WorldWideScience

Sample records for boron 18

  1. Boron

    Science.gov (United States)

    ... an eye wash. Boron was used as a food preservative between 1870 and 1920, and during World Wars ... chemical symbol), B (symbole chimique), Borate, Borate de Sodium, Borates, Bore, Boric Acid, Boric Anhydride, Boric Tartrate, ...

  2. All-boron analogues of aromatic hydrocarbons: B17- and B18-

    Science.gov (United States)

    Sergeeva, Alina P.; Averkiev, Boris B.; Zhai, Hua-Jin; Boldyrev, Alexander I.; Wang, Lai-Sheng

    2011-06-01

    We have investigated the structural and electronic properties of the B17- and B18- clusters using photoelectron spectroscopy (PES) and ab initio calculations. The adiabatic electron detachment energies of B17- and B18- are measured to be 4.23 ± 0.02 and 3.53 ± 0.05 eV, respectively. Calculated electron detachment energies are compared with experimental data, confirming the presence of one planar C2v (1A1) isomer for B17- and two nearly isoenergetic quasi-planar C3v (2A1) and Cs (2A') isomers for B18-. The stability and planarity/quasi-planarity of B17- and B18- are ascribed to σ- and π-aromaticity. Chemical bonding analyses reveal that the nature of π-bonding in B17- and B18- is similar to that in the recently elucidated B162- and B19- clusters, respectively. The planar B17- cluster can be considered as an all-boron analogue of naphthalene, whereas the π-bonding in the quasi-planar B18- is reminiscent of that in coronene.

  3. Positron emission tomography and [{sup 18}F]BPA: A perspective application to assess tumour extraction of boron in BNCT

    Energy Technology Data Exchange (ETDEWEB)

    Menichetti, L. [Department of PET and Radiopharmaceutical Chemistry, C.N.R. Institute of Clinical Physiology, Pisa (Italy)], E-mail: luca.menichetti@ifc.cnr.it; Cionini, L. [Unit of Radiotherapy, AOUP-University Hospital, Pisa (Italy); Sauerwein, W.A. [Department of Radiation Oncology, University Duisburg-Essen, University Hospital Essen (Germany); Altieri, S. [University of Pavia, Department of Nuclear Physics, Pavia (Italy); Solin, O.; Minn, H. [Turku PET Centre, University of Turku (Finland); Salvadori, P.A. [Department of PET and Radiopharmaceutical Chemistry, C.N.R. Institute of Clinical Physiology, Pisa (Italy)

    2009-07-15

    Positron emission tomography (PET) has become a key imaging tool in clinical practice and biomedical research to quantify and study biochemical processes in vivo. Physiologically active compounds are tagged with positron emitters (e.g. {sup 18}F, {sup 11}C, {sup 124}I) while maintaining their biological properties, and are administered intravenously in tracer amounts (10{sup -9}-10{sup -12} M quantities). The recent physical integration of PET and computed tomography (CT) in hybrid PET/CT scanners allows a combined anatomical and functional imaging: nowadays PET molecular imaging is emerging as powerful pharmacological tool in oncology, neurology and for treatment planning as guidance for radiation therapy. The in vivo pharmacokinetics of boron carrier for BNCT and the quantification of {sup 10}B in living tissue were performed by PET in the late nineties using compartmental models based on PET data. Nowadays PET and PET/CT have been used to address the issue of pharmacokinetic, metabolism and accumulation of BPA in target tissue. The added value of the use of L-[{sup 18}F]FBPA and PET/CT in BNCT is to provide key data on the tumour extraction of {sup 10}B-BPA versus normal tissue and to predict the efficacy of the treatment based on a single-study patient analysis. Due to the complexity of a binary treatment like BNCT, the role of PET/CT is currently to design new criteria for patient enrolment in treatment protocols: the L-[{sup 18}F]BPA/PET methodology could be considered as an important tool in newly designed clinical trials to better estimate the concentration ratio of BPA in the tumour as compared to neighbouring normal tissues. Based on these values for individual patients the decision could be made whether BNCT treatment could be advantageous due to a selective accumulation of BPA in an individual tumour. This approach, applicable in different tumour entities like melanoma, glioblastoma and head and neck malignancies, make this methodology as reliable

  4. A critical study on borosilicate glassware and silica-based QMA's in nucleophilic substitution with [{sup 18}F]fluoride: influence of aluminum, boron and silicon on the reactivity of [{sup 18}F]fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Svadberg, A., E-mail: anders.svadberg@uit.n [University of Tromso, Institute of Pharmacy, Department of Pharmaceutics and Biopharmaceutics, N-9037 Tromso (Norway); Clarke, A.; Dyrstad, K.; Martinsen, I. [GE Healthcare MDx R and D, Nycoveien 2, NO-0401 Oslo (Norway); Hjelstuen, O.K. [University of Tromso, Institute of Pharmacy, Department of Pharmaceutics and Biopharmaceutics, N-9037 Tromso (Norway); GE Healthcare MDx R and D, Nycoveien 2, NO-0401 Oslo (Norway)

    2011-02-15

    Leachables of borosilicate glassware and silica-based anion exchange columns (QMAs) may influence nucleophilic substitution with [{sup 18}F]fluoride ([{sup 18}F]F{sup -}). Aluminum, boron and silicon, all constituents of borosilicate glass, were found as water soluble leachables in a typical PET synthesis setup. Relevant ranges of the leachable quantities were studied based on an experimental design, in which species of the three elements were added to the labeling of the precursor for anti-1-amino-3-[{sup 18}F]fluorocyclobutyl-1-carboxylic acid ([{sup 18}F]FACBC). Levels of 0.4-2 ppm aluminum as AlCl{sub 3} had a strong negative influence on labeling yield while 4-20 ppm of boron as KBO{sub 2} and 50-250 ppm of silicon as Na{sub 2}SiO{sub 3} did not have a significant impact. Interesting interaction effects between the elements were observed, where particularly KBO{sub 2} reduced the negative effect of AlCl{sub 3} on labeling yield. It can be concluded that leachables of borosilicate glassware easily can influence nucleophilic substitution with n.c.a. [{sup 18}F]F{sup -} and give variable yields.

  5. A critical study on borosilicate glassware and silica-based QMA's in nucleophilic substitution with [18F]fluoride: influence of aluminum, boron and silicon on the reactivity of [18F]fluoride.

    Science.gov (United States)

    Svadberg, A; Clarke, A; Dyrstad, K; Martinsen, I; Hjelstuen, O K

    2011-02-01

    Leachables of borosilicate glassware and silica-based anion exchange columns (QMAs) may influence nucleophilic substitution with [(18)F]fluoride ([(18)F]F(-)). Aluminum, boron and silicon, all constituents of borosilicate glass, were found as water soluble leachables in a typical PET synthesis setup. Relevant ranges of the leachable quantities were studied based on an experimental design, in which species of the three elements were added to the labeling of the precursor for anti-1-amino-3-[(18)F]fluorocyclobutyl-1-carboxylic acid ([(18)F]FACBC). Levels of 0.4-2 ppm aluminum as AlCl(3) had a strong negative influence on labeling yield while 4-20 ppm of boron as KBO(2) and 50-250 ppm of silicon as Na(2)SiO(3) did not have a significant impact. Interesting interaction effects between the elements were observed, where particularly KBO(2) reduced the negative effect of AlCl(3) on labeling yield. It can be concluded that leachables of borosilicate glassware easily can influence nucleophilic substitution with n.c.a. [(18)F]F(-) and give variable yields.

  6. Enhanced copper-mediated (18)F-fluorination of aryl boronic esters provides eight radiotracers for PET applications.

    Science.gov (United States)

    Preshlock, Sean; Calderwood, Samuel; Verhoog, Stefan; Tredwell, Matthew; Huiban, Mickael; Hienzsch, Antje; Gruber, Stefan; Wilson, Thomas C; Taylor, Nicholas J; Cailly, Thomas; Schedler, Michael; Collier, Thomas Lee; Passchier, Jan; Smits, René; Mollitor, Jan; Hoepping, Alexander; Mueller, Marco; Genicot, Christophe; Mercier, Joël; Gouverneur, Véronique

    2016-06-28

    [(18)F]FMTEB, [(18)F]FPEB, [(18)F]flumazenil, [(18)F]DAA1106, [(18)F]MFBG, [(18)F]FDOPA, [(18)F]FMT and [(18)F]FDA are prepared from the corresponding arylboronic esters and [(18)F]KF/K222 in the presence of Cu(OTf)2py4. The method was successfully applied using three radiosynthetic platforms, and up to 26 GBq of non-carrier added starting activity of (18)F-fluoride.

  7. Crystalline boron nitride aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Zettl, Alexander K.; Rousseas, Michael; Goldstein, Anna P.; Mickelson, William; Worsley, Marcus A.; Woo, Leta

    2017-04-04

    This disclosure provides methods and materials related to boron nitride aerogels. In one aspect, a material comprises an aerogel comprising boron nitride. The boron nitride has an ordered crystalline structure. The ordered crystalline structure may include atomic layers of hexagonal boron nitride lying on top of one another, with atoms contained in a first layer being superimposed on atoms contained in a second layer.

  8. Boronated mesophase pitch coke for lithium insertion

    Science.gov (United States)

    Frackowiak, E.; Machnikowski, J.; Kaczmarska, H.; Béguin, F.

    Boronated carbons from mesophase pitch have been used as materials for lithium storage in Li/carbon cells. Doping by boron has been realized by co-pyrolysis of coal tar pitch with the pyridine-borane complex. Amount of boron in mesocarbon microbeads (MCMB) varied from 1.4 to 1.8 wt.% affecting the texture of carbon. Optical microscopy and X-ray diffractograms have shown tendency to more disordered structure for boron-doped carbon. The values of specific reversible capacity ( x) varied from 0.7 to 1.1 depending significantly on the final temperature of pyrolysis (700-1150°C). The optimal charge/discharge performance was observed for boronated carbon heated at 1000°C.

  9. Boron doping a semiconductor particle

    Science.gov (United States)

    Stevens, Gary Don; Reynolds, Jeffrey Scott; Brown, Louanne Kay

    1998-06-09

    A method (10,30) of boron doping a semiconductor particle using boric acid to obtain a p-type doped particle. Either silicon spheres or silicon powder is mixed with a diluted solution of boric acid having a predetermined concentration. The spheres are dried (16), with the boron film then being driven (18) into the sphere. A melt procedure mixes the driven boron uniformly throughout the sphere. In the case of silicon powder, the powder is metered out (38) into piles and melted/fused (40) with an optical furnace. Both processes obtain a p-type doped silicon sphere with desired resistivity. Boric acid is not a restricted chemical, is inexpensive, and does not pose any special shipping, handling, or disposal requirements.

  10. Boron Nitride Nanotubes

    Science.gov (United States)

    Smith, Michael W. (Inventor); Jordan, Kevin (Inventor); Park, Cheol (Inventor)

    2012-01-01

    Boron nitride nanotubes are prepared by a process which includes: (a) creating a source of boron vapor; (b) mixing the boron vapor with nitrogen gas so that a mixture of boron vapor and nitrogen gas is present at a nucleation site, which is a surface, the nitrogen gas being provided at a pressure elevated above atmospheric, e.g., from greater than about 2 atmospheres up to about 250 atmospheres; and (c) harvesting boron nitride nanotubes, which are formed at the nucleation site.

  11. Boron nitride composites

    Energy Technology Data Exchange (ETDEWEB)

    Kuntz, Joshua D.; Ellsworth, German F.; Swenson, Fritz J.; Allen, Patrick G.

    2017-02-21

    According to one embodiment, a composite product includes: a matrix material including hexagonal boron nitride and one or more borate binders; and a plurality of cubic boron nitride particles dispersed in the matrix material. According to another embodiment, a composite product includes: a matrix material including hexagonal boron nitride and amorphous boron nitride; and a plurality of cubic boron nitride particles dispersed in the matrix material.

  12. Methods of forming boron nitride

    Science.gov (United States)

    Trowbridge, Tammy L; Wertsching, Alan K; Pinhero, Patrick J; Crandall, David L

    2015-03-03

    A method of forming a boron nitride. The method comprises contacting a metal article with a monomeric boron-nitrogen compound and converting the monomeric boron-nitrogen compound to a boron nitride. The boron nitride is formed on the same or a different metal article. The monomeric boron-nitrogen compound is borazine, cycloborazane, trimethylcycloborazane, polyborazylene, B-vinylborazine, poly(B-vinylborazine), or combinations thereof. The monomeric boron-nitrogen compound is polymerized to form the boron nitride by exposure to a temperature greater than approximately 100.degree. C. The boron nitride is amorphous boron nitride, hexagonal boron nitride, rhombohedral boron nitride, turbostratic boron nitride, wurzite boron nitride, combinations thereof, or boron nitride and carbon. A method of conditioning a ballistic weapon and a metal article coated with the monomeric boron-nitrogen compound are also disclosed.

  13. Boron nitride converted carbon fiber

    Science.gov (United States)

    Rousseas, Michael; Mickelson, William; Zettl, Alexander K.

    2016-04-05

    This disclosure provides systems, methods, and apparatus related to boron nitride converted carbon fiber. In one aspect, a method may include the operations of providing boron oxide and carbon fiber, heating the boron oxide to melt the boron oxide and heating the carbon fiber, mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide, and converting at least a portion of the carbon fiber to boron nitride.

  14. Boron in sillimanite.

    Science.gov (United States)

    Grew, E S; Hinthorne, J R

    1983-08-05

    Sillimanite in six granulite-facies, kornerupine-bearing rocks contains 0.035 to 0.43 percent B(2)O(3) and 0.02 to 0.23 percent MgO (by weight). Substitution of boron for silicon and magnesium for aluminum is coupled such that the ratio of magnesium to boron is about 0.5. Sillimanite incorporates more than 0.1 percent B(2)O(3) only at high temperatures in a boron-rich environment at very low partial pressures of water. In the amphibolite facies, the sillimanite boron contents are too low to appreciably affect the stability relations of sillimanite with kyanite and andalusite.

  15. Boron-Loaded Silicone Rubber Scintillators

    CERN Document Server

    Bell, Z W; Maya, L; Sloop, F V J

    2003-01-01

    Silicone rubber received attention as an alternative to polyvinyltoluene in applications in which the scintillator is exposed to high doses because of the increased resistance of the rubber to the formation of blue-absorbing color centers. Work by Bowen, et al., and Harmon, et al., demonstrated their properties under gamma/x-ray irradiation, and Bell, et al. have shown their response to thermal neutrons. This last work, however, provided an example of a silicone in which both the boron and the scintillator were contained in the rubber as solutes, a formulation which led to the precipitation of solids and sublimation of the boron component. In the present work we describe a scintillator in which the boron is chemically bonded to the siloxane and so avoids the problem of precipitation and loss of boron to sublimation. Material containing up to 18% boron, by weight, was prepared, mounted on photomultipliers, and exposed to both neutron and gamma fluxes. Pulse height spectra showing the neutron and photon respons...

  16. Mathematical modeling based evaluation and simulation of boron removal in bioelectrochemical systems.

    Science.gov (United States)

    Ping, Qingyun; Abu-Reesh, Ibrahim M; He, Zhen

    2016-11-01

    Boron removal is an arising issue in desalination plants due to boron's toxicity. As an emerging treatment concept, bioelectrochemical systems (BES) can achieve potentially cost-effective boron removal by taking advantage of cathodic-produced alkali. Prior studies have demonstrated successful removal of boron in microbial desalination cells (MDCs) and microbial fuel cells (MFCs), both of which are representative BES. Herein, mathematical models were developed to further evaluate boron removal by different BES and understand the key operating factors. The models delivered very good prediction of the boron concentration in the MDC integrated with Donnan Dialysis (DD) system with the lowest relative root-mean-square error (RMSE) of 0.00%; the predication of the MFC performance generated the highest RMSE of 18.55%. The model results of salt concentration, solution pH, and current generation were well fitted with experimental data for RMSE values mostly below 10%. The long term simulation of the MDC-DD system suggests that the accumulation of salt in the catholyte/stripping solution could have a positive impact on the removal of boron due to osmosis-driven convection. The current generation in the MDC may have little influence on the boron removal, while in the MFC the current-driven electromigration can contribute up to 40% of boron removal. Osmosis-induced convection transport of boron could be the major driving force for boron removal to a low level 22.2 in order to avoid boron accumulation in the anolyte effluent.

  17. Boron and the kidney.

    Science.gov (United States)

    Pahl, Madeleine V; Culver, B Dwight; Vaziri, Nosratola D

    2005-10-01

    Boron, the fifth element in the periodic table, is ubiquitous in nature. It is present in food and in surface and ocean waters, and is frequently used in industrial, cosmetic, and medical settings. Exposure to boron and related compounds has been recently implicated as a potential cause of chronic kidney disease in Southeast Asia. This observation prompted the present review of the published data on the effects of acute and chronic exposure to boron on renal function and structure in human beings and in experimental animals.

  18. Innovative method for boron extraction from iron ore containing boron

    Science.gov (United States)

    Wang, Guang; Wang, Jing-song; Yu, Xin-yun; Shen, Ying-feng; Zuo, Hai-bin; Xue, Qing-guo

    2016-03-01

    A novel process for boron enrichment and extraction from ludwigite based on iron nugget technology was proposed. The key steps of this novel process, which include boron and iron separation, crystallization of boron-rich slag, and elucidation of the boron extraction behavior of boron-rich slag by acid leaching, were performed at the laboratory. The results indicated that 95.7% of the total boron could be enriched into the slag phase, thereby forming a boron-rich slag during the iron and slag melting separation process. Suanite and kotoite were observed to be the boron-containing crystalline phases, and the boron extraction properties of the boron-rich slag depended on the amounts and grain sizes of these minerals. When the boron-rich slag was slowly cooled to 1100°C, the slag crystallized well and the efficiency of extraction of boron (EEB) of the slag was the highest observed in the present study. The boron extraction property of the slow-cooled boron-rich slag obtained in this study was much better than that of szaibelyite ore under the conditions of 80% of theoretical sulfuric acid amount, leaching time of 30 min, leaching temperature of 40°C, and liquid-to-solid ratio of 8 mL/g.

  19. Boron-Based Drug Design.

    Science.gov (United States)

    Ban, Hyun Seung; Nakamura, Hiroyuki

    2015-06-01

    The use of the element boron, which is not generally observed in a living body, possesses a high potential for the discovery of new biological activity in pharmaceutical drug design. In this account, we describe our recent developments in boron-based drug design, including boronic acid containing protein tyrosine kinase inhibitors, proteasome inhibitors, and tubulin polymerization inhibitors, and ortho-carborane-containing proteasome activators, hypoxia-inducible factor 1 inhibitors, and topoisomerase inhibitors. Furthermore, we applied a closo-dodecaborate as a water-soluble moiety as well as a boron-10 source for the design of boron carriers in boron neutron capture therapy, such as boronated porphyrins and boron lipids for a liposomal boron delivery system.

  20. Boron nitride composites

    Science.gov (United States)

    Kuntz, Joshua D.; Ellsworth, German F.; Swenson, Fritz J.; Allen, Patrick G.

    2016-02-16

    According to one embodiment, a composite product includes hexagonal boron nitride (hBN), and a plurality of cubic boron nitride (cBN) particles, wherein the plurality of cBN particles are dispersed in a matrix of the hBN. According to another embodiment, a composite product includes a plurality of cBN particles, and one or more borate-containing binders.

  1. Boron analysis for neutron capture therapy using particle-induced gamma-ray emission.

    Science.gov (United States)

    Nakai, Kei; Yamamoto, Yohei; Okamoto, Emiko; Yamamoto, Tetsuya; Yoshida, Fumiyo; Matsumura, Akira; Yamada, Naoto; Kitamura, Akane; Koka, Masashi; Satoh, Takahiro

    2015-12-01

    The neutron source of BNCT is currently changing from reactor to accelerator, but peripheral facilities such as a dose-planning system and blood boron analysis have still not been established. To evaluate the potential application of particle-induced gamma-ray emission (PIGE) for boron measurement in clinical boron neutron capture therapy, boronophenylalanine dissolved within a cell culture medium was measured using PIGE. PIGE detected 18 μgB/mL f-BPA in the culture medium, and all measurements of any given sample were taken within 20 min. Two hours of f-BPA exposure was required to create a boron distribution image. However, even though boron remained in the cells, the boron on the cell membrane could not be distinguished from the boron in the cytoplasm.

  2. Boronated liposome development and evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Hawthorne, M.F. [Univ. of California, Los Angeles, CA (United States)

    1995-11-01

    The boronated liposome development and evaluation effort consists of two separate tasks. The first is the development of new boron compounds and the synthesis of known boron species with BNCT potential. These compounds are then encapsulated within liposomes for the second task, biodistribution testing in tumor-bearing mice, which examines the potential for the liposomes and their contents to concentrate boron in cancerous tissues.

  3. In Vivo Boron Uptake Determination for Boron Neutron Capture Synovectomy

    Energy Technology Data Exchange (ETDEWEB)

    Binello, Emanuela; Shortkroff, Sonya; Yanch, Jacquelyn C.

    1999-06-06

    Boron neutron capture synovectomy (BNCS) has been proposed as a new application of the boron neutron capture reaction for the treatment of rheumatoid arthritis. In BNCS, a boron compound is injected into the joint space, where it is taken up by the synovium. The joint is then irradiated with neutrons of a desired energy range, inducing the boron neutron capture reaction in boron-loaded cells. Boron uptake by the synovium is an important parameter in the assessment of the potential of BNCS and in the determination of whether to proceed to animal irradiations for the testing of therapeutic efficacy. We present results from an investigation of boron uptake in vivo by the synovium.

  4. Effect of Boronization on Ohmic Plasmas in NSTX

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, C.H.; Kugel, H.; Maingi, R.; Wampler, W.R.; Blanchard, W.; Bell, M.; Bell, R.; LeBlanc, B.; Gates, D.; Kaye, S.; LaMarche, P.; Menard, J.; Mueller, D.; Na, H.K.; Nishino, N.; Paul, S.; Sabbagh, S.; Soukhanovskii, V.

    2001-03-27

    Boronization of the National Spherical Torus Experiment (NSTX) has enabled access to higher density, higher confinement plasmas. A glow discharge with 4 mTorr helium and 10% deuterated trimethyl boron deposited 1.7 g of boron on the plasma facing surfaces. Ion beam analysis of witness coupons showed a B+C areal density of 10 to the 18 (B+C) cm to the -2 corresponding to a film thickness of 100 nm. Subsequent ohmic discharges showed oxygen emission lines reduced by x15, carbon emission reduced by two and copper reduced to undetectable levels. After boronization, the plasma current flattop time increased by 70% enabling access to higher density, higher confinement plasmas.

  5. Boron contamination in drinking - irrigation water and boron removal methods

    Directory of Open Access Journals (Sweden)

    Meltem Bilici Başkan

    2014-03-01

    Full Text Available Boron presents in IIIA group of periodic table and has high ionization capacity. Therefore it is classified as a metalloid. Average boron concentration in earth's crust is 10 mg/kg. It presents in the environment as a salts of Ca, Na, and Mg. Boron reserves having high concentration and economical extent are found mostly in Turkey and in arid, volcanic and high hydrothermal activity regions of U.S. as compounds of boron attached to oxygen. Boron is an essential micronutrient for plants, although it may be toxic at higher levels. The range in which it is converted from a nutrient to a contaminant is quite narrow. Boron presents in water environment as a boric acid and rarely borate salts. The main boron sources, whose presence is detected in surface waters, are urban wastes and industrial wastes, which can come from a wide range of different activities as well as several chemical products used in agriculture. In Turkey, the most pollutant toxic element in drinking and irrigation water is boron. Therefore boron removal is very important in terms of human health and agricultural products in high quality. Mainly boron removal methods from drinking water and irrigation water are ion exchange, ultrafiltration, reverse osmosis, and adsorption.

  6. Plasma boron and the effects of boron supplementation in males.

    Science.gov (United States)

    Green, N R; Ferrando, A A

    1994-11-01

    Recently, a proliferation of athletic supplements has been marketed touting boron as an ergogenic aid capable of increasing testosterone. The effect of boron supplementation was investigated in male bodybuilders. Ten male bodybuilders (aged 20 to 26) were given a 2.5-mg boron supplement, while nine male bodybuilders (aged 21 to 27) were given a placebo for 7 weeks. Plasma total and free testosterone, plasma boron, lean body mass, and strength measurements were determined on day 1 and day 49 of the study. A microwave digestion procedure followed by inductively coupled argon plasma spectroscopy was used for boron determination. Twelve subjects had boron values at or above the detection limit with median value of 25 ng/ml (16 ng/ml lower quartile and 33 ng/ml upper quartile). Of the ten subjects receiving boron supplements, six had an increase in their plasma boron. Analysis of variance indicated no significant effect of boron supplementation on any of the other dependent variables. Both groups demonstrated significant increases in total testosterone (p bodybuilding can increase total testosterone, lean body mass, and strength in lesser-trained bodybuilders, but boron supplementation affects these variables not at all.

  7. Bright prospects for boron

    NARCIS (Netherlands)

    Wassink, J.

    2012-01-01

    Professor Lis Nanver at Dimes has laid the foundation for a range of new photodetectors by creating a thin coating of boron on a silicon substrate. The sensors are used in ASML’s latest lithography machines and FEI’s most sensitive electron microscopes.

  8. Methods of producing continuous boron carbide fibers

    Energy Technology Data Exchange (ETDEWEB)

    Garnier, John E.; Griffith, George W.

    2015-12-01

    Methods of producing continuous boron carbide fibers. The method comprises reacting a continuous carbon fiber material and a boron oxide gas within a temperature range of from approximately 1400.degree. C. to approximately 2200.degree. C. Continuous boron carbide fibers, continuous fibers comprising boron carbide, and articles including at least a boron carbide coating are also disclosed.

  9. Oxidation of Silicon and Boron in Boron Containing Molten Iron

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new process of directly smelting boron steel from boron-containing pig iron has been established. The starting material boron-containing pig iron was obtained from ludwigite ore, which is very abundant in the eastern area of Liaoning Province of China. The experiment was performed in a medium-frequency induction furnace, and Fe2O3 powder was used as the oxidizing agent. The effects of temperature, addition of Fe2O3, basicity, stirring, and composition of melt on the oxidation of silicon and boron were investigated respectively. The results showed that silicon and boron were oxidized simultaneously and their oxidation ratio exceeded 90% at 1 400 ℃. The favorable oxidation temperature of silicon was about 1 300-1 350 C. High oxygen potential of slag and strong stirring enhanced the oxidation of silicon and boron.

  10. Structures, stability, mechanical and electronic properties of α-boron and α*-boron

    OpenAIRE

    Chaoyu He; J. X. Zhong

    2013-01-01

    The structures, stability, mechanical and electronic properties of α-boron and a promising metastable boron phase (α*-boron) have been studied by first-principles calculations. α-boron and α*-boron consist of equivalent icosahedra B12 clusters in different connecting configurations of “3S-6D-3S” and “2S-6D-4S”, respectively. The total energy calculations show that α*-boron is less stable than α-boron but more favorable than the well-known β-boron and γ-boron at zero pressure. Both α-boron and...

  11. Fivefold twinned boron carbide nanowires.

    Science.gov (United States)

    Fu, Xin; Jiang, Jun; Liu, Chao; Yuan, Jun

    2009-09-01

    Chemical composition and crystal structure of fivefold twinned boron carbide nanowires have been determined by electron energy-loss spectroscopy and electron diffraction. The fivefold cyclic twinning relationship is confirmed by systematic axial rotation electron diffraction. Detailed chemical analysis reveals a carbon-rich boron carbide phase. Such boron carbide nanowires are potentially interesting because of their intrinsic hardness and high temperature thermoelectric property. Together with other boron-rich compounds, they may form a set of multiply twinned nanowire systems where the misfit strain could be continuously tuned to influence their mechanical properties.

  12. Standard specification for boron-Based neutron absorbing material systems for use in nuclear spent fuel storage racks

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This specification defines criteria for boron-based neutron absorbing material systems used in racks in a pool environment for storage of nuclear light water reactor (LWR) spent-fuel assemblies or disassembled components to maintain sub-criticality in the storage rack system. 1.2 Boron-based neutron absorbing material systems normally consist of metallic boron or a chemical compound containing boron (for example, boron carbide, B4C) supported by a matrix of aluminum, steel, or other materials. 1.3 In a boron-based absorber, neutron absorption occurs primarily by the boron-10 isotope that is present in natural boron to the extent of 18.3 ± 0.2 % by weight (depending upon the geological origin of the boron). Boron, enriched in boron-10 could also be used. 1.4 The materials systems described herein shall be functional – that is always be capable to maintain a B10 areal density such that subcriticality Keff <0.95 or Keff <0.98 or Keff < 1.0 depending on the design specification for the service...

  13. Removing Boron from an Aqueous Solution Using Turmeric Extract-Aided Coagulation-Flocculation

    Directory of Open Access Journals (Sweden)

    Azhar Abdul Halim

    2012-01-01

    Full Text Available Problem statement: Boron exists in an environment naturally either through weathering of rocks or volcanic activity but due to anthropogenic activity, boron had been distributed widely into our surroundings. Boron was a problematic pollutant due to the difficulty to remove it from the water. Turmeric which had been widely used as a spice and traditional medicine, were investigated to determine its capabilities to aid in coagulation-flocculation process to remove boron. Optimizing coagulation-flocculation process might be effective to remove boron to a lower concentration. Approach: In this study, the optimum parameter for pH, dose of aluminium sulfate (alum and a dose of turmeric extract were determined by conducting a set of jar test experiment. The coagulation-flocculation process was performed to study the effectiveness of the turmeric extract as a coagulant aid in boron removal. Results: The result demonstrated that coagulation-flocculation process with the aid of turmeric extract can remove boron effectively at optimum conditions rather than coagulation-flocculation process without the aid of turmeric extract. The optimum conditions for boron removal were achieved at pH 7, an alum dosage of 18, 367 mg L-1 and turmeric extract dosage of 82 mg L-1. Conclusion/Recommendations: Result showed that removal of boron depends on pH, alum dosage and turmeric extract dosage. The boron removal percentage of the aqueous solution using the coagulation-flocculation process aided by the addition of turmeric extract and without the addition of turmeric extract were 95 and 62%, respectively. In addition, there was a significance difference between both processes. Turmeric extract as a coagulant aid demonstrated promising performance in boron removal and can be used as an alternative treatment to treat boron-containing wastewater.

  14. Functionalized boron nitride nanotubes

    Science.gov (United States)

    Sainsbury, Toby; Ikuno, Takashi; Zettl, Alexander K

    2014-04-22

    A plasma treatment has been used to modify the surface of BNNTs. In one example, the surface of the BNNT has been modified using ammonia plasma to include amine functional groups. Amine functionalization allows BNNTs to be soluble in chloroform, which had not been possible previously. Further functionalization of amine-functionalized BNNTs with thiol-terminated organic molecules has also been demonstrated. Gold nanoparticles have been self-assembled at the surface of both amine- and thiol-functionalized boron nitride Nanotubes (BNNTs) in solution. This approach constitutes a basis for the preparation of highly functionalized BNNTs and for their utilization as nanoscale templates for assembly and integration with other nanoscale materials.

  15. Chronic boron exposure and human semen parameters.

    Science.gov (United States)

    Robbins, Wendie A; Xun, Lin; Jia, Juan; Kennedy, Nola; Elashoff, David A; Ping, Liu

    2010-04-01

    Boron found as borates in soil, food, and water has important industrial and medical applications. A panel reviewing NTP reproductive toxicants identified boric acid as high priority for occupational studies to determine safe versus adverse reproductive effects. To address this, we collected boron exposure/dose measures in workplace inhalable dust, dietary food/fluids, blood, semen, and urine from boron workers and two comparison worker groups (n=192) over three months and determined correlations between boron and semen parameters (total sperm count, sperm concentration, motility, morphology, DNA breakage, apoptosis and aneuploidy). Blood boron averaged 499.2 ppb for boron workers, 96.1 and 47.9 ppb for workers from high and low environmental boron areas (pBoron concentrated in seminal fluid. No significant correlations were found between blood or urine boron and adverse semen parameters. Exposures did not reach those causing adverse effects published in animal toxicology work but exceeded those previously published for boron occupational groups.

  16. Enhanced diffusion of oxygen depending on Fermi level position in heavily boron-doped silicon

    Energy Technology Data Exchange (ETDEWEB)

    Torigoe, Kazuhisa, E-mail: ktorigoe@sumcosi.com; Fujise, Jun; Ono, Toshiaki [Technology Division, Advanced Evaluation and Technology Development Department, SUMCO Corporation, 1-52 Kubara, Yamashiro-cho, Imari, Saga 849-4256 (Japan); Nakamura, Kozo [Department of Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197 (Japan)

    2014-11-21

    The enhanced diffusivity of oxygen in heavily boron doped silicon was obtained by analyzing oxygen out-diffusion profile changes found at the interface between a lightly boron-doped silicon epitaxial layer and a heavily boron-doped silicon substrate by secondary ion mass spectrometry. It was found that the diffusivity is proportional to the square root of boron concentration in the range of 10{sup 18 }cm{sup −3}–10{sup 19 }cm{sup −3} at temperatures from 750 °C to 950 °C. The model based on the diffusion of oxygen dimers in double positive charge state could explain the enhanced diffusion. We have concluded that oxygen diffusion enhanced in heavily boron-doped silicon is attributed to oxygen dimers ionized depending on Fermi level position.

  17. Mechanical properties and stabilities of α-boron monolayers.

    Science.gov (United States)

    Peng, Qing; Han, Liang; Wen, Xiaodong; Liu, Sheng; Chen, Zhongfang; Lian, Jie; De, Suvranu

    2015-01-21

    We investigate the mechanical properties and stabilities of planar α-boron monolayers under various large strains using density functional theory (DFT). α-Boron has a high in-plane stiffness, about 2/3 of that of graphene, which suggests that α-boron is four times as strong as iron. Potential profiles and stress-strain curves indicate that a free standing α-boron monolayer can sustain large tensile strains, up to 0.12, 0.16, and 0.18 for armchair, zigzag, and biaxial deformations, respectively. Third, fourth, and fifth order elastic constants are indispensable for accurate modeling of the mechanical properties under strains larger than 0.02, 0.06, and 0.08 respectively. Second order elastic constants, including in-plane stiffness, are predicted to monotonically increase with pressure, while the trend of Poisson's ratio is reversed. The surface sound speeds of both the compressional and shear waves increase with pressure. The ratio of these two sound speeds increases with the increase of pressure and converges to a value of 2.5. Our results imply that α-boron monolayers are mechanically stable under various large strains and have advanced mechanical properties - high strength and high flexibility.

  18. Rapid accurate isotopic measurements on boron in boric acid and boron carbide.

    Science.gov (United States)

    Duchateau, N L; Verbruggen, A; Hendrickx, F; De Bièvre, P

    1986-04-01

    A procedure is described whereby rapid and accurate isotopic measurements can be performed on boron in boric acid and boron carbide after fusion of these compounds with calcium carbonate. It allows the determination of the isotopic composition of boron in boric acid and boron carbide and the direct assay of boron or the (10)B isotope in boron carbide by isotope-dilution mass spectrometry.

  19. A new and effective approach to boron removal by using novel boron-specific fungi isolated from boron mining wastewater.

    Science.gov (United States)

    Taştan, Burcu Ertit; Çakir, Dilara Nur; Dönmez, Gönül

    2016-01-01

    Boron-resistant fungi were isolated from the wastewater of a boron mine in Turkey. Boron removal efficiencies of Penicillium crustosum and Rhodotorula mucilaginosa were detected in different media compositions. Minimal Salt Medium (MSM) and two different waste media containing molasses (WM-1) or whey + molasses (WM-2) were tested to make this process cost effective when scaled up. Both isolates achieved high boron removal yields at the highest boron concentrations tested in MSM and WM-1. The maximum boron removal yield by P. crustosum was 45.68% at 33.95 mg l(-1) initial boron concentration in MSM, and was 38.97% at 42.76 mg l(-1) boron for R. mucilaginosa, which seemed to offer an economically feasible method of removing boron from the effluents.

  20. Boron deprivation decreases liver S-adenosylmethionine and spermidine and increases plasma homocysteine and cysteine in rats.

    Science.gov (United States)

    Nielsen, Forrest Harold

    2009-01-01

    Two experiments were conducted with weanling Sprague-Dawley rats to determine whether changes in S-adenosylmethionine utilization or metabolism contribute to the diverse responses to boron deprivation. In both experiments, four treatment groups of 15 male rats were fed ground corn-casein based diets that contained an average of 0.05 mg (experiment 1) or 0.15 mg (experiment 2) boron/kg. In experiment 2, some ground corn was replaced by sucrose and fructose to increase oxidative stress. The dietary variables were supplemental 0 (boron-deprived) or 3 (boron-adequate) mg boron/kg and different fat sources (can affect the response to boron) of 75 g corn oil/kg or 65 g fish (menhaden) oil/kg plus 10 linoleic acid/kg. When euthanized at age 20 (experiment 1) and 18 (experiment 2) weeks, rats fed the low-boron diet were considered boron-deprived because they had decreased boron concentrations in femur and kidney. Boron deprivation regardless of dietary oil increased plasma cysteine and homocysteine and decreased liver S-adenosylmethionine, S-adenosylhomocysteine, and spermidine. Plasma concentration of 8-iso-prostaglandin F2alpha (indicator of oxidative stress) was not affected by boron, but was decreased by feeding fish oil instead of corn oil. Fish oil instead of corn oil decreased S-adenosylmethionine, increased spermidine, and did not affect S-adenosylhomocysteine concentrations in liver. Additionally, fish oil versus corn oil did not affect plasma homocysteine in experiment 1, and slightly increased it in experiment 2. The findings suggest that boron is bioactive through affecting the formation or utilization of S-adenosylmethionine. Dietary fatty acid composition also affects S-adenosylmethionine formation or utilization, but apparently through a mechanism different from that of boron.

  1. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

    Ashish Jain; C Ghosh; T R Ravindran; S Anthonysamy; R Divakar; E Mohandas; G S Gupta

    2013-12-01

    Structural characterization of electrodeposited boron was carried out by using transmission electron microscopy and Raman spectroscopy. Electron diffraction and phase contrast imaging were carried out by using transmission electron microscopy. Phase identification was done based on the analysis of electron diffraction patterns and the power spectrum calculated from the lattice images from thin regions of the sample. Raman spectroscopic examination was carried out to study the nature of bonding and the allotropic form of boron obtained after electrodeposition. The results obtained from transmission electron microscopy showed the presence of nanocrystallites embedded in an amorphous mass of boron. Raman microscopic studies showed that amorphous boron could be converted to its crystalline form at high temperatures.

  2. Combustion of boron containing compositions

    Energy Technology Data Exchange (ETDEWEB)

    Frolov, Y.; Pivkina, A. [Institute of Chemical Physics, Russian Academy of Science, Moscow (Russian Federation)

    1996-12-31

    Boron is one of the most energetic components for explosives, propellants and for heterogeneous condensed systems in common. The combustion process of mixtures of boron with different oxidizers was studied. The burning rate, concentration combustion limits, the agglomeration and dispersion processes during reaction wave propagation were analysed in the respect of the percolation theory. The linear dependence of the burning rate on the contact surface value was demonstrated. The percolative model for the experimental results explanation is proposed. (authors) 5 refs.

  3. Boron diffusion in silicon devices

    Science.gov (United States)

    Rohatgi, Ajeet; Kim, Dong Seop; Nakayashiki, Kenta; Rounsaville, Brian

    2010-09-07

    Disclosed are various embodiments that include a process, an arrangement, and an apparatus for boron diffusion in a wafer. In one representative embodiment, a process is provided in which a boric oxide solution is applied to a surface of the wafer. Thereafter, the wafer is subjected to a fast heat ramp-up associated with a first heating cycle that results in a release of an amount of boron for diffusion into the wafer.

  4. Effect of boron carbide on primary crystallization of chromium cast iron

    Directory of Open Access Journals (Sweden)

    A. Studnicki

    2008-04-01

    Full Text Available In the paper results of the influence of boron carbide (B4C as inoculant of abrasion-resisting chromium cast iron (about 2,8% carbon and 18% chromium on primary crystallization researches are presented. Boron carbide dispersion was introduced at the bottom of pouring ladle before tap of liquid cast iron. In this investigations were used three different quantities of inoculant in amounts 0,1%; 0,2% and 0,3% with relation to bath weight. It has been demonstrated that such small additions of boron carbide change primary crystallization parameters, particularly temperature characteristic of process, their time and kinetics.

  5. Irradiation Effects in Fortiweld Steel Containing Different Boron Isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Grounes, M.

    1967-07-15

    Tensile specimens and miniature impact specimens of the low alloyed pressure vessel steel Fortiweld have been irradiated at 265 deg C in R2 to two neutron doses, 6.5 x 10{sup 18} n/cm{sup 2} (> 1 MeV) and 4 x 10{sup 19} n/cm{sup 2} (thermal) and also 9.0 x 10{sup 18} n/cm{sup 2} (> 1 MeV) and 6 x 10{sup 19} n/cm{sup 2} (thermal). Material from three laboratory melts, in which the boron consisted of {sup 10}B, {sup 11}B and natural boron respectively, were investigated. The results both of tensile tests and impact tests with miniature impact specimens show that the {sup 10}B-alloyed material was changed more and the {sup 11}B-alloyed material was changed less than the material containing natural boron. At the higher neutron dose the increase in yield strength (0.2 % offset yield strength) was 11 kg/mm in the {sup 10}B containing material compared to 5 kg/mm in the {sup 11}B-containing material. The decrease in total elongation was 5 and 0 percentage units respectively. The transition temperature was increased 190 deg C at the higher neutron dose in the {sup 10}B-alloyed material, 40 deg C in the {sup 11}B-alloyed material and 80 deg C in the material containing natural boron.

  6. Preparation of High Purity Amorphous Boron Powder

    Directory of Open Access Journals (Sweden)

    K.V. Tilekar

    2005-10-01

    Full Text Available Amorphous boron powder of high purity (92-94 % with a particle size of l-2 mm is preferred as a fuel for fuel-rich propellants for integrated rocket ramjets and for igniter formulations. Thispaper describes the studies on process optimisation of two processes, ie, oxidative roasting of boron (roasting boron in air and roasting boron with zinc in an inert medium for preparing high purity boron. Experimental studies reveal that roasting boron with zinc at optimised process conditions yields boron of purity more than 93 per cent, whereas oxidative roasting method yields boron of purity - 92 per cent. Oxidative roasting has comparative edge over the other processes owing to its ease of scale-up and simplicity

  7. Semiconducting boron carbides with better charge extraction through the addition of pyridine moieties

    Science.gov (United States)

    Echeverria, Elena; Dong, Bin; Peterson, George; Silva, Joseph P.; Wilson, Ethiyal R.; Sky Driver, M.; Jun, Young-Si; Stucky, Galen D.; Knight, Sean; Hofmann, Tino; Han, Zhong-Kang; Shao, Nan; Gao, Yi; Mei, Wai-Ning; Nastasi, Michael; Dowben, Peter A.; Kelber, Jeffry A.

    2016-09-01

    The plasma-enhanced chemical vapor (PECVD) co-deposition of pyridine and 1,2 dicarbadodecaborane, 1,2-B10C2H12 (orthocarborane) results in semiconducting boron carbide composite films with a significantly better charge extraction than plasma-enhanced chemical vapor deposited semiconducting boron carbide synthesized from orthocarborane alone. The PECVD pyridine/orthocarborane based semiconducting boron carbide composites, with pyridine/orthocarborane ratios ~3:1 or 9:1 exhibit indirect band gaps of 1.8 eV or 1.6 eV, respectively. These energies are less than the corresponding exciton energies of 2.0 eV-2.1 eV. The capacitance/voltage and current/voltage measurements indicate the hole carrier lifetimes for PECVD pyridine/orthocarborane based semiconducting boron carbide composites (3:1) films of ~350 µs compared to values of  ⩽35 µs for the PECVD semiconducting boron carbide films fabricated without pyridine. The hole carrier lifetime values are significantly longer than the initial exciton decay times in the region of ~0.05 ns and 0.27 ns for PECVD semiconducting boron carbide films with and without pyridine, respectively, as suggested by the time-resolved photoluminescence. These data indicate enhanced electron-hole separation and charge carrier lifetimes in PECVD pyridine/orthocarborane based semiconducting boron carbide and are consistent with the results of zero bias neutron voltaic measurements indicating significantly enhanced charge collection efficiency.

  8. Structures, stability, mechanical and electronic properties of a-boron and its twined brother a*-boron

    OpenAIRE

    He, Chaoyu; Zhong, Jianxin

    2013-01-01

    The structures, stability, mechanical and electronic properties of a-boron and its twined brother a*-boron have been studied by first-principles calculations. Both a-boron and a*-boron consist of equivalent icosahedra B12 clusters in different connecting configurations of "3S-6D-3S" and "2S-6D-4S", respectively. The total energy calculations show that a*-boron is less stable than a-boron but more favorable than beta-boron and Gamma-boron at zero pressure. Both a-boron and a*-boron are confirm...

  9. Boron Neutron Capture Therapy for Malignant Brain Tumors

    Science.gov (United States)

    MIYATAKE, Shin-Ichi; KAWABATA, Shinji; HIRAMATSU, Ryo; KUROIWA, Toshihiko; SUZUKI, Minoru; KONDO, Natsuko; ONO, Koji

    2016-01-01

    Boron neutron capture therapy (BNCT) is a biochemically targeted radiotherapy based on the nuclear capture and fission reactions that occur when non-radioactive boron-10, which is a constituent of natural elemental boron, is irradiated with low energy thermal neutrons to yield high linear energy transfer alpha particles and recoiling lithium-7 nuclei. Therefore, BNCT enables the application of a high dose of particle radiation selectively to tumor cells in which boron-10 compound has been accumulated. We applied BNCT using nuclear reactors for 167 cases of malignant brain tumors, including recurrent malignant gliomas, newly diagnosed malignant gliomas, and recurrent high-grade meningiomas from January 2002 to May 2014. Here, we review the principle and history of BNCT. In addition, we introduce fluoride-18-labeled boronophenylalanine positron emission tomography and the clinical results of BNCT for the above-mentioned malignant brain tumors. Finally, we discuss the recent development of accelerators producing epithermal neutron beams. This development could provide an alternative to the current use of specially modified nuclear reactors as a neutron source, and could allow BNCT to be performed in a hospital setting. PMID:27250576

  10. Boron Neutron Capture Therapy for Malignant Brain Tumors.

    Science.gov (United States)

    Miyatake, Shin-Ichi; Kawabata, Shinji; Hiramatsu, Ryo; Kuroiwa, Toshihiko; Suzuki, Minoru; Kondo, Natsuko; Ono, Koji

    2016-07-15

    Boron neutron capture therapy (BNCT) is a biochemically targeted radiotherapy based on the nuclear capture and fission reactions that occur when non-radioactive boron-10, which is a constituent of natural elemental boron, is irradiated with low energy thermal neutrons to yield high linear energy transfer alpha particles and recoiling lithium-7 nuclei. Therefore, BNCT enables the application of a high dose of particle radiation selectively to tumor cells in which boron-10 compound has been accumulated. We applied BNCT using nuclear reactors for 167 cases of malignant brain tumors, including recurrent malignant gliomas, newly diagnosed malignant gliomas, and recurrent high-grade meningiomas from January 2002 to May 2014. Here, we review the principle and history of BNCT. In addition, we introduce fluoride-18-labeled boronophenylalanine positron emission tomography and the clinical results of BNCT for the above-mentioned malignant brain tumors. Finally, we discuss the recent development of accelerators producing epithermal neutron beams. This development could provide an alternative to the current use of specially modified nuclear reactors as a neutron source, and could allow BNCT to be performed in a hospital setting.

  11. Thermal conductivity of boron carbides

    Science.gov (United States)

    Wood, C.; Emin, D.; Gray, P. E.

    1985-01-01

    Knowledge of the thermal conductivity of boron carbide is necessary to evaluate its potential for high-temperature thermoelectric energy conversion applications. Measurements have been conducted of the thermal diffusivity of hot-pressed boron carbide BxC samples as a function of composition (x in the range from 4 to 9), temperature (300-1700 K), and temperature cycling. These data, in concert with density and specific-heat data, yield the thermal conductivities of these materials. The results are discussed in terms of a structural model that has been previously advanced to explain the electronic transport data. Some novel mechanisms for thermal conduction are briefly discussed.

  12. Geochemical study of boron isotopes in the process of loess weathering

    Institute of Scientific and Technical Information of China (English)

    赵志琦; 刘丛强; 肖应凯; 郎赟超

    2003-01-01

    In this paper the boron contents and boron isotopic composition of acid-soluble phases in loess and paleosol samples are determined for the first time. The boron contents of acid-soluble phases in the Luochuan loess section (S0 -S2) vary within the range of (0.8-2.7)×10-6 and theirδ11B values vary from -1.8‰ to +18.6‰, mostly within the range of 0-+10‰. The boron contents andδ11B values of paleosol layers are higher than those of loess layers, especially in the loess layer S1. Varying chemical weathering intensity and loess adsorption capability are the main factors leading to the variations of boron contents and δ11B values of acid-soluble phases in the loess section. The variation of chemical weathering intensity in response to the variation of climatic conditions seems to be the main factor leading to the variations of boron contents andδ11B values of acid-soluble phases in the loess section.

  13. A Preliminary experimental study of the boron concentration in vapor and the isotopic A preliminary experimental study of the boron concentrationin vapor and the isotopic fractionation of boron betweenseawater and vapor during evaporation of seawater

    Institute of Scientific and Technical Information of China (English)

    XIAO; Yingkai

    2001-01-01

    [1]Gast, J. A., Thompson, T. G., Evaporation of boric acid from seawater, Tellus, 1959, 6: 344-347.[2]Nishimura, M., Tanaka, K., Seawater may not be a source of boron in the atmosphere, J. Geoph. Res., 1972, 77: 5239-5242.[3]Fogg, T. R., Duce, R. A., Fasching, J. L., Sampling and determination of boron in the atmosphere, Anal. Chem., 1983, 55:2179-2184.[4]Fogg, T. R., Duce, R. A., Boron in the troposphere: Distribution and fluxes, J. Geoph. Res., 1985, 90: 3781-3796.[5]Spivack, A. J., Berndt, M. E., Seyfreid, W. E., Boron isotope fractionation during supercritical phase separation, Geochim.Cosmochim. Acta, 1990, 54: 2337-2339.[6]Palmer, M. R., London, D., Morgan, G. B. et al., Experimental determination of fractionation of 11B/10B between tourma-line and aqueous vapor: A temperature and pressure-dependent isotopic system, Chem. Geol., 1992, 101:123-129.[7]Hervig, R. L., London, D., Morgan, G. B. et al., Large boron isotope fractionation between hydrous vapor and silicate meltat igneous temperatures, in the Seventh Annual V. M. Goldschmidt Conf., LPI Contribution No. 921, Houston: Lunar and Planetary Institute, 1997, 93-94.[8]Vengosh, A., Starinsky, A., Kolodny, Y. et al., Boron isotope variations during fractional evaporation of seawater: New constraints on the marine vs. nonmarine debate, Geology, 1992, 20: 799-802.[9]Zhang, X. P., Shi, Y. E, Yao, T. D., The variation characteristics of δo18O in precipitation in Northeastern Qing-Zhang Plateau, Science in China, Series B (in Chinese), 1995, 25(5): 540-547.[10]Yu, J. S., Yu, E J., Liu, D. P., The hydrogen and oxygen of isotopic compositions of meteoric water in the eastern part of China, Geochimica (in Chinese), 1987, (1): 22-26.[11]Xiao, Y. K., Xiao, Y., Swihart, G. H. et al., Separation of boron by ion exchange with boron specific resin, Acta Geosci.Sinica (in Chinese), 1997, 18: 286-289.[12]Kiss, E., Ion-exchange separation and spectrophotometric determination of

  14. Advanced microstructure of boron carbide.

    Science.gov (United States)

    Werheit, Helmut; Shalamberidze, Sulkhan

    2012-09-26

    The rhombohedral elementary cell of the complex boron carbide structure is composed of B(12) or B(11)C icosahedra and CBC, CBB or B□B (□, vacancy) linear arrangements, whose shares vary depending on the actual chemical compound. The evaluation of the IR phonon spectra of isotopically pure boron carbide yields the quantitative concentrations of these components within the homogeneity range. The structure formula of B(4.3)C at the carbon-rich limit of the homogeneity range is (B(11)C) (CBC)(0.91) (B□B)(0.09) (□, vacancy); and the actual structure formula of B(13)C(2) is (B(12))(0.5)(B(11)C)(0.5)(CBC)(0.65)(CBB)(0.16) (B□B)(0.19), and deviates fundamentally from (B(12))CBC, predicted by theory to be the energetically most favourable structure of boron carbide. In reality, it is the most distorted structure in the homogeneity range. The spectra of (nat)B(x)C make it evident that boron isotopes are not randomly distributed in the structure. However, doping with 2% silicon brings about a random distribution.

  15. Friction anisotropy in boronated graphite

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, N., E-mail: niranjan@igcar.gov.in [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Radhika, R. [Crystal Growth Centre, Anna University, Chennai (India); Kozakov, A.T. [Research Institute of Physics, Southern Federal University, Rostov-on-Don (Russian Federation); Pandian, R. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Chakravarty, S. [UGC-DAE CSR, Kalpakkam (India); Ravindran, T.R.; Dash, S.; Tyagi, A.K. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2015-01-01

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient.

  16. Jaguar Procedures for Detonation Behavior of Explosives Containing Boron

    Science.gov (United States)

    Stiel, L. I.; Baker, E. L.; Capellos, C.

    2009-12-01

    The Jaguar product library was expanded to include boron and boron containing products by analysis of Available Hugoniot and static volumetric data to obtain constants of the Murnaghan relationships for the components. Experimental melting points were also utilized to obtain the constants of the volumetric relationships for liquid boron and boron oxide. Detonation velocities for HMX—boron mixtures calculated with these relationships using Jaguar are in closer agreement with literature values at high initial densities for inert (unreacted) boron than with the completely reacted metal. These results indicate that the boron does not react near the detonation front or that boron mixtures exhibit eigenvalue detonation behavior (as shown by some aluminized explosives), with higher detonation velocities at the initial points. Analyses of calorimetric measurements for RDX—boron mixtures indicate that at high boron contents the formation of side products, including boron nitride and boron carbide, inhibits the detonation properties of the formulation.

  17. Modeling anthropogenic boron in groundwater flow and discharge at Volusia Blue Spring (Florida, USA)

    Science.gov (United States)

    Reed, Erin M.; Wang, Dingbao; Duranceau, Steven J.

    2016-08-01

    Volusia Blue Spring (VBS) is the largest spring along the St. Johns River in Florida (USA) and the spring pool is refuge for hundreds of manatees during winter months. However, the water quality of the spring flow has been degraded due to urbanization in the past few decades. A three-dimensional contaminant fate and transport model, utilizing MODFLOW-2000 and MT3DMS, was developed to simulate boron transport in the Upper Florida Aquifer, which sustains the VBS spring discharge. The VBS model relied on information and data related to natural water features, rainfall, land use, water use, treated wastewater discharge, septic tank effluent flows, and fertilizers as inputs to simulate boron transport. The model was calibrated against field-observed water levels, spring discharge, and analysis of boron in water samples. The calibrated VBS model yielded a root-mean-square-error value of 1.8 m for the head and 17.7 μg/L for boron concentrations within the springshed. Model results show that anthropogenic boron from surrounding urbanized areas contributes to the boron found at Volusia Blue Spring.

  18. Synthesis of Boron Nanowires, Nanotubes, and Nanosheets

    Directory of Open Access Journals (Sweden)

    Rajen B. Patel

    2015-01-01

    Full Text Available The synthesis of boron nanowires, nanotubes, and nanosheets using a thermal vapor deposition process is reported. This work confirms previous research and provides a new method capable of synthesizing boron nanomaterials. The materials were made by using various combinations of MgB2, Mg(BH42, MCM-41, NiB, and Fe wire. Unlike previously reported methods, a nanoparticle catalyst and a silicate substrate are not required for synthesis. Two types of boron nanowires, boron nanotubes, and boron nanosheets were made. Their morphology and chemical composition were determined through the use of scanning electron microscopy, transmission electron microscopy, and electron energy loss spectroscopy. These boron-based materials have potential for electronic and hydrogen storage applications.

  19. Prediction of boron carbon nitrogen phase diagram

    Science.gov (United States)

    Yao, Sanxi; Zhang, Hantao; Widom, Michael

    We studied the phase diagram of boron, carbon and nitrogen, including the boron-carbon and boron-nitrogen binaries and the boron-carbon-nitrogen ternary. Based on the idea of electron counting and using a technique of mixing similar primitive cells, we constructed many ''electron precise'' structures. First principles calculation is performed on these structures, with either zero or high pressures. For the BN binary, our calculation confirms that a rhmobohedral phase can be stablized at high pressure, consistent with some experimental results. For the BCN ternary, a new ground state structure is discovered and an Ising-like phase transition is suggested. Moreover, we modeled BCN ternary phase diagram and show continuous solubility from boron carbide to the boron subnitride phase.

  20. Biodistribution of sodium borocaptate (BSH) for boron neutron capture therapy (BNCT) in an oral cancer model.

    Science.gov (United States)

    Garabalino, Marcela A; Heber, Elisa M; Monti Hughes, Andrea; González, Sara J; Molinari, Ana J; Pozzi, Emiliano C C; Nievas, Susana; Itoiz, Maria E; Aromando, Romina F; Nigg, David W; Bauer, William; Trivillin, Verónica A; Schwint, Amanda E

    2013-08-01

    Boron neutron capture therapy (BNCT) is based on selective accumulation of ¹⁰B carriers in tumor followed by neutron irradiation. We previously proved the therapeutic success of BNCT mediated by the boron compounds boronophenylalanine and sodium decahydrodecaborate (GB-10) in the hamster cheek pouch oral cancer model. Based on the clinical relevance of the boron carrier sodium borocaptate (BSH) and the knowledge that the most effective way to optimize BNCT is to improve tumor boron targeting, the specific aim of this study was to perform biodistribution studies of BSH in the hamster cheek pouch oral cancer model and evaluate the feasibility of BNCT mediated by BSH at nuclear reactor RA-3. The general aim of these studies is to contribute to the knowledge of BNCT radiobiology and optimize BNCT for head and neck cancer. Sodium borocaptate (50 mg ¹⁰B/kg) was administered to tumor-bearing hamsters. Groups of 3-5 animals were killed humanely at nine time-points, 3-12 h post-administration. Samples of blood, tumor, precancerous pouch tissue, normal pouch tissue and other clinically relevant normal tissues were processed for boron measurement by optic emission spectroscopy. Tumor boron concentration peaked to therapeutically useful boron concentration values of 24-35 ppm. The boron concentration ratio tumor/normal pouch tissue ranged from 1.1 to 1.8. Pharmacokinetic curves showed that the optimum interval between BSH administration and neutron irradiation was 7-11 h. It is concluded that BNCT mediated by BSH at nuclear reactor RA-3 would be feasible.

  1. Composite Reinforcement using Boron Nitride Nanotubes

    Science.gov (United States)

    2014-05-09

    Final 3. DATES COVERED (From - To) 11-Mar-2013 to 10-Mar-2014 4. TITLE AND SUBTITLE Composite Reinforcement using Boron Nitride Nanotubes...AVAILABILITY STATEMENT Approved for public release. 13. SUPPLEMENTARY NOTES 14. ABSTRACT Boron nitride nanotubes have been proposed as a...and titanium (Ti) metal clusters with boron nitride nanotubes (BNNT). First-principles density-functional theory plus dispersion (DFT-D) calculations

  2. Oxygen radical functionalization of boron nitride nanosheets

    OpenAIRE

    MAY, PETER; Coleman, Jonathan; MCGOVERN, IGNATIUS; GOUNKO, IOURI; Satti, Amro

    2012-01-01

    PUBLISHED The covalent chemical functionalization of exfoliated hexagonal boron-nitride nanosheets (BNNSs) is achieved by the solution phase oxygen radical functionalization of boron atoms in the h-BN lattice. This involves a two-step procedure to initially covalently graft alkoxy groups to boron atoms and the subsequent hydrolytic defunctionalisation of the groups to yield hydroxyl-functionalized BNNSs (OH-BNNSs). Characterization of the functionalized-BNNSs using HR-TEM, Raman, UV-Vis, F...

  3. Boron-10 ABUNCL Active Testing

    Energy Technology Data Exchange (ETDEWEB)

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.

    2013-07-09

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Coincidence Counting With Boron-Based Alternative Neutron Detection Technology at Pacific Northwest National Laboratory (PNNL) for the development of a 3He proportional counter alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a system based upon 10B-lined proportional tubes in a configuration typical for 3He-based coincidence counter applications. This report provides results from testing of the active mode of the General Electric Reuter-Stokes Alternative Boron-Based Uranium Neutron Coincidence Collar (ABUNCL) at Los Alamos National Laboratory using sources and fuel pins.

