 heterostructure. These changes of the contact natures are ascribed to the variation of Fermi level pinning, work function and charge distribution. Analysis demonstrates that the Fermi level pinning effects are significantly weakened for metal/BN-MoS2 contacts because no gap states dominated by MoS2 are formed, in contrast to those of metal-MoS2 contacts. Although additional BN layers reduce the interlayer interaction and the work function of the metal, the Schottky barriers of metal/BN-MoS2 contacts still do not obey the Schottky-Mott rule. Moreover, different from metal-MoS2 contacts, the charges transfer from electrodes to the monolayer MoS2, resulting in an increment of the work function of these metals in metal/BN-MoS2 contacts. These findings may prove to be instrumental in the future design of new MoS2-based FETs with ohmic contact or p-type character.

2D Hexagonal Boron Nitride (2D-hBN) Explored for the Electrochemical Sensing of Dopamine.

PubMed

Khan, Aamar F; Brownson, Dale A C; Randviir, Edward P; Smith, Graham C; Banks, Craig E

2016-10-04

Crystalline 2D hexagonal boron nitride (2D-hBN) nanosheets are explored as a potential electrocatalyst toward the electroanalytical sensing of dopamine (DA). The 2D-hBN nanosheets are electrically wired via a drop-casting modification process onto a range of commercially available carbon supporting electrodes, including glassy carbon (GC), boron-doped diamond (BDD), and screen-printed graphitic electrodes (SPEs). 2D-hBN has not previously been explored toward the electrochemical detection/electrochemical sensing of DA. We critically evaluate the potential electrocatalytic performance of 2D-hBN modified electrodes, the effect of supporting carbon electrode platforms, and the effect of "mass coverage" (which is commonly neglected in the 2D material literature) toward the detection of DA. The response of 2D-hBN modified electrodes is found to be largely dependent upon the interaction between 2D-hBN and the underlying supporting electrode material. For example, in the case of SPEs, modification with 2D-hBN (324 ng) improves the electrochemical response, decreasing the electrochemical oxidation potential of DA by ∼90 mV compared to an unmodified SPE. Conversely, modification of a GC electrode with 2D-hBN (324 ng) resulted in an increased oxidation potential of DA by ∼80 mV when compared to the unmodified electrode. We explore the underlying mechanisms of the aforementioned examples and infer that electrode surface interactions and roughness factors are critical considerations. 2D-hBN is utilized toward the sensing of DA in the presence of the common interferents ascorbic acid (AA) and uric acid (UA). 2D-hBN is found to be an effective electrocatalyst in the simultaneous detection of DA and UA at both pH 5.0 and 7.4. The peak separations/resolution between DA and UA increases by ∼70 and 50 mV (at pH 5.0 and 7.4, respectively, when utilizing 108 ng of 2D-hBN) compared to unmodified SPEs, with a particularly favorable response evident in pH 5.0, giving rise to a

High operating temperature nBn detector with monolithically integrated microlens

NASA Astrophysics Data System (ADS)

Soibel, Alexander; Keo, Sam A.; Fisher, Anita; Hill, Cory J.; Luong, Edward; Ting, David Z.; Gunapala, Sarath D.; Lubyshev, Dmitri; Qiu, Yueming; Fastenau, Joel M.; Liu, Amy W. K.

2018-01-01

We demonstrate an InAsSb nBn detector monolithically integrated with a microlens fabricated on the back side of the detector. The increase in the optical collection area of the detector resulted in a five-fold enhancement of the responsivity to Rp = 5.5 A/W. The responsivity increases further to Rp = 8.5 A/W with an antireflection coating. These 4.5 μm cut-off wavelength antireflection coated detectors with microlenses exhibited a detectivity of D* (λ) = 2.7 × 1010 cmHz0.5/W at T = 250 K, which can be reached easily with a single-stage thermoelectric cooler or with a passive radiator in the space environment. This represents a 25 K increase in the operating temperature of these devices compared to the uncoated detectors without an integrated microlens.

Stability, Elastic Properties, and Deformation of LiBN2: A Potential High-Energy Material.

PubMed

Zhu, Chunye; Zhu, Wenjun; Yang, Yanqiang

2018-05-15

Searching for high-energy-density materials is of great interest in scientific research and for industrial applications. Using an unbiased structure prediction method and first-principles calculations, we investigated the phase stability of LiBN 2 from 0 to100 GPa. Two new structures with space groups P4̅2 1 m and Pnma were discovered. The theoretical calculations revealed that Pnma LiBN 2 is stable with respect to a mixture of 1 / 3 Li 3 N, BN, and 1 / 3 N 2 above 22 GPa. The electronic band structure revealed that Pnma LiBN 2 has an indirect band gap of 2.3 eV, which shows a nonmetallic feature. The Pnma phase has a high calculated bulk modulus and shear modulus, indicating its incompressible nature. The microscopic mechanism of the structural deformation was demonstrated by ideal tensile shear strength calculations. It is worth mentioning that Pnma LiBN 2 is dynamically stable under ambient conditions. The decomposition of this phase is exothermic, releasing an energy of approximately 1.23 kJ/g at the PBE level. The results provide new thoughts for designing and synthesizing novel high-energy compounds in ternary systems.

Initial stages of growth and the influence of temperature during chemical vapor deposition of sp{sup 2}-BN films

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

Chubarov, Mikhail; Pedersen, Henrik; Högberg, Hans

2015-11-15

Knowledge of the structural evolution of thin films, starting by the initial stages of growth, is important to control the quality and properties of the film. The authors present a study on the initial stages of growth and the temperature influence on the structural evolution of sp{sup 2} hybridized boron nitride (BN) thin films during chemical vapor deposition (CVD) with triethyl boron and ammonia as precursors. Nucleation of hexagonal BN (h-BN) occurs at 1200 °C on α-Al{sub 2}O{sub 3} with an AlN buffer layer (AlN/α-Al{sub 2}O{sub 3}). At 1500 °C, h-BN grows with a layer-by-layer growth mode on AlN/α-Al{sub 2}O{sub 3} upmore » to ∼4 nm after which the film structure changes to rhombohedral BN (r-BN). Then, r-BN growth proceeds with a mixed layer-by-layer and island growth mode. h-BN does not grow on 6H-SiC substrates; instead, r-BN nucleates and grows directly with a mixed layer-by-layer and island growth mode. These differences may be caused by differences in substrate surface temperature due to different thermal conductivities of the substrate materials. These results add to the understanding of the growth process of sp{sup 2}-BN employing CVD.« less

Influence of BN fiber coatings on the interfacial structure of sapphire fiber reinforced NiAl composites

NASA Astrophysics Data System (ADS)

Reichert, K.; Wen, K.; Cremer, R.; Hu, W.; Neuschütz, D.; Gottstein, G.

2001-07-01

A new concept for a tailored fiber-matrix interface for sapphire fiber reinforced NiAl matrix composites is proposed, consisting of an initial hexagonal boron nitride (hBN) fiber coating. For this, single crystal Al 2O 3 fibers were coated with hBN by chemical vapor deposition (CVD). Following a comprehensive characterization of the CVD coating as to composition and structure by means of X-ray photoelectron spectroscopy (XPS) and grazing incidence X-ray diffraction (GIXRD), the fiber reinforced NiAl matrix composites were fabricated by diffusion bonding at 1400°C. The interfaces NiAl/BN and BN/Al 2O 3 were analyzed by scanning electron microscopy (SEM), analytical transmission electron microscopy (TEM), and selected area diffraction (SAD). An interfacial reaction between NiAl and hBN to form AlN was revealed using these analytical techniques.

Effect of BN coating on the strength of a mullite type fiber

NASA Astrophysics Data System (ADS)

Chawla, K. K.; Xu, Z. R.; Ha, J.-S.; Schmücker, M.; Schneider, H.

1997-09-01

Nextel 480 is a polycrystalline essentially mullite fiber (70 wt.-% Al2O3+28 wt.-% SiO2+2 wt.-% B2O3). Different thicknesses of BN were applied as coatings on this fiber. Optical, scanning electron, and transmission electron microscopy were used to characterize the microstructure of the coatings and fibers. The effects of coating and high temperature exposure on the fiber strength were investigated using two-parameter Weibull distribution. TEM examination showed that the BN coating has a turbostratic structure, with the basal planes lying predominantly parallel to the fiber surface. Such an orientation of coating is desirable for easy crack deflection and subsequent fiber pullout in a composite. The BN coated Nextel 480 fiber showed that Weibull mean strength increased first and then decreased with increasing coating thickness. This was due to the surface flaw healing effect of the coating (up to 0.3 μm) while in the case of thick BN coating (1 μm), the soft nature of the coating material had a more dominant effect and resulted in a decrease of the fiber strength. High temperature exposure of Nextel 480 resulted in grain growth, which led to a strength loss.

Calculation of the octanol-water partition coefficient of armchair polyhex BN nanotubes

NASA Astrophysics Data System (ADS)

Mohammadinasab, E.; Pérez-Sánchez, H.; Goodarzi, M.

2017-12-01

A predictive model for determination partition coefficient (log P) of armchair polyhex BN nanotubes by using simple descriptors was built. The relationship between the octanol-water log P and quantum chemical descriptors, electric moments, and topological indices of some armchair polyhex BN nanotubes with various lengths and fixed circumference are represented. Based on density functional theory electric moments and physico-chemical properties of those nanotubes are calculated.

Solid Oxide Fuel Cell Seal Glass - BN Nanotubes Composites

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Choi, Sung R.; Hurst, Janet B.; Garg, Anita

2005-01-01

Solid oxide fuel cell seal glass G18 composites reinforced with approx.4 weight percent of BN nanotubes were fabricated via hot pressing. Room temperature strength and fracture toughness of the composite were determined by four-point flexure and single edge V-notch beam methods, respectively. The strength and fracture toughness of the composite were higher by as much as 90% and 35%, respectively, than those of the glass G18. Microscopic examination of the composite fracture surfaces using SEM and TEM showed pullout of the BN nanotubes, similar in feature to fiber-reinforced ceramic matrix composites with weak interfaces. Other mechanical and physical properties of the composite will also be presented.

Acoustically-driven surface and hyperbolic plasmon-phonon polaritons in graphene/h-BN heterostructures on piezoelectric substrates

NASA Astrophysics Data System (ADS)

Fandan, R.; Pedrós, J.; Schiefele, J.; Boscá, A.; Martínez, J.; Calle, F.

2018-05-01

Surface plasmon polaritons in graphene couple strongly to surface phonons in polar substrates leading to hybridized surface plasmon-phonon polaritons (SPPPs). We demonstrate that a surface acoustic wave (SAW) can be used to launch propagating SPPPs in graphene/h-BN heterostructures on a piezoelectric substrate like AlN, where the SAW-induced surface modulation acts as a dynamic diffraction grating. The efficiency of the light coupling is greatly enhanced by the introduction of the h-BN film as compared to the bare graphene/AlN system. The h-BN interlayer not only significantly changes the dispersion of the SPPPs but also enhances their lifetime. The strengthening of the SPPPs is shown to be related to both the higher carrier mobility induced in graphene and the coupling with h-BN and AlN surface phonons. In addition to surface phonons, hyperbolic phonons polaritons (HPPs) appear in the case of multilayer h-BN films leading to hybridized hyperbolic plasmon-phonon polaritons (HPPPs) that are also mediated by the SAW. These results pave the way for engineering SAW-based graphene/h-BN plasmonic devices and metamaterials covering the mid-IR to THz range.

Template-Free Synthesis of Functional 3D BN architecture for removal of dyes from water

PubMed Central

Liu, Dan; Lei, Weiwei; Qin, Si; Chen, Ying

2014-01-01

Three-dimensional (3D) architectures are of interest in applications in electronics, catalysis devices, sensors and adsorption materials. However, it is still a challenge to fabricate 3D BN architectures by a simple method. Here, we report the direct synthesis of 3D BN architectures by a simple thermal treatment process. A 3D BN architecture consists of an interconnected flexible network of nanosheets. The typical nitrogen adsorption/desorption results demonstrate that the specific surface area for the as-prepared samples is up to 1156 m2 g−1, and the total pore volume is about 1.17 cm3 g−1. The 3D BN architecture displays very high adsorption rates and large capacities for organic dyes in water without any other additives due to its low densities, high resistance to oxidation, good chemical inertness and high surface area. Importantly, 88% of the starting adsorption capacity is maintained after 15 cycles. These results indicate that the 3D BN architecture is potential environmental materials for water purification and treatment. PMID:24663292

Template-free synthesis of functional 3D BN architecture for removal of dyes from water.

PubMed

Liu, Dan; Lei, Weiwei; Qin, Si; Chen, Ying

2014-03-25

Three-dimensional (3D) architectures are of interest in applications in electronics, catalysis devices, sensors and adsorption materials. However, it is still a challenge to fabricate 3D BN architectures by a simple method. Here, we report the direct synthesis of 3D BN architectures by a simple thermal treatment process. A 3D BN architecture consists of an interconnected flexible network of nanosheets. The typical nitrogen adsorption/desorption results demonstrate that the specific surface area for the as-prepared samples is up to 1156 m(2) g(-1), and the total pore volume is about 1.17 cm(3) g(-1). The 3D BN architecture displays very high adsorption rates and large capacities for organic dyes in water without any other additives due to its low densities, high resistance to oxidation, good chemical inertness and high surface area. Importantly, 88% of the starting adsorption capacity is maintained after 15 cycles. These results indicate that the 3D BN architecture is potential environmental materials for water purification and treatment.

Growth of 2D heterostructures of graphene/BN

NASA Astrophysics Data System (ADS)

Hwang, Jeonghyun; Calderon, Brian R.; Alsalman, Hussain A.; Kwak, Joon Young; Kim, Moonkyung; Spencer, Michael G.

2014-06-01

Metal free direct growth of graphene on h-BN using a high temperature (~1550°C) chemical vapor deposition technique was done under Ar environment. Growth temperature, methane partial pressure, hydrogen/methane flow ratio, and growth time were varied and optimized. Raman spectroscopy clearly showed the signature of graphene with G- (~1580cm-1) and 2D-mode (~2700cm-1). The smallest width of G- and 2D-peak was 30 and 55cm-1, respectively, and the Raman I2D/IG ratio varied between 0.7 and 1.8. Raman D-peak (~1350cm-1) shows a strong dependence on growth temperature with the smallest ID/IG value of 0.15 at 1550°C. In the case of long growth, nitrogen and boron doping were detected by x-ray photoelectron spectroscopy with a small Raman D'-peak. A continuous graphene film with the rms roughness (1×1 μm2 area) of 0.32nm was shown by atomic force microscopy. Early stage of growth revealed circular shaped nucleation islands, the density and heights of which are ~15/μm2 and 1-2 graphene monolayer (ML), respectively. The hydrogen/methane flow ratio was found to be a critical parameter to obtain smooth 2D growth. Growth of h-BN is performed with ammonia borane, hydrogen and Ar. The growth is found to be critically dependent on the conditions of the ammonia boran precursor. Reproducible continuous films of h-BN are reported.

Improved Performance of h-BN Encapsulated Double Gate Graphene Nanomesh Field Effect Transistor for Short Channel Length

NASA Astrophysics Data System (ADS)

Tiwari, Durgesh Laxman; Sivasankaran, K.

This paper presents improved performance of Double Gate Graphene Nanomesh Field Effect Transistor (DG-GNMFET) with h-BN as substrate and gate oxide material. The DC characteristics of 0.95μm and 5nm channel length devices are studied for SiO2 and h-BN substrate and oxide material. For analyzing the ballistic behavior of electron for 5nm channel length, von Neumann boundary condition is considered near source and drain contact region. The simulated results show improved saturation current for h-BN encapsulated structure with two times higher on current value (0.375 for SiO2 and 0.621 for h-BN) as compared to SiO2 encapsulated structure. The obtained result shows h-BN to be a better substrate and oxide material for graphene electronics with improved device characteristics.

Investigation of structure and mechanical properties of plasma vapor deposited nanocomposite TiBN films

NASA Astrophysics Data System (ADS)

Han, Bin; Neena, D.; Wang, Zesong; Kondamareddy, K. k.; Li, Na; Zuo, Wenbin; Yan, Shaojian; Liu, Chuansheng; Fu, Dejun

2017-04-01

TiBN coatings have huge potential applications as they have excellent properties with increasing modern industrial requirements. Nanocomposite TiBN coatings were synthesized on cemented carbide, high speed steel and Si substrates by using cathodic arc plasma ion plating from pure TiB2 ceramic targets. The structure and mechanical properties of the TiBN coatings were significantly influenced by the nitrogen partial pressure. Rutherford backscattering spectrometry demonstrates that the nitrogen content of the coating varied from 2.8% to 34.5% and high-resolution electron microscopy images reveal that all coatings have the characteristic of nanocrystals embedded in an amorphous matrix. The root-mean-square roughness of the coatings increases from 3.73 to 14.64 nm and the coefficients of friction of the coatings at room temperature vary from 0.54 to 0.73 with increasing nitrogen partial pressure. The microhardness of the coating increases up to 35.7 GPa at 10 sccm N2 flow rate. The smallest wear rate is 2.65 × 10-15 m3 N-1 m-1 which indicates that TiBN coatings have excellent wear resistance. The adhesion test revealed that the TiBN coatings have good adhesion at low nitrogen partial pressure.

Temperature Dependence of Raman-Active In-Plane E2g Phonons in Layered Graphene and h-BN Flakes

NASA Astrophysics Data System (ADS)

Li, Xiaoli; Liu, Jian; Ding, Kai; Zhao, Xiaohui; Li, Shuai; Zhou, Wenguang; Liang, Baolai

2018-01-01

Thermal properties of sp2 systems such as graphene and hexagonal boron nitride (h-BN) have attracted significant attention because of both systems being excellent thermal conductors. This research reports micro-Raman measurements on the in-plane E2g optical phonon peaks ( 1580 cm-1 in graphene layers and 1362 cm-1 in h-BN layers) as a function of temperature from - 194 to 200 °C. The h-BN flakes show higher sensitivity to temperature-dependent frequency shifts and broadenings than graphene flakes. Moreover, the thermal effect in the c direction on phonon frequency in h-BN layers is more sensitive than that in graphene layers but on phonon broadening in h-BN layers is similar as that in graphene layers. These results are very useful to understand the thermal properties and related physical mechanisms in h-BN and graphene flakes for applications of thermal devices.

Functional Identification and Characterization of the Brassica Napus Transcription Factor Gene BnAP2, the Ortholog of Arabidopsis Thaliana APETALA2

PubMed Central

Xiong, Zhiyong; Chen, Chunli; Wang, Lijun; Yu, Jingyin; Lu, Changming; Wei, Wenhui

2012-01-01

BnAP2, an APETALA2 (AP2)-like gene, has been isolated from Brassica napus cultivar Zhongshuang 9. The cDNA of BnAP2, with 1, 299 bp in length, encoded a transcription factor comprising of 432 amino acid residues. Results from complementary experiment indicated that BnAP2 was completely capable of restoring the phenotype of Arabidopsis ap2-11 mutant. Together with the sequence and expression data, the complementation data suggested that BnAP2 encodes the ortholog of AtAP2. To address the transcriptional activation of BnAP2, we performed transactivation assays in yeast. Fusion protein of BnAP2 with GAL4 DNA binding domain strongly activated transcription in yeast, and the transactivating activity of BnAP2 was localized to the N-terminal 100 amino acids. To further study the function of BnAP2 involved in the phenotype of B. napus, we used a transgenic approach that involved targeted RNA interference (RNAi) repression induced by ihp-RNA. Floral various phenotype defectives and reduced female fertility were observed in B. napus BnAP2-RNAi lines. Loss of the function of BnAP2 gene also resulted in delayed sepal abscission and senescence with the ethylene-independent pathway. In the strong BnAP2-RNAi lines, seeds showed defects in shape, structure and development and larger size. Strong BnAP2-RNAi and wild-type seeds initially did not display a significant difference in morphology at 10 DAF, but the development of BnAP2-RNAi seeds was slower than that of wild type at 20 DAF, and further at 30 DAF, wild-type seeds were essentially at their final size, whereas BnAP2-RNAi seeds stopped growing and developing and gradually withered. PMID:22479468

Functional identification and characterization of the Brassica napus transcription factor gene BnAP2, the ortholog of Arabidopsis thaliana APETALA2.

PubMed

Yan, Xiaohong; Zhang, Lei; Chen, Bo; Xiong, Zhiyong; Chen, Chunli; Wang, Lijun; Yu, Jingyin; Lu, Changming; Wei, Wenhui

2012-01-01

BnAP2, an APETALA2 (AP2)-like gene, has been isolated from Brassica napus cultivar Zhongshuang 9. The cDNA of BnAP2, with 1, 299 bp in length, encoded a transcription factor comprising of 432 amino acid residues. Results from complementary experiment indicated that BnAP2 was completely capable of restoring the phenotype of Arabidopsis ap2-11 mutant. Together with the sequence and expression data, the complementation data suggested that BnAP2 encodes the ortholog of AtAP2. To address the transcriptional activation of BnAP2, we performed transactivation assays in yeast. Fusion protein of BnAP2 with GAL4 DNA binding domain strongly activated transcription in yeast, and the transactivating activity of BnAP2 was localized to the N-terminal 100 amino acids. To further study the function of BnAP2 involved in the phenotype of B. napus, we used a transgenic approach that involved targeted RNA interference (RNAi) repression induced by ihp-RNA. Floral various phenotype defectives and reduced female fertility were observed in B. napus BnAP2-RNAi lines. Loss of the function of BnAP2 gene also resulted in delayed sepal abscission and senescence with the ethylene-independent pathway. In the strong BnAP2-RNAi lines, seeds showed defects in shape, structure and development and larger size. Strong BnAP2-RNAi and wild-type seeds initially did not display a significant difference in morphology at 10 DAF, but the development of BnAP2-RNAi seeds was slower than that of wild type at 20 DAF, and further at 30 DAF, wild-type seeds were essentially at their final size, whereas BnAP2-RNAi seeds stopped growing and developing and gradually withered.

Plasma synthesis and HPHT consolidation of BN nanoparticles, nanospheres, and nanotubes to produce nanocrystalline cubic boron nitride

NASA Astrophysics Data System (ADS)

Stout, Christopher

Plasma methods offer a variety of advantages to nanomaterials synthesis. The process is robust, allowing varying particle sizes and phases to be generated simply by modifying key parameters. The work here demonstrates a novel approach to nanopowder synthesis using inductively-coupled plasma to decompose precursor, which are then quenched to produce a variety of boron nitride (BN)-phase nanoparticles, including cubic phase, along with short-range-order nanospheres (e.g., nano-onions) and BN nanotubes. Cubic BN (c-BN) powders can be generated through direct deposition onto a chilled substrate. The extremely-high pyrolysis temperatures afforded by the equilibrium plasma offer a unique particle growth environment, accommodating long deposition times while exposing resulting powders to temperatures in excess of 5000K without any additional particle nucleation and growth. Such conditions can yield short-range ordered amorphous BN structures in the form of 20nm diameter nanospheres. Finally, when introducing a rapid-quenching counter-flow gas against the plasma jet, high aspect ratio nanotubes are synthesized, which are collected on substrate situated radially. The benefits of these morphologies are also evident in high-pressure/high-temperature consolidation experiments, where nanoparticle phases can offer a favorable conversion route to super-hard c-BN while maintaining nanocrystallinity. Experiments using these morphologies are shown to begin to yield c-BN conversion at conditions as low as 2.0 GPa and 1500°C when using micron sized c-BN seeding to create localized regions of high pressures due to Hertzian forces acting on the nanoparticles.

Suppression of Lateral Diffusion and Surface Leakage Currents in nBn Photodetectors Using an Inverted Design

NASA Astrophysics Data System (ADS)

Du, X.; Savich, G. R.; Marozas, B. T.; Wicks, G. W.

2018-02-01

Surface leakage and lateral diffusion currents in InAs-based nBn photodetectors have been investigated. Devices fabricated using a shallow etch processing scheme that etches through the top contact and stops at the barrier exhibited large lateral diffusion current but undetectably low surface leakage. Such large lateral diffusion current significantly increased the dark current, especially in small devices, and causes pixel-to-pixel crosstalk in detector arrays. To eliminate the lateral diffusion current, two different approaches were examined. The conventional solution utilized a deep etch process, which etches through the top contact, barrier, and absorber. This deep etch processing scheme eliminated lateral diffusion, but introduced high surface current along the device mesa sidewalls, increasing the dark current. High device failure rate was also observed in deep-etched nBn structures. An alternative approach to limit lateral diffusion used an inverted nBn structure that has its absorber grown above the barrier. Like the shallow etch process on conventional nBn structures, the inverted nBn devices were fabricated with a processing scheme that only etches the top layer (the absorber, in this case) but avoids etching through the barrier. The results show that inverted nBn devices have the advantage of eliminating the lateral diffusion current without introducing elevated surface current.

Recent advances in preparation, properties and device applications of two-dimensional h-BN and its vertical heterostructures

NASA Astrophysics Data System (ADS)

Yang, Huihui; Gao, Feng; Dai, Mingjin; Jia, Dechang; Zhou, Yu; Hu, Pingan

2017-03-01

Two-dimensional (2D) layered materials, such as graphene, hexagonal boron nitride (h-BN), molybdenum disulfide (MoS{}2 ), have attracted tremendous interest due to their atom-thickness structures and excellent physical properties. h-BN has predominant advantages as the dielectric substrate in FET devices due to its outstanding properties such as chemically inert surface, being free of dangling bonds and surface charge traps, especially the large-band-gap insulativity. h-BN involved vertical heterostructures have been widely exploited during the past few years. Such heterostructures adopting h-BN as dielectric layers exhibit enhanced electronic performance, and provide further possibilities for device engineering. Besides, a series of intriguing physical phenomena are observed in certain vertical heterostructures, such as superlattice potential induced replication of Dirac points, band gap tuning, Hofstadter butterfly states, gate-dependent pseudospin mixing. Herein we focus on the rapid developments of h-BN synthesis and fabrication of vertical heterostructures devices based on h-BN, and review the novel properties as well as the potential applications of the heterostructures composed of h-BN. Project supported by the National Natural Science Foundation of China (Nos. 61390502, 21373068), the National Basic Research Program of China (No. 2013CB632900), the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (No. 51521003), and the Self-Planned Task of State Key Laboratory of Robotics and System (No. SKLRS201607B).

Thermal Conductivity Enhancement by Optical Phonon Sub-Band Engineering of Nanostructures Based on C and BN

DTIC Science & Technology

2005-09-01

Thermal Conductivity Enhancement by Optical Phonon Sub-Band Engineering of Nanostructures Based on C and BN DARPA CONTRACT MDA972-02-C-0044...AND SUBTITLE Thermal Conductivity Enhancement by Optical Phonon Sub-Band Engineering of Nanostructures Based on C and BN 5a. CONTRACT NUMBER 5b...Conductivity. Enhancement by Optical Phonon Sub-Bands Engineering in 3-D Nanostructures Based on C and BN Nanotubes" 1.3.1a. Phonon dynamics

Antimicrobial (BN/PE) film combined with modified atmosphere packaging extends the shelf life of minimally processed fresh-cut iceberg lettuce.

PubMed

Kang, Sun-Chul; Kim, Min-Jeong; Park, In-Sik; Choi, Ung-Kyu

2008-03-01

This study was conducted to investigate the effect of modified atmosphere packaging (MAP) in combination with BN/PE film on the shelf life and quality of fresh-cut iceberg lettuce during cold storage. The total mesophilic population in the sample packed in BN/PE film under MAP conditions was dramatically reduced in comparison with that of PE film, PE film under MAP conditions, and BN/PE film. The O2 concentration in the BN/PE film under MAP conditions decreased slightly as the storage period progressed. The coloration of the iceberg lettuce progressed the slowest when it was packaged in BN/PE film under MAP conditions, followed by BN/PE film, PE film, and PE film under MAP conditions. The shelf life of fresh-cut iceberg lettuce packaged in the BN/PE film under MAP conditions was extended by more than 2 days at 10 degrees as compared with that of the BN/PE film in which the extension effect was more than 2 days longer than that of PE, PET, and OPP films.

Substitutional carbon doping of free-standing and Ru-supported BN sheets: a first-principles study

NASA Astrophysics Data System (ADS)

Berseneva, N.; Komsa, H.-P.; Vierimaa, V.; Björkman, T.; Fan, Z.; Harju, A.; Todorović, M.; Krasheninnikov, A. V.; Nieminen, R. M.

2017-10-01

The development of spatially homogeneous mixed structures with boron (B), nitrogen (N) and carbon (C) atoms arranged in a honeycomb lattice is highly desirable, as they open the possibility of creating stable two-dimensional materials with tunable band gaps. However, at least in the free-standing form, the mixed BCN system is energetically driven towards phase segregation to graphene and hexagonal BN. It is possible to overcome the segregation when BCN material is grown on a particular metal substrate, for example Ru(0 0 0 1), but the stabilization mechanism is still unknown. With the use of density-functional theory we study the energetics of BN/Ru slabs, with different types of configurations of C substitutional defects introduced to the h-BN overlayer. The results are compared to the energetics of free-standing BCN materials. We found that the substrate facilitates the C substitution process in the h-BN overlayer. Thus, more homogeneous BCN material can be grown, overcoming the segregation into graphene and h-BN. In addition, we investigate the electronic and transport gaps in free-standing BCN structures, and assess their mechanical properties and stability. The band gap in mixed BCN free-standing material depends on the concentration of the constituent elements and ranges from zero in pristine graphene to nearly 5 eV in free-standing h-BN. This makes BCN attractive for application in modern electronics.

Exfoliated BN shell-based high-frequency magnetic core-shell materials.

PubMed

Zhang, Wei; Patel, Ketan; Ren, Shenqiang

2017-09-14

The miniaturization of electric machines demands high frequency magnetic materials with large magnetic-flux density and low energy loss to achieve a decreased dimension of high rotational speed motors. Herein, we report a solution-processed high frequency magnetic composite (containing a nanometal FeCo core and a boron nitride (BN) shell) that simultaneously exhibits high electrical resistivity and magnetic permeability. The frequency dependent complex initial permeability and the mechanical robustness of nanocomposites are intensely dependent on the content of BN insulating phase. The results shown here suggest that insulating magnetic nanocomposites have potential for application in next-generation high-frequency electric machines with large electrical resistivity and permeability.

Stability, elastic and electronic properties of a novel BN2 sheet with extended hexagons with N-N bonds

NASA Astrophysics Data System (ADS)

Waters, Kevin; Pandey, Ravindra

2018-04-01

A new B-N monolayer material (BN2) consisting of a network of extended hexagons is predicted using density functional theory. The distinguishable nature of this 2D material is found to be the presence of the bonded N atoms (N-N) in the lattice. Analysis of the phonon dispersion curves show this phase of BN2 to be stable. The calculated elastic properties exhibit anisotropic mechanical properties that surpass graphene in the armchair direction. The BN2 monolayer is metallic with in-plane p states dominating the Fermi level. Novel applications resulting from a strong anisotropic mechanical strength together with the metallic properties of the BN2 sheet with the extended hexagons with N-N bonds may enable future innovation at the nanoscale.

In low transpiring conditions, uncoupling the BnNrt2.1 and BnNrt1.1 NO3- transporters by glutamate treatment reveals the essential role of BnNRT2.1 for nitrate uptake and the nitrate-signaling cascade during growth

PubMed Central

Leblanc, Antonin; Segura, Raphaël; Deleu, Carole; Le Deunff, Erwan

2013-01-01

In plants, the nitrate transporters, NRT1.1 and NRT2.1, are mainly responsible for nitrate uptake. Intriguingly, both nitrate transporters are located in a complementary manner in different cells layers of the mature root suggesting that their coordination should occur during nitrate uptake and plant growth. This hypothesis was examined on 5-d-old rape seedlings grown on agar medium supplemented with 1 or 5mM nitrate. Seedlings were treated with increasing potassium glutamate concentrations in order to uncouple the two nitrate transporters by inhibiting BnNRT2.1 expression and activity specifically. In both nitrate treatments, increasing the glutamate concentrations from 0.5 to 10mM induced a reduction in 15NO3- uptake and an inhibition of N assimilation. The decrease in 15NO3- uptake was caused by downregulation of BnNRT2.1 expression but surprisingly it was not compensated by the upregulation of BnNRT1.1. This created an unprecedented physiological situation where the effects of the nitrate signal on shoot growth were solely modulated by nitrate absorption. In these conditions, the osmotic water flow for volumetric shoot growth was mainly dependent on active nitrate transport and nitrate signaling. This behavior was confirmed by the allometric relationships found between changes in the root length with 15N and water accumulation in the shoot. These findings demonstrate that the BnNRT2.1 transporter is essential for nitrate uptake and growth, and renew the question of the respective roles of the NRT2.1 and NRT1.1 transporters in nitrate uptake and sensing at the whole plant level. PMID:23299418

nBn Infrared Detector Containing Graded Absorption Layer

NASA Technical Reports Server (NTRS)

Gunapala, Sarath D.; Ting, David Z.; Hill, Cory J.; Bandara, Sumith V.

2009-01-01

It has been proposed to modify the basic structure of an nBn infrared photodetector so that a plain electron-donor- type (n-type) semiconductor contact layer would be replaced by a graded n-type III V alloy semiconductor layer (i.e., ternary or quarternary) with appropriate doping gradient. The abbreviation nBn refers to one aspect of the unmodified basic device structure: There is an electron-barrier ("B" ) layer between two n-type ("n" ) layers, as shown in the upper part of the figure. One of the n-type layers is the aforementioned photon-absorption layer; the other n-type layer, denoted the contact layer, collects the photocurrent. The basic unmodified device structure utilizes minority-charge-carrier conduction, such that, for reasons too complex to explain within the space available for this article, the dark current at a given temperature can be orders of magnitude lower (and, consequently, signal-to-noise ratios can be greater) than in infrared detectors of other types. Thus, to obtain a given level of performance, less cooling (and, consequently, less cooling equipment and less cooling power) is needed. [In principle, one could obtain the same advantages by means of a structure that would be called pBp because it would include a barrier layer between two electron-acceptor- type (p-type) layers.] The proposed modifications could make it practical to utilize nBn photodetectors in conjunction with readily available, compact thermoelectric coolers in diverse infrared- imaging applications that could include planetary exploration, industrial quality control, monitoring pollution, firefighting, law enforcement, and medical diagnosis.

Effects of hydrostatic pressure and biaxial strains on the elastic and electronic properties of t-C8B2N2

NASA Astrophysics Data System (ADS)

Zhu, Haiyan; Shi, Liwei; Li, Shuaiqi; Duan, Yifeng; Zhang, Shaobo; Xia, Wangsuo

2018-04-01

The effects of hydrostatic pressure and biaxial strains on the elastic and electronic properties of a superhard material t-C8B2N2 have been studied using first-principles calculations. The structure is proven to be mechanically and dynamically stable under the applied external forces. All the elastic constants (except C66) and elastic modulus increase (decrease) with increasing pressure and compressive (tensile) biaxial strain ɛxx. A microscopic model is used to calculate the Vicker's hardness of every single bond as well as the crystal. The hardness of t-C8B2N2 (64.7 GPa) exceeds that of c-BN (62 GPa) and increases obviously by employing pressure and compressive ɛxx. Furthermore, the Debye temperature and anisotropy of sound velocities for t-C8B2N2 have been discussed. t-C8B2N2 undergoes an indirect to direct bandgap transition when ɛxx > 2%; however, the indirect bandgap character of the material remains under pressure.

Engineering few-layer MoTe2 devices by Co/hBN tunnel contacts

NASA Astrophysics Data System (ADS)

Zhu, Mengjian; Luo, Wei; Wu, Nannan; Zhang, Xue-ao; Qin, Shiqiao

2018-04-01

2H phase Molybdenum ditelluride (MoTe2) is a layered two-dimensional (2D) semiconductor that has recently gained extensive attention for its intriguing properties, demonstrating great potential for nanoelectronics and optoelectronics. Optimizing the electric contacts to MoTe2 is a critical step for realizing high performance devices. Here, we demonstrate Co/hBN tunnel contacts to few-layer MoTe2. In sharp contrast to the p-type conduction of Co contacted MoTe2, Co/hBN tunnel contacted MoTe2 devices show clear n-type transport properties. Our first principles calculation reveals that the inserted few-layer hBN strongly interacts with Co and significantly reduces its work-function by ˜1.2 eV, while MoTe2 itself has a much weaker influence on the work-function of Co. This allows us to build MoTe2 diodes using the mixed Co/hBN and Co contact architecture, which can be switched from p-n type to n-p type by changing the gate-voltage, paving the way for engineering multi-functional devices based on atomically thin 2D semiconductors.

Thermal Conductivity Enhancement by Optical Phonon Sub-Band Engineering of Nanostructures Based on C and BN

DTIC Science & Technology

2002-01-01

Thermal Conductivity Enhancement by Optical Phono n Sub-Band Engineering of Nanostructures Based on C and BN DARPA CONTRACT MDA972-02-C-0044... Engineering in 3-D Nanostructures Based on C an d BN Nanotubes " 1.3.1a. Phonon dynamics and thermal properties of zigzag carbon nanotubes Content I...Conductivity. Enhancement by Optical Phonon Sub-Bands Engineering in 3-D Nanostructure s Based on C and BN Nanotubes " . Here, the dynamics of the heat

Gender-specific interactions of MTHFR C677T and MTRR A66G polymorphisms with overweight/obesity on serum lipid levels in a Chinese Han population.

PubMed

Zhi, Xueyuan; Yang, Boyi; Fan, Shujun; Wang, Yanxun; Wei, Jian; Zheng, Quanmei; Sun, Guifan

2016-10-28

Little is known regarding the interactions of methylenetetrahydrofolate reductase (MTHFR) C677T and methionine synthase reductase (MTRR) A66G polymorphisms with overweight/obesity on serum lipid profiles. The aim of the current study was to explore interactions between the two polymorphisms and overweight/obesity on four common lipid levels in a Chinese Han population and further to evaluate whether these interactions exhibit gender-specificity. A total of 2239 participants (750 females and 1489 males) were enrolled into this study. The genotypes of the MTHFR C677T and MTRR A66G were determined by a TaqMan assay. Overweight and obesity were defined as a body mass index between 24 and 27.99 and ≥ 28 kg/m 2 , respectively. The interactions were examined by factorial design covariance analysis, and further multiple comparisons were conducted by Bonferroni correction. There was no significant difference in the genotypic and allelic frequencies between females and males (MTHFR 677 T allele: 54.47 % for females and 54.40 % for males; MTRR 66G allele: 24.73 % for females and 24.71 % for males). Interaction between the MTHFR C677T polymorphism and overweight/obesity on serum triglyceride levels, and interaction between the MTRR A66G polymorphism and overweight/obesity on serum high-density lipoprotein cholesterol levels were detected in women (P = 0.015 and P = 0.056, respectively). For female subjects with overweight/obesity, the serum triglyceride levels in MTHFR 677TT genotype [1.09 (0.78-1.50) mmol/L] were significantly higher as compared with MTHFR 677CC genotype [0.90 (0.60-1.15) mmol/L, P = 0.007], and the MTRR 66GG genotype carriers had higher serum high-density lipoprotein cholesterol levels than those with MTRR 66AG genotype (1.46 ± 0.50 vs. 1.19 ± 0.31 mmol/L, P = 0.058). Furthermore, in male subjects with overweight/obesity, the MTHFR 677CT genotype carriers had higher low-density lipoprotein cholesterol levels than those

Variation at Extra-epitopic Amino Acid Residues Influences Suppression of Influenza Virus Replication by M158-66 Epitope-Specific CD8+ T Lymphocytes.

PubMed

van de Sandt, Carolien E; Pronk, Mark R; van Baalen, Carel A; Fouchier, Ron A M; Rimmelzwaan, Guus F

2018-06-01

Influenza virus-specific CD8 + T lymphocytes (CTLs) contribute to clearance of influenza virus infections and reduce disease severity. Variation at amino acid residues located in or outside CTL epitopes has been shown to affect viral recognition by virus-specific CTLs. In the present study, we investigated the effect of naturally occurring variation at residues outside the conserved immunodominant and HLA*0201-restricted M1 58-66 epitope, located in the influenza virus M1 protein, on the extent of virus replication in the presence of CTLs specific for the epitope. To this end, we used isogenic viruses with an M1 gene segment derived from either an avian or a human influenza virus, HLA-transgenic human epithelial cells, human T cell clones specific for the M1 58-66 epitope or a control epitope, and a novel, purposely developed in vitro system to coculture influenza virus-infected cells with T cells. We found that the M gene segment of a human influenza A/H3N2 virus afforded the virus the capacity to replicate better in the presence of M1 58-66 -specific CTLs than the M gene segment of avian viruses. These findings are in concordance with previously observed differential CTL activation, caused by variation at extra-epitopic residues, and may reflect an immune adaptation strategy of human influenza viruses that allows them to cope with potent CTL immunity to the M1 58-66 epitope in HLA-A*0201-positive individuals, resulting in increased virus replication and shedding and possibly increasing disease severity. IMPORTANCE Influenza viruses are among the leading causes of acute respiratory tract infections. CD8 + T lymphocytes display a high degree of cross-reactivity with influenza A viruses of various subtypes and are considered an important correlate of protection. Unraveling viral immune evasion strategies and identifying signs of immune adaptation are important for defining the role of CD8 + T lymphocytes in affording protection more accurately. Improving our insight

Bombesin receptors and transplanted stem cells in rat brain: High-resolution scan with 99mTc BN1.1

NASA Astrophysics Data System (ADS)

Scopinaro, F.; Paschali, E.; Di Santo, G.; Antonellis, T.; Massari, R.; Trotta, C.; Gourni, H.; Bouziotis, P.; David, V.; Soluri, A.; Varvarigou, A. D.

2006-12-01

The aim of this work is to detect the presence of transplanted stem cells (TSC) in rat brain with high-resolution (HR) scintigraphy and labelled bombesin (BN). BN is a morphogen for Central Nervous System (CNS) as well as for other organs: CNS-oriented TSC over-express BN Receptors (BNR). BN is also a neurotransmitter and modulates several functions of CNS. 99mTc labelled BN-like peptide scan of CNS is the ideal method to detect growing TSC once knowing normal distribution of BNRs in CNS. HR Planar and single photon emission computerized tomography (SPECT) images of rat brain were performed with new HR detectors (Li-tech, Italy). Pertechnetate, 99mTc HMPAO and the new 99mTc BN1.1 (patented) were i.v. administered in five rats. HR SPECT of 99mTc BN1.1 detected olfactory tract, fronto-lateral cortex, cerebellum, basal ganglia and amygdale. Results of SPECT were confirmed by bio-distribution study performed after autopsy of three of the five rats. The remaining two rats underwent cerebral lesions followed by transplant of TSC. Three months later, HR scintigraphy was repeated and showed images completely different from previous basal study, with hot spot of 99mTc BN1.1 corresponding to the site of TSC transplant. Immuno-histochemistry confirmed the presence of viable TSC. Not only 99mTc BN1.1 HR scan showed viability of transplanted TSC but also the "background brain" was the still now unknown map of BNR in mammalian brain.

Bandgap oscillation in quasiperiodic (BN)xCy nanotubes

NASA Astrophysics Data System (ADS)

Freitas, A.; Bezerra, C. G.; Azevedo, S.; Machado, L. D.; Pedreira, D. O.

2016-12-01

In the present contribution, we apply first-principles calculations to study the effects of quasiperiodic disorder on the physical properties of BN and C nanotubes. We take BN nanotubes (BNNTs) and C nanotubes (CNTs) as building blocks and construct quasiperiodic BNxCy nanotubes according to the Fibonacci sequence. We studied armchair and zigzag nanotubes of varying diameters. Our results demonstrate that the energy gap oscillates as a function of the n-generation index of the Fibonacci sequence. Moreover, we show that the choice of the BNNTs and CNTs may lead to a quasiperiodic BNxCy nanotube presenting an adjustable energy gap. We obtained a variety of quasiperiodic nanotubes with energy gaps ranging from 0.29 eV to 1.06 eV, which may be of interest for specific technological applications. Finally, it is also demonstrated that the specific heat of the quasiperiodic zigzag and armchair nanotubes presents an oscillatory behavior in the low temperature regime, and that this behavior depends on the curvature of the nanotube.

Thick c-BN films deposited by radio frequency magnetron sputtering in argon/nitrogen gas mixture with additional hydrogen gas

NASA Astrophysics Data System (ADS)

Zhao, Yan; Gao, Wei; Xu, Bo; Li, Ying-Ai; Li, Hong-Dong; Gu, Guang-Rui; Yin, Hong

2016-10-01

The excellent physical and chemical properties of cubic boron nitride (c-BN) film make it a promising candidate for various industry applications. However, the c-BN film thickness restricts its practical applications in many cases. Thus, it is indispensable to develop an economic, simple and environment-friend way to synthesize high-quality thick, stable c-BN films. High-cubic-content BN films are prepared on silicon (100) substrates by radio frequency (RF) magnetron sputtering from an h-BN target at low substrate temperature. Adhesions of the c-BN films are greatly improved by adding hydrogen to the argon/nitrogen gas mixture, allowing the deposition of a film up to 5-μm thick. The compositions and the microstructure morphologies of the c-BN films grown at different substrate temperatures are systematically investigated with respect to the ratio of H2 gas content to total working gas. In addition, a primary mechanism for the deposition of thick c-BN film is proposed. Project supported by the National Natural Science Foundation of China (Grant Nos. 51572105, 61504046, and 51272224), the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, China, the Development and Reform Commission of Jilin Province, China (Grant No. 2015Y050), and the Scientific Research Foundation for the Returned Overseas of Jilin Province, China.

Effects of epitaxial structure and processing on electrical characteristics of InAs-based nBn infrared detectors

NASA Astrophysics Data System (ADS)

Du, X.; Savich, G. R.; Marozas, B. T.; Wicks, G. W.

2017-02-01

The conventional processing of the III-V nBn photodetectors defines mesa devices by etching the contact n-layer and stopping immediately above the barrier, i.e., a shallow etch. This processing enables great suppression of surface leakage currents without having to explore surface passivation techniques. However, devices that are made with this processing scheme are subject to lateral diffusion currents. To address the lateral diffusion current, we compare the effects of different processing approaches and epitaxial structures of nBn detectors. The conventional solution for eliminating lateral diffusion current, a deep etch through the barrier and the absorber, creates increased dark currents and an increased device failure rate. To avoid deep etch processing, a new device structure is proposed, the inverted-nBn structure. By comparing with the conventional nBn structure, the results show that the lateral diffusion current is effectively eliminated in the inverted-nBn structure without elevating the dark currents.

Magnetization distribution and spin transport of graphene/h-BN/graphene nanoribbon-based magnetic tunnel junction

NASA Astrophysics Data System (ADS)

Zhang, Y.; Yan, X. H.; Guo, Y. D.; Xiao, Y.

2017-09-01

Motivated by recent electronic transport measurement of boron nitride-graphene hybrid atomic layers, we studied magnetization distribution, transmission and current-bias relation of graphene/h-BN/graphene (C/BN/C) nanoribbon-based magnetic tunnel junctions (MTJ) based on density functional theory and non-equilibrium Green's function methods. Three types of MTJs, i.e. asymmetric, symmetric (S) and symmetric (SS), and two types of lead magnetization alignment, i.e. parallel (PC) and antiparallel (APC), are considered. The results show that the magnetization distribution is closely related to the interface structure. Especially for asymmetric MTJ, the B/N atoms at the C/BN interface are spin-polarized and give finite magnetic moments. More interesting, it is found that the APC transmission of asymmetric MTJ with the thinnest barrier dominates over the PC one. By analyzing the projected density of states, one finds that the unusual higher APC transmission than PC is due to the coupling of electronic states of left ZGNR and right ZGNR. By integrating transmission, we calculate the current-bias voltage relation and find that the APC current is larger than PC current at small bias voltage and therefore reproduces a negative tunnel magnetoresistance. The results reported here will be useful and important for the design of C/BN/C-based MTJ.

Germany unveils €18bn research plan

NASA Astrophysics Data System (ADS)

Banks, Michael

2009-07-01

The German government has unveiled an ambitious plan to inject a total of €18bn into teaching and research over the next decade. The German chancellor Angela Merkel, who has a degree in physics, announced that she was releasing the funds despite concerns from her social-democrat coalition partners that financing the package could be difficult in the economic downturn.

Optical control of inter-layer distance of hBN: a TDDFT study

NASA Astrophysics Data System (ADS)

Miyamoto, Yoshiyuki; Zhang, Hong; Miyazaki, Takehide; Rubio, Angel

In this presentation, we introduce an idea to modify inter-layer distance of hBN by shining IR laser in resonance with the frequency of the optical phonon (A2u mode). By performing the TDDFT-MD simulation under the IR laser, significant grow in an amplitude of the A2u phonon mode was observed and inter-layer contraction over 11 % of the original distance was achieved. The source of the stronger attraction of hBN sheets was attributed with increase of dipole moment of each layer coming from the motions of boron (B) and nitrogen (N) atoms in opposite directions. Since the dipole moments of these layers remain as parallel throughout the A2u phonon vibration, the increase of attractive force occurs between the two hBN sheets in analogy of the London force. In this talk, we will further discuss proper intensity of IR laser and potential applications of this phenomenon. This work was published in.

33 CFR 66.10-5-66.10-10 - [Reserved

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false [Reserved] 66.10-5-66.10-10 Section 66.10-5-66.10-10 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Uniform State Waterway Marking System §§ 66.10-5—66.10-10...

33 CFR 66.10-5-66.10-10 - [Reserved

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false [Reserved] 66.10-5-66.10-10 Section 66.10-5-66.10-10 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Uniform State Waterway Marking System §§ 66.10-5—66.10-10...

Isolation, purification and functional characterization of alpha-BnIA from Conus bandanus venom.

PubMed

Nguyen, Bao; Le Caer, Jean-Pierre; Aráoz, Romulo; Thai, Robert; Lamthanh, Hung; Benoit, Evelyne; Molgó, Jordi

2014-12-01

We report the isolation and characterization by proteomic approach of a native conopeptide, named BnIA, from the crude venom of Conus bandanus, a molluscivorous cone snail species, collected in the South central coast of Vietnam. Its primary sequence was determined by matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry using collision-induced dissociation and confirmed by Edman's degradation of the pure native fraction. BnIA was present in high amounts in the crude venom and the complete sequence of the 16 amino acid peptide was the following GCCSHPACSVNNPDIC*, with C-terminal amidation deduced from Edman's degradation and theoretical monoisotopic mass calculation. Sequence alignment revealed that its -C1C2X4C3X7C4- pattern belongs to the A-superfamily of conopeptides. The cysteine connectivity of BnIA was 1-3/2-4 as determined by partial-reduction technique, like other α4/7-conotoxins, reported previously on other Conus species. Additionally, we found that native α-BnIA shared the same sequence alignment as Mr1.1, from the closely related molluscivorous Conus marmoreus venom, in specimens collected in the same coastal region of Vietnam. Functional studies revealed that native α-BnIA inhibited acetylcholine-evoked currents reversibly in oocytes expressing the human α7 nicotinic acetylcholine receptors, and blocked nerve-evoked skeletal muscle contractions in isolated mouse neuromuscular preparations, but with ∼200-times less potency. Copyright © 2014 Elsevier Ltd. All rights reserved.

PREFACE: Ultrathin layers of graphene, h-BN and other honeycomb structures Ultrathin layers of graphene, h-BN and other honeycomb structures

NASA Astrophysics Data System (ADS)

Geber, Thomas; Oshima, Chuhei

2012-08-01

Since ancient times, pure carbon materials have been familiar in human society—not only diamonds in jewellery and graphite in pencils, but also charcoal and coal which have been used for centuries as fuel for living and industry. Carbon fibers are stronger, tougher and lighter than steel and increase material efficiency because of their lower weight. Today, carbon fibers and related composite materials are used to make the frames of bicycles, cars and even airplane parts. The two-dimensional allotrope, now called graphene, is just a single layer of carbon atoms, locked together in a strongly bonded honeycomb lattice. In plane, graphene is stiffer than diamond, but out-of-plane it is soft, like rubber. It is virtually invisible, may conduct electricity (heat) better than copper and weighs next to nothing. Carbon compounds with two carbon atoms as a base, such as graphene, graphite or diamond, have isoelectronic sister compounds made of boron-nitrogen pairs: hexagonal and cubic boron nitride, with almost the same lattice constant. Although the two 2D sisters, graphene and h-BN, have the same number of valence electrons, their electronic properties are very different: freestanding h-BN is an insulator, while charge carriers in graphene are highly mobile. The past ten years have seen a great expansion in studies of single-layer and few-layer graphene. This activity has been concerned with the π electron transport in graphene, in electric and magnetic fields. More than 30 years ago, however, single-layer graphene and h-BN on solid surfaces were widely investigated. It was noted that they drastically changed the chemical reactivity of surfaces, and they were known to 'poison' heterogeneous catalysts, to passivate surfaces, to prevent oxidation of surfaces and to act as surfactants. Also, it was realized that the controlled growth of h-BN and graphene on substrates yields the formation of mismatch driven superstructures with peculiar template functionality on the

Synthesis and Comparison of Two cBN Composites with Starting Ternary Carbide Binders

NASA Astrophysics Data System (ADS)

Yue, Zhenming; Yang, Limin; Gong, Jianhong; Gao, Jun

2018-04-01

Ti3SiC2 and Ti3AlC2 are two promising binders for the ultrahard composite polycrystalline cubic boron nitride (PcBN). In this study, the cBN composites with Ti3SiC2 and Ti3AlC2 binders with different binder contents were synthesized under the same high pressure ( 5.5 GPa) and high temperature (1350 °C) conditions. Their mechanical properties were measured separately, including Vickers hardness, bending hardening, and compression hardening. Together with XRD results, the phase compounds were also investigated. The decomposition and reaction processes were affected by binder content. Some new compounds formed during sintering, these compounds were TiC, TiSi2, SiC, TiB2, SiB4, TiB2, and TiC0.7N0.3 in Ti3SiC2-cBN composites, as well as TiC0.7N0.3, TiB2, and AlN in Ti3AlC2-cBN composites. The microstructure of the cracks surface was obtained after the bending tests, and was used to further investigate and compare their crack mode by SEM. The crack surface profile and elementary analysis on the oxidative surface were also discussed.

Synthesis and Comparison of Two cBN Composites with Starting Ternary Carbide Binders

NASA Astrophysics Data System (ADS)

Yue, Zhenming; Yang, Limin; Gong, Jianhong; Gao, Jun

2018-05-01

Ti3SiC2 and Ti3AlC2 are two promising binders for the ultrahard composite polycrystalline cubic boron nitride (PcBN). In this study, the cBN composites with Ti3SiC2 and Ti3AlC2 binders with different binder contents were synthesized under the same high pressure ( 5.5 GPa) and high temperature (1350 °C) conditions. Their mechanical properties were measured separately, including Vickers hardness, bending hardening, and compression hardening. Together with XRD results, the phase compounds were also investigated. The decomposition and reaction processes were affected by binder content. Some new compounds formed during sintering, these compounds were TiC, TiSi2, SiC, TiB2, SiB4, TiB2, and TiC0.7N0.3 in Ti3SiC2-cBN composites, as well as TiC0.7N0.3, TiB2, and AlN in Ti3AlC2-cBN composites. The microstructure of the cracks surface was obtained after the bending tests, and was used to further investigate and compare their crack mode by SEM. The crack surface profile and elementary analysis on the oxidative surface were also discussed.

Growth kinetics of white graphene (h-BN) on a planarised Ni foil surface

PubMed Central

Cho, Hyunjin; Park, Sungchan; Won, Dong-Il; Kang, Sang Ook; Pyo, Seong-Soo; Kim, Dong-Ik; Kim, Soo Min; Kim, Hwan Chul; Kim, Myung Jong

2015-01-01

The morphology of the surface and the grain orientation of metal catalysts have been considered to be two important factors for the growth of white graphene (h-BN) by chemical vapour deposition (CVD). We report a correlation between the growth rate of h-BN and the orientation of the nickel grains. The surface of the nickel (Ni) foil was first polished by electrochemical polishing (ECP) and subsequently annealed in hydrogen at atmospheric pressure to suppress the effect of the surface morphology. Atmospheric annealing with hydrogen reduced the nucleation sites of h-BN, which induced a large crystal size mainly grown from the grain boundary with few other nucleation sites in the Ni foil. A higher growth rate was observed from the Ni grains that had the {110} or {100} orientation due to their higher surface energy. PMID:26156068

In Vitro and In Vivo Evaluations of Nano-Hydroxyapatite/Polyamide 66/Glass Fibre (n-HA/PA66/GF) as a Novel Bioactive Bone Screw

PubMed Central

Su, Bao; Peng, Xiaohua; Jiang, Dianming; Wu, Jun; Qiao, Bo; Li, Weichao; Qi, Xiaotong

2013-01-01

In this study, we prepared nano-hydroxyapatite/polyamide 66/glass fibre (n-HA/PA66/GF) bioactive bone screws. The microstructure, morphology and coating of the screws were characterised, and the adhesion, proliferation and viability of MC3T3-E1 cells on n-HA/PA66/GF scaffolds were determined using scanning electron microscope, CCK-8 assays and cellular immunofluorescence analysis. The results confirmed that n-HA/PA66/GF scaffolds were biocompatible and had no negative effect on MC3T3-E1 cells in vitro. To investigate the in vivo biocompatibility, internal fixation properties and osteogenesis of the bioactive screws, both n-HA/PA66/GF screws and metallic screws were used to repair intercondylar femur fractures in dogs. General photography, CT examination, micro-CT examination, histological staining and biomechanical assays were performed at 4, 8, 12 and 24 weeks after operation. The n-HA/PA66/GF screws exhibited good biocompatibility, high mechanical strength and extensive osteogenesis in the host bone. Moreover, 24 weeks after implantation, the maximum push-out load of the bioactive screws was greater than that of the metallic screws. As shown by their good cytocompatibility, excellent biomechanical strength and fast formation and ingrowth of new bone, n-HA/PA66/GF screws are thus suitable for orthopaedic clinical applications. PMID:23861888

Radioactive waste from decommissioning of fast reactors (through the example of BN-800)

NASA Astrophysics Data System (ADS)

Rybin, A. A.; Momot, O. A.

2017-01-01

Estimation of volume of radioactive waste from operating and decommissioning of fast reactors is introduced. Preliminary estimation has shown that the volume of RW from decommissioning of BN-800 is amounted to 63,000 cu. m. Comparison of the amount of liquid radioactive waste derived from operation of different reactor types is performed. Approximate costs of all wastes disposal for complete decommissioning of BN-800 reactor are estimated amounting up to approx. 145 million.

The Structure and Stability of Bn(+) Clusters

NASA Technical Reports Server (NTRS)

Ricca, Alessandra; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R. (Technical Monitor)

1995-01-01

The geometries of B+n clusters for n less than 14 have been optimized using density functional theory with the B3LYP functional. The most stable structure for each cluster is planar or quasi-planar. The B3LYP fragmentation energies are calibrated using coupled cluster theory. Overall, our corrected fragmentation energies are in reasonable agreement with experiment. Our results are compared with previous theoretical results.

First principles-based moiré model for incommensurate graphene on BN

NASA Astrophysics Data System (ADS)

Spataru, Catalin; Thurmer, Konrad

Various properties of supported graphene films depend strongly on the exact positions of carbon atoms with respect to the underlying substrate. While density functional theory (DFT) can predict atom position in many systems, it cannot be applied straightforwardly to systems that are incommensurate or have large unit cells, such as graphene on a BN surface. We address these limitations by developing a simple moiré model with parameters derived from DFT calculations for systems strained into commensurate structures with manageable unit cell sizes. Our moiré model, which takes into account the flexural rigidity of graphene and includes the influence of the substrate, is able to reproduce the DFT-relaxed carbon positions with an accuracy of <0.01 Å. We then apply this model to the unstrained C/BN system and predict how structure and energy vary with azimuthal orientation of the graphene sheet with respect to the BN substrate. Work supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Co., for the U.S. DOE under Contract DE-AC04-94AL85000.

Electronic structure and STM images simulation of defects on hBN/ black-phosphorene heterostructures: A theoretical study

NASA Astrophysics Data System (ADS)

Ospina, D. A.; Cisternas, E.; Duque, C. A.; Correa, J. D.

2018-03-01

By first principles calculations which include van der Waals interactions, we studied the electronic structure of hexagonal boron-nitride/black-phosphorene heterostructures (hBN/BP). In particular the role of several kind of defects on the electronic properties of black-phosphorene monolayer and hBN/BP heterostructure was analyzed. The defects under consideration were single and double vacancies, as well Stone-Wale type defects, all of them present in the phosphorene layer. In this way, we found that the electronic structure of the hBN/BP is modified according the type of defect that is introduced. As a remarkable feature, our results show occupied states at the Fermi Level introduced by a single vacancy in the energy gap of the hBN/BP heterostructure. Additionally, we performed simulations of scanning tunneling microscopy images. These simulations show that is possible to discriminate the kind of defect even when the black-phosphorene monolayer is part of the heterostructure hBN/BP. Our results may help to discriminate among several kind of defects during experimental characterization of these novel materials.

Study of vibrational modes and specific heat of wurtzite phase of BN

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

Singh, Daljit, E-mail: daljit.jt@gmail.com; Sinha, M. M.

2016-05-06

In these days of nanotechnology the materials like BN is of utmost importance as in hexagonal phase it is among hardest materials. The phonon mode study of the materials is most important factor to find structural and thermodynamcal properties. To study the phonons de launey angular force (DAF) constant model is best suited as it involves many particle interactions. Therefore in this presentation we have studied the lattice dynamical properties and specific heat of BN in wurtzite phase using DAF model. The obtained results are in excellent agreement with existing results.

The electrical and thermal transport properties of hybrid zigzag graphene-BN nanoribbons

NASA Astrophysics Data System (ADS)

Gao, Song; Lu, Wei; Zheng, Guo-Hui; Jia, Yalei; Ke, San-Huang

2017-06-01

The electron and phonon transport in hybrid graphene-BN zigzag nanoribbons are investigated by the nonequilibrium Green’s function method combined with density functional theory calculations. A 100% spin-polarized electron transport in a large energy window around the Fermi level is found and this behavior is independent of the ribbon width as long as there contain 3 zigzag carbon chains. The phonon transport calculations show that the ratio of C-chain number to BN-chain number will modify the thermal conductance of the hybrid nanoribbon in a complicated manner.

Effect of different thickness h-BN coatings on interface shear strength of quartz fiber reinforced Sisbnd Osbnd Csbnd N composite

NASA Astrophysics Data System (ADS)

Wang, Shubin; Zheng, Yu

2014-02-01

Hexagonal boron nitride (h-BN) coatings with different thickness were prepared on quartz fibers to improve mechanical properties of quartz fiber reinforced Sisbnd Osbnd Csbnd N composite. Scanning electron microscopy (SEM), push-out test and single edge notched beam (SENB) in three point bending test were employed to study morphology, interface shear strength and fracture toughness of the composite. The results showed that h-BN coatings changed the crack growth direction and weaken the interface shear strength efficiently. When the h-BN coating was 308.2 nm, the interface shear strength was about 5.2 MPa, which was about one-quarter of that of the sample without h-BN coatings. After the heating process for obtaining composite, the h-BN nanometer-sized grains would grow up to micron-sized hexagonal grains. Different thickness h-BN coatings had different structure. When the coatings were relatively thin, the hexagonal grains were single layer structure, and when the coatings were thicker, the hexagonal grains were multiple layer structure. This multiple layer interface phase would consume more power of cracks, thus interface shear strength of the composite decreased steadily with the increasing of h-BN coatings thickness. When the coating thickness was 238.8 nm, KIC reaches the peak value 3.8 MPa m1/2, which was more than two times of that of composites without h-BN coatings.

BnDGAT1s Function Similarly in Oil Deposition and Are Expressed with Uniform Patterns in Tissues of Brassica napus

PubMed Central

Zhao, Cuizhu; Li, Huan; Zhang, Wenxue; Wang, Hailan; Xu, Aixia; Tian, Jianhua; Zou, Jitao; Taylor, David C.; Zhang, Meng

2017-01-01

As an allotetraploid oilcrop, Brassica napus contains four duplicated Acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) genes, which catalyze one of the rate-limiting steps in triacylglycerol (TAG) biosynthesis in plants. While all four BnDGAT1s have been expressed functionally in yeast, their expression patterns in different germplasms and tissues and also consequent contribution to seed oil accumulation in planta remain to be elucidated. In this study, the coding regions of the four BnDGAT1s were expressed in an Arabidopsis dgat1 mutant. All four BnDGAT1s showed similar effects on oil content and fatty acid composition, a result which is different from that observed in previous studies of their expression in yeast. Expression patterns of BnDGAT1s were analyzed in developing seeds of 34 B. napus inbred lines and in different tissues of 14 lines. Different expression patterns were observed for the four BnDGAT1s, which suggests that they express independently or randomly in different germplasm sources. Higher expression of BnDGAT1s was correlated with higher seed oil content lines. Tissue-specific analyses showed that the BnDGAT1s were expressed in a uniform pattern in different tissues. Our results suggest that it is important to maintain expression of the four BnDGAT1s for maximum return on oil content. PMID:29312429

BnDGAT1s Function Similarly in Oil Deposition and Are Expressed with Uniform Patterns in Tissues of Brassica napus.

PubMed

Zhao, Cuizhu; Li, Huan; Zhang, Wenxue; Wang, Hailan; Xu, Aixia; Tian, Jianhua; Zou, Jitao; Taylor, David C; Zhang, Meng

2017-01-01

As an allotetraploid oilcrop, Brassica napus contains four duplicated Acyl-CoA:diacylglycerol acyltransferase 1 ( DGAT1 ) genes, which catalyze one of the rate-limiting steps in triacylglycerol (TAG) biosynthesis in plants. While all four BnDGAT1 s have been expressed functionally in yeast, their expression patterns in different germplasms and tissues and also consequent contribution to seed oil accumulation in planta remain to be elucidated. In this study, the coding regions of the four BnDGAT1s were expressed in an Arabidopsis dgat1 mutant. All four BnDGAT1s showed similar effects on oil content and fatty acid composition, a result which is different from that observed in previous studies of their expression in yeast. Expression patterns of BnDGAT1s were analyzed in developing seeds of 34 B. napus inbred lines and in different tissues of 14 lines. Different expression patterns were observed for the four BnDGAT1 s, which suggests that they express independently or randomly in different germplasm sources. Higher expression of BnDGAT1s was correlated with higher seed oil content lines. Tissue-specific analyses showed that the BnDGAT1 s were expressed in a uniform pattern in different tissues. Our results suggest that it is important to maintain expression of the four BnDGAT1s for maximum return on oil content.

78 FR 28836 - Vulcan/BN Geothermal Power Company; Supplemental Notice That Initial Market-Based Rate Filing...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-16

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER13-1273-000] Vulcan/BN Geothermal Power Company; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for... Vulcan/BN Geothermal Power Company's application for market-based rate authority, with an accompanying...

/sup 3/H-PAF-acether displacement and inhibition of binding in intact human platelets by BN 52021

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

Korth, R.; Le Couedic, J.P.; Benveniste, J.

1986-03-05

Intact washed human platelets incubated at 20/sup 0/C in Tyrode's buffer containing 0.25% (w/v) bovine serum albumin bound /sup 3/H paf-acether in a concentration (0-6.5 nM) and time (0-60 min) dependent manner (n=3). BN 52021 (60 ..mu..M) a chemically defined extract from Ginkgo biloba inhibited the binding of increasing concentrations of /sup 3/H paf-acether. Calculated differences between /sup 3/H paf-acether binding in the presence or absence of BN 52021 (60 ..mu..M) reached nearly a plateau in concentrations higher than 0.65 nM /sup 3/H paf-acether. Increasing concentrations of BN 52021 (0-60 ..mu..M) as well as of unlabelled paf-acether (0-50 nM) preventedmore » within 15 min /sup 3/H paf-acether binding (0.65 nM) to platelets in a concentration-dependent way. Increasing BN 52021 concentrations (0-60 ..mu..M) also displaced platelet-bound /sup 3/H paf-acether (0.65 nM) in a concentration-dependent way. Displacement increased with the time length of platelet incubation with BN 52021 and reached a plateau at 15 min. Platelet-bound /sup 3/H paf-acether displacement of 28.3 +/- 6.3%, 31.1 +/- 4.0% and 26.7 +/- 5.6% was observed using 50 nM unlabelled paf-acether, 60 ..mu..M BN 52021 or both substances together (vs 4.3 +/- 7.2% for vehicle alone). No degradation of /sup 3/H paf-acether occurred as assessed by high pressure liquid chromatography. These results demonstrate that BN 52021 competes directly with paf-acether binding sites on human platelets.« less

Fabrication and properties of SiNO continuous fiber reinforced BN wave-transparent composites

NASA Astrophysics Data System (ADS)

Cao, F.; Fang, Z.; Chen, F.; Shen, Q.; Zhang, C.

2012-06-01

SiNO continuous fiber reinforced boron nitride (BN) wave-transparent composites (SiNO f /BN) have been fabricated by a precursor infiltration pyrolysis (PIP) method using borazine as the precursor. The densification behavior, microstructures, mechanical properties, and dielectric properties of the composites have been investigated. After four PIP cycles, the density of the composites had increased from 1.1 g·cm-3 to 1.81 g·cm-3. A flexural strength of 128.9 MPa and an elastic modulus of 23.5 GPa were achieved. The obtained composites have relatively high density and the fracture faces show distinct fiber pull-out and interface de-bonding features. The dielectric properties of the SiNO f /BN composites, including the dielectric constant of 3.61 and the dielectric loss angle tangent of 5.7×10-3, are excellent for application as wave-transparent materials.

BnEPFL6, an EPIDERMAL PATTERNING FACTOR-LIKE (EPFL) secreted peptide gene, is required for filament elongation in Brassica napus.

PubMed

Huang, Yi; Tao, Zhangsheng; Liu, Qiong; Wang, Xinfa; Yu, Jingyin; Liu, Guihua; Wang, Hanzhong

2014-07-01

Inflorescence architecture, pedicel length and stomata patterning in Arabidopsis thaliana are specified by inter-tissue communication mediated by ERECTA and its signaling ligands in the EPIDERMAL PATTERNING FACTOR-LIKE (EPFL) family of secreted cysteine-rich peptides. Here, we identified and characterized BnEPFL6 from Brassica napus. Heterologous expression of this gene under the double enhanced CaMV promoter (D35S) in Arabidopsis resulted in shortened stamen filaments, filaments degradation, and reduced filament cell size that displayed down-regulated expression of AHK2, in which phenotypic variation of ahk2-1 mutant presented highly consistent with that of BnEPFL6 transgenic lines. Especially, the expression level of BnEPFL6 in the shortened filaments of four B. napus male sterile lines (98A, 86A, SA, and Z11A) was similar to that of BnEPFL6 in the transgenic Arabidopsis lines. The activity of pBnEPFL6.2::GUS was intensive in the filaments of transgenic lines. These observations reveal that BnEPFL6 plays an important role in filament elongation and may also affect organ morphology and floral organ specification via a BnEPFL6-mediated cascade.

Bandgap renormalization and work function tuning in MoSe2/hBN/Ru(0001) heterostructures.

PubMed

Zhang, Qiang; Chen, Yuxuan; Zhang, Chendong; Pan, Chi-Ruei; Chou, Mei-Yin; Zeng, Changgan; Shih, Chih-Kang

2016-12-14

The van der Waals interaction in vertical heterostructures made of two-dimensional (2D) materials relaxes the requirement of lattice matching, therefore enabling great design flexibility to tailor novel 2D electronic systems. Here we report the successful growth of MoSe 2 on single-layer hexagonal boron nitride (hBN) on the Ru(0001) substrate using molecular beam epitaxy. Using scanning tunnelling microscopy and spectroscopy, we found that the quasi-particle bandgap of MoSe 2 on hBN/Ru is about 0.25 eV smaller than those on graphene or graphite substrates. We attribute this result to the strong interaction between hBN/Ru, which causes residual metallic screening from the substrate. In addition, the electronic structure and the work function of MoSe 2 are modulated electrostatically with an amplitude of ∼0.13 eV. Most interestingly, this electrostatic modulation is spatially in phase with the Moiré pattern of hBN on Ru(0001) whose surface also exhibits a work function modulation of the same amplitude.

Quality of Life in Patients With Brain Metastases Using the EORTC QLQ-BN20+2 and QLQ-C15-PAL

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

Caissie, Amanda; Nguyen, Janet; Chen, Emily

Purpose: The 20-item European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Brain Neoplasm (QLQ-BN20) is a validated quality-of-life (QOL) questionnaire for patients with primary brain tumors. The European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core 15 Palliative (QLQ-C15-PAL) core palliative questionnaire is a 15-item version of the core 30-item QLQ-C30 and was developed to decrease the burden on patients with advanced cancer. The combination of the QLQ-BN20 and QLQ-C30 to assess QOL may be too burdensome for patients. The primary aim of this study was to assess QOL in patients before and aftermore » treatment for brain metastases using the QLQ-BN20+2 and QLQ-C15-PAL, a version of the QLQ-BN20 questionnaire with 2 additional questions assessing cognitive functioning that were not addressed in the QLQ-C15-PAL. Methods and Materials: Patients with brain metastases completed the QLQ-C15-PAL and QLQ-BN20+2 questionnaires to assess QOL before and 1 month after radiation. Linear regression analysis was used to assess changes in QOL scores over time, as well as to explore associations between the QLQ-BN20+2 and QLQ-C15-PAL scales, patient demographics, and clinical variables. Spearman correlation assessed associations between the QLQ-BN20+2 and QLQ-C15-PAL scales. Results: Among 108 patients, the majority (55%) received whole-brain radiotherapy only, with 65% of patients completing follow-up at 1 month after treatment. The most prominent symptoms at baseline were future uncertainty (QLQ-BN20+2) and fatigue (QLQ-C15-PAL). After treatment, significant improvement was seen for the QLQ-C15-PAL insomnia scale, as well as the QLQ-BN20+2 scales of future uncertainty, visual disorder, and concentration difficulty. Baseline Karnofsky Performance Status was negatively correlated to QLQ-BN20+2 motor dysfunction but positively related to QLQ-C15-PAL physical functioning and QLQ-BN20+2 cognitive functioning

Conjugated π electron engineering of generalized stacking fault in graphene and h-BN.

PubMed

Ouyang, Bin; Chen, Cheng; Song, J

2018-03-02

Generalized-stacking-fault energy (GSFE) serves as an important metric that prescribes dislocation behaviors in materials. In this paper, utilizing first-principle calculations and chemical bonding analysis, we studied the behaviors of generalized stacking fault in graphene and h-BN. It has been shown that the π bond formation plays a critical role in the existence of metastable stacking fault (MSF) in graphene and h-BN lattice along certain slip directions. Chemical functionalization was then proposed as an effective means to engineer the π bond, and subsequently MSF along dislocation slips within graphene and h-BN. Taking hydrogenation as a representative functionalization method, we demonstrated that, with the preferential adsorption of hydrogen along the slip line, π electrons along the slip would be saturated by adsorbed hydrogen atoms, leading to the moderation or elimination of MSF. Our study elucidates the atomic mechanism of MSF formation in graphene-like materials, and more generally, provides important insights towards predictive tuning of mechanic properties in two-dimensional nanomaterials.

Conjugated π electron engineering of generalized stacking fault in graphene and h-BN

NASA Astrophysics Data System (ADS)

Ouyang, Bin; Chen, Cheng; Song, J.

2018-03-01

Generalized-stacking-fault energy (GSFE) serves as an important metric that prescribes dislocation behaviors in materials. In this paper, utilizing first-principle calculations and chemical bonding analysis, we studied the behaviors of generalized stacking fault in graphene and h-BN. It has been shown that the π bond formation plays a critical role in the existence of metastable stacking fault (MSF) in graphene and h-BN lattice along certain slip directions. Chemical functionalization was then proposed as an effective means to engineer the π bond, and subsequently MSF along dislocation slips within graphene and h-BN. Taking hydrogenation as a representative functionalization method, we demonstrated that, with the preferential adsorption of hydrogen along the slip line, π electrons along the slip would be saturated by adsorbed hydrogen atoms, leading to the moderation or elimination of MSF. Our study elucidates the atomic mechanism of MSF formation in graphene-like materials, and more generally, provides important insights towards predictive tuning of mechanic properties in two-dimensional nanomaterials.

A Novel Enzyme Portfolio for Red Algal Polysaccharide Degradation in the Marine Bacterium Paraglaciecola hydrolytica S66T Encoded in a Sizeable Polysaccharide Utilization Locus.

PubMed

Schultz-Johansen, Mikkel; Bech, Pernille K; Hennessy, Rosanna C; Glaring, Mikkel A; Barbeyron, Tristan; Czjzek, Mirjam; Stougaard, Peter

2018-01-01

Marine microbes are a rich source of enzymes for the degradation of diverse polysaccharides. Paraglaciecola hydrolytica S66 T is a marine bacterium capable of hydrolyzing polysaccharides found in the cell wall of red macroalgae. In this study, we applied an approach combining genomic mining with functional analysis to uncover the potential of this bacterium to produce enzymes for the hydrolysis of complex marine polysaccharides. A special feature of P. hydrolytica S66 T is the presence of a large genomic region harboring an array of carbohydrate-active enzymes (CAZymes) notably agarases and carrageenases. Based on a first functional characterization combined with a comparative sequence analysis, we confirmed the enzymatic activities of several enzymes required for red algal polysaccharide degradation by the bacterium. In particular, we report for the first time, the discovery of novel enzyme activities targeting furcellaran, a hybrid carrageenan containing both β-carrageenan and κ/β-carrageenan motifs. Some of these enzymes represent a new subfamily within the CAZy classification. From the combined analyses, we propose models for the complete degradation of agar and κ/β-type carrageenan by P. hydrolytica S66 T . The novel enzymes described here may find value in new bio-based industries and advance our understanding of the mechanisms responsible for recycling of red algal polysaccharides in marine ecosystems.

In vitro and in vivo evaluation of a 64Cu-labeled NOTA-Bn-SCN-Aoc-bombesin analogue in gastrin-releasing peptide receptor expressing prostate cancer.

PubMed

Craft, Jeffrey M; De Silva, Ravindra A; Lears, Kimberly A; Andrews, Rebecca; Liang, Kexian; Achilefu, Samuel; Rogers, Buck E

2012-07-01

Bombesin (BN) is an amphibian peptide that binds to the gastrin-releasing peptide receptor (GRPR). It has been demonstrated that BN analogues can be radiolabeled for potential diagnosis and treatment of GRPR-expressing malignancies. Previous studies have conjugated various chelators to the eight C-terminal amino acids of BN [BN(7-14)] for radiolabeling with 64Cu. Recently, (1,4,7-triazacyclononane-1,4,7-triacetic acid) (NOTA) has been evaluated as the five-coordinate 64Cu complex, with results indicating GRPR-specific tumor uptake. This study aimed to conjugate S-2-(4-isothiocyanatobenzyl)-NOTA (p-SCN-Bn-NOTA) to BN(7-14) such that it could form a six-coordinate complex with 64Cu and to evaluate the resulting peptide. p-SCN-NOTA was conjugated to 8-aminooctanoic acid (Aoc)-BN(7-14) in solution to yield NOTA-Bn-SCN-Aoc-BN(7-14). The unlabeled peptide was evaluated in a cell binding assay using PC-3 prostate cancer cells and 125I-Tyr4-BN to determine the IC50 value. The peptide was radiolabeled with 64Cu and evaluated for internalization into PC-3 cells and for tumor uptake in mice bearing PC-3 xenografts using biodistribution and micro-positron emission tomography imaging studies. The binding assay demonstrated that NOTA-Bn-SCN-Aoc-BN(7-14) bound with high affinity to GRPR with an IC50 of 1.4 nM. The radiolabeled peptide demonstrated time-dependent internalization into PC-3 cells. In vivo, the peptide demonstrated tumor-specific uptake and imaging that were comparable to those of previously reported 64Cu-labeled BN analogues. These studies demonstrate that 64Cu-NOTA-Bn-SCN-Aoc-BN(7-14) binds to GRPR-expressing cells and that it can be used for imaging of GRPR-expressing prostate cancer. Copyright © 2012 Elsevier Inc. All rights reserved.

Stabilization of the O p2x2 phase on Cu(001) sheltered by wrinkled BN over-layer

NASA Astrophysics Data System (ADS)

Kim, Yong-Sung; Ma, Chuanxu; Li, An-Ping; Yoon, Mina

The 2 √3x √3R45°phase of oxygen (O) on the Cu(001) surface has been observed in scanning tunneling microscopy (STM) measurements. Although the p2x2 phase of O on the Cu(001) surface has been proposed theoretically to be the most stable in O-lean conditions, it has not been observed in experiments for a long time. Recently, the O p2x2 phase has been found in STM on the Cu(001) surface with an overlying BN monolayer. In this theoretical study, we investigate what the role of BN over-layer is to stabilize the O p2x2 phase on the Cu(001) surface. The BN over-layer is lattice-matched with the Cu(001) surface and the BN mono-layer sheet is periodically wrinkled along the BN arm-chair direction and along the [100] or [010] direction on the Cu(001) surface. The interlayer space between the Cu(001) surface and the bulge of the wrinkled BN sheet is found to play as a preferential shelter for O to be adsorbed, and the boundary of the BN inner wall along the [010] or [100] direction makes the p2x2 phase more favorable against the 45°-tilted 2 √3x √3R45°phase of O on the Cu(001) surface. This was supported by Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility, and the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, maaged by UT-Battelle, LLC, for the U. S. DOE.

Paraburkholderia aromaticivorans sp. nov., an aromatic hydrocarbon-degrading bacterium, isolated from gasoline-contaminated soil.

PubMed

Lee, Yunho; Jeon, Che Ok

2018-04-01

A Gram-stain-negative, facultatively aerobic, aromatic hydrocarbon-degrading bacterium, designated strain BN5 T , was isolated from gasoline-contaminated soil. Cells were motile and slightly curved rods with a single flagellum showing catalase and oxidase activities. Growth was observed at 20-37 °C (optimum, 25-30 °C), pH 3-7 (optimum, pH 5-6) and 0-2 % NaCl (optimum, 0 %). Ubiquinone-8 was the predominant respiratory quinone. The major fatty acids were C16 : 0, cyclo-C19 : 0ω8c and summed feature 8 (comprising C18 : 1ω7c and/or C18 : 1ω6c). Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an unidentified phosphoamino lipid, three unidentified amino lipids and eight unidentified lipids were the identified polar lipids. The DNA G+C content was 62.93 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain BN5 T formed a phylogenic lineage with members of the genus Paraburkholderia and showed the highest 16S rRNA gene sequence similarities to Paraburkholderia phytofirmans PsJN T (99.4 %), Paraburkholderia dipogonis DL7 T (98.8 %) and Paraburkholderia insulsa PNG-April T (98.8 %). The average nucleotide identity and in silico DNA-DNA hybridization (DDH) values between strain BN5 T and P. phytofirmans PsJN T were 88.5 and 36.5 %, respectively. The DDH values for strain BN5 T with P. dipogonis LMG 28415 T and P. insulsa DSM 28142 T were 41.0±4.9 % (reciprocal, 33.0±4.3 %) and 47.1±6.6 % (reciprocal, 51.7±5.4 %), respectively. Based on its physiological, chemotaxonomic and phylogenetic features, we conclude that strain BN5 T is a novel species of the genus Paraburkholderia, for which the name Paraburkholderia aromaticivorans sp. nov. is proposed. The type strain is BN5 T (=KACC 19419 T =JCM 32303 T ).

High hardness BaCb-(BxOy/BN) composites with 3D mesh-like fine grain-boundary structure by reactive spark plasma sintering.

PubMed

Vasylkiv, Oleg; Borodianska, Hanna; Badica, Petre; Grasso, Salvatore; Sakka, Yoshio; Tok, Alfred; Su, Liap Tat; Bosman, Michael; Ma, Jan

2012-02-01

Boron carbide B4C powders were subject to reactive spark plasma sintering (also known as field assisted sintering, pulsed current sintering or plasma assisted sintering) under nitrogen atmosphere. For an optimum hexagonal BN (h-BN) content estimated from X-ray diffraction measurements at approximately 0.4 wt%, the as-prepared BaCb-(BxOy/BN) ceramic shows values of Berkovich and Vickers hardness of 56.7 +/- 3.1 GPa and 39.3 +/- 7.6 GPa, respectively. These values are higher than for the vacuum SPS processed B4C pristine sample and the h-BN -mechanically-added samples. XRD and electronic microscopy data suggest that in the samples produced by reactive SPS in N2 atmosphere, and containing an estimated amount of 0.3-1.5% h-BN, the crystallite size of the boron carbide grains is decreasing with the increasing amount of N2, while for the newly formed lamellar h-BN the crystallite size is almost constant (approximately 30-50 nm). BN is located at the grain boundaries between the boron carbide grains and it is wrapped and intercalated by a thin layer of boron oxide. BxOy/BN forms a fine and continuous 3D mesh-like structure that is a possible reason for good mechanical properties.

Nonequilibrium BN-ZnO: Optical properties and excitonic effects from first principles

NASA Astrophysics Data System (ADS)

Zhang, Xiao; Schleife, André

2018-03-01

The nonequilibrium boron nitride (BN) phase of zinc oxide (ZnO) has been reported for thin films and nanostructures, however, its properties are not well understood due to a persistent controversy that prevents reconciling experimental and first-principles results for its atomic coordinates. We use first-principles theoretical spectroscopy to accurately compute electronic and optical properties, including single-quasiparticle and excitonic effects: Band structures and densities of states are computed using density functional theory, hybrid functionals, and the G W approximation. Accurate optical absorption spectra and exciton binding energies are computed by solving the Bethe-Salpeter equation for the optical polarization function. Using this data we show that the band-gap difference between BN-ZnO and wurtzite (WZ) ZnO agrees very well with experiment when the theoretical lattice geometry is used, but significantly disagrees for the experimental atomic coordinates. We also show that the optical anisotropy of BN-ZnO differs significantly from that of WZ-ZnO, allowing us to optically distinguish both polymorphs. By using the transfer-matrix method to solve Maxwell's equations for thin films composed of both polymorphs, we illustrate that this opens up a promising route for tuning optical properties.

Surprising stability of neutral interstitial hydrogen in diamond and cubic BN

DOE PAGES

Lyons, J. L.; Van de Walle, C. G.

2016-01-21

We report that in virtually all semiconductors and insulators, hydrogen interstitials (H i) act as negative-U centers, implying that hydrogen is never stable in the neutral charge state. Using hybrid density functional calculations, we find a different behavior for H i in diamond and cubic BN. In diamond, H i is a very strong positive-U center, and the H 0 icharge state is stable over a Fermi-level range of more than 2 eV. In cubic BN, a III-V compound similar to diamond, we also find positive-U behavior, though over a much smaller Fermi-level range. Finally, these results highlight the uniquemore » behavior of Hi in these covalent wide-band-gap semiconductors.« less

Theory of proximity-induced exchange coupling in graphene on hBN/(Co, Ni)

NASA Astrophysics Data System (ADS)

Zollner, Klaus; Gmitra, Martin; Frank, Tobias; Fabian, Jaroslav

2016-10-01

Graphene, being essentially a surface, can borrow some properties of an insulating substrate (such as exchange or spin-orbit couplings) while still preserving a great degree of autonomy of its electronic structure. Such derived properties are commonly labeled as proximity. Here we perform systematic first-principles calculations of the proximity exchange coupling, induced by cobalt (Co) and nickel (Ni) in graphene, via a few (up to three) layers of hexagonal boron nitride (hBN). We find that the induced spin splitting of the graphene bands is of the order of 10 meV for a monolayer of hBN, decreasing in magnitude but alternating in sign by adding each new insulating layer. We find that the proximity exchange can be giant if there is a resonant d level of the transition metal close to the Dirac point. Our calculations suggest that this effect could be present in Co heterostructures, in which a d level strongly hybridizes with the valence-band orbitals of graphene. Since this hybridization is spin dependent, the proximity spin splitting is unusually large, about 10 meV even for two layers of hBN. An external electric field can change the offset of the graphene and transition-metal orbitals and can lead to a reversal of the sign of the exchange parameter. This we predict to happen for the case of two monolayers of hBN, enabling electrical control of proximity spin polarization (but also spin injection) in graphene/hBN/Co structures. Nickel-based heterostructures show weaker proximity effects than cobalt heterostructures. We introduce two phenomenological models to describe the first-principles data. The minimal model comprises the graphene (effective) pz orbitals and can be used to study transport in graphene with proximity exchange, while the pz-d model also includes hybridization with d orbitals, which is important to capture the giant proximity exchange. Crucial to both models is the pseudospin-dependent exchange coupling, needed to describe the different spin

High thermoelectricpower factor in graphene/hBN devices

PubMed Central

Duan, Junxi; Wang, Xiaoming; Lai, Xinyuan; Li, Guohong; Taniguchi, Takashi; Zebarjadi, Mona; Andrei, Eva Y.

2016-01-01

Fast and controllable cooling at nanoscales requires a combination of highly efficient passive cooling and active cooling. Although passive cooling in graphene-based devices is quite effective due to graphene’s extraordinary heat conduction, active cooling has not been considered feasible due to graphene’s low thermoelectric power factor. Here, we show that the thermoelectric performance of graphene can be significantly improved by using hexagonal boron nitride (hBN) substrates instead of SiO2. We find the room temperature efficiency of active cooling in the device, as gauged by the power factor times temperature, reaches values as high as 10.35 W⋅m−1⋅K−1, corresponding to more than doubling the highest reported room temperature bulk power factors, 5 W⋅m−1⋅K−1, in YbAl3, and quadrupling the best 2D power factor, 2.5 W⋅m−1⋅K−1, in MoS2. We further show that the Seebeck coefficient provides a direct measure of substrate-induced random potential fluctuations and that their significant reduction for hBN substrates enables fast gate-controlled switching of the Seebeck coefficient polarity for applications in integrated active cooling devices. PMID:27911824

Magnetic and Electronic Properties of h-BN Nanosheets with Nonmetal Atoms Adsorbed: an Ab Initio Study

NASA Astrophysics Data System (ADS)

Luo, M.; Yin, H. H.; Chu, J. H.

2018-04-01

The magnetic properties of the h-BN monolayer with nonmetal atoms are studied by ab initio methods. Different dopants (C, Cl, F, and O) and doping sites are considered. Magnetic behavior is observed in the two-dimensional (2D) BN system with C, Cl, and O atoms. On the other hand, the O adsorbed system shows a more stable formed structure among above three magnetic materials, we study the ferromagnetic (FM) interaction in 2D-BN system with two O adatoms. Interestingly, as the O-O distance increases, the interaction between two O adatoms prefers to a long-range FM coupling. This phenomenon could be well described by a simple Heisenberg model.

Pulsed laser deposition of single layer, hexagonal boron nitride (white graphene, h-BN) on fiber-oriented Ag(111)/SrTiO3(001)

NASA Astrophysics Data System (ADS)

Velázquez, Daniel; Seibert, Rachel; Man, Hamdi; Spentzouris, Linda; Terry, Jeff

2016-03-01

We report on the growth of 1-10 ML films of hexagonal boron nitride (h-BN), also known as white graphene, on fiber-oriented Ag buffer films on SrTiO3(001) by pulsed laser deposition. The Ag buffer films of 40 nm thickness were used as substitutes for expensive single crystal metallic substrates. In-situ, reflection high-energy electron diffraction was used to monitor the surface structure of the Ag films and to observe the formation of the characteristic h-BN diffraction pattern. Further evidence of the growth of h-BN was provided by attenuated total reflectance spectroscopy, which showed the characteristic h-BN peaks at ˜780 cm-1 and 1367.4 cm-1. Ex-situ photoelectron spectroscopy showed that the surface of the h-BN films is stoichiometric. The physical structure of the films was confirmed by scanning electron microscopy. The h-BN films grew as large, sub-millimeter sheets with nano- and micro-sheets scattered on the surface. The h-BN sheets can be exfoliated by the micromechanical adhesive tape method. Spectral analysis was performed by energy dispersive spectroscopy in order to identify the h-BN sheets after exfoliation. The use of thin film Ag allows for reduced use of Ag and makes it possible to adjust the surface morphology of the thin film prior to h-BN growth.

Quasi-Two-Dimensional h-BN/β-Ga2O3 Heterostructure Metal-Insulator-Semiconductor Field-Effect Transistor.

PubMed

Kim, Janghyuk; Mastro, Michael A; Tadjer, Marko J; Kim, Jihyun

2017-06-28

β-gallium oxide (β-Ga 2 O 3 ) and hexagonal boron nitride (h-BN) heterostructure-based quasi-two-dimensional metal-insulator-semiconductor field-effect transistors (MISFETs) were demonstrated by integrating mechanical exfoliation of (quasi)-two-dimensional materials with a dry transfer process, wherein nanothin flakes of β-Ga 2 O 3 and h-BN were utilized as the channel and gate dielectric, respectively, of the MISFET. The h-BN dielectric, which has an extraordinarily flat and clean surface, provides a minimal density of charged impurities on the interface between β-Ga 2 O 3 and h-BN, resulting in superior device performances (maximum transconductance, on/off ratio, subthreshold swing, and threshold voltage) compared to those of the conventional back-gated configurations. Also, double-gating of the fabricated device was demonstrated by biasing both top and bottom gates, achieving the modulation of the threshold voltage. This heterostructured wide-band-gap nanodevice shows a new route toward stable and high-power nanoelectronic devices.

Spin polarization of graphene and h -BN on Co(0001) and Ni(111) observed by spin-polarized surface positronium spectroscopy

NASA Astrophysics Data System (ADS)

Miyashita, A.; Maekawa, M.; Wada, K.; Kawasuso, A.; Watanabe, T.; Entani, S.; Sakai, S.

2018-05-01

In spin-polarized surface positronium annihilation measurements, the spin polarizations of graphene and h -BN on Co(0001) were higher than those on Ni(111), while no significant differences were seen between graphene and h -BN on the same metal. The obtained spin polarizations agreed with those expected from first-principles calculations considering the positron wave function and the electron density of states from the first surface layer to the vacuum region. The higher spin polarizations of graphene and h -BN on Co(0001) as compared to Ni(111) simply reflect the spin polarizations of these metals. The comparable spin polarizations of graphene and h -BN on the same metal are attributed to the creation of similar electronic states due to the strong influence of the metals: the Dirac cone of graphene and the band gap of h -BN disappear as a consequence of d -π hybridization.

Carbon-tuned bonding method significantly enhanced the hydrogen storage of BN-Li complexes.

PubMed

Deng, Qing-ming; Zhao, Lina; Luo, You-hua; Zhang, Meng; Zhao, Li-xia; Zhao, Yuliang

2011-11-01

Through first-principles calculations, we found doping carbon atoms onto BN monolayers (BNC) could significantly strengthen the Li bond on this material. Unlike the weak bond strength between Li atoms and the pristine BN layer, it is observed that Li atoms are strongly hybridized and donate their electrons to the doped substrate, which is responsible for the enhanced binding energy. Li adsorbed on the BNC layer can serve as a high-capacity hydrogen storage medium, without forming clusters, which can be recycled at room temperature. Eight polarized H(2) molecules are attached to two Li atoms with an optimal binding energy of 0.16-0.28 eV/H(2), which results from the electrostatic interaction of the polarized charge of hydrogen molecules with the electric field induced by positive Li atoms. This practical carbon-tuned BN-Li complex can work as a very high-capacity hydrogen storage medium with a gravimetric density of hydrogen of 12.2 wt%, which is much higher than the gravimetric goal of 5.5 wt % hydrogen set by the U.S. Department of Energy for 2015.

Fabrication and characterization of Ni-decorated h-BN powders with ChCl-EG ionic liquid as addition by electroless deposition

NASA Astrophysics Data System (ADS)

Yang, Qionglian; Ru, Juanjian; Song, Peng; Hu, Mingyu; Feng, Jing

2018-05-01

Ni-decorated h-BN powders are fabricated with ChCl-EG as additive via electroless plating in the paper. As comparison, the different additive concentration of choline chloride-ethylene glycol (ChCl-EG) ionic liquid (0 g l-1, 30 g l-1, 60 g l-1, 90 g l-1) is presented. The effects of ChCl-EG concentration are studied, including the surface morphologies, phase analysis of Ni-decorated h-BN powders and the residual Ni2+ concentration is measured in electroless plating bath. It is demonstrated that the deposition phenomena of nickel particles on h-BN surface is changed with the addition of ChCl-EG. When the concentration of ChCl-EG is 30 g l-1, the Ni particles on h-BN surface are in dispersed and spheroid state with the average size of 10-1000 nm. It can be found that 30 g l-1 ChCl-EG is conducive to the arise of deposition phenomena, which is the formation of the single nickel particle on h-BN surface. Besides, more Ni particles are deposited on h-BN surface with the increase of nickel plating times, which is characterized with scanning electron microscope and transmission electron microscope. Furthermore, the deposition phenomenon and growth mechanism are proposed without and with ChCl-EG as additive to further elaborate the formation of Ni particles on h-BN surface.

Fabrication and characterization of Ni-decorated h-BN powders with ChCl-EG ionic liquid as addition by electroless deposition.

PubMed

Yang, Qionglian; Ru, Juanjian; Song, Peng; Hu, Mingyu; Feng, Jing

2018-05-01

Ni-decorated h-BN powders are fabricated with ChCl-EG as additive via electroless plating in the paper. As comparison, the different additive concentration of choline chloride-ethylene glycol (ChCl-EG) ionic liquid (0 g l -1 , 30 g l -1 , 60 g l -1 , 90 g l -1 ) is presented. The effects of ChCl-EG concentration are studied, including the surface morphologies, phase analysis of Ni-decorated h-BN powders and the residual Ni 2+ concentration is measured in electroless plating bath. It is demonstrated that the deposition phenomena of nickel particles on h-BN surface is changed with the addition of ChCl-EG. When the concentration of ChCl-EG is 30 g l -1 , the Ni particles on h-BN surface are in dispersed and spheroid state with the average size of 10-1000 nm. It can be found that 30 g l -1 ChCl-EG is conducive to the arise of deposition phenomena, which is the formation of the single nickel particle on h-BN surface. Besides, more Ni particles are deposited on h-BN surface with the increase of nickel plating times, which is characterized with scanning electron microscope and transmission electron microscope. Furthermore, the deposition phenomenon and growth mechanism are proposed without and with ChCl-EG as additive to further elaborate the formation of Ni particles on h-BN surface.

Improved BN Coatings on SiC Fibers in SiC Matrices

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.; Bhatt, Ramakrishna; Yun, Hee-Mann; DiCarlo, James A.

2004-01-01

Modifications of BN-based coatings that are used as interfacial layers between the fibers and matrices of SiCfiber/SiC-matrix composite materials have been investigated to improve the thermomechanical properties of these materials. Such interfacial coating layers, which are also known as interphases (not to be confused with interphase in the biological sense), contribute to strength and fracture toughness of a fiber/matrix composite material by providing for limited amounts of fiber/matrix debonding and sliding to absorb some of the energy that would otherwise contribute to the propagation of cracks. Heretofore, the debonding and sliding have been of a type called inside debonding because they have taken place predominantly on the inside surfaces of the BN layers that is, at the interfaces between the SiC fibers and the interphases. The modifications cause the debonding and sliding to include more of a type, called outside debonding, that takes place at the outside surfaces of the BN layers that is, at the interfaces between the interphases and the matrix (see figure). One of the expected advantages of outside debonding is that unlike in inside debonding, the interphases would remain on the crack-bridging fibers. The interphases thus remaining should afford additional protection against oxidation at high temperature and should delay undesired fiber/fiber fusion and embrittlement of the composite material. A secondary benefit of outside debonding is that the interphase/matrix interfaces could be made more compliant than are the fiber/interphase interfaces, which necessarily incorporate the roughness of the SiC fibers. By properly engineering BN interphase layers to favor outside debonding, it should be possible, not only to delay embrittlement at intermediate temperatures, but also to reduce the effective interfacial shear strength and increase the failure strain and toughness of the composite material. Two techniques have been proposed and partially experimentally

Multilayered BN Coatings Processed by a Continuous LPCVD Treatment onto Hi-Nicalon Fibers

NASA Astrophysics Data System (ADS)

Jacques, S.; Vincent, H.; Vincent, C.; Lopez-Marure, A.; Bouix, J.

2001-12-01

Boron nitride coatings were deposited onto SiC fibers by means of continuous low-pressure chemical vapor deposition (LPCVD) treatment from BF3/NH3 mixtures. This process lies in unrolling the fiber in the reactor axis. The relationships between the processing parameters and the structure of the BN deposits are presented. Thanks to a temperature gradient present in the reactor, multilayered BN films can be performed by stacking successive isotropic and anisotropic sublayers. Tensile tests show that when the temperature profile is well adapted, the SiC fibers are not damaged by the LPCVD treatment.

Dielectric Response and Born Dynamic Charge of BN Nanotubes from Ab Initio Finite Electric Field Calculations

NASA Astrophysics Data System (ADS)

Guo, Guang-Yu; Ishibashi, Shoji; Tamura, Tomoyuki; Terakura, Kiyoyuki

2007-03-01

Since the discovery of carbon nanotubes (CNTs) in 1991 by Iijima, carbon and other nanotubes have attracted considerable interest worldwide because of their unusual properties and also great potentials for technological applications. Though CNTs continue to attract great interest, other nanotubes such as BN nanotubes (BN-NTs) may offer different opportunities that CNTs cannot provide. In this contribution, we present the results of our recent systematic ab initio calculations of the static dielectric constant, electric polarizability, Born dynamical charge, electrostriction coefficient and piezoelectric constant of BN-NTs using the latest crystalline finite electric field theory [1]. [1] I. Souza, J. Iniguez, and D. Vanderbilt, Phys. Rev. Lett. 89, 117602 (2002); P. Umari and A. Pasquarello, Phys. Rev. Lett. 89, 157602 (2002).

Understanding Coulomb Scattering Mechanism in Monolayer MoS2 Channel in the Presence of h-BN Buffer Layer.

PubMed

Joo, Min-Kyu; Moon, Byoung Hee; Ji, Hyunjin; Han, Gang Hee; Kim, Hyun; Lee, Gwanmu; Lim, Seong Chu; Suh, Dongseok; Lee, Young Hee

2017-02-08

As the thickness becomes thinner, the importance of Coulomb scattering in two-dimensional layered materials increases because of the close proximity between channel and interfacial layer and the reduced screening effects. The Coulomb scattering in the channel is usually obscured mainly by the Schottky barrier at the contact in the noise measurements. Here, we report low-temperature (T) noise measurements to understand the Coulomb scattering mechanism in the MoS 2 channel in the presence of h-BN buffer layer on the silicon dioxide (SiO 2 ) insulating layer. One essential measure in the noise analysis is the Coulomb scattering parameter (α SC ) which is different for channel materials and electron excess doping concentrations. This was extracted exclusively from a 4-probe method by eliminating the Schottky contact effect. We found that the presence of h-BN on SiO 2 provides the suppression of α SC twice, the reduction of interfacial traps density by 100 times, and the lowered Schottky barrier noise by 50 times compared to those on SiO 2 at T = 25 K. These improvements enable us to successfully identify the main noise source in the channel, which is the trapping-detrapping process at gate dielectrics rather than the charged impurities localized at the channel, as confirmed by fitting the noise features to the carrier number and correlated mobility fluctuation model. Further, the reduction in contact noise at low temperature in our system is attributed to inhomogeneous distributed Schottky barrier height distribution in the metal-MoS 2 contact region.

Comparison of Multiple Molecular Dynamics Trajectories Calculated for the Drug-Resistant HIV-1 Integrase T66I/M154I Catalytic Domain

PubMed Central

Brigo, Alessandro; Lee, Keun Woo; Iurcu Mustata, Gabriela; Briggs, James M.

2005-01-01

HIV-1 integrase (IN) is an essential enzyme for the viral replication and an interesting target for the design of new pharmaceuticals for multidrug therapy of AIDS. Single and multiple mutations of IN at residues T66, S153, or M154 confer degrees of resistance to several inhibitors that prevent the enzyme from performing its normal strand transfer activity. Four different conformations of IN were chosen from a prior molecular dynamics (MD) simulation on the modeled IN T66I/M154I catalytic core domain as starting points for additional MD studies. The aim of this article is to understand the dynamic features that may play roles in the catalytic activity of the double mutant enzyme in the absence of any inhibitor. Moreover, we want to verify the influence of using different starting points on the MD trajectories and associated dynamical properties. By comparison of the trajectories obtained from these MD simulations we have demonstrated that the starting point does not affect the conformational space explored by this protein and that the time of the simulation is long enough to achieve convergence for this system. PMID:15764656

Large-roll growth of 25-inch hexagonal BN monolayer film for self-release buffer layer of free-standing GaN wafer

NASA Astrophysics Data System (ADS)

Wu, Chenping; Soomro, Abdul Majid; Sun, Feipeng; Wang, Huachun; Huang, Youyang; Wu, Jiejun; Liu, Chuan; Yang, Xiaodong; Gao, Na; Chen, Xiaohong; Kang, Junyong; Cai, Duanjun

2016-10-01

Hexagonal boron nitride (h-BN) is known as promising 2D material with a wide band-gap (~6 eV). However, the growth size of h-BN film is strongly limited by the size of reaction chamber. Here, we demonstrate the large-roll synthesis of monolayer and controllable sub-monolayer h-BN film on wound Cu foil by low pressure chemical vapor deposition (LPCVD) method. By winding the Cu foil substrate into mainspring shape supported by a multi-prong quartz fork, the reactor size limit could be overcome by extending the substrate area to a continuous 2D curl of plane inward. An extremely large-size monolayer h-BN film has been achieved over 25 inches in a 1.2” tube. The optical band gap of h-BN monolayer was determined to be 6.0 eV. The h-BN film was uniformly transferred onto 2” GaN or 4” Si wafer surfaces as a release buffer layer. By HVPE method, overgrowth of thick GaN wafer over 200 μm has been achieved free of residual strain, which could provide high quality homo-epitaxial substrate.

Stitching h-BN by atomic layer deposition of LiF as a stable interface for lithium metal anode

PubMed Central

Xie, Jin; Liao, Lei; Gong, Yongji; Li, Yanbin; Shi, Feifei; Pei, Allen; Sun, Jie; Zhang, Rufan; Kong, Biao; Subbaraman, Ram; Christensen, Jake; Cui, Yi

2017-01-01

Defects are important features in two-dimensional (2D) materials that have a strong influence on their chemical and physical properties. Through the enhanced chemical reactivity at defect sites (point defects, line defects, etc.), one can selectively functionalize 2D materials via chemical reactions and thereby tune their physical properties. We demonstrate the selective atomic layer deposition of LiF on defect sites of h-BN prepared by chemical vapor deposition. The LiF deposits primarily on the line and point defects of h-BN, thereby creating seams that hold the h-BN crystallites together. The chemically and mechanically stable hybrid LiF/h-BN film successfully suppresses lithium dendrite formation during both the initial electrochemical deposition onto a copper foil and the subsequent cycling. The protected lithium electrodes exhibit good cycling behavior with more than 300 cycles at relatively high coulombic efficiency (>95%) in an additive-free carbonate electrolyte. PMID:29202031

Stitching h-BN by atomic layer deposition of LiF as a stable interface for lithium metal anode

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

Xie, Jin; Liao, Lei; Gong, Yongji

Defects are important features in two-dimensional (2D) materials that have a strong influence on their chemical and physical properties. Through the enhanced chemical reactivity at defect sites (point defects, line defects, etc.), one can selectively functionalize 2D materials via chemical reactions and thereby tune their physical properties. We demonstrate the selective atomic layer deposition of LiF on defect sites of h-BN prepared by chemical vapor deposition. The LiF deposits primarily on the line and point defects of h-BN, thereby creating seams that hold the h-BN crystallites together. The chemically and mechanically stable hybrid LiF/h-BN film successfully suppresses lithium dendrite formationmore » during both the initial electrochemical deposition onto a copper foil and the subsequent cycling. In conclusion, the protected lithium electrodes exhibit good cycling behavior with more than 300 cycles at relatively high coulombic efficiency (>95%) in an additive-free carbonate electrolyte.« less

Stitching h-BN by atomic layer deposition of LiF as a stable interface for lithium metal anode

DOE PAGES

Xie, Jin; Liao, Lei; Gong, Yongji; ...

2017-11-29

Defects are important features in two-dimensional (2D) materials that have a strong influence on their chemical and physical properties. Through the enhanced chemical reactivity at defect sites (point defects, line defects, etc.), one can selectively functionalize 2D materials via chemical reactions and thereby tune their physical properties. We demonstrate the selective atomic layer deposition of LiF on defect sites of h-BN prepared by chemical vapor deposition. The LiF deposits primarily on the line and point defects of h-BN, thereby creating seams that hold the h-BN crystallites together. The chemically and mechanically stable hybrid LiF/h-BN film successfully suppresses lithium dendrite formationmore » during both the initial electrochemical deposition onto a copper foil and the subsequent cycling. In conclusion, the protected lithium electrodes exhibit good cycling behavior with more than 300 cycles at relatively high coulombic efficiency (>95%) in an additive-free carbonate electrolyte.« less

Validation of the Chinese version of EORTC QLQ-BN20 for patients with brain cancer.

PubMed

Zhang, K; Tian, J; He, Z; Sun, W; Pekbay, B; Lin, Y; Wu, D; Zhang, J; Chen, P; Guo, H; Wan, Y; Wang, M; Yang, S; Zheng, J; Zhang, L

2018-03-01

This is a single centre study in mainland China aiming to evaluate the reliability, validity and responsiveness of the Chinese version of EORTC QLQ-BN20, designed by The European Organization for Research and Treatment of Cancer Quality of Life Group to evaluate the life quality of patients with brain tumour, cancer or metastases. One hundred and eighty-eight patients with primary or secondary brain cancer from Hunan Provincial Tumor Hospital during September 2013 to June 2014 completed the Chinese EORTC QLQ-C30/BN20 questionnaires developed by translation, back translation and cultural adaptation. Results were statistically analysed using SPSS17.0. The internal consistency (Cronbach's α coefficient) was between .753 and .869, the correlation coefficients among items and its own dimension were bigger than .4, and all items had a better correlation with its own dimension. The Spearman was used to analyse the correlation of each dimension between EORTC QLQ-BN20 and EORTC QLQ-C30, and the result showed that individual dimensions were moderately correlated, other dimensions were weakly correlated. In conclusion, the Chinese version of EORTC QLQ BN20 questionnaire had great relevance, reliability, convergent validity and discriminant validity. It provides a valuable tool for the assessment of health-related quality of life in clinical studies of Chinese patients with primary or secondary brain cancer. © 2018 John Wiley & Sons Ltd.

Polarity control of h-BN nanoribbon edges by strain and edge termination.

PubMed

Yamanaka, Ayaka; Okada, Susumu

2017-03-29

We studied the polarity of h-BN nano-flakes in terms of their edge geometries, edge hydrogen termination, and uniaxial strain by evaluating their electrostatic potential using density functional theory. Our calculations have shown that the polarity of the nanoribbons is sensitive to their edge shape, edge termination, and uniaxial tensile strain. Polarity inversion of the ribbons can be induced by controlling the hydrogen concentration at the edges and the uniaxial tensile strain. The polarity inversion indicates that h-BN nanoribbons can exhibit non-polar properties at a particular edge hydrogen concentration and tensile strain, even though the nanoribbons essentially have polarity at the edge. We also found that the edge angle affects the polarity of nanoribbons with hydrogenated edges.

Calculated Properties of Fully Hydrogenated Single Layers of BN, BC2N, and Graphene: Graphane and Its BN-Containing Analogues

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

Averill, Frank; Morris, James R; Cooper, Valentino R

2009-01-01

Carbon is an attractive material for hydrogen adsorption, due to its light weight, variety of structures, and ability to both physisorb and chemisorb hydrogen. Recently, fully hydrogenated graphene layers ( graphane ) have been predicted to exist [J.O. Sofo et al., Phys. Rev. B 75, 15340 (2007)], and experimentally observed [D.C. Elias et al., Science 323, 610 (2009)]. In this work, we examine analogues of graphane, in particular BNH2 and BC2NH4. Unlike graphene, these materials have a band gap without hydrogenation. Our results indicate that the hydrogenation product of BN is metastable: the fully hydrogenated compound BNH2 is higher inmore » energy than hexagonal BN sheets plus H2 molecules, in sharp contrast with graphane. We find that BC2NH4 is energetically very close to hexagonal BC2N+2H2 molecules. Furthermore our examination of the relative binding strengths of rows of symmetry related hydrogen atoms on BC2NH4shows that this compound is marginally higher in energy than BC2NH2 plus an H2 molecule, with the hydrogen atoms in BC2NH2 absorbed on the carbon sites. These remaining hydrogen atoms are not as strongly bound as in graphane, indicating that the average hydrogen chemisorption energy is controllable by changing the carbon content in the B-C-N layer.« less

Creep/Stress Rupture Behavior of 3D Woven SiC/SiC Composites with Sylramic-iBN, Super Sylramic-iBN and Hi-Nicalon-S Fibers at 2700F in Air

NASA Technical Reports Server (NTRS)

Bhatt, R. T.

2017-01-01

To determine the influence of fiber types on creep durability, 3D SiC/SiC CMCs were fabricated with Sylramic-iBN, super Sylramic-iBN and Hi-Nicalon-S fibers and the composite specimens were then tested under isothermal tensile creep at 14820C at 69, 103 and 138 MPa for up to 300hrs in air. The failed specimens were examined by scanning electron microscopy (SEM) and computed tomography (CT) for fracture mode analysis. The creep data of these composites are compared with those of other SiC/SiC composites in the literature. The results of this study will be presented.

Interface-induced perpendicular magnetic anisotropy of Co nanoparticles on single-layer h-BN/Pt(111)

NASA Astrophysics Data System (ADS)

Watanabe, Takahiro; Yamada, Yoichi; Koide, Akihiro; Entani, Shiro; Li, Songtian; Popov, Zakhar I.; Sorokin, Pavel B.; Naramoto, Hiroshi; Sasaki, Masahiro; Amemiya, Kenta; Sakai, Seiji

2018-01-01

Ferromagnetism with perpendicular magnetic anisotropy (PMA) was observed at room temperature in cobalt nanoparticles (NPs) grown on hexagonal boron nitride (h-BN) on a Pt(111) surface. It was shown that the Co NPs have planar hexagonal shapes with a mean diameter of ˜20 nm and a mean height of ˜1.6 nm. The depth-resolved analysis of X-ray magnetic circular dichroism at the Co L2,3-edges revealed that in the ferromagnetic Co NPs, the ratio of the orbital magnetic moment to the spin magnetic moment in the out-of-plane direction becomes larger at the Co NP/h-BN interface than the ratio in bulk Co. The B and N K-edge near edge X-ray absorption fine structures showed the orbital hybridization between the π orbitals of h-BN and d orbitals of Co at the interface, as an origin of the orbital magnetic moment enhancement possibly giving rise to PMA in the Co NPs.

Becoming Socialized into a New Professional Role: LPN to BN Student Nurses' Experiences with Legitimation

PubMed Central

Melrose, Sherri; Miller, Jean; Gordon, Kathryn; Janzen, Katherine J.

2012-01-01

This paper presents findings from a qualitative descriptive study that explored the professional socialization experiences of Licensed Practical Nurses (LPNs) who attended an online university to earn a Baccalaureate degree in nursing (BN), a prerequisite to writing the Canadian Registered Nurse (RN) qualifying exam. The project was framed from a constructivist worldview and Haas and Shaffir's theory of legitimation. Participants were 27 nurses in a Post-LPN to BN program who came from across Canada to complete required practicums. Data was collected from digital recordings of four focus groups held in different cities. Transcripts were analyzed for themes and confirmed with participants through member checking. Two overarching themes were identified and are presented to explain how these unique adult learners sought to legitimize their emerging identity as Registered Nurses (RNs). First, Post-LPN to BN students need little, if any, further legitimation to affirm their identities as “nurse.” Second, practicum interactions with instructors and new clinical experiences are key socializing agents. PMID:22548165

Becoming Socialized into a New Professional Role: LPN to BN Student Nurses' Experiences with Legitimation.

PubMed

Melrose, Sherri; Miller, Jean; Gordon, Kathryn; Janzen, Katherine J

2012-01-01

This paper presents findings from a qualitative descriptive study that explored the professional socialization experiences of Licensed Practical Nurses (LPNs) who attended an online university to earn a Baccalaureate degree in nursing (BN), a prerequisite to writing the Canadian Registered Nurse (RN) qualifying exam. The project was framed from a constructivist worldview and Haas and Shaffir's theory of legitimation. Participants were 27 nurses in a Post-LPN to BN program who came from across Canada to complete required practicums. Data was collected from digital recordings of four focus groups held in different cities. Transcripts were analyzed for themes and confirmed with participants through member checking. Two overarching themes were identified and are presented to explain how these unique adult learners sought to legitimize their emerging identity as Registered Nurses (RNs). First, Post-LPN to BN students need little, if any, further legitimation to affirm their identities as "nurse." Second, practicum interactions with instructors and new clinical experiences are key socializing agents.

The BnGRF2 gene (GRF2-like gene from Brassica napus) enhances seed oil production through regulating cell number and plant photosynthesis

PubMed Central

Liu, Jing; Hua, Wei; Yang, Hong-Li; Zhan, Gao-Miao; Deng, Lin-Bin; Wang, Xin-Fa; Liu, Gui-Hua; Wang, Han-Zhong

2012-01-01

Seed yield and oil content are two important agricultural characteristics in oil crop breeding, and a lot of functional gene research is being concentrated on increasing these factors. In this study, by differential gene expression analyses between rapeseed lines (zy036 and 51070) which exhibit different levels of seed oil production, BnGRF2 (Brassica napus growth-regulating factor 2-like gene) was identified in the high oil-producing line zy036. To elucidate the possible roles of BnGRF2 in seed oil production, the cDNA sequences of the rapeseed GRF2 gene were isolated. The Blastn result showed that rapeseed contained BnGRF2a/2b which were located in the A genome (A1 and A3) and C genome (C1 and C6), respectively, and the dominantly expressed gene BnGRF2a was chosen for transgenic research. Analysis of 35S-BnGRF2a transgenic Arabidopsis showed that overexpressed BnGRF2a resulted in an increase in seed oil production of >50%. Moreover, BnGRF2a also induced a >20% enlargement in extended leaves and >40% improvement in photosynthetic efficiency because of an increase in the chlorophyll content. Furthermore, transcriptome analyses indicated that some genes associated with cell proliferation, photosynthesis, and oil synthesis were up-regulated, which revealed that cell number and plant photosynthesis contributed to the increased seed weight and oil content. Because of less efficient self-fertilization induced by the longer pistil in the 35S-BnGRF2a transgenic line, Napin-BnGRF2a transgenic lines were further used to identify the function of BnGRF2, and the results showed that seed oil production also could increase >40% compared with the wild-type control. The results suggest that improvement to economically important characteristics in oil crops may be achieved by manipulation of the GRF2 expression level. PMID:22442419

The BnGRF2 gene (GRF2-like gene from Brassica napus) enhances seed oil production through regulating cell number and plant photosynthesis.

PubMed

Liu, Jing; Hua, Wei; Yang, Hong-Li; Zhan, Gao-Miao; Li, Rong-Jun; Deng, Lin-Bin; Wang, Xin-Fa; Liu, Gui-Hua; Wang, Han-Zhong

2012-06-01

Seed yield and oil content are two important agricultural characteristics in oil crop breeding, and a lot of functional gene research is being concentrated on increasing these factors. In this study, by differential gene expression analyses between rapeseed lines (zy036 and 51070) which exhibit different levels of seed oil production, BnGRF2 (Brassica napus growth-regulating factor 2-like gene) was identified in the high oil-producing line zy036. To elucidate the possible roles of BnGRF2 in seed oil production, the cDNA sequences of the rapeseed GRF2 gene were isolated. The Blastn result showed that rapeseed contained BnGRF2a/2b which were located in the A genome (A1 and A3) and C genome (C1 and C6), respectively, and the dominantly expressed gene BnGRF2a was chosen for transgenic research. Analysis of 35S-BnGRF2a transgenic Arabidopsis showed that overexpressed BnGRF2a resulted in an increase in seed oil production of >50%. Moreover, BnGRF2a also induced a >20% enlargement in extended leaves and >40% improvement in photosynthetic efficiency because of an increase in the chlorophyll content. Furthermore, transcriptome analyses indicated that some genes associated with cell proliferation, photosynthesis, and oil synthesis were up-regulated, which revealed that cell number and plant photosynthesis contributed to the increased seed weight and oil content. Because of less efficient self-fertilization induced by the longer pistil in the 35S-BnGRF2a transgenic line, Napin-BnGRF2a transgenic lines were further used to identify the function of BnGRF2, and the results showed that seed oil production also could increase >40% compared with the wild-type control. The results suggest that improvement to economically important characteristics in oil crops may be achieved by manipulation of the GRF2 expression level.

Acetone in Orion BN/KL. High-resolution maps of a special oxygen-bearing molecule

NASA Astrophysics Data System (ADS)

Peng, T.-C.; Despois, D.; Brouillet, N.; Baudry, A.; Favre, C.; Remijan, A.; Wootten, A.; Wilson, T. L.; Combes, F.; Wlodarczak, G.

2013-06-01

Aims: As one of the prime targets of interstellar chemistry study, Orion BN/KL clearly shows different molecular distributions between large nitrogen- (e.g., C2H5CN) and oxygen-bearing (e.g., HCOOCH3) molecules. However, acetone (CH3)2CO, a special complex O-bearing molecule, has been shown to have a very different distribution from other typical O-bearing molecules in the BN/KL region. Therefore, it is worth investigating acetone in detail at high angular resolutions, which will help us understand the formation of this molecule and its chemical role in the complex BN/KL region. Methods: We searched for acetone within our IRAM Plateau de Bure Interferometer 3 mm and 1.3 mm data sets. Twenty-two acetone lines were searched within these data sets. The angular resolution ranged from 1farcs8×0farcs8 to 6farcs0×2farcs3, and the spectral resolution ranged from 0.4 to 1.9 km s-1. Results: Nine of the acetone lines appear free of contamination. Three main acetone peaks (Ace-1, 2, and 3) are identified in Orion BN/KL. The new acetone source Ace-3 and the extended emission in the north of the hot core region have been found for the first time. An excitation temperature of about 150 K is determined toward Ace-1 and Ace-2, and the acetone column density is estimated to be 2-4 × 1016 cm-2 with a relative abundance of 1-6 × 10-8 toward these two peaks. Acetone is a few times less abundant toward the hot core and Ace-3 compared with Ace-1 and Ace-2. Conclusions: We find that the overall distribution of acetone in BN/KL is similar to that of N-bearing molecules, e.g., NH3 and C2H5CN, and very different from those of large O-bearing molecules, e.g., HCOOCH3 and (CH3)2O. Our findings show the acetone distribution is more extended than in previous studies and does not originate only in those areas where both N-bearing and O-bearing species are present. Moreover, because the N-bearing molecules may be associated with shocked gas in Orion BN/KL, this suggests that the formation and

Effects of nano-sized boron nitride (BN) reinforcement in expandable graphite based in-tumescent fire retardant coating

NASA Astrophysics Data System (ADS)

Zulkurnain, E. S.; Ahmad, F.; Gillani, Q. F.

2016-08-01

The purpose of in-tumescent fire retardant coating (IFRC) is to protect substrate from fire attack by limiting heat transfer. A range of coating formulations have been prepared using Bisphenol A epoxy resin BE-188 and polyamide solidifier H-2310 as two-part binder, ammonium polyphosphate (APP) as acid source, melamine (MEL) as the blowing agent, expandable graphite (EG) as carbon source and nano-boron nitride (BN) as inorganic nano filler. The filler was used to improve the performances of the APP-EG-MEL coating. The effects of nano-BN on the char morphology and thermal degradation were investigated by fire test, thermo gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X- ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FESEM). The results showed that by substituting or reinforcing of 4% weight percentage of nano-BN, residual weight of the char increases by 23.82% compared to APP-EG-MEL coating without filler. Higher carbon content was obtained in the char and a more compact char was produced. The results indicated that nano-BN could be used as a filler to improve thermal stability of the APP-EG-MEL coating.

Electronic theoretical study on the influence of torsional deformation on the electronic structure and optical properties of BN-doped graphene

NASA Astrophysics Data System (ADS)

Fan, Dazhi; Liu, Guili; Wei, Lin

2018-06-01

Based on the density functional theory, the effect of torsional deformation on the electronic structure and optical properties of boron nitride (BN)-doped graphene is studied by using the first-principles calculations. The band structure calculations show that the intrinsic graphene is a semi-metallic material with zero band gap and the torsional deformation has a large effect on its band gap, opening its band gap and turning it from the semi-metal to the medium band gap semiconductor. The doping of BN in graphene makes its band gap open and becomes a medium band gap semiconductor. When it is subjected to a torsional effect, it is found to have a weak influence on its band gap. In other words, the doping of BN makes the changes of the band gap of graphene no longer sensitive to torsional deformation. Optical properties show that the doping of BN leads to a significant decrease in the light absorption coefficient and reflectivity of the graphene at the characteristic peak and that of BN-doped graphene system is also weakened by torsional deformation at the characteristic peak. In the absorption spectrum, the absorption peaks of the doping system of the torsion angle of 2-20∘ are redshifted compared with that of the BN-doped system (the torsion angle is 0∘). In the reflection spectrum, the two reflection peaks are all redshifted relative to that of the BN-doped system (the torsion angle is 0∘) and when the torsion angle exceeds 12∘, the size relationship between the two peaks is interchanged. The results of this paper are of guiding significance for the study of graphene-based nanotube devices in terms of deformation.

Oxidation of SiC/BN/SiC Composites in Reduced Oxygen Partial Pressures

NASA Technical Reports Server (NTRS)

Opila, Elizabeth J.; Boyd, Meredith

2010-01-01

SiC fiber-reinforced SiC composites with a BN interphase are proposed for use as leading edge structures of hypersonic vehicles. The durability of these materials under hypersonic flight conditions is therefore of interest. Thermogravimetric analysis was used to characterize the oxidation kinetics of both the constituent fibers and composite coupons at four temperatures: 816, 1149, 1343, and 1538 C (1500, 2100, 2450, and 2800 F) and in oxygen partial pressures between 5% and 0.1% (balance argon) at 1 atm total pressure. One edge of the coupons was ground off so the effects of oxygen ingress into the composite could be monitored by post-test SEM and EDS. Additional characterization of the oxidation products was conducted by XPS and TOF-SIMS. Under most conditions, the BN oxidized rapidly, leading to the formation of borosilicate glass. Rapid initial oxidation followed by volatilization of boria lead to protective oxide formation and further oxidation was slow. At 1538C in 5% oxygen, both the fibers and coupons exhibited borosilicate glass formation and bubbling. At 1538C in 0.1% oxygen, active oxidation of both the fibers and the composites was observed leading to rapid SiC degradation. BN oxidation at 1538C in 0.1% oxygen was not significant.

Hybrid MoS2/h-BN Nanofillers As Synergic Heat Dissipation and Reinforcement Additives in Epoxy Nanocomposites.

PubMed

Ribeiro, Hélio; Trigueiro, João Paulo C; Silva, Wellington M; Woellner, Cristiano F; Owuor, Peter S; Cristian Chipara, Alin; Lopes, Magnovaldo C; Tiwary, Chandra S; Pedrotti, Jairo J; Villegas Salvatierra, Rodrigo; Tour, James M; Chopra, Nitin; Odeh, Ihab N; Silva, Glaura G; Ajayan, Pulickel M

2017-09-26

Two-dimensional (2D) nanomaterials as molybdenum disulfide (MoS 2 ), hexagonal boron nitride (h-BN), and their hybrid (MoS 2 /h-BN) were employed as fillers to improve the physical properties of epoxy composites. Nanocomposites were produced in different concentrations and studied in their microstructure, mechanical and thermal properties. The hybrid 2D mixture imparted efficient reinforcement to the epoxy leading to increases of up to 95% in tensile strength, 60% in ultimate strain, and 58% in Young's modulus. Moreover, an enhancement of 203% in thermal conductivity was achieved for the hybrid composite as compared to the pure polymer. The incorporation of MoS 2 /h-BN mixture nanofillers in epoxy resulted in nanocomposites with multifunctional characteristics for applications that require high mechanical and thermal performance.

Single-step synthesis of crystalline h-BN quantum- and nanodots embedded in boron carbon nitride films

NASA Astrophysics Data System (ADS)

Matsoso, Boitumelo J.; Ranganathan, Kamalakannan; Mutuma, Bridget K.; Lerotholi, Tsenolo; Jones, Glenn; Coville, Neil J.

2017-03-01

Herein we report on the synthesis and characterization of novel crystalline hexagonal boron nitride (h-BN) quantum- and nanodots embedded in large-area boron carbon nitride (BCN) films. The films were grown on a Cu substrate by an atmospheric pressure chemical vapour deposition technique. Methane, ammonia, and boric acid were used as precursors for C, N and B to grow these few atomic layer thick uniform films. We observed that both the size of the h-BN quantum/nanodots and thickness of the BCN films were influenced by the vaporization temperature of boric acid as well as the H3BO3 (g) flux over the Cu substrate. These growth conditions were easily achieved by changing the position of the solid boric acid in the reactor with respect to the Cu substrate. Atomic force microscope (AFM) and TEM analyses show a variation in the h-BN dot size distribution, ranging from nanodots (˜224 nm) to quantum dots (˜11 nm) as the B-source is placed further away from the Cu foil. The distance between the B-source and the Cu foil gave an increase in the C atomic composition (42 at% C-65 at% C) and a decrease in both B and N contents (18 at% B and 14 at% N to 8 at% B and 7 at% N). UV-vis absorption spectra showed a higher band gap energy for the quantum dots (5.90 eV) in comparison with the nanodots (5.68 eV) due to a quantum confinement effect. The results indicated that the position of the B-source and its reaction with ammonia plays a significant role in controlling the nucleation of the h-BN quantum- and nanodots. The films are proposed to be used in solar cells. A mechanism to explain the growth of h-BN quantum/nanodots in BCN films is reported.

The Evolution of Interfacial Sliding Stresses During Cyclic Push-in Testing of C- and BN-Coated Hi-Nicalon Fiber-Reinforced CMCs

NASA Technical Reports Server (NTRS)

Eldridge, J. I.; Bansal, N. P.; Bhatt, R. T.

1998-01-01

Interfacial debond cracks and fiber/matrix sliding stresses in ceramic matrix composites (CMCs) can evolve under cyclic fatigue conditions as well as with changes in the environment, strongly affecting the crack growth behavior, and therefore, the useful service lifetime of the composite. In this study, room temperature cyclic fiber push-in testing was applied to monitor the evolution of frictional sliding stresses and fiber sliding distances with continued cycling in both C- and BN-coated Hi-Nicalon SiC fiber-reinforced CMCs. A SiC matrix composite reinforced with C-coated Hi-Nical on fibers as well as barium strontium aluminosilicate (BSAS) matrix composites reinforced with BN-coated (four different deposition processes compared) Hi-Nicalon fibers were examined. For failure at a C interface, test results indicated progressive increases in fiber sliding distances during cycling in room air but not in nitrogen. These results suggest the presence of moisture will promote crack growth when interfacial failure occurs at a C interface. While short-term testing environmental effects were not apparent for failure at the BN interfaces, long-term exposure of partially debonded BN-coated fibers to humid air resulted in large increases in fiber sliding distances and decreases in interfacial sliding stresses for all the BN coatings, presumably due to moisture attack. A wide variation was observed in debond and frictional sliding stresses among the different BN coatings.

49 CFR 178.39 - Specification 3BN seamless nickel cylinders.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) Type, size and service pressure. A DOT 3BN cylinder is a seamless nickel cylinder with a water capacity (nominal) not over 125 pounds water capacity (nominal) and a service pressure at least 150 to not over 500...) Wall thickness. The wall stress may not exceed 15,000 psi. A minimum wall thickness of 0.100 inch is...

49 CFR 178.39 - Specification 3BN seamless nickel cylinders.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Type, size and service pressure. A DOT 3BN cylinder is a seamless nickel cylinder with a water capacity (nominal) not over 125 pounds water capacity (nominal) and a service pressure at least 150 to not over 500...) Wall thickness. The wall stress may not exceed 15,000 psi. A minimum wall thickness of 0.100 inch is...

CD70 encoded by modified vaccinia virus Ankara enhances CD8 T-cell-dependent protective immunity in MHC class II-deficient mice.

PubMed

Bathke, Barbara; Pätzold, Juliane; Kassub, Ronny; Giessel, Raphael; Lämmermann, Kerstin; Hinterberger, Maria; Brinkmann, Kay; Chaplin, Paul; Suter, Mark; Hochrein, Hubertus; Lauterbach, Henning

2017-12-27

The immunological outcome of infections and vaccinations is largely determined during the initial first days in which antigen-presenting cells instruct T cells to expand and differentiate into effector and memory cells. Besides the essential stimulation of the T-cell receptor complex a plethora of co-stimulatory signals not only ensures a proper T-cell activation but also instils phenotypic and functional characteristics in the T cells appropriate to fight off the invading pathogen. The tumour necrosis factor receptor/ligand pair CD27/CD70 gained a lot of attention because of its key role in regulating T-cell activation, survival, differentiation and maintenance, especially in the course of viral infections and cancer. We sought to investigate the role of CD70 co-stimulation for immune responses induced by the vaccine vector modified vaccinia virus Ankara-Bavarian Nordic ® (MVA-BN ® ). Short-term blockade of CD70 diminished systemic CD8 T-cell effector and memory responses in mice. The dependence on CD70 became even more apparent in the lungs of MHC class II-deficient mice. Importantly, genetically encoded CD70 in MVA-BN ® not only increased CD8 T-cell responses in wild-type mice but also substituted for CD4 T-cell help. MHC class II-deficient mice that were immunized with recombinant MVA-CD70 were fully protected against a lethal virus infection, whereas MVA-BN ® -immunized mice failed to control the virus. These data are in line with CD70 playing an important role for vaccine-induced CD8 T-cell responses and prove the potency of integrating co-stimulatory molecules into the MVA-BN ® backbone. © 2017 The Authors. Immunology Published by John Wiley & Sons Ltd.

New Cu(TiBN x ) copper alloy films for industrial applications

NASA Astrophysics Data System (ADS)

Lin, Chon-Hsin

2016-06-01

In this study, I explore a new type of copper alloy, Cu(TiBN x ), films by cosputtering Cu and TiB within an Ar/N2 gas atmosphere on Si substrates. The films are then annealed for 1 h in a vacuum environment at temperatures up to 700 °C. The annealed films exhibit not only excellent thermal stability and low resistivity but also little leakage current and strong adhesion to the substrates while no Cu/Si interfacial interactions are apparent. Within a Sn/Cu(TiBN x )/Si structure at 200 °C, the new alloy exhibits a minute dissolution rate, which is lower than that of pure Cu by at least one order of magnitude. Furthermore, the new alloy’s consumption rate is comparable to that of Ni commonly used in solder joints. The new films appear suitable for some industrial applications, such as barrierless Si metallization and new wetting and diffusion barrier layers required in flip-chip solder joints.

Engineering of hydrogenated two-dimensional h-BN/C superlattices as electrostatic substrates.

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

Liu, Zhun; Zhong, Xiaoliang; Yan, Hui

2016-01-14

Hybridized two-dimensional materials incorporating domains from the hexagonal boron nitride (h-BN) and graphene is an interesting branch of materials science due to their highly tunable electronic properties. In the present study, we investigate the hydrogenated two-dimensional (2D) h-BN/C superlattices (SLs) with zigzag edges using first-principles calculations. We found that the domain width, the phase ratio, and the vertical dipole orientation all have significant influence on the stability of SLs. The electronic reconstruction is associated with the lateral polar discontinuities at the zigzag edges and the vertically polarized (B2N2H4)(m) domains, which modifies the electronic structures and the spatial potential of themore » SLs significantly. Furthermore, we demonstrate that the hydrogenated 2D h-BN/C SLs can be applied in engineering the electronic structure of graphene: laterally-varying doping can be achieved by taking advantage of the spatial variation of the surface potential of the SLs. By applying an external vertical electric field on these novel bidirectional heterostructures, graphene doping levels and band offsets can be tuned to a wide range, such that the graphene doping profile can be switched from the bipolar (p-n junction) to unipolar (n(+)-n junction) mode. It is expected that such bidirectional heterostructures provide an effective approach for developing novel nanoscale electronic devices and improving our understanding of the fundamentals of low-dimensional materials.« less

Electronic structure, stability and magnetic properties of small M1-2Cr (M = Fe, Co, and Ni) alloy encapsulated inside a (BN)48 cage

NASA Astrophysics Data System (ADS)

Liang, Wenjuan; Jia, Jianfeng; Lv, Jin; Wu, Haishun

2015-09-01

The geometrical structure and magnetic properties of M1-2Cr (M = Fe, Co, and Ni) alloy clusters inside a (BN)48 cage were calculated at the BPW91/LANL2DZ level of theory. The doping with Cr significantly changed the magnetic properties of the transition-metal clusters. When M1-2Cr alloys were placed inside a (BN)48 cage, the alloy clusters interacted strongly with the cage, and the M1-2Cr@(BN)48 clusters showed high stability. Moreover, Cr-doped magnetic metal clusters preferably occupied positions off-center and near the hexagonal rings of (BN)48 cages. Thus, the (BN)48 cages can be used to increase the stability of M1-2Cr alloys, and retain their magnetic nature, except for CoCr and Ni2Cr clusters.

Nearly temperature-independent ultraviolet light emission intensity of indirect excitons in hexagonal BN microcrystals

NASA Astrophysics Data System (ADS)

Chichibu, Shigefusa F.; Ishikawa, Youichi; Kominami, Hiroko; Hara, Kazuhiko

2018-02-01

The radiative performance of hexagonal boron nitride (h-BN) was assessed by the spatio-time-resolved luminescence measurements on its microcrystals (MCs) annealed in an O2 gas ambient. The MCs exhibited distinct deep ultraviolet luminescence peaks higher than 5.7 eV, although h-BN is an indirect bandgap semiconductor. The result indicates a strong interaction between the indirect excitons (iXs) and LO/TO (and LA/TA) phonons at T points of the Brillouin zone. Such phonon replicas of free iXs and a luminescence band at 4.0 eV showed negligible thermal quenching, most probably assisted by the strong excitonic effect, enhanced phonon scattering, and formation of a surface BxOy layer that prevents excitons from surface recombination by the thermal excitation. Conversely, the luminescence band between 5.1 and 5.7 eV, which seems to consist of LO/TO phonon replicas of iXs localized at a certain structural singularity that are further scattered by multiple TO phonons at K points and another two emission peaks that originate from the singularity, showed the thermal quenching. In analogy with GaN and AlGaN, cation vacancy complexes most likely act as native nonradiative recombination centers (NRCs). In the present case, vacancy complexes that contain a boron vacancy (VB), such as divacancies with a nitrogen vacancy (VN), VBVN, are certain to act as NRCs. In this instance, iXs delocalized from the singularity are likely either captured by NRCs or the origin of the 4.0 eV-band; the latter is assigned to originate from a carbon on the N site or a complex between VB and an oxygen on the N site.

Minority carrier lifetime and dark current measurements in mid-wavelength infrared InAs 0.91Sb 0.09 alloy nBn photodetectors

DOE PAGES

Olson, B. V.; Kim, J. K.; Kadlec, E. A.; ...

2015-11-03

Carrier lifetime and dark current measurements are reported for a mid-wavelength infrared InAs 0.91Sb 0.09 alloy nBn photodetector. Minority carrier lifetimes are measured using a non-contact time-resolved microwave technique on unprocessed portions of the nBn wafer and the Auger recombination Bloch function parameter is determined to be |F 1F 2|=0.292. Moreover, the measured lifetimes are also used to calculate the expected diffusion dark current of the nBn devices and are compared with the experimental dark current measured in processed photodetector pixels from the same wafer. As a result, excellent agreement is found between the two, highlighting the important relationship betweenmore » lifetimes and diffusion currents in nBn photodetectors.« less

Electronic structure, stability and magnetic properties of small M1-4(M = Fe, Co, Ni) clusters encapsulated inside a (BN)48 cage

NASA Astrophysics Data System (ADS)

Liang, Wenjuan; Jia, Jianfeng; Lv, Jin; Wu, Haishun

2015-02-01

The geometrical structure and magnetic properties of M1-4(M = Fe, Co and Ni) clusters within a (BN)48 cage were calculated at the BPW91/LanL2DZ level. The small M1-4 clusters generally prefer an off-centered position near the hexagonal rings in the (BN)48 cages. The (BN)48 cages can increase the stability of these small magnetic clusters while protecting the magnetic nature of M and M2 clusters.

BnLATE, a Cys2/His2-Type Zinc-Finger Protein, Enhances Silique Shattering Resistance by Negatively Regulating Lignin Accumulation in the Silique Walls of Brassica napus

PubMed Central

Tao, Zhangsheng; Huang, Yi; Zhang, Lida; Wang, Xinfa; Liu, Guihua; Wang, Hanzhong

2017-01-01

Silique shattering resistance is one of the most important agricultural traits in oil crop breeding. Seed shedding from siliques prior to and during harvest causes devastating losses in oilseed yield. Lignin biosynthesis in the silique walls is thought to affect silique-shattering resistance in oil crops. Here, we identified and characterized B. napus LATE FLOWERING (BnLATE), which encodes a Cys2/His2-type zinc-finger protein. Heterologous expression of BnLATE under the double enhanced CaMV 35S promoter (D35S) in wild-type Arabidopsis plants resulted in a marked decrease in lignification in the replum, valve layer (carpel) and dehiscence zone. pBnLATE::GUS activity was strong in the yellowing silique walls of transgenic lines. Furthermore, the expression pattern of BnLATE and the lignin content gradient in the silique walls at 48 days after pollination (DAP) of 73290, a B. napus silique shattering-resistant line, are similar to those in transgenic Arabidopsis lines expressing BnLATE. Transcriptome sequencing of the silique walls revealed that genes encoding peroxidases, which polymerize monolignols and lignin in the phenylpropanoid pathway, were down-regulated at least two-fold change in the D35S::BnLATE transgenic lines. pBnLATE::BnLATE transgenic lines were further used to identify the function of BnLATE, and the results showed that lignification in the carpel and dehiscence zone of yellowing silique also remarkably decreased compared with the wild-type control, the silique shattering-resistance and expression pattern of peroxidase genes are very similar to results with D35S::BnLATE. These results suggest that BnLATE is a negative regulator of lignin biosynthesis in the yellowing silique walls, and promotes silique-shattering resistance in B. napus through restraining the polymerization of monolignols and lignin. PMID:28081140

High-performance polyimide nanocomposites with core-shell AgNWs@BN for electronic packagings

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

Zhou, Yongcun; Liu, Feng, E-mail: liufeng@nwpu.edu.cn

2016-08-22

The increasing density of electronic devices underscores the need for efficient thermal management. Silver nanowires (AgNWs), as one-dimensional nanostructures, possess a high aspect ratio and intrinsic thermal conductivity. However, high electrical conductivity of AgNWs limits their application for electronic packaging. We synthesized boron nitride-coated silver nanowires (AgNWs@BN) using a flexible and fast method followed by incorporation into synthetic polyimide (PI) for enhanced thermal conductivity and dielectric properties of nanocomposites. The thinner boron nitride intermediate nanolayer on AgNWs not only alleviated the mismatch between AgNWs and PI but also enhanced their interfacial interaction. Hence, the maximum thermal conductivity of an AgNWs@BN/PImore » composite with a filler loading up to 20% volume was increased to 4.33 W/m K, which is an enhancement by nearly 23.3 times compared with that of the PI matrix. The relative permittivity and dielectric loss were about 9.89 and 0.015 at 1 MHz, respectively. Compared with AgNWs@SiO{sub 2}/PI and Ag@BN/PI composites, boron nitride-coated core-shell structures effectively increased the thermal conductivity and reduced the permittivity of nanocomposites. The relative mechanism was studied and discussed. This study enables the identification of appropriate modifier fillers for polymer matrix nanocomposites.« less

Cerebellar transcranial direct current stimulation interacts with BDNF Val66Met in motor learning.

PubMed

van der Vliet, Rick; Jonker, Zeb D; Louwen, Suzanne C; Heuvelman, Marco; de Vreede, Linda; Ribbers, Gerard M; De Zeeuw, Chris I; Donchin, Opher; Selles, Ruud W; van der Geest, Jos N; Frens, Maarten A

2018-04-11

Cerebellar transcranial direct current stimulation has been reported to enhance motor associative learning and motor adaptation, holding promise for clinical application in patients with movement disorders. However, behavioral benefits from cerebellar tDCS have been inconsistent. Identifying determinants of treatment success is necessary. BDNF Val66Met is a candidate determinant, because the polymorphism is associated with motor skill learning and BDNF is thought to mediate tDCS effects. We undertook two cerebellar tDCS studies in subjects genotyped for BDNF Val66Met. Subjects performed an eyeblink conditioning task and received sham, anodal or cathodal tDCS (N = 117, between-subjects design) or a vestibulo-ocular reflex adaptation task and received sham and anodal tDCS (N = 51 subjects, within-subjects design). Performance was quantified as a learning parameter from 0 to 100%. We investigated (1) the distribution of the learning parameter with mixture modeling presented as the mean (M), standard deviation (S) and proportion (P) of the groups, and (2) the role of BDNF Val66Met and cerebellar tDCS using linear regression presented as the regression coefficients (B) and odds ratios (OR) with equally-tailed intervals (ETIs). For the eyeblink conditioning task, we found distinct groups of learners (M Learner  = 67.2%; S Learner  = 14.7%; P Learner  = 61.6%) and non-learners (M Non-learner  = 14.2%; S Non-learner  = 8.0%; P Non-learner  = 38.4%). Carriers of the BDNF Val66Met polymorphism were more likely to be learners (OR = 2.7 [1.2 6.2]). Within the group of learners, anodal tDCS supported eyeblink conditioning in BDNF Val66Met non-carriers (B = 11.9% 95%ETI = [0.8 23.0]%), but not in carriers (B = 1.0% 95%ETI = [-10.2 12.1]%). For the vestibulo-ocular reflex adaptation task, we found no effect of BDNF Val66Met (B = -2.0% 95%ETI = [-8.7 4.7]%) or anodal tDCS in either carriers (B = 3.4% 95%ETI = [-3

Rapid degradation of azo dye Direct Black BN by magnetic MgFe2O4-SiC under microwave radiation

NASA Astrophysics Data System (ADS)

Gao, Jia; Yang, Shaogui; Li, Na; Meng, Lingjun; Wang, Fei; He, Huan; Sun, Cheng

2016-08-01

A novel microwave (MW) catalyst, MgFe2O4 loaded on SiC (MgFe2O4-SiC), was successfully synthesized by sol-gel method, and pure MgFe2O4 was used as reference. The MgFe2O4 and MgFe2O4-SiC catalysts were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), N2 adsorption analyzer (BET specific surface area), X-ray photoelectron spectroscopy (XPS). The electromagnetic parameters of the prepared catalysts were measured by vector network analyzer. The reflection loss (RL) based on the electromagnetic parameters calculated in Matlab showed MgFe2O4-SiC attained the maximum absorbing value of 13.32 dB at 2.57 GHz, which reached extremely high RL value at low frequency range, revealing the excellent MW absorption property of MgFe2O4-SiC. MW-induced degradation of Direct Black BN (DB BN) over as-synthesized MgFe2O4-SiC indicated that degradation efficiency of DB BN (20 mg L-1) in 5 min reached 96.5%, the corresponding TOC removal was 65%, and the toxicity of DB BN after degradation by MgFe2O4-SiC obviously decreased. The good stability and applicability of MgFe2O4-SiC on the degradation process were also discovered. Moreover, the ionic chromatogram during degradation of DB BN demonstrated that the C-S, C-N and azo bonds in the DB BN molecule were destroyed gradually. MW-induced rad OH and holes could be responsible for the efficient removal involved in the system. These findings make MgFe2O4-SiC become an excellent MW absorbent as well as an effective MW catalyst with rapid degradation of DB BN. Therefore, it may be promising for MgFe2O4-SiC under MW radiation to deal with various dyestuffs and other toxic organic pollutants.

Mid-IR Imaging of Orion BN/KL: Modeling of Physical Conditions and Energy Balance

NASA Astrophysics Data System (ADS)

Gezari, Daniel; Varosi, Frank; Dwek, Eli; Danchi, William; Tan, Jonathan; Okumura, Shin-Ichiro

We have modeled two mid-infrared imaging photometry data sets to determine the spatial distribution of physical conditions in the BN/KL infrared complex. We observed the BN/KL region using the 10-m Keck I telescope and the LWS in the direct imaging mode, over a 13'' × 19'' field (Figure 1, left). We also modeled images obtained with COMICS (Kataza et al. 2000) at the 8.2-m SUBARU telescope, over a total field of view is 31'' × 41'' (Figure 1, right), in a total of nine bands: 7.8, 8.8, 9.7, 10.5, 11.7, 12.4, 18.5, 20.8 and 24.8 μm with ~1 μm bandwidth interference filters.

ZnO quantum dot-doped graphene/h-BN/GaN-heterostructure ultraviolet photodetector with extremely high responsivity

NASA Astrophysics Data System (ADS)

Lu, Yanghua; Wu, Zhiqian; Xu, Wenli; Lin, Shisheng

2016-12-01

A ZnO quantum dot photo-doped graphene/h-BN/GaN-heterostructure ultraviolet photodetector with extremely high responsivity of more than 1915 A W-1 and detectivity of more than 1.02 × 1013 Jones (Jones = cm Hz1/2 W-1) has been demonstrated. The interfaced h-BN layer increases the barrier height at the graphene/GaN heterojunction, which decreases the dark current and improves the on/off current ratio of the device. The photo-doping effect increases the barrier height and carrier concentration at the graphene/h-BN/GaN heterojunction, thus the responsivity is improved from 1473 A W-1 to 1915 A W-1 and the detectivity is improved from 5.8 × 1012 to 1.0 × 1013 Jones. Moreover, all of the responsivity and detectivity values are the highest values among all the graphene-based ultraviolet photodetectors.

Molecular Dynamics implementation of BN2D or 'Mercedes Benz' water model

NASA Astrophysics Data System (ADS)

Scukins, Arturs; Bardik, Vitaliy; Pavlov, Evgen; Nerukh, Dmitry

2015-05-01

Two-dimensional 'Mercedes Benz' (MB) or BN2D water model (Naim, 1971) is implemented in Molecular Dynamics. It is known that the MB model can capture abnormal properties of real water (high heat capacity, minima of pressure and isothermal compressibility, negative thermal expansion coefficient) (Silverstein et al., 1998). In this work formulas for calculating the thermodynamic, structural and dynamic properties in microcanonical (NVE) and isothermal-isobaric (NPT) ensembles for the model from Molecular Dynamics simulation are derived and verified against known Monte Carlo results. The convergence of the thermodynamic properties and the system's numerical stability are investigated. The results qualitatively reproduce the peculiarities of real water making the model a visually convenient tool that also requires less computational resources, thus allowing simulations of large (hydrodynamic scale) molecular systems. We provide the open source code written in C/C++ for the BN2D water model implementation using Molecular Dynamics.

Costs of shutting down nuclear reactors to hit €79bn

NASA Astrophysics Data System (ADS)

Stafford, Ned

2012-09-01

The decision by the German government last year to phase out all of the country's 17 nuclear power plants by 2022 could cost the nation up to €79bn, according to a new study by the Nuclear Energy Agency (NEA), which is part of the Organisation for Economic Co-operation and Development.

Exploring the effect of oxygen coverage on the electronic, magnetic and chemical properties of Ni(111) supported h-BN sheet: A density functional study

NASA Astrophysics Data System (ADS)

Wasey, A. H. M. Abdul; Das, G. P.; Majumder, C.

2017-05-01

Traditionally, h-BN is used as coating material to prevent corrosion on the metal surface. In sharp contrast to this, here we show catalytic behavior of h-BN monolayer deposited on Ni(111) surface, clearly demonstrating the influence of the support in modulation of h-BN electronic structure. Using first principles density functional theory we have studied the interaction of O2 molecules with the h-BN/Ni(111) surface. The activation of Osbnd O bond, which is the most important step for oxidative catalysis, showed dependence on the O2 coverage. Thus this study is extremely important to predict the optimum O2 pressure in reaction chamber for efficient catalysis.

BDNF-Val66Met-Polymorphism Impact on Cortical Plasticity in Schizophrenia Patients: A Proof-of-Concept Study

PubMed Central

Nitsche, Michael A.; Wobrock, Thomas; Bunse, Tilmann; Rein, Bettina; Herrmann, Maximiliane; Schmitt, Andrea; Nieratschker, Vanessa; Witt, Stephanie H.; Rietschel, Marcella; Falkai, Peter; Hasan, Alkomiet

2015-01-01

Background: Brain-derived neurotrophic factor (BDNF) has been shown to be a moderator of neuroplasticity. A frequent BDNF-polymorphism (Val66Met) is associated with impairments of cortical plasticity. In patients with schizophrenia, reduced neuroplastic responses following non-invasive brain stimulation have been reported consistently. Various studies have indicated a relationship between the BDNF-Val66Met-polymorphism and motor-cortical plasticity in healthy individuals, but schizophrenia patients have yet to be investigated. The aim of this proof-of-concept study was, therefore, to test the impact of the BDNF-Val66Met-polymorphism on inhibitory and facilitatory cortical plasticity in schizophrenia patients. Methods: Cortical plasticity was investigated in 22 schizophrenia patients and 35 healthy controls using anodal and cathodal transcranial direct-current stimulation (tDCS) applied to the left primary motor cortex. Animal and human research indicates that excitability shifts following anodal and cathodal tDCS are related to molecular long-term potentiation and long-term depression. To test motor-cortical excitability before and after tDCS, well-established single- and paired-pulse transcranial magnetic stimulation protocols were applied. Results: Our analysis revealed increased glutamate-mediated intracortical facilitation in met-heterozygotes compared to val-homozygotes at baseline. Following cathodal tDCS, schizophrenia met-heterozygotes had reduced gamma-amino-butyric-acid-mediated short-interval intracortical inhibition, whereas healthy met-heterozygotes displayed the opposite effect. The BDNF-Val66Met-polymorphism did not influence single-pulse motor-evoked potential amplitudes after tDCS. Conclusions: These preliminary findings support the notion of an association of the BDNF-Val66Met-polymorphism with observable alterations in plasticity following cathodal tDCS in schizophrenia patients. This indicates a complex interaction between inhibitory

First Science Observations with SOFIA/FORCAST: 6-37 μm Imaging of Orion BN/KL

NASA Astrophysics Data System (ADS)

De Buizer, James M.; Morris, Mark R.; Becklin, E. E.; Zinnecker, Hans; Herter, Terry L.; Adams, Joseph D.; Shuping, Ralph Y.; Vacca, William D.

2012-04-01

The Becklin-Neugebauer/Kleinmann-Low (BN/KL) region of the Orion Nebula is the nearest region of high-mass star formation in our galaxy. As such, it has been the subject of intense investigation at a variety of wavelengths, which have revealed it to be brightest in the infrared to submillimeter wavelength regime. Using the newly commissioned SOFIA airborne telescope and its 5-40 μm camera FORCAST, images of the entire BN/KL complex have been acquired. The 31.5 and 37.1 μm images represent the highest resolution observations (lsim4'') ever obtained of this region at these wavelengths. These observations reveal that the BN object is not the dominant brightness source in the complex at wavelengths >= 31.5 μm and that this distinction goes instead to the source IRc4. It was determined from these images and derived dust color temperature maps that IRc4 is also likely to be self-luminous. A new source of emission has also been identified at wavelengths >= 31.5 μm that coincides with the northeastern outflow lobe from the protostellar disk associated with radio source I.

Solution properties and spectroscopic characterization of polymeric precursors to SiNCB and BN ceramic materials

NASA Astrophysics Data System (ADS)

Cortez, E.; Remsen, E.; Chlanda, V.; Wideman, T.; Zank, G.; Carrol, P.; Sneddon, L.

1998-06-01

Boron Nitride, BN, and composite SiNCB ceramic fibers are important structural materials because of their excellent thermal and oxidative stabilities. Consequently, polymeric materials as precursors to ceramic composites are receiving increasing attention. Characterization of these materials requires the ability to evaluate simultaneous molecular weight and compositional heterogeneity within the polymer. Size exclusion chromatography equipped with viscometric and refractive index detection as well as coupled to a LC-transform device for infrared absorption analysis has been employed to examine these heterogeneities. Using these combined approaches, the solution properties and the relative amounts of individual functional groups distributed through the molecular weight distribution of SiNCB and BN polymeric precursors were characterized.

ZnO quantum dot-doped graphene/h-BN/GaN-heterostructure ultraviolet photodetector with extremely high responsivity.

PubMed

Lu, Yanghua; Wu, Zhiqian; Xu, Wenli; Lin, Shisheng

2016-12-02

A ZnO quantum dot  photo-doped graphene/h-BN/GaN-heterostructure ultraviolet photodetector with extremely high responsivity of more than 1915 A W -1 and detectivity of more than 1.02 × 10 13 Jones (Jones = cm Hz 1/2 W -1 ) has been demonstrated. The interfaced h-BN layer increases the barrier height at the graphene/GaN heterojunction, which decreases the dark current and improves the on/off current ratio of the device. The photo-doping effect increases the barrier height and carrier concentration at the graphene/h-BN/GaN heterojunction, thus the responsivity is improved from 1473 A W -1 to 1915 A W -1 and the detectivity is improved from 5.8 × 10 12 to 1.0 × 10 13 Jones. Moreover, all of the responsivity and detectivity values are the highest values among all the graphene-based ultraviolet photodetectors.

Characterisation of an Al-BN nanocomposite prepared by ball milling and hot extrusion

NASA Astrophysics Data System (ADS)

Arlic, U.; Drozd, Z.; Trojanová, Z.; Molnárová, O.; Kasakewitsch, A.

2017-07-01

Aluminium-matrix-nanocomposites were manufactured by ball milling of microscale aluminium powder with BN nanoparticles in air, followed by subsequent consolidation by hot extrusion. The microstructure of the samples was studied using scanning electron microscopy. Vickers microhardness measurements were used to probe the mechanical properties of the samples. The amplitude dependent damping of the nanocomposites was measured at room temperature after thermal treatment of samples, and the linear thermal expansion was measured over a wide temperature range from room temperature up to 670K in the as-extruded state. The experimental results give a comprehensive picture of the behaviour of this nanocomposite system over the range of thermomechanical treatment conditions examined in this study. Based on these experimental data some possible influences of BN nanoparticles on the anelastic, plastic and thermal properties of microcrystalline aluminium are discussed.

The concerted calculation of the BN-600 reactor for the deterministic and stochastic codes

NASA Astrophysics Data System (ADS)

Bogdanova, E. V.; Kuznetsov, A. N.

2017-01-01

The solution of the problem of increasing the safety of nuclear power plants implies the existence of complete and reliable information about the processes occurring in the core of a working reactor. Nowadays the Monte-Carlo method is the most general-purpose method used to calculate the neutron-physical characteristic of the reactor. But it is characterized by large time of calculation. Therefore, it may be useful to carry out coupled calculations with stochastic and deterministic codes. This article presents the results of research for possibility of combining stochastic and deterministic algorithms in calculation the reactor BN-600. This is only one part of the work, which was carried out in the framework of the graduation project at the NRC “Kurchatov Institute” in cooperation with S. S. Gorodkov and M. A. Kalugin. It is considering the 2-D layer of the BN-600 reactor core from the international benchmark test, published in the report IAEA-TECDOC-1623. Calculations of the reactor were performed with MCU code and then with a standard operative diffusion algorithm with constants taken from the Monte - Carlo computation. Macro cross-section, diffusion coefficients, the effective multiplication factor and the distribution of neutron flux and power were obtained in 15 energy groups. The reasonable agreement between stochastic and deterministic calculations of the BN-600 is observed.

Mapping PrBn and Other Quantitative Trait Loci Responsible for the Control of Homeologous Chromosome Pairing in Oilseed Rape (Brassica napus L.) Haploids

PubMed Central

Liu, Zhiqian; Adamczyk, Katarzyna; Manzanares-Dauleux, Maria; Eber, Frédérique; Lucas, Marie-Odile; Delourme, Régine; Chèvre, Anne Marie; Jenczewski, Eric

2006-01-01

In allopolyploid species, fair meiosis could be challenged by homeologous chromosome pairing and is usually achieved by the action of homeologous pairing suppressor genes. Oilseed rape (Brassica napus) haploids (AC, n = 19) represent an attractive model for studying the mechanisms used by allopolyploids to ensure the diploid-like meiotic pairing pattern. In oilseed rape haploids, homeologous chromosome pairing at metaphase I was found to be genetically based and controlled by a major gene, PrBn, segregating in a background of polygenic variation. In this study, we have mapped PrBn within a 10-cM interval on the C genome linkage group DY15 and shown that PrBn displays incomplete penetrance or variable expressivity. We have identified three to six minor QTL/BTL that have slight additive effects on the amount of pairing at metaphase I but do not interact with PrBn. We have also detected a number of other loci that interact epistatically, notably with PrBn. Our results support the idea that, as in other polyploid species, metaphase I homeologous pairing in oilseed rape haploids is controlled by an integrated system of several genes, which function in a complex manner. PMID:16951054

h-BN Nanosheets as 2D Substrates to Load 0D Fe3O4 Nanoparticles: A Hybrid Anode Material for Lithium-Ion Batteries.

PubMed

Duan, Zhi-Qiang; Liu, Yi-Tao; Xie, Xu-Ming; Ye, Xiong-Ying; Zhu, Xiao-Dong

2016-03-18

h-BN, as an isoelectronic analogue of graphene, has improved thermal mechanical properties. Moreover, the liquid-phase production of h-BN is greener since harmful oxidants/reductants are unnecessary. Here we report a novel hybrid architecture by employing h-BN nanosheets as 2D substrates to load 0D Fe3O4 nanoparticles, followed by phenol/formol carbonization to form a carbon coating. The resulting carbon-encapsulated h-BN@Fe3O4 hybrid architecture exhibits synergistic interactions: 1) The h-BN nanosheets act as flexible 2D substrates to accommodate the volume change of the Fe3O4 nanoparticles; 2) The Fe3O4 nanoparticles serve as active materials to contribute to a high specific capacity; and 3) The carbon coating not only protects the hybrid architecture from deformation but also keeps the whole electrode highly conductive. The synergistic interactions translate into significantly enhanced electrochemical performances, laying a basis for the development of superior hybrid anode materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multifunctional tunneling devices based on graphene/h-BN/MoSe2 van der Waals heterostructures

NASA Astrophysics Data System (ADS)

Cheng, Ruiqing; Wang, Feng; Yin, Lei; Xu, Kai; Ahmed Shifa, Tofik; Wen, Yao; Zhan, Xueying; Li, Jie; Jiang, Chao; Wang, Zhenxing; He, Jun

2017-04-01

The vertically stacked devices based on van der Waals heterostructures (vdWHs) of two-dimensional layered materials (2DLMs) have attracted considerable attention due to their superb properties. As a typical structure, graphene/hexagonal boron nitride (h-BN)/graphene vdWH has been proved possible to make tunneling devices. Compared with graphene, transition metal dichalcogenides possess intrinsic bandgap, leading to high performance of electronic devices. Here, tunneling devices based on graphene/h-BN/MoSe2 vdWHs are designed for multiple functions. On the one hand, the device shows a typical tunneling field-effect transistor behavior. A high on/off ratio of tunneling current (5 × 103) and an ultrahigh current rectification ratio (7 × 105) are achieved, which are attributed to relatively small electronic affinity of MoSe2 and optimized thickness of h-BN. On the other hand, the same structure also realizes 2D non-volatile memory with a high program/erase current ratio (>105), large memory window (˜150 V from ±90 V), and good retention characteristic. These results could enhance the fundamental understanding of tunneling behavior in vdWHs and contribute to the design of ultrathin rectifiers and memory based on 2DLMs.

Mid-IR Imaging of Orion BN/KL: Modeling of Physical Conditions and Energy Balance

NASA Technical Reports Server (NTRS)

Gezari, Daniel; Varosi, Frank; Dwek, Eli; Danchi, William C.; Tan, Jonathan; Okumura, Shin-ichiro

2016-01-01

We have modeled two mid-infrared imaging photometry data sets to determine the spatial distribution of physical conditions in the BN/KL (Becklin-Neugebauer / Kleinmann-Low) infrared complex. We observed the BN/KL region using the 10-meter Keck I telescope and the LWS (Living With a Star) in the direct imaging mode, over a 13 inch by 19 inch field . We also modeled images obtained with COMICS (Cooled Mid-Infrared Camera and Spectrometer, Kataza et al. 2000) at the 8.2-meter SUBARU telescope, over a total field of view [which] is 31 inches by 41 inches in a total of nine bands: 7.8, 8.8, 9.7, 10.5, 11.7, 12.4, 18.5, 20.8 and 24.8 microns with 1-micron bandwidth interference filters.

Reinforcement of nylon 6,6/nylon 6,6 grafted nanodiamond composites by in situ reactive extrusion.

PubMed

Choi, Eun-Yeob; Kim, Kiho; Kim, Chang-Keun; Kang, Eunah

2016-11-14

Nanodiamond (ND), an emerging new carbon material, was exploited to reinforce nylon 6,6 (PA66) polymer composites. Surface modified nanodiamonds with acyl chloride end groups were employed to chemically graft into PA66, enhancing the interfacial adhesion and thus the mechanical properties. The ND grafted PA66 (PA66-g-ND) reinforced PA66 composite prepared by in situ reactive extrusion exhibited increased tensile strength and modulus. The tensile strength and modulus of PA66/3 wt.% PA66-g-ND composites were enhanced by 11.6 and 20.8%, respectively when compared to those of the bare PA66 matrix. Even the PA66/pristine ND composites exhibited enhanced mechanical properties. The PA66-g-ND and the homogeneously dispersed PA66-g-ND in PA66 matrix were examined using X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy techniques. The mechanical properties and thermal conductivities of the nanodiamond incorporated PA66 composites were also explored. The enhanced mechanical properties and thermal conductivities of the PA66-g-ND/PA66 composites make them potential materials for new applications as functional engineered thermoplastics.

Reinforcement of nylon 6,6/nylon 6,6 grafted nanodiamond composites by in situ reactive extrusion

PubMed Central

Choi, Eun-Yeob; Kim, Kiho; Kim, Chang-Keun; Kang, Eunah

2016-01-01

Nanodiamond (ND), an emerging new carbon material, was exploited to reinforce nylon 6,6 (PA66) polymer composites. Surface modified nanodiamonds with acyl chloride end groups were employed to chemically graft into PA66, enhancing the interfacial adhesion and thus the mechanical properties. The ND grafted PA66 (PA66-g-ND) reinforced PA66 composite prepared by in situ reactive extrusion exhibited increased tensile strength and modulus. The tensile strength and modulus of PA66/3 wt.% PA66-g-ND composites were enhanced by 11.6 and 20.8%, respectively when compared to those of the bare PA66 matrix. Even the PA66/pristine ND composites exhibited enhanced mechanical properties. The PA66-g-ND and the homogeneously dispersed PA66-g-ND in PA66 matrix were examined using X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy techniques. The mechanical properties and thermal conductivities of the nanodiamond incorporated PA66 composites were also explored. The enhanced mechanical properties and thermal conductivities of the PA66-g-ND/PA66 composites make them potential materials for new applications as functional engineered thermoplastics. PMID:27841314

Reinforcement of nylon 6,6/nylon 6,6 grafted nanodiamond composites by in situ reactive extrusion

NASA Astrophysics Data System (ADS)

Choi, Eun-Yeob; Kim, Kiho; Kim, Chang-Keun; Kang, Eunah

2016-11-01

Nanodiamond (ND), an emerging new carbon material, was exploited to reinforce nylon 6,6 (PA66) polymer composites. Surface modified nanodiamonds with acyl chloride end groups were employed to chemically graft into PA66, enhancing the interfacial adhesion and thus the mechanical properties. The ND grafted PA66 (PA66-g-ND) reinforced PA66 composite prepared by in situ reactive extrusion exhibited increased tensile strength and modulus. The tensile strength and modulus of PA66/3 wt.% PA66-g-ND composites were enhanced by 11.6 and 20.8%, respectively when compared to those of the bare PA66 matrix. Even the PA66/pristine ND composites exhibited enhanced mechanical properties. The PA66-g-ND and the homogeneously dispersed PA66-g-ND in PA66 matrix were examined using X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy techniques. The mechanical properties and thermal conductivities of the nanodiamond incorporated PA66 composites were also explored. The enhanced mechanical properties and thermal conductivities of the PA66-g-ND/PA66 composites make them potential materials for new applications as functional engineered thermoplastics.

Mussel-inspired immobilization of BN nanosheets onto poly(p-phenylene benzobisoxazole) fibers: Multifunctional interface for photothermal self-healing

NASA Astrophysics Data System (ADS)

Shao, Qing; Hu, Zhen; Xu, Xirong; Yu, Long; Zhang, Dayu; Huang, Yudong

2018-05-01

The composites with interfacial self-healing ability are smart and promising materials in the future. Although some approaches have been used to heal the micro-cracks in composite materials, it is still a great challenge to develop a versatile strategy to fabricate multifunctional interface for self-healing. Here, boron nitride nanosheets (BN) are immobilized onto PBO fibers by facile polydopamine (PDA) chemistry. Benefiting from the photothermal effect of BN-PDA, the obtained surface layer displays interfacial self-healing properties under Xenon light irradiation.

Processing and Structural Advantages of the Sylramic-iBN SiC Fiber for SiC/SiC Components

NASA Technical Reports Server (NTRS)

Yun, H. M.; Dicarlo, J. A.; Bhatt, R. T.; Hurst, J. B.

2008-01-01

The successful high-temperature application of complex-shaped SiC/SiC components will depend on achieving as high a fraction of the as-produced fiber strength as possible during component fabrication and service. Key issues center on a variety of component architecture, processing, and service-related factors that can reduce fiber strength, such as fiber-fiber abrasion during architecture shaping, surface chemical attack during interphase deposition and service, and intrinsic flaw growth during high-temperature matrix formation and composite creep. The objective of this paper is to show that the NASA-developed Sylramic-iBN SiC fiber minimizes many of these issues for state-of-the-art melt-infiltrated (MI) SiC/BN/SiC composites. To accomplish this, data from various mechanical tests are presented that compare how different high performance SiC fiber types retain strength during formation of complex architectures, during processing of BN interphases and MI matrices, and during simulated composite service at high temperatures.

Bilayered graphene/h-BN with folded holes as new nanoelectronic materials: modeling of structures and electronic properties

PubMed Central

Chernozatonskii, Leonid A.; Demin, Viсtor A.; Bellucci, Stefano

2016-01-01

The latest achievements in 2-dimensional (2D) material research have shown the perspective use of sandwich structures in nanodevices. We demonstrate the following generation of bilayer materials for electronics and optoelectronics. The atomic structures, the stability and electronic properties of Moiré graphene (G)/h-BN bilayers with folded nanoholes have been investigated theoretically by ab-initio DFT method. These perforated bilayers with folded hole edges may present electronic properties different from the properties of both graphene and monolayer nanomesh structures. The closing of the edges is realized by C-B(N) bonds that form after folding the borders of the holes. Stable ≪round≫ and ≪triangle≫ holes organization are studied and compared with similar hole forms in single layer graphene. The electronic band structures of the considered G/BN nanomeshes reveal semiconducting or metallic characteristics depending on the sizes and edge terminations of the created holes. This investigation of the new types of G/BN nanostructures with folded edges might provide a directional guide for the future of this emerging area. PMID:27897237

Effect of Defects on III-V MWIR nBn Detector Performance

DTIC Science & Technology

2014-08-01

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS (ES) U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 infrared detectors ...rather than diffusion based processes. Keywords: infrared detectors , MWIR, nBn, photodiode, defects, irradiation, lattice mismatch, dark current...currents will increase noise in the detector , it is important to understand the impact elevated defect concentrations will have on barrier architecture

Hexagonal MoTe2 with Amorphous BN Passivation Layer for Improved Oxidation Resistance and Endurance of 2D Field Effect Transistors.

PubMed

Sirota, Benjamin; Glavin, Nicholas; Krylyuk, Sergiy; Davydov, Albert V; Voevodin, Andrey A

2018-06-06

Environmental and thermal stability of two-dimensional (2D) transition metal dichalcogenides (TMDs) remains a fundamental challenge towards enabling robust electronic devices. Few-layer 2H-MoTe 2 with an amorphous boron nitride (a-BN) covering layer was synthesized as a channel for back-gated field effect transistors (FET) and compared to uncovered MoTe 2 . A systematic approach was taken to understand the effects of heat treatment in air on the performance of FET devices. Atmospheric oxygen was shown to negatively affect uncoated MoTe 2 devices while BN-covered FETs showed considerably enhanced chemical and electronic characteristic stability. Uncapped MoTe 2 FET devices, which were heated in air for one minute, showed a polarity switch from n- to p-type at 150 °C, while BN-MoTe 2 devices switched only after 200 °C of heat treatment. Time-dependent experiments at 100 °C showed that uncapped MoTe 2 samples exhibited the polarity switch after 15 min of heat treatment while the BN-capped device maintained its n-type conductivity for the maximum 60 min duration of the experiment. X-ray photoelectron spectroscopy (XPS) analysis suggests that oxygen incorporation into MoTe 2 was the primary doping mechanism for the polarity switch. This work demonstrates the effectiveness of an a-BN capping layer in preserving few-layer MoTe 2 material quality and controlling its conductivity type at elevated temperatures in an atmospheric environment.

Modulating the spin transport behaviors in ZBNCNRs by edge hydrogenation and position of BN chain

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

Ouyang, Jun; Long, Mengqiu, E-mail: mqlong@csu.edu.cn, E-mail: ygao@csu.edu.cn; Zhang, Dan

2016-03-15

Using the density functional theory and the nonequilibrium Green’s function method, we study the spin transport behaviors in zigzag boron-nitrogen-carbon nanoribbons (ZBNCNRs) by modulating the edge hydrogenation and the position of B-N nanoribbons (BNNRs) chain. The different edge hydrogenations of the ZBNCNRs and the different position relationships of the BNNRs have been considered systematically. Our results show that the metallic, semimetallic and semiconductive properties of the ZBNCNRs can be modulated by the different edge hydrogenations and different position relationships of BN chains. And our proposaled ZBNCNRs devices act as perfect spin-filters with nearly 100% spin polarization. These effects would havemore » potential applications for boron-nitrogen-carbon-based nanomaterials in spintronics nano-devices.« less

2D Heterostructure coatings of hBN-MoS2 layers for corrosion resistance

NASA Astrophysics Data System (ADS)

Vandana, Sajith; Kochat, Vidya; Lee, Jonghoon; Varshney, Vikas; Yazdi, Sadegh; Shen, Jianfeng; Kosolwattana, Suppanat; Vinod, Soumya; Vajtai, Robert; Roy, Ajit K.; Sekhar Tiwary, Chandra; Ajayan, P. M.

2017-02-01

Heterostructures of atomically thin 2D materials could have improved physical, mechanical and chemical properties as compared to its individual components. Here we report, the effect of heterostructure coatings of hBN and MoS2 on the corrosion behavior as compared to coatings employing the individual 2D layer compositions. The poor corrosion resistance of MoS2 (widely used as wear resistant coating) can be improved by incorporating hBN sheets. Depending on the atomic stacking of the 2D sheets, we can further engineer the corrosion resistance properties of these coatings. A detailed spectroscopy and microscopy analysis has been used to characterize the different combinations of layered coatings. Detailed DFT based calculation reveals that the effect on the electrical properties due to atomic stacking is one of the major reasons for the improvement seen in corrosion resistance.

Nuclear and Physical Properties of Dielectrics under Neutron Irradiation in Fast (BN-600) and Fusion (DEMO-S) Reactors

NASA Astrophysics Data System (ADS)

Blokhin, D. A.; Chernov, V. M.; Blokhin, A. I.

2017-12-01

Nuclear and physical properties (activation and transmutation of elements) of BN and Al2O3 dielectric materials subjected to neutron irradiation for up to 5 years in Russian fast (BN-600) and fusion (DEMO-S) reactors were calculated using the ACDAM-2.0 software complex for different post-irradiation cooling times (up to 10 years). Analytical relations were derived for the calculated quantities. The results may be used in the analysis of properties of irradiated dielectric materials and may help establish the rules for safe handling of these materials.

Integrating AgI/AgBr biphasic heterostructures encased by few layer h-BN with enhanced catalytic activity and stability.

PubMed

Wu, Wen; Lv, Xiaomeng; Wang, Jiaxi; Xie, Jimin

2017-06-15

Using freshly prepared water-soluble KBr crystal as facile, low-cost sacrificial template, AgBr nanocubes were synthesized through one-pot precipitation method, then navy bean shaped AgI/AgBr biphasic heterostructures were synthesized through anion-exchange reaction and encased within few-layer h-BN to obtain final product. The obtained heterostructured AgI/AgBr/h-BN composite without plasmonic noble metal nanoparticles was used as stable and high active photocatalyst for dye degradation under visible light irradiation, comparing both with self-prepared normal AgBr, AgBr cubes, AgI/AgBr navy beans and other related catalysts reported in the literature. The significant boosting of activity was attributed to the formation of AgI/AgBr interface and the coupling of few-layer h-BN, the latter of which not only effectively suppresses the reduction of silver ions but greatly enhance the charge separation. Furthermore, it was suggested that the photogenerated holes and superoxide radical were the main active species according to photoelectron chemical measurements, electron spin resonance spin-trap analysis and radical trapping experiments. Finally, the possible mechanism of enhanced photocatalytic activity and stability was discussed and proposed. The work demonstrates that engineering Ag-based semiconductor coupling with h-BN would profit the design strategy for low-cost, solar-driven photocatalysts. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of the SiCl₄ Flow Rate on SiBN Deposition Kinetics in SiCl₄-BCl₃-NH₃-H₂-Ar Environment.

PubMed

Li, Jianping; Qin, Hailong; Liu, Yongsheng; Ye, Fang; Li, Zan; Cheng, Laifei; Zhang, Litong

2017-06-07

To improve the thermal and mechanical stability of SiC f /SiC or C/SiC composites with SiBN interphase, SiBN coating was deposited by low pressure chemical vapor deposition (LPCVD) using SiCl₄-BCl₃-NH₃-H₂-Ar gas system. The effect of the SiCl₄ flow rate on deposition kinetics was investigated. Results show that deposition rate increases at first and then decreases with the increase of the SiCl₄ flow rate. The surface of the coating is a uniform cauliflower-like structure at the SiCl₄ flow rate of 10 mL/min and 20 mL/min. The surface is covered with small spherical particles when the flow rate is 30 mL/min. The coatings deposited at various SiCl₄ flow rates are all X-ray amorphous and contain Si, B, N, and O elements. The main bonding states are B-N, Si-N, and N-O. B element and B-N bonding decrease with the increase of SiCl₄ flow rate, while Si element and Si-N bonding increase. The main deposition mechanism refers to two parallel reactions of BCl₃+NH₃ and SiCl₄+NH₃. The deposition process is mainly controlled by the reaction of BCl₃+NH₃.

42 CFR 66.202 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Definitions. 66.202 Section 66.202 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Institutional Grants § 66.202 Definitions. The definitions in § 66.102 of...

42 CFR 66.202 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Definitions. 66.202 Section 66.202 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Institutional Grants § 66.202 Definitions. The definitions in § 66.102 of...

42 CFR 66.202 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Definitions. 66.202 Section 66.202 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Institutional Grants § 66.202 Definitions. The definitions in § 66.102 of...

A Fractional Step Theta-Method for Viscoelastic Fluid Flow Using a UPG Approximation

DTIC Science & Technology

2007-10-01

dtu (n+1) − u(n+ 1 2) t ,v ) + ( θ̃σ(n+θ) + θσ(n+1) − σ(n+ 1 2),d(v) ) + 2α̃ ( θd(u(n+1)) + θ̃d(u(n+θ))− d ( u(n+ 1 2) ) ,d(v) ) , ∀ v ∈ Zh. (6.6...both sides (6.11) giving Bn5 (u,v) = ( f(n+ 1 2 −θ),v ) + ( p(n+ 1 2 −θ),∇ · v ) + In5 (v). (6.12) Here we define In5 (v) := Re ( dtu (n+θ̃) − u(n+ 1 2...Bn6 (u,v) to both sides of (6.18) we obtain: Bn6 (u,v) = ( f(n+θ− 1 2),v ) + ( p(n+θ− 1 2),∇ · v ) + In6 (v), ∀v ∈ Zh, (6.19) with In6 (v) := Re ( dtu

DFT STUDY OF CO AND NO ADSORPTION ON BORON NITRIDE (BN)n = 3 - 5 NANOCLUSTERS

NASA Astrophysics Data System (ADS)

Zahedi, Ehsan; Pangh, Abdolhakim; Ghorbanpour, Hamed

2015-11-01

Interaction of CO and NO molecules by different orientations on (BN)n=3-5 clusters have been studied at the B3LYP/6-311+G* level of theory. Total electronic energies have been corrected for geometrical counterpoise (gCP) and dispersion (D3) energies at the B3LYP/6-31G* level. Formation of a new sigma bond between the gas and (BN)3 cluster, atom in molecules (AIM) results, density of states spectrums (DOS), molecular electrostatic potential (MEP) surfaces, and visualization of wave function of molecular orbitals in the nearest bonding regions to the Fermi level have confirmed that adsorption of CO by carbon end atom, and NO by nitrogen end atom is covalent in nature, so that the charge transfer is occurred from gas molecule to the cluster.

Ab-initio study of structural and electronic properties of WS2/h-BN van der Waals heterostructure

NASA Astrophysics Data System (ADS)

Ghasemi majd, Zahra; Amiri, Peiman; Taghizadeh, Seyed Fardin

2018-06-01

First-principle calculations with different exchange-correlation functionals, including LDA, GGA, semi-empirical and ab-initio van der Waals in the forms of vdW-DF2B86R and vdW-DF2 were performed to evaluate the performance of different functionals in describing the bonding mechanism, adsorption energy and interlayer distance of WS2 monolayer on and between h-BN layers. The finding was that the vdW-DF2B86R seems to be the approach best lending itself to this purpose. In order to include the van der Waals (vdW) interactions in our calculations, we used the DFT-D2 and vdW methods, which gave rise to a physical adsorption with no net charge transfer between the WS2 layer and the corresponding substrates. In addition, we investigated the electronic and structural properties of WS2 and h-BN heterolayers, using vdW-DF2B86R functional. Based on density functional theory calculations, WS2 on and between h-BN layers showed a direct band gap at the K-point, which was experimentally observed.

42 CFR 66.205 - Requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Requirements. 66.205 Section 66.205 Public Health... NATIONAL RESEARCH SERVICE AWARDS Institutional Grants § 66.205 Requirements. (a) No Award shall be made to... the form and manner the Secretary may prescribe, that he or she will satisfy the requirements of § 66...

42 CFR 66.205 - Requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Requirements. 66.205 Section 66.205 Public Health... NATIONAL RESEARCH SERVICE AWARDS Institutional Grants § 66.205 Requirements. (a) No Award shall be made to... the form and manner the Secretary may prescribe, that he or she will satisfy the requirements of § 66...

Quantum interference on electron scattering in graphene by carbon impurities in underlying h -BN

NASA Astrophysics Data System (ADS)

Kaneko, Tomoaki; Koshino, Mikito; Saito, Riichiro

2017-03-01

Electronic structures and transport properties of graphene on h -BN with carbon impurities are investigated by first-principles calculation and the tight-binding model. We show that the coupling between the impurity level and the graphene's Dirac cone sensitively depends on the impurity position, and in particular, it nearly vanishes when the impurity is located right below the center of the six membered ring of graphene. The Bloch phase factor at the Brillouin zone edge plays a decisive role in the cancellation of the hopping integrals. The impurity position dependence on the electronic structures of graphene on h -BN is investigated by the first-principles calculation, and its qualitative feature is well explained by a tight-binding model with graphene and a single impurity site. We also propose a simple one-dimensional chain-impurity model to analytically describe the role of the quantum interference in the position-dependent coupling.

Linkage studies on 13 biochemical loci and 2 coat color loci in a [(BN x TM) x TM] backcross progeny of the rat (Rattus norvegicus).

PubMed

Yamada, J; Hamada, S; Bender, K; Adams, M

1986-10-01

In a [(BN X TM) X TM] backcross progeny of rats, nine significant linkage associations were found among 105 pairwise combinations of 15 loci. After comparing this with other published data and data of personal communications, we considered that the d gene we tentatively designated may be identical to the gene for pink-eyed dilution (p), and that the associations of Gc-Hbb, RT1-h, and Gc-Fh were due to chance rather than real linkage. The linkages obtained in this study, therefore, were Hbb-p (26.5 +/- 5.5) in LG I, Mup-1-Acon-1 (12.5 +/- 4.1) in LG II, Hao-1-Svp-1 (23.8 +/- 6.6) in LG IV, Es-1-Es-3 (17.2 +/- 4.7) in LG V, h-Gc (10.9 +/- 3.3) in LG VI, and Fh-Pep-3 (32.3 +/- 5.9) in LG X.

Reaction paths in the system Al 2O 3-hBN-Y

NASA Astrophysics Data System (ADS)

Reichert, K.; Oreshina, O.; Cremer, R.; Neuschütz, D.

2001-07-01

As part of the investigations on the suitability of a new concept for a tailored fiber-matrix interface in sapphire fiber reinforced NiAl matrix composites for application as a high-temperature structural material, the interfacial reactions in the system alumina-hexagonal boron nitride-yttrium (Al 2O 3-hBN-Y) have been examined in the temperature range of 1100-1300°C. For this, alumina substrates were coated with hBN by means of CVD and subsequently with sputter deposited yttrium. Afterwards the samples were annealed for up to 16 h under inert atmosphere. Grazing incidence X-ray diffraction (GIXRD) served to analyze the phases formed by diffusion processes in the reaction zone. The peak intensities in these diffraction patterns were used to evaluate the sequence of phases formed due to diffusion and reaction. After the initial formation of YN and YB 2, the phases Y 2O 3, Al 2Y, and YB 4 were observed. Even longer annealing times or higher temperatures, respectively, led to the formation of the ternary oxides YAlO 3 and Y 3Al 5O 12 as well as metallic aluminum.

Dynamical effects in x-ray absorption spectra of graphene and monolayered h -BN on Ni(111)

NASA Astrophysics Data System (ADS)

Rusz, J.; Preobrajenski, A. B.; Ng, May Ling; Vinogradov, N. A.; Mårtensson, N.; Wessely, O.; Sanyal, B.; Eriksson, O.

2010-02-01

We present first-principles calculations of x-ray absorption spectra of graphene and hexagonal BN monolayer on the Ni(111) substrate. Including dynamical core-hole screening effects according to the theory of Mahan-Nozières-de Dominics (MND) results in an overall good agreement with previously published experimental data and our new observations. This approach provides a unified first-principles description of the electronic structure and core excitations in the sp2 -bonded materials on metal surfaces and a better insight into the dynamics of screening effects. We demonstrate in particular that the observed spectral features of graphene and hexagonal BN can be well reproduced with the MND theory, and that they are determined by a delicate balance between initial and final-state effects.

Boride Formation Induced by pcBN Tool Wear in Friction-Stir-Welded Stainless Steels

NASA Astrophysics Data System (ADS)

Park, Seung Hwan C.; Sato, Yutaka S.; Kokawa, Hiroyuki; Okamoto, Kazutaka; Hirano, Satoshi; Inagaki, Masahisa

2009-03-01

The wear of polycrystalline cubic boron nitride (pcBN) tool and its effect on second phase formation were investigated in stainless steel friction-stir (FS) welds. The nitrogen content and the flow stress were analyzed in these welds to examine pcBN tool wear. The nitrogen content in stir zone (SZ) was found to be higher in the austenitic stainless steel FS welds than in the ferritic and duplex stainless steel welds. The flow stress of austenitic stainless steels was almost 1.5 times larger than that of ferritic and duplex stainless steels. These results suggest that the higher flow stress causes the severe tool wear in austenitic stainless steels, which results in greater nitrogen pickup in austenitic stainless steel FS welds. From the microstructural observation, a possibility was suggested that Cr-rich borides with a crystallographic structure of Cr2B and Cr5B3 formed through the reaction between the increased boron and nitrogen and the matrix during FS welding (FSW).

Approaching quantum anomalous Hall effect in proximity-coupled YIG/graphene/h-BN sandwich structure

NASA Astrophysics Data System (ADS)

Tang, Chi; Cheng, Bin; Aldosary, Mohammed; Wang, Zhiyong; Jiang, Zilong; Watanabe, K.; Taniguchi, T.; Bockrath, Marc; Shi, Jing

2018-02-01

Quantum anomalous Hall state is expected to emerge in Dirac electron systems such as graphene under both sufficiently strong exchange and spin-orbit interactions. In pristine graphene, neither interaction exists; however, both interactions can be acquired by coupling graphene to a magnetic insulator as revealed by the anomalous Hall effect. Here, we show enhanced magnetic proximity coupling by sandwiching graphene between a ferrimagnetic insulator yttrium iron garnet (YIG) and hexagonal-boron nitride (h-BN) which also serves as a top gate dielectric. By sweeping the top-gate voltage, we observe Fermi level-dependent anomalous Hall conductance. As the Dirac point is approached from both electron and hole sides, the anomalous Hall conductance reaches ¼ of the quantum anomalous Hall conductance 2e2/h. The exchange coupling strength is determined to be as high as 27 meV from the transition temperature of the induced magnetic phase. YIG/graphene/h-BN is an excellent heterostructure for demonstrating proximity-induced interactions in two-dimensional electron systems.

Comparison of B{sub 2}O{sub 3} and BN deposited by atomic layer deposition for forming ultrashallow dopant regions by solid state diffusion

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

Consiglio, Steven, E-mail: steve.consiglio@us.tel.com; Clark, Robert D.; O'Meara, David

2016-01-15

In this study, the authors investigated atomic layer deposition (ALD) of B{sub 2}O{sub 3} and BN for conformal, ultrashallow B doping applications and compared the effect of dopant-containing overlayers on sheet resistance (R{sub s}) and B profiles for both types of films subjected to a drive-in thermal anneal. For the deposition of B{sub 2}O{sub 3}, tris(dimethylamido)borane and O{sub 3} were used as coreactants and for the deposition of BN, BCl{sub 3} and NH{sub 3} were used as coreactants. Due to the extreme air instability of B{sub 2}O{sub 3} films, physical analysis was performed on B{sub 2}O{sub 3} films, which weremore » capped in-situ with ∼30 Å ALD grown Al{sub 2}O{sub 3} layers. For the BN films, in-situ ALD grown Si{sub 3}N{sub 4} capping layers (∼30 Å) were used for comparison. From spectroscopic ellipsometry, a thickness decrease was observed after 1000 °C, 30 s anneal for the B{sub 2}O{sub 3} containing stack with 60 ALD cycles of B{sub 2}O{sub 3}, whereas the BN containing stacks showed negligible thickness decrease after the annealing step, regardless of the number of BN cycles tested. The postanneal reduction in film thickness as well as decrease in R{sub s} for the B{sub 2}O{sub 3} containing stack suggests that the solid state diffusion dopant mechanism is effective, whereas for the BN containing stacks this phenomenon seems to be suppressed. Further clarification of the effectiveness of the B{sub 2}O{sub 3} containing layer compared to the film stacks with BN was evidenced in backside secondary ion mass spectrometry profiling of B atoms. Thus, B{sub 2}O{sub 3} formed by an ALD process and subsequently capped in-situ followed by a drive-in anneal offers promise as a dopant source for ultrashallow doping, whereas the same method using BN seems ineffective. An integrated approach for B{sub 2}O{sub 3} deposition and annealing on a clustered tool also demonstrated controllable R{sub s} reduction without the use of a capping layer.« less

Improvement of Ion/Ioff for h-BN encapsulated bilayer graphene by graphite local back gate electrode

NASA Astrophysics Data System (ADS)

Uwanno, Teerayut; Taniguchi, Takashi; Watanabe, Kenji; Nagashio, Kosuke

The critical issue for bilayer graphene (BLG) devices is low Ion/Ioff even at the band gap of 0.3eV. Band gap in BLG can be formed by creating potential difference between the two layers of BLG. This can be done by applying external electric field perpendicularly to BLG to induce different carrier densities in the two layers. Due to such origin, the spatial uniformity of band gap in the channel is quite sensitive to charge inhomogeneity in BLG. In order to apply electric field of 3V/nm to open the maximum band gap of 0.3eV, high- k gate stack has been utilized so far. However, oxide dielectrics usually have large charge inhomogeneity causing in-plane potential fluctuation in BLG channel. Due to surface flatness and small charge inhomogeneity, h-BN has been used as dielectrics to achieve high quality graphene devices, however, Ion/Iofffor BLG/ h-BN heterostuctures has not been reported yet. In this study, we used graphite as local back gate electrode to BLG encapsulated with h-BN. This resulted in much higher Ion/Ioff, indicating the importance of screening of charge inhomogeneity from SiO2 substrate surface by local graphite back gate electrode. This research was partly supported by JSPS Core-to-Core Program, A. Advanced Research Networks.

The Mass1frings mutation underlies early onset hearing impairment in BUB/BnJ mice, a model for the auditory pathology of Usher syndrome IIC

PubMed Central

Johnson, K.R.; Zheng, Q.Y.; Weston, M.D.; Ptacek, L.J.; Noben-Trauth, K.

2010-01-01

The human ortholog of the gene responsible for audiogenic seizure susceptibility in Frings and BUB/BnJ mice (mouse gene symbol Mass1) recently was shown to underlie Usher syndrome type IIC (USH2C). Here we report that the Mass1frings mutation is responsible for the early onset hearing impairment of BUB/BnJ mice. We found highly significant linkage of Mass1 with ABR threshold variation among mice from two backcrosses involving BUB/BnJ mice with mice of strains CAST/EiJ and MOLD/RkJ. We also show an additive effect of the Cdh23 locus in modulating the progression of hearing loss in backcross mice. Together, these two loci account for more than 70% of the total ABR threshold variation among the backcross mice at all ages. The modifying effect of the strain-specific Cdh23ahl variant may account for the hearing and audiogenic seizure differences observed between Frings and BUB/BnJ mice, which share the Mass1frings mutation. During postnatal cochlear development in BUB/BnJ mice, stereocilia bundles develop abnormally and remain immature and splayed into adulthood, corresponding with the early onset hearing impairment associated with Mass1frings. Progressive base–apex hair cell degeneration occurs at older ages, corresponding with the age-related hearing loss associated with Cdh23ahl. The molecular basis and pathophysiology of hearing loss suggest BUB/BnJ and Frings mice as models to study cellular and molecular mechanisms underlying USH2C auditory pathology. PMID:15820310

Auger electron spectroscopy, secondary ion mass spectroscopy and optical characterization of a-C-H and BN films

NASA Technical Reports Server (NTRS)

Pouch, J. J.; Alterovitz, S. A.; Warner, J. D.

1986-01-01

The amorphous dielectrics a-C:H and BN were deposited on III-V semiconductors. Optical band gaps as high as 3 eV were measured for a-C:H generated by C4H10 plasmas; a comparison was made with bad gaps obtained from films prepared by CH4 glow discharges. The ion beam deposited BN films exhibited amorphous behavior with band gaps on the order of 5 eV. Film compositions were studied by Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The optical properties were characterized by ellipsometry, UV/VIS absorption, and IR reflection and transmission. Etching rates of a-C:H subjected to O2 dicharges were determined.

A Tourist-like MITE insertion in the upstream region of the BnFLC.A10 gene is associated with vernalization requirement in rapeseed (Brassica napus L.).

PubMed

Hou, Jinna; Long, Yan; Raman, Harsh; Zou, Xiaoxiao; Wang, Jing; Dai, Shutao; Xiao, Qinqin; Li, Cong; Fan, Longjiang; Liu, Bin; Meng, Jinling

2012-12-15

Rapeseed (Brassica napus L.) has spring and winter genotypes adapted to different growing seasons. Winter genotypes do not flower before the onset of winter, thus leading to a longer vegetative growth period that promotes the accumulation and allocation of more resources to seed production. The development of winter genotypes enabled the rapeseed to spread rapidly from southern to northern Europe and other temperate regions of the world. The molecular basis underlying the evolutionary transition from spring- to winter- type rapeseed is not known, however, and needs to be elucidated. We fine-mapped the spring environment specific quantitative trait locus (QTL) for flowering time, qFT10-4,in a doubled haploid (DH) mapping population of rapeseed derived from a cross between Tapidor (winter-type) and Ningyou7 (semi-winter) and delimited the qFT10-4 to an 80-kb region on chromosome A10 of B. napus. The BnFLC.A10 gene, an ortholog of FLOWERING LOCUS C (FLC) in Arabidopsis, was cloned from the QTL. We identified 12 polymorphic sites between BnFLC.A10 parental alleles of the TN-DH population in the upstream region and in intron 1. Expression of both BnFLC.A10 alleles decreased during vernalization, but decreased more slowly in the winter parent Tapidor. Haplotyping and association analysis showed that one of the polymorphic sites upstream of BnFLC.A10 is strongly associated with the vernalization requirement of rapeseed (r2 = 0.93, χ2 = 0.50). This polymorphic site is derived from a Tourist-like miniature inverted-repeat transposable element (MITE) insertion/deletion in the upstream region of BnFLC.A10. The MITE sequence was not present in the BnFLC.A10 gene in spring-type rapeseed, nor in ancestral 'A' genome species B. rapa genotypes. Our results suggest that the insertion may have occurred in winter rapeseed after B. napus speciation. Our findings strongly suggest that (i) BnFLC.A10 is the gene underlying qFT10-4, the QTL for phenotypic diversity of flowering time in

The direct exchange mechanism of induced spin polarization of low-dimensional π-conjugated carbon- and h-BN fragments at LSMO(001) MnO-terminated interfaces

NASA Astrophysics Data System (ADS)

Kuklin, Artem V.; Kuzubov, Alexander A.; Kovaleva, Evgenia A.; Lee, Hyosun; Sorokin, Pavel B.; Sakai, Seiji; Entani, Shiro; Naramoto, Hiroshi; Avramov, Paul

2017-10-01

Induced spin polarization of π-conjugated carbon and h-BN low dimensional fragments at the interfaces formed by deposition of pentacene molecule and narrow zigzag graphene and h-BN nanoribbons on MnO2-terminated LSMO(001) thin film was studied using GGA PBE+U PAW D3-corrected approach. Induced spin polarization of π-conjugated low-dimensional fragments is caused by direct exchange with Mn ions of LSMO(001) MnO-derived surface. Due to direct exchange, the pentacene molecule changes its diamagnetic narrow-band gap semiconducting nature to the ferromagnetic semiconducting state with 0.15 eV energy shift between spin-up and spin-down valence bands and total magnetic moment of 0.11 μB. Direct exchange converts graphene nanoribbon to 100% spin-polarized half-metal with large amplitude of spin-up electronic density at the Fermi level. The direct exchange narrows the h-BN nanoribbon band gap from 4.04 to 1.72 eV in spin-up channel and converts the h-BN ribbon semiconducting diamagnetic nature to a semiconducting magnetic one. The electronic structure calculations demonstrate a possibility to control the spin properties of low-dimensional π-conjugated carbon and h-BN fragments by direct exchange with MnO-derived LSMO(001) surface for spin-related applications.

Spin filter effect of hBN/Co detector electrodes in a 3D topological insulator spin valve

NASA Astrophysics Data System (ADS)

Vaklinova, Kristina; Polyudov, Katharina; Burghard, Marko; Kern, Klaus

2018-03-01

Topological insulators emerge as promising components of spintronic devices, in particular for applications where all-electrical spin control is essential. While the capability of these materials to generate spin-polarized currents is well established, only very little is known about the spin injection/extraction into/out of them. Here, we explore the switching behavior of lateral spin valves comprising the 3D topological insulator Bi2Te2Se as channel, which is separated from ferromagnetic Cobalt detector contacts by an ultrathin hexagonal boron nitride (hBN) tunnel barrier. The corresponding contact resistance displays a notable variation, which is correlated with a change of the switching characteristics of the spin valve. For contact resistances below ~5 kΩ, the hysteresis in the switching curve reverses upon reversing the applied current, as expected for spin-polarized currents carried by the helical surface states. By contrast, for higher contact resistances an opposite polarity of the hysteresis loop is observed, which is independent of the current direction, a behavior signifying negative spin detection efficiency of the multilayer hBN/Co contacts combined with bias-induced spin signal inversion. Our findings suggest the possibility to tune the spin exchange across the interface between a ferromagnetic metal and a topological insulator through the number of intervening hBN layers.

How Germinal Centers Evolve Broadly Neutralizing Antibodies: the Breadth of the Follicular Helper T Cell Response

DOE PAGES

De Boer, Rob J.; Perelson, Alan S.

2017-09-06

Many HIV-1-infected patients evolve broadly neutralizing antibodies (bnAbs). This evolutionary process typically takes several years and is poorly understood as selection taking place in germinal centers occurs on the basis of antibody affinity. B cells with the highest-affinity receptors tend to acquire the most antigen from the follicular dendritic cell (FDC) network and present the highest density of cognate peptides to follicular helper T (Tfh) cells, which provide survival signals to the B cell. bnAbs are therefore expected to evolve only when the B cell lineage evolving breadth is consistently capturing and presenting more peptides to Tfh cells than othermore » lineages of more specific B cells. Here we develop mathematical models of Tfh cells in germinal centers to explicitly define the mechanisms of selection in this complex evolutionary process. Our results suggest that broadly reactive B cells presenting a high density of peptides bound to major histocompatibility complex class II molecules (pMHC) are readily outcompeted by B cells responding to lineages of HIV-1 that transiently dominate the within host viral population. Conversely, if broadly reactive B cells acquire a large variety of several HIV-1 proteins from the FDC network and present a high diversity of several pMHC, they can be rescued by a large fraction of the Tfh cell repertoire in the germinal center. Under such circumstances the evolution of bnAbs is much more consistent. Increasing either the magnitude of the Tfh cell response or the breadth of the Tfh cell repertoire markedly facilitates the evolution of bnAbs. Because both the magnitude and breadth can be increased by vaccination with several HIV-1 proteins, this calls for experimental testing. Many HIV-infected patients slowly evolve antibodies that can neutralize a large variety of viruses. Such broadly neutralizing antibodies (bnAbs) could in the future become therapeutic agents. bnAbs appear very late, and patients are typically

How Germinal Centers Evolve Broadly Neutralizing Antibodies: the Breadth of the Follicular Helper T Cell Response

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

De Boer, Rob J.; Perelson, Alan S.

Many HIV-1-infected patients evolve broadly neutralizing antibodies (bnAbs). This evolutionary process typically takes several years and is poorly understood as selection taking place in germinal centers occurs on the basis of antibody affinity. B cells with the highest-affinity receptors tend to acquire the most antigen from the follicular dendritic cell (FDC) network and present the highest density of cognate peptides to follicular helper T (Tfh) cells, which provide survival signals to the B cell. bnAbs are therefore expected to evolve only when the B cell lineage evolving breadth is consistently capturing and presenting more peptides to Tfh cells than othermore » lineages of more specific B cells. Here we develop mathematical models of Tfh cells in germinal centers to explicitly define the mechanisms of selection in this complex evolutionary process. Our results suggest that broadly reactive B cells presenting a high density of peptides bound to major histocompatibility complex class II molecules (pMHC) are readily outcompeted by B cells responding to lineages of HIV-1 that transiently dominate the within host viral population. Conversely, if broadly reactive B cells acquire a large variety of several HIV-1 proteins from the FDC network and present a high diversity of several pMHC, they can be rescued by a large fraction of the Tfh cell repertoire in the germinal center. Under such circumstances the evolution of bnAbs is much more consistent. Increasing either the magnitude of the Tfh cell response or the breadth of the Tfh cell repertoire markedly facilitates the evolution of bnAbs. Because both the magnitude and breadth can be increased by vaccination with several HIV-1 proteins, this calls for experimental testing. Many HIV-infected patients slowly evolve antibodies that can neutralize a large variety of viruses. Such broadly neutralizing antibodies (bnAbs) could in the future become therapeutic agents. bnAbs appear very late, and patients are typically

Activation of CO and CO2 on homonuclear boron bonds of fullerene-like BN cages: first principles study

NASA Astrophysics Data System (ADS)

Sinthika, S.; Kumar, E. Mathan; Surya, V. J.; Kawazoe, Y.; Park, Noejung; Iyakutti, K.; Thapa, Ranjit

2015-12-01

Using density functional theory we investigate the electronic and atomic structure of fullerene-like boron nitride cage structures. The pentagonal ring leads to the formation of homonuclear bonds. The homonuclear bonds are also found in other BN structures having pentagon line defect. The calculated thermodynamics and vibrational spectra indicated that, among various stable configurations of BN-60 cages, the higher number of homonuclear N-N bonds and lower B:N ratio can result in the more stable structure. The homonuclear bonds bestow the system with salient catalytic properties that can be tuned by modifying the B atom bonding environment. We show that homonuclear B-B (B2) bonds can anchor both oxygen and CO molecules making the cage to be potential candidates as catalyst for CO oxidation via Langmuir-Hinshelwood (LH) mechanism. Moreover, the B-B-B (B3) bonds are reactive enough to capture, activate and hydrogenate CO2 molecules to formic acid. The observed trend in reactivity, viz B3 > B2 > B1 is explained in terms of the position of the boron defect state relative to the Fermi level.

Activation of CO and CO2 on homonuclear boron bonds of fullerene-like BN cages: first principles study

PubMed Central

Sinthika, S.; Kumar, E. Mathan; Surya, V. J.; Kawazoe, Y.; Park, Noejung; Iyakutti, K.; Thapa, Ranjit

2015-01-01

Using density functional theory we investigate the electronic and atomic structure of fullerene-like boron nitride cage structures. The pentagonal ring leads to the formation of homonuclear bonds. The homonuclear bonds are also found in other BN structures having pentagon line defect. The calculated thermodynamics and vibrational spectra indicated that, among various stable configurations of BN-60 cages, the higher number of homonuclear N-N bonds and lower B:N ratio can result in the more stable structure. The homonuclear bonds bestow the system with salient catalytic properties that can be tuned by modifying the B atom bonding environment. We show that homonuclear B-B (B2) bonds can anchor both oxygen and CO molecules making the cage to be potential candidates as catalyst for CO oxidation via Langmuir–Hinshelwood (LH) mechanism. Moreover, the B-B-B (B3) bonds are reactive enough to capture, activate and hydrogenate CO2 molecules to formic acid. The observed trend in reactivity, viz B3 > B2 > B1 is explained in terms of the position of the boron defect state relative to the Fermi level. PMID:26626147

Activation of CO and CO2 on homonuclear boron bonds of fullerene-like BN cages: first principles study.

PubMed

Sinthika, S; Kumar, E Mathan; Surya, V J; Kawazoe, Y; Park, Noejung; Iyakutti, K; Thapa, Ranjit

2015-12-02

Using density functional theory we investigate the electronic and atomic structure of fullerene-like boron nitride cage structures. The pentagonal ring leads to the formation of homonuclear bonds. The homonuclear bonds are also found in other BN structures having pentagon line defect. The calculated thermodynamics and vibrational spectra indicated that, among various stable configurations of BN-60 cages, the higher number of homonuclear N-N bonds and lower B:N ratio can result in the more stable structure. The homonuclear bonds bestow the system with salient catalytic properties that can be tuned by modifying the B atom bonding environment. We show that homonuclear B-B (B2) bonds can anchor both oxygen and CO molecules making the cage to be potential candidates as catalyst for CO oxidation via Langmuir-Hinshelwood (LH) mechanism. Moreover, the B-B-B (B3) bonds are reactive enough to capture, activate and hydrogenate CO2 molecules to formic acid. The observed trend in reactivity, viz B3 > B2 > B1 is explained in terms of the position of the boron defect state relative to the Fermi level.

7 CFR 953.66 - Termination.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Termination. 953.66 Section 953.66 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... STATES Order Regulating Handling Effective Time and Termination § 953.66 Termination. (a) The Secretary...

42 CFR 66.201 - Applicability.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Applicability. 66.201 Section 66.201 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Institutional Grants § 66.201 Applicability. The regulations in this...

42 CFR 66.113 - Publications.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Publications. 66.113 Section 66.113 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.113 Publications. Publication, distribution, and...

42 CFR 66.201 - Applicability.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Applicability. 66.201 Section 66.201 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Institutional Grants § 66.201 Applicability. The regulations in this...

42 CFR 66.113 - Publications.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Publications. 66.113 Section 66.113 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.113 Publications. Publication, distribution, and...

42 CFR 66.113 - Publications.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Publications. 66.113 Section 66.113 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.113 Publications. Publication, distribution, and...

42 CFR 66.201 - Applicability.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Applicability. 66.201 Section 66.201 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Institutional Grants § 66.201 Applicability. The regulations in this...

42 CFR 66.113 - Publications.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Publications. 66.113 Section 66.113 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.113 Publications. Publication, distribution, and...

42 CFR 66.113 - Publications.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Publications. 66.113 Section 66.113 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.113 Publications. Publication, distribution, and...

7 CFR 983.66 - Records.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 8 2011-01-01 2011-01-01 false Records. 983.66 Section 983.66 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements and... NEW MEXICO Reports, Books and Records § 983.66 Records. Records of pistachios received, held and...

7 CFR 983.66 - Records.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 8 2013-01-01 2013-01-01 false Records. 983.66 Section 983.66 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND... NEW MEXICO Reports, Books and Records § 983.66 Records. Records of pistachios received, held and...

42 CFR 66.104 - Application.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Application. 66.104 Section 66.104 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.104 Application. (a) Eligible individuals may apply for...

42 CFR 66.101 - Applicability.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Applicability. 66.101 Section 66.101 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.101 Applicability. The regulations in this subpart...

42 CFR 66.109 - Termination.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Termination. 66.109 Section 66.109 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.109 Termination. (a) The Secretary may terminate an...

42 CFR 66.104 - Application.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Application. 66.104 Section 66.104 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.104 Application. (a) Eligible individuals may apply for...

42 CFR 66.204 - Application.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Application. 66.204 Section 66.204 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Institutional Grants § 66.204 Application. (a) Application for a grant...

42 CFR 66.114 - Copyright.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Copyright. 66.114 Section 66.114 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.114 Copyright. Where the work accomplished under an...

42 CFR 66.104 - Application.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Application. 66.104 Section 66.104 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.104 Application. (a) Eligible individuals may apply for...

42 CFR 66.114 - Copyright.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Copyright. 66.114 Section 66.114 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.114 Copyright. Where the work accomplished under an...

42 CFR 66.204 - Application.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Application. 66.204 Section 66.204 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Institutional Grants § 66.204 Application. (a) Application for a grant...

42 CFR 66.203 - Eligibility.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Eligibility. 66.203 Section 66.203 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Institutional Grants § 66.203 Eligibility. To be eligible for a grant...

42 CFR 66.109 - Termination.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Termination. 66.109 Section 66.109 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.109 Termination. (a) The Secretary may terminate an...

42 CFR 66.114 - Copyright.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Copyright. 66.114 Section 66.114 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.114 Copyright. Where the work accomplished under an...

42 CFR 66.109 - Termination.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Termination. 66.109 Section 66.109 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.109 Termination. (a) The Secretary may terminate an...

42 CFR 66.203 - Eligibility.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Eligibility. 66.203 Section 66.203 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Institutional Grants § 66.203 Eligibility. To be eligible for a grant...

42 CFR 66.204 - Application.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Application. 66.204 Section 66.204 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Institutional Grants § 66.204 Application. (a) Application for a grant...

42 CFR 66.101 - Applicability.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Applicability. 66.101 Section 66.101 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.101 Applicability. The regulations in this subpart...

42 CFR 66.104 - Application.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Application. 66.104 Section 66.104 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.104 Application. (a) Eligible individuals may apply for...

42 CFR 66.101 - Applicability.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Applicability. 66.101 Section 66.101 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.101 Applicability. The regulations in this subpart...

42 CFR 66.101 - Applicability.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Applicability. 66.101 Section 66.101 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.101 Applicability. The regulations in this subpart...

42 CFR 66.109 - Termination.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Termination. 66.109 Section 66.109 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.109 Termination. (a) The Secretary may terminate an...

42 CFR 66.101 - Applicability.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Applicability. 66.101 Section 66.101 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.101 Applicability. The regulations in this subpart...

42 CFR 66.114 - Copyright.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Copyright. 66.114 Section 66.114 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.114 Copyright. Where the work accomplished under an...

42 CFR 66.109 - Termination.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Termination. 66.109 Section 66.109 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.109 Termination. (a) The Secretary may terminate an...

42 CFR 66.114 - Copyright.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Copyright. 66.114 Section 66.114 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.114 Copyright. Where the work accomplished under an...

42 CFR 66.203 - Eligibility.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Eligibility. 66.203 Section 66.203 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Institutional Grants § 66.203 Eligibility. To be eligible for a grant...

44 CFR 66.2 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 44 Emergency Management and Assistance 1 2012-10-01 2011-10-01 true Definitions. 66.2 Section 66.2 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF HOMELAND SECURITY INSURANCE AND HAZARD MITIGATION National Flood Insurance Program CONSULTATION WITH LOCAL OFFICIALS § 66.2...

BN-C Hybrid Nanoribbons as Gas Sensors

NASA Astrophysics Data System (ADS)

Darvishi Gilan, Mahdi; Chegel, Raad

2018-02-01

The effects of carbon monoxide (CO) and ammonia (NH3) molecules adsorption on the various composites of boron nitride and graphene BN-C hybrid nanoribbons are investigated using the non-equilibrium Green's function (NEGF) technique based on density functional theory (DFT). The effects of adsorption with possible random configurations on the average of the density of states (DOS), transmission coefficient, and the current-voltage ( I- V) characteristics are calculated. The results indicate that, by embedding armchair graphene nanoribbon (AGNR) with boron nitride nanoribbon (BNNR), the various electronic properties can be observed after gas molecule adsorption. The electronic structure and gap of hybrids system is modified due to gas adsorption, and the systems act like the n-type semiconductor by NH3 molecule adsorption. The hybrid structures due to their tunable band gap are better candidates for gas detecting compared to the pristine BNNRs and AGNRs.

Surfactant exfoliated 2D hexagonal Boron Nitride (2D-hBN) explored as a potential electrochemical sensor for dopamine: surfactants significantly influence sensor capabilities.

PubMed

Khan, Aamar F; Brownson, Dale A C; Foster, Christopher W; Smith, Graham C; Banks, Craig E

2017-05-21

Surfactant exfoliated 2D hexagonal Boron Nitride (2D-hBN) nanosheets are explored as a potential electrochemical sensing platform and evaluated towards the electroanalytical sensing of dopamine (DA) in the presence of the common interferents, ascorbic acid (AA) and uric acid (UA). Surfactant exfoliated 2D-hBN nanosheets (2-4 layers) fabricated using sodium cholate in aqueous media are electrically wired via a drop-casting modification process onto disposable screen-printed graphite electrodes (SPEs). We critically evaluate the performance of these 2D-hBN modified SPEs and demonstrate the effect of 'mass coverage' towards the detection of DA, AA and UA. Previous studies utilising surfactant-free (pristine) 2D-hBN modified SPEs have shown a beneficial effect towards the detection of DA, AA and UA when compared to the underlying/unmodified graphite-based electrode. We show that the fabrication route utilised to prepare 2D-hBN is a vital experimental consideration, such that the beneficial effect previously reported is considerably reduced when surfactant exfoliated 2D-hBN is utilised. We demonstrate for the first time, through implementation of control experiments in the form of surfactant modified graphite electrodes, that sodium cholate is a major contributing factor to the aforementioned detrimental behaviour. The significance here is not in the material per se, but the fundamental knowledge of the surfactant and surface coverage changing the electrochemical properties of the material under investigation. Given the wide variety of ionic and non-ionic surfactants that are utilised in the manufacture of novel 2D materials, the control experiments reported herein need to be performed in order to de-convolute the electrochemical response and effectively evaluate the 'underlying surface/surfactant/2D materials' electrocatalytic contribution.

36 CFR 228.66 - Refunds.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 2 2012-07-01 2012-07-01 false Refunds. 228.66 Section 228.66 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE MINERALS Disposal of Mineral Materials Types and Methods of Disposal § 228.66 Refunds. Upon termination of any contract...

36 CFR 228.66 - Refunds.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 2 2011-07-01 2011-07-01 false Refunds. 228.66 Section 228.66 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE MINERALS Disposal of Mineral Materials Types and Methods of Disposal § 228.66 Refunds. Upon termination of any contract...

36 CFR 228.66 - Refunds.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 2 2013-07-01 2013-07-01 false Refunds. 228.66 Section 228.66 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE MINERALS Disposal of Mineral Materials Types and Methods of Disposal § 228.66 Refunds. Upon termination of any contract...

36 CFR 228.66 - Refunds.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false Refunds. 228.66 Section 228.66 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE MINERALS Disposal of Mineral Materials Types and Methods of Disposal § 228.66 Refunds. Upon termination of any contract...

36 CFR 228.66 - Refunds.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 2 2014-07-01 2014-07-01 false Refunds. 228.66 Section 228.66 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE MINERALS Disposal of Mineral Materials Types and Methods of Disposal § 228.66 Refunds. Upon termination of any contract...

22 CFR 66.1 - Introduction.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Introduction. 66.1 Section 66.1 Foreign Relations DEPARTMENT OF STATE PUBLIC DIPLOMACY AND EXCHANGES AVAILABILITY OF THE RECORDS OF THE NATIONAL ENDOWMENT FOR DEMOCRACY § 66.1 Introduction. These regulations amend the Code of Federal Regulations to...

21 CFR 1316.66 - Exceptions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Exceptions. 1316.66 Section 1316.66 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE ADMINISTRATIVE FUNCTIONS, PRACTICES, AND PROCEDURES Administrative Hearings § 1316.66 Exceptions. (a) Within twenty days after the date upon which a...

28 CFR 66.30 - Changes.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Changes. 66.30 Section 66.30 Judicial... AGREEMENTS TO STATE AND LOCAL GOVERNMENTS Post-Award Requirements Changes, Property, and Subawards § 66.30 Changes. (a) General. Grantees and subgrantees are permitted to rebudget within the approved direct cost...

7 CFR 1775.66 - Purpose.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 12 2014-01-01 2013-01-01 true Purpose. 1775.66 Section 1775.66 Agriculture... (CONTINUED) TECHNICAL ASSISTANCE GRANTS Solid Waste Management Grants § 1775.66 Purpose. Grants may be made...) Provide technical assistance and/or training to reduce the solid waste stream through reduction, recycling...

7 CFR 1775.66 - Purpose.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 12 2013-01-01 2013-01-01 false Purpose. 1775.66 Section 1775.66 Agriculture... (CONTINUED) TECHNICAL ASSISTANCE GRANTS Solid Waste Management Grants § 1775.66 Purpose. Grants may be made...) Provide technical assistance and/or training to reduce the solid waste stream through reduction, recycling...

7 CFR 1775.66 - Purpose.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 12 2012-01-01 2012-01-01 false Purpose. 1775.66 Section 1775.66 Agriculture... (CONTINUED) TECHNICAL ASSISTANCE GRANTS Solid Waste Management Grants § 1775.66 Purpose. Grants may be made...) Provide technical assistance and/or training to reduce the solid waste stream through reduction, recycling...

7 CFR 1775.66 - Purpose.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 12 2011-01-01 2011-01-01 false Purpose. 1775.66 Section 1775.66 Agriculture... (CONTINUED) TECHNICAL ASSISTANCE GRANTS Solid Waste Management Grants § 1775.66 Purpose. Grants may be made...) Provide technical assistance and/or training to reduce the solid waste stream through reduction, recycling...

42 CFR 66.105 - Requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Requirements. 66.105 Section 66.105 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.105 Requirements. The Secretary shall make an Award to...

42 CFR 66.105 - Requirements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Requirements. 66.105 Section 66.105 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.105 Requirements. The Secretary shall make an Award to...

42 CFR 66.106 - Awards.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Awards. 66.106 Section 66.106 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.106 Awards. (a) Within the limits of funds available, the...

42 CFR 66.103 - Eligibility.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Eligibility. 66.103 Section 66.103 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.103 Eligibility. To be eligible for a National Research...

42 CFR 66.106 - Awards.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Awards. 66.106 Section 66.106 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.106 Awards. (a) Within the limits of funds available, the...

42 CFR 66.103 - Eligibility.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Eligibility. 66.103 Section 66.103 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.103 Eligibility. To be eligible for a National Research...

42 CFR 66.105 - Requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Requirements. 66.105 Section 66.105 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.105 Requirements. The Secretary shall make an Award to...

42 CFR 66.103 - Eligibility.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Eligibility. 66.103 Section 66.103 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.103 Eligibility. To be eligible for a National Research...

42 CFR 66.106 - Awards.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Awards. 66.106 Section 66.106 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.106 Awards. (a) Within the limits of funds available, the...

42 CFR 66.103 - Eligibility.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Eligibility. 66.103 Section 66.103 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.103 Eligibility. To be eligible for a National Research...

42 CFR 66.106 - Awards.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Awards. 66.106 Section 66.106 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.106 Awards. (a) Within the limits of funds available, the...

42 CFR 66.103 - Eligibility.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Eligibility. 66.103 Section 66.103 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.103 Eligibility. To be eligible for a National Research...

42 CFR 66.105 - Requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Requirements. 66.105 Section 66.105 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.105 Requirements. The Secretary shall make an Award to...

Na-ion batteries based on the inorganic BN nanocluster anodes: DFT studies.

PubMed

Nejati, K; Hosseinian, A; Bekhradnia, A; Vessally, E; Edjlali, L

2017-06-01

It has been recently indicated that the Li-ion batteries may be replaced by Na-ion batteries because of their low safety, high cost, and low-temperature performance, and lack of the Li mineral reserves. Here, using density functional theory calculations, we studied the potential application of B 12 N 12 nanoclusters as anode in Na-ion batteries. Our calculations indicate that the adsorption energy of Na + and Na are about -23.4 and -1.4kcal/mol, respectively, and the pristine BN cage to improve suffers from a low cell voltage (∼0.92V) as an anode in Na-ion batteries. We presented a strategy to increase the cell voltage and performance of Na-ion batteries. We showed that encapsulation of different halides (X=F - , Cl - , or Br - ) into BN cage significantly increases the cell voltage. By increasing the atomic number of X, the Gibbs free energy change of cell becomes more negative and the cell voltage is increased up to 3.93V. The results are discussed based on the structural, energetic, frontier molecular orbital, charge transfer and electronic properties and compared with the performance of other nanostructured anodes. Copyright © 2017 Elsevier Inc. All rights reserved.

22 CFR 66.6 - Exemptions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Exemptions. 66.6 Section 66.6 Foreign Relations DEPARTMENT OF STATE PUBLIC DIPLOMACY AND EXCHANGES AVAILABILITY OF THE RECORDS OF THE NATIONAL ENDOWMENT FOR DEMOCRACY § 66.6 Exemptions. NED reserves the right to withhold records and information that are exempt from...

Raman Study of Uncoated and p-BN/SiC-Coated Hi-Nicalon Fiber-Reinforced Celsian Matrix Composites. Part 1; Distribution and Nanostructure of Different Phases

NASA Technical Reports Server (NTRS)

Gouadec, Gwenael; Colomban, Philippe; Bansal, Narottam P.

2000-01-01

Hi-Nicalon fiber reinforced celsian matrix composites were characterized by Raman spectroscopy and imaging, using several laser wavelengths. Composite #1 is reinforced by as-received fibers while coatings of p-BN and SiC protect the fibers in composite #2. The matrix contains traces of the hexagonal phase of celsian, which is concentrated in the neighborhood of fibers in composite #1. Some free silicon was evident in the coating of composite #2 which might involve a {BN + SiC yields BNC + Si} "reaction" at the p-BN/SiC interface. Careful analysis of C-C peaks revealed no abnormal degradation of the fiber core in the composites.

Thermochemistry and electronic structure of small boron clusters (B(n), n = 5-13) and their anions.

PubMed

Truong, Ba Tai; Grant, Daniel J; Nguyen, Minh Tho; Dixon, David A

2010-01-21

Thermochemical parameters of a set of small-sized neutral (B(n)) and anionic (B(n)(-)) boron clusters, with n = 5-13, were determined using coupled-cluster theory CCSD(T) calculations with the aug-cc-pVnZ (n = D, T, and Q) basis sets extrapolated to the complete basis set limit (CBS) plus addition corrections and/or G3B3 calculations. Enthalpies of formation, adiabatic electron affinities (EA), vertical (VDE), and adiabatic (ADE) detachment energies were evaluated. Our calculated EAs are in good agreement with recent experiments (values in eV): B(5) (CBS, 2.29; G3B3, 2.48; exptl., 2.33 +/- 0.02), B(6) (CBS, 2.59; G3B3, 3.23; exptl., 3.01 +/- 0.04), B(7) (CBS, 2.62; G3B3, 2.67; exptl., 2.55 +/- 0.05), B(8) (CBS, 3.02; G3B3, 3.11; exptl., 3.02 +/- 0.02), B(9) (G3B3, 3.03; exptl., 3.39 +/- 0.06), B(10) (G3B3, 2.85; exptl., 2.88 +/- 0.09), B(11) (G3B4, 3.48;, exptl., 3.43 +/- 0.01), B(12) (G3B3, 2.33; exptl., 2.21 +/- 0.04), and B(13) (G3B3, 3.62; exptl., 3.78 +/- 0.02). The difference between the calculated adiabatic electron affinity and the adiabatic detachment energy for B(6) is due to the fact that the geometry of the anion is not that of the ground-state neutral. The calculated adiabatic detachment energies to the (3)A(u), C(2h) and (1)A(g), D(2h) excited states of B(6), which have geometries similar to the (1)A(g), D(2h) state of B(6)(-), are 2.93 and 3.06 eV, in excellent agreement with experiment. The VDEs were also well reproduced by the calculations. Partitioning of the electron localization functions into pi and sigma components allows probing of the partial and local delocalization in global nonaromatic systems. The larger clusters appear to exhibit multiple aromaticity. The binding energies per atom vary in a parallel manner for both neutral and anionic series and approach the experimental value for the heat of atomization of B. The resonance energies and the normalized resonance energies are convenient indices to quantify the stabilization of a cluster

High-Pressure Design of Advanced BN-Based Materials.

PubMed

Kurakevych, Oleksandr O; Solozhenko, Vladimir L

2016-10-20

The aim of the present review is to highlight the state of the art in high-pressure design of new advanced materials based on boron nitride. Recent experimental achievements on the governing phase transformation, nanostructuring and chemical synthesis in the systems containing boron nitride at high pressures and high temperatures are presented. All these developments allowed discovering new materials, e.g., ultrahard nanocrystalline cubic boron nitride (nano-cBN) with hardness comparable to diamond, and superhard boron subnitride B 13 N₂. Thermodynamic and kinetic aspects of high-pressure synthesis are described based on the data obtained by in situ and ex situ methods. Mechanical and thermal properties (hardness, thermoelastic equations of state, etc.) are discussed. New synthetic perspectives, combining both soft chemistry and extreme pressure-temperature conditions are considered.

22 CFR 66.8 - Reports.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Reports. 66.8 Section 66.8 Foreign Relations... DEMOCRACY § 66.8 Reports. On or before March 1 of each calendar year, NED shall submit a reporting covering... Senate for referral to the appropriate committees of the Congress. The report shall include those items...

22 CFR 66.8 - Reports.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Reports. 66.8 Section 66.8 Foreign Relations... DEMOCRACY § 66.8 Reports. On or before March 1 of each calendar year, NED shall submit a reporting covering... Senate for referral to the appropriate committees of the Congress. The report shall include those items...

22 CFR 66.8 - Reports.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Senate for referral to the appropriate committees of the Congress. The report shall include those items... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Reports. 66.8 Section 66.8 Foreign Relations... DEMOCRACY § 66.8 Reports. On or before March 1 of each calendar year, NED shall submit a reporting covering...

22 CFR 66.8 - Reports.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Senate for referral to the appropriate committees of the Congress. The report shall include those items... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Reports. 66.8 Section 66.8 Foreign Relations... DEMOCRACY § 66.8 Reports. On or before March 1 of each calendar year, NED shall submit a reporting covering...

22 CFR 66.8 - Reports.

Code of Federal Regulations, 2012 CFR

2012-04-01

... Senate for referral to the appropriate committees of the Congress. The report shall include those items... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Reports. 66.8 Section 66.8 Foreign Relations... DEMOCRACY § 66.8 Reports. On or before March 1 of each calendar year, NED shall submit a reporting covering...

A Tourist-like MITE insertion in the upstream region of the BnFLC.A10 gene is associated with vernalization requirement in rapeseed (Brassica napus L.)

PubMed Central

2012-01-01

Background Rapeseed (Brassica napus L.) has spring and winter genotypes adapted to different growing seasons. Winter genotypes do not flower before the onset of winter, thus leading to a longer vegetative growth period that promotes the accumulation and allocation of more resources to seed production. The development of winter genotypes enabled the rapeseed to spread rapidly from southern to northern Europe and other temperate regions of the world. The molecular basis underlying the evolutionary transition from spring- to winter- type rapeseed is not known, however, and needs to be elucidated. Results We fine-mapped the spring environment specific quantitative trait locus (QTL) for flowering time, qFT10-4,in a doubled haploid (DH) mapping population of rapeseed derived from a cross between Tapidor (winter-type) and Ningyou7 (semi-winter) and delimited the qFT10-4 to an 80-kb region on chromosome A10 of B. napus. The BnFLC.A10 gene, an ortholog of FLOWERING LOCUS C (FLC) in Arabidopsis, was cloned from the QTL. We identified 12 polymorphic sites between BnFLC.A10 parental alleles of the TN-DH population in the upstream region and in intron 1. Expression of both BnFLC.A10 alleles decreased during vernalization, but decreased more slowly in the winter parent Tapidor. Haplotyping and association analysis showed that one of the polymorphic sites upstream of BnFLC.A10 is strongly associated with the vernalization requirement of rapeseed (r2 = 0.93, χ2 = 0.50). This polymorphic site is derived from a Tourist-like miniature inverted-repeat transposable element (MITE) insertion/deletion in the upstream region of BnFLC.A10. The MITE sequence was not present in the BnFLC.A10 gene in spring-type rapeseed, nor in ancestral ‘A’ genome species B. rapa genotypes. Our results suggest that the insertion may have occurred in winter rapeseed after B. napus speciation. Conclusions Our findings strongly suggest that (i) BnFLC.A10 is the gene underlying qFT10-4, the QTL for

19 CFR 207.66 - Hearing.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 19 Customs Duties 3 2010-04-01 2010-04-01 false Hearing. 207.66 Section 207.66 Customs Duties... EXPORTS TO THE UNITED STATES Five-Year Reviews § 207.66 Hearing. (a) In general. The Commission shall hold a hearing in each full review. The date of the hearing shall be specified in the scheduling notice...

Dynamic Negative Compressibility of Few-Layer Graphene, h-BN, and MoS2

NASA Astrophysics Data System (ADS)

Neves, Bernardo; Barboza, Ana Paula; Chacham, Helio; Oliveira, Camilla; Fernandes, Thales; Martins Ferreira, Erlon; Archanjo, Braulio; Batista, Ronaldo; Oliveira, Alan

2013-03-01

We report a novel mechanical response of few-layer graphene, h-BN, and MoS2 to the simultaneous compression and shear by an atomic force microscope (AFM) tip. The response is characterized by the vertical expansion of these two-dimensional (2D) layered materials upon compression. Such effect is proportional to the applied load, leading to vertical strain values (opposite to the applied force) of up to 150%. The effect is null in the absence of shear, increases with tip velocity, and is anisotropic. It also has similar magnitudes in these solid lubricant materials (few-layer graphene, h-BN, and MoS2), but it is absent in single-layer graphene and in few-layer mica and Bi2Se3. We propose a physical mechanism for the effect where the combined compressive and shear stresses from the tip induce dynamical wrinkling on the upper material layers, leading to the observed flake thickening. The new effect (and, therefore, the proposed wrinkling) is reversible in the three materials where it is observed.[2] Financial support from CNPq, Fapemig, Rede Nacional de Pesquisa em Nanotubos de Carbono and INCT-Nano-Carbono

First-principles calculations and model analysis of plasmon excitations in graphene and graphene/hBN heterostructure

NASA Astrophysics Data System (ADS)

Li, Pengfei; Ren, Xinguo; He, Lixin

2017-10-01

Plasmon excitations in free-standing graphene and graphene/hexagonal boron nitride (hBN) heterostructure are studied using linear-response time-dependent density functional theory within the random phase approximation. Within a single theoretical framework, we examine both the plasmon dispersion behavior and lifetime (linewidth) of Dirac and π plasmons on an equal footing. Particular attention is paid to the influence of the hBN substrate and the anisotropic effect. Furthermore, a model-based analysis indicates that the correct dispersion behavior of π plasmons should be ωπ(q ) =√{Eg2+β ql} for small q 's, where Eg is the band gap at the M point in the Brillouin zone, and β is a fitting parameter. This model is radically different from previous proposals, but in good agreement with our calculated results from first principles.

Structural instabilities and wrinkles at the grain boundaries in 2-D h-BN: a first-principles analysis.

PubMed

Singh, Anjali; Waghmare, Umesh V

2014-10-21

The structure of grain boundaries (GBs) or interfaces between nano-forms of carbon determines their evolution into 3-D forms with nano-scale architecture. Here, we present a general framework for the construction of interfaces in 2-D h-BN and graphene in terms of (a) stacking faults and (b) growth faults, using first-principles density functional theoretical analysis. Such interfaces or GBs involve deviation from their ideal hexagonal lattice structure. We show that a stacking fault involves a linkage of rhombal and octagonal rings (4 : 8), and a growth fault involves a linkage of paired pentagonal and octagonal rings (5 : 5 : 8). While a growth fault is energetically more stable than a stacking fault in graphene, the polarity of B and N leads to the reversal of their relative stability in h-BN. We show that the planar structure of these interfacing grains exhibits instability with respect to buckling (out-of-plane deformation), which results in the formation of a wrinkle at the grain boundary (GB) and rippling of the structure. Our analysis leads to prediction of new types of low-energy GBs of 2-D h-BN and graphene. Our results for electronic and vibrational signatures of these interfaces and an STM image of the most stable interface will facilitate their experimental characterization, particularly of the wrinkles forming spontaneously at these interfaces.

Microstructure and Tensile Properties of BN/SiC Coated Hi-Nicalon, and Sylramic SiC Fiber Preforms

NASA Technical Reports Server (NTRS)

Bhatt, Ramakrishna T.; Chen, Yuan L.; Morscher, Gregory N.

2001-01-01

Batch to batch and within batch variations, and the influence of fiber architecture on room temperature physical and tensile properties of BN/SiC coated Hi-Nicalon and Sylramic SiC fiber preform specimens were determined. The three fiber architectures studied were plain weave (PW), 5-harness satin (5HS) and 8-harness satin (8HS) Results indicate that the physical properties vary up to 10 percent within a batch, and up to 20 percent between batches of preforms. Load-reload (Hysteresis) and acoustic emission methods were used to analyze damage accumulation occurring during tensile loading. Early acoustic emission activity, before observable hysteretic behavior, indicates that the damage starts with the formation of nonbridged tunnel cracks. These cracks then propagate and intersect the load bearing "0" fibers giving rise to hysteretic behavior, For the Hi-Nicalon preform specimens, the onset of "0" bundle cracking stress and strain appeared to be independent of the fiber architecture. Also, the "0" fiber bundle cracking strain remained nearly the same for the preform specimens of both fiber types. Transmission Electron Microscope (TEM) analysis indicates that the Chemical Vapor Infiltration (CVI) Boron Nitride (BN) interface coating is mostly amorphous and contains carbon and oxygen impurities, and the CVI SiC coating is crystalline. No reaction exists between the CVI BN and SiC coating.

h-BN/graphene van der Waals vertical heterostructure: a fully spin-polarized photocurrent generator.

PubMed

Tao, Xixi; Zhang, Lei; Zheng, Xiaohong; Hao, Hua; Wang, Xianlong; Song, Lingling; Zeng, Zhi; Guo, Hong

2017-12-21

By constructing transport junctions using graphene-based van der Waals (vdW) heterostructures in which a zigzag-edged graphene nanoribbon (ZGNR) is sandwiched between two hexagonal boron-nitride sheets, we computationally demonstrate a new scheme for generating perfect spin-polarized quantum transport in ZGNRs by light irradiation. The mechanism lies in the lift of spin degeneracy of ZGNR induced by the stagger potential it receives from the BN sheets and the subsequent possibility of single spin excitation of electrons from the valence band to the conduction band by properly tuning the photon energy. This scheme is rather robust in that we always achieve desirable results irrespective of whether we decrease or increase the interlayer distance by applying compressive or tensile strain vertically to the sheets or shift the BN sheets in-plane relative to the graphene nanoribbons. More importantly, this scheme overcomes the long-standing difficulties in traditional ways of using solely electrical field or chemical modification for obtaining half-metallic transport in ZGNRs and thus paves a more feasible way for their application in spintronics.

Time-resolved Polarimetry of the Superluminous SN 2015bn with the Nordic Optical Telescope

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

Leloudas, Giorgos; Gal-Yam, Avishay; Maund, Justyn R.

2017-03-01

We present imaging polarimetry of the superluminous supernova SN 2015bn, obtained over nine epochs between −20 and +46 days with the Nordic Optical Telescope. This was a nearby, slowly evolving Type I superluminous supernova that has been studied extensively and for which two epochs of spectropolarimetry are also available. Based on field stars, we determine the interstellar polarization in the Galaxy to be negligible. The polarization of SN 2015bn shows a statistically significant increase during the last epochs, confirming previous findings. Our well-sampled imaging polarimetry series allows us to determine that this increase (from ∼0.54% to ≳1.10%) coincides in timemore » with rapid changes that took place in the optical spectrum. We conclude that the supernova underwent a “phase transition” at around +20 days, when the photospheric emission shifted from an outer layer, dominated by natal C and O, to a more aspherical inner core, dominated by freshly nucleosynthesized material. This two-layered model might account for the characteristic appearance and properties of Type I superluminous supernovae.« less

Most effective way to improve the hydrogen storage abilities of Na-decorated BN sheets: applying external biaxial strain and an electric field.

PubMed

Tang, Chunmei; Zhang, Xue; Zhou, Xiaofeng

2017-02-15

Density functional calculations were used to investigate the hydrogen storage abilities of Na-atoms-decorated BN sheets under both external biaxial strain and a vertical electric field. The Na atom generally has the weakest binding strength to a given substrate compared with the other elements in the periodic table [PANS, 2016, 113, 3735]. Consequently, it is understudied in comparison to other elements and there are few reports about the hydrogen storage abilities of Na-decorated nanomaterials. We calculated that the average binding energy (E b ) of Na atoms to the pure BN sheet is 1.08 eV, which is smaller than the cohesive energy of bulk Na (1.11 eV). However, the E b can be increased to 1.15 eV under 15% biaxial strain, and further up to 1.53 eV with the control of both 15% biaxial strain and a 5.14 V nm -1 electric field (E-field). Therefore, the application of biaxial strain and an external upward E-field can prevent clustering of the Na atoms on the surface of a BN sheet, which is crucial for the hydrogen storage. Each Na atom on the surface of a BN sheet can adsorb only one H 2 molecule when no strain or E-field is applied; however, the absorption increases to five H 2 molecules under 15% biaxial strain and six H 2 molecules under both 15% biaxial strain combined with a 5.14 V nm -1 E-field. The average adsorption energies for H 2 of BN-(Na-mH 2 ) (m = 1-6) are within the range of practical applications (0.2-0.6 eV). The hydrogen gravimetric density of the periodic BN-(Na-6H 2 ) 4 structure is 9 wt%, which exceeds the 5.5 wt% value that should be met by 2017 as specified by the US Department of Energy. On the other side, removal of the biaxial strain and E-field can help to desorb the H 2 molecule. These findings suggest a new route to design hydrogen storage materials under near-ambient conditions.

Microstructure and Tensile Properties of BN/SiC Coated Hi-Nicalon, and Sylramic SiC Fiber Preforms. Revised

NASA Technical Reports Server (NTRS)

Bhatt, Ramakrishna T.; Chen, Yuan L.; Morscher, Gregory N.

2002-01-01

Batch to batch and within batch variations, and the influence of fiber architecture on room temperature physical and tensile properties of BN/SiC coated Hi-Nicalon and Sylramic SiC fiber preform specimens were determined. The three fiber architectures studied were plain weave (PW), 5-harness satin (5HS), and 8-harness satin (8HS). Results indicate that the physical properties vary up to 10 percent within a batch, and up to 20 percent between batches of preforms. Load-reload (Hysteresis) and acoustic emission methods were used to analyze damage accumulation occurring during tensile loading. Early acoustic emission activity, before observable hysteretic behavior, indicates that the damage starts with the formation of nonbridged tunnel cracks. These cracks then propagate and intersect the load bearing "0 deg" fibers giving rise to hysteretic behavior. For the Hi-Nicalon preform specimens, the onset of "0 deg" bundle cracking stress and strain appeared to be independent of the fiber architecture. Also, the "0 deg" fiber bundle cracking strain remained nearly the same for the preform specimens of both fiber types. TEM analysis indicates that the CVI BN interface coating is mostly amorphous and contains carbon and oxygen impurities, and the CVI SiC coating is crystalline. No reaction exists between the CVI BN and SiC coating.

Strain-Engineering of Giant Pseudo-Magnetic Fields in Graphene/Boron Nitride (BN) Periodic Nanostructures

NASA Astrophysics Data System (ADS)

Hsu, Chen-Chih; Wang, Jiaqing; Teague, Marcus; Chen, Chien-Chang; Yeh, Nai-Chang

2015-03-01

Ideal graphene is strain-free whereas non-trivial strain can induce pseudo-magnetic fields as predicted theoretically and manifested experimentally. Here we employ nearly strain-free single-domain graphene, grown by plasma-enhanced chemical vapor deposition (PECVD) at low temperatures, to induce controlled strain by placing the PECVD-graphene on substrates containing engineered nanostructures. We fabricate periodic pyramid nanostructures (typically 100 ~ 200 nm laterally and 10 ~ 60 nm in height) on Si substrates by focused ion beam, and determine the topography of these nanostructures using atomic force microscopy and scanning electron microscopy after we transferred monolayer h-BN followed by PECVD-graphene onto these substrates. We find both layers conform well to the nanostructures so that we can control the size, arrangement, separation, and shape of the nanostructures to generate desirable pseudo-magnetic fields. We also employ molecular dynamics simulation to determine the displacement of carbon atoms under a given nanostructure. The pseudo-magnetic field thus obtained is ~150T in the center, relatively homogeneous over 50% of the area, and drops off precipitously near the edge. These findings are extended to arrays of nanostructures and compared with topographic and spectroscopic studies by STM. Supported by NSF.

FAST TRACK COMMUNICATION: Electronic structure of a graphene/hexagonal-BN heterostructure grown on Ru(0001) by chemical vapor deposition and atomic layer deposition: extrinsically doped graphene

NASA Astrophysics Data System (ADS)

Bjelkevig, Cameron; Mi, Zhou; Xiao, Jie; Dowben, P. A.; Wang, Lu; Mei, Wai-Ning; Kelber, Jeffry A.

2010-08-01

A significant BN-to-graphene charge donation is evident in the electronic structure of a graphene/h-BN(0001) heterojunction grown by chemical vapor deposition and atomic layer deposition directly on Ru(0001), consistent with density functional theory. This filling of the lowest unoccupied state near the Brillouin zone center has been characterized by combined photoemission/k vector resolved inverse photoemission spectroscopies, and Raman and scanning tunneling microscopy/spectroscopy. The unoccupied σ*(Γ1 +) band dispersion yields an effective mass of 0.05 me for graphene in the graphene/h-BN(0001) heterostructure, in spite of strong perturbations to the graphene conduction band edge placement.

Microstructure, Mechanical Properties, and Two-Body Abrasive Wear Behavior of Cold-Sprayed 20 vol.% Cubic BN-NiCrAl Nanocomposite Coating

NASA Astrophysics Data System (ADS)

Luo, Xiao-Tao; Yang, Er-Juan; Shang, Fu-Lin; Yang, Guan-Jun; Li, Chen-Xin; Li, Chang-Jiu

2014-10-01

20 vol.% cubic boron nitride (cBN) dispersoid reinforced NiCrAl matrix nanocomposite coating was prepared by cold spray using mechanically alloyed nanostructured composite powders. The as-sprayed nanocomposite coating was annealed at a temperature of 750 °C to enhance the inter-particle bonding. Microstructure of spray powders and coatings was characterized. Vickers microhardness of the coatings was measured. Two-body abrasive wear behavior of the coatings was examined on a pin-on-disk test. It was found that, in mechanically alloyed composite powders, nano-sized and submicro-sized cBN particles are uniformly distributed in nanocrystalline NiCrAl matrix. Dense coating was deposited by cold spray at a gas temperature of 650 °C with the same phases and grain size as those of the starting powder. Vickers hardness test yielded a hardness of 1063 HV for the as-sprayed 20 vol.% cBN-NiCrAl coating. After annealed at 750 °C for 5 h, unbonded inter-particle boundaries were partially healed and evident grain growth of nanocrystalline NiCrAl was avoided. Wear resistance of the as-sprayed 20 vol.% cBN-NiCrAl nanocomposite coating was comparable to the HVOF-sprayed WC-12Co coating. Annealing of the nanocomposite coating resulted in the improvement of wear resistance by a factor of ~33% owing to the enhanced inter-particle bonding. Main material removal mechanisms during the abrasive wear are also discussed.

Molecular Cloning and Functional Analysis of Three Type D Endogenous Retroviruses of Sheep Reveal a Different Cell Tropism from That of the Highly Related Exogenous Jaagsiekte Sheep Retrovirus

PubMed Central

Palmarini, Massimo; Hallwirth, Claus; York, Denis; Murgia, Claudio; de Oliveira, Tulio; Spencer, Thomas; Fan, Hung

2000-01-01

Integrated into the sheep genome are 15 to 20 copies of type D endogenous loci that are highly related to two exogenous oncogenic viruses, jaagsiekte sheep retrovirus (JSRV) and enzootic nasal tumor virus (ENTV). The exogenous viruses cause infectious neoplasms of the respiratory tract in small ruminants. In this study, we molecularly cloned three intact type D endogenous retroviruses of sheep (enJS56A1, enJS5F16, and enJS59A1; collectively called enJRSVs) and analyzed their genomic structures, their phylogenies with respect to their exogenous counterparts, their capacity to form viral particles, and the expression specificities of their long terminal repeats (LTRs). In addition, the pattern of expression of enJSRVs in vivo was studied by in situ hybridization. All of the three enJSRV proviruses had open reading frames for at least one of the structural genes. In particular, enJS56A1 had open reading frames for all structural genes, but it could not assemble viral particles when highly expressed in human 293T cells. We localized the defect for viral assembly in the first two-thirds of the gag gene by making a series of chimeras between enJS56A1 and the exogenous infectious molecular clone JSRV21. Phylogenetic analysis distinguished five ovine type D retroviruses: enJSRV groups A and B, ENTV, and two exogenous JSRV groups (African versus United Kingdom/North America isolates). Transient transfection assays indicated that the LTRs of the three enJSRVs were not preferentially active in differentiated lung epithelial cells. This suggests that the pulmonary tropic JSRV developed from a type D retrovirus that did not have lung specificity. Consistent with this, in situ hybridization of a panel of normal ovine tissues revealed high expression of enJSRV mRNA in the luminal epithelium and glandular epithelium of the uterus; lower expression was localized in the lamina propria of the gut and in the bronchiolar epithelium of the lungs. PMID:10933716

7 CFR 1730.66 - Administrative waiver.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 11 2010-01-01 2010-01-01 false Administrative waiver. 1730.66 Section 1730.66 Agriculture Regulations of the Department of Agriculture (Continued) RURAL UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE ELECTRIC SYSTEM OPERATIONS AND MAINTENANCE Interconnection of Distributed Resources § 1730.66...

Island shape, size and interface dependency on electronic and magnetic properties of graphene hexagonal-boron nitride (h-BN) in-plane hybrids

NASA Astrophysics Data System (ADS)

Akman, Nurten; Özdoğan, Cem

2018-04-01

We systematically investigate the energetics of ion implantation, stability, electronic, and magnetic properties of graphene/hexagonal boron nitrate (h-BN) in-plane hybrids through first principle calculations. We consider hexagonal and triangular islands in supercells of graphene and h-BN layouts. In the case of triangular islands, both phases mix with each other by either solely Csbnd N or Csbnd B bonds. We also patterned triangles with predominating Csbnd N or Csbnd B bonds at their interfaces. The energetics of island implantation is discussed in detail. Formation energies point out that the island implantation could be even exothermic for all hybrids studied in this work. Effects of size and shape of the island, and dominating bonding sort at the island-layout interfaces on the stability, band gap, and magnetic properties of hybrids are studied particularly. The hybrids become more stable with increasing island size. Regardless of the layout, hybrids with hexagonal islands are all non-magnetic and semiconducting. One can thus open a band gap in the semimetallic graphene by mixing it with the h-BN phase. In general, hybrids containing graphene triangles show metallic property and exhibit considerable amount of magnetic moments for possible localized spin utilizations. Total magnetic moment of hybrids with both graphene and h-BN layouts increases with growing triangle island as well. The spin densities of magnetic hybrids are derived from interfaces of the islands and diminish towards their center. We suggest that the increase in stability and magnetic moment depend on the number of atoms at the interfaces rather than the island size.

Physical, mechanical and neutron shielding properties of h-BN/Gd2O3/HDPE ternary nanocomposites

NASA Astrophysics Data System (ADS)

İrim, Ş. Gözde; Wis, Abdulmounem Alchekh; Keskin, M. Aker; Baykara, Oktay; Ozkoc, Guralp; Avcı, Ahmet; Doğru, Mahmut; Karakoç, Mesut

2018-03-01

In order to prepare an effective neutron shielding material, not only neutron but also gamma absorption must be taken into account. In this research, a polymer nanocomposite based novel type of multifunctional neutron shielding material is designed and fabricated. For this purpose, high density polyethylene (HDPE) was compounded with different amounts of hexagonal boron nitride (h-BN) and Gd2O3 nanoparticles having average particle size of 100 nm using melt-compounding technique. The mechanical, thermal and morphological properties of nanocomposites were investigated. As filler content increased, the absorption of both neutron and gamma fluxes increased despite fluctuating neutron absorption curves. Adding h-BN and Gd2O3 nano particles had a significant influence on both neutron and gamma attenuation properties (Σ, cm-1 and μ/ρ, cm-2/g) of ternary shields and they show an enhancement of 200-280%, 14-52% for neutron and gamma radiations, respectively, in shielding performance.

Formation of graphene on BN substrate by vapor deposition method and size effects on its structure

NASA Astrophysics Data System (ADS)

Giang, Nguyen Hoang; Hanh, Tran Thi Thu; Ngoc, Le Nhu; Nga, Nguyen To; Van Hoang, Vo

2018-04-01

We report MD simulation of the growth of graphene by the vapor deposition on a two-dimensional hBN substrate. The systems (containing carbon vapor and hBN substrate) are relaxed at high temperature (1500 K), and then it is cooled down to room one (300 K). Carbon atoms interact with the substrate via the Lennard-Jones potential while the interaction between carbon atoms is computed via the Tersoff potential. Depending on the size of the model, different crystalline honeycomb structures have been found. Structural properties of the graphene obtained at 300 K are studied by analyzing radial distribution functions (RDFs), coordination numbers, ring statistics, interatomic distances, bond-angle distributions and 2D visualization of atomic configurations. We find that the models containing various numbers of atoms have a honeycomb structure. Besides, differences in structural properties of graphene formed by the vapor deposition on the substrate and free standing one are found. Moreover, the size effect on the structure is significant.

Delineating the role of ripples on the thermal expansion of 2D honeycomb materials: graphene, 2D h-BN and monolayer (ML)-MoS2.

PubMed

Anees, P; Valsakumar, M C; Panigrahi, B K

2017-04-19

We delineated the role of thermally excited ripples on the thermal expansion properties of 2D honeycomb materials (free-standing graphene, 2D h-BN, and ML-MoS 2 ), by explicitly carrying out three-dimensional (3D) and two-dimensional (2D) molecular dynamics simulations. In 3D simulations, the in-plane lattice parameter (a-lattice) of graphene and 2D h-BN shows thermal contraction over a wide range of temperatures and exhibits a strong system size dependence. The 2D simulations of the very same system show a reverse trend, where the a-lattice expands in the whole computed temperature range. In contrast to graphene and 2D h-BN, the a-lattice of ML-MoS 2 shows thermal expansion in both 2D and 3D simulations and their system size dependence is marginal. By analyzing the phonon dispersion at 300 K, we found that the discrepancy between 2D and 3D simulations of graphene and 2D h-BN is due to the absence of out-of-plane bending modes (ZA) in 2D simulations, which is responsible for the thermal contraction of the a-lattice at low temperature. Meanwhile, all the phonon modes are present in the 2D phonon dispersion of ML-MoS 2 , which indicates that the origin of the ZA mode is not purely due to the out-of-plane movement of atoms and also its effect on thermal expansion is not significant as found in graphene and 2D h-BN.

DNA and modified vaccinia virus Ankara vaccines encoding multiple cytotoxic and helper T-lymphocyte epitopes of human immunodeficiency virus type 1 (HIV-1) are safe but weakly immunogenic in HIV-1-uninfected, vaccinia virus-naive adults.

PubMed

Gorse, Geoffrey J; Newman, Mark J; deCamp, Allan; Hay, Christine Mhorag; De Rosa, Stephen C; Noonan, Elizabeth; Livingston, Brian D; Fuchs, Jonathan D; Kalams, Spyros A; Cassis-Ghavami, Farah L

2012-05-01

We evaluated a DNA plasmid-vectored vaccine and a recombinant modified vaccinia virus Ankara vaccine (MVA-mBN32), each encoding cytotoxic and helper T-lymphocyte epitopes of human immunodeficiency virus type 1 (HIV-1) in a randomized, double-blinded, placebo-controlled trial in 36 HIV-1-uninfected adults using a heterologous prime-boost schedule. HIV-1-specific cellular immune responses, measured as interleukin-2 and/or gamma interferon production, were induced in 1 (4%) of 28 subjects after the first MVA-mBN32 immunization and in 3 (12%) of 25 subjects after the second MVA-mBN32 immunization. Among these responders, polyfunctional T-cell responses, including the production of tumor necrosis factor alpha and perforin, were detected. Vaccinia virus-specific antibodies were induced to the MVA vector in 27 (93%) of 29 and 26 (93%) of 28 subjects after the first and second immunizations with MVA-mBN32. These peptide-based vaccines were safe but were ineffective at inducing HIV-1-specific immune responses and induced much weaker responses than MVA vaccines expressing the entire open reading frames of HIV-1 proteins.

46 CFR 310.66 - Foreign students.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 8 2010-10-01 2010-10-01 false Foreign students. 310.66 Section 310.66 Shipping... Training of Midshipmen at the United States Merchant Marine Academy § 310.66 Foreign students. (a..., country clearances, travel papers, transportation to the Academy, obtaining the necessary designation by...

33 CFR 401.66 - Applicable laws.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Applicable laws. 401.66 Section 401.66 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Dangerous Cargo § 401.66 Applicable laws. (a) Vessels...

33 CFR 401.66 - Applicable laws.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Applicable laws. 401.66 Section 401.66 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Dangerous Cargo § 401.66 Applicable laws. (a) Vessels...

33 CFR 401.66 - Applicable laws.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Applicable laws. 401.66 Section 401.66 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Dangerous Cargo § 401.66 Applicable laws. (a) Vessels...

33 CFR 401.66 - Applicable laws.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Applicable laws. 401.66 Section 401.66 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Dangerous Cargo § 401.66 Applicable laws. (a) Vessels...

40 CFR 66.93 - Time limits.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Time limits. 66.93 Section 66.93 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ASSESSMENT AND COLLECTION OF NONCOMPLIANCE PENALTIES BY EPA Supplemental Rules for Formal Adjudicatory Hearings § 66.93 Time...

40 CFR 66.93 - Time limits.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 16 2013-07-01 2013-07-01 false Time limits. 66.93 Section 66.93 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ASSESSMENT AND COLLECTION OF NONCOMPLIANCE PENALTIES BY EPA Supplemental Rules for Formal Adjudicatory Hearings § 66.93 Time...

40 CFR 66.93 - Time limits.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 16 2014-07-01 2014-07-01 false Time limits. 66.93 Section 66.93 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ASSESSMENT AND COLLECTION OF NONCOMPLIANCE PENALTIES BY EPA Supplemental Rules for Formal Adjudicatory Hearings § 66.93 Time...

40 CFR 66.93 - Time limits.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 15 2011-07-01 2011-07-01 false Time limits. 66.93 Section 66.93 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ASSESSMENT AND COLLECTION OF NONCOMPLIANCE PENALTIES BY EPA Supplemental Rules for Formal Adjudicatory Hearings § 66.93 Time...

34 CFR 691.66 - Correspondence study.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 34 Education 3 2010-07-01 2010-07-01 false Correspondence study. 691.66 Section 691.66 Education... RETAIN TALENT GRANT (NATIONAL SMART GRANT) PROGRAMS Determination of Awards § 691.66 Correspondence study... program of study offered by correspondence courses without terms, but not including any residential...

33 CFR 401.66 - Applicable laws.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Applicable laws. 401.66 Section 401.66 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Dangerous Cargo § 401.66 Applicable laws. (a) Vessels...

45 CFR 98.66 - Disallowance procedures.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 45 Public Welfare 1 2014-10-01 2014-10-01 false Disallowance procedures. 98.66 Section 98.66 Public Welfare Department of Health and Human Services GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Financial Management § 98.66 Disallowance procedures. (a) Any expenditures not made in accordance...

45 CFR 98.66 - Disallowance procedures.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 45 Public Welfare 1 2011-10-01 2011-10-01 false Disallowance procedures. 98.66 Section 98.66 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Financial Management § 98.66 Disallowance procedures. (a) Any expenditures not made in accordance...

45 CFR 98.66 - Disallowance procedures.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 45 Public Welfare 1 2010-10-01 2010-10-01 false Disallowance procedures. 98.66 Section 98.66 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Financial Management § 98.66 Disallowance procedures. (a) Any expenditures not made in accordance...

45 CFR 98.66 - Disallowance procedures.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 45 Public Welfare 1 2012-10-01 2012-10-01 false Disallowance procedures. 98.66 Section 98.66 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Financial Management § 98.66 Disallowance procedures. (a) Any expenditures not made in accordance...

45 CFR 98.66 - Disallowance procedures.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 45 Public Welfare 1 2013-10-01 2013-10-01 false Disallowance procedures. 98.66 Section 98.66 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Financial Management § 98.66 Disallowance procedures. (a) Any expenditures not made in accordance...

42 CFR 66.115 - Additional conditions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Additional conditions. 66.115 Section 66.115 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.115 Additional conditions. The Secretary may with...

42 CFR 66.115 - Additional conditions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Additional conditions. 66.115 Section 66.115 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.115 Additional conditions. The Secretary may with...

42 CFR 66.115 - Additional conditions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Additional conditions. 66.115 Section 66.115 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL RESEARCH SERVICE AWARDS Direct Awards § 66.115 Additional conditions. The Secretary may with...

27 CFR 5.66 - Comparative advertising.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Comparative advertising. 5.66 Section 5.66 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU... Spirits § 5.66 Comparative advertising. (a) General. Comparative advertising shall not be disparaging of a...

27 CFR 5.66 - Comparative advertising.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Comparative advertising. 5.66 Section 5.66 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU... Spirits § 5.66 Comparative advertising. (a) General. Comparative advertising shall not be disparaging of a...

27 CFR 5.66 - Comparative advertising.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Comparative advertising. 5.66 Section 5.66 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU... Spirits § 5.66 Comparative advertising. (a) General. Comparative advertising shall not be disparaging of a...

27 CFR 5.66 - Comparative advertising.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Comparative advertising. 5.66 Section 5.66 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU... Spirits § 5.66 Comparative advertising. (a) General. Comparative advertising shall not be disparaging of a...

27 CFR 5.66 - Comparative advertising.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Comparative advertising. 5.66 Section 5.66 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU... Spirits § 5.66 Comparative advertising. (a) General. Comparative advertising shall not be disparaging of a...

28 CFR 66.41 - Financial reporting.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Financial reporting. 66.41 Section 66.41..., Retention, and Enforcement § 66.41 Financial reporting. (a) General. (1) Except as provided in paragraphs (a..., for: (i) Submitting financial reports to Federal agencies, or (ii) Requesting advances or...

22 CFR 201.66 - Side payments.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Side payments. 201.66 Section 201.66 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT RULES AND PROCEDURES APPLICABLE TO COMMODITY TRANSACTIONS FINANCED BY USAID Price Provisions § 201.66 Side payments. Any payment which an importer makes to a...

22 CFR 201.66 - Side payments.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Side payments. 201.66 Section 201.66 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT RULES AND PROCEDURES APPLICABLE TO COMMODITY TRANSACTIONS FINANCED BY USAID Price Provisions § 201.66 Side payments. Any payment which an importer makes to a...

22 CFR 201.66 - Side payments.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Side payments. 201.66 Section 201.66 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT RULES AND PROCEDURES APPLICABLE TO COMMODITY TRANSACTIONS FINANCED BY USAID Price Provisions § 201.66 Side payments. Any payment which an importer makes to a...

22 CFR 201.66 - Side payments.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Side payments. 201.66 Section 201.66 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT RULES AND PROCEDURES APPLICABLE TO COMMODITY TRANSACTIONS FINANCED BY USAID Price Provisions § 201.66 Side payments. Any payment which an importer makes to a...

22 CFR 201.66 - Side payments.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Side payments. 201.66 Section 201.66 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT RULES AND PROCEDURES APPLICABLE TO COMMODITY TRANSACTIONS FINANCED BY USAID Price Provisions § 201.66 Side payments. Any payment which an importer makes to a...

10 CFR 1040.66 - Discrimination prohibited.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 4 2013-01-01 2013-01-01 false Discrimination prohibited. 1040.66 Section 1040.66 Energy... Practices § 1040.66 Discrimination prohibited. (a) General. (1) No qualified handicapped person shall, on the basis of handicap, be subjected to discrimination employment under any program or activity to...

10 CFR 1040.66 - Discrimination prohibited.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 4 2014-01-01 2014-01-01 false Discrimination prohibited. 1040.66 Section 1040.66 Energy... Practices § 1040.66 Discrimination prohibited. (a) General. (1) No qualified handicapped person shall, on the basis of handicap, be subjected to discrimination employment under any program or activity to...

10 CFR 1040.66 - Discrimination prohibited.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 4 2012-01-01 2012-01-01 false Discrimination prohibited. 1040.66 Section 1040.66 Energy... Practices § 1040.66 Discrimination prohibited. (a) General. (1) No qualified handicapped person shall, on the basis of handicap, be subjected to discrimination employment under any program or activity to...

10 CFR 1040.66 - Discrimination prohibited.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 4 2011-01-01 2011-01-01 false Discrimination prohibited. 1040.66 Section 1040.66 Energy... Practices § 1040.66 Discrimination prohibited. (a) General. (1) No qualified handicapped person shall, on the basis of handicap, be subjected to discrimination employment under any program or activity to...

28 CFR 66.41 - Financial reporting.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 28 Judicial Administration 2 2011-07-01 2011-07-01 false Financial reporting. 66.41 Section 66.41..., Retention, and Enforcement § 66.41 Financial reporting. (a) General. (1) Except as provided in paragraphs (a..., for: (i) Submitting financial reports to Federal agencies, or (ii) Requesting advances or...

7 CFR 3550.66 - Interest rate.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 15 2010-01-01 2010-01-01 false Interest rate. 3550.66 Section 3550.66 Agriculture... DIRECT SINGLE FAMILY HOUSING LOANS AND GRANTS Section 502 Origination § 3550.66 Interest rate. Loans will be written using the applicable RHS interest rate in effect at loan approval or loan closing...

7 CFR 3550.66 - Interest rate.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 15 2011-01-01 2011-01-01 false Interest rate. 3550.66 Section 3550.66 Agriculture... DIRECT SINGLE FAMILY HOUSING LOANS AND GRANTS Section 502 Origination § 3550.66 Interest rate. Loans will be written using the applicable RHS interest rate in effect at loan approval or loan closing...

7 CFR 3550.66 - Interest rate.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 15 2013-01-01 2013-01-01 false Interest rate. 3550.66 Section 3550.66 Agriculture... DIRECT SINGLE FAMILY HOUSING LOANS AND GRANTS Section 502 Origination § 3550.66 Interest rate. Loans will be written using the applicable RHS interest rate in effect at loan approval or loan closing...

7 CFR 3550.66 - Interest rate.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 15 2014-01-01 2014-01-01 false Interest rate. 3550.66 Section 3550.66 Agriculture... DIRECT SINGLE FAMILY HOUSING LOANS AND GRANTS Section 502 Origination § 3550.66 Interest rate. Loans will be written using the applicable RHS interest rate in effect at loan approval or loan closing...

28 CFR 66.11 - State plans.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 28 Judicial Administration 2 2010-07-01 2010-07-01 false State plans. 66.11 Section 66.11 Judicial... AGREEMENTS TO STATE AND LOCAL GOVERNMENTS Pre-Award Requirements § 66.11 State plans. (a) Scope. The statutes for some programs require States to submit plans before receiving grants. Under regulations...

7 CFR 3550.66 - Interest rate.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 15 2012-01-01 2012-01-01 false Interest rate. 3550.66 Section 3550.66 Agriculture... DIRECT SINGLE FAMILY HOUSING LOANS AND GRANTS Section 502 Origination § 3550.66 Interest rate. Loans will be written using the applicable RHS interest rate in effect at loan approval or loan closing...

Carbon-doped BN nanosheets for metal-free photoredox catalysis

PubMed Central

Huang, Caijin; Chen, Cheng; Zhang, Mingwen; Lin, Lihua; Ye, Xinxin; Lin, Sen; Antonietti, Markus; Wang, Xinchen

2015-01-01

The generation of sustainable and stable semiconductors for solar energy conversion by photoredox catalysis, for example, light-induced water splitting and carbon dioxide reduction, is a key challenge of modern materials chemistry. Here we present a simple synthesis of a ternary semiconductor, boron carbon nitride, and show that it can catalyse hydrogen or oxygen evolution from water as well as carbon dioxide reduction under visible light illumination. The ternary B–C–N alloy features a delocalized two-dimensional electron system with sp2 carbon incorporated in the h-BN lattice where the bandgap can be adjusted by the amount of incorporated carbon to produce unique functions. Such sustainable photocatalysts made of lightweight elements facilitate the innovative construction of photoredox cascades to utilize solar energy for chemical conversion. PMID:26159752

I-66--a case study

DOT National Transportation Integrated Search

1982-01-01

The Arlington-Fairfax County section of 1-66 is similar to many : urban highway projects, yet in many ways this project represents a : milestone in urban transportation planning. 1-66, not unlike many : others, required non-technical political groups...

Airport Flight Departure Delay Model on Improved BN Structure Learning

NASA Astrophysics Data System (ADS)

Cao, Weidong; Fang, Xiangnong

An high score prior genetic simulated annealing Bayesian network structure learning algorithm (HSPGSA) by combining genetic algorithm(GA) with simulated annealing algorithm(SAA) is developed. The new algorithm provides not only with strong global search capability of GA, but also with strong local hill climb search capability of SAA. The structure with the highest score is prior selected. In the mean time, structures with lower score are also could be choice. It can avoid efficiently prematurity problem by higher score individual wrong direct growing population. Algorithm is applied to flight departure delays analysis in a large hub airport. Based on the flight data a BN model is created. Experiments show that parameters learning can reflect departure delay.

28 CFR 66.31 - Real property.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 28 Judicial Administration 2 2012-07-01 2012-07-01 false Real property. 66.31 Section 66.31..., and Subawards § 66.31 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...

28 CFR 66.31 - Real property.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 28 Judicial Administration 2 2011-07-01 2011-07-01 false Real property. 66.31 Section 66.31..., and Subawards § 66.31 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...

28 CFR 66.31 - Real property.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Real property. 66.31 Section 66.31..., and Subawards § 66.31 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...

28 CFR 66.31 - Real property.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Real property. 66.31 Section 66.31..., and Subawards § 66.31 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...

33 CFR 66.01-45 - Penalties.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Penalties. 66.01-45 Section 66.01-45 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-45 Penalties. Any person...

33 CFR 66.01-40 - Exemptions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Exemptions. 66.01-40 Section 66.01-40 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-40 Exemptions. (a...

34 CFR 690.66 - Correspondence study.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 34 Education 4 2011-07-01 2011-07-01 false Correspondence study. 690.66 Section 690.66 Education... § 690.66 Correspondence study. (a) An institution calculates the Federal Pell Grant for a payment period for a student in a program of study offered by correspondence courses without terms, but not including...

28 CFR 66.25 - Program income.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Program income. 66.25 Section 66.25... Administration § 66.25 Program income. (a) General. Grantees are encouraged to earn income to defray program costs. Program income includes income from fees for services performed, from the use or rental of real...

33 CFR 66.01-40 - Exemptions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Exemptions. 66.01-40 Section 66.01-40 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-40 Exemptions. (a...

33 CFR 66.01-40 - Exemptions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Exemptions. 66.01-40 Section 66.01-40 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-40 Exemptions. (a...

33 CFR 66.01-45 - Penalties.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Penalties. 66.01-45 Section 66.01-45 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-45 Penalties. Any person...

33 CFR 66.01-45 - Penalties.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Penalties. 66.01-45 Section 66.01-45 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-45 Penalties. Any person...

33 CFR 66.01-40 - Exemptions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Exemptions. 66.01-40 Section 66.01-40 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-40 Exemptions. (a...

33 CFR 66.01-45 - Penalties.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Penalties. 66.01-45 Section 66.01-45 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-45 Penalties. Any person...

33 CFR 66.01-40 - Exemptions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Exemptions. 66.01-40 Section 66.01-40 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-40 Exemptions. (a...

33 CFR 66.01-45 - Penalties.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Penalties. 66.01-45 Section 66.01-45 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-45 Penalties. Any person...

7 CFR 201.66 - [Reserved

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 3 2010-01-01 2010-01-01 false [Reserved] 201.66 Section 201.66 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT...

32 CFR 842.66 - Applicable law.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 32 National Defense 6 2014-07-01 2014-07-01 false Applicable law. 842.66 Section 842.66 National... CLAIMS Foreign Claims (10 U.S.C. 2734) § 842.66 Applicable law. This paragraph provides guidance to determine the applicable law for assessment of liability. (a) A claim is settled under the law and standards...

32 CFR 842.66 - Applicable law.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 32 National Defense 6 2011-07-01 2011-07-01 false Applicable law. 842.66 Section 842.66 National... CLAIMS Foreign Claims (10 U.S.C. 2734) § 842.66 Applicable law. This paragraph provides guidance to determine the applicable law for assessment of liability. (a) A claim is settled under the law and standards...

32 CFR 842.66 - Applicable law.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 32 National Defense 6 2012-07-01 2012-07-01 false Applicable law. 842.66 Section 842.66 National... CLAIMS Foreign Claims (10 U.S.C. 2734) § 842.66 Applicable law. This paragraph provides guidance to determine the applicable law for assessment of liability. (a) A claim is settled under the law and standards...

32 CFR 842.66 - Applicable law.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 32 National Defense 6 2013-07-01 2013-07-01 false Applicable law. 842.66 Section 842.66 National... CLAIMS Foreign Claims (10 U.S.C. 2734) § 842.66 Applicable law. This paragraph provides guidance to determine the applicable law for assessment of liability. (a) A claim is settled under the law and standards...

32 CFR 842.66 - Applicable law.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 6 2010-07-01 2010-07-01 false Applicable law. 842.66 Section 842.66 National... CLAIMS Foreign Claims (10 U.S.C. 2734) § 842.66 Applicable law. This paragraph provides guidance to determine the applicable law for assessment of liability. (a) A claim is settled under the law and standards...

40 CFR 66.81 - Final action.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Final action. 66.81 Section 66.81... COLLECTION OF NONCOMPLIANCE PENALTIES BY EPA Final Action § 66.81 Final action. (a) A final Agency action... State action pursuant to part 67. (b) The actions listed in paragraph (a) of this section constitute...

44 CFR 66.2 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 44 Emergency Management and Assistance 1 2011-10-01 2011-10-01 false Definitions. 66.2 Section 66.2 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF HOMELAND SECURITY INSURANCE AND HAZARD MITIGATION National Flood Insurance Program CONSULTATION WITH LOCAL OFFICIALS...

44 CFR 66.2 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 44 Emergency Management and Assistance 1 2013-10-01 2013-10-01 false Definitions. 66.2 Section 66.2 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF HOMELAND SECURITY INSURANCE AND HAZARD MITIGATION National Flood Insurance Program CONSULTATION WITH LOCAL OFFICIALS...

44 CFR 66.2 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 44 Emergency Management and Assistance 1 2014-10-01 2014-10-01 false Definitions. 66.2 Section 66.2 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF HOMELAND SECURITY INSURANCE AND HAZARD MITIGATION National Flood Insurance Program CONSULTATION WITH LOCAL OFFICIALS...

44 CFR 66.2 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Definitions. 66.2 Section 66.2 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT AGENCY, DEPARTMENT OF HOMELAND SECURITY INSURANCE AND HAZARD MITIGATION National Flood Insurance Program CONSULTATION WITH LOCAL OFFICIALS...

27 CFR 6.6 - Administrative provisions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Administrative provisions. 6.6 Section 6.6 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS âTIED-HOUSEâ Scope of Regulations § 6.6 Administrative provisions. (a) General. The Act makes applicable the...

33 CFR 66.01-11 - Lights.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lights. 66.01-11 Section 66.01-11... TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-11 Lights. (a) Except for range and sector lights, each light approved as a private aid to navigation must: (1) Have at least the...

33 CFR 66.01-11 - Lights.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Lights. 66.01-11 Section 66.01-11... TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-11 Lights. (a) Except for range and sector lights, each light approved as a private aid to navigation must: (1) Have at least the...

33 CFR 66.01-11 - Lights.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Lights. 66.01-11 Section 66.01-11... TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-11 Lights. (a) Except for range and sector lights, each light approved as a private aid to navigation must: (1) Have at least the...

33 CFR 66.01-11 - Lights.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Lights. 66.01-11 Section 66.01-11... TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-11 Lights. (a) Except for range and sector lights, each light approved as a private aid to navigation must: (1) Have at least the...

33 CFR 66.01-11 - Lights.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Lights. 66.01-11 Section 66.01-11... TO NAVIGATION Aids to Navigation Other Than Federal or State § 66.01-11 Lights. (a) Except for range and sector lights, each light approved as a private aid to navigation must: (1) Have at least the...

Deposition of BN interphase coatings from B-trichloroborazine and its effects on the mechanical properties of SiC/SiC composites

NASA Astrophysics Data System (ADS)

Wu, Haitang; Chen, Mingwei; Wei, Xi; Ge, Min; Zhang, Weigang

2010-12-01

Boron nitride thin films were deposited on silicon carbide fibers by chemical vapor deposition at atmospheric pressure from the single source precursor B-trichloroborazine (Cl 3B 3N 3H 3, TCB). The film growth and structure, as a function of deposition temperature, hydrogen gas flow rate, and deposition time, were discussed. The deposition rate reaches a maximum at 1000 °C, then decreases with the increasing of temperature, and the apparent activation energy of the reaction is 127 kJ/mol. Above 1000 °C, gas-phase nucleation determines the deposition process. The deposited BN films were characterized by Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of BN interphase on the mechanical properties of the unidirectional SiC fiber-reinforced SiC matrix (SiC/SiC) composites was also investigated. The results show that the flexural strength of SiC/SiC composites with and without coating is 276 MPa and 70 MPa, respectively, which indicates that BN interphase coating deposited from B-trichloroborazine precursor can effectively adjust the fiber/matrix interface, thus causing a dramatic increase in the mechanical properties of the composites.

40 CFR 66.61 - Duty to pay.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Duty to pay. 66.61 Section 66.61... COLLECTION OF NONCOMPLIANCE PENALTIES BY EPA Payment § 66.61 Duty to pay. (a) Except where the owner or... who submits a petition pursuant to § 66.52 shall pay the penalty amount calculated by the owner or...

Gamma-ray Irradiation Effects on InAs/GaSb-based nBn IR Detector

DTIC Science & Technology

2011-01-01

very low noise performance. When properly passivated, conventional mercury cadmium telluride ( MCT )?based infrared detectors have been shown to...Gamma-ray Irradiation Effects on InAs/GaSb-based nBn IR Detector Vincent M. Cowan*1, Christian P. Morath1, Seth M. Swift1, Stephen Myers2...2Center for High Technology Materials, University of New Mexico, Albuquerque, NM 87106, USA ABSTRACT IR detectors operated in a space environment are

Wetting Behavior and Reactivity of Molten Silicon with h-BN Substrate at Ultrahigh Temperatures up to 1750 °C

NASA Astrophysics Data System (ADS)

Polkowski, Wojciech; Sobczak, Natalia; Nowak, Rafał; Kudyba, Artur; Bruzda, Grzegorz; Polkowska, Adelajda; Homa, Marta; Turalska, Patrycja; Tangstad, Merete; Safarian, Jafar; Moosavi-Khoonsari, Elmira; Datas, Alejandro

2017-12-01

For a successful implementation of newly proposed silicon-based latent heat thermal energy storage systems, proper ceramic materials that could withstand a contact heating with molten silicon at temperatures much higher than its melting point need to be developed. In this regard, a non-wetting behavior and low reactivity are the main criteria determining the applicability of ceramic as a potential crucible material for long-term ultrahigh temperature contact with molten silicon. In this work, the wetting of hexagonal boron nitride (h-BN) by molten silicon was examined for the first time at temperatures up to 1750 °C. For this purpose, the sessile drop technique combined with contact heating procedure under static argon was used. The reactivity in Si/h-BN system under proposed conditions was evaluated by SEM/EDS examinations of the solidified couple. It was demonstrated that increase in temperature improves wetting, and consequently, non-wetting-to-wetting transition takes place at around 1650 °C. The contact angle of 90° ± 5° is maintained at temperatures up to 1750 °C. The results of structural characterization supported by a thermodynamic modeling indicate that the wetting behavior of the Si/h-BN couple during heating to and cooling from ultrahigh temperature of 1750 °C is mainly controlled by the substrate dissolution/reprecipitation mechanism.

40 CFR 279.66 - Notices.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Notices. 279.66 Section 279.66 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR THE MANAGEMENT OF USED OIL Standards for Used Oil Burners Who Burn Off-Specification Used Oil for...

40 CFR 279.66 - Notices.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 28 2013-07-01 2013-07-01 false Notices. 279.66 Section 279.66 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR THE MANAGEMENT OF USED OIL Standards for Used Oil Burners Who Burn Off-Specification Used Oil for...

40 CFR 279.66 - Notices.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 28 2012-07-01 2012-07-01 false Notices. 279.66 Section 279.66 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR THE MANAGEMENT OF USED OIL Standards for Used Oil Burners Who Burn Off-Specification Used Oil for...

40 CFR 279.66 - Notices.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 27 2014-07-01 2014-07-01 false Notices. 279.66 Section 279.66 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR THE MANAGEMENT OF USED OIL Standards for Used Oil Burners Who Burn Off-Specification Used Oil for...

40 CFR 279.66 - Notices.

Code of Federal Regulations, 2011 CFR