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Sample records for bn tin hfc

  1. Tin

    NARCIS (Netherlands)

    Bulten, E.J.; Meinema, H.A.

    1991-01-01

    Tin is rather unique in the wide variety of its compounds and applications. Ever since the beginning of the bronze age the metal and its alloys have been of importance to mankind. When considering the impact of tin and its compounds on the environment, it has to be realized that no generalization ca

  2. FIRST-PRINCIPLES CALCULATION OF ELECTRONIC STRUCTURE,BONDING CHARACTERISTIC AND BONDING STRENGTH OF TiN(111)/BN/TiN(111) INTERFACE%第一性原理计算TiN(111)/BN/TiN(111)界面的电子结构、成键特性和结合强度

    Institute of Scientific and Technical Information of China (English)

    牛建钢; 王宝军; 王翠表; 田晓

    2009-01-01

    利用第-性原理计算方法研究了TiN(111)/BN/TiN(111)界面的16个理论界面构型.计算结果表明,最稳定界面构型为top-top-BN构型,此构型中B原子只与周围N原子成键,为四面体配位.同时计算了top-top-BN构型的电子结构和成键特性以及界面结合强度,结果表明,top-top-BN构型界面上的键为较强共价键,其界面结合强度比TiN(111)板层或TiN块体材料的(111)晶面间的结合强度大,说明此构型具有强界面特征.%The nanocomposite 'nc-TiN/a-BN' as a representation of the family of super-hard nitride-based nanocomposites, which is a nanocomposite thin film material, exhibits a significant hardness enhancement as compared with the pure constituents. In this paper, first-principles calcula-tions were performed to investigate the role of interfaces in the nanocomposite 'nc-TiN/a-BN' , to which less attention has been paid up to now. In order to determine theoretically the stable interface configuration in 'nc-TiN/a-BN' , 16 possible theoretical TiN(111)/BN/TiN(111) sandwich interface configurations have been constructed based on the structure characteristic of 'nc-TiN/a-BN' . It is found in this calculation that the most favorable interface configuration is 'top-top-BN' , which is closely related to each B atom covalently bonding to its tetrahedrally coordinated N atoms in it. Its electronic structure is calculated. The calculated results show that the bonds at the interface in 'top-top-BN' configuration are covalent. Its interface bonding strength is higher than that between two 111 crystalline planes in slab TiN or bulk TiN.

  3. THERMODYNAMIC PROPERTIES OF SELECTED HFC REFRIGERANTS

    Science.gov (United States)

    Hydrofluorocarbon (HFC) refrigerants are possible alternatives to replace ozone-depleting chlorofluorocarbon and hydrochlorofluorocarbon (HCFC) refrigerants. The flammability of a proposed new refrigerant is a major consideration in assessing its utility for a particular applicat...

  4. Mitigating Noise for the HFC Upstream Channel

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Provides the methods to mitigate noise for the upstream channel over HFC networks. We first briefly discuss the HFC network topology, then we describe the sources of noise, the mechanism to form noise, the characteristics of their spectrum, etc. In light of the mechanism to form noise and the characteristics of their spectrum, many methods are put forward in this paper. These methods are evaluated with implementation.

  5. Microstructure Evolution of Ti/BN Powder Blend during Ball Milling and Heat Treatment

    Institute of Scientific and Technical Information of China (English)

    Jianlin LI; Keao HU; Yong ZHONG

    2001-01-01

    Ball milled Ti/BN composite powder was prepared by high energy ball milling for 40 h, using Ti and BN (the molar ratio of Ti/BN is 3:2) as starting materials. The as-milled composite powder consists of TiN, Ti and amorphous phase. TiN formed while the milled powder was annealed at 400℃. The heat treatment at 700℃ led to the formation of TiB2 and TiB. The nanocrystalline Ti and amorphous phase converted to TiN and TiB2 when the powder was heated to 1300℃.

  6. Structure of BN Nanotubes

    Science.gov (United States)

    Celik-Aktas, Ayten; Tao, Jing; Zuo, Jian-Min

    2004-03-01

    Boron nitride (BN) nanotubes have been the subject of intensive scientific study in recent years due to their unique properties. BN nanotubes have uniform wide gap semiconducting properties regardless of their chirality and diameter [1]. On the other hand electrical properties of carbon nanotubes (CNTs) depend on their chirality. This unique difference between BN and CNTs makes BN nanotubes a better candidate for nano electronics and/or other nano technology applications. HRTEM and nano area electron diffraction (NAD) studies have been conducted to better understand the microstructure of BN nanotubes. In addition to TEM analysis we would like to present the results of image simulations and compare the NAD patterns with the simulated diffraction patterns. Preliminary results suggest that the BN nanotubes that have been investigated in this study showed overwhelmingly near zigzag chirality. Average diameter of the BN tubes are about 35-40 nm. Regular patches of perfect crystals have been observed along the length of the tubes except tubes with very large diameters (Dng 150 nm). Other regions of the BN nanotubes were quite defective. CNT templates have been employed in the synthesis of our samples. [1] X. Blasé, A. Rubio, S.G. Louie, M.L. Cohen, Europhysics Letters, 28 (1994) 335.

  7. Research on Transport Properties of HFC-227ea

    Institute of Scientific and Technical Information of China (English)

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

    2001-01-01

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

  8. Telemetry systems on cable tv networks (HFC); Sistema de telemetria sobre redes de TV a cabo (HFC)

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, Christina [Furukawa Industrial S.A. Produtos Eletricos, Curitiba, PR (Brazil). E-mail: christi@furukawa.com.br

    1999-07-01

    This paper presents a telemetry system on the cable TV (Hybrid Fiber Coaxial network). This system conducts remote electric power using the HFC network as physical way. The telemetry system represents an aggregated value on this type of network. The HFC network is a network prepared for data transport under the concept of a future wide single band network.

  9. Transmission design in a multimode HFC network

    Science.gov (United States)

    Cambron, G. Keith

    1996-11-01

    Contemporary hybrid fiber coaxial (HFC) networks are capable of supporting a wide range of services including traditional analog video, telephony, digital video, and data services. Each service has unique performance or service requirements. This contribution examines transmission design for one such network. Pacific Bell's advanced communications network (ACN). The design methodology begins with a set of end to end service quality objectives. Network impairments, such as noise, distortion and delay, are allocated across the network elements using a set of standard network models. These models are a representative set of the actual field designs and bound the network operating parameters. Network components, headend equipment, and customer premises equipment are specified analytically or characterized empirically in relationship to the chosen impairment set. The component parameters are then included in analytical models to estimate overall network performance. In addition to the forward path transmission considerations examined by traditional coaxial network designers, other dimensions including power consumption, traffic demand, and message latency are taken into account. Analytical models are used to estimate the effects of multiple modulation schemes within the unified network. The variability introduced by on demand services such as telephony and interactive digital services changes the base computational domain from deterministic models to stochastic ones. These models are then used to set operating parameters at measurable points throughout the network for proof of performance prior to turn up, and for ongoing performance monitoring. For closure, empirical results are compared with model projections as a way of verifying and improving the predictive models.

  10. Lubricants for HFC-134a Compatible Rotary Compressors

    Science.gov (United States)

    Takaichi, Kenji; Sakai, Hisakazu

    In replacing CFC-12 with HFC-134a for refrigerator compressors, the compatibility with lubricating oil, and lubrication in general, are of major concern. HFC-134a dose not have adequate solubility with current lubricating oils because of its molecular structure. Current oils also do not provide enough lubricating action when using HFC-134a. A new oil and new materials have to be utilized in order to use HFC-134a. Developing a new lubricating oil involved numerous tests of different combinations of many polyolester synthetic oils and additives. One of the pre-evaluated methods was pursued via sealed tube tests. Lubricated parts were selected by studies involving a plane-on-roller type of wear test machine and by analyzing the traces of acid material commonly created during the lubricating action. The matrices of new lubricating oils and new lubricated materials were estimated based on durability tests conducted on compressors and refrigerators. Results showed that polyolester synthetic oils having a low total acid value and including certain quantities of additives did not break down into a tar-like substance and they did not produce composite particles in the operating compressors and refrigerators. The study also found that ceramics and anti-corrosion alloy steel possessed good adrasion-reducing qualities. Based on our evaluation, we will implement compressor reliability tests and apply HFC-134a to rotary compressors for refrigerators.

  11. Performance and heat transfer characteristics of HFC-134a and CFC-12 in a water chiller

    Energy Technology Data Exchange (ETDEWEB)

    Devotta, S.; Parande, M.G.; Patwardhan, V.R. [National Chemical Lab., Pune (India)

    1998-07-01

    A water chiller with an open reciprocating compressor has been used to comparatively assess the performance of HFC-134a with reference to CFC-12 under as close to identical conditions as possible. Performance characteristics of the chiller under retrofit conditions show that HFC-134a offers better cooling load and coefficients of performance vis-a-vis CFC-12 for identical operating conditions. Further heat transfer analysis of data for the condenser shows that the condensing heat transfer coefficients for HFC-134a are superior to CFC-12. The better performance of HFC-134a may be ascribed to the better heat transfer coefficient of HFC-134a over CFC-12. (Author)

  12. HCC-240fa氟化合成HFC-245fa技术进展%Progress on Synthesizing HFC -245fa by Fluorinating HCC -240fa

    Institute of Scientific and Technical Information of China (English)

    张国利; 杨会娥; 张文庆; 赵新堂

    2009-01-01

    HFC-245fa作为ODS发泡剂HCHC-141b和CFC-11的良好替代品,具有很好工业前景.全面综述了以HCC-240fa为原料合成HFC-245fa的各种工艺,并对HFC-245fa粗品的提纯进行详细的讨论.

  13. HFC-134a Export Expansion in Great Urgency

    Institute of Scientific and Technical Information of China (English)

    Zhang Lizhe

    2007-01-01

    @@ 1,1,1,2-tetrafluoroethane (HFC- 134a) is a new refrigerant. It has the features of no toxicity, no odor, no color, no inflammability, no explosion, good thermal stability and stable chemical property. Its ODP (ozone depletion potential) is zero. It has a refrigerating ability similar to F12.

  14. (Fuzzy Ideals of BN-Algebras

    Directory of Open Access Journals (Sweden)

    Grzegorz Dymek

    2015-01-01

    set to be a fuzzy ideal are given. The relationships between ideals and fuzzy ideals of a BN-algebra are established. The homomorphic properties of fuzzy ideals of a BN-algebra are provided. Finally, characterizations of Noetherian BN-algebras and Artinian BN-algebras via fuzzy ideals are obtained.

  15. Exploratory report Tin and tin compounds

    NARCIS (Netherlands)

    Slooff W; Bont PFH; Hesse JM; Annema JA

    1993-01-01

    In the Netherlands tin is produced from concentrate and secondary production (about 3,500 tonnes Sn per year), whereas about 5,000 tonnes Sn per year is applied. Of this amount about 4,200 tonnes is applied as inorganic tin (most for the manufacturing of tin plate) and about 800 tonnes Sn is applie

  16. Evaporation of refrigerant HFC 407C on plain tubes or at an improved surface; Evaporation du refrigerant HFC 407C sur des tubes lisses ou a surface amelioree

    Energy Technology Data Exchange (ETDEWEB)

    Zuercher, O.; Favrat, D.; Thome, J.R.; Kattan, N.; Nidegger, E. [Ecole polytechnique federale, Lab. d`energetique industrielle, Lausanne (Switzerland)

    1996-11-15

    The substitution of CFC refrigerants in refrigeration systems, heat pumps and organic Rankine cycles for heat recovery, requires good methods for predicting heat transfer of substitute fluids. The measurements in the LENI test facility (concentric tubes with water flowing in a counter-current flow) with HFC 407C, HFC 134a, HCFC 123, HFC 404a and HFC/HCFC 402A provide a new data bank for new refrigerants, and allow a coherent comparison with old refrigerants CFC 11, CFC 12, CFC/HCFC 502 and with existing correlations. The existing correlations were found to be inadequate. Because of this work, an improved flow pattern map and flow boiling model were developed, which resulted in a substantial progress in the accurate predict of heat transfer in plain, horizontal tubes for refrigerants without oil. The Kattan et al. correlation was programmed to calculate and compare predicted heat transfer coefficients to the new HFC 407C test data. The flow pattern map proposed by Kattan et al. was also programmed and compared to flow regimes observed for HFC 407C. It predicted the HFC 407C flow pattern data quite accurately. The original objective of the HFC 407C measurements was the validation of the Kattan et al. correlation applied to a zeotropic refrigerant blend. Local flow boiling heat transfer coefficients were measured for HFC 407C evaporating inside a microfin and a plain tube. In addition, microfin heat transfer augmentation relative to a plain tube was investigated. The presence of oil in the evaporator had a complex effect on heat transfer coefficients. Local flow boiling heat transfer coefficients were measured for refrigerant HFC 407C ester oil mixtures (Mobil EAL Arctic 68). A new thermodynamic approach for modeling mixtures of zeotropic refrigerant blends and lubricating oils was also developed. (author) figs., tabs., 14 refs.

  17. HFC-134A and HCFC-22 supermarket refrigeration demonstration and laboratory testing. Phase I. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-04-01

    Aspen Systems and a team of nineteen agencies and industry participants conducted a series of tests to determine the performance of HFC-134a, HCFC-22, and CFC-502 for supermarket application. This effort constitutes the first phase of a larger project aimed at carrying out both laboratory and demonstration tests of the most viable HFC refrigerants and the refrigerants they replace. The results of the Phase I effort are presented in the present report. The second phase of the project has also been completed. It centered on testing all viable HFC replacement refrigerants for CFC-502. These were HFC-507, HFC-404A, and HFC-407A. The latter results are published in the Phase II report for this project. As part of Phase I, a refrigeration rack utilizing a horizontal open drive screw compressor was constructed in our laboratory. This refrigeration rack is a duplicate of one we have installed in a supermarket in Clifton Park, NY.

  18. Analysis of Potential for HFC-23 Emission Reduction in China’s Fluorine Chemical Industry

    Institute of Scientific and Technical Information of China (English)

    LIN Hui; CUI Yong-Li; YANG Li-Rong

    2013-01-01

    China is one of the major producers of chlorodifluoromethane (HCFC-22) in the world. A large amount of fluoroform (HFC-23) is emitted during the production of HCFC-22. Emission factors of HFC-23 were calculated in accordance with the monitoring reports of eleven HFC-23 clean development mechanism (CDM) projects in China and the HFC-23 emissions in 2000-2010 as well as that in 2011-2020 were estimated and projected, respectively. It is expected that, by the end of 2020, emissions of HFC-23 in China will be as much as 230 Mt CO2-eq. If HCFC-22 producers voluntarily reduced HFC-23 emissions, it would contribute 3.2%-3.6%to the national CO2 emission reduction target for 2020.

  19. CFC and HFC recycling equipments: Test performances; Qualificazione di dispositivi per il riciclaggio dei CFC e degli HFC

    Energy Technology Data Exchange (ETDEWEB)

    Picini, P.; Caropreso, G.; Cicoli, G.; Posarelli, M. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente; Pallotti, P. [ICF, Industria Componenti Frigoriferi Srl, Bologna (Italy)

    1996-12-01

    Actual regulatory conditions about ozone layer depleting chemicals set problems on their disposal and on the management of plants still using illegal CFCs. Anyway fluids that will replace CFCs (i.e. HFCs) will not be allowed to be spread into the atmosphere, due to their high costs and to the greenhouse effect. A viable solution would be the recovery, purification and recycle of contaminated fluids. ENEA (National Agency for New Technology, Energy and the Environment), in cooperation with ICF (Industria Componenti Frigoriferi) Company leader in the field of air refrigerating and conditioning, patented a device able to extract, to clean and to recycle CFC 12 and HFC 134a in the refrigerating systems. This paper presents experimental data from the qualification tests on a device performing the above mentioned operations regarding systems that use HFC 134a as process fluid.

  20. Efficient noble metal nanocatalysts supported on HfC(001 for O2 dissociation

    Directory of Open Access Journals (Sweden)

    Shiyan Wang

    2017-03-01

    Full Text Available The adsorption and dissociation of O2 on the M4 (M=Au, Pd, Pt clusters supported on HfC(001 (Hafnium Carbide are investigated using ab initio density functional theory calculations. The geometric and electronic structures are analyzed in detail. It is found that the dissociation barriers of O2 on Au4/HfC(001 (0.26 eV, Pd4/HfC(001 (0.49 eV and Pt4/HfC(001 (0.09 eV are much smaller than those on the clean surfaces of HfC(001 (1.60 eV, Au(111 (1.37 eV, Pd(111 (1.0 and 0.91 eV and Pt(111 (0.27–0.7 eV, respectively. The low dissociation barriers imply that the Pt4/HfC(001 exhibits the highest catalytic activity for O2 dissociation, and the Au4/HfC(001 and Pd4/HfC(001 may also be possible substitutes with lower cost for the current Pt/C catalyst for O2 dissociation. The present study is conductive to designing new efficient noble metal catalyst using HfC support for efficiently promoting O2 dissociation.

  1. Efficient noble metal nanocatalysts supported on HfC(001) for O2 dissociation

    Science.gov (United States)

    Wang, Shiyan; Zhang, Xilin; Zhang, Yanxing; Mao, Jianjun; Yang, Zongxian

    2017-03-01

    The adsorption and dissociation of O2 on the M4 (M=Au, Pd, Pt) clusters supported on HfC(001) (Hafnium Carbide) are investigated using ab initio density functional theory calculations. The geometric and electronic structures are analyzed in detail. It is found that the dissociation barriers of O2 on Au4/HfC(001) (0.26 eV), Pd4/HfC(001) (0.49 eV) and Pt4/HfC(001) (0.09 eV) are much smaller than those on the clean surfaces of HfC(001) (1.60 eV), Au(111) (1.37 eV), Pd(111) (1.0 and 0.91 eV) and Pt(111) (0.27-0.7 eV), respectively. The low dissociation barriers imply that the Pt4/HfC(001) exhibits the highest catalytic activity for O2 dissociation, and the Au4/HfC(001) and Pd4/HfC(001) may also be possible substitutes with lower cost for the current Pt/C catalyst for O2 dissociation. The present study is conductive to designing new efficient noble metal catalyst using HfC support for efficiently promoting O2 dissociation.

  2. (Fuzzy) Ideals of BN-Algebras

    Science.gov (United States)

    Walendziak, Andrzej

    2015-01-01

    The notions of an ideal and a fuzzy ideal in BN-algebras are introduced. The properties and characterizations of them are investigated. The concepts of normal ideals and normal congruences of a BN-algebra are also studied, the properties of them are displayed, and a one-to-one correspondence between them is presented. Conditions for a fuzzy set to be a fuzzy ideal are given. The relationships between ideals and fuzzy ideals of a BN-algebra are established. The homomorphic properties of fuzzy ideals of a BN-algebra are provided. Finally, characterizations of Noetherian BN-algebras and Artinian BN-algebras via fuzzy ideals are obtained. PMID:26125050

  3. Investigation into the conditions under which HFC134a may become flammable.

    CSIR Research Space (South Africa)

    Kramers, AP

    2002-01-01

    Full Text Available flammability limit of a propane/HFC134a/air mixture (Schröeder 1995). The contribution of the lubricant to the flammability of HFC134a was not well understood. The literature review and findings of the Tau Tona accident report (Department of Minerals... are also highly dependent on the type of ignition source and the volume of the vessel used. 2.1.2 Lubricants used with HFC134a Lubricants used with refrigerant 134a are mineral oils; alkyl benzenes; dibasic, polybasic and polyol esters...

  4. HFC双向宽带网%HFC-way Broadband Network

    Institute of Scientific and Technical Information of China (English)

    刘前

    2015-01-01

    With the rapid advent of the information society, information exchange has already become the most important resource, it is mainly for the three forms of images, integrated, intelligent and personal, all-digital service support. HFC network is a better access network, the best solution is the information superhighway broadband access networks.%信息交换已然成最重要的资源,它主要表现为图像、声音和数据3种形式。信息网络发展方向是数字化、综合化、智能化和个人化,支持全数字化业务。HFC网是目前较好的接入网,是信息高速公路宽带接入网的最佳方案。

  5. Electrical transport properties of (BN)-rich hexagonal (BN)C semiconductor alloys

    OpenAIRE

    2014-01-01

    The layer structured hexagonal boron nitride carbon semiconductor alloys, h-(BN)C, offer the unique abilities of bandgap engineering (from 0 for graphite to ∼6.4 eV for h-BN) and electrical conductivity control (from semi-metal for graphite to insulator for undoped h-BN) through alloying and have the potential to complement III-nitride wide bandgap semiconductors and carbon based nanostructured materials. Epilayers of (BN)-rich h-(BN)1-x(C2)x alloys were synthesized by metal-organic chemical ...

  6. HFC-23 (CHF3 emission trend response to HCFC-22 (CHClF2 production and recent HFC-23 emission abatement measures

    Directory of Open Access Journals (Sweden)

    R. G. Prinn

    2010-08-01

    Full Text Available HFC-23 (also known as CHF3, fluoroform or trifluoromethane is a potent greenhouse gas (GHG, with a global warming potential (GWP of 14 800 for a 100-year time horizon. It is an unavoidable by-product of HCFC-22 (CHClF2, chlorodifluoromethane production. HCFC-22, an ozone depleting substance (ODS, is used extensively in commercial refrigeration and air conditioning, in the extruded polystyrene (XPS foam industries (dispersive applications and also as a feedstock in fluoropolymer manufacture (a non-dispersive use. Aside from small markets in specialty uses, HFC-23 has historically been considered a waste gas that was, and often still is, simply vented to the atmosphere. Efforts have been made in the past two decades to reduce HFC-23 emissions, including destruction (incineration in facilities in developing countries under the United Nations Framework Convention on Climate Change's (UNFCCC Clean Development Mechanism (CDM, and by process optimization and/or voluntary incineration by most producers in developed countries. We present observations of lower-tropospheric mole fractions of HFC-23 measured by "Medusa" GC/MSD instruments from ambient air sampled in situ at the Advanced Global Atmospheric Gases Experiment (AGAGE network of five remote sites (2007–2009 and in Cape Grim air archive (CGAA samples (1978–2009 from Tasmania, Australia. These observations are used with the AGAGE 2-D atmospheric 12-box model and an inverse method to produce model mole fractions and a "top-down" HFC-23 emission history. The model 2009 annual mean global lower-tropospheric background abundance is 22.6 (±0.2 pmol mol−1. The derived HFC-23 emissions show a "plateau" during 1997–2003, followed by a rapid ~50% increase to a peak of 15.0 (+1.3/−1.2 Gg/yr in 2006. Following this peak, emissions of HFC-23 declined rapidly to 8.6 (+0.9/−1.0 Gg/yr in 2009, the lowest annual emission of the past 15 years. We derive a 1990–2008 "bottom-up" HFC-23 emission history

  7. HFC-23 (CHF3 emission trend response to HCFC-22 (CHClF2 production and recent HFC-23 emission abatement measures

    Directory of Open Access Journals (Sweden)

    R. G. Prinn

    2010-05-01

    Full Text Available HFC-23 (also known as CHF3, fluoroform or trifluoromethane is a potent greenhouse gas (GHG, with a global warming potential (GWP of 14 800 for a 100-year time horizon. It is an unavoidable by-product of HCFC-22 (CHClF2, chlorodifluoromethane production. HCFC-22, an ozone depleting substance (ODS, is used extensively in commercial refrigeration and air conditioning, in the extruded polystyrene (XPS foam industries (dispersive applications and also as a feedstock in fluoropolymer manufacture (a non-dispersive use. Aside from small markets in specialty uses, HFC-23 has historically been considered a waste gas that was, and often still is, simply vented to the atmosphere. Efforts have been made in the past two decades to reduce HFC-23 emissions, including destruction (incineration in facilities in developing countries under the United Nations Framework Convention on Climate Change's (UNFCCC Clean Development Mechanism (CDM, and by process optimization and/or voluntary incineration by most producers in developed countries. We present observations of lower-tropospheric mole fractions of HFC-23 measured by "Medusa" GC/MSD instruments from ambient air sampled in situ at the Advanced Global Atmospheric Gases Experiment (AGAGE network of five remote sites and in Cape Grim air archive (CGAA samples (1978–2009 from Tasmania, Australia. These observations are used with the AGAGE 2-D atmospheric 12-box model and an inverse method to produce model mole fractions and a "top-down" HFC-23 emission history. The model 2009 annual mean global lower-tropospheric background abundance is 22.8 (±0.2 pmol mol−1. The derived HFC-23 emissions show a "plateau" during 1997–2003, followed by a rapid ~50% increase to a peak of 15.0 (+1.3/−1.2 Gg/yr in 2006. Following this peak, emissions of HFC-23 declined rapidly to 8.6 (+0.9/−1.0 Gg/yr in 2009, the lowest annual emission of the past 15 years. We derive a 1990–2008 "bottom-up" HFC-23 emission history using data

  8. HFC-134a refrigerant gas hydrate formation process and RIN model

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, the macroscopic visualization experiments of HFC-134a refrigerant gas hydrate formation are investigated. According to the macroscopic photos and Mori's microscopic photos of HFC-134a hydrate formation process, the mechanism of gas hydrate formation is analyzed.A random inducement nucleation model is presented to describe the hydrate formation process. The factors affecting the fractal growth dimension in the model, such as step,branch increment and angle, are discussed.``

  9. HFC-134a emissions from mobile air conditioning in China from 1995 to 2030

    Science.gov (United States)

    Su, Shenshen; Fang, Xuekun; Li, Li; Wu, Jing; Zhang, Jianbo; Xu, Weiguang; Hu, Jianxin

    2015-02-01

    Since 1995, 1,1,1,2-tetrafluoroethane (CH2FCF3, HFC-134a) has become the most important substitute of CFC-12 in mobile air conditioning (MAC) in China and MAC sector has dominated all the emissions of HFC-134a. In this study, we developed an accurate, updated and county-level inventory of the HFC-134a emissions from MAC in China for the period of 1995-2030 with an improved bottom-up method. Our estimation indicated that the total HFC-134a emissions kept growing at increase rates of ∼100% per year for 1995-2000 and ∼34% per year for 2001-2010. In 2010, HFC-134a emissions from MAC in China reached 16.7 Gg (10.5-22.7 Gg at 95% confidential interval), equivalent to 21.7 Tg CO2 (CO2-eq). Furthermore, the emissions in China estimated in this study accounted for 9.8% of global HFC-134a emissions and 29.0% of total emissions from Non-Annex_I countries in 2010. Due to the more advanced social-economic conditions and more intensive ownership of automobiles, greater HFC-134a were observed to come from big cities in East China. Under a Business-as-usual (BAU) Scenario, projected emissions will grow to 89.4 (57.9-123.9) Gg (about 75.3-161.1 Tg CO2-eq) in 2030, but under an Alternative Scenario, 88.6% of the projected emissions under BAU scenario could be curbed. Our estimation demonstrates huge emission mitigation potential of HFC-134a in China's MAC sector.

  10. Mechanical properties of metal decorated graphyne, graphyne-BN-yne, and BN-yne sheets

    CERN Document Server

    Ahmadi, Aidin; Nasiri, Mahdi Faghih; Sabeti, Moones

    2016-01-01

    In this paper, the mechanical properties of two-dimensional structures of metal decoration systems of simple graphyne (CC), analogous system of BN sheet (BN-yne), also the graphyne-BN sheet (CC-BN-yne) was investigated. The properties such as Young and Bulk moduli were studied using Energy-Strain correlation. We introduced calculations based on density functional theory (DFT); the generalized gradient approximation (GGA) framework was used in this regard. The results demonstrated very competitive values for Young and Bulk moduli of the Pt decorated CC and BN-yne. However, the CC-BN-yne structure defined around 80% of Young and 77% of Bulk values of that of pure structures. Also Na decorated ones were examined and the results showed the same trend for all three structures. The CC-BN-yne defined the lowest values for either Young or Bulk moduli.

  11. (Vapour + liquid) equilibria of the {l_brace}trifluoromethane (HFC-23) + propane{r_brace} and {l_brace}trifluoromethane (HFC-23) + n-butane{r_brace} systems

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Mincheol; Yun, Yongju [School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Shin, Moon Sam [Department of Cosmetic Science, Chungwoon University, Chungnam 350-701 (Korea, Republic of); Kim, Hwayong [School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of)], E-mail: hwayongk@snu.ac.kr

    2009-12-15

    Isothermal (vapour + liquid) equilibrium data were measured for the two systems, {l_brace}trifluoromethane (HFC-23) + propane{r_brace} and {l_brace}trifluoromethane (HFC-23) + n-butane{r_brace}, at temperatures ranging from 283.15 K to 313.15 K at 10 K intervals. These experiments were performed with a circulating-type apparatus and on-line gas chromatography. Experimental data were well correlated by the Peng-Robinson equation of state using the Wong-Sandler mixing rules and the NRTL model.

  12. Deposition of B{sub 4}C/BCN/c-BN multilayered thin films by r.f. magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Bejarano, G. [Laboratorio de Recubrimientos Duros del CDT-ASTIN SENA, Cali (Colombia); Caicedo, J.M. [Laboratorio de Recubrimientos Duros del CDT-ASTIN SENA, Cali (Colombia); Baca, E. [Departamento de Fisica, Universidad del Valle, A.A. 25360, Cali (Colombia); Prieto, P. [Departamento de Fisica, Universidad del Valle, A.A. 25360, Cali (Colombia)]. E-mail: pprieto@calima.univalle.edu.co; Balogh, A.G. [Institute for Material Science, Darmstadt University of Technology (Germany); Enders, S. [Max Plank Institute, Department of Material Research, Stuttgart (Germany)

    2006-01-03

    Thin films of cubic boron nitride (c-BN) and B{sub 4}C/BCN/c-BN multilayers, were deposited by r.f. (13.56 MHz) multi-target magnetron sputtering from high-purity (99.99%) h-BN and a (99.5%) B{sub 4}C targets, in an Ar (90%)/N{sub 2} (10%) gas mixture. Films were deposited onto silicon substrates with (100) orientations at 300 {sup o}C, with r.f. power density near 7 W/cm{sup 2}. In order to obtain the highest fraction of the c-BN phase, an r.f. substrate bias voltage between - 100 and - 300 V was applied during the initial nucleation process and - 50 to - 100 V during the film growth. Additionally, B{sub 4}C and BCN films were deposited and analyzed individually. For their deposition, we varied the bias voltage of the B{sub 4}C films between - 50 and - 250 V, and for the BCN coatings, the nitrogen gas flow from 3% to 12%. A 300-nm-thick TiN buffer layer was first deposited to improve the adhesion of all samples. X-ray diffraction patterns revealed the presence of c-BN (111) and h-BN phases. FTIR spectroscopy measurements indicate the presence of a peak at 780 cm{sup -} {sup 1} referred to as 'out-of-plane' h-BN vibration mode; another peak at 1100 cm{sup -} {sup 1} corresponds to the c-BN TO mode and the 'in-plane' vibration mode of the h-BN at 1400 cm{sup -} {sup 1}. BN films deposited at 300 deg. C at a pressure of 4.0 Pa and under - 150 V of nucleation r.f. bias, applied for 35 min, presented the highest c-BN fraction, near 85%. By using 32 layers, it was possible to deposit a 4.6-{mu}m-thick c-BN film with adequate mechanical properties and good adhesion to the substrate.

  13. HFC245fa热物性数学模型及其lgp-h图%Modeling of Thermodynamic Properties and Transport Properties of HFC245fa and its lgp-h Diagram

    Institute of Scientific and Technical Information of China (English)

    张淑彦; 李岩; 张吉礼

    2011-01-01

    高温热泵适宜采用高温工质.HFC245fa被普遍认为是替代CFC11和HCFC123的HFCs类新型高温工质.本文以试验数据为基础,采用Soave-Redlich-Kwong方程,辩识了HFC245fa的状态方程;采用Wagner模型拟合了HFC245fa的饱和蒸汽压力模型;基于基团原理,建立了HFC245fa的气体定压比热容模型;由Clausius-Clapegron方程得到了HFC245fa的汽化潜热模型;利用多项式模型,拟合了HFC245fa的粘度﹑导热系数等迁移性质模型;最后,根据上述模型,绘制其lgp-h图.结果表明,上述模型和图表的精度能够满足HFC245fa在设备研发和制造中的实际应用.%High temperature work fluids are greatly suitable for the high temperature heat pump,and HFC245fa has been widely considered as a new high temperature work fluid to substitute CFC11 and HCFC123.Based on the experimental results of HFC245fa ,thermodynamic properties models and transport properties models of HFC245fa have been regressed.Namely ,the state equation and saturation vapor pressure equation of HFC245fa have been regressed respectively on the basis of Soave-RedlichKwong model and Wagner model.The vapor isotonic ratio specific heat model of HFC245fa has been created by the group theory.The evaporation latent heat model of HFC245fa has been finished by Clausius-Clapegron equation.Coefficient of viscosity,coefficient of heat transfer and other transport properties equations of HFC245fa have been built by various polynomial models.Finally,the lgp-h diagram of HFC245fa has been drawn out according to the built thermedynamic properties models.The error analyzed results of the thermodynamic properties models and transport properties models of HFC245fa show that all the models can meet the calculation precision demands of its applications in the development of the heat pump.

  14. Modeling tin whisker growth.

    Energy Technology Data Exchange (ETDEWEB)

    Weinberger, Christopher Robert

    2013-08-01

    Tin, lead, and lead-tin solders are the most commonly used solders due to their low melting temperatures. However, due to the toxicity problems, lead must now be removed from solder materials. This has lead to the re-emergence of the issue of tin whisker growth. Tin whiskers are a microelectronic packaging issue because they can lead to shorts if they grow to sufficient length. However, the cause of tin whisker growth is still not well understood and there is lack of robust methods to determine when and if whiskering will be a problem. This report summarizes some of the leading theories on whisker growth and attempts to provide some ideas towards establishing the role microstructure plays in whisker growth.

  15. Modeling tin whisker growth.

    Energy Technology Data Exchange (ETDEWEB)

    Weinberger, Christopher Robert

    2013-08-01

    Tin, lead, and lead-tin solders are the most commonly used solders due to their low melting temperatures. However, due to the toxicity problems, lead must now be removed from solder materials. This has lead to the re-emergence of the issue of tin whisker growth. Tin whiskers are a microelectronic packaging issue because they can lead to shorts if they grow to sufficient length. However, the cause of tin whisker growth is still not well understood and there is lack of robust methods to determine when and if whiskering will be a problem. This report summarizes some of the leading theories on whisker growth and attempts to provide some ideas towards establishing the role microstructure plays in whisker growth.

  16. Bias induced modulation of electrical and thermal conductivity and heat capacity of BN and BN/graphene bilayers

    Science.gov (United States)

    Chegel, Raad

    2017-04-01

    By using the tight binding approximation and Green function method, the electronic structure, density of state, electrical conductivity, heat capacity of BN and BN/graphene bilayers are investigated. The AA-, AB1- and AB2- BN/graphene bilayers have small gap unlike to BN bilayers which are wide band gap semiconductors. Unlike to BN bilayer, the energy gap of graphene/BN bilayers increases with external field. The magnitude of the change in the band gap of BN bilayers is much higher than the graphene/BN bilayers. Near absolute zero, the σ(T) is zero for BN bilayers and it increases with temperature until reaches maximum value then decreases. The BN/graphene bilayers have larger electrical conductivity larger than BN bilayers. For both bilayers, the specific heat capacity has a Schottky anomaly.

  17. Bias induced modulation of electrical and thermal conductivity and heat capacity of BN and BN/graphene bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Chegel, Raad, E-mail: Raad.chegel@gmail.com

    2017-04-15

    By using the tight binding approximation and Green function method, the electronic structure, density of state, electrical conductivity, heat capacity of BN and BN/graphene bilayers are investigated. The AA-, AB{sub 1}- and AB{sub 2}- BN/graphene bilayers have small gap unlike to BN bilayers which are wide band gap semiconductors. Unlike to BN bilayer, the energy gap of graphene/BN bilayers increases with external field. The magnitude of the change in the band gap of BN bilayers is much higher than the graphene/BN bilayers. Near absolute zero, the σ(T) is zero for BN bilayers and it increases with temperature until reaches maximum value then decreases. The BN/graphene bilayers have larger electrical conductivity larger than BN bilayers. For both bilayers, the specific heat capacity has a Schottky anomaly.

  18. HFC-134a Emissions in China: An Inventory for 1995-2030

    Science.gov (United States)

    Su, Shenshen; Fang, Xuekun; Wu, Jing; Li, Li; Hu, Jianxin; Han, Jiarui

    2014-05-01

    HFC-134a is the most important substitute of CFC-12 used in the mobile air-conditioner in China since 1995. The bottom-up method was used to estimate HFC-134a emissions in China, from 1995 to 2030, basing on updated automobile industry data and latest emission characters. From 1995, total HFC-134a emission has kept a high growth rate of nearly 60% per year, and reached 16,414.3 Mg (11,959.4-20,834.5 Mg) in 2010, which was equivalent to 23.5 Mt CO2-eq emissions. Furthermore, the emissions in China accounted for nearly half of total emissions of Non-AnnexI countries in 2008. As for provincial emissions in 2010, provinces with emission greater than 1,000 Mg are Guangdong, Shandong, Jiangsu and Beijing. Quantitative relationship between provincial HFC-134a emissions and GRP of the Tertiary Industry was used to estimate HFC-134a emissions at county level, and Hangzhou municipal district held the maximum emission intensity (4,605 Mg/10,000 km2). For HFC-134a, emissions calculated from the observations within 46 cities through Euler box model are in good agreement with the corresponding emissions estimated from the bottom-up method, verifying that the emission inventory at county level adequately describes the emission spatial pattern. For the future emissions of HFC-134a, projected emissions will reach 89,370.4 Mg (65,959.7- 114,068.2 Mg) in 2030 under the Business-as-usual (BAU) Scenario, but under the Alternative Scenario, a emission reduction potential of 88.6% of the projected BAU emissions would be obtained.

  19. Cellulose nanofibrils (CNF) filled boron nitride (BN) nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Sulaiman, Hanisah Syed; Hua, Chia Chin; Zakaria, Sarani [School of Applied Physic, Faculty of Science and Technology, Universiti Kebangsaan Malaysia.43600 Bangi, Selangor (Malaysia)

    2015-09-25

    In this study, nanocomposite using cellulose nanofibrils filled with different percentage of boron nitride (CNF-BN) were prepared. The objective of this research is to study the effect of different percentage of BN to the thermal conductivity of the nanocomposite produced. The CNF-BN nanocomposite were characterization by FT-IR, SEM and thermal conductivity. The FT-IR analysis of the CNF-BN nanocomposite shows all the characteristic peaks of cellulose and BN present in all samples. The dispersion of BN in CNF were seen through SEM analysis. The effect of different loading percentage of BN to the thermal conductivity of the nanocomposite were also investigated.

  20. Performance investigation of capillary tubes for machine tool coolers retrofitted with HFC-407C refrigerant

    Science.gov (United States)

    Wang, Fujen; Chang, Tongbou; Chiang, Weiming; Lee, Haochung

    2012-09-01

    The machine tool coolers are the best managers of coolant temperature in avoiding the deviation of spindle centerline for machine tools. However, the machine coolers are facing the compressed schedule to phase out the HCFC (hydro-chloro-floro-carbon) refrigerant and little attention has been paid to comparative study on sizing capillary tube for retrofitted HFC (hydro-floro-carbon) refrigerant. In this paper, the adiabatic flow in capillary tube is analyzed and modeled for retrofitting of HFC-407C refrigerant in a machine tool cooler system. A computer code including determining the length of sub-cooled flow region and the two phase region of capillary tube is developed. Comparative study of HCFC-22 and HFC-407C in a capillary tube is derived and conducted to simplify the traditional trial-and-error method of predicting the length of capillary tubes. Besides, experimental investigation is carried out by field tests to verify the simulation model and cooling performance of the machine tool cooler system. The results from the experiments reveal that the numerical model provides an effective approach to determine the performance data of capillary tube specific for retrofitting a HFC-407C machine tool cooler. The developed machine tool cooler system is not only directly compatible with new HFC-407C refrigerant, but can also perform a cost-effective temperature control specific for industrial machines.

  1. The large contribution of projected HFC emissions to future climate forcing.

    Science.gov (United States)

    Velders, Guus J M; Fahey, David W; Daniel, John S; McFarland, Mack; Andersen, Stephen O

    2009-07-01

    The consumption and emissions of hydrofluorocarbons (HFCs) are projected to increase substantially in the coming decades in response to regulation of ozone depleting gases under the Montreal Protocol. The projected increases result primarily from sustained growth in demand for refrigeration, air-conditioning (AC) and insulating foam products in developing countries assuming no new regulation of HFC consumption or emissions. New HFC scenarios are presented based on current hydrochlorofluorocarbon (HCFC) consumption in leading applications, patterns of replacements of HCFCs by HFCs in developed countries, and gross domestic product (GDP) growth. Global HFC emissions significantly exceed previous estimates after 2025 with developing country emissions as much as 800% greater than in developed countries in 2050. Global HFC emissions in 2050 are equivalent to 9-19% (CO(2)-eq. basis) of projected global CO(2) emissions in business-as-usual scenarios and contribute a radiative forcing equivalent to that from 6-13 years of CO(2) emissions near 2050. This percentage increases to 28-45% compared with projected CO(2) emissions in a 450-ppm CO(2) stabilization scenario. In a hypothetical scenario based on a global cap followed by 4% annual reductions in consumption, HFC radiative forcing is shown to peak and begin to decline before 2050.

  2. Raman Scattering from Tin

    Science.gov (United States)

    2015-09-01

    and processing that will enable us to investigate the unique electronic states between topological insulators (TIs) and high- temperature... superconductors . TIs are electronic materials that have a bulk bandgap and gapless conducting surface states that are protected by the topological and...temperatures lower than 286 K and undergoes a phase transition at 286 K to metallic tin (β-Sn), the stable tin allotrope at temperatures above 286 K.4 High

  3. Research Update: Direct conversion of h-BN into pure c-BN at ambient temperatures and pressures in air

    Directory of Open Access Journals (Sweden)

    Jagdish Narayan

    2016-02-01

    Full Text Available We report a direct conversion of hexagonal boron nitride (h-BN into pure cubic boron nitride (c-BN by nanosecond laser melting at ambient temperatures and atmospheric pressure in air. According to the phase diagram, the transformation from h-BN into c-BN can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa. Using nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800 K and atmospheric pressure. The rapid quenching from super undercooled state leads to formation of super undercooled BN (Q-BN. The c-BN phase is nucleated from Q-BN depending upon the time allowed for nucleation and growth.

  4. Research Update: Direct conversion of h-BN into pure c-BN at ambient temperatures and pressures in air

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Jagdish, E-mail: narayan@ncsu.edu; Bhaumik, Anagh [Department of Materials Science and Engineering, Centennial Campus, North Carolina State University, Raleigh, North Carolina 27695-7907 (United States)

    2016-02-01

    We report a direct conversion of hexagonal boron nitride (h-BN) into pure cubic boron nitride (c-BN) by nanosecond laser melting at ambient temperatures and atmospheric pressure in air. According to the phase diagram, the transformation from h-BN into c-BN can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa. Using nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800 K and atmospheric pressure. The rapid quenching from super undercooled state leads to formation of super undercooled BN (Q-BN). The c-BN phase is nucleated from Q-BN depending upon the time allowed for nucleation and growth.

  5. Role of excited CF3CFHO radicals in the atmospheric chemistry of HFC-134a

    DEFF Research Database (Denmark)

    Wallington, T.J.; Hurley, M.D.; Fracheboud, J.M.;

    1996-01-01

    CFHO* radicals limits the formation of CF3C(O)F and hence CF3COOH in the atmospheric degradation of HFC-134a. We estimate that the CF3COOH yield from atmospheric oxidation of HFC-134a is 7-20%. Vibrationally excited alkoxy radicals may play an important role in the atmospheric chemistry of other...

  6. Resistive switching characteristic and uniformity of low-power HfO x -based resistive random access memory with the BN insertion layer

    Science.gov (United States)

    Su, Shuai; Jian, Xiao-Chuan; Wang, Fang; Han, Ye-Mei; Tian, Yu-Xian; Wang, Xiao-Yang; Zhang, Hong-Zhi; Zhang, Kai-Liang

    2016-10-01

    In this letter, the Ta/HfO x /BN/TiN resistive switching devices are fabricated and they exhibit low power consumption and high uniformity each. The reset current is reduced for the HfO x /BN bilayer device compared with that for the Ta/HfO x /TiN structure. Furthermore, the reset current decreases with increasing BN thickness. The HfO x layer is a dominating switching layer, while the low-permittivity and high-resistivity BN layer acts as a barrier of electrons injection into TiN electrode. The current conduction mechanism of low resistance state in the HfO x /BN bilayer device is space-charge-limited current (SCLC), while it is Ohmic conduction in the HfO x device. Project supported by the National Natural Science Foundation of China (Grant Nos. 61274113, 11204212, 61404091, 51502203, and 51502204), the Tianjin Natural Science Foundation, China (Grant Nos. 14JCZDJC31500 and 14JCQNJC00800), and the Tianjin Science and Technology Developmental Funds of Universities and Colleges, China (Grant No. 20130701).

  7. BN coatings deposition by magnetron sputtering of B and BN targets in electron beam generated plasma

    Science.gov (United States)

    Kamenetskikh, A. S.; Gavrilov, N. V.; Koryakova, O. V.; Cholakh, S. O.

    2017-05-01

    Boron nitride coatings were deposited by reactive pulsed magnetron sputtering of B and BN targets (50 kHz, 10 µs for B; 13.56 MHz for BN) at 2-20 mA/cm2 ion current density on the substrate. The effect of electron beam generated plasma on characteristics of magnetron discharge and phase composition of coatings was studied.

  8. Future atmospheric abundances and climate forcings from scenarios of global and regional hydrofluorocarbon (HFC) emissions

    Science.gov (United States)

    Velders, Guus J. M.; Fahey, David W.; Daniel, John S.; Andersen, Stephen O.; McFarland, Mack

    2015-12-01

    Hydrofluorocarbons (HFCs) are manufactured for use as substitutes for ozone-depleting substances that are being phased out globally under Montreal Protocol regulations. While HFCs do not deplete ozone, many are potent greenhouse gases that contribute to climate change. Here, new global scenarios show that baseline emissions of HFCs could reach 4.0-5.3 GtCO2-eq yr-1 in 2050. The new baseline (or business-as-usual) scenarios are formulated for 10 HFC compounds, 11 geographic regions, and 13 use categories. The scenarios rely on detailed data reported by countries to the United Nations; projections of gross domestic product and population; and recent observations of HFC atmospheric abundances. In the baseline scenarios, by 2050 China (31%), India and the rest of Asia (23%), the Middle East and northern Africa (11%), and the USA (10%) are the principal source regions for global HFC emissions; and refrigeration (40-58%) and stationary air conditioning (21-40%) are the major use sectors. The corresponding radiative forcing could reach 0.22-0.25 W m-2 in 2050, which would be 12-24% of the increase from business-as-usual CO2 emissions from 2015 to 2050. National regulations to limit HFC use have already been adopted in the European Union, Japan and USA, and proposals have been submitted to amend the Montreal Protocol to substantially reduce growth in HFC use. Calculated baseline emissions are reduced by 90% in 2050 by implementing the North America Montreal Protocol amendment proposal. Global adoption of technologies required to meet national regulations would be sufficient to reduce 2050 baseline HFC consumption by more than 50% of that achieved with the North America proposal for most developed and developing countries.

  9. 怎样维修"HFC-134a"制冷剂冰箱

    Institute of Scientific and Technical Information of China (English)

    徐进华

    2003-01-01

    @@ 美国杜邦(DuPont)公司推出了HFC-I34a,即四氯乙烷,它仍属于卤代烃类,但不含氟和溴,所以ODP(Ozone Deplete Potentia即臭氧消耗潜值)为零.家用电冰箱发展到现在,主要采用的制冷剂有:R12(CFC-12)、R134a(HFC-134a)、HC-600a等.

  10. Research Progress of PcBN Materials and Cutting Tools%PcBN材料及其刀具研究进展

    Institute of Scientific and Technical Information of China (English)

    班新星; 谢欢; 纪莲清; 刘书锋

    2012-01-01

    介绍了PcBN材料及其刀具的发展史,给出了制备PcBN的工艺流程及关键技术.通过大量实验数据总结出,作为合成PcBN的基本原料,cBN具有高的硬度和化学惰性.但高的化学惰性阻碍了晶格间的良好烧结,即cBN与cBN晶粒直接键合是十分困难的.分析了不同结合剂对制备PcBN的影响,介绍了金属结合剂及陶瓷结合剂对PcBN性能的影响,如:Al、B、AlN、TiN和WC等.最后对PcBN材料的发展作了展望.%The development status of materials and cutting tools of PcBN were briefly introduced, and the preparation PcBN process and the key technologies were given. Summed up by a large number of experimental data, as synthetic PcBN of basic raw materials, cBN has high hardness and chemical inertness. But high chemical inertness hinders the good sintering between the lattices. cBN and cBN grain direct bonding is very difficult. To solve the problems, the influences of different binders on the preparation of PcBN were analyzed, the metal-binding agents and ceramic-binding agents of PcBN performance were introduced, such as: Al, B, AlN and TiN, WC, etc. Finally, the development of PcBN materials in the future was prospected.

  11. Comparison of four inverse modelling systems applied to the estimation of HFC-125, HFC-134a, and SF6 emissions over Europe

    Science.gov (United States)

    Brunner, Dominik; Arnold, Tim; Henne, Stephan; Manning, Alistair; Thompson, Rona L.; Maione, Michela; O'Doherty, Simon; Reimann, Stefan

    2017-09-01

    Hydrofluorocarbons (HFCs) are used in a range of industrial applications and have largely replaced previously used gases (CFCs and HCFCs). HFCs are not ozone-depleting but have large global warming potentials and are, therefore, reported to the United Nations Framework Convention on Climate Change (UNFCCC). Here, we use four independent inverse models to estimate European emissions of the two HFCs contributing the most to global warming (HFC-134a and HFC-125) and of SF6 for the year 2011. Using an ensemble of inverse models offers the possibility to better understand systematic uncertainties in inversions. All systems relied on the same measurement time series from Jungfraujoch (Switzerland), Mace Head (Ireland), and Monte Cimone (Italy) and the same a priori estimates of the emissions, but differed in terms of the Lagrangian transport model (FLEXPART, NAME), inversion method (Bayesian, extended Kalman filter), treatment of baseline mole fractions, spatial gridding, and a priori uncertainties. The model systems were compared with respect to the ability to reproduce the measurement time series, the spatial distribution of the posterior emissions, uncertainty reductions, and total emissions estimated for selected countries. All systems were able to reproduce the measurement time series very well, with prior correlations between 0.5 and 0.9 and posterior correlations being higher by 0.05 to 0.1. For HFC-125, all models estimated higher emissions from Spain + Portugal than reported to UNFCCC (median higher by 390 %) though with a large scatter between individual estimates. Estimates for Germany (+140 %) and Ireland (+850 %) were also considerably higher than UNFCCC, whereas the estimates for France and the UK were consistent with the national reports. In contrast to HFC-125, HFC-134a emissions from Spain + Portugal were broadly consistent with UNFCCC, and emissions from Germany were only 30 % higher. The data suggest that the UK over-reports its HFC-134a emissions to

  12. Wide multi air-conditioning system using new cooling medium HFC407C; Shinreibai HFC407C saiyo no wide multi eakon

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    A multi air conditioner for a building was commercialized which used, as a substitute for the cooling medium HCFC(hydro chloro fluoro carbon)22, a new cooling medium HFC(hydro fluoro carbon)407C containing no chlorine atom that destroys the ozone layer. Since the new cooling medium HFC407C was a mixture of three kinds of cooling mediums having different boiling points, there were problems such as lowered performance through composition change in a heat exchanger and lowered lubricity due to no chlorine content. In order to solve these problems, high efficiency of the heat exchanger by the use of a new heat exchanger tube was contrived, as were improvement of the compressor, employment of a new lubricating oil, security of performance and enhancement of reliability through the optimum super heat control. As a result, the new cooling medium series was completed succeeding the advantage of the wide multi air-conditioners. (translated by NEDO)

  13. HEAT TRANSFER EVALUATION OF HFC-236FA IN CONDENSATION AND EVAPORATION

    Science.gov (United States)

    The report gives results of an evaluation of the shell-side heat transfer performance of hydrofluorocarbon (HFC)-236fa, which is considered to be a potential substitute for chlorofluorocarbon (CFC)-114 in Navy shipboard chillers, for both conventional finned [1024- and 1575-fpm (...

  14. HEAT TRANSFER EVALUATION OF HFC-236EA AND CFC-114 IN CONDENSATION AND EVAPORATION

    Science.gov (United States)

    The report gives results of a heat transfer evaluation of the refrigerants hexafluoropropane (HFC-236ea) and 1,1,2,2-dichloro-tetrafluoroethane (CFC-114). (NOTE: With the mandatory phase-out of chlorofluorocarbons (CFCs), as dictated by the Montreal Protocol and Clean Air Act Ame...

  15. HEAT TRANSFER EVALUATION OF HFC-236EA WITH HIGH PERFORMANCE ENHANCED TUBES IN CONDENSATION AND EVAPORATION

    Science.gov (United States)

    The report gives results of an evaluation of the heat transfer performance of pure hydrofluorocarbon (HFC)-236ea for high performance enhanced tubes which had not been previously used in Navy shipboard chillers. Shell-side heat transfer coefficient data are presented for condensa...

  16. MODELING AND DESIGN STUDY USING HFC-236EA AS AN ALTERNATIVE REFRIGERANT IN A CENTRIFUGAL COMPRESSOR

    Science.gov (United States)

    The report gives results of an investigation of the operation of a centrifugal compressor--part of a chlorofluorocarbon (CFC)-114 chiller installation--with the new refrigerant hydrofluorocarbon (HFC)-236ea, a proposed alternative to CFC-114. A large set of CFC-236ea operating da...

  17. Electron Excitation of Tin and Tin ion

    Science.gov (United States)

    Sharma, Lalita; Srivastava, Rajesh

    2014-05-01

    There is a great requirement of accurate atomic data of tin and its ions to understand the properties of laser produced tin plasma, one of the sources of extreme ultraviolet (EUV) radiation. The constant efforts are being made under various international programs viz., International SEMATECH's EUV Source Program, Intel Lithography Roadmap etc., to improve the efficiency of the EUV sources which can meet the requirements of high volume manufacturing of commercial chips. For optimizing the efficiency of EUV device the plasma modeling should be accurate which in turn, would rely on the accuracy of atomic data used. In this connection we have undertaken the study of electron impact excitation of Sn and Sn+. Since the atomic number of Sn is 50, it is sufficiently heavy atom to manifest relativistic spin - orbit and exchange effects. Therefore, we have used a fully relativistic distorted wave (RDW) theory to calculate results for cross sections corresponding to various transitions as well as polarization of photons due to decay of excited states of Sn and Sn+ In our RDW theory wavefunctions for both, the target electrons and projectile electrons are obtained by solving Dirac equations. Thus the relativistic effects are incorporated in consistent manner to ensure the reliability of the cross section and polarization results which will be presented in detail at the conference. Department of Atomic Energy, Govt. of India (DAE-BRNS).

  18. TIN-X

    DEFF Research Database (Denmark)

    Cannon, Daniel C; Yang, Jeremy J; Mathias, Stephen L

    2017-01-01

    Motivation: The increasing amount of peer-reviewed manuscripts requires the development of specific mining tools to facilitate the visual exploration of evidence linking diseases and proteins. Results: We developed TIN-X, the Target Importance and Novelty eXplorer, to visualize the association be...

  19. Metals on BN Studied by High Resolution Transmission Electron Microscopy

    Science.gov (United States)

    Bangert, U.; Zan, R.; Ramasse, Q.; Jalil, Rashid; Riaz, Ibstam; Novoselov, K. S.

    2012-07-01

    Metal impurities, gold and nickel, have been deliberately introduced into boron-nitride (BN) sheets. The structural and topographic properties of doped BN have been studied by aberration corrected scanning transmission electron microscopy (STEM). Analysis revealed that metal atoms cluster preferentially in/on contaminated areas. The metal coverage on BN is almost the same for the same evaporated amount of 1 Å.

  20. Leakage Evaluation of Blend Refrigerant HCFC-22/HFC-152a for Auto mobile Air Conditioners%混合工质HCFC-22/HFC-152a汽车空调系统中泄漏性能分析

    Institute of Scientific and Technical Information of China (English)

    张华; 谷松

    2001-01-01

    A analysis of leakage is carried out for automobile air conditioner charged with HCFC-22/HFC-152a. The performance of automobile air conditioners doesn,t obvio usly change when leakage of the blend refrigerant happens. The HCFC-22/HFC-152a( 40/60mass%) can be used as alternative refrigerant in the transition period of e xisting automobile air conditioners.%对采用HCFC-22/HFC-152a混合制冷剂的汽车空调的 泄漏性能进行了分析;说明了HCFC-22/HFC-152a混合制冷剂不会因泄漏引起制冷系统性 能的显著变化,它可作为现有的汽车空调系统的过渡替代工质。

  1. First-principles study of the crystal structures and physical properties of H18-BN and Rh6-BN

    Science.gov (United States)

    Ren, Xiao-Yan; Zhao, Chun-Xiang; Niu, Chun-Yao; Wang, Jia-Qi; Jia, Yu; Cho, Jun-Hyung

    2016-12-01

    As the analog of carbon allotropes, new three-dimensional (3D) boron nitride (BN) allotropes have attracted much attention of researchers due to their great importance in fundamental sciences and wide practical applications. Here, based on first-principles density-functional theory calculations, we predict two new stable BN allotropes: One is H18-BN with the P 6 bar m 2 (D3h1) symmetry containing eighteen atoms in the hexagonal unit cell and the other is Rh6-BN with the R 3 bar m (C3v5) symmetry containing six atoms in the rhombohedral primitive unit cell. The dynamic stabilities of the two structures are examined through the phonon spectrum analysis as well as molecular dynamics simulations, whereas the mechanical properties are analyzed by elastic constants, bulk modulus and shear modulus. From the analysis of the enthalpy evolution with respect to pressure, we find that h-BN can be transformed into either H18-BN or RH6-BN structure under a higher pressure of ∼ 15 GPa. We also find that both the H18-BN and Rh6-BN allotropes are brittle materials with indirect band gaps of 2.31 and 4.48 eV, respectively. The simulated XRD spectra provide detailed structural information of H18-BN and Rh6-BN for future experimental examinations. Our findings not only greatly enrich the existing structural family of 3D-BN materials but also stimulate further experiments.

  2. ESTUDO TRIBOLÓGICO DE REVESTIMENTOS DE DLC COM GASES REFRIGERANTES HFC134A E HC600A

    National Research Council Canada - National Science Library

    Silverio, Marcio; Binder, Roberto; Mello, José Daniel Biasoli

    2011-01-01

    This work aims to study the effect of refrigerant gases HFC134a and HC600a in components coated with DLC, Diamond-like Carbon, as well as is to establish a methodology for tribology evaluating of them...

  3. Deuterated methanol in Orion BN/KL

    CERN Document Server

    Peng, T -C; Brouillet, N; Parise, B; Baudry, A

    2012-01-01

    Deuterated molecules have been detected and studied toward Orion BN/KL in the past decades, mostly with single-dish telescopes. However, high angular resolution data are critical not only for interpreting the spatial distribution of the deuteration ratio but also for understanding this complex region in terms of cloud evolution involving star-forming activities and stellar feedbacks. We present here the first high angular resolution (1.8 arcsec \\times 0.8 arcsec) images of deuterated methanol CH2DOH in Orion BN/KL observed with the IRAM Plateau de Bure Interferometer from 1999 to 2007 in the 1 to 3 mm range. Six CH2DOH lines were detected around 105.8, 223.5, and 225.9 GHz. In addition, three E-type methanol lines around 101-102 GHz were detected and were used to derive the corresponding CH3OH rotational temperatures and column densities toward different regions across Orion BN/KL. The strongest CH2DOH and CH3OH emissions come from the Hot Core southwest region with an LSR velocity of about 8 km/s. We derive ...

  4. Linear Assembles of BN Nanosheets, Fabricated in Polymer/BN Nanosheet Composite Film

    Directory of Open Access Journals (Sweden)

    Hong-Baek Cho

    2011-01-01

    Full Text Available Linear assembles of BN nanosheets (LABNs were fabricated in polysiloxane/BN nanosheet composite film under a high DC electric field. The hexagonal BN nanosheets were dispersed by sonication in a prepolymer mixture of polysiloxane followed by a high-speed mixing. The homogeneous suspension was cast on a spacer of microscale thickness and applied to a high DC electric field before it became cross-linked. X-ray diffraction, scanning electron microscopy, and digital microscopy revealed that LABNs formed in the polysiloxane matrix and that the BN nanosheets in the LABNs were aligned perpendicular to the film plane with high anisotropy. This is the first time that linear assemblies of nanosheets have been fabricated in an organic-inorganic hybrid film by applying a DC electric field. The enhanced thermal conductivity of the composite film is attributed to the LABNs. The LABN formation and heat conduction mechanisms are discussed. The polysiloxane/BN nanosheet composite film has the potential to be used semiconductor applications that require both a high thermal conductivity and a high electric insulation.

  5. Quantitative comparisons of absorption cross-section spectra and integrated intensities of HFC-143a

    Science.gov (United States)

    Le Bris, Karine; Graham, Laura

    2015-01-01

    The integrated absorption cross-sections of HFC-143a (CH3CF3) differ substantially in the literature. This leads to an important uncertainty on the value of the radiative efficiency of this molecule. The ambiguity on the absorption cross-sections of HFC-143a is highlighted by the existence of two significantly different datasets in the HITRAN database. To solve the issue, we performed high-resolution Fourier transform infrared laboratory measurements of HFC-13a and compared the spectra with the two HITRAN datasets and with the data from the Pacific Northwest National Laboratory (PNNL). The experimental methods and data analysis techniques are examined and typical sources of errors are discussed. The integrated intensities of the main bands are compared to other literature values. It was found that the integrated absorption cross-section values in the highest range - around 13.8 ×10-17 cm .molecule-1 in the 570-1500 cm-1 spectral band - show the most consistency between authors.

  6. Two BN isosteres of anthracene: synthesis and characterization.

    Science.gov (United States)

    Ishibashi, Jacob S A; Marshall, Jonathan L; Mazière, Audrey; Lovinger, Gabriel J; Li, Bo; Zakharov, Lev N; Dargelos, Alain; Graciaa, Alain; Chrostowska, Anna; Liu, Shih-Yuan

    2014-10-29

    The synthesis of two parental BN anthracenes, 1 and 2, was developed, and their electronic structure and reactivity behavior were characterized in direct comparison with all-carbon anthracene. Gas-phase UV-photoelecton spectroscopy studies revealed the following HOMO energy trend: anthracene, -7.4 eV; BN anthracene 1, -7.7 eV; bis-BN anthracene 2, -8.0 eV. The λmax of the lower energy band in the UV-vis absorption spectrum is as follows: anthracene, 356 nm; BN anthracene 1, 359 nm; bis-BN anthracene 2, 357 nm. Thus, although the HOMO is stabilized with increasing BN incorporation, the HOMO-LUMO band gap remains unchanged across the anthracene series. The emission λmax values for the three investigated anthracene compounds are at 403 nm. The pKa values of the N-H proton for BN anthracene 1 and bis-BN anthracene 2 were determined to be approximately 26. BN anthracenes 1 and 2 do not undergo heat- or light-induced cycloaddition reactions or Friedel-Crafts acylations. Electrophilic bromination of BN anthracene 1 with Br2, however, occurs regioselectively at the 9-position. The reactivity behavior and regioselectivity of bromination of BN anthracenes are consistent with the electronic structure of these compounds; i.e., (1) the lower HOMO energy levels for BN anthracenes stabilize the molecules against cycloaddition and Friedel-Crafts reactions, and (2) the HOMO orbital coefficients are consistent with the observed bromination regioselectivity. Overall, this work demonstrates that BN/CC isosterism can be used as a molecular design strategy to stabilize the HOMO of acene-type structures while the optical band gap is maintained.

  7. HFC-152a and HFC-134a emission estimates and characterization of CFCs, CFC replacements, and other halogenated solvents measured during the 2008 ARCTAS campaign (CARB phase over the South Coast Air Basin of California

    Directory of Open Access Journals (Sweden)

    B. Barletta

    2011-03-01

    Full Text Available This work presents results from the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS study. Whole air samples were obtained on board research flights that flew over California during June 2008 and analyzed for selected volatile organic compounds, including several halogenated species. Samples collected over the South Coast Air Basin of California (SoCAB, which includes much of Los Angeles (LA County, were compared with samples from inflow air masses over the Pacific Ocean. The levels of many halocarbon species were enhanced significantly over the SoCAB, including compounds regulated by the Montreal Protocol and subsequent amendments. Emissions estimates of HFC-152a (1,1-difluoroethane, CH3CHF2; 0.82 ± 0.11 Gg and HFC-134a (1,1,1,2-tetrafluoroethane, CH2FCF3; 1.16 ± 0.22 Gg in LA County for 2008 were obtained using the observed HFC:carbon monoxide (CO enhancement ratio. Emission rates also were calculated for the SoCAB (1.60 ± 0.22 Gg yr−1 for HFC-152a and 2.12 ± 0.28 Gg yr−1 for HFC-134a and then extrapolated to the United States (32 ± 4 Gg yr−1 for HFC-152a and 43 ± 6 Gg yr−1 for HFC-134a using population data. In addition, emission rates of the two HFCs in LA County and SoCAB were calculated by a second method that utilizes air quality modeling. Emissions estimates obtained using both methods differ by less than 25% for the LA County and less than 45% for the SoCAB.

  8. Three of a Kind: Genetically Similar Tsukamurella Phages TIN2, TIN3, and TIN4.

    Science.gov (United States)

    Dyson, Zoe A; Tucci, Joseph; Seviour, Robert J; Petrovski, Steve

    2015-10-01

    Three Tsukamurella phages, TIN2, TIN3, and TIN4, were isolated from activated sludge treatment plants located in Victoria, Australia, using conventional enrichment techniques. Illumina and 454 whole-genome sequencing of these Siphoviridae viruses revealed that they had similar genome sequences, ranging in size between 76,268 bp and 76,964 bp. All three phages shared 74% nucleotide sequence identity to the previously described Gordonia phage GTE7. Genome sequencing suggested that phage TIN3 had suffered a mutation in one of its lysis genes compared to the sequence of phage TIN4, to which it is genetically very similar. Mass spectroscopy data showed the unusual presence of a virion structural gene in the DNA replication module of phage TIN4, disrupting the characteristic modular genome architecture of Siphoviridae phages. All three phages appeared highly virulent on strains of Tsukamurella inchonensis and Tsukamurella paurometabola. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  9. Synthesis and Characterization of Hexagonal Boron Nitride (h- BN) Films

    Science.gov (United States)

    2014-01-09

    Synthesis 1. Diborane- ammonia (B2H6-NH3- gases): Early results with these precursors were published in 2012. 5 Briefly, LPCVD growth of h-BN in a hot-wall...Approved for public release; distribution is unlimited. Synthesis and Characterization of Hexagonal Boron Nitride (h- BN) Films. The views, opinions and...1 ABSTRACT Number of Papers published in peer-reviewed journals: Synthesis and Characterization of Hexagonal Boron Nitride (h-BN) Films. Report Title

  10. Photo doping effect in graphene/BN heterostructure

    Science.gov (United States)

    Ju, Long; Velasco, Jairo, Jr.; Hwang, Edwin; Kim, Jonghwan; Wang, Feng

    2013-03-01

    Boron nitride has been demonstrated as an ideal substrate to achieve high mobility in graphene. At the same time We observed strong change of graphene transport properties by shining light on graphene/BN heterostructure. This is attributed to photo doping effect induced by impurity excitation in BN. Optical spectroscopy based on this photo-doping effects enables us to probe impurities in crystalline BN. Such information will be important for potential applications based on graphene/BN heterostructures. The potential of applying similar technique to probe defects in other insulators and semiconductors will also be discussed.

  11. Extraction and Separation of Tin from Tin-Bearing Secondary Resources: A Review

    Science.gov (United States)

    Su, Zijian; Zhang, Yuanbo; Liu, Bingbing; Lu, Manman; Li, Guanghui; Jiang, Tao

    2017-08-01

    The proven global tin reserves were reported to be approximately 4.7 million tons (Mts) in 2016, and among these resources, only approximately 2.2 Mts can be recovered economically. The original tin deposits will be exhausted in several years, therefore, tin-bearing secondary resources, such as tin alloy, tin anode slime, e-wastes, tin slag and tin-bearing tailings, will become the primary source from which tin can be extracted. Many investigations have been conducted on the recovery of tin from these tin-bearing materials. However, the separation and recovery approaches of tin vary significantly, since the content and phase compositions of tin are totally different in these secondary resources. This paper reviews these methods of extracting and separating tin from different kinds of tin-bearing secondary resources.

  12. A straightforward strategy toward large BN-embedded π-systems: synthesis, structure, and optoelectronic properties of extended BN heterosuperbenzenes.

    Science.gov (United States)

    Wang, Xiao-Ye; Zhuang, Fang-Dong; Wang, Rui-Bo; Wang, Xin-Chang; Cao, Xiao-Yu; Wang, Jie-Yu; Pei, Jian

    2014-03-12

    A straightforward strategy has been used to construct large BN-embedded π-systems simply from azaacenes. BN heterosuperbenzene derivatives, the largest BN heteroaromatics to date, have been synthesized in three steps. The molecules exhibit curved π-surfaces, showing two different conformations which are self-organized into a sandwich structure and further packed into a π-stacking column. The assembled microribbons exhibit good charge transport properties and photoconductivity, representing an important step toward the optoelectronic applications of BN-embedded aromatics.

  13. Study of thermodynamic properties of HFC refrigerant mixtures for Loretz-cycled niew generation air-conditioning equipment; Lorentz cycle ka shinsedai kucho kikiyo HFC kei kongo reibai no netsu rikigaku seishitsu ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, K.; Sato, H. [Keio University, Tokyo (Japan). Faculty of Science and Technology

    1997-02-01

    This paper describes thermodynamic properties of HFC refrigerant mixtures for Lorentz-cycled new generation air-conditioning equipment. Equipment has been completed for simultaneous measurement of density and vapor-liquid equilibrium property, accurate measurement of latent heat of vaporization, and accurate measurement of specific heat at constant pressure in liquid phase. Final adjustment and preliminary measurements are currently conducted. Through analytical investigation using actually measured data of thermodynamic properties of HFC refrigerant mixtures, five state equations were obtained, i.e., modified Peng-Robinson state equation which can reproduce the vapor-liquid equilibrium property of refrigerant mixtures, modified Patel-Teja state equation, Helmholtz function type state equation which is applicable in the whole fluid region of refrigerant mixtures, and so on. An evaluation test equipment has been fabricated as a trial for Lorentz-cycled air-conditioning equipments using HFC refrigerant mixtures, and demonstration test is conducted to confirm the validity. 9 refs., 5 figs.

  14. Tin-containing silicates

    DEFF Research Database (Denmark)

    Osmundsen, Christian M.; Holm, Martin Spangsberg; Dahl, Søren

    2012-01-01

    The selective conversion of biomass-derived substrates is one of the major challenges facing the chemical industry. Recently, stannosilicates have been employed as highly active and selective Lewis acid catalysts for a number of industrially relevant reactions. In the present work, four different...... stannosilicates have been investigated: Sn-BEA, Sn-MFI, Sn-MCM-41 and Sn-SBA-15. When comparing the properties of tin sites in the structures, substantial differences are observed. Sn-beta displays the highest Lewis acid strength, as measured by probe molecule studies using infrared spectroscopy, which gives...... it a significantly higher activity at low temperatures than the other structures investigated. Furthermore, the increased acid strength translates into large differences in selectivity between the catalysts, thus demonstrating the influence of the structure on the active site, and pointing the way forward...

  15. Accurate measurement of phase equilibria and dissociation enthalpies of HFC-134a hydrates in the presence of NaCl for potential application in desalination

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dongyoung; Lee, Yohan; Choi, Wonjung; Seo, Yongwon [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of); Lee, Seungmin [Korea Institute of Industrial Technology, Busan (Korea, Republic of)

    2016-04-15

    Phase equilibria, structure identification, and dissociation enthalpies of HFC-134a hydrates in the presence of NaCl are investigated for potential application in desalination. To verify the influence of NaCl on the thermodynamic hydrate stability of the HFC-134a hydrate, the three-phase (hydrate (H) - liquid water (L{sub W}) - vapor (V)) equilibria of the HFC-134a+NaCl (0, 3.5, and 8.0 wt%)+water systems are measured by both a conventional isochoric (pVT) method and a stepwise differential scanning calorimeter (DSC) method. Both pVT and DSC methods demonstrate reliable and consistent hydrate phase equilibrium points of the HFC-134a hydrates in the presence of NaCl. The HFC- 134a hydrate is identified as sII via powder X-ray diffraction. The dissociation enthalpies (ΔH{sub d}) of the HFC-134a hydrates in the presence of NaCl are also measured with a high pressure micro-differential scanning calorimeter. The salinity results in significant thermodynamic inhibition of the HFC-134a hydrates, whereas it has little effect on the dissociation enthalpy of the HFC-134a hydrates. The experimental results obtained in this study can be utilized as foundational data for the hydrate-based desalination process.

  16. Experimental investigation of HFC407C/HC290/HC600a mixture in a window air conditioner

    Energy Technology Data Exchange (ETDEWEB)

    Jabaraj, D.B.; Avinash, P.; Lal, D. Mohan; Renganarayan, S. [Department of Mechanical Engineering, College of Engineering, Anna University, Chennai 600 025 (India)

    2006-09-15

    HCFC22, one of the widely used refrigerants in window air conditioners must be phased out soon as per the Montreal protocol. Presently, HFC407C is considered as a potential drop in substitute for HCFC22, but retrofitting HCFC22 systems with HFC407C with polyol ester oil (POE) is a major issue as HFC407C is immiscible with mineral oil. The miscibility issue of HFC407C with mineral oil was overcome with the addition of a HC blend to it. The above technoeconomic feasibility issues to retrofit the existing HCFC22 systems with an ozone friendly refrigerant and retain the energy efficiency of the system are challenges in the air conditioning sector. In this present work, an experimental analysis has been conducted in a window air conditioner retrofitted with eco-friendly refrigerant mixtures of HFC407C/HC290/HC600a without changing the mineral oil. Its performance, as well as energy consumption, was compared with the conventional one. It is observed that the mixtures demand lengthening of the condenser in order to maintain the discharge pressure within acceptable limits. This also resulted in better heat transfer at the condenser. Therefore, in this study, the condenser tube length was increased by 19% to suit the mixtures as compared to HCFC22. Compared to HCFC22, the refrigeration capacity of the new mixture was 9.54-12.76% higher than that of HCFC22, while the actual COP was found to be 11.91-13.24% higher than that of HCFC22. The overall performance has proved that the HFC407C/HC blend refrigerant mixture could be an eco-friendly substitute to phase out HCFC22. (author)

  17. Historical and projected emissions of HCFC-22 and HFC-410A from China's room air conditioning sector

    Science.gov (United States)

    Wang, Ziyuan; Fang, Xuekun; Li, Li; Bie, Pengju; Li, Zhifang; Hu, Jianxin; Zhang, Boya; Zhang, Jianbo

    2016-05-01

    Recent decades witnessed the increase in production and uses of HCFC-22 (chlorodifluoromethane, CHClF2) and its alternative, HFC-410A (a blend of difluoromethane and pentafluoroethane), in China in response to the booming of room air conditioners (RACs) for both domestic use and exports. HCFC-22 is an ozone-depleting substance under the Montreal Protocol, while both HCFC-22 and HFC-410A are greenhouse gases (GHGs). This study provides a most comprehensive consumption and emission inventory of refrigerants emissions (HCFC-22 and HFC-410A) from RAC sector during 1995-2014, for the first time. Our estimates show that HCFC-22 emissions increased from 0.7 Gg/yr in 1995 to 48.2 Gg/yr in 2014. The accumulative emissions contributed to global total HCFCs emissions by 4.4% (3.3%-6.1%) CFC-11-equivalent (CFC-11-eq) and 5.4% (4.1%-7.5%) CO2-equivalent (CO2-eq) during 1995-2012. If left uncontrolled, accumulative emissions of HFC-410A will be12.4 (7.1-20.2) CO2-eq Pg during 2015-2050, which can offset the global climate benefits achieved by the Montreal Protocol. The HFC-410A emissions from China's RAC sector are estimated to be of importance to both global HFCs emissions and China's GHG emissions. Further, we probed the emission mitigation performances of the current 2014 North American Proposal scenario and a modified more ambitious scenario. The emissions of two mitigation scenarios are only 28% and 22% of the emissions without mitigation actions, respectively. This study is the first effort to map the transition of eliminated substance HCFC-22 and its alternative HFC-410A in RAC sector. Therefore, alternative chemicals should be scrutinized with cautions before they are promoted and applied.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yang; Chen, Xiaolong; Ye, Weiguang; Wu, Zefei; Han, Yu; Han, Tianyi; He, Yuheng; Cai, Yuan; Wang, Ning, E-mail: phwang@ust.hk [Department of Physics and the William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

    2014-12-15

    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, possibly due to the weakened interactions between the graphene nanoribbon and side-gate electrodes caused by the Ga{sup +} beam etching process.

  19. Determination of micro structural corrosion by BN

    Energy Technology Data Exchange (ETDEWEB)

    Zergoug, M.; Kamel, G.; Benchaala, A. [Laboratoire d' Electronique et d' Electrotechnique, Centre de soudage et de controle, Route de Dely Ibrahim, B.P:64, Cheraga (Algeria)

    2004-07-01

    The quality control of industrial components requires adaptation and the development of new material characterization and particular non destructive testing techniques. To characterize steel, it would be useful to know its chemical composition, physic-chemical constitution, metallurgical state (annealed, hammered) and other parameters (superficial and chemical processing, etc.). The testing method using Barkhausen noise (B.N.) is a particular method, which can be applied on ferromagnetic materials. It is a magnetic non destructive evaluation (NDE) method and can provide very important information about the material microstructure. The work here presented documents the ability to determine the metallurgical state of steel submitted to the corrosive attack by electrochemical process. The samples are characterized by Barkhausen noise as non destructive methods and are compared with methods as metallography, micro hardness measurement, and toughness determination. (authors)

  20. Effect of pH on the Hydrothermal Synthesis of BN Nanocrystals

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Boron nitride (BN) has been synthesized using hydrothermal synthesis method. The experimental results showed that the pH value of the reaction solution has an important effect on the yield and phases of BN samples. As the pH value decreased, the content of cBN increased and the yield improved. The increase in cBN content is resulted from the conversion of oBN into cBN under hydrothermal condition, and the growth of cBN nanocrystals may due to the decrease in the reaction speed, thus the crystalline perfection of BN improved when the pH value decreased.

  1. Integrated services to the home and small business over a service-independent HFC network

    Science.gov (United States)

    Counterman, Raymond

    1995-11-01

    This paper proposes three different approaches to providing integrated digital services to small businesses and residential customers over modern hybrid fiber and coaxial (HFC) access networks. The target delivery system is one that is flexible and forms a multiservice, service- independent platform capable of providing a wide range of services (voice, video, data, and multimedia). The merits and limitations of the three approaches are explored. In the first approach, the common facilities of an HFC access network may be shared by the frequency partitioning of the coaxial plant's radio frequency spectrum. video, data, and telephony services each use different portions of this spectrum -- a service-dependent network. In the second approach, asynchronous transfer mode (ATM) transmission is used as the information delivery vehicle all the way to the home or small business, creating a more flexible delivery system. The ATM-based architecture is expected to support any service or service mix -- a service-independent network. In the third approach, a common transport protocol composed of both asynchronous and synchronous transfer modes (ATM/STM) is used. Such an approach could (1) provide a common interface between home/small business premises equipment and both the circuit and ATM switching networks; (2) meet a wide range of delay and throughput requirements; and (3) allow for many network migration scenarios.

  2. Experimental evaluation of automotive air-conditioning using HFC-134a and HC-134a

    Science.gov (United States)

    Nasution, Henry; Zainudin, Muhammad Amir; Aziz, Azhar Abdul; Latiff, Zulkarnain Abdul; Perang, Mohd Rozi Mohd; Rahman, Abd Halim Abdul

    2012-06-01

    An experimental study to evaluate the energy consumption of an automotive air conditioning is presented. In this study, these refrigerants will be tested using the experimental rig which simulated the actual cars as a cabin complete with a cooling system component of the actual car that is as the blower, evaporator, condenser, radiators, electric motor, which acts as a vehicle engine, and then the electric motor will operate the compressor using a belt and pulley system, as well as to the alternator will recharge the battery. The compressor working with the fluids HFC-134a and HC-134a and has been tested varying the speed in the range 1000, 1500, 2000 and 2500 rpm. The measurements taken during the one hour experimental periods at 2-minutes interval times for temperature setpoint of 20°C with internal heat loads 0, 500, 700 and 1000 W. The final results of this study show an overall better energy consumption of the HFC-134a compared with the HC-134a.

  3. Proton transport properties of tin phosphate, chromotropic acid anchored onto tin phosphate and tin phenyl phosphonate

    Indian Academy of Sciences (India)

    Chithra Sumej; P P Sharmila; Nisha J Tharayil; S Suma

    2013-02-01

    Tin (IV) phosphates of the class of tetravalent metal acid (TMA) salts have been synthesized by sol–gel method. The functionalized materials of tin (IV) phosphate (SnP) like chromotropic acid anchored tin phosphate (SnPCA) and tin phenyl phosphonate (SnPP) were also synthesized. These materials have been characterized for elemental analysis (ICP–AES), thermal analysis, X-ray analysis and FTIR spectroscopy. Chemical resistivity of these materials has been accessed in acidic, basic and organic solvent media. The proton present in the structural hydroxyl groups indicates good potential for TMA salts to exhibit solid-state proton conduction. The transport properties of these materials have been explored by measuring specific proton conductance at different temperatures. Based on the specific conduction data and Arrhenius plots, a suitable mechanism has been proposed.

  4. Facile synthesis of tin phosphite nanosheets via exfoliated bulk crystals: Electronic structure and piezoelectric property.

    Science.gov (United States)

    Song, Jun-Ling; Zhang, Xi-Rui; Lu, Rui-Feng

    2016-08-01

    Tin phosphite nanosheets were synthesized by a facile exfoliation method. SnHPO3 nanosheets with a thickness of ∼2.6nm readily form a stable colloidal suspension in ethanol using ultrasonic method. Structures and optical properties of the obtained nanosheets were investigated. The prepared SnHPO3 nanosheets exhibit an obvious blue-shift in UV absorbance compared with bulk SnHPO3 crystal materials. Moreover, the piezoelectric coefficients of SnHPO3 monolayer were calculated based on density functional theory, which are larger than that of h-BN monolayer, indicating this material could be a good candidate for designing electro-optical nano-devices.

  5. Synthesis and Oxidation Resistance of h-BN Thin Films

    Science.gov (United States)

    Stewart, David; Meulenberg, Robert; Lad, Robert

    Hexagonal boron nitride (h-BN) is an exciting 2D material for use in sensors and other electronic devices that operate in harsh, high temperature environments. Not only is h-BN a wide band gap material with excellent wear resistance and high temperature stability, but recent reports indicate that h-BN can prevent metallic substrates from oxidizing above 600°C in low O2 pressures. However, the PVD of highly crystalline h-BN films required for this oxidation protection has proven challenging. In this work, we have explored the growth of h-BN thin films by reactive RF magnetron sputtering from an elemental B target in an Ar/N2 atmosphere. The film growth rate is extremely slow and the resulting films are atomically smooth and homogeneous. Using DC biasing during deposition and high temperature annealing treatments, the degree of film crystallinity can be controlled. The oxidation resistance of h-BN films deposited on inert sapphire and reactive metal substrates such as Zr and ZrB2 has been examined by techniques such as XPS, XRD, and SEM after oxidation between 600 and 1200°C under varying oxygen pressures. The success of h-BN as a passivation layer for metallic substrates in harsh environments is shown to depend greatly on its crystalline quality and defects. Supported by the NSF SusChEM program.

  6. Diamond-cBN alloy: A universal cutting material

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Pei [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); High Pressure Science and Engineering Center and Department of Physics and Astronomy, University of Nevada Las Vegas, Las Vegas, Nevada 89154 (United States); He, Duanwei, E-mail: duanweihe@scu.edu.cn; Kou, Zili; Li, Yong; Hu, Qiwei; Xu, Chao; Lei, Li; Wang, Qiming [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Wang, Liping; Zhao, Yusheng [High Pressure Science and Engineering Center and Department of Physics and Astronomy, University of Nevada Las Vegas, Las Vegas, Nevada 89154 (United States); Xiong, Lun; Liu, Jing [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    2015-09-07

    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 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. High-speed cutting tests on hardened steel and granite suggest that diamond-cBN alloy is indeed a universal cutting material.

  7. 爆炸极限实验系统研制及二甲醚/HFC125的可燃性研究%Flammability Limits Measurement System and Flammability of Dimethyl Ether/HFC125

    Institute of Scientific and Technical Information of China (English)

    张可; 吴江涛; 高辉; 薛征欣

    2010-01-01

    根据ASTM E681-04及ANSI/ASHRAE Standard 34-2007标准,建立了一套全自动可燃性气体爆炸极限实验系统.该系统实际配气比例与设定比例的误差不超过±0.1%,配气比例的不确定度小于0.5%.对几种常见制冷剂的爆炸极限进行了测试,验证了系统的准确性.对二甲醚/HFC125混合气体的爆炸极限进行了实验研究,结果表明,加入HFC125后二甲醚的可燃性范围减小,当HFC125与二甲醚的体积比为4.6时达到临界抑爆点,但HFC125含量较低时对二甲醚的阻燃作用不明显.该测试结果为将二甲醚作为一种环保型制冷剂进行推广应用提供了安全参考.

  8. Sorbate rearrangement and cation migration in HFC-134 loaded NaY zeolite: a temperature dependent synchrotron powder diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Gualtieri, A.F. [Dipt. di Scienze della Terra, Univ. di Modena e R.E. (Italy); Norby, P. [Chemistry Dept., Univ. of Aarhus (Denmark); Grey, C.P. [Chemistry Dept., SUNY Stony Brook, NY (United States); Hanson, J.C. [Chemistry Dept., Brookhaven National Lab., Upton, NY (United States)

    2004-07-01

    The HFC-134/NaY binding has been monitored by temperature dependent X-ray powder diffraction. Diffraction patterns were obtained as a function of different loading levels to investigate the rearrangement of the cations and of the HFC-134 molecules, in the temperature range 100-230 K. In situ real-time data were collected using a Translating Imaging Plate System (TIPS) at the NSLS (USA). Rietveld structure refinements were performed for the HFC-134 (32 molecules per unit cell [m/uc=molecules per unit cell] or 4 molecules per supercage [m/sc=molecules per supercage]) using data collected from 100 to 230 K. A phase transition is observed at about 180 K (A to B phase transition) where a disordering of the HFC-134 molecule takes place and modification of its surrounding due to Na{sup +} migrations is observed. These results are preliminary and the experiment with the 32 m/uc should be repeated in order to assess whether the observed effect is reproducible. (orig.)

  9. Determination of the infrared cross sections and global warming potentials of 1,1,2-trifluorethane (HFC-143)

    Energy Technology Data Exchange (ETDEWEB)

    Clerbaux, C.; Colin, R. [Univ. Libre de Bruxelles, Brussels (Belgium)

    1994-11-01

    The Global Warming Potentials (GWPs) of CH2F-CHF2 (HFC-143) have been estimated for different time horizons. Radiative forcings associated with this CFC alternative have been derived relative to CFC-11 and CO2 by introducing laboratory measured absorption cross sections into a coupled chemical-radiative model.

  10. Accelerating growth of HFC-227ea (1,1,1,2,3,3,3-heptafluoropropane) in the atmosphere

    NARCIS (Netherlands)

    Laube, J.C.; Martinerie, P.; Witrant, E.; Brenninkmeijer, C.A.M.; Bolder, M.; Rockmann, T.; van der Veen, C; Sturges, W.T.

    2010-01-01

    We report the first measurements of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), a substitute for ozone depleting compounds, in air samples originating from remote regions of the atmosphere and present evidence for its accelerating growth. Observed mixing ratios ranged from below 0.01 ppt in deep f

  11. Toeplitz and composition operators on H~2 (B_n)

    Institute of Scientific and Technical Information of China (English)

    曹广福; 孙顺华

    1997-01-01

    The composition operators with closed range on H2( Bn) are characterized, and the Frcdholmness of products of Toeplitz and composition operators discussed. Moreover, using composition operators, the spectra of Toeplitz operators are studied.

  12. Fabrication and Microstructure of BN Matrix Composites with Electrical Conductivity

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    BN ceramic is an advanced engineering ceramics with excellent thermal shock resistance, good workability and excellent dielectricity.TiB2 ceramic has excellent electric conductivity,high melting points, and corrosion resistance to molten metal.Therefore,the composite consisting of BN and TiB2 ceramics is expected to have a combination of above-mentioned properties,thereby can be used as self- heating crucible.In this paper,hot pressing technology was used to fabricate the high performance BN-TiB2 composite materials.microstructure and electric conducting mechanism were studied,and the relationship between the microstructure and physical property was discussed.The results show that the microstructure of composites has a great influence on the physical property of composites.The BN-TiB2 composites with excellent mechanical strength and stable resistivity can be obtained by optimizing the processing parameter and controlling the microstructure of composites.

  13. GaN nanorods coated with pure BN

    Science.gov (United States)

    Han, Wei-Qiang; Zettl, A.

    2002-12-01

    We report a method to efficiently synthesize gallium nitride (GaN) nanorods coated with insulating boron nitride (BN) layers. The GaN core is crystalline (with either a cubic zincblende or hexagonal wurtzite structure) and has diameters ranging from 10 to 85 nm and lengths up to 60 μm. The outer encapsulating BN shells with typical thicknesses less than 5 nm extend fully over, and adhere well to, the entire nanorod surface.

  14. h-BN-TiO2 Nanocomposite for Photocatalytic Applications

    Directory of Open Access Journals (Sweden)

    Václav Štengl

    2016-01-01

    Full Text Available h-BN-TiO2 nanocomposites were synthesized by the thermal hydrolysis of titanium peroxo-complexes in the presence of exfoliated h-BN. The bulk h-BN was prepared by annealing mixture of boric acid and urea, and high intensity ultrasound was used for its exfoliation. The prepared samples were characterized by X-ray powder diffraction (XRD, infrared spectroscopy, Raman spectroscopy, electron spin resonance (ESR, high resolution electron microscopy, BET surface area, and BJH porosity measurement. The UV-Vis diffuse reflectance spectroscopy was employed to estimate band-gap energies. The photoinduced charge on the surface of h-BN-TiO2 nanocomposites was visualized using electric force microscopy (EFM. The photocatalytic activity was determined by azo dyes Orange II and Reactive Black 5 photobleaching. The highest rate constant k = 0.0762 min−1 and 0.0164 min−1, under UV and visible light irradiation, respectively, showed sample denoted TiP050BN with moderate concentration of h-BN.

  15. A comparative computational study on the BN ring doped nanographenes

    Science.gov (United States)

    Vessally, E.; Soleimani-Amiri, S.; Hosseinian, A.; Edjlali, L.; Bekhradnia, A.

    2017-02-01

    The electronic, optical, energetic, and structural properties of a HBC (hexa-peri-hexabenzocoronene) nanographene and its central benzene- and coronene-like BN substituted forms, and also full BN analogue were investigated using density functional theory. It was found that a larger number of carbon atoms cause a more negative cohesive energy and, thereby a greater structural stability. Our nucleus independent chemical shift analysis indicates that the aromaticity and Clar's sextet rule determine the relative stability of these structures. The benzene-like or coronene-like doping makes the HBC more insulator or semiconductor. Electron-hole Frenkel type exciton binding energy was predicted and calculated to be nearly identical for all nanographenes in the range of 0.61-0.69 eV. The coronene-like BN-doped HBC (BN2-HBN) shows higher conductivity due to very narrow optical and HOMO-LUMO energy gap. Partial density of states analysis indicates that the BN2-HBC electronically can be assumed a full BN whose peripheral atoms are replaced by carbon atoms. These carbon atoms are responsible for new states which are appeared within the gap.

  16. Energetics and Electronic Structure of h-BN Nanoflakes

    Science.gov (United States)

    Yamanaka, Ayaka; Okada, Susumu

    2016-08-01

    We studied the energetics and electronic structure of hexagonal boron nitride (h-BN) nanoribbons with hydrogenated and clean edges with respect to the detailed edge shapes using density functional theory. Our calculations showed that the stability of h-BN edges strongly depends on the edge termination. In the case of hydrogenated edges, the formation energy is constant for all edge angles ranging from armchair to zigzag, indicating that h-BN may exhibit rich variation in their edge atomic arrangements under static conditions. The hydrogenated h-BN nanoribbons are insulators with an energy gap of 4 eV irrespective of edge shape, in which the lowest branch of the conduction band exhibits nearly free electron states nature distributed in the vacuum region outside the ribbons. In contrast, the formation energy of h-BN nanoribbons with clean edges monotonically increases as the edge angle is changed from armchair to zigzag. Our analysis reveals that the increase of density of states at the Fermi level arising from dangling bond states leads to this monotonic increase of edge formation energy in h-BN nanoribbons with clean edges.

  17. Electronic transport properties and first-principles study of graphene/h-BN and h-BN bilayers

    Science.gov (United States)

    Ashhadi, M.; Hadavi, M. S.; Sarri, Z.

    2017-03-01

    We use a tight binding approach to study of electron transport properties of bilayers of zig-zag graphene/h-BN nanoribbon (GBNNR) and h-BN nanoribbon (BNNR) embedded between two bilayer of zig-zag graphene nanoribbons (GNR), which are considered as electrodes. In this study, the parameters of tight biding hopping and on-site energies are obtained by comparing the tight binding band structure graphene/h-BN and h-BN bilayers with density functional theory (DFT) calculations. We numerically compute the transport properties in terms of transmission and current-voltage characteristic. Our calculations show that the electron transport can open a conduction gap in the GNR/BNNR/GNR structure.

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

    Science.gov (United States)

    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).

  19. Performance studies on mechanical + adsorption hybrid compression refrigeration cycles with HFC 134a

    Energy Technology Data Exchange (ETDEWEB)

    Banker, N.D.; Dutta, P.; Srinivasan, K. [Department of Mechanical Engineering, Indian Institute of Science, Bangalore 560 012 (India); Prasad, M. [Thermal Systems Division, ISRO Satellite Centre, Bangalore 560 017 (India)

    2008-12-15

    This paper presents the results of an investigation on the efficacy of hybrid compression process for refrigerant HFC 134a in cooling applications. The conventional mechanical compression is supplemented by thermal compression using a string of adsorption compressors. Activated carbon is the adsorbent for the thermal compression segment. The alternatives of bottoming either mechanical or thermal compression stages are investigated. It is shown that almost 40% energy saving is realizable by carrying out a part of the compression in a thermal compressor compared to the case when the entire compression is carried out in a single-stage mechanical compressor. The hybrid compression is feasible even when low grade heat is available. Some performance indictors are defined and evaluated for various configurations. (author)

  20. HFC网络升级优化方案%HFC Network Upgrade Optimum Proposal

    Institute of Scientific and Technical Information of China (English)

    黄映辉; 庄嘉

    2012-01-01

    Aiming at the transmission structure of the Secondary transmission network which use the high power light transmission module that was ubiquity in the HFC network at present.This kind of transmission structure is difficult to sustain the broadband services,the ITV and other new business.This paper discusses the design proposal and characteristic which adapt to INT structure interactive broadband Secondary transmission platform%针对目前HFC网络普遍存在的二级传输网采用大功率光发模块的传输结构,难以支撑宽带业务及互动电视等新业务的问题,论述了为适应三网融合构建交互式宽带网络二级传输网光平台的设计方案及特点。

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

    OpenAIRE

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

    2011-01-01

    Abstract 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...

  2. Preparation of the radiopharmaceutical {sup 99m} Tc-HYNIC-[Lys{sup 3}]-BN; Preparacion del radiofarmaco {sup 99m} Tc-HYNIC-[Lys{sup 3}]-BN

    Energy Technology Data Exchange (ETDEWEB)

    Conde S, E. [Universidad Autonoma del Estado de Mexico, Facultad de Quimica, 50000 Toluca, Estado de Mexico (Mexico)

    2007-07-01

    hydrazinenicotinamidic acid (HYNIC). The formulation that was obtained for the scaling of the lots is shown in the following relationship among reagent and quantity: HYNIC-[Lys{sup 3}]-BN (HYNIC-Bombesin), 25 {mu}g; tin chloride, 10 mg; Ethylenediamineacetic acid (EDDA), 10 mg; N-tris(hydroxymethyl)methylglycine (Tricine), 20 mg; Manitol, 50 mg. The radiochemical purity was determined by means of HPLC coupled to a radioactivity detector. The stability tests demonstrate that the one conjugated is stable until for three months; also, the activity stays for more than 24 hours, that which makes very versatile the use of the nucleus-equipment in the clinical area. The incorporation of radioactivity in the pancreas demonstrated the ability of the radiopharmaceutical to unite In vivo to cells related with GRP receivers. Also, the studies of blockade of receivers confirmed the specificity of the bio conjugated by the GRP-r. The incorporation inside the PC-3 cells receiver-positive it went significantly smaller to that of the pancreas, but the incorporation to the tumor was highly specific. (Author)

  3. Inventory and mitigation opportunities for HFC-134a emissions from nonprofessional automotive service

    Science.gov (United States)

    Zhan, Tao; Potts, Winston; Collins, John F.; Austin, Jeff

    2014-12-01

    Many vehicle owners in the United States recharge their vehicles' air conditioning systems with small containers of hydrofluorocarbon-134a (HFC-134a, CH2FCF3), at a frequency estimated to be once every year on average. Such nonprofessional service produces immediate emissions of this potent greenhouse gas during service and from the residual heel in partially used containers. The nonprofessional operations are also associated with increased delayed refrigerant emissions that occur because owners are less likely to repair leaks than professional technicians. In California, an estimated 1.3 million nonprofessional service operations performed each year generate 0.27 ± 0.07 million metric ton CO2 equivalent (MMTCO2e) of immediate emissions and 0.54 ± 0.08 MMTCO2e of delayed emissions, using a Global Warming Potential of 1300 for HFC-134a. The immediate emissions can be largely mitigated by a regulation that requires self-sealing valves and improved labeling instructions on the containers, a deposit-return-recycling program for the containers, and a consumer education program. If 95% of the used containers were to be returned by consumers for recycling of the container heel, the annual immediate emissions would be reduced by 0.26 ± 0.07 MMTCO2e. In the United States, an estimated 24 million nonprofessional service operations are performed each year, generating 5.1 ± 1.4 MMTCO2e of immediate emissions and 10.4 ± 1.5 MMTCO2e of delayed emissions. Mitigation measures equivalent to the California regulation would reduce nationwide immediate emissions by 4.9 ± 1.4 MMTCO2e, if 95% of the used cans were returned for recycling. These business-as-usual emissions and mitigation potentials are projected to stay approximately constant until around 2022, and remain at significant levels into the 2030s.

  4. Substituent Directed Phototransformations of BN-Heterocycles: Elimination vs Isomerization via Selective B-C Bond Cleavage.

    Science.gov (United States)

    Yang, Deng-Tao; Mellerup, Soren K; Peng, Jin-Bao; Wang, Xiang; Li, Quan-Song; Wang, Suning

    2016-09-14

    Electron-rich and -poor BN-heterocycles with benzyl-pyridyl backbones and two bulky aryls on the boron (Ar = tipp, BN-1, Ar = MesF, BN-2) have been found to display distinct molecular transformations upon irradiation by UV light. BN-1 undergoes an efficient photoelimination reaction forming a BN-phenanthrene with ΦPE = 0.25, whereas BN-2 undergoes a thermally reversible, stereoselective, and quantitative isomerization to a dark colored BN-1,3,5-cyclooctatriene (BN-1,3,5-COT, BN-2a). This unusual photoisomerization persists for other BN-heterocycles with electron-deficient aryls such as BN-3 with a benzyl-benzothiazolyl backbone and Mes(F) substituents or BN-4 with a benzyl-pyridyl backbone and two C6F5 groups on the boron. The photoisomerization of BN-4 goes beyond BN-1,3,5-COT (BN-4a), forming a new species (BN-1,3,6-COT, BN-4b) via C-F bond cleavage and [1,3]-F atom sigmatropic migration. Computational studies support that BN-4a is an intermediate in the formation of BN-4b. This work establishes that steric and electronic factors can effectively control the transformations of BN-heterocycles, allowing access to important and previously unknown BN-embedded species.

  5. International strategic minerals inventory summary report; tin

    Science.gov (United States)

    Sutphin, D.M.; Sabin, A.E.; Reed, B.L.

    1990-01-01

    The International Strategic Minerals Inventory tin inventory contains records for 56 major tin deposits and districts in 21 countries. These countries accounted for 98 percent of the 10 million metric tons of tin produced in the period 1934-87. Tin is a good alloying metal and is generally nontoxic, and its chief uses are as tinplate for tin cans and as solder in electronics. The 56 locations consist of 39 lode deposits and 17 placers and contain almost 7.5 million metric tons of tin in identified economic resources (R1E) and another 1.5 million metric tons of tin in other resource categories. Most of these resources are in major deposits that have been known for over a hundred years. Lode deposits account for 44 percent of the R1E and 87 percent of the resources in other categories. Placer deposits make up the remainder. Low-income and middle-income countries, including Bolivia and Brazil and countries along the Southeast Asian Tin Belt such as Malaysia, Thailand, and Indonesia account for 91 percent of the R1E resources of tin and for 61 percent of resources in other categories. The United States has less than 0.05 percent of the world's tin R1E in major deposits. Available data suggest that the Soviet Union may have about 4 percent of resources in this category. The industrial market economy countries of the United States, Japan, Federal Republic of Germany, and the United Kingdom are major consumers of tin, whereas the major tin-producing countries generally consume little tin. The Soviet Union and China are both major producers and consumers of tin. At the end of World War II, the four largest tin-producing countries (Bolivia, the Belgian Congo (Zaire), Nigeria, and Malaysia) produced over 80 percent of the world's tin. In 1986, the portion of production from the four largest producers (Malaysia, Brazil, Soviet Union, Indonesia) declined to about 55 percent, while the price of tin rose from about $1,500 to $18,000 per metric ton. In response to tin shortages

  6. 管束效应对HFC245fa与HCFC123膜状凝结换热影响%Effect of Inundation on Film Condensation of HFC245fa and HCFC123 on Horizontal Tubes

    Institute of Scientific and Technical Information of China (English)

    马志先; 张吉礼; 孙德兴

    2012-01-01

    建立试验系统、改进试验方法,试验研究HFC245fa与HCFC123在光管与3种强化换热管(2D-A,3D-A与3D-B)管束外冷凝换热特性.试验管束由4列排深为5排的列管构成,换热管公称外径为19.05 mm、有效换热长度为500 mm.试验中,利用改进的Wilson图解法获得水侧对流传热系数,通过轮转试验方法消除管束试验中各试验管换热本构差异等因素对管束效应测试分析的影响.试验结果表明,Kern模型预测值与HFC245fa与HCFC123光管管束外凝结换热结果偏差随试验热通量升高而增大;管束效应对光管与三维表面强化管(3D-B)凝结换热影响比其对二维表面低肋管(2D-A)影响显著;管束效应对HFC245fa在3D-B管外凝结换热影响在n>3后超过Nusselt管束模型预测值;HFC245fa在3D-B管束外凝结换热性能随管排深度的变化规律与其在光管管束外的变化规律及Nusselt模型显示规律明显不同.%A test facility was constructed to perform shell-side condensation testing, and test results are presented for HFC245fa and HCFC123 using horizontal tube bundles (4 lines×5 rows) consist of smooth tubes and 2D-A, 3D-A and 3D-B enhanced tubes. Effect of inundation on the condensation heat transfer coefficient (CHTC) is considered in the study. The nominal diameter of test tubes is 19.05 mm and the active length of the test section is 500 mm. In the experiment, water-side convection heat transfer coefficient of enhanced tube was gained by modified Wilson plot method and the tube row effect is studied by a designed method with high precision. The results show that the deviation between CHTC of HCFC123 and HFC245fa on smooth tube bundle and that predicted by Kern's model increased with the increase of heat flow rate; Inundation effect significantly affects CHTC of smooth and 3D-B tubes, but lightly affects that of 2D-A tubes; Inundation effect of HFC245fa on 3D-B tubes is more severity than that predicted by Nusselt model for

  7. Purification of chimeric heavy chain monoclonal antibody EG2-hFc using hydrophobic interaction membrane chromatography: an alternative to protein-A affinity chromatography.

    Science.gov (United States)

    Sadavarte, Rahul; Spearman, Maureen; Okun, Natalie; Butler, Michael; Ghosh, Raja

    2014-06-01

    Heavy chain monoclonal antibodies are being considered as alternative to whole-IgG monoclonal antibodies for certain niche applications. Protein-A chromatography which is widely used for purifying IgG monoclonal antibodies is also used for purifying heavy chain monoclonal antibodies as these molecules possess fully functional Fc regions. However, the acidic conditions used to elute bound antibody may sometimes also leach protein-A, which is immunotoxic. Low pH conditions also tend to make the mAb molecules unstable and prone to aggregation. Moreover, protein-A affinity chromatography does not remove aggregates already present in the feed. Hydrophobic interaction membrane chromatography (or HIMC) has already been studied as an alternative to protein-A chromatography for purifying whole-IgG monoclonal antibodies. This paper describes the use of HIMC for capturing a humanized chimeric heavy chain monoclonal antibody (EG2-hFC). Binding and eluting conditions were suitably optimized using pure EG2-hFC. Based on this, an HIMC method was developed for capture of EG2-hFC directly from cell culture supernatant. The EG2-hFc purity obtained in this single-step process was high. The glycan profiles of protein-A and HIMC purified monoclonal antibody samples were similar, clearly demonstrating that both techniques captured similarly glycosylated population of EG2-hFc. Moreover, this technique was able to resolve aggregates from monomeric form of the EG2-hFc.

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

    Directory of Open Access Journals (Sweden)

    Wu Jiangtao

    2011-01-01

    Full Text Available Abstract 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.

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

    Science.gov (United States)

    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.

  10. Enhancement of surface mechanical properties by using TiN[BCN/BN]{sub n}/c-BN multilayer system

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, H. [Laboratorio de Recubrimientos Duros, CDT-ASTIN SENA, Cali (Colombia); Caicedo, J.C., E-mail: Jcesarca@calima.univalle.edu.co [Grupo de Peliculas Delgadas, Universidad del Valle, Cali (Colombia); Amaya, C. [Grupo de Peliculas Delgadas, Universidad del Valle, Cali (Colombia); Munoz-Saldana, J. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro, Mexico (Mexico); Yate, L.; Esteve, J. [Department de Fisica Aplicada i Optica, Universitat de Barcelona, Catalunya (Spain); Prieto, P. [Grupo de Peliculas Delgadas, Universidad del Valle, Cali (Colombia); Centro de Excelencia en Nuevos Materiales, CENM, Cali (Colombia)

    2010-11-15

    The aim of this work is to improve the mechanical properties of AISI 4140 steel substrates by using a TiN[BCN/BN]{sub n}/c-BN multilayer system as a protective coating. TiN[BCN/BN]{sub n}/c-BN multilayered coatings via reactive r.f. magnetron sputtering technique were grown, systematically varying the length period ({Lambda}) and the number of bilayers (n) because one bilayer (n = 1) represents two different layers (t{sub BCN} + t{sub BN}), thus the total thickness of the coating and all other growth parameters were maintained constant. The coatings were characterized by Fourier transform infrared spectroscopy showing bands associated with h-BN bonds and c-BN stretching vibrations centered at 1400 cm{sup -1} and 1100 cm{sup -1}, respectively. Coating composition and multilayer modulation were studied via secondary ion mass spectroscopy. Atomic force microscopy analysis revealed a reduction in grain size and roughness when the bilayer number (n) increased and the bilayer period decreased. Finally, enhancement of mechanical properties was determined via nanoindentation measurements. The best behavior was obtained when the bilayer period ({Lambda}) was 80 nm (n = 25), yielding the relative highest hardness ({approx}30 GPa) and elastic modulus (230 GPa). The values for the hardness and elastic modulus are 1.5 and 1.7 times greater than the coating with n = 1, respectively. The enhancement effects in multilayered coatings could be attributed to different mechanisms for layer formation with nanometric thickness due to the Hall-Petch effect; because this effect, originally used to explain increased hardness with decreasing grain size in bulk polycrystalline metals, has also been used to explain hardness enhancements in multilayered coatings taking into account the thickness reduction at individual single layers that make up the multilayered system. The Hall-Petch model based on dislocation motion within layered and across layer interfaces has been successfully applied to

  11. Thermal Conductance of the 2D MoS2/h-BN and graphene/h-BN Interfaces

    Science.gov (United States)

    Liu, Yi; Ong, Zhun-Yong; Wu, Jing; Zhao, Yunshan; Watanabe, Kenji; Taniguchi, Takashi; Chi, Dongzhi; Zhang, Gang; Thong, John T. L.; Qiu, Cheng-Wei; Hippalgaonkar, Kedar

    2017-01-01

    Two-dimensional (2D) materials and their corresponding van der Waals heterostructures have drawn tremendous interest due to their extraordinary electrical and optoelectronic properties. Insulating 2D hexagonal boron nitride (h-BN) with an atomically smooth surface has been widely used as a passivation layer to improve carrier transport for other 2D materials, especially for Transition Metal Dichalcogenides (TMDCs). However, heat flow at the interface between TMDCs and h-BN, which will play an important role in thermal management of various electronic and optoelectronic devices, is not yet understood. In this paper, for the first time, the interface thermal conductance (G) at the MoS2/h-BN interface is measured by Raman spectroscopy, and the room-temperature value is (17.0 ± 0.4) MW · m−2K−1. For comparison, G between graphene and h-BN is also measured, with a value of (52.2 ± 2.1) MW · m−2K−1. Non-equilibrium Green’s function (NEGF) calculations, from which the phonon transmission spectrum can be obtained, show that the lower G at the MoS2/h-BN interface is due to the weaker cross-plane transmission of phonon modes compared to graphene/h-BN. This study demonstrates that the MoS2/h-BN interface limits cross-plane heat dissipation, and thereby could impact the design and applications of 2D devices while considering critical thermal management. PMID:28262778

  12. Final Project Closeout Report for Sprint Hydrogen Fuel Cell (HFC) Deployment Project in California, Gulf Coast and Eastern Seaboard Markets

    Energy Technology Data Exchange (ETDEWEB)

    Kenny, Kevin [Sprint, Reston, VA (United States); Bradley, Dwayne [Burns & McDonnell, Kansas City, MO (United States)

    2015-09-01

    Sprint is one of the telecommunications industry leaders in the deployment of hydrogen fuel cell (HFC) systems to provide backup power for their mission critical wireless network facilities. With several hundred fuel cells commissioned in California, states in the gulf coast region, and along the upper eastern seaboard. A strong incentive for advancing the integration of fuel cells into the Sprint network came through the award of a Department of Energy (DOE) grant focused on Market Transformation activities for project (EE0000486). This grant was funded by the 2009 American Recovery and Reinvestment Act (ARRA). The funding provided by DOE ($7.295M) was allocated to support the installation of 260 new HFC systems, equipped with an on-site refillable Medium Pressure Hydrogen Storage Solution (MPHSS), as well as for the conversion of 21 low pressure hydrogen systems to the MPHSS, in hopes of reducing barriers to market acceptance.

  13. Isosteric heats of adsorption extracted from experiments of ethanol and HFC 134a on carbon based adsorbents

    Energy Technology Data Exchange (ETDEWEB)

    El-Sharkawy, Ibrahim I.; Saha, Bidyut B.; Koyama, Shigeru [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga-koen 6-1, Kasuga-shi, Fukuoka 816-8580 (Japan); Srinivasan, Kandadai [School of Engineering and Logistics, Charles Darwin University, Darwin NT 0909 (Australia)

    2007-03-15

    The purpose of this paper is to provide empirical correlations for isosteric heats of adsorption on carbon based adsorbents for two refrigerants namely ethanol and HFC 134a. A non-dimensional correlation which partitions the contributions of the concentration and temperature dependence is proposed. The correlation is tested out against data obtained from experimental isotherms of ethanol adsorption on activated carbon fibers [ACF (A-20) and ACF (A-15)] and HFC 134a on two specimens of activated carbon powders and one specimen of carbon granules. It is expected that the suggested correlation will be useful for designers of adsorption chillers where indenting heat inventories fulcrums on the magnitude of isosteric heat of adsorption. (author)

  14. (Vapour + liquid) equilibria of the {l_brace}pentafluoroethane (HFC-125) + dimethyl ether (DME){r_brace} system

    Energy Technology Data Exchange (ETDEWEB)

    Im, Jihoon [School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Lee, Gangwon [School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Lee, Jongcheon [LG Chem, Ltd. Research Park, Yuseong-gu, Science Town, Daejeon 305-380 (Korea, Republic of); Kim, Hwayong [School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of)]. E-mail: hwayongk@snu.ac.kr

    2006-12-15

    Binary (vapour + liquid) equilibrium data were measured for the {l_brace}pentafluoroethane (HFC-125) + dimethyl ether (DME){r_brace} system at temperatures from (313.15 to 363.15) K. These experiments were carried out with a circulating-type apparatus with on-line gas chromatography. The experimental data were correlated well by the Peng-Robinson Stryjek-Vera equation of state using the Wong-Sandler mixing rules.

  15. Anisotropy of BN and Be x-ray-emission bands

    Energy Technology Data Exchange (ETDEWEB)

    Mansour, A.; Schnatterly, S.E.

    1987-12-15

    We present measurements of the K emission spectra of hexagonal Be and BN (h-Be and h-BN). The anisotropy of the emission allows us to separate the bands into their sigma and ..pi.. components, enabling us to demonstrate the unambiguous ..pi.. character of the B core exciton. We find that the exciton presents a double-peaked structure which we attribute to phonon ringing. For the first time we are able to separate into ..pi.. and sigma components the doubly ionized K emission bands of B and N in h-BN and of Be in h-Be, revealing the effect of the spectator core hole on the shape of the density of states. Such an effect is in qualitative agreement with the final-state rule, although the local p density of states is distorted more than has previously been reported.

  16. Study on the Interaction Coefficients in PR Equation with vdW Mixing Rules for HFC and HC Binary Mixtures

    Science.gov (United States)

    Chen, Jian-Xin; Hu, Peng; Chen, Ze-Shao

    2008-12-01

    The Peng-Robinson equation of state with the van der Waals mixing rules was used to correlate vapor-liquid equilibrium (VLE) data for HFC/HC, HFC/HFC, and HC/HC binary mixtures. The interaction parameter k ij was obtained for every binary mixture. It was assumed that k ij has contributions from the two components, and each component has its own constant contribution factor k i for the mixture, and the values of k ij indicate the degree in difference of properties between the two components. Therefore, the interaction parameters k ij is proposed as: k ij = k i - k j . The values of the mixing factor k i for Hydrofluorocarbons (HFCs) and Hydrocarbons (HCs), including propane, isobutane, n-butane, R23, R32, R125, R143a, R134a, R152a, R227ea R236fa, R236ea, and R245fa, were obtained by least-square fitting. In total, 39 refrigerant binary mixtures were analyzed on the basis of this method, and the results showed good agreement with experimental data. The overall average absolute deviations of pressure and vapor mole fraction are 1.3 % and 0.0089, respectively.

  17. Extrinsic allergic alveolitis with eosinophil infiltration induced by 1,1,1,2-tetrafluoroethane (HFC-134a): a case report.

    Science.gov (United States)

    Ishiguro, Takashi; Yasui, Masahide; Nakade, Yusuke; Kimura, Hideharu; Katayama, Nobuyuki; Kasahara, Kazuo; Fujimura, Masaki

    2007-01-01

    A 22-year-old woman was admitted with symptoms of dyspnea and fever with pulmonary infiltrates noted on her chest X-ray study. She developed these symptoms in the workplace; her job included the removal of body hair using a diode-laser with 1,1,1,2-tetrafluoroethane (HFC134a, an alternative to chlorofluorocarbon) as a coolant. A chest X-ray examination revealed ground-glass opacities in the lower lung fields, and a chest computed tomographic study showed diffuse centrilobular opacities. An examination of the bronchoalveolar lavage fluid revealed increased lymphocytes with a slight increase in the number of eosinophils. An examination of the transbronchial biopsy specimens revealed eosinophil infiltration. A peripheral blood eosinophilia was also seen. The patient's symptoms, chest X-ray findings, and arterial blood gas analysis all returned to normal within a week. A challenge test of 1,1,1,2-tetrafluoroethane (HFC134a) inhalation was performed, which resulted in an elevation of body temperature, the development of a cough, and laboratory data indicating increased inflammation. We then determined the patient's diagnosis to be extrinsic allergic alveolitis with eosinophil infiltration, caused by HFC134a.

  18. Studies on Cementation of Tin on Copper and Tin Stripping from Copper Substrate

    Directory of Open Access Journals (Sweden)

    Rudnik E.

    2016-06-01

    Full Text Available Cementation of tin on copper in acid chloride-thiourea solutions leads to the formation of porous layers with a thickness dependent on the immersion time. The process occurs via Sn(II-Cu(I mechanism. Chemical stripping of tin was carried out in alkaline and acid solutions in the presence of oxidizing agents. It resulted in the dissolution of metallic tin, but refractory Cu3Sn phase remained on the copper surface. Electrochemical tin stripping allows complete tin removal from the copper substrate, but porosity and complex phase composition of the tin coating do not allow monitoring the process in unambiguous way.

  19. Measurements of HFC-134a and HCFC-22 in groundwater and unsaturated-zone air: implications for HFCs and HCFCs as dating tracers

    Science.gov (United States)

    Haase, Karl B.; Busenberg, Eurybiades; Plummer, L. Niel; Casile, Gerolamo; Sanford, Ward E.

    2014-01-01

    A new analytical method using gas chromatography with an atomic emission detector (GC–AED) was developed for measurement of ambient concentrations of hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) in soil, air, and groundwater, with the goal of determining their utility as groundwater age tracers. The analytical detection limits of HCFC-22 (difluorochloromethane, CHClF2) and HFC-134a (1,2,2,2-tetrafluoroethane, C2H2F4) in 1 L groundwater samples are 4.3 × 10− 1 and 2.1 × 10− 1 pmol kg− 1, respectively, corresponding to equilibrium gas-phase mixing ratios of approximately 5–6 parts per trillion by volume (pptv). Under optimal conditions, post-1960 (HCFC-22) and post-1995 (HFC-134a) recharge could be identified using these tracers in stable, unmixed groundwater samples. Ambient concentrations of HCFC-22 and HFC-134a were measured in 50 groundwater samples from 27 locations in northern and western parts of Virginia, Tennessee, and North Carolina (USA), and 3 unsaturated-zone profiles were collected in northern Virginia. Mixing ratios of both HCFC-22 and HFC-134a decrease with depth in unsaturated-zone gas profiles with an accompanying increase in CO2 and loss of O2. Apparently, ambient concentrations of HCFC-22 and HFC-134a are readily consumed by methanotrophic bacteria under aerobic conditions in the unsaturated zone. The results of this study indicate that soils are a sink for these two greenhouse gases. These observations contradict the previously reported results from microcosm experiments that found that degradation was limited above-ambient HFC-134a. The groundwater HFC and HCFC concentrations were compared with concentrations of chlorofluorocarbons (CFCs, CFC-11, CFC-12, CFC-113) and sulfur hexafluoride (SF6). Nearly all samples had measured HCFC-22 or HFC-134a that were below concentrations predicted by the CFCs and SF6, with many samples showing a complete loss of HCFC-22 and HFC-134a. This study indicates that HCFC-22 and HFC-134

  20. Combustion Synthesis of h-BN-SiC Ceramic Composites

    Institute of Scientific and Technical Information of China (English)

    LI Hong-bo; ZHENG Yong-ting; ZHOU Li-juan; HAN Jie-cai

    2006-01-01

    The feasibility was demonstrated to fabricate h-BN-SiC ceramics through combustion synthesis of the mixture of boron carbide and silicon powders under 100 MPa nitrogen pressure. The mass fraction of BN and SiC in the combustion products were found to be 72 % and 28 % respectively. The thermodynamics of the synthesis reaction and the adiabatic combustion temperature were calculated on the theoretical ground. The bending strengths of the ceramics were measured to be 65.2 MPa at room temperature and 55 MPa at 1350 ℃. The phase composition and microstructure of the combustion products were identified by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

  1. Raman fingerprint of aligned graphene/h-BN superlattices.

    Science.gov (United States)

    Eckmann, Axel; Park, Jaesung; Yang, Huafeng; Elias, Daniel; Mayorov, Alexander S; Yu, Geliang; Jalil, Rashid; Novoselov, Kostya S; Gorbachev, Roman V; Lazzeri, Michele; Geim, Andre K; Casiraghi, Cinzia

    2013-11-13

    Graphene placed on hexagonal-boron nitride (h-BN) experiences a superlattice (Moiré) potential, which leads to a strong reconstruction of graphene's electronic spectrum with new Dirac points emerging at sub-eV energies. Here we study the effect of such superlattices on graphene's Raman spectrum. In particular, the 2D Raman peak is found to be exquisitely sensitive to the misalignment between graphene and h-BN lattices, probably due to the presence of a strain distribution with the same periodicity of the Moiré potential. This feature can be used to identify graphene superlattices with a misalignment angle smaller than 2°.

  2. Tin Whisker Testing and Modeling

    Science.gov (United States)

    2015-11-01

    contamination , and post-assembly contamination methods 40 5.2.3 Environmental exposure, whisker measurements and metallurgical analysis 42 5.3 Results and...The roughness is partly a result of the shrinkage of the liquid between the primary tin dendrites. The roughness tends to trap contamination , which...diameter, density, and distribution were measured. 5.2.3.3 Metallurgical analysis To examine contamination levels and distributions, as-received

  3. Fundamental Discovery of New Phases and Direct Conversion of Carbon into Diamond and hBN into cBN and Properties

    Science.gov (United States)

    Narayan, Jagdish; Bhaumik, Anagh

    2016-04-01

    We review the discovery of new phases of carbon (Q-carbon) and BN (Q-BN) and address critical issues related to direct conversion of carbon into diamond and hBN into cBN at ambient temperatures and pressures in air without any need for catalyst and the presence of hydrogen. The Q-carbon and Q-BN are formed as a result of quenching from super undercooled state by using high-power nanosecond laser pulses. We discuss the equilibrium phase diagram ( P vs T) of carbon, and show that by rapid quenching, kinetics can shift thermodynamic graphite/diamond/liquid carbon triple point from 5000 K/12 GPa to super undercooled carbon at atmospheric pressure in air. Similarly, the hBN-cBN-Liquid triple point is shifted from 3500 K/9.5 GPa to as low as 2800 K and atmospheric pressure. It is shown that nanosecond laser heating of amorphous carbon and nanocrystalline BN on sapphire, glass, and polymer substrates can be confined to melt in a super undercooled state. By quenching this super undercooled state, we have created a new state of carbon (Q-carbon) and BN (Q-BN) from which nanocrystals, microcrystals, nanoneedles, microneedles, and thin films are formed depending upon the nucleation and growth times allowed and the presence of growth template. The large-area epitaxial diamond and cBN films are formed, when appropriate planar matching or lattice matching template is provided for growth from super undercooled liquid. The Q-phases have unique atomic structure and bonding characteristics as determined by high-resolution SEM and backscatter diffraction, HRTEM, STEM-Z, EELS, and Raman spectroscopy, and exhibit new and improved mechanical hardness, electrical conductivity, and chemical and physical properties, including room-temperature ferromagnetism and enhanced field emission. The Q-carbon exhibits robust bulk ferromagnetism with estimated Curie temperature of about 500 K and saturation magnetization value of 20 emu g-1. We have also deposited diamond on cBN by using a novel

  4. Finnish 2002 inventory of HFC, PFC and SF{sub 6} emissions

    Energy Technology Data Exchange (ETDEWEB)

    Oinonen, T.

    2004-07-01

    Year 2002 was exceptional in the history of Finnish HFC, PFC and SF6 (F-gases for short) use. For the first time in a 10 year period, emissions fell from previous year. High uncertainty of the 2001 estimate prevents reliable quantification of the magnitude of this decrease, but simulation results suggest that the decrease may have been around 10%. The 2002 level of F-gases emissions was 530 Gg CO{sub 2}-equivalent. This figure corresponds to 0.6% of total Finnish greenhouse gas emissions.The inventory of F-gases was improved in 2003 by extending the coverage of the survey used to gather data. The number of respondents surveyed was quadrupled to some 1 000 individuals, and more than 750 of these responded. This improvement had an effect of bringing down the inventory uncertainty (measured by the width of the 95 % certainty range) from 400 Gg CO{sub 2}-eq. in 2001 to 140 Gg CO{sub 2}-eq. in 2002. Best efforts were made to ensure the accuracy, transparency, consistency, completeness and comparability of the inventory, as mandated in the guidelines of the United Nations Framework Convention on Climate Change. Although reporting to the UNFCCC is the primary purpose of this document, it is hoped that the information contained within is of use also in formulating strategies to combat climate change both in Finland and in European Union. (orig.)

  5. Perverse effects of carbon markets on HFC-23 and SF6 abatement projects in Russia

    Science.gov (United States)

    Schneider, Lambert; Kollmuss, Anja

    2015-12-01

    Carbon markets are considered a key policy tool to achieve cost-effective climate mitigation. Project-based carbon market mechanisms allow private sector entities to earn tradable emissions reduction credits from mitigation projects. The environmental integrity of project-based mechanisms has been subject to controversial debate and extensive research, in particular for projects abating industrial waste gases with a high global warming potential (GWP). For such projects, revenues from credits can significantly exceed abatement costs, creating perverse incentives to increase production or generation of waste gases as a means to increase credit revenues from waste gas abatement. Here we show that all projects abating HFC-23 and SF6 under the Kyoto Protocol’s Joint Implementation mechanism in Russia increased waste gas generation to unprecedented levels once they could generate credits from producing more waste gas. Our results suggest that perverse incentives can substantially undermine the environmental integrity of project-based mechanisms and that adequate regulatory oversight is crucial. Our findings are critical for mechanisms in both national jurisdictions and under international agreements.

  6. Consideration of Sludge Formation in HFC-134a / Polyol Ester oil Refrigeration System

    Science.gov (United States)

    Yamamoto, Tsutomu; Yamamoto, Tethuya; Simizu, Yasuhiko; Nakayama, Yoshinori; Takizawa, Kikuo

    A refrigeration test employing HFC-134a and polyol ester oil was carried out in order to make clear the causes of the sludge formation in the capillary tube. Compressors used were two types: a hermetic reciprocating compressor and a rotary compressor. Installed dryer contained desiccant of the compound zeolite type. The results showed that the amount of capillary sludge increased as the compressor temperature rose. The capillary sludge was determined to consist of desiccant and metal dust for the reciprocating compressor, and of tar-like substance for the rotary compressor. Thermal stability test which was used to check the degree of deterioration of the ester oil, suggested that the presence of desiccant and high compressor temperature might produce tar-like substance by the break down and polymerization of the ester oil. In addition, it was confirmed that factors affecting the sludge formation were the dirtiness of the refrigeration circuit for the reciprocating compressor, and the presence of desiccant, for the rotary compressor.

  7. Study on two stage activated carbon/HFC-134a based adsorption chiller

    Science.gov (United States)

    >K Habib,

    2013-06-01

    In this paper, a theoretical analysis on the performance of a thermally driven two-stage four-bed adsorption chiller utilizing low-grade waste heat of temperatures between 50°C and 70°C in combination with a heat sink (cooling water) of 30°C for air-conditioning applications has been described. Activated carbon (AC) of type Maxsorb III/HFC-134a pair has been examined as an adsorbent/refrigerant pair. FORTRAN simulation program is developed to analyze the influence of operating conditions (hot and cooling water temperatures and adsorption/desorption cycle times) on the cycle performance in terms of cooling capacity and COP. The main advantage of this two-stage chiller is that it can be operational with smaller regenerating temperature lifts than other heat-driven single-stage chillers. Simulation results shows that the two-stage chiller can be operated effectively with heat sources of 50°C and 70°C in combination with a coolant at 30°C.

  8. Research on Processing Multi-noise Signals in Mobile Multimedia Communication Based on HFC

    Institute of Scientific and Technical Information of China (English)

    ZENG Qinghui; HU Xiulin; ZHUANG Zhaowen; ZENG Yilin; MA Tao; ZHANG Yunyu; YANG Haizhou

    2001-01-01

    As well known, noise is one of mainobjects of signals processing. However, many kindsof noises are affecting widely on mobile communica-tion along with enlarging mobile networks and rapidlyincreasing application range of multimedia commu-nication. The noises include 1/f noise; burst noise;multichannel noise; thermal and shot noise etc., allof which here are called "multi-noise (MN)" and atthe same time, the signals affected by "multi-noise"is called "multi-noise signals". The article firstly ana-lyzes some disturbance factors of multi-noise that af-fects multimedia flow. Then, it describes briefly hi-erarchical fuzzy control (HFC) technology and its ap-plication procedure for online identification and con-trolling multi-noise signals in mobile multimedia com-munication networks. Lastly, how to make a specialhierarchical fuzzy control program is also discussed.With different test examples, the article demonstratesthe ability of hierarchical fuzzy control to identifyflow states and control signal distortion in multime-dia communication. The hierarchical fuzzy controland hierarchical fuzzy control programs provide anadvanced efficient tool for supervising the distributedstates of multi-noise and movement characteristics ofmulti-noise signals in mobile multimedia communica-tion.

  9. Band-gap engineering of the h-BN/MoS2/h-BN sandwich heterostructure under an external electric field

    Science.gov (United States)

    Huang, Zongyu; Qi, Xiang; Yang, Hong; He, Chaoyu; Wei, Xiaolin; Peng, Xiangyang; Zhong, Jianxin

    2015-05-01

    Based on first-principles calculations in the framework of van der Waals density functional theory, we investigate the structural, electronic properties and band-gap tuning of the h-BN/MoS2/h-BN sandwich heterostructure under an external electric field. We find that, different from the suspended monolayer MoS2 with a direct band-gap, h-BN/MoS2/h-BN has an indirect band-gap. Particular attention has been focused on the engineering of the band-gap of the h-BN/MoS2/h-BN heterostructure via application of an external electric field. With the increase of electric field, the band-gap of the h-BN/MoS2/h-BN heterostructure undergoes an indirect-to-direct band-gap transition. Once the electric field intensity is larger than 0.1 V Å-1, the gap value of direct band-gap shrinks almost linearly with the field-strength, which indicates that the h-BN/MoS2/h-BN heterostructure is a viable candidate for optoelectronic applications.

  10. Atomic Layer Epitaxy of h-BN(0001) Multilayers on Co(0001) and Molecular Beam Epitaxy Growth of Graphene on h-BN(0001)/Co(0001).

    Science.gov (United States)

    Driver, M Sky; Beatty, John D; Olanipekun, Opeyemi; Reid, Kimberly; Rath, Ashutosh; Voyles, Paul M; Kelber, Jeffry A

    2016-03-22

    The direct growth of hexagonal boron nitride (h-BN) by industrially scalable methods is of broad interest for spintronic and nanoelectronic device applications. Such applications often require atomically precise control of film thickness and azimuthal registry between layers and substrate. We report the formation, by atomic layer epitaxy (ALE), of multilayer h-BN(0001) films (up to 7 monolayers) on Co(0001). The ALE process employs BCl3/NH3 cycles at 600 K substrate temperature. X-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED) data show that this process yields an increase in h-BN average film thickness linearly proportional to the number of BCl3/NH3 cycles, with BN layers in azimuthal registry with each other and with the Co(0001) substrate. LEED diffraction spot profile data indicate an average BN domain size of at least 1900 Å. Optical microscopy data indicate the presence of some domains as large as ∼20 μm. Transmission electron microscopy (TEM) and ambient exposure studies demonstrate macroscopic and microscopic continuity of the h-BN film, with the h-BN film highly conformal to the Co substrate. Photoemission data show that the h-BN(0001) film is p-type, with band bending near the Co/h-BN interface. Growth of graphene by molecular beam epitaxy (MBE) is observed on the surface of multilayer h-BN(0001) at temperatures of 800 K. LEED data indicate azimuthal graphene alignment with the h-BN and Co(0001) lattices, with domain size similar to BN. The evidence of multilayer BN and graphene azimuthal alignment with the lattice of the Co(0001) substrate demonstrates that this procedure is suitable for scalable production of heterojunctions for spintronic applications.

  11. Further delays hit troubled $2bn cosmic-ray detector

    CERN Multimedia

    Cartlidge, Edwin

    2010-01-01

    "A $2bn mission to study cosmic rays will have to wait another few months before being sent to the International Space Station (ISS) after NASA announced last month that it was pushing back the launch of the Space Shuttle Endeavour until 26 February 2011" (0.5 page)

  12. Electrochemical characterization of TiN coatings

    Energy Technology Data Exchange (ETDEWEB)

    Piippo, J. (Swiss Federal Inst. of Tech., Inst. of Materials Chemistry and Corrosion, Zuerich (Switzerland)); Elsener, B. (Swiss Federal Inst. of Tech., Inst. of Materials Chemistry and Corrosion, Zuerich (Switzerland)); Boehni, H. (Swiss Federal Inst. of Tech., Inst. of Materials Chemistry and Corrosion, Zuerich (Switzerland))

    1993-12-03

    The corrosion behaviour of titanium nitride (TiN) CVD coatings on AISI 316L stainless steel and on inert Si[sub 3]N[sub 4] in hydrochloric acid is studied with a.c. and d.c. electrochemical methods. The electrochemical behaviour of TiN on stainless steel can be divided into active and passive behaviour according to the state of the substrate. The measurements indicate that there is an oxide layer on TiN that is responsible for its noble electrochemical behaviour. A model that describes the formation of the oxide layer on TiN in an electrolyte is proposed. (orig.)

  13. Band-gap control in phosphorene/BN structures from first-principles calculations

    Science.gov (United States)

    Marsoner Steinkasserer, Lukas Eugen; Suhr, Simon; Paulus, Beate

    2016-09-01

    Using both DFT as well as G0W0 calculations, we investigate static and dynamic effects on the phosphorene band gap upon deposition and encapsulation on/in BN multilayers. We demonstrate how competing long- and short-range effects cause the phosphorene band gap to increase at low P -BN interlayer spacings, while the band gap is found to drop below that of isolated phosphorene in the BN/P bilayer at intermediate distances around 4 Å. Subsequent stacking of BN layers, i.e., BN/BN/P and BN/BN/BN/P is found to have a negligible effect at the DFT level while at the G0W0 level, increased screening lowers the band gap as compared to the BN/P bilayer. Encapsulation between two BN layers, on the other hand, is found to further increase the phosphorene band gap with respect to the BN/P bilayer. Lastly we investigate the use of the GLLB-SC functional as a starting point for G0W0 calculations showing it to, in the case of phosphorene, yield results close to those obtained from G W0@P B E .

  14. Refined exposure assessment for Brilliant Black BN (E 151

    Directory of Open Access Journals (Sweden)

    European Food Safety Authority

    2015-01-01

    Full Text Available The European Food Safety Authority (EFSA carried out an exposure assessment of Brilliant Black BN (E 151, taking into account new information on its use as a food additive in foods. In 2010, the EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS adopted a scientific opinion on the re-evaluation of Brilliant Black BN and concluded that dietary exposure in 1- to 10-year-old children at the high level may exceed the Acceptable Daily Intake (ADI for Brilliant Black BN of 5 mg/kg body weight (bw/day at the upper end of the range. Following this conclusion, the European Commission requested that EFSA performs a refined exposure assessment for this food colour. Data on the presence of Brilliant Black BN in foods were requested from relevant stakeholders through a call for usage and concentration data. Usage levels were provided to EFSA for 11 out of 37 food categories in which Brilliant Black is authorised. In addition, 4 337 analytical results were also reported to EFSA, with the majority of values being below the limit of detection (LOD or limit of quantification (LOQ. Exposure assessment was performed using the EFSA Comprehensive Food Consumption Database. Three scenarios were considered: (1 exposure estimates based on Maximum Permitted Levels (MPLs, (2 a refined brand-loyal exposure scenario, and (3 a refined non-brand-loyal exposure scenario. Considering the first scenario, high exposure levels (95th percentile exceeded the ADI for toddlers and children in four dietary surveys. In comparison with the previous assessment, for both children and adults, the current mean exposure estimates are of the same order of magnitude, whereas the 95th percentile exposure is lower, particularly in adults. The mean and high-level exposure estimates of Brilliant Black BN are below the ADI for all population groups when considering the refined scenarios (brand-loyal and non-brand-loyal.

  15. Dynamic chiral-at-metal stability of tetrakis(d/l-hfc)Ln(III) complexes capped with an alkali metal cation in solution.

    Science.gov (United States)

    Lin, Yiji; Zou, Fang; Wan, Shigang; Ouyang, Jie; Lin, Lirong; Zhang, Hui

    2012-06-14

    Chiral tetrakis(β-diketonate) Ln(III) complexes Δ-[NaLa(d-hfc)(4)(CH(3)CN)] (1) and Λ-[NaLa(l-hfc)(4) (CH(3)CN)] (2) (d/l-hfc(-) = 3-heptafluo-robutylryl-(+)/(-)-camphorate) are a pair of enantiomers and crystallize in the same Sohncke space group (P2(1)2(1)2(1)) with dodecahedral (DD) geometry. Typically positive and negative exciton splitting patterns around 320 nm were observed in the solid-state circular dichroism (CD) spectra of complexes 1 and 2, which indicate that their shell configurational chiralities are Δ and Λ, respectively. The apparent bisignate couplets in the solid-state CD spectra of [CsLn(d-hfc)(4)(H(2)O)] [Ln = La (3), Yb (5)] and [CsLn(l-hfc)(4)(H(2)O)] [Ln = La (4), Yb (6)] show that they are a pair of enantiomers and their absolute configurations are denoted Δ and Λ, respectively. The crystallographic data of 5 reveals that its coordination polyhedron is the square antiprism (SAP) geometry and it undergoes a phase transition from triclinic (α phase, P1) to monoclinic (β phase, C2) upon cooling. The difference between the two phases is brought about by the temperature dependent behaviour of the coordination water molecules, but this did not affect the configurational chirality of the Δ-SAP-[Yb(d-hfc)(4)](-) moiety. Furthermore, time-dependent CD, UV-vis and (19)F NMR were applied to study the solution behavior of these complexes. It was found that the chiral-at-metal stability of the three pairs of complexes is different and affected by both the Ln(3+) and M(+) ion size. The results show that the Cs(+) cation can retain the metal center chirality and stablize the structures of [Ln(d/l-hfc)(4)](-) or the dissociated tris(d/l-hfc)Ln(III) species in solution for a longer time than that of the Na(+) cation, and it is important that the Cs(+) ion successfully lock the configurational chirality around the Yb(3+) center of the complex species in solution. This is reasoned by the short Cs(+)···FC, Cs(+)···O-Yb and Cs(+)···Yb(3

  16. Estimated 2017 refrigerant emissions of 2,3,3,3-tetrafluoropropene (HFC-1234yf) in the United States resulting from automobile air conditioning.

    Science.gov (United States)

    Papasavva, Stella; Luecken, Deborah J; Waterland, Robert L; Taddonio, Kristen N; Andersen, Stephen O

    2009-12-15

    In response to recent regulations and concern over climate change, the global automotive community is evaluating alternatives to the current refrigerant used in automobile air conditioning units, 1,1,1,2-tetrafluoroethane, HFC-134a. One potential alternative is 2,3,3,3-tetrafluoropropene (HFC-1234yf, also known as HFO-1234yf). We have developed a spatially and temporally resolved inventory of likely future HFC refrigerant emissions from the U.S. vehicle fleet in 2017, considering regular, irregular, servicing, and end-of-life leakages. We estimate the annual leak rate emissions for each leakage category for a projected 2017 U.S. vehicle fleet by state, and spatially apportion these leaks to a 36 km square grid over the continental United States. This projected inventory is a necessary first step in analyzing for potential atmospheric and ecosystem effects, such as ozone and trifluoroacetic acid production, that might result from widespread replacement of HFC-134a with HFC-1234yf.

  17. R.F. magnetron sputtering of multilayered c-BN films on cemented carbide tool.

    Science.gov (United States)

    Park, Sungtae; Jeong, Sehoon; Lee, Kwangmin

    2011-02-01

    A c-BN thin film was deposited using a B4C target in a r.f. magnetron sputtering system. The c-BN layer was coated with a TiAIN adhesion layer (approximately 2 microm), boron carbide (approximately 1 microm) and BCN (10 approximately 15 nm) nano-gradient layer system. The c-BN layers with thicknesses of more than 0.5 microm were successfully deposited onto cemented carbide substrates. The high resolution XPS spectra analysis of B1s and N1s revealed that the c-BN film was mainly composed of sp3 BN bonds.

  18. Radioecological impacts of tin mining.

    Science.gov (United States)

    Aliyu, Abubakar Sadiq; Mousseau, Timothy Alexander; Ramli, Ahmad Termizi; Bununu, Yakubu Aliyu

    2015-12-01

    The tin mining activities in the suburbs of Jos, Plateau State, Nigeria, have resulted in technical enhancement of the natural background radiation as well as higher activity concentrations of primordial radionuclides in the topsoil of mining sites and their environs. Several studies have considered the radiological human health risks of the mining activity; however, to our knowledge no documented study has investigated the radiological impacts on biota. Hence, an attempt is made to assess potential hazards using published data from the literature and the ERICA Tool. This paper considers the effects of mining and milling on terrestrial organisms like shrubs, large mammals, small burrowing mammals, birds (duck), arthropods (earth worm), grasses, and herbs. The dose rates and risk quotients to these organisms are computed using conservative values for activity concentrations of natural radionuclides reported in Bitsichi and Bukuru mining areas. The results suggest that grasses, herbs, lichens, bryophytes and shrubs receive total dose rates that are of potential concern. The effects of dose rates to specific indicator species of interest are highlighted and discussed. We conclude that further investigation and proper regulations should be set in place in order to reduce the risk posed by the tin mining activity on biota. This paper also presents a brief overview of the impact of mineral mining on biota based on documented literature for other countries.

  19. Optimization of electrodeposition processes for tin coatings

    Science.gov (United States)

    Wen, Shixue

    The mechanism of nucleation and growth of tin electrodeposits was investigated. Also the influences of the operating parameters on the morphology, texture, and microstructure as well as the corrosion resistance of tin coatings were studied in order to propose optimum deposition conditions. Tin electrodeposition on glassy carbon and steel from acid sulfate electrolytes proceeds via the 3D (Volmer-Weber) mechanism. On low carbon steel substrates, 3D tin crystallites are initially formed preferentially on step edges, followed by fast deposition of other sites with much smaller and densely packed crystallites of about 150-180 nm in diameter. It was discovered that hydrogen co-evolution and gelatin have a synergy effect contributing to the fast and complete coverage of steel substrate with tin. The cathodic potential oscillation of tin (II) reduction in the tin electrolyte is attributed to the depletion and restoration of tin ions on the cathode surface. It has been found that an increase in current density improves the coverage of the substrate or the covering power. Without agitation, the deposits are powdery at high current densities. In order to obtain smooth and compact coatings, agitation is crucial when the applied current density is well above the limiting value. Tin coatings with two different fibre textures, (100) and (301) were produced by electrodeposition. At a lower current density of 100 A/m 2, (301) fibre was obtained. At the current densities of 100 and up to 400 A/m2, only (100) fibre texture was observed. An increase in current density leads to a decrease in grain size. At the same current density, the grain size of tin coatings increases with increased temperature. The influence of temperature (20, 40, 60 and 80°C) on texture is small. The corrosion resistance of tin coatings increases with a decrease in grain size. The corrosion resistance of tin coatings with (301) fibre was higher than that of the tin coating with (100) fibre texture. The optimum

  20. Atmospheric observations for quantifying emissions of point-source synthetic greenhouse gases (CF4, NF3 and HFC-23)

    Science.gov (United States)

    Arnold, Tim; Manning, Alistair J.; Li, Shanlan; Kim, Jooil; Park, Sunyoung; Fraser, Paul J.; Mitrevski, Blagoj; Steele, L. Paul; Krummel, Paul B.; Mühle, Jens; Weiss, Ray F.

    2016-04-01

    The fluorinated species carbon tetrafluoride (CF4; PFC-14), nitrogen trifluoride (NF3) and trifluoromethane (CHF3; HFC-23) are potent greenhouse gases with 100-year global warming potentials of 6,630, 16,100 and 12,400, respectively. Unlike the majority of CFC-replacement compounds that are emitted from fugitive and mobile emission sources, these gases are largely emitted from large single point sources - semiconductor manufacturing facilities (all three), aluminium smelting plants (CF4) and chlorodifluoromethane factories (HFC-23). In this work we show the potential for atmospheric measurements to understand regional sources of these gases and to highlight emission 'hotspots'. We target our analysis on measurements from two Advanced Global Atmospheric Gases Experiment (AGAGE) long term monitoring sites that are particularly sensitive to regional emissions of these gases: Gosan on Jeju Island in the Republic of Korea and Cape Grim on Tasmania in Australia. These sites measure CF4, NF3 and HFC-23 alongside a suite of greenhouse and stratospheric ozone depleting gases every two hours using automated in situ gas-chromatography mass-spectrometry instrumentation. We couple each measurement to an analysis of air history using the regional atmospheric transport model NAME (Numerical Atmospheric dispersion Modelling Environment) driven by 3D meteorology from the Met Office's Unified Model, and use a Bayesian inverse method (InTEM - Inversion Technique for Emission Modelling) to calculate yearly emission changes over a decade (2005-2015) at high spatial resolution. At present these gases make a small contribution to global radiative forcing, however, given that their impact could rise significantly and that point sources of such gases can be mitigated, atmospheric monitoring could be an important tool for aiding emissions reduction policy.

  1. Quantifying India's HFC emissions from whole-air samples collected on the UK-India Monsoon campaign

    Science.gov (United States)

    Say, Daniel; Ganesan, Anita; O'Doherty, Simon; Bauguitte, Stephane; Rigby, Matt; Lunt, Mark

    2017-04-01

    With a population exceeding 1 billion and a rapidly expanding economy, greenhouse gas (GHG) emissions from India are of global significance. As of 2010, India's anthropogenic GHG emissions accounted for 5.6% of the global total, with this share predicted to grow significantly in the coming decades. We focus here on hydrofluorocarbons (HFCs), a diverse range of potent GHGs, whose role as replacements for ozone-depleting CFCs and HCFCs in air-conditioning and refrigeration applications (among others) has led to rapid atmospheric accumulation. Recent efforts to reduce their consumption (and subsequent emission) culminated in an amendment to the Montreal Protocol; member states are now required to phase-down their use of HFCs, with the first cuts planned for 2019. Despite the potential climate implications, atmospheric measurements of HFCs in India, required for quantifying their emissions using top-down inverse methods, have not previously existed. Here we present the first Indian hydrofluorocarbon (HFC) observations, obtained during two months of low altitude (<2000 m) flights. Of the 176 whole air samples collected on board the UK's NERC-FAAM (Facility for Airborne Atmospheric Measurements) research aircraft, the majority were obtained above the Indo-Gangetic Plains of Northern India, where population density is greatest. Using a small subset of samples filled above the Arabian Sea, we derive compound specific baselines, to which the remaining samples are compared. Significant mole fraction enhancements are observed for all major HFCs, indicating the presence of regional emissions sources. Little enhancement is observed in the concentration of various HFC predecessors, including CFCs, suggesting India's success in phasing out the majority of ozone depleting substances. Using these atmospheric observations and the NAME (Numerical Atmospheric dispersion Modelling Environment) atmospheric transport model, we present the first regional HFC flux estimates for India.

  2. Performance testing of a semi-hermetic compressor with HFC-236EA and CFC-114 at chiller conditions. Report for December 1993-May 1994

    Energy Technology Data Exchange (ETDEWEB)

    Kazachki, G.S.; Hendriks, R.V.

    1994-12-31

    The paper gives results of tests of both HFC-236ea and CFC-114 at a range of temperatures covering surface craft and submarine chiller conditions. Evaporating temperatures ranged from 1.7 to 12.8 C, and condensing temperatures from 40.6 to 65.6 C, in order to develop a nine-point test map. Polyol ester oil was used with the refrigerants. The tests evaluated suction and discharge pressures, their difference and ratio, cooling capacity, electric power input, compressor energy efficiency ratio (coefficient of performance), electric current, and compressor volumetric and isentropic energy efficiency. Compressor discharge, motor winding, and oil temperature were also monitored. HFC-236ea is one of the strongest candidates for a CFC-114 alternative in surface craft and submarine chillers. Some material compatibility and oil miscibility work has also been performed in support of HFC-236ea as a refrigerant.

  3. Uranium in cassiterites of tin deposits

    Energy Technology Data Exchange (ETDEWEB)

    Zagruzina, I.A.; Pinskij, Eh.M.; Savinova, I.B.

    1986-01-01

    For the purpose of elucidation of physico-chemical features of uranium and tin behaviour in ore deposition zones uranium determinations (1000 determ) in cassiterite grains from 55 tin-ore deposits of different formation types of several separate regions are carried out by means of fission radiography. It is shown that uranium content in cassiterites is a genetic sign. Peculiarities of uranium concentration and migration in tin deposits permit to use them as prognostic radiogeochemical criteria. Radiogeochemical prognostic-search signs confirm the antagonism between uranium and tin deposits of cassiterite-silicate and cassiterite-sulfide formations and paragenetic of certain types of uranium hydrothermal deposits with tin deposits of cassiterite-quartz formation.

  4. Structural studies of supported tin catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Nava, Noel [Instituto Mexicano del Petroleo, Gerencia de Catalizadores (Mexico); Viveros, Tomas [Universidad Autonoma Metropolitana-Iztapalapa, Area de Ingenieria Quimica (Mexico)

    1999-11-15

    Tin oxide was supported on aluminium oxide, titanium oxide, magnesium oxide and silicon oxide, and the resulting interactions between the components in the prepared samples and after reduction were characterized by Moessbauer spectroscopy. It was observed that in the oxide state, tin is present as SnO{sub 2} on alumina, magnesia and silica, but on titania tin occupies Ti sites in the structure. After hydrogen treatment at high temperatures, tin is reduced from Sn(4) to Sn(2) on alumina and titania; it is reduced from Sn(4) to Sn(0) on silica, and is practically not reduced on magnesia. These results reveal the degree of interaction between tin and the different supports studied.

  5. Biological Efficacy of Streptomyces sp. Strain BN1 against the Cereal Head Blight Pathogen Fusarium graminearum

    Directory of Open Access Journals (Sweden)

    Boknam Jung

    2013-03-01

    Full Text Available Fusarium head blight (FHB caused by the filamentous fungus Fusarium graminearum is one of the most severe diseases threatening the production of small grains. Infected grains are often contaminated with mycotoxins such as zearalenone and trichothecences. During survey of contamination by FHB in rice grains, we found a bacterial isolate, designated as BN1, antagonistic to F. graminearum. The strain BN1 had branching vegetative hyphae and spores, and its aerial hyphae often had long, straight filaments bearing spores. The 16S rRNA gene of BN1 had 100% sequence identity with those found in several Streptomyces species. Phylogenetic analysis of ITS regions showed that BN1 grouped with S. sampsonii with 77% bootstrap value, suggesting that BN1 was not a known Streptomyces species. In addition, the efficacy of the BN1 strain against F. graminearum strains was tested both in vitro and in vivo. Wheat seedling length was significantly decreased by F. graminearum infection. However, this effect was mitigated when wheat seeds were treated with BN1 spore suspension prior to F. graminearum infection. BN1 also significantly decreased FHB severity when it was sprayed onto wheat heads, whereas BN1 was not effective when wheat heads were point inoculated. These results suggest that spraying of BN1 spores onto wheat heads during the wheat flowering season can be efficient for plant protection. Mechanistic studies on the antagonistic effect of BN1 against F. graminearum remain to be analyzed.

  6. The electric properties and the current-controlled differential negative resistance of cBN crystal

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The electric properties of nonintentionally doped n-cubic boron nitride(cBN) crystal are investigated.The cBN crystal was transformed from hexagonal-boron nitride(h-BN) under high pressure(HP) and high temperature(HT) using magnesium powder as catalyst.At room temperature,the current-voltage(I-V) characteristics of cBN crystal are measured and found to be nonlinear.When the electric field is in the range of(1―1.5)×105 V/cm,the avalanche breakdown occurs inside the whole cBN crystal.At this same time,the bright blue-violet with the wavelength of 380―400 nm from the cBN crystal is observed.When measuring the I-V curve after breakdown of cBN crystal,the current-controlled differential negative resistance phenomenon is observed.The breakdown is repeatable.

  7. HFO1234ze(E) And HFC134a Flow Boiling Inside a 4mm Horizontal Smooth Tube

    OpenAIRE

    Longo, Giovanni A.; Mancin, Simone; Righetti, Giulia; Zilio, Claudio

    2016-01-01

    Nowadays, the substitution of HFC134a with low GWP refrigerants is one of the most important challenge for refrigeration and air conditioning. The possible substitutes include natural refrigerants, such as HC600 (Butane) and HC600a (Isobutane), and also synthetic refrigerants, such as HFO1234yf and HFO1234ze(E). The HC refrigerants exhibit very low GWP, 3 and 4 HC600a and HC600 respectively, good thermodynamic and transport properties, and pressure and volumetric performance very similar to H...

  8. Accelerating growth of HFC-227ea (1,1,1,2,3,3,3-heptafluoropropane) in the atmosphere

    DEFF Research Database (Denmark)

    Laube, J.C.; Martinerie, P.; Witrant, E.

    2010-01-01

    We report the first measurements of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), a substitute for ozone depleting compounds, in air samples originating from remote regions of the atmosphere and present evidence for its accelerating growth. Observed mixing ratios ranged from below 0.01 ppt in deep...... firn air to 0.59 ppt in the current northern mid-latitudinal upper troposphere. Firn air samples collected in Greenland were used to reconstruct a history of atmospheric abundance. Year-on-year increases were deduced, with acceleration in the growth rate from 0.029 ppt per year in 2000 to 0.056 ppt per...

  9. Lattice vibrational properties of transition metal carbides (TiC, ZrC and HfC)

    Indian Academy of Sciences (India)

    K S Upadhyaya; Ajay Kumar Singh; Atul Pandey; S N Pathak; A K Singh

    2005-02-01

    Lattice vibrational properties of transition metal carbides (TiC, ZrC and HfC) have been presented by including the effects of free-carrier doping and three-body interactions in the rigid shell model. The short-range overlap repulsion is operative up to the second neighbour ions. An excellent agreement has been obtained between theory and experiment for their phonon dispersion curves and Debye temperature variations. It is concluded that the contributions of free-carrier doping and three-body interactions are essential for the description of the lattice dynamics of these carbides.

  10. Substituting HCFC-22 for HFC-410A: an environmental impact trade-off between the ozone depletion and climate change regimes

    Science.gov (United States)

    Wang, Z.; Fang, X.; Zhang, J.

    2015-12-01

    After the phase-out of hydrochlorofluorocarbons (HCFCs) as ozone-depleting substances pursuant to the requirements of the Montreal Protocol, hydrofluorocarbons (HFCs) are worldwide used as substitutes although the bulk of them are potent greenhouse gases (GHGs). Therefore, the alternation may bring side effect on global climate change. The trade-off of its environmental impacts between the ozone depletion and climate change regimes necessitates a quantification of the past and future consumption and emissions of both the original HCFCs and their alternative HFCs. Now a dilemma arise in China's RAC industry that HCFC-22, which has an ozone-depleting potential (ODP) of 0.055, has been replaced by HFC-410A, which is a blended potent GHG from respective 50% HFC-32 and HFC-125 with a global warming potential (GWP) of 1923.5. Here, we present our results of estimates of consumption and emissions of HCFC-22 and HFC-410A from 1994 to 2050. Historic emissions of HCFC-22 contributed to global total HCFCs by 4.0% (3.0%-5.6%) ODP-weighted. Projection under a baseline scenario shows future accumulative emissions of HFC-410A make up 5.9%-11.0% of global GWP-weighted HFCs emissions, and its annual contribution to national overall CO2 emissions can be 5.5% in 2050. This makes HCFC-22 and HFC-410A emissions of significant importance in ozone depletion and climate change regimes. Two mitigation scenarios were set to assess the mitigation performance under the North America Proposal and an accelerated schedule. In practice of international environmental agreement, "alternative to alternative" should be developed to avoid regrettable alternations.

  11. Electrodeposition and characterization of Co–BN (h) nanocomposite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Shahri, Z.; Allahkaram, S.R., E-mail: akaram@ut.ac.ir; Zarebidaki, A.

    2013-07-01

    Co–BN (h) nanocomposite coatings were prepared by means of the conventional electrodeposition in a chloride solution containing different concentrations of hexagonal boron nitride particles, and pure Co coating was also prepared as a comparison. Morphology of the coatings and the effect of incorporated particles on metal matrix structure and composition were investigated via scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction analysis. Microhardness, roughness, friction coefficient and wear resistance of the coatings were also evaluated using Vickers microhardness, stylus profilometer and pin-on disk machine. The results showed that Co–BN (h) nanocomposite coatings exhibit higher hardness and lower friction coefficient. Roughness and wear resistance compared with that of the pure Co coating obtained under the same electrodeposition condition and the wear mechanism of the coatings were also discussed.

  12. Bandgap oscillation in quasiperiodic carbon-BN nanoribbons

    Science.gov (United States)

    Pedreira, D. O.; Azevedo, S.; Bezerra, C. G.; Viol, A.; Viswanathan, G. M.; Ferreira, M. S.

    2014-02-01

    In this work we address the effects of quasiperiodic disorder on the physical properties of nanoribbons, composed by BN and C, constructed according to the Fibonacci quasiperiodic sequence. We assume BN and C as the building blocks of the resulting quasiperiodic structure. The density of states and energy band gap were obtained through ab-initio calculations based on the density functional theory. We report the effects of the quasiperiodic disorder on the oscillatory behavior of the specific heat, in the low temperature regime, and on the behavior of the energy band gap. In particular, we show that the electronic energy band gap oscillates as a function of the Fibonacci generation index n. Our results suggest that the choice of the building block materials of the quasiperiodic sequence, with appropriate band gap energies, may lead to a tuneable band gap of quasiperiodic nanoribbons.

  13. Identification and Characterization of 1,2-BN Cyclohexene Using Microwave Spectroscopy

    Science.gov (United States)

    Kukolich, Stephen G.; Sun, Ming; Daly, Adam M.; Ishibashi, Jacob S. A.; Liu, Shih-Yuan

    2016-06-01

    1,2-BN Cyclohexene was produced from 1,2-BN Cyclohexane through the loss of H_2 and characterized and identified using a pulsed-beam Fourier-transform microwave spectrometer. The first microwave spectra for 1,2-10BN Cyclohexene 1,2-11BN Cyclohexene have been measured in the frequency range of 5.5-12.5 GHz, providing accurate rotational constants and nitrogen and boron quadrupole coupling strengths for two isotopologues. High-level ab initio calculations provided rotational constants and quadrupole coupling strengths for the precursor 1,2-BN Cyclohexane (C_4H12BN) and 1,2-BN Cyclohexene(C_4H10BN). Calculated molecular properties for 1,2-BN Cyclohexene are in very good agreement with measured parameters. Calculated parameters for the starting material, 1,2-BN Cyclohexane do not agree with the experimental data. Rotational constants for 1,2-11BN Cyclohexene are A = 4702.058(2) MHz, B = 4360.334(1) MHz and C = 2494.407(1) MHz. The inertial defect is Δ_0 = -20.78 amu-Å^2 clearly indicating a nonplanar structure. These microwave experiments show that heating the initial compound, 1,2-BN Cyclohexane, to 60 C in a 1 atm neon stream results in the loss of H_2 and conversion to 1,2-BN Cyclohexene. This appears to be the first characterization of the 1,2-BN Cyclohexene monomer. Supported by the NSF CHE-1057796 and DOE DE-EE-0005658

  14. Emissions of CO2, CO, NOx, HC, PM, HFC-134a, N2O and CH4 from the global light duty vehicle fleet

    Directory of Open Access Journals (Sweden)

    Timothy J. Wallington

    2008-04-01

    Full Text Available Vehicles emit carbon dioxide (CO2, carbon monoxide (CO, nitrogen oxides (NOx, hydrocarbons (HC, particulate matter (PM, hydrofluorocarbon 134a (HFC-134a, methane (CH4, and nitrous oxide (N2O. An understanding of these emissions is needed in discussions of climate change and local air pollution issues. To facilitate such discussions an overview of past, present, and likely future emissions from light duty vehicles is presented. Emission control technologies have reduced the emissions of CO, VOCs, PM, HFC-134a, CH4, and N2O from modern vehicles to very low levels.

  15. 浅谈TCE供应格局变化对我国HFC-134a行业的影响%HFC-134a In China is Affected by the Change Supply Pattern of TCE

    Institute of Scientific and Technical Information of China (English)

    马文锐; 尹海飞

    2011-01-01

    随着全球经济形势的变化,先是金融危机冲击氯碱行业,国外TCE(三氯乙烯)装置纷纷减产或关停;再有国际氟化工公司战略转型,基础氟化工产品[1](HFC-134a、低端PTFE等)生产向发展中国家转移;后是各国政府纷纷出台政策刺激经济,制冷剂需求持续升温,而其生产原料之一TCE供应格局却发生了翻天覆地的变化,本文详细分析原料TCE对下游HFC-134a行业的深远影响,提出制冷剂行业针对TCE供应格局变化的应对建议。%Along with the changing of global economic,financial crisis impact chlor-alkali industry,foreign TCE(trichloroethylene) device reduce the production or shut down.International fluorine chemical company planned strategic transformation,production of based

  16. Electronic structure of tin monosulfide

    Science.gov (United States)

    Bletskan, D. I.; Bletskan, M. M.; Glukhov, K. E.

    2017-01-01

    The band structure of three-dimensional and two-dimensional tin monosulfide was calculated by the density functional method in LDA and LDA+U approximations. Group-theoretical analysis of the electronic band structure of SnS crystallized in the orthorhombic structure with space group D2h16- Pcmn is carried out, the symmetry of wave functions of the valence band and the bottom of the conduction band is found. The selection rules for direct and indirect optical transitions at different incident light polarization are determined. The group-theoretical analysis of energy states of the three-dimensional and two-dimensional SnS structures explains the formation of the band structure including the Davydov splitting. The calculated total density of states is compared with the known experimental XPS and UPS spectra, providing the assignment of their main features.

  17. Tin compounds and insect fauna

    Energy Technology Data Exchange (ETDEWEB)

    Butovskiy, R.O.

    1985-03-01

    A review of the literature of tin compounds serving as pesticides has resulted in the identification of 11 widely used compounds, both organic and inorganic, with largely fungicidal activity. Organotin compounds seem to be limited in use to the control of insect pests, with the majority of the compounds consisting of Sn(IV) and falling into the following four categories: R/sub 4/Sn, R/sub 3/SNX, R/sub 2/SnX/sub 2/, and RSnX/sub 3/, where R = aliphatic or aromatic hydrocarbon radicals, and X = organic or inorganic substituent. The insecticidal activity of these compounds appears to rest on inhibition of ATPase and uncoupling of oxidative phosphorylation. As a result, these compounds act as larvicides, ovicides and imagocides. 77 references.

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

    Directory of Open Access Journals (Sweden)

    Namir S. Raddaha

    2014-03-01

    Full Text Available 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.

  19. Direct Growth of MoS₂/h-BN Heterostructures via a Sulfide-Resistant Alloy.

    Science.gov (United States)

    Fu, Lei; Sun, Yangyong; Wu, Nian; Mendes, Rafael G; Chen, Linfeng; Xu, Zhen; Zhang, Tao; Rümmeli, Mark H; Rellinghaus, Bernd; Pohl, Darius; Zhuang, Lin; Fu, Lei

    2016-02-23

    Improved properties arise in transition metal dichalcogenide (TMDC) materials when they are stacked onto insulating hexagonal boron nitride (h-BN). Therefore, the scalable fabrication of TMDCs/h-BN heterostructures by direct chemical vapor deposition (CVD) growth is highly desirable. Unfortunately, to achieve this experimentally is challenging. Ideal substrates for h-BN growth, such as Ni, become sulfides during the synthesis process. This leads to the decomposition of the pregrown h-BN film, and thus no TMDCs/h-BN heterostructure forms. Here, we report a thoroughly direct CVD approach to obtain TMDCs/h-BN vertical heterostructures without any intermediate transfer steps. This is attributed to the use of a nickel-based alloy with excellent sulfide-resistant properties and a high catalytic activity for h-BN growth. The strategy enables the direct growth of single-crystal MoS2 grains of up to 200 μm(2) on h-BN, which is approximately 1 order of magnitude larger than that in previous reports. The direct band gap of our grown single-layer MoS2 on h-BN is 1.85 eV, which is quite close to that for free-standing exfoliated equivalents. This strategy is not limited to MoS2-based heterostructures and so allows the fabrication of a variety of TMDCs/h-BN heterostructures, suggesting the technique has promise for nanoelectronics and optoelectronic applications.

  20. Ion sputtering erosion mechanisms of h-BN composite ceramics with textured microstructures

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Xiaoming, E-mail: dxm_hit@126.com [Institute for Advanced Ceramics, Harbin Institute of Technology, Harbin 150001 (China); Ding, Yongjie [School of Energy Science and Technology, Harbin Institute of Technology, Harbin 150001 (China); Jia, Dechang; Jing, Nan; Yang, Zhihua; He, Peigang; Tian, Zhuo; Wang, Shengjin; Wang, Yujin; Zhou, Yu [Institute for Advanced Ceramics, Harbin Institute of Technology, Harbin 150001 (China); Yu, Daren [School of Energy Science and Technology, Harbin Institute of Technology, Harbin 150001 (China)

    2014-11-15

    Highlights: • Textured h-BN ceramics were made by hot press sintering using mullite as additives. • Sintering pressures play important role on ions sputtering resistance properties. • Textured microstructures lead to various surface morphologies by ion sputtering. • Sputtering erosion mechanisms include B–N bonds breaking and BN layers delamination. - Abstract: Since the hexagonal boron nitride (h-BN) grain shows typical lamellar structures, textured materials can be obtained by arranging h-BN grains along one direction. In this work, textured h-BN composite ceramics with the c-axis orientation arranged along the pressure direction are manufactured by hot-press sintering using mullite as the sintering additive. The results show that sintering pressures not only play a major role in the density and the textured degrees of composite ceramics, but also influence Xe ion erosion resistance performances. After Xe ion sputtering, compositions of both h-BN and mullite stay stable, while the elemental compositions have changed due to the so-called “preferential sputtering”. Sputtered surfaces along different orientations show diverse morphologies attributed to the textured microstructures. The erosion mechanisms of h-BN grains during Xe ion sputtering are breaking of B–N bonds and delamination of BN layers. While the mass loss of composite ceramics is due to the erosion of h-BN grains and mullite coupled with partial detachment of h-BN grains from the surface.

  1. Synthesis of tin-containing polyimide films

    Science.gov (United States)

    Ezzell, S. A.; Taylor, L. T.

    1984-01-01

    A series of tin-containing polyimide films derived from either 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride or pyromellitic dianhydride and 4,4'-oxydianiline have been synthesized and their electrical properties examined. Highest quality materials (i.e., homogeneous, smooth surface, flexible) with the best electrical properties were doped with either SnCl2.2H2O or (n-Bu)2SnCl2. In all cases, extensive reactivity of the tin dopant with water, air or polyamic acid during imidization is observed. Lowered electrical surface resistivities appear to be correlatable with the presence of surface tin oxide on the film surface.

  2. Tuning band gaps of BN nanosheets and nanoribbons via interfacial dihalogen bonding and external electric field.

    Science.gov (United States)

    Tang, Qing; Bao, Jie; Li, Yafei; Zhou, Zhen; Chen, Zhongfang

    2014-08-07

    Density functional theory computations with dispersion corrections (DFT-D) were performed to investigate the dihalogen interactions and their effect on the electronic band structures of halogenated (fluorinated and chlorinated) BN bilayers and aligned halogen-passivated zigzag BN nanoribbons (BNNRs). Our results reveal the presence of considerable homo-halogen (FF and ClCl) interactions in bilayer fluoro (chloro)-BN sheets and the aligned F (Cl)-ZBNNRs, as well as substantial hetero-halogen (FCl) interactions in hybrid fluoro-BN/chloro-BN bilayer and F-Cl-ZBNNRs. The existence of interfacial dihalogen interactions leads to significant band-gap modifications for the studied BN nanosystems. Compared with the individual fluoro (chloro)-BN monolayers or pristine BNNRs, the gap reduction in bilayer fluoro-BN (B-FF-N array), hybrid fluoro-BN/chloro-BN bilayer (N-FCl-N array), aligned Cl-ZBNNRs (B-ClCl-N alignment), and hybrid F-Cl-ZBNNRs (B-FCl-N alignment) is mainly due to interfacial polarizations, while the gap narrowing in bilayer chloro-BN (N-ClCl-N array) is ascribed to the interfacial nearly-free-electron states. Moreover, the binding strengths and electronic properties of the interactive BN nanosheets and nanoribbons can be controlled by applying an external electric field, and extensive modulation from large-gap to medium-gap semiconductors, or even metals can be realized by adjusting the direction and strength of the applied electric field. This interesting strategy for band gap control based on weak interactions offers unique opportunities for developing BN nanoscale electronic devices.

  3. A Win for the Future of Tin

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Drinking that draft beer from a glass? Why not try tin products instead—they keep your beer cooler and more refreshing longer than glasses! In 1885, Yong Koon, a young man from Guangdong Province, traveled

  4. Mitigating tin whisker risks theory and practice

    CERN Document Server

    Handwerker, Carol A; Bath, Jasbir

    2016-01-01

    Discusses the growth mechanisms of tin whiskers and the effective mitigation strategies necessary to reduce whisker growth risks. This book covers key tin whisker topics, ranging from fundamental science to practical mitigation strategies. The text begins with a review of the characteristic properties of local microstructures around whisker and hillock grains to identify why these particular grains and locations become predisposed to forming whiskers and hillocks. The book discusses the basic properties of tin-based alloy finishes and the effects of various alloying elements on whisker formation, with a focus on potential mechanisms for whisker suppression or enhancement for each element. Tin whisker risk mitigation strategies for each tier of the supply chain for high reliability electronic systems are also described.

  5. Estimated 2017 Refrigerant Emissions of 2,3,3,3-Tetrafluoropropene (HFC-1234yf) in the United States Resulting from Automobile Air Conditioning

    Science.gov (United States)

    In response to recent regulations and concern over climate change, the global automotive community is evaluating alternatives to the current refrigerant used in automobile air conditioning units, 1,1,1,2-tetrafluoroethane, HFC-134a. One potential alternative is 2,3,3,3-tetrafluor...

  6. Estimated 2017 Refrigerant Emissions of 2,3,3,3-Tetrafluoropropene (HFC-1234yf) in the United States Resulting from Automobile Air Conditioning

    Science.gov (United States)

    In response to recent regulations and concern over climate change, the global automotive community is evaluating alternatives to the current refrigerant used in automobile air conditioning units, 1,1,1,2-tetrafluoroethane, HFC-134a. One potential alternative is 2,3,3,3-tetrafluor...

  7. Diseño de una red urbana HFC para la distribución de servicios avanzados de telecomunicación.

    OpenAIRE

    2001-01-01

    Este traba}o presenta el diseño de la infraestructura básica correspondiente a una arquitectura de red híbrida fibra óptica-cable coaxial (HFC) para la distribución de contenidos telemáticos integrados por cable en pequeños núcleos

  8. Effects of Temperature Raising Speed on the Growth of BN Crystals in Hydrothermal Solutions

    Institute of Scientific and Technical Information of China (English)

    YU,Mei-Yan(于美燕); LI,Kai(李凯); CUI,De-Liang(崔得良); DONG,Shou-Yi(董守义); WANG,Qi-Long(王琪珑); JIANG,Min-Hua(蒋民华)

    2004-01-01

    Cubic boron nitride (cBN) and orthorhombic boron nitride (oBN) crystals have been prepared in hydrothermal solutions by reacting H3BO3+NaN3+P and H3BO3+NaN3+N2H4 respectively. The experimental results indicated that, if the temperature was increased rapidly, both the yield and perfectness of BN crystals became poor. On the contrast, the yield and perfectness of BN crystals can be improved very much by slowly increasing the temperature of the reaction mixture. The results of X-ray powder diffraction (XRD), Fourier transform infrared spectrum (FTIR)and high resolution transmission electron microscopy (HRTEM) proved that the samples were composed of oBN and cBN.

  9. First-principles study of the noble metal-doped BN layer

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yungang; Yang, Ping; Sun, Xin; Wang, Zhiguo; Zu, Xiaotao T.; Gao, Fei

    2011-04-18

    Intriguing electronic and magnetic properties of BN layer with noble metal (Pd, Pt, Ag and Au) doping are obtained by first-principles calculations. Adsorbed Pd (or Pt) reduces the band gap of BN sheet owing to the induction of impurity states. The unpaired electrons in the Ag (or Au)-adsorbed and the Pd (or Pt)-substituted BN layers are polarized, and thus exhibit a magnetic moment of 1.0 µB, leading to these BN configurations to be magnetic semiconductors. The half-metallic feature of the Ag-substituted BN layer, along with the delocalization of spin states, renders this configuration an excellent spin filter material. Thus, these findings offer a unique opportunity for developing BN-based nanoscale devices.

  10. Space Shuttle Program Tin Whisker Mitigation

    Science.gov (United States)

    Nishimi, Keith

    2007-01-01

    The discovery of tin whiskers (TW) on space shuttle hardware led to a program to investigate and removal and mitigation of the source of the tin whiskers. A Flight Control System (FCS) avionics box failed during vehicle testing, and was routed to the NASA Shuttle Logistics Depot for testing and disassembly. The internal inspection of the box revealed TW growth visible without magnification. The results of the Tiger Team that was assembled to investigate and develop recommendations are reviewed in this viewgraph presentation.

  11. Global and regional emissions estimates of 1,1-difluoroethane (HFC-152a, CH3CHF2 from in situ and air archive observations

    Directory of Open Access Journals (Sweden)

    P. G. Simmonds

    2015-08-01

    Full Text Available High frequency, ground-based, in situ measurements from eleven globally-distributed sites covering 1994–2014, combined with measurements of archived air samples dating from 1978 onward and atmospheric transport models, have been used to estimate the growth of 1,1-difluoroethane (HFC-152a, CH3CHF2 mole fractions in the atmosphere and the global emissions required to derive the observed growth. HFC-152a is a significant greenhouse gas but since it does not contain chlorine or bromine, HFC-152a makes no direct contribution to the destruction of stratospheric ozone and is therefore used as a substitute for the ozone depleting chlorofluorocarbons (CFCs and hydrochlorofluorocarbons (HCFCs. HFC-152a has exhibited substantial atmospheric growth since the first measurements reaching a maximum annualised global growth rate of 0.81 ± 0.05 ppt yr−1 in 2006, implying a substantial increase in emissions up to 2006. However, since 2007, the annualised rate of growth has slowed to 0.38 ± 0.04 ppt yr−1 in 2010 with a further decline to an average rate of change in 2013–2014 of −0.06 ± 0.05 ppt yr−1. The average Northern Hemisphere (NH mixing ratio in 1994 was 1.2 ppt rising to a mixing ratio of 10.2 ppt in December 2014. Average annual mixing ratios in the Southern Hemisphere (SH in 1994 and 2014 were 0.34 and 4.4 ppt, respectively. We estimate global emissions of HFC-152a have risen from 7.3 ± 5.6 Gg yr−1 in 1994 to a maximum of 54.4 ± 17.1 Gg yr−1 in 2011, declining to 52.5 ± 20.1 Gg yr−1 in 2014 or 7.2 ± 2.8 Tg-CO2 eq yr−1. Analysis of mixing ratio enhancements above regional background atmospheric levels suggests substantial emissions from North America, Asia and Europe. Global HFC emissions (so called "bottom up" emissions reported by the United Nations Framework Convention on Climate Change (UNFCCC are based on cumulative national emission data reported to the UNFCCC, which in turn are based on national consumption data. There

  12. Basic research on mechanism of BN inclusion in improving the machinability of steel

    Energy Technology Data Exchange (ETDEWEB)

    Ya-nan, C.; Yan-ping, B.; Min, W.; Xiao-feng, C.; Lin-jing, W.; Li-hua, Z.

    2014-07-01

    Boron nitride-added eco-friendly free cutting steel has recently drawn more and more attention. But, the mechanisms explaining the role of BN inclusions improving the machinability of steels is not very clear. In this investigation, the material removal mechanism for cutting of BN inclusions in steels is explored, using a combination of theoretical analysis and a series of experiments. First, the actual shape of BN inclusions is observed and the amount and distribution of BN inclusions is quantitatively analyzed. Subsequently, the cutting performance of the steel is determined by cutting experimental tests. Moreover, the micro mechanical properties and the material removal mechanisms for cutting of BN inclusions are investigated by means of nano indentation. The results revealed that the BN inclusions are hexagonal and are uniformly distributed, their average content is 23.2 per unit area and their volume fraction is 0.51% in the steel with 74 ppm B and 180 ppm N. It is shown that BN inclusions can improve the cutting performance of steel significantly, and a model describing the material removal mechanism for cutting of BN inclusions is proposed. BN inclusions act as stress concentration source, lubrication and wrap page of hard particles. (Author)

  13. Energetic assessment of HFC-blends as R 22 alternatives; Energetische Bewertung von FKW-Gemischen als R 22-Alternativen

    Energy Technology Data Exchange (ETDEWEB)

    Ahnefeld, G. [Inst. fuer Luft- und Kaeltetehnik gem.GmbH, Dresden (Germany); Vollmer, D. [Inst. fuer Luft- und Kaeltetehnik gem.GmbH, Dresden (Germany); Wobst, E. [Inst. fuer Luft- und Kaeltetehnik gem.GmbH, Dresden (Germany)

    1996-05-01

    Available with ILK is an HFC, HFC-blend test rig, which can be used for testing of refrigerant compressors as well as for industrial plant tests under nearly practical conditions. As compared with R 22, performance measurements of plants operated with the HFC-blends R 407C, R 407A, R 407B, R 404A and R 507 under constant external conditions (temperature difference 5 K between refrigerant/heat carrier, constant refrigerating capacity) showed losses up to 20% for the coefficient of performance. The highest deviations between theoretical cycle calculations and experimental results were obtained on R 407C and R 407A. One reason is an increased temperature glide of the condensing refrigerant caused by pressure drop and subcooling. Energetic benefits can be achieved through installation of an internal heat exchanger at blends with a higher R 125 content (R 407B, R 404A, R 507). (orig.) [Deutsch] Mit der FKW-, FKW-Gemisch-Experimentieranlage steht im ILK eine Versuchseinrichtung zur Verfuegung, die sowohl fuer Verdichterleistungsmessungen als auch fuer anlagentechnische Untersuchungen unter praxisnahen Bedingungen geeignet ist. Anlagenleistungsmessungen mit den zeotropen FKW-Gemischen R 407C, R 407A, R 407B und R 404A sowie dem azeotropen Gemisch R 507 haben bei konstanten aeusseren Bedingungen (Temperaturspreizung des Kaelte-/Waermetragers 5 K, konstante Kaelteleistung) Leistungszahleinbussen bis zu 20% im Vergleich zu R 22 ergeben. Bei R 407C und R 407A weichen die Werte besonders stark von theoretischen Vorausberechnungen (Kreisprozess) ab. Eine wesentliche Ursache ist die durch Druckverlust und Unterkuehlung vergroesserte Temperaturaenderung im Verfluessiger. Vom LORENZ-Prozess ist bekannt, dass zusaetzliche Verluste auftreten, wenn die Temperaturaenderung des zeotropen Kaeltemittelgemisches groesser als die Temperaturspreizung des aeusseren Stoffstromes ist. Auch eine wesentliche Flaechenvergroesserung fuehrt dann nur zu geringen Verbesserungen. Die Anwendung des

  14. HFC宽带接入网上行带宽分配策略的改进%Improving the Upstream Bandwidth Allocation Policy for the HFC Broadband Access Networks

    Institute of Scientific and Technical Information of China (English)

    宋军; 甘育裕; 吴资玉

    2003-01-01

    The request/transmit based upstream bandwidth resource allocation policy of DOCSIS introduces a trouble to the quality of the data service provided in the I-IFC networks. In this paper, the mechanism of the upstream data transrmitting and the process of data service transmitting in the HFC networks are described in detail, and the perfor- mance of the data service in HFC networks is analyzed. An advanced upstream bandwidth resource allocation policy is proposed to improve the quality of the data service in the HFC networks.

  15. IMPEDANCE SPECTROSCOPY OF POLYCRYSTALLINE TIN DIOXIDE FILMS

    Directory of Open Access Journals (Sweden)

    D. V. Adamchuck

    2016-01-01

    Full Text Available The aim of this work is the analysis of the influence of annealing in an inert atmosphere on the electrical properties and structure of non-stoichiometric tin dioxide films by means of impedance spectroscopy method. Non-stoichiometric tin dioxide films were fabricated by two-step oxidation of metallic tin deposited on the polycrystalline Al2O3 substrates by DC magnetron sputtering. In order to modify the structure and stoichiometric composition, the films were subjected to the high temperature annealing in argon atmosphere in temperature range 300–800 °С. AC-conductivity measurements of the films in the frequency range 20 Hz – 2 MHz were carried out. Variation in the frequency dependencies of the real and imaginary parts of the impedance of tin dioxide films was found to occur as a result of high-temperature annealing. Equivalent circuits for describing the properties of films with various structure and stoichiometric composition were proposed. Possibility of conductivity variation of the polycrystalline tin dioxide films as a result of аnnealing in an inert atmosphere was demonstrated by utilizing impedance spectroscopy. Annealing induces the recrystallization of the films, changing in their stoichiometry as well as increase of the sizes of SnO2 crystallites. Variation of electrical conductivity and structure of tin dioxide films as a result of annealing in inert atmosphere was confirmed by X-ray diffraction analysis. Analysis of the impedance diagrams of tin dioxide films was found to be a powerful tool to study their electrical properties. 

  16. FC网络工程图纸的绘制%HFC Network Engineering Drawings of Drawing Method

    Institute of Scientific and Technical Information of China (English)

    先守东

    2012-01-01

    Engineering drawings in HFC network construction has the very important role. This article from the following several aspects of the engineering drawings of rendering techniques: How to get the reference map; The importance of field survey; The benefits of scale conversion; Drawing method and forms of engineering drawing.%工程图纸在HFC网络建设中具有很重要的作用,从以下几个方面阐述工程图纸的绘制技巧:如何获取用于工程图纸设计的参照图;实地调查的重要性;比例尺转换的好处;工程图纸的绘制方法及形式。

  17. Random test of R22 and HFC leakage in cooling installations; Steekproefonderzoek R22 en HFK lekkage koelinstallaties

    Energy Technology Data Exchange (ETDEWEB)

    Pennartz, F.; Van den Bovenkamp, M. [KWA Bedrijfsadviseurs, Amersfoort (Netherlands)

    2013-02-15

    KWA Business Consultants has conducted a random test survey in the dairy industry, meat industry and a peer group in other food sectors. The main goal was to obtain data on the size and trends of R22 and HFC emissions in the period 2007-2010. The survey is carried out by collecting the data of refilling refrigeration installations that have been registered by the refrigeration contractors. In total 1984 installations of 193 companies participated in the random test [Dutch] Begin 2012 is in opdracht van Agentschap NL onderzoek uitgevoerd naar lekkages van R22 en HFK koudemiddelen uit koelinstallaties in de sectoren zuivel, vlees en overige gerelateerde sectoren in de voedingsmiddelenindustrie. Het onderzoek had de vorm van een steekproef. Er hebben 193 bedrijven deelgenomen; 1984 koelinstallaties zijn onderzocht. Het gemiddelde lekpercentages is 7. De lekkages zijn afkomstig van 10 procent van de installaties uit de onderzoeksgroep.

  18. Parabolic starlike mappings of the unit ball $B^n$

    Directory of Open Access Journals (Sweden)

    Samira Rahrovi

    2016-02-01

    Full Text Available Let $f$ be a locally univalent function on the unit disk $U$. We consider the normalized extensions of $f$ to the Euclidean unit ball $B^nsubseteqmathbb{C}^n$ given by$$Phi_{n,gamma}(f(z=left(f(z_1,(f'(z_1^gammahat{z}right,$$ where $gammain[0,1/2]$, $z=(z_1,hat{z}in B^n$ and$$Psi_{n,beta}(f(z=left(f(z_1,(frac{f(z_1}{z_1}^betahat{z}right,$$in which $betain[0,1]$, $f(z_1neq 0$ and $z=(z_1,hat{z}inB^n$. In the case $gamma=1/2$, the function $Phi_{n,gamma}(f$ reduces to the well known Roper-Suffridge extension operator. By using different methods, we prove that if $f$ is parabolic starlike mapping on $U$ then $Phi_{n,gamma}(f$ and $Psi_{n,beta}(f$ are parabolic starlike mappings on $B^n$.

  19. Bandgap oscillation in quasiperiodic (BN)xCy nanotubes

    Science.gov (United States)

    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.

  20. Final Technical Report HFC Concrete: A Low­Energy, Carbon-Dioxide­Negative Solution for reducing Industrial Greenhouse Gas Emissions

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Larry McCandlish, Principal Investigator; Dr. Richard Riman, Co-Principal Investigator

    2012-05-14

    Solidia/CCSM received funding for further research and development of its Low Temperature Solidification Process (LTS), which is used to create hydrate-free concrete (HFC). LTS/HFC is a technology/materials platform that offers wide applicability in the built infrastructure. Most importantly, it provides a means of making concrete without Portland cement. Cement and concrete production is a major consumer of energy and source of industrial greenhouse gas (GHG) emissions. The primary goal of this project was to develop and commercialize a novel material, HFC, which by replacing traditional concrete and cement, reduces both energy use and GHG emissions in the built infrastructure. Traditional concrete uses Portland Cement (PC) as a binder. PC production involves calcination of limestone at {approx}1450 C, which releases significant amounts of CO{sub 2} gas to the atmosphere and consumes a large amount of energy due to the high temperature required. In contrast, HFC is a carbonate-based hydrate-free concrete (HFC) that consumes CO{sub 2} gas in its production. HFC is made by reaction of silicate minerals with CO{sub 2} at temperatures below 100 C, more than an order-of-magnitude below the temperature required to make PC. Because of this significant difference in temperature, it is estimated that we will be able to reduce energy use in the cement and concrete industry by up to 30 trillion Btu by 2020. Because of the insulating properties of HFC, we believe we will also be able to significantly reduce energy use in the Building sector, though the extent of this saving is not yet quantified. It is estimated that production of a tonne of PC-based concrete requires about 6.2 million Btu of energy and produces over 1 tonne of CO{sub 2} emissions (Choate, 2003). These can be reduced to 1.9 million Btu and 0.025 tonnes of CO{sub 2} emissions per tonne of HFC (with overall CO{sub 2}-negativity possible by increasing carbonation yield). In this way, by replacing PC

  1. Effect of the cBN content and sintering temperature on the transverse rupture strength and hardness of cBn/diamond cutting tools

    Directory of Open Access Journals (Sweden)

    Kır Durmuş

    2012-01-01

    Full Text Available The aim of this work was to investigate the effect of cBN content and sintering temperature on the transverse rupture strength (TRS of cBN/diamond cutting tools produced by hot pressing. The segments containing different cBN content were manufactured under 35 MPa pressure at 600, 650 and 700°C with a 3 minutes sintering time. The TRS of segments were determined using three-point bending test. Microstructure and phase composition of fracture surface of segments were determined by scanning electron microscopy (SEM, and X-ray diffraction (XRD analysis. The obtained results show that the TRS of the segments with cBN were higher than that of the segments with diamond.

  2. The dysprosium-tin phase diagram

    Energy Technology Data Exchange (ETDEWEB)

    Eremenko, V.N.; Bulanova, M.V.; Martsenjuk, P.S. (I.N. Frantsevich Inst. for Problems of Materials Science, Kiev (Ukraine))

    1992-12-07

    The dysprosium-tin phase diagram was established by means of differential thermal, X-ray and microscopic analyses of 22 alloys. Seven intermetallic compounds were found to exist in the system. Dy[sub 5]Sn[sub 3] melts congruently at 1870 degC, and undergoes a polymorphous transformation at 1823 [+-] 6 degC. The intermetallics Dy[sub 5]Sn[sub 4], Dy[sub 11]Sn[sub 10], DySn, Dy[sub 4]Sn[sub 5], DySn[sub 2], DySn[sub 3] are formed peritectically at 1712 [+-]11, 1605 [+-]12, 1208 [+-]3, 1166 [+-]7, 1138 [+-]3 and 747 [+-]6 degC respectively. DySn[sub 3] exists in a narrow temperature range, in two polymorphous modifications. The transformation [beta]-DySn[sub 3] [yields] [alpha]-DySn[sub 3] occurs at 608 [+-] 12 degC, and at 499 [+-]2 degC [alpha]-DySn[sub 3] decomposes to DySn[sub 2] and the tin-rich melt. The dysprosium-rich eutectic crystallizes at 1204 [+-]10 degC and contains 13 at.% tin. The solid-state solubility of tin in dysprosium is about 3 at.%, and that of dysprosium in tin is negligible.

  3. The BnALMT1 and BnALMT2 genes from rape encode aluminum-activated malate transporters that enhance the aluminum resistance of plant cells.

    Science.gov (United States)

    Ligaba, Ayalew; Katsuhara, Maki; Ryan, Peter R; Shibasaka, Mineo; Matsumoto, Hideaki

    2006-11-01

    The release of organic anions from roots can protect plants from aluminum (Al) toxicity and help them overcome phosphorus (P) deficiency. Our previous findings showed that Al treatment induced malate and citrate efflux from rape (Brassica napus) roots, and that P deficiency did not induce the efflux. Since this response is similar to the malate efflux from wheat (Triticum aestivum) that is controlled by the TaALMT1 gene, we investigated whether homologs of TaALMT1 are present in rape and whether they are involved in the release of organic anions. We isolated two TaALMT1 homologs from rape designated BnALMT1 and BnALMT2 (B. napus Al-activated malate transporter). The expression of these genes was induced in roots, but not shoots, by Al treatment but P deficiency had no effect. Several other cations (lanthanum, ytterbium, and erbium) also increased BnALMT1 and BnALMT2 expression in the roots. The function of the BnALMT1 and BnALMT2 proteins was investigated by heterologous expression in cultured tobacco (Nicotiana tabacum) cells and in Xenopus laevis oocytes. Both transfection systems showed an enhanced capacity for malate efflux but not citrate efflux, when exposed to Al. Smaller malate fluxes were also activated by ytterbium and erbium treatment. Transgenic tobacco cells grew significantly better than control cells following an 18 h treatment with Al, indicating that the expression of BnALMT1 and BnALMT2 increased the resistance of these plant cells to Al stress. This report demonstrates that homologs of the TaALMT1 gene from wheat perform similar functions in other species.

  4. Cubic and hexagonal boron-nitride (c-BN/h-BN) thin films deposited in situ by r.f. magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Caicedo, J.M.; Zambrano, G.; Baca, E.; Moran, O.; Prieto, P. [Departamento de Fisica, Universidad del Valle, A.A. 25360 Cali (Colombia); Bejarano, G. [Laboratorio de Recubrimientos Duros, CDT-ASTIN SENA, Cali (Colombia)

    2005-07-01

    Cubic boron-nitride (c-BN)/hexagonal boron nitride (h-BN) thin films were grown in situ on (100) oriented silicon substrates by r.f. (13.56 MHz) magnetron sputtering technique. In order to obtain the highest fraction of the c-BN phase, a negative d.c bias voltage, varying from 0 to -200 V was applied to the substrate during deposition. Another set of boron nitride thin films was deposited in situ on (100) oriented silicon substrates under r.f. bias voltage. The substrate holder was biased from 0 to -350 V by connecting such to an auxiliary r.f. generator (operated at 13.56 MHz). Films were characterized by Fourier Transformed Infrared Spectroscopy (FTIR) and Atomic Force Microscope (AFM). Well-defined peaks at 787 cm{sup -1}, 1100 cm{sup -1} and 1387 cm{sup -1}, corresponding to the 2{sub Au} (out-plane bending of B-N-B bond) h-BN vibration mode, the F2 (stretching) c-BN Transversal Optical (TO) mode and the E{sub 1u} (in-plane stretching of B-N bond) vibration mode of the h-BN, respectively, were observed in the FTIR spectra. A maximal fraction of the c-BN phase close to 85% was obtained under a bias voltage of -150 V at substrate temperature of 300 C and a total pressure of 4 x 10{sup -2} mbar. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. An Upper Bound of Essential Norm of Composition Operator on H2(Bn)

    Institute of Scientific and Technical Information of China (English)

    Zhihua CHEN; Liangying JIANG; Qiming YAN

    2012-01-01

    The authors give an upper bound of the essential norm of a composition operator on H2(Bn),which involves the counting function in the higher dimensional value distribution theory defined by S.S.Chern.A criterion is also given to assure that the composition operator on H2(Bn) is bounded or compact.

  6. BnWRI1 coordinates fatty acid biosynthesis and photosynthesis pathways during oil accumulation in rapeseed.

    Science.gov (United States)

    Wu, Xue-Long; Liu, Zhi-Hong; Hu, Zhang-Hua; Huang, Rui-Zhi

    2014-06-01

    Photosynthesis in "green" seeds, such as rapeseed, soybean, and Arabidopsis, plays a substantial role in the improved efficiency of oil accumulation. However, the molecular mechanism underpinning the coordinated expression of fatty acid (FA) biosynthesis- and photosynthesis-related genes in such developing seeds remains to be elucidated. Here, we found that seed-specific overexpression of BnWRI1, a WRI1 homolog from rapeseed (Brassica napus cv. ZGY2), results in enhanced chlorophyll content in developing seeds and increased oil content and seed mass in matured seeds. BnWRI1 was co-expressed with BnBCCP and BnCAB, two marker genes of FA biosynthesis and photosynthesis during seed development, respectively. Overexpression of BnWRI1 increased expression of both marker genes. Further, the nuclear-localized BnWRI1 protein was found to act as a transcription activator. It could bind to the GT1-element and/or GCC-box, which are widespread in the upstream regions of genes involved in FA biosynthesis and photosynthesis pathways. Accordingly, BnWRI1 could interact with promoters of BCCP2 and LHB1B2 in vivo. These results suggested that BnWRI1 may coordinate FA biosynthesis and photosynthesis pathways in developing seeds via directly stimulating expression of GT1-element and/or GCC-box containing genes.

  7. van der Waals Bonded Co/h-BN Contacts to Ultrathin Black Phosphorus Devices.

    Science.gov (United States)

    Avsar, Ahmet; Tan, Jun Y; Luo, Xin; Khoo, Khoong Hong; Yeo, Yuting; Watanabe, Kenji; Taniguchi, Takashi; Quek, Su Ying; Özyilmaz, Barbaros

    2017-09-13

    Because of the chemical inertness of two dimensional (2D) hexagonal-boron nitride (h-BN), few atomic-layer h-BN is often used to encapsulate air-sensitive 2D crystals such as black phosphorus (BP). However, the effects of h-BN on Schottky barrier height, doping, and contact resistance are not well-known. Here, we investigate these effects by fabricating h-BN encapsulated BP transistors with cobalt (Co) contacts. In sharp contrast to directly Co contacted p-type BP devices, we observe strong n-type conduction upon insertion of the h-BN at the Co/BP interface. First-principles calculations show that this difference arises from the much larger interface dipole at the Co/h-BN interface compared to the Co/BP interface, which reduces the work function of the Co/h-BN contact. The Co/h-BN contacts exhibit low contact resistances (∼4.5 kΩ) and are Schottky barrier-free. This allows us to probe high electron mobilities (4,200 cm(2)/(V s)) and observe insulator-metal transitions even under two-terminal measurement geometry.

  8. BnWRI1 coordinates fatty acid biosynthesis and photosynthesis pathways during oil accumulation in rapeseed

    Institute of Scientific and Technical Information of China (English)

    Xue-Long Wu; Zhi-Hong Liu; Zhang-Hua Hu; Rui-Zhi Huang

    2014-01-01

    Photosynthesis in“green”seeds, such as rapeseed, soybean, and Arabidopsis, plays a substantial role in the improved efficiency of oil accumulation. However, the molecular mecha-nism underpinning the coordinated expression of fatty acid (FA) biosynthesis-and photosynthesis-related genes in such develop-ing seeds remains to be elucidated. Here, we found that seed-specific overexpression of BnWRI1, a WRI1 homolog from rapeseed (Brassica napus cv. ZGY2), results in enhanced chlorophyl content in developing seeds and increased oil content and seed mass in matured seeds. BnWRI1 was co-expressed with BnBCCP and BnCAB, two marker genes of FA biosynthesis and photosynthesis during seed development, respectively. Over-expression of BnWRI1 increased expression of both marker genes. Further, the nuclear-localized BnWRI1 protein was found to act as a transcription activator. It could bind to the GT1-element and/or GCC-box, which are widespread in the upstream regions of genes involved in FA biosynthesis and photosynthesis pathways. Accordingly, BnWRI1 could interact with promoters of BCCP2 and LHB1B2 in vivo. These results suggested that BnWRI1 may coordinate FA biosynthesis and photosynthesis pathways in developing seeds via directly stimulating expression of GT1-element and/or GCC-box containing genes.

  9. Microstructure and mechanical properties of SiO2-BN ceramic and Invar alloy joints brazed with Ag–Cu–Ti+TiH2+BN composite filler

    Directory of Open Access Journals (Sweden)

    Y. Wang

    2016-03-01

    Full Text Available Ag–Cu–Ti + TiH2+BN composite filler was prepared to braze SiO2-BN ceramic and Invar alloy. The interfacial microstructure, mechanical properties, and residual stress distribution of the brazed joints were investigated. The results show that a wave-like Fe2Ti–Ni3Ti structure appears in the Invar substrate and a thin TiN–TiB2 reaction layer forms adjacent to the SiO2-BN ceramic. The added BN particles react with Ti to form TiN–TiB fine-particles, which is beneficial to refine the microstructure of the brazing seam and to greatly inhibit the brittle compounds formation. The interfacial microstructure at various brazing temperatures was analyzed, and the mechanism for the interfacial reactions responsible for the bonding was proposed. The maximum shear strength of the joints brazed with the composite filler at 880 °C for 10 min is 39 MPa, which is 30% greater than that brazed with Ag–Cu–Ti alloy. The improvement of the joint strength is attributed to the variation of joint microstructure and the reduction of tensile stresses induced in the SiO2-BN ceramic. The finite element analysis indicates that the peak tensile stress decreases from 230 to 142 MPa due to the addition of BN particles in the ceramic.

  10. Mechanical properties and electronic structures of one BN nanotube under radial compression

    Institute of Scientific and Technical Information of China (English)

    Hai-jun SHEN

    2009-01-01

    The Tersoff-potential based MD (molecular dynamics)method was used to simulate the radial compression of one(10,0)BN nanotube,and its compressive pmpertes was compared with those of one (10,0)carbon nanotube The semi-empirical PM3 QC (Quantum chemistry)method was adopted to calculate the electronic structures of the compressed BN-tube,and the effect of the radial compression on the electronic structures of the BN-tube was discussed. It is shown that(I) BN-tube has comparable radial compressive stiffness to carbon-tube,but lower energy-absorbing,load-support and deformation-support capabilities,and (ii) with the increase of compressive strain,the HOMO energy of the BN-tube lncreases the LUMO energy and the LUMO-HOMOenergy-gap decrease,and its chemical activity and conductance increase.

  11. Decomposition of BN and formation of Nd2Fe14BNx phase prepared by mechanical alloying

    Science.gov (United States)

    Liu, W.; Zhang, Z. D.; Sun, X. K.; He, J. F.; Zhao, X. G.

    1999-07-01

    The decomposition of pyrolytic boron nitride (p-BN) during milling is studied as a function of the milling time. It has been found that the p-BN compound can be partially decomposed by milling until an amorphous p-BN phase is formed so that the content of nitrogen in the p-BN system will not continue to be changed by the milling process. Furthermore, the structure and magnetic properties of Nd2Fe14BNx-based alloys prepared by mechanical alloying using either p-BN or milled p-BN as starting material have been investigated. The Nd2Fe14BNx phase with x up to 0.25 coexists with some amounts of NdN, the Nd-rich phase and icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/>-Fe. A pre-milling process of p-BN favours the formation of the Nd2Fe14BNx phase. The magnetic properties of Nd16Fe76B8Nx alloys prepared by using milled p-BN are better than those made of non-milled p-BN. The Curie temperature of the Nd2Fe14BN0.25 phase is 335 °C, which is slightly higher than that of the Nd2Fe14B compound. A coercivity higher than 20 kOe is achieved for Nd2Fe14BNx-based alloys by adding excess Nd, which is close to the value of Nd16Fe76B8 prepared by using pure B.

  12. Electron beam induced growth of tin whiskers

    Energy Technology Data Exchange (ETDEWEB)

    Vasko, A. C.; Karpov, V. G. [Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States); Warrell, G. R.; Parsai, E. I.; Shvydka, Diana, E-mail: diana.shvydka@utoledo.edu [Department of Radiation Oncology, University of Toledo Health Science Campus, Toledo, Ohio 43614 (United States)

    2015-09-28

    We have investigated the influence of electron irradiation on tin whisker growth. Sputtered tin samples exposed to electron beam of 6 MeV energy exhibited fast whisker growth, while control samples did not grow any whiskers. The statistics of e-beam induced whiskers was found to follow the log-normal distribution. The observed accelerated whisker growth is attributed to electrostatic effects due to charges trapped in an insulating substrate. These results offer promise for establishing whisker-related accelerated life testing protocols.

  13. Moessbauer spectra of tin in float glass

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J.A. [Liverpool John Moores Univ. (United Kingdom). Sch. of the Built Environ.; Johnson, C.E. [Liverpool Univ. (United Kingdom). Dept. of Physics; Williams, K.F.E. [Liverpool Univ. (United Kingdom). Dept. of Physics; Holland, D. [Warwick Univ., Coventry (United Kingdom). Dept. of Physics; Karim, M.M. [Warwick Univ., Coventry (United Kingdom). Dept. of Physics

    1995-03-01

    Tin is not a major constituent of window glass, but is found at high concentrations in the lower surface of float glass which has been in contact with the molten tin bath. It does not extend far into the surface, but causes the physical and chemical behaviour to differ from that of the upper surface. It is important, therefore, to understand the structural role of tin in silicate glasses and thus its effect on various properties. Moessbauer spectra were taken of three series of glassy materials, namely binary glasses (SnO and SiO{sub 2}) in varying proportions, re-melted float glass containing tin, and float glass from a production plant. The binary glasses contained between 20 and 70% tin which was found to be mainly Sn{sup 2+}, with very small amounts of Sn{sup 4+} in some of them. The spectra showed a small decrease in isomer shift with increase in tine content, which is ascribed to the change in molar volume. The re-melted samples were float glass which was mixed with stannous oxalate in appropriate conditions to try and maintain tin in the 2+ state, and contained up to 15% tin by weight. The spectra show both Sn{sup 4+} and Sn{sup 2+} with rather more in the 4+ oxidation state. The change in the spectra as a function of temperature revealed a large difference in the f-factor (and hence the chemical binding) of the two states. A series of spectra was taken between 17.5 and 900 K for the sample containing 15% tin. From the absorption as a function of temperature the f-factor was determined for both oxidation states, and hence enabled the relative amounts of Sn{sup 4+} and Sn{sup 2+} present in each sample to be estimated. Measurements of the shift as a function of temperature were also made. The float samples were surface material produced by grinding away all but 0.1 mm of the lower surface of industrially produced float glass. The Moessbauer spectra showed them to be predominantly Sn{sup 2+}, as expected from the reducing atmosphere in the float plant.

  14. High-Pressure Design of Advanced BN-Based Materials

    Directory of Open Access Journals (Sweden)

    Oleksandr O. Kurakevych

    2016-10-01

    Full Text Available 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 B13N2. 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.

  15. Naphthalene degradation and biosurfactant activity by Bacillus cereus 28BN

    Energy Technology Data Exchange (ETDEWEB)

    Tuleva, B.; Christova, N. [Inst. of Microbiology, Bulgarian Academy of Sciences, Sofia (Bulgaria); Jordanov, B.; Nikolova-Damyanova, B. [Inst. of Organic Chemistry, Sofia (Bulgaria); Petrov, P. [National Center of Infectious and Parasitic Diseases, Sofia (Bulgaria)

    2005-08-01

    Biosurfactant activity and naphthalene degradation by a new strain identified as Bacillus cereus 28BN were studied. The strain grew well and produced effective biosurfactants in the presence of n-alkanes, naphthalene, crude oil and vegetable oils. The biosurfactants were detected by the surface tension lowering of the medium, thin layer chromatography and infrared spectra analysis. With (2%) naphthalene as the sole carbon source, high levels of rhamnolipids at a concentration of 2.3 g l{sup -1} were determined in the stationary growth. After 20 d of incubation 72 {+-} 4% of the initial naphthalene was degraded. This is the first report for a Bacillus cereus rhamnolipid producing strain that utilized naphthalene under aerobic conditions. The strain looks promising for application in environmental technologies. (orig.)

  16. High-Pressure Design of Advanced BN-Based Materials.

    Science.gov (United States)

    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 B13N₂. 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.

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

    Science.gov (United States)

    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.

  18. Effects of electron beam irradiation on tin dioxide gas sensors

    Indian Academy of Sciences (India)

    Zheng Jiao; Xiaojuan Wan; Bing Zhao; Huijiao Guo; Tiebing Liu; Minghong Wu

    2008-02-01

    In this paper, the effects of electron beam irradiation on the gas sensing performance of tin dioxide thin films toward H2 are studied. The tin dioxide thin films were prepared by ultrasonic spray pyrolysis. The results show that the sensitivity increased after electron beam irradiation. The electron beam irradiation effects on tin dioxide thin films were simulated and the mechanism was discussed.

  19. EVALUASI PENGELOLAAN REFRIGERAN CFC, DAN HFC DENGAN MESIN 3R DAN UJI UNJUK KERJA MESIN PENDINGIN STUDI KASUS PADA BENGKEL AC MOBIL DI DENPASAR - BALI

    OpenAIRE

    I MADE RASTA; I.W. Kasa; I Gede Mahardika

    2015-01-01

    CFC refrigerant has been known to be one of causes of ozone layer diminishing and HFC is one of green house gases contributing to global warming through the leak and synthetic refrigerant waste to environment. As a response to the ozone layer diminishment on stratosphere, UNEP, in 1981, through a negotiating process of international stages of development reserve the ozone layer through Wina Convention legalized in March 1985. It was then followed up with Montreal Protocol in September 1987 co...

  20. (Vapour + liquid) equilibria of the {l_brace}1,1,1-trifluoroethane (HFC-143a) + isobutene{r_brace} system

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Yongju; Im, Jihoon [School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Kim, Hwayong [School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of)], E-mail: hwayongk@snu.ac.kr

    2008-05-15

    Isothermal (vapour + liquid) equilibrium data were measured for the {l_brace}1,1,1-trifluoroethane (HFC-143a) + isobutene{r_brace} as an alternative refrigerant in the temperature range from (273.15 to 348.15) K at 15 K intervals. A circulating-type apparatus with on-line gas chromatography was used in these experiments. The experimental data were correlated well by Peng-Robinson equation of state using the Wong-Sandler mixing rules.

  1. Investigations on structural, elastic, thermodynamic and electronic properties of TiN, Ti2N and Ti3N2 under high pressure by first-principles

    Science.gov (United States)

    Yang, Ruike; Zhu, Chuanshuai; Wei, Qun; Du, Zheng

    2016-11-01

    The lattice parameters, cell volume, elastic constants, bulk modulus, shear modulus, Young's modulus and Poisson's ratio are calculated at zero pressure, and their values are in excellent agreement with the available data, for TiN, Ti2N and Ti3N2. By using the elastic stability criteria, it is shown that the three structures are all stable. The brittle/ductile behaviors are assessed in the pressures from 0 GPa to 50 GPa. Our calculations present that the performances for TiN, Ti2N and Ti3N2 become from brittle to ductile with pressure rise. The Debye temperature rises as pressure increase. With increasing N content, the enhancement of covalent interactions and decline of metallicity lead to the increase of the micro-hardness. Their constant volume heat capacities increase rapidly in the lower temperature, at a given pressure. At higher temperature, the heat capacities are close to the Dulong-Petit limit, and the heat capacities of TiN and Ti2N are larger than that of c-BN. The thermal expansion coefficients of titanium nitrides are slightly larger than that of c-BN. The band structure and the total Density of States (DOS) are calculated at 0 GPa and 50 GPa. The results show that TiN and Ti2N present metallic character. Ti3N2 present semiconducting character. The band structures have some discrepancies between 0 GPa and 50 GPa. The extent of energy dispersion increases slightly at 50 GPa, which means that the itinerant character of electrons becomes stronger at 50 GPa. The main bonding peaks of TiN, Ti2N and Ti3N2 locate in the range from -10 to 10 eV, which originate from the contribution of valance electron numbers of Ti s, Ti p, Ti d, N s and N p orbits. We can also find that the pressure makes that the total DOS decrease at the Fermi level for Ti2N. The bonding behavior of N-Ti compounds is a combination of covalent and ionic nature. As N content increases, valence band broadens, valence electron concentration increases, and covalent interactions become stronger

  2. Synthesising highly reactive tin oxide using Tin(II2- ethylhexanoate polynucleation as precursor

    Directory of Open Access Journals (Sweden)

    Alejandra Montenegro Hernández

    2010-05-01

    Full Text Available Tin oxide is a widely used compound in technological applications, particularity as a catalyst, gas sensor and in making varistors, transparent conductors, electrocatalytic electrodes and photovoltaic cells. An ethylhexanoate tin salt, a carboxylic acid and poly-esterification were used for synthesising highly reactive tin oxide in the present study. Synthesis was controlled by Fourier transform infrared (FTIR spectroscopy and recording changes in viscosity. The tin oxide characteristics so obtained were determined using FTIR spectroscopy, X-ray diffraction (XRD and scanning electron microscopy (SEM. The SnO2 dust synthesised and heat-treated at 550°C yielded high density aggregates, having greater than 50 μm particle size. This result demonstrates the high reactivity of the ceramic powders synthesised here.

  3. 钛沉积工艺制备TiN/cBN和TiC/金钢石涂层颗粒%Fabrication of TiN/cBN and TiC/diamond coated particles by titanium deposition process

    Institute of Scientific and Technical Information of China (English)

    Walid M. DAOUSH; Hee S. PARK; Soon H. HONG

    2014-01-01

    Cubic boron nitride particles coated by titanium nitride (TiN/cBN) as well as diamond particles coated by titanium carbide (TiC/diamond) were prepared by Ti molten salt deposition followed by heat-treatment process. cBN or diamond particles were mixed separately with Ti powders and molten salts (KCl, NaCl and K2TiF6). The mixture was heated at 900 °C under argon atmosphere. The produced particles were heat-treated under hydrogen at 1000 °C. The morphologies and chemical compositions of the produced particles were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and focused ion beam (FIB). The results show that the cBN and the diamond particles are coated by nano-sized Ti layers. By heat-treatment of the Ti/cBN and TiC/diamond coated particles under hydrogen atmosphere, the deposited Ti layers were interacted by the in-situ transformation reaction with the surfaces of cBN and diamond particles and converted to titanium compounds (TiN and TiC), respectively.%用钛熔盐沉积及热处理工艺分别制备碳化钛涂覆的立方碳化硼颗粒(TiN/cBN)及碳化钛涂覆的金刚石颗粒(TiC/金刚石)。将cBN或金刚石颗粒分别与钛粉和KCl、NaCl和K2TiF6熔盐混合。将所得混合物在Ar气氛中加热至900°C,然后在H2气氛中于1000°C进行热处理。采用扫描电镜、X射线衍射和聚焦离子束技术对所制得颗粒进行表征。结果表明:cBN和金刚石颗粒表面已覆盖了纳米钛层。对Ti/cBN和TiC/金刚石涂层颗粒进行热处理后,颗粒表面沉积的Ti层与cBN和金刚石颗粒发生了原位化学反应,分别转化为钛化合物TiN和TiC。

  4. Hydrolysis of bis(dimethylamido)tin to tin (II) oxyhydroxide and its selective transformation into tin (II) or tin (IV) oxide

    KAUST Repository

    Khanderi, Jayaprakash

    2015-03-01

    Sn6O4(OH)4, a hydrolysis product of Sn(NMe2)2, is transformed to tin (II) or tin (IV) oxide by solid and solution phase processing. Tin (II) oxide is formed by heating Sn6O4(OH)4 at ≤200 °C in air or under inert atmosphere. Tin (IV) oxide nanoparticles are formed in the presence of a carboxylic acid and base in air at room temperature. IR spectroscopy, Raman spectroscopy, thermogravimetry (coupled with infrared spectroscopy), powder X-ray diffraction, high temperature X-ray diffraction, scanning electron and transmission electron microscopy are used for the characterization of Sn6O4(OH)4 and the investigation of its selective decomposition into SnO or SnO2. Spectroscopic and X-ray diffraction results indicate that SnO is formed by the removal of water from crystalline Sn6O4(OH)4. SEM shows octahedral morphology of the Sn6O4(OH)4, SnO and SnO2 with particle size from 400 nm-2 μm during solid state conversion. Solution phase transformation of Sn6O4(OH)4 to SnO2 occurs in the presence of potassium glutarate and oxygen. SnO2 particles are 15-20 nm in size.

  5. Optoelectronic properties of higher acenes, their BN analogue and substituted derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Armaković, Stevan, E-mail: stevan.armakovic@df.uns.ac.rs [University of Novi Sad, Faculty of Sciences, Department of Physics, Trg Dositeja Obradovića 4, 21000, Novi Sad (Serbia); Armaković, Sanja J. [University of Novi Sad, Faculty of Sciences, Department of Chemistry, Biochemistry and Environmental Protection, Trg Dositeja Obradovića 3, 21000, Novi Sad (Serbia); Holodkov, Vladimir [Educons University, Faculty of Sport and Tourism - TIMS, Radnička 30a, 21000, Novi Sad (Serbia); Pelemiš, Svetlana [University of East Sarajevo, Faculty of Technology, Karakaj bb, 75400, Zvornik, Republic of Srpska, Bosnia and Herzegovina (Bosnia and Herzegovina)

    2016-02-15

    We have investigated optoelectronic properties of higher acenes: pentacene, hexacene, heptacene, octacene, nonacene, decacene and their boron-nitride (BN) analogues, within the framework of density functional theory (DFT). We have also investigated the optoelectronic properties of acenes modified by BN substitution. Calculated optoelectronic properties encompasses: oxidation and reduction potentials, electron and hole reorganization energies and energy difference between excited first singlet and triplet states ΔE(S{sub 1}−T{sub 1}). Oxidation and reduction potentials indicate significantly better stability of BN analogues, comparing with their all-carbon relatives. Although higher acenes possess lower electron and hole reorganization energies, with both best values much lower than 0.1 eV, their BN analogues also have competitive values of reorganization energies, especially for holes for which reorganization energy is also lower than 0.1 eV. On the other hand ΔE(S{sub 1}−T{sub 1}) is much better for BN analogues, having values that indicate that BN analogues are possible applicable for thermally activated delayed fluorescence. - Highlights: • Optoelectronic properties of structures based on higher acenes have been investigated. • Oxidation and reduction potentials together with reorganization energies are calculated. • TADF is analyzed through calculation of ΔE(S{sub 1}−T{sub 1}), which is much better for BN analogues. • Reorganization energies of acenes improve with the increase of number of benzene rings.

  6. Low frequency Raman spectroscopy of few-atomic-layer thick hBN crystals

    Science.gov (United States)

    Stenger, I.; Schué, L.; Boukhicha, M.; Berini, B.; Plaçais, B.; Loiseau, A.; Barjon, J.

    2017-09-01

    Hexagonal boron nitride (hBN) has recently gained a strong interest as a strategic component in engineering van der Waals heterostructures built with 2D crystals such as graphene. This work reports micro-Raman measurements on hBN flakes made of a few atomic layers, prepared by mechanical exfoliation. The temperature dependence of the Raman scattering in hBN is investigated first such as to define appropriate measurements conditions suitable for thin layers avoiding undesirable heating induced effects. We further focus on the low frequency Raman mode corresponding to the rigid shearing oscillation between adjacent layers, found to be equal to 52.5 cm-1 in bulk hBN. For hBN sheets with thicknesses below typically 4 nm, the frequency of this mode presents discrete values, which are found to decrease down to 46.0(5) cm-1 for a three-layer hBN, in good agreement with the linear-chain model. This makes Raman spectroscopy a relevant tool to quantitatively determine in a non destructive way the number of layers in ultra thin hBN sheets, below 8 L, prior to their integration in van der Waals heterostructures.

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

    Science.gov (United States)

    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.

  8. Graphene on h-BN: to align or not to align?

    Science.gov (United States)

    Guerra, Roberto; van Wijk, Merel; Vanossi, Andrea; Fasolino, Annalisa; Tosatti, Erio

    2017-06-29

    The contact strength, adhesion and friction, between graphene and an incommensurate crystalline substrate such as h-BN depends on their relative alignment angle θ. The well-established Novaco-McTague (NM) theory predicts for a monolayer graphene on a hard bulk h-BN crystal face a small spontaneous misalignment, here θNM ≃ 0.45 degrees which if realized would be relevant to a host of electronic properties besides the mechanical ones. Because experimental equilibrium is hard to achieve, we inquire theoretically about alignment or misalignment by simulations based on dependable state-of-the-art interatomic force fields. Surprisingly at first, we find compelling evidence for θ = 0, i.e., full energy-driven alignment in the equilibrium state of graphene on h-BN. Two factors drive this deviation from the NM theory. First, graphene is not flat, developing on h-BN a long-wavelength out-of-plane corrugation. Second, h-BN is not hard, releasing its contact stress by planar contractions/expansions that accompany the interface moiré structure. Repeated simulations by artificially forcing graphene to keep flat, and h-BN to keep rigid, indeed yield an equilibrium misalignment similar to θNM as expected. Subsequent sliding simulations show that friction of graphene on h-BN, small and essentially independent of misalignments in the artificial frozen state, strongly increases in the more realistic corrugated, strain-modulated, aligned state.

  9. P-BN/n-Si Heterojunction Prepared by Beryllium ion Implantation

    Institute of Scientific and Technical Information of China (English)

    HE Bin; CHEN Guang-Hua; LI Zhi-Zhong; DENG Jin-Xiang; ZHANG Wun-Jun

    2008-01-01

    A boron nitride(BN)/silicon p-n heterojunction is fabricated by implanting beryllium (Be) ions into the BN films deposited by rf sputtering on n-type Si(111)substrates.The FTIR observations indicate that the films deposited have a mixed phase composition of sp2-and sp3-hybridized BN.Considering the thickness of the BN layer.the ion implantation is conducted at an ion energy of 100ke V with the dose of 5×1015cm-2.After annealing at a high temperature,the surface resistance of the BN film decreases significantly by 6 orders down to 1.2×105Ω.Space-charge-limited current characteristic.which indicates the existence of shallow traps in the film,is observed.Current-voltage measurements across the BN film and the Si substrate reveal a clear rectification feature,demonstrating the achievement of p-type doping of BN films by Be ion implantation.

  10. Osbornite (TiN) and boron nitride nanoinclusions in coesite from Tibet: a first record of nitrogen in a terrestrial ultrahigh pressure environment

    Science.gov (United States)

    Dobrzhinetskaya, L.; Wirth, R.; Yang, J.; Hutcheon, I.; Weber, P.; Green, H. W.

    2007-12-01

    We report here discovery of nitrides in podiform chromitite of the Luobusa ophiolite, Tibet, representing the mantle section of a ¡°fossil¡± fragment of oceanic crust which marks the Early Tertiary (~65Ma) suture zone between Asia and India. Nanometric crystals of TiN and BN are included in coesite which, together with kyanite, TiO2-II and several other still unidentified phases rim a FeTi-alloy pellet; this sample, together with an OsIr alloy pellet containing microdiamond were extracted from the massive chromitite (Yang et al., Geology, 2007). Both TiN and BN form bright-grey-contrast particles in secondary-electron scanning electron microscope imaging. Several focused ion beam foils were prepared for a transmission electron microscope (TEM) and a nano secondary ion mass spectrometry (nanoSIMS) studies. Because energy dispersive X-ray spectra (EDS) of boron and nitrogen K-lines have overlaps with each other and with Ti L-lines, we have used electron energy loss spectroscopy (EELS) in TEM to determine the presence of boron and nitrogen K-edges and to separate them from Ti L-lines. Electron diffraction patterns identify the cubic boron nitride (c-BN) structure. TiN is stoichiometric (Ti=77.20wt%; N=22.80wt%) and is also cubic. Both phases contain trace carbon. Osbornite, is usually found only in meteorites, although it also has been reported as inclusions in carbonado diamonds and as inclusion in a corundum grain from lamproitic breccia in the Asov block, Eastern-European platform, Ukraine. Until now, boron nitride was known only as an industrial compound, with both hexagonal and cubic structures. With the nanoSIMS Cameca-50 using the Cs beam we have measured nitrogen and carbon isotopes in both the TiN and c-BN inclusions: δ 15N= +(6-10) ‰ and δ 13C= (+1) ¨C (-10) ‰. The results show that both minerals are characterized by δ 15N similar to crustal rocks involved in the subduction process and their δ 13C values suggest mixture of heavy (mantle) and

  11. Development of (Ti, Al)N coated cBN tool for ADI machining; ADI zai kakoyo (Ti, Al) N coated cBN kogu no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Shintani, K.; Sugiyama, H.; Kato, H. [Kanazawa Institute of Technology, Ishikawa (Japan); Goto, M. [Sumitomo Electric Industries, Ltd., Osaka (Japan)

    1998-06-25

    Concerning cBN tools used for machining austempered ductile cast iron (ADI), the effects of difference in the strength of cBN particles themselves on tool life and the tool life extending effects of a (Ti, Al)N coating formed on the tool surface are discussed. In the experiment, three kinds of tool materials, which are C60-F, C60-M, and C60-T, are prepared, which contain 60vol% cBN particles different in strength. The flank abrasion inhibiting effect of the coating is also studied. In this study, C60c and C20c tools are tested, built of parent materials containing 20% 1{mu}m T particles and 60% 3{mu}m T particles and coated by (Ti, Al)N. Some of the conclusions reached are outlined below. The strength of cBN particles present in the specimens exerts virtually no influence on the improvement of flank abrasion characteristics. In a tool provided with a (Ti, Al)N coating, some of the (Ti, Al)N coating is retained between the cutting face near the cutting edge and the flank lower edge, and this suppresses the progress of flank abrasion. A tool provided with a (Ti, Al)N coating has a life which is more than three times the life of uncoated cBN tools. 9 refs., 12 figs., 2 tabs.

  12. Characterization methods dedicated to nanometer-thick hBN layers

    Science.gov (United States)

    Schué, Léonard; Stenger, Ingrid; Fossard, Frédéric; Loiseau, Annick; Barjon, Julien

    2017-03-01

    Hexagonal boron nitride (hBN) has regained interest as a strategic component in graphene engineering and in van der Waals heterostructures built with two dimensional materials. It is crucial then, to handle reliable characterization techniques capable to assess the quality of structural and electronic properties of the hBN material used. We present here characterization procedures based on optical spectroscopies, namely cathodoluminescence and Raman, with the additional support of structural analysis conducted by transmission electron microscopy. We show the capability of optical spectroscopies to investigate and benchmark the optical and structural properties of various hBN thin layers sources.

  13. Sensitivity of BN nano-cages to caffeine and nicotine molecules

    Science.gov (United States)

    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.

  14. Basic research on mechanism of BN inclusion in improving the machinability of steel

    Directory of Open Access Journals (Sweden)

    Ya-nan, Chen

    2014-12-01

    Full Text Available Boron nitride-added eco-friendly free cutting steel has recently drawn more and more attention. But, the mechanisms explaining the role of BN inclusions improving the machinability of steels is not very clear. In this investigation, the material removal mechanism for cutting of BN inclusions in steels is explored, using a combination of theoretical analysis and a series of experiments. First, the actual shape of BN inclusions is observed and the amount and distribution of BN inclusions is quantitatively analyzed. Subsequently, the cutting performance of the steel is determined by cutting experimental tests. Moreover, the micro mechanical properties and the material removal mechanisms for cutting of BN inclusions are investigated by means of nanoindentation. The results revealed that the BN inclusions are hexagonal and are uniformly distributed, their average content is 23.2 per unit area and their volume fraction is 0.51% in the steel with 74 ppm B and 180 ppm N. It is shown that BN inclusions can improve the cutting performance of steel significantly, and a model describing the material removal mechanism for cutting of BN inclusions is proposed. BN inclusions act as stress concentration source, lubrication and wrappage of hard particles.Los aceros de fácil mecanizado o corte libre con nitruro de boro agregado han despertado un gran interés. Sin embargo, aún no se han determinado los mecanismos que explican el papel de las inclusiones de BN en la mejora de la maquinabilidad de estos aceros. En este trabajo, se investigan los mecanismos de corte de las inclusiones BN en aceros mediante la combinación de un análisis teórico y una serie de experimentos. En primer lugar, se determina la morfología de las inclusiones BN y se analiza cuantitativamente la cantidad y distribución de las mismas. Posteriormente, el rendimiento de corte del acero se determina mediante ensayos de corte. Por otra parte, las propiedades mecánicas locales y los

  15. Growth of YBCO Thin Films on TiN(001) and CeO2-Coated TiN Surfaces

    Science.gov (United States)

    2012-02-01

    AFRL-RZ-WP-TP-2012-0102 GROWTH OF YBCO THIN FILMS ON TiN(001) AND CeO2-COATED TiN SURFACES (POSTPRINT) Paul N. Barnes, Rand Biggers...GROWTH OF YBCO THIN FILMS ON TiN(001) AND CeO2-COATED TiN SURFACES (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM...Number: ASC-01-1691; Clearance Date: 19 Nov 2002. This paper contains color 14. ABSTRACT Epitaxial growth of YBa2Cu3O7-x ( YBCO ) layers on TiN(0 0

  16. Global and regional emissions estimates of 1,1-difluoroethane (HFC-152a, CH3CHF2 from in situ and air archive observations

    Directory of Open Access Journals (Sweden)

    P. G. Simmonds

    2016-01-01

    Full Text Available High frequency, in situ observations from 11 globally distributed sites for the period 1994–2014 and archived air measurements dating from 1978 onward have been used to determine the global growth rate of 1,1-difluoroethane (HFC-152a, CH3CHF2. These observations have been combined with a range of atmospheric transport models to derive global emission estimates in a top-down approach. HFC-152a is a greenhouse gas with a short atmospheric lifetime of about 1.5 years. Since it does not contain chlorine or bromine, HFC-152a makes no direct contribution to the destruction of stratospheric ozone and is therefore used as a substitute for the ozone depleting chlorofluorocarbons (CFCs and hydrochlorofluorocarbons (HCFCs. The concentration of HFC-152a has grown substantially since the first direct measurements in 1994, reaching a maximum annual global growth rate of 0.84 ± 0.05 ppt yr−1 in 2006, implying a substantial increase in emissions up to 2006. However, since 2007, the annual rate of growth has slowed to 0.38 ± 0.04 ppt yr−1 in 2010 with a further decline to an annual average rate of growth in 2013–2014 of −0.06 ± 0.05 ppt yr−1. The annual average Northern Hemisphere (NH mole fraction in 1994 was 1.2 ppt rising to an annual average mole fraction of 10.1 ppt in 2014. Average annual mole fractions in the Southern Hemisphere (SH in 1998 and 2014 were 0.84 and 4.5 ppt, respectively. We estimate global emissions of HFC-152a have risen from 7.3 ± 5.6 Gg yr−1 in 1994 to a maximum of 54.4 ± 17.1 Gg yr−1 in 2011, declining to 52.5 ± 20.1 Gg yr−1 in 2014 or 7.2 ± 2.8 Tg-CO2 eq yr−1. Analysis of mole fraction enhancements above regional background atmospheric levels suggests substantial emissions from North America, Asia, and Europe. Global HFC emissions (so called “bottom up” emissions reported by the United Nations Framework Convention on Climate Change (UNFCCC

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

    Directory of Open Access Journals (Sweden)

    Quan Chen

    2015-07-01

    Full Text Available 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.

  18. Density functional theory study of BnC clusters.

    Science.gov (United States)

    Liu, Chunhui; Han, Peilin; Tang, Mingsheng

    2011-05-15

    B(n)C clusters (n = 3-10) were studied at the density functional theory (DFT) (B3LYP)/6-311G** level of theory. The calculations predicted that the most stable configurations of the B(n) C clusters are the (n + 1)-membered cyclic structures. For boron-carbon clusters, the configurations containing greater numbers of three-membered boron rings are more favorable, except for the B(7)C and B(9)C clusters. Through molecular orbital analysis of these B(n)C clusters, we have concluded that π-electron delocalization plays a crucial role in the stability of n + 1-membered cyclic structures. In this paper, the relative stability of each cluster is discussed based on their single atomic-binding energies. The capability of clusters to obtain or lose an electron was also discussed, based on their vertical electron detachment energies (VDEs), adiabatic electron detachment energies (ADEs), vertical electron affinities (VEAs) and adiabatic electron affinities (AEAs). Copyright © 2011 John Wiley & Sons, Ltd.

  19. Sepsis Patient Detection and Monitor Based on Auto-BN.

    Science.gov (United States)

    Jiang, Yu; Sha, Lui; Rahmaniheris, Maryam; Wan, Binhua; Hosseini, Mohammad; Tan, Pengliu; Berlin, Richard B

    2016-04-01

    Sepsis is a life-threatening condition caused by an inappropriate immune response to infection, and is a leading cause of elderly death globally. Early recognition of patients and timely antibiotic therapy based on guidelines improve survival rate. Unfortunately, for those patients, it is often detected late because it is too expensive and impractical to perform frequent monitoring for all the elderly. In this paper, we present a risk driven sepsis screening and monitoring framework to shorten the time of onset detection without frequent monitoring of all the elderly. Within this framework, the sepsis ultimate risk of onset probability and mortality is calculated based on a novel temporal probabilistic model named Auto-BN, which consists of time dependent state, state dependent property, and state dependent inference structures. Then, different stages of a patient are encoded into different states, monitoring frequency is encoded into the state dependent property, and screening content is encoded into different state dependent inference structures. In this way, the screening and monitoring frequency and content can be automatically adjusted when encoding the sepsis ultimate risk into the guard of state transition. This allows for flexible manipulation of the tradeoff between screening accuracy and frequency. We evaluate its effectiveness through empirical study, and incorporate it into existing medical guidance system to improve medical healthcare.

  20. Underpotential deposition of tin(II) on a gold disc electrode and determination of tin in a tin plate sample.

    Science.gov (United States)

    Qiao, Zhiqing; Shang, Wei; Zhang, Xin; Wang, Chunming

    2005-04-01

    This work describes a study of the underpotential deposition (UPD) of Sn2+ on a polycrystalline gold disc electrode using cyclic voltammetry (CV) and chronocoulometry (CC). Sn2+ ions showed well-defined peaks from UPD and UPD stripping (UPD-S) in 1 mol/L HCl solutions, while bulk deposition (BD) and BD stripping (BD-S) of the ions were also observed. The measured UPD shifts, DeltaE(UPD), between the UPD-S and the BD-S peaks were more than 200 mV. The UPD charge and the surface coverage of tin were measured by CC. A new method for determining Sn2+ was therefore developed, based on the excellent electrochemical properties of the Au/Sn UPD system. A plot of the UPD-DPASV (differential pulse anodic stripping voltammetry) signal versus the Sn(II) concentration was obtained for [Sn(II)] of 1.98x10(-7) to 3.64x10(-5) M. The method developed here has been applied to determine the tin in a tin plate sample.

  1. Graphene/h-BN/ZnO van der Waals tunneling heterostructure based ultraviolet photodetector.

    Science.gov (United States)

    Wu, Zhiqian; Li, Xiaoqiang; Zhong, Huikai; Zhang, Shengjiao; Wang, Peng; Kim, Tae-ho; Kwak, Sung Soo; Liu, Cheng; Chen, Hongsheng; Kim, Sang-Woo; Lin, Shisheng

    2015-07-27

    We report a novel ultraviolet photodetector based on graphene/h-BN/ZnO van der Waals heterostructure. Graphene/ZnO heterostructure shows poor rectification behavior and almost no photoresponse. In comparison, graphene/h-BN/ZnO structure shows improved electrical rectified behavior and surprising high UV photoresponse (1350AW(-1)), which is two or three orders magnitude larger than reported GaN UV photodetector (0.2~20AW(-1)). Such high photoresponse mainly originates from the introduction of ultrathin two-dimensional (2D) insulating h-BN layer, which behaves as the tunneling layer for holes produced in ZnO and the blocking layer for holes in graphene. The graphene/h-BN/ZnO heterostructure should be a novel and representative 2D heterostructure for improving the performance of 2D materials/Semiconductor heterostructure based optoelectronic devices.

  2. Fabrication of TiB2 composite powders coated with BN by high speed airflow impact

    Institute of Scientific and Technical Information of China (English)

    FENG Cai-mei; WANG Wei-min; FU Zheng-yi

    2005-01-01

    TiB2 powders coated with BN were prepared by Hybridization System making use of dry impact blending method to achieve powder surface modification. Parameters of coating were analyzed and the most appropriate condition was summarized. Scan electron microscope of JSM-5610LV and transmission electron microscope of H600STEM/EDS were used to observe the microstructure of coated powders. Results show that treatment time, rotation speed, granularity ratio of TiB2 to BN, pretreatment of materials etc influence the coating results evidently.Mixing raw materials and coating with BN under the appropriate condition can get round TiB2/BN composite powder with smooth surface and compact coating layer.

  3. STUDY ON EROSION RESISTANCE PROPERTIES OF O'-SIALON-BN IN MOLTEN STEEL

    Institute of Scientific and Technical Information of China (English)

    Q. Zhen; W.Z. Ding; W.C. Li

    2001-01-01

    The erosion resistance properties of O'-Sialon-BN in molten steel are investigated in this work. According to experimental results and theoretical analysis, BN in O'Sialon-BN plays an important role in molten steel erosion resistance. And the erosion kinetics of the O'-Sialon-BN composites in molten steel is controlled by two stages:the first one is controlled by chemical reaction taking place on the interface; the second one is controlled by diffusion. The erosion surface of the materials is also investigated with fractal theory. The results show that the fractal dimensions of the erosion surface vary with erosion time from a linear way to parabolic way, which relates to the change of erosion mechanism from interface chemical reaction to diffusion.

  4. Probing a General Rule towards Thermodynamic Stabilities of Mono BN-doped Lower Polyenes.

    Science.gov (United States)

    Rouf, Alvi Muhammad; Wu, Jingjing; Zhu, Jun

    2017-03-02

    The BN-doped organic analogues are interesting as aliphatic amineboranes for hydrogen storage, precursors for aromatic borazines and adsorbent cage azaboranes. However, BN-doped aliphatic polyenes remained undeveloped. Herein, we perform theoretical calculations on two mono BN-doped aliphatic lower polyenes, 1,3-butadiene and 1,3,5-hexatriene. A general rule is proposed, i.e., isomers with terminal nitrogen and directly BN-connected, N-B(R), in particular, are of significant thermodynamic stability as compared with their inverse analogues (where boron is at the terminal position). The N-B(R) type isomers are found to be the most stable ones in both polyenes. Isomers with terminal B and N are of intermediate stability. Highly destabilized isomers are those with one terminal methylene group and one terminal heteroatom in the butadiene series, and two terminal methylene groups in the hexatriene series. Rules established here may lead researchers to synthesize isomers with particular thermodynamic stability.

  5. Nanoindentation of ultra-hard cBN films: A molecular dynamics study

    Science.gov (United States)

    Huang, Cheng; Peng, Xianghe; Fu, Tao; Zhao, Yinbo; Feng, Chao; Lin, Zijun; Li, Qibin

    2017-01-01

    Cubic Boron nitride (cBN) exhibits excellent mechanical properties including high strength, hardness and thermal resistance, etc. We optimized the parameters in the Tersoff interatomic potential for cBN based on its cohesive energy, lattice parameter, elastic constants, surface energy and stacking fault energy. We performed with molecular dynamics (MD) simulations the nanoindentation on the (001) and (111) surface of monocrystalline cBN thin films to study the deformation mechanisms and the effects of temperature and substrate orientation. It was found that during the indentation plastic deformation is mainly stress-induced slips of dislocations along {111} orientations. It was also found that the hardness of cBN depends strongly on temperature, and the capability of plastic deformation is enhanced with the increase of temperature.

  6. Ap( Bn,dV)上具有BT符号的Toeplitz算子%Toeplitz operators on Ap (Bn, dV) with symbol in BT

    Institute of Scientific and Technical Information of China (English)

    何莉; 曹广福

    2011-01-01

    研究了高维Bergman空间Ap(Bn,dV)(1 <p<∞)上具有BT符号的Toeplitz算子,利用Toeplitz算子的Berezin变换讨论了Toeplitz算子的有界性,得到了Ap(Bn,dV)上具有BT符号的Toeplitz算子的范数和本性范数的估计,推广了MIAO和ZHENG在Bergman空间LP(D,dA)上对具有BT符号的Toeplitz算子的范数和本性范数进行估计的结论.

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

    Science.gov (United States)

    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.

  8. Band gap tunning in BN-doped graphene systems with high carrier mobility

    KAUST Repository

    Kaloni, T. P.

    2014-02-17

    Using density functional theory, we present a comparative study of the electronic properties of BN-doped graphene monolayer, bilayer, trilayer, and multilayer systems. In addition, we address a superlattice of pristine and BN-doped graphene. Five doping levels between 12.5% and 75% are considered, for which we obtain band gaps from 0.02 eV to 2.43 eV. We demonstrate a low effective mass of the charge carriers.

  9. Modeling Environmental Degradation of SiC/BN/SiC CMCs (Preprint)

    Science.gov (United States)

    2017-04-28

    display, or disclose the work. 14. ABSTRACT (Maximum 200 words ) Experimental data on the stress rupture behavior of SiC fiber based tows...oxygen and water from the environment through matrix cracks to internal fiber tows, the resulting oxidative loss of BN interphase, the oxidative...stress-rupture behavior of the CMCs or minicomposites. The models for oxidation and/or volatilization of BN and SiC by oxygen and water use

  10. Fabrication of AlN/BN bishell hollow nanofibers by electrospinning and atomic layer deposition

    Directory of Open Access Journals (Sweden)

    Ali Haider

    2014-09-01

    Full Text Available Aluminum nitride (AlN/boron nitride (BN bishell hollow nanofibers (HNFs have been fabricated by successive atomic layer deposition (ALD of AlN and sequential chemical vapor deposition (CVD of BN on electrospun polymeric nanofibrous template. A four-step fabrication process was utilized: (i fabrication of polymeric (nylon 6,6 nanofibers via electrospinning, (ii hollow cathode plasma-assisted ALD of AlN at 100 °C onto electrospun polymeric nanofibers, (iii calcination at 500 °C for 2 h in order to remove the polymeric template, and (iv sequential CVD growth of BN at 450 °C. AlN/BN HNFs have been characterized for their chemical composition, surface morphology, crystal structure, and internal nanostructure using X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction. Measurements confirmed the presence of crystalline hexagonal BN and AlN within the three dimensional (3D network of bishell HNFs with relatively low impurity content. In contrast to the smooth surface of the inner AlN layer, outer BN coating showed a highly rough 3D morphology in the form of BN nano-needle crystallites. It is shown that the combination of electrospinning and plasma-assisted low-temperature ALD/CVD can produce highly controlled multi-layered bishell nitride ceramic hollow nanostructures. While electrospinning enables easy fabrication of nanofibrous template, self-limiting reactions of plasma-assisted ALD and sequential CVD provide control over the wall thicknesses of AlN and BN layers with sub-nanometer accuracy.

  11. Bioinspired modification of h-BN for high thermal conductive composite films with aligned structure.

    Science.gov (United States)

    Shen, Heng; Guo, Jing; Wang, Hao; Zhao, Ning; Xu, Jian

    2015-03-18

    With the development of microelectronic technology, the demand of insulating electronic encapsulation materials with high thermal conductivity is ever growing and much attractive. Surface modification of chemical inert h-BN is yet a distressing issue which hinders its applications in thermal conductive composites. Here, dopamine chemistry has been used to achieve the facile surface modification of h-BN microplatelets by forming a polydopamine (PDA) shell on its surface. The successful and effective preparation of h-BN@PDA microplatelets has been confirmed by SEM, EDS, TEM, Raman spectroscopy, and TGA investigations. The PDA coating increases the dispersibility of the filler and enhances its interaction with PVA matrix as well. Based on the combination of surface modification and doctor blading, composite films with aligned h-BN@PDA are fabricated. The oriented fillers result in much higher in-plane thermal conductivities than the films with disordered structures produced by casting or using the pristine h-BN. The thermal conductivity is as high as 5.4 W m(-1) K(-1) at 10 vol % h-BN@PDA loading. The procedure is eco-friendly, easy handling, and suitable for the practical application in large scale.

  12. Preparation of BN/SiO2 ceramics by PIP method

    Institute of Scientific and Technical Information of China (English)

    WANG Jing; WEN Guang-wu; MENG Qing-chang

    2005-01-01

    The precursor infiltration and pyrolysis(PIP) method for preparation of BN/SiO2 composites was used to improve mechanical properties, dielectric properties and feasibility of high temperature dielectric parts with large dimensions and complex shapes. In the processing procedure, the porous BN ceramic matrix was first successfully prepared by compacting the mixed powders of B and BN and then sintering them at a certain temperature under normal pressure of N2.The polycarbosilane(PCS) solution was vacuum infiltrated into porous BN ceramics at the room temperature and then at 800 ℃ in the air to depolimerize out amorphous SiO2, and sintered further at 1 300 ℃ in N2 to get BN/SiO2 composites. The microstructure of materials was studied by means of X-ray diffraction and electron probe micro analysis. The thermo-decomposition mechanism of PCS was investigated by a TG-DTA and infrared (IR) spectrum analysis. The flexural strengths were measured by the three-point bending method. The dielectric constant and the loss tangent were measured by the wave-guide method. The results show BN/SiO2 composites were fabricated. The obtained composites posses a flexural strength of 61.9693.31 MPa, the dielectric constant in the range of 3.503.78 and the order of magnitude of the loss tangent at 10-3, which are good for the high temperature dielectric parts with large size and complex shapes.

  13. Structural and electronic properties of epitaxial multilayer h-BN on Ni(111) for spintronics applications.

    Science.gov (United States)

    Tonkikh, A A; Voloshina, E N; Werner, P; Blumtritt, H; Senkovskiy, B; Güntherodt, G; Parkin, S S P; Dedkov, Yu S

    2016-03-24

    Hexagonal boron nitride (h-BN) is a promising material for implementation in spintronics due to a large band gap, low spin-orbit coupling, and a small lattice mismatch to graphene and to close-packed surfaces of fcc-Ni(111) and hcp-Co(0001). Epitaxial deposition of h-BN on ferromagnetic metals is aimed at small interface scattering of charge and spin carriers. We report on the controlled growth of h-BN/Ni(111) by means of molecular beam epitaxy (MBE). Structural and electronic properties of this system are investigated using cross-section transmission electron microscopy (TEM) and electron spectroscopies which confirm good agreement with the properties of bulk h-BN. The latter are also corroborated by density functional theory (DFT) calculations, revealing that the first h-BN layer at the interface to Ni is metallic. Our investigations demonstrate that MBE is a promising, versatile alternative to both the exfoliation approach and chemical vapour deposition of h-BN.

  14. Third-generation muffin–tin orbitals

    Indian Academy of Sciences (India)

    O K Andersen; T Saha-Dasgupta; S Ezhov

    2003-01-01

    By the example of $sp^3$-bonded semiconductors, we illustrate what 3rd-generation muffin–tin orbitals (MTOs) are. We demonstrate that they can be downfolded to smaller and smaller basis sets: $sp^3d^{10}, sp^3$, and bond orbitals. For isolated bands, it is possible to generate Wannier functions a priori. Also for bands, which overlap other bands, Wannier-like MTOs can be generated a priori. Hence, MTOs have a unique capability for providing chemical understanding.

  15. Development of tin-plated regenerator material

    Science.gov (United States)

    Xu, M. Y.; Morie, T.; Tsuchiya, A.

    2017-02-01

    To improve the efficiency of a cryocooler, it is vital to improve the regenerator. In general, the heat capacity of materials decreases as temperature decreases. Thus, when temperature is below 50 K, lead spheres are often used as a regenerator material. However, the pressure drop through a sphere regenerator is larger than that through a screen regenerator. To overcome this dilemma, a new, low pressure loss tin-plated screen is proposed. A comparison test was performed with a two-stage GM cryocooler by replacing part of the first stage regenerator material, bronze screens with tin-plated screens. Compared to a regenerator filled with bronze screens, the cooling capacity of the first stage increased by about 14% at 40 K and 90% at 30 K with such tin-plated screens. The ratio of the wire diameter before and after the deposition was also optimized. An optimum cooling capacity of 53.5 W at 40 K was obtained at a diameter ratio of about 1.4. The detailed experimental results are reported in this paper.

  16. Analysis of bell materials: Tin bronzes

    Institute of Scientific and Technical Information of China (English)

    Jaromir Audy; Katarina Audy

    2008-01-01

    The present study was set up to examine the effect of alloying elements (including harmful elements) on metallurgical features (material properties and qualitative parameters) of tin bronzes, with particular reference to church bells from Middle Ages to Current times. A driving force of this study was to identify and demonstrate features related to the quality of church bells made in different centuries. The findings have been derived via metallographic and chemical analysis of specimens of bells from various parts of Australasia and Europe. The bell materials consisted of a mixture of the a phase and the (α+β) eutectoid essentially, in proportions determined by tin content and mould materials during casting. The samples from the 15th century to the one from the 20th century showed a progressive increase in hardness, ranging from the minimum of -280 VHM20g to a maximum of -470 VHM20g for the (α+β) eutectoid, and -160 VHM20g to -230 VHM20g for the a phase. The investigation also shows that the sound decay of the bell decreased with lowering the wt.% of tin and increasing the wt.% of lead and silver. This information is expected to provide an additional interesting knowledge into manufacturing practices and their significance in the quality of church bells over past centuries.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chubarov, Mikhail; Pedersen, Henrik; Högberg, Hans; Henry, Anne, E-mail: anne.henry@liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Czigány, Zsolt [Institute of Technical Physics and Materials Science, Centre for Energy Research of Hungarian Academy of Sciences, Konkoly-Thege Miklós út 29-33, H-1121 Budapest (Hungary)

    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} up 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.

  18. Electrorheological fluids of polypyrrole-tin oxide nanocomposite particles

    Science.gov (United States)

    Kim, Young Dae; Yoon, Dae Jeon

    2016-11-01

    The electrorheological (ER) response of polypyrrole(PPy)-tin oxide nanocomposite ER fluids increased with the increase in the tin oxide/pyrrole weight ratio, particle volume fraction, and electric field strength. The dielectric properties and direct current (dc) conductivity of PPy-tin oxide nanocomposite particles and the dielectric properties of PPy-tin oxide nanocomposite ER fluids agreed with the ER behaviors. The ER behavior of PPy-tin oxide nanocomposite ER fluids was well fitted to τ = 0.0248 ϕE 1.5 and showed a transition from that of the polarization model ( τ ˜ E 2) to that of the conduction model ( τ ˜ E 1.5) depending on the tin oxide/pyrrole weight ratio.

  19. Thermodynamics of the incongruently subliming niobium-tin system

    Energy Technology Data Exchange (ETDEWEB)

    Schiffman, R.A.; Bailey, D.M.

    1982-01-01

    The niobium-tin system was investigated in the temperature range 1261-2076 K by measurement of tin vapor pressures with a simultaneous weight loss-mass-spectrometric technique. For the reaction Nb + 1/3Sn ..-->.. NbSn/sub 1///sub 3/, ..delta..H/sub f//sup 298/ was found to be -21.59 kJ/mol. The heat of solution of tin in niobium was determined as a function of composition. The temperature-composition diagram for the niobium-tin system above 1200/sup 0/C was constructed. The Nb/sub 3/Sn phase has a narrow homogeneity range from 25 to 28 at% tin below 1600 K that broadens to include 18 at% tin at 2076 K.

  20. Heat Resistance of TiN Coated HSS Tools

    Institute of Scientific and Technical Information of China (English)

    周兰英; 周焕雷; 贾庆莲

    2003-01-01

    The cutting friction, cutting deformation, producing heat, conducting heat, temperature field of TiN coated HSS tools in the cutting process are discussed profoundly. In order to make clear the heat property of TiN coated tools, from the micromechanism angle, the relationship of the heat property and the crystal structure of TiN compound is analyzed, and the regularity of TiN compound crystal structure changing with temperature rising is sought. The difference of the wear resistance and heat resistance of TiN coated tools deposited by c1 and c2 depositing techniques is proved by tests. The conclusions will offer the theoretical basis for correct design of geometrical parameters of TiN coated tools, rational selection of cutting regimes and optimization of the depositing technique.

  1. Decomposition Pathway of Ammonia Borane on the Surface of nano-BN

    Energy Technology Data Exchange (ETDEWEB)

    Neiner, Doinita; Luedtke, Avery T; Karkamkar, Abhijeet J; Shaw, Wendy J; Wang, Julia; Browning, Nigel; Autrey, Thomas; Kauzlarich, Susan M

    2010-08-19

    Ammonia borane (AB) is under significant investigation as a possible hydrogen storage material. While many chemical additives have been demonstrated to have a significant positive effect on hydrogen release from ammonia borane, many provide additional complications in the regeneration cycle. Mechanically alloyed hexagonal BN (nano-BN) has been shown to facilitate the release of hydrogen from AB at lower temperature, with minimal induction time, less exothermically, and inert nano-BN may be easily removed during any regeneration of the spent AB. The samples were prepared by mechanically alloying AB with nano-BN. Raman spectroscopy indicates that the AB:nano-BN samples are physical mixtures of AB and h-BN. The release of hydrogen from AB:nano-BN mixtures as well as the decomposition products were characterized by 11B magic angle spinning (MAS) solid state NMR, TGA/DSC/MS with 15N labeled AB, and solution 11B NMR spectroscopy. The 11B MAS solid state NMR spectrum shows that diammonate of diborane (DADB) is present in the mechanically alloyed mixture, which drastically shortens the induction period for hydrogen release from AB. Analysis of the TGA/DSC/MS spectra using 15N labeled AB shows that all the borazine (BZ) produced in the reaction comes from AB and that increasing nano-BN surface area results in increased amounts of BZ. However, under high temperature, 150°C, isothermal conditions, the amount of BZ released was the same as for neat AB. High resolution transmission electron microscopy (HRTEM), selected area diffraction (SAD), and electron energy loss spectroscopy (EELS) of the initial and final nano-BN additive provide evidence for crystallinity loss but not significant chemical changes. The higher concentration of BZ observed for low temperature dehydrogenation of AB:nano-BN mixtures versus neat AB is attributed to a surface interaction that favors the formation of precursors which ultimately result in BZ

  2. Ab initio study of the structural, electronic and optical properties of BAs and BN compounds and BN{sub x}As{sub 1−x} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Guemou, M., E-mail: guemoumhamed7@gmail.com [Engineering Physics Laboratory, Ibn Khaldoun University of Tiaret, Postbox 78-Zaaroura, 14000 Tiaret (Algeria); Abdiche, A.; Riane, R. [Applied Materials Laboratory, Research Center, University of Sidi Bel Abbes, 22000 Sidi Bel Abbes (Algeria); Khenata, R. [Laboratoire de Physique Quantique et de Modélisation Mathématique (LPQ3M), Département de Technologie, Université de Mascara, 29000 Mascara (Algeria)

    2014-03-01

    In this work, we present a density-functional theory study of structural, electronic and optical properties of BAs, BN binary compounds and their ternary BN{sub x}As{sub 1−x} solid solutions. The calculations are done by using the all-electron full potential linear augmented plane-wave method (FP-LAPW) as employed in WIEN2k code. For the exchange-correlation potential, local-density approximation (LDA) and generalized gradient approximation (GGA) have been used to calculate theoretical lattice parameters, bulk modulus, and its pressure derivative. The electronic band structure of these compounds have been calculated by using the above two approximations. We have also investigated in this article the density of state and the optical properties such as the dielectric function and the refractive index of BAs, BN and BN{sub 0.25}As{sub 0.75} compounds by using the above method. The results obtained for structural and electronic properties are compared with experimental data and other computational work. It has been found that the energy bands with all these approximations are similar except the band gap values. It has also been found that our results with LDA and GGA are in good agreement with other computational work wherever these are available.

  3. Characterization of tin dioxide nanoparticles synthesized by oxidation

    OpenAIRE

    Abruzzi,R. C.; B. A. Dedavid; Pires,M. J. R.

    2015-01-01

    AbstractTin dioxide (SnO2) is a promising material with great potential for applications such as gas sensors and catalysts. Nanostructures of this oxide exhibit greater activation efficiency given their larger effective surface. The present study presents results of the synthesis and characterization of tin dioxide under different conditions via oxidation of solid tin with nitric oxide. SnO2powder was characterized primarily by X-ray diffraction and scanning electron microscopy, as well as co...

  4. Reductive spectrophotometry of divalent tin sensitization on soda lime glass

    Science.gov (United States)

    Bejugam, Vinith; Wei, Xingfei; Roper, D. Keith

    2016-07-01

    Rapid and facile evaluation of tin (II) sensitization could lead to improved understanding of metal deposition in electroless (EL) plating. This report used a balanced redox reaction between 3,3‧,5,5‧-tetramethylbenzidine dihydrochloride (TMB-HCL) and N-bromosuccinimide (NBS) to evaluate effects of sensitization conditions (i.e., sensitization time, analyte concentration, aqueous immersion, and acid content) on the accumulated mass of surface-associated divalent tin ion. The accumulated mass of tin (II) increased as the sensitization time increased up to 30 s in proportion to aqueous tin (II) chloride concentrations between 2.6 and 26 mM at a trifluoroacetic acid (TFA) content of 68 mM. The average mass peaked at 7.3 nanomoles (nmol) per cm2 after a 5 s aqueous immersion post-sensitization, and then decreased with increasing aqueous immersion post-sensitization. The total average tin (II) + tin (IV) accumulated on soda lime glass measured by inductively coupled plasma optical emission spectrometry (ICP-OES) was 17% higher at 30 s sensitization, suggesting a fraction of the tin (II) present may have oxidized to tin (IV). These results indicated that in situ spectrophotometric evaluation of tin (II) could support development of EL plating for electronics, catalysis, and solar cells.

  5. Silicon- and tin-based cuprates: now catalytic in copper!

    Science.gov (United States)

    Weickgenannt, Andreas; Oestreich, Martin

    2010-01-11

    Silicon- and tin-containing molecules are versatile building blocks in organic synthesis. A stalwart method for their preparation relies on the stoichiometric use of silicon- and tin-based cuprates, although a few copper(I)-catalyzed or even copper-free protocols have been known for decades. In this Concept, we describe our efforts towards copper(I)-catalyzed carbon--silicon and also carbon--tin bond formations using soft bis(triorganosilyl) and bis(triorganostannyl) zinc reagents as powerful sources of nucleophilic silicon and tin. Conjugate addition, allylic substitution, and carbon--carbon multiple bond functionalization is now catalytic in copper!

  6. Atomic dynamics of tin nanoparticles embedded into porous glass

    Energy Technology Data Exchange (ETDEWEB)

    Parshin, P. P.; Zemlyanov, M. G., E-mail: zeml@isssph.kiae.ru; Panova, G. Kh.; Shikov, A. A. [Russian Research Centre Kurchatov Institute (Russian Federation); Kumzerov, Yu. A.; Naberezhnov, A. A. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Sergueev, I.; Crichton, W. [European Synchrotron Radiation Facility (France); Chumakov, A. I. [Russian Research Centre Kurchatov Institute (Russian Federation); Rueffer, R. [European Synchrotron Radiation Facility (France)

    2012-03-15

    The method of resonant nuclear inelastic absorption of synchrotron radiation has been used to study the phonon spectrum for tin nanoparticles (with a natural isotope mixture) embedded into a porous glassy (silica) matrix with an average pore diameter of 7 nm in comparison to the analogous spectrum of bulk tin enriched with {sup 119}Sn isotope. Differences between the spectra have been observed, which are related to both the dimensional effects and specific structural features of the porous glass-tin nanocomposite. Peculiarities in the dynamics of tin atoms embedded into nanopores of glass are interpreted in terms of a qualitative model of the nanocomposite structure.

  7. EVALUASI PENGELOLAAN REFRIGERAN CFC, DAN HFC DENGAN MESIN 3R DAN UJI UNJUK KERJA MESIN PENDINGIN STUDI KASUS PADA BENGKEL AC MOBIL DI DENPASAR - BALI

    Directory of Open Access Journals (Sweden)

    I MADE RASTA

    2015-06-01

    Full Text Available CFC refrigerant has been known to be one of causes of ozone layer diminishing and HFC is one of green house gases contributing to global warming through the leak and synthetic refrigerant waste to environment. As a response to the ozone layer diminishment on stratosphere, UNEP, in 1981, through a negotiating process of international stages of development reserve the ozone layer through Wina Convention legalized in March 1985. It was then followed up with Montreal Protocol in September 1987 consisting supervision rules on producing, consuming, and treading ozone damaging materials. The government of Indonesia had ratified the convention through President Decree Number 23 Year 1999. The ozone layer reservation program implementation in Indonesia is facilitated by KLH. Governor of Bali issued Decree Number 523/04-B/HK/2010 on membership restructuring of ozone layer reservation and ozone damaging materials control team work in province of Bali. This research was done in 27 car AC service companies or workshop, which received grant of 3R engine in Denpasar, Bali. The research was dominantly focused on monitoring and evaluation, that is how car AC service company or workshop manage CFC/ R-12 and HFC/R-134a refrigerant at service time using 3R engine that refrigerant does not escape to atmostphere. Cooling machine work procedure test (COP was conducted in laboratory. Research result showed that car AC service company or workshop could manage CFC/ R-12 and HFC /R-l 34a eefctively ( 88,3%. The cooling engine work procedure using CFC /R-12 as the result of 3R engine recovery and recycel resulted in 2,435 while pure CFC/R-12 resulted in 2,54. There were differences in cooling engine work procedure to the use of pure CFC/R-12 refrigerant with that resulted by 3R engine with avarage difference 0,089 or 3,53%.

  8. The behaviour of Gd in lead and tin tellurides and its effect on their physical properties

    Science.gov (United States)

    Zayachuk, D. M.; Matulenis, E. L.; Mikityuk, V. I.

    1992-06-01

    The behaviour of gadolinium in Pb 1- xSn xTe (0 ⩽ x ⩽ 0.3) introduced during Bridgman growth and its effect on the composition profiles and free carrier concentration is investigated. The Gd, Pb, Sn and Te contents in crystals were determined by electron microprobe analysis, and the free carrier concentration was obtained by Hall measurements. The results indicate that Gd behaves like an impurity with a segregation coefficient larger than unity, which strongly depends on the Gd concentration N( L) Gd in the melt and is given by KS = 1 + Aexp( - BN( L) Gd), where A takes values of 8 or 9 and B a value of about 10 -20 cm 3. The effect of such a strong KS( N( L) Gd) dependence is that all the Gd impurity concentrates in the first-to-freeze section, leaving the rest of the ingot free from the impurity. Thus, by introducing Gd during melt growth of lead-tin telluride crystals, one can obtain high quality crystals of the solid solutions studied.

  9. Electrical transport properties of (BN-rich hexagonal (BNC semiconductor alloys

    Directory of Open Access Journals (Sweden)

    M. R. Uddin

    2014-08-01

    Full Text Available The layer structured hexagonal boron nitride carbon semiconductor alloys, h-(BNC, offer the unique abilities of bandgap engineering (from 0 for graphite to ∼6.4 eV for h-BN and electrical conductivity control (from semi-metal for graphite to insulator for undoped h-BN through alloying and have the potential to complement III-nitride wide bandgap semiconductors and carbon based nanostructured materials. Epilayers of (BN-rich h-(BN1-x(C2x alloys were synthesized by metal-organic chemical vapor deposition (MOCVD on (0001 sapphire substrates. Hall-effect measurements revealed that homogeneous (BN-rich h-(BN1-x(C2x alloys are naturally n-type. For alloys with x = 0.032, an electron mobility of about 20 cm2/Vs at 650 °K was measured. X-ray photoelectron spectroscopy (XPS was used to determine the chemical composition and analyze chemical bonding states. Both composition and chemical bonding analysis confirm the formation of alloys. XPS results indicate that the carbon concentration in the alloys increases almost linearly with the flow rate of the carbon precursor (propane (C3H8 employed during the epilayer growth. XPS chemical bonding analysis showed that these MOCVD grown alloys possess more C-N bonds than C-B bonds, which possibly renders the undoped h-(BN1-x(C2x alloys n-type and corroborates the Hall-effect measurement results.

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

    Science.gov (United States)

    Chung, Shyan-Lung; Lin, Jeng-Shung

    2016-05-20

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

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

    Directory of Open Access Journals (Sweden)

    Shyan-Lung Chung

    2016-05-01

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

  12. Vacuolar iron transporter BnMEB2 is involved in enhancing iron tolerance of Brassica napus

    Directory of Open Access Journals (Sweden)

    Wei Zhu

    2016-09-01

    Full Text Available Iron toxicity is a major nutrient disorder that severely affects crop development and yield. Vacuolar detoxification of metal stress is an important strategy for plants to survive and adapt to this adverse environment. Vacuolar iron transporter (VIT members are involved in this process and play essential roles in iron storage and transport. In this study, a rapeseed VIT gene BnMEB2 (BnaC07g30170D was identified. BnMEB2 is a homolog to Arabidopsis MEB2 (At5g24290 and acts as a detoxifier in vacuolar sequestration of divalent metal. Transient expression analysis revealed that BnMEB2 was localized to the vacuolar membrane. Q-PCR detection showed a high expression of BnMEB2 in mature (60-day-old leaves and could be obviously induced by exogenous iron stress in both roots and leaves. Over-expressed BnMEB2 in both Arabidopsis wild type and meb2 mutant seedlings resulted in greatly improved iron tolerability with no significant changes in the expression level of other vacuolar iron transporter genes. The mutant meb2 grew slowly and its root hair elongation was inhibited under high iron concentration condition while BnMEB2 over-expressed transgenic plants of the mutant restored the phenotypes with apparently higher iron storage in roots and dramatically increased iron content in the whole plant. Taken together, these results suggested that BnMEB2 was a VIT gene in rapeseed which was necessary for safe storage and vacuole detoxification function of excess iron to enhance the tolerance of iron toxicity. This research sheds light on a potentially new strategy for attenuating hazardous metal stress from environment and improving iron biofortification in Brassicaceae crops.

  13. Synthesis and characterization of cBN/WCCo composites obtained by the pulse plasma sintering (PPS) method

    Energy Technology Data Exchange (ETDEWEB)

    Michalski, A; Rosinski, M; Plocinska, M; Szawlowski, J, E-mail: mihalski@inmat.pw.edu.pl [Warsaw University of Technology, Faculty of Materials Science and Engineering, Warsaw (Poland)

    2011-10-29

    The cBN/cemented carbide containing 30vol% of cBN particles was produced using a mixture of a 6wt% Co added-WC powder, with a WC grain size of 0.4 {mu}m and a cBN powder with a grain size ranging from 4 to 40 {mu}m. The mixture was sintered to produce a plate, 20 mm in diameter, 3 mm thick. The sintering processes were conducted at temperature of 1100 deg. C under a load of 100 MPa. The phase composition, density, hardness and micro structure of the sintered parts thus obtained were examined. The fractures through the WCCo/cBN composite showed the cBN particles torn out from the cemented carbide matrix were only few, whereas most of them have cleaved along the fracture plane. This gives evidence that the bond at the WCCo/cBN interface is mechanically strong.

  14. Mechanical characterization of Si-C(O) fiber/SiC (CVI) matrix composites with a BN-interphase

    Energy Technology Data Exchange (ETDEWEB)

    Prouhet, S.; Camus, G.; Labrugere, C.; Guette, A. (Lab. des Composites Thermostructuraux, Pessac (France)); Martin, E. (Univ. de Bordeaux, Talence (France). Lab. de Genie Mechanique de l' IUT A)

    1994-03-01

    The mechanical behavior of three CVI-processed 2D woven SiC/BN/SiC composite materials with different initial BN interphase thicknesses has been investigated by means of tensile and impact tests. The results have established the efficiency of a BN interphase in promoting a nonlinear/noncatastrophic tensile behavior and high impact resistance. The effect of the initial BN interphase thickness on the resulting mechanical behavior has also been demonstrated. AES and TEM has revealed the presence of a SiO[sub 2]/C double layer at the BN/fiber interface, which might result from a decomposition undergone by the Si-C(O) Nicalon fiber during processing. It has been suggested that the influence of the initial BN interphase thickness on the mechanical properties of the composites results from both changes occurring in the composition and morphology of the interfacial zones and modifications of the interfacial forces due to accommodation of the radial residual clamping stress.

  15. Diseño de una red urbana HFC para la distribución de servicios avanzados de telecomunicación

    OpenAIRE

    2001-01-01

    Este traba}o presenta el diseño de la infraestructura básica correspondiente a una arquitectura de red híbrida fibra óptica-cable coaxial (HFC) para la distribución de contenidos telemáticos integrados por cable en pequeños núcleos urbanos. En este contexto el problema de Steiner modela adecuadamente la situación. Finalmente se presenta una batería de heurísticas que permite afrontar con éxito este tipo de diseños.

  16. (Vapour + liquid) equilibria of the {l_brace}1,1-difluoroethane (HFC-152a) + n-butane (HC-600){r_brace} system

    Energy Technology Data Exchange (ETDEWEB)

    Im, Jihoon [School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Lee, Gangwon [School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Lee, Yong-Jin [School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Kim, Hwayong [School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of) ]. E-mail: hwayongk@snu.ac.kr

    2007-08-15

    Binary (vapour + liquid) equilibrium data were obtained for the {l_brace}1,1-difluoroethane (HFC-152a) + n-butane (HC-600){r_brace} system at temperatures from 313.15 K to 363.15 K. These experiments were carried out with a circulating-type apparatus with on-line gas chromatography. The experimental data were correlated well by Peng-Robinson equation of state using the Wong-Sandler mixing rules. This system shows positive azeotropic phase behaviour.

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

    OpenAIRE

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

    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...

  18. Fabrication of high thermal conductive Al-cBN ceramic sinters by high temperature high pressure method

    Science.gov (United States)

    Wang, P. F.; Li, Zh. H.; Zhu, Y. M.

    2011-05-01

    Al-cBN ceramic sinters were fabricated by sintering micro-powder mixture of Al and cBN under high temperature and high pressure condition. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electronic microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) elemental mapping analyses and laser flashing thermal conductivity measurements were performed to investigate the sintering properties and thermal conductivity of the Al-cBN ceramic sinters. XRD analysis revealed these Al-cBN ceramic sinters were composed of a large portion of cBN and of a small portion of AlN, and very little amount of AlB 12 and hBN. Formation of boundary phase resulted in the rapid densification of the sinters, as well as the increase of their relative density with increasing Al additions. The Al-cBN ceramic sinters have a maximum thermal conductivity of about 1.94 W/cm K at room temperature and a much higher value of about 2.04 W/cm K at 200 °C. Their high thermal conductivity over that of AlN-hBN composites promise Al-cBN ceramic sinters favorite candidates as high efficiency heat sink materials for wide band gap semiconductors.

  19. Layered Graphene-Hexagonal BN Nanocomposites: Experimentally Feasible Approach to Charge-Induced Switchable CO2 Capture.

    Science.gov (United States)

    Tan, Xin; Kou, Liangzhi; Smith, Sean C

    2015-09-07

    Recently, inducing negative charge density on hexagonal boron nitride (h-BN) has been predicted as an effective strategy for controllable, selective, and reversible CO2 capture. However, h-BN is a wide-gap semiconductor and it is not clear how to effectively induce the requisite negative charge density. In this paper, we employ first-principle calculations to propose hybrid h-BN-graphene (hybrid BN/G) nanosheets as an experimentally feasible strategy to induce charge on h-BN for charge-controlled CO2 capture. The results indicate that the charge density is effectively transferred from the graphene layer with high electronic mobility into the h-BN layer on the surface, regardless of the thickness of BN layers, such that CO2 capture/release can be simply controlled by switching on/off the charge states of hybrid BN/G system. In addition, these negatively charged hybrid BN/G are highly selective for separating CO2 from mixtures with CH4 , N2 , and/or H2 .

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

    Science.gov (United States)

    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

  1. The Effect of Processing Parameters on the Performance of Spark Plasma Sintered cBN-WC-Co Composites

    Science.gov (United States)

    Mao, Cong; Zhang, Mingjun; Zhang, Jian; Tang, Kun; Gan, Hangyu; Zhang, Gaofeng

    2015-12-01

    Cubic boron nitride (cBN) particles were mixed into superfine tungsten carbide (WC), and then cBN-WC-cobalt (Co) composites were prepared using spark plasma sintering method. The influence of the processing parameters on the microstructures and the mechanical properties of the cBN-WC-Co composites were investigated. The results indicated that the cBN particles arranged uniformly and had an excellent adhesion with WC matrix. There was no evidence of phase transformation from cBN to hBN. With the increasing of the sintering temperature, the liquid-phase Co was increased and entered the micro-pores between WC and cBN particles easily. Correspondingly, the density, the flexural strength, and the hardness of the cBN-WC-Co composites also increased. With the further increasing of the sintering temperature, WC grains grew leading to the reduction of the hardness. Therefore, the hardness of the samples increased to a maximum value of 2978 HV at 1250 °C, and then decreased with the sintering temperature. The experimental results also showed that the density, the flexural strength, and the hardness of cBN-WC-Co composites increased with the holding time, whereas the hardness presented a decreasing tendency when the holding time exceeded 7 min.

  2. Identification of Thylakoid Membrane Protein Complexes by Using a BN-Chip/MS Approach

    Institute of Scientific and Technical Information of China (English)

    Longquan Fan; Yinghong Pan

    2012-01-01

    Thylakoid membrane protein complexes of wheat (Triticum aestivum Linn.)play crucial roles in growth and crop production.Knowledge of the composition and structure of protein complexes,as well as protein interactions,will result in a much deeper understanding of metabolic pathways and cellular processes than protein identities alone,especially if the complexes can be separated in the native forms.Whereas the analysis of membrane protein complexes is a significant challenge due to their hydrophobic properties and relatively low abundance.A rapid and efficient method of identifying membrane protein complexes will greatly facilitate the investigation of agriculture.The present work developed an BN-Chip/MS approach for exhaustive separation and identification of protein complexes,by combining using blue-native polyacrylamide gel electrophoresis (BN-PAGE) and chip-based high-performance liquid chromatography quadruple time-of-flight tandem mass spectrometry (HPLC-Chip/ESI-QT-OF-MS,Chip/MS).By using this approach,seventy-five nonredundant proteins of wheat thylakoid membrane complexes were identified from digested 13 bands of BN-gel.When the protocol of BN separation was not used,only 37 nonredundant proteins had been identified and among of them 9 proteins were uniquely identi? ed.This BN-Chip/MS approach is rapid and efficient for identifying protein complexes in wheat thylakoid membranes,and also providing reliable foundations for further functional research of wheat chloroplast and for identifying protein complexes of other species.

  3. Molecular self-assembly on graphene on SiO2 and h-BN substrates.

    Science.gov (United States)

    Järvinen, Päivi; Hämäläinen, Sampsa K; Banerjee, Kaustuv; Häkkinen, Pasi; Ijäs, Mari; Harju, Ari; Liljeroth, Peter

    2013-07-10

    One of the suggested ways of controlling the electronic properties of graphene is to establish a periodic potential modulation on it, which could be achieved by self-assembly of ordered molecular lattices. We have studied the self-assembly of cobalt phthalocyanines (CoPc) on chemical vapor deposition (CVD) grown graphene transferred onto silicon dioxide (SiO2) and hexagonal boron nitride (h-BN) substrates. Our scanning tunneling microscopy (STM) experiments show that, on both substrates, CoPc forms a square lattice. However, on SiO2, the domain size is limited by the corrugation of graphene, whereas on h-BN, single domain extends over entire terraces of the underlying h-BN. Additionally, scanning tunneling spectroscopy (STS) measurements suggest that CoPc molecules are doped by the substrate and that the level of doping varies from molecule to molecule. This variation is larger on graphene on SiO2 than on h-BN. These results suggest that graphene on h-BN is an ideal substrate for the study of molecular self-assembly toward controlling the electronic properties of graphene by engineered potential landscapes.

  4. Estrellas Bn: discontinuidad de Balmer; parámetros fundamentales y colores infrarrojos

    Science.gov (United States)

    Cochetti, Y. R.; Arias, M. L.; Cidale, L. S.; Granada, A.; Zorec, J.

    2015-08-01

    Bn stars are mainly main sequence objects with B spectral types, that display in their spectra broad hydrogen lines in absorption. This line broadening is originated by high rotational velocities. We know that high rotation is probably an essential factor in the development of the Be phenomenon: B stars with high rotational velocity and hydrogen lines in emission, which present an extended envelope. Thus, it is interesting to analyze Bn stars in a broader context, that includes Be stars, with the purpose of investigating their properties, the link between the formation of the envelopes and rotation, and the conditions which define the presence of emission lines. In this work we study a sample of 62 Bn star and 70 Be star spectra in the Balmer jump region. We analyze the presence and intensity of the second Balmer discontinuity, which reveals the existence of circumstellar material, its correlation with the projected rotational velocity, V sen(i), and the fundamental parameters of the stars. We also study the distribution of both groups in different infrared color-color diagrams, to generate methods to classify them in highly obscured regions. Our study suggests that Bn stars are the late counterpart of Be stars. The high projected rotational velocity, the spectral type distribution in both groups, and the presence of Bn stars with a second Balmer discontinuity in absorption, related with dense material close the photosphere, provide evidence that support this hypothesis.

  5. Synthesis of tin and tin oxide nanoparticles of low size dispersity for application in gas sensing.

    Science.gov (United States)

    Nayral, C; Viala, E; Fau, P; Senocq, F; Jumas, J C; Maisonnat, A; Chaudret, B

    2000-11-17

    Nanocomposite core-shell particles that consist of a Sn0 core surrounded by a thin layer of tin oxides have been prepared by thermolysis of [(Sn(NMe2)2)2] in anisole that contains small, controlled amounts of water. The particles were characterized by means of electronic microscopies (TEM, HRTEM, SEM), X-ray diffraction (XRD) studies, photoelectron spectroscopy (XPS), and Mossbauer spectroscopy. The TEM micrographs show spherical nanoparticles, the size and size distribution of which depends on the initial experimental conditions of temperature, time, water concentration, and tin precursor concentration. Nanoparticles of 19 nm median size and displaying a narrow size distribution have been obtained with excellent yield in the optimized conditions. HRTEM, XPS, XRD and Mossbauer studies indicate the composite nature of the particles that consist of a well-crystallized tin beta core of approximately equals 11 nm covered with a layer of approximately equals 4 nm of amorphous tin dioxide and which also contain quadratic tin monoxide crystallites. The thermal oxidation of this nanocomposite yields well-crystallized nanoparticles of SnO2* without coalescence or size change. XRD patterns show that the powder consists of a mixture of two phases: the tetragonal cassiterite phase, which is the most abundant, and an orthorhombic phase. In agreement with the small SnO2 particle size, the relative intensity of the adsorbed dioxygen peak observed on the XPS spectrum is remarkable, when compared with that observed in the case of larger SnO2 particles. This is consistent with electrical conductivity measurements, which demonstrate that this material is highly sensitive to the presence of a reducing gas such as carbon monoxide.

  6. Synthesis and Characterization of Tin(IV) Oxide Obtained by Chemical Vapor Deposition Method

    Science.gov (United States)

    Nagirnyak, Svitlana V.; Lutz, Victoriya A.; Dontsova, Tatiana A.; Astrelin, Igor M.

    2016-07-01

    The effect of precursors on the characteristics of tin oxide obtained by chemical vapor deposition (CVD) method was investigated. The synthesis of nanosized tin(IV) oxide was carried out with the use of two different precursors: tin(II) oxalate obtained using tin chloride(II) and oxalic acid; tin(II) oxalate obtained using tin chloride(II); and ammonium oxalate. The synthesized tin(IV) oxide samples were studied by electron microscopy, X-ray diffraction and optical spectra. The lattice parameters of tin(IV) oxide samples were defined, the bandgap of samples were calculated.

  7. Tin cans and refuse incineration: upgrading the scrap

    NARCIS (Netherlands)

    Dapper, G.; Dijkstra, S.J.; Loon, van A.P.M.

    1978-01-01

    In the series of investigations whether and how it is possible to reclaim the iron and tin constituents after incineration, several experiments were performed with the refuse incinerator of Amsterdam. The operating conditions were varied and the influence on the behaviour of the tin cans were determ

  8. Solution of a tinned iron purchasing problem by Lagrangean relaxation

    NARCIS (Netherlands)

    Dorhout, B.

    1995-01-01

    A tin factory obtains its material from steel works. This consists of sheets of tinned iron which may have very diverging specifications with respect to length, width, thickness, and thicknesses of tinfoils. Prices per unit of volume vary with width and thickness. For large quantities of the same si

  9. Application of Microwave Melting for the Recovery of Tin Powder

    Directory of Open Access Journals (Sweden)

    Lei Xu

    2017-06-01

    Full Text Available The present work explores the application of microwave heating for the melting of powdered tin. The morphology and particle size of powdered tin prepared by the centrifugal atomization method were characterized. The tin particles were uniform and spherical in shape, with 90% of the particles in the size range of 38–75 μm. The microwave absorption characteristic of the tin powder was assessed by an estimation of the dielectric properties. Microwave penetration was found to have good volumetric heating on powdered tin. Conduction losses were the main loss mechanisms for powdered tin by microwave heating at temperatures above 150 °C. A 20 kW commercial-scale microwave tin-melting unit was designed, developed, and utilized for production. This unit achieved a heating rate that was at least 10 times higher than those of conventional methods, as well as a far shorter melting duration. The results suggest that microwave heating accelerates the heating rate and shortens the melting time. Tin recovery rate was 97.79%, with a slag ratio of only 1.65% and other losses accounting for less than 0.56%. The unit energy consumption was only 0.17 (kW·h·kg–1—far lower than the energy required by conventional melting methods. Thus, the microwave melting process improved heating efficiency and reduced energy consumption.

  10. Mechanical Properties of Glass Surfaces Coated with Tin Oxide

    DEFF Research Database (Denmark)

    Swindlehurst, W. E.; Cantor, B.

    1978-01-01

    of tin tetrachloride on industrial soda glass at ~800K to thicknesses of ~3×10-8 and 3×10 -7 m, commercially by the `titanising' process on industrial soda glass at ~800K to a thickness of ~3.10-9 m, and in the laboratory by radio frequency sputtering from tin oxide powder over a range of glass...

  11. Dynamic Viscosity for HFC-134a + Polyether Mixtures up to 373.15 K and 140 MPa at Low Polyether Concentration. Measurements and Modeling

    CERN Document Server

    Comuñas, Maria J P; Boned, Christian; Fernandez, Josefa

    2008-01-01

    This paper reports viscosity data for mixtures containing a refrigerant (HFC-134a) and a lubricant (triethylene glycol dimethyether, TriEGDME, or tetraethylene glycol dimethyl ether, TEGDME), at 12% of TriEGDME or 14% mass fraction of TEGDME. The measurements (140 data points) were obtained at various pressures (between 10 and 140 MPa) in the monophasic liquid state from 293.15 to 373.15 K. Because HFC-134a and the polyethers are not in the same single phase at normal pressure and temperature (the refrigerant is a gas, whereas the polyethers are liquids), accurate measurements of their mixtures require specific procedures for preparation of the samples and filling of the apparatus. A specially designed isobaric-transfer falling-body viscometer is used in this work. The viscosities of the mixtures are, on average, 40% higher than that of the pure refrigerant, and this increase is more noticeable at low temperatures. The experimental viscosities have been used to check the predictive and correlation ability of ...

  12. Condensation of downward-flowing zeotropic mixture HCFC-123/HFC-134a on a staggered bundle of horizontal low-finned tubes

    Energy Technology Data Exchange (ETDEWEB)

    Honda, H.; Takamatsu, H.; Takata, N. [Kyushu Univ., Kasuga, Fukuoka (Japan). Inst. of Advanced Material Study

    1999-05-01

    Experiments were conducted to obtain row-by-row heat transfer data during condensation of downward-flowing zeotropic refrigerant mixture HCFC-123/HFC-134a on a 3 x 15 (columns x rows) staggered bundle of horizontal low-finned tubes. The vapor temperature and the HFC-134a mass fraction at the tube bundle inlet were maintained at about 50 C and 9%, respectively. The refrigerant mass velocity ranged from 9 to 34 kg/m{sup 2} s, and the condensation temperature difference from 3 to 12 K. The measured distribution of the vapor mass fraction in the tube bundle agreed fairly well with that of the equilibrium vapor mass fraction. The vapor phase mass transfer coefficient was obtained from the heat transfer data by subtracting the thermal resistance of the condensate film. The heat transfer coefficient and the mass transfer coefficient decreased significantly with decreasing mass velocity. These values first increased with the row number up to the third (or second) row, then decreased monotonically with further increasing row number, and then increased again at the last row. The mass transfer coefficient increased with condensation temperature difference, which was due to the effect of suction associated with condensation. On the basis of the analogy between heat and mass transfer, a dimensionless correlation of the mass transfer coefficient for the 4th to 14th rows was developed.

  13. Condensation of Downward-Flowing Zeotropic Mixture HCFC-123/HFC-134a on a Staggered Bundle of Horizontal Low-Finned Tubes

    Science.gov (United States)

    Honda, Hiroshi; Takamatsu, Hiroshi; Takata, Nobuo

    Expenmentswere conducted to obtain row-by-row heat transfer data during condensation of downward-flowing zeotropic refrigerant mixture HCFC-123/HFC-134 a on a staggered bundle of horizontal low-finned tubes. The vapor temperature and the HFC-134a m ass fraction at the tube bundle inlet were maintained at about 50°C and 14% respectively. The refrigerant mass velocity ranged from 9 to 33 kg/m2s, and the condensation temperature difference from 2 to 12K. Four kinds of low-finned tubes with different fin geometry were tested. The highest heat transfer coefficient was obtained with a tube which showed the highest performance for HCFC-123. However, the effect of fin geometry was much smaller for the mixture than for HCFC-123. The heat transfer coefficient and the vapor-phase mass transfer coefficient decreased significantly with decreasing mass velocity. On the other hand, the mass transfer coefficient increased with condensation temperature difference. This was due to the effect of suction associated with condensation. On the basis of the analogy between heat and mass transfer, a dimensionless correlation of the mass transfer coefficient was developed for each tube.

  14. Energy savings with the effect of magnetic field using R290/600a mixture as substitute for CFC12 and HFC134a

    Directory of Open Access Journals (Sweden)

    Mani Kolandavel

    2008-01-01

    Full Text Available This paper presents an experimental study on the replacement of CFC12 and HFC134a by the new R290/R600a refrigerant mixture as drop-in replacement refrigerant with and without the effect of magnetic field. Without any modification to the system components drop-in experimental tests were performed on a vapour compression refrigeration system with a reciprocating compressor, which was originally designed to operate with CFC12.The test results with no magnets showed that the refrigerant R290/R600a had 19.9-50.1% higher refrigerating capacity than R12 and 28.6-87.2% than R134a. The mixture R290/R600a consumed 6.8- -17.4% more energy than R12. The coefficient of performance of R290/R600a mixture increases from 3.9-25.1% than R12 at lower evaporating temperatures and 11.8-17.6% at higher evaporating temperatures. The effect of magnetic field force reduced the compressor energy consumption by 1.5-2.5% than with no magnets. The coefficient of performance of the system was higher in the range 1.5-2.4% with the effect of magnetic field force. The R290/600a (68/32 by wt.% mixture can be considered as an excellent alternative refrigerant for CFC12 and HFC134a systems.

  15. Comparative analysis of CO2-based transcritical Rankine cycle and HFC245fa-based subcritical organic Rankine cycle using low-temperature geothermal source

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A detailed thermodynamic and techno-economic comparison is presented for a CO2-based transcritical Rankine cycle and a subcritical organic Rankine cycle (ORC) using HFC245fa (1,1,1,3,3-pentafluoro-propane) as the working fluid driven by the low-temperature geothermal source,in order to determine the configuration that presents the maximum net power output with a minimum investment.The evaluations of both Rankine cycles have been performed based on equal thermodynamic mean heat rejection temperature by varying certain system operating parameters to achieve each Rankine cycle’s optimum design at various geothermal source temperature levels ranging from 80oC to 120oC.The results obtained show that the optimum ther-modynamic mean heat injection temperatures of both Rankine cycles are distributed in the scope of 55% to 65% of a given geothermal source temperature level,and that the CO2-based transcritical Rankine cycle presents 3% to 7% higher net power output,84% reduction of turbine inlet volume flow rate,47% reduction of expansion ratio and 1.68 times higher total heat transfer capacity compared with the HFC245fa-based subcritical ORC.It is also indicated that using the CO2-based transcritical system can reduce the dimension of turbine design.However,it requires larger heat transfer areas with higher strength heat exchanger materials because of the higher system pressure.

  16. BN/BNSiO2 sputtering yield shape profiles under stationary plasma thruster operating conditions

    Directory of Open Access Journals (Sweden)

    M. Ranjan

    2016-09-01

    Full Text Available Quartz Crystal Microbalance (QCM is used to measure the volumetric and total sputtering yield of Boron Nitride (BN and Boron Nitride Silicon Dioxide (BNSiO2 bombarded by Xenon ions in the energy range of 100 eV to 550 eV. Sputtering yield shape profiles are reported at various angles of incidence 0-85° with surface normal and compared with modified Zhang model. The yield shape profile is found to be symmetric at normal incidence and asymmetric at oblique incidence. Both the materials show a sudden jump in the sputtering yield above 500 eV and at an angle of incidence in the range of 45-65°. Erosion of BN at as low as 74 eV ion energy is predicted using generalized Bohdansky model. BNSiO2 show a marginally higher sputtering yield compare to BN.

  17. First-Principles Studies on Properties of Boron-Related Impurities in c-BN

    Institute of Scientific and Technical Information of China (English)

    TIAN Fu-Bo; WANG Xiao-Li; MA Yan-Ming; CUI Tian; LIU Bing-Bing; ZOU Guang-Tian

    2009-01-01

    We investigate,by first-principles calculations,the pressure dependence of formation enthalpies and defective geometry and bulk modulus of boron-related impurities (VB,CB,NB,and OB ) with different charged states in cubic boron nitride (c-BN) using a supercell approach.It is found that the nitrogen atoms surrounding the defect relax inward in the case of CB,while the nitrogen atoms relax outward in the other cases.These boron-related impurities become much more stable and have larger concentration with increasing pressure.The impurity C+B1 is found to have the lowest formation enthalpy,make the material exhibit semiconductor characters and have the bulk modulus higher than ideal c-BN and than those in the cases of other impurities.Our results suggest that the hardness of c-BN may be strengthened when a carbon atom substitutes at a B site.

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

    Directory of Open Access Journals (Sweden)

    Wu Liu

    2014-06-01

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

  19. Interfacial characteristics of mullite fiber/BN coating/mullite matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Chawla, K.K.; Xu, Z.R.; Ha, J.S. [New Mexico Tech, Socorro, NM (United States)] [and others

    1994-12-31

    The interface in mullite fiber Nextel 480/mullite matrix was engineered by using a thick BN (1 {mu}m) coating on mullite fibers, such that deformation mechanisms conducive to toughness enhancement could be brought to play. Significant improvements in the mechanical properties of these mullite fiber/mullite matrix composites could be achieved by incorporation of BN interfacial coating and by using a colloidal processing route to make dense mullite matrix. An interfacial testing system with a flat-bottomed, diamond indenter was used to obtain the interface characteristics. Using a progressive debonding of the interface model, it was determined that the average interfacial frictional sliding shear stress in this composite was about 50 MPa. Fracture surfaces of these BN coated composites obtained in flexure test showed fiber pullout.

  20. Effects of V-type ducts on condensation heat transfer of HFC245fa on horizontal tube bundles%V型导液槽对HFC245fa水平管束外冷凝换热影响

    Institute of Scientific and Technical Information of China (English)

    马志先; 张吉礼; 孙德兴

    2011-01-01

    试验研究了HFC245fa在水平光管与强化管管束外的冷凝换热特性,提出在管束中加装V型导液槽来消除管束效应的方法,并通过试验研究了V型导液槽对管束冷凝换热特性的影响.试验管束由4列排深为5排的列管构成,带导液槽管束的前4排管下方加装了两段长度为450 mm的导液槽;试验换热管公称外径为19.05 mm、换热长度为1000 mm.试验中,以Wilson描点法获得强化换热管水侧对流传热系数,以对比试验方法研究了V型导液槽对水平管束外冷凝换热性能的影响.结果表明:传统的管束效应模型仅在较小的热通量范围适用;凝液在管间的迁移形态与流态随管上作用凝液量的系列变化是导致管束效应变化的主要因素;加装导液槽可有效控制凝液在管间的迁移,控制管束效应;加装导液槽使光管单管冷凝传热能力下降10%左右,使光管管束总体换热能力提升4.5%~9.5%;加装导液槽对强化管单管冷凝换热性能的影响比对光管影响强近4倍.本文研究成果对引入导液槽开发新型高效卧式冷凝管束具有指导意义.%In a horizontal condensation tube-bundle, the inundation effect, resulted from local condensation film and falling condensate from upper tube rows, may reduce the condensation heat transfer coefficient (CHTC) considerably. This paper presents an experimental study on condensation heat transfer characteristic of HFC245fa on horizontal tube bundles. A scheme was proposed to reduce the tube row effect resulted from falling condensate with V-type ducts, and the effect of the duct on CHTC of the tube bundles was investigated experimentally. The tube bundle consisted of 4 columns, each with 5 tubes, with smooth tubes and enhanced tubes, separately. Two columns out of the four were equipped with the duct. The equivalent outside diameter and effective length for heat transfer of tubes were 19.05 mm and 1000 mm respectively. In the experiment, water

  1. Studies on Properties and Structure of Electroless Plating Tin Coating

    Institute of Scientific and Technical Information of China (English)

    XU Rui-dong; GUO Zhong-cheng; ZHU Xiao-yun

    2004-01-01

    The composition and structure of electroless tin coating were analyzed by SEM and X-ray diffraction. In the meantime, porosity, solderability and extensibility were determined by physical and chemical methods. The results showed that the porosity of the tin coating increases with the rise of bath temperature and decreases as the plating time rises. Solderability is improved with the rise of thickness of tin coating, and decreases when the tin deposit is heated at 180 ~ 200 ℃. The crystalline grain size becomes bigger and bigger with increasing plating time or bath temperature or coating thickness. X-ray diffraction indicates that only Cu and β-Sn phases show up in the diffraction patterns. Tin coating has a strong joint force with copper substrate and excellent function of electrochemical protection as anode coating.

  2. The Stress Distribution and Thermal Behavior of TiBN and TiBN/TiN Coatings in Milling AISI H13 Work Tool Steel

    Institute of Scientific and Technical Information of China (English)

    YAN Hong; HUA Jiang; SHIVPURI Raja

    2005-01-01

    The FEM model of TiBN and TiBN/TiN coated cutting tool in milling of H13 steel was developed. Process variables such as temperature and stress in the coating layer as well as in the substrate were analyzed. The efficacy of the present FEM analysis was verified by conducting controlled milling experiments on AISI H13 to collect the relevant tool life and force data.The results show that the stress in a coated tool can significantly be reduced compared to an uncoated cutting tool,possibly due to surface coatings improving the tribological properties of cutting tools.Coatings with good thermal properties also help to improve the thermal behavior of cutting tool.

  3. Synthesis of O'-SiAlON-BN Composite by Reaction Sintering

    Institute of Scientific and Technical Information of China (English)

    ZHEN Qiang; YAN Kai; ZHANG Dahai; LI Wenchao

    2006-01-01

    By using micron α-Si3N4, SiO2, Al2O3 and h-BN as starting materials, O' -SiAlON-BN ( Si2-ZAlzO1+zN2-z, z = 0.3) composite was synthesized by reaction sintering. According to theoretical proportion ratio:n(SiO2)/n(α-Si3N4) = 1, the effects of two sintering aid comtosites, Y2O3+B2O3 and Y2O3+TiO2 at 1700℃ for 2h, were studied. The results indicate that Y2O3+TiO2 as sintering aid can accelerate reaction sintering of O'-SiAlON-BN more effectively than Y2O3+B2O3, and the relative density of the composites declined with the increase of BN addition (10%, 20% and30% respectively); XRD analysis found that excessive β-Si3N4 existed in the O' -SiAlON-BN composite. Therefore, in order to get more pure O' -SiAlON and BN phases in the composites ore SiO2 is needed. When Y2O3+TiO2 was used as sintering aid and addition of BN was 10%, the result of cross experiment on condition of A n(SiO2)/n(α-Si3N4) was 1.05, 1.1 and1.2; B addition of sintering aid was 2%, 4% and 6%; C firing temperature was 1600℃, 1650℃ and 1700℃ ;D-soaking time was 1h, 2h and 3h, shows that the sintering properties were influenced by factors of firing temperature, soaking time, addition of sintering aid and n(SiO2)/n(α-Si3N4) in order of importance. In addition, the technical parameter A3B3C3D3 can achieve the highest relative density. Besides, using Pattern Recognition method, the optimized parameter range to form pure O' -SiAlON and BN without β-Si3N4 remained was determined as Y > 1024X2 - 230.400X+11.088 ( X =0.9999A-0.0006C-0.0163D, Y =0.0163A +0.0009B -0.0014C+0.9999D).

  4. 单位球Bn上的Bohr不等式%Bohr's Inequality on the Unit Ball Bn

    Institute of Scientific and Technical Information of China (English)

    王建飞; 刘太顺

    2007-01-01

    Bohr's type inequalities are studied in this paper: if / is a holomorphic mapping from the unit ball Bn to B", /(O) = p, then we have ∞∑k=0|Dψp(P)[Dkf(0)(zk)]|k!||Dψp(p)||<1 for |z|< max{1/2+|p|,√1-|p|/2} and ψp ∈ Aut(Bn) such that ψp (p) = 0. As corollaries of theabove estimate, we obtain some sharp Bohr's type modulus inequalities. In particular, whenn=1 and |P| →1, then our theorem reduces to a classical result of Bohr.

  5. Near-band edge optical properties of exfoliated h-BN layers.

    OpenAIRE

    Loyza, J.; Barjon, J; Pierret, A.; Betz, A.; Placais, B.; Ducastelle, F.; Loiseau, A.

    2013-01-01

    Luminescence properties of h-BN are governed, in the energy range 5.5 { 6 eV, by strong Frenkel-type excitonic e ects, highly sensitive to structural defects [1-3]. Nowadays, BN meets a growing interest for graphene engineering. It is therefore highly desirable to better know optical and electronic properties of thin layers, in correlation with their structural properties. We carry out optical and structural characterizations of this material by combining CL at 4K in the UV range and TEM. Thi...

  6. B=N Units as Part of Extended π-Conjugated Oligomers and Polymers.

    Science.gov (United States)

    Helten, Holger

    2016-09-01

    The replacement of C=C units by their isoelectronic and isosteric B=N units (BN/CC isosterism) in π-conjugated organic compounds, as a strategy to produce novel organic-inorganic hybrid materials, has recently been successfully transferred to π-conjugated polymers. This Concept provides an overview of the recent advances in this quickly evolving field, with a focus on synthesis, photophysical and electrochemical properties of the new polymers and related oligomers, as well as possible future applications in organic electronics and optoelectronics.

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

    Science.gov (United States)

    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.

  8. Phonons and electron-phonon coupling in graphene-h-BN heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Slotman, Guus J.; Wijs, Gilles A. de; Fasolino, Annalisa; Katsnelson, Mikhail I. [Institute for Molecules and Materials, Radboud University Nijmegen (Netherlands)

    2014-10-15

    First principle calculations of the phonons of graphene-h-BN heterostructures are presented and compared to those of the constituents. It is shown that AA and AB' stacking are not only energetically less favoured than AB but also dynamically unstable. Low energy flat phonon branches of h-BN character with out of plane displacement have been identified and their coupling to electrons in graphene has been evaluated. (copyright 2014 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Proper Motions of the BN Object and the I Radio Source in Orion: Where and When Did BN Become a Runaway Star?

    CERN Document Server

    Rodríguez, L F; Lizano, S; Allen, C; Rodriguez, Luis F.; Poveda, Arcadio; Lizano, Susana; Allen, Christine

    2005-01-01

    We present absolute astrometry of the core of the Orion molecular cloud, made with Very Large Array archive data taken over the last two decades. Our analysis reveals that both the BN object and the radio source I have proper motions: the BN object has a proper motion of $12.6 \\pm 0.6$ mas yr$^{-1}$ (corresponding to a velocity of $27 \\pm 1$ km s$^{-1}$ at an adopted distance of 450 pc) to the northwest, while the radio source I has a proper motion of $5.6 \\pm 0.7$ mas yr$^{-1}$ (corresponding to a velocity of $12 \\pm 2$ km s$^{-1}$) to the southeast. The motion of the two sources is nearly antiparallel, diverging from a point in between them, where they were located about 500 years ago. These results suggest that the BN object and the radio source I were part of a multiple young stellar system that disintegrated in the recent past.

  10. Divacancy-assisted transition metal adsorption on the BN graphene and its interaction with hydrogen molecules: a theoretical study

    Science.gov (United States)

    Chen, Ying; Wang, Hongmei; Wang, Hongxia; Zhao, Jing-xiang; Cai, Qing-hai; Wang, Xiao-Guang; Ding, Yi-hong

    2013-05-01

    We have performed first-principles calculations to study the chemical functionalization of the BN graphene with divacancy (DV) defect by 12 different transition metal (TM) atoms, including Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pt, and Au. The results indicate that the DV defect can assist the adsorption of TM atoms on BN graphene. Moreover, some impurity bands are induced within the band gap of DV-BN graphene, leading to the modification of its electronic properties in various ways. Interestingly, Ti- and Co-adsorbed DV-BN graphenes are found to possess ferromagnetic characteristic, while antiferromagnetic state is preferred for V-, Mn-, and Fe-functionalized DV-BN graphenes, and the paramagnetic state is the ground state for Sc-, Cr-, Ni-, Cu, Zn-, Pt-, and Au-decorated DV-BN graphenes. Finally, aiming at evaluating the potential of these functionalized BN graphenes in hydrogen storage, we study their interaction with H2 molecules. It is found that the dispersed Sc, V, and Cr on DV-BN graphene are able to adsorb up to three H2 molecules as strongly as 0.25-0.58 eV/H2, suggesting that the three nanomaterials may be suitable candidates for hydrogen storage.

  11. Divacancy-assisted transition metal adsorption on the BN graphene and its interaction with hydrogen molecules: a theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ying; Wang, Hongmei; Wang, Hongxia [Key Laboratory for Photoelectric Bandgap Materials, Ministry of Education, Harbin Normal University, Harbin 150025 (China); Zhao, Jing-xiang, E-mail: xjz_hmily@yahoo.com.cn [Key Laboratory for Photoelectric Bandgap Materials, Ministry of Education, Harbin Normal University, Harbin 150025 (China); Cai, Qing-hai; Wang, Xiao-Guang [Key Laboratory for Photoelectric Bandgap Materials, Ministry of Education, Harbin Normal University, Harbin 150025 (China); Ding, Yi-hong, E-mail: yhdd@jlu.edu.cn [State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023 (China)

    2013-05-15

    We have performed first-principles calculations to study the chemical functionalization of the BN graphene with divacancy (DV) defect by 12 different transition metal (TM) atoms, including Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pt, and Au. The results indicate that the DV defect can assist the adsorption of TM atoms on BN graphene. Moreover, some impurity bands are induced within the band gap of DV-BN graphene, leading to the modification of its electronic properties in various ways. Interestingly, Ti- and Co-adsorbed DV-BN graphenes are found to possess ferromagnetic characteristic, while antiferromagnetic state is preferred for V-, Mn-, and Fe-functionalized DV-BN graphenes, and the paramagnetic state is the ground state for Sc-, Cr-, Ni-, Cu, Zn-, Pt-, and Au-decorated DV-BN graphenes. Finally, aiming at evaluating the potential of these functionalized BN graphenes in hydrogen storage, we study their interaction with H{sub 2} molecules. It is found that the dispersed Sc, V, and Cr on DV-BN graphene are able to adsorb up to three H{sub 2} molecules as strongly as 0.25–0.58 eV/H{sub 2}, suggesting that the three nanomaterials may be suitable candidates for hydrogen storage.

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

    Science.gov (United States)

    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.

  13. 78 FR 28836 - Vulcan/BN Geothermal Power Company; Supplemental Notice That Initial Market-Based Rate Filing...

    Science.gov (United States)

    2013-05-16

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Vulcan/BN Geothermal Power Company; Supplemental Notice That Initial Market... in the above-referenced proceeding of Vulcan/BN Geothermal Power Company's application for...

  14. Generated photocatalytic performance of h-BN sheet by coupling with reduced graphene oxide/fluorid: A DFT study

    Science.gov (United States)

    Lu, Baichuan; Jia, Jun; Guo, Fengjuan; Li, Dongyang; Zhao, Yunhao; Zhao, Xian; Gao, Hongtao

    2017-09-01

    First-principles calculation based on density functional theory (DFT) was performed to investigate the enhanced photocatalytic mechanism and electronic properties of hexagonal boron nitride (h-BN) sheet by coupling with reduced graphene oxide (RGO) or reduced graphene fluorid (RGF). It is demonstrated that the combination of h-BN with RGO(F) is thermodynamically favorable. The spatial configurations of O and F atoms played a key role in modifying the electronic structure and properties of h-BN/RGO(F) composites. The interaction between h-BN and RGO(F) sheets caused charge accumulation on the side of h-BN layer and charge depletion on the lower side of RGO(F) sheet. There formed a heterjunction between the interface, which could improve the separation efficiency of photogenerated carriers and inhibit their combination. Both valence band edge and conduction band edge positions of h-BN/RGO(F) composites were characterized to illustrate the enhanced oxidation-reduction performance mechanism. The theoretical investigation could provide valuable information for thoroughly understanding the mechanism of the exceptional performance of h-BN/RGO(F) composites compared to the h-BN sheet.

  15. Electrochemical behavior of tin(II at the electrodeposition tin sulfide on Mo-electrode

    Directory of Open Access Journals (Sweden)

    Kazhmukhan Urazov

    2015-03-01

    Full Text Available The electrochemical behavior of tin ions (II and thiosulfate ions (S2O32- on the Mo electrode in various concentrations and potential scan rate was studied by voltammetric method. Dependence of oxidation and reduction currents from concentrations of tin (II ions and scan rate was obtained. It was showed the diffusion nature of the limiting stage of reduction. It was determined the different voltammograms’s character with a sweep potential to E = -1300mV or -1500mV for simultaneous reduction ions Sn (II and (S2O32- from 0,2 M sodium citrate on molybdenum electrode. Nanocrystalline films SnS with a thickness of 1 µ were obtained by the electrodeposition on glass/SnO2.

  16. Solderability perservative coatings: Electroless tin vs. organic azoles

    Energy Technology Data Exchange (ETDEWEB)

    Artaki, I.; Ray, U.; Jackson, A.M.; Gordon, H.M. [AT and T Bell Labs., Princeton, NJ (United States); Vianco, P.T. [Sandia National Labs., Albuquerque, NM (United States)

    1993-07-01

    This paper compares the solderability performance and corrosions ion protection effectiveness of electroless tin coatings versus organic azole films after exposure to a series of humidity and thermal (lead-free solders) cycling conditions. The solderability of immersion tin is directly related to the tin oxide growth on the surface and is not affected by the formation of Sn-Cu intermetallic phases as long as the intermetallic phase is protected by a Sn layer. For a nominal tin thickness of 60{mu}inches, the typical thermal excursions associated with assembly are not sufficient to cause the intermetallic phase to consume the entire tin layer. Exposure to humidity at moderate to elevated temperatures promotes heavy tin oxide formation which leads to solderability loss. In contrast, thin azole films are more robust to humidity exposure; however upon heating in the presence of oxygen, they decompose and lead to severe solderability degradation. Evaluations of lead-free solder pastes for surface mount assembly applications indicate that immersion tin significantly improves the spreading of Sn:Ag and Sn:Bi alloys as compared to azole surface finishes.

  17. Tin LPP plasma control in the argon cusp source

    Science.gov (United States)

    McGeoch, Malcolm W.

    2016-03-01

    The argon cusp plasma has been introduced [1,2] for 500W class tin LPP exhaust control in view of its high power handling, predicted low tin back-scatter from a beam dump, and avoidance of hydrogen usage. The physics of tin ion control by a plasma is first discussed. Experimentally, cusp stability and exhaust disc geometry have previously been proved at full scale [2], the equivalent of 300W-500W usable EUV. Here we verify operation of the plasma barrier that maintains a high argon density next to the collector, for its protection, and a low density in the long path toward the intermediate focus, for efficiency. A pressure differential of 2Pa has been demonstrated in initial work. Other aspects of tin LPP plasma control by the cusp have now been demonstrated using tin ions from a low Hz 130mJ CO2 laser pulse onto a solid tin surface at the cusp center. Plasma is rejected at the design to match a specified exhaust power is discussed. In view of this work, argon cusp exhaust control appears to be very promising for 500W class tin LPP sources.

  18. (n,{gamma}) Experiments on tin isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Baramsai, B.; Mitchell, G. E.; Walker, C. L.; Rusev, G. [North Carolina State University, Raleigh, NC 27695, USA and Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Mosby, S.; O' Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Becvar, F.; Krticka, M.; Kroll, J. [Charles University of Prague, V Holesovickach 2, 180 00 Prague 8 (Czech Republic); Agvaanluvsan, U.; Dashdorj, D.; Erdenehuluun, B.; Tsend-Ayush, T. [MonAme Scientific Research Center, Ulaanbaatar (Mongolia)

    2013-04-19

    Neutron capture experiments on highly enriched {sup 117,119}Sn isotopes were performed with the DANCE detector array located at the Los Alamos Neutron Science Center. The DANCE detector provides detailed information about the multi-step {gamma}-ray cascade following neutron capture. Analysis of the experimental data provides important information to improve understanding of the neutron capture reaction, including a test of the statistical model, the assignment of spins and parities of neutron resonances, and information concerning the Photon Strength Function (PSF) and Level Density (LD) below the neutron separation energy. Preliminary results for the (n,{gamma}) reaction on {sup 117,119}Sn are presented. Resonance spins of the odd-A tin isotopes were almost completely unknown. Resonance spins and parities have been assigned via analysis of the multi-step {gamma}-ray spectra and directional correlations.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2016-10-01

    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.

  1. Excitonic recombinations in h-BN: From bulk to exfoliated layers

    Science.gov (United States)

    Pierret, A.; Loayza, J.; Berini, B.; Betz, A.; Plaçais, B.; Ducastelle, F.; Barjon, J.; Loiseau, A.

    2014-01-01

    Hexagonal boron nitride (h-BN) and graphite are structurally similar but with very different properties. Their combination in graphene-based devices is now of intense research focus, and it becomes particularly important to evaluate the role played by crystalline defects on their properties. In this paper, the cathodoluminescence (CL) properties of hexagonal boron nitride crystallites are reported and compared to those of nanosheets mechanically exfoliated from them. First, the link between the presence of structural defects and the recombination intensity of trapped excitons, the so-called D series, is confirmed. Low defective h-BN regions are further evidenced by CL spectral mapping (hyperspectral imaging), allowing us to observe new features in the near-band-edge region, tentatively attributed to phonon replicas of exciton recombinations. Second, the h-BN thickness was reduced down to six atomic layers, using mechanical exfoliation, as evidenced by atomic force microscopy. Even at these low thicknesses, the luminescence remains intense and exciton recombination energies are not strongly modified with respect to the bulk, as expected from theoretical calculations, indicating extremely compact excitons in h-BN.

  2. Ab initio study of Mn adsorption on w-BN(0 0 0 1) surface

    Energy Technology Data Exchange (ETDEWEB)

    Perez, W. Lopez [GFMC, Departamento de Matematicas y Fisica, Universidad del Norte, A. A. 1569, Barranquilla (Colombia)], E-mail: wlopez@uninorte.edu.co; Rodriguez Martinez, J.A.; Fajardo, F.; Cardona, R. [GEMA - Grupo de estudio de materiales, Departamento de Fisica, Universidad Nacional de Colombia, A. A. 5997, Bogota (Colombia)

    2008-07-15

    We have carried out total energy calculations to study the adsorption energy of Mn on w-BN(0 0 0 1) surface in a 2x2 structure. The surface is modeled using the repeated slabs approach. The calculation was performed solving the Kohn-Sham equation with a plane wave-pseudopotential approach and the generalized gradient approximation (GGA), using the Quantum-Espresso package. We find that with a Mn adatom, the w-BN(0 0 0 1) lateral surface relaxation was around some hundredth of A. To study the most favorable Mn adsorption configuration we considered T{sub 1}, T{sub 4} and H{sub 3} special points. We predict that the Mn-T{sub 4} structure is the most energetically favorable. We find that the adsorption of a Mn atom on top of a B atom (T{sub 1} site) is totally unfavorable. The calculated potential energy to describe the diffusion of a Mn atom on w-BN(0 0 0 1) shows an energy barrier of 0.708 eV. From the density of states with polarized spin we discuss the magnetic effect of Mn on w-BN(0 0 0 1) surface.

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

    Science.gov (United States)

    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.

  4. Using charged defects in BN to create rewritable graphene quantum dots and visualize quantum interference

    Science.gov (United States)

    Velasco, Jairo, Jr.

    Heterostructures of graphene and hexagonal boron nitride (BN) are highly tunable platforms that enable the study of novel physical phenomena and technologically promising nanoelectronic devices. Common control schemes employed in these studies are electrostatic gating and chemical doping. However, these methods have significant drawbacks, such as complicated fabrication processes that introduce contamination and irreversible changes to material properties, as well as a lack of flexible control. To address these problems we have developed a new method that employs light and/or electric field excitation to control defect charge (from the single impurity level to ensembles) in the underlying BN. We have used optoelectronic and scanning tunneling spectroscopy measurements to characterize these BN defects. We find that by manipulating defect charge in BN it is possible to create rewritable tip-induced doping patterns such as gate-tunable graphene pn junctions and quantum dots. This creates new opportunities for mapping the electronic states of confined electrons in graphene and to visualize their quantum interference behavior.

  5. Studies on BN rats model to determine the potential allergenicity of proteins from genetically modified foods

    Institute of Scientific and Technical Information of China (English)

    Xu-Dong Jia; Ning Li; Yong-Ning Wu; Xiao-Guang Yang

    2005-01-01

    AIM: To develop a Brown Norway (BN) rat model to determine the potential allergenicity of novel proteins in genetically modified food.METHODS: The allergenicity of different proteins were compared, including ovalbumin (OVA), a potent respiratory and food allergen, bovine serum albumin (BSA), a protein that is considered to have a lesser allergenic potential,and potato acid phosphatase (PAP), a non-allergenic protein when administered to BN rats via different routes of exposure (intraperitoneally or by gavage). IgG and IgE antibody responses were determined by ELISA and PCA,respectively. An immunoassay kit was used to determine the plasma histamine level. In addition, possible systemic effect of allergens was investigated by monitoring blood pressure.RESULTS: OVA provoked very vigorous protein-specific IgG and IgE responses, low grade protein-specific IgG and IgE responses were elicited by BSA, while by neither route did PAP elicit anything. In either routes of exposure,plasma histamine level in BN rats sensitized with OVA was higher than that of BSA or PAP. In addition, an oral challenge with BSA and PAP did not induce any effect on blood pressure, while a temporary drop in systolic blood pressure in few animals of each routes of exposure was found by an oral challenge with OVA.CONCLUSION: BN rat model might be a useful and predictive animal model to study the potential allergenicity of novel food proteins.

  6. Resolving the Structure and Kinematics of the BN Object at $0\\rlap.{"}2$ Resolution

    CERN Document Server

    Rodr{\\'\\i}guez, Luis F; Ho, Paul T P

    2008-01-01

    We present sensitive 7 mm observations of the H53$\\alpha$ recombination line and adjacent continuum, made toward the Orion BN/KL region. In the continuum we detect the BN object, the radio source I (GMR I) and the radio counterpart of the infrared source n (Orion-n). Comparing with observations made at similar angular resolutions but lower frequency, we discuss the spectral indices and angular sizes of these sources. In the H53$\\alpha$ line we only detect the BN object. This is the first time that radio recombination lines are detected from this source. The LSR radial velocity of BN from the H53$\\alpha$ line, $v_{LSR} = 20.1 \\pm 2.1$ km s$^{-1}$, is consistent with that found from previous studies in near-infared lines. While the continuum emission is expected to have considerable optical depth at 7 mm, the observed H53$\\alpha$ line emission is consistent with an optically-thin nature and we discuss possible explanations for this apparent discrepancy. There is evidence of a velocity gradient, with the NE part...

  7. 76 FR 14902 - Certain Tin Mill Products From Japan: Rescission of Antidumping Duty Administrative Review

    Science.gov (United States)

    2011-03-18

    ..., surface finish, temper, coating metal (tin, chromium, chromium oxide), reduction (single-or double-reduced... products that are coated or plated with tin, chromium or chromium oxides. Flat-rolled steel products coated with tin are known as tin plate. Flat-rolled steel products coated with chromium or chromium oxides...

  8. Tin-phosphate glass anode for sodium ion batteries

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Honma

    2013-11-01

    Full Text Available The electrochemical property of tin-phosphate (designate as GSPO glass anode for the sodium ion battery was studied. During the first charge process, sodium ion diffused into GSPO glass matrix and due to the reduction of Sn2+ to Sn0 state sodiated tin metal nano-size particles are formed in oxide glass matrix. After the second cycle, we confirmed the steady reversible reaction ∼320 mAh/g at 0–1 V cutoff voltage condition by alloying process in NaxSn4. The tin-phosphate glass is a promising candidate of new anode active material that realizes high energy density sodium ion batteries.

  9. In-vivo behavior of tin-radiopharmaceuticals

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Tin is an essential ingredient of most technetium-99m radiopharmaceuticals but its in-vivo distribution and long-term fate are not well understood. This work describes distribution in mice of several tin-117m labeled compounds. The results indicate that stannic-HEDTMP appears to be the best overall bone localizing agent with very low blood, muscle, kidney, or liver uptake, and its binding to bone is higher than that of tin-117m-DTPA, which make it potentially useful as an agent for skeletal scintigraphy and radiotherapy of bone tumors.

  10. Mechanical Properties of Glass Surfaces Coated with Tin Oxide

    DEFF Research Database (Denmark)

    Swindlehurst, W. E.; Cantor, B.

    1978-01-01

    of tin tetrachloride on industrial soda glass at ~800K to thicknesses of ~3×10-8 and 3×10 -7 m, commercially by the `titanising' process on industrial soda glass at ~800K to a thickness of ~3.10-9 m, and in the laboratory by radio frequency sputtering from tin oxide powder over a range of glass......The effect of tin oxide coatings on the coefficient of friction and fracture strength of glass surfaces is studied. Experiments were performed partly on commercially treated glass bottles and partly on laboratory prepared microscope slides. Coatings were applied in the laboratory by decomposition...

  11. Diffusion Coefficient of Tin(II) Methanesulfonate in Ionic Liquid and Methane Sulfonic Acid (MSA) Solvent

    Science.gov (United States)

    Yang, Kok Kee; Mahmoudian, M. R.; Ebadi, Mehdi; Koay, Hun Lee; Basirun, Wan Jeffrey

    2011-12-01

    Voltammetry and chronoamperometry for the electrodeposition of tin from Tin(II) methane sulfonate mixed with ionic liquid and methane sulfonate acid at room temperature was studied. Cyclic voltammetry shows redox waves of Tin(II), which proves that the electrodeposition of tin from Tin(II) methane sulfonate is a diffusion-controlled process. The diffusion coefficient of Tin(II) ions in the solvent mixture showed good agreement from both voltammetry and chronoamperometry results. The diffusion coefficient of Tin(II) in the mixture was much smaller than in aqueous solution, and it depends on the anion of the ionic liquid.

  12. Synthesis and Characterization of Tin(IV) Oxide Obtained by Chemical Vapor Deposition Method

    OpenAIRE

    Nagirnyak, Svitlana V.; Lutz, Victoriya A.; Dontsova, Tatiana A.; Astrelin, Igor M.

    2016-01-01

    The effect of precursors on the characteristics of tin oxide obtained by chemical vapor deposition (CVD) method was investigated. The synthesis of nanosized tin(IV) oxide was carried out with the use of two different precursors: tin(II) oxalate obtained using tin chloride(II) and oxalic acid; tin(II) oxalate obtained using tin chloride(II); and ammonium oxalate. The synthesized tin(IV) oxide samples were studied by electron microscopy, X-ray diffraction and optical spectra. The lattice parame...

  13. Tin and Tin Compounds for Sodium Ion Battery Anodes: Phase Transformations and Performance.

    Science.gov (United States)

    Li, Zhi; Ding, Jia; Mitlin, David

    2015-06-16

    Sodium ion batteries (NIB, NAB, SIB) are attracting interest as a potentially lower cost alternative to lithium ion batteries (LIB), with readily available and geographically democratic reserves of the metal. Tin is one of most promising SIB anode materials, which alloys with up to 3.75 Na, leading to a charge storage capacity of 847 mAh g(-1). In this Account, we outline the state-of-the-art understanding regarding the sodiation-induced phase transformations and the associated performance in a range of Sn-based systems, treating metallic Sn and its alloys, tin oxide (SnO2), tin sulfide (SnS2/SnS), and tin phosphide (Sn4P3). We first detail what is known about the sodiation sequence in metallic Sn, highlighting the most recent insight into the reactions prior to the terminal equilibrium Na15Sn4 intermetallic. We explain why researchers argue that the equilibrium (phase diagram) series of phase transitions does not occur in this system, and rather why sodiation/desodiation proceeds through a series of metastable crystalline and amorphous structures. We also outline the recent modeling-based insight regarding how this phase transition profoundly influences the mechanical properties of the alloy, progressively changing the bonding and the near neighbor arrangement from "Sn-like" to "Na-like" in the process. We then go on to discuss the sodiation reactions in SnO2. We argue that while a substantial amount of experimental work already exists where the focus is on synthesis and testing of tin oxide-based nanocomposites, the exact sodiation sequence is just beginning to be understood. Unlike in Sn and Sn alloys, where capacities near the theoretical are reached at least early during cycling, SnO2 never quite achieves anything close to the 1398 mAh g(-1) that would be possible with a combination of fully reversible conversion and alloying reactions. We highlight recent work demonstrating that contrary to general expectations, it is the Sn to Na15Sn4 alloying reaction that

  14. Technical and economic evaluation of emission abatement options of HFC{sub s}, PFC{sub s} and SF{sub 6}. The case of Finland; HFC- ja PFC-yhdisteiden sekae SF6:n paeaestoejen tekniset vaehentaemiskeinot ja niiden kustannukset Suomessa

    Energy Technology Data Exchange (ETDEWEB)

    Oinonen, T.; Soimakallio, S. [VTT Energy, Espoo (Finland). Energy Systems

    2001-07-01

    Emissions of the so called new greenhouse gases - HFC{sub s}, PFC{sub s} and SF6 - are expected to grow globally in the near future. Sources, magnitudes and projections of future emissions differ significantly between countries, mainly due to structural differences between countries' industries, as well as the rate and phase of the substitution of ozone depleting substances by HFC{sub s} and PFC{sub s}. This study focuses on Finnish emissions of the new greenhouse gases, the projected growth in emissions, and the resulting need to reduce these emissions. Currently, emissions of new greenhouse gases amount to some 0.5 Mt of CO{sub 2}-eq. in Finland. Emissions are expected to quadruple by 2010 and to be five-fold by 2020, at which time they represent a much larger share of Finnish emissions of Kyoto greenhouse gases than presently. The substitution of ozone depleting substances by HFC-refrigerants was indentified as a major driver behind the expected growth of emissions. After the first Kyoto commitment period, emissions of HFC-refrigerants were projected to contribute some 90% of the total emissions of new greehouse gases in Finland. The application of emission reduction technologies to an existing equipment base is usually more problematic and less effective than applying these technologies to new equipment. For this reason, the emission reduction potential is conditional on schedule of introducing abatement measures. In the calculations of this study, most of the abatement measures were introduced in 2002. The measures considered consisted mainly of two kinds of technical reduction options: i) alternative gases and technologies and ii) leakage reduction (containment). Measures focusing on application of altenatives were significantly more expensive compared to leakage reduction. Average abatement costs of leakage reduction, weighted by potential emission reductions, were estimated as 80 FIM/t CO{sub 2}-eq. during the first Kyoto commitment period and 60 FIM

  15. High-pressure structure prediction of Hf-C system and first-principle simulation of their electronic prop erties%Hf-C体系的高压结构预测及电子性质第一性原理模拟∗

    Institute of Scientific and Technical Information of China (English)

    彭军辉; 曾庆丰; 谢聪伟; 朱开金; 谭俊华

    2015-01-01

    Hafnium carbides (Hf-C system), known as ultra-high temperature ceramics, have attracted growing attention because of their unique features. In this paper, we carry out researches on the stable crystal structures in the Hf-C system at high pressures, using a variable-composition ab initio evolutionary algorithm implemented in the USPEX code. In addition to the ambient-pressure structures HfC (F m¯3m), there are two new compounds Hf3C2 and Hf6C5 and two high-pressure structures of HfC. When pressures are lower than 100 GPa, no new structures are found other than those at ambient pressure, and Hf3C2 and Hf6C5 become metastable at 20 GPa and 100 GPa, respectively. At 200 GPa, a new compound Hf2C is found, and the stable structure HfC has changed from F m¯3m to C2/m. At 300 GPa, another new compound HfC2 is found. At 400 GPa, the stable structure of HfC has changed again to the space group P nma. And at 500 GPa, the stable structures are Hf2C, HfC2 and HfC (P nma), no new structures are found except those at 400 GPa. The composition-pressure phase diagram that shows the pressure range of stable structures in Hf-C system is simulated by calculation of their enthalpies. When the pressures are lower than 15.5 GPa and 37.7 GPa, Hf3C2 and Hf6C5 are stable, respectively, and their space groups are both of C2/m. And Hf2C and HfC2, with space group I4/m and Immm, respectively become stable structures when the pressure is higher than 102.5 GPa and 215.5 GPa, respectively. The phase-transition route of HfC is F m¯3m → C2/m → P nma, and the two phase-transition pressures are 185.5 GPa and 322 GPa, respectively, which are different from the conclusion of Zhao. Then we will show and discuss the newly predicted high-pressure structures and their crystallographic data, such as volume, lattice constants and atom positions. The crystal structures of HfC are described in the literature. The structure of Hf2C contains 12 atoms in the conventional cell, and carbon atoms lie at the

  16. Nucleate pool boiling heat transfer coefficients of pure HFC134a, H&c, HC600a and their binary and ternary mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Zhaohu; Gong, Maoqiong; Li, Zhijian; Wu, Jianfeng [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing (China)

    2007-01-15

    An experimental test rig for study on the pooling-boiling heat transfer performance of pure and mixed refrigerants were designed and established. With this test system, the heat transfer coefficients (HTCs) of the nucleate boiling on a smooth flat surface were measured for pure fluids of HFC134a, HC290, HC600a and their binary and ternary mixtures. Extensive experimental measures were made for those pure and mixed refrigerants at different heat fluxes from 10kWm{sup -2} to 300kWm{sup -2} and different pressures from 0.2 to 0.6MPa. Comprehensive measured data are presented in this paper. From experimental results, these binary mixtures and ternary mixtures show different heat transfer features according to their vapor-liquid phase equilibria behaviors. New heat transfer correlations were regressed from the measured data with average deviations within +/-15% for pure refrigerants and within +/-20% for mixtures. (author)

  17. High-pressure viscosity behavior of x 1,1,1,2-tetrafluoroethane (HFC-134a)+(1-x) triethylene glycol dimethylether (TriEGDME) mixtures: Measurements and modeling

    DEFF Research Database (Denmark)

    Monsalvo, Matias Alfonso; Baylaucq, A.; Cisneros, Sergio;

    2006-01-01

    In this work new dynamic viscosity measurements for binary mixtures containing a refrigerant (HFC-134a, CF3CH2F) and a lubricant (TriEGDME, CH3O(CH2OCH2)(3)CH3) are reported. The measurements were carried out at temperatures between 293.15 and 373.15 K and pressures from 10 to 100 MPa, for two mo...... with a physical and theoretical background, such as the hard-sphere scheme, the free-volume model, and the friction theory....... for this binary system have been used to test the ability of several viscosity models having different origins and theoretical backgrounds. The considered models range from simple mixing rules, through empirical correlations, such as the self-referencing model and the LBC model, to recent approaches...

  18. Surface tension of molten tin investigated with sessile drop method

    Institute of Scientific and Technical Information of China (English)

    LI Jing; YUAN Zhang-fu; FAN Jian-feng; KE Jia-jun

    2005-01-01

    The surface tension of molten tin was determined by a set of self-developed digital equipment with sessile drop method at oxygen partial pressure of 1.0 × 10-6 MPa under different temperatures, and the dependence of surface tension of molten tin on temperature was also discussed. The emphasis was placed on the comparison of surface tension of the same molten tin sample measured by using different equipments with sessile drop method. Results of the comparison indicate that the measurement results with sessile drop method under the approximate experimental conditions are coincident, and the self-developed digital equipment for surface tension measurement has higher stability and accuracy. The relationships of surface tension of molten tin and its temperature coefficient with temperature and oxygen partial pressure were also elucidated from the thermodynamic equilibrium analysis.

  19. Platinum-Catalyzed Selective Tin-Carbon Bond Formation

    NARCIS (Netherlands)

    Thoonen, Sander Hendrikus Lambertus

    2003-01-01

    In conclusion, two improved methods for the selective synthesis of monoorganotin trihalides were developed. The platinum-catalyzed Kocheshkov redistribution reaction of dialkyltin dichlorides with tin tetrachloride is the most interesting. Contrary to the other two methods described (the direct

  20. Land Elevation TINs (Triangulated Irregular Networks) for Jefferson County, WI

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — The Land Elevation TINs (Triangulated Irregular Networks) in this directory are generated from 2 foot contour lines from Jefferson County. Little is known about the...

  1. Method of manufacturing tin-doped indium oxide nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Ozcan, Soydan; Naskar, Amit K

    2017-06-06

    A method of making indium tin oxide nanofibers includes the step of mixing indium and tin precursor compounds with a binder polymer to form a nanofiber precursor composition. The nanofiber precursor composition is co-formed with a supporting polymer to form a composite nanofiber having a precursor composition nanofiber completely surrounded by the supporting polymer composition. The supporting polymer composition is removed from the composite nanofiber to expose the precursor composition nanofiber. The precursor composition nanofiber is then heated in the presence of oxygen such as O.sub.2 to form indium tin oxide and to remove the binder polymer to form an indium tin oxide nanofiber. A method of making metal oxide nanofibers is also disclosed.

  2. Characterization of tin dioxide nanoparticles synthesized by oxidation

    Directory of Open Access Journals (Sweden)

    R. C. Abruzzi

    2015-09-01

    Full Text Available AbstractTin dioxide (SnO2 is a promising material with great potential for applications such as gas sensors and catalysts. Nanostructures of this oxide exhibit greater activation efficiency given their larger effective surface. The present study presents results of the synthesis and characterization of tin dioxide under different conditions via oxidation of solid tin with nitric oxide. SnO2powder was characterized primarily by X-ray diffraction and scanning electron microscopy, as well as complementary techniques such as energy-dispersive X-ray spectroscopy, dynamic light scattering and Fourier transform infrared spectroscopy. The results indicated that the established synthesis conditions were suitable for obtaining rutile tin dioxide nanoparticles with a tetragonal crystal structure.

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

    Science.gov (United States)

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

    2016-05-01

    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.

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

    Science.gov (United States)

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

    2016-05-05

    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.

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

    Science.gov (United States)

    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).

  6. Predicting crystal structures and physical properties of novel superhard p-BN under pressure via first-principles investigation

    Energy Technology Data Exchange (ETDEWEB)

    Long, Jianping, E-mail: longjianping@cdut.cn [College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China); Shu, Chaozhu [The Mineral Resources Chemistry Key Laboratory of Sichuan Higher Education Institutions, Chengdu University of Technology, Chengdu 610059 (China); Yang, Lijun; Yang, Mei [College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China)

    2015-09-25

    Graphical abstract: The minimum thermal conductivity as a function of pressure for p-BN. - Highlights: • First-principles calculations were carried out to investigate the physical properties of novel superhard p-BN under pressure. • The calculated Vicker’s hardness of p-BN was 55.4 GPa, which indicates that it is a superhard material. • The elastic constants, polycrystalline modulus and Debye temperature under pressure are obtained. • A new modified Clarke-type equation is used to calculate the minimum thermal conductivity. - Abstract: The first-principles calculations were carried out to investigate the electronic structure, elastic, hardness and thermodynamics properties of novel superhard p-BN under pressure. The calculated lattice parameters are in good agreement with previous theoretical results. The band structure, the density of states and the partial density of states are analyzed, which reveals the insulator character of p-BN. In addition, the elastic constants, polycrystalline modulus and Debye temperature under pressure are also successfully obtained. It is observed that the p-BN should be classified as brittle materials and possesses elastically anisotropic. The calculated Vicker’s hardness of p-BN was 55.4 GPa, which indicates that it is a superhard material. According to the calculated polycrystalline modulus, a new modified Clarke-type equation is used to calculate the minimum thermal conductivity. This work provides a useful guide for designing novel borides materials having excellent mechanical performance.

  7. Triangulated Irregular Networks (TIN), TIN raster file obtained from DASC, Published in unknown, 1:24000 (1in=2000ft) scale, Reno County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Triangulated Irregular Networks (TIN) dataset, published at 1:24000 (1in=2000ft) scale as of unknown. It is described as 'TIN raster file obtained from DASC'....

  8. Triangulated Irregular Networks (TIN), Compiled a TIN baed our LIDARD data through ArcGIS tools, Published in unknown, Johnson County AIMS.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Triangulated Irregular Networks (TIN) dataset, was produced all or in part from LIDAR information as of unknown. It is described as 'Compiled a TIN baed our...

  9. Failure Mechanism of Reflow Conductor Roll of Electroplating Tinning Line

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The surface roughness of reflow conductor roll was checked on membrane sample. The surface morphology of conductor roll was observed by microscope, and the composition of adhered layer on conductor roll surface was analyzed by X-ray spectroscope. The results show that tin adhesion is the main reason for failure of conductor roll, and the failure of conductor roll is accelerated by wear. The measures to decrease tin adhesion and improve wear resistance were put forward.

  10. Study on Systemic Separation of Palladium, Silver, Cadmium and Tin

    Institute of Scientific and Technical Information of China (English)

    YU; Zhen-hua; HUANG; Kun

    2013-01-01

    To accurately measure the yields of palladium,silver,cadmium and tin that generated from the fission of plutonium,radiochemical method is needed because there is much interference in using directγ-spectroscopy measurements.Usually,we want to get as much as possible the experiment data from one target,so it is required systemic separation of palladium,silver,cadmium and tin.Considering the

  11. Brassica napus L. Homeodomain Leucine-Zipper Gene BnHB6 Responds to Abiotic and Biotic Stresses

    Institute of Scientific and Technical Information of China (English)

    Shun-Wu YU; Li-Da ZHANG; Kai-Jing ZUO; Dong-Qin TANG; Xiao-Fen SUN; Ke-Xuan TANG

    2005-01-01

    Ahomeodomain leucine-zipper(HD-Zip) gene BnHB6 (GenBank accession No. AY336103) was isolated from oilseed rape (Brassica napus L.) following drought treatment through rapid amplification of cDNA ends (RACE). The full-length cDNA of BnHB6 was 1 611 bp and contained a 936-bp open reading frame encoding 311 amino acids. Sequence analysis indicated that BnHB6 belonged to the HD-Zip I subfamily.High-stringency Southern boltting analysis showed that BnHB6 appeared in rape as a single copy but had homologous genes. Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that BnHB6 was expressed in several tissues tested under control conditions, but that expression was significantly upregulated in shoots by mannitol, NaCl, cold treatment, anaerobic culture, wounding, H2O2, abscisic acid (ABA), and salicylic acid (SA) treatments, but not by ultraviolet treatment. Further RTPCR analysis revealed that BnHB6 was a late-responsive gene, the expression of which was not activated by NaCl, cold treatment, H2O2, ABA, and SA at an early time point (20 min) of treatment in the shoot. However, after a certain period of treatment, the induced expression culminated and then declined until the next peak occurred. Tissue-specific analysis revealed that BnHB6 was expressed at certain levels in the roots, shoots, and flowers, and the roots were found to respond to the osmotic stimuli more rapidly than shoots to increase the expression of BnHB6. The present study implies that BnHB6 plays a positive role as a regulator of biotic and abiotic stresses on growth during seedling establishment.

  12. Vacuum Carbothermal Reduction for Treating Tin Anode Slime

    Science.gov (United States)

    Li, Wei; Guo, Weizhong; Qiu, Keqiang

    2013-11-01

    In this work, a process of vacuum carbothermal reduction was proposed for treating tin anode slime containing antimony and lead. During vacuum carbothermal reduction, the antimony and lead were selectively removed simultaneously by reducing and decomposing the less volatile mixed oxide of lead and antimony into the more volatile Sb2O3 and PbO. Then the tin was enriched in the distilland and primarily present as SnO2. Crude tin was obtained via vacuum reduction of the residual SnO2. The results showed that 92.85% by weight of antimony and 99.58% by weight of lead could be removed at 850°C for 60 min with 4 wt.% of reductant and air flow rate at 400 mL/min corresponding to the residual gas pressure of 40 Pa-150 Pa. Under these conditions, an evaporation ratio of 52.7% was achieved. Crude tin with a tin content of 94.22 wt.% was obtained at temperature of 900°C, reduction time of 60 min, reductant dosage of 12.5 wt.%, and a residual gas pressure of 40 Pa-400 Pa. Correspondingly, the direct recovery of tin was 94.35%.

  13. Ion-assisted sputtering on TiN films

    Energy Technology Data Exchange (ETDEWEB)

    Musil, J.; Kadlec, S. (Inst. of Physics, Czechoslovak Academy of Sciences, Prague (Czechoslovakia)); Valvoda, V.; Kuzel, R. Jr.; Cerny, R. (Dept. of Semiconductor Physics, Charles Univ., Prague (Czechoslovakia))

    1990-12-05

    Ion bombardment of growing films is one of the possible ways to produce films with specific properties. As yet there are no general rules for the production of these films. The quality of TiN films produced depends on the deposition conditions. A sharp transition from porous, black TiN films to compact, dense, bright gold TiN films is observed at a substrate bias U{sub s} of about -40 V. Recent experiments have indicated that the microstructure of TiN films and the transition mentioned above can be controlled by the ion energy delivered to the growing film per deposited particle E{sub p}=eU{sub s}{nu}{sub i}/{nu}{sub m}. This paper investigates the transition from porous, soft TiN films with a zone I microstructure to compact, hard TiN films with a zone T microstructure as a function of i{sub s}, U{sub s} and the deposition rate a{sub D} at constant temperature T{sub s}=350deg C and pressure p{sub T}=5 Pa. Correlations between the microhardness HV, the macrostress, {sigma}, the microstrain, e, the lattice parameters, the intensities of the X-ray reflections and the colour and appearance of the film are discussed. The zone I to zone T transition is observed at E{sub p}{approx equal}150 eV atom{sup -1}. (orig.).

  14. Studies in group IV organometallic chemistry XXX. Synthesis of compounds containing tin---titanium and tin---zirconium bonds

    NARCIS (Netherlands)

    Creemers, H.M.J.C.; Verbeek, F.; Noltes, J.G.

    1968-01-01

    Starting from the tetrakis(diethylamino) derivatives of titanium and zirconium and pheyltin hydrides six intermetalic compounds contianing up to nine tin and titanium(or zirconium) atoms have been obtained by hydrostannolysis type reactions.

  15. Triangulated Irregular Networks (TIN), TIN Bayfield County, Published in 2008, 1:24000 (1in=2000ft) scale, Bayfield County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Triangulated Irregular Networks (TIN) dataset, published at 1:24000 (1in=2000ft) scale, was produced all or in part from Orthoimagery information as of 2008....

  16. Studies in group IV organometallic chemistry XXX. Synthesis of compounds containing tin---titanium and tin---zirconium bonds

    NARCIS (Netherlands)

    Creemers, H.M.J.C.; Verbeek, F.; Noltes, J.G.

    Starting from the tetrakis(diethylamino) derivatives of titanium and zirconium and pheyltin hydrides six intermetalic compounds contianing up to nine tin and titanium(or zirconium) atoms have been obtained by hydrostannolysis type reactions.

  17. BnSIP1-1, a Trihelix Family Gene, Mediates Abiotic Stress Tolerance and ABA Signaling in Brassica napus

    Science.gov (United States)

    Luo, Junling; Tang, Shaohua; Mei, Fengling; Peng, Xiaojue; Li, Jun; Li, Xiaofei; Yan, Xiaohong; Zeng, Xinhua; Liu, Fang; Wu, Yuhua; Wu, Gang

    2017-01-01

    The trihelix family genes have important functions in light-relevant and other developmental processes, but their roles in response to adverse environment are largely unclear. In this study, we identified a new gene, BnSIP1-1, which fell in the SIP1 (6b INTERACTING PROTEIN1) clade of the trihelix family with two trihelix DNA binding domains and a fourth amphipathic α-helix. BnSIP1-1 protein specifically targeted to the nucleus, and its expression can be induced by abscisic acid (ABA) and different stresses. Overexpression of BnSIP1-1 improved seed germination under osmotic pressure, salt, and ABA treatments. Moreover, BnSIP1-1 decreased the susceptibility of transgenic seedlings to osmotic pressure and ABA treatments, whereas there was no difference under salt stress between the transgenic and wild-type seedlings. ABA level in the transgenic seedlings leaves was higher than those in the control plants under normal condition. Under exogenous ABA treatment and mannitol stress, the accumulation of ABA in the transgenic plants was higher than that in the control plants; while under salt stress, the difference of ABA content before treatment was gradually smaller with the prolongation of salt treatment time, then after 24 h of treatment the ABA level was similar in transgenic and wild-type plants. The transcription levels of several general stress marker genes (BnRD29A, BnERD15, and BnLEA1) were higher in the transgenic plants than the wild-type plants, whereas salt-responsive genes (BnSOS1, BnNHX1, and BnHKT) were not significantly different or even reduced compared with the wild-type plants, which indicated that BnSIP1-1 specifically exerted different regulatory mechanisms on the osmotic- and salt-response pathways in seedling period. Overall, these findings suggested that BnSIP1-1 played roles in ABA synthesis and signaling, salt and osmotic stress response. To date, information about the involvement of the Brassica napus trihelix gene in abiotic response is scarce

  18. Formation and Physical Properties of h-BN Atomic Layers: A First-Principles Density-Functional Study

    Directory of Open Access Journals (Sweden)

    Yoshitaka Fujimoto

    2017-01-01

    Full Text Available Hexagonal boron nitride (h-BN atomic layers have attracted much attention as a potential device material for future nanoelectronics, optoelectronics, and spintronics applications. This review aims to describe the recent works of the first-principles density-functional study on h-BN layers. We show physical properties induced by introduction of various kinds of defects in h-BN layers. We further discuss the relationship among the defect size, the strain, and the magnetic as well as the electronic properties.

  19. In-situ epitaxial growth of graphene/h-BN van der Waals heterostructures by molecular beam epitaxy.

    Science.gov (United States)

    Zuo, Zheng; Xu, Zhongguang; Zheng, Renjing; Khanaki, Alireza; Zheng, Jian-Guo; Liu, Jianlin

    2015-10-07

    Van der Waals materials have received a great deal of attention for their exceptional layered structures and exotic properties, which can open up various device applications in nanoelectronics. However, in situ epitaxial growth of dissimilar van der Waals materials remains challenging. Here we demonstrate a solution for fabricating van der Waals heterostructures. Graphene/hexagonal boron nitride (h-BN) heterostructures were synthesized on cobalt substrates by using molecular beam epitaxy. Various characterizations were carried out to evaluate the heterostructures. Wafer-scale heterostructures consisting of single-layer/bilayer graphene and multilayer h-BN were achieved. The mismatch angle between graphene and h-BN is below 1°.

  20. Precipitation in a lead calcium tin anode

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Gonzalez, Francisco A., E-mail: fco.aurelio@inbox.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico); Camurri, Carlos G., E-mail: ccamurri@udec.cl [Departamento de Ingenieria de Materiales, Universidad de Concepcion (Chile); Carrasco, Claudia A., E-mail: ccarrascoc@udec.cl [Departamento de Ingenieria de Materiales, Universidad de Concepcion (Chile); Colas, Rafael, E-mail: rafael.colas@uanl.edu.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico)

    2012-02-15

    Samples from a hot rolled sheet of a tin and calcium bearing lead alloy were solution heat treated at 300 Degree-Sign C and cooled down to room temperature at different rates; these samples were left at room temperature to study natural precipitation of CaSn{sub 3} particles. The samples were aged for 45 days before analysing their microstructure, which was carried out in a scanning electron microscope using secondary and backscattered electron detectors. Selected X-ray spectra analyses were conducted to verify the nature of the precipitates. Images were taken at different magnifications in both modes of observation to locate the precipitates and record their position within the images and calculate the distance between them. Differential scanning calorimeter analyses were conducted on selected samples. It was found that the mechanical properties of the material correlate with the minimum average distance between precipitates, which is related to the average cooling rate from solution heat treatment. - Highlights: Black-Right-Pointing-Pointer The distance between precipitates in a lead alloy is recorded. Black-Right-Pointing-Pointer The relationship between the distance and the cooling rate is established. Black-Right-Pointing-Pointer It is found that the strengthening of the alloy depends on the distance between precipitates.

  1. Tin oxide dependence of the CO2 reduction efficiency on tin electrodes and enhanced activity for tin/tin oxide thin-film catalysts.

    Science.gov (United States)

    Chen, Yihong; Kanan, Matthew W

    2012-02-01

    The importance of tin oxide (SnO(x)) to the efficiency of CO(2) reduction on Sn was evaluated by comparing the activity of Sn electrodes that had been subjected to different pre-electrolysis treatments. In aqueous NaHCO(3) solution saturated with CO(2), a Sn electrode with a native SnO(x) layer exhibited potential-dependent CO(2) reduction activity consistent with previously reported activity. In contrast, an electrode etched to expose fresh Sn(0) surface exhibited higher overall current densities but almost exclusive H(2) evolution over the entire 0.5 V range of potentials examined. Subsequently, a thin-film catalyst was prepared by simultaneous electrodeposition of Sn(0) and SnO(x) on a Ti electrode. This catalyst exhibited up to 8-fold higher partial current density and 4-fold higher faradaic efficiency for CO(2) reduction than a Sn electrode with a native SnO(x) layer. Our results implicate the participation of SnO(x) in the CO(2) reduction pathway on Sn electrodes and suggest that metal/metal oxide composite materials are promising catalysts for sustainable fuel synthesis.

  2. The Influence of Nitrogen and Boron Implant into Silicon Substrate on the Phase and Internal Stress of c-BN Films

    Institute of Scientific and Technical Information of China (English)

    TAN Jun; CAI Zhi-hai; ZHANG Ping

    2004-01-01

    Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously.

  3. Pi and sigma double conjugations in boronyl polyboroene nanoribbons: Bn(BO)2- and Bn(BO)2 (n = 5-12)

    Science.gov (United States)

    Zhai, Hua-Jin; Chen, Qiang; Bai, Hui; Lu, Hai-Gang; Li, Wei-Li; Li, Si-Dian; Wang, Lai-Sheng

    2013-11-01

    A series of boron dioxide clusters, BxO2- (x = 7-14), have been produced and investigated using photoelectron spectroscopy and quantum chemical calculations. The dioxide clusters are shown to possess elongated ladder-like structures with two terminal boronyl (BO) groups, forming an extensive series of boron nanoribbons, Bn(BO)2- (n = 5-12). The electron affinities of Bn(BO)2 exhibit a 4n periodicity, indicating that the rhombic B4 unit is the fundamental building block in the nanoribbons. Both π and σ conjugations are found to be important in the unique bonding patterns of the boron nanoribbons. The π conjugation in these clusters is analogous to the polyenes (aka polyboroenes), while the σ conjugation plays an equally important role in rendering the stability of the nanoribbons. The concept of σ conjugation established here has no analogues in hydrocarbons. Calculations suggest the viability of even larger boronyl polyboroenes, B16(BO)2 and B20(BO)2, extending the boron nanoribbons to ˜1.5 nm in length or possibly even longer. The nanoribbons form a new class of nanowires and may serve as precursors for a variety of boron nanostructures.

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

    Science.gov (United States)

    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

  5. AIS-BN: An Adaptive Importance Sampling Algorithm for Evidential Reasoning in Large Bayesian Networks

    CERN Document Server

    Cheng, J; 10.1613/jair.764

    2011-01-01

    Stochastic sampling algorithms, while an attractive alternative to exact algorithms in very large Bayesian network models, have been observed to perform poorly in evidential reasoning with extremely unlikely evidence. To address this problem, we propose an adaptive importance sampling algorithm, AIS-BN, that shows promising convergence rates even under extreme conditions and seems to outperform the existing sampling algorithms consistently. Three sources of this performance improvement are (1) two heuristics for initialization of the importance function that are based on the theoretical properties of importance sampling in finite-dimensional integrals and the structural advantages of Bayesian networks, (2) a smooth learning method for the importance function, and (3) a dynamic weighting function for combining samples from different stages of the algorithm. We tested the performance of the AIS-BN algorithm along with two state of the art general purpose sampling algorithms, likelihood weighting (Fung and Chang...

  6. Atomistic simulations of pristine and defective hexagonal BN and SiC sheets under uniaxial tension

    Energy Technology Data Exchange (ETDEWEB)

    Le, Minh-Quy, E-mail: quy.leminh@hust.edu.vn [Department of Mechanics of Materials and Structures, School of Mechanical Engineering, Hanoi University of Science and Technology, No. 1, Dai Co Viet Road, Hanoi (Viet Nam); International Institute for Computational Science and Engineering, Hanoi University of Science and Technology, No. 1, Dai Co Viet Road, Hanoi (Viet Nam); Nguyen, Danh-Truong [Department of Mechanics of Materials and Structures, School of Mechanical Engineering, Hanoi University of Science and Technology, No. 1, Dai Co Viet Road, Hanoi (Viet Nam)

    2014-10-06

    The uniaxial tensile mechanical properties of pristine and defective hexagonal boron nitride (BN) and silicon carbide (SiC) sheets are investigated through a molecular dynamics finite element method with Tersoff and Tersoff-like potentials. 2-Atom vacancy and 2 types of Stone–Wales defects are considered. It is found that uniaxial tensile stress–strain curves of defective and pristine sheets are almost identical up to fracture points. A centered single defect reduces significantly fracture stress and fracture strain from those of the corresponding pristine sheet. In contrast, Young's modulus is nearly unchanged by a single defect. One 2-atom vacancy in the sheet's center reduces 15–18% and 16–25% in fracture stress, and 32–34% and 32–48% in fracture strain of BN and SiC sheets, respectively. Reduction in fracture properties depends on the tensile direction as well as the orientation of Stone–Wales defects.

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

    Science.gov (United States)

    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.

  8. Les collections cartographiques numérisées de la BnF

    Directory of Open Access Journals (Sweden)

    Olivier Loiseaux

    2005-04-01

    Full Text Available Depuis 1997 la Bibliothèque nationale de France (BnF propose en accès libre sur son site internet dans la rubrique Gallica de vastes collections de documents numérisés. Les fonds de Gallica, extraits de la vaste bibliothèque numérique de la BnF ont été choisis de manière à constituer une bibliothèque encyclopédique, centrée sur la culture francophone mais également pour permettre la découverte de ressources culturelles par le grand public. Ces fonds numérisés comprennent actuellement 70.000 ouvrages (21 millions de pages, 80.000 images et 500 documents sonores. Parmi les documents iconographiques, on recense entre 3500 et 4000 documents cartographiques.

  9. Ab initio calculations on twisted graphene/hBN: Electronic structure and STM image simulation

    Science.gov (United States)

    Correa, J. D.; Cisternas, E.

    2016-09-01

    By performing ab initio calculations we obtained theoretical scanning tunneling microscopy (STM) images and studied the electronic properties of graphene on a hexagonal boron-nitrite (hBN) layer. Three different stack configurations and four twisted angles were considered. All calculations were performed using density functional theory, including van der Waals interactions as implemented in the SIESTA ab initio package. Our results show that the electronic structure of graphene is preserved, although some small changes are induced by the interaction with the hBN layer, particularly in the total density of states at 1.5 eV under the Fermi level. When layers present a twisted angle, the density of states shows several van Hove singularities under the Fermi level, which are associated to moiré patterns observed in theoretical STM images.

  10. Effect of Si doping on the electronic properties of BN monolayer.

    Science.gov (United States)

    Gupta, Sanjeev K; He, Haiying; Banyai, Douglas; Si, Mingsu; Pandey, Ravindra; Karna, Shashi P

    2014-05-21

    The effect of Si doping on the stability, electronic structure, and electron transport properties of boron nitride (BN) monolayer has been investigated by density functional theory method. Unique features in the electron transport characteristics consisting of a significant enhancement of current at the Si site, diode-like asymmetric current-voltage response, and negative differential resistance are noted for the doped BN monolayer. These features are found to result from new "tunnel" channels induced by the substitutional Si atom near Fermi level in the band gap. The calculated position-projected tunneling currents providing scanning tunneling micrograph clearly discern the site-dependence of the Si atom and can be used to distinguish substitutional sites of atomic dopants in the monolayer.

  11. Tunable light-matter interaction and the role of hyperbolicity in graphene-hBN system

    CERN Document Server

    Kumar, Anshuman; Fung, Kin Hung; Avouris, Phaedon; Fang, Nicholas X

    2015-01-01

    Hexagonal boron nitride (hBN) is a natural hyperbolic material which can also accommodate highly dispersive surface phonon-polariton modes. In this paper, we examine theoretically the mid-infrared optical properties of graphene-hBN heterostructures derived from their coupled plasmon-phonon modes. We found that the graphene plasmon couples differently with the phonons of the two Reststrahlen bands, owing to their different hyperbolicity. This also leads to distinctively different interaction between an external quantum emitter and the plasmon-phonon modes in the two bands, leading to substantial modification of its spectrum. The coupling to graphene plasmons allows for additional gate tunability in the Purcell factor, and narrow dips in its emission spectra.

  12. Temperature dependence of Raman-active phonons and anharmonic interactions in layered hexagonal BN

    Science.gov (United States)

    Cuscó, Ramon; Gil, Bernard; Cassabois, Guillaume; Artús, Luis

    2016-10-01

    We present a Raman scattering study of optical phonons in hexagonal BN for temperatures ranging from 80 to 600 K. The experiments were performed on high-quality, single-crystalline hexagonal BN platelets. The observed temperature dependence of the frequencies and linewidths of both Raman active E2 g optical phonons is analyzed in the framework of anharmonic decay theory, and possible decay channels are discussed in the light of density-functional theory calculations. With increasing temperature, the E2g high mode displays strong anharmonic interactions, with a linewidth increase that indicates an important contribution of four-phonon processes and a marked frequency downshift that can be attributed to a substantial effect of the four-phonon scattering processes (quartic anharmonicity). In contrast, the E2g low mode displays a very narrow linewidth and weak anharmonic interactions, with a frequency downshift that is primarily accounted for by the thermal expansion of the interlayer spacing.

  13. Clifford groups of quantum gates, BN-pairs and smooth cubic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Planat, Michel [Institut FEMTO-ST, CNRS, 32 Avenue de l' Observatoire, F-25044 Besancon (France); Sole, Patrick [CNRS I3S, Les Algorithmes, Euclide B, 2000 route des Lucioles, BP 121, 06903 Sophia Antipolis (France)

    2009-01-30

    The recent proposal (Planat and Kibler 2008 arXiv:0807.3650 [quant-ph]) of representing Clifford quantum gates in terms of unitary reflections is revisited. In this communication, the geometry of a Clifford group G is expressed as a BN-pair, i.e. a pair of subgroups B and N that generate G, is such that intersection H = B intersection N is normal in G, the group W = N/H is a Coxeter group and two extra axioms are satisfied by the double cosets acting on B. The BN-pair used in this decomposition relies on the swap and match gates already introduced for classically simulating quantum circuits (Jozsa and Miyake 2008 arXiv:0804.4050 [quant-ph]). The two- and three-qubit cases are related to the configuration with 27 lines on a smooth cubic surface. (fast track communication)

  14. 2D Heterostructure coatings of hBN-MoS2 layers for corrosion resistance

    Science.gov (United States)

    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.

  15. Energy Bandgap and Edge States in an Epitaxially Grown Graphene/h-BN Heterostructure.

    Science.gov (United States)

    Hwang, Beomyong; Hwang, Jeongwoon; Yoon, Jong Keon; Lim, Sungjun; Kim, Sungmin; Lee, Minjun; Kwon, Jeong Hoon; Baek, Hongwoo; Sung, Dongchul; Kim, Gunn; Hong, Suklyun; Ihm, Jisoon; Stroscio, Joseph A; Kuk, Young

    2016-08-09

    Securing a semiconducting bandgap is essential for applying graphene layers in switching devices. Theoretical studies have suggested a created bulk bandgap in a graphene layer by introducing an asymmetry between the A and B sub-lattice sites. A recent transport measurement demonstrated the presence of a bandgap in a graphene layer where the asymmetry was introduced by placing a graphene layer on a hexagonal boron nitride (h-BN) substrate. Similar bandgap has been observed in graphene layers on metal substrates by local probe measurements; however, this phenomenon has not been observed in graphene layers on a near-insulating substrate. Here, we present bulk bandgap-like features in a graphene layer epitaxially grown on an h-BN substrate using scanning tunneling spectroscopy. We observed edge states at zigzag edges, edge resonances at armchair edges, and bandgap-like features in the bulk.

  16. Energy Bandgap and Edge States in an Epitaxially Grown Graphene/h-BN Heterostructure

    Science.gov (United States)

    Hwang, Beomyong; Hwang, Jeongwoon; Yoon, Jong Keon; Lim, Sungjun; Kim, Sungmin; Lee, Minjun; Kwon, Jeong Hoon; Baek, Hongwoo; Sung, Dongchul; Kim, Gunn; Hong, Suklyun; Ihm, Jisoon; Stroscio, Joseph A.; Kuk, Young

    2016-08-01

    Securing a semiconducting bandgap is essential for applying graphene layers in switching devices. Theoretical studies have suggested a created bulk bandgap in a graphene layer by introducing an asymmetry between the A and B sub-lattice sites. A recent transport measurement demonstrated the presence of a bandgap in a graphene layer where the asymmetry was introduced by placing a graphene layer on a hexagonal boron nitride (h-BN) substrate. Similar bandgap has been observed in graphene layers on metal substrates by local probe measurements; however, this phenomenon has not been observed in graphene layers on a near-insulating substrate. Here, we present bulk bandgap-like features in a graphene layer epitaxially grown on an h-BN substrate using scanning tunneling spectroscopy. We observed edge states at zigzag edges, edge resonances at armchair edges, and bandgap-like features in the bulk.

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

    Directory of Open Access Journals (Sweden)

    Jun Ouyang

    2016-03-01

    Full Text Available 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 have potential applications for boron-nitrogen-carbon-based nanomaterials in spintronics nano-devices.

  18. Formation, structure, and properties of "welded" h-BN/graphene compounds

    Science.gov (United States)

    Chernozatonskii, L. A.; Demin, V. A.; Artyukh, A. A.

    2016-07-01

    Structures of h-BN/graphene with holes where atoms at the edges are bonded to each other by sp 2 hybridized C-B and C-N bonds and form continuous junctions from layer to layer with topological defects inside holes have been considered. Their formation, as well as the moiré-type stable atomic structure of such compounds (with different rotation angles of graphene with respect to the hexagonal boron nitride monolayer) with closed hexagonal holes in the AA centers of packing of the moiré superlattice, has been studied. The stability, as well as the electronic and mechanical properties, of such bilayer BN/graphene nanomeshes has been analyzed within electron density functional theory. It has been shown that they have semiconducting properties. Their electronic band structures and mechanical characteristics differ from the respective properties of separate monolayer nanomeshes with the same geometry and arrangement of holes.

  19. First principles study on defectives BN nanotubes for water splitting and hydrogen storage

    Science.gov (United States)

    Bevilacqua, Andressa C.; Rupp, Caroline J.; Baierle, Rogério J.

    2016-06-01

    First principles calculations within the spin polarized density functional approximation have been addressed to investigate the energetic stability, electronic and optical properties of defective BN nanotubes. Our results show that the presence of carbon impurities interacting with vacancies gives rise to defective electronic levels inside the nanotube band gap. By calculating the absorbance index, we have obtained a strong inter-band optical absorption in the visible region (around 2.1 eV) showing that defective BN nanotubes could be an efficient catalytic semiconductor material to be used within solar energy for water splitting. In addition, we observe that the adsorption energy for one and two H2 molecules on the defective surface is in the desired window for the system to be useful as a hydrogen storage medium.

  20. Tin( ii ) ketoacidoximates: synthesis, X-ray structures and processing to tin( ii ) oxide

    KAUST Repository

    Khanderi, Jayaprakash

    2015-10-21

    Tin(ii) ketoacidoximates of the type [HONCRCOO]Sn (R = Me 1, CHPh 2) and (MeONCMeCOO)Sn] NH·2HO 3 were synthesized by reacting pyruvate- and hydroxyl- or methoxylamine RONH (R = H, Me) with tin(ii) chloride dihydrate SnCl·2HO. The single crystal X-ray structure reveals that the geometry at the Sn atom is trigonal bipyramidal in 1, 2 and trigonal pyramidal in 3. Inter- or intramolecular hydrogen bonding is observed in 1-3. Thermogravimetric (TG) analysis shows that the decomposition of 1-3 to SnO occurs at ca. 160 °C. The evolved gas analysis during TG indicates complete loss of the oximato ligand in one step for 1 whereas a small organic residue is additionally removed at temperatures >400 °C for 2. Above 140 °C, [HONC(Me)COO]Sn (1) decomposes in air to spherical SnO particles of size 10-500 nm. Spin coating of 1 on Si or a glass substrate followed by heating at 200 °C results in a uniform film of SnO. The band gap of the produced SnO film and nanomaterial was determined by diffuse reflectance spectroscopy to be in the range of 3.0-3.3 eV. X-ray photoelectron spectroscopy indicates surface oxidation of the SnO film to SnO in ambient atmosphere.

  1. Role of Plasma Temperature and Residence Time in Stagnation Plasma Synthesis of c-BN Nanopowders

    Science.gov (United States)

    2013-01-01

    critical compressive stress model based off of sub- plantation , which in the energy range of thin film technology, ions loose energy by nuclear...interstitial positions. Lower energy species, however, stick to the outer surface and form sp 2 bonded sites. A thermal spike is seen for a very short ...temperature of 350°C, which produced ~98% c- BN. Uchida et al. 14 used a substrate at room temperature during an IVD process. The substrate was rotated

  2. Preparation and Biological Evaluation of 18F-AlF-NOTA-Bn-c(RGDfK)

    Institute of Scientific and Technical Information of China (English)

    SHI; Cui-yan; JIA; Bing; GUO; Fei-hu; YANG; Yun; CUI; Hai-ping

    2012-01-01

    <正>RGD antagonistie peptide radiolabelled by positron-emitting radionuclides, could be used as a image tracer for tumor diagnosis. The purpose of this research was to synthesis 18F-AlF-NOTA-Bn-c(RGDfK) through one-pot radio-chemical procedure. After that, we investigated the biological evaluation of this conjugate and its imaging feasibility on αvβ3 expressing tumors. The radiochemical purity was measured

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

    Science.gov (United States)

    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.

  4. Structure of TiBN coatings deposited onto cemented carbides and sialon tool ceramics

    OpenAIRE

    L.A. Dobrzański; M. Staszuk; J. Konieczny; W. Kwaśny; M. Pawlyta

    2009-01-01

    Purpose: The aim of this paper was investigated structure of sintered carbides WC-Co type and sialon tool ceramics with wear resistance ternary coatings TiBN type deposited by cathodes arc evaporation process (CAE-PVD).Design/methodology/approach: Observation of fracture and topography studied coatings were done by scanning electron microscope. Chemical composition was determine by energy dispersive spectrometry (EDS) method. Thin foils of substrates and coatings by transmission electron micr...

  5. When Harry met Sally: different approaches towards Uber and AirBnB—an Australian and Singapore perspective

    National Research Council Canada - National Science Library

    Tham, Aaron

    2016-01-01

    .... Two of the main organisations, or disruptors, are AirBnB and Uber. These two organisations were examined and compared in terms of how they have featured within two countries, Australia and Singapore...

  6. Fully dry PMMA transfer of graphene on h-BN using a heating/cooling system

    Science.gov (United States)

    Uwanno, T.; Hattori, Y.; Taniguchi, T.; Watanabe, K.; Nagashio, K.

    2015-12-01

    The key to achieve high-quality van der Waals heterostructure devices made of stacking various two-dimensional (2D) layered materials lies in the clean interface without bubbles and wrinkles. Although polymethylmethacrylate (PMMA) is generally used as a sacrificial transfer film due to its strong adhesion property, it is always dissolved in the solvent after the transfer, resulting in the unavoidable PMMA residue on the top surface. This makes it difficult to locate clean interface areas. In this work, we present a fully dry PMMA transfer of graphene onto h-BN using a heating/cooling system which allows identification of clean interface area for high quality graphene/h-BN heterostructure fabrication. The mechanism lies in the utilization of the large difference in thermal expansion coefficients between polymers (PMMA/PDMS) and inorganic materials (graphene/h-BN substrate) to mechanically peel off PMMA from graphene by the thermal shrinkage of polymers, leaving no PMMA residue on the graphene surface. This method can be applied to all types of 2D layered materials.

  7. The Proper Motions of the Double Radio Source n in the Orion BN/KL Region

    Science.gov (United States)

    Rodríguez, Luis F.; Dzib, Sergio A.; Loinard, Laurent; Zapata, Luis; Gómez, Laura; Menten, Karl M.; Lizano, Susana

    2017-01-01

    We have extended the time baseline for observations of the proper motions of radio sources in the Orion BN/KL region from 14.7 to 22.5 years. We present improved determinations for the sources BN and I. In addition, we address the proper motions of the double radio source n, that have been questioned in the literature. We confirm that all three sources are moving away at transverse velocities of tens of kilometers per second from a region in-between them, where they were located about 500 years ago. Source n exhibits a new component that we interpret as due to a one-sided ejection of free–free emitting plasma that took place after 2006.36. We used the highly accurate relative proper motions between sources BN and I to determine that their closest separation took place in the year 1475 ± 6, when they were within ∼100 au or less from each other in the plane of the sky.

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

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhun; Zhong, Xiaoliang; Yan, Hui; Wang, Ru-Zhi

    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 the 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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Zhou, Yongcun; Liu, Feng

    2016-08-01

    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/PI 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@SiO2/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.

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

    Science.gov (United States)

    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.

  12. Superhydrophobic hBN-Regulated Sponges with Excellent Absorbency Fabricated Using a Green and Facile Method

    Science.gov (United States)

    Zhou, Ying; Wang, Yao; Liu, Tengfei; Xu, Gang; Chen, Guangming; Li, Huayi; Liu, Lichun; Zhuo, Qiqi; Zhang, Jiaoxia; Yan, Chao

    2017-03-01

    The world faces severe environmental, human and ecological problems when major oil spills and organic discharges are released into the environment. And so it is imperative to develop tools and high performance innovative materials that can efficiently absorb these organic discharges. Furthermore, green, facile methods to produce these advanced materials are also needed. In this paper, we demonstrate a novel porous supersponge based on melamine coated with hBN. This superhydrophobic sponge (with a contact angle >150°) exhibits excellent absorption performance for oils and organic solvents, including good selectivity, high capacity (up to 175 g·g-1) and extraordinary recyclability (less than 20% decline after 30 cycles of absorption/squeezing). The synthetic procedure required only ultrasonication and immersion of the sponge in aqueous hBN solution, being a green, cost-effective and scalable production methodology. By virtue of the straightforward and cost-effective fabrication method, along with the excellent absorption performance, hBN-decorated sponges have great promise for real world practical application in the field of oil spills and organic leakage cleanup.

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

    Science.gov (United States)

    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.

  14. Mid-J CO emission from the Orion BN/KL explosive outflow

    CERN Document Server

    Peng, T -C; Wyrowski, F; Güsten, R; Menten, K M; 10.1051/0004-6361/201219937

    2012-01-01

    High spatial resolution low-J 12CO observations have shown that the wide-angle outflow seen in the Orion BN/KL region correlates with the famous H2 fingers. Recently, high-resolution large-scale mappings of mid- and higher-J CO emissions have been reported toward the Orion molecular cloud 1 core region using the APEX telescope. Therefore, it is of interest to investigate this outflow in the higher-J 12CO emission, which is likely excited by shocks. The observations were carried out using the dual-color heterodyne array CHAMP+ on the APEX telescope. The images of the Orion BN/KL region were obtained in the 12CO J=6-5 and J=7-6 transitions with angular resolutions of 8.6 and 7.4 arcsec, respectively. The results show a good agreement between our higher-J 12CO emission and SMA low-J 12CO data, which indicates that this wide-angle outflow in Orion BN/KL is likely the result of an explosive event that is related to the runaway objects from a dynamically decayed multiple system. From our observations, we estimate t...

  15. Superhydrophobic hBN-Regulated Sponges with Excellent Absorbency Fabricated Using a Green and Facile Method

    Science.gov (United States)

    Zhou, Ying; Wang, Yao; Liu, Tengfei; Xu, Gang; Chen, Guangming; Li, Huayi; Liu, Lichun; Zhuo, Qiqi; Zhang, Jiaoxia; Yan, Chao

    2017-01-01

    The world faces severe environmental, human and ecological problems when major oil spills and organic discharges are released into the environment. And so it is imperative to develop tools and high performance innovative materials that can efficiently absorb these organic discharges. Furthermore, green, facile methods to produce these advanced materials are also needed. In this paper, we demonstrate a novel porous supersponge based on melamine coated with hBN. This superhydrophobic sponge (with a contact angle >150°) exhibits excellent absorption performance for oils and organic solvents, including good selectivity, high capacity (up to 175 g·g−1) and extraordinary recyclability (less than 20% decline after 30 cycles of absorption/squeezing). The synthetic procedure required only ultrasonication and immersion of the sponge in aqueous hBN solution, being a green, cost-effective and scalable production methodology. By virtue of the straightforward and cost-effective fabrication method, along with the excellent absorption performance, hBN-decorated sponges have great promise for real world practical application in the field of oil spills and organic leakage cleanup. PMID:28332612

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yongcun; Liu, Feng, E-mail: liufeng@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an Shaanxi 710072 (China)

    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/PI 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.

  17. Over-Expression of BnMAPK1 in Brassica napus Enhances Tolerance to Drought Stress

    Institute of Scientific and Technical Information of China (English)

    WENG Chang-mei; LU Jun-xing; WAN Hua-fang; WANG Shu-wen; WANG Zhen; LU Kun; LIANG Ying

    2014-01-01

    Mitogen-activated protein kinases (MAPKs) are a family of Ser/Thr protein kinases widely conserved in all eukaryotes and involved in responses to biotic and abiotic stresses. In this study, two over-expressing BnMAPK1 oilseed rape lines, ov3 and ov11, were used to study the drought-resistant mechanism of BnMAPK1 under natural drought and simulation drought through spraying 10%PEG 8000 in seedlings. Zhongyou 821 (WT) was used as control. Compared with wild type, transgenic seedlings had higher leaf water content, higher root activity, slightly higher peroxidase (POD) and superoxide dismutase (SOD) activity, higher proline content and lower malondialdehyde (MDA) content. The expression of drought-resistant related genes, including P5CSB, PLC, LEA4 and SCE1, have been up-regulated in some degree and the expressed time of transgenic lines were earlier than that of wild type. These results suggested that over-expression of BnMAPK1 can enhance the resistance to drought in oilseed rape (Brassica napus).

  18. The Proper Motions of the Double Radio Source n in the Orion BN/KL Region

    CERN Document Server

    Rodriguez, Luis F; Loinard, Laurent; Zapata, Luis; Gomez, Laura; Menten, Karl M; Lizano, Susana

    2016-01-01

    We have extended the time baseline for observations of the proper motions of radio sources in the Orion BN/KL region from 14.7 to 22.5 years. We present improved determinations for the sources BN and I. In addition, we address the proper motions of the double radio source n, that have been questioned in the literature. We confirm that all three sources are moving away at transverse velocities of tens of km s$^{-1}$ from a region in-between them, where they were located about 500 years ago. Source n exhibits a new component that we interpret as due to a one-sided ejection of free-free emitting plasma that took place after 2006.36. We used the highly accurate relative proper motions between sources BN and I to determine that their closest separation took place in the year 1475$\\pm$6, when they were within $\\sim$100 AU or less from each other in the plane of the sky.

  19. Investigation of dependence of BN-600 reactor sector fuel cladding leak detection system responses on the operation parameters

    Directory of Open Access Journals (Sweden)

    O.I. Albutova

    2015-12-01

    Implemented studies of dependence of background on the reactor operational parameters are of practical importance and are original scientifically - similar types of research have not been done previously. Upon completion of testing and validation of the developed model using extended volume of reactor operation data the issue will be addressed of the implementation of the methodology within the composition of the SFCLDS of BN-600 and BN-800 reactors.

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

    Science.gov (United States)

    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 MoS2 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 MoS2 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 MoS2/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 MoS2/h-BN is attributed to the decreased effective work function of MoS2 arisen from h-BN induced n-doping and the reduced effective metal work function due to dipole moments originated from fixed charges in SiO2.

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

    Science.gov (United States)

    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.

  2. On-site study of HCFC-22 substitution for HFC non-azeotropic blends (R417A, R422D) on a water chiller of a centralized HVAC system

    Energy Technology Data Exchange (ETDEWEB)

    Torrella, E.; Larumbe, J.A. [Polytechnic University of Valencia, Dep. of Applied Thermodynamics, Camino de Vera 14, E-46022 Valencia (Spain); Cabello, R.; Sanchez, D.; Llopis, R. [Jaume I University, Dep. of Mechanical Engineering and Construction, Campus de Riu Sec s/n, E-12071 Castellon (Spain)

    2010-09-15

    The European Regulation no 2037/2000 has banned manufacturing HCFC refrigerants from January 1st 2010, although its use is allowed up to 2015 if the fluids come from a recycling process. This situation creates the need for developing new working fluids to replace the HCFC in the refrigeration plants now in operation. Among all the HCFCs the R22 is the most widely used in a wide range of applications, especially in air conditioning. This work presents an on-site experimental study of the R22 replacement by two possible substitutes, the HFC-417A and the HFC-422D, in a water chiller in which the energy performance was evaluated. This chiller is part of the centralized HVAC system of a lecture room building at the Jaume I University of Castellon, Spain. This communication compares and analyses main operation parameters of the chiller when operating with each refrigerant in real conditions. (author)

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

    Science.gov (United States)

    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.

  4. Formation of orthorhombic tin dioxide from mechanically milled monoxide powders

    Science.gov (United States)

    Lamelas, F. J.

    2004-12-01

    X-ray scattering measurements are used to show that the metastable orthorhombic phase of tin dioxide is produced by the oxidation of mechanically milled litharge-phase tin monoxide. After milling to a grain size of approximately 20nm, followed by heating to 575°C, the fraction of the orthorhombic phase is approximately 80%. The orthorhombic phase was originally observed in high-pressure experiments, but more recently, it has been produced in a wide variety of thin-film and nanoparticle samples. The data presented here demonstrate the importance of small-grain-size tin monoxide as a precursor in the ambient-pressure synthesis of the orthorhombic phase. This result has practical importance in the production of tin dioxide gas sensors. A more fundamental observation is that the particle size of a precursor phase can have a marked effect on subsequent phases produced during oxidation. Lastly, a formula for determining the orthorhombic fraction in two-phase tin dioxide samples is developed using the method of standard additions.

  5. Influence of Fretting Wear on Lifetime of Tin Plated Connectors

    Science.gov (United States)

    Ikeda, Hirosaka; Ito, Tetsuya; Sawada, Shigeru; Hattori, Yasuhiro; Saitoh, Yasushi; Tamai, Terutaka; Iida, Kazuo

    Due to the recent increase in electronic devices mounted on automobiles, a large number of connectors, especially low-cost tin plated connectors are being used. As a result, their contact reliability has become problematic. Furthermore, for the connectors which are subjected to fretting wear caused by heat cycle and vibrations, the contact resistance increases because of wear of tin and deposition of oxides, which generates problems of poor contact. This study is intended to analyze the change in contact resistance of tin plated connectors from the start of fretting wear to the end of their lifetime from the viewpoint of practical reliability, and to observe the trace and the characteristics of fretting wear microscopically. This study found that wear and oxidation of tin plated connectors start immediately with fretting wear, and thus accumulation of abrasion powder on fretting areas causes connectors to reach to the end of their useful lifetime quickly. Especially, it was demonstrated that amplitude of fretting has a considerable influence on a connector's lifetime. It is made clear that air-tightness, so-called “gas-tight” of tin in a fretting area influences fretting wear considerably.

  6. DEM Based Modeling: Grid or TIN? The Answer Depends

    Science.gov (United States)

    Ogden, F. L.; Moreno, H. A.

    2015-12-01

    The availability of petascale supercomputing power has enabled process-based hydrological simulations on large watersheds and two-way coupling with mesoscale atmospheric models. Of course with increasing watershed scale come corresponding increases in watershed complexity, including wide ranging water management infrastructure and objectives, and ever increasing demands for forcing data. Simulations of large watersheds using grid-based models apply a fixed resolution over the entire watershed. In large watersheds, this means an enormous number of grids, or coarsening of the grid resolution to reduce memory requirements. One alternative to grid-based methods is the triangular irregular network (TIN) approach. TINs provide the flexibility of variable resolution, which allows optimization of computational resources by providing high resolution where necessary and low resolution elsewhere. TINs also increase required effort in model setup, parameter estimation, and coupling with forcing data which are often gridded. This presentation discusses the costs and benefits of the use of TINs compared to grid-based methods, in the context of large watershed simulations within the traditional gridded WRF-HYDRO framework and the new TIN-based ADHydro high performance computing watershed simulator.

  7. Properties of tin oxides prepared by ion-beam-sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Martin; Hamann, Robert; Polity, Angelika; Feili, Davar; Meyer, Bruno K. [I. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 16, 35392 Giessen (Germany)

    2013-07-01

    The success of n-type oxide semiconductors and its application in oxide-based electronic devices has motivated the interest in p-type oxide based semiconductors. Therefore synthesis of tin monoxide (SnO) recently has received increasing attention. Another phase of this binary system, SnO{sub 2}, is of great technological interest in manifold applications, such as transparent electrodes, heat-reflecting filters and gas sensing. The preparation of tin oxide thin films has been performed by many different procedures such as sol/gel, epitaxial procedures or methods working under vacuum conditions like sputtering techniques. Radio-Frequency-Ion-Thrusters, as designed for propulsion applications, are also qualified for thin film deposition and surface etching if utilized as ion source. Tin oxide thin films were grown by ion-beam sputtering using a 3 inch metallic tin target. Different aspects of growth and properties of the tin oxide phases were investigated in relation to growth parameters such as substrate temperature or flux of oxygen. Structural, optical and electrical properties of the films are discussed.

  8. Synthesis, characterization and photoluminescence of tin oxide nanoribbons and nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Duraia, El-Shazly M.A., E-mail: duraia_physics@yahoo.co [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farabi Kazakh National University, Almaty (Kazakhstan); Institute of Physics and Technology, 11 Ibragimov Street, 050032 Almaty (Kazakhstan); Mansorov, Z.A. [Al-Farabi Kazakh National University, Almaty (Kazakhstan); Tokmolden, S. [Institute of Physics and Technology, 11 Ibragimov Street, 050032 Almaty (Kazakhstan)

    2009-11-15

    In this work we report the successful formation of tin oxide nanowires and tin oxide nanoribbons with high yield and by using simple cheap method. We also report the formation of curved nanoribbon, wedge-like tin oxide nanowires and star-like nanowires. The growth mechanism of these structures has been studied. Scanning electron microscope was used in the analysis and the EDX analysis showed that our samples is purely Sn and O with ratio 1:2. X-ray analysis was also used in the characterization of the tin oxide nanowire and showed the high crystallinity of our nanowires. The mechanism of the growth of our1D nanostructures is closely related to the vapor-liquid-solid (VLS) process. The photoluminescence PL measurements for the tin oxide nanowires indicated that there are three stable emission peaks centered at wavelengths 630, 565 and 395 nm. The nature of the transition may be attributed to nanocrystals inside the nanobelts or to Sn or O vacancies occurring during the growth which can induce trapped states in the band gap.

  9. Antimony Doped Tin Oxide Thin Films: Co Gas Sensor

    Directory of Open Access Journals (Sweden)

    P.S. Joshi

    2011-01-01

    Full Text Available Tin dioxide (SnO2 serves as an important base material in a variety of resistive type gas sensors. The widespread applicability of this semicoducting oxide is related both to its range of conductance variability and to the fact that it responds to both oxidising and reducing gases. The antimony doped tin-oxide films were prepared by spray pyrolysis method. The as-deposited films are blackish in colour. Addition of antimony impurity showed little increase in the thickness. The X-ray diffraction pattern shows characteristic tin oxide peaks with tetragonal structure. As the doping concentration of antimony was increased, new peak corresponding to Sb was observed. The intensity of this peak found to be increased when the Sb concentration was increased from 0.01 % to the 1 % which indicates the antimony was incorporated into the tin oxide. For gas sensing studies ohmic contacts were preferred to ensure the changes in resistance of sensor is due to only adsorption of gas molecule. The graph of I-V shows a straight line in nature which indicates the ohmic contact. The sensitivity of the sensor for CO gas was tested. The sensitivity of antimony doped tin oxide found to be increased with increasing Sb concentration. The maximum sensitivity was observed for Sb = 1 % at a working temperature of 250 °C.

  10. Investigation of Surface Phenomena in Shocked Tin in Converging Geometry

    Energy Technology Data Exchange (ETDEWEB)

    Rousculp, Christopher L. [Los Alamos National Laboratory; Oro, David Michael [Los Alamos National Laboratory; Griego, Jeffrey Randall [Los Alamos National Laboratory; Turchi, Peter John [Los Alamos National Laboratory; Reinovsky, Robert Emil [Los Alamos National Laboratory; Bradley, Joseph Thomas [Los Alamos National Laboratory; Cheng, Baolian [Los Alamos National Laboratory; Freeman, Matthew Stouten [Los Alamos National Laboratory; Patten, Austin Randall [Los Alamos National Laboratory

    2016-03-21

    There is great interest in the behavior of the free surface of tin under shock loading. While it is known that meso-scale surface imperfections can seed the Richtmyer- Meshkov Instability (RMI) for a surface that is melted on release, much less is known about a tin surface that is solid, but plastically deforming. Here material properties such as shear and yield strength come into play especially in converging geometry. Previous experiments have been driven by direct contact HE. Usually a thin, flat target coupon is fielded with various single-mode, sinusoidal, machined, profiles on the free surface. The free surface is adjacent to either vacuum or an inert receiver gas. Most of these previous driver/target configurations have been nominal planer geometry. With modern HE it has been straightforward to shock tin into melt on release. However it has been challenging to achieve a low enough pressure for solid state on release. Here we propose to extend the existing base of knowledge to include the behavior of the free surface of tin in cylindrical converging geometry. By shock loading a cylindrical tin shell with a magnetically driven cylindrical liner impactor, the free surface evolution can be diagnosed with proton radiography. With the PHELIX capacitor bank, the drive can easily be varied to span the pressure range to achieve solid, mixed, and liquid states on release. A conceptual cylindrical liner and target is shown in Figure 1.

  11. Investigation of Surface Phenomena in Shocked Tin in Converging Geometry

    Energy Technology Data Exchange (ETDEWEB)

    Rousculp, Christopher L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Oro, David Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Margolin, Len G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Griego, Jeffrey Randall [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reinovsky, Robert Emil [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Turchi, Peter John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-08-06

    There is great interest in the behavior of the free surface of tin under shock loading. While it is known that meso-scale surface imperfections can seed the Richtmyer-Meshkov Instability (RMI) for a surface that is melted on release, much less is known about a tin surface that is solid, but plastically deforming. Here material properties such as shear and yield strength come into play especially in converging geometry. Previous experiments have been driven by direct contact HE. Usually a thin, flat target coupon is fielded with various single-mode, sinusoidal, machined, profiles on the free surface. The free surface is adjacent to either vacuum or an inert receiver gas. Most of these previous driver/target configurations have been nominal planer geometry. With modern HE it has been straightforward to shock tin into melt on release. However it has been challenging to achieve a low enough pressure for solid state on release. Here we propose to extend the existing base of knowledge to include the behavior of the free surface of tin in cylindrical converging geometry. By shock loading a cylindrical tin shell with a magnetically driven cylindrical liner impactor, the free surface evolution can be diagnosed with proton radiography. With the PHELIX capacitor bank, the drive can easily be varied to span the pressure range to achieve solid, mixed, and liquid states on release.

  12. Numerical modeling of the thermal-hydraulic behavior of wire-on-tube condensers operating with HFC-134a using homogeneous equilibrium model: evaluation of some void fraction correlations

    Science.gov (United States)

    Guzella, Matheus dos Santos; Cabezas-Gómez, Luben; da Silva, José Antônio; Maia, Cristiana Brasil; Hanriot, Sérgio de Morais

    2016-02-01

    This study presents a numerical evaluation of the influence of some void fraction correlations over the thermal-hydraulic behavior of wire-on-tube condensers operating with HFC-134a. The numerical model is based on finite volume method considering the homogeneous equilibrium model. Empirical correlations are applied to provide closure relations. Results show that the choice of void fraction correlation influences the refrigerant charge and pressure drop calculations, while no influences the heat transfer rate.

  13. Strategies to Reduce Tin and Other Metals in Electronic Cigarette Aerosol.

    Directory of Open Access Journals (Sweden)

    Monique Williams

    Full Text Available Metals are present in electronic cigarette (EC fluid and aerosol and may present health risks to users.The objective of this study was to measure the amounts of tin, copper, zinc, silver, nickel and chromium in the aerosol from four brands of EC and to identify the sources of these metals by examining the elemental composition of the atomizer components.Four brands of popular EC were dissected and the cartomizers were examined microscopically. Elemental composition of cartomizer components was determined using integrated energy dispersive X-ray microanalysis, and the concentrations of the tin, copper, zinc silver, nickel, and chromium in the aerosol were determined for each brand using inductively coupled plasma optical emission spectroscopy.All filaments were made of nickel and chromium. Thick wires were copper coated with either tin or silver. Wires were joined to each other by tin solder, brazing, or by brass clamps. High concentrations of tin were detected in the aerosol when tin solder joints were friable. Tin coating on copper wires also contributed to tin in the aerosol.Tin concentrations in EC aerosols varied both within and between brands. Tin in aerosol was reduced by coating the thick wire with silver rather than tin, placing stable tin solder joints outside the atomizing chamber, joining wires with brass clamps or by brazing rather than soldering wires. These data demonstrate the feasibility of removing tin and other unwanted metals from EC aerosol by altering designs and using materials of suitable quality.

  14. 在HFC网上使用EPON技术是实现三网融合的最佳方案%In HFC Using FPON Technology is to Realize Online the Convergence of the Optimal Scheme

    Institute of Scientific and Technical Information of China (English)

    高丽

    2011-01-01

    在电信网、广播电视网和互联网三网逐渐融合总趋势下,有线电视HFC网络实现高宽带、高速率、多业务的双向改造问题是一个十分重要而紧迫的任务。通过HFC网络的分析,对EPON的探讨,提出了在HFC升级改造时,搭建EPON无源光网络的必要性和可行性。%In the network and broadcast networks and the Internet three nets fuses gradually under the general trend, CATV HFC network to realize high broadband, high rate, many business problem is a two -way transformation is very important and urgent task. Through the analysis of HFC network, the paper, the author puts forward the EPON in HFC upgraded, build EPON passive optical network of necessity and feasibility.

  15. BN-350 unattended safeguards system current status and initial fuel movement data

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Richard Brady [Los Alamos National Laboratory; Browne, Michael C [Los Alamos National Laboratory; Parker, Robert F [Los Alamos National Laboratory; Ingegneri, Maurizio [IAEA

    2009-01-01

    The Unattended and Remote Monitoring (UNARM) system at the BN-350 fast breeder reactor facility in Aktau, Kazakhstan continues to provide safeguards monitoring data as the spent fuel disposition project transitions from wet fuel storage to dry storage casks. Qualitative data from the initial cask loading procedures has been released by the International Atomic Energy Agency (IAEA) and is presented here for the first time. The BN-350 fast breeder reactor in Aktau, Kazakhstan, operated as a plutonium-producing facility from 1973 W1til 1999. Kazakhstan signed the Nonproliferation Treaty (NPT) in February 1994, and shortly afterwards the IAEA began safeguarding the reactor facility and its nuclear material. Slnce the cessation of reactor operations ten years ago, the chief proliferation concern has been the spent fuel assemblies stored in the pond on-site. By 2002, all fuel assemblies in wet storage had been repackaged into proliferation-resistant canisters. From the beginning, the IAEA's safeguards campaign at the BN-350 included a constant unattended sensor presence in the form of UNARM which monitors nuclear material activities at the facility in the absence of inspector presence. The UNARM equipment at the BN-350 was designed to be modular and extensible, allowing the system to adapt as the safeguards requirements change. This has been particularly important at the BN-350 due to the prolonged wet storage phase of the project. The primary function of the BN-350 UNARM system is to provide the IAEA with an independent, radiation-centric Containment and Surveillance (C&S) layer in addition to the standard seals and video systems. The UNARM system has provided continuous Continuity of Knowledge (COK) data for the BN-350's nuclear material storage areas in order to ensure the validity of the attended measurements during the lifetime of the project. The first of these attended measurements was characterization of the spent fuel assemblies. This characterization

  16. Indium Tin Oxide@Carbon Core–Shell Nanowire and Jagged Indium Tin Oxide Nanowire

    Directory of Open Access Journals (Sweden)

    Wang Yong

    2010-01-01

    Full Text Available Abstract This paper reports two new indium tin oxide (ITO-based nanostructures, namely ITO@carbon core–shell nanowire and jagged ITO nanowire. The ITO@carbon core–shell nanowires (~50 nm in diameter, 1–5 μm in length, were prepared by a chemical vapor deposition process from commercial ITO nanoparticles. A carbon overlayer (~5–10 in thickness was observed around ITO nanowire core, which was in situ formed by the catalytic decomposition of acetylene gas. This carbon overlayer could be easily removed after calcination in air at an elevated temperature of 700°C, thus forming jagged ITO nanowires (~40–45 nm in diameter. The growth mechanisms of ITO@carbon core–shell nanowire and jagged ITO nanowire were also suggested.

  17. Physicochemical characteristics of fluorine doped tin oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, A I [Electronics Department, National Institute for Astrophysics, Optics, and Electronics (INAOE), Luis E Erro No.1, 72000 Tonantzintla, Puebla (Mexico); Huerta, L [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, AP 70-360, 04510 Mexico DF (Mexico); Leon, J M O- Rueda de [Institute of Physics, National Autonomous University of Mexico, 04510 Mexico DF (Mexico); Acosta, D [Institute of Physics, National Autonomous University of Mexico, 04510 Mexico DF (Mexico); Malik, O [Electronics Department, National Institute for Astrophysics, Optics, and Electronics (INAOE), Luis E Erro No.1, 72000 Tonantzintla, Puebla (Mexico); Aguilar, M [Institute of Physics, National Autonomous University of Mexico, 04510 Mexico DF (Mexico)

    2006-12-07

    In this work, relationships between chemical and physical properties of fluorine doped tin oxide films prepared by the chemical spray pyrolysis technique have been studied. Changes in the structural, optical and electrical properties of these films in relation to their doping concentrations determined by the resonant nuclear reaction analysis and x-ray photoelectron spectroscopy (XPS) techniques have been correlated. By XPS measurements, it was found that the fluorine content in the tin oxide films does not induce any chemical shift of the Sn and O core levels. At the same time, XPS measurements are carried out at low binding energy, shown that the valence band of heavy doped tin oxide changes with respect to that determined in SnO{sub 2} powder, due to the influence of the fluorine doping. In addition, it was shown that the formation of F-Sn complexes provides a decrease in both the concentration and mobility of the carriers.

  18. Tin - an unlikely ally for silicon field effect transistors?

    KAUST Repository

    Hussain, Aftab M.

    2014-01-13

    We explore the effectiveness of tin (Sn), by alloying it with silicon, to use SiSn as a channel material to extend the performance of silicon based complementary metal oxide semiconductors. Our density functional theory based simulation shows that incorporation of tin reduces the band gap of Si(Sn). We fabricated our device with SiSn channel material using a low cost and scalable thermal diffusion process of tin into silicon. Our high-κ/metal gate based multi-gate-field-effect-transistors using SiSn as channel material show performance enhancement, which is in accordance with the theoretical analysis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Modified solid electrodes for stripping voltammetric determination of tin

    Energy Technology Data Exchange (ETDEWEB)

    Faller, C. [Kaiserslautern Univ. (Germany). Fachbereich Chemie]|[Univ. Trier (Germany). Abt. Anorganische und Analytische Chemie; Henze, G. [Kaiserslautern Univ. (Germany). Fachbereich Chemie]|[Univ. Trier (Germany). Abt. Anorganische und Analytische Chemie; Stojko, N. [Ural State Economic University, 8th of March Street 62, 620219 Ekaterinburg (Russian Federation); Saraeva, S. [Ural State Economic University, 8th of March Street 62, 620219 Ekaterinburg (Russian Federation); Brainina, K. [Ural State Economic University, 8th of March Street 62, 620219 Ekaterinburg (Russian Federation)

    1997-07-01

    The paper describes the determination of tin by ASV using modified thick film electrodes. Three different types of electrodes were developed: One modified with a mixture of Nafion and mercury(II)acetate, one modified with diethyldithiocarbamate (DDC) or pyrrolidinedithiocarbamate (PDC) and mercury(II)acetate, and one modified with calomel. The analyte was accumulated on the electrode surface after special electrochemical pretreatment of the modified electrode. After recording the voltammogram the electrodes were electrochemically regenerated. By virtue of their lifetime and their measurement reproducibility, we preferred the DDC and PDC modified electrodes. They can be used for months without changing their chemical characteristics. The linear range for tin determination with these electrodes is between 1 and 100 {mu}g/L; the detection limit was calculated as 0.9 {mu}g/L. The electrodes were applied to the direct determination of tin in different canned fruit juices without special sample pretreatment. (orig.). With 10 figs., 4 tabs.

  20. Stabilized tin-oxide-based oxidation/reduction catalysts

    Science.gov (United States)

    Jordan, Jeffrey D. (Inventor); Schryer, David R. (Inventor); Davis, Patricia P. (Inventor); Leighty, Bradley D. (Inventor); Watkins, Anthony Neal (Inventor); Schryer, Jacqueline L. (Inventor); Oglesby, Donald M. (Inventor); Gulati, Suresh T. (Inventor); Summers, Jerry C. (Inventor)

    2008-01-01

    The invention described herein involves a novel approach to the production of oxidation/reduction catalytic systems. The present invention serves to stabilize the tin oxide reducible metal-oxide coating by co-incorporating at least another metal-oxide species, such as zirconium. In one embodiment, a third metal-oxide species is incorporated, selected from the group consisting of cerium, lanthanum, hafnium, and ruthenium. The incorporation of the additional metal oxide components serves to stabilize the active tin-oxide layer in the catalytic process during high-temperature operation in a reducing environment (e.g., automobile exhaust). Moreover, the additional metal oxides are active components due to their oxygen-retention capabilities. Together, these features provide a mechanism to extend the range of operation of the tin-oxide-based catalyst system for automotive applications, while maintaining the existing advantages.

  1. Properties of Polydisperse Tin-doped Dysprosium and Indium Oxides

    Directory of Open Access Journals (Sweden)

    Malinovskaya Tatyana

    2017-01-01

    Full Text Available The results of investigations of the complex permittivity, diffuse-reflectance, and characteristics of crystal lattices of tin-doped indium and dysprosium oxides are presented. Using the methods of spectroscopy and X-ray diffraction analysis, it is shown that doping of indium oxide with tin results in a significant increase of the components of the indium oxide complex permittivity and an appearance of the plasma resonance in its diffuse-reflectance spectra. This indicates the appearance of charge carriers with the concentration of more than 1021 cm−3 in the materials. On the other hand, doping of the dysprosium oxide with the same amount of tin has no effect on its optical and electromagnetic properties.

  2. Recovery of antimony-125 from tin-124 irradiated by neutrons

    Science.gov (United States)

    Baluev, A. V.; Mityakhina, V. S.; Krasnikov, L. V.; Galkin, B. Ya.; Besnosyuk, V. I.

    2003-01-01

    Separation of 125Sb from tin using highly basic, medium-basic, and weakly basic ion-exchangers was studied. The best results were obtained for AN-31 weakly basic anion exchanger. The yield of 125Sb was 95-98% of the initial activity, the yield of tin, 98±0.5% of the initial amount. The separation coefficient is 106-107 for one cycle. A procedure based on ion exchange was developed. Extraction procedures of separation of 125Sb from tin were studied. Isoamyl alcohol, ethyl acetate, and di- n-butyl ether were used as extracting agents. The most efficient extracting agent is di- n-butyl ether. Carrier-free radiochemically pure sample of 125Sb was produced. More than 20 mCi of the target product was recovered. The extraction recovery procedure of 125Sb has been developed.

  3. Tin(II) ketoacidoximates: synthesis, X-ray structures and processing to tin(II) oxide.

    Science.gov (United States)

    Khanderi, Jayaprakash; Davaasuren, Bambar; Alshankiti, Buthainah Ameen; Rothenberger, Alexander

    2015-12-14

    Tin(II) ketoacidoximates of the type [HON=CRCOO]2Sn (R = Me 1, CH2Ph 2) and (MeON=CMeCOO)3Sn](-) NH4(+)·2H2O 3 were synthesized by reacting pyruvate- and hydroxyl- or methoxylamine RONH2 (R = H, Me) with tin(II) chloride dihydrate SnCl2·2H2O. The single crystal X-ray structure reveals that the geometry at the Sn atom is trigonal bipyramidal in 1, 2 and trigonal pyramidal in 3. Inter- or intramolecular hydrogen bonding is observed in 1-3. Thermogravimetric (TG) analysis shows that the decomposition of 1-3 to SnO occurs at ca. 160 °C. The evolved gas analysis during TG indicates complete loss of the oximato ligand in one step for 1 whereas a small organic residue is additionally removed at temperatures >400 °C for 2. Above 140 °C, [HON=C(Me)COO]2Sn (1) decomposes in air to spherical SnO particles of size 10-500 nm. Spin coating of 1 on Si or a glass substrate followed by heating at 200 °C results in a uniform film of SnO. The band gap of the produced SnO film and nanomaterial was determined by diffuse reflectance spectroscopy to be in the range of 3.0-3.3 eV. X-ray photoelectron spectroscopy indicates surface oxidation of the SnO film to SnO2 in ambient atmosphere.

  4. Low-temperature Synthesis of Tin(II) Oxide From Tin(II) ketoacidoximate Precursor

    KAUST Repository

    Alshankiti, Buthainah

    2015-04-01

    Sn (II) oxide finds numerous applications in different fields such as thin film transistors1, solar cells2 and sensors.3 In this study we present the fabrication of tin monoxide SnO by using Sn (II) ketoacid oximate complexes as precursors. Tin (II) ketoacidoximates of the type [HON=CRCOO]2Sn where R= Me 1, R= CH2Ph 2, and [(MeON=CMeCOO)3Sn]- NH4 +.2H2O 3 were synthesized by in situ formation of the ketoacid oximate ligand. The crystal structures were determined via single crystal X- ray diffraction of the complexes 1-3 revealed square planar and square pyramidal coordination environments for the Sn atom. Intramolecular hydrogen bonding is observed in all the complexes. Furthermore, the complexes were characterized by Infrared (IR), Nuclear Magnetic Resonance (NMR) and elemental analysis. From thermogravimetric analysis of 1-3, it was found that the complexes decomposed in the range of 160 – 165 oC. Analysis of the gases evolved during decomposition indicated complete loss of the oximato ligand in one step and the formation of SnO. Spin coating of 1 on silicon or glass substrate show uniform coating of SnO. Band gaps of SnO films were measured and found to be in the range of 3.0 – 3.3 eV by UV-Vis spectroscopy. X-ray photoelectron spectroscopy indicated surface oxidation of the SnO film. Heating 1 above 140 oC in air gives SnO of size ranging from 10 – 500 nm and is spherical in shape. The SnO nanomaterial is characterized by powder X-ray diffraction(XRD), Raman spectroscopy, Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM).

  5. Electrical Properties of Electrospun Sb-Doped Tin Oxide Nanofibers

    Science.gov (United States)

    León-Brito, Neliza; Melendez, Anamaris; Ramos, Idalia; Pinto, Nicholas J.; Santiago-Aviles, Jorge J.

    2007-03-01

    Transparent and conducting tin oxide fibers are of considerable interest for solar energy conversion, sensors and in various electrode applications. Appropriate doping can further enhance the conductivity of the fibers without loosing optical transparency. Undoped and antimony-doped tin oxide fibers have been synthesized by our group in previous work using electrospinning and metallorganic decomposition techniques. The undoped tin oxide fibers were obtained using a mixture of pure tin oxide sol made from tin (IV) chloride : water : propanol : isopropanol at a molar ratio of 1:9:9:6, and a viscous solution made from poly(ethylene oxide) (PEO) and chloroform at a ratio of 200 mg PEO/10 mL chloroform. In this work, antimony doped fibers were obtained by adding a dopant solution of antimony trichloride and isopropanol at a ratio of 2.2812 g antimony trichloride/10 ml isopropanol to the original tin oxide precursor solution. The Sb concentration in the precursor solution is 1.5%. After deposition, the fibers were sintered 600°C in air for two hours. The electrical conductivity of single fibers measured at room temperature increases by up to three orders of magnitude when compared to undoped fibers prepared using the same method. The resistivity change as a function of the annealing temperature can be attributed to the thermally activated formation of a nearly stoichoimetric solid. The resistivity of the fibers changes monotonically with temperature from 714Ω-cm at 2 K to 0.1Ω-cm at 300 K. In the temperature range from 2 to 8 K the fibers have a positive magnetoresistance (MR) with the highest value of 155 % at 2 K and ±9 T. At temperatures of 10 and 12 K the sign of MR changes to negative values for low magnetic fields and positive for high magnetic fields. For higher temperatures (15 K and above) the MR becomes negative and its magnitude decreases with temperature.

  6. Charge transport in a single superconducting tin nanowire encapsulated in a multiwalled carbon nanotube

    NARCIS (Netherlands)

    Tombros, Nikolaos; Buit, Luuk; Arfaoui, Imad; Tsoufis, Theodoros; Gournis, Dimitrios; Trikalitis, Pantelis N.; van der Molen, Sense Jan; Rudolf, Petra; van Wees, Bart J.

    2008-01-01

    The charge transport properties of single superconducting tin nanowires encapsulated by multiwalled carbon nanotubes have been investigated by multiprobe measurements. The multiwalled carbon nanotube protects the tin nanowire from oxidation and shape fragmentation and therefore allows us to investig

  7. Transition metal catalysed Grignard-like allylic activation across tetragonal tin(II) oxide

    Indian Academy of Sciences (India)

    Pradipta Sinha; Moloy Banerjee; Abhijit Kundu; Sujit Roy

    2002-08-01

    The reaction of allyl halide and a carbonyl compound under the aegis of tetragonal tin(II) oxide and catalytic 8, 10 metal complexes provides the corresponding homoallylic alcohol, via a novel allyl tin intermediate.

  8. Design features of internal tin superconductors for ITER magnetic system

    Energy Technology Data Exchange (ETDEWEB)

    Pantsyrnyi, V.I.; Shikov, A.K.; Nikulin, A.D.; Silaev, A.G.; Bel`akov, N.A.; Vdovin, V.F.; Semin, M.J. [Bochvar All-Russia Inst. of Inorganic Materials, Moscow (Russian Federation)

    1996-07-01

    The influence of parameters of internal tin superconductor design on the main working characteristics such as critical current density and hysteresis losses were analyzed. It was shown that having the value of hysteresis losses at the acceptable level of 400--600 mJ/cm{sup 3} the critical current density 20--30% higher than the value typical for bronze route processed superconductors was attainable in principle. The results of experimental work on the design of new types of internal tin superconductors for ITER magnetic system are given.

  9. The first barium tin(II) bromide fluoride

    Science.gov (United States)

    Dénès, Georges; Merazig, Hocine; Muntasar, Abdualhafeed; Porterfield, Robyn

    2014-04-01

    In an effort to prepare barium tin(II) bromide fluorides for the first time, possibly similar to the chloride fluorides obtained earlier in our laboratory, precipitation reactions were carried out by mixing aqueous solutions of SnF2 and of BaBr2.2H2O. In contrast with the chloride fluoride system, a single powdered phase was obtained throughout the SnF2 - BaBr2 system, with the yield being maximum at X ≈ 0.25, where X is the molar fraction of barium bromide in the reaction mixture. Phase identification with the JCPDS database failed to produce a match, confirming that a new phase had been produced. The exact chemical composition of the new compound has not been obtained yet. Based on the X value for the maximum yield, the Sn/Ba ratio is likely to be 3/1 or 2/1. The Mössbauer spectrum at ambient conditions shows that bonding to tin(II) is covalent, therefore with the tin lone pair being stereoactive. The Mössbauer parameters ( δ = 3.68 mm/s, Δ = 0.99 mm/s) are similar to those of SnBrF and of Sn2BrF5, thereby showing that tin is bonded to both fluorine and bromine. The larger isomer shift and lower quadrupole splitting than in tin(II) fluorides show that the stereoactivity of the tin lone pair is lower than in the fluorides. The Mössbauer parameters fit well the linear correlation of the quadrupole splitting versus the isomer shift" that has been shown to be present in other series of tin(II) compounds. The linear decrease on this correlation shows that the contribution of non-spherical orbitals ( p and d) to the lone pair is a much larger contributor to the quadrupole splitting than lattice distortions. The structure is likely made of Ba2+ cations and tin(II) fluoride bromide polyatomic anions, with covalent bonding withinthe anions.

  10. An Empirical Model for Estimating the Probability of Electrical Short Circuits from Tin Whiskers. Part 2

    Science.gov (United States)

    Courey, Karim; Wright, Clara; Asfour, Shihab; Onar, Arzu; Bayliss, Jon; Ludwig, Larry

    2009-01-01

    In this experiment, an empirical model to quantify the probability of occurrence of an electrical short circuit from tin whiskers as a function of voltage was developed. This empirical model can be used to improve existing risk simulation models. FIB and TEM images of a tin whisker confirm the rare polycrystalline structure on one of the three whiskers studied. FIB cross-section of the card guides verified that the tin finish was bright tin.

  11. Mixed europium valence in Eu0.937Ba8[BN2]6 - Structure and spectroscopic behavior

    Science.gov (United States)

    Dierkes, Tobias; Seidel, Stefan; Benndorf, Christopher; Heletta, Lukas; de Oliveira Junior, Marcos; Holtkamp, Michael; Karst, Uwe; Block, Theresa; Jüstel, Thomas; Eckert, Hellmut; Pöttgen, Rainer

    2017-08-01

    Polycrystalline samples of Sr0.95Eu0.05Ba8[BN2]6 and Eu0.937Ba8[BN2]6 were synthesized via conventional solid-state reaction from the binary precursor compounds Sr3N2, EuN, Ba3N2 and BN at 1000 °C. The structure of Eu0.937Ba8[BN2]6 was refined from single crystal X-ray diffractometer data: Eu0.937Ba8[BN2]6 type, Fd 3 barm, a = 1594.54(9) pm, wR2 = 0.0654, 380 F2 values and 23 variables. The 8a europium site shows an occupancy of only 93.7(9) % suggesting partial oxidation of europium to fulfil an electron-precise description, i. e. EuII0.81EuIII0.13Ba8[BN2]6. The mixed europium valence was confirmed by magnetic susceptibility measurements (reduced magnetic moment of 7.28 μB per europium atom) and 151Eu Mössbauer spectroscopy (EuII: EuIII = 82: 18). The nitridoborate anions are coordinated by slightly distorted, mono-capped (europium) square prisms formed by the barium atoms. All metal cations are hexa-coordinated by nitrogen atoms. The EPR spectra of EuxSr1-xBa8[BN2]6 samples (0.001 ≤ x ≤ 0.01) suggest close to cubic local symmetry of the Eu2+ dopant ions and reveal some highly unusual features: Magnetic hyperfine splitting is only observed with one of the Eu nuclear isotopes, and the coupling constant of 243.6 MHz is extremely large compared to values (90-100 MHz) typically observed in the literature for Eu2+ doped crystalline materials.

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

    Energy Technology Data Exchange (ETDEWEB)

    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) prevented 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.

  13. NASA Goddard Space Flight Center Tin Whisker (and Other Metal Whisker) Homepage

    Science.gov (United States)

    Brusse, Jay; Sampson, Mike; Leidecker, Henning; Kadesch, Jong

    2004-01-01

    This website provides information about tin whiskers and related research. The independent research performed during the past 50+ years is so vast that it is impractical to cover all aspects of tin whiskers in this one resource. Therefore, the absence of information in this website about a particular aspect of tin whiskers should NOT be construed as evidence of absence.

  14. NASA Goddard Space Flight Center Tin Whisker (and Other Metal Whisker) Homepage

    Science.gov (United States)

    Brusse, Jay; Sampson, Mike; Leidecker, Henning; Kadesch, Jong

    2004-01-01

    This website provides information about tin whiskers and related research. The independent research performed during the past 50+ years is so vast that it is impractical to cover all aspects of tin whiskers in this one resource. Therefore, the absence of information in this website about a particular aspect of tin whiskers should NOT be construed as evidence of absence.

  15. Thermal and plasma-enhanced oxidation of ALD TiN

    NARCIS (Netherlands)

    Groenland, A.W.; Brunets, I.; Boogaard, A.; Aarnink, A.A.I.; Kovalgin, A.Y.; Schmitz, J.

    2008-01-01

    Despite its high chemical stability, sputtered stoichiometric TiN can still be oxidized at temperatures below 400 ºC, whereas a non-stoichiometric TiN is known to oxidize even at room temperature. In this work, the oxidation behaviour of thin TiN layers, realized via atomic layer deposition (ALD), i

  16. Telomere dysfunction and cell survival: roles for distinctTIN2-containing complexes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sahn-Ho; Davalos, Albert R.; Heo, Seok-Jin; Rodier, Francis; Beausejour, Christian; Kaminker, Patrick; Campisi, Judith

    2006-11-07

    Telomeres are maintained by three DNA binding proteins, TRF1, TRF2 and POT1, and several associated factors. One factor, TIN2, binds TRF1 and TRF2 directly and POT1 indirectly. These and two other proteins form a soluble complex that may be the core telomere-maintenance complex. It is not clear whether subcomplexes exist or function in vivo. Here, we provide evidence for two TIN2 subcomplexes with distinct functions in human cells. TIN2 ablation by RNA interference caused telomere uncapping and p53-independent cell death in all cells tested. However, we isolated two TIN2 complexes from cell lysates, each selectively sensitive to a TIN2 mutant (TIN2-13, TIN2-15C). In cells with wild-type p53 function, TIN2-15C was more potent than TIN2-13 in causing telomere uncapping and eventual growth arrest. In cells lacking p53 function, TIN215C more than TIN2-13 caused genomic instability and cell death. Thus, TIN2 subcomplexes likely have distinct functions in telomere maintenance, and may provide selective targets for eliminating cells with mutant p53.

  17. Telomere dysfunction and cell survival: Roles for distinct TIN2-containing complexes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sahn-ho; Davalos, Albert R.; Heo, Seok-Jin; Rodier, Francis; Zou, Ying; Beausejour, Christian; Kaminker, Patrick; Yannone, Steven M.; Campisi, Judith

    2007-10-02

    Telomeres are maintained by three DNA binding proteins (TRF1, TRF2 and POT1), and several associated factors. One factor, TIN2, binds TRF1 and TRF2 directly and POT1 indirectly. Along with two other proteins, TPP1 and hRap1, these form a soluble complex that may be the core telomere maintenance complex. It is not clear whether sub-complexes also exist in vivo. We provide evidence for two TIN2 sub-complexes with distinct functions in human cells. We isolated these two TIN2 sub-complexes from nuclear lysates of unperturbed cells and cells expressing TIN2 mutants TIN2-13, TIN2-15C, which cannot bind TRF2 or TRF1, respectively. In cells with wild-type p53 function, TIN2-15C was more potent than TIN2-13 in causing telomere uncapping and eventual growth arrest. In cells lacking p53 function, TIN2-15C was more potent than TIN2-13 in causing telomere dysfunction and cell death. Our findings suggest that distinct TIN2 complexes exist, and that TIN2-15C-sensitive subcomplexes are particularly important for cell survival in the absence of functional p53.

  18. 40 CFR 721.10140 - Phosphoric acid, tin (2+) salt (2:3).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Phosphoric acid, tin (2+) salt (2:3... Specific Chemical Substances § 721.10140 Phosphoric acid, tin (2+) salt (2:3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as phosphoric acid, tin...

  19. 77 FR 5767 - Certain Tin Mill Products From Japan: Rescission of Antidumping Duty Administrative Review

    Science.gov (United States)

    2012-02-06

    ... International Trade Administration Certain Tin Mill Products From Japan: Rescission of Antidumping Duty...) initiated an administrative review of the antidumping duty order covering certain tin mill products from... antidumping duty order on certain tin mill products from Japan. See Antidumping or Countervailing Duty...

  20. 77 FR 34938 - Certain Tin Mill Products From Japan: Continuation of Antidumping Duty Order

    Science.gov (United States)

    2012-06-12

    ... International Trade Administration Certain Tin Mill Products From Japan: Continuation of Antidumping Duty Order... Trade Commission (USITC) that revocation of the antidumping duty order on certain tin mill products from... Department published the antidumping duty order on certain tin mill products from Japan.\\1\\ On June 1,...

  1. Criticality safety issues in the disposition of BN-350 spent fuel

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, R. W.; Klann, R. T.; Koltyshev, S. M.; Krechetov, S.

    2000-02-28

    A criticality safety analysis has been performed as part of the BN-350 spent fuel disposition project being conducted jointly by the DOE and Kazakhstan. The Kazakhstan regulations are reasonably consistent with those of the DOE. The high enrichment and severe undermoderation of this fast reactor fuel has significant criticality safety consequences. A detailed modeling approach was used that showed some configurations to be safe that otherwise would be rejected. Reasonable requirements for design and operations were needed, and with them, all operations were found to be safe.

  2. Nanopillar optical antenna nBn detectors for subwavelength infrared pixels

    Science.gov (United States)

    Hung, Chung Hong; Senanayake, Pradeep; Lee, Wook-Jae; Farrell, Alan; Hsieh, Nick; Huffaker, Diana L.

    2015-06-01

    The size, weight and power (SWaP) of state of the art infrared focal plane arrays are limited by the pixel size approaching the diffraction limit. We investigate a novel detector architecture which allows improvements in detectivity by shrinking the absorber volume while maintaining high quantum efficiency and wide field of view (FOV). It has been previously shown that the Nanopillar Optical Antenna (NOA) utilizes 3D plasmonic modes to funnel light into a subwavelength nanopillar absorber. We show detailed electro-optical simulations for the NOA-nBn architecture for overcoming generation recombination current with suitable surface passivation to achieve background limited infrared performance.

  3. Mechanical and Thermal Properties of Polymethyl Methacrylate-BN Nanotube Composites

    Directory of Open Access Journals (Sweden)

    C. Y. Zhi

    2008-01-01

    Full Text Available Polymethyl methacrylate (PMMA-BN nanotube (BNNT composites were fabricated and their mechanical and thermal properties were analyzed. Using a 1 wt.% BNNTs fraction in a polymer, the elastic modulus of PMMA was increased up to 19%. In addition, thermal stability and glass transition temperature of PMMA were also positively affected. The thermal conductivity of PMMA with BNNT additions increased three times. The resultant BNNT-PMMA composites possess the high electrical breakover voltages. Thus our studies clearly indicate that BNNTs are promising nanofillers for improvement of mechanical and thermal conductivity of dielectric polymers under preservation of their electrical insulation.

  4. Effect of Adventitious Carbon on the Environmental Degradation of SiC/BN/SiC Composites

    Science.gov (United States)

    Ogbuji, L. U. J. T.; Yun, H. M.; DiCarlo, J.

    2002-01-01

    Pesting remains a major obstacle to the application of SiC/SiC composites in engine service and selective degradation of the boron nitride interphase at intermediate temperatures is of primary concern. However, significant progress has been made on interphase improvement recently and we now know more about the phenomenon and ways to suppress it. By screening SiC/BN/SiC materials through characterization of strength and microstructures after exposure in a burner rig, some factors that control pesting in these composites have been determined. A key precaution is careful control of elemental carbon presence in the interphase region.

  5. Vacuolar Iron Transporter BnMEB2 Is Involved in Enhancing Iron Tolerance of Brassica napus

    OpenAIRE

    Zhu, Wei; Zuo, Rong; Zhou, Rongfang; Huang, Junyan; Tang, Minqiang; Cheng, Xiaohui; Liu, Yueying; Tong, Chaobo; XIANG, YANG; Dong, Caihua; Liu, Shengyi

    2016-01-01

    Iron toxicity is a nutrient disorder that severely affects crop development and yield in some soil conditions. Vacuolar detoxification of metal stress is an important strategy for plants to survive and adapt to this adverse environment. Vacuolar iron transporter (VIT) members are involved in this process and play essential roles in iron storage and transport. In this study, we identified a rapeseed VIT gene BnMEB2 (BnaC07g30170D) homologs to Arabidopsis MEB2 (At5g24290). Transient expression ...

  6. Elastic and thermodynamic properties of c-BN from first-principles calculations

    Institute of Scientific and Technical Information of China (English)

    Hao Yan-Jun; Cheng Yan; Wang Yan-Ju; Chen Xiang-Rong

    2007-01-01

    The elastic constants and thermodynamic properties of c-BN are calculated using the first-principles plane wave method with the relativistic analytic pseudopotential of the Hartwigen, Goedecker and Hutter (HGH) type in the frame of local density approximation and using the quasi-harmonic Debye model, separately. Moreover, the dependences of the normalized volume V/V0 on pressure P, as well as the bulk modulus B, the thermal expansion α, and the heat capacity CV on pressure P and temperature T are also successfully obtained.

  7. First-Principles Investigations of the Working Mechanism of 2D h-BN as an Interfacial Layer for the Anode of Lithium Metal Batteries.

    Science.gov (United States)

    Shi, Le; Xu, Ao; Zhao, Tianshou

    2017-01-18

    An issue with the use of metallic lithium as an anode material for lithium-based batteries is dendrite growth, causing a periodic breaking and repair of the solid electrolyte interphase (SEI) layer. Adding 2D atomic crystals, such as h-BN, as an interfacial layer between the lithium metal anode and liquid electrolyte has been demonstrated to be effective to mitigate dendrite growth, thereby enhancing the Columbic efficiency of lithium metal batteries. But the underlying mechanism leading to the reduced dendrite growth remains unknown. In this work, with the aid of first-principle calculations, we find that the interaction between the h-BN and lithium metal layers is a weak van der Waals force, and two atomic layers of h-BN are thick enough to block the electron tunneling from lithium metal to electrolyte, thus prohibiting the decomposition of electrolyte. The interlayer spacing between the h-BN and lithium metal layers can provide larger adsorption energies toward lithium atoms than that provided by bare lithium or h-BN, making lithium atoms prefer to intercalate under the cover of h-BN during the plating process. The combined high stiffness of h-BN and the low diffusion energy barriers of lithium at the Li/h-BN interfaces induce a uniform distribution of lithium under h-BN, therefore effectively suppressing dendrite growth.

  8. High mobility tin oxide deposition with methanol addition

    NARCIS (Netherlands)

    Deelen, J. van; Volintiru, I.; Graaf, A. de; Poodt, P.W.G.

    2011-01-01

    SnO 2 coated glass is widely used in thin film PV. Atmospheric pressure chemical vapor deposition (APCVD) is the most common method of deposition and apart from a tin precursor and oxygen precursor, other additives can improve the layer quality. In this contribution, the beneficial effect of methano

  9. Geochemistry of the Panasqueira tungsten-tin deposit, Portugal

    NARCIS (Netherlands)

    Bussink, R.W.

    1984-01-01

    Major tin-tungsten deposits in Portugal are related to intrusions of the Younger Series (300-280 Ma) of Hercynian granitoids. Mineralized granites are 'specialized' by a specific increase or decrease of major, minor and trace element contents in comparison with non-mineralized occurrences. Component

  10. Geochemistry of the Panasqueira tungsten-tin deposit, Portugal

    NARCIS (Netherlands)

    Bussink, R.W.

    1984-01-01

    Major tin-tungsten deposits in Portugal are related to intrusions of the Younger Series (300-280 Ma) of Hercynian granitoids. Mineralized granites are 'specialized' by a specific increase or decrease of major, minor and trace element contents in comparison with non-mineralized occurrences.

  11. Electronegativity-dependent tin etching from thin films

    NARCIS (Netherlands)

    Pachecka, M.; Sturm, J.M.; Kruijs, van de R.W.E.; Lee, C.J.; Bijkerk, F.

    2016-01-01

    The influence of a thin film substrate material on the etching of a thin layer of deposited tin (Sn) by hydrogen radicals was studied. The amount of remaining Sn was quantified for materials that cover a range of electronegativities. We show that, for metals, etching depends on the relative electron

  12. Geochemistry of the Panasqueira tungsten-tin deposit, Portugal

    NARCIS (Netherlands)

    Bussink, R.W.

    1984-01-01

    Major tin-tungsten deposits in Portugal are related to intrusions of the Younger Series (300-280 Ma) of Hercynian granitoids. Mineralized granites are 'specialized' by a specific increase or decrease of major, minor and trace element contents in comparison with non-mineralized occurrences. Component

  13. On the low-lying states of TiN

    Science.gov (United States)

    Bauschlicher, C. W., Jr.

    1983-01-01

    A series of CAS SCF and multi-reference CI calculations are used to describe the lowest states of TiN. The bonding in all states is described as a triple bond involving the Ti 3d orbitals. The system has some ionic character as seen from both population analysis and dipole moment. The origins of the excited states are discussed.

  14. One Step Internal Tin Nb3Sn Superconductor Fabrication.

    Science.gov (United States)

    1985-03-01

    34" TABLE. OF CONTENTS SECTION PAGE I INTRODUCTION 1 11 TIN PLATING LINEI III RIBBON FABRICATION2 IV EXTRUSION2 V WIRE DRAWING VI HEAT TREATMENT VII...8217 "> >; i ; ,’’ \\>,/ ; -2 ; "--; i > . . .? :-. -. -. .-.- - .. . - I" SECTION V WIRE DRAWING The extruded rod was cut into approximately 15 cm long pieces

  15. A CityGML Extension for Handling Very Large Tins

    Science.gov (United States)

    Kumar, K.; Ledoux, H.; Stoter, J.

    2016-10-01

    In addition to buildings, the terrain forms an important part of a 3D city model. Although in GIS terrains are usually represented with 2D grids, TINs are also increasingly being used in practice. One example is 3DTOP10NL, the 3D city model covering the whole of the Netherlands, which stores the relief with a constrained TIN containing more than 1 billion triangles. Due to the massive size of such datasets, the main problem that arises is: how to efficiently store and maintain them? While CityGML supports the storage of TINs, we argue in this paper that the current solution is not adequate. For instance, the 1 billion+ triangles of 3DTOP10NL require 686 GB of storage space with CityGML. Furthermore, the current solution does not store the topological relationships of the triangles, and also there are no clear mechanisms to handle several LODs. We propose in this paper a CityGML extension for the compact representation of terrains. We describe our abstract and implementation specifications (modelled in UML), and our prototype implementation to convert TINs to our CityGML structure. It increases the topological relationships that are explicitly represented, and allows us to compress up to a factor of ∼ 25 in our experiments with massive real-world terrains (more than 1 billion triangles).

  16. Geology,Geochemistry and Genesis of Yinyan Porphyry Tin Deposit

    Institute of Scientific and Technical Information of China (English)

    朱正书; 朱金初; 等

    1989-01-01

    The Yinyan porphyry tin deposit is a blind deposit associated with a small granite porphyry stock.The petrology and geochemistry of the Yinyan granite porphyry suggest that it is genetically of the transfor-mation type,emplaced at the late stage of fractional crystallization within a high-level magma chamber.Ore-forming fluids are derived predominantly from the granitic magma and they interact with the wall rocks intensely when finding their way upwards through the granite porphyry.From the lower part of the porphyry upwards the following alteration zones can be distinguished(a)slightly altered granite porphyry (with weak potash feldspathization),(b)protolithionite-quartz greisenization zone,(c)to-paz-quartz greisenization zone,(d)senicite-quartz sericitization zone,and (e)silicification zone (quartz core at the surface).Tin mineralization is related to greisenization,especially to topaz-quartz greisenization.Rock and ore-forming temperatures and oxygen fugacities are estimated,respectively.There are significant differences in many aspects between the Yinyan porphyry tin deposit and volcan-ic-subvolcanic porphyry tin deposits.

  17. Burden of injuries and diseases in Yunnan Tin Miners

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    @@ The burden of injuries is underestimated to an even greater extent in developing countries than in industrialized countries. The objective of this paper is to analyze injuries and diseases in the monitored work place of the world's largest tin mining operation in Yunnan, South China.

  18. Chemical vapor deposition of tin oxide: fundamentals and applications

    NARCIS (Netherlands)

    Mol, A.M.B. van; Chae, Y.; McDaniel, A.H.; Allendorf, M.D.

    2006-01-01

    Tin oxide thin layers have very beneficial properties such as a high transparency for visible light and electrical conductivity making these coatings suitable for a wide variety of applications, such as solar cells, and low-emissivity coatings for architectural glass windows. Each application

  19. Recent results on neutron rich tin isotopes by laser spectroscopy

    CERN Document Server

    Roussière, B; Crawford, J E; Essabaa, S; Fedosseev, V; Geithner, W; Genevey, J; Girod, M; Huber, G; Horn, R; Kappertz, S; Lassen, J; Le Blanc, F; Lee, J K P; Le Scornet, G; Lettry, Jacques; Mishin, V I; Neugart, R; Obert, J; Oms, J; Ouchrif, A; Peru, S; Pinard, J; Ravn, H L; Sauvage, J; Verney, D

    2001-01-01

    Laser spectroscopy measurements have been performed on neutron rich tin isotopes using the COMPLIS experimental setup. The nuclear charge radii of the even-even isotopes from A=108 to 132 are compared to the results of macroscopic and microscopic calculations. The improvements and optimizations needed to perform the isotope shift measurement on $^{134}$Sn are presented.

  20. On the electrochemical migration mechanism of tin in electronics

    DEFF Research Database (Denmark)

    Minzari, Daniel; Jellesen, Morten Stendahl; Møller, Per

    2011-01-01

    Electrochemical migration (ECM) of tin can result in the growth of a metal deposit with a dendritic structure from cathode to anode. In electronics, such growth can lead to short circuit of biased electrodes, potentially leading to intermittent or complete failure of an electronic device...

  1. CdTe nBn photodetectors with ZnTe barrier layer grown on InSb substrates

    Science.gov (United States)

    He, Zhao-Yu; Campbell, Calli M.; Lassise, Maxwell B.; Lin, Zhi-Yuan; Becker, Jacob J.; Zhao, Yuan; Boccard, Mathieu; Holman, Zachary; Zhang, Yong-Hang

    2016-09-01

    We have demonstrated an 820 nm cutoff CdTe nBn photodetector with ZnTe barrier layer grown on an InSb substrate. At room temperature, under a bias of -0.1 V, the photodetector shows Johnson and shot noise limited specific detectivity (D*) of 3 × 1013 cm Hz1/2/W at a wavelength of 800 nm and 2 × 1012 cm Hz1/2/W at 200 nm. The D* is optimized by using a top contact design of ITO/undoped-CdTe. This device not only possesses nBn advantageous characteristics, such as generation-recombination dark current suppression and voltage-bias-addressed two-color photodetection, but also offers features including responsivity enhancements by deep-depletion and by using a heterostructure ZnTe barrier layer. In addition, this device provides a platform to study nBn device physics at room temperature, which will help us to understand more sophisticated properties of infrared nBn photodetectors that may possess a large band-to-band tunneling current at a high voltage bias, because this current is greatly suppressed in the large-bandgap CdTe nBn photodetector.

  2. Mechanical, tribological and corrosion properties of CrBN films deposited by combined direct current and radio frequency magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Jahodova, Vera [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, 638075 (Singapore); Koszalin University of Technology, Sniadeckich 2, 75-0453 Koszalin (Poland); Technical University of Liberec, Studentska 1402/2, 461 17 Liberec1 (Czech Republic); Ding, Xing-zhao, E-mail: xzding@SIMTech.a-star.edu.sg [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, 638075 (Singapore); Seng, Debbie H.L. [Institute of Materials Research and Engineering, 3 Research Link, 117602 (Singapore); Gulbinski, W. [Koszalin University of Technology, Sniadeckich 2, 75-0453 Koszalin (Poland); Louda, P. [Technical University of Liberec, Studentska 1402/2, 461 17 Liberec1 (Czech Republic)

    2013-10-01

    Cr–B–N films were deposited on stainless steel substrates by a combined direct current and radio frequency (RF) reactive unbalanced magnetron sputtering process using two elemental Cr and one compound BN targets. Boron content in the as-deposited films was qualitatively analyzed by time-of-flight secondary ion mass spectroscopy. Films' microstructure, mechanical and tribological properties were characterized by X-ray diffraction, nanoindentation and pin-on-disk tribometer experiments. Corrosion behavior of the Cr–B–N films was evaluated by electrochemical potentiodynamic polarization method in a 3 wt.% NaCl solution. All the films were crystallized into a NaCl-type cubic structure. At lower RF power applied on the BN target (≤ 600 W), films are relatively randomly oriented, and films' crystallinity increased with increasing RF power. With increasing RF power further (≥ 800 W), films became (200) preferentially oriented, and films' crystallinity decreased gradually. With incorporation of a small amount of boron atoms into the CrN films, hardness, wear- and corrosion-resistance were all improved evidently. The best wear and corrosion resistance was obtained for the film deposited with 600 W RF power applied on the BN target. - Highlights: • CrBN films deposited by direct current and radio frequency magnetron sputtering. • CrBN exhibited higher hardness, wear- and corrosion-resistance than pure CrN. • The best wear- and corrosion-resistant film was deposited with 600 W RF power.

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

    Science.gov (United States)

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

    2017-08-01

    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 (ΔT 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.

  4. Modulation of interfacial electronic properties in PbI2 and BN van der Waals heterobilayer via external electric field

    Science.gov (United States)

    Ma, Yaqiang; Zhao, Xu; Niu, Mengmeng; Dai, Xianqi; Li, Wei; Wang, Xiaolong; Zhao, Mingyu; Wang, Tianxing; Tang, Yanan

    2017-07-01

    The interfacial electronic properties of PbI2 and BN van der Waals (vdW) heterobilayer are explored by using density functional theory (DFT) method. An intrinsic type-II heterostructure with a wide bandgap is demonstrated. The spatial separation of the lowest energy electron-hole pairs can be actualised and make PbI2/BN heterostructure as a good candidate for applications in optoelectronics and solar cell. A simulation of Efield is actualized to modify its electronic properties. Band alignment converts from type-II to type-I heterostructure separated by a forward voltage with the value of about 0.07 V/Å. Three regions implying different Efield-sensitive properties are obtained from the variations of bandgap with Efield. The charge redistribution with an Efield is mainly on the surface of PbI2 and BN layers as well as the amount of electrons depends on the strength of Efield. In addition, the PbI2/BN heterobilayer exhibits more outstanding optical conductivity capability. Our results could bring forward a new perspective on sensor and shed light on the design of novel nano- and optoelectronics based on the PbI2/BN vdW heterostructure.

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

    Science.gov (United States)

    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.

  6. Wear resistance and microstructural properties of Ni–Al/h-BN/WC–Co coatings deposited using plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Hsiao, W.T. [Materials and Chemical Research Laboratories, Industrial Technology Research Institute, Chutung 310, Taiwan (China); Su, C.Y., E-mail: cysu@ntut.edu.tw [Graduate Institute of Manufacturing Technology, National Taipei University of Technology, Taipei 106, Taiwan (China); Huang, T.S. [China Steel Corporation, Kaohsiung, Taiwan (China); Liao, W.H. [Materials and Chemical Research Laboratories, Industrial Technology Research Institute, Chutung 310, Taiwan (China); Nano Technology Laboratory, Department of Materials Engineering, National Chung Hsing University, Taichung 402, Taiwan (China)

    2013-05-15

    Hexagonal boron nitride (h-BN) and tungsten carbide cobalt (WC–Co) were added to nickel aluminum alloy (Ni–Al) and deposited as plasma sprayed coatings to improve their tribological properties. The microstructure of the coatings was analyzed using a scanning electron microscope (SEM). Following wear test, the worn surface morphologies of the coatings were analyzed using a SEM to identify their fracture modes. The results of this study demonstrate that the addition of h-BN and WC–Co improved the properties of the coatings. Ni–Al/h-BN/WC–Co coatings with high hardness and favorable lubrication properties were deposited. - Highlights: • We mixed Ni–Al, h-BN and WC–Co powders and deposited them as composite coatings. • Adding WC–Co was found to increase the hardness and reduce the wear volume loss. • Adding h-BN was found to decrease the hardness and reduce the friction coefficient. • This composite coating was shown to have improved wear properties at 850 °C.

  7. Micro/nano-scale investigation on tin alloys and tin dioxide nanowires

    Science.gov (United States)

    Sun, Yong

    Tin (Sn) and its alloys have been at people's service since 3000 BC when bronze (alloy of tin and copper) was produced in large scale. They have unique properties and find applications in various engineering fields. Correspondingly, there is abundant information waiting to be clarified surrounding these Sn-related materials. As the key element used for solder alloys, the properties of Sn alloys have been of great interest to the electronic packaging community. At the same time, the intriguing phenomenon of spontaneous Sn whisker growth from Sn / Sn-alloy thin films have bothered, yet also inspired materials scientists for over 60 years. The most commonly seen Sn-containing compound, SnO 2, is in high demand as well due to its exceptional electronic and chemical properties. In addition, nanostructures of SnO2 are intensively studied for their potential applications as solid-state sensors, transparent conducting materials, lithium-ion batteries, high-efficiency solar cell and recently, supercapacitors. The objective of this proposed research is to explore the amazing properties of Sn and Sn-alloys from several different perspectives. Firstly, ever since the banish of lead in solder alloys, lead-free alloys such as Sn-Ag-Cu (SAC) has been put under the spotlight. We intend to use our expertise in nanomechanics to give an in-depth and thorough investigation on a popular SAC387 alloy. The mechanical properties of each phase and the local deformation mechanisms have been considered. Secondly, the Sn whisker growth phenomenon is to be re-visited. With the aid of digital image correlation (DIC) techniques, it was found that magnitude of the strain gradient plays an important role in whisker growth. Moreover, DIC helps to visualize the dynamic growth process in which the alteration of strain field has been identified to cause growth of subsequent whiskers. Last but not least, the performance of SnO2 nanowires is to be evaluated in several aspects including mechanical

  8. Effects of Conformal Coat on Tin Whisker Growth

    Science.gov (United States)

    Kadesch, Jong S.; Leidecker, Henning; Day, John H. (Technical Monitor)

    2000-01-01

    A whisker from a tin plated part was blamed for the loss of a commercial spacecraft in 1998. Although pure tin finishes are prohibited by NASA, tin plated parts, such as hybrids, relays and commercial off the shelf (COTS) parts, are something discovered to have been installed in NASA spacecraft. Invariably, the assumption is that a conformal coat will prevent the growth of, or short circuits caused by, tin whiskers. This study measures the effect a Uralane coating has on the initiation and growth of tin whiskers, on the ability of this coating to prevent a tin whisker from emerging from the coating, and on the ability to prevent shorting. A sample of fourteen brass substrates (1 inch by 4 inches by 1/16 inch) were plated by two separate processes: half of the specimens were 'bright' tin plated directly over the brass substrate and half received a copper flash over the brass substrate prior to 'bright' tin plating. Each specimen was coated on one half of the substrate with three bi-directional sprays of Uralane 5750 to a nominal thickness of 25 to 75 micrometers (1 to 3 mils). Several specimens of both types, Cu and non-Cu flashed, were placed in an oven maintained at 50 C as others' work suggests that this is the optimal temperature for whisker formation. The remaining specimens were maintained at room ambient conditions. The surfaces of each specimen have been regularly inspected using both optical (15 to 400x power) and Scanning Electronic Microscopy (SEM). Many types of growths, including needle-like whiskers, first appeared approximately three months after plating on the non-conformally coated sides of all specimens. At four months, 4 to 5 times more growth sites were observed on the coated side; however, the density of growth sites on the non-conformally coated side has since increased rapidly, and now, at one year, is about the same for both sides. The density of growth sites is estimated at 90/sq mm with 30 percent of the sites growing whiskers (needle

  9. Colorimetric visualization of tin corrosion: A method for early stage corrosion detection on printed circuit boards

    DEFF Research Database (Denmark)

    Verdingovas, Vadimas; Jellesen, Morten Stendahl; Ambat, Rajan

    2017-01-01

    A majority of printed circuit board surfaces are covered with tin, therefore tin corrosion under humid conditions and movement of tin ions under the influence of an electric field plays an important role in the corrosion failure development. Tracking tin corrosion products spread on the printed...... a colorimetric tin ion indicator applied as a gel. The examples provided in this paper include visualization of corrosion caused by weak organic acids found in solder fluxes, corrosion profiling on the PCBAs after climatic device level testing, and failure analysis of field returns....

  10. Proton microprobe study of tin-polymetallic deposits

    Energy Technology Data Exchange (ETDEWEB)

    Murao, S. [Geological Survey of Japan, Tsukuba, Ibaraki (Japan); Sie, S.H.; Suter, G.F. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience

    1996-12-31

    Tin-polymetallic vein type deposits are a complex mixture of cassiterite and sulfides and they are the main source of technologically important rare metals such as indium and bismuth. Constituent minerals are usually fine grained having wide range of chemical composition and often the elements of interest occur as trace elements not amenable to electron microprobe analysis. PIXE with a proton microprobe can be an effective tool to study such deposits by delineating the distribution of trace elements among carrier minerals. Two representative indium-bearing deposits of tin- polymetallic type, Tosham of India (Cu-ln-Bi-Sn-W-Ag), and Mount Pleasant of Canada (Zn-Cu-In-Bi-Sn-W), were studied to delineate the distribution of medical/high-tech rare metals and to examine the effectiveness of the proton probe analysis of such ore. One of the results of the study indicated that indium and bismuth are present in chalcopyrite in the deposits. In addition to these important rare metals, zinc, copper, arsenic, antimony, selenium, and tin are common in chalcopyrite and pyrite. Arsenopyrite contains nickel, copper, zinc, silver, tin, antimony and bismuth. In chalcopyrite and pyrite, zinc, arsenic, indium, bismuth and lead are richer in Mount Pleasant ore, but silver is higher at Tosham. Also thallium and gold were found only in Tosham pyrite. The Tosham deposit is related to S-type granite, while Mount Pleasant to A-type. It appears that petrographic character of the source magma is one of the factors to determine the trace element distribution in tin-polymetallic deposit. 6 refs., 2 figs.

  11. 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

    Science.gov (United States)

    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.

  12. Evaluation of tin plating systems for a high-noble alloy.

    Science.gov (United States)

    Imbery, T A; Davis, R D

    1993-01-01

    The tensile bond strength of Panavia EX to a high-noble alloy prepared by abrasive spraying and tin plating was measured. Two different intraoperatory tin plating systems were compared. Disk-shaped specimens were cast in type III gold, abrasive sprayed with aluminum oxide, and divided into three groups of 30 specimens each. Specimens in one group were tin plated by using a Kura Ace Mini unit, those in the second group were tin plated by using a Micro Tin unit, and those in the third group were not tin plated and served as the control group. Disks within each group were luted to each other with Panavia EX. The specimens were thermocycled and tested in tension. There was no significant difference between the two tin plated groups; however, the luting bond of both experimental groups was significantly stronger than was that of the control (P < .05).

  13. Metallic tin quantum sheets confined in graphene toward high-efficiency carbon dioxide electroreduction

    Science.gov (United States)

    Lei, Fengcai; Liu, Wei; Sun, Yongfu; Xu, Jiaqi; Liu, Katong; Liang, Liang; Yao, Tao; Pan, Bicai; Wei, Shiqiang; Xie, Yi

    2016-09-01

    Ultrathin metal layers can be highly active carbon dioxide electroreduction catalysts, but may also be prone to oxidation. Here we construct a model of graphene confined ultrathin layers of highly reactive metals, taking the synthetic highly reactive tin quantum sheets confined in graphene as an example. The higher electrochemical active area ensures 9 times larger carbon dioxide adsorption capacity relative to bulk tin, while the highly-conductive graphene favours rate-determining electron transfer from carbon dioxide to its radical anion. The lowered tin-tin coordination numbers, revealed by X-ray absorption fine structure spectroscopy, enable tin quantum sheets confined in graphene to efficiently stabilize the carbon dioxide radical anion, verified by 0.13 volts lowered potential of hydroxyl ion adsorption compared with bulk tin. Hence, the tin quantum sheets confined in graphene show enhanced electrocatalytic activity and stability. This work may provide a promising lead for designing efficient and robust catalysts for electrolytic fuel synthesis.

  14. Effect of Graphene Addition on Mechanical Properties of TiN

    Energy Technology Data Exchange (ETDEWEB)

    Shon, In-Jin [Chonbuk National University, Jeonju (Korea, Republic of); Yoon, Jin-Kook; Hong, Kyung-Tae [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2017-03-15

    Despite of many attractive properties of TiN, the current concern about the TiN focuses on its low fracture toughness below the ductile-brittle transition temperature. To improve its mechanical properties, the approach generally utilized has been the addition of a second phase to form composites and to make nanostructured materials. In this respect, highly dense nanostructured TiN and TiN-graphene composites were obtained within two min at 1250 ℃. The grain size of TiN was reduced remarkably by the addition of graphene. The addition of graphene to TiN simultaneously improved the fracture toughness and hardness of TiN-graphene composite due to refinement of TiN and deterring crack propagation by graphene. This study demonstrates that the graphene can be an effective reinforcing agent for improved hardness and fracture toughness of TiN composites.

  15. Ferroelectric Single-Crystal Gated Graphene/Hexagonal-BN/Ferroelectric Field-Effect Transistor.

    Science.gov (United States)

    Park, Nahee; Kang, Haeyong; Park, Jeongmin; Lee, Yourack; Yun, Yoojoo; Lee, Jeong-Ho; Lee, Sang-Goo; Lee, Young Hee; Suh, Dongseok

    2015-11-24

    The effect of a ferroelectric polarization field on the charge transport in a two-dimensional (2D) material was examined using a graphene monolayer on a hexagonal boron nitride (hBN) field-effect transistor (FET) fabricated using a ferroelectric single-crystal substrate, (1-x)[Pb(Mg1/3Nb2/3)O3]-x[PbTiO3] (PMN-PT). In this configuration, the intrinsic properties of graphene were preserved with the use of an hBN flake, and the influence of the polarization field from PMN-PT could be distinguished. During a wide-range gate-voltage (VG) sweep, a sharp inversion of the spontaneous polarization affected the graphene channel conductance asymmetrically as well as an antihysteretic behavior. Additionally, a transition from antihysteresis to normal ferroelectric hysteresis occurred, depending on the V(G) sweep range relative to the ferroelectric coercive field. We developed a model to interpret the complex coupling among antihysteresis, current saturation, and sudden conductance variation in relation with the ferroelectric switching and the polarization-assisted charge trapping, which can be generalized to explain the combination of 2D structured materials with ferroelectrics.

  16. Immobilization of Cesium Traps from the BN-350 Fast Reactor (Aktau, Kazakhstan)

    Energy Technology Data Exchange (ETDEWEB)

    J. A. Michelbacher; C. Knight; O. G. Romanenko; I. L. Tazhibaeva; I. L. Yakovlev; A. V. Rovneyko; V. I. Maev; D. Wells; A. Herrick

    2011-03-01

    During BN-350 reactor operations and also during the initial stages of decommissioning, cesium traps were used to decontaminate the reactor’s primary sodium coolant. Two different types of carbon-based trap were used – the MAVR series, low ash granulated graphite adsorber (LAG) contained in a carrier designed to be inserted into the reactor core during shutdown; and a series of ex-reactor trap accumulators(TAs) which used reticulated vitreous carbon (RVC) to reduce Cs-137 levels in the sodium after final reactor shutdown. In total four MAVRs and seven TAs were used at BN-350 to remove an estimated cumulative 755 TBq of cesium. The traps, which also contain residual sodium, need to be immobilized in an appropriate way to allow them to be consigned as waste packages for long term storage and, ultimately, disposal. The present paper reports on the current status of the implementation phase, with particular reference to the work done to date on the trap accumulators, which have the most similarity with the cesium traps used at other reactors.

  17. GGA-based analysis of the metformin adsorption on BN nanotubes

    Science.gov (United States)

    Chigo Anota, Ernesto; Cocoletzi, Gregorio H.

    2014-02-01

    Density functional theory (DFT) studies are done to investigate structural and electronic properties of (5,5) chirality single walls boron nitride nanotubes (BNNTs) in the armchair model interacting with metformin (MF) on the surface and ends. Our calculations consider the exchange-correlation energies with the Hamprecht-Cohen-Tozer-Handy functional within the generalized gradient approximation (HCTH-GGA) and the double polarized DNP base function. The geometry optimization follows the minimum energy criterion for all six geometries we have considered. Results show that the MF is adsorbed through the groups NH2-NH at one end of the nanotube. The system polarity is increased which indicates the possible dispersion and solubility. Moreover the interaction between these species induces an increase in the chemical reactivity of the order of 0.42 eV. Meanwhile the solvation in water keeps the semiconductor characteristics of both nanotube and MF. The work function of the BNNT-MF is drastically reduced respect to the pristine system when the BN nanotube is doped at its surface and ends with carbon. This means that the functionalized BN nanotube facilitates conditions to improve field emission.

  18. First-principles study on electron transport through BN-dimer embedded zigzag carbon nanotubes

    Science.gov (United States)

    Egami, Yoshiyuki; Akera, Hiroshi

    2017-04-01

    First-principles calculations are performed for electron transmission through a metallic zigzag carbon nanotube with substitutional BN dimers parallel to the nanotube axis. The transmission coefficient is calculated in the energy range (around the charge neutrality point) in which there exist two degenerate subbands for each spin. Wave functions in the circumferential direction of one of the degenerate subbands can be chosen so as to have nodes at the position of a carbon dimer parallel to the nanotube axis. It is shown that the transmission probability of an incident wave with such wave-function nodes depends crucially on positions of BN dimers relative to the nodes. By placing each of dimers at one of the nodes, the transmission probability is substantially enhanced and is well described by the Born approximation in spite of spatially extended scattering potential due to ionized B and N. This suggests that the arrangement in the circumferential direction of various impurities influences transport through metallic zigzag carbon nanotubes.

  19. High-Energy Density and Superhard Nitrogen-Rich B-N Compounds

    Science.gov (United States)

    Li, Yinwei; Hao, Jian; Liu, Hanyu; Lu, Siyu; Tse, John S.

    2015-09-01

    The pressure-induced transformation of diatomic nitrogen into nonmolecular polymeric phases may produce potentially useful high-energy-density materials. We combine first-principles calculations with structure searching to predict a new class of nitrogen-rich boron nitrides with a stoichiometry of B3N5 that are stable or metastable relative to solid N2 and h -BN at ambient pressure. The most stable phase at ambient pressure has a layered structure (h -B3N5 ) containing hexagonal B3N3 layers sandwiched with intercalated freely rotating N2 molecules. At 15 GPa, a three-dimensional C 2 2 21 structure with single N-N bonds becomes the most stable. This pressure is much lower than that required for triple-to-single bond transformation in pure solid nitrogen (110 GPa). More importantly, C 2 2 21-B3N5 is metastable, and can be recovered under ambient conditions. Its energy density of ˜3.44 kJ /g makes it a potential high-energy-density material. In addition, stress-strain calculations estimate a Vicker's hardness of ˜4 4 GPa . Structure searching reveals a new clathrate sodalitelike BN structure that is metastable under ambient conditions.

  20. SN 2015bn: a detailed multi-wavelength view of a nearby superluminous supernova

    CERN Document Server

    Nicholl, M; Smartt, S J; Margutti, R; Kamble, A; Alexander, K D; Chen, T -W; Inserra, C; Arcavi, I; Blanchard, P K; Cartier, R; Chambers, K C; Childress, M J; Chornock, R; Cowperthwaite, P S; Drout, M; Flewelling, H A; Fraser, M; Gal-Yam, A; Galbany, L; Harmanen, J; Holoien, T W -S; Hosseinzadeh, G; Howell, D A; Huber, M E; Jerkstrand, A; Kankare, E; Kochanek, C S; Lin, Z -Y; Lunnan, R; Magnier, E A; Maguire, K; McCully, C; McDonald, M; Metzger, B D; Milisavljevic, D; Mitra, A; Reynolds, T; Saario, J; Shappee, B J; Smith, K W; Valenti, S; Villar, V A; Waters, C; Young, D R

    2016-01-01

    We present observations of SN 2015bn (= PS15ae = CSS141223-113342+004332 = MLS150211-113342+004333), a Type I superluminous supernova (SLSN) at $z=0.1136$. As well as being one of the closest SLSNe, it is intrinsically brighter ($M_U\\approx-23.1$) and in a fainter host ($M_B\\approx-16.0$) than other SLSNe at $z\\sim0.1$. We collected the most extensive dataset for an SLSN I to date, including spectroscopy and UV to NIR photometry from $-$50 to +250 d from maximum light. SN 2015bn is a slowly-declining SLSN, but exhibits surprising undulations in the light curve on a timescale of 30-50 d, which are more pronounced in the UV. The spectrum resembles other SLSNe, but our well-sampled data reveal extraordinarily slow evolution except for a rapid transformation between +7 and +30 d. We detect weak features that we tentatively suggest may be hydrogen and helium. At late times, blue colours and a trio of lines around 6000 \\AA\\ seem to distinguish slowly-declining SLSNe from faster ones. We derive physical properties i...

  1. Dynamic Negative Compressibility of Few-Layer Graphene, h-BN, and MoS2

    Science.gov (United States)

    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

  2. BN-coated Ca(1-x)Sr(x)S:Eu solid-solution nanowires with tunable red light emission.

    Science.gov (United States)

    Lin, Jing; Huang, Yang; Mi, Jiao; Zhang, Xinghua; Lu, Zunming; Xu, Xuewen; Fan, Ying; Zou, Jin; Tang, Chengchun

    2013-10-11

    We report on the controlled growth of novel BN-coated Ca(1-x)Sr(x)S:Eu nanowires via a solid-liquid-solid process. The Ca(1-x)Sr(x)S solid solution forms as one-dimensional nanowires and has been coated with homogeneous protective BN nanolayers. The structure and luminescence properties of this new nanocomposite have been systematically investigated. High-spatial-resolution cathodoluminescence investigations reveal that effective red color tuning has been achieved by tailoring the composition of the Ca(1-x)Sr(x)S nanowires. Moreover, codoping of Ce(3+) and Eu(2+) in the CaS nanowire can induce energy transfer in the matrix and make it possible to obtain enhanced orange color in the nanowires. The BN-coated Ca(1-x)Sr(x)S:Eu solid-solution nanowires are envisaged to be valuable red-emitting nanophosphors and useful in advanced nanodevices and white LEDs.

  3. Theoretical Study of Midwave Infrared HgCdTe nBn Detectors Operating at Elevated Temperatures

    Science.gov (United States)

    Akhavan, Nima Dehdashti; Jolley, Gregory; Umana-Membreno, Gilberto A.; Antoszewski, Jarek; Faraone, Lorenzo

    2015-09-01

    We report a theoretical study of mercury cadmium telluride (HgCdTe) unipolar n-type/barrier/ n-type (nBn) detectors for midwave infrared (MWIR) applications at elevated temperatures. The results obtained indicate that the composition, doping, and thickness of the barrier layer in MWIR HgCdTe nBn detectors can be optimized to yield performance levels comparable with those of ideal HgCdTe p- n photodiodes. It is also shown that introduction of an additional barrier at the back contact layer of the detector structure (nBnn+) leads to substantial suppression of the Auger generation-recombination (GR) mechanism; this results in an order-of-magnitude reduction in the dark current level compared with conventional nBn or p- n junction-based detectors, thus enabling background-limited detector operation above 200 K.

  4. Electronic structure of transferred graphene/h-BN van der Waals heterostructures with nonzero stacking angles by nano-ARPES

    Science.gov (United States)

    Wang, Eryin; Chen, Guorui; Wan, Guoliang; Lu, Xiaobo; Chen, Chaoyu; Avila, Jose; Fedorov, Alexei V.; Zhang, Guangyu; Asensio, Maria C.; Zhang, Yuanbo; Zhou, Shuyun

    2016-11-01

    In van der Waals heterostructures, the periodic potential from the Moiré superlattice can be used as a control knob to modulate the electronic structure of the constituent materials. Here we present a nanoscale angle-resolved photoemission spectroscopy (nano-ARPES) study of transferred graphene/h-BN heterostructures with two different stacking angles of 2.4° and 4.3° respectively. Our measurements reveal six replicas of graphene Dirac cones at the superlattice Brillouin zone (SBZ) centers. The size of the SBZ and its relative rotation angle to the graphene BZ are in good agreement with Moiré superlattice period extracted from atomic force microscopy (AFM) measurements. Comparison to the epitaxial graphene/h-BN with 0° stacking angles suggests that the interaction between graphene and h-BN decreases with increasing stacking angle.

  5. Diamond and cBN hybrid and nanomodified cutting tools with enhanced performance: Development, testing and modelling

    DEFF Research Database (Denmark)

    Loginov, Pavel; Mishnaevsky, Leon; Levashov, Evgeny

    2015-01-01

    The potential of enhancement of superhard steel and cast iron cutting tool performance on the basis of microstuctural modifications of the tool materials is studied. Hybrid machining tools with mixed diamond and cBN grains, as well as machining tool with composite nanomodified metallic binder...... are developed, and tested experimentally and numerically. It is demonstrated that both combination of diamond and cBN (hybrid structure) and nanomodification of metallic binder (with hexagonal boron nitride/hBN platelets) lead to sufficient improvement of the cast iron machining performance. The superhard tools...... compared to the tool with the original binder. Computational model of hybrid superhard tools is developed, and applied to the analysis of structure-performance relationships of the tools....

  6. Al-doped graphene-like BN nanosheet as a sensor for para-nitrophenol: DFT study

    Science.gov (United States)

    Peyghan, Ali Ahmadi; Noei, Maziar; Yourdkhani, Sirous

    2013-07-01

    We investigated the electronic sensitivity of pristine and Al-doped BN sheets to para-nitrophenol (p-NP) by using density functional calculations. It was found that p-NP adsorption on the pristine sheet is endothermic and unfavorable. By replacing adsorbing boron atom of the sheet surface by an Al atom, the sheet becomes more reactive to p-NP, so energy of 20.4 kcal/mol is released upon adsorption process. Upon p-NP adsorption on the Al-doped BN sheet, HOMO/LUMO energy gap of the sheet is dramatically decreased from 5.39 to 1.23 eV and it becomes a p-type semiconductor. Thus, the Al-doped BN sheet may transform the presence of p-NP molecule into an electrical signal, and it might be potentially used in p-NP sensors.

  7. Impact of graphene and single-layer BN insertion on bipolar resistive switching characteristics in tungsten oxide resistive memory

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jongmin; Kim, Duhwan; Jo, Yongcheol; Han, Jaeseok; Woo, Hyeonseok [Division of Physics and Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of); Kim, Hyungsang, E-mail: hskim@dongguk.edu [Division of Physics and Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of); Kim, K.K., E-mail: kkkim@dongguk.edu [Department of Energy and Materials Engineering, Dongguk University, Seoul 100-715 (Korea, Republic of); Hong, J.P. [Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Im, Hyunsik, E-mail: hyunsik7@dongguk.edu [Division of Physics and Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of)

    2015-08-31

    The role of the atomic interface in the resistive switching in Al–WO{sub 3}–Al devices is investigated by inserting metallic graphene or insulating hexagonal BN sheet between the top Al electrode and WO{sub 3} film. Clear reversible bipolar-type resistive switching phenomena were observed, regardless of the interface modification. However, endurance and retention properties were affected by the nature of the interface. While the device containing the graphene interface showed significantly improved performance, another device containing the hexagonal BN sheet showed degraded performance. These experimental findings suggest that atomic configuration of the electrode/oxide interface plays a key role in determining the resistive switching characteristics. - Highlights: • We fabricated WO{sub 3}-based non-volatile memories. • Effects of interface on memory performance were studied using graphene and BN. • The graphene-inserted device showed significantly improved performance.

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

    Science.gov (United States)

    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.

  9. DEPOSITION OF TiBN HARD FILMS ON HOT-WORKING-STEEL DIES FOR ALUMINIUM EXTRUSION VIA A DUPLEX PROCESS

    Institute of Scientific and Technical Information of China (English)

    K. MUller

    2001-01-01

    Hot working steels have been used as die materials for hot extrusion of aluminium.Due to tribological interaction at elevated temperature between the die bearing and thesurface of extruded aluminium profiles, not only the surface quality of the extrudedproduct, but also the lifetime of the dies decreases. Deposition of TiBN hard films onthe die bearing could improve the die performance. Treatment should be done in aduplex process process combining a plasma nitriding pretreatment (PN) and a plasmaassisted chemical vapour deposition (PACVD) of TiBN. In this study the influence ofthe process conditions on the properties of the duplex coatings was investigated. Therelationship between structure and mechanical property was researched. For testingthese TiBN hardfilms under elevated temperature conditions and for comparison withother possible coatings special extrusion dies with different coated bearings were used.The extrusion trials were performed on the 8MN-extrusion press at the research anddevelopment center for extrusion, Technical University of Berlin.

  10. Synthesis and characterisation of the complete series of B-N analogues of triptycene.

    Science.gov (United States)

    Seven, Omer; Popp, Sebastian; Bolte, Michael; Lerner, Hans-Wolfram; Wagner, Matthias

    2014-06-14

    The reaction between the bisborate Li2[o-C6H4(BH3)2] and 2 equivalents of an appropriate pyrazole derivative (Hpz(R)) in the presence of Me3SiCl yields o-phenylene-bridged pyrazaboles HB(μ-pz(R))2(μ-o-C6H4)BH (3a-3e; Hpz(R) = 4-iodopyrazole (3a), 4-(trimethylsilyl)pyrazole (3b), 3,5-dimethylpyrazole (3c), 3,5-di(tert-butyl)pyrazole (3d), 3,5-bis(trifluoromethyl)pyrazole (3e)). The synthesis approach thus provides access to uncharged B-N triptycenes bearing (i) functionalisable groups, (ii) electron-donating or -withdrawing substituents and (iii) pyrazole rings of varying steric demand. Treatment of p-R*C6H4BBr2 with the potassium tris(pyrazol-1-yl)borates K[HBpz3] or K[p-R*C6H4Bpz3] yields cationic pyrazolyl-bridged pyrazaboles [p-BrC6H4B(μ-pz)3BH]Br ([4a]Br) and [p-R*C6H4B(μ-pz)3Bp-C6H4R*]Br (R* = Br ([4b]Br), I ([4c]Br), SiMe3 ([4d]Br)), which can be regarded as full B-N analogues of triptycene. The B-H bonds of 3b and [4a]Br are unreactive towards tBuC[triple bond, length as m-dash]CH even at temperatures of 80 °C, thereby indicating an appreciable thermal stability of the corresponding B-N cage bonds. Most of the cage compounds are sufficiently inert towards water to allow quick aqueous workup. However, NMR spectroscopy in CD3OD solution reveals degradation of 3b or [4a]Br to the corresponding pyrazoles and o-C6H4(B(OCD3)2)2 or p-BrC6H4B(OCD3)2/B(OCD3)3. The diphenylated species [4b]Br is significantly more stable under the same measurement conditions; even after 76 d, most of the material degrades only to the stage of the syn/anti-pyrazaboles p-BrC6H4(CD3O)B(μ-pz)2B(OCD3)p-C6H4Br (11a/11b). A derivatisation of [4c]Br with nBu3SnC≡CtBu through Stille-type coupling reactions furnishes the alkynyl derivative [p-tBuC≡CC6H4B(μ-pz)3Bp-C6H4C≡CtBu]Br ([4e]Br). Larger B-N aggregates are also accessible: treatment of the tetrakisborate Li4[1,2,4,5-C6H2(BH3)4] with 4 equivalents of Hpz(R) in the presence of Me3SiCl leads to the corresponding B-N

  11. Unleashing the quadratic nonlinear optical responses of graphene by confining white-graphene (h-BN) sections in its framework.

    Science.gov (United States)

    Karamanis, Panaghiotis; Otero, Nicolás; Pouchan, Claude

    2014-05-21

    In an attempt to diversify the options in designing graphene-based systems bearing large second order nonlinear optical (NLO) responses of octupolar and/or dipolar character, the subject of the quadratic NLO properties of hybrid boron nitride (BN) graphene flakes is opened up. State of the art ab initio and density functional theory methods applied on a toolbox of book-text octupolar and arbitrary dipolar planar hybrid h-BN-graphene nanosized systems reveal that by confining finite h-BN sections in the internal network of graphene, the capacity of the π-electron network of graphene species in delivering giant second order NLO responses could be fully exploited. Configuration interaction (CIS) and time-dependent density functional (TD) computations, within the sum-overstate (SOS) perturbational approach, expose that the prevailing (hyper)polarization mechanism, lying under the sizable computed octupolar hyperpolarizabilities, is fueled by alternating positive and negative atomic charges located in the internal part of the hybrid flakes, and more precisely at the BN/graphene intersections. This type of charge transfer mechanism distinguishes, in fact, the elemental graphene dipoles/octupoles we report here from other conventional NLO dipoles or octupoles. More interestingly, it is shown that by controlling the shape, size, and covering area of the h-BN domain (or domains), one can effectively regulate "à volonté" both the magnitudes and types of the second order NLO responses switching from dipolar to octupolar and vice versa. Especially in the context of the latter class of NLO properties, this communication brings into surface novel, graphene-based, octupolar planar or quasiplanar motifs. The take home message of this communication is summarized as follows: When the right BN segment is incorporated in the right section of the right graphene flake, systems of giant quadratic NLO octupolar and/or dipolar responses may emerge.

  12. Boosting the adsorption performance of BN nanosheet as an anode of Na-ion batteries: DFT studies

    Energy Technology Data Exchange (ETDEWEB)

    Hosseinian, A. [Department of Engineering Science, College of Engineering, University of Tehran, P.O. Box 11365-4563, Tehran (Iran, Islamic Republic of); Soleimani-amiri, S. [Department of Chemistry, Karaj Branch, Islamic Azad University, Karaj (Iran, Islamic Republic of); Arshadi, S., E-mail: chemistry_arshadi@pnu.ac.ir [Department of Chemistry, Payame Noor University, Tehran (Iran, Islamic Republic of); Vessally, E. [Department of Chemistry, Payame Noor University, Tehran (Iran, Islamic Republic of); Edjlali, L. [Department of Chemistry, Tabriz Branch, Islamic Azad University, Tabriz (Iran, Islamic Republic of)

    2017-06-28

    Despite the high advance in the Li-ion battery technology, there exist great concerns about its lifetime, safety, cost, and low-temperature performance. It is expected that the Li-ion batteries may be replaced by Na-ion batteries (NIB) because of the low cost, nontoxicity, and wide availability of sodium. Here, we investigated the potential application of BN nanosheets in anode of NIBs by means of density functional theory calculation and introduced a strategy to increase their performance. It was shown that the Na and Na{sup +} are mainly adsorbed on the center of a hexagonal ring of BN sheet with adsorption energies of −0.08 and −33.7 kcal/mol, respectively. Replacing three N atoms of the hexagonal ring with larger P atoms significantly increases the performance of the sheet as an anode of a NIB but the replacement of B by Al decreases the performance. The initial cell voltage of LIB is increased by about 0.67 V after the P-doping which causes a high storage performance with long discharge time. The results are discussed based on the energetic, structural, orbital, charge transfer and electronic properties and provide guidelines to build better high-capacity anode materials for NIBs. - Highlights: • Potential use of BN sheet as anode in Na-ion batteries (NIB) is studied by DFT. • The replacement of B by Al decreases the performance. • The cell voltage of LIB is increased by about 0.67 V after by P-doping. • The order of performance is P-BN > BN >> Al-BN.

  13. Structural studies with BnSP-7 reveal an atypical oligomeric conformation compared to phospholipases A2-like toxins.

    Science.gov (United States)

    de Lima, Lino Fernando G; Borges, Rafael J; Viviescas, Maria Alejandra; Fernandes, Carlos A H; Fontes, Marcos R M

    2017-07-24

    There are 2.5 million cases of snakebite per year and approximately 100,000 at 150,000 deaths. Thus, it is considered an important public health problem by the World Health Organization. Snakes from the Bothrops genus may cause severe local effects in the victims, so it is important to develop inhibitors to treat local effects in patients. In addition, approximately 30 different species of bothropic snakes have been described that may present differences in their venom composition. Small structural differences in the venom proteins may result in different ligands binding. Herein, BnSP-7, a PLA2-like protein that causes local myotoxic effects, was analyzed using different biophysical techniques. Crystal structures of BnSP-7 binding to three different cinnamic acid derivates were solved showing that the ligands bind in the membrane-dockage region (MDoS) of the protein. Spectroscopy fluorescence and microscale thermophoresis (MST) assays showed that these ligands also bind to BnSP-7 in solution and provide comparative information about their affinity to BnSP-7. MST experiments also showed that hydroxyl radicals of the ligands, involved in their binding with the MDoS region of BnSP-7, are essential to increase their affinity with the protein. As this region has been indicated as essential for the myotoxic mechanism, the ligands could potentially be used as inhibitors for BnSP-7. These results provide relevant insights to understand the PLA2-like proteins myotoxic mechanism and may eventually lead to design of new inhibitors for these toxins. Furthermore, a comparative structural analysis of BnSP-7 with other PLA2-like proteins showed that BnSP-7 has an atypical quaternary conformation, suggesting an intermediate state that is unlike other PLA2-like proteins. This information, combined with the absence or partial occupancy of molecules in their hydrophobic channel and the misaligned membrane-disruption region, led us to hypothesize that the protein is not able to fully

  14. A High-Performance WSe2 /h-BN Photodetector using a Triphenylphosphine (PPh3 )-Based n-Doping Technique.

    Science.gov (United States)

    Jo, Seo-Hyeon; Kang, Dong-Ho; Shim, Jaewoo; Jeon, Jaeho; Jeon, Min Hwan; Yoo, Gwangwe; Kim, Jinok; Lee, Jaehyeong; Yeom, Geun Young; Lee, Sungjoo; Yu, Hyun-Yong; Choi, Changhwan; Park, Jin-Hong

    2016-06-01

    The effects of triphenylphosphine (PPh3 )-based n-doping and hexagonal boron nitride (h-BN) insertion on a tungsten diselenide (WSe2 ) photodetector are systematically studied, and a very high performance WSe2 /h-BN heterostucture-based photodetector is demonstrated with a record photoresponsivity (1.27 × 10(6) A W(-1) ) and temporal photoresponse (rise time: 2.8 ms, decay time: 20.8 ms) under 520 nm wavelength and 5 pW power laser illumination.

  15. Raman enhancement effect on two-dimensional layered materials: graphene, h-BN and MoS2.

    Science.gov (United States)

    Ling, Xi; Fang, Wenjing; Lee, Yi-Hsien; Araujo, Paulo T; Zhang, Xu; Rodriguez-Nieva, Joaquin F; Lin, Yuxuan; Zhang, Jin; Kong, Jing; Dresselhaus, Mildred S

    2014-06-11

    Realizing Raman enhancement on a flat surface has become increasingly attractive after the discovery of graphene-enhanced Raman scattering (GERS). Two-dimensional (2D) layered materials, exhibiting a flat surface without dangling bonds, were thought to be strong candidates for both fundamental studies of this Raman enhancement effect and its extension to meet practical applications requirements. Here, we study the Raman enhancement effect on graphene, hexagonal boron nitride (h-BN), and molybdenum disulfide (MoS2), by using the copper phthalocyanine (CuPc) molecule as a probe. This molecule can sit on these layered materials in a face-on configuration. However, it is found that the Raman enhancement effect, which is observable on graphene, hBN, and MoS2, has different enhancement factors for the different vibrational modes of CuPc, depending strongly on the surfaces. Higher-frequency phonon modes of CuPc (such as those at 1342, 1452, 1531 cm(-1)) are enhanced more strongly on graphene than that on h-BN, while the lower frequency phonon modes of CuPc (such as those at 682, 749, 1142, 1185 cm(-1)) are enhanced more strongly on h-BN than that on graphene. MoS2 demonstrated the weakest Raman enhancement effect as a substrate among these three 2D materials. These differences are attributed to the different enhancement mechanisms related to the different electronic properties and chemical bonds exhibited by the three substrates: (1) graphene is zero-gap semiconductor and has a nonpolar C-C bond, which induces charge transfer (2) h-BN is insulating and has a strong B-N bond, while (3) MoS2 is semiconducting with the sulfur atoms on the surface and has a polar covalent bond (Mo-S) with the polarity in the vertical direction to the surface. Therefore, the different Raman enhancement mechanisms differ for each material: (1) charge transfer may occur for graphene; (2) strong dipole-dipole coupling may occur for h-BN, and (3) both charge transfer and dipole-dipole coupling may

  16. Investigation of band structure and electrochemical properties of h-BN/rGO composites for asymmetric supercapacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Sanjit; Jana, Milan; Samanta, Pranab; Murmu, Naresh C. [Surface Engineering & Tribology Division, CSIR-Central Mechanical Engineering Research Institute, Durgapur, 713209 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-CMERI Campus, Durgapur, 713209 (India); Kim, Nam H. [Advanced Materials Institute of BIN Convergence Technology (BK21 Plus Global), Dept. of BIN Convergence Technology, Chonbuk National University, Jeonju, Jeonbuk, 54896 (Korea, Republic of); Kuila, Tapas, E-mail: tkuila@gmail.com [Surface Engineering & Tribology Division, CSIR-Central Mechanical Engineering Research Institute, Durgapur, 713209 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-CMERI Campus, Durgapur, 713209 (India); Lee, Joong H., E-mail: jhl@jbnu.ac.kr [Advanced Materials Institute of BIN Convergence Technology (BK21 Plus Global), Dept. of BIN Convergence Technology, Chonbuk National University, Jeonju, Jeonbuk, 54896 (Korea, Republic of); Carbon Composite Research Centre, Department of Polymer & Nanoscience and Technology, Chonbuk National University, Jeonju, Jeonbuk, 54896 (Korea, Republic of)

    2017-04-01

    The effect of different content of graphene oxide (GO) on the electrical and electrochemical property of h-BN/reduced GO (rGO) hetero-structure is investigated elaborately. The increasing amount of rGO within the h-BN moiety plays fascinating role by reducing the electronic work function while increasing the density of state of the electrode. Furthermore, different h-BN/rGO architecture shows different potential window and the transition from pseudocapacitance to electrochemical double layer capacitance (EDLC) is observed with increasing π-conjugation of C atoms. The rod like h-BN is aligned as sheet while forming super-lattice with rGO. Transmission electron microscopy images show crystalline morphology of the hetero-structure super-lattice. The valance band and Mott-Shotky relationship determined from Mott-Shotky X-ray photoelectron spectroscopy shows that the electronic band structure of super-lattice is improved as compared to the insulating h-BN. The h-BN/rGO super-lattice provides high specific capacitance of ∼960 F g{sup −1}. An asymmetric device configured with h-BN/rGO super-lattice and B, N doped rGO shows very high energy and power density of 73 W h kg{sup −1} and 14,000 W kg{sup −1}, respectively. Furthermore, very low relaxation time constant of ∼1.6 ms and high stability (∼80%) after 10,000 charge-discharge cycles ensure the h-BN/rGO super-lattice as potential materials for the next generation energy storage applications. - Highlights: • Band gap energy of boron nitride decreased with increasing graphene oxide content. • Graphene oxide effectively affected the charge storage mechanism of the composite. • Morphology of boron nitride changed from rod to sheet while forming superlattice. • Highly conducting superlattice showed excellent supercapacitor performance. • Asymmetric device exhibited long stability with high energy and power density.

  17. Research on Fault Diagnosis of HFC Upstream Channel Based on ANN%基于神经网络的HFC上行信道故障诊断研究

    Institute of Scientific and Technical Information of China (English)

    张力; 朱琳; 马永涛; 刘开华; 陈韬

    2011-01-01

    In order to improve the network reliability and efficiency of network maintenance, it is important to search on how to determine noise and interference types quickly and accurately based on data of actual HFC network upstream channel and then assist to find out the cause of network malfunction. BP neural network malfunction diagnosis model of HFC upstream channel is established based on LM algorithm using Matlab. The networks are trained by actual HFC upstream channel data. It is proved by simulation that the method of application of LM neural network algorithm for malfunction diagnosis has some referenced and practical value and the accuracy rate of diagnose is more than 85%.%为了提高HFC网络的可靠性和网络维护的效率,研究如何从实际的HFC网络上行信道数据中快速、准确地判断出信道中噪声和干扰的类型,进而协助查找引发故障的原因具有重大意义.利用Matlab建立了基于LM算法的HFC上行信道故障诊断BP神经网络模型,采用实际的HFC上行信道数据对网络进行训练.仿真表明,应用LM神经网络算法后故障诊断准确率达到85%以上,该方法具有一定的参考及实用价值.

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

    Science.gov (United States)

    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.

  19. Effect of different thickness h-BN coatings on interface shear strength of quartz fiber reinforced Si-O-C-N composite

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shubin [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Zheng, Yu, E-mail: shubinwang@buaa.edu.cn [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); International Centre for Bamboo and Rattan, Beijing 100102 (China)

    2014-02-15

    Hexagonal boron nitride (h-BN) coatings with different thickness were prepared on quartz fibers to improve mechanical properties of quartz fiber reinforced Si-O-C-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, K{sub IC} reaches the peak value 3.8 MPa m{sup 1/2}, which was more than two times of that of composites without h-BN coatings.

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

    Science.gov (United States)

    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.

  1. First-principles studies of BN sheets with absorbed transition metal single atoms or dimers: stabilities, electronic structures, and magnetic properties.

    Science.gov (United States)

    Ma, Dongwei; Lu, Zhansheng; Ju, Weiwei; Tang, Yanan

    2012-04-11

    BN sheets with absorbed transition metal (TM) single atoms, including Fe, Co, and Ni, and their dimers have been investigated by using a first-principles method within the generalized gradient approximation. All of the TM atoms studied are found to be chemically adsorbed on BN sheets. Upon adsorption, the binding energies of the Fe and Co single atoms are modest and almost independent of the adsorption sites, indicating the high mobility of the adatoms and isolated particles to be easily formed on the surface. However, Ni atoms are found to bind tightly to BN sheets and may adopt a layer-by-layer growth mode. The Fe, Co, and Ni dimers tend to lie (nearly) perpendicular to the BN plane. Due to the wide band gap of the pure BN sheet, the electronic structures of the BN sheets with TM adatoms are determined primarily by the distribution of TM electronic states around the Fermi level. Very interesting spin gapless semiconductors or half-metals can be obtained in the studied systems. The magnetism of the TM atoms is preserved well on the BN sheet, very close to that of the corresponding free atoms and often weakly dependent on the adsorption sites. The present results indicate that BN sheets with adsorbed TM atoms have potential applications in fields such as spintronics and magnetic data storage due to the special spin-polarized electronic structures and magnetic properties they possess.

  2. Corrosion of steels in molten gallium (Ga), tin (Sn) and tin lithium alloy (Sn–20Li)

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, Masatoshi, E-mail: kondo.masatoshi@nr.titech.ac.jp [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8550 (Japan); Ishii, Masaomi [Department of Nuclear Engineering, School of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292 (Japan); Muroga, Takeo [Department of Helical Plasma Research, National Institute for Fusion Science, Toki, Gifu 502-5292 (Japan)

    2015-10-15

    Graphical abstract: Corrosion of RAFM steel, JLF-1, in liquid Sn–20Li was caused by the formation of Fe-Sn alloyed layer. - Highlights: • The corrosion tests were performed for the reduced activation ferritic martensitic steel JLF-1 and the austenitic steel SUS316 in liquid Ga, Sn and Sn-20Li at 873 K up to 750 h. • The weight loss of the specimens exposed to liquid Ga, Sn and Sn-20Li was evaluated. • The corrosion of the steels in liquid Ga was caused by the alloying reaction between Ga and Fe on the steel surface. • The corrosion of the steels in liquid Sn was caused by the alloying reaction between Sn and Fe on the steel surface. • The corrosion of the steels in liquid Sn-20Li was caused by the formation of the Fe-Sn alloyed layer and the diffusion of Sn and Li into the steel matrix. - Abstract: The compatibility of steels in liquid gallium (Ga), tin (Sn) and tin lithium alloy (Sn–20Li) was investigated by means of static corrosion tests. The corrosion tests were performed for reduced activation ferritic martensitic steel JLF-1 (JOYO-HEAT, Fe–9Cr–2W–0.1C) and austenitic steel SUS316 (Fe–18Cr–12Ni–2Mo). The test temperature was 873 K, and the exposure time was 250 and 750 h. The corrosion of these steels in liquid Ga, Sn and Sn–20Li alloy was commonly caused by the formation of a reaction layer and the dissolution of the steel elements into the melts. The reaction layer formed in liquid Ga was identified as Fe{sub 3}Ga from the results of metallurgical analysis and the phase diagram. The growth rate of the reaction layer on the JLF-1 steel showed a parabolic rate law, and this trend indicated that the corrosion could be controlled by the diffusion process through the layer. The reaction layer formed in liquid Sn and Sn–20Li was identified as FeSn. The growth rate had a linear function with exposure time. The corrosion in Sn and Sn–20Li could be controlled by the interface reaction on the layer. The growth rate of the layer formed

  3. (Vapour + liquid) equilibria of the {l_brace}carbon dioxide + pentafluoroethane (HFC-125){r_brace} system and the {l_brace}carbon dioxide + dodecafluoro-2-methylpentan-3-one (NOVEC{sup TM}1230){r_brace} system

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Keesin [School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Im, Jihoon [School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Lee, Sukyung [Department of Safety Engineering, Seoul National University of Technology, Gongneung2-dong, Nowon-gu, Seoul 139-743 (Korea, Republic of); Kim, Hwayong [School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of)]. E-mail: hwayongk@snu.ac.kr

    2007-04-15

    Binary (vapour + liquid) equilibrium data were measured for the {l_brace}carbon dioxide + pentafluoroethane (HFC-125){r_brace} system at temperatures from 313.15 K to 333.15 K and the {l_brace}carbon dioxide + dodecafluoro-2-methylpentan-3-one (NOVEC{sup TM}1230){r_brace} system at temperatures from 313.15 K to 343.15 K. These experiments were carried out with a circulating-type apparatus with on-line gas chromatography. The experimental data were correlated well by the Peng-Robinson equation of state using the Wong-Sandler mixing rules.

  4. Tin oxide coating of aluminous porcelain by reactive ion plating.

    Science.gov (United States)

    McCrory, P V; Tinston, S; Piddock, V; Kelly, P; Combe, E C; Arnell, R D

    1991-06-01

    Alumina reinforced dental porcelain has been coated directly with tin oxide by reactive ion plating. Samples were prepared at different distances from the tin source in the ion plating rig. Tensile bond strengths of treated and untreated porcelain discs to a commercially available phosphate-methacrylate based dental cement were determined. Bond strengths of certain coated samples were found to be in excess of the cohesive strength of the porcelain substrates (greater than 7.8 MPa), whereas untreated porcelain achieved an average bond strength of only 3.4 MPa. The microstructures of coatings produced under conditions similar to those which yielded the maximum bond strength were examined in a scanning electron microscope and were found to be approximately 0.5 microns thick. It is believed that ion plating has great potential for rendering inert ceramic surfaces capable of direct bonding to dental cements.

  5. Direct reaction experimental studies with beams of radioactive tin ions

    Energy Technology Data Exchange (ETDEWEB)

    Jones, K. L., E-mail: kgrzywac@utk.edu; Ayres, A.; Bey, A.; Burcher, S.; Cartegni, L.; Cerizza, G. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Ahn, S. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Allmond, J. M.; Beene, J. R.; Galindo-Uribarri, A.; Liang, J. F.; Nesaraja, C. D.; Pain, S. D.; Radford, D. C.; Schmitt, K. T.; Smith, M. S.; Stracener, D. W.; Varner, R. L. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Bardayan, D. W. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Baugher, T. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903 (United States); and others

    2015-10-15

    The tin chain of isotopes provides a unique region in which to investigate the evolution of single-particle structure, spreading from N = 50 at {sup 100}Sn, through 10 stable isotopes and the N = 82 shell closure at {sup 132}Sn out into the r-process path. Direct reactions performed on radioactive ion beams are sensitive spectroscopic tools for studying exotic nuclei. Here we present one experiment knocking out neutrons from tin isotopes that are already neutron deficient and two reactions that add a neutron to neutron-rich {sup 130}Sn. Both techniques rely on selective particle identification and the measurement of γ rays in coincidence with charged ions. We present the goals of the two experiments and the particle identification for the channels of interest. The final results will be presented in future publications.

  6. Photoelectricalchemical characteristics of brush plated tin sulfide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, B.; Jayachandran, M. [Central Electrochemical Research Inst., Karaikudi (India); Sanjeeviraja, C. [Alagappa Univ., Karaikudi (India). Dept. of Physics

    2003-08-01

    Thin films of tin sulfide find wide applications in optoelectronic devices and window materials for heterojunction solar cells. Thin films of p-SnS were brush plated onto tin oxide coated glass substrates from aqueous solution containing SnCl{sub 2} and Na{sub 2}S{sub 2}O{sub 3}. Deposits have been characterized with XRD and SEM for structural analysis. Hot probe method showed invariably p-type nature for all the brush plated SnS films. The variation of space charge capacitance, C{sub sc} with applied potential, V, was recorded for the PEC cell with p-SnS/Fe{sup 3+}, Fe{sup 2+}/Pt system. The spectral response of the PEC cell formed with SnS photoelectrode was studied and reported. (author)

  7. Photoelectrochemical characteristics of brush plated tin sulfide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, B.; Jayachandran, M. [Central Electrochemical Research Institute, Karaikudi 630 006 (India); Sanjeeviraja, C. [Department of Physics, Alagappa University, Karaikudi 630 006 (India)

    2003-08-01

    Thin films of tin sulfide find wide applications in optoelectronic devices and window materials for heterojunction solar cells. Thin films of p-SnS were brush plated onto tin oxide coated glass substrates from aqueous solution containing SnCl{sub 2} and Na{sub 2}S{sub 2}O{sub 3}. Deposits have been characterized with XRD and SEM for structural analysis. Hot probe method showed invariably p-type nature for all the brush plated SnS films. The variation of space charge capacitance, C{sub sc}, with applied potential, V, was recorded for the PEC cell with p-SnS/Fe{sup 3+}, Fe{sup 2+}/Pt system. The spectral response of the PEC cell formed with SnS photoelectrode was studied and reported.

  8. Direct Reaction Experimental Studies with Beams of Radioactive Tin Ions

    Energy Technology Data Exchange (ETDEWEB)

    Jones, K. L. [University of Tennessee, Knoxville (UTK); Ahn, S.H. [University of Tennessee, Knoxville (UTK); Allmond, James M [ORNL; Ayres, A. [University of Tennessee, Knoxville (UTK); Bardayan, Daniel W [ORNL; Baugher, T. [Michigan State University, East Lansing; Bazin, D. [Michigan State University, National Superconducting Cyclotron Laboratory (NSCL); Beene, James R [ORNL; Berryman, J. S. [Michigan State University, East Lansing; Bey, A. [University of Tennessee, Knoxville (UTK); Bingham, C. R. [University of Tennessee, Knoxville (UTK); Cartegni, L. [University of Tennessee, Knoxville (UTK); Chae, K. Y. [University of Tennessee, Knoxville (UTK)/Sungkyunkwan University, Korea; Cizewski, J. A. [Rutgers University; Gade, A. [Michigan State University, National Superconducting Cyclotron Laboratory (NSCL); Galindo-Uribarri, Alfredo {nmn} [ORNL; Garcia-Ruiz, R.F. [Instituut voor Kernen Stralingsfysica, KU Leuven, B-3001, Leuven, Belgium; Grzywacz, Robert Kazimierz [ORNL; Howard, Meredith E [ORNL; Kozub, R. L. [Tennessee Technological University (TTU); Liang, J Felix [ORNL; Manning, Brett M [ORNL; Matos, M. [Louisiana State University; McDaniel, S. [Michigan State University, East Lansing; Miller, D. [University of Tennessee, Knoxville (UTK); Nesaraja, Caroline D [ORNL; O' Malley, Patrick [Rutgers University; Padgett, S [University of Tennessee, Knoxville (UTK); Padilla-Rodal, Elizabeth [Universidad Nacional Autonoma de Mexico (UNAM); Pain, Steven D [ORNL; Pittman, S. T. [University of Tennessee (UTK) and Oak Ridge National Laboratory (ORNL); Radford, David C [ORNL; Ratkiewicz, Andrew J [ORNL; Schmitt, Kyle [ORNL; Smith, Michael Scott [ORNL; Stracener, Daniel W [ORNL; Stroberg, S. [Michigan State University, East Lansing; Tostevin, Jeffrey A [ORNL; Varner Jr, Robert L [ORNL; Weisshaar, D. [Michigan State University, East Lansing; Wimmer, K. [Michigan State University, National Superconducting Cyclotron Laboratory (NSCL)/Central Michigan University; Winkler, R. [Michigan State University, East Lansing

    2015-01-01

    The tin chain of isotopes provides a unique region in which to investigate the evolution of single-particle structure, spreading from N = 50 at Sn-100, through 10 stable isotopes and the N = 82 shell closure at Sn-132 out into the r-process path. Direct reactions performed on radioactive ion beams are sensitive spectroscopic tools for studying exotic nuclei. Here we present one experiment knocking out neutrons from tin isotopes that are already neutron deficient and two reactions that add a neutron to neutron-rich Sn-130. Both techniques rely on selective particle identification and the measurement of gamma rays in coincidence with charged ions. We present the goals of the two experiments and the particle identification for the channels of interest. The final results will be presented in future publications.

  9. Polymorphic transition of tin under shock wave compression: Experimental results

    Directory of Open Access Journals (Sweden)

    Sinatti F.

    2012-08-01

    Full Text Available In this work, the β-bct polymorphic transition in tin is investigated by means of plate impact experiments. The Sn target surface is observed in a partially released state obtained thanks to a transparent lithium fluoride (LiF anvil. We report both measurements of interface velocity and temperature obtained using Photon Doppler Velocimetry and IR optical pyrometer on shock-loaded tin from 8 to 16 GPa. We show that the Mabire Model EOS associated to the SCG plasticity model provides an overall good estimate of the velocity profiles. However, depnding on the shock amplitude, its prediction of the temperature profile may be less satisfactory, hence underlining the need for future improvements in terms of phase transition kinetics description.

  10. Diffusion of tin in germanium: A GGA+U approach

    KAUST Repository

    Tahini, H. A.

    2011-10-18

    Density functional theory calculations are used to investigate the formation and diffusion of tin-vacancy pairs (SnV) in germanium(Ge). Depending upon the Fermi energy, SnV pairs can form in neutral, singly negative, or doubly negative charged states. The activation energies of diffusion, also as function of the Fermi energy, are calculated to lie between 2.48-3.65 eV, in agreement with and providing an interpretation of available experimental work.

  11. Structure Characterization of Semiconducting Tin and Tungsten Mixed Oxides

    Science.gov (United States)

    Solis, J. L.; Frantti, J.; Lantto, V.; Häggström, L.; Wikner, M.

    Mixed-oxide powders of tin and tungsten were made by heating various mixtures of SnO and WO3 powders, corresponding to the nominal formula SnxWO3+x with x between 0.5 and 2.0, in an argon atmosphere at 600°C for 15 hours. The α-SnWO4 phase was the result of heating of an equi-molar mixture of SnO and WO3 powders. In addition to 119Sn Mössbauer experiments, X-ray diffraction and Raman spectroscopy were used to study the phase structures of the mixed-oxide powders. Mössbauer spectra from all samples show a small peak at ∽0mm/s from phase(s) like rutile SnO2, and a larger peak doublet centred at ∽3.4mm/s from the α-SnWO4 phase, where tin is in the form Sn4+ and Sn2+, respectively. Another peak doublet centred at ∽3.0mm/s was needed to obtain reasonable fits for samples with x≥1.3. This doublet originates from an undocumented phase where tin is also in the divalent form Sn2+. 119Sn Mössbauer spectroscopy made it possible to reveal the relative amounts of the two valence states of tin in the mixed-oxide structures. Raman spectroscopy as the other probe for ``local'' structures was insensitive to reveal the changes in the phase structures between different mixed-oxide samples up to x=1.72, but an extra peak at ∽890cm-1 in the Raman spectrum from the sample with x=2.0 indicates also the presence of the undocumented phase.

  12. ORGANO—TIN POLYMERS:SYNTHESIS,PROPERTIES AND APPLICATION

    Institute of Scientific and Technical Information of China (English)

    WEIRongbao; CheRongrui; 等

    1993-01-01

    Through interfacial poly-condensation of R2SnCl2 (R=Me,Bu) with various diacids,diphenols (diols),diamines,amino-acids,hydroxyacids,urea,or thiourea,a series of organo-tin poly-esters,poly-ethers,poly-amines,poly-amine-esters,poly-ureas,poly-thioureas were prepared,and characterised altogether totalling 100 polymers,among which 91 are previously unreported.The synthesized polymers have a potential as a thermostabilizer in PVC products.

  13. Palladium–tin catalysts on conducting polymers for nitrate removal

    OpenAIRE

    Dodouche, Ibrahim; Barbosa, Danns Pereira; Varela, Maria do Carmo Rangel Santos; Epron, Florence

    2009-01-01

    Trabalho completo: acesso restrito, p. 50–55 Palladium–tin catalysts were prepared by successive impregnation or co-impregnation onto polyaniline and polypyrrole. The catalytic tests showed that this type of catalyst is active for nitrate reduction. The use of polymer support improves the selectivity of the catalyst toward nitrogen formation compared to a classical support, and avoids the apparition of intermediate nitrite. These better performances of the catalysts supported on electroact...

  14. Patterning Cells on Optically Transparent Indium Tin Oxide Electrodes

    OpenAIRE

    Shah, Sunny; Revzin, Alexander

    2007-01-01

    The ability to exercise precise spatial and temporal control over cell-surface interactions is an important prerequisite to the assembly of multi-cellular constructs serving as in vitro mimics of native tissues. In this study, photolithography and wet etching techniques were used to fabricate individually addressable indium tin oxide (ITO) electrodes on glass substrates. The glass substrates containing ITO microelectrodes were modified with poly(ethylene glycol) (PEG) silane to make them pr...

  15. Micropatterning of Proteins and Mammalian Cells on Indium Tin Oxide

    OpenAIRE

    Shah, Sunny S.; Howland, Michael C.; Chen, Li-Jung; Silangcruz, Jaime; Verkhoturov, Stanislav V.; Schweikert, Emile A.; Parikh, Atul N.; Revzin, Alexander

    2009-01-01

    This paper describes a novel surface engineering approach that combines oxygen plasma treatment and electrochemical activation to create micropatterned cocultures on indium tin oxide (ITO) substrates. In this approach, photoresist was patterned onto an ITO substrate modified with poly(ethylene) glycol (PEG) silane. The photoresist served as a stencil during exposure of the surface to oxygen plasma. Upon incubation with collagen (I) solution and removal of the photoresist, the ITO substrate co...

  16. Crystal structure of tin(II perchlorate trihydrate

    Directory of Open Access Journals (Sweden)

    Erik Hennings

    2014-12-01

    Full Text Available The title compound, [Sn(H2O3](ClO42, was synthesized by the redox reaction of copper(II perchlorate hexahydrate and metallic tin in perchloric acid. Both the trigonal–pyramidal [Sn(H2O3]2+ cations and tetrahedral perchlorate anions lie on crystallographic threefold axes. In the crystal, the cations are linked to the anions by O—H...O hydrogen bonds, generating (001 sheets.

  17. Antifriction and wear resistance of tin diffusion coating on brass

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    After brass is coated with tin, heat treatment makes the coating metal Sn and the substrate metal lic elements Cu and Zn diffuse with each other. This causes the c oating composition to be changed and the interface to be strengthened. The diffusion coating with a multiphase structure formed by this process has excellent properties of antifriction and wear resistance. With the aid of scanning electron microscopy, electronic probe microanalysis and X-ray diffraction, the mechanism of the properties is discussed.

  18. Field Emission from Carbon Nanotube/Tin Composite

    Institute of Scientific and Technical Information of China (English)

    ZHAO Bo; ZHANG Ya-fei

    2009-01-01

    Powder metallurgy was used to fabricate carbon nanotube (CNT) field emission cathodes. CNTs and tin (Sn) powder were blended, compacted and sintered. After polishing and etching, CNTs were exposed and protruded from the metal surface. CNTs were embedded into the Sn matrix, which acted as stable field emitters. The J-E curves show excellent field emission properties, such as low turn-on field of 2.8 V/μm, high emission current density and good current stability.

  19. Tin (Sn) for enhancing performance in silicon CMOS

    KAUST Repository

    Hussain, Aftab M.

    2013-10-01

    We study a group IV element: tin (Sn) by integrating it into silicon lattice, to enhance the performance of silicon CMOS. We have evaluated the electrical properties of the SiSn lattice by performing simulations using First-principle studies, followed by experimental device fabrication and characterization. We fabricated high-κ/metal gate based Metal-Oxide-Semiconductor capacitors (MOSCAPs) using SiSn as channel material to study the impact of Sn integration into silicon. © 2013 IEEE.

  20. Temperature Modeling of the Molten Glass in Tin Bath

    Institute of Scientific and Technical Information of China (English)

    WEI Zhihua; CHEN Jinshu; NIE Yingsong

    2009-01-01

    Based on the experimental investigation by quantitative analysis, temperature fields of the molten glass in tin bath were numerically simulated by the finite elememt method. The ex-perimental results show that the cooling rate of glass is directly proportional to the draught speed, but inversely proportional to the thickness of the glass. This model lays the foundation for computer simulation system about float glass.