  4. Boron deposition from fused salts. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.L.

    1980-08-01

    A partial evaluation of the feasibility of a process to electrodeposit pure coherent coatings of elemental boron from molten fluorides has been performed. The deposit produced was powdery and acicular, unless the fluoride melt was purified to have very low oxygen concentration. When the oxygen activity was reduced in the melt by addition of crystalline elemental boron, dense, amorphous boron deposit was produced. The boron deposits produced had cracks but were otherwise pure and dense and ranged up to 0.35 mm thick. Information derived during this project suggests that similar deposits might be obtained crack-free up to 1.00 mm thick by process modifications and improvements.

  5. Mineral resource of the month: boron

    Science.gov (United States)

    Crangle, Robert D.

    2012-01-01

    The article offers information on the mineral, boron. Boron compounds, particularly borates, have more commercial applications than its elemental relative which is a metalloid. Making up the 90% of the borates that are used worldwide are colemanite, kernite, tincal, and ulexite. The main borate deposits are located in the Mojave Desert of the U.S., the Tethyan belt in southern Asia, and the Andean belt of South America. Underground and surface mining are being used in gathering boron compounds. INSETS: Fun facts;Boron production and consumption.

  6. Boron removal from geothermal waters by electrocoagulation

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, A. Erdem [Atatuerk University, Faculty of Engineering, Department of Environmental Engineering., 25240 Erzurum (Turkey)], E-mail: aerdemy@atauni.edu.tr; Boncukcuoglu, Recep [Atatuerk University, Faculty of Engineering, Department of Environmental Engineering., 25240 Erzurum (Turkey); Kocakerim, M. Muhtar [Atatuerk University, Faculty of Engineering, Department of Chemical Engineering, 25240 Erzurum (Turkey); Yilmaz, M. Tolga; Paluluoglu, Cihan [Atatuerk University, Faculty of Engineering, Department of Environmental Engineering., 25240 Erzurum (Turkey)

    2008-05-01

    Most of the geothermal waters in Turkey contain extremely high concentration of boron when they are used for irrigation. The use of geothermal waters for irrigation can results in excess amount deposition of boron in soil. On the other hand, a minimal boron concentration is required for irrigational waters. In this study, electrocoagulation (EC) was selected as a treatment process for the removal of boron from thermal waters obtained from Ilica-Erzurum in Turkey. Current density (CD), pH of solution and temperature of solution were selected as operational parameters. The results showed that boron removal efficiency increased from pH 4.0 to 8.0 and decreased at pH 10.0. Although boron removal efficiency was highest at pH 8.0, energy consumption was very high at this pH value compared to other pH intervals. Boron removal efficiency reached to 95% with increasing current density from 1.5 to 6.0 mA/cm{sup 2}, but energy consumption was also increased in this interval. At higher temperatures of solution, such as 313 and 333 K, boron removal efficiency increased. At optimum conditions, boron removal efficiency in geothermal water reached up to 95%.

  7. Conduction mechanism in boron carbide

    Science.gov (United States)

    Wood, C.; Emin, D.

    1984-01-01

    Electrical conductivity, Seebeck-coefficient, and Hall-effect measurements have been made on single-phase boron carbides, B(1-x)C(x), in the compositional range from 0.1 to 0.2 X, and between room temperature and 1273 K. The results indicate that the predominant conduction mechanism is small-polaron hopping between carbon atoms at geometrically inequivalent sites.

  8. Boron coating on boron nitride coated nuclear fuels by chemical vapor deposition

    Science.gov (United States)

    Durmazuçar, Hasan H.; Gündüz, Güngör

    2000-12-01

    Uranium dioxide-only and uranium dioxide-gadolinium oxide (5% and 10%) ceramic nuclear fuel pellets which were already coated with boron nitride were coated with thin boron layer by chemical vapor deposition to increase the burn-up efficiency of the fuel during reactor operation. Coating was accomplished from the reaction of boron trichloride with hydrogen at 1250 K in a tube furnace, and then sintering at 1400 and 1525 K. The deposited boron was identified by infrared spectrum. The morphology of the coating was studied by using scanning electron microscope. The plate, grainy and string (fiber)-like boron structures were observed.

  9. Preparation of Boron Suboxide Nanoparticles and Their Processing

    Directory of Open Access Journals (Sweden)

    Jānis GRABIS

    2012-03-01

    Full Text Available Crystalline boron suboxide B6O particles with size in the range of 1.5 µm – 2 µm and crystallite size in the range of 32 nm – 40 nm were prepared by calcination at 1400 °C for one or two hours of precursors obtained by mixing X-ray amorphous boron with water solution of B2O3 followed by evaporation and drying. Decrease of molar ratio B/B2O3 from 16 to 14 in the precursor mixture reduced nonstoichiometry of prepared B6O although simultaneously it increased admixture of B2O3. Particulate composites of B6O with TiN or Ni nanoparticles were prepared by mechanical mixing. The spark plasma sintering process intensified the densification of prepared boron suboxide nanoparticles at 1900 °C and allowed manufacturing of fully dense bodies (98 % during five minutes. Additives of TiN or Ni nanoparticles reduced sintering temperature to 1700 °C and their promoted formation of Ti or Ni borides.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1345

  10. Boron Separation by the Two-step Ion-Exchange for the Isotopic Measurement of Boron

    Institute of Scientific and Technical Information of China (English)

    WANG,Qing-Zhong(王庆忠); XIAO,Ying-Kai(肖应凯); WANG,Yun-Hui(王蕴惠); ZHANG,Chong-Geng(张崇耿); WEI,Hai-Zhen(魏海珍)

    2002-01-01

    An improved procedure for extraction and purification of boron from natural samples is presented. The separation and purification of boron was carried out using a boron-specific resin, Amberlite IRA743, and a mixed ion exchange resin,Dowex 50W × 8 and Ion Exchanger Ⅱ resin. Using the mixed ion exchange resin which adsorbs all cations and anions except boron, the HCl and other cations and anions left in eluant from the Amberlite IRA 743 were removed effectively. In this case, boron loss can be avoided because the boron-bearing solution does not have to be evaporated to reach dryness to dislodge HCl. The boron recovery ranged from 97.6% to 102% in this study. The isotopic fractionation of boron can be negligible within the precision of the isotopic measurement. The results show that boron separation for the isotopic measurement by using both Amberlite IRA 743 resin and the mixed rein is more effective than that using Amberlite IRA 743 resin alone. The boron in samples of brine, seawater, rock, coral and foraminifer were separated by this procedure. Boron isotopic compositions of these samples were measured by thermal ionization mass spectrometry in this study.

  11. Comparison of the level of boron concentrations in black teas with fruit teas available on the Polish market.

    Science.gov (United States)

    Zioła-Frankowska, Anetta; Frankowski, Marcin; Novotny, Karel; Kanicky, Viktor

    2014-01-01

    The determination of boron by inductively coupled plasma-atomic emission spectrometry has been carried in water-soluble and acid soluble (total content) fractions of 36 samples of traditional black tea and fruit brew. The estimation of the impact of the type of tea on the concentration of boron in water-soluble and acid extracts and potential human health risk from the daily intake of boron was carried out in this study. The levels of boron differed significantly in black and fruit tea types. The mean total content of boron ranged from 8.31 to 18.40 mg/kg in black teas, from 12.85 to 15.13 mg/kg in black tea with fruit flavor, and from 12.09 to 22.77 mg/kg in fruit brews. The degree of extraction of boron in black tea ranged from 8% to 27% and for fruit tea from 17% to 69%. In addition, the values below 25% were of black teas with fruit flavors. The daily intake of B from tea infusions (three cups/day) is still within the average daily intake except for some of the fruit brews which exceed acceptable regulations of the daily intake of total boron by humans. Hence, it may not produce any health risks for human consumption, if other sources of metal contaminated food are not taken at the same time.

  12. Comparison of the Level of Boron Concentrations in Black Teas with Fruit Teas Available on the Polish Market

    Directory of Open Access Journals (Sweden)

    Anetta Zioła-Frankowska

    2014-01-01

    Full Text Available The determination of boron by inductively coupled plasma-atomic emission spectrometry has been carried in water-soluble and acid soluble (total content fractions of 36 samples of traditional black tea and fruit brew. The estimation of the impact of the type of tea on the concentration of boron in water-soluble and acid extracts and potential human health risk from the daily intake of boron was carried out in this study. The levels of boron differed significantly in black and fruit tea types. The mean total content of boron ranged from 8.31 to 18.40 mg/kg in black teas, from 12.85 to 15.13 mg/kg in black tea with fruit flavor, and from 12.09 to 22.77 mg/kg in fruit brews. The degree of extraction of boron in black tea ranged from 8% to 27% and for fruit tea from 17% to 69%. In addition, the values below 25% were of black teas with fruit flavors. The daily intake of B from tea infusions (three cups/day is still within the average daily intake except for some of the fruit brews which exceed acceptable regulations of the daily intake of total boron by humans. Hence, it may not produce any health risks for human consumption, if other sources of metal contaminated food are not taken at the same time.

  13. Possible toxicity of boron on sugar cane

    Energy Technology Data Exchange (ETDEWEB)

    Bravo C., M.

    Analyses of necrotic and green leaf tissues from sugar cane grown in the Tambo Valley (Arequipa, Peru) have shown that the boron concentration in necrotic tissue (average 657.7 ppm) is several times higher than that in the green tissue (average 55.7 ppm). This suggests that the necrosis may be due to boron toxicity.

  14. Computational Evidence for the Smallest Boron Nanotube

    Institute of Scientific and Technical Information of China (English)

    Xian Jie LIN; Dong Ju ZHANG; Cheng Bu LIU

    2006-01-01

    The structure of boron nanotubes (BNTs) was found not to be limited to hexagonal pyramidal structures. Based on density functional theory calculations we provided evidence for the smallest boron nanotube, a geometrical analog of the corresponding carbon nanotube. As shown by our calculations, the smallest BNT possesses highly structural, dynamical, and thermal stability, which should be interest for attempts at its synthesis.

  15. Boron carbide whiskers produced by vapor deposition

    Science.gov (United States)

    1965-01-01

    Boron carbide whiskers have an excellent combination of properties for use as a reinforcement material. They are produced by vaporizing boron carbide powder and condensing the vapors on a substrate. Certain catalysts promote the growth rate and size of the whiskers.

  16. Boron rates for triticale and wheat crops

    Directory of Open Access Journals (Sweden)

    Corrêa Juliano Corulli

    2005-01-01

    Full Text Available No reports are registered on responses to boron fertilization nutrient deficiency and toxicity in triticale crops. The aim of this study was to evaluate triticale response to different rates of boron in comparison to wheat in an hapludox with initial boron level at 0.08 mg dm-3 4 4 factorial design trial completely randomized blocks design (n = 4. Boron rates were 0; 0.62; 1.24 and 1.86 mg dm-3; triticale cultivars were IAC 3, BR 4 and BR 53 and IAPAR 38 wheat crop was used for comparison. The wheat (IAPAR 38 crop presented the highest boron absorption level of all. Among triticale cultivars, the most responsive was IAC 53, presenting similar characteristics to wheat, followed by BR 4; these two crops are considered tolerant to higher boron rates in soil. Regarding to BR 53, no absorption effect was observed, and the cultivars was sensitive to boron toxicity. Absorption responses differed for each genotype. That makes it possible to choose and use the best-adapted plants to soils with different boron rates.

  17. Boron Carbides As Thermo-electric Materials

    Science.gov (United States)

    Wood, Charles

    1988-01-01

    Report reviews recent theoretical and experimental research on thermoelectric materials. Recent work with narrow-band semiconductors demonstrated possibility of relatively high thermoelectric energy-conversion efficiencies in materials withstanding high temperatures needed to attain such efficiencies. Among promising semiconductors are boron-rich borides, especially boron carbides.

  18. Stabilization of boron carbide via silicon doping.

    Science.gov (United States)

    Proctor, J E; Bhakhri, V; Hao, R; Prior, T J; Scheler, T; Gregoryanz, E; Chhowalla, M; Giulani, F

    2015-01-14

    Boron carbide is one of the lightest and hardest ceramics, but its applications are limited by its poor stability against a partial phase separation into separate boron and carbon. Phase separation is observed under high non-hydrostatic stress (both static and dynamic), resulting in amorphization. The phase separation is thought to occur in just one of the many naturally occurring polytypes in the material, and this raises the possibility of doping the boron carbide to eliminate this polytype. In this work, we have synthesized boron carbide doped with silicon. We have conducted a series of characterizations (transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and x-ray diffraction) on pure and silicon-doped boron carbide following static compression to 50 GPa non-hydrostatic pressure. We find that the level of amorphization under static non-hydrostatic pressure is drastically reduced by the silicon doping.

  19. XPS analysis of boron doped heterofullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Schnyder, B.; Koetz, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Muhr, H.J.; Nesper, R. [ETH Zurich, Zurich (Switzerland)

    1997-06-01

    Boron heterofullerenes were generated through arc-evaporation of doped graphite rods in a helium atmosphere. According to mass spectrometric analysis only mono-substituted fullerenes like C{sub 59}B, C{sub 69}B and higher homologues together with a large fraction of higher undoped fullerenes were extracted and enriched when pyridine was used as the solvent. XPS analysis of the extracts indicated the presence of two boron species with significantly different binding energies. One peak was assigned to borid acid. The second one corresponds to boron in the fullerene cage, which is mainly C{sub 59}B, according to the mass spectrum. This boron is in a somewhat higher oxidation state than that of ordinary boron-carbon compounds. The reported synthesis and extraction procedure opens a viable route for production of macroscopic amounts of these compounds. (author) 2 figs., 1 tab., 7 refs.

  20. Boron enrichment in martian clay.

    Directory of Open Access Journals (Sweden)

    James D Stephenson

    Full Text Available We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration.

  1. Boron-Boron One-Electron Sigma Bonds versus B-X-B Bridged Structures.

    Science.gov (United States)

    Kusevska, Elena; Montero-Campillo, M Merced; Mó, Otilia; Yáñez, Manuel

    2016-09-12

    The existence of one-electron B-B σ bonds, for two different sets of compounds, was investigated by analyzing their electron density with different tools, namely QTAIM, ELF, NCIPLOT, and NBO approaches. Our results indicate that although the generic label "one-electron sigma bond" is often used in the literature, the nature of these bonds varies considerably, or they even do not exist. The [B2 X6 ](-) radical anions give place to true covalent one-electron σ bonds, the stronger the more electronegative is the X substituent. When both boron atoms are substituents in a rigid aromatic moiety, such as naphthalene, to yield 1,8-disubstituted derivatives, two kinds of equilibrium structures are found, those also stabilized through a one-electron σ bond (X=OH, F, Cl, CN) and those stabilized by the formation of B-X-B bridges (X=H, OMe). These 1,8-BX2 naphthalene derivatives can be considered as analogues of 1,8-NX2 naphthalene proton sponges. While the latter are able to stabilize a proton between the two basic sites, the former are able to stabilize an electron between the two electron-deficient B atoms. Interestingly, when all the H atoms attached to B are substituted by phenyl groups no one-electron σ bonds B-B bonds are formed, due to the dispersion of the unpaired electron in the aromatic substituents.

  2. Relationship Not Found Between Blood and Urine Concentrations and Body Mass Index in Humans With Apparently Adequate Boron Status.

    Science.gov (United States)

    Koc, Fulya; Aysan, Erhan; Hasbahceci, Mustafa; Arpaci, Beyza; Gecer, Salih; Demirci, Selami; Sahin, Fikrettin

    2016-06-01

    The impact of boron on the development of obesity remains controversial in the analysis of experimental and clinical data. The objective of this study was to investigate the relationship between blood and urine boron concentrations and obesity in normal, overweight, obese, and morbidly obese subjects in different age groups. A total of 105 subjects were categorized into 12 groups based on body mass index and three different age levels: as young adult (18 to 34 years old), adult (35 to 54 years old), and older adult (greater than 55 years old). Age, gender, body mass index, and blood and urine boron concentrations were recorded for each subject. There were 50 women and 55 men, with a mean age of 44.63 ± 17.9 years. Blood and urine boron concentrations were similar among the groups (p = 0.510 and p = 0.228, respectively). However, a positive correlation between age and blood boron concentration (p = 0.001) was detected in contrast to the presence of a negative correlation between age and urine boron concentration (p = 0.027). Multiple linear regression analysis showed that there was no significant relationship between gender, age, and quantitative values of body mass index for each subject, and blood and urine boron concentrations. Although the relationship between boron and obesity has not been confirmed, changes of blood and urine boron concentrations with age may have some physiologic sequences to cause obesity.

  3. Standard test methods for chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade boron carbide

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2004-01-01

    1.1 These test methods cover procedures for the chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade boron carbide powder and pellets to determine compliance with specifications. 1.2 The analytical procedures appear in the following order: Sections Total Carbon by Combustion and Gravimetry 7-17 Total Boron by Titrimetry 18-28 Isotopic Composition by Mass Spectrometry 29-38 Chloride and Fluoride Separation by Pyrohydrolysis 39-45 Chloride by Constant-Current Coulometry 46-54 Fluoride by Ion-Selective Electrode 55-63 Water by Constant-Voltage Coulometry 64-72 Impurities by Spectrochemical Analysis 73-81 Soluble Boron by Titrimetry 82-95 Soluble Carbon by a Manometric Measurement 96-105 Metallic Impurities by a Direct Reader Spectrometric Method 106-114

  4. Porous Boron Nitride with Tunable Pore Size.

    Science.gov (United States)

    Dai, Jun; Wu, Xiaojun; Yang, Jinlong; Zeng, Xiao Cheng

    2014-01-16

    On the basis of a global structural search and first-principles calculations, we predict two types of porous boron-nitride (BN) networks that can be built up with zigzag BN nanoribbons (BNNRs). The BNNRs are either directly connected with puckered B (N) atoms at the edge (type I) or connected with sp(3)-bonded BN chains (type II). Besides mechanical stability, these materials are predicted to be thermally stable at 1000 K. The porous BN materials entail large surface areas, ranging from 2800 to 4800 m(2)/g. In particular, type-II BN material with relatively large pores is highly favorable for hydrogen storage because the computed hydrogen adsorption energy (-0.18 eV) is very close to the optimal adsorption energy (-0.15 eV) suggested for reversible hydrogen storage at room temperature. Moreover, the type-II materials are semiconductors with width-dependent direct bandgaps, rendering the type-II BN materials promising not only for hydrogen storage but also for optoelectronic and photonic applications.

  5. Autoionizing states of atomic boron

    Science.gov (United States)

    Argenti, Luca; Moccia, Roberto

    2016-04-01

    We present a B -spline K -matrix method for three-active-electron atoms in the presence of a polarizable core, with which it is possible to compute multichannel single-ionization scattering states with good accuracy. We illustrate the capabilities of the method by computing the parameters of several autoionizing states of the boron atom, with S2e, 2,o2P and D2e symmetry, up to at least the 2 p2(1S) excitation threshold of the B ii parent ion, as well as selected portions of the photoionization cross section from the ground state. Our results exhibit remarkable gauge consistency, they significantly extend the existing sparse record of data for the boron atom, and they are in good agreement with the few experimental and theoretical data available in the literature. These results open the way to extend to three-active-electron systems the spectral analysis of correlated wave packets in terms of accurate scattering states that has already been demonstrated for two-electron atoms in Argenti and Lindroth [Phys. Rev. Lett. 105, 053002 (2010), 10.1103/PhysRevLett.105.053002].

  6. Effects of water quality parameters on boron toxicity to Ceriodaphnia dubia.

    Science.gov (United States)

    Dethloff, Gail M; Stubblefield, William A; Schlekat, Christian E

    2009-07-01

    The potential modifying effects of certain water quality parameters (e.g., hardness, alkalinity, pH) on the acute toxicity of boron were tested using a freshwater cladoceran, Ceriodaphnia dubia. By comparison, boron acute toxicity was less affected by water quality characteristics than some metals (e.g., copper and silver). Increases in alkalinity over the range tested did not alter toxicity. Increases in water hardness appeared to have an effect with very hard waters (>500 mg/L as CaCO(3)). Decreased pH had a limited influence on boron acute toxicity in laboratory waters. Increasing chloride concentration did not provide a protective effect. Boron acute toxicity was unaffected by sodium concentrations. Median acute lethal concentrations (LC(50)) in natural water samples collected from three field sites were all greater than in reconstituted laboratory waters that matched natural waters in all respects except for dissolved organic carbon. Water effect ratios in these waters ranged from 1.4 to 1.8. In subsequent studies using a commercially available source of natural organic matter, acute toxicity decreased with increased dissolved organic carbon, suggesting, along with the natural water studies, that dissolved organic carbon should be considered further as a modifier of boron toxicity in natural waters where it exceeds 2 mg/L.

  7. Response of Boron and Light on Morph-Physiology and Pod Yield of Two Peanut Varieties

    Directory of Open Access Journals (Sweden)

    Md. Quamruzzaman

    2016-01-01

    Full Text Available Boron is an important micronutrient that enhances vegetative growth and yield of crops, like peanut. Light also plays an important role in pegging of peanut. There has been little information regarding the application of boron and light in peanut in Bangladesh. Therefore, a field experiment was conducted to study the response of boron and light on morph-physiology and pod yield of two peanut varieties. Treatments considered two peanut varieties, namely, Dhaka-1 and BARI Chinabadam-8, three levels of boron (B, namely, 0-kg B ha−1 (B0, 1-kg B ha−1 (B1, and 2-kg B ha−1 (B2, and two levels of light, namely, normal day light (≈12 h light and normal day light + 6 h extended red light at night (≈18 h light. Result revealed that days to first-last emergence and days to first-50% flowering took shorter times and vegetative growth, pods dry weight plant−1, pod yield, and germination were markedly increased with the application of boron. Vegetative growth and germinations were significantly increased in light, but the lowest leaf area, pods dry weight plant−1, and pod yield were found in light. Without germination, the highest vegetative growth, reproductive unit, and pod yield were observed from BARI Chinabadam-8. Days to first-last emergence, days to first-50% flowering, and number of branches plant−1 were found linearly related to pod yield.

  8. Combustion synthesis of novel boron carbide

    Science.gov (United States)

    Harini, R. Saai; Manikandan, E.; Anthonysamy, S.; Chandramouli, V.; Eswaramoorthy, D.

    2013-02-01

    The solid-state boron carbide is one of the hardest materials known, ranking third behind diamond and cubic boron nitride. Boron carbide (BxCx) enriched in the 10B isotope is used as a control rod material in the nuclear industry due to its high neutron absorption cross section and other favorable physico-chemical properties. Conventional methods of preparation of boron carbide are energy intensive processes accompanied by huge loss of boron. Attempts were made at IGCAR Kalpakkam to develop energy efficient and cost effective methods to prepare boron carbide. The products of the gel combustion and microwave synthesis experiments were characterized for phase purity by XRD. The carbide formation was ascertained using finger-print spectroscopy of FTIR. Samples of pyrolized/microwave heated powder were characterized for surface morphology using SEM. The present work shows the recent advances in understanding of structural and chemical variations in boron carbide and their influence on morphology, optical and vibrational property results discussed in details.

  9. Method of synthesizing cubic system boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Yuzu, S.; Sumiya, H.; Degawa, J.

    1987-10-13

    A method is described for synthetically growing cubic system boron nitride crystals by using boron nitride sources, solvents for dissolving the boron nitride sources, and seed crystals under conditions of ultra-high pressure and high temperature for maintaining the cubic system boron nitride stable. The method comprises the following steps: preparing a synthesizing vessel having at least two chambers, arrayed in order in the synthesizing vessel so as to be heated according to a temperature gradient; placing the solvents having different eutectic temperatures in each chamber with respect to the boron nitride sources according to the temperature gradient; placing the boron nitride source in contact with a portion of each of the solvents heated at a relatively higher temperature and placing at least a seed crystal in a portion of each of the solvents heated at a relatively lower temperature; and growing at least one cubic system boron nitride crystal in each of the solvents in the chambers by heating the synthesizing vessel for establishing the temperature gradient while maintaining conditions of ultra-high pressure and high temperature.

  10. X-ray diffraction study of boron produced by pyrolysis of boron tribromide

    Science.gov (United States)

    Rosenberg, David

    The goal of this research was to determine the composition of boron deposits produced by pyrolysis of boron tribromide, and to use the results to (a) determine the experimental conditions (reaction temperature, etc.) necessary to produce alpha-rhombohedral boron and (b) guide the development/refinement of the pyrolysis experiments such that large, high purity crystals of alpha-rhombohedral boron can be produced with consistency. Developing a method for producing large, high purity alpha-rhombohedral boron crystals is of interest because such crystals could potentially be used to achieve an alpha-rhombohedral boron based neutron detector design (a solid-state detector) that could serve as an alternative to existing neutron detector technologies. The supply of neutron detectors in the United States has been hampered for a number of years due to the current shortage of helium-3 (a gas used in many existing neutron detector technologies); the development of alternative neutron detector technology such as an alpha-rhombohedral boron based detector would help provide a more sustainable supply of neutron detectors in this country. In addition, the prospect/concept of an alpha-rhombohedral boron based neutron detector is attractive because it offers the possibility of achieving a design that is smaller, longer life, less power consuming, and potentially more sensitive than existing neutron detectors. The main difficulty associated with creating an alpha-rhombohedral boron based neutron detector is that producing large, high purity crystals of alpha-rhombohedral boron is extremely challenging. Past researchers have successfully made alpha-rhombohedral boron via a number of methods, but no one has developed a method for consistently producing large, high purity crystals. Alpha-rhombohedral boron is difficult to make because it is only stable at temperatures below around 1100-1200 °C, its formation is very sensitive to impurities, and the conditions necessary for its

  11. Engineering design feasibility of low boron concentration core in PWR

    Energy Technology Data Exchange (ETDEWEB)

    Daing, A. T.; Kim, M. H. [Kyung Hee University, Yongin-shi, Gyeonggi-do, 446-701 Republic of Korea (Korea, Republic of); Woo, I.; Shon, S. R., E-mail: atdaing@khu.ac.k [Korea Nuclear Fuel, 1047 Daedukdaero, Yuseong-gu, Daejeon, 305-353 Republic of Korea (Korea, Republic of)

    2010-10-15

    In pressurized water reactor operation, higher level of soluble boron concentration could contribute higher impact from boron dilution situations, higher amount of liquid waste, and higher radiation dose to operators from higher corrosion potential to cladding and structure. Two practical and feasible means to reduce the maximum boron concentration were investigated in this study. A technically straightforward, possible means, can be achieved either by implementation of enriched boric acid (Eba) or by increasing more shim rod (fixed burnable absorber) worth. A simplest option is that the Eba is applied into reference core (Ref) design, OPR-1000 design, Ulchin unit-5 by allowing use of same fuel assemblies and core design without changing any nuclear design methodology used in that Ref design. Although results of Eba option proved its favorable power distribution and peaking factor, its moderator temperature coefficient (MTC) value reached positive, 3.25 pcm/ C at 40 EFPD which is beyond the design safety limit. An alternative option with more shim rods in fuel assemblies was tried with four types of integral burnable absorbers: gadolinia, integral fuel burnable absorber (Ifba), erbium and alumina boron carbide. Four core design candidates have been developed by keeping major engineering designs and preserving equivalent fuel enrichment level used in Ref design. However, all optimal designs were targeted to achieve comparable discharge burnup as well as favorable design safety parameters. The comparative analysis between Ref and optimal core designs is presented here. One of them is suggested as the most promising and favorable low boron core (Lbc) design in this framework. The proper combination of axial and radial enrichment zoning pattern in Lbc design candidate with Ifba-bearing fuel assemblies at equilibrium cycle, could bring 2 times narrower axial offset variation than that of Ref design, and maintain acceptable power peaking factor around 23% lower than

  12. From Boron Cluster to Two-Dimensional Boron Sheet on Cu(111) Surface: Growth Mechanism and Hole Formation

    OpenAIRE

    Hongsheng Liu; Junfeng Gao; Jijun Zhao

    2013-01-01

    As attractive analogue of graphene, boron monolayers have been theoretically predicted. However, due to electron deficiency of boron atom, synthesizing boron monolayer is very challenging in experiments. Using first-principles calculations, we explore stability and growth mechanism of various boron sheets on Cu(111) substrate. The monotonic decrease of formation energy of boron cluster BN with increasing cluster size and low diffusion barrier for a single B atom on Cu(111) surface ensure cont...

  13. Developments in boron magnetic resonance imaging (MRI)

    Energy Technology Data Exchange (ETDEWEB)

    Schweizer, M.

    1995-11-01

    This report summarizes progress during the past year on maturing Boron-11 magnetic resonance imaging (MRI) methodology for noninvasive determination of BNCT agents (BSH) spatially in time. Three major areas are excerpted: (1) Boron-11 MRI of BSH distributions in a canine intracranial tumor model and the first human glioblastoma patient, (2) whole body Boron-11 MRI of BSH pharmacokinetics in a rat flank tumor model, and (3) penetration of gadolinium salts through the BBB as a function of tumor growth in the canine brain.

  14. Bonding in boron: building high-pressure phases from boron sheets

    Energy Technology Data Exchange (ETDEWEB)

    Kunstmann, Jens [Institute for Materials Science and Max Bergmann Center of Biomaterials, Dresden University of Technology (Germany); Boeri, Lilia [Max Planck Institute for Solid State Research, Stuttgart (Germany); Kortus, Jens [Institute for Theoretical Physics, TU Bergakademie Freiberg (Germany)

    2010-07-01

    We present the results of a study of the high pressure phase diagram of elemental boron, using full-potential density functional calculations. We show that at high pressures (P > 100 GPa) boron crystallizes in quasi-layered bulk phases, characterized by in-plane multicenter bonds and out-of-plane unidimensional sigma bonds. These structures are all metallic, in contrast to the low-pressure icosahedral ones, which are semiconducting. We show that the structure and bonding of layered bulk phases can be easily described in terms of single puckered boron sheets. Our results bridge the gap between boron nanostructures and bulk phases.

  15. Characterization of boron tolerant bacteria isolated from a fly ash dumping site for bacterial boron remediation.

    Science.gov (United States)

    Edward Raja, Chellaiah; Omine, Kiyoshi

    2013-08-01

    Boron is an essential micronutrient for plants, but can above certain concentrations be toxic to living organisms. A major environmental concern is the removal of boron from contaminated water and fly ash. For this purpose, the samples were collected from a fly ash dumping site, Nagasaki prefecture, Japan. The chemical characteristics and heavy metal concentration of the samples were performed by X-ray fluorescent analysis and leaching test. For bacterial analysis, samples were collected in sterile plastic sheets and isolation was carried out by serial dilution method. The boron tolerant isolates that showed values of maximum inhibitory concentration toward boron ranging from 100 to 260 mM level were screened. Based on 16S rRNA sequencing and phylogenetic analysis, the isolates were most closely related to the genera Bacillus, Lysinibacillus, Microbacterium and Ralstonia. The boron tolerance of these strains was also associated with resistant to several heavy metals, such as As (III), Cr (VI), Cd, Cu, Pb, Ni, Se (III) and Zn. Indeed, these strains were arsenic oxidizing bacteria confirmed by silver nitrate test. These strains exhibited their salt resistances ranging from 4 to 15 % were determined in Trypticase soy agar medium. The boron tolerant strains were capable of removing 0.1-2.0 and 2.7-3.7 mg l(-1) boron from the medium and fly ash at 168 h. Thus, we have successfully identified the boron tolerant and removal bacteria from a fly ash dumping site for boron remediation.

  16. Complementary incorporation of boron compounds with different cellular targets in melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Morre, D.E. [University of Sydney, Dept. of Pharmacy, Sydney, NSW (Australia); Setiawan, Y.; Allen, B.J. [St George Cancer Care Centre, Kogarah, NSW (Australia)

    1996-12-31

    Full text. The heterogeneity of malignant tumours is well known, and post-surgical control may only be achieved by the application of a number of adjuvant therapies. In boron neutron capture therapy (BNCT), a similar effect could be achieved by utilising boron compounds with quite different uptake and incorporation mechanisms. While tumour growth delay or control can be induced by BNCT in animal models, long term control in human patients may be much more difficult. Thus we have carried out experiments with two boron compounds which exhibit quite different pharmacokinetics and interact with cancer cells by quite different mechanisms. The compounds studied were p-boronophenylalanine (BPA) and boronated low density lipoprotein (B-LDL). Non-specific boron compounds such as n-alkyl carboranes can be delivered to melanoma tumour cells when incorporated in reconstituted LDL. Biodistribution studies were performed with BALB/c mice bearing subcutaneous Harding-Passey melanoma xenografts. The mice were pretreated with a high fat diet and hydrocortisone to down regulate the non-autonomous LDL receptors. A tumour to blood boron concentration ratio of 5:1 was achieved 18 hours after administration of B-LDL. The same compound administered in a non-specific arachis oil vehicle failed to demonstrate selective uptake in the tumour. Neutron capture therapy using B-LDL as the boron delivery vehicle produced a growth delay effect on the tumours which was equivalent to that found when BPA was administered as the fructose complex to develop a similar boron concentration in the tumour. This is indicative that the boron microdistribution across different types of tumour cells achieved by B-LDL has a similar effect to that achieved by BPA in the tumour model, even though the uptake mechanisms for BPA and B-LDL are different. BPA uptake is thought to be dependent on the amino acid transport mechanism, whereas receptor density determines LDL incorporation. Thus the combined administration

  17. Boron-Based (Nano-Materials: Fundamentals and Applications

    Directory of Open Access Journals (Sweden)

    Umit B. Demirci

    2016-09-01

    Full Text Available The boron (Z = 5 element is unique. Boron-based (nano-materials are equally unique. Accordingly, the present special issue is dedicated to crystalline boron-based (nano-materials and gathers a series of nine review and research articles dealing with different boron-based compounds. Boranes, borohydrides, polyhedral boranes and carboranes, boronate anions/ligands, boron nitride (hexagonal structure, and elemental boron are considered. Importantly, large sections are dedicated to fundamentals, with a special focus on crystal structures. The application potentials are widely discussed on the basis of the materials’ physical and chemical properties. It stands out that crystalline boron-based (nano-materials have many technological opportunities in fields such as energy storage, gas sorption (depollution, medicine, and optical and electronic devices. The present special issue is further evidence of the wealth of boron science, especially in terms of crystalline (nano-materials.

  18. Catalytic Asymmetric Synthesis of Phosphine Boronates

    NARCIS (Netherlands)

    Hornillos, Valentin; Vila, Carlos; Otten, Edwin; Feringa, Ben L.

    2015-01-01

    The first catalytic enantioselective synthesis of ambiphilic phosphine boronate esters is presented. The asymmetric boration of ,-unsaturated phosphine oxides catalyzed by a copper bisphosphine complex affords optically active organoboronate esters that bear a vicinal phosphine oxide group in good y

  19. Boron-Filled Hybrid Carbon Nanotubes

    Science.gov (United States)

    Patel, Rajen B.; Chou, Tsengming; Kanwal, Alokik; Apigo, David J.; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-07-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs.

  20. Boron-10 loaded inorganic shielding material

    Science.gov (United States)

    Baker, S. I.; Ryskiewicz, R. S.

    1972-01-01

    Shielding material containing Boron 10 and gadoliunium for neutron absorption has been developed to reduce interference from low energy neutrons in measurement of fission neutron spectrum using Li-6 fast neutron spectrometer.

  1. Spectromicroscopy in Boron Neutron Capture Therapy Research

    Science.gov (United States)

    Gilbert, Benjamin; Redondo, Jose; Andres, Roger; Suda, Takashi; Neumann, Michael; Steen, Steffi; Gabel, Detlef; Mercanti, Delio; Ciotti, Teresa; Perfetti, Paolo; Margaritondo, Giorgio; de Stasio, Gelsomina

    1998-03-01

    The MEPHISTO synchrotron imaging spectromicroscope can analyse ashed cells or tissue sections to reveal the microdistribution of trace elements. MEPHISTO performs core level x-ray absorption spectroscopy with synchrotron radiation, and uses an electron optics system to provide magnified photoelectron images. An application of the MEPHISTO spectromicroscope is in boron neutron capture therapy (BNCT). BNCT is a binary cancer therapy that will selectively destroy cancer cells provided that compounds containing a boron isotope are selectively accumulated in tumor tissue. Important factors for the success of BNCT include the ability to target every cancer cell, and the distribution of boron inside the cell. To investigate the boron distribution in tissue, sections of human glioblastoma containing a BNCT compound, and stained with nickel against a protein found in the nuclei of proliferating (cancer) cells, were studied with MEPHISTO.

  2. Boron-Filled Hybrid Carbon Nanotubes

    Science.gov (United States)

    Patel, Rajen B.; Chou, Tsengming; Kanwal, Alokik; Apigo, David J.; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-01-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs. PMID:27460526

  3. Combustion Behavior of Free Boron Slurry Droplets,

    Science.gov (United States)

    2014-09-26

    weak disruptive behavior while pure JP-1t burn quiescently, except for a flash extinction which occurs at the termination of combustion. The...I AD-R158 628 COMBUSTION BEHAVIOR OF FREE BORON SLURRY DROPLETS(U) i/i I PRINCETON UNIV NJ DEPT OF MECHANICAL AND AEROSPACE ENINEERIN., F TAKAHASHI...COMBUSTION BEHAVIOR OF FREE BORON SLURRY DROPLETS TAM by F. Takahashi, F.L. Dryer, and F.A. Williams Department of M~echanical and keyosase Engineering

  4. Short-term coral bleaching is not recorded by skeletal boron isotopes.

    Directory of Open Access Journals (Sweden)

    Verena Schoepf

    Full Text Available Coral skeletal boron isotopes have been established as a proxy for seawater pH, yet it remains unclear if and how this proxy is affected by seawater temperature. Specifically, it has never been directly tested whether coral bleaching caused by high water temperatures influences coral boron isotopes. Here we report the results from a controlled bleaching experiment conducted on the Caribbean corals Porites divaricata, Porites astreoides, and Orbicella faveolata. Stable boron (δ11B, carbon (δ13C, oxygen (δ18O isotopes, Sr/Ca, Mg/Ca, U/Ca, and Ba/Ca ratios, as well as chlorophyll a concentrations and calcification rates were measured on coral skeletal material corresponding to the period during and immediately after the elevated temperature treatment and again after 6 weeks of recovery on the reef. We show that under these conditions, coral bleaching did not affect the boron isotopic signature in any coral species tested, despite significant changes in coral physiology. This contradicts published findings from coral cores, where significant decreases in boron isotopes were interpreted as corresponding to times of known mass bleaching events. In contrast, δ13C and δ18O exhibited major enrichment corresponding to decreases in calcification rates associated with bleaching. Sr/Ca of bleached corals did not consistently record the 1.2°C difference in seawater temperature during the bleaching treatment, or alternatively show a consistent increase due to impaired photosynthesis and calcification. Mg/Ca, U/Ca, and Ba/Ca were affected by coral bleaching in some of the coral species, but the observed patterns could not be satisfactorily explained by temperature dependence or changes in coral physiology. This demonstrates that coral boron isotopes do not record short-term bleaching events, and therefore cannot be used as a proxy for past bleaching events. The robustness of coral boron isotopes to changes in coral physiology, however, suggests that

  5. Short-term coral bleaching is not recorded by skeletal boron isotopes.

    Science.gov (United States)

    Schoepf, Verena; McCulloch, Malcolm T; Warner, Mark E; Levas, Stephen J; Matsui, Yohei; Aschaffenburg, Matthew D; Grottoli, Andréa G

    2014-01-01

    Coral skeletal boron isotopes have been established as a proxy for seawater pH, yet it remains unclear if and how this proxy is affected by seawater temperature. Specifically, it has never been directly tested whether coral bleaching caused by high water temperatures influences coral boron isotopes. Here we report the results from a controlled bleaching experiment conducted on the Caribbean corals Porites divaricata, Porites astreoides, and Orbicella faveolata. Stable boron (δ11B), carbon (δ13C), oxygen (δ18O) isotopes, Sr/Ca, Mg/Ca, U/Ca, and Ba/Ca ratios, as well as chlorophyll a concentrations and calcification rates were measured on coral skeletal material corresponding to the period during and immediately after the elevated temperature treatment and again after 6 weeks of recovery on the reef. We show that under these conditions, coral bleaching did not affect the boron isotopic signature in any coral species tested, despite significant changes in coral physiology. This contradicts published findings from coral cores, where significant decreases in boron isotopes were interpreted as corresponding to times of known mass bleaching events. In contrast, δ13C and δ18O exhibited major enrichment corresponding to decreases in calcification rates associated with bleaching. Sr/Ca of bleached corals did not consistently record the 1.2°C difference in seawater temperature during the bleaching treatment, or alternatively show a consistent increase due to impaired photosynthesis and calcification. Mg/Ca, U/Ca, and Ba/Ca were affected by coral bleaching in some of the coral species, but the observed patterns could not be satisfactorily explained by temperature dependence or changes in coral physiology. This demonstrates that coral boron isotopes do not record short-term bleaching events, and therefore cannot be used as a proxy for past bleaching events. The robustness of coral boron isotopes to changes in coral physiology, however, suggests that reconstruction of

  6. Short-Term Coral Bleaching Is Not Recorded by Skeletal Boron Isotopes

    Science.gov (United States)

    Schoepf, Verena; McCulloch, Malcolm T.; Warner, Mark E.; Levas, Stephen J.; Matsui, Yohei; Aschaffenburg, Matthew D.; Grottoli, Andréa G.

    2014-01-01

    Coral skeletal boron isotopes have been established as a proxy for seawater pH, yet it remains unclear if and how this proxy is affected by seawater temperature. Specifically, it has never been directly tested whether coral bleaching caused by high water temperatures influences coral boron isotopes. Here we report the results from a controlled bleaching experiment conducted on the Caribbean corals Porites divaricata, Porites astreoides, and Orbicella faveolata. Stable boron (δ11B), carbon (δ13C), oxygen (δ18O) isotopes, Sr/Ca, Mg/Ca, U/Ca, and Ba/Ca ratios, as well as chlorophyll a concentrations and calcification rates were measured on coral skeletal material corresponding to the period during and immediately after the elevated temperature treatment and again after 6 weeks of recovery on the reef. We show that under these conditions, coral bleaching did not affect the boron isotopic signature in any coral species tested, despite significant changes in coral physiology. This contradicts published findings from coral cores, where significant decreases in boron isotopes were interpreted as corresponding to times of known mass bleaching events. In contrast, δ13C and δ18O exhibited major enrichment corresponding to decreases in calcification rates associated with bleaching. Sr/Ca of bleached corals did not consistently record the 1.2°C difference in seawater temperature during the bleaching treatment, or alternatively show a consistent increase due to impaired photosynthesis and calcification. Mg/Ca, U/Ca, and Ba/Ca were affected by coral bleaching in some of the coral species, but the observed patterns could not be satisfactorily explained by temperature dependence or changes in coral physiology. This demonstrates that coral boron isotopes do not record short-term bleaching events, and therefore cannot be used as a proxy for past bleaching events. The robustness of coral boron isotopes to changes in coral physiology, however, suggests that reconstruction of

  7. Invisible face of boron pollution in fluvial ecosystem: the level in the tissues of sentinel and nectonic organisms.

    Science.gov (United States)

    Arslan, Naime

    2013-10-01

    Turkey is the largest producer of borate products in the world. Among four largest boron mines in Turkey two of them are located in basins of Orhaneli and Emet Streams. In this study, boron levels in abiotic (water-sediment) and some biotic elements (sentinel organisms; Asellus aquaticus, Gammarus pulex, Chironomus tentans, Limnodrilus hoffmeisteri and nektonic organism; Squalius cii) of Orhaneli and Emet Streams were investigated and their ranks among the food chain were demonstrated. Since Orhaneli and Emet Streams confluence to form Mustafakemalpaşa Brook which feeds Uluabat Lake which is one of the most important Ramsar fields of the world, Boron levels in those two streams have importance in terms of both continuances of aquatic systems. Present study results have shown that boron levels in water of both streams are much higher (vary between 8.64 and 16.73 mg L(-1)) than not only Turkish Standard but also limits determined by WHO, US EPA, and NAS. Boron levels determined in sediments of two streams vary between 18.05 and 36.7 mg kg(-1). The highest boron level in the biotic elements was determined in liver of Squalius cii (34.64 mg kg(-1)), it is followed by Limnodrilus hoffmeisteri (2.84 mg kg(-1)), Chironomus tentans (2.11 mg kg(-1)), and Gammarus pulex (1.98 mg kg(-1)).

  8. Innovative boron nitride-doped propellants

    Institute of Scientific and Technical Information of China (English)

    Thelma MANNING; Henry GRAU; Paul MATTER; Michael BEACHY; Christopher HOLT; Samuel SOPOK; Richard FIELD; Kenneth KLINGAMAN; Michael FAIR; John BOLOGNINI; Robin CROWNOVER; Carlton P. ADAM; Viral PANCHAL; Eugene ROZUMOV

    2016-01-01

    The U.S. military has a need for more powerful propellants with balanced/stoichiometric amounts of fuel and oxidants. However, balanced and more powerful propellants lead to accelerated gun barrel erosion and markedly shortened useful barrel life. Boron nitride (BN) is an interesting potential additive for propellants that could reduce gun wear effects in advanced propellants (US patent pending 2015-026P). Hexagonal boron nitride is a good lubricant that can provide wear resistance and lower flame temperatures for gun barrels. Further, boron can dope steel, which drastically improves its strength and wear resistance, and can block the formation of softer carbides. A scalable synthesis method for producing boron nitride nano-particles that can be readily dispersed into propellants has been developed. Even dispersion of the nano-particles in a double-base propellant has been demonstrated using a solvent-based processing approach. Stability of a composite propellant with the BN additive was verified. In this paper, results from propellant testing of boron nitride nano-composite propellants are presented, including closed bomb and wear and erosion testing. Detailed characterization of the erosion tester substrates before and after firing was obtained by electron microscopy, inductively coupled plasma and x-ray photoelectron spectroscopy. This promising boron nitride additive shows the ability to improve gun wear and erosion resistance without any destabilizing effects to the propellant. Potential applications could include less erosive propellants in propellant ammunition for large, medium and small diameter fire arms.

  9. Innovative boron nitride-doped propellants

    Directory of Open Access Journals (Sweden)

    Thelma Manning

    2016-04-01

    Full Text Available The U.S. military has a need for more powerful propellants with balanced/stoichiometric amounts of fuel and oxidants. However, balanced and more powerful propellants lead to accelerated gun barrel erosion and markedly shortened useful barrel life. Boron nitride (BN is an interesting potential additive for propellants that could reduce gun wear effects in advanced propellants (US patent pending 2015-026P. Hexagonal boron nitride is a good lubricant that can provide wear resistance and lower flame temperatures for gun barrels. Further, boron can dope steel, which drastically improves its strength and wear resistance, and can block the formation of softer carbides. A scalable synthesis method for producing boron nitride nano-particles that can be readily dispersed into propellants has been developed. Even dispersion of the nano-particles in a double-base propellant has been demonstrated using a solvent-based processing approach. Stability of a composite propellant with the BN additive was verified. In this paper, results from propellant testing of boron nitride nano-composite propellants are presented, including closed bomb and wear and erosion testing. Detailed characterization of the erosion tester substrates before and after firing was obtained by electron microscopy, inductively coupled plasma and x-ray photoelectron spectroscopy. This promising boron nitride additive shows the ability to improve gun wear and erosion resistance without any destabilizing effects to the propellant. Potential applications could include less erosive propellants in propellant ammunition for large, medium and small diameter fire arms.

  10. Proceedings of workshop on 'boron science and boron neutron capture therapy'

    Energy Technology Data Exchange (ETDEWEB)

    Kitaoka, Y. [ed.

    1998-12-01

    This volume contains the abstracts and programs of the 8th (1996), 9th (1997) and 10th (1998) of the workshop on 'the Boron Science and Boron Neutron Capture Therapy' and the recent progress reports especially subscribed. The 11 of the presented papers are indexed individually. (J.P.N.)

  11. The effect of boron deficiency on gene expression and boron compartmentalization in sugarbeet

    Science.gov (United States)

    NIP5, BOR1, NIP6, and WRKY6 genes were investigated for their role in boron deficiency in sugar beet, each with a proposed role in boron use in model plant species. All genes showed evidence of polymorphism in fragment size and gene expression in the target genomic DNA and cDNA libraries, with no co...

  12. Junctions between a boron nitride nanotube and a boron nitride sheet.

    Science.gov (United States)

    Baowan, Duangkamon; Cox, Barry J; Hill, James M

    2008-02-20

    For future nanoelectromechanical signalling devices, it is vital to understand how to connect various nanostructures. Since boron nitride nanostructures are believed to be good electronic materials, in this paper we elucidate the classification of defect geometries for combining boron nitride structures. Specifically, we determine possible joining structures between a boron nitride nanotube and a flat sheet of hexagonal boron nitride. Firstly, we determine the appropriate defect configurations on which the tube can be connected, given that the energetically favourable rings for boron nitride structures are rings with an even number of sides. A new formula E = 6+2J relating the number of edges E and the number of joining positions J is established for each defect, and the number of possible distinct defects is related to the so-called necklace and bracelet problems of combinatorial theory. Two least squares approaches, which involve variation in bond length and variation in bond angle, are employed to determine the perpendicular connection of both zigzag and armchair boron nitride nanotubes with a boron nitride sheet. Here, three boron nitride tubes, which are (3, 3), (6, 0) and (9, 0) tubes, are joined with the sheet, and Euler's theorem is used to verify geometrically that the connected structures are sound, and their relationship with the bonded potential energy function approach is discussed. For zigzag tubes (n,0), it is proved that such connections investigated here are possible only for n divisible by 3.

  13. Spectromicroscopy of boron for the optimization of boron neutron capture therapy (BNCT) for cancer

    Science.gov (United States)

    Gilbert, B.; Redondo, J.; Baudat, P.-A.; Lorusso, G. F.; Andres, R.; Van Meir, E. G.; Brunet, J.-F.; Hamou, M.-F.; Suda, T.; Mercanti, Delio; Ciotti, M. Teresa; Droubay, T. C.; Tonner, B. P.; Perfetti, P.; Margaritondo, M.; DeStasio, Gelsomina

    1998-10-01

    We used synchrotron spectromicroscopy to study the microscopic distribution of boron in rat brain tumour and healthy tissue in the field of boron neutron capture therapy (BNCT). The success of this experimental cancer therapy depends on the preferential uptake of ? in tumour cells after injection of a boron compound (in our case ?, or BSH). With the Mephisto (microscope à emission de photoélectrons par illumination synchrotronique de type onduleur) spectromicroscope, high-magnification imaging and chemical analysis was performed on brain tissue sections from a rat carrying an implanted brain tumour and the results were compared with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) detection of boron in bulk tissue. Boron was found to have been taken up more favourably by regions of tumour rather than healthy tissue, but the resulting boron distribution in the tumour was inhomogeneous. The results demonstrate that Mephisto can perform microchemical analysis of tissue sections, detect and localize the presence of boron with submicron spatial resolution. The application of this technique to boron in brain tissue can therefore be used to evaluate the current efforts to optimize BNC therapy.

  14. Spectromicroscopy of boron for the optimization of boron neutron capture therapy (BNCT) for cancer

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, B.; Redondo, J.; Baudat, P-A. [Institut de Physique Appliquee, Ecole Polytechnique Federale, Lausanne (Switzerland)] [and others

    1998-10-07

    We used synchrotron spectromicroscopy to study the microscopic distribution of boron in rat brain tumour and healthy tissue in the field of boron neutron capture therapy (BNCT). The success of this experimental cancer therapy depends on the preferential uptake of {sup 10}B in tumour cells after injection of a boron compound (in our case B{sub 12}H{sub 11}SH, or BSH). With the Mephisto (microscope a emission de photoelectrons par illumination synchrotronique de type onduleur) spectromicroscope, high-magnification imaging and chemical analysis was performed on brain tissue sections from a rat carrying an implanted brain tumour and the results were compared with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) detection of boron in bulk tissue. Boron was found to have been taken up more favourably by regions of tumour rather than healthy tissue, but the resulting boron distribution in the tumour was inhomogeneous. The results demonstrate that Mephisto can perform microchemical analysis of tissue sections, detect and localize the presence of boron with submicron spatial resolution. The application of this technique to boron in brain tissue can therefore be used to evaluate the current efforts to optimize BNC therapy. (author)

  15. Ceramic silicon-boron-carbon fibers from organic silicon-boron-polymers

    Science.gov (United States)

    Riccitiello, Salvatore R. (Inventor); Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

    1993-01-01

    Novel high strength ceramic fibers derived from boron, silicon, and carbon organic precursor polymers are discussed. The ceramic fibers are thermally stable up to and beyond 1200 C in air. The method of preparation of the boron-silicon-carbon fibers from a low oxygen content organosilicon boron precursor polymer of the general formula Si(R2)BR(sup 1) includes melt-spinning, crosslinking, and pyrolysis. Specifically, the crosslinked (or cured) precursor organic polymer fibers do not melt or deform during pyrolysis to form the silicon-boron-carbon ceramic fiber. These novel silicon-boron-carbon ceramic fibers are useful in high temperature applications because they retain tensile and other properties up to 1200 C, from 1200 to 1300 C, and in some cases higher than 1300 C.

  16. A quantitative comparison between electrocoagulation and chemical coagulation for boron removal from boron-containing solution

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, A. Erdem [Atatuerk University, Faculty of Engineering, Department of Environmental Engineering, 25240 Erzurum (Turkey)], E-mail: aerdemy@atauni.edu.tr; Boncukcuoglu, Recep [Atatuerk University, Faculty of Engineering, Department of Environmental Engineering, 25240 Erzurum (Turkey); Kocakerim, M. Muhtar [Atatuerk University, Faculty of Engineering, Department of Chemical Engineering, 25240 Erzurum (Turkey)

    2007-10-22

    This paper provides a quantitative comparison of electrocoagulation and chemical coagulation approaches based on boron removal. Electrocoagulation process delivers the coagulant in situ as the sacrificial anode corrodes, due to a fixed current density, while the simultaneous evolution of hydrogen at the cathode allows for pollutant removal by flotation. By comparison, conventional chemical coagulation typically adds a salt of the coagulant, with settling providing the primary pollutant removal path. Chemical coagulation was carried out via jar tests using aluminum chloride. Comparison was done with the same amount of coagulant between electrocoagulation and chemical coagulation processes. Boron removal obtained was higher with electrocoagulation process. In addition, it was seen that chemical coagulation has any effect for boron removal from boron-containing solution. At optimum conditions (e.g. pH 8.0 and aluminum dose of 7.45 g/L), boron removal efficiencies for electrocoagulation and chemical coagulation were 94.0% and 24.0%, respectively.

  17. A quantitative comparison between electrocoagulation and chemical coagulation for boron removal from boron-containing solution.

    Science.gov (United States)

    Yilmaz, A Erdem; Boncukcuoğlu, Recep; Kocakerim, M Muhtar

    2007-10-22

    This paper provides a quantitative comparison of electrocoagulation and chemical coagulation approaches based on boron removal. Electrocoagulation process delivers the coagulant in situ as the sacrificial anode corrodes, due to a fixed current density, while the simultaneous evolution of hydrogen at the cathode allows for pollutant removal by flotation. By comparison, conventional chemical coagulation typically adds a salt of the coagulant, with settling providing the primary pollutant removal path. Chemical coagulation was carried out via jar tests using aluminum chloride. Comparison was done with the same amount of coagulant between electrocoagulation and chemical coagulation processes. Boron removal obtained was higher with electrocoagulation process. In addition, it was seen that chemical coagulation has any effect for boron removal from boron-containing solution. At optimum conditions (e.g. pH 8.0 and aluminum dose of 7.45 g/L), boron removal efficiencies for electrocoagulation and chemical coagulation were 94.0% and 24.0%, respectively.

  18. DABO Boronates: Stable Heterocyclic Boronic Acid Complexes for Use in Suzuki-Miyaura Cross-Coupling Reactions.

    Science.gov (United States)

    Reilly, Maureen K; Rychnovsky, Scott D

    2011-10-01

    Diethanolamine complexed heterocyclic boronic acids (DABO boronates) are air-stable reagents that can be used directly in Suzuki-Miyaura reactions in the presence of water or a protic co-solvent. Interestingly, heterocyclic DABO boronates can be stored for extended periods of time at room temperature with no noticeable degradation, unlike their boronic acid counterparts. Heterocyclic DABO boronates constitute an operationally simple and efficient alternative to other boronic acid derivatives as coupling partners in palladium catalyzed cross-coupling reactions under standard Suzuki-Miyaura conditions.

  19. Boron remobilization at low boron supply in olive (Olea europaea) in relation to leaf and phloem mannitol concentrations.

    Science.gov (United States)

    Liakopoulos, Georgios; Stavrianakou, Sotiria; Filippou, Manolis; Fasseas, Costas; Tsadilas, Christos; Drossopoulos, Ioannis; Karabourniotis, George

    2005-02-01

    For plant species in which a considerable portion of the photoassimilates are translocated in the phloem as sugar alcohols, boron is freely translocated from mature organs to growing tissues. However, the effects of decreased plant boron status on boron remobilization are poorly understood. We conducted a growth chamber experiment (CE) and a field experiment (FE) to study the effects of low boron supply on boron remobilization in olive (Olea europaea L.), a species that transports considerable amounts of mannitol in the phloem. For the CE, several physiological parameters were compared between control (B+) and boron-deficient olive plants (B-) during the expansion of new leaves. Boron remobilization was assessed by measuring boron content of selected leaves at the beginning and at the end of the CE. As expected, boron was remobilized from mature leaves to young leaves of B+ plants; however, considerable boron remobilization was also observed in B- plants, suggesting a mechanism whereby olive can sustain a minimum boron supply for growth of new tissues despite an insufficient external boron supply. Boron deficiency caused inhibition of new growth but had no effect on photosynthetic capacity per unit leaf surface area of young and mature leaves, thereby altering the carbon utilization pattern and resulting in carbon allocation to structures within the source leaves and accumulation of soluble carbohydrates. Specifically, in mature B- leaves in the CE and in B- leaves in the FE, mannitol concentration on a leaf water content basis increased by 48 and 27% respectively, compared with controls. Carbon export ability (assessed by both phloem anatomy and phloem exudate composition of FE leaves) was enhanced at low boron supply. We conclude that, at low boron supply, increased mannitol concentrations maintain boron remobilization from source leaves to boron-demanding sink leaves.

  20. Studies on Separation Process and Production Technology of Boron Isotope

    Directory of Open Access Journals (Sweden)

    LI Jian-ping

    2014-02-01

    Full Text Available The boron isotopes separation test was performed by chemical exchange reaction in the benzene ether -three boron fluoride system, which resulted to the boron isotopic enrichment of -10 in the liquid phase, the boron isotopic enrichment of -11 in the gas phase. After then, boron isotope separation trial production has been finished. In this process, the exchange column and complex tower normal operating parameters and the complex tower technology have been obtained, the problems of material distillation purification is solved, boron isotopes feasibility with PTFE packing enrichment is verified in an exchange column. Also, effect of operating pressure, flow and other parameters on boron -10 isotopic enrichment experiments and the effect and properties of the PTFE packing have been investigated in the existing system. All the results are very useful for the industrialization of the boron isotopes separation system.

  1. Method of manufacture of atomically thin boron nitride

    Science.gov (United States)

    Zettl, Alexander K

    2013-08-06

    The present invention provides a method of fabricating at least one single layer hexagonal boron nitride (h-BN). In an exemplary embodiment, the method includes (1) suspending at least one multilayer boron nitride across a gap of a support structure and (2) performing a reactive ion etch upon the multilayer boron nitride to produce the single layer hexagonal boron nitride suspended across the gap of the support structure. The present invention also provides a method of fabricating single layer hexagonal boron nitride. In an exemplary embodiment, the method includes (1) providing multilayer boron nitride suspended across a gap of a support structure and (2) performing a reactive ion etch upon the multilayer boron nitride to produce the single layer hexagonal boron nitride suspended across the gap of the support structure.

  2. Characterization of boron carbide with an electron microprobe

    Science.gov (United States)

    Matteudi, G.; Ruste, J.

    1983-01-01

    Within the framework of a study of heterogeneous materials (Matteudi et al., 1971: Matteudi and Verchery, 1972) thin deposits of boron carbide were characterized. Experiments using an electronic probe microanalyzer to analyze solid boron carbide or boron carbide in the form of thick deposits are described. Quantitative results on boron and carbon are very close to those obtained when applying the Monte Carlo-type correction calculations.

  3. Against Drought Stress Effect of Antioxidant Enzymes of Boron

    Directory of Open Access Journals (Sweden)

    Mahmut Doğan

    2013-04-01

    Full Text Available In this study, soybean seeds (Glycine max. L., cv., “A3935 were grown under controlled conditions (25±2 C composed of different boron compounds. In the experiment, 5 groups were determined respectively as potassium tetraborate tetrahydrate (1 mg/1, ammonium tetraborate tetrahydrate (1 mg/1, sodium boron hydride (1 mg/1, lithium tetraborate tetrahydrate (100 mg/1, and sodium tetraborate decahydrate (100 mg/1. The doses used in this study were determined according to the results of a preliminary study. Soybean seeds were exposed to different amounts of drought stress based on time (control, 3, 6, 9, 12, 15, and 18 days. Activities of antioxidant enzymes superoxide dismutase (SOD: EC 1.15.1.1, glutathione reductase (GR: EC 1.6.4.2, ascorbate peroxidase (APX: EC 1.11.1.11 and catalase (CAT: EC 1.11.1.6 measured. According to the results stress+potassium tetraborate tetrahydrate environment has increased the amount of CAT, decreased the amount GR, APX and SOD. Potassium tetraborate 0.1 mg / l dose administration is the most appropriate critical value, and the most important indicator of drought CAT enzyme found to give the best results.

  4. Boron Removal in Seawater Reverse Osmosis System

    KAUST Repository

    Rahmawati, Karina

    2011-07-01

    Reverse osmosis successfully proves to remove more than 99% of solute in seawater, providing fresh water supply with satisfied quality. Due to some operational constraints, however, some trace contaminants removal, such as boron, cannot be achieved in one pass system. The stringent criterion for boron from World Health Organization (WHO) and Saudi Arabia local standard (0.5 mg/l) is hardly fulfilled by single pass sea water reverse osmosis (SWRO) plants. Some design processes have been proposed to deal with boron removal, but they are not economically efficient due to high energy and chemical consumption. The objective of this study was to study boron removal by different reverse osmosis membranes in two pH conditions, with and without antiscalant addition. Thus, it was expected to observe the possibility of operating single pass system and necessity to operate two pass system using low energy membrane. Five membrane samples were obtained from two different manufacturers. Three types of feed water pH were used, pH 8, pH 10, and pH 10 with antiscalant addition. Experiment was conducted in parallel to compare membrane performance from two manufacturers. Filtration was run with fully recycle mode for three days. Sample of permeate and feed were taken every 12 hours, and analyzed for their boron and TDS concentration. Membrane samples were also tested for their surface charge. The results showed that boron rejection increases as the feed pH increases. This was caused by dissociation of boric acid to negatively charged borate ion and more negatively charged membrane surface at elevated pH which enhance boron rejection. This study found that single pass reverse osmosis system, with and without elevating the pH, may not be possible to be applied because of two reasons. First, permeate quality in term of boron, does not fulfill WHO and local Saudi Arabia regulations. Second, severe scaling occurs due to operation in alkaline condition, since Ca and Mg concentration are

  5. First gaseous boronization during pulsed discharge cleaning

    Science.gov (United States)

    Ko, J.; Den Hartog, D. J.; Goetz, J. A.; Weix, P. J.; Limbach, S. T.

    2013-01-01

    The first successful gaseous boronization during a pulsed discharge is reported. Sublimation of o-carborane (C2B10H12) combined with pulsed discharge plasmas with a repetition rate of 1 Hz is used to produce a hard boron-containing coating for reversed field pinch (RFP) plasmas in the Madison Symmetric Torus. X-ray photoelectron spectroscopy with Ar ion beam etching for silicon coupons installed at the plasma boundary shows about 60% boron concentration in the deposited layer. Both profilometer and scanning electron microscope analyses of the silicon coupons imply a strong toroidally non-uniform deposition depending on the location of the o-carborane injection. The layer thickness ranges from 50 to 300 nm. Ellipsometry calibrated with the profilometer results yields a refractive index of 2.2-2.3 for the films. The high refractive index implies that the coating is hard and has a well-ordered morphology. A reduction in wall recycling has consistently been observed after all boronization sessions. Comparison of the X-ray spectra in standard RFP plasmas before and after boronization indicates a slight decrease in the effective ionic charge.

  6. First gaseous boronization during pulsed discharge cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Ko, J., E-mail: jinseok@nfri.re.kr [Department of Physics, University of Wisconsin, Madison, WI (United States); Den Hartog, D.J.; Goetz, J.A.; Weix, P.J.; Limbach, S.T. [Department of Physics, University of Wisconsin, Madison, WI (United States)

    2013-01-15

    The first successful gaseous boronization during a pulsed discharge is reported. Sublimation of o-carborane (C{sub 2}B{sub 10}H{sub 12}) combined with pulsed discharge plasmas with a repetition rate of 1 Hz is used to produce a hard boron-containing coating for reversed field pinch (RFP) plasmas in the Madison Symmetric Torus. X-ray photoelectron spectroscopy with Ar ion beam etching for silicon coupons installed at the plasma boundary shows about 60% boron concentration in the deposited layer. Both profilometer and scanning electron microscope analyses of the silicon coupons imply a strong toroidally non-uniform deposition depending on the location of the o-carborane injection. The layer thickness ranges from 50 to 300 nm. Ellipsometry calibrated with the profilometer results yields a refractive index of 2.2-2.3 for the films. The high refractive index implies that the coating is hard and has a well-ordered morphology. A reduction in wall recycling has consistently been observed after all boronization sessions. Comparison of the X-ray spectra in standard RFP plasmas before and after boronization indicates a slight decrease in the effective ionic charge.

  7. Axial residual stresses in boron fibers

    Science.gov (United States)

    Behrendt, D. R.

    1978-01-01

    A method of measuring axial residual stresses in boron fibers is presented. With this method, the axial residual stress distribution as a function of radius is determined from the fiber surface to the core including the average residual stress in the core. Such measurements on boron on tungsten (B/W) fibers show that the residual stresses for 102, 142, 203, and 366 micron diam fibers are similar, being compressive at the surface and changing monotonically to a region of tensile stress within the boron. At approximately 25% of the original radius, the stress reaches a maximum tensile stress of about 860 MN sq m and then decreases to a compressive stress near the tungsten boride core. Data are presented for 203-micron diam B/W fibers that show annealing above 900 C reduces the residual stresses. A comparison between 102-micron diam B/W and boron on carbon (B/C) show that the residual stresses are similar in the outer regions of the fibers, but that large differences near and in the core are observed. Fracture of boron fibers is discussed.

  8. Update on human health effects of boron.

    Science.gov (United States)

    Nielsen, Forrest H

    2014-10-01

    In vitro, animal, and human experiments have shown that boron is a bioactive element in nutritional amounts that beneficially affects bone growth and central nervous system function, alleviates arthritic symptoms, facilitates hormone action and is associated with a reduced risk for some types of cancer. The diverse effects of boron suggest that it influences the formation and/or activity of substances that are involved in numerous biochemical processes. Several findings suggest that this influence is through the formation of boroesters in biomolecules containing cis-hydroxyl groups. These biomolecules include those that contain ribose (e.g., S-adenosylmethionine, diadenosine phosphates, and nicotinamide adenine dinucleotide). In addition, boron may form boroester complexes with phosphoinositides, glycoproteins, and glycolipids that affect cell membrane integrity and function. Both animal and human data indicate that an intake of less than 1.0mg/day inhibits the health benefits of boron. Dietary surveys indicate such an intake is not rare. Thus, increasing boron intake by consuming a diet rich in fruits, vegetables, nuts and pulses should be recognized as a reasonable dietary recommendation to enhance health and well-being.

  9. INFLUENCE OF FINE-DISPERSED BORON CARBIDE ON THE STRUCTURE AND CHARACTERISTICS OF IRON-BORON ALLOY

    Directory of Open Access Journals (Sweden)

    N. F. Nevar

    2010-01-01

    Full Text Available The influence of boron carbide as fine-dispersed material input into the melt on structure morphology, founding, technological and exploitation characterisstics of cast iron-boron material is shown.

  10. Dietary boron: possible roles in human and animal physiology

    Science.gov (United States)

    Boron is a bioactive element of low molecular weight. Since discovery of the first boron biomolecule, boromycin, in 1967, several other similar biomolecules are now well-characterized. Most recently described was a bacterial cell-to-cell communication signal that requires boron, autoinducer-II. Boro...

  11. IMPROVEMENT OF TYPE IV CRACKING RESISTANCE OF 9Cr HEAT RESISTING STEEL WELDMENT BY BORON ADDITION

    Institute of Scientific and Technical Information of China (English)

    M.Tabuchi; M.Kondo; T.Watanabe; H.Hongo; F.Yin; F.Abe

    2004-01-01

    Creep lives of high Cr ferritic heat resisting steel weldments decrease due to Type IV fracture, which occurs as a result of formation and growth of creep voids and cracks on grain boundaries in fine-grained heat affected zone (HAZ). Because boron is considered to suppress the coarsening of grain boundary precipitates and growth of creep voids, we have investigated the effect of boron addition on the creep properties of 9Cr steel weldments. Four kinds of 9Cr3W3CoVNb steels with boron content varying from 4.7×10-5 to 1.8×10-4 and with nitrogen as low as 2.0×10-5 were prepared.The steel plates were welded by gas tungsten arc welding and crept at 923K. It was found that the microstructures of HAZ were quite different from those of conventional high Cr steels such as P91 and P92, namely the fine-grained HAZ did not exist in the present steel weldments. Boron addition also has the effect to suppress coarsening of grain boundary carbides in HAZ during creep. As a result of these phenomena,the welded joints of present steels showed no Type IV fractures and much better creep lives than those of conventional steels.

  12. Probing Field Emission from Boron Carbide Nanowires

    Institute of Scientific and Technical Information of China (English)

    TIAN Ji-Fa; GAO Hong-Jun; BAO Li-Hong; WANG Xing-Jun; HUI Chao; LIU Fei; LI Chen; SHEN Cheng-Min; WANG Zong-Li; GU Chang-Zhi

    2008-01-01

    High density boron carbide nanowires are grown by an improved carbon thermal reduction technique. Transmission electron microscopy and electron energy lose spectroscopy of the sample show that the synthesized nanowires are B4 C with good crystallization. The field emission measurement for an individual boron nanowire is performed by using a Pt tip installed in the focused ion beam system. A field emission current with enhancement factor of 106 is observed and the evolution process during emission is also carefully studied. Furthermore, a two-step field emission with stable emission current density is found from the high-density nanowire film. Our results together suggest that boron carbide nanowires are promising candidates for electron emission nanodevices.

  13. Depth resolved investigations of boron implanted silicon

    Energy Technology Data Exchange (ETDEWEB)

    Sztucki, M. E-mail: michael@sztucki.de; Metzger, T.H.; Milita, S.; Berberich, F.; Schell, N.; Rouviere, J.L.; Patel, J

    2003-01-01

    We have studied the depth distribution and structure of defects in boron implanted silicon (0 0 1). Silicon wafers were implanted with a boron dose of 6x10{sup 15} ions/cm{sup -2} at 32 keV and went through different annealing treatments. Using diffuse X-ray scattering at grazing incidence and exit angles we are able to distinguish between different kinds of defects (point defect clusters and extrinsic stacking faults on {l_brace}1 1 1{r_brace} planes) and to determine their depth distribution as a function of the thermal budget. Cross-section transmission electron microscopy was used to gain complementary information. In addition we have determined the strain distribution caused by the boron implantation as a function of depth from rocking curve measurements.

  14. Oxygen radical functionalization of boron nitride nanosheets.

    Science.gov (United States)

    Sainsbury, Toby; Satti, Amro; May, Peter; Wang, Zhiming; McGovern, Ignatius; Gun'ko, Yurii K; Coleman, Jonathan

    2012-11-14

    The covalent chemical functionalization of exfoliated hexagonal boron-nitride nanosheets (BNNSs) is achieved by the solution-phase oxygen radical functionalization of boron atoms in the h-BN lattice. This involves a two-step procedure to initially covalently graft alkoxy groups to boron atoms and the subsequent hydrolytic defunctionalization of the groups to yield hydroxyl-functionalized BNNSs (OH-BNNSs). Characterization of the functionalized-BNNSs using HR-TEM, Raman, UV-vis, FTIR, NMR, and TGA was performed to investigate both the structure of the BNNSs and the covalent functionalization methodology. OH-BNNSs were used to prepare polymer nanocomposites and their mechanical properties analyzed. The influence of the functional groups grafted to the surface of the BNNSs is investigated by demonstrating the impact on mechanical properties of both noncovalent and covalent bonding at the interface between the nanofiller and polymer matrixes.

  15. Lateral gas phase diffusion length of boron atoms over Si/B surfaces during CVD of pure boron layers

    NARCIS (Netherlands)

    Mohammadi, V.; Nihtianov, S.

    2016-01-01

    The lateral gas phase diffusion length of boron atoms, LB, along silicon and boron surfaces during chemical vapor deposition(CVD) using diborane (B2H6) is reported. The value of LB is critical for reliable and uniform boron layer coverage. The presented information was obtained experimentally and co

  16. Boron removal by electrocoagulation and recovery.

    Science.gov (United States)

    Isa, Mohamed Hasnain; Ezechi, Ezerie Henry; Ahmed, Zubair; Magram, Saleh Faraj; Kutty, Shamsul Rahman Mohamed

    2014-03-15

    This work investigated the removal of boron from wastewater and its recovery by electrocoagulation and hydrothermal mineralization methods respectively. The experimental design was developed using Box-Behnken Model. An initial study was performed based on four preselected variables (pH, current density, concentration and time) using synthetic wastewater. Response surface methodology (RSM) was used to evaluate the effect of process variables and their interaction on boron removal. The optimum conditions were obtained as pH 6.3, current density 17.4 mA/cm(2), and time 89 min. At these applied optimum conditions, 99.7% boron removal from an initial concentration of 10.4 mg/L was achieved. The process was effectively optimized by RSM with a desirability value of 1.0. The results showed that boron removal efficiency enhanced with increase in current density and treatment time. Removal efficiency also increased when pH was increased from 4 to 7 and subsequently decreased at pH 10. Adsorption kinetics study revealed that the reaction followed pseudo second order kinetic model; evidenced by high correlation and goodness of fit. Thermodynamics study showed that mechanism of boron adsorption was chemisorption and the reaction was endothermic in nature. Furthermore, the adsorption process was spontaneous as indicated by negative values of the adsorption free energy. Treatment of real produced water using electrocoagulation resulted in 98% boron removal. The hydrothermal mineralization study showed that borate minerals (Inyoite, Takadaite and Nifontovite) can be recovered as recyclable precipitate from electrocoagulation flocs of produced water.

  17. Molecular Medicine: Synthesis and In Vivo Detection of Agents for use in Boron Neutron Capture Therapy. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Kabalka, G. W.

    2005-06-28

    The primary objective of the project was the development of in vivo methods for the detection and evaluation of tumors in humans. The project was focused on utilizing positron emission tomography (PET) to monitor the distribution and pharamacokinetics of a current boron neutron capture therapy (BNCT) agent, p-boronophenylalanine (BPA) by labeling it with a fluorine-18, a positron emitting isotope. The PET data was then used to develop enhanced treatment planning protocols. The study also involved the synthesis of new tumor selective BNCTagents that could be labeled with radioactive nuclides for the in vivo detection of boron.

  18. Ultrahard nanotwinned cubic boron nitride.

    Science.gov (United States)

    Tian, Yongjun; Xu, Bo; Yu, Dongli; Ma, Yanming; Wang, Yanbin; Jiang, Yingbing; Hu, Wentao; Tang, Chengchun; Gao, Yufei; Luo, Kun; Zhao, Zhisheng; Wang, Li-Min; Wen, Bin; He, Julong; Liu, Zhongyuan

    2013-01-17

    Cubic boron nitride (cBN) is a well known superhard material that has a wide range of industrial applications. Nanostructuring of cBN is an effective way to improve its hardness by virtue of the Hall-Petch effect--the tendency for hardness to increase with decreasing grain size. Polycrystalline cBN materials are often synthesized by using the martensitic transformation of a graphite-like BN precursor, in which high pressures and temperatures lead to puckering of the BN layers. Such approaches have led to synthetic polycrystalline cBN having grain sizes as small as ∼14 nm (refs 1, 2, 4, 5). Here we report the formation of cBN with a nanostructure dominated by fine twin domains of average thickness ∼3.8 nm. This nanotwinned cBN was synthesized from specially prepared BN precursor nanoparticles possessing onion-like nested structures with intrinsically puckered BN layers and numerous stacking faults. The resulting nanotwinned cBN bulk samples are optically transparent with a striking combination of physical properties: an extremely high Vickers hardness (exceeding 100 GPa, the optimal hardness of synthetic diamond), a high oxidization temperature (∼1,294 °C) and a large fracture toughness (>12 MPa m(1/2), well beyond the toughness of commercial cemented tungsten carbide, ∼10 MPa m(1/2)). We show that hardening of cBN is continuous with decreasing twin thickness down to the smallest sizes investigated, contrasting with the expected reverse Hall-Petch effect below a critical grain size or the twin thickness of ∼10-15 nm found in metals and alloys.

  19. Boron nitride nanotubes for spintronics.

    Science.gov (United States)

    Dhungana, Kamal B; Pati, Ranjit

    2014-09-22

    With the end of Moore's law in sight, researchers are in search of an alternative approach to manipulate information. Spintronics or spin-based electronics, which uses the spin state of electrons to store, process and communicate information, offers exciting opportunities to sustain the current growth in the information industry. For example, the discovery of the giant magneto resistance (GMR) effect, which provides the foundation behind modern high density data storage devices, is an important success story of spintronics; GMR-based sensors have wide applications, ranging from automotive industry to biology. In recent years, with the tremendous progress in nanotechnology, spintronics has crossed the boundary of conventional, all metallic, solid state multi-layered structures to reach a new frontier, where nanostructures provide a pathway for the spin-carriers. Different materials such as organic and inorganic nanostructures are explored for possible applications in spintronics. In this short review, we focus on the boron nitride nanotube (BNNT), which has recently been explored for possible applications in spintronics. Unlike many organic materials, BNNTs offer higher thermal stability and higher resistance to oxidation. It has been reported that the metal-free fluorinated BNNT exhibits long range ferromagnetic spin ordering, which is stable at a temperature much higher than room temperature. Due to their large band gap, BNNTs are also explored as a tunnel magneto resistance device. In addition, the F-BNNT has recently been predicted as an ideal spin-filter. The purpose of this review is to highlight these recent progresses so that a concerted effort by both experimentalists and theorists can be carried out in the future to realize the true potential of BNNT-based spintronics.

  20. Dietary boron: progress in establishing essential roles in human physiology.

    Science.gov (United States)

    Hunt, Curtiss D

    2012-06-01

    This review summarizes the progress made in establishing essential roles for boron in human physiology and assesses that progress in view of criteria for essentiality of elements. The evidence to date suggests that humans and at least some higher animals may use boron to support normal biological functions. These include roles in calcium metabolism, bone growth and maintenance, insulin metabolism, and completion of the life cycle. The biochemical mechanisms responsible for these effects are poorly understood but the nature of boron biochemistry suggests further characterization of the cell signaling molecules capable of complexing with boron. Such characterization may provide insights into the biochemical function(s) of boron in humans.

  1. Nuclear quadrupole resonance of boron in borate glasses

    Science.gov (United States)

    Gravina, Samuel J.; Bray, Phillip J.

    A continuous wave nuclear quadrupole resonance spectrometer that has a high sensitivity even at low frequencies has been built. Boron and aluminum NQR has been detected in the region 200 kHz to 1.4 MHz. For the first time, boron NQR has been detected in a glass. The NQR spectrum of pure B 20 3 glass is consistent with 85 ± 2% of the boron atoms belonging to boroxol rings. In sodium borate glasses, the number of borons in boroxol rings decreases with increasing sodium content, until when sodium oxide comprises 20 mol% of the glass less than 2% of the borons are in boroxol rings.

  2. Geochemical study of boron isotopes in the process of loess weathering

    Institute of Scientific and Technical Information of China (English)

    ZHAO; Zhiqi; (

    2003-01-01

    from sea-water, Earth Planet Sci. Lett., 1969, 6: 1-5.[13]Palmer, M. R., Spivack, A. J., Edmond, J. M., Temperature and pH controls over isotopic fractionation during adsorption of boron on marine clay, Geochim Cosmochim Acta, 1987, 51: 2319-2323.[14]Vengosh, A., Kolodny, Y., Starinsky, A. et al., Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates, Geochim. Cosmochim. Acta, 1991, 55: 2901-2910.[15]Hemming, N. G., Hanson, G. N., Boron isotopic composition and concentration in modern marine carbonates, Geochim. Cosmochim. Acta, 1992, 56: 537-543.[16]Porter, S. C., An Zhisheng, Correlation between climate events in the North Atlantic and China during the last glaciation, Nature, 1995, 375: 305-308.[17]Guo, Z. T., Liu, T. S., Guiot, J. et al., High frequency pulses of east Asian monsoon climate in the last two glaciations: Link with the North Atlantic, Climate Dynamics, 1996, 12: 701-709.[18]Chen Jun, An Zhisheng, Wang Yongjin et al., Distribution of Rb and Sr in the Luochuan loess-paleosol sequence of China during the last 800 ka: Implications for paleomosoon variations, Science in China, Ser. D, 1999, 42 (3): 225-232.[19]Lemarchand, D., Gaillardet, J., Lewin, E. et al., The influence of rivers on marine boron isotopes and implications for reconstructing past ocean pH, Nature, 2000, 408: 951-954.[20]Spivack, A. J., You, C. F., Smith, H. J., Foraminiferal boron isotope ratios as a proxy for surface ocean pH over the past 21 Myr., Nature, 1993, 363: 149-151.[21]Sanayal, A., Hemming, N. G., Evidence for a higher pH in the glacial ocean from boron isotopes in foraminifer., Nature, 1995, 373: 234-236.[22]Palmer, M. R., Pearson, P. N., Cobb, S. J., Reconstructing past ocean pH-depth profiles, Science, 1998, 282: 1468-1471.[23]Pearson, P. N., Palmer, M. R., Middle Eocene seawater pH and atmospheric carbon dioxide concentrations, Science, 1999, 284: 1824-1826.[24]Pearson, P. N., Palmer, M. R

  3. Hollow boron nitride nanospheres as boron reservoir for prostate cancer treatment

    Science.gov (United States)

    Li, Xia; Wang, Xiupeng; Zhang, Jun; Hanagata, Nobutaka; Wang, Xuebin; Weng, Qunhong; Ito, Atsuo; Bando, Yoshio; Golberg, Dmitri

    2017-01-01

    High global incidence of prostate cancer has led to a focus on prevention and treatment strategies to reduce the impact of this disease in public health. Boron compounds are increasingly recognized as preventative and chemotherapeutic agents. However, systemic administration of soluble boron compounds is hampered by their short half-life and low effectiveness. Here we report on hollow boron nitride (BN) spheres with controlled crystallinity and boron release that decrease cell viability and increase prostate cancer cell apoptosis. In vivo experiments on subcutaneous tumour mouse models treated with BN spheres demonstrated significant suppression of tumour growth. An orthotopic tumour growth model was also utilized and further confirmed the in vivo anti-cancer efficacy of BN spheres. Moreover, the administration of hollow BN spheres with paclitaxel leads to synergetic effects in the suppression of tumour growth. The work demonstrates that hollow BN spheres may function as a new agent for prostate cancer treatment.

  4. Relationship Between Soil Boron Adsorption Kinetics and Rape Plant Boron Response

    Institute of Scientific and Technical Information of China (English)

    ZHUDUANWEI; PIMEIMEI; 等

    1997-01-01

    The boron adsorption kinetic experiment in soil by means a flow displacement technique showed that the kinetic data could be described with some mathematic equations.The average values of the coorealtion coefficeint for zero-order,first-order,parabolic diffusion ,Elovich,power function and eponential equations were 0.957,0.982,0.981,0.984,0.981 and 0.902 ,respectively,The correlation between adsorbed boron or its other expression form and time were the highest for first-order ,parabloic diffusion Elovich,and pwer function equations,the second for the zeroorder equation,and the tlowest for the exponential equation.The parabloic diffusion equation fitted well the expermiental results,with the least standard error among the six kinetic equation,showing that the monvemetn of boron from soil solution to soil colloid surface may be controlled by boron diffusion speed.The boron content of rape seedling obtained from soil cultvation was correlated with the rate constants of the kinetic equations.The constants of first-order ,parabloic diffusion,and exponential equaitions were significanlty correlated with the boron content of the crop of NPK treatment at a 95% probaility level ,with correation coeffecients being 0.686,0.691 and 0.64 and 0.641,respectively.In the case of zero-order equation,it Was significant at 99% probability level(r=0.736),These results showed that the adsorption kinetic constants of soil boron were closely related with the rape plant response to boron.

  5. Boron carbide coating deposition on tungsten substrates from atomic fluxes of boron and carbon

    Science.gov (United States)

    Sadovskiy, Y.; Begrambekov, L.; Ayrapetov, A.; Gretskaya, I.; Grunin, A.; Dyachenko, M.; Puntakov, N.

    2016-09-01

    A device used for both coating deposition and material testing is presented in the paper. By using lock chambers, sputtering targets are easily exchanged with sample holder thus allowing testing of deposited samples with high power density electron or ion beams. Boron carbide coatings were deposited on tungsten samples. Methods of increasing coating adhesion are described in the paper. 2 μm boron carbide coatings sustained 450 heating cycles from 100 to 900 C. Ion beam tests have shown satisfactory results.

  6. Evaluation of freestanding boron-doped diamond grown by chemical vapour deposition as substrates for vertical power electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Issaoui, R.; Achard, J.; Tallaire, A.; Silva, F.; Gicquel, A. [LSPM-CNRS (formerly LIMHP), Universite Paris 13, 99, Avenue Jean-Baptiste Clement, 93430 Villetaneuse (France); Bisaro, R.; Servet, B.; Garry, G. [Thales Research and Technology France, Campus de Polytechnique, 1 Avenue Augustin Fresnel, F-91767 Palaiseau Cedex (France); Barjon, J. [GEMaC-CNRS, Universite de Versailles Saint Quentin Batiment Fermat, 45 Avenue des Etats-Unis, 78035 Versailles Cedex (France)

    2012-03-19

    In this study, 4 x 4 mm{sup 2} freestanding boron-doped diamond single crystals with thickness up to 260 {mu}m have been fabricated by plasma assisted chemical vapour deposition. The boron concentrations measured by secondary ion mass spectroscopy were 10{sup 18} to 10{sup 20} cm{sup -3} which is in a good agreement with the values calculated from Fourier transform infrared spectroscopy analysis, thus indicating that almost all incorporated boron is electrically active. The dependence of lattice parameters and crystal mosaicity on boron concentrations have also been extracted from high resolution x-ray diffraction experiments on (004) planes. The widths of x-ray rocking curves have globally shown the high quality of the material despite a substantial broadening of the peak, indicating a decrease of structural quality with increasing boron doping levels. Finally, the suitability of these crystals for the development of vertical power electronic devices has been confirmed by four-point probe measurements from which electrical resistivities as low as 0.26 {Omega} cm have been obtained.

  7. Multi-dimensional boron transport modeling in subchannel approach: Part II. Validation of CTF boron tracking model and adding boron precipitation model

    Energy Technology Data Exchange (ETDEWEB)

    Ozdemir, Ozkan Emre, E-mail: ozdemir@psu.edu; Avramova, Maria N., E-mail: mna109@psu.edu

    2014-10-15

    Highlights: • Validation of implemented multi-dimensional subchannel boron transport model. • Extension of boron transport model to entrained droplets. • Implementation of boron precipitation model. • Testing of the boron precipitation model under transient condition. - Abstract: The risk of small-break loss of coolant accident (SB-LOCA) and other reactivity initiated transients caused by boron dilution in the light water reactors (LWRs), and the complications of tracking the soluble boron concentration experimentally inside the primary coolant have stimulated the interest in computational studies for accurate boron tracking simulations in nuclear reactors. In Part I of this study, the development and implementation of a multi-dimensional boron transport model with modified Godunov scheme based on a subchannel approach within the COBRA-TF (CTF) thermal-hydraulic code was presented. The modified Godunov scheme approach with a physical diffusion term was determined to provide the most accurate and precise solution. Current paper extends these conclusions and presents the model validation studies against experimental data from the Rossendorf coolant mixing model (ROCOM) test facility. In addition, the importance of the two-phase flow characteristics in modeling boron transient are emphasized, especially during long-term cooling period after the loss of coolant accident (LOCA) condition in pressurized water reactors (PWRs). The CTF capabilities of boron transport modeling are further improved based on the three-field representation of the two-phase flow utilized in the code. The boron transport within entrained droplets is modeled, and a model for predicting the boron precipitation under transient conditions is developed and tested. It is aimed to extend the applicability of CTF to reactor transient simulations, and particularly to a large-break loss of coolant accident (LB-LOCA) analysis.

  8. The investigation of physical conditions of boron uptake region in proton boron fusion therapy (PBFT)

    Science.gov (United States)

    Jung, Joo-Young; Yoon, Do-Kun; Lee, Heui Chang; Lu, Bo; Suh, Tae Suk

    2016-09-01

    We conducted a quantitative study to identify the effectiveness of proton boron fusion therapy (PBFT). Four simulation scenarios were designed to investigate the escalation in total dose with the proton boron reaction using a Monte Carlo n-particle extended (MCNPX 2.6.0) simulation. The peak integrated dose was obtained for three different physical conditions (i.e., boron uptake region (BUR) thickness, BUR location, and boron concentration) with differing proton beam energy (60-90 MeV). We found that the peak integrated dose was increased by up to 96.62% compared to the pristine proton Bragg-peak. For the synergetic effect to take place with 60-70 MeV proton beam, the BUR had to be at least 0.3 cm thick while spanning the Bragg-peak. Similarly to the thickness, the BUR location needed to be within 0.3 cm from the Bragg-peak when the thickness was maintained at 0.9 cm. An effective proton boron reaction required the boron concentration to be equal to or greater than 14.4 mg/g. These results demonstrate the impact of various physical and beam conditions of the PBFT, which are critical environmental factors for the treatment planning. We envision that this study will advance our understanding of the PBFT, which can be an invaluable treatment method for maximizing the potential of proton therapy.

  9. Synthesis and evaluation of boron folates for Boron-Neutron-Capture-Therapy (BNCT)

    Energy Technology Data Exchange (ETDEWEB)

    Kettenbach, Kathrin; Schieferstein, Hanno; Grunewald, Catrin; Hampel, Gabriele; Schuetz, Christian L. [Mainz Univ. (Germany). Inst. of Nuclear Chemistry; Iffland, Dorothee; Bings, Nicolas H. [Mainz Univ. (Germany). Inst. of Inorganic Chemistry and Analytical Chemistry; Reffert, Laura M. [Hannover Medical School (Germany). Radiopharmaceutical Chemistry; Ross, Tobias L. [Mainz Univ. (Germany). Inst. of Nuclear Chemistry; Hannover Medical School (Germany). Radiopharmaceutical Chemistry

    2015-07-01

    Boron neutron capture therapy (BNCT) employs {sup 10}B-pharmaceuticals administered for the treatment of malignancies, and subsequently irradiated with thermal neutrons. So far, clinical established pharmaceuticals like boron phenylalanine (BPA) or sodium boron mercaptate (BSH) use imperfect (BPA) or passive (BSH) targeting for accumulation at target sites. Due to the need of a selective transportation of boron drugs into cancer cells and sparing healthy tissues, we combined the BNCT approach with the specific and effective folate receptor (FR) targeting concept. The FR is overexpressed on many human carcinomas and provides a selective and specific target for molecular imaging as well as for tumor therapy. We synthesized and characterized a carborane-folate as well as a BSH-folate to study their in vitro characteristics and their potential as new boron-carriers for BNCT. Uptake studies were carried out using human KB cells showing a significant increase of the boron content in cells and demonstrating the successful combination of active FR-targeting and BNCT.

  10. Rapid mass-spectrometric determination of boron isotopic distribution in boron carbide.

    Science.gov (United States)

    Rein, J E; Abernathey, R M

    1972-07-01

    Boron isotopic ratios are measured in boron carbide by thermionic ionization mass spectrometry with no prior chemical separation. A powder blend of boron carbide and sodium hydroxide is prepared, a small portion is transferred to a tantalum filament, the filament is heated to produce sodium borate, and the filament is transferred to the mass spectrometer where the(11)B/(10)B ratio is measured, using the Na(2)BO(2)(+) ion. Variables investigated for their effect on preferential volatilization of (10)B include the sodium hydroxide-boron carbide ratio and the temperature and duration of filament heating. A series of boron carbide pellets containing natural boron, of the type proposed for the control rods of the Fast Flux Test Facility reactor, were analysed with an apparently unbiased result of 4.0560 for the (11)B/(10)B ratio (standard deviation 0.0087). The pellets contained over 3% metal impurities typically found in this material. Time of analysis is 45 min per sample, with one analyst.

  11. The investigation of physical conditions of boron uptake region in proton boron fusion therapy (PBFT

    Directory of Open Access Journals (Sweden)

    Joo-Young Jung

    2016-09-01

    Full Text Available We conducted a quantitative study to identify the effectiveness of proton boron fusion therapy (PBFT. Four simulation scenarios were designed to investigate the escalation in total dose with the proton boron reaction using a Monte Carlo n-particle extended (MCNPX 2.6.0 simulation. The peak integrated dose was obtained for three different physical conditions (i.e., boron uptake region (BUR thickness, BUR location, and boron concentration with differing proton beam energy (60–90 MeV. We found that the peak integrated dose was increased by up to 96.62% compared to the pristine proton Bragg-peak. For the synergetic effect to take place with 60–70 MeV proton beam, the BUR had to be at least 0.3 cm thick while spanning the Bragg-peak. Similarly to the thickness, the BUR location needed to be within 0.3 cm from the Bragg-peak when the thickness was maintained at 0.9 cm. An effective proton boron reaction required the boron concentration to be equal to or greater than 14.4 mg/g. These results demonstrate the impact of various physical and beam conditions of the PBFT, which are critical environmental factors for the treatment planning. We envision that this study will advance our understanding of the PBFT, which can be an invaluable treatment method for maximizing the potential of proton therapy.

  12. Substitution reactions at boron atoms in metallacarboranes

    Energy Technology Data Exchange (ETDEWEB)

    Bregadze, Vladimir I; Timofeev, Sergei V; Sivaev, Igor B; Lobanova, Irina A [A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow (Russian Federation)

    2004-05-31

    Data on substitution reactions at boron atoms in 10-12-vertex metallacarboranes, which are of fundamental and applied significance, are generalised. The possible mechanisms of substitution reactions and the influence of the metal fragment on substitution positions in the polyhedron are discussed.

  13. Catalytic Asymmetric Synthesis of Phosphine Boronates.

    Science.gov (United States)

    Hornillos, Valentín; Vila, Carlos; Otten, Edwin; Feringa, Ben L

    2015-06-26

    The first catalytic enantioselective synthesis of ambiphilic phosphine boronate esters is presented. The asymmetric boration of α,β-unsaturated phosphine oxides catalyzed by a copper bisphosphine complex affords optically active organoboronate esters that bear a vicinal phosphine oxide group in good yields and high enantiomeric excess. The synthetic utility of the products is demonstrated through stereospecific transformations into multifunctional optically active compounds.

  14. NEW ADVANCES IN BORON SOIL CHEMISTRY

    Science.gov (United States)

    Boron is an essential plant micronutrient for which the range between deficiency and toxicity is narrower than for any other nutrient element. Plants respond directly to the amount of B in soil solution and only indirectly to the amount of B adsorbed on soil particle surfaces. ...

  15. New insight into pecan boron nutrition

    Science.gov (United States)

    Alternate bearing by individual pecan [Carya illinoinensis (Wangenh.) K. Koch] trees is problematic for nut producers and processors. There are many unknowns regarding alternate bearing physiology, such as the relationship between boron and fruit set, nutmeat quality, and kernel maladies. Evidence...

  16. Trapping and Sympathetic Cooling of Boron Ions

    CERN Document Server

    Rugango, Rene; Shu, Gang; Brown, Kenneth R

    2016-01-01

    We demonstrate the trapping and sympathetic cooling of B$^{+}$ ions in a Coulomb crystal of laser-cooled Ca$^{+}$, We non-destructively confirm the presence of the both B$^+$ isotopes by resonant excitation of the secular motion. The B$^{+}$ ions are loaded by ablation of boron and the secular excitation spectrum also reveals features consistent with ions of the form B$_{n}^{+}$.

  17. Compaction of amorphous iron–boron powder

    DEFF Research Database (Denmark)

    Hendriksen, Peter Vang; Mørup, Steen; Koch, Christian;

    1993-01-01

    report on attempts to compact amorphous iron–boron particles prepared by chemical reduction of Fe(II) ions in aqueous solution by NaBH4 (Ref. 2). The particles prepared in this way are pyrophoric, but can be passivated. The small particle size (10–100 nm), characteristic of this preparation technique...

  18. NEW ADVANCES IN BORON SOIL CHEMISTRY - Paper

    Science.gov (United States)

    Boron is an essential plant micronutrient for which the range between deficiency and toxicity is narrower than for any other nutrient element. Plants respond directly to the amount of B in soil solution and only indirectly to the amount of B adsorbed on soil particle surfaces. ...

  19. Boron carbide morphology changing under purification

    Science.gov (United States)

    Rahmatullin, I. A.; Sivkov, A. A.

    2015-10-01

    Boron carbide synthesized by using coaxial magnetoplasma accelerator with graphite electrodes was purified by two different ways. XRD-investigations showed content changing and respectively powder purification. Moreover TEM-investigations demonstrated morphology changing of product under purification that was discussed in the work.

  20. Pechmann Reaction Promoted by Boron Trifluoride Dihydrate

    Directory of Open Access Journals (Sweden)

    J. Mezger

    2005-08-01

    Full Text Available The Pechmann reaction of substituted phenols 1a-e with methyl acetoacetate (2 can be activated by boron trifluoride dihydrate (3 to give the corresponding 4-methyl- coumarin derivatives 4a-e in excellent yield (98-99 %.

  1. Investigating the Boron Requirement of Plants.

    Science.gov (United States)

    Bohnsack, Charles W.

    1991-01-01

    This article describes a simple and rapid method for using summer squash to investigate born deficiency in plants. Author asserts that students are likely to feel challenged by laboratory exercises and projects that focus on the role boron plays in plant growth because it is an unresolved problem in biology. (PR)

  2. Powdered Hexagonal Boron Nitride Reducing Nanoscale Wear

    Science.gov (United States)

    Chkhartishvili, L.; Matcharashvili, T.; Esiava, R.; Tsagareishvili, O.; Gabunia, D.; Margiev, B.; Gachechiladze, A.

    2013-05-01

    A morphology model is suggested for nano-powdered hexagonal boron nitride that can serve as an effective solid additive to liquid lubricants. It allows to estimate the specific surface, that is a hard-to-measure parameter, based on average size of powder particles. The model can be used also to control nanoscale wear processes.

  3. Boron nanoparticles inhibit turnour growth by boron neutron capture therapy in the murine B16-OVA model

    DEFF Research Database (Denmark)

    Petersen, Mikkel Steen; Petersen, Charlotte Christie; Agger, Ralf;

    2008-01-01

    Background: Boron neutron capture therapy usually relies on soluble, rather than particulate, boron compounds. This study evaluated the use of a novel boron nanoparticle for boron neutron capture therapy. Materials and Methods: Two hundred and fifty thousand B16-OVA tumour cells, pre......-incubated with boron nanoparticles for 12 hours, were injected subcutaneously into C57BL16J mice. The tumour sites were exposed to different doses of neutron radiation one, four, or eight days after tumour cell inoculation. Results: When the tumour site was irradiated with thermal neutrons one day after injection......, tumour growth was delayed and the treated mice survived longer than untreated controls (median survival time 20 days (N=8) compared with 10 days (N=7) for untreated mice). Conclusion: Boron nanoparticles significantly delay the growth of an aggressive B16-OVA tumour in vivo by boron neutron capture...

  4. Preparation and properties of unidirectional boron nitride fibre reinforced boron nitride matrix composites via precursor infiltration and pyrolysis route

    Energy Technology Data Exchange (ETDEWEB)

    Li Duan, E-mail: whataboutduan@gmail.com [State Key Laboratory of Advanced Ceramic Fibres and Composites, College of Aerospace and Materials Engineering, National University of Defense Technology, Changsha 410073 (China); Zhang Changrui; Li Bin; Cao Feng; Wang Siqing; Li Junsheng [State Key Laboratory of Advanced Ceramic Fibres and Composites, College of Aerospace and Materials Engineering, National University of Defense Technology, Changsha 410073 (China)

    2011-10-25

    Highlights: {yields} BN fibres degrade little when exposed at elevated temperatures. {yields} Precursor infiltration and pyrolysis route is useful to prepare BNf/BN composites. {yields} Few reports have related to the preparation and properties of BNf/BN composites. {yields} BNf/BN composites have desirable high-temperature mechanical properties. {yields} BNf/BN composites have excellent dielectric properties at 2-18 GHz. - Abstract: The unidirectional boron nitride fibre reinforced boron nitride matrix (BN{sub f}/BN) composites were prepared via the precursor infiltration and pyrolysis (PIP) route, and the structure, composition, mechanical and dielectric properties were studied. The composites have a high content and fine crystallinity of BN. The density is 1.60 g cm{sup -3} with a low open porosity of 4.66%. The composites display good mechanical properties with the average flexural strength, elastic modulus and fracture toughness being 53.8 MPa, 20.8 GPa and 6.88 MPa m{sup 1/2}, respectively. Lots of long fibres pull-out from the fracture surface, suggesting a good fibre/matrix interface. As temperature increases, both of the flexural strength and elastic modulus exhibit a decreasing trend, with the lowest values being 36.2 MPa and 8.6 GPa at 1000 deg. C, respectively. The desirable residual ratios of the flexural strength and elastic modulus at 1000 deg. C are 67.3% and 41.3%, respectively. The composites have excellent dielectric properties, with the average dielectric constant and loss tangent being 3.07 and 0.0044 at 2-18 GHz, respectively.

  5. BCM6: New Generation of Boron Meter

    Energy Technology Data Exchange (ETDEWEB)

    Pirat, P. [Rolls-Royce Civil Nuclear SAS (France)

    2010-07-01

    Full text of publication follows: Rolls-Royce has developed a new generation of boron meter, based on more than 30 years of experience. The Rolls-Royce BCM6 boron meter provides Nuclear Power Plant (NPP) operators with the boron concentration of the primary circuit. The meter provides continuous and safe measurements with no manual sampling and no human contact. In this paper, technical features, advantages and customer benefits of the use of the new generation of Rolls-Royce BCM6 boron meter will be detailed. Values and associated alarms are provides over different media: 4-20 mA outputs, relays, displays in the main control room and in the chemical lab, and digital links. A special alarm avoids unexpected homogeneous dilution of the primary circuit, which is a critical operational parameter. The Rolls-Royce BCM6 boron meter is fully configurable over a set of parameters allowing adaptation to customer needs. It has a differential capability, thus eliminating neutronic noise and keeping measurements accurate, even in the case of fuel clad rupture. Measurements are accurate, reliable, and have a quick response time. Equipment meets state-of-the-art qualification requests. Designed in 2008, the BCM6 boron meter is the newest equipment of Rolls-Royce boron meters product line. It has been chosen to equip the French EPR NPP and complies with the state-of-the-art of the technology. Rolls-Royce has more than 30 years of experience in Instrumentation and Controls with more than 75 NPP units operating worldwide. All of this experience return has been put in this new generation of equipment to provide the customer with the best operation. About Rolls-Royce Rolls-Royce is a global business providing integrated power systems for use on land, at sea and in the air. The Group has a balanced business portfolio with leading market positions. Rolls-Royce has a broad range of civil nuclear expertise, including work related to licensing and safety reviews, engineering design

  6. Silicon-[18F]Fluorine Radiochemistry: Basics, Applications and Challenges

    Directory of Open Access Journals (Sweden)

    Carmen Wängler

    2012-03-01

    Full Text Available Silicon-[18F]fluorine (Si-18F radiochemistry has recently emerged alongside other unconventional approaches such as aluminum-18F and boron-18F based labeling strategies, reshaping the landscape of modern 18F-radiochemistry. All these novel methodologies are driven by the demand for more convenient 18F-labeling procedures to further disseminate one of the most sophisticated imaging technologies, Positron Emission Tomography (PET. The PET methodology requires special radionuclides such as 18F (one of the most prominent examples to be introduced into bioactive molecules. Si-18F radiochemistry contributed greatly towards the development of new radiopharmaceuticals for PET imaging. Herein, we describe the radiochemical basics of Si-18F bond formation, the application of Si-18F tracers for PET imaging, and additionally, the inherent chemical intricacies of this methodology.

  7. The Promotion of Liquid Phase Sintering of Boron-Containing Powder Metallurgy Steels by Adding Nickel

    Directory of Open Access Journals (Sweden)

    Wu Ming-Wei

    2015-01-01

    Full Text Available Boron is a feasible alloying element for liquid phase sintering (LPS of powder metallurgy (PM steels. This study investigated the effect of nickel (Ni, which is widely used in PM steels, on the liquid phase sintering of boron-containing PM steels. The results showed that the addition of 1.8wt% Ni does not apparently modify the LPS mechanism of boron-containing PM steels. However, adding 1.8wt% Ni slightly improves the LPS densification from 0.60 g/cm3 to 0.65 g/cm3, though the green density is reduced. Thermodynamic simulation demonstrated that the presence of Ni lowers the temperature region of liquid formation, resulting in enhanced LPS densification. Moreover, original graphite powders remains in the steels sintered at 1200 ºC. These graphite powders mostly dissolve into the base iron powder when the sintering temperature is increased from 1200 ºC to 1250 ºC.

  8. Synthesis and characterization of ammonium phosphate fertilizers with boron

    Directory of Open Access Journals (Sweden)

    ANGELA MAGDA

    2010-07-01

    Full Text Available The concentration of boron, an essential micronutrient for plants, presents a narrow range between deficiency and toxicity. In order to provide the boron requirement for plants, and to avoid toxicity problems, boron compounds are mixed with basic fertilizers. Sodium borate pentahydrate was used as a boron source. Ammonium orthophosphates fertilizers with boron were prepared by neutralizing phosphoric acid with ammonia and addition of variable amounts of sodium tetraborate pentahydrate to the reaction mixture at a NH3:H3PO4 molar ratio of 1.5. The fertilizers obtained with boron contents ranging from 0.05 to 1 % (w/w were fully characterized by chemical analysis, thermal analysis, X-ray diffraction and infrared spectrophotometry. The studies showed that up to 500 °C, regardless of the boron content, no significant changes concerning thermal stability and nutritional properties occurred. Above 500 °C, an increase of thermal stability with an increase of the boron content was observed. X-Ray diffraction of a heat-treated sample containing 5 % (w/w boron indicated the appearance of boron orthophosphate, BPO4, as a new crystalline phase, and the disappearance of the previous structures above 500 °C, which explains the increase in thermal stability.

  9. Higher boron rejection with a new TFC forward osmosis membrane

    KAUST Repository

    Valladares Linares, Rodrigo

    2014-07-17

    Due to the stringent limits for boron in drinking and irrigation water, water treatment facilities have to incur additional treatment to remove boron down to a safe concentration. Forward osmosis (FO) is a membrane technology that may reduce the energy required to remove boron present in seawater. In direct FO desalination hybrid systems, fresh water is recovered from seawater using a recoverable draw solution, FO membranes are expected to show high boron rejection. This study focuses on determining the boron rejection capabilities of a new generation thin-film composite (TFC) FO membrane compared to a first generation cellulose triacetate (CTA) FO membrane. The effects of water permeate flux, membrane structure, draw solute charge, and reverse solute flux on boron rejection were determined. For TFC and CTA FO membranes, experiments showed that when similar operating conditions are applied (e.g. membrane type and draw solute type) boron rejection decreases with increase in permeate flux. Reverse draw solute flux and membrane fouling have no significant impact on boron rejection. Compared to the first generation CTA FO membrane operated at the same conditions, the TFC FO membrane showed a 40% higher boron rejection capability and a 20% higher water flux. This demonstrates the potential for boron removal for new generation TFC FO membranes. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.

  10. Boron Arsenide and Boron Phosphide for High Temperature and Luminescent Devices. [semiconductor devices - crystal growth/crystal structure

    Science.gov (United States)

    Chu, T. L.

    1975-01-01

    The crystal growth of boron arsenide and boron phosphide in the form of bulk crystals and epitaxial layers on suitable substrates is discussed. The physical, chemical, and electrical properties of the crystals and epitaxial layers are examined. Bulk crystals of boron arsenide were prepared by the chemical transport technique, and their carrier concentration and Hall mobility were measured. The growth of boron arsenide crystals from high temperature solutions was attempted without success. Bulk crystals of boron phosphide were also prepared by chemical transport and solution growth techniques. Techniques required for the fabrication of boron phosphide devices such as junction shaping, diffusion, and contact formation were investigated. Alloying techniques were developed for the formation of low-resistance ohmic contacts to boron phosphide. Four types of boron phosphide devices were fabricated: (1) metal-insulator-boron phosphide structures, (2) Schottky barriers; (3) boron phosphide-silicon carbide heterojunctions; and (4) p-n homojunctions. Easily visible red electroluminescence was observed from both epitaxial and solution grown p-n junctions.

  11. Van Hove singularities of some icosahedral boron-rich solids by differential reflectivity spectra

    Science.gov (United States)

    Werheit, Helmut

    2015-09-01

    Differential reflectivity spectra of some icosahedral boron rich solids, β-rhombohedral boron, boron carbide and YB66-type crystals, were measured. The derivatives yield the van Hove singularities, which are compared with results obtained by other experimental methods.

  12. Synthesis of borophenes: Anisotropic, two-dimensional boron polymorphs

    Science.gov (United States)

    Mannix, Andrew J.; Zhou, Xiang-Feng; Kiraly, Brian; Wood, Joshua D.; Alducin, Diego; Myers, Benjamin D.; Liu, Xiaolong; Fisher, Brandon L.; Santiago, Ulises; Guest, Jeffrey R.; Yacaman, Miguel Jose; Ponce, Arturo; Oganov, Artem R.; Hersam, Mark C.; Guisinger, Nathan P.

    2016-01-01

    At the atomic-cluster scale, pure boron is markedly similar to carbon, forming simple planar molecules and cage-like fullerenes.Theoretical studies predict that two-dimensional (2D) boron sheets will adopt an atomic configuration similar to that of boron atomic clusters. We synthesized atomically thin, crystalline 2D boron sheets (i.e., borophene) on silver surfaces under ultrahigh-vacuum conditions. Atomic-scale characterization, supported by theoretical calculations, revealed structures reminiscent of fused boron clusters with multiple scales of anisotropic, out-of-plane buckling. Unlike bulk boron allotropes, borophene shows metallic characteristics that are consistent with predictions of a highly anisotropic, 2D metal. PMID:26680195

  13. 11B nuclear magnetic resonance in boron-doped diamond

    Directory of Open Access Journals (Sweden)

    Miwa Murakami, Tadashi Shimizu, Masataka Tansho and Yoshihiko Takano

    2008-01-01

    Full Text Available This review summarizes recent results obtained by 11B solid-state nuclear magnetic resonance (NMR on boron-doped diamond, grown by the high-pressure high-temperature (HPHT or chemical vapor deposition techniques. Simple single-pulse experiments as well as advanced two-dimensional NMR experiments were applied to the boron sites in diamond. It is shown that magic-angle spinning at magnetic fields above 10 T is suitable for observation of high-resolution 11B spectra of boron-doped diamond. For boron-doped HPHT diamonds, the existence of the excess boron that does not contribute to electrical conductivity was confirmed and its 11B NMR signal was characterized. The point-defect structures (B+H complexes and -B-B-/-B-C-B- clusters, postulated previously for the excess boron, were discarded and graphite-like structures were assigned instead.

  14. Boron Rich Solids Sensors, Ultra High Temperature Ceramics, Thermoelectrics, Armor

    CERN Document Server

    Orlovskaya, Nina

    2011-01-01

    The objective of this book is to discuss the current status of research and development of boron-rich solids as sensors, ultra-high temperature ceramics, thermoelectrics, and armor. Novel biological and chemical sensors made of stiff and light-weight boron-rich solids are very exciting and efficient for applications in medical diagnoses, environmental surveillance and the detection of pathogen and biological/chemical terrorism agents. Ultra-high temperature ceramic composites exhibit excellent oxidation and corrosion resistance for hypersonic vehicle applications. Boron-rich solids are also promising candidates for high-temperature thermoelectric conversion. Armor is another very important application of boron-rich solids, since most of them exhibit very high hardness, which makes them perfect candidates with high resistance to ballistic impact. The following topical areas are presented: •boron-rich solids: science and technology; •synthesis and sintering strategies of boron rich solids; •microcantileve...

  15. Potential of using boric acid as a boron drug for boron neutron capture therapy for osteosarcoma

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, C.F.; Lin, S.Y. [Institute of Nuclear Engineering and Science, National Tsing Hua University, Taiwan (China); Peir, J.J. [Nuclear Science and Technology Development Center, National Tsing Hua University, Taiwan (China); Liao, J.W. [Graduate Institute of Veterinary Pathobiology, National Chung Hsing University, Taiwan (China); Lin, Y.C. [Department of Veterinary Medicine, National Chung Hsing University, Taiwan (China); Chou, F.I., E-mail: fichou@mx.nthu.edu.tw [Institute of Nuclear Engineering and Science, National Tsing Hua University, Taiwan (China)] [Nuclear Science and Technology Development Center, National Tsing Hua University, Taiwan (China)

    2011-12-15

    Osteosarcoma is a malignant tumor commonly found in human and animals. The ability of boric acid (BA) to accumulate in osteosarcoma due to the mechanism of the bone formation of cancer cells would make boron neutron capture therapy (BNCT) an alternative therapy for osteosarcoma. This study evaluated the feasibility of using BA as the boron drug for BNCT of bone cancer. The cytotoxicity of BA to L929 cells exceeded that of UMR-106 cells. With 25 {mu}g {sup 10}B/mL medium of BA treatment, the boron concentration in UMR-106 cells was higher than that in L929 cells. The biodistribution and pharmacokinetics of BA in Sprague-Dawley (SD) rats were studied by administrating 25 mg {sup 10}B/kg body weight to SD rats. Blood boron level decreased rapidly within one hour after BA injection. Boron concentration in the long bone was 4-6 time higher than that of blood. Results of this study suggest that BA may be a potential drug for BNCT for osteosarcoma.

  16. Application of Cycloaddition Reactions to the Syntheses of Novel Boron Compounds

    OpenAIRE

    Maguire, John A.; Hosmane, Narayan S; Yinghuai Zhu; Xiao Siwei

    2010-01-01

    This review covers the application of cycloaddition reactions in forming the boron-containing compounds such as symmetric star-shaped boron-enriched dendritic molecules, nano-structured boron materials and aromatic boronic esters. The resulting boron compounds are potentially important reagents for both materials science and medical applications such as in boron neutron capture therapy (BNCT) in cancer treatment and as drug delivery agents and synthetic intermediates for carbon-carbon cross-c...

  17. Synthesis of an orthorhombic high pressure boron phase

    Science.gov (United States)

    Zarechnaya, Evgeniya Yu; Dubrovinsky, Leonid; Dubrovinskaia, Natalia; Miyajima, Nobuyoshi; Filinchuk, Yaroslav; Chernyshov, Dmitry; Dmitriev, Vladimir

    2008-12-01

    The densest boron phase (2.52 g cm-3) was produced as a result of the synthesis under pressures above 9 GPa and temperatures up to ~1800 °C. The x-ray powder diffraction pattern and the Raman spectra of the new material do not correspond to those of any known boron phases. A new high-pressure high-temperature boron phase was defined to have an orthorhombic symmetry (Pnnm (No. 58)) and 28 atoms per unit cell.

  18. Successive Boronizing and Austempering for GGG-40 Grade Ductile Iron

    Institute of Scientific and Technical Information of China (English)

    Murat Baydogan; Seckin Izzet Akray

    2009-01-01

    Boronizing and austempering were successively applied to a GGG-40 grade ductile iron in order to combine the advantages of both process in a single treatment. This new procedure formed a 30 μm thick boride layer on the surface with subsurface matrix structure consisted of acicular ferrite and retained austenite. Reciprocating wear tests showed that successive boronizing and austempering exhibited considerably higher wear resistance than conventional boronizing having a subsurface matrix structure consisting of ferrite and pearlite.

  19. Measurement of boron isotopes by negative thermal ionization mass spectrometry

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The isobaric interference for boron isotopic measurement by negative thermal ionization mass spectrometry (NTIMS) has been studied. The result shows that the CNO- is not only from the organic material, but also from nitrate in loading reagent in NTIMS. Monitoring the mass 43 ion intensity and 43/42 ratio of blank are also necessary for the boron isotopic measurement by NTIMS, other than is only boron content.

  20. Apparatus for the production of boron nitride nanotubes

    Science.gov (United States)

    Smith, Michael W; Jordan, Kevin

    2014-06-17

    An apparatus for the large scale production of boron nitride nanotubes comprising; a pressure chamber containing; a continuously fed boron containing target; a source of thermal energy preferably a focused laser beam; a cooled condenser; a source of pressurized nitrogen gas; and a mechanism for extracting boron nitride nanotubes that are condensed on or in the area of the cooled condenser from the pressure chamber.

  1. Isotopic effects on the phonon modes in boron carbide.

    Science.gov (United States)

    Werheit, H; Kuhlmann, U; Rotter, H W; Shalamberidze, S O

    2010-10-01

    The effect of isotopes ((10)B-(11)B; (12)C-(13)C) on the infrared- and Raman-active phonons of boron carbide has been investigated. For B isotopes, the contributions of the virtual crystal approximation, polarization vector and isotopical disorder are separated. Boron and carbon isotope effects are largely opposite to one another and indicate the share of the particular atoms in the atomic assemblies vibrating in specific phonon modes. Some infrared-active phonons behave as expected for monatomic boron crystals.

  2. Microadditions of boron and vanadium in ADI

    Directory of Open Access Journals (Sweden)

    Rzychoń T.

    2007-01-01

    Full Text Available In the second part of the study, describing the role of vanadium and boron microadditions in the process of structure formation in heavy-walled castings made from ADI, the results of own investigations were presented. Within this study two series of melts of the ductile iron were made, introducing microadditions of the above mentioned elements to both unalloyed ductile iron and the ductile iron containing high levels of nickel and copper (the composition typical of ADI. Melts were conducted with iron-nickel-magnesium master alloy. Thermal analysis of the solidification process of the cast keel blocks was conducted, the heat treatment of the alloys was carried out, and then the effect of the introduced additions of boron and vanadium on the hardenability of the investigated cast iron was examined and evaluated.

  3. Facile Synthesis of Ternary Boron Carbonitride Nanotubes

    Directory of Open Access Journals (Sweden)

    Luo Lijie

    2009-01-01

    Full Text Available Abstract In this study, a novel and facile approach for the synthesis of ternary boron carbonitride (B–C–N nanotubes was reported. Growth occurred by heating simple starting materials of boron powder, zinc oxide powder, and ethanol absolute at 1150 °C under a mixture gas flow of nitrogen and hydrogen. As substrate, commercial stainless steel foil with a typical thickness of 0.05 mm played an additional role of catalyst during the growth of nanotubes. The nanotubes were characterized by SEM, TEM, EDX, and EELS. The results indicate that the synthesized B–C–N nanotubes exhibit a bamboo-like morphology and B, C, and N elements are homogeneously distributed in the nanotubes. A catalyzed vapor–liquid–solid (VLS mechanism was proposed for the growth of the nanotubes.

  4. Boron-10 ABUNCL Models of Fuel Testing

    Energy Technology Data Exchange (ETDEWEB)

    Siciliano, Edward R.; Lintereur, Azaree T.; Kouzes, Richard T.; Ely, James H.

    2013-10-01

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Coincidence Counting With Boron-Based Alternative Neutron Detection Technology at Pacific Northwest National Laboratory (PNNL) for the development of a 3He proportional counter alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a system based upon 10B-lined proportional tubes in a configuration typical for 3He-based coincidence counter applications. This report provides results from MCNP simulations of the General Electric Reuter-Stokes Alternative Boron-Based Uranium Neutron Coincidence Collar (ABUNCL) active configuration model with fuel pins previously measured at Los Alamos National Laboratory. A comparison of the GE-ABUNCL simulations and simulations of 3He based UNCL-II active counter (the system for which the GE-ABUNCL was targeted to replace) with the same fuel pin assemblies is also provided.

  5. Boron Nitride Nanotube: Synthesis and Applications

    Science.gov (United States)

    Tiano, Amanda L.; Park, Cheol; Lee, Joseph W.; Luong, Hoa H.; Gibbons, Luke J.; Chu, Sang-Hyon; Applin, Samantha I.; Gnoffo, Peter; Lowther, Sharon; Kim, Hyun Jung; Danehy, Paul M.; Inman, Jennifer A.; Jones, Stephen B.; Kang, Jin Ho; Sauti, Godfrey; Thibeault, Sheila A.; Yamakov, Vesselin; Wise, Kristopher E.; Su, Ji; Fay, Catharine C.

    2014-01-01

    Scientists have predicted that carbon's immediate neighbors on the periodic chart, boron and nitrogen, may also form perfect nanotubes, since the advent of carbon nanotubes (CNTs) in 1991. First proposed then synthesized by researchers at UC Berkeley in the mid 1990's, the boron nitride nanotube (BNNT) has proven very difficult to make until now. Herein we provide an update on a catalyst-free method for synthesizing highly crystalline, small diameter BNNTs with a high aspect ratio using a high power laser under a high pressure and high temperature environment first discovered jointly by NASA/NIA JSA. Progress in purification methods, dispersion studies, BNNT mat and composite formation, and modeling and diagnostics will also be presented. The white BNNTs offer extraordinary properties including neutron radiation shielding, piezoelectricity, thermal oxidative stability (> 800 C in air), mechanical strength, and toughness. The characteristics of the novel BNNTs and BNNT polymer composites and their potential applications are discussed.

  6. Characterization of boron doped nanocrystalline diamonds

    Energy Technology Data Exchange (ETDEWEB)

    Peterlevitz, A C; Manne, G M; Sampaio, M A; Quispe, J C R; Pasquetto, M P; Iannini, R F; Ceragioli, H J; Baranauskas, V [Faculdade de Engenharia Eletrica e Computacao, Departamento de Semicondutores, Instrumentos e Fotonica, Universidade Estadual de Campinas, UNICAMP, Av. Albert Einstein N.400, 13083-852 Campinas SP Brasil (Brazil)], E-mail: vitor.baranauskas@gmail.com

    2008-03-15

    Nanostructured diamond doped with boron was prepared using a hot-filament assisted chemical vapour deposition system fed with an ethyl alcohol, hydrogen and argon mixture. The reduction of the diamond grains to the nanoscale was produced by secondary nucleation and defects induced by argon and boron atoms via surface reactions during chemical vapour deposition. Raman measurements show that the samples are nanodiamonds embedded in a matrix of graphite and disordered carbon grains, while morphological investigations using field electron scanning microscopy show that the size of the grains ranges from 20 to 100 nm. The lowest threshold fields achieved were in the 1.6 to 2.4 V/{mu}m range.

  7. Behavior of disordered boron carbide under stress.

    Science.gov (United States)

    Fanchini, Giovanni; McCauley, James W; Chhowalla, Manish

    2006-07-21

    Gibbs free-energy calculations based on density functional theory have been used to determine the possible source of failure of boron carbide just above the Hugoniot elastic limit (HEL). A range of B4C polytypes is found to be stable at room pressure. The energetic barrier for shock amorphization of boron carbide is by far the lowest for the B12(CCC) polytype, requiring only 6 GPa approximately = P(HEL) for collapse under hydrostatic conditions. The results clearly demonstrate that the collapse of the B12(CCC) phase leads to segregation of B12 and amorphous carbon in the form of 2-3 nm bands along the (113) lattice direction, in excellent agreement with recent transmission electron microscopy results.

  8. The Boron Isotopic Composition of Elephant Dung: Inputs to the Global Boron Budget

    Science.gov (United States)

    Williams, L. B.; Hervig, R. L.

    2011-12-01

    A survey of boron in kerogen showed isotopically light δ11B values (0 to -50%) that are distinctly different from most mineral and natural water B reservoirs. Diagenesis releases this isotopically light B into pore fluids when hydrocarbons are generated, thus enriching oilfield brines in 10B. This observation suggests that borated biomolecules (BM) are primarily tetrahedral favoring 10B, whereas 11B is preferred in trigonal coordination. Plants, with optimal concentrations up to 100ppm, contribute more B than animal remains to sediment. Elephants are one of the largest herbivores on earth, consuming 200 - 250 kg of plant material/day and producing 50 kg of manure/day. They are inefficient at digestion, thus the manure contains >50% undigested plant material. Dung samples are therefore ideal for studying the δ11B of both the food input and digested output of a significant B supply to sedimentary systems. Horse and rabbit manure were studied for comparison to evaluate B isotope variations in the food supply and potential vital effects on the output. B-content and isotopic composition of dung plant material and digested fractions were measured in the solid state by secondary ion mass spectrometry. The digests were rinsed in 1.8% mannitol, a B-complexing agent, to remove surface adsorbed-B, then air dried and Au-coated for charge compensation. Results showed that the elephant diet contains 3-13 ppm B, with an average δ11B of -20 ± 0.8% (1σ), while rabbit food had 88 ppm B with a δ11B of -50 ± 1.3 %. The digested fraction of the elephant dung contains 4-10ppm B with average δ11B values of -12 ± 1.2%. In comparison, horse manure with 11-21 ppm B has a δ11B of -10.7 ± 0.5% and rabbit manure contains 2-3 ppm B with a δ11B of -8.8 ± 1%. Boron isotope compositions of these manures are indistinguishable (within error). Clearly plant material is a major contributor of isotopically light B to sediments. The herbivores studied fractionate their total B intake in

  9. Laser Boronizing of Stainless Steel with Direct Diode Laser

    Science.gov (United States)

    Kusuhara, Takayoshi; Morimoto, Junji; Abe, Nobuyuki; Tsukamoto, Masahiro

    Boronizing is a thermo-chemical surface treatment in which boron atoms are diffused into the surface of a work piece to form borides with the base material. When applied to the metallic materials, boronizing provides wear and abrasion resistance comparable to sintered carbides. However conventional boronizing is carried out at temperatures ranging from 800°C to 1050°C and takes from one to several hours. The structure and properties of the base material is influenced considerably by the high temperature and long treatment time. In order to avoid these drawbacks of conventional boronizing, laser-assisted boronizing is investigated which activates the conventional boronizing material and the work piece with a high density laser power. In this study, effect of laser characteristics was examined on the laser boronizing of stainless steel. After laser boronizing, the microstructure of the boride layer was analyzed with an optical microscope, electron probe micro analyser(EPMA) and X-ray diffractometer (XRD). The mechanical properties of borided layer were evaluated using Vickers hardness tester and sand erosion tester. Results showed that the boride layer was composed of NiB, CrB, FeB and Fe2B, and get wear resistance.

  10. Switchable Surface Wettability by Using Boronic Ester Chemistry.

    Science.gov (United States)

    Taleb, Sabri; Noyer, Elisabeth; Godeau, Guilhem; Darmanin, Thierry; Guittard, Frédéric

    2016-01-18

    Here, we report for the first time the use of a boronic ester as an efficient tool for reversible surface post-functionalization. The boronic ester bond allows surfaces to be reversibly switched from hydrophilic to hydrophobic. Based on the well-known boronic acid/glycol affinity, this strategy offers the opportunity to play with surface hydrophobic properties by adding various boronic acids onto substrates bearing glycol groups. The post-functionalization can then be reversed to regenerate the starting glycol surface. This pathway allows for the preparation of various switchable surfaces for a large range of applications in biosensors, liquid transportation, and separation membranes.

  11. Doping Silicon Wafers with Boron by Use of Silicon Paste

    Institute of Scientific and Technical Information of China (English)

    Yu Gao; Shu Zhou; Yunfan Zhang; Chen Dong; Xiaodong Pi; Deren Yang

    2013-01-01

    In this work we introduce recently developed silicon-paste-enabled p-type doping for silicon.Boron-doped silicon nanoparticles are synthesized by a plasma approach.They are then dispersed in solvents to form silicon paste.Silicon paste is screen-printed at the surface of silicon wafers.By annealing,boron atoms in silicon paste diffuse into silicon wafers.Chemical analysis is employed to obtain the concentrations of boron in silicon nanoparticles.The successful doping of silicon wafers with boron is evidenced by secondary ion mass spectroscopy (SIMS) and sheet resistance measurements.

  12. Boron removal from molten silicon using sodium-based slags

    Institute of Scientific and Technical Information of China (English)

    Yin Changhao; Hu Bingfeng; Huang Xinming

    2011-01-01

    Slag refining,as an important option for boron removal to produce solar grade silicon (SOG-Si) from metallurgical grade silicon (MG-Si),has attracted increasing attention.In this paper,Na2CO3-SiO2 systems were chosen as the sodium-based refining slag materials for boron removal from molten silicon.Furthermore,the effect of Al2O3 addition for boron removal was studied in detail,which showed that an appropriate amount of Al2O3 can help retention of the basicity of the slags,hence improving the boron removal rate.

  13. Lateral gas phase diffusion length of boron atoms over Si/B surfaces during CVD of pure boron layers

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, V., E-mail: V.Mohammadi@tudelft.nl; Nihtianov, S. [Department of Microelectronics, Delft University of Technology, Mekelweg 4, 2628 CD, Delft (Netherlands)

    2016-02-15

    The lateral gas phase diffusion length of boron atoms, L{sub B}, along silicon and boron surfaces during chemical vapor deposition (CVD) using diborane (B{sub 2}H{sub 6}) is reported. The value of L{sub B} is critical for reliable and uniform boron layer coverage. The presented information was obtained experimentally and confirmed analytically in the boron deposition temperature range from 700 °C down to 400 °C. For this temperature range the local loading effect of the boron deposition is investigated on the micro scale. A L{sub B} = 2.2 mm was determined for boron deposition at 700 °C, while a L{sub B} of less than 1 mm was observed at temperatures lower than 500 °C.

  14. New nanoforms of carbon and boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Pokropivny, V V [Institute for Problems of Materials Science of National Academy of Sciences of Ukraine (Ukraine); Ivanovskii, A L [Institute of Solid State Chemistry, Urals Branch of the Russian Academy of Sciences, Ekaterinburg (Russian Federation)], e-mail: Ivanovskii@ihim.uran.ru

    2008-10-31

    Data on new carbon nanostructures including those based on fullerenes, nanotubes as well monolithic diamond-like nanoparticles, nanofibres, various nanocomposites, etc., published in the last decade are generalised. The experimental and theoretical data on their atomic and electronic structures, the nature of chemical bonds and physicochemical properties are discussed. These data are compared with the results obtained in studies of nanoforms of boron nitride, an isoelectronic analogue of carbon. Potential fields of applications of the new nanostructures are considered.

  15. New nanoforms of carbon and boron nitride

    Science.gov (United States)

    Pokropivny, V. V.; Ivanovskii, A. L.

    2008-10-01

    Data on new carbon nanostructures including those based on fullerenes, nanotubes as well monolithic diamond-like nanoparticles, nanofibres, various nanocomposites, etc., published in the last decade are generalised. The experimental and theoretical data on their atomic and electronic structures, the nature of chemical bonds and physicochemical properties are discussed. These data are compared with the results obtained in studies of nanoforms of boron nitride, an isoelectronic analogue of carbon. Potential fields of applications of the new nanostructures are considered.

  16. Formation and Structure of Boron Nitride Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Jiang ZHANG; Zongquan LI; Jin XU

    2005-01-01

    Boron nitride (BN) nanotubes were simply synthesized by heating well-mixed boric acid, urea and iron nitrate powders at 1000℃. A small amount of BN nanowires was also obtained in the resultants. The morphological and structural characters of the BN nanostructures were studied using transmission electron microscopy. Other novel BN nanostructures, such as Y-junction nanotubes and bamboo-like nanotubes, were simultaneously observed. The growth mechanism of the BN nanotubes was discussed briefly.

  17. Amorphous Carbon-Boron Nitride Nanotube Hybrids

    Science.gov (United States)

    Kim, Jae Woo (Inventor); Siochi, Emilie J. (Inventor); Wise, Kristopher E. (Inventor); Lin, Yi (Inventor); Connell, John (Inventor)

    2016-01-01

    A method for joining or repairing boron nitride nanotubes (BNNTs). In joining BNNTs, the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures. In repairing BNNTs, the damaged site of the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures at the damage site.

  18. Electron-Spin Resonance in Boron Carbide

    Science.gov (United States)

    Wood, Charles; Venturini, Eugene L.; Azevedo, Larry J.; Emin, David

    1987-01-01

    Samples exhibit Curie-law behavior in temperature range of 2 to 100 K. Technical paper presents studies of electron-spin resonance of samples of hot pressed B9 C, B15 C2, B13 C2, and B4 C. Boron carbide ceramics are refractory solids with high melting temperatures, low thermal conductives, and extreme hardnesses. They show promise as semiconductors at high temperatures and have unusually large figures of merit for use in thermoelectric generators.

  19. Critical Range of Soil Boron for Prognosis of Boron Deficiency in Oilseed Rape

    Institute of Scientific and Technical Information of China (English)

    WEIYOUZHANG

    2001-01-01

    Relationships between seed yields of oilseed rape(Brassica napus L.) and extractable boron concen-trations in three soil layers(A,P and W) were investigated through ten experiments on three types of soils(Alluvic Entisols,Udic Ferrisols and Sagnic Anthrosols) in northern,Western and middle Zhejing Province.Among several mathematical models used to described the relationships,the polynomial equation,y=a+bx+cx2+dx3,where y is the yield of oilseed rape seed and x the extractable boron concentration in P layer of soil,was the best one.The critical range of the concentrations corresponding to 90% of the maximum oilseed rape yield was 0.40-0.52 mg kg-1,The extractable boron concentration of the P layers of the soils was the most stable,The critical range determined was verified through the production practices of oilseed rape in Zhejiang and Anhui provinces.

  20. Critical Range of Soil Boron for Prognosis of Boron Deficiency in Oilseed Rape

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Relationships between seed yields of oilseed rape (Brassica napus L.) and extractable boron concen- trations in three soil layers (A, P and W) were investigated through ten experiments on three types of soils (Alluvic Entisols, Udic Ferrisols and Stagnic Anthrosols) in northern, western and middle Zhejiang Province. Among several mathematical models used to described the relationships, the polynomial equation, y = a + bx + cx2 + dx3, where y is the yield of oilseed rape seed and x the extractable boron concentration in P layer of soil, was the best one. The critical range of the concentrations corresponding to 90% of the maximum oilseed rape yield was 0.40~0.52 mg kg-1. The extractable boron concentration of the P layers of the soils was the most stable. The critical range determined was verified through the production practices of oilseed rape in Zhejiang and Anhui provinces.

  1. Boron impregnation treatment of Eucalyptus grandis wood.

    Science.gov (United States)

    Dhamodaran, T K; Gnanaharan, R

    2007-08-01

    Eucalyptus grandis is suitable for small timber purposes, but its wood is reported to be non-durable and difficult to treat. Boron compounds being diffusible, and the vacuum-pressure impregnation (VPI) method being more suitable for industrial-scale treatment, the possibility of boron impregnation of partially dry to green timber was investigated using a 6% boric acid equivalent (BAE) solution of boric acid and borax in the ratio 1:1.5 under different treatment schedules. It was found that E. grandis wood, even in green condition, could be pressure treated to desired chemical dry salt retention (DSR) and penetration levels using 6% BAE solution. Up to a thickness of 50mm, in order to achieve a DSR of 5 kg/m(3) boron compounds, the desired DSR level as per the Indian Standard for perishable timbers for indoor use, it was found that neither the moisture content of wood nor the treatment schedule posed any problem as far as the treatability of E. grandis wood was concerned.

  2. WA18

    CERN Multimedia

    1977-01-01

    Front view. The target plates are cut from marble (3x3 m slabs surrounded by magnetized iron) and allow the use of the calorimeter as a muon polarimeter. WA18 was CHARM, the experiment of the CERN-Hamburg-Amsterdam-Rome(INFN)-Moskow(ITEP) Collaboration

  3. Paragraf 18

    DEFF Research Database (Denmark)

    Lundgaard Andersen, Linda; Neerup, Stine; Cauchi, Pernille

    Redegørelsen tegner et aktuelt billede af bredden og variationen af samarbejdet mellem de frivillige sociale foreninger og kommuner i fem udvalgte kommuner. Den giver et billede af hvilke opgaver der varetages inden for det frivillige sociale arbejde, støttet gennem § 18 midler i serviceloven og...

  4. Boron Removal in Radioactive Liquid Waste by Forward Osmosis Membrane

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Dooseong; Choi, Hei Min; Lee, Kune Woo; Moon Jeikwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    These wastes contain about 0.3-0.8 wt% boric acid and have been concentrated through an evaporation treatment. Boric acid tends to crystallize owing to its solubility, and to plug the evaporator. The volume reduction obtained through evaporation is limited by the amount of boric acid in the waste. As an emerging technology, forward osmosis (FO) has attracted growing interest in wastewater treatment and desalination. FO is a membrane process in which water flows across a semi-permeable membrane from a feed solution of lower osmotic pressure to a draw solution of higher osmotic pressure. However, very few studies on the removal of boron by FO have been performed. The objective of this study is to evaluate the possibility of boron separation in radioactive liquid waste by FO. In this study, the performance of FO was investigated to separate boron in the simulated liquid waste under the factors such as pH, osmotic pressure, ionic strength of the solution, and membrane characteristic. The boron separation in radioactive borate liquid waste was investigated with an FO membrane. When the feed solution containing boron is treated by the FO membrane, the boron permeation depends on the type of membrane, membrane orientation, pH of the feed solution, salt and boron concentration in the feed solution, and osmotic pressure of the draw solution. The boron flux begins to decline from pH 7, and increases with an increase in the osmotic driving force. The boron flux of the CTA-ES and ALFD membrane orientation is higher than those of the CTA-NW and ALFF orientation, respectively. The boron permeation rate is constant regardless of the osmotic pressure and membrane orientation. The boron flux decreases slightly with the salt concentration, but it is not heavily influenced at a low salt concentration.

  5. MIDA boronates are hydrolysed fast and slow by two different mechanisms

    Science.gov (United States)

    Gonzalez, Jorge A.; Ogba, O. Maduka; Morehouse, Gregory F.; Rosson, Nicholas; Houk, Kendall N.; Leach, Andrew G.; Cheong, Paul H.-Y.; Burke, Martin D.; Lloyd-Jones, Guy C.

    2016-11-01

    MIDA boronates (N-methylimidodiacetic boronic acid esters) serve as an increasingly general platform for small-molecule construction based on building blocks, largely because of the dramatic and general rate differences with which they are hydrolysed under various basic conditions. Yet the mechanistic underpinnings of these rate differences have remained unclear, which has hindered efforts to address the current limitations of this chemistry. Here we show that there are two distinct mechanisms for this hydrolysis: one is base mediated and the other neutral. The former can proceed more than three orders of magnitude faster than the latter, and involves a rate-limiting attack by a hydroxide at a MIDA carbonyl carbon. The alternative ‘neutral’ hydrolysis does not require an exogenous acid or base and involves rate-limiting B-N bond cleavage by a small water cluster, (H2O)n. The two mechanisms can operate in parallel, and their relative rates are readily quantified by 18O incorporation. Whether hydrolysis is ‘fast’ or ‘slow’ is dictated by the pH, the water activity and the mass-transfer rates between phases. These findings stand to enable, in a rational way, an even more effective and widespread utilization of MIDA boronates in synthesis.

  6. Enrichment and desalting of tryptic protein digests and the protein depletion using boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Fischnaller, Martin; Köck, Rainer; Bakry, Rania, E-mail: rania.bakry@uibk.ac.at; Bonn, Günther K.

    2014-05-01

    Highlights: • Protein tryptic digests were desalted and enriched utilizing hexagonal boron nitride. • Phosphopeptides were desalted with high recovery rates. • Boron nitride exhibits high wettability allowing fast sample preparation. • Boron nitride shows protein depletion capability applied for peptide purification. - Abstract: Sample preparation still remains a great challenge in modern bioanalysis and the interest in new efficient solid phase extraction (SPE) materials still remains high. In this work, hexagonal boron nitride (h-BN) is introduced as a new SPE material for the isolation and enrichment of peptides. The h-BN is isoelectronic and structurally similar to graphite. It has remarkable properties including good thermal conductivity, excellent thermal and chemical stability and a better oxidation resistance than graphite. BN attracts increasing interest because of its wide range of applicability. In the present work, the great potential of h-BN, as a new SPE-material, on the enrichment, preconcentration and desalting of tryptic digest of model proteins is demonstrated. A special attention was dedicated to the efficient enrichment of hydrophilic phosphopeptides. Two elution protocols were developed for the enrichment of peptides compatible for subsequent MALDI-MS and ESI-MS analysis. In addition, the recoveries of 5 peptides and 3 phosphopeptides with wide range of pI values utilizing h-BN materials with different surface areas were investigated. 84–106% recovery rate could be achieved using h-BN materials. The results were compared with those obtained using graphite and silica C18 under the same elution conditions, and lower recoveries were obtained. In addition, h-BN was found to have a capability of protein depletion, which is requisite for the peptide profiling.

  7. Can epithermal boron neutron capture therapy treat primary and metastatic liver cancer?

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, S.A. [Austin Repatriation Medical Centre, Heidelberg (Australia); Carolan, M.C. [Illawarra Cancer Care Centre, Wollongong (Australia); Allen, B.J. [St George Cancer Care Centre, Kogarah (Australia)

    1996-12-31

    Full text: The poor prognosis of metastatic cancer to the liver calls for the investigation of alternative treatment modalities. This paper analyses the possible use of epithermal boron neutron capture therapy for the palliative treatment of these cancers. We examine possible treatment planning scenarios for selected tumour to liver boron ratios, and specifically for the epithermal beam at the HFR, Petten. It is required that a therapeutic ratio> 1 be achieved over the entire organ. Monte Carlo calculations were performed using the radiation transport code MCNP. The geometrical model used a `variable voxel` technique to reconstruct an anthropomorphic phantom from CT scans. Regions of interest such as the liver were modelled to a resolution of a few millimetres, whereas surrounding regions were modelled with lesser detail thereby facilitating faster computation time. Three dimensional dose distributions were calculated for a frontal beam directed at the liver, and found to be in satisfactory agreement with measurements using bare and cadmium covered gold foils, PIN and MOSFET dosimeters for fast neutron and gamma measurements respectively. Dose distributions were calculated for orthogonal epithermal neutron beams to the front and side, using the parameters of the epithermal beam at Petten, and assumed tumour and normal tissue boron-10 concentrations of 30 ppm and 7.5 ppm boron-10 respectively. The therapeutic ratio (i e the dose to the tumour relative to the maximum dose to normal tissue) was found to be about 1.8, reducing to unity for the limiting condition of a tumour in the posterior liver. This result opens up the possibility of palliative therapy for the management of primary and metastatic liver cancer.

  8. Contamination of urban garden soils with copper and boron

    Energy Technology Data Exchange (ETDEWEB)

    Purves, D.

    1966-06-04

    Spectrochemical analyses of garden soils sampled in the Edinburgh and Dundee areas indicate that there is substantial contamination of urban soils with copper and boron. These soils were analyzed spectrochemically with respect to total copper and water-extractable boron content with the view of comparing the levels obtained in urban areas with levels in arable soils in rural areas. The results indicate that urban garden soils contain about four times as much copper and two to three times as much water-soluble boron as rural arable soils. The existence of such a marked disparity between the levels of two potentially toxic elements in urban and rural areas is evidence of slow poisoning of the soil environment in built-up areas and is cause for concern. While the major source of contamination of soils with copper and boron is still a matter for speculation, it is probable that the addition of soot to garden soils and the fall-out of sooty material in built-up areas where atmospheric pollution is a problem make a substantial contribution to the water-extractable boron content of urban soils. Three samples of soot from domestic chimneys, obtained from independent sources, were found on analysis to contain 640, 650 and 555 p.p.m. water-extractable boron, and it is evident that the addition to soil of even small amounts of soot with a boron content of this order would have a marked effect on its water-extractable boron content.

  9. Low-dimensional boron structures based on icosahedron B12

    Science.gov (United States)

    Kah, C. B.; Yu, M.; Tandy, P.; Jayanthi, C. S.; Wu, S. Y.

    2015-10-01

    One-dimensional icosahedral boron chains and two-dimensional icosahedral boron sheets (icosahedral α, δ6, and δ4 sheets) that contain icosahedra B12 as their building units have been predicted in a computer simulation study using a state-of-the-art semi-empirical Hamiltonian. These novel low-dimensional icosahedral structures exhibit interesting bonding and electronic properties. Specifically, the three-center, two-electron bonding between icosahedra B12 of the boron bulk (rhombohedral boron) transforms into a two-center bonding in these new allotropes of boron sheets. In contrast to the previously reported stable buckled α and triangular boron monolayer sheets, these new allotropes of boron sheets form a planar network. Calculations of electronic density of states (DOS) reveal a semiconducting nature for both the icosahedral chain and the icosahedral δ6 and δ4 sheets, as well as a nearly gapless (or metallic-like) feature in the DOS for the icosahedral α sheet. The results for the energy barrier per atom between the icosahedral δ6 and α sheets (0.17 eV), the icosahedral δ6 and δ4 sheets (0.38 eV), and the icosahedral α and δ4 sheets (0.27 eV), as indicated in the respective parentheses, suggest that these new allotropes of boron sheets are relatively stable.

  10. Growing evidence for human health benefits of boron

    Science.gov (United States)

    Growing evidence from numerous laboratories using a variety of experimental models shows that boron is a bioactive beneficial, perhaps essential, element for humans. Reported beneficial actions of boron include arthritis alleviation or risk reduction; bone growth and maintenance; central nervous sys...

  11. Predicted phase diagram of boron-carbon-nitrogen

    Science.gov (United States)

    Zhang, Hantao; Yao, Sanxi; Widom, Michael

    2016-04-01

    Noting the structural relationships between phases of carbon and boron carbide with phases of boron nitride and boron subnitride, we investigate their mutual solubilities using a combination of first-principles total energies supplemented with statistical mechanics to address finite temperatures. Thus we predict the solid-state phase diagram of boron-carbon-nitrogen (B-C-N). Owing to the large energy costs of substitution, we find that the mutual solubilities of the ultrahard materials diamond and cubic boron nitride are negligible, and the same for the quasi-two-dimensional materials graphite and hexagonal boron nitride. In contrast, we find a continuous range of solubility connecting boron carbide to boron subnitride at elevated temperatures. An electron-precise ternary compound B13CN consisting of B12 icosahedra with NBC chains is found to be stable at all temperatures up to melting. It exhibits an order-disorder transition in the orientation of NBC chains at approximately T =500 K. We also propose that the recently discovered binary B13N2 actually has composition B12.67N2 .

  12. Phase diagrams and synthesis of cubic boron nitride

    CERN Document Server

    Turkevich, V Z

    2002-01-01

    On the basis of phase equilibria, the lowest temperatures, T sub m sub i sub n , above which at high pressures cubic boron nitride crystallization from melt solution is allowable in terms of thermodynamics have been found for a number of systems that include boron nitride.

  13. BORON NITRIDE CAPACITORS FOR ADVANCED POWER ELECTRONIC DEVICES

    Energy Technology Data Exchange (ETDEWEB)

    N. Badi; D. Starikov; C. Boney; A. Bensaoula; D. Johnstone

    2010-11-01

    This project fabricates long-life boron nitride/boron oxynitride thin film -based capacitors for advanced SiC power electronics with a broad operating temperature range using a physical vapor deposition (PVD) technique. The use of vapor deposition provides for precise control and quality material formation.

  14. The investigation of parameters affecting boron removal by electrocoagulation method

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, A. Erdem [Department of Environmental Engineering, Atatuerk University, Faculty of Engineering, Erzurum (Turkey)]. E-mail: aerdemy@atauni.edu.tr; Boncukcuoglu, Recep [Department of Environmental Engineering, Atatuerk University, Faculty of Engineering, Erzurum (Turkey); Kocakerim, M. Muhtar [Department of Chemical Engineering, 25240, Atatuerk University, Faculty of Engineering Erzurum (Turkey); Keskinler, Buelent [Department of Environmental Engineering, Gebze Institute of Technology, Gebze/Kocaeli 41400 (Turkey)

    2005-10-17

    Boron removal from wastewaters by electrocoagulation using aluminum electrode material was investigated in this paper. Several working parameters, such as pH, current density, boron concentration and type and concentration of supporting electrolyte were studied in an attempt to achieve a higher removal capacity. The experiments were carried out by keeping the pH of solution constant and optimum pH of solution was determined 8.0 for the aluminum electrode. Although energy consumption increased with decreasing boron concentration, which conductivity of these solutions were low, boron removal efficiency was higher at 100 mg/L than that of 1000 mg/L. Current density was an important parameter affecting removal efficiency. Boron removal efficiency and energy consumption increased with increasing current density from 1.2 to 6.0 mA/cm{sup 2}. The types of different supporting electrolyte were experimented in order to investigate to this parameter effect on boron removal. The highest boron removal efficiency, 97%, was found by CaCl{sub 2}. Added CaCl{sub 2} increased more the conductivity of solution according to other supporting electrolytes, but decreased energy consumption. The results showed to have a high effectiveness of the electrocoagulation method in removing boron from aqueous solutions.

  15. Method for removal of phosgene from boron trichloride

    Science.gov (United States)

    Freund, S.M.

    1983-09-20

    Selective ultraviolet photolysis using an unfiltered mercury arc lamp has been used to substantially reduce the phosgene impurity in a mixture of boron trichloride and phosgene. Infrared spectrophotometric analysis of the sample before and after irradiation shows that it is possible to highly purify commercially available boron trichloride with this method. 5 figs.

  16. Finite Element Analysis Of Boron Diffusion In Wood

    DEFF Research Database (Denmark)

    Krabbenhøft, Kristian; Hoffmeyer, Preben; Bechgaard, Carl;

    2002-01-01

    The coupled heat and mass transfer equations for air, water and heat transfer are supplemented with a conservation equation for an additional species representing the concentration of boron in wood. Boundary conditions for wood-air. wood-soil and wood-boron interfaces arc discussed and finally th...

  17. APPLICATION OF BORON MODIFIED SILICA SOL ON RETENTION AND DRAINAGE

    Institute of Scientific and Technical Information of China (English)

    JinxiaMa; YuxiuPeng; ZhongzhengLi

    2004-01-01

    In this paper it was studied that these dosage effectsof CPAM, cationic starch,boron modified silica sol(BMS), A12(SO4)3, pH value and electrolyte on theretention and drainage of different microparticulatesystems including CPAM, cationic starch and boronsilica sol. The research results indicated that CPAMhad no good retention when used with boron silicasol. The best retention efficiency was the micropar-ticulate system of CPAM + cationic starch withboron modified silica sol; Secondly was that ofcationic starch with boron modified silica sol; Theworst was that of CPAM with boron modified silicasol. The retention efficiency had no relation with theaddition order between CPAM and cationic starch. Itwas also found that the microparticulate retentionsystem of boron modified silica sol could be used inalum-rosin sizing and in acidity, neutral or alkalinepapermaking conditions. This system also could beused with close circulate water so that it could reducethe water pollution and waste.

  18. Safety Assessment of Boron Nitride as Used in Cosmetics.

    Science.gov (United States)

    Fiume, Monice M; Bergfeld, Wilma F; Belsito, Donald V; Hill, Ronald A; Klaassen, Curtis D; Liebler, Daniel C; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

    2015-01-01

    The Cosmetic Ingredient Review Expert Panel (Panel) assessed the safety of boron nitride which functions in cosmetics as a slip modifier (ie, it has a lubricating effect). Boron nitride is an inorganic compound with a crystalline form that can be hexagonal, spherical, or cubic; the hexagonal form is presumed to be used in cosmetics. The highest reported concentration of use of boron nitride is 25% in eye shadow formulations. Although boron nitride nanotubes are produced, boron nitride is not listed as a nanomaterial used in cosmetic formulations. The Panel reviewed available chemistry, animal data, and clinical data and concluded that this ingredient is safe in the present practices of use and concentration in cosmetic formulations.

  19. A computational study of carbon dioxide adsorption on solid boron.

    Science.gov (United States)

    Sun, Qiao; Wang, Meng; Li, Zhen; Du, Aijun; Searles, Debra J

    2014-07-07

    Capturing and sequestering carbon dioxide (CO2) can provide a route to partial mitigation of climate change associated with anthropogenic CO2 emissions. Here we report a comprehensive theoretical study of CO2 adsorption on two phases of boron, α-B12 and γ-B28. The theoretical results demonstrate that the electron deficient boron materials, such as α-B12 and γ-B28, can bond strongly with CO2 due to Lewis acid-base interactions because the electron density is higher on their surfaces. In order to evaluate the capacity of these boron materials for CO2 capture, we also performed calculations with various degrees of CO2 coverage. The computational results indicate CO2 capture on the boron phases is a kinetically and thermodynamically feasible process, and therefore from this perspective these boron materials are predicted to be good candidates for CO2 capture.

  20. Synthesis and photoluminescence property of boron carbide nanowires

    Institute of Scientific and Technical Information of China (English)

    Bao Li-Hong; Li Chen; Tian Yuan; Tian Ji-Fa; Hui Chao; Wang Xing-Jun; Shen Cheng-Min; Gao Hong-Jun

    2008-01-01

    Large scale, high density boron carbide nanowires have been synthesized by using an improved carbothermal reduction method with B/B2O3/C powder precursors under an argon flow at 1100~C. The boron carbide nanowires are 5-10 μm in length and 80-100 nm in diameter. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) characterizations show that the boron carbide nanowire has a B4C rhombohedral structure with good crystallization. The Raman spectrum of the as-grown boron carbide nanowires is consistent with that of a B4C structure consisting of B11C icosahedra and C-B-C chains. The room temperature photoluminescence spectrum of the boron carbide nanowires exhibits a visible range of emission centred at 638 nm.

  1. Numerical simulation of boron injection in a BWR

    Energy Technology Data Exchange (ETDEWEB)

    Tinoco, Hernan, E-mail: htb@forsmark.vattenfall.s [Forsmarks Kraftgrupp AB, SE-742 03 Osthammar (Sweden); Buchwald, Przemyslaw [Reactor Technology, Royal Institute of Technology, SE-100 44 Stockholm (Sweden); Frid, Wiktor, E-mail: wiktor@reactor.sci.kth.s [Reactor Technology, Royal Institute of Technology, SE-100 44 Stockholm (Sweden)

    2010-02-15

    The present study constitutes a first step to understand the process of boron injection, transport and mixing in a BWR. It consists of transient CFD simulations of boron injection in a model of the downcomer of Forsmark's Unit 3 containing about 6 million elements. The two cases studied are unintentional start of boron injection under normal operation and loss of offsite power with partial ATWS leaving 10% of the core power uncontrolled. The flow conditions of the second case are defined by means of an analysis with RELAP5, assuming boron injection start directly after the first ECCS injection. Recent publications show that meaningful conservative results may be obtained for boron or thermal mixing in PWRs with grids as coarse as that utilized here, provided that higher order discretization schemes are used to minimize numerical diffusion. The obtained results indicate an apparently strong influence of the scenario in the behavior of the injection process. The normal operation simulation shows that virtually all boron solution flows down to the Main Recirculation Pump inlet located directly below the boron inlet nozzle. The loss of offsite power simulation shows initially a spread of the boron solution over the entire sectional area of the lower part of the downcomer filled with colder water. This remaining effect of the ECCS injection lasts until all this water has left the downcomer. Above this region, the boron injection jet develops in a vertical streak, eventually resembling the injection of the normal operation scenario. Due to the initial spread, this boron injection will probably cause larger temporal and spatial concentration variations in the core. In both cases, these variations may cause reactivity transients and fuel damage due to local power escalation. To settle this issue, an analysis using an extended model containing the downcomer, the MRPs and the Lower Plenum will be carried out. Also, the simulation time will be extended to a scale of

  2. pH dependent salinity-boron interactions impact yield, biomass, evapotranspiration and boron uptake in broccoli (Brassica oleracea L.)

    Science.gov (United States)

    Soil pH is known to influence many important biochemical processes in plants and soils, however its role in salinity - boron interactions affecting plant growth and ion relations has not been examined. The purpose of this research was to evaluate the interactive effects of salinity, boron and soil ...

  3. Magnesium doping of boron nitride nanotubes

    Science.gov (United States)

    Legg, Robert; Jordan, Kevin

    2015-06-16

    A method to fabricate boron nitride nanotubes incorporating magnesium diboride in their structure. In a first embodiment, magnesium wire is introduced into a reaction feed bundle during a BNNT fabrication process. In a second embodiment, magnesium in powder form is mixed into a nitrogen gas flow during the BNNT fabrication process. MgB.sub.2 yarn may be used for superconducting applications and, in that capacity, has considerably less susceptibility to stress and has considerably better thermal conductivity than these conventional materials when compared to both conventional low and high temperature superconducting materials.

  4. Method for exfoliation of hexagonal boron nitride

    Science.gov (United States)

    Lin, Yi (Inventor); Connell, John W. (Inventor)

    2012-01-01

    A new method is disclosed for the exfoliation of hexagonal boron nitride into mono- and few-layered nanosheets (or nanoplatelets, nanomesh, nanoribbons). The method does not necessarily require high temperature or vacuum, but uses commercially available h-BN powders (or those derived from these materials, bulk crystals) and only requires wet chemical processing. The method is facile, cost efficient, and scalable. The resultant exfoliated h-BN is dispersible in an organic solvent or water thus amenable for solution processing for unique microelectronic or composite applications.

  5. Fe nanowire encapsulated in boron nitride nanotubes

    Science.gov (United States)

    Koi, Naruhiro; Oku, Takeo; Nishijima, Masahiko

    2005-11-01

    Boron nitride (BN) nanotubes, nanohorns, nanocoils were synthesized by annealing Fe 4N and B powders at 1000 °C for 1 h in nitrogen gas atmosphere. Especially, Fe-filled BN nanotubes were produced, and investigated by high-resolution electron microscopy, high-angle annular dark-field scanning transmission electron microscopy, electron diffraction and energy dispersive X-ray spectroscopy, which indicates that the [110] of Fe is parallel to the BN nanotube axis. Formation mechanism of Fe-filled BN nanotube was speculated based on these results.

  6. Synthesis of a boron modified phenolic resin

    Directory of Open Access Journals (Sweden)

    Aparecida M. Kawamoto

    2010-08-01

    Full Text Available Phenolic resin has long been used as matrix for composites mainly because of its flame retardant behavior and high char yield after pyrolysis, which results in a self supporting structure. The addition of ceramic powders, such as SiC and B4C, as fillers to the phenolic resin, results in better thermo-oxidative stability, but as drawbacks, it has poor homogeneity, adhesion and processing difficulties during molding of the composites. The addition of single elements, such as boron, silicon and phosphorus in the main backbone of the thermo-set resin is a new strategy to obtain special high performance resins, which results in higher mechanical properties, avoiding the drawbacks of simply adding fillers, which results in enhanced thermo-oxidative stability compared to conventional phenol-formaldehyde resins. Therefore, the product can have several applications, including the use as ablative thermal protection for thermo-structural composites. This work describes the preparation of a boron-modified phenolic resin (BPR using salicyl alcohol and boric acid. The reaction was performed in refluxing toluene for a period of four hours, which produced a very high viscosity amber resin in 90% yield.The final structure of the compound, the boric acid double, substituted at the hydroxyl group of the aromatic ring, was determined with the help of the Infrared Spectroscopy, ¹H-NMR, TGA-DSC and boron elemental analysis. The absorption band of the group B-O at 1349 cm ˉ¹ can be visualized at the FT-IR spectrum. ¹H-NMR spectra showed peaks at 4.97-5.04 ppm and 3.60-3.90 ppm assigned to belong to CH2OH groups from the alcohol. The elemental analysis was also performed for boron determination.The product has also been tested in carbon and silicon fibers composite for the use in thermal structure. The results of the tests showed composites with superior mechanical properties when compared with the conventional phenolic resin.

  7. Determination of difference of boron content in soybean and its product yuba by ICP - AES%ICP - AES 法测定大豆及其产品腐竹中硼含量

    Institute of Scientific and Technical Information of China (English)

    杨大鹏; 刘晶

    2016-01-01

    The boron content in three different kinds of bean and their products yubas were determined by inductively coupled plasma - atomic emission spectrometry (ICP - AES)to research the migration of boron during the process of yubas and the relationship of boron content between different beans and yubas. The results showed that the boron contents were detected in all of the three kinds of beans, and the content was between 18 ~ 24 mg / kg. The boron contents in yubas were different because of the beans,but the mobilitys of boron were independent of the species of bean,were all between 60% ~ 67% .%为了研究腐竹生产过程中硼元素的迁移,通过ICP - AES对三种不同原料豆和对应生产的腐竹中硼含量进行检测,探索不同原料豆与腐竹中硼含量之间的关系。结果表明,三种豆中均含有一定量的硼,范围在18~24 mg / kg之间。腐竹中硼含量随原料豆不同而不同,但其迁移率与原料种类无关,都在60%~67%之间。

  8. The Adhesion Improvement of Cubic Boron Nitride Film on High Speed Steel Substrate Implanted by Boron Element

    Institute of Scientific and Technical Information of China (English)

    CAI Zhi-hai; ZHANG Ping; TAN Jun

    2005-01-01

    Cubic boron nitride(c-BN) films were deposited on W6Mo5Cr4V2 high speed steel(HSS) substrate implanted with boron ion by RF-magnetron sputtering. The films were analyzed by the bending beam method, scratch test, XPS and AFM. The experimental results show that the implantation of boron atom can reduce the in ternal stress and improve the adhesion strength of the films. The critical load of scratch test rises to 27.45 N, compared to 1.75 N of c-BN film on the unimplanted HSS. The AFM shows that the surface of the c-BN film on the implanted HSS is low in roughness and small in grain size. Then the composition of the boron implanted layer was analyzed by the XPS. And the influence of the boron implanted layer on the internal stress and adhesion strength of c-BN films were investigated.

  9. Influence of the composition of the boroning mixture on the dimension change of pressed and boroned samples from iron powder

    Directory of Open Access Journals (Sweden)

    Ivanov S.

    2008-01-01

    Full Text Available Volume changes occur during sintering and chemical-thermal treatments of metal powder samples. The results of the investigation of the volume change of pressed and boroned samples from an iron powder, depending on the mixture composition used for the boroning process, are presented in this paper. The basic mixture, used for boroning of the investigated samples from iron powder, is modified by the addition of activators with different chemical compositions and in different concentrations, of up to 4 wt %. Mixtures with ammonium bifluoride, ammonium chloride and boron potassium fluoride were investigated. The research results and the mathematical modelling enable the choice of mixture compositions for boroning based on the volume change given in advance.

  10. Thermodynamics and Kinetics of Boron Removal from Metallurgical Grade Silicon by Addition of High Basic Potassium Carbonate to Calcium Silicate Slag

    Science.gov (United States)

    Wu, Jijun; Wang, Fanmao; Ma, Wenhui; Lei, Yun; Yang, Bin

    2016-06-01

    In this study, we investigated the thermodynamics and kinetics of boron removal from metallurgical grade silicon (MG-Si) using a calcium silicate slag containing a high basic potassium carbonate. The distribution of boron between slag and silicon was theoretically derived and the distribution coefficients ( L B) of boron with different compositions of CaO, SiO2, and K2CO3 in slag reagents were determined. The maximal value of L B reached 2.08 with a high basicity slag of 40 pctCaO-40 pctSiO2-20 pctK2CO3 (Λ = 0.73). The boron removal rates from MG-Si using CaO-SiO2 and CaO-SiO2-K2CO3 slags at 1823 K (1550 °C) were investigated in an electromagnetic induction furnace. The results showed that the boron concentration in MG-Si can be reduced from 22 to 1.8 ppmw at 1823 K (1550 °C) with 20 pct K2CO3 addition to calcium silicate slag, where the removal efficiency of boron reached 91.8 pct. The mass transfer coefficient ( β S) of boron in binary 50 pctCaO-50 pctSiO2 slag was 3.16 × 10-6 m s-1 at 1823 K (1550 °C) and was 2.43 × 10-5 m s-1 in ternary 40 pctCaO-40 pctSiO2-20 pctK2CO3 slag.

  11. Efficient Boron-Carbon-Nitrogen Nanotube Formation Via Combined Laser-Gas Flow Levitation

    Science.gov (United States)

    Whitney, R. Roy (Inventor); Jordan, Kevin (Inventor); Smith, Michael W. (Inventor)

    2015-01-01

    A process for producing boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula BxCyNz. The process utilizes a combination of laser light and nitrogen gas flow to support a boron ball target during heating of the boron ball target and production of a boron vapor plume which reacts with nitrogen or nitrogen and carbon to produce boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula BxCyNz.

  12. Efficient Boron Nitride Nanotube Formation via Combined Laser-Gas Flow Levitation

    Science.gov (United States)

    Whitney, R. Roy (Inventor); Jordan, Kevin (Inventor); Smith, Michael W. (Inventor)

    2014-01-01

    A process for producing boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula B(sub x)C(sub y)N(sub z) The process utilizes a combination of laser light and nitrogen gas flow to support a boron ball target during heating of the boron ball target and production of a boron vapor plume which reacts with nitrogen or nitrogen and carbon to produce boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula B(sub x)C(sub y)N(sub z).

  13. Application of cycloaddition reactions to the syntheses of novel boron compounds.

    Science.gov (United States)

    Zhu, Yinghuai; Siwei, Xiao; Maguire, John A; Hosmane, Narayan S

    2010-12-21

    This review covers the application of cycloaddition reactions in forming the boron-containing compounds such as symmetric star-shaped boron-enriched dendritic molecules, nano-structured boron materials and aromatic boronic esters. The resulting boron compounds are potentially important reagents for both materials science and medical applications such as in boron neutron capture therapy (BNCT) in cancer treatment and as drug delivery agents and synthetic intermediates for carbon-carbon cross-coupling reactions. In addition, the use of boron cage compounds in a number of cycloaddition reactions to synthesize unique aromatic species will be reviewed briefly.

  14. Application of Cycloaddition Reactions to the Syntheses of Novel Boron Compounds

    Directory of Open Access Journals (Sweden)

    John A. Maguire

    2010-12-01

    Full Text Available This review covers the application of cycloaddition reactions in forming the boron-containing compounds such as symmetric star-shaped boron-enriched dendritic molecules, nano-structured boron materials and aromatic boronic esters. The resulting boron compounds are potentially important reagents for both materials science and medical applications such as in boron neutron capture therapy (BNCT in cancer treatment and as drug delivery agents and synthetic intermediates for carbon-carbon cross-coupling reactions. In addition, the use of boron cage compounds in a number of cycloaddition reactions to synthesize unique aromatic species will be reviewed briefly.

  15. Crystallography, semiconductivity, thermoelectricity, and other properties of boron and its compounds, especially B6O

    Science.gov (United States)

    Slack, G. A.; Morgan, K. E.

    2015-09-01

    Electron deficient and non-deficient boron compounds are discussed as potential thermoelectric generator materials. Particular attention is paid to carbon-doped beta-boron, high-carbon boron carbide, and the alpha-boron derivative compound boron suboxide. Stoichiometric B6O shows some promise, and may have a higher ZT than the other two compounds. Carbon saturated beta-boron appears to have a higher ZT than undoped samples. Carbon saturated boron carbide at B12C3 does exist. Its thermoelectric behavior is unknown.

  16. New insight in boron chemistry: Application in two-photon absorption

    Science.gov (United States)

    Bolze, F.; Hayek, A.; Sun, X. H.; Baldeck, P. L.; Bourgogne, C.; Nicoud, J.-F.

    2011-07-01

    Two groups of one-dimensional (1D) boron containing two-photon absorbing fluorophores have been prepared and characterized. One group includes boron atoms incorporated in the conjugated or pseudo conjugated central core and the other contain a boron cluster as an acceptor group at one end of the fluorophores. Two boron containing central cores (with two boron atoms) have been explored: the cyclodiborazane and the pyrazabole moieties. The chosen boron cluster, p-carborane, contains 10 boron atoms. All the prepared fluorophores present high two-photon absorption cross-sections. Some water-soluble as well as lipophylic dyes have been prepared and used in bio-imaging.

  17. Design of a boron neutron capture enhanced fast neutron therapy assembly

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhonglu [Georgia Inst. of Technology, Atlanta, GA (United States)

    2006-12-01

    The use of boron neutron capture to boost tumor dose in fast neutron therapy has been investigated at several fast neutron therapy centers worldwide. This treatment is termed boron neutron capture enhanced fast neutron therapy (BNCEFNT). It is a combination of boron neutron capture therapy (BNCT) and fast neutron therapy (FNT). It is believed that BNCEFNT may be useful in the treatment of some radioresistant brain tumors, such as glioblastoma multiform (GBM). A boron neutron capture enhanced fast neutron therapy assembly has been designed for the Fermilab Neutron Therapy Facility (NTF). This assembly uses a tungsten filter and collimator near the patient's head, with a graphite reflector surrounding the head to significantly increase the dose due to boron neutron capture reactions. The assembly was designed using Monte Carlo radiation transport code MCNP version 5 for a standard 20x20 cm2 treatment beam. The calculated boron dose enhancement at 5.7-cm depth in a water-filled head phantom in the assembly with a 5x5 cm2 collimation was 21.9% per 100-ppm 10B for a 5.0-cm tungsten filter and 29.8% for a 8.5-cm tungsten filter. The corresponding dose rate for the 5.0-cm and 8.5-cm thick filters were 0.221 and 0.127 Gy/min, respectively; about 48.5% and 27.9% of the dose rate of the standard 10x10 cm2 fast neutron treatment beam. To validate the design calculations, a simplified BNCEFNT assembly was built using four lead bricks to form a 5x5 cm2 collimator. Five 1.0-cm thick 20x20 cm2 tungsten plates were used to obtain different filter thicknesses and graphite bricks/blocks were used to form a reflector. Measurements of the dose enhancement of the simplified assembly in a water-filled head phantom were performed using a pair of tissue-equivalent ion chambers. One of the ion chambers is loaded with 1000-ppm natural boron (184-ppm 10B) to measure dose due to boron neutron capture. The

  18. Detection of boron removal capacities of different microorganisms in wastewater and effective removal process.

    Science.gov (United States)

    Laçin, Bengü; Ertit Taştan, Burcu; Dönmez, Gönül

    2015-01-01

    In this study boron removal capacities of different microorganisms were tested. Candida tropicalis, Rhodotorula mucilaginosa, Micrococcus luteus, Bacillus thuringiensis, Bacillus cereus, Bacillus megaterium, Bacillus pumilus, Pseudomonas aeruginosa and Aspergillus versicolor were examined for their boron bioaccumulation capacities in simulated municipal wastewater. A. versicolor and B. cereus were found as the most boron-tolerant microorganisms in the experiments. Also boron bioaccumulation yield of A. versicolor was 49.25% at 15 mg/L boron concentration. On the other hand biosorption experiments revealed that A. versicolor was more capable of boron removal in inactive form at the highest boron concentrations. In this paper maximum boron bioaccumulation yield was detected as 39.08% at 24.17 mg/L and the maximum boron biosorption yield was detected as 41.36% at 24.01 mg/L boron concentrations.

  19. β-Rhombohedral Boron: At the Crossroads of the Chemistry of Boron and the Physics of Frustration [Boron: a frustrated element

    Energy Technology Data Exchange (ETDEWEB)

    Ogitsu, Tadashi [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Schwegler, Eric [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Galli, Giulia [Univ. of California, Davis, CA (United States)

    2013-05-08

    In the periodic table boron occupies a peculiar, crossover position: on the first row, it is surrounded by metal forming elements on the left and by non-metals on the right. In addition, it is the only non-metal of the third column. Therefore it is perhaps not surprising that the crystallographic structure and topology of its stable allotrope at room temperature (β-boron) are not shared by any other element, and are extremely complex. The formidable intricacy of β- boron, with interconnecting icosahedra, partially occupied sites, and an unusually large number of atoms per unit cell (more than 300) has been known for more than 40 years. Nevertheless boron remains the only element purified in significant quantities whose ground state geometry has not been completely determined by experiments. However theoretical progress reported in the last decade has shed light on numerous properties of elemental boron, leading to a thorough characterization of its structure at ambient conditions, as well as of its electronic and thermodynamic properties. This review discusses in detail the properties of β-boron, as inferred from experiments and the ab-initio theories developed in the last decade.

  20. Planar CoB18- Cluster: a New Motif for - and Metallo-Borophenes

    Science.gov (United States)

    Chen, Teng-Teng; Jian, Tian; Lopez, Gary; Li, Wan-Lu; Chen, Xin; Li, Jun; Wang, Lai-Sheng

    2016-06-01

    Combined Photoelectron Spectroscopy (PES) and theoretical calculations have found that anion boron clusters (Bn-) are planar and quasi-planar up to B25-. Recent works show that anion pure boron clusters continued to be planar at B27-,B30-,B35- and B36-. B35- and B36- provide the first experimental evidence for the viability of the two-dimensional (2D) boron sheets (Borophene). The 2D to three-dimensional (3D) transitions are shown to happen at B40-,B39- and B28-, which possess cage-like structures. These fullerene-like boron cage clusters are named as Borospherene. Recently, borophenes or similar structures are claimed to be synthesized by several groups. Following an electronic design principle, a series of transition-metal-doped boron clusters (M©Bn-, n=8-10) are found to possess the monocyclic wheel structures. Meanwhile, CoB12- and RhB12- are revealed to adopt half-sandwich-type structures with the quasi-planar B12 moiety similar to the B12- cluster. Very lately, we show that the CoB16- cluster possesses a highly symmetric Cobalt-centered drum-like structure, with a new record of coordination number at 16. Here we report the CoB18- cluster to possess a unique planar structure, in which the Co atom is doped into the network of a planar boron cluster. PES reveals that the CoB18- cluster is a highly stable electronic system with the first adiabatic detachment energy (ADE) at 4.0 eV. Global minimum searches along with high-level quantum calculations show the global minimum for CoB18- is perfectly planar and closed shell (1A1) with C2v symmetry. The Co atom is bonded with 7 boron atoms in the closest coordination shell and the other 11 boron atoms in the outer coordination shell. The calculated vertical detachment energy (VDE) values match quite well with our experimental results. Chemical bonding analysis by the Adaptive Natural Density Partitioning (AdNDP) method shows the CoB18- cluster is π-aromatic with four 4-centered-2-electron (4c-2e) π bonds and one 19

  1. Mechanical deformations of boron nitride nanotubes in crossed junctions

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yadong; Chen, Xiaoming; Ke, Changhong, E-mail: cke@binghamton.edu [Department of Mechanical Engineering, State University of New York at Binghamton, Binghamton, New York 13902 (United States); Park, Cheol [NASA Langley Research Center, Hampton, Virginia 23681 (United States); Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Fay, Catharine C. [NASA Langley Research Center, Hampton, Virginia 23681 (United States); Stupkiewicz, Stanislaw [Institute of Fundamental Technological Research, Warsaw (Poland)

    2014-04-28

    We present a study of the mechanical deformations of boron nitride nanotubes (BNNTs) in crossed junctions. The structure and deformation of the crossed tubes in the junction are characterized by using atomic force microscopy. Our results show that the total tube heights are reduced by 20%–33% at the crossed junctions formed by double-walled BNNTs with outer diameters in the range of 2.21–4.67 nm. The measured tube height reduction is found to be in a nearly linear relationship with the summation of the outer diameters of the two tubes forming the junction. The contact force between the two tubes in the junction is estimated based on contact mechanics theories and found to be within the range of 4.2–7.6 nN. The Young's modulus of BNNTs and their binding strengths with the substrate are quantified, based on the deformation profile of the upper tube in the junction, and are found to be 1.07 ± 0.11 TPa and 0.18–0.29 nJ/m, respectively. Finally, we perform finite element simulations on the mechanical deformations of the crossed BNNT junctions. The numerical simulation results are consistent with both the experimental measurements and the analytical analysis. The results reported in this paper contribute to a better understanding of the structural and mechanical properties of BNNTs and to the pursuit of their applications.

  2. Power Burst Facility/Boron Neutron Capture Therapy Program for cancer treatment

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, A.L. (ed.); Dorn, R.V. III.

    1990-08-01

    This report discusses monthly progress in the Power Boron Facility/Boron Neutron Capture Therapy (PBF/BNCT) Program for Cancer Treatment. Highlights of the PBF/BNCT Program during August 1990 include progress within the areas of: Gross Boron Analysis in Tissue, Blood, and Urine, boron microscopic (subcellular) analytical development, noninvasive boron quantitative determination, analytical radiation transport and interaction modeling for BNCT, large animal model studies, neutron source and facility preparation, administration and common support and PBF operations.

  3. Process to produce silicon carbide fibers using a controlled concentration of boron oxide vapor

    Science.gov (United States)

    Barnard, Thomas Duncan (Inventor); Lipowitz, Jonathan (Inventor); Nguyen, Kimmai Thi (Inventor)

    2001-01-01

    A process for producing polycrystalline silicon carbide by heating an amorphous ceramic fiber that contains silicon and carbon in an environment containing boron oxide vapor. The boron oxide vapor is produced in situ by the reaction of a boron containing material such as boron carbide and an oxidizing agent such as carbon dioxide, and the amount of boron oxide vapor can be controlled by varying the amount and rate of addition of the oxidizing agent.

  4. Durability of tannin-boron-treated timber

    Directory of Open Access Journals (Sweden)

    Gianluca Tondi

    2012-11-01

    Full Text Available Tannin-boron wood preservatives were investigated for their resistance against outdoor agents. This work focused on the analysis of the causes that affect the durability of the tannin-hexamine-treated samples. In particular, dimensional stability, resistance to leaching, and resistance to biological agents were investigated. The combined effect of deterioration agents was evaluated by subjecting the treated samples to simulated and natural weathering tests. The study of the appearance and of the color components (L*, a*, and b* according to CIELAB space of the exposed samples was monitored to assess the efficacy of the tannin-boron formulations for outdoor applications. Significant resistance against the action of water (EN 84, ENV 1250-2 and insects (EN 47 has been demonstrated in specific tests. Conversely, the continuous stress due to artificial and natural weathering deteriorates the color and the visible features of the treated specimens. The combined effect of moisture modifications, solar exposition, and leaching cycles damages the structure of the tannin-based polymeric network and subsequently it negatively affects its preservation properties.

  5. Boron-10 ABUNCL Prototype Initial Testing

    Energy Technology Data Exchange (ETDEWEB)

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.

    2012-12-01

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Coincidence Counting With Boron-Based Alternative Neutron Detection Technology at Pacific Northwest National Laboratory (PNNL) for the development of a 3He proportional counter alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a system based upon 10B-lined proportional tubes in a configuration typical for 3He-based coincidence counter applications. This report provides results of initial testing of an Alternative Boron-Based Uranium Neutron Coincidence Collar (ABUNCL) design built by General Electric Reuter-Stokes. Several configurations of the ABUNCL models, which use 10B-lined proportional counters in place of 3He proportional counters for the neutron detection elements, were previously reported. The ABUNCL tested is of a different design than previously modeled. Initial experimental testing of the as-delivered passive ABUNCL was performed, and modeling will be conducted. Testing of the system reconfigured for active testing will be performed in the near future, followed by testing with nuclear fuel.

  6. Techniques for increasing boron fiber fracture strain

    Science.gov (United States)

    Dicarlo, J. A.

    1977-01-01

    Improvement in the strain-to-failure of chemical-vapor-deposition boron fibers is shown possible by contracting the tungsten boride core region and its inherent flaws. Results of three methods are presented in which etching and thermal-processing techniques were employed to achieve core flaw contraction by internal stresses available in the boron sheath. After commercially and treatment-induced surface flaws were removed from 203-micron (8-mil) fibers, the core flaw was observed to be essentially the only source of fiber fracture. Thus, fiber strain-to-failure was found to improve by an amount equal to the treatment-induced contraction on the core flaw. To date, average fracture strains and stresses greater than 1.4% and 5.5 GN/sq m (800 ksi), respectively, have been achieved. Commercial feasibility considerations suggest as the most cost-effective technique that method in which as-produced fibers are given a rapid heat treatment above 700 C. Preliminary results concerning the contraction kinetics and fracture behavior observed with this technique are presented and discussed for both high-vacuum and argon-gas heat-treatment environments.

  7. Analysis of boron carbides' electronic structure

    Science.gov (United States)

    Howard, Iris A.; Beckel, Charles L.

    1986-01-01

    The electronic properties of boron-rich icosahedral clusters were studied as a means of understanding the electronic structure of the icosahedral borides such as boron carbide. A lower bound was estimated on bipolaron formation energies in B12 and B11C icosahedra, and the associated distortions. While the magnitude of the distortion associated with bipolaron formation is similar in both cases, the calculated formation energies differ greatly, formation being much more favorable on B11C icosahedra. The stable positions of a divalent atom relative to an icosahedral borane was also investigated, with the result that a stable energy minimum was found when the atom is at the center of the borane, internal to the B12 cage. If incorporation of dopant atoms into B12 cages in icosahedral boride solids is feasible, novel materials might result. In addition, the normal modes of a B12H12 cluster, of the C2B10 cage in para-carborane, and of a B12 icosahedron of reduced (D sub 3d) symmetry, such as is found in the icosahedral borides, were calculated. The nature of these vibrational modes will be important in determining, for instance, the character of the electron-lattice coupling in the borides, and in analyzing the lattice contribution to the thermal conductivity.

  8. APPLICATION OF BORON MODIFIED SILICA SOL ON RETENTION AND DRAINAGE

    Institute of Scientific and Technical Information of China (English)

    Jinxia Ma; Yuxiu Peng; Zhongzheng Li

    2004-01-01

    In this paper it was studied that these dosage effects of CPAM, cationic starch、boron modified silica sol (BMS), Al2(SO4)3, pH value and electrolyte on the retention and drainage of different microparticulate systems including CPAM, cationic starch and boron silica sol. The research results indicated that CPAM had no good retention when used with boron silica sol. The best retention efficiency was the microparticulate system of CPAM + cationic starch with boron modified silica sol; Secondly was that of cationic starch with boron modified silica sol; The worst was that of CPAM with boron modified silica sol. The retention efficiency had no relation with the addition order between CPAM and cationic starch. It was also found that the microparticulate retention system of boron modified silica sol could be used in alum-rosin sizing and in acidity, neutral or alkaline papermaking conditions. This system also could be used with close circulate water so that it could reduce the water pollution and waste.

  9. Boron Particle Ignition in Secondary Chamber of Ducted Rocket

    Directory of Open Access Journals (Sweden)

    J. X. Hu

    2012-01-01

    Full Text Available In the secondary chamber of ducted rocket, there exists a relative speed between boron particles and air stream. Hence, the ignition laws under static conditions cannot be simply applied to represent the actual ignition process of boron particles, and it is required to study the effect of forced convective on the ignition of boron particles. Preheating of boron particles in gas generator makes it possible to utilize the velocity difference between gas and particles in secondary chamber for removal of the liquid oxide layer with the aid of Stoke's forces. An ignition model of boron particles is formulated for the oxide layer removal by considering that it results from a boundary layer stripping mechanism. The shearing action exerted by the high-speed flow causes a boundary layer to be formed in the surface of the liquid oxide layer, and the stripping away of this layer accounts for the accelerated ignition of boron particles. Compared with the King model, as the ignition model of boron particles is formulated for the oxide layer removal by considering that it results from a boundary layer stripping mechanism, the oxide layer thickness thins at all times during the particle ignition and lower the ignition time.

  10. Computational Studies of Physical Properties of Boron Carbide

    Energy Technology Data Exchange (ETDEWEB)

    Lizhi Ouyang

    2011-09-30

    The overall goal is to provide valuable insight in to the mechanisms and processes that could lead to better engineering the widely used boron carbide which could play an important role in current plight towards greener energy. Carbon distribution in boron carbide, which has been difficult to retrieve from experimental methods, is critical to our understanding of its structure-properties relation. For modeling disorders in boron carbide, we implemented a first principles method based on supercell approach within our G(P,T) package. The supercell approach was applied to boron carbide to determine its carbon distribution. Our results reveal that carbon prefers to occupy the end sites of the 3-atom chain in boron carbide and further carbon atoms will distribute mainly on the equatorial sites with a small percentage on the 3-atom chains and the apex sites. Supercell approach was also applied to study mechanical properties of boron carbide under uniaxial load. We found that uniaxial load can lead to amorphization. Other physical properties of boron carbide were calculated using the G(P,T) package.

  11. Characterization of a boron carbide-based polymer neutron sensor

    Science.gov (United States)

    Tan, Chuting; James, Robinson; Dong, Bin; Driver, M. Sky; Kelber, Jeffry A.; Downing, Greg; Cao, Lei R.

    2015-12-01

    Boron is used widely in thin-film solid-state devices for neutron detection. The film thickness and boron concentration are important parameters that relate to a device's detection efficiency and capacitance. Neutron depth profiling was used to determine the film thicknesses and boron-concentration profiles of boron carbide-based polymers grown by plasma enhanced chemical vapor deposition (PECVD) of ortho-carborane (1,2-B10C2H12), resulting in a pure boron carbide film, or of meta-carborane (1,7-B10C2H12) and pyridine (C5H5N), resulting in a pyridine composite film, or of pyrimidine (C4H4N2) resulting in a pure pyrimidine film. The pure boron carbide film had a uniform surface appearance and a constant thickness of 250 nm, whereas the thickness of the composite film was 250-350 nm, measured at three different locations. In the meta-carborane and pyridine composite film the boron concentration was found to increase with depth, which correlated with X-ray photoelectron spectroscopy (XPS)-derived atomic ratios. A proton peak from 14N (n,p)14C reaction was observed in the pure pyrimidine film, indicating an additional neutron sensitivity to nonthermal neutrons from the N atoms in the pyrimidine.

  12. Structure, nonstoichiometry, and geometrical frustration of α -tetragonal boron

    Science.gov (United States)

    Uemura, Naoki; Shirai, Koun; Eckert, Hagen; Kunstmann, Jens

    2016-03-01

    Recent discoveries of supposedly pure α -tetragonal boron require to revisit its structure. The system is also interesting with respect to a new type of geometrical frustration in elemental crystals, which was found in β -rhombohedral boron. Based on density functional theory calculations, the present study has resolved the structural and thermodynamic characteristics of pure α -tetragonal boron. Different from β -rhombohedral boron, the conditions for stable covalent bonding (a band gap and completely filled valence bands) are almost fulfilled at a composition B52 with two 4 c interstitial sites occupied. This indicates that the ground state of pure α -tetragonal boron is stoichiometric. However, the covalent condition is not perfectly fulfilled because nonbonding in-gap states exist that cannot be eliminated. The half occupation of the 4 c sites yields a macroscopic amount of residual entropy, which is as large as that of β -rhombohedral boron. Therefore α -tetragonal boron can be classified as an elemental crystal with geometrical frustration. Deviations from stoichiometry can occur only at finite temperatures. Thermodynamic considerations show that deviations δ from the stoichiometric composition (B52 +δ) are small and positive. For the reported high-pressure syntheses conditions δ is predicted to be about 0.1 to 0.2. An important difference between pure and C- or N-containing α -tetragonal boron is found in the occupation of interstitial sites: the pure form prefers to occupy the 4 c sites, whereas in C- or N-containing forms, a mixture of 2 a , 8 h , and 8 i sites are occupied. The present article provides relations of site occupation, δ values, and lattice parameters, which enable us to identify pure α -tetragonal boron and distinguish the pure form from other ones.

  13. Boron-Based Hydrogen Storage: Ternary Borides and Beyond

    Energy Technology Data Exchange (ETDEWEB)

    Vajo, John J. [HRL Laboratories, LLC, Malibu, CA (United States)

    2016-04-28

    DOE continues to seek reversible solid-state hydrogen materials with hydrogen densities of ≥11 wt% and ≥80 g/L that can deliver hydrogen and be recharged at moderate temperatures (≤100 °C) and pressures (≤100 bar) enabling incorporation into hydrogen storage systems suitable for transportation applications. Boron-based hydrogen storage materials have the potential to meet the density requirements given boron’s low atomic weight, high chemical valance, and versatile chemistry. However, the rates of hydrogen exchange in boron-based compounds are thus far much too slow for practical applications. Although contributing to the high hydrogen densities, the high valance of boron also leads to slow rates of hydrogen exchange due to extensive boron-boron atom rearrangements during hydrogen cycling. This rearrangement often leads to multiple solid phases occurring over hydrogen release and recharge cycles. These phases must nucleate and react with each other across solid-solid phase boundaries leading to energy barriers that slow the rates of hydrogen exchange. This project sought to overcome the slow rates of hydrogen exchange in boron-based hydrogen storage materials by minimizing the number of solid phases and the boron atom rearrangement over a hydrogen release and recharge cycle. Two novel approaches were explored: 1) developing matched pairs of ternary borides and mixed-metal borohydrides that could exchange hydrogen with only one hydrogenated phase (the mixed-metal borohydride) and only one dehydrogenated phase (the ternary boride); and 2) developing boranes that could release hydrogen by being lithiated using lithium hydride with no boron-boron atom rearrangement.

  14. Does excess boron affect malondialdehyde levels of potato cultivars?

    Directory of Open Access Journals (Sweden)

    Murat Kemal Avci

    2013-07-01

    Full Text Available Background: Malondialdehyde (MDA is a product of lipid peroxidation and a sign of oxidative stress in plants. Therefore, determining the responses of plants to a particular type of stress at a particular time will shed a light on clarifying the stress status of the plants. In this study, we report how MDA levels in potato cultivars changed under toxic concentrations of boron, an essential plant micronutrient. Materials and Methods: Eight different potato (Solanum tuberosum cultivars (cv. Konsul, cv. Morene, cv. Slaney, cv. Mona Lisa, cv. Jaerla, cv. Poroventa, cv. Yayla Kizi, cv. Armada were used as study material. Excess boron was applied for seven weeks in three concentrations (0.5, 2.5 and 5 mM to plants that were grown from tubers. Plants were harvested and malondialdehyde content analyses were carried out in leaf tissues. Results: MDA levels under excess boron in cv. Mona Lisa and Yayla Kizi steadily increased rose with increasing concentrations in all groups, compared to control. In cv. Morene, MDA decreased in 0.5 mM Boron and increased in 2.5 and 5 mM Boron applications. In cv. Armada, cv. Slaney, cv. Konsul and cv. Poroventa, MDA levels fluctuated in different groups of each cultivar. In cv. Jaerla, MDA decreased in all groups with increasing boron, compared to control. Conclusions: MDA levels under excess boron showed increase, fluctuation and decrease in each group of the cultivars, compared to control. Therefore, MDA levels in potato plants under excess boron might not be a clear sign to determine the level of stress. This is the first report of MDA levels in eight different potato cultivars subjected to three different excess boron concentrations.

  15. Synthesis of an orthorhombic high pressure boron phase

    Energy Technology Data Exchange (ETDEWEB)

    Yu Zarechnaya, Evgeniya; Dubrovinsky, Leonid; Miyajima, Nobuyoshi [Bayerisches Geoinstitut, Universitaet Bayreuth, 95440 Bayreuth (Germany); Dubrovinskaia, Natalia [Institute of Earth Sciences, Universitaet Heidelberg, Im Neuenheimer Feld 236, 69120 Heidelberg (Germany); Filinchuk, Yaroslav; Chernyshov, Dmitry; Dmitriev, Vladimir [Swiss Norwegian Beam lines at ESRF, 38043 Gernoble (France)], E-mail: Evgeniya.Zarechnaya@uni-bayreuth.de

    2008-12-15

    The densest boron phase (2.52 g cm{sup -3}) was produced as a result of the synthesis under pressures above 9 GPa and temperatures up to {approx}1800 deg. C. The x-ray powder diffraction pattern and the Raman spectra of the new material do not correspond to those of any known boron phases. A new high-pressure high-temperature boron phase was defined to have an orthorhombic symmetry (Pnnm (No. 58)) and 28 atoms per unit cell.

  16. Synthesis of an orthorhombic high pressure boron phase

    Directory of Open Access Journals (Sweden)

    Evgeniya Yu Zarechnaya, Leonid Dubrovinsky, Natalia Dubrovinskaia, Nobuyoshi Miyajima, Yaroslav Filinchuk, Dmitry Chernyshov and Vladimir Dmitriev

    2008-01-01

    Full Text Available The densest boron phase (2.52 g cm-3 was produced as a result of the synthesis under pressures above 9 GPa and temperatures up to ~1800 °C. The x-ray powder diffraction pattern and the Raman spectra of the new material do not correspond to those of any known boron phases. A new high-pressure high-temperature boron phase was defined to have an orthorhombic symmetry (Pnnm (No. 58 and 28 atoms per unit cell.

  17. Boron complexing with H-resorcinol and acidic hydroxyxanthene dyes

    Energy Technology Data Exchange (ETDEWEB)

    Nazarenko, V.A.; Flyantikova, G.V.; Chekirda, T.N. (AN Ukrainskoj SSR, Odessa. Fiziko-Khimicheskij Inst.)

    1984-01-01

    Complex formation of boron with H-resorcinol (hr; 2,4-dihydroxybenzene-azo -8-hydroxynaphtalene-3,6-disulfonic acid) and acidic hydroxyxanthene dyes (hxd: fluorescein, eosine, erathrosine). Mixed-ligand complexes with a ratio of r:hr:hxd=1:1:1 are formed at pH=5-6. The chemism of the complex formation of boron with H-resorcinol and fluorescein has been studied. The stability constant of the complex is 1.12x10/sup 21/, the conditional molar absorptivitis 1.80x10/sup 0/. This complex formation reaction was used for photometric determination of boron in natural water.

  18. Boron-doped nanodiamonds as possible agents for local hyperthermia

    Science.gov (United States)

    Vervald, A. M.; Burikov, S. A.; Vlasov, I. I.; Ekimov, E. A.; Shenderova, O. A.; Dolenko, T. A.

    2017-04-01

    In this work, the effective heating of surrounding water by heavily-boron-doped nanodiamonds (NDs) under laser irradiation of visible wavelength was found. Using Raman scattering spectroscopy of aqueous suspensions of boron-doped NDs, it was found that this abnormally high heating results in the weakening of hydrogen bonds much more so (2–5 times stronger) than for undoped NDs. The property of boron-doped NDs to heat a solvent under the influence of laser radiation (1–5 W cm‑2) opens broad prospects for their use to create nanoagents for medical oncology and local hyperthermia.

  19. Analyses of beyond design basis accident homogeneous boron dilution scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Kereszturi, Andras; Hegyi, Gyoergy; Maraczy, Csaba; Trosztel, Istvan; Tota, Adam [Hungarian Academy of Sciences, Centre for Energy Research, Budapest (Hungary); Karsa, Zoltan [NUBIKI Nuclear Safety Research Institute, Ltd., Budapest (Hungary)

    2015-09-15

    Homogeneous boron dilution scenarios in a VVER-440 reactor were analyzed using the coupled KIKO3D-ATHLET code. The scenarios are named ''homogeneous'' because of the very slow dilution caused by a rupture in the heat exchanger of the makeup system. Without the presented analyses, a significant contribution of the homogeneous boron dilution to the Core Damage Frequency (CDF) had to be assumed in the Probabilistic Safety Analyses (PSA). According to the combined results of the presented deterministic and probabilistic analyses, the final conclusion is that boron dilution transients don't give significant contribution to the CDF for the investigated VVER-440 NPP.

  20. Advances in boron-10 isotope separation by chemical exchange distillation

    Energy Technology Data Exchange (ETDEWEB)

    Song Shuang, E-mail: chengruoyu2@sina.co [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Mu Yujun; Li Xiaofeng; Bai Peng [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2010-01-15

    Advances in boron-10 isotope separation by chemical exchange distillation are reviewed in this article. With a brief introduction of the principle of the separation, the progress on the research of this method and the problems relating to the separation coefficient are discussed. Several new donors, including nitromethane, acetone, methyl isobutyl ketone (MIBK) and diisobutyl ketone (DIBK), which have large separation factors are introduced. The complexes of these new donors and boron trifluoride (BF{sub 3}) are more stable than those of using the donors examined before. Among these new donors nitromethane could be a promising substitute for donors in present use to develop new technology of separating boron-10.

  1. Iron-Catalyzed Boron Removal from Molten Silicon in Ammonia

    Science.gov (United States)

    Chen, Zhiyuan; Morita, Kazuki

    2016-12-01

    A high-temperature process of refining metallurgical-grade silicon to solar-grade silicon was developed. In this gas purging treatment, boron impurity in silicon reacts with ammonia and the products are removed as volatiles at high temperature. 1 mass pct metallic iron was added to molten silicon as a catalyst, improving the boron removal ratio from 14 to 80 pct at 1723 K (1450 °C). At 1823 K (1550 °C), this reaction could reduce boron concentration from more than 120 ppmw to activation energy of 329 ± 129 kJ mol-1 was calculated from experimental data.

  2. Structure, Mechanics and Synthesis of Nanoscale Carbon and Boron Nitride

    Science.gov (United States)

    Rinaldo, Steven G.

    This thesis is divided into two parts. In Part I, we examine the properties of thin sheets of carbon and boron nitride. We begin with an introduction to the theory of elastic sheets, where the stretching and bending modes are considered in detail. The coupling between stretching and bending modes is thought to play a crucial role in the thermodynamic stability of atomically-thin 2D sheets such as graphene. In Chapter 2, we begin by looking at the fabrication of suspended, atomically thin sheets of graphene. We then study their mechanical resonances which are read via an optical transduction technique. The frequency of the resonators was found to depend on their temperature, as was their quality factor. We conclude by offering some interpretations of the data in terms of the stretching and bending modes of graphene. In Chapter 3, we look briefly at the fabrication of thin sheets of carbon and boron nitride nanotubes. We examine the structure of the sheets using transmission and scanning electron microscopy (TEM and SEM, respectively). We then show a technique by which one can make sheets suspended over a trench with adjustable supports. Finally, DC measurements of the resistivity of the sheets in the temperature range 600 -- 1400 C are presented. In Chapter 4, we study the folding of few-layer graphene oxide, graphene and boron nitride into 3D aerogel monoliths. The properties of graphene oxide are first considered, after which the structure of graphene and boron nitride aerogels is examined using TEM and SEM. Some models for their structure are proposed. In Part II, we look at synthesis techniques for boron nitride (BN). In Chapter 5, we study the conversion of carbon structures of boron nitride via the application of carbothermal reduction of boron oxide followed by nitridation. We apply the conversion to a wide variety of morphologies, including aerogels, carbon fibers and nanotubes, and highly oriented pyrolytic graphite. In the latter chapters, we look at the

  3. Microstructure and Properties of Plasma Spraying Boron Carbide Coating

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Microstructure of plasma spray boron carbide coating was studied by SEM and TEM. Its physical,mechanical and electrical properties were measured. The results showed that high microhardness,modulus and Iow porosity of B4C coating were manufactured by plasma spray. It was lamellar packing and dense. The B4C coating examined here contained two principal structures and two impurity phase besides major phase. The relatively small value of Young′s modulus, comparing with that of the bulk materials, is explained by porosity. The Fe impurity phase could account for the relatively high electrical conductivity of boron carbide coating by comparing with the general boron carbide materials.

  4. Tuning field emission properties of boron nanocones with catalyst concentration

    Institute of Scientific and Technical Information of China (English)

    Li Chen; Tian Yuan; Wang Deng-Ke; Shi Xue-Zhao; Hui Chao; Shen Cheng-Min; Gao Hong-Jun

    2011-01-01

    Single crystalline boron nanocones are prepared by using a simple spin spread method in which Fe3O4 nanoparticles are pre-manipulated on Si(111) to form catalyst patterns of different densities. The density of boron nanocones can be tuned by changing the concentration of catalyst nanoparticles. High-resolution transmission electron microscopy analysis shows that the boron nanocone has a β-tetragonal structure with good crystallization. The field emission behaviour is optimal when the spacing distance is close to the nanocone length, which indicates that this simple spin spread method has great potential applications in electron emission nanodevices.

  5. INFLUENCE OF MICROALLOYING BY BORON ON HARDENABILITY OF STEEL

    Directory of Open Access Journals (Sweden)

    E. P. Baradyntseva

    2016-01-01

    Full Text Available The research conducted in laboratory of metallurgical science by which the factors exerting impact on hardenability of steel microalloyed by boron were analysed. The research was made because the implementation of this process in mass production is connected with the certain difficulties. The conducted researches have allowed to draw a conclusion that changing content of various chemical elements, such as nitrogen, boron, the titan and aluminum in steel containing boron, produced by JSC «BSW – Management Company of Holding «BMC» at the stage of preparation of chart flowsheet make it possible to predict terms of hardenability of the final product.

  6. Synthesis and characterization of boron-doped carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Ceragioli, H J; Peterlevitz, A C; Quispe, J C R; Pasquetto, M P; Sampaio, M A; Baranauskas, V [Faculdade de Engenharia Eletrica e Computacao, Departamento de Semicondutores, Instrumentos e Fotonica, Universidade Estadual de Campinas, UNICAMP, Av. Albert Einstein N.400, 13083-852 Campinas SP Brasil (Brazil); Larena, A [Department of Chemical Industrial Engineering and Environment, Universidad Politecnica de Madrid, E.T.S. Ingenieros Industriales, C/ Jose Gutierrez Abascal, Madrid (Spain)], E-mail: vitor.baranauskas@gmail.com

    2008-03-15

    Boron-doped carbon nanotubes have been prepared by chemical vapour deposition of ethyl alcohol doped with B{sub 2}O{sub 3} using a hot-filament system. Multi-wall carbon nanotubes of diameters in the range of 30-100 nm have been observed by field emission scanning electron microscopy (FESEM). Raman measurements indicated that the degree of C-C sp{sup 2} order decreased with boron doping. Lowest threshold fields achieved were 1.0 V/{mu}m and 2.1 V/{mu}m for undoped and boron-doped samples, respectively.

  7. Hugoniot equation of state and dynamic strength of boron carbide

    Energy Technology Data Exchange (ETDEWEB)

    Grady, Dennis E. [Applied Research Associates, Southwest Division, 4300 San Mateo Blvd NE, A-220, Albuquerque, New Mexico 87110-129 (United States)

    2015-04-28

    Boron carbide ceramics have been particularly problematic in attempts to develop adequate constitutive model descriptions for purposes of analysis of dynamic response in the shock and impact environment. Dynamic strength properties of boron carbide ceramic differ uniquely from comparable ceramics. Furthermore, boron carbide is suspected, but not definitely shown, to undergoing polymorphic phase transformation under shock compression. In the present paper, shock-wave compression measurements conducted over the past 40 years are assessed for the purpose of achieving improved understanding of the dynamic equation of state and strength of boron carbide. In particular, attention is focused on the often ignored Los Alamos National Laboratory (LANL) Hugoniot measurements performed on porous sintered boron carbide ceramic. The LANL data are shown to exhibit two compression anomalies on the shock Hugoniot within the range of 20–60 GPa that may relate to crystallographic structure transitions. More recent molecular dynamics simulations on the compressibility of the boron carbide crystal lattice reveal compression transitions that bear similarities to the LANL Hugoniot results. The same Hugoniot data are complemented with dynamic isentropic compression data for boron carbide extracted from Hugoniot measurements on boron carbide and copper granular mixtures. Other Hugoniot measurements, however, performed on near-full-density boron carbide ceramic differ markedly from the LANL Hugoniot data. These later data exhibit markedly less compressibility and tend not to show comparable anomalies in compressibility. Alternative Hugoniot anomalies, however, are exhibited by the near-full-density data. Experimental uncertainty, Hugoniot strength, and phase transformation physics are all possible explanations for the observed discrepancies. It is reasoned that experimental uncertainty and Hugoniot strength are not likely explanations for the observed differences. The notable

  8. Hugoniot equation of state and dynamic strength of boron carbide

    Science.gov (United States)

    Grady, Dennis E.

    2015-04-01

    Boron carbide ceramics have been particularly problematic in attempts to develop adequate constitutive model descriptions for purposes of analysis of dynamic response in the shock and impact environment. Dynamic strength properties of boron carbide ceramic differ uniquely from comparable ceramics. Furthermore, boron carbide is suspected, but not definitely shown, to undergoing polymorphic phase transformation under shock compression. In the present paper, shock-wave compression measurements conducted over the past 40 years are assessed for the purpose of achieving improved understanding of the dynamic equation of state and strength of boron carbide. In particular, attention is focused on the often ignored Los Alamos National Laboratory (LANL) Hugoniot measurements performed on porous sintered boron carbide ceramic. The LANL data are shown to exhibit two compression anomalies on the shock Hugoniot within the range of 20-60 GPa that may relate to crystallographic structure transitions. More recent molecular dynamics simulations on the compressibility of the boron carbide crystal lattice reveal compression transitions that bear similarities to the LANL Hugoniot results. The same Hugoniot data are complemented with dynamic isentropic compression data for boron carbide extracted from Hugoniot measurements on boron carbide and copper granular mixtures. Other Hugoniot measurements, however, performed on near-full-density boron carbide ceramic differ markedly from the LANL Hugoniot data. These later data exhibit markedly less compressibility and tend not to show comparable anomalies in compressibility. Alternative Hugoniot anomalies, however, are exhibited by the near-full-density data. Experimental uncertainty, Hugoniot strength, and phase transformation physics are all possible explanations for the observed discrepancies. It is reasoned that experimental uncertainty and Hugoniot strength are not likely explanations for the observed differences. The notable mechanistic

  9. Geometrical frustration in an element solid: (beta)-rhombohedral boron

    Energy Technology Data Exchange (ETDEWEB)

    Ogitsu, T; Gygi, F; Reed, J; Udagawa, M; Motome, Y; Schwegler, E; Galli, G

    2009-05-19

    Although a comprehensive understanding of the basic properties of most elemental solids has been achieved, there are still fundamental, open questions regarding simple substances, e.g. boron. Based on an Ising model that describes the intrinsic defect states in elemental boron, we show that this system is the only known element to exhibit geometrical frustration in its solid form. Interestingly, we find that the peculiar transport properties of boron that have been reported over the past forty years originate from the presence of geometrical frustration.

  10. Click Reactions and Boronic Acids: Applications, Issues, and Potential Solutions

    Directory of Open Access Journals (Sweden)

    Chaofeng Dai

    2010-08-01

    Full Text Available Boronic acids have been widely used in a wide range of organic reactions, in the preparation of sensors for carbohydrates, and as potential pharmaceutical agents. With the growing importance of click reactions, inevitably they are also applied to the synthesis of compounds containing the boronic acid moiety. However, such applications have unique problems. Chief among them is the issue of copper-mediated boronic acid degradation in copper-assisted [2,3]-cycloadditions involving an alkyne and an azido compound as the starting materials. This review summarizes recent developments, analyzes potential issues, and discusses known as well as possible solutions.

  11. Technology for boron-doped layers formation on the diamond

    Directory of Open Access Journals (Sweden)

    Zyablyuk K. N.

    2012-10-01

    Full Text Available The authors investigated natural type IIa diamond crystals and CVD diamond films. The article presents electrophysical parameters of the structures obtained in different modes of ion implantation of boron into the crystal with further annealing. Parameters of the crystals with a high nitrogen impurity density indicate that they can be used for the manufacture of microwave field-effect transistors operating at room temperature. CVD diamond films doped with boron during the growth process also have the required for MOSFET manufacture carrier mobility. However, due to the high activation energy of boron, the required channel conductivity is achieved at high operating temperatures.

  12. Defects involving interstitial boron in low-temperature irradiated silicon

    Science.gov (United States)

    Khirunenko, L. I.; Sosnin, M. G.; Duvanskii, A. V.; Abrosimov, N. V.; Riemann, H.

    2016-12-01

    Interstitial boron-related defects in silicon subjected to irradiation with 5 MeV electrons at a temperature of 80 K are investigated by Fourier-transform infrared absorption spectroscopy. This study demonstrates the radiation-enhanced annealing of interstitial boron during irradiation. We have revealed the interaction, which occurs in the course of irradiation, of diffusing interstitial boron atoms with one another and with interstitial oxygen. The local vibrational modes associated with these defects are identified, and the thermal stability of the defects is determined.

  13. Study on wear resistant cast B-containing 1Cr18Ni9Ti stainless steel

    Institute of Scientific and Technical Information of China (English)

    Kuang Jiacai; Jiang Zhiqiang; Zhang Shiyin; Ye Chang; Liu Qicheng

    2009-01-01

    The developed 1Cr18Ni9Ti austenitic stainless steel containing 1.63 wt.%B have been characterized by X-ray diffraction (XRD), electron probe microanalyzer (EPMA), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Vickers microhardness measurement. The microstructural evolution and property of high boron stainless steel after solution treatment at the temperature of 1050℃ are also investigated. The results show that the main compositions of borides are Fe, Cr and B, and with small amount of Ni, Mn and C elements. Silicon is insoluble in the borides. The hardness of borides is over 1,500 HV. It has been found that borides do not decompose during solution treatment, but part of borides dissolves into the matrix. The effect of increasing the solubility of boron element in the austenitic matrix favours the hardness enhancement by 8.54%. High boron stainless steel has excellent wear resistance in corrosive environment. Lifetime of transfer pipe made of high boron-containing stainless steel is 1.5-1.8 times longer than that of boron-free 1Cr18Ni9Ti stainless steel.

  14. A boron-boron coupling reaction between two ethyl cation analogues.

    Science.gov (United States)

    Litters, Sebastian; Kaifer, Elisabeth; Enders, Markus; Himmel, Hans-Jörg

    2013-12-01

    The design of larger architectures from smaller molecular building blocks by element-element coupling reactions is one of the key concerns of synthetic chemistry, so a number of strategies were developed for this bottom-up approach. A general scheme is the coupling of two elements with opposing polarity or that of two radicals. Here, we show that a B-B coupling reaction is possible between two boron analogues of the ethyl cation, resulting in the formation of an unprecedented dicationic tetraborane. The bonding properties in the rhomboid B₄ core of the product can be described as two B-B units connected by three-centre, two-electron bonds, sharing the short diagonal. Our discovery might lead the way to the long sought-after boron chain polymers with a structure similar to the silicon chains in β-SiB₃. Moreover, the reaction is a prime textbook example of the influence of multiple-centre bonding on reactivity.

  15. Residual stresses in boron/tungsten and boron/carbon fibers

    Science.gov (United States)

    Behrendt, D. R.

    1977-01-01

    Longitudinal residual stress distribution is determined for 102-micron diam B/W and B/C fibers. The 102-micron diam B/W fibers are deposited on a 12.7-micron diam tungsten wire resistively heated in a BCl3-H2 reactor. The 102-micron diam B/C fibers are made by deposition of boron on a pyrolytic graphite-coated carbon fiber. The longitudinal residual stress distribution is calculated from measurements of the change in length of the fiber produced by removal of the surface through electropolishing. It is found that for both types of fibers, the residual stress vary from a compressive stress at the surface to a tensile stress in the boron near the core. Closer to the core and in the core, significant differences in the residual stresses are observed for the B/W and B/C fibers.

  16. Residual stresses in boron/tungsten and boron/carbon fibers

    Science.gov (United States)

    Behrendt, D. R.

    1977-01-01

    By measuring the change in fracture stress of 203 micrometer diameter fibers of boron on tungsten (B/W) as a function of fiber diameter as reduced by chemical etching, it is shown that the flaws which limit B/W fiber strength are located at the surface and in the tungsten boride core. After etching to a diameter of 188 micrometers m virtually all fiber fractures were caused by core flaws, the average strength being 4.50 GN/sq m. If both the surface and core flaws are removed, the fracture strength, limited by flaws in the boron itself, is approximately 6.89 GN/sq m. This was measured on B/W fibers which were split longitudinally and had their cores removed by chemical etching. The longitudinal residual stress distribution was determined for 102 micrometer diameter B/W and B/C fibers.

  17. High Temperature Oxidation of Boron Nitride. Part 1; Monolithic Boron Nitride

    Science.gov (United States)

    Jacobson, Nathan; Farmer, Serene; Moore, Arthur; Sayir, Haluk

    1997-01-01

    High temperature oxidation of monolithic boron nitride (BN) is examined. Hot pressed BN and both low and high density CVD BN were studied. It is shown that oxidation rates are quite sensitive to microstructural factors such as orientation, porosity, and degree of crystallinity. In addition small amounts of water vapor lead to volatilization of the B2O3 oxide as H(x)B(y)O(z). For these reasons, very different oxidation kinetics were observed for each type of BN.

  18. Synthesis of boron nitride from boron containing poly(vinyl alcohol) as ceramic precursor

    Indian Academy of Sciences (India)

    M Das; S Ghatak

    2012-02-01

    A ceramic precursor, prepared by condensation reaction from poly(vinyl alcohol) (PVA) and boric acid (H3BO3) in 1:1, 2:1 and 4:1 molar ratios, was synthesized as low temperature synthesis route for boron nitride ceramic. Samples were pyrolyzed at 850°C in nitrogen atmosphere followed by characterization using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD).

  19. An empirical model for parameters affecting energy consumption in boron removal from boron-containing wastewaters by electrocoagulation

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, A. Erdem [Atatuerk University, Faculty of Engineering, Department of Environmental Engineering, 25240 Erzurum (Turkey)]. E-mail: aerdemy@atauni.edu.tr; Boncukcuoglu, Recep [Atatuerk University, Faculty of Engineering, Department of Environmental Engineering, 25240 Erzurum (Turkey); Kocakerim, M. Muhtar [Atatuerk University, Faculty of Engineering, Department of Chemical Engineering, 25240 Erzurum (Turkey)

    2007-06-01

    In this study, it was investigated parameters affecting energy consumption in boron removal from boron containing wastewaters prepared synthetically, via electrocoagulation method. The solution pH, initial boron concentration, dose of supporting electrolyte, current density and temperature of solution were selected as experimental parameters affecting energy consumption. The obtained experimental results showed that boron removal efficiency reached up to 99% under optimum conditions, in which solution pH was 8.0, current density 6.0mA/cm{sup 2}, initial boron concentration 100mg/L and solution temperature 293K. The current density was an important parameter affecting energy consumption too. High current density applied to electrocoagulation cell increased energy consumption. Increasing solution temperature caused to decrease energy consumption that high temperature decreased potential applied under constant current density. That increasing initial boron concentration and dose of supporting electrolyte caused to increase specific conductivity of solution decreased energy consumption. As a result, it was seen that energy consumption for boron removal via electrocoagulation method could be minimized at optimum conditions. An empirical model was predicted by statistically. Experimentally obtained values were fitted with values predicted from empirical model being as following;[ECB]=7.6x10{sup 6}x[OH]{sup 0.11}x[CD]{sup 0.62}x[IBC]{sup -0.57}x[DSE]{sup -0.}= {sup 04}x[T]{sup -2.98}x[t] Unfortunately, the conditions obtained for optimum boron removal were not the conditions obtained for minimum energy consumption. It was determined that support electrolyte must be used for increase boron removal and decrease electrical energy consumption.

  20. Determination of Boron Trifluoride in Boron Trifluoride Complex by Fluoride Ion Selective Electrode

    Institute of Scientific and Technical Information of China (English)

    郎五可; 张卫江; 唐银; 徐姣; 张雷

    2016-01-01

    A method was proposed to determine boron trifluoride in boron trifluoride complex using fluoride ion selective electrode(ISE). Hydroxide was chosen to mask aluminum for the determination of 0.01—0.1 mol/L of fluoride. The simulation indicated that the permissible aluminum masked at a certain pH value was limited and hardly related to F-concentration and boric acid. It is better to control pH value below 11.5 and the aluminum con-centration within 0.025 mol/L to minimize the interference of hydroxide to the fluoride ISE. The decomposition conditions of boron trifluoride by aluminum chloride were investigated. It is found that the F-detection ratio will approach 1.0 if the Al/F molar ratio is 0.3—0.7 and aluminum concentration is no more than 0.02 mol/L when heated at 80℃ for 10 min. In one word, hydroxide is quite fit to mask aluminum for samples which contain high content of fluoride and aluminum and the BF3 content can be successfully determined by this method.

  1. Nanostructured Boron Nitride With High Water Dispersibility For Boron Neutron Capture Therapy

    Science.gov (United States)

    Singh, Bikramjeet; Kaur, Gurpreet; Singh, Paviter; Singh, Kulwinder; Kumar, Baban; Vij, Ankush; Kumar, Manjeet; Bala, Rajni; Meena, Ramovatar; Singh, Ajay; Thakur, Anup; Kumar, Akshay

    2016-10-01

    Highly water dispersible boron based compounds are innovative and advanced materials which can be used in Boron Neutron Capture Therapy for cancer treatment (BNCT). Present study deals with the synthesis of highly water dispersible nanostructured Boron Nitride (BN). Unique and relatively low temperature synthesis route is the soul of present study. The morphological examinations (Scanning/transmission electron microscopy) of synthesized nanostructures showed that they are in transient phase from two dimensional hexagonal sheets to nanotubes. It is also supported by dual energy band gap of these materials calculated from UV- visible spectrum of the material. The theoretically calculated band gap also supports the same (calculated by virtual nano lab Software). X-ray diffraction (XRD) analysis shows that the synthesized material has deformed structure which is further supported by Raman spectroscopy. The structural aspect of high water disperse ability of BN is also studied. The ultra-high disperse ability which is a result of structural deformation make these nanostructures very useful in BNCT. Cytotoxicity studies on various cell lines (Hela(cervical cancer), human embryonic kidney (HEK-293) and human breast adenocarcinoma (MCF-7)) show that the synthesized nanostructures can be used for BNCT.

  2. Preparation and characterization of Boron carbide nanoparticles for use as a novel agent in T cell-guided boron neutron capture therapy

    DEFF Research Database (Denmark)

    Mortensen, M. W.; Sørensen, P. G.; Björkdahl, O.;

    2006-01-01

    Boron carbide nanoparticles are proposed as a system for T cell-guided boron neutron capture therapy. Nanoparticles were produced by ball milling in various atmospheres of commercially available boron carbide. The physical and chemical properties of the particles were investigated using...

  3. Phonon transport in single-layer Boron nanoribbons

    CERN Document Server

    Zhang, Zhongwei; Peng, Qing; Chen, Yuanping

    2016-01-01

    Inspired by the successful synthesis of several allotropes, boron sheets have been one of the hottest spot areas of focus in various fields. Here, we study phonon transport in three types of boron nanoribbons with zigzag and armchair edges by using a non-equilibrium Green's function combined with first principles methods. Diverse transport properties are found in the nanoribbons. At the room temperature, their highest thermal conductance can be comparable with that of graphene, while the lowest thermal conductance is less than half of graphene's. The three boron sheets exhibit different anisotropic transport characteristics. Two of these sheets have stronger phonon transport abilities along the zigzag edges than the armchair edges, while in the case of the third, the results are reversed. With the analysis of phonon dispersion, bonding charge density, and simplified models of atomic chains, the mechanisms of the diverse phonon properties are discussed. Because all boron allotropes consists of hexagonal and tr...

  4. Fractionation of Boron Isotopes in Icelandic Hydrothermal Systems

    Energy Technology Data Exchange (ETDEWEB)

    Aggarwal, J.K.; Palmer, M.R.

    1995-01-01

    Boron isotope ratios have been determined in a variety of different geothermal waters from hydrothermal systems across Iceland. Isotope ratios from the high temperature meteoric water recharged systems reflect the isotope ratio of the host rocks without any apparent fractionation. Seawater recharged geothermal systems exhibit more positive {delta}{sup 11}B values than the meteoric water recharged geothermal systems. Water/rock ratios can be assessed from boron isotope ratios in the saline hydrothermal systems. Low temperature hydrothermal systems also exhibit more positive {delta}{sup 11}B than the high temperature systems, indicating fractionation of boron due to adsorption of the lighter isotope onto secondary minerals. Fractionation of boron in carbonate deposits may indicate the level of equilibrium attained within the systems.

  5. Functionalization and cellular uptake of boron carbide nanoparticles

    DEFF Research Database (Denmark)

    Mortensen, M. W.; Björkdahl, O.; Sørensen, P. G.;

    2006-01-01

    In this paper we present surface modification strategies of boron carbide nanoparticles, which allow for bioconjugation of the transacting transcriptional activator (TAT) peptide and fluorescent dyes. Coated nanoparticles can be translocated into murine EL4 thymoma cells and B16 F10 malignant...... melanoma cells in amounts as high as 0.3 wt. % and 1 wt. %, respectively. Neutron irradiation of a test system consisting of untreated B16 cells mixed with B16 cells loaded with boron carbide nanoparticles were found to inhibit the proliferative capacity of untreated cells, showing that cells loaded...... with boron-containing nanoparticles can hinder the growth of neighboring cells upon neutron irradiation. This could provide the first step toward a T cell-guided boron neutron capture therapy....

  6. Boron isotope method for study of seawater intrusion

    Institute of Scientific and Technical Information of China (English)

    肖应凯; 尹德忠; 刘卫国; 王庆忠; 魏海珍

    2001-01-01

    A distinct difference in boron isotopes between seawater and terrestrial water is emphasized by δ11B values reported for seawater and groundwater, with an average of 38.8‰ and in the range of -8.9‰ to 9.8‰, respectively. The isotopic composition of boron in groundwater can be used to quantify seawater intrusion and identify intrusion types, e.g. seawater or brine intrusions with different chemical and isotopic characteristics, by using the relation of δ11B and chloride concentration. The feasibility of utilizing boron isotope in groundwater for studying seawater intrusion in Laizhou Bay Region, China, is reported in this study, which shows that boron isotope is a useful and excellent tool for the study of seawater intrusion.

  7. Radial furnace shows promise for growing straight boron carbide whiskers

    Science.gov (United States)

    Feingold, E.

    1967-01-01

    Radial furnace, with a long graphite vaporization tube, maintains a uniform thermal gradient, favoring the growth of straight boron carbide whiskers. This concept seems to offer potential for both the quality and yield of whiskers.

  8. Atomic structure of amorphous shear bands in boron carbide.

    Science.gov (United States)

    Reddy, K Madhav; Liu, P; Hirata, A; Fujita, T; Chen, M W

    2013-01-01

    Amorphous shear bands are the main deformation and failure mode of super-hard boron carbide subjected to shock loading and high pressures at room temperature. Nevertheless, the formation mechanisms of the amorphous shear bands remain a long-standing scientific curiosity mainly because of the lack of experimental structure information of the disordered shear bands, comprising light elements of carbon and boron only. Here we report the atomic structure of the amorphous shear bands in boron carbide characterized by state-of-the-art aberration-corrected transmission electron microscopy. Distorted icosahedra, displaced from the crystalline matrix, were observed in nano-sized amorphous bands that produce dislocation-like local shear strains. These experimental results provide direct experimental evidence that the formation of amorphous shear bands in boron carbide results from the disassembly of the icosahedra, driven by shear stresses.

  9. On surface Raman scattering and luminescence radiation in boron carbide.

    Science.gov (United States)

    Werheit, H; Filipov, V; Schwarz, U; Armbrüster, M; Leithe-Jasper, A; Tanaka, T; Shalamberidze, S O

    2010-02-01

    The discrepancy between Raman spectra of boron carbide obtained by Fourier transform Raman and conventional Raman spectrometry is systematically investigated. While at photon energies below the exciton energy (1.560 eV), Raman scattering of bulk phonons of boron carbide occurs, photon energies exceeding the fundamental absorption edge (2.09 eV) evoke additional patterns, which may essentially be attributed to luminescence or to the excitation of Raman-active processes in the surface region. The reason for this is the very high fundamental absorption in boron carbide inducing a very small penetration depth of the exciting laser radiation. Raman excitations essentially restricted to the boron carbide surface region yield spectra which considerably differ from bulk phonon ones, thus indicating structural modifications.

  10. Molecular Dynamics Modeling of Piezoelectric Boron Nirtride Nanotubes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Boron-nitride nanotubes (BNNTs) exhibit electroactive behavior in response to mechanical deformation, but the origin of this phenomenon is not well understood. Our...

  11. Recent Advances in Boron-Containing Conjugated Porous Polymers

    Directory of Open Access Journals (Sweden)

    Feng Qiu

    2016-05-01

    Full Text Available Porous polymers, integrating the advantages of porous materials and conventional polymers, have been well developed and exhibited tremendous attention in the fields of material, chemistry and biology. Of these, boron-containing conjugated porous polymers, featuring tunable geometric structures, unique Lewis acid boron centers and very rich physical properties, such as high specific surface, chargeable scaffold, strong photoluminescence and intramolecular charge transfer, have emerged as one of the most promising functional materials for optoelectronics, catalysis and sensing, etc. Furthermore, upon thermal treatment, some of them can be effectively converted to boron-doped porous carbon materials with good electrochemical performance in energy storage and conversion, extensively enlarging the applicable scope of such kinds of polymers. In this review, the synthetic approaches, structure analyses and various applications of the boron-containing conjugated porous polymers reported very recently are summarized.

  12. Isotopic compositions of boron in sediments and their implications

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; Yingkai, X.

    The abundance and isotopic compositions of boron in sediments from the salt lakes of Qaidam Basin, China have been determined by thermal ionization mass spectrometry of cesium borate. The results show large variations in the isotopic compositions...

  13. Quantum emission from hexagonal boron nitride monolayers

    Science.gov (United States)

    Tran, Toan Trong; Bray, Kerem; Ford, Michael J.; Toth, Milos; Aharonovich, Igor

    2016-01-01

    Artificial atomic systems in solids are widely considered the leading physical system for a variety of quantum technologies, including quantum communications, computing and metrology. To date, however, room-temperature quantum emitters have only been observed in wide-bandgap semiconductors such as diamond and silicon carbide, nanocrystal quantum dots, and most recently in carbon nanotubes. Single-photon emission from two-dimensional materials has been reported, but only at cryogenic temperatures. Here, we demonstrate room-temperature, polarized and ultrabright single-photon emission from a colour centre in two-dimensional hexagonal boron nitride. Density functional theory calculations indicate that vacancy-related defects are a probable source of the emission. Our results demonstrate the unprecedented potential of van der Waals crystals for large-scale nanophotonics and quantum information processing.

  14. Boronic acids for fluorescence imaging of carbohydrates.

    Science.gov (United States)

    Sun, Xiaolong; Zhai, Wenlei; Fossey, John S; James, Tony D

    2016-02-28

    "Fluorescence imaging" is a particularly exciting and rapidly developing area of research; the annual number of publications in the area has increased ten-fold over the last decade. The rapid increase of interest in fluorescence imaging will necessitate the development of an increasing number of molecular receptors and binding agents in order to meet the demand in this rapidly expanding area. Carbohydrate biomarkers are particularly important targets for fluorescence imaging given their pivotal role in numerous important biological events, including the development and progression of many diseases. Therefore, the development of new fluorescent receptors and binding agents for carbohydrates is and will be increasing in demand. This review highlights the development of fluorescence imaging agents based on boronic acids a particularly promising class of receptors given their strong and selective binding with carbohydrates in aqueous media.

  15. Boronized steels with corundum-baddeleyite coatings

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2016-07-01

    Full Text Available The paper describes preparation and properties of anti-corrosion and anti-abrasive coatings from corundum-baddeleyite ceramics deposited on surface of low-carbon boronized steel S235JRH-1.0038 (EN 10025-1 by plasma spraying method. Adhesive interlayers Fe2B reaches bond strength of up to 20 MPa in the pull-off tests, the ZrO2 - Al2O3 - SiO2 coatings have a value of fracture adhesion of 4 - 6 MPa. Hardness of these ceramic coatings on steel is as high as 1 800 HV100 and its polarization resistance is 1 600 Ω/cm2 to 4 000 Ω/cm2.

  16. Mechanical Hysteresis of Hexagonal Boron Nitride

    Institute of Scientific and Technical Information of China (English)

    ZHOU Aiguo; LI Haoran

    2011-01-01

    Hexagonal boron nitride (h-BN) is an important structural material with layered microstructure.Because of the plastic anisotropy,this material shows obvious mechanical hysteresis (nonlinear elastic deformation).There are hysteretic loops at the cyclical load-unload stress-strain curves of h-BN.Consequently,two hot-pressed h-BN cylinders with different textures were studied.The mechanical hysteresis is heavily texture-dependent.The area of hysteretic loop is linearly related with the square of loading stresslevel.Two minor loops attached on the hysteretic loops with the same extreme stresses have congruent shapes.It can be concluded that the mechanical hysteresis of h-BN can he explained by a Kink Nonlinear Elastic model developed from the study of a ternary carbide Ti3SiC2.

  17. Research in boron neutron capture synovectomy

    Science.gov (United States)

    Binello, E.; Shortkroff, S.; Jones, A.; Viveiros, C.; Ly, A.; Sledge, C. B.; Davison, A.; Shefer, Ruth E.; Yanch, Jacquelyn C.

    1997-02-01

    Boron Neutron Capture Synovectomy (BNCS) is a novel application of the 10B(n, (alpha) )7Li reaction for the treatment of Rheumatoid Arthritis. This potential treatment modality is in its developmental stages; in this paper results of research in two aspects of BNCS are presented. First, quantification of 10B-uptake in samples of human arthritic tissue by Prompt Gamma Neutron Activation Analysis is presented. 10B concentrations from 1625 to 2726 ppm are readily achieved. Second, ideal neutron beam studies have been undertaken and indicate that neutrons from thermal energies to 1 keV are useful for BNCS. This information is of use in designing practical therapy beams should this treatment modality be realized.

  18. Pure and doped boron nitride nanotubes

    Directory of Open Access Journals (Sweden)

    M. Terrones

    2007-05-01

    Full Text Available More than ten years ago, it was suggested theoretically that boron nitride (BN nanotubes could be produced. Soon after, various reports on their synthesis appeared and a new area of nanotube science was born. This review aims to cover the latest advances related to the synthesis of BN nanotubes. We show that these tubes can now be produced in larger amounts and, in particular, that the chemistry of BN tubes appears to be very important to the production of reinforced composites with insulating characteristics. From the theoretical standpoint, we also show that (BN-C heteronanotubes could have important implications for nanoelectronics. We believe that BN nanotubes (pure and doped could be used in the fabrication of novel devices in which pure carbon nanotubes do not perform very efficiently.

  19. Boron in Plants: Deficiency and Toxicity

    Institute of Scientific and Technical Information of China (English)

    Juan J. Camacho-Crist6bal; Jesus Rexach; Agustin González-Fontess

    2008-01-01

    Boron (B) is an essential nutrient for normal growth of higher plants, and B availability in soil and irrigation water is an important determinant of agricultural production. To date, a primordial function of B is undoubtedly its structural role in the cell wall; however, there is increasing evidence for a possible role of B in other processes such as the maintenance of plasma membrane function and several metabolic pathways. In recent years, the knowledge of the molecular basis of B deficiency and toxicity responses in plants has advanced greatly. The aim of this review is to provide an update on recent findings related to these topics, which can contribute to a better understanding of the role of B in plants.

  20. Helium behaviour in implanted boron carbide

    Directory of Open Access Journals (Sweden)

    Motte Vianney

    2015-01-01

    Full Text Available When boron carbide is used as a neutron absorber in nuclear power plants, large quantities of helium are produced. To simulate the gas behaviour, helium implantations were carried out in boron carbide. The samples were then annealed up to 1500 °C in order to observe the influence of temperature and duration of annealing. The determination of the helium diffusion coefficient was carried out using the 3He(d,p4He nuclear reaction (NRA method. From the evolution of the width of implanted 3He helium profiles (fluence 1 × 1015/cm2, 3 MeV corresponding to a maximum helium concentration of about 1020/cm3 as a function of annealing temperatures, an Arrhenius diagram was plotted and an apparent diffusion coefficient was deduced (Ea = 0.52 ± 0.11 eV/atom. The dynamic of helium clusters was observed by transmission electron microscopy (TEM of samples implanted with 1.5 × 1016/cm2, 2.8 to 3 MeV 4He ions, leading to an implanted slab about 1 μm wide with a maximum helium concentration of about 1021/cm3. After annealing at 900 °C and 1100 °C, small (5–20 nm flat oriented bubbles appeared in the grain, then at the grain boundaries. At 1500 °C, due to long-range diffusion, intra-granular bubbles were no longer observed; helium segregates at the grain boundaries, either as bubbles or inducing grain boundaries opening.

  1. Microalloying Boron Carbide with Silicon to Achieve Dramatically Improved Ductility

    Science.gov (United States)

    2014-11-18

    Fracture Toughness in Nanostructured Diamond−SiC Composites. Appl . Phys. Lett. 2004, 84, 1356−1358. (8) Sigl, L. S.; Mataga, P. A.; Dalgleish, B. J...Commun. 2012, 3, 1052. (11) Sezer, A. O.; Brand , J. I. Chemical Vapor Deposition of Boron Carbide. Mater. Sci. Eng., B 2001, 79, 191−202. (12) Thevenot...23) Johnson, G. R.; Holmquist, T. J. Response of Boron Carbide Subjected to Large Strains, High Strain Rates, and High Pressures. J. Appl . Phys. 1999

  2. 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

  3. Boron concentration measurement system for the Czech BNCT project

    Science.gov (United States)

    Honzátko, J.; Tomandl, I.

    2000-07-01

    In the framework of the Czech Boron Neutron Capture Therapy (BNCT) project a Prompt Gamma Ray Analysis (PGRA) facility for the determination of the boron concentration in biological samples was built at light-water reactor at Řež. The facility utilizes the beam of thermal neutrons from a neutron guide. The pure beam of thermal neutrons and background conditions enables the determination of 1 ppm with the reasonable statistical error 5% within 15 minutes.

  4. Manufacturing uniform field silicon drift detector using double boron layer

    Energy Technology Data Exchange (ETDEWEB)

    Golshani, Negin, E-mail: negingolshani@gmail.com; Beenakker, C.I.M; Ishihara, R.

    2015-09-11

    Novel SDDs with continuous junctions on both sides are fabricated using pure boron (PureB) depositions to create a shallow junction in the entrance window side and a continuous rectifying junction with different potentials as function of the drift coordinate in the device side. The SDDs made in this material offer lower leakage current. In addition, continuous SDD designed with two boron layers with different sheet resistances displays uniform electric field.

  5. Explicitly correlated wave function for a boron atom

    CERN Document Server

    Puchalski, Mariusz; Pachucki, Krzysztof

    2015-01-01

    We present results of high-precision calculations for a boron atom's properties using wave functions expanded in the explicitly correlated Gaussian basis. We demonstrate that the well-optimized 8192 basis functions enable a determination of energy levels, ionization potential, and fine and hyperfine splittings in atomic transitions with nearly parts per million precision. The results open a window to a spectroscopic determination of nuclear properties of boron including the charge radius of the proton halo in the $^8$B nucleus.

  6. Dynamic compaction of boron carbide by a shock wave

    Science.gov (United States)

    Buzyurkin, Andrey E.; Kraus, Eugeny I.; Lukyanov, Yaroslav L.

    2016-10-01

    This paper presents experiments on explosive compaction of boron carbide powder and modeling of the stress state behind the shock front at shock loading. The aim of this study was to obtain a durable low-porosity compact sample. The explosive compaction technology is used in this problem because the boron carbide is an extremely hard and refractory material. Therefore, its compaction by traditional methods requires special equipment and considerable expenses.

  7. The Influence of Parameters Affecting Boron Removal by Electrocoagulation Process

    KAUST Repository

    Zeboudji, B.

    2013-04-01

    Boron removal in seawater desalination presents a particular challenge. In seawater reverse osmosis (SWRO) systems boron removal at low concentration (<0.5 mg/L) is usually achieved by a second pass using brackish water RO membranes. However, this process requires chemical addition and important additional investment, operation and maintenance, and energy costs. Electrocoagulation (EC) process can be used to achieve such low boron concentration. In this work, the removal of boron from aqueous solution was carried out by EC process using aluminum and iron electrodes. Several operating parameters on the removal efficiency such as initial pH, current density, initial boron ion concentration, feed concentration, gap between electrodes, and electrode material, were investigated. In the case of bipolar electrocoagulation (BEC), an optimum removal efficiency of 96% corresponding to a final boron concentration of 0.4 mg/L was achieved at a current density of 6 mA/cm2 and pH = 8 using aluminum electrodes. The concentration of NaCl was 2,500 mg/L and the gap between the electrodes of 0.5 cm. Furthermore, a comparison between monopolar electrocoagulation (MEC) and BEC using both aluminum and iron electrodes was carried out. Results showed that the BEC process has reduced the current density applied to obtain high level of boron removal in a short reaction time compared to MEC process. The high performance of the EC showed that the process could be used to reduce boron concentration to acceptable levels at low-cost and more environmentally friendly. © 2013 Copyright Taylor and Francis Group, LLC.

  8. Structural Modification in Carbon Nanotubes by Boron Incorporation

    Directory of Open Access Journals (Sweden)

    Handuja Sangeeta

    2009-01-01

    Full Text Available Abstract We have synthesized boron-incorporated carbon nanotubes (CNTs by decomposition of ferrocene and xylene in a thermal chemical vapor deposition set up using boric acid as the boron source. Scanning and transmission electron microscopy studies of the synthesized CNT samples showed that there was deterioration in crystallinity and improvement in alignment of the CNTs as the boron content in precursor solution increased from 0% to 15%. Raman analysis of these samples showed a shift of ~7 cm−1in wave number to higher side and broadening of the G band with increasing boron concentration along with an increase in intensity of the G band. Furthermore, there was an increase in the intensity of the D band along with a decrease in its wave number position with increase in boron content. We speculate that these structural modifications in the morphology and microstructure of CNTs might be due to the charge transfer from boron to the graphite matrix, resulting in shortening of the carbon–carbon bonds.

  9. Boron uptake, localization, and speciation in marine brown algae.

    Science.gov (United States)

    Miller, Eric P; Wu, Youxian; Carrano, Carl J

    2016-02-01

    In contrast to the generally boron-poor terrestrial environment, the concentration of boron in the marine environment is relatively high (0.4 mM) and while there has been extensive interest in its use as a surrogate of pH in paleoclimate studies in the context of climate change-related questions, the relatively depth independent, and the generally non-nutrient-like concentration profile of this element have led to boron being neglected as a potentially biologically relevant element in the ocean. Among the marine plant-like organisms the brown algae (Phaeophyta) are one of only five lineages of photosynthetic eukaryotes to have evolved complex multicellularity. Many of unusual and often unique features of brown algae are attributable to this singular evolutionary history. These adaptations are a reflection of the marine coastal environment which brown algae dominate in terms of biomass. Consequently, brown algae are of fundamental importance to oceanic ecology, geochemistry, and coastal industry. Our results indicate that boron is taken up by a facilitated diffusion mechanism against a considerable concentration gradient. Furthermore, in both Ectocarpus and Macrocystis some boron is most likely bound to cell wall constituent alginate and the photoassimilate mannitol located in sieve cells. Herein, we describe boron uptake, speciation, localization and possible biological function in two species of brown algae, Macrocystis pyrifera and Ectocarpus siliculosus.

  10. Boron concentration measurement in biological tissues by charged particle spectrometry.

    Science.gov (United States)

    Bortolussi, S; Altieri, S

    2013-11-01

    Measurement of boron concentration in biological tissues is a fundamental aspect of boron neutron capture therapy, because the outcome of the therapy depends on the distribution of boron at a cellular level, besides on its overall concentration. This work describes a measurement technique based on the spectroscopy of the charged particles emitted in the reaction (10)B(n,α)(7)Li induced by thermal neutrons, allowing for a quantitative determination of the boron concentration in the different components that may be simultaneously present in a tissue sample, such as healthy cells, tumor cells and necrotic cells. Thin sections of tissue containing (10)B are cut at low temperatures and irradiated under vacuum in a thermal neutron field. The charged particles arising from the sample during the irradiation are collected by a thin silicon detector, and their spectrum is used to determine boron concentration through relatively easy calculations. The advantages and disadvantages of this technique are here described, and validation of the method using tissue standards with known boron concentrations is presented.

  11. Boron Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review

    Science.gov (United States)

    Eisler, R.

    1990-01-01

    Ecological and toxicological aspects of boron (B) in the environment are reviewed, with emphasis on natural resources. Subtopics covered include environmental chemistry, background concentrations, effects, and current recommendations for the protection of living resources. Boron is not now considered essential in mammalian nutrition, although low dietary levels protect against fluorosis and bone demineralization. Excessive consumption (i.e., >1,000 mg B/kg diet, >15 mg B/kg body weight daily, >1.0 mg B/L drinking water, or >210 mg B/kg body weight in a single dose) adversely affects growth, survival, or reproduction in sensitive mammals. Boron and its compounds are potent teratogens when applied directly to the mammalian embryo, but there is no evidence of mutagenicity or carcinogenicity. Boron`s unique affinity for cancerous tissues has been exploited in neutron capture radiation therapy of malignant human brain tumors. Current boron criteria recommended for the protection of sensitive species include aquatic life, <5.0 mg B/L in livestock drinking waters, <30 mg B/kg in waterfowl diets, and <100 mg B/kg in livestock diets.

  12. Lattice vibrations of icosahedral boron-rich solids

    Energy Technology Data Exchange (ETDEWEB)

    Beckel, C.L.; Yousaf, M. (The University of New Mexico, Albuquerque, New Mexico 87131 (United States))

    1991-07-01

    The rhombohedral lattices for {alpha}-boron, boron arsenide, and boron phosphide are each of D{sub 3d} symmetry and have bases that include B{sub 12} icosahedra. Boron carbide with B{sub 4}C stoichiometry has near-D{sub 3d} symmetry and is almost certainly composed of B{sub 11}C icosahedra and C-B-C chains. Comparable classical force field models are applied to each of these crystals to correlate q=0 phonon structure with experimental Raman and IR spectra. We here describe our methods and contrast interaction strengths for different materials. Vibrations are correlated in the different crystals through normal mode eigenvector expansions. Acoustic wave velocities from Brillouin zone dispersion curves in two distinct symmetry-axis directions are presented and contrasted for {alpha}-boron and B{sub 12}As{sub 2}. The origin of lines with anomalous polarization and width in {alpha}-boron, B{sub 12}As{sub 2}, and B{sub 12}P{sub 2} is considered.

  13. Experimental realization of two-dimensional boron sheets.

    Science.gov (United States)

    Feng, Baojie; Zhang, Jin; Zhong, Qing; Li, Wenbin; Li, Shuai; Li, Hui; Cheng, Peng; Meng, Sheng; Chen, Lan; Wu, Kehui

    2016-06-01

    A variety of two-dimensional materials have been reported in recent years, yet single-element systems such as graphene and black phosphorus have remained rare. Boron analogues have been predicted, as boron atoms possess a short covalent radius and the flexibility to adopt sp(2) hybridization, features that favour the formation of two-dimensional allotropes, and one example of such a borophene material has been reported recently. Here, we present a parallel experimental work showing that two-dimensional boron sheets can be grown epitaxially on a Ag(111) substrate. Two types of boron sheet, a β12 sheet and a χ3 sheet, both exhibiting a triangular lattice but with different arrangements of periodic holes, are observed by scanning tunnelling microscopy. Density functional theory simulations agree well with experiments, and indicate that both sheets are planar without obvious vertical undulations. The boron sheets are quite inert to oxidization and interact only weakly with their substrate. We envisage that such boron sheets may find applications in electronic devices in the future.

  14. Boron transport in Eucalyptus. 2. Identification in silico of a putative boron transporter for xylem loading in eucalypt

    Directory of Open Access Journals (Sweden)

    Douglas Silva Domingues

    2005-01-01

    Full Text Available Boron (B is a low mobility plant micronutrient whose molecular mechanisms of absorption and translocation are still controversial. Many factors are involved in tolerance to Boron excess or deficiency. Recently, the first protein linked to boron transport in biological systems, BOR1, was characterized in Arabidopsis thaliana. This protein is involved in boron xylem loading and is similar to bicarbonate transporters found in animals. There are indications that BOR1 is a member of a conserved protein family in plants. In this work, FORESTS database was used to identify sequences similar to this protein family, looking for a probable BOR1 homolog in eucalypt. We found five consensus sequences similar to BOR1; three of them were then used in multiple alignment analysis. Based on amino acid similarity and in silico expression patterns, a consensus sequence was identified as a candidate BOR1 homolog, helping deeper experimental assays that could identify the function of this protein family in Eucalyptus.

  15. Lattice dynamics of {alpha} boron and of boron carbide; Proprietes vibrationnelles du bore {alpha} et du carbure de bore

    Energy Technology Data Exchange (ETDEWEB)

    Vast, N

    1999-07-01

    The atomic structure and the lattice dynamics of {alpha} boron and of B{sub 4}C boron carbide have been studied by Density Functional Theory (D.F.T.) and Density Functional Perturbation Theory (D.F.P.T.). The bulk moduli of the unit-cell and of the icosahedron have been investigated, and the equation of state at zero temperature has been determined. In {alpha} boron, Raman diffusion and infrared absorption have been studied under pressure, and the theoretical and experimental Grueneisen coefficients have been compared. In boron carbide, inspection of the theoretical and experimental vibrational spectra has led to the determination of the atomic structure of B{sub 4}C. Finally, the effects of isotopic disorder have been modeled by an exact method beyond the mean-field approximation, and the effects onto the Raman lines has been investigated. The method has been applied to isotopic alloys of diamond and germanium. (author)

  16. Functionalization and cellular uptake of boron carbide nanoparticles. The first step toward T cell-guided boron neutron capture therapy.

    Science.gov (United States)

    Mortensen, M W; Björkdahl, O; Sørensen, P G; Hansen, T; Jensen, M R; Gundersen, H J G; Bjørnholm, T

    2006-01-01

    In this paper we present surface modification strategies of boron carbide nanoparticles, which allow for bioconjugation of the transacting transcriptional activator (TAT) peptide and fluorescent dyes. Coated nanoparticles can be translocated into murine EL4 thymoma cells and B16 F10 malignant melanoma cells in amounts as high as 0.3 wt. % and 1 wt. %, respectively. Neutron irradiation of a test system consisting of untreated B16 cells mixed with B16 cells loaded with boron carbide nanoparticles were found to inhibit the proliferative capacity of untreated cells, showing that cells loaded with boron-containing nanoparticles can hinder the growth of neighboring cells upon neutron irradiation. This could provide the first step toward a T cell-guided boron neutron capture therapy.

  17. Effects of excess and deficient boron and niacin on the ultrastructure of root cells in Daucus carota cv. Nantes

    OpenAIRE

    DEMİRAY, Hatice; DEREBOYLU, Aylin EŞİZ

    2013-01-01

    The effects of excess and deficient boron and niacin on vascular tissues of carrot roots (Daucus carota L. cv. Nantes) were investigated in plants grown in medium both rich and poor in boron and also boron with niacin. Five media were investigated: control (MS medium), boron-deficient MS medium, MS medium with excess boron, niacin-deficient MS medium, MS medium with niacin excess, and MS medium with excess boron and niacin. In anatomical cross sections, lignification was seen in middle lamell...

  18. Boron Neutron Capture Therapy (BCNT) for the Treatment of Liver Metastases: Biodistribution Studies of Boron Compounds in an Experimental Model

    Energy Technology Data Exchange (ETDEWEB)

    Marcela A. Garabalino; Andrea Monti Hughes; Ana J. Molinari; Elisa M. Heber; Emiliano C. C. Pozzi; Maria E. Itoiz; Veronica A. Trivillin; Amanda E. Schwint; Jorge E. Cardoso; Lucas L. Colombo; Susana Nievas; David W. Nigg; Romina F. Aromando

    2011-03-01

    Abstract We previously demonstrated the therapeutic efficacy of different boron neutron capture therapy (BNCT) protocols in an experimental model of oral cancer. BNCT is based on the selective accumulation of 10B carriers in a tumor followed by neutron irradiation. Within the context of exploring the potential therapeutic efficacy of BNCT for the treatment of liver metastases, the aim of the present study was to perform boron biodistribution studies in an experimental model of liver metastases in rats. Different boron compounds and administration conditions were assayed to determine which administration protocols would potentially be therapeutically useful in in vivo BNCT studies at the RA-3 nuclear reactor. A total of 70 BDIX rats were inoculated in the liver with syngeneic colon cancer cells DHD/K12/TRb to induce the development of subcapsular tumor nodules. Fourteen days post-inoculation, the animals were used for biodistribution studies. We evaluated a total of 11 administration protocols for the boron compounds boronophenylalanine (BPA) and GB-10 (Na210B10H10), alone or combined at different dose levels and employing different administration routes. Tumor, normal tissue, and blood samples were processed for boron measurement by atomic emission spectroscopy. Six protocols proved potentially useful for BNCT studies in terms of absolute boron concentration in tumor and preferential uptake of boron by tumor tissue. Boron concentration values in tumor and normal tissues in the liver metastases model show it would be feasible to reach therapeutic BNCT doses in tumor without exceeding radiotolerance in normal tissue at the thermal neutron facility at RA-3.

  19. PET pharmacokinetic analysis to estimate boron concentration in tumor and brain as a guide to plan BNCT for malignant cerebral glioma

    Energy Technology Data Exchange (ETDEWEB)

    Nariai, Tadashi [Department of Neurosurgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo (Japan)], E-mail: nariai.nsrg@tmd.ac.jp; Ishiwata, Kiichi [Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 1-1, Nakacho, Itabashi-ku, Tokyo (Japan); Kimura, Yuichi [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba (Japan); Inaji, Motoki; Momose, Toshiya [Department of Neurosurgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo (Japan); Yamamoto, Tetsuya; Matsumura, Akira [Department of Neurosurgery, University of Tsukuba, Tennodai, Tsukuba, Igaraki (Japan); Ishii, Kenji [Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 1-1, Nakacho, Itabashi-ku, Tokyo (Japan); Ohno, Kikuo [Department of Neurosurgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo (Japan)

    2009-07-15

    Introduction: To plan the optimal BNCT for patients with malignant cerebral glioma, estimation of the ratio of boron concentration in tumor tissue against that in the surrounding normal brain (T/N ratio of boron) is important. We report a positron emission tomography (PET) imaging method to estimate T/N ratio of tissue boron concentration based on pharmacokinetic analysis of amino acid probes. Methods: Twelve patients with cerebral malignant glioma underwent 60 min dynamic PET scanning of brain after bolus injection of {sup 18}F-borono-phenyl-alanine (FBPA) with timed arterial blood sampling. Using kinetic parameter obtained by this scan, T/N ratio of boron concentration elicited by one-hour constant infusion of BPA, as performed in BNCT, was simulated on Runge-Kutta algorithm. {sup 11}C-methionine (MET) PET scan, which is commonly used in worldwide PET center as brain tumor imaging tool, was also performed on the same day to compare the image characteristics of FBPA and that of MET. Result: PET glioma images obtained with FBPA and MET are almost identical in all patients by visual inspection. Estimated T/N ratio of tissue boron concentration after one-hour constant infusion of BPA, T/N ratio of FBPA on static condition, and T/N ratio of MET on static condition showed significant linear correlation between each other. Conclusion: T/N ratio of boron concentration that is obtained by constant infusion of BPA during BNCT can be estimated by FBPA PET scan. This ratio can also be estimated by MET-PET imaging. As MET-PET study is available in many clinical PET center, selection of candidates for BNCT may be possible by MET-PET images. Accurate planning of BNCT may be performed by static images of FBPA PET. Use of PET imaging with amino acid probes may contribute very much to establish an appropriate application of BNCT for patients with malignant glioma.

  20. The boron content in soils of solonetzic complexes in the Irtysh Region of Omsk oblast and the boron resistance of plants

    Science.gov (United States)

    Azarenko, Yu. A.

    2007-05-01

    Data on the boron content in the main soil types of solonetzic complexes in the Irtysh Region of Omsk oblast are given. They attest to the boron salinization of the soils. It is shown that there is a risk of excessive boron accumulation in natural plants and crops. The boron resistance of crops cultivated on the boronsaline soils has been examined in the field and in pot experiments. Approximate normal and toxic levels of the boron content in soils and in plants and the corresponding Ca-to-B ratios in the aboveground phytomass are suggested. Amelioration of solonetzes with application of gypsum and phosphogypsum reduces the degree of their boron salinization and the boron uptake by plants.

  1. Boron sorption from aqueous solution by hydrotalcite and its preliminary application in geothermal water deboronation.

    Science.gov (United States)

    Guo, Qinghai; Zhang, Yin; Cao, Yaowu; Wang, Yanxin; Yan, Weide

    2013-11-01

    Hydrotalcite and its calcination product were used to treat pure water spiked with various concentrations of boron and geothermal water containing boron as a major undesirable element. The kinetics process of boron sorption by uncalcined hydrotalcite is controlled by the diffusion of boron from bulk solution to sorbent-solution boundary film and its exchange with interlayer chloride of hydrotalcite, whereas the removal rate of boron by calcined hydrotalcite rests with the restoration process of its layered structure. The results of isotherm sorption experiments reveal that calcined hydrotalcite generally has much stronger ability to lower solution boron concentration than uncalcined hydrotalcite. The combination of adsorption of boron on the residue of MgO-Al2O3 solid solution and intercalation of boron into the reconstructed hydrotalcite structure due to "structural memory effect" is the basic mechanism based on which the greater boron removal by calcined hydrotalcite was achieved. As 15 geothermal water samples were used to test the deboronation ability of calcined hydrotalcite at 65 °C, much lower boron removal efficiencies were observed. The competitive sorption of the other anions in geothermal water, such as HCO3-, SO4(2-), and F-, is the reason why calcined hydrotalcite could not remove boron from geothermal water as effectively as from pure boron solution. However, boron removal percents ranging from 89.3 to 99.0% could be obtained if 50 times of sorbent were added to the geothermal water samples. Calcined hydrotalcite is a good candidate for deboronation of geothermal water.

  2. Effect of Boron on Delayed Fracture Resistance of Medium-Carbon High Strength Spring Steel

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The delayed fracture behavior of medium-carbon high strength spring steel containing different amounts of boron (0. 000 5%, 0. 001 6%) was studied using sustained load delayed fracture test. The results show that delayed fracture resistance of boron containing steels is higher than that of conventional steel 60Si2MnA at the same strength level and it increases with the increase of boron content from 0. 000 5 % to 0. 001 6 %. The delayed fracture mode is mainly intergranular in the boron containing steels tempered at 350 ℃, which indicates that the addition of boron does not change the fracture character. However, the increase of boron content enlarges the size of the crack initiation area. Further study of phase analysis indicates that most boron is in solid solution, and only a very small quantity of boron is in the M3 (C, B) phase.

  3. Cross-Linked Dependency of Boronic Acid-Conjugated Chitosan Nanoparticles by Diols for Sustained Insulin Release

    Directory of Open Access Journals (Sweden)

    Nabil A. Siddiqui

    2016-10-01

    Full Text Available Boronic acids have been widely investigated for their potential use as glucose sensors in glucose responsive polymeric insulin delivery systems. Interactions between cyclic diols and boronic acids, anchored to polymeric delivery systems, may result in swelling of the delivery system, releasing the drug. In this study, 4-formylphenylboronic acid conjugated chitosan was formulated into insulin containing nanoparticles via polyelectrolyte complexation. The nanoparticles had an average diameter of 140 ± 12.8 nm, polydispersity index of 0.17 ± 0.1, zeta potential of +19.1 ± 0.69 mV, encapsulation efficiency of 81% ± 1.2%, and an insulin loading capacity of 46% ± 1.8% w/w. Changes in size of the nanoparticles and release of insulin were type of sugar- and concentration-dependent. High concentration of diols resulted in a sustained release of insulin due to crosslink formation with boronic acid moieties within the nanoparticles. The formulation has potential to be developed into a self-regulated insulin delivery system for the treatment of diabetes.

  4. The corrosion resistance of zinc coatings in the presence of boron-doped detonation nanodiamonds (DND)

    Science.gov (United States)

    Burkat, G. K.; Alexandrova, G. S.; Dolmatov, V. Yu; Osmanova, E. D.; Myllymäki, V.; Vehanen, A.

    2017-02-01

    The effect of detonation nanodiamonds, doped with boron (boron-DND) in detonation synthesis on the process of zinc electrochemical deposition from zincate electrolyte is investigated. It is shown that the scattering power (coating uniformity) increases 2-4 times (depending on the concentration of DND-boron electrolyte conductivity does not change, the corrosion resistance of Zn- DND -boron coating increases 2.6 times in 3% NaCl solution (corrosion currents) and 3 times in the climatic chamber.

  5. Boron neutron capture therapy outcomes for advanced or recurrent head and neck cancer

    Science.gov (United States)

    Suzuki, Minoru; Kato, Ituro; Aihara, Teruhito; Hiratsuka, Junichi; Yoshimura, Kenichi; Niimi, Miyuki; Kimura, Yoshihiro; Ariyoshi, Yasunori; Haginomori, Shin-ichi; Sakurai, Yoshinori; Kinashi, Yuko; Masunaga, Shin-ichiro; Fukushima, Masanori; Ono, Koji; Maruhashi, Akira

    2014-01-01

    We retrospectively review outcomes of applying boron neutron capture therapy (BNCT) to unresectable advanced or recurrent head and neck cancers. Patients who were treated with BNCT for either local recurrent or newly diagnosed unresectable head or neck cancers between December 2001 and September 2007 were included. Clinicopathological characteristics and clinical outcomes were retrieved from hospital records. Either a combination of borocaptate sodium and boronophenylalanine (BPA) or BPA alone were used as boron compounds. In all the treatment cases, the dose constraint was set to deliver a dose <10–12 Gy-eq to the skin or oral mucosa. There was a patient cohort of 62, with a median follow-up of 18.7 months (range, 0.7–40.8). A total of 87 BNCT procedures were performed. The overall response rate was 58% within 6 months after BNCT. The median survival time was 10.1 months from the time of BNCT. The 1- and 2-year overall survival (OS) rates were 43.1% and 24.2%, respectively. The major acute Grade 3 or 4 toxicities were hyperamylasemia (38.6%), fatigue (6.5%), mucositis/stomatitis (9.7%) and pain (9.7%), all of which were manageable. Three patients died of treatment-related toxicity. Three patients experienced carotid artery hemorrhage, two of whom had coexistent infection of the carotid artery. This study confirmed the feasibility of our dose-estimation method and that controlled trials are warranted. PMID:23955053

  6. The effect of the boron source composition ratio on the adsorption performance of hexagonal boron nitride without a template

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ning, E-mail: zhangning5832@163.com; Zhang, Tong; Kan, Hongmin; Wang, Xiaoyang; Long, Haibo; Cui, Xingyu

    2015-08-01

    An inexpensive boric acid (H{sub 3}BO{sub 3}) and borax (Na{sub 2}B{sub 4}O{sub 7}·10H{sub 2}O) mix was used as a source of boron with different composition ratios, and urea was used as a nitrogen source, in flowing ammonia atmosphere, for the preparation of hexagonal boron nitride (h-BN) with different micro-morphologies. Under a certain synthesis process, the effects of the molar ratio of borax and boric acid (or simply the boron source composition ratio for short) on the phase composition of the sample were studied; the work also explored the effect of boron source composition ratio on the micro-morphology, adsorption desorption isotherm and specific surface area of the h-BN powder. The main purpose of this work was to determine the optimum composition ratio of preparing spherical mesoporous h-BN and ensure that the micro-mechanism underpinning the formation of spherical mesoporous h-BN was understood. The results showed that at the optimum boron source composition ratio of 1:1, globular mesoporous spheres with a diameter of approximately 600–800 nm could be obtained with the highest pore volume and specific surface area (230.2 m{sup 2}/g). - Graphical abstract: Display Omitted - Highlights: • Spherical h-BN was synthesized by controlling the boron source composition ratio. • Without extra spherical template, solid Na{sub 2}O was equal to a spherical template. • At boron source composition ratio of 1:1, h-BN had best adsorption performance.

  7. Nickel-boron electrochemical properties investigations

    Energy Technology Data Exchange (ETDEWEB)

    Kanta, A.-F., E-mail: abdoul.kanta@umons.ac.b [Service de Science des Materiaux, Universite de Mons, 56 rue de l' Epargne, 7000 Mons (Belgium); Poelman, M. [Materia Nova a.s.b.l, 56 rue de l' Epargne, 7000 Mons (Belgium); Vitry, V.; Delaunois, F. [Service de Metallurgie, Universite de Mons, 56 rue de l' Epargne, 7000 Mons (Belgium)

    2010-08-27

    Electroless nickel-boron (Ni-B) was synthesized on mild steel. Coating thickness was approximately 30 {mu}m. Some of the coatings were submitted to a hardening heat treatment at 400 {sup o}C for 1 h in an atmosphere containing 95% Ar and 5% H{sub 2} to improve their mechanical performance. Heat treated and untreated samples were submitted to the Taber abrasion test to assess their wear resistance. The wear track was then examined by SEM and roughness measurement. The Taber Wear Index of untreated samples was slightly better than that of steel but heat treated samples attained TWI as small as 13. The corrosion resistance of the Ni-B coatings was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. The EIS results showed diffusion phenomena in 0.1 M NaCl solution. Electroless Ni-B coating increases the corrosion resistance of steel and heat treatments allow a further enhancement. Wear decreases that resistance but the worn product keeps a better behaviour than uncoated parts.

  8. Ceramic processing of boron nitride insulators

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, C. S.; McCulloch, R. W.

    1977-01-01

    Fuel pin simulators (FPS) are the prime elements of several test facilities at the Oak Ridge National Laboratory (ORNL). These experimental facilities are used to conduct out-of-reactor thermal-hydraulic and mechanical interaction safety tests for both light-water and breeder reactor programs. The FPS units simulate the geometry, heat flux profiles, and operational capabilities of a reactor core element under steady-state and transient conditions. They are subjected to temperatures as high as 1600/sup 0/C (2900/sup 0/F) and power levels as high as 57.5 kW/m (17.5 kW/ft) as well as severe thermal stresses during transient tests. The insulating material in the narrow annulus between the heating coil and the FPS sheath is subjected to very rigorous conditions. Accuracy of the reactor safety test information and validity of the test data depend on the heat flux uniformity under all test conditions and on the reliable operation of all fuel pin simulators and their internal thermocouples. Boron nitride (BN), because of its high degree of chemical inertness combined with its relatively unique properties of high thermal conductivity and low electrical conductivity, is the most suitable insulating material for FPS. The important BN properties, thermal conductivity and electrical resistance, are strongly influenced by crystallite orientation and by impurities. The article describes new BN powder processing techniques, which optimize these properties.

  9. Hexagonal boron-nitride nanomesh magnets

    Science.gov (United States)

    Ohata, C.; Tagami, R.; Nakanishi, Y.; Iwaki, R.; Nomura, K.; Haruyama, J.

    2016-09-01

    The formation of magnetic and spintronic devices using two-dimensional (2D) atom-thin layers has attracted attention. Ferromagnetisms (FMs) arising from zigzag-type atomic structure of edges of 2D atom-thin materials have been experimentally observed in graphene nanoribbons, hydrogen (H)-terminated graphene nanomeshes (NMs), and few-layer oxygen (O)-terminated black phosphorus NMs. Herein, we report room-temperature edge FM in few-layer hexagonal boron-nitride (hBN) NMs. O-terminated hBNNMs annealed at 500 °C show the largest FM, while it completely disappears in H-terminated hBNNMs. When hBNNMs are annealed at other temperatures, amplitude of the FM significantly decreases. These are highly in contrast to the case of graphene NMs but similar to the cases of black phosphorus NM and suggest that the hybridization of the O atoms with B(N) dangling bonds of zigzag pore edges, formed at the 500 °C annealing, strongly contribute to this edge FM. Room-temperature FM realizable only by exposing hBNNMs into air opens the way for high-efficiency 2D flexible magnetic and spintronic devices without the use of rare magnetic elements.

  10. Boronline, a new generation of boron meter

    Energy Technology Data Exchange (ETDEWEB)

    Pirat, P. [Rolls-Royce Company, Meylan (France)

    2011-07-01

    Rolls-Royce is a global business providing integrated power systems for use on land, at sea and in the air. The Group has a balanced business portfolio with leading market positions - civil aerospace, defence aerospace, marine and energy Rolls-Royce understands the challenges of design, procurement, manufacture, operation and in-service support of nuclear reactor plants, with over 50 years of experience through the Royal Navy submarine programme. Rolls-Royce can therefore offer full product life-cycle management for new civil nuclear installations, as well as support to existing installations, including plant lifetime extensions. Rolls-Royce produced for 40 years, Instrumentation and Control (I and C) systems of and associated services for nuclear reactors in Europe, including 58 French reactors and others situated in the United States and in others countries, such as China. Rolls-Royce equipped in this domain 200 nuclear reactors in 20 countries. Among all of its nuclear systems, Rolls Royce is presenting to the conference its new generation of on-line boron measurement system, so called Boronline. (authors)

  11. Hyperbolic phonon polaritons in hexagonal boron nitride

    Science.gov (United States)

    Dai, Siyuan

    2015-03-01

    Uniaxial materials whose axial and tangential permittivities have opposite signs are referred to as indefinite or hyperbolic media. While hyperbolic responses are normally achieved with metamaterials, hexagonal boron nitride (hBN) naturally possesses this property due to the anisotropic phonons in the mid-infrared. Using scattering-type scanning near-field optical microscopy, we studied polaritonic phenomena in hBN. We performed infrared nano-imaging of highly confined and low-loss hyperbolic phonon polaritons in hBN. The polariton wavelength was shown to be governed by the hBN thickness according to a linear law persisting down to few atomic layers [Science, 343, 1125-1129 (2014)]. Additionally, we carried out the modification of hyperbolic response in heterostructures comprised of a mononlayer graphene deposited on hBN. Electrostatic gating of the top graphene layer allows for the modification of wavelength and intensity of hyperbolic phonon polaritons in bulk hBN. The physics of the modification originates from the plasmon-phonon coupling in the hyperbolic medium. Furthermore, we demonstrated the ``hyperlens'' for subdiffractional imaging and focusing using a slab of hBN.

  12. Boron Nitride Nanostructures: Fabrication, Functionalization and Applications.

    Science.gov (United States)

    Yin, Jun; Li, Jidong; Hang, Yang; Yu, Jin; Tai, Guoan; Li, Xuemei; Zhang, Zhuhua; Guo, Wanlin

    2016-06-01

    Boron nitride (BN) structures are featured by their excellent thermal and chemical stability and unique electronic and optical properties. However, the lack of controlled synthesis of quality samples and the electrically insulating property largely prevent realizing the full potential of BN nanostructures. A comprehensive overview of the current status of the synthesis of two-dimensional hexagonal BN sheets, three dimensional porous hexagonal BN materials and BN-involved heterostructures is provided, highlighting the advantages of different synthetic methods. In addition, structural characterization, functionalizations and prospective applications of hexagonal BN sheets are intensively discussed. One-dimensional BN nanoribbons and nanotubes are then discussed in terms of structure, fabrication and functionality. In particular, the existing routes in pursuit of tunable electronic and magnetic properties in various BN structures are surveyed, calling upon synergetic experimental and theoretical efforts to address the challenges for pioneering the applications of BN into functional devices. Finally, the progress in BN superstructures and novel B/N nanostructures is also briefly introduced.

  13. Phonon transport in single-layer boron nanoribbons

    Science.gov (United States)

    Zhang, Zhongwei; Xie, Yuee; Peng, Qing; Chen, Yuanping

    2016-11-01

    Inspired by the successful synthesis of three two-dimensional (2D) allotropes, the boron sheet has recently been one of the hottest 2D materials around. However, to date, phonon transport properties of these new materials are still unknown. By using the non-equilibrium Green’s function (NEGF) combined with the first principles method, we study ballistic phonon transport in three types of boron sheets; two of them correspond to the structures reported in the experiments, while the third one is a stable structure that has not been synthesized yet. At room temperature, the highest thermal conductance of the boron nanoribbons is comparable with that of graphene, while the lowest thermal conductance is less than half of graphene’s. Compared with graphene, the three boron sheets exhibit diverse anisotropic transport characteristics. With an analysis of phonon dispersion, bonding charge density, and simplified models of atomic chains, the mechanisms of the diverse phonon properties are discussed. Moreover, we find that many hybrid patterns based on the boron allotropes can be constructed naturally without doping, adsorption, and defects. This provides abundant nanostructures for thermal management and thermoelectric applications.

  14. Aggregation and deposition behavior of boron nanoparticles in porous media.

    Science.gov (United States)

    Liu, Xuyang; Wazne, Mahmoud; Christodoulatos, Christos; Jasinkiewicz, Kristin L

    2009-02-01

    New kinds of solid fuels and propellants comprised of nanomaterials are making their way into civilian and military applications yet the impact of their release on the environment remains largely unknown. One such material is nano boron, a promising solid fuel and propellant. The fate and transport of nano boron under various aquatic systems was investigated in aggregation and deposition experiments. Column experiments were performed to examine the effects of electrolyte concentration and flow velocity on the transport of boron nanoparticles under saturated conditions, whereas aggregation tests were conducted to assess the effects of electrolytes on the aggregation of the boron nanoparticles. Aggregation tests indicated the presence of different reaction-controlled and diffusion-controlled regimes and yielded critical coagulation concentrations (CCC) of 200 mM, 0.7 mM and 1.5 mM for NaCl, CaCl(2), and MgCl(2), respectively. Aggregation and deposition experimental data corresponded with the classic Derjaguin-Landau-Verwey-Overbeek (DLVO) model and the constant attachment efficiency filtration model, respectively. Theoretical calculations indicated that both the primary and secondary energy minima play important roles in the deposition of nano boron in sand columns.

  15. Disorder and defects are not intrinsic to boron carbide

    Science.gov (United States)

    Mondal, Swastik; Bykova, Elena; Dey, Somnath; Ali, Sk Imran; Dubrovinskaia, Natalia; Dubrovinsky, Leonid; Parakhonskiy, Gleb; van Smaalen, Sander

    2016-01-01

    A unique combination of useful properties in boron-carbide, such as extreme hardness, excellent fracture toughness, a low density, a high melting point, thermoelectricity, semi-conducting behavior, catalytic activity and a remarkably good chemical stability, makes it an ideal material for a wide range of technological applications. Explaining these properties in terms of chemical bonding has remained a major challenge in boron chemistry. Here we report the synthesis of fully ordered, stoichiometric boron-carbide B13C2 by high-pressure–high-temperature techniques. Our experimental electron-density study using high-resolution single-crystal synchrotron X-ray diffraction data conclusively demonstrates that disorder and defects are not intrinsic to boron carbide, contrary to what was hitherto supposed. A detailed analysis of the electron density distribution reveals charge transfer between structural units in B13C2 and a new type of electron-deficient bond with formally unpaired electrons on the C–B–C group in B13C2. Unprecedented bonding features contribute to the fundamental chemistry and materials science of boron compounds that is of great interest for understanding structure-property relationships and development of novel functional materials.

  16. Raman effect in icosahedral boron-rich solids

    Directory of Open Access Journals (Sweden)

    Helmut Werheit, Volodymyr Filipov, Udo Kuhlmann, Ulrich Schwarz, Marc Armbrüster, Andreas Leithe-Jasper, Takaho Tanaka, Iwami Higashi, Torsten Lundström, Vladimir N Gurin and Maria M Korsukova

    2010-01-01

    Full Text Available We present Raman spectra of numerous icosahedral boron-rich solids having the structure of α-rhombohedral, β-rhombohedral, α-tetragonal, β-tetragonal, YB66, orthorhombic or amorphous boron. The spectra were newly measured and, in some cases, compared with reported data and discussed. We emphasize the importance of a high signal-to-noise ratio in the Raman spectra for detecting weak effects evoked by the modification of compounds, accommodation of interstitial atoms and other structural defects. Vibrations of the icosahedra, occurring in all the spectra, are interpreted using the description of modes in α-rhombohedral boron by Beckel et al. The Raman spectrum of boron carbide is largely clarified. Relative intra- and inter-icosahedral bonding forces are estimated for the different structural groups and for vanadium-doped β-rhombohedral boron. The validity of Badger's rule is demonstrated for the force constants of inter-icosahedral B–B bonds, whereas the agreement is less satisfactory for the intra-icosahedral B–B bonds.

  17. Multidimensional potential of boron-containing molecules in functional materials

    Indian Academy of Sciences (India)

    Wolfgang Kaim; Narayan S Hosmane

    2010-01-01

    Boron-containing molecular systems have received much attention under theoretical aspects and from the side of synthetic organic chemistry. However, their potential for further applications such as optically interesting effects such as Non-Linear Optics (NLO), medical uses for Boron Neutron Capture Therapy (BNCT), or magnetism has been recognised only fairly recently. Molecular systems containing boron offer particular mechanisms to accommodate unpaired electrons which may result in stable radicals as spin-bearing materials. Among such materials are organoboron compounds in which the prototypical electron deficient (10B, 11B) boron vs. carbon centers can accept and help to delocalise added electrons in a 2-dimensionally conjugated system. Alternatively, oligoboron clusters B$_{n}$X$_{n}^{k}$ and the related carboranes or metallacarboranes are capable of adding or losing single electrons to form paramagnetic clusters with 3-dimensionally delocalised spin, according to combined experimental studies and quantum chemical calculations. The unique nuclear properties of 10B are of therapeutic value if their selective transport via appended carbon nanotubes, boron nanotubes, or magnetic nanoparticles can be effected.

  18. Ab initio modelling of boron related defects in amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Tiago A.; Torres, Vitor J.B. [Department of Physics, University of Aveiro, Campus Santiago, 3810-193 Aveiro (Portugal)

    2012-10-15

    We have modeled boron related point defects in amorphous silicon, using an ab initio method, the Density functional theory-pseudopotential code Aimpro. The boron atoms were embedded in 64 atom amorphous silicon cubic supercells. The calculations were performed using boron defects in 15 different supercells. These supercells were developed using a modified Wooten-Winer-Weaire bond switching mechanism. In average, the properties of the 15 supercells agree with the observed radial and bond angle distributions, as well the electronic and vibrational density of states and Raman spectra. In amorphous silicon it has been very hard to find real self-interstitials, since for almost all the tested configurations, the amorphous lattice relaxes overall. We found that substitutional boron prefers to be 4-fold coordinated. We find also an intrinsic hole-trap in the non-doped amorphous lattice, which may explain the low efficiency of boron doping. The local vibrational modes are, in average, higher than the correspondent crystalline values (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Disorder and defects are not intrinsic to boron carbide.

    Science.gov (United States)

    Mondal, Swastik; Bykova, Elena; Dey, Somnath; Ali, Sk Imran; Dubrovinskaia, Natalia; Dubrovinsky, Leonid; Parakhonskiy, Gleb; van Smaalen, Sander

    2016-01-18

    A unique combination of useful properties in boron-carbide, such as extreme hardness, excellent fracture toughness, a low density, a high melting point, thermoelectricity, semi-conducting behavior, catalytic activity and a remarkably good chemical stability, makes it an ideal material for a wide range of technological applications. Explaining these properties in terms of chemical bonding has remained a major challenge in boron chemistry. Here we report the synthesis of fully ordered, stoichiometric boron-carbide B13C2 by high-pressure-high-temperature techniques. Our experimental electron-density study using high-resolution single-crystal synchrotron X-ray diffraction data conclusively demonstrates that disorder and defects are not intrinsic to boron carbide, contrary to what was hitherto supposed. A detailed analysis of the electron density distribution reveals charge transfer between structural units in B13C2 and a new type of electron-deficient bond with formally unpaired electrons on the C-B-C group in B13C2. Unprecedented bonding features contribute to the fundamental chemistry and materials science of boron compounds that is of great interest for understanding structure-property relationships and development of novel functional materials.

  20. On the spectroscopic detection of neutral species in a low-pressure plasma containing boron and hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Lavrov, B P [Faculty of Physics, St. Petersburg State University, St. Petersburg, 198504 (Russian Federation); Osiac, M [Institut fuer Niedertemperatur-Plasmaphysik, 17489 Greifswald, Friedrich-Ludwig-Jahn-Str. 19 (Germany); Pipa, A V [Faculty of Physics, St. Petersburg State University, St. Petersburg, 198504 (Russian Federation); Roepcke, J [Institut fuer Niedertemperatur-Plasmaphysik, 17489 Greifswald, Friedrich-Ludwig-Jahn-Str. 19 (Germany)

    2003-11-01

    Spectroscopic studies of microwave discharges in H{sub 2}-Ar-B{sub 2}H{sub 6} gas mixtures (f = 2.45 GHz, P = 1.2-3.5 kW, p = 1-8 mbar) have been performed to improve the possibilities of diagnostics of non-equilibrium, low-pressure plasmas containing boron and hydrogen. For this purpose, UV-VIS optical emission spectroscopy and infrared absorption spectroscopy with tunable diode lasers (TDLAS) have been applied. It is shown that information about neutral species and the gas temperature may be obtained by means of new and modified spectroscopic methods. A method for the determination of the absolute number density of boron atoms from measured relative intensities of the components of the boron resonance doublet (distorted by reabsorption) is proposed and tested for validity. The maximum of the density was found to be 3.8x10{sup 11} atoms cm{sup -3} at an admixture of diborane of about 2%. The gas temperature was determined from the intensity distributions in the rotational structure of the emission bands of BH and H{sub 2} and from Doppler broadening of the absorption line profiles of the BH molecule. It was observed that values of the gas temperature obtained from the rotational intensity distributions are in good agreement with those obtained from Doppler widths (T{sub g} = 700-1070 K). Based on measurements of the relative line intensities of atomic and molecular hydrogen and the gas temperature, and using a simple excitation-deactivation model, the density of molecular hydrogen was found to be about 40 times higher than the density of atomic hydrogen. It is shown that some absorption lines of boron hydrides (B{sub 2}H{sub 6}, BH{sub 3} and BH) detected by TDLAS may be used for plasma diagnostics.

  1. Manufacture of Boron-free Magnesia with High Purity from Residual Brine

    Institute of Scientific and Technical Information of China (English)

    Fa Qiang LI; Bao Ping LING; Pei Hua MA

    2004-01-01

    A novel method for removing boron with ion exchange resin from residual brines to manufacture boron-free magnesia is described. The concentration of boron in the target magnesia manufactured thereby from Qinghai salt lakes is lower than 5μg/g, and the typical D50 size of product is 10.625μm.

  2. Dietary boron in the typical diet: possible essential roles in human and animal physiology

    Science.gov (United States)

    Boron is a bioactive element of low molecular weight. Since discovery of the first boron biomolecule, boromycin, in 1967, several other similar biomolecules are now well-characterized. Most recently described was a bacterial cell-to-cell communication signal that requires boron, autoinducer-II. Boro...

  3. Isolation and characterization of indigenous Streptomyces and Lentzea strains from soils containing boron compounds in Argentina.

    Science.gov (United States)

    Moraga, Norma Beatriz; Poma, Hugo Ramiro; Amoroso, María Julia; Rajal, Verónica Beatriz

    2014-06-01

    The Salta Province - in the northwest of Argentina - is the main worldwide producer of hydroboracite and leads in exports of boron mineral and its derivatives in Latin America. In addition to the natural presence of boron compounds in the soils, there are others contaminated due to the boron mining industry. Although some bacteria are known to require boron for their growth or to be capable of storing boron, no studies have been published about Streptomyces or Lentzea genera's capacity to tolerate high boron concentrations, or about their metabolic capacities in boron contaminated environments. The results of this research show the isolation and molecular characterization of eight strains belonging to the actinobacteria phylum collected from different soils contaminated with high boron concentration in Salta state. The boron tolerance assays, which show that three of the strains were able to tolerate up 60-80 mM boron, demonstrate the potential capability of this group of bacteria to grow and maybe to remove boron from the environment. They appear to be promising, considering that these microorganisms are infrequent pathogens, are metabolically versatile and many Streptomyces can synthesize boron containing metabolites.

  4. Dose point kernel for boron-11 decay and the cellular S values in boron neutron capture therapy.

    Science.gov (United States)

    Ma, Yunzhi; Geng, JinPeng; Gao, Song; Bao, Shanglian

    2006-12-01

    The study of the radiobiology of boron neutron capture therapy is based on the cellular level dosimetry of boron-10's thermal neutron capture reaction 10B(n,alpha)7Li, in which one 1.47 MeV helium-4 ion and one 0.84 MeV lithium-7 ion are spawned. Because of the chemical preference of boron-10 carrier molecules, the dose is heterogeneously distributed in cells. In the present work, the (scaled) dose point kernel of boron-11 decay, called 11B-DPK, was calculated by GEANT4 Monte Carlo simulation code. The DPK curve drops suddenly at the radius of 4.26 microm, the continuous slowing down approximation (CSDA) range of a lithium-7 ion. Then, after a slight ascending, the curve decreases to near zero when the radius goes beyond 8.20 microm, which is the CSDA range of a 1.47 MeV helium-4 ion. With the DPK data, S values for nuclei and cells with the boron-10 on the cell surface are calculated for different combinations of cell and nucleus sizes. The S value for a cell radius of 10 microm and a nucleus radius of 5 microm is slightly larger than the value published by Tung et al. [Appl. Radiat. Isot. 61, 739-743 (2004)]. This result is potentially more accurate than the published value since it includes the contribution of a lithium-7 ion as well as the alpha particle.

  5. 钴和硼的联合测定%Determination of cobalt and boron in cobalt-boron complex

    Institute of Scientific and Technical Information of China (English)

    李祖光; 高云芳; 高志祥

    2001-01-01

    建立了一种联合测定硼酰化钴中钴含量和硼含量的分析方法。采用二甲酚橙为指示剂,EDTA为滴定剂测钴时,加入孔雀绿作衬托剂,可明显改善滴定终点。采用甘露醇强化硼酸滴定硼时, 以EDTA为掩蔽剂,可消除二价钴对硼分析的干扰;改用溴甲酚绿-甲基红-酚酞三元混合指示剂作为测定硼的指示剂,使滴定终点灵敏,准确。%A method of determination cobalt and boron in boron-containing fine organic chemicals was described. Cobalt was titrated at pH 5~6 in hexamethylenetramine medium using xylenol orange and malachite green as indicator.A mixed indicator composed of bromocresol green, methyl red and phenalphthalein was used as indicator in titration of boron after the inteterience of cobalt was masked by EDTA.It is simple and fast and has been satisfactorily used for the determination of cobalt and boron in the rubber adhesion promoter, such as cobalt-boron complex.

  6. Hydrogen-induced boron passivation in Cz Si

    Energy Technology Data Exchange (ETDEWEB)

    Castaldini, A.; Cavalcoli, D.; Cavallini, A. [INFM and Physics Department, Viale Berti Pichat 6/2, 40137 Bologna (Italy); Susi, E. [CNR-LAMEL, Via Gobetti 101, 40129 Bologna (Italy)

    2002-11-01

    Acceptor deactivation in the near-surface region of as-grown, boron-doped Si wafers was detected by in-depth profiles of the free-carrier density obtained by capacitance-voltage measurements. As this deactivation was only observed in wafers subjected to the standard cleaning procedures used in Si manufacturing, we ascribed it to boron passivation by an impurity introduced during the cleaning process. From the study of the free-carrier reactivation kinetics and of the diffusion behaviour of boron-impurity complexes, we have concluded that the impurity is possibly related to hydrogen introduced during the cleaning treatments. The characteristics of the deep level associated with this impurity have been analysed by deep-level transient spectroscopy. (orig.)

  7. Analytical and experimental research into boron dilution events

    Energy Technology Data Exchange (ETDEWEB)

    Teschendorff, V. [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) mbH, Garching (Germany); Umminger, K. [Framatome ANP GmbH, Erlengen (Germany); Weiss, F.P. [Forschungszentrum Rossendorf e.V. (FZR) (Germany). Inst. fuer Sicherheitsforschung

    2001-07-01

    Research activities are being performed in Germany with the aim to improve and validate the methods for predicting boron dilution events. Integral experiments in the PKL test facility investigate the thermal-hydraulic system behaviour in a wide range of conditions. The latest test program comprises small break LOCA scenarios with boron dilution. For these tests, boric acid in the coolant is used together with an advanced instrumentation that can measure boron concentration during the transient. Mixing processes in the downcomer and lower plenum under the influence of various loop operating conditions are studied in the transparent 1:5 ROCOM four-loop test facility equipped with advanced wire mesh sensors to follow the transient concentration patterns. Analytical R and D activities include further model development and validation in the thermal-hydraulic system code ATHLET as well as assessment calculations for detailed three-dimensional mixing in the reactor pressure vessel with CFD-codes. (authors)

  8. PGNAA of human arthritic synovium for boron neutron capture synovectomy

    Energy Technology Data Exchange (ETDEWEB)

    Binello, E.; Yanch, J.C. [Massashucetts Institute of Technology, Cambridge, MA (United States); Shortkroff, S. [Brigham and Women`s Hospital, Boston, MA (United States)

    1997-12-01

    Boron neutron capture synovectomy (BNCS), is a proposed new therapy modality for the treatment of rheumatoid arthritis, an autoimmune disease afflicting the joints. The synovium, which is the membrane lining the joint, becomes inflamed and represents the target tissue for therapy. When a joint is unresponsive to drug treatment, physical removal of the synovium, termed synovectomy, becomes necessary. Existing options include surgery and radiation synovectomy. BNCS has advantages over these options in that it is noninvasive and does not require the administration of radioactive substances. Previous studies have shown that the uptake of {sup 10}B by human arthritic synovium ex vivo is high, ranging from 194 to 545 ppm with an unenriched boron compound. While tissue samples remain viable up to 1 week, ex vivo conditions do not accurately reflect those in vivo. This paper presents results from experiments assessing the washout of boron from the tissue and examines the implications for in vivo studies.

  9. Experimental core electron density of cubic boron nitride

    DEFF Research Database (Denmark)

    Wahlberg, Nanna; Bindzus, Niels; Bjerg, Lasse;

    Experimental core electron density of cubic boron nitride Nanna Wahlberg*, Niels Bindzus*, Lasse Bjerg*, Jacob Becker*, and Bo B. Iversen* *Aarhus University, Department of Chemistry, CMC, Langelandsgade 140, 8000 Århus, Denmark The resent progress in powder diffraction provides data of quality...... beyond multipolar modeling of the valence density. As was recently shown in a benchmark study of diamond by Bindzus et al.1 The next step is to investigate more complicated chemical bonding motives, to determine the effect of bonding on the core density. Cubic boron nitride2 lends itself as a perfect...... candidate because of its many similarities with diamond: bonding pattern in the extended network structure, hardness, and the quality of the crystallites.3 However, some degree ionic interaction is a part of the bonding in boron nitride, which is not present in diamond. By investigating the core density...

  10. Atomic-Level Understanding of "Asymmetric Twins" in Boron Carbide

    Science.gov (United States)

    Xie, Kelvin Y.; An, Qi; Toksoy, M. Fatih; McCauley, James W.; Haber, Richard A.; Goddard, William A.; Hemker, Kevin J.

    2015-10-01

    Recent observations of planar defects in boron carbide have been shown to deviate from perfect mirror symmetry and are referred to as "asymmetric twins." Here, we demonstrate that these asymmetric twins are really phase boundaries that form in stoichiometric B4C (i.e., B12C3 ) but not in B13C2 . TEM observations and ab initio simulations have been coupled to show that these planar defects result from an interplay of stoichiometry, atomic positioning, icosahedral twinning, and structural hierarchy. The composition of icosahedra in B4C is B11C and translation of the carbon atom from a polar to equatorial site leads to a shift in bonding and a slight distortion of the lattice. No such distortion is observed in boron-rich B13C2 because the icosahedra do not contain carbon. Implications for tailoring boron carbide with stoichiometry and extrapolations to other hierarchical crystalline materials are discussed.

  11. Bosonic Anomalies in Boron-Doped Polycrystalline Diamond

    Science.gov (United States)

    Zhang, Gufei; Samuely, Tomas; Kačmarčík, Jozef; Ekimov, Evgeny A.; Li, Jun; Vanacken, Johan; Szabó, Pavol; Huang, Junwei; Pereira, Paulo J.; Cerbu, Dorin; Moshchalkov, Victor V.

    2016-12-01

    Quantum confinement and coherence effects are considered the cause of many specific features for systems which are generally low dimensional, strongly disordered, and/or situated in the vicinity of the metal-insulator transition. Here, we report on the observation of anomalous resistance peak and specific heat peaks superimposed at the superconducting transition of heavily boron-doped polycrystalline bulk diamond, which is a three-dimensional system situated deep on the metallic side of the boron-doping-driven metal-insulator transition in diamond. The anomalous resistance peak and specific heat peaks are interpreted as a result of confinement and coherence effects in the presence of intrinsic and extrinsic granularity. Our data, obtained for superconducting diamond, provide a reference for understanding the superconductivity in other granular disordered systems. Furthermore, our study brings attention to the significant influence of granular disorder on the physical properties of boron-doped diamond, which is considered a promising candidate for electronics applications.

  12. Ordering of carbon atoms in boron carbide structure

    Energy Technology Data Exchange (ETDEWEB)

    Ponomarev, V. I., E-mail: i2212@yandex.ru; Kovalev, I. D.; Konovalikhin, S. V.; Vershinnikov, V. I. [Russian Academy of Sciences, Institute of Structural Macrokinetics and Materials Science (Russian Federation)

    2013-05-15

    Boron carbide crystals have been obtained in the entire compositional range according to the phase diagram by self-propagating high-temperature synthesis (SHS). Based on the results of X-ray diffraction investigations, the samples were characterized by the unit-cell metric and reflection half-width in the entire range of carbon concentrations. A significant spread in the boron carbide unit-cell parameters for the same carbon content is found in the data in the literature; this spread contradicts the structural concepts for covalent compounds. The SHS samples have not revealed any significant spread in the unit-cell parameters. Structural analysis suggests that the spread of parameters in the literary data is related to the unique process of ordering of carbon atoms in the boron carbide structure.

  13. Subgrains and boron distribution of low carbon bainitic steels

    Institute of Scientific and Technical Information of China (English)

    Xuemin Wang; Bing Cao; Chengjia Shang; Xueyi Liu; Xinlai He

    2005-01-01

    The structure variation of deformed austenite during the relaxation stage after deformation at various temperatures in an Nb-B ultra low carbon bainitic steel and Fe-Ni alloy was studied by the thermo-simulation. Optical microscope and TEM were applied to analyze the microstructure after RPC (Relaxation-precipitation-controlling phase transformation technique) and the evolution of dislocation configuration. The particle tracking autoradiography (PTA) technique, revealing the distribution of boron, was employed to show the change of boron segregation after different relaxation times. The results indicate that during the relaxation stage the recovery occurs in the deformed austenite, the dislocations rearrange and subgrains form. During the subsequent cooling the boron will segregate at the boundaries of subgrains.

  14. Reconstructing Ocean pH with Boron Isotopes in Foraminifera

    Science.gov (United States)

    Foster, Gavin L.; Rae, James W. B.

    2016-06-01

    In order to better understand the effect of CO2 on the Earth system in the future, geologists may look to CO2-induced environmental change in Earth's past. Here we describe how CO2 can be reconstructed using the boron isotopic composition (δ11B) of marine calcium carbonate. We review the chemical principles that underlie the proxy, summarize the available calibration data, and detail how boron isotopes can be used to estimate ocean pH and ultimately atmospheric CO2 in the past. δ11B in a variety of marine carbonates shows a coherent relationship with seawater pH, in broad agreement with simple models for this proxy. Offsets between measured and predicted δ11B may in part be explained by physiological influences, though the exact mechanisms of boron incorporation into carbonate remain unknown. Despite these uncertainties, we demonstrate that δ11B may provide crucial constraints on past ocean acidification and atmospheric CO2.

  15. Multi-layer boron thin-film detectors for neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhehui [Los Alamos National Laboratory; Morris, Christopher L [Los Alamos National Laboratory

    2010-01-01

    Intrinsic efficiencies of the multilayer boron detectors have been examined both theoretically and experimentally. It is shown that due to the charge loss in the boron layers, the practical efficiencies of most multi-layer {sup 10}B detectors are limited up to about 42%, much less than 77% of the 2 bar 2-inch diameter {sup 3}He detectors. It is suggested that the same charge loss mechanism will prevent essentially all substrate-based boron detectors from ever reaching the efficiencies of high-pressure {sup 3}He tubes, independent of the substrate geometry and material composition (including silicon). Meanwhile, the experimental data indicate that the multi-layer approach can increase the efficiencies up to the theoretical limit. Good n/{gamma} discrimination has also achieved using the ionization charnber technique.

  16. Atomic-Level Understanding of "Asymmetric Twins" in Boron Carbide.

    Science.gov (United States)

    Xie, Kelvin Y; An, Qi; Toksoy, M Fatih; McCauley, James W; Haber, Richard A; Goddard, William A; Hemker, Kevin J

    2015-10-23

    Recent observations of planar defects in boron carbide have been shown to deviate from perfect mirror symmetry and are referred to as "asymmetric twins." Here, we demonstrate that these asymmetric twins are really phase boundaries that form in stoichiometric B(4)C (i.e., B(12)C(3)) but not in B(13)C(2). TEM observations and ab initio simulations have been coupled to show that these planar defects result from an interplay of stoichiometry, atomic positioning, icosahedral twinning, and structural hierarchy. The composition of icosahedra in B(4)C is B(11)C and translation of the carbon atom from a polar to equatorial site leads to a shift in bonding and a slight distortion of the lattice. No such distortion is observed in boron-rich B(13)C(2) because the icosahedra do not contain carbon. Implications for tailoring boron carbide with stoichiometry and extrapolations to other hierarchical crystalline materials are discussed.

  17. The local structure of transition metal doped semiconducting boron carbides

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jing; Dowben, P A [Department of Physics and Astronomy and the Nebraska Center for Materials and Nanoscience, Behlen Laboratory of Physics, University of Nebraska-Lincoln, PO Box 880111, Lincoln, NE 68588-0111 (United States); Luo Guangfu; Mei Waining [Department of Physics, University of Nebraska at Omaha, Omaha, NE 68182-0266 (United States); Kizilkaya, Orhan [J. Bennett Johnston Sr. Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Hwy., Baton Rouge LA 70806 (United States); Shepherd, Eric D; Brand, J I [College of Engineering, and the Nebraska Center for Materials and Nanoscience, N209 Walter Scott Engineering Center, 17th and Vine Streets, University of Nebraska-Lincoln, Lincoln, NE 68588-0511 (United States)

    2010-03-03

    Transition metal doped boron carbides produced by plasma enhanced chemical vapour deposition of orthocarborane (closo-1,2-C{sub 2}B{sub 10}H{sub 12}) and 3d metal metallocenes were investigated by performing K-edge extended x-ray absorption fine structure and x-ray absorption near edge structure measurements. The 3d transition metal atom occupies one of the icosahedral boron or carbon atomic sites within the icosahedral cage. Good agreement was obtained between experiment and models for Mn, Fe and Co doping, based on the model structures of two adjoined vertex sharing carborane cages, each containing a transition metal. The local spin configurations of all the 3d transition metal doped boron carbides, Ti through Cu, are compared using cluster and/or icosahedral chain calculations, where the latter have periodic boundary conditions.

  18. On-line DLTS investigations of vacancy related defects in low-temperature electron irradiated, boron-doped Si

    Science.gov (United States)

    Zangenberg, N. R.; Nylandsted Larsen, A.

    2005-02-01

    Vacancy-related defects in Si are explored with deep level transient spectroscopy (DLTS). The measurements are performed on-line on irradiated p-type Si and a new trap with the signature (Epa, σpa) = (0.18 eV, 6.5×10-15 cm2) only present at cryogenic temperatures is studied. Furthermore, the bi-stable boron-vacancy complex is studied and it’s configuration at low temperatures is investigated and found to have the signature (Epa, σpa) = (0.11 eV, 8.2×10-15 cm2).

  19. Boron isotope effect in superconducting MgB2.

    Science.gov (United States)

    Bud'ko, S L; Lapertot, G; Petrovic, C; Cunningham, C E; Anderson, N; Canfield, P C

    2001-02-26

    We report the preparation method of and boron isotope effect for MgB2, a new binary intermetallic superconductor with a remarkably high superconducting transition temperature T(c)(10B) = 40.2 K. Measurements of both temperature dependent magnetization and specific heat reveal a 1.0 K shift in T(c) between Mg11B2 and Mg10B2. Whereas such a high transition temperature might imply exotic coupling mechanisms, the boron isotope effect in MgB2 is consistent with the material being a phonon-mediated BCS superconductor.

  20. Inter-layer potential for hexagonal boron nitride

    Science.gov (United States)

    Leven, Itai; Azuri, Ido; Kronik, Leeor; Hod, Oded

    2014-03-01

    A new interlayer force-field for layered hexagonal boron nitride (h-BN) based structures is presented. The force-field contains three terms representing the interlayer attraction due to dispersive interactions, repulsion due to anisotropic overlaps of electron clouds, and monopolar electrostatic interactions. With appropriate parameterization, the potential is able to simultaneously capture well the binding and lateral sliding energies of planar h-BN based dimer systems as well as the interlayer telescoping and rotation of double walled boron-nitride nanotubes of different crystallographic orientations. The new potential thus allows for the accurate and efficient modeling and simulation of large-scale h-BN based layered structures.

  1. Communication: Water on hexagonal boron nitride from diffusion Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hamdani, Yasmine S.; Ma, Ming; Michaelides, Angelos, E-mail: angelos.michaelides@ucl.ac.uk [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Alfè, Dario [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT (United Kingdom); Lilienfeld, O. Anatole von [Institute of Physical Chemistry and National Center for Computational Design and Discovery of Novel Materials, Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland); Argonne Leadership Computing Facility, Argonne National Laboratories, 9700 S. Cass Avenue Argonne, Lemont, Illinois 60439 (United States)

    2015-05-14

    Despite a recent flurry of experimental and simulation studies, an accurate estimate of the interaction strength of water molecules with hexagonal boron nitride is lacking. Here, we report quantum Monte Carlo results for the adsorption of a water monomer on a periodic hexagonal boron nitride sheet, which yield a water monomer interaction energy of −84 ± 5 meV. We use the results to evaluate the performance of several widely used density functional theory (DFT) exchange correlation functionals and find that they all deviate substantially. Differences in interaction energies between different adsorption sites are however better reproduced by DFT.

  2. Introduction to Neutron Coincidence Counter Design Based on Boron-10

    Energy Technology Data Exchange (ETDEWEB)

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.

    2012-01-22

    The Department of Energy Office of Nonproliferation Policy (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is ultimately to design, build and demonstrate a boron-lined proportional tube based alternative system in the configuration of a coincidence counter. This report, providing background information for this project, is the deliverable under Task 1 of the project.

  3. Superhard Semiconducting Optically Transparent High Pressure Phase of Boron

    Science.gov (United States)

    Zarechnaya, E. Yu.; Dubrovinsky, L.; Dubrovinskaia, N.; Filinchuk, Y.; Chernyshov, D.; Dmitriev, V.; Miyajima, N.; El Goresy, A.; Braun, H. F.; van Smaalen, S.; Kantor, I.; Kantor, A.; Prakapenka, V.; Hanfland, M.; Mikhaylushkin, A. S.; Abrikosov, I. A.; Simak, S. I.

    2009-05-01

    An orthorhombic (space group Pnnm) boron phase was synthesized at pressures above 9 GPa and high temperature, and it was demonstrated to be stable at least up to 30 GPa. The structure, determined by single-crystal x-ray diffraction, consists of B12 icosahedra and B2 dumbbells. The charge density distribution obtained from experimental data and ab initio calculations suggests covalent chemical bonding in this phase. Strong covalent interatomic interactions explain the low compressibility value (bulk modulus is K300=227GPa) and high hardness of high-pressure boron (Vickers hardness HV=58GPa), after diamond the second hardest elemental material.

  4. Boron in Pariette Wetland Sediments, Aquatic Vegetation & Benthic Organisms

    Science.gov (United States)

    Vasudeva, P.; Jones, C. P.; Powelson, D.; Jacobson, A. R.

    2015-12-01

    The Pariette Wetlands are comprised of 20 ponds located in Utah's Uintah Basin. Boron concentration in the Pariette Wetlands have been observed to exceed the total maximum daily limit of 750 µg L-1. Considering water flow in and out of the wetlands, boron is accumulating within the wetlands where it is sorbed to sediments and bioconcentrated by wetland plant and macro invertebrates. Since boron is an avian teratogen, an estimate of boron ingestion exposure is warranted. Samples from 3 of the 23 Pariette Wetland ponds with one pond near the inlet, one near the outlet, and one in the middle were collected. Five sampling points were designated along a 100 m transect of each pond. At each sampling point duplicate (or triplicate) samples of water, sediments, benthic organisms and wetland vegetation were collected. The sediments were collected with a KB-corer and divided at depths of 0-2 cm, 2-7 cm, and 7+ cm from the sediment surface. Sample splits were sent to the USU Bug lab for identification of invertebrate species. Whenever this transect was not intercepting vegetation, 2-3 additional sample sites were identified at the pond within stands of representative vegetation where bird nests are located. The plant parts used for boron analyses will include seeds, shoot and roots of vascular plants, as well as algae or duckweeds skimmed from the surface. Samples were processed within 2 days of collection. Water samples filtered through a 0.45 μ membrane filter were analyzed for DOC, pH and ECe. The dried and washed vegetation samples were ground and stored. The benthic organisms and macro invertebrates were netted at the water surface. The dried samples were weighed, ground and stored. Samples were weighed, oven dried and reweighed. For plant and macro-invertebrate samples, a nitric and hydrogen peroxide digestion procedure is used to dissolve environmentally available elements. The Hot Water extraction and DTPA-Sorbitol extraction were compared to estimate wetland plant

  5. NOVEL SALTS OF GRAPHITE AND A BORON NITRIDE SALT

    Energy Technology Data Exchange (ETDEWEB)

    Bartlett, Neil; Biagioni, R.N.; McQuillan, B.W.; Robertson, A.S.; Thompson, A.C

    1977-12-01

    Graphite is oxidized by O{sub 2}{sup +} AsF{sub 6}{sup -} and by OsF{sub 6} to give first-stage graphite salts C{sub 8}{sup +} MF{sub 6}{sup -} and S{sub 2}O{sub 6}F{sub 2} oxidizes both graphite and boron nitride to yield the salts C{sub 12}{sup +} SO{sub 3}F{sup -} and (BN){sub 4}{sup +} SO{sub 3}F{sup -}, the latter being the first example of a first-stage boron nitride salt.

  6. Influence of Boron doping on micro crystalline silicon growth

    Institute of Scientific and Technical Information of China (English)

    Li Xin-Li; Wang Guo; Chen Yong-Sheng; Yang Shi-E; Gu Jin-Hua; Lu Jing-Xiao; Gao Xiao-Yong; Li Rui; Jiao Yue-Chao; Gao Hai-Bo

    2011-01-01

    Microcrystalline silicon (Ftc-Si:H) thin films with and without boron doping are deposited using the radio-frequency plasmsrenhanced chemical vapour deposition method. The surface roughness evolutions of the silicon thin films are investigated using ex situ spectroscopic ellipsometry and an atomic force microscope. It is shown that the growth exponent β and the roughness exponent a are about 0.369 and 0.95 for the undoped thin film,respectively. Whereas,for the boron-doped pc-Si:H thin film,βincreases to 0.534 and a decreases to 0.46 due to the shadowing effect.

  7. Design of multidirectional neutron beams for boron neutron capture synovectomy

    Energy Technology Data Exchange (ETDEWEB)

    Gierga, D.P.; Yanch, J.C. [Massachusetts Institute of Technology, Cambridge, MA (United States); Shefer, R.E. [Newton Scientific, Inc., Cambridge, MA (United States)

    1997-12-01

    Boron neutron capture synovectomy (BNCS) is a potential application of the {sup 10}B(n, a) {sup 7}Li reaction for the treatment of rheumatoid arthritis. The target of therapy is the synovial membrane. Rheumatoid synovium is greatly inflamed and is the source of the discomfort and disability associated with the disease. The BNCS proposes to destroy the synovium by first injecting a boron-labeled compound into the joint space and then irradiating the joint with a neutron beam. This study discusses the design of a multidirectional neutron beam for BNCS.

  8. Optical phonon modes in rhombohedral boron monosulfide under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Cherednichenko, Kirill A. [Synchrotron SOLEIL, 91192 Gif-sur-Yvette (France); IMPMC, UPMC Sorbonne Universités, CNRS UMR 7590, 75005 Paris (France); LSPM–CNRS, Université Paris Nord, 93430 Villetaneuse (France); Sokolov, Petr S.; Solozhenko, Vladimir L., E-mail: vladimir.solozhenko@univ-paris13.fr [LSPM–CNRS, Université Paris Nord, 93430 Villetaneuse (France); Kalinko, Aleksandr [Synchrotron SOLEIL, 91192 Gif-sur-Yvette (France); Institute of Solid State Physics, University of Latvia, LV-1063 Riga (Latvia); Le Godec, Yann; Polian, Alain [IMPMC, UPMC Sorbonne Universités, CNRS UMR 7590, 75005 Paris (France); Itié, Jean-Paul [Synchrotron SOLEIL, 91192 Gif-sur-Yvette (France)

    2015-05-14

    Raman spectra of rhombohedral boron monosulfide (r-BS) were measured under pressures up to 34 GPa at room temperature. No pressure-induced structural phase transition was observed, while strong pressure shift of Raman bands towards higher wavenumbers has been revealed. IR spectroscopy as a complementary technique has been used in order to completely describe the phonon modes of r-BS. All experimentally observed bands have been compared with theoretically calculated ones and modes assignment has been performed. r-BS enriched by {sup 10}B isotope was synthesized, and the effect of boron isotopic substitution on Raman spectra was observed and analyzed.

  9. Shock-induced localized amorphization in boron carbide.

    Science.gov (United States)

    Chen, Mingwei; McCauley, James W; Hemker, Kevin J

    2003-03-01

    High-resolution electron microscope observations of shock-loaded boron carbide have revealed the formation of nanoscale intragranular amorphous bands that occur parallel to specific crystallographic planes and contiguously with apparent cleaved fracture surfaces. This damage mechanism explains the measured, but not previously understood, decrease in the ballistic performance of boron carbide at high impact rates and pressures. The formation of these amorphous bands is also an example of how shock loading can result in the synthesis of novel structures and materials with substantially altered properties.

  10. Are there bipolarons in icosahedral boron-rich solids?

    Science.gov (United States)

    Werheit, H

    2007-05-01

    The charge transport of boron carbide, often incorrectly denoted as B(4)C, has been controversially discussed. It is shown that the bipolaron hypothesis is not compatible with numerous experimental results. In particular, the determined real microstructure of boron carbide and its related electronic properties disprove several assumptions, which are fundamental to the bipolaron hypothesis. In contrast, the actual energy band scheme derived mainly from optical investigations is confirmed by careful evaluation of the high-temperature electrical conductivity, and allows a consistent description at most of the experimental results.

  11. Boronic acid-based autoligation of nucleic acids

    DEFF Research Database (Denmark)

    Barbeyron, R.; Vasseur, J.-J.; Smietana, M.;

    2013-01-01

    Abstract: The development of synthetic systems displaying dynamic and adaptive characteristics is a formidable challenge with wide applications from biotechnology to therapeutics. Recently, we described a dynamic and programmable nucleic acid-based system relying on the formation of reversible...... boronate internucleosidic linkages. The DNA- or RNA-templated system comprises a 5′-ended boronic acid probe connecting a 3′-ended ribonucleosidic oligonucleotide partner. To explore the dominant factors that control the reversible linkage, we synthesized a series of 3′-end modified ribonucleotidic strands...

  12. Metallogenic Model and Prospecting Indicators of the Boron Deposits in East Liaoning Area

    Institute of Scientific and Technical Information of China (English)

    Qu Hongxiang; Zhang Guoren; Li Xiandong; Chen Shuliang; Yang Zhongzhu; Wang Zhongjiang

    2001-01-01

    The Paleoproterozoic boron deposits in east Liaoning occur in Mg- rich marble of Li' eryu Formation of Liaohe group. The mineralization was controlled by stratigraphic lithology. The volcano ~ sedimentation is the material base of ore-formation. Boron mainly derived from volcanic source. Boron in Li' eryu formation was activated and transferred by migmatization and then deposited into ore when metasomatism occurrs in Mg - rich marble. Structural deformation reconstructed the boron ore bodies. Meanwhile, ore - bearing hyd~othermal solution produced by structural deformation and remetasomated the host - ore rocks or filled in fissure of ore. Boron deposit is a stratabound deposit, which formed by migmatization and structural deformation mineralization.

  13. Boronated unnatural cyclic amino acids as potential delivery agents for neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Kabalka, George W.; Shaikh, Aarif L. [Departments of Radiology and Chemistry, University of Tennessee, Knoxville, TN (United States); Barth, Rolf F.; Huo Tianyao; Yang Weilian [Department of Pathology, Ohio State University, Columbus, OH (United States); Gordnier, Pamela M. [Department of Biomedical Engineering and Cornell SIMS Laboratory, Cornell University, Ithaca, NY (United States); Chandra, Subhash, E-mail: sc40@cornell.edu [Department of Biomedical Engineering and Cornell SIMS Laboratory, Cornell University, Ithaca, NY (United States)

    2011-12-15

    Boron delivery characteristics of cis and trans isomers of a boronated unnatural amino acid, 1-amino-3-boronocyclopentanecarboxylic acid (ABCPC) were tested in the B16 mouse model for human melanoma. Both ABCPC isomers delivered comparable boron to B16 melanoma tumor cells as L-p-boronophenylalanine (BPA). Secondary ion mass spectrometry (SIMS) analysis revealed the presence of boron throughout the tumor from these compounds, and a near homogeneous distribution between the nucleus and cytoplasm of B16 cells grown in vitro. These encouraging observations support further studies of these new boron carriers in BNCT.

  14. The electrical properties of sulfur-implanted cubic boron nitride thin films

    Institute of Scientific and Technical Information of China (English)

    Deng Jin-Xiang; Qin Yang; Kong Le; Yang Xue-Liang; Li Ting; Zhao Wei-Ping; Yang Ping

    2012-01-01

    Cubic boron nitride (c-BN) thin films are deposited on p-type Si wafers using radio frequency (RF) sputtering and then doped by implanting S ions.The implantation energy of the ions is 19 keV,and the implantation dose is between 1015 ions/cm2 and 1016 ions/cm2.The doped c-BN thin films are then annealed at a temperature between 400 ℃ and 800 ℃.The results show that the surface resistivity of doped and annealed c-BN thin films is lowered by two to three orders,and the activation energy of c-BN thin films is 0.18 eV.

  15. Impact of boron on the step-free area formation on Si(111) mesa structures

    Energy Technology Data Exchange (ETDEWEB)

    Roy Chaudhuri, Ayan, E-mail: chaudhuri@mbe.uni-hannover.de; Osten, H. J.; Fissel, A. [Institute of Electronic Materials and Devices, Leibniz University of Hannover, Schneiderberg 32, D-30167 Hannover (Germany)

    2015-12-28

    We report about the influence of boron (B) on surface morphology of Si layers grown by molecular beam epitaxy on Si(111) mesas. Dimension of step-free mesa areas is reduced in comparison to pristine Si and scales with the B-coverage. This can be explained by a reduced mass transport on the Si surface in the presence of B-induced √3 × √3 surface structure which is due to a reduced Si equilibrium free adatom density. We demonstrate that a suitable combination of initial B coverage and Si layer thickness results in large step free areas and B doping concentration up to 4 × 10{sup 18 }cm{sup −3}.

  16. Influence of boron doping on mechanical and tribological properties in multilayer CVD-diamond coating systems

    Indian Academy of Sciences (India)

    SAJAD HUSSAIN DIN; M A SHAH; N A SHEIKH; K A NAJAR; K RAMASUBRAMANIAN; S BALAJI; M S RAMACHANDRA RAO

    2016-12-01

    Titanium alloy (Ti6Al4V) substrates were deposited with smooth multilayer coatings, by hot filament chemical vapour deposition technique. The effect of boron doping on lattice parameter, residual stresses, hardness and coefficient of friction in multilayer-diamond coating system was studied. The frictional behaviour of the coatings was studied using a ball-on-disc micro-tribometer by sliding the coated samples of titanium alloy (Ti6Al4V) substrates against alumina (Al$_2$O$_3$) balls, and increasing normal load from 1 to 10N. The average friction coefficient decreased from 0.36 to 0.29 for undoped multilayer-diamond coating system and from 0.33 to 0.18 for borondoped (BD) multilayer-diamond coating system. The average indentation depths for undoped and BD multilayerdiamond coating systems were found to be equal to $\\sim$58 and $\\sim$65 nm, respectively, and their hardness values were 60 and 55~GPa, respectively.

  17. Protodeboronation of ortho- and para-phenol boronic acids and application to ortho and meta functionalization of phenols using boronic acids as blocking and directing groups.

    Science.gov (United States)

    Lee, Chun-Young; Ahn, Su-Jin; Cheon, Cheol-Hong

    2013-12-06

    The first metal-free thermal protodeboronation of ortho- and para-phenol boronic acids in DMSO was developed. The protodeboronation was successfully applied to the synthesis of ortho- and meta-functionalized phenols using the boronic acid moiety as a blocking group and a directing group, respectively. Mechanistic studies suggested that this protodeboronation proceeds through the coordination of water to the boron atom followed by σ-bond metathesis.

  18. INFLUENCE RESEARCH OF COLD PLASTIC DEFORMATION ON DIFFUSION SATURATION PROCESS BY CARBON AND BORON OF THE LOW-CARBON AND BORON-CONTAINING ALLOYS

    Directory of Open Access Journals (Sweden)

    N. Yu. Filonenko

    2010-06-01

    Full Text Available This work is devoted to the study of influence of cold prestrain with degree of deformation within the range 0…40 % on diffusion saturation with boron and carbon for low-carbon and boron steels. It is determined that the plastic prestrain with degree of deformation 20 % at temperature 750 °С for the low-carbon steel promote increasing of boron-cementation layer thickness by 25 % and microhardness of perlite layer by 20 %.

  19. The major facilitator superfamily transporter Knq1p modulates boron homeostasis in Kluyveromyces lactis.

    Science.gov (United States)

    Svrbicka, Alexandra; Toth Hervay, Nora; Gbelska, Yvetta

    2016-03-01

    Boron is an essential micronutrient for living cells, yet its excess causes toxicity. To date, the mechanisms of boron toxicity are poorly understood. Recently, the ScATR1 gene has been identified encoding the main boron efflux pump in Saccharomyces cerevisiae. In this study, we analyzed the ScATR1 ortholog in Kluyveromyces lactis--the KNQ1 gene, to understand whether it participates in boron stress tolerance. We found that the KNQ1 gene, encoding a permease belonging to the major facilitator superfamily, is required for K. lactis boron tolerance. Deletion of the KNQ1 gene led to boron sensitivity and its overexpression increased K. lactis boron tolerance. The KNQ1 expression was induced by boron and the intracellular boron concentration was controlled by Knq1p. The KNQ1 promoter contains two putative binding motifs for the AP-1-like transcription factor KlYap1p playing a central role in oxidative stress defense. Our results indicate that the induction of the KNQ1 expression requires the presence of KlYap1p and that Knq1p like its ortholog ScAtr1p in S. cerevisiae functions as a boron efflux pump providing boron resistance in K. lactis.

  20. Separation and Analysis of Boron Isotope in High Plant by Thermal Ionization Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Qingcai Xu

    2015-01-01

    Full Text Available Knowledge of boron and its isotope in plants is useful to better understand the transposition and translocation of boron within plant, the geochemical behavior in the interface between soil and plant, and the biogeochemical cycle of boron. It is critical to develop a useful method to separate boron from the plant for the geochemical application of boron and its isotope. A method was developed for the extraction of boron in plant sample, whose isotope was determined by thermal ionization mass spectrometry. The results indicated that this method of dry ashing coupled with two-step ion-exchange chromatography is powerful for the separation of boron in plant sample with large amounts of organic matters completely. The ratios of boron isotope composition in those plant tissue samples ranged from -19.45‰ to +28.13‰ (total range: 47.58‰ with a mean value of 2.61±11.76‰ SD. The stem and root isotopic compositions were lower than those in flower and leaf. The molecular mechanism of boron isotope may be responsible for the observed variation of boron isotopic composition and are considered as a useful tool for the better understanding of boron cycling process in the environment and for the signature of living systems.

  1. Raman spectroscopic characterization of the core-rim structure in reaction bonded boron carbide ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Jannotti, Phillip; Subhash, Ghatu, E-mail: subhash@ufl.edu [Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida 32611 (United States); Zheng, James Q.; Halls, Virginia [Program Executive Office—Soldier Protection and Individual Equipment, US Army, Fort Belvoir, Virginia 22060 (United States); Karandikar, Prashant G.; Salamone, S.; Aghajanian, Michael K. [M-Cubed Technologies, Inc., Newark, Delaware 19711 (United States)

    2015-01-26

    Raman spectroscopy was used to characterize the microstructure of reaction bonded boron carbide ceramics. Compositional and structural gradation in the silicon-doped boron carbide phase (rim), which develops around the parent boron carbide region (core) due to the reaction between silicon and boron carbide, was evaluated using changes in Raman peak position and intensity. Peak shifting and intensity variation from the core to the rim region was attributed to changes in the boron carbide crystal structure based on experimental Raman observations and ab initio calculations reported in literature. The results were consistent with compositional analysis determined by energy dispersive spectroscopy. The Raman analysis revealed the substitution of silicon atoms first into the linear 3-atom chain, and then into icosahedral units of the boron carbide structure. Thus, micro-Raman spectroscopy provided a non-destructive means of identifying the preferential positions of Si atoms in the boron carbide lattice.

  2. Challenges and Opportunities for the Application of Boron Clusters in Drug Design.

    Science.gov (United States)

    Leśnikowski, Zbigniew J

    2016-09-08

    There are two branches in boron medicinal chemistry: the first focuses on single boron atom compounds, and the second utilizes boron clusters. Boron clusters and their heteroatom counterparts belong to the family of cage compounds. A subset of this extensive class of compounds includes dicarbadodecaboranes, which have the general formula C2B10H12, and their metal biscarboranyl complexes, metallacarboranes, with the formula [M(C2B10H12)2(-2)]. The unique properties of boron clusters have resulted in their utilization in applications such as in pharmacophores, as scaffolds in molecular construction, and as modulators of bioactive compounds. This Perspective presents an overview of the properties of boron clusters that are pertinent for drug discovery, recent applications in the design of various classes of drugs, and the potential use of boron clusters in the construction of new pharmaceuticals.

  3. Effects of strontium and boron interactions in Al-7Si alloys

    Directory of Open Access Journals (Sweden)

    Chen Xiang

    2010-11-01

    Full Text Available Effects of boron and strontium combined treatment on the microstructure of hypoeutectic Al-7Si alloy have been studied. Experimental results show that strontium has no significant effect on the grain refinement efficiency of boron and the eutectic silicon modification efficiency is not only related to the strontium content but also related to the boron content in the Al-7Si alloy melt. There is a negative interaction between boron and strontium that results in the formation of a strontium-boron-aluminum containing compound, which reduces the effective strontium level and decreases the eutectic silicon modification efficiency substantially. The refinement and modification mechanisms remain unchanged after the combined addition of strontium and boron. Based on the experimental results, a model for assessing the modification level in the Al-Si alloy melts after combined addition of boron and strontium was presented.

  4. Biodistribution of Amine-Amide Chlorin e6 Derivative Conjugate with a Boron Nanoparticle for Boron Neutron-Capture Therapy

    OpenAIRE

    А.B. Volovetsky; N.Y. Shilyagina; V.V. Dudenkova; S.О. Pasynkova; М.А. Grin; А.F. Mironov; А.V. Feofanov; I.V. Balalaeva; А.V. Maslennikova

    2016-01-01

    The aim of the investigation was to study the biodistribution of amino-amide chlorin e6 derivative conjugate with cobalt bis-dicarbollide as a potential boron transporter for the tasks of boron neutron-capture therapy. Materials and Methods. The experiments were carried out on Balb/c mice with induced murine colon carcinoma CT-26. Amino-amide chlorin e6 derivative conjugate with cobalt bis-dicarbollide was administered intravenously, the dose being 5 and 10 mg/kg body mass. The sampling for m...

  5. Biodistribution of boron after intravenous 4-dihydroxyborylphenylalanine-fructose (BPA-F) infusion in meningioma and schwannoma patients: A feasibility study for boron neutron capture therapy.

    Science.gov (United States)

    Kulvik, Martti; Kallio, Merja; Laakso, Juha; Vähätalo, Jyrki; Hermans, Raine; Järviluoma, Eija; Paetau, Anders; Rasilainen, Merja; Ruokonen, Inkeri; Seppälä, Matti; Jääskeläinen, Juha

    2015-12-01

    We studied the uptake of boron after 100 mg/kg BPA infusion in three meningioma and five schwannoma patients as a pre-BNCT feasibility study. With average tumour-to-whole blood boron concentrations of 2.5, we discuss why BNCT could, and probably should, be developed to treat severe forms of the studied tumours. However, analysing 72 tumour and 250 blood samples yielded another finding: the plasma-to-whole blood boron concentrations varied with time, suggesting that the assumed constant boron ratio of 1:1 between normal brain tissue and whole blood deserves re-assessment.

  6. Biodistribution of the boron carriers boronophenylalanine (BPA) and/or decahydrodecaborate (GB-10) for Boron Neutron Capture Therapy (BNCT) in an experimental model of lung metastases

    Energy Technology Data Exchange (ETDEWEB)

    D.W. Nigg; Various Others

    2014-06-01

    BNCT was proposed for the treatment of diffuse, non-resectable tumors in the lung. We performed boron biodistribution studies with 5 administration protocols employing the boron carriers BPA and/or GB-10 in an experimental model of disseminated lung metastases in rats. All 5 protocols were non-toxic and showed preferential tumor boron uptake versus lung. Absolute tumor boron concentration values were therapeutically useful (25–76 ppm) for 3 protocols. Dosimetric calculations indicate that BNCT at RA-3 would be potentially therapeutic without exceeding radiotolerance in the lung.

  7. Boron neutron capture therapy (BNCT): implications of neutron beam and boron compound characteristics.

    Science.gov (United States)

    Wheeler, F J; Nigg, D W; Capala, J; Watkins, P R; Vroegindeweij, C; Auterinen, I; Seppälä, T; Bleuel, D

    1999-07-01

    The potential efficacy of boron neutron capture therapy (BNCT) for malignant glioma is a significant function of epithermal-neutron beam biophysical characteristics as well as boron compound biodistribution characteristics. Monte Carlo analyses were performed to evaluate the relative significance of these factors on theoretical tumor control using a standard model. The existing, well-characterized epithermal-neutron sources at the Brookhaven Medical Research Reactor (BMRR), the Petten High Flux Reactor (HFR), and the Finnish Research Reactor (FiR-1) were compared. Results for a realistic accelerator design by the E. O. Lawrence Berkeley National Laboratory (LBL) are also compared. Also the characteristics of the compound p-Boronophenylaline Fructose (BPA-F) and a hypothetical next-generation compound were used in a comparison of the BMRR and a hypothetical improved reactor. All components of dose induced by an external epithermal-neutron beam fall off quite rapidly with depth in tissue. Delivery of dose to greater depths is limited by the healthy-tissue tolerance and a reduction in the hydrogen-recoil and incident gamma dose allow for longer irradiation and greater dose at a depth. Dose at depth can also be increased with a beam that has higher neutron energy (without too high a recoil dose) and a more forward peaked angular distribution. Of the existing facilities, the FiR-1 beam has the better quality (lower hydrogen-recoil and incident gamma dose) and a penetrating neutron spectrum and was found to deliver a higher value of Tumor Control Probability (TCP) than other existing beams at shallow depth. The greater forwardness and penetration of the HFR the FiR-1 at greater depths. The hypothetical reactor and accelerator beams outperform at both shallow and greater depths. In all cases, the hypothetical compound provides a significant improvement in efficacy but it is shown that the full benefit of improved compound is not realized until the neutron beam is fully

  8. Graphitized boron-doped carbon foams: Performance as anodes in lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Elena; Camean, Ignacio; Garcia, Roberto [Instituto Nacional del Carbon (CSIC), C/Francisco Pintado Fe 26, 33011 Oviedo (Spain); Garcia, Ana B., E-mail: anabgs@incar.csic.es [Instituto Nacional del Carbon (CSIC), C/Francisco Pintado Fe 26, 33011 Oviedo (Spain)

    2011-05-30

    Highlights: > Because of the catalytic effect of boron, graphite-like foams were prepared. > The presence of substitutional boron in carbon foams improves their anodic performance. > The graphitized boron-doped foams provide reversible capacities of 310 mA h g{sup -1}. - Abstract: The electrochemical performance as potential anodes in lithium-ion batteries of several boron-doped and non-doped graphitic foams with different degree of structural order was investigated by galvanostatic cycling. The boron-doped foams were prepared by the co-pyrolysis of a coal and two boron sources (boron oxide and a borane-pyridine complex), followed by heat treatment in the 2400-2800 deg. C temperature interval. The extent of the graphitization process of the carbon foams depends on boron concentration and source. Because of the catalytic effect of boron, lightweight graphite-like foams were prepared. Boron in the foams was found to be present as carbide (B{sub 4}C), in substitutional positions in the carbon lattice (B-C), bonded to nitrogen (B-N) and forming clusters. Larger reversible lithium storage capacities with values up to {approx}310 mA h g{sup -1} were achieved by using the boron oxide-based carbon foams. Moreover, since the electrochemical anodic performance of these boron-doped foams with different degree of structural order is similar, the beneficial effect of the presence of the B-C boron phase was inferred. However, the bonding of boron with nitrogen in the pyridine borane-based has a negative effect on lithium intercalation.

  9. Understanding boron through size-selected clusters: structure, chemical bonding, and fluxionality.

    Science.gov (United States)

    Sergeeva, Alina P; Popov, Ivan A; Piazza, Zachary A; Li, Wei-Li; Romanescu, Constantin; Wang, Lai-Sheng; Boldyrev, Alexander I

    2014-04-15

    Boron is an interesting element with unusual polymorphism. While three-dimensional (3D) structural motifs are prevalent in bulk boron, atomic boron clusters are found to have planar or quasi-planar structures, stabilized by localized two-center-two-electron (2c-2e) σ bonds on the periphery and delocalized multicenter-two-electron (nc-2e) bonds in both σ and π frameworks. Electron delocalization is a result of boron's electron deficiency and leads to fluxional behavior, which has been observed in B13(+) and B19(-). A unique capability of the in-plane rotation of the inner atoms against the periphery of the cluster in a chosen direction by employing circularly polarized infrared radiation has been suggested. Such fluxional behaviors in boron clusters are interesting and have been proposed as molecular Wankel motors. The concepts of aromaticity and antiaromaticity have been extended beyond organic chemistry to planar boron clusters. The validity of these concepts in understanding the electronic structures of boron clusters is evident in the striking similarities of the π-systems of planar boron clusters to those of polycyclic aromatic hydrocarbons, such as benzene, naphthalene, coronene, anthracene, or phenanthrene. Chemical bonding models developed for boron clusters not only allowed the rationalization of the stability of boron clusters but also lead to the design of novel metal-centered boron wheels with a record-setting planar coordination number of 10. The unprecedented highly coordinated borometallic molecular wheels provide insights into the interactions between transition metals and boron and expand the frontier of boron chemistry. Another interesting feature discovered through cluster studies is boron transmutation. Even though it is well-known that B(-), formed by adding one electron to boron, is isoelectronic to carbon, cluster studies have considerably expanded the possibilities of new structures and new materials using the B(-)/C analogy. It is

  10. Boronate Derivatives of Functionally Diverse Catechols: Stability Studies

    Directory of Open Access Journals (Sweden)

    Kamal Aziz Ketuly

    2010-03-01

    Full Text Available Benzeneboronate of catecholic carboxyl methyl esters, N-acetyldopamine, coumarin and catechol estrogens were prepared as crystalline derivatives in high yield. Related catechol compounds with extra polar functional group(s (OH, NH2 do not form or only partially form unstable cyclic boronate derivatives.

  11. Study of boron implantation in Ag-Si layer structures

    Energy Technology Data Exchange (ETDEWEB)

    Pelikan, L. (Ceske Vysoke Uceni Technicke, Prague (Czechoslovakia). Fakulta Elektrotechnicka); Rybka, V.; Krejci, P. (Tesla, Prague (Czechoslovakia). Vyzkumny Ustav pro Sdelovaci Techniku); Hnatowicz, V.; Kvitek, J. (Ustav Jaderneho Vyzkumu CSKAE, Rez (Czechoslovakia))

    1982-07-16

    The implanted boron depth profiles in samples comprising Si wafers covered with Ag films of various thicknesses are determined experimentally as well as by Monte-Carlo simulation. A complex shape of depth profiles is revealed, which is well reproduced by the calculation.

  12. Lateral boron distribution in polycrystalline SiC source materials

    DEFF Research Database (Denmark)

    Linnarsson, M. K.; Kaiser, M.; Liljedahl, R.

    2013-01-01

    Polycrystalline SiC containing boron and nitrogen are used in growth of fluorescent SiC for white LEDs. Two types of doped polycrystalline SiC have been studied in detail with secondary ion mass spectrometry: sintered SiC and poly-SiC prepared by sublimation in a physical vapor transport setup...

  13. Neutron beam monitor based on a boron-coated GEM

    Institute of Scientific and Technical Information of China (English)

    周健荣; 李仪; 孙志嘉; 刘贲; 王艳凤; 杨桂安; 周良; 许虹; 董静; 杨雷

    2011-01-01

    A new thermal neutron beam monitor with a Gas Electron Multiplier (GEM) is developed to meet the needs of the next generation of neutron facilities. A prototype chamber has been constructed with two 100 mm×100 mm GEM foils. Enriched boron-10 is coated on

  14. Temperature admittance spectroscopy of boron doped chemical vapor deposition diamond

    Energy Technology Data Exchange (ETDEWEB)

    Zubkov, V. I., E-mail: VZubkovspb@mail.ru; Kucherova, O. V.; Zubkova, A. V.; Ilyin, V. A.; Afanas' ev, A. V. [St. Petersburg State Electrotechnical University (LETI), Professor Popov Street 5, 197376 St. Petersburg (Russian Federation); Bogdanov, S. A.; Vikharev, A. L. [Institute of Applied Physics of the Russian Academy of Sciences, Ul' yanov Street 46, 603950 Nizhny Novgorod (Russian Federation); Butler, J. E. [St. Petersburg State Electrotechnical University (LETI), Professor Popov Street 5, 197376 St. Petersburg (Russian Federation); Institute of Applied Physics of the Russian Academy of Sciences, Ul' yanov Street 46, 603950 Nizhny Novgorod (Russian Federation); National Museum of Natural History (NMNH), P.O. Box 37012 Smithsonian Inst., Washington, D.C. 20013-7012 (United States)

    2015-10-14

    Precision admittance spectroscopy measurements over wide temperature and frequency ranges were carried out for chemical vapor deposition epitaxial diamond samples doped with various concentrations of boron. It was found that the experimentally detected boron activation energy in the samples decreased from 314 meV down to 101 meV with an increase of B/C ratio from 600 to 18000 ppm in the gas reactants. For the heavily doped samples, a transition from thermally activated valence band conduction to hopping within the impurity band (with apparent activation energy 20 meV) was detected at temperatures 120–150 K. Numerical simulation was used to estimate the impurity DOS broadening. Accurate determination of continuously altering activation energy, which takes place during the transformation of conduction mechanisms, was proposed by numerical differentiation of the Arrhenius plot. With increase of boron doping level the gradual decreasing of capture cross section from 3 × 10{sup −13} down to 2 × 10{sup −17} cm{sup 2} was noticed. Moreover, for the hopping conduction the capture cross section becomes 4 orders of magnitude less (∼2 × 10{sup −20} cm{sup 2}). At T > T{sub room} in doped samples the birth of the second conductance peak was observed. We attribute it to a defect, related to the boron doping of the material.

  15. Early detection of deteriorations affecting neutrons boron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Domenech, T.; Hamrita, H.; Normand, S. [CEA, LIST, Laboratoire Capteur et Architectures Electroniques, F-91191 Gif/Yvette (France); Daviaud, J. P. [EDF, DPN, 1 place Pleyel, 93 282 Saint Denis Cedex (France); Laroche, M. [EDF, SEPTEN, 12-14 rue Dutrievoz, 69628 Villeurbanne Cedex (France)

    2011-07-01

    The objective of these studies is to design and to industrialize a new device taking back the features of the actual system of control of boron detectors and updating them by adding some analysis of the pulses shapes for predictive maintenance. (authors)

  16. Effect of factors on the extraction of boron from slags

    Science.gov (United States)

    Zhang, Peixin; Sui, Zhitong

    1995-04-01

    The effects of slag composition, additive agent, and heat treatment on the crystal morphologies, the crystallization behavior, and the efficiency of extraction of boron (EEB) from slags were investigated by chemical analysis, polarization microscope, and X-ray diffraction (XRD) as well as differential thermal analysis (DTA). The EEB varied with the slag composition. The farther the slag composition deviated from the line between 2MgO · B2O3 and 2MgO · SiO2 in the MgO-B2O3-SiO2 system, the lower the EEB. The EEB was directly related to the precipitating characteristics of the boron component in the slags. The EEB was high if the boron component existed in the form of a crystalline phase, otherwise the EEB was low when boron was in the form of an amorphous phase. The EEB from MgO-Al2O3-CaO-B2O3-SiO2 slag varied with the temperature of heat treatment; the highest EEB appeared at 1100 °C. The EEB and the crystallinities were increased by addition of TiO2 and MOx (M = Mg, Ca, Fe, Si). The effect of MOx was more notable than that of TiO2.

  17. Analysis of boron dilution in a four-loop PWR

    Energy Technology Data Exchange (ETDEWEB)

    Sun, J.G.; Sha, W.T. [Argonne National Lab., IL (United States)

    1995-03-01

    Thermal mixing and boron dilution in a pressurized water reactor were analyzed with COMMIX codes. The reactor system was the four-loop Zion reactor. Two boron dilution scenarios were analyzed. In the first scenario, the plant is in cold shutdown and the reactor coolant system has just been filled after maintenance on the steam generators. To flush the air out of the steam generator tubes, a reactor coolant pump (RCP) is started, with the water in the pump suction line devoid of boron and at the same temperature as the coolant in the system. In the second scenario, the plant is at hot standby and the reactor coolant system has been heated to operating temperature after a long outage. It is assumed that an RCP is started, with the pump suction line filled with cold unborated water, forcing a slug of diluted coolant down the downcomer and subsequently through the reactor core. The subsequent transient thermal mixing and boron dilution that would occur in the reactor system is simulated for these two scenarios. The reactivity insertion rate and the total reactivity are evaluated and a sensitivity study is performed to assess the accuracy of the numerical modeling of the geometry of the reactor coolant system.

  18. Analysis of boron dilution in a four-loop PWR

    Energy Technology Data Exchange (ETDEWEB)

    Sun, J.G.; Sha, W.T.

    1995-12-31

    Thermal mixing and boron dilution in a pressurized water reactor were analyzed with COMMIX codes. The reactor system was the four loop Zion reactor. Two boron dilution scenarios were analyzed. In the first scenario, the plant is in cold shutdown and the reactor coolant system has just been filled after maintenance on the steam generators. To flush the air out of the steam generator tubes, a reactor coolant pump (RCP) is started, with the water in the pump suction line devoid of boron and at the same temperature as the coolant in the system. In the second scenario, the plant is at hot standby and the reactor coolant system has been heated up to operating temperature after a long outage. It is assumed that an RCP is started, with the pump suction line filled with cold unborated water, forcing a slug of diluted coolant down the downcomer and subsequently through the reactor core. The subsequent transient thermal mixing and boron dilution that would occur in the reactor system is simulated for these two scenarios. The reactivity insertion rate and the total reactivity are evaluated.

  19. Screening The Aegilops-Triticum Group For Boron Tolerance

    Science.gov (United States)

    Boron deficient and toxic soils pose a critical problem in wheat production on a world scale. Therefore, 79 accessions from 12 diverse wild wheat (Aegilops speltoides, Ae. longissima, Ae. sharonensis, Ae. bicornis, Ae. searsii, Ae. kotschyi, Ae. peregrina ssp. cylindrostachys, Ae. peregrina ssp. eu...

  20. Dynamic strength of reaction-sintered boron carbide ceramic

    Science.gov (United States)

    Savinykh, A. S.; Garkushin, G. V.; Razorenov, S. V.; Rumyantsev, V. I.

    2015-06-01

    The shock compression wave profiles in three modifications of boron carbide ceramic are studied in the compressive stress range 3-19 GPa. The Hugoniot elastic limit and the spall strength of the materials are determined. It is confirmed that the spall strength of high-hardness ceramic changes nonmonotonically with the compressive stress in a shock wave.

  1. Predicted boron-carbide compounds: a first-principles study.

    Science.gov (United States)

    Wang, De Yu; Yan, Qian; Wang, Bing; Wang, Yuan Xu; Yang, Jueming; Yang, Gui

    2014-06-14

    By using developed particle swarm optimization algorithm on crystal structural prediction, we have explored the possible crystal structures of B-C system. Their structures, stability, elastic properties, electronic structure, and chemical bonding have been investigated by first-principles calculations with density functional theory. The results show that all the predicted structures are mechanically and dynamically stable. An analysis of calculated enthalpy with pressure indicates that increasing of boron content will increase the stability of boron carbides under low pressure. Moreover, the boron carbides with rich carbon content become more stable under high pressure. The negative formation energy of predicted B5C indicates its high stability. The density of states of B5C show that it is p-type semiconducting. The calculated theoretical Vickers hardnesses of B-C exceed 40 GPa except B4C, BC, and BC4, indicating they are potential superhard materials. An analysis of Debye temperature and electronic localization function provides further understanding chemical and physical properties of boron carbide.

  2. Standard specification for nuclear-Grade boron carbide pellets

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This specification applies to boron carbide pellets for use as a control material in nuclear reactors. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

  3. High-hardness ceramics based on boron carbide fullerite derivatives

    Science.gov (United States)

    Ovsyannikov, D. A.; Popov, M. Yu.; Perfilov, S. A.; Prokhorov, V. M.; Kulnitskiy, B. A.; Perezhogin, I. A.; Blank, V. D.

    2017-02-01

    A new type of ceramics based on the phases of fullerite derivatives and boron carbide B4C is obtained. The material is synthesized at a temperature of 1500 K and a relatively low pressure of 4 GPa; it has a high hardness of 45 GPa and fracture toughness of 15 MPa m1/2.

  4. Interaction of Boron Clusters with Oxygen: a DFT Study

    Science.gov (United States)

    Salavitabar, Kamron; Boggavarapu, Kiran; Kandalam, Anil

    A controlled combustion involving aluminum nanoparticles has often been the focus of studies in the field of solid fuel propellants. However very little focus has been given to the study of boron nanoparticles in controlled combustion. In contrast to aluminum nanoclusters, boron nanoclusters (Bn) are known to exhibit a planar geometries even at the size of n = 19 - 20, and thus offer a greater surface area for interaction with oxygen. Earlier experimental studies have shown that boron nanoclusters exhibit different reactivity with oxygen depending on their size and charge. In this poster, we present our recent density functional theory based results, focusing on the reactivity patterns of neutral and negatively charged B5 cluster with On, where n = 1 - 5; and B6 cluster with On (n = 1 - 2). The effect of charge on the reactivity of boron cluster, variation in the stability of product clusters, i e., neutral and negatively charged B5On (n = 1 - 5) and B6On (n = 1 - 2) are also examined. Financial Support from West Chester University Foundation under FaStR grant is acknowledged.

  5. Boron isotope fractionation in magma via crustal carbonate dissolution.

    Science.gov (United States)

    Deegan, Frances M; Troll, Valentin R; Whitehouse, Martin J; Jolis, Ester M; Freda, Carmela

    2016-08-04

    Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low δ(11)B values down to -41.5‰, reflecting preferential partitioning of (10)B into the assimilating melt. Loss of (11)B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports (11)B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ(11)B melt values in arc magmas could flag shallow-level additions to the subduction cycle.

  6. Pore confined synthesis of magnesium boron hydride nanoparticles

    NARCIS (Netherlands)

    Au, Yuen S.; Yan, Yigang; De Jong, Krijn P.; Remhof, Arndt; De Jongh, Petra E.

    2014-01-01

    Nanostructured materials based on light elements such as Li, Mg, and Na are essential for energy storage and conversion applications, but often difficult to prepare with control over size and structure. We report a new strategy that is illustrated for the formation of magnesium boron hydrides, relev

  7. Electrochemistry of the Oxofluoro Complexes of Boron in Fluoride Melts

    DEFF Research Database (Denmark)

    Polyakova, L.P.; Bukatova, G.A.; Polyakov, E.G.

    1997-01-01

    Electrochemical behavior of oxofluoro complexes of boron, synthesized both in situ in FLINAK melt and added into the melt as Na3B3O3F6 compound, was by linear voltammetry within the range of 570-750 oC. It was shown that in lower part of this range the electrochemical reduction of BOF2- complexes...

  8. Boron, calcium and magnesium in Kavaratti lagoon water, Lakshadweep Archipelago

    Digital Repository Service at National Institute of Oceanography (India)

    Nasnolkar, C.M.; Salkar, V.R.; Shirodkar, P.V.; Abidi, S.A.H.

    Analysis of major elements in the water of Kavaratti lagoon show variations in the concentrations of boron from 4.08 to 4.25 mg kg sup(-1) (av. 4.15 mg kg sup(-1)); calcium from 420.4 to 429.3 mg kg sup(-1) (av. 424.79 mg kg sup(-1)); magnesium from...

  9. Global and local superconductivity in boron-doped granular diamond.

    Science.gov (United States)

    Zhang, Gufei; Turner, Stuart; Ekimov, Evgeny A; Vanacken, Johan; Timmermans, Matias; Samuely, Tomás; Sidorov, Vladimir A; Stishov, Sergei M; Lu, Yinggang; Deloof, Bart; Goderis, Bart; Van Tendeloo, Gustaaf; Van de Vondel, Joris; Moshchalkov, Victor V

    2014-04-02

    Strong granularity-correlated and intragrain modulations of the superconducting order parameter are demonstrated in heavily boron-doped diamond situated not yet in the vicinity of the metal-insulator transition. These modulations at the superconducting state (SC) and at the global normal state (NS) above the resistive superconducting transition, reveal that local Cooper pairing sets in prior to the global phase coherence.

  10. Glucose selective bis-boronic acid click-fluor.

    Science.gov (United States)

    Zhai, Wenlei; Male, Louise; Fossey, John S

    2017-02-14

    Four novel bis-boronic acid compounds were synthesised via copper catalysed azide-alkyne cycloaddition (CuAAC) reactions. Glucose selectivity was observed for a particular structural motif. Moreover, a new glucose selective fluorescent sensor was designed and synthesised as a result.

  11. Finite element analysis of boron diffusion in wooden Poles

    DEFF Research Database (Denmark)

    Krabbenhøft, Kristian; Hoffmeyer, Preben; Bechgaard, Carl;

    2004-01-01

    The problem of describing the migration of dissolved boron in wood is treated with special reference to the commonly used remedial treatment of wooden poles. The governing equations are derived and discussed together with some of the material parameters required. The equations are solved by the f...... by the finite element method and, finally, results showing the effect of different treatment strategies are presented....

  12. Finite Element Analysis of Boron Diffusion in Wooden Poles

    DEFF Research Database (Denmark)

    Krabbenhøft, Kristian; Hoffmeyer, Preben; Bechgaard, Carl;

    2004-01-01

    The problem of describing the migration of dissolved boron in wood is treated with special reference to the commonly used remedial treatment of wooden poles. The governing equations are derived and discussed together with some of the material parameters required. The equations are solved by the f...... by the finite element method and, finally, results showing the effect of different treatment strategies are presented....

  13. Finite Element Analysis of Boron Diffusion in Wooden Poles

    DEFF Research Database (Denmark)

    Krabbenhøft, Kristian; Hoffmeyer, P.; Bechgaard, C.;

    2003-01-01

    The problem of describing the migration of dissolved boron in wood is treated with special reference to the commonly used remedial treatment of wooden poles. The governing equations are derived and discussed together with some of the material parameters required. The equations are solved by the f...... by the finite element method and, finally, results showing the effect of different treatment strategies are presented....

  14. An Exploration of Neutron Detection in Semiconducting Boron Carbide

    Science.gov (United States)

    Hong, Nina

    The 3He supply problem in the U.S. has necessitated the search for alternatives for neutron detection. The neutron detection efficiency is a function of density, atomic composition, neutron absorption cross section, and thickness of the neutron capture material. The isotope 10B is one of only a handful of isotopes with a high neutron absorption cross section---3840 barns for thermal neutrons. So a boron carbide semiconductor represents a viable alternative to 3He. This dissertation provides an evaluation of the performance of semiconducting boron carbide neutron detectors grown by plasma enhance chemical vapor deposition (PECVD) in order to determine the advantages and drawbacks of these devices for neutron detection. Improved handling of the PECVD system has resulted in an extremely stable plasma, enabling deposition of thick films of semiconducting boron carbide. A variety of material and semiconducting characterization tools have been used to investigate the structure and electronic properties of boron carbide thin films, including X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, infrared/Raman spectroscopy, current-voltage measurements and capacitance-voltage measurements. Elemental concentrations in the boron carbide films have been obtained from Rutherford backscattering and elastic recoil detection analysis. Solid state neutron detection devices have been fabricated in the form of heterostructured p-n diodes, p-type boron carbide/n-type Si. Operating conditions, including applied bias voltage, and time constants, have been optimized for maximum detection efficiency and correlated to the semiconducting properties investigated in separate electronic measurements. Accurate measurements of the neutron detection efficiency and the response of the detector to a wide range of neutron wavelengths have been performed at a well calibrated, tightly collimated, "white" cold neutron beam source using time-of-flight neutron detection technique

  15. Understanding Boron through Size-Selected Clusters: Structure, Chemical Bonding, and Fluxionality

    Energy Technology Data Exchange (ETDEWEB)

    Sergeeva, Alina P.; Popov, Ivan A.; Piazza, Zachary A.; Li, Wei-Li; Romanescu, Constantin; Wang, Lai S.; Boldyrev, Alexander I.

    2014-04-15

    Conspectus Boron is an interesting element with unusual polymorphism. While three-dimensional (3D) structural motifs are prevalent in bulk boron, atomic boron clusters are found to have planar or quasi-planar structures, stabilized by localized two-center–two-electron (2c–2e) σ bonds on the periphery and delocalized multicenter–two-electron (nc–2e) bonds in both σ and π frameworks. Electron delocalization is a result of boron’s electron deficiency and leads to fluxional behavior, which has been observed in B13+ and B19–. A unique capability of the in-plane rotation of the inner atoms against the periphery of the cluster in a chosen direction by employing circularly polarized infrared radiation has been suggested. Such fluxional behaviors in boron clusters are interesting and have been proposed as molecular Wankel motors. The concepts of aromaticity and antiaromaticity have been extended beyond organic chemistry to planar boron clusters. The validity of these concepts in understanding the electronic structures of boron clusters is evident in the striking similarities of the π-systems of planar boron clusters to those of polycyclic aromatic hydrocarbons, such as benzene, naphthalene, coronene, anthracene, or phenanthrene. Chemical bonding models developed for boron clusters not only allowed the rationalization of the stability of boron clusters but also lead to the design of novel metal-centered boron wheels with a record-setting planar coordination number of 10. The unprecedented highly coordinated borometallic molecular wheels provide insights into the interactions between transition metals and boron and expand the frontier of boron chemistry. Another interesting feature discovered through cluster studies is boron transmutation. Even though it is well-known that B–, formed by adding one electron to boron, is isoelectronic to carbon, cluster studies have considerably expanded the possibilities of new structures and new materials using the B

  16. The levels of boron-uptake proteins in roots are correlated with tolerance to boron stress in barley

    Science.gov (United States)

    Boron (B) is an essential micronutrient required for plant growth and development. Recently, two major B-uptake proteins, BOR1 and NIP5;1 have been identified and partially characterized. BOR1 is a high-affinity B transporter involved in xylem loading in roots, and NIP5;1 acts is a major boric-acid ...

  17. Interaction of boron with graphite: A van der Waals density functional study

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Juan; Wang, Chen [Beijing Key Lab of Fine Ceramics, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Liang, Tongxiang, E-mail: txliang@tsinghua.edu.cn [State Key Lab of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084 (China); Lai, Wensheng [Advanced Material Laboratory, School of Materials Science & Engineering, Tsinghua University, Beijing, 100084 (China)

    2016-08-30

    Highlights: • A van der Waals density-functional approach is applied to study the interaction of boron with graphite. • VdW-DF functionals give fair agreement of crystal parameters with experiments. • The π electron approaches boron while adsorbing on graphite surface. • The hole introduced by boron mainly concentrates on boron and the nearest three carbon atoms. • PBE cannot describe the interstitial boron in graphite because of the ignoring binding of graphite sheets. - Abstract: Boron doping has been widely investigated to improve oxidation resistance of graphite. In this work the interaction of boron with graphite is investigated by a van der Waals density-functional approach (vdW-DF). The traditional density-functional theory (DFT) is well accounted for the binding in boron-substituted graphite. However, to investigate the boron atom on graphite surface and the interstitial impurities require use of a description of graphite interlayer binding. Traditional DFT cannot describe the vdW physics, for instance, GGA calculations show no relevant binding between graphite sheets. LDA shows some binding, but they fail to provide an accurate account of vdW forces. In this paper, we compare the calculation results of graphite lattice constant and cohesive energy by several functionals, it shows that vdW-DF such as two optimized functionals optB88-vdW and optB86b-vdW give much improved results than traditional DFT. The vdW-DF approach is then applied to study the interaction of boron with graphite. Boron adsorption, substitution, and intercalation are discussed in terms of structural parameters and electronic structures. When adsorbing on graphite surface, boron behaves as π electron acceptor. The π electron approaches boron atom because of more electropositive of boron than carbon. For substitution situation, the hole introduced by boron mainly concentrates on boron and the nearest three carbon atoms. The B-doped graphite system with the hole has less

  18. Magnetron sputtering synthesis of large area well-ordered boron nanowire arrays

    Institute of Scientific and Technical Information of China (English)

    CAO; Limin; ZHANG; Ze; WANG; Wenkui

    2004-01-01

    One-dimensionally nanostructured materials, such as nanowires and nanotubes, are the smallest dimensional structures for efficient transport of electrons and excitons, and are therefore critical building blocks for nanoscale electronic and mechanical devices. In this paper, boron nanowires with uniform diameters from 20 to 80nm were synthesized by radio-frequency magnetron sputtering of pure boron powder and B2O3 powder mixtures in argon atmosphere. The boron nanowires produced stand vertically on the substrate surface to form well-ordered arrays over large areas with selforganized arrangements without involvement of any template and patterned catalyst. The high-density boron nanowires are parallel to each other and well distributed, forming highly ordered and uniform arrays. A more interesting and unique feature of the boron nanowires is that most of their tips are flat rather than hemispherical in morphologies.Detailed studies on its structure and composition indicate that boron nanowires are amorphous. Boron nanowire appears as a new member in the family of one-dimensional nanostructures. Considering the unique properties of boron-rich solids and other nanostructures, it is reasonable to expect that the boron nanowires will display some exceptional and interesting properties. A vapor-cluster-solid (VCS) mechanism was proposed to explain the growth of boron nanowires based on our experimental observations.

  19. Boron effects on creep rupture strength of W containing advanced ferritic creep resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Mito, N.; Hasegawa, Y. [Tohoku Univ., Sendai (Japan)

    2010-07-01

    The creep strength in ferritic creep resistant steels is increased by boron addition. However, the strengthening mechanisms have not yet been studied. This study clarifies the strengthening mechanism of 9% chromium steels with 10{proportional_to}100ppm boron and 0.5{proportional_to}2.0mass% tungsten in the laboratory. The strengthening effect of simultaneous addition of boron and tungsten was analyzed by hardenability, room-temperature strength and creep tests at 650 C. Changes in the microstructure as a result of the addition of boron and tungsten were also examined by optical microscope and transmission electron microscope (TEM). In addition, Alpha-ray Track Etching (ATE) method was used to detect the boron distribution and analyze the mechanisms change in the mechanical properties. Boron addition did not affect room-temperature strength, however, simultaneous addition of boron and tungsten increased room-temperature and high-temperature strength. According to ATE analysis, boron exists at the grain boundary. Therefore, synergistic effects of boron and tungsten on the creep strength suggest the tungsten precipitates stabilization by boron at the grain boundary. (orig.)

  20. Boron exposure assessment using drinking water and urine in the North of Chile.

    Science.gov (United States)

    Cortes, S; Reynaga-Delgado, E; Sancha, A M; Ferreccio, C

    2011-12-01

    Boron is an essential trace element for plants and humans however it is still an open question what levels of boron are actually safe for humans. This study, conducted between 2006 and 2010, measured exposure levels of boron in drinking water and urine of volunteers in Arica, an area in the North of Chile with high levels of naturally occurring boron. Samples were taken of tap and bottled water (173 and 22, respectively), as well as urine from 22 volunteers, and subsequently analyzed by inductively coupled plasma spectroscopy (ICP-OES). Boron varied in public tap water from 0.22 to 11.3mgL(-1), with a median value of 2.9mgL(-1), while concentrations of boron in bottled water varied from 0.01 to 12.2mgL(-1). Neither tap nor bottled water samples had concentrations of boron within WHO recommended limits. The concentration of boron in urine varied between 0.45 and 17.4mgL(-1), with a median of 4.28mgL(-1) and was found to be correlated with tap water sampled from the homes of the volunteers (r=0.64). Authors highly recommend that in northern Chile - where levels of boron are naturally high - that the tap and bottled water supplies be monitored in order to protect public health and that regulatory standards also be established for boron in drinking water in order to limit exposure.

  1. Electric Heating Property from Butyl Rubber-Loaded Boron Carbide Composites

    Institute of Scientific and Technical Information of China (English)

    MENG Dechuan; WANG Ninghui; LI Guofeng

    2014-01-01

    We researched the electric heating property from butyl rubber-loaded boron carbide composite. The effects of boron carbide content on bulk resistivity, voltage-current characteristic, thermal conductivity and thermal stability of boron carbide/butyl rubber (IIR) polymer composite were introduced. The analysis results indicated that the bulk resistivity decreased greatly with increasing boron carbide content, and when boron carbide content reached to 60%, the bulk resistivity achieved the minimum. Accordingly, electric heating behavior of the composite is strongly dependent on boron carbide content as well as applied voltage. The content of boron carbide was found to be effective in achieving high thermal conductivity in composite systems. The thermal conductivity of the composite material with added boron carbide was improved nearly 20 times than that of the pure IIR. The thermal stability test showed that, compared with pure IIR, the thermal stable time of composites was markedly extended, which indicated that the boron carbide can significantly improve the thermal stability of boron carbide/IIR composite.

  2. Effect of Boron Content on the Microstructure and Magnetic Properties of Non-oriented Electrical Steels

    Institute of Scientific and Technical Information of China (English)

    WAN Yong; CHEN Weiqing

    2015-01-01

    The effects of boron content in the range of 0-0.0082 wt%, on the inclusion type, microstructure, texture and magnetic properties of non-oriented electrical steels have been studied. Afterfi nal annealing, the addition of excess boron(w(Bt)>0.004 1 wt%) led to the formation of Fe2B particles. As boron content increased, grain size increased and reached a maximum in steel with 0.004 1 wt% boron. Furthermore, steel containing 0.004 1 wt% boron had the strongest {100}fi ber texture, Goss texture and the weakest {111}fi ber texture among thefi ve tested steels. Flux densityfi rstly rapidly increased and then suddenly decreased with increasing boron content and reached a maximum in steel with 0.004 1 wt% boron. Conversely, core lossfi rst sharply decreased and then abruptly increased with the increase of boron content and reached a minimum in steel containing 0.004 1 wt% boron. Steel containing 0.004 1 wt% boron obtained the best magnetic properties, predominantly through the development of optimum grain size and favorable texture.

  3. Boron exposure assessment using drinking water and urine in the North of Chile

    Energy Technology Data Exchange (ETDEWEB)

    Cortes, S., E-mail: scortes@med.puc.cl [Departamento de Salud Publica, Pontificia Universidad Catolica de Chile, Santiago (Chile); Reynaga-Delgado, E. [Centro de Investigaciones Biologicas del Noroeste, La Paz B.C.S. (Mexico); Sancha, A.M. [Facultad de Ciencias Fisicas y Matematicas, Universidad de Chile, Santiago (Chile); Ferreccio, C. [Departamento de Salud Publica, Pontificia Universidad Catolica de Chile, Santiago (Chile)

    2011-12-01

    Boron is an essential trace element for plants and humans however it is still an open question what levels of boron are actually safe for humans. This study, conducted between 2006 and 2010, measured exposure levels of boron in drinking water and urine of volunteers in Arica, an area in the North of Chile with high levels of naturally occurring boron. Samples were taken of tap and bottled water (173 and 22, respectively), as well as urine from 22 volunteers, and subsequently analyzed by inductively coupled plasma spectroscopy (ICP-OES). Boron varied in public tap water from 0.22 to 11.3 mg L{sup -1}, with a median value of 2.9 mg L{sup -1}, while concentrations of boron in bottled water varied from 0.01 to 12.2 mg L{sup -1}. Neither tap nor bottled water samples had concentrations of boron within WHO recommended limits. The concentration of boron in urine varied between 0.45 and 17.4 mg L{sup -1}, with a median of 4.28 mg L{sup -1} and was found to be correlated with tap water sampled from the homes of the volunteers (r = 0.64). Authors highly recommend that in northern Chile - where levels of boron are naturally high - that the tap and bottled water supplies be monitored in order to protect public health and that regulatory standards also be established for boron in drinking water in order to limit exposure.

  4. Two-dimensional finite elements model for boron management in agroforestry sites.

    Science.gov (United States)

    Tayfur, Gokmen; Tanji, Kenneth K; Baba, Alper

    2010-01-01

    Agroforesty systems, which are recommended as a management option to lower the shallow groundwater level and to reuse saline subsurface drainage waters from the tile-drained croplands in the drainage-impacted areas of Jan Joaquin Valley of California, have resulted in excessive boron buildup in the soil root zone. To assess the efficacy of the long-term impacts of soil boron buildup in agroforesty systems, a mathematical model was developed to simulate non-conservative boron transport. The developed dynamic two-dimensional finite element model simulates water flow and boron transport in saturated-unsaturated soil system, including boron sorption and boron uptake by root-water extraction processes. The simulation of two different observed field data sets by the developed model is satisfactory, with mean absolute error of 1.5 mg/L and relative error of 6.5%. Application of the model to three different soils shows that boron adsorption is higher in silt loam soil than that in sandy loam and clay loam soils. This result agrees with the laboratory experimental observations. The results of the sensitivity analysis indicate that boron uptake by root-water extraction process influences the boron concentration distribution along the root zone. Also, absorption coefficient and maximum adsorptive capacity of a soil for boron are found to be sensitive parameters.

  5. Effect of boron on the microstructure and mechanical properties of carbidic austempered ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Peng Yuncheng; Jin Huijin [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China); Liu Jinhai, E-mail: pyc_wanhj@163.com [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China); Li Guolu [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China)

    2011-11-25

    Highlights: {yields} Boron are applied to carbidic austempered ductile iron (CADI). {yields} Boron microalloying CADI is a new high hardenability of wear-resistant cast iron. {yields} Addition of boron to CADI significantly improves hardenability. {yields} Effect of boron on the CADI grinding ball were investigated. {yields} Optimum property is obtained when boron content at 0.03 wt%. - Abstract: Carbidic austempered ductile iron (CADI) castings provide a unique combination of high hardness and toughness coupled with superior wear resistance properties, but their hardenability restricts their range of applications. The purpose of this study was to investigate the influence of boron on the microstructure and mechanical properties of CADI. The experimental results indicate that the CADI comprises graphite nodules, which are dispersive boron-carbides that are distributed in the form of strips, and the matrix is a typical ausferritic matrix. Microscopic amounts of boron can improve the hardenability of CADI, but higher boron content reduces the hardenability and toughness of CADI. The results are discussed in the context of the influence of boron content on the microstructure and mechanical properties of grinding balls.

  6. Interaction of boron with graphite: A van der Waals density functional study

    Science.gov (United States)

    Liu, Juan; Wang, Chen; Liang, Tongxiang; Lai, Wensheng

    2016-08-01

    Boron doping has been widely investigated to improve oxidation resistance of graphite. In this work the interaction of boron with graphite is investigated by a van der Waals density-functional approach (vdW-DF). The traditional density-functional theory (DFT) is well accounted for the binding in boron-substituted graphite. However, to investigate the boron atom on graphite surface and the interstitial impurities require use of a description of graphite interlayer binding. Traditional DFT cannot describe the vdW physics, for instance, GGA calculations show no relevant binding between graphite sheets. LDA shows some binding, but they fail to provide an accurate account of vdW forces. In this paper, we compare the calculation results of graphite lattice constant and cohesive energy by several functionals, it shows that vdW-DF such as two optimized functionals optB88-vdW and optB86b-vdW give much improved results than traditional DFT. The vdW-DF approach is then applied to study the interaction of boron with graphite. Boron adsorption, substitution, and intercalation are discussed in terms of structural parameters and electronic structures. When adsorbing on graphite surface, boron behaves as π electron acceptor. The π electron approaches boron atom because of more electropositive of boron than carbon. For substitution situation, the hole introduced by boron mainly concentrates on boron and the nearest three carbon atoms. The B-doped graphite system with the hole has less ability to offer electrons to oxygen, ultimately resulted in the inhibition of carbon oxidation. For interstitial doping, vdW-DFs show more accurate formation energy than LDA. PBE functional cannot describe the interstitial boron in graphite reasonably because of the ignoring binding of graphite sheets. The investigation of electron structures of boron doped graphite will play an important role in understanding the oxidation mechanism in further study.

  7. Boron-Based Hydrogen Storage: Ternary Borides and Beyond

    Energy Technology Data Exchange (ETDEWEB)

    Vajo, John

    2016-09-22

    DOE continues to seek reversible solid-state hydrogen materials with hydrogen densities of ³11 wt% and ³80 g/L that can deliver hydrogen and be recharged at moderate temperatures (£100 °C) and pressures (£100 bar) enabling incorporation into hydrogen storage systems suitable for transportation applications. Boron-based hydrogen storage materials have the potential to meet the density requirements given boron’s low atomic weight, high chemical valance, and versatile chemistry. However, the rates of hydrogen exchange in boron based compounds are thus far much too slow for practical applications. Although contributing to the high hydrogen densities, the high valance of boron also leads to slow rates of hydrogen exchange due to extensive boron-boron atom rearrangements during hydrogen cycling. This rearrangement often leads to multiple solid phases occurring over hydrogen release and recharge cycles. These phases must nucleate and react with each other across solid-solid phase boundaries leading to energy barriers that slow the rates of hydrogen exchange. This project sought to overcome the slow rates of hydrogen exchange in boron-based hydrogen storage materials by minimizing the number of solid phases and the boron atom rearrangement over a hydrogen release and recharge cycle. Two novel approaches were explored: 1) developing matched pairs of ternary borides and mixed-metal borohydrides that could exchange hydrogen with only one hydrogenated phase (the mixed-metal borohydride) and only one dehydrogenated phase (the ternary boride); and 2) developing boranes that could release hydrogen by being lithiated using lithium hydride with no boron-boron atom rearrangement. For the first approach, possible pairs of ternary borides and mixed-metal borohydrides based on Mg with various first row transition metals were investigated both experimentally and theoretically. In particular, the Mg/Mn ternary boride and mixed-metal borohydride were found to be a suitable pair and

  8. Boron concentration measurements by alpha spectrometry and quantitative neutron autoradiography in cells and tissues treated with different boronated formulations and administration protocols.

    Science.gov (United States)

    Bortolussi, Silva; Ciani, Laura; Postuma, Ian; Protti, Nicoletta; Luca Reversi; Bruschi, Piero; Ferrari, Cinzia; Cansolino, Laura; Panza, Luigi; Ristori, Sandra; Altieri, Saverio

    2014-06-01

    The possibility to measure boron concentration with high precision in tissues that will be irradiated represents a fundamental step for a safe and effective BNCT treatment. In Pavia, two techniques have been used for this purpose, a quantitative method based on charged particles spectrometry and a boron biodistribution imaging based on neutron autoradiography. A quantitative method to determine boron concentration by neutron autoradiography has been recently set-up and calibrated for the measurement of biological samples, both solid and liquid, in the frame of the feasibility study of BNCT. This technique was calibrated and the obtained results were cross checked with those of α spectrometry, in order to validate them. The comparisons were performed using tissues taken form animals treated with different boron administration protocols. Subsequently the quantitative neutron autoradiography was employed to measure osteosarcoma cell samples treated with BPA and with new boronated formulations.

  9. Optical properties of boron carbide near the boron K edge evaluated by soft-x-ray reflectometry from a Ru/B(4)C multilayer.

    Science.gov (United States)

    Ksenzov, Dmitriy; Panzner, Tobias; Schlemper, Christoph; Morawe, Christian; Pietsch, Ullrich

    2009-12-10

    Soft-x-ray Bragg reflection from two Ru/B(4)C multilayers with 10 and 63 periods was used for independent determination of both real and imaginary parts of the refractive index n = 1 - delta + ibeta close to the boron K edge (approximately 188 eV). Prior to soft x-ray measurements, the structural parameters of the multilayers were determined by x-ray reflectometry using hard x rays. For the 63-period sample, the optical properties based on the predictions made for elemental boron major deviations were found close to the K edge of boron for the 10-period sample explained by chemical bonding of boron to B(4)C and various boron oxides.

  10. OsNIP3;1, a rice boric acid channel, regulates boron distribution and is essential for growth under boron-deficient conditions.

    Science.gov (United States)

    Hanaoka, Hideki; Uraguchi, Shimpei; Takano, Junpei; Tanaka, Mayuki; Fujiwara, Toru

    2014-06-01

    Boron is an essential micronutrient for higher plants. Boron deficiency is an important agricultural issue because it results in loss of yield quality and/or quantity in cereals and other crops. To understand boron transport mechanisms in cereals, we characterized OsNIP3;1, a member of the major intrinsic protein family in rice (Oryza sativa L.), because OsNIP3;1 is the most similar rice gene to the Arabidopsis thaliana boric acid channel genes AtNIP5;1 and AtNIP6;1. Yeast cells expressing OsNIP3;1 imported more boric acid than control cells. GFP-tagged OsNIP3;1 expressed in tobacco BY2 cells was localized to the plasma membrane. The accumulation of OsNIP3;1 transcript increased fivefold in roots within 6 h of the onset of boron starvation, but not in shoots. Promoter-GUS analysis suggested that OsNIP3;1 is expressed mainly in exodermal cells and steles in roots, as well as in cells around the vascular bundles in leaf sheaths and pericycle cells around the xylem in leaf blades. The growth of OsNIP3;1 RNAi plants was impaired under boron limitation. These results indicate that OsNIP3;1 functions as a boric acid channel, and is required for acclimation to boron limitation. Boron distribution among shoot tissues was altered in OsNIP3;1 knockdown plants, especially under boron-deficient conditions. This result demonstrates that OsNIP3;1 regulates boron distribution among shoot tissues, and that the correct boron distribution is crucial for plant growth.

  11. Elaboration and characterization of boron doping during SiC growth by VLS mechanism

    Science.gov (United States)

    Soueidan, Maher; Ferro, Gabriel; Nsouli, Bilal; Roumié, Mohamad; Habka, Nada; Souliere, Véronique; Bluet, Jean-Marie; Kazan, Michel

    2011-07-01

    VLS mechanism was used for growing boron doped homoepitaxial SiC layers on 4H-SiC(0 0 0 1) 8° off substrate. Si-based melts were fed by propane in the temperature range 1450-1500 °C. Two main approaches were studied to incorporate boron during growth: (1) adding elemental B in the initial melt, with two different compositions: Si 90B 10 and Si 27Ge 68B 5; the growth was performed at 1500 °C; (2) adding B 2H 6 to the gas phase during growth with a melt composition of Si 25Ge 75; the growth was performed at 1450 °C. In most cases, the growth time was limited by liquid loss. The longest growth duration (1 h) was obtained when adding B 2H 6 to the gas phase. In the case of Si 90B 10 melt, the surface morphology exhibits large and parallel terraces whereas the step front is more undulated when adding Ge. Raman and photoluminescence characterizations performed on these layers confirmed the 4H polytype of the layers in addition to the presence of B, which results in a strong B-N donor-acceptor band. The thickness and the growth rate were determined by micro-Infrared spectroscopy. Particle Induced γ-ray Emission (PIGE) was tentatively used to detect B incorporation inside the grown layers. These results were compared to SIMS measurements from which B concentration was found to vary from 10 18 to 10 19 at cm -3.

  12. Effect of the powder particle size on the wear behavior of boronized AISI 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Guenen, Ali [Mustafa Kemal Univ., Hatay (Turkey). Dept. of Metallurgy and Material Engineering; Kuecuek, Yilmaz; Oege, Mecit; Goek, M. Sabri [Bartin Univ. (Turkey). Dept. of Mechanical Engineering; Er, Yusuf [Firat Univ., Elazig (Turkey); Cay, V. Veli [Dicle Univ., Diyarbakir (Turkey). Civil Aviation Higher School

    2015-06-01

    In this study, the AISI 304 steel specimens were boronized with nanoboron of the size of 10 50 nm and commercial Ekabor 3 powders (<1400 μm) at 950 C to 1000 C for 2 h and 4 h. Boronized steel specimens were characterized via SEM, microhardness and XRD analyses. Abrasive wear behavior of the specimens, boronized at different temperatures and treatment durations, were examined. The fixed ball micro-abrasion tests were carried out using the abrasive slurry, prepared with different SiC powder particle sizes on the boronized specimens at different rotational speeds. The specimens boronized with nanoboron powders exhibited a higher hardness and abrasive wear resistance than the samples boronized with the Ekabor 3 powders.

  13. Boron Plays an Important Role in the Regulation of Plant Cell Growth

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Boron is an essential nutrition for higher plants.However, the primary function of boron remains a matter of discussion.Boron may function by forming complexes with compounds having cis-hydroxyl groups(diols), e.g., pectic materials in cell walls, glycoproteins or glycolipids in membranes and o-diphenols.The well-defined functions of boron are its involvement in maintaining cell wall structure and both the structural and the functional integrity of plasma membrane.Lack of boron causes an increase in the leakage of ions and compounds which reflects the impairment of plasma membrane.Boron is functionally important in forming a pectic network in cell wall which is responsible for the extensibility of cell wall and consequently regulates cell growth.

  14. Preparation and characterization of boron nitride/carbon fiber composite with high specific surface area

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yan; Fan, Mingwen [Wuhan Univ. (China). Key Laboratory for Oral Biomedical Engineering; Yuan, Songdong; Xiong, Kun; Hu, Kunpeng; Luo, Yi [Hubei Univ. of Technology, Wuhan (China). School of Chemistry and Chemical Engineering; Li, Dong [Hubei Univ. of Technology, Wuhan (China). School of Chemistry and Chemical Engineering; Oxford Univ. (United Kingdom). Chemistry Research Lab.

    2014-06-15

    Boron nitride can be used as a good catalyst carrier because of its high thermal conductivity and chemical stability. However, a high specific surface area of boron nitride is still desirable. In this work, a carbon fiber composite coated with boron nitride villous nano-film was prepared, and was also characterized by means of scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis. The results indicated that the carbon fibers were covered by uniform villous boron nitride films whose thickness was about 150 - 200 nm. The specific surface area of the boron nitride/carbon fiber composite material was 96 m{sup 2} g{sup -1}, which was markedly improved compared with conventional boron nitride materials. (orig.)

  15. Ion Exchange Extraction of Boron from Aqueous Fluids by Amberlite IRA 743 Resin

    Institute of Scientific and Technical Information of China (English)

    肖应凯; 廖步勇; 刘卫国; 肖云; SWIHART,GeorgeH.

    2003-01-01

    The ion exchange characteristics d Amherlite IRA 743 resin for extracting boron from aqueous fluids have been investigated in detail. The results show that AmherHte IRA 743 resin, a boron specific ion exchange resin, can quantitatively extract boron as the B (OH)4- spedes from weakly basle solution. Some exchangeable anions such as CI- and SO42- are present, resulting in an increase in pH value of the loeded solution within the nan, and the boron in natural aqueous fluids with low nH is also extracted by Amberlite IRA 743 resin. However, the voiume of loaded solution must be restricted. The maximum voiume of loaded solution giving quantitative extraction of boron decreases for sample soh.,tiom of lower pH value. Warm HCI solution is more effective than room temperature HCI solution for eluting boron from Amberllte IRA 743 resin.

  16. Effects of supplemental boron on growth performance and meat quality in African ostrich chicks.

    Science.gov (United States)

    Wang, Wei; Xiao, Ke; Zheng, Xinting; Zhu, Daiyun; Yang, Zhi; Tang, Juan; Sun, Pengpeng; Wang, Jing; Peng, Kemei

    2014-11-19

    To investigate the effects of boron on growth performance and meat quality, 10-day-old Africa ostrich chicks were randomly divided into 6 groups with 6 replicates in each group. For 80 days, birds in the treatments were fed the same basal diet but given different concentrations of boron-supplemented water. The highest final BW (33.4 ± 0.30 kg), ADFI (376 ± 1.83 g), and ADG (224 ± 1.01 g) appeared in the group receiving 160 mg/L boron (group 4). 160 mg/L boron also decreased drip loss (2.20 ± 0.59), cooking loss (35.3 ± 1.14), and elevated pH value (6.13 ± 0.28) of meat (P boron improved ostrich growth performance and meat quality; however, high concentrations of boron decreased both performance and meat quality.

  17. Effect of boron addition on the microstructure and stress-rupture properties of directionally solidified superalloys

    Institute of Scientific and Technical Information of China (English)

    Bao-ping Wu; Lin-han Li; Jian-tao Wu; Zhen Wang; Yan-bin Wang; Xing-fu Chen; Jian-xin Dong; Jun-tao Li

    2014-01-01

    This study is focused on the effect of boron addition, in the range of 0.0007wt% to 0.03wt%, on the microstructure and stress-rupture properties of a directionally solidified superalloy. With increasing boron content in the as-cast alloys, there is an increase in the fraction of theγ′/γ eutectic and block borides precipitate around theγ′/γ eutectic. At a high boron content of 0.03wt%, there is precipitation of lamellar borides. Upon heat treatment, fine block borides tend to precipitate at grain boundaries with increasing boron content. Overall, the rupture life of the directionally solidified superalloy is significantly improved with the addition of nominal content of boron. However, the rupture life decreases when the boron content exceeds 0.03wt%.

  18. Effect of boron on hot strips of low carbon steel produced by compact strip production

    Institute of Scientific and Technical Information of China (English)

    Hao Yu; Yonglin Kang

    2008-01-01

    The effect of boron on hot strips of low carbon steel produced by compact strip production (CSP) to reduce the strength to a certain degree was investigated, which is quite different from that of high-strength low alloy steel. The mechanical properties and microstructural evolution of the hot strip were studied using optical microscopy and tensile tests. By means of an electrolytic disso- lution technique and Thermo-Cal calculation, the precipitates containing boron were analyzed and detected. From the electron back- scattered diffraction analysis, it can be deciphered whether the microstructure has recrystallized or not. Furthermore, the effect of boron segregation on the recrystallization or non-recrystallization conditions can be distinguished. The segregation behavior of boron was investigated in boron-containing steel. The nonequilibrium segregation of boron during processing was discussed on the basis of the forming complexes with vacancies that migrate to the boundaries prior to annihilation, which was confirmed by the subsequent cold rolling with annealing experiments.

  19. BORON-NITROGEN RELATIONSHIP IN WHEAT (Triticum aestivum L. GROWN WITH THE NUTRIENT SOLUTION

    Directory of Open Access Journals (Sweden)

    Mehmet ALPASLAN

    1996-03-01

    Full Text Available The effects of boron applied 0.01, 0.1, 1.0, and 10.0 µg B/ml levels as boric acid (H3 BO3, and nitrogen applied 25, 100, 200, and 400 µg N/ml as ammonium nitrate (NH4 NO3, respectively, on the amount of dry matter yield, and boron, nitrogen and nitrate contents of wheat (Triticum aestivum L. grown in perlite medium with Ruakura nutrient solution under greenhouse conditions were investigated. Dry matter yield and nitrate contents of wheat were decreased and boron content was increased with increasing boron application. Controversially, application of nitrogen increased dry matter yield, nitrogen and nitrate contents of wheat, while decreases in boron contents. Those effects of boron and nitrogen were found to be statistically significant (P

  20. A Preliminary experimental study of the boron concentration in vapor and the isotopic A preliminary experimental study of the boron concentrationin vapor and the isotopic fractionation of boron betweenseawater and vapor during evaporation of seawater

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A laboratory experiment was undertaken to investigate the behaviour of boron at theseawater-air interface under air flow conditions. Dried air at 25 and 35℃ was passed over or bub-bled through seawater at the same temperature. A combination of ice-chilled condensers and KOHimpregnated cellulose fibre filters was used to collect boron from the reacted air. When air strippedof boron was passed over the seawater, boron was found in the reacted air, and its concentrationwas higher in the higher temperature test. In the tests where air was bubbled through seawater theconcentration of boron in the reacted air was directly proportional to the air flow rate. In this situa-tion the boron in the reacted air was mainly introduced as a spray of microdroplets. Isotopic analy-sis of the collected boron in the non-bubbled tests yields fractionation factors which demonstratethat the lighter isotope, 10B, is enriched in the reacted air. The size of the fractionation changeswith temperature, ruling out a purely kinetic effect.

  1. Dry Process for Manufacturing Hybridized Boron Fiber/Carbon Fiber Thermoplastic Composite Materials from a Solution Coated Precursor

    Science.gov (United States)

    Belvin, Harry L. (Inventor); Cano, Roberto J. (Inventor)

    2003-01-01

    An apparatus for producing a hybrid boron reinforced polymer matrix composite from precursor tape and a linear array of boron fibers. The boron fibers are applied onto the precursor tapes and the precursor tape processed within a processing component having an impregnation bar assembly. After passing through variable-dimension forming nip-rollers, the precursor tape with the boron fibers becomes a hybrid boron reinforced polymer matrix composite. A driving mechanism is used to pulled the precursor tape through the method and a take-up spool is used to collect the formed hybrid boron reinforced polymer matrix composite.

  2. Synthesis of alkenyl boronates from allyl-substituted aromatics using an olefin cross-metathesis protocol.

    Science.gov (United States)

    Hemelaere, Rémy; Carreaux, François; Carboni, Bertrand

    2013-07-01

    An efficient synthesis of 3-aryl-1-propenyl boronates from pinacol vinyl boronic ester and allyl-substituted aromatics by cross metathesis is reported. Although the allylbenzene derivatives are prone to isomerization reaction under metathesis conditions, we found that some ruthenium catalysts are effective for this methodology. This strategy thus provides an interesting alternative approach to alkyne hydroboration, leading to the preparation of unknown compounds. Moreover, the boron substituent can be replaced by various functional groups in good yields.

  3. Integrated Rig for the Production of Boron Nitride Nanotubes via the Pressurized Vapor-Condenser Method

    Science.gov (United States)

    Smith, Michael W. (Inventor); Jordan, Kevin C. (Inventor)

    2014-01-01

    An integrated production apparatus for production of boron nitride nanotubes via the pressure vapor-condenser method. The apparatus comprises: a pressurized reaction chamber containing a continuously fed boron containing target having a boron target tip, a source of pressurized nitrogen and a moving belt condenser apparatus; a hutch chamber proximate the pressurized reaction chamber containing a target feed system and a laser beam and optics.

  4. Beam neutron energy optimization for boron neutron capture therapy using Monte Carlo method

    OpenAIRE

    Ali Pazirandeh; Elham Shekarian

    2006-01-01

     In last two decades the optimal neutron energy for the treatment of deep seated tumors in boron neutron capture therapy in view of neutron physics and chemical compounds of boron carrier has been under thorough study. Although neutron absorption cross section of boron is high (3836b), the treatment of deep seated tumors such as gliobelastoma multiform (GBM) requires beam of neutrons of higher energy that can penetrate deeply into the brain and thermalize in the proximity of the tumor. Dosage...

  5. Short-Term Coral Bleaching Is Not Recorded by Skeletal Boron Isotopes

    OpenAIRE

    Schoepf, Verena; McCulloch, Malcolm T.; Mark E. Warner; Levas, Stephen J.; Matsui,Yohei; Aschaffenburg, Matthew D.; Andréa G Grottoli

    2014-01-01

    Coral skeletal boron isotopes have been established as a proxy for seawater pH, yet it remains unclear if and how this proxy is affected by seawater temperature. Specifically, it has never been directly tested whether coral bleaching caused by high water temperatures influences coral boron isotopes. Here we report the results from a controlled bleaching experiment conducted on the Caribbean corals Porites divaricata, Porites astreoides, and Orbicella faveolata. Stable boron (δ11B), carbon (δ1...

  6. Response of Boron and Light on Morph-Physiology and Pod Yield of Two Peanut Varieties

    OpenAIRE

    Md. Quamruzzaman; Md. Jafar Ullah; Md. Fazlul Karim; Nazrul Islam; Md. Jahedur Rahman; Md. Dulal Sarkar

    2016-01-01

    Boron is an important micronutrient that enhances vegetative growth and yield of crops, like peanut. Light also plays an important role in pegging of peanut. There has been little information regarding the application of boron and light in peanut in Bangladesh. Therefore, a field experiment was conducted to study the response of boron and light on morph-physiology and pod yield of two peanut varieties. Treatments considered two peanut varieties, namely, Dhaka-1 and BARI Chinabadam-8, three le...

  7. Electrical transport and thermoelectric properties of boron carbide nanowires

    Science.gov (United States)

    Kirihara, Kazuhiro; Mukaida, Masakazu; Shimizu, Yoshiki

    2017-04-01

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

  8. Thermal Studies on Boron-Based Initiator Formulation.

    Directory of Open Access Journals (Sweden)

    A. G. Rajendran

    1996-12-01

    Full Text Available Boron-potassium nitrate pyrotechnic composition can be converted into a hot wire-sensitive initiator formulation by the addition of an extra fuel. viz. lead thiocyanate. The ignition temperature of this composition depends on the percentage of thiocyanate in the mix and follows a binomial fit. The kinetic parameters. viz. activation energy E and pre-exponential factor A of the charge have been calculated from TG and DSC curves using different approaches developed by Coats-Redfern and Kissinger. Ignition delays measured from isothermal TG runs were found to yield equally good values of E and A. A comparison of these values for the tricomponent system' with those of the bicomponent systems as well as of the ingredients suggests that the starting reaction in this formulation is the reaction between lead thiocyanate and potassium nitrate which energises the main reaction between boron and potassium nitrate. leading to ignition.

  9. Computational prediction of the diversity of monolayer boron phosphide allotropes

    Science.gov (United States)

    Zhu, Zhili; Cai, Xiaolin; Niu, Chunyao; Wang, Chongze; Jia, Yu

    2016-10-01

    We propose previously unrecognized allotropes of monolayer boron phosphorus (BP) based on ab initio density functional calculations. In addition to the hexagonal structure of h-BP, four types of boron phosphide compounds were predicted to be stable as monolayers. They can form sp2 hybridized planar structures composed of 6-membered rings, and buckled geometries including 4-8 or 3-9 membered rings with sp3 like bonding for P atoms. The calculated Bader charges illustrate their ionic characters with the charge transfers from B to P atoms. The competing between the electrostatic energy and the bonding energy of sp2 and sp3 hybridizations reflected in P atoms results in multiple structures of BP. These 2D BP structures can be semiconducting or metallic depending on their geometric structures. Our findings significantly broaden the diversity of monolayer BP allotropes and provide valuable guidance to other 2D group-III-V allotropes.

  10. Superhard Semiconducting Optically Transparent High Pressure Phase of Boron

    Energy Technology Data Exchange (ETDEWEB)

    Zarechnaya, E.Yu.; Dubrovinsky, L.; Dubrovinskaia, N.; Filinchuk, Y.; Chernyshov, D.; Dmitriev, V.; Miyajima, N.; Goresy, A. El; Braun, H.F.; Van Smaalen, S.; Kantor, I.; Kantor, A.; Prakapenka, V.; Hanfland, M.; Mikhaylushkin, A.S.; Abrikosov, I.A.; Simak, S.I.; (Link); (Heidelberg); (Bayreuth); (ESRF); (UC)

    2009-05-21

    An orthorhombic (space group Pnnm) boron phase was synthesized at pressures above 9 GPa and high temperature, and it was demonstrated to be stable at least up to 30 GPa. The structure, determined by single-crystal x-ray diffraction, consists of B{sub 12} icosahedra and B{sub 2} dumbbells. The charge density distribution obtained from experimental data and ab initio calculations suggests covalent chemical bonding in this phase. Strong covalent interatomic interactions explain the low compressibility value (bulk modulus is K{sub 300} = 227 GPa) and high hardness of high-pressure boron (Vickers hardness H{sub v} = 58 GPa), after diamond the second hardest elemental material.

  11. Nuclear Physics meets Medicine and Biology: Boron Neutron Capture Therapy

    CERN Document Server

    F. Ballarini, F; S. Bortolussi, S; P. Bruschi, P; A.M. Clerici, A M; A. De Bari, A; P. Dionigi, P; C. Ferrari, C; M.A. Gadan, M A; N. Protti, N; S. Stella, S; C. Zonta, C; A. Zonta, A; S. Altieri, S

    2010-01-01

    BNCT is a tumour treatment based on thermal-neutron irradiation of tissues enriched with 10B, which according to the 10B(n, )7Li reaction produces particles with high Linear Energy Transfer and short range. Since this treatment can deliver a therapeutic tumour dose sparing normal tissues, BNCT represents an alternative for diffuse tumours and metastases, which show poor response to surgery and photontherapy. In 2001 and 2003, in Pavia BNCT was applied to an isolated liver, which was infused with boron, explanted, irradiated and re-implanted. A new project was then initiated for lung tumours, developing a protocol for Boron concentration measurements and performing organ-dose Monte Carlo calculations; in parallel, radiobiology studies are ongoing to characterize the BNCT effects down to cellular level. After a brief introduction, herein we will present the main activities ongoing in Pavia including the radiobiological ones, which are under investigation not only experimentally but also theoretically, basing on...

  12. Potential applications of boron nitride nanotubes as drug delivery systems.

    Science.gov (United States)

    Ciofani, Gianni

    2010-08-01

    In recent years, there has been an explosion of research in the 'bio-nano' field, with the discovery and introduction of ever more fascinating materials for applications as drug delivery systems, sensors, transducers, and so on. The author's group, for the first time in the literature, proposed boron nitride nanotubes as a valid alternative to carbon nanotubes and other kinds of inorganic materials, because of their improved chemical properties that theoretically guarantee better stability and compatibility in a biological context. In this paper, the bio-applications of boron nitride nanotubes that have emerged in the literature are summarized, with special attention given to their exploitation as safe drug delivery and targeting carriers. Finally, the possibility of combining their physical and chemical properties is approached, highlighting the features that render these innovative nanovectors unique and exceptional candidates for many bio-applications.

  13. BSA-boronic acid conjugate as lectin mimetics.

    Science.gov (United States)

    Narla, Satya Nandana; Pinnamaneni, Poornima; Nie, Huan; Li, Yu; Sun, Xue-Long

    2014-01-10

    We report bovine serum albumin (BSA)-boronic acid (BA) conjugates as lectin mimetics and their glyco-capturing capacity. The BSA-BA conjugates were synthesized by amidation of carboxylic acid groups in BSA with aminophenyl boronic acid in the presence of EDC, and were characterized by Alizarin Red S (ARS) assay and SDS-PAGE gel. The BSA-BA conjugates were immobilized onto maleimide-functionalized silica beads and their sugar capturing capacity and specificity were confirmed by ARS displacement assay. Further, surface plasmon resonance (SPR) analysis of the glyco-capturing activity of the BSA-BA conjugates was conducted by immobilizing BSA-BA onto SPR gold chip. Overall, we demonstrated a BSA-BA-based lectin mimetics for glyco-capturing applications. These lectin mimetics are expected to provide an important tool for glycomics and biosensor research and applications.

  14. Facile synthesis of boron nitride nanotubes and improved electrical conductivity.

    Science.gov (United States)

    Chen, Yongjun; Luo, Lijie; Zhou, Longchang; Mo, Libin; Tong, Zhangfa

    2010-02-01

    A layer of catalyst film on substrate is usually required during the vapor-liquid-solid (VLS) growth of one-dimensional (1D) nanomaterials. In this work, however, a novel approach for synthesizing high-purity bamboo-like boron nitride (BN) nanotubes directly on commercial stainless steel foils was demonstrated. Synthesis was realized by heating boron and zinc oxide (ZnO) powders at 1200 degrees C under a mixture gas flow of nitrogen and hydrogen. The stainless steel foils played an additional role of catalyst besides the substrate during the VLS growth of the nanotubes. In addition, the electrical conductivity of the BN nanotubes was efficiently improved in a simple way by coating with Au and Pd nanoparticles. The decorated BN nanotubes may find potential applications in catalysts, sensors and nanoelectronics.

  15. Boron rings containing planar octacoordinate iron and cobalt

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The boron rings containing planar octacoordinate transition metals, D8h FeB82-, CoB8- and CoB83+, C2v FeB8, D2h CoB8+ and CoB8, are optimized with all real vibrational frequencies at the B3LYP/6-311+G* level of the theory. The D8h FeB82- and CoB8- isomers are global minima, while D8h CoB83+ is only local minimum. The electronic structure character of these systems is revealed by natural bond orbital (NBO) analysis, showing that the boron rings containing planar octacoordinate transition metals have stability and aromaticity with six π electrons. The aromaticity is confirmed by nucleus independent chemical shifts (NICS) calculations.

  16. Encapsulated boron as an osteoinductive agent for bone scaffolds.

    Science.gov (United States)

    Gümüşderelioğlu, Menemşe; Tunçay, Ekin Ö; Kaynak, Gökçe; Demirtaş, Tolga T; Aydın, Seda Tığlı; Hakkı, Sema S

    2015-01-01

    The aim of this study was to develop boron (B)-releasing polymeric scaffold to promote regeneration of bone tissue. Boric acid-doped chitosan nanoparticles with a diameter of approx. 175 nm were produced by tripolyphosphate (TPP)-initiated ionic gelation process. The nanoparticles strongly attached via electrostatic interactions into chitosan scaffolds produced by freeze-drying with approx. 100 μm pore diameter. According to the ICP-OES results, following first 5h initial burst release, fast release of B from scaffolds was observed for 24h incubation period in conditioned medium. Then, slow release of B was performed over 120 h. The results of the cell culture studies proved that the encapsulated boron within the scaffolds can be used as an osteoinductive agent by showing its positive effects on the proliferation and differentiation of MC3T3-E1 preosteoblastic cells.

  17. Boron carbide (B4C) coating. Deposition and testing

    Science.gov (United States)

    Azizov, E.; Barsuk, V.; Begrambekov, L.; Buzhinsky, O.; Evsin, A.; Gordeev, A.; Grunin, A.; Klimov, N.; Kurnaev, V.; Mazul, I.; Otroshchenko, V.; Putric, A.; Sadovskiy, Ya.; Shigin, P.; Vergazov, S.; Zakharov, A.

    2015-08-01

    Boron carbide was proposed as a material of in-situ protecting coating for tungsten tiles of ITER divertor. To prove this concept the project including investigation of regimes of plasma deposition of B4C coating on tungsten and tests of boron carbide layer in ITER-like is started recently. The paper contends the first results of the project. The results of B4C coating irradiation by the plasma pulses of QSPU-T plasma accelerator are presented. The new device capable of B4C film deposition on tungsten and testing of the films and materials with ITER-like heat loads and ion- and electron irradiation is described. The results of B4C coating deposition and testing of both tungsten substrate and coating are shown and discussed.

  18. Structural phase transitions in boron carbide under stress

    Science.gov (United States)

    Korotaev, P.; Pokatashkin, P.; Yanilkin, A.

    2016-01-01

    Structural transitions in boron carbide B4C under stress were studied by means of first-principles molecular dynamics in the framework of density functional theory. The behavior depends strongly on degree of non-hydrostatic stress. Under hydrostatic stress continuous bending of the three-atom C-B-C chain was observed up to 70 GPa. The presence of non-hydrostatic stress activates abrupt reversible chain bending, which is displacement of the central boron atom in the chain with the formation of weak bonds between this atom and atoms in the nearby icosahedra. Such structural change can describe a possible reversible phase transition in dynamical loading experiments. High non-hydrostatic stress achieved in uniaxial loading leads to disordering of the initial structure. The formation of carbon chains is observed as one possible transition route.

  19. Single crystalline boron carbide nanobelts:synthesis and characterization

    Institute of Scientific and Technical Information of China (English)

    Bao Li-Hong; Li Chen; Tian Yuan; Tian Ji-Fa; Hui Chao; Wang Xing-Jun; Shen Cheng-Min; Gao Hong-Jun

    2008-01-01

    This paper reports that the large-scale single crystalline boron carbide nanobelts have been fabricated through a simple carbothermal reduction method with B/B203/C/Fe powder as precursors at ll00~C.Transmission electron microscopy and selected area electron diffraction characterizations show that the boron carbide nanobelt has a B4C rhomb-centred hexagonal structure with good crystallization.Electron energy loss spectroscopy analysis indicates that the nanobelt contains only B and C,and the atomic ratio of B to C is close to 4:1.High resolution transmission electron microscopy results show that the preferential growth direction of the nanobelt is [101].A possible growth mechanism is also discussed.

  20. Low-Cost Preparation of Boron Nitride Ceramic Powders

    Institute of Scientific and Technical Information of China (English)

    LI Duan; ZHANG Changrui; LI Bin; CAO Feng; WANG Siqing; LIU Kun; FANG Zhenyu

    2012-01-01

    The amorphous boron nitride ceramic powders were prepared at 750-950 ℃ by the lowcost urea route,and the effects of preparation temperatures,molar ratios of the raw materials and oxidation treatment on the composition,structure and surface morphology of the products were investigated through FTIR,XRD and SEM.The results show that the products ceramize and crystallize gradually with the increase of the temperature.When the molar ratio and reaction temperature are 3:2 and 850 ℃,respectively,the products have high purity,compact structure and nice shape.The oxidation treatment at 450 ℃ will not impair the composition and structure of boron nitfide but effectively remove the impurities.

  1. Boron-10 ABUNCL Prototype Models And Initial Active Testing

    Energy Technology Data Exchange (ETDEWEB)

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.

    2013-04-23

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Coincidence Counting With Boron-Based Alternative Neutron Detection Technology at Pacific Northwest National Laboratory (PNNL) for the development of a 3He proportional counter alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a system based upon 10B-lined proportional tubes in a configuration typical for 3He-based coincidence counter applications. This report provides results from MCNPX model simulations and initial testing of the active mode variation of the Alternative Boron-Based Uranium Neutron Coincidence Collar (ABUNCL) design built by General Electric Reuter-Stokes. Initial experimental testing of the as-delivered passive ABUNCL was previously reported.

  2. Superconductivity in heavily boron-doped silicon carbide

    Directory of Open Access Journals (Sweden)

    Markus Kriener, Takahiro Muranaka, Junya Kato, Zhi-An Ren, Jun Akimitsu and Yoshiteru Maeno

    2008-01-01

    Full Text Available The discoveries of superconductivity in heavily boron-doped diamond in 2004 and silicon in 2006 have renewed the interest in the superconducting state of semiconductors. Charge-carrier doping of wide-gap semiconductors leads to a metallic phase from which upon further doping superconductivity can emerge. Recently, we discovered superconductivity in a closely related system: heavily boron-doped silicon carbide. The sample used for that study consisted of cubic and hexagonal SiC phase fractions and hence this led to the question which of them participated in the superconductivity. Here we studied a hexagonal SiC sample, free from cubic SiC phase by means of x-ray diffraction, resistivity, and ac susceptibility.

  3. Application of proton boron fusion reaction to radiation therapy: A Monte Carlo simulation study

    Science.gov (United States)

    Yoon, Do-Kun; Jung, Joo-Young; Suh, Tae Suk

    2014-12-01

    Three alpha particles are emitted from the point of reaction between a proton and boron. The alpha particles are effective in inducing the death of a tumor cell. After boron is accumulated in the tumor region, the emitted from outside the body proton can react with the boron in the tumor region. An increase of the proton's maximum dose level is caused by the boron and only the tumor cell is damaged more critically. In addition, a prompt gamma ray is emitted from the proton boron reaction point. Here, we show that the effectiveness of the proton boron fusion therapy was verified using Monte Carlo simulations. We found that a dramatic increase by more than half of the proton's maximum dose level was induced by the boron in the tumor region. This increase occurred only when the proton's maximum dose point was located within the boron uptake region. In addition, the 719 keV prompt gamma ray peak produced by the proton boron fusion reaction was positively detected. This therapy method features the advantages such as the application of Bragg-peak to the therapy, the accurate targeting of tumor, improved therapy effects, and the monitoring of the therapy region during treatment.

  4. Electron impact ionization in plasma technologies; studies on atomic boron and BN molecule

    Science.gov (United States)

    Joshi, Foram M.; Joshipura, K. N.; Chaudhari, Asha S.

    2016-05-01

    Electron impact ionization plays important role in plasma technologies. Relevant cross sections on atomic boron are required to understand the erosion processes in fusion experiments. Boronization of plasma exposed surfaces of tokomaks has proved to be an effective way to produce very pure fusion plasmas. This paper reports comprehensive theoretical investigations on electron scattering with atomic Boron and Boron Nitride in solid phases. Presently we determine total ionization cross-section Qion and the summed-electronic excitation cross section ΣQexc in a standard quantum mechanical formalism called SCOP and CSP-ic methods. Our calculated cross sections are examined as functions of incident electron energy along with available comparisons.

  5. Selectivity of CO2 via pore space partition in zeolitic boron imidazolate frameworks.

    Science.gov (United States)

    Zhang, Hai-Xia; Liu, Min; Xu, Guilan; Liu, Liyang; Zhang, Jian

    2016-02-28

    Reported here is a versatile method capable of generating pore space partition in zeolitic boron imidazolate frameworks (BIFs), which is based on the coexistence of presynthesized boron imidazolate complexes and charge balancing carboxylate ligands. Using this method, boron imidazolate complexes are used to form zeolitic nets, while the carboxylate serves to partition large channel spaces into multiple domains. The generality of this method is shown by two distinct boron imidazolate frameworks mimicking GIS (BIF-41) and ABW (BIF-42) zeotype topologies. BIF-41 shows high selectivity sorption of CO2 over N2.

  6. Determination of boron over a large dynamic range by prompt-gamma activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, R.K. [University of Texas at Austin, Nuclear Engineering Teaching Lab., Pickle Research Campus, R-9000 Austin, TX 78712 (United States); Landsberger, S. [University of Texas at Austin, Nuclear Engineering Teaching Lab., Pickle Research Campus, R-9000 Austin, TX 78712 (United States)], E-mail: s.landsberger@mail.utexas.edu

    2009-02-15

    An evaluation of the PGAA method for the determination of boron across a wide dynamic range of concentrations was performed for trace levels up to 5 wt.% boron. This range encompasses a transition from neutron transparency to significant self- shielding conditions. To account for self-shielding, several PGAA techniques were employed. First, a calibration curve was developed in which a set of boron standards was tested and the count rate to boron mass curve was determined. This set of boron measurements was compared with an internal standard self-shielding correction method and with a method for determining composition using PGAA peak ratios. The advantages and disadvantages of each method are analyzed. The boron concentrations of several laboratory-grade chemicals and standard reference materials were measured with each method and compared. The evaluation of the boron content of nanocrystalline transition metals prepared with a boron-containing reducing agent was also performed with each of the methods tested. Finally, the k{sub 0} method was used for non-destructive measurement of boron in catalyst materials for the characterization of new non-platinum fuel cell catalysts.

  7. Boron toxicity causes multiple effects on Malus domestica pollen tube growth

    Directory of Open Access Journals (Sweden)

    Kefeng eFang

    2016-02-01

    Full Text Available Boron is an essential micronutrient for plants. However, boron is also toxic to cells at high concentrations, although the mechanism of this stress is not known. This study aimed to evaluate the effect of boron stress on Malus domestica pollen tube growth and its possible regulatory pathway. Our results show that a high concentration of boron inhibited pollen germination and tube growth and led to the morphological abnormality of pollen tubes. Fluorescent labeling coupled with a scanning ion-selective electrode technique detected that boron stress could decrease [Ca2+]c and induce the disappearance of the [Ca2+]c gradient, which are critical for pollen tube polar growth. Actin filaments were therefore altered by boron stress. Immuno-localization and fluorescence labeling, together with Fourier-transform infrared analysis (FTIR, suggested that boron stress influenced the accumulation and distribution of callose, de-esterified pectins, esterified pectins and arabinogalactan proteins in pollen tubes. All of the above results provide new insights into the regulatory role of boron in pollen tube development. In summary, boron likely plays a structural and regulatory role in relation to [Ca2+]c, actin cytoskeleton and cell wall components and thus regulates Malus domestica pollen germination and tube polar growth.

  8. Functional characterization of Citrus macrophylla BOR1 as a boron transporter.

    Science.gov (United States)

    Cañon, Paola; Aquea, Felipe; Rodríguez-Hoces de la Guardia, Amparo; Arce-Johnson, Patricio

    2013-11-01

    Plants have evolved to develop an efficient system of boron uptake and transport using a range of efflux carriers named BOR proteins. In this work we isolated and characterized a boron transporter of citrus (Citrus macrophylla), which was named CmBOR1 for its high homology to AtBOR1. CmBOR1 has 4403 bp and 12 exons. Its coding region has 2145 bp and encodes for a protein of 714 amino acids. CmBOR1 possesses the molecular features of BORs such as an anion exchanger domain and the presence of 10 transmembrane domains. Functional analysis in yeast indicated that CmBOR1 has an efflux boron transporter activity, and transformants have increased tolerance to excess boron. CmBOR1 is expressed in leaves, stem and flowers and shows the greatest accumulation in roots. The transcript accumulation was significantly increased under boron deficiency conditions in shoots. In contrast, the accumulation of the transcript did not change in boron toxicity conditions. Finally, we observed that constitutive expression of CmBOR1 was able to increase tolerance to boron deficiency conditions in Arabidopsis thaliana, suggesting that CmBOR1 is a xylem loading boron transporter. Based on these results, it was determined that CmBOR1 encodes a boric acid/borate transporter involved in tolerance to boron deficiency in plants.

  9. Boron and nucleic acid chemistries: merging the best of both worlds.

    Science.gov (United States)

    Martin, Anthony R; Vasseur, Jean-Jacques; Smietana, Michael

    2013-07-07

    At the intersection of nucleic acid and boron chemistries lies a thriving world of possibilities. During the past decades, the merging of these research domains has led to fascinating discoveries in different fields ranging from material to medical sciences. In recent years the interplay of these two worlds has gained a lot of attention, as can be judged by the increasing number of articles in which boron and nucleic acids stand out for their potential medicinal, biotechnological or analytical applications. In this review, we present an outline of this crossroads by focusing on both the interaction of boronated compounds with nucleic acids and the modification of nucleic acids by boron containing moieties.

  10. Characterization of Boron Diffusion Phenomena According to the Specific Resistivity of N-Type Si Wafer.

    Science.gov (United States)

    Lee, Woo-Jin; Choi, Chel-Jong; Park, Gye-Choon; Yang, O-Bong

    2016-02-01

    This paper is directed to characterize the boron diffusion process according to the specific resistivity of the Si wafer. N-type Si wafers were used with the specific resistivity of 0.5-3.2 omega-cm, 1.0-6.5 omega-cm and 2.0-8.0 omega-cm. The boron tribromide (BBr3) was used as boron source to create the PN junction on N-type Si wafer. The boron diffusion in N-type Si wafer was characterized by sheet resistance of wafer surface, secondary ion mass spectroscopy measurements (SIMS) and surface life time analysis. The degree of boron diffusion was depended on the variation in specific resistivity and sheet resistance of the bare N-type Si wafer. The boron diffused N-Si wafer exhibited the average junction depth of 750 nm and boron concentration of 1 x 10(19). N-type Si wafer with the different specific resistance considerably affected the boron diffusion length and life time of Si wafer. It was found that the lifetime of boron diffused wafer was proportional to the sheet resistance and resistivity. However, optimization process may necessary to achieve the high efficiency through the high sheet resistance wafer, because the metallization process control is very sensitive.

  11. The possibility of the boronizing process on the pressed samples of iron powder

    Directory of Open Access Journals (Sweden)

    Požega Emina D.

    2009-01-01

    Full Text Available The paper presents results of the experimental investigation of the boronizing process on nonsintering iron powder samples (NC100.24, Höganäs, Sweden. Experiments are planned within the limits of applicability of simultaneous sintering at chemical-thermal treatment process (boronizing. The simlex plan of 15 experimental points was used for the experiment, while a polynomial function of fourth degree was employed in the modeling of a mixture composition based on the volume changes, porosity and the depth layer changes. Boronizing was carried out in mixture with born carbide by addition of ammonium bifluoride, ammonium chloride and boron potassium fluoride as activators, by proportion definited plan.

  12. Hückel's Rule of Aromaticity Categorizes Aromatic Closo Boron Hydride Clusters

    OpenAIRE

    Poater i Teixidor, Jordi; Solà i Puig, Miquel; Viñas, Clara; Teixidor, Francesc

    2016-01-01

    A direct connection is established between tridimensional aromatic closo boron hydride clusters and planar aromatic [n]annulenes for medium and large size boron clusters. In particular, our results prove the existence of a link between the two-dimensional Hückel rule followed by aromatic [n]-annulenes and Wade-Mingos' rule of three-dimensional aromaticity applied to the aromatic [BnHn]2- closo boron hydride clusters. Our results show that closo boron hydride clusters can be categorized into d...

  13. Boron stress activates the general amino acid control mechanism and inhibits protein synthesis.

    Directory of Open Access Journals (Sweden)

    Irem Uluisik

    Full Text Available Boron is an essential micronutrient for plants, and it is beneficial for animals. However, at high concentrations boron is toxic to cells although the mechanism of this toxicity is not known. Atr1 has recently been identified as a boron efflux pump whose expression is upregulated in response to boron treatment. Here, we found that the expression of ATR1 is associated with expression of genes involved in amino acid biosynthesis. These mechanisms are strictly controlled by the transcription factor Gcn4 in response to boron treatment. Further analyses have shown that boron impaired protein synthesis by promoting phosphorylation of eIF2α in a Gcn2 kinase dependent manner. The uncharged tRNA binding domain (HisRS of Gcn2 is necessary for the phosphorylation of eIF2α in the presence of boron. We postulate that boron exerts its toxic effect through activation of the general amino acid control system and inhibition of protein synthesis. Since the general amino acid control pathway is conserved among eukaryotes, this mechanism of boron toxicity may be of general importance.

  14. Investigations into thermoluminescence and afterglow characterization of strontium aluminates with boron-modification and reductions via sol-gel route

    Institute of Scientific and Technical Information of China (English)

    Ⅰ-Cherng Chen; Ker-Kong Chen; Hong-Sen Chen; Je-kang Du; Tsao-Jen Lin; Shiu-Shiung Lin; Teng-Ming Chen; Tien-Yu Shieh

    2012-01-01

    The effects of strontium aluminates of SrAl2O4:Eu2+,Dy3+ (SAED) and boron-modified SAED (BSAED) phases synthesized from a sol-gel process on thermoluminescence (TL) along with their afterglow properties were systematically investigated with thermal activation in the different atmospheres.The result showed that the addition of boron and the reduction routes of Eu3+ to Eu2+ in SrAl2O4:Dy3+ were related to the phosphorescent decay properties.The aid of Dy3+ to induce the hole-trapping effect required both SAED and BSAED to be heated at 1300 ℃ under the H2/N2 (5%:95%) atmosphere.However,the trapping behavior of the reductions of SAED in nitrogen was similar to the compound without Dy3+ co-doping SrAl2O4:Eu2+ (SAE) in H2/N2 (5%:95%).BSAED showed deeper traps in situ compared to SAED which contained no boron,and this led to the better afterglow properties of BSAED than those of SAED.The afterglow spectrum of BSAED showed two peaks at 400+1 nm and 4854±1 nm,which were two individuals composed and contributed from different depths of traps at 0.57 and 0.76 eV,accordingly.The depth of the traps was calculated from the Hoogenstraaten's plot of glow curves.The calculations for SAED and SAE were at around 0.43 and 0.18 eV,respectively.

  15. Boron Clusters as Highly Stable Magnesium-Battery Electrolytes**

    OpenAIRE

    Carter, Tyler J; Mohtadi, Rana; Arthur, Timothy S.; Mizuno, Fuminori; Zhang, Ruigang; Shirai, Soichi; Kampf, Jeff W.

    2014-01-01

    Boron clusters are proposed as a new concept for the design of magnesium-battery electrolytes that are magnesium-battery-compatible, highly stable, and noncorrosive. A novel carborane-based electrolyte incorporating an unprecedented magnesium-centered complex anion is reported and shown to perform well as a magnesium-battery electrolyte. This finding opens a new approach towards the design of electrolytes whose likelihood of meeting the challenging design targets for magnesium-battery electro...

  16. Observation of viscoelasticity in boron nitride nanosheet aerogel.

    Science.gov (United States)

    Zeng, Xiaoliang; Ye, Lei; Sun, Rong; Xu, Jianbin; Wong, Ching-Ping

    2015-07-14

    The viscoelasticity of boron nitride nanosheet (BNNS) aerogel has been observed and investigated. It is found that the BNNS aerogel has a high damping ratio (0.2), while it exhibits lightweight and negligible temperature dependence below 180 °C. The creep behavior of the BNNS aerogel markedly demonstrates its strain dependence on stress magnitude and temperature, and can be well simulated by the classical models.

  17. Mechanism of boron uptake by hydrocalumite calcined at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Xinhong, E-mail: qxinhong@gmail.com [Department of Earth Resources Engineering, Kyushu University,Fukuoka 819-0395 (Japan); Sasaki, Keiko; Takaki, Yu; Hirajima, Tsuyoshi [Department of Earth Resources Engineering, Kyushu University,Fukuoka 819-0395 (Japan); Ideta, Keiko; Miyawaki, Jin [Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga 816-8180 (Japan)

    2015-04-28

    Highlights: • Higher sorption density of borate was observed at higher calcination temperature. • Sorption of borate by Ca-Al-LDH was mainly through DR mechanism. • Removal of borate by Ca-LDH-300 and Ca-LDH-500 were through forming of ettringite. • Boron was mainly adsorbed and intercalated into hydration of Ca-Al-LDH-900. - Abstract: Hydrocalumite (Ca-Al-layered double hydroxide (LDH)) was prepared and applied for the removal of borate. The properties of Ca-Al-LDH calcined at different temperatures were diverse, which affected the sorption density and mechanism of boron species. The sorption density increased with increase in calcined temperature and the sample calcined at 900 °C (Ca-Al-LDH-900) showed the maximum sorption density in this work. The solid residues after sorption were characterized by {sup 11}B NMR, {sup 27}Al NMR, SEM, and XRD to investigate the sorption mechanism. Dissolution–reprecipitation was the main mechanism for sorption of borate in Ca-Al-LDH. For Ca-Al-LDH calcined at 300 and 500 °C, regeneration occurred in a short time and the newly forming LDHs were decomposed to release Ca{sup 2+} ions and formed ettringite with borate. Two stages occurred in the sorption of boron by Ca-Al-LDH calcined at 900 °C. In the first stage, boron species adsorbed on the alumina gel resulting from the hydration of calcined products. In this stage, borate was included as an interlayer anion into the newly forming LDHs in the following stage, and then immobilized as HBO{sub 3}{sup 2−} into the interlayer, most the LDHs.

  18. Characterization of a Boron Carbide Heterojunction Neutron Detector

    Science.gov (United States)

    2011-03-24

    1969. [82] J. W. McClory, The Effect of Radiation on the Electrical Poperties of Aluminum Gallium Nitride / Gallium Nitrude Heterostructures, 2008...the possible limitations that can guide future development and provide a rough benchmark of what can be expected in terms of radiation hardness ...icosahedral boron-rich solids have also indicated a high level of radiation hardness [26]. As shown in Figure 26, even in experiments where

  19. Precision Morphology in Sulfonic, Phosphonic, Boronic, and Carboxylic Acid Polyolefins

    Science.gov (United States)

    2013-11-15

    Science Part A: Polymer Chemistry , (02 2011): 0. doi: 10.1002/pola.24491 Number of Papers published in peer-reviewed journals: (b) Papers published in...Wagener. Effects of Boron-Containing Lewis Acids on Olefin Metathesis, Organometallics , (05 2013): 0. doi: 10.1021/om400257b Michael D. Schulz, Rachel R...Ford, Kenneth B. Wagener. Insertion metathesis depolymerization, Polymer Chemistry , (05 2013): 0. doi: 10.1039/c3py00531c Pascale Atallah, Kenneth

  20. Separation of the isotopes of boron by chemical exchange reactions

    Energy Technology Data Exchange (ETDEWEB)

    McCandless, F.P.; Herbst, R.S.

    1995-05-30

    The isotopes of boron, {sup 10}B and {sup 11}B, are separated by means of a gas-liquid chemical exchange reaction involving the isotopic equilibrium between gaseous BF{sub 3} and a liquid BF{sub 3} donor molecular addition complex formed between BF{sub 3} gas and a donor chosen from the group consisting of: nitromethane, acetone, methyl isobutyl ketone, or diisobutyl ketone. 1 Fig.

  1. Promotion of the Growth of Boron-Carbide Nanowires

    Science.gov (United States)

    Kranov, Yanko; Zhang, Daqing; McIlroy, David; Norton, Grant

    2000-03-01

    Boron carbide, is a wide bandgap semiconductor (2.1eV) with a high melting temperature in excess of 2400^circC. Initial studies indicate that nanowires of boron carbide approximately 25 ~30 μm in length and less than 100 nm in diameter can be grown by the technique of plasma enhanced chemical vapor deposition by a mode of the vapor-liquid-solid mechanism [1] at relatively low temperatures ( ~1150^circC). Through the use of boron based eutectics such as FeB, NiB and PtB nanowire growth at temperatures below 1150^circC. These metal borides have successively lower melting temperatures, respectively. In this paper we will discuss a simple technique for making submicron metal boride particles, as well as a simple means of depositing them onto a surface. In addition, the effect of droplet size on nanowire diameter and the stability of the size of the metal boride droplet during growth will be discussed. These studies demonstrate that the surface can be selectively seeded thereby controlling the location of the nanowires, i.e. select area deposition. Lastly, the techniques and materials used to grow boron carbide nanowires can easily be used to grow other types of nanowires, as well as carbon nanotubes. [1]. D. N. McIlroy, Daqing Zhang, Robert M. Cohen, J. Wharton, Yongjun Geng, M. Grant Norton, G. De Stasio, B.Gilbert, L.Perfetti, J.H.Streiff, B.Broocks and J.L. McHale, Phys. Rev. B 60 (1999) 4874

  2. Synthesis of boron nitride nanotubes and their applications

    OpenAIRE

    Saban Kalay; Zehra Yilmaz; Ozlem Sen; Melis Emanet; Emine Kazanc; Mustafa Çulha

    2015-01-01

    Boron nitride nanotubes (BNNTs) have been increasingly investigated for use in a wide range of applications due to their unique physicochemical properties including high hydrophobicity, heat and electrical insulation, resistance to oxidation, and hydrogen storage capacity. They are also valued for their possible medical and biomedical applications including drug delivery, use in biomaterials, and neutron capture therapy. In this review, BNNT synthesis methods and the surface modification stra...

  3. NIR Electrofluorochromic Properties of Aza-Boron-dipyrromethene Dyes

    OpenAIRE

    2016-01-01

    The photophysical properties of near-infrared (NIR) emissive aza-boron-dipyrromethene (aza-BDP) dyes incorporating nitrofluorene and alkoxy decorations were intensively investigated. Their highly reversible one-electron reduction process showed characteristic electrofluorochromic (EF) properties in the NIR range, depending on the substituents. The nitrofluorene ethynyl-substituted (Type I) dyes showed smaller EF effects than the alkoxy-containing (Type II) dyes because of the difference in th...

  4. Program and Abstracts, Boron Americas IX Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Feakes, Debra A.

    2006-08-09

    The Scientific and Technical Information (STI) submitted includes the final report and a collection of abstracts for the Ninth Boron in the Americas Conference which was held May 19-22, 2004, in San Marcos, Texas. The topics covered in the abstracts include: Application in Medicine, Application in Organic Synthesis and Catalysis, Boranes and Carboranes, Materials and Polymers, Metallaboranes and Metallacarboranes, Organoboron Compounds, Synthesis and Catalysis, and Theoretical Studies. Attendees represented researchers from government, industry, and academia.

  5. Simulation of swift boron clusters traversing amorphous carbon foils

    OpenAIRE

    Heredia Ávalos, Santiago; Abril Sánchez, Isabel; Denton Zanello, Cristian D.; García Molina, Rafael

    2007-01-01

    We use a simulation code to study the interaction of swift boron clusters (Bn+, n=2–6, 14) with amorphous carbon foils. We analyze different aspects of this interaction, such as the evolution of the cluster structure inside the target, the energy and angle distributions at the detector or the stopping power ratio. Our simulation code follows in detail the motion of the cluster fragments through the target and in the vacuum until reaching a detector, taking into account the following interacti...

  6. Concentrations of boron, molybdenum, and selenium in chinook salmon

    Science.gov (United States)

    Hamilton, Steven J.; Wiedmeyer, Raymond H.

    1990-01-01

    The concentrations of boron, molybdenum, and selenium in young chinook salmon Oncorhynchus tshawytscha were determined in three partial life cycle chronic toxicity studies. In each study, fish were exposed to a mixture of boron, molybdenum, selenate, and selenite in the proportions found in subsurface agricultural drainage water in the basin of the San Joaquin Valley, California. Tests were conducted in well water and in site-specific fresh and brackish waters. No boron or molybdenum was detected in fish exposed to concentrations as high as 6,046 μg boron/L and 193 μg molybdenum/L for 90 d in well water or fresh water; however, whole-body concentrations of selenium increased with increasing exposure concentrations in well water and fresh water, but not in brackish water. Concentrations of selenium in chinook salmon were strongly correlated with reduced survival and growth of fish in well water and with reduced survival in a 15-d seawater challenge test of fish from fresh water. Concentrations of selenium in fish seemed to reach a steady state after 60 d of exposure in well water or fresh water. Fish in brackish water had only background concentrations of selenium after 60 d of exposure, and no effects on survival and growth in brackish water or on survival in a 10-d seawater challenge test were exhibited. This lack of effect in brackish water was attributed to initiation of the study with advanced fry, which were apparently better able to metabolize the trace element mixture than were the younger fish used in studies with well water and fresh water. In all three experimental waters, concentration factors (whole-body concentration/waterborne concentration) for selenium decreased with increasing exposure concentrations, suggesting decreased uptake or increased excretion, or both, of selenium at the higher concentrations.

  7. Electronic structure of spontaneously strained graphene on hexagonal Boron Nitride

    OpenAIRE

    San-Jose, Pablo; Gutiérrez, Ángel; Sturla, Mauricio; Guinea, Francisco

    2014-01-01

    Hexagonal Boron Nitride substrates have been shown to dramatically improve the electric properties of graphene. Recently, it has been observed that when the two honeycomb crystals are close to perfect alignment, strong lattice distortions develop in graphene due to the moir\\'e adhesion landscape. Simultaneously a gap opens at the Dirac point. Here we derive a simple low energy model for graphene carriers close to alignment with the substrate, taking into account spontaneous strains at equilib...

  8. Method for forming monolayer graphene-boron nitride heterostructures

    Science.gov (United States)

    Sutter, Peter Werner; Sutter, Eli Anguelova

    2016-08-09

    A method for fabricating monolayer graphene-boron nitride heterostructures in a single atomically thin membrane that limits intermixing at boundaries between graphene and h-BN, so as to achieve atomically sharp interfaces between these materials. In one embodiment, the method comprises exposing a ruthenium substrate to ethylene, exposing the ruthenium substrate to oxygen after exposure to ethylene and exposing the ruthenium substrate to borazine after exposure to oxygen.

  9. Coffee leaf and stem anatomy under boron deficiency

    OpenAIRE

    Rosolem,Ciro Antonio; Leite, Vagner Maximino [UNESP

    2007-01-01

    Boron deficiency in coffee is widely spread in Brazilian plantations, but responses to B fertilizer have been erratic, depending on the year, form and time of application and B source. A better understanding of the effects of B on plant physiology and anatomy is important to establish a rational fertilization program since B translocation within the plant may be affected by plant anatomy. In this experiment, coffee plantlets of two varieties were grown in nutrient solutions with B levels of 0...

  10. Rotary Ultrasonic Machining of Poly-Crystalline Cubic Boron Nitride

    OpenAIRE

    2014-01-01

    Poly-crystalline cubic boron nitride (PCBN) is one of the hardest material. Generally, so hard materials could not be machined by conventional machining methods. Therefore, for this purpose, advanced machining methods have been designed. Rotary ultrasonic machining (RUM) is included among them. RUM is based on abrasive removing mechanism of ultrasonic vibrating diamond particles, which are bonded on active part of rotating tool. It is suitable especially for machining hard and brittle materia...

  11. Phonon spectrum of single-walled boron nitride nanotubes

    Institute of Scientific and Technical Information of China (English)

    Xiao Yang; Yan Xiao-Hong; Cao Jue-Xian; Mao Yu-Liang; Xiang Jun

    2004-01-01

    Based on a force constant model, we investigated the phonon spectrum and then specific heat of single-walled boron nitride nanotubes. The results show that the frequencies of Raman and infrared active modes decrease with increasing diameter in the low frequency, which is consistent with the results calculated by density functional theory.The fitting formulae for diameter and chirality dependence of specific heat at 300K are given.

  12. Boron doped simulated graphene field effect transistor model

    Science.gov (United States)

    Sharma, Preetika; Kaur, Inderpreet; Gupta, Shuchi; Singh, Sukhbir

    2016-05-01

    Graphene based electronic devices due to its unique properties has transformed electronics. A Graphene Field Effect Transistor (GNRFET) model is simulated in Virtual Nano Lab (VNL) and the calculations are based on density functional theory (DFT). Simulations were performed on this pristine GNRFET model and the transmission spectrum was observed. The graph obtained showed a uniform energy gap of +1 to -1eV and the highest transmission peak at -1.75 eV. To this pristine model of GNRFET, doping was introduced and its effect was seen on the Fermi level obtained in the transmission spectrum. Boron as a dopant was used which showed variations in both the transmission peaks and the energy gap. In this model, first the single boron was substituted in place of carbon and Fermi level showed an energy gap of 1.5 to -0.5eV with the highest transmission peak at -1.3 eV. In another variation in the model, two carbon atoms were replaced by two boron atoms and Fermi level shifted from 2 to 0.25eV. In this observation, the highest transmission peak was observed at -1(approx.). The use of nanoelectronic devices have opened many areas of applications as GFET is an excellent building block for electronic circuits, and is being used in applications such as high-performance frequency doublers and mixers, digital modulators, phase detectors, optoelectronics and spintronics.

  13. Boron-Based Layered Structures for Energy Storage

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Y.; Wei, S. H.

    2012-01-01

    Based on Density Functional Theory simulations, we have studied the boron-based graphite-like materials, i.e., LiBC and MgB2 for energy storage. First, when half of the Li-ions in the LiBC are removed, the BC layered structure is still preserved. The Li intercalation potential (equilibrium lithium-insertion voltage of 2.3-2.4 V relative to lithium metal) is significantly higher than that in graphite, allowing Li0.5BC to function as a cathode material. The reversible electrochemical reaction, LiBC = Li0.5BC + 0.5Li, enables a specific energy density of 1088 Wh/kg and a volumetric energy density of 2463 Wh/L. Second, 75% of the Mg ions in MgB2 can be removed and reversibly inserted with the layered boron structures being preserved through an in-plane topological transformation between the hexagonal lattice domains and triangular domains. The mechanism of such a charge-driven transformation originates from the versatile valence state of boron in its planar form.

  14. A Search for Boron in Damped Ly{\\alpha} Systems

    CERN Document Server

    Berg, Trystyn A M; Venn, Kim A; Prochaska, J Xavier

    2013-01-01

    We present the first systematic study of boron beyond the Local Group. This analysis is performed on a sample of 30 damped Ly{\\alpha} systems (DLAs) with strong metal-lines, which are expected to trace the interstellar medium of high z galaxies. We report on two boron detections at > 3{\\sigma} significance; one new detection and one confirmation. The ratios of B/O and, for the first time, B/S are compared with previous stellar and interstellar measurements in the Milky Way and Small Magellanic Cloud. The novel comparison with sulphur, which tracks oxygen's abundance, alleviates the uncertainty associated with stellar oxygen measurements. For both detections, the inferred B/S ratio is in excess of the prediction of primary boron production from spallation processes. Possible sources of contamination are discussed, as well as physical effects that could impact the observed ratios. However taken at face value, the implication of these measurements suggest potentially higher cosmic ray fluxes in DLAs. The prospec...

  15. Carborane derivative development for boron neutron capture therapy. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Barnum, Beverly A.; Yan Hao; Moore, Roger; Hawthorne, M. Frederick; Baum, Kurt

    1999-04-01

    Boron Neutron Capture Therapy [BNCT] is a binary method of cancer therapy based on the capture of neutrons by a boron-10 atom [{sup 10}B]. Cytotoxic {sup 7}Li nuclei and {alpha}-particles are emitted, with a range in tissue of 9 and 5 {micro}m, respectively, about one cell diameter. The major obstacle to clinically viable BNCT is the selective localization of 5-30 ppm {sup 10}B in tumor cells required for effective therapy. A promising approach to BNCT is based on hydrophilic boron-rich oligomeric phosphate diesters, or ''trailers'' that have been shown to concentrate selectively in tumor tissue. Examples of these compounds were prepared previously at high cost using an automated DNA synthesizer. Direct synthesis methods are needed for the production of gram-scale quantities for further biological evaluation. The work accomplished as a result of the collaboration between Fluorochem, Inc. and UCLA demonstrates that short oligomers containing at least five carborane units with four phosphodiester linkages can be prepared in substantial quantities. This work was accomplished by the application of standard phosphoramidite coupling chemistry.

  16. Termite Resistance of MDF Panels Treated with Various Boron Compounds

    Directory of Open Access Journals (Sweden)

    Sedat Ondaral

    2009-06-01

    Full Text Available In this study, the effects of various boron compounds on the termite resistance of MDF panels were evaluated. Either borax (BX, boric acid (BA, zinc borate (ZB, or sodium perborate tetrahydrate (SPT were added to urea-formaldehyde (UF resin at target contents of 1%, 1.5%, 2% and 2.5% based on dry fiber weight. The panels were then manufactured using 12% urea-formaldehyde resin and 1% NH4Cl. MDF samples from the panels were tested against the subterranean termites, Coptotermes formosanus Shiraki. Laboratory termite resistance tests showed that all samples containing boron compounds had greater resistance against termite attack compared to untreated MDF samples. At the second and third weeks of exposure, nearly 100% termite mortalities were recorded in all boron compound treated samples. The highest termite mortalities were determined in the samples with either BA or BX. Also, it was found that SPT showed notable performance on the termite mortality. As chemical loadings increased, termite mortalities increased, and at the same time the weight losses of the samples decreased.

  17. Tribological properties of boron nitride synthesized by ion beam deposition

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.; Spalvins, T.

    1985-01-01

    The adhesion and friction behavior of boron nitride films on 440 C bearing stainless steel substrates was examined. The thin films containing the boron nitride were synthesized using an ion beam extracted from a borazine plasma. Sliding friction experiments were conducted with BN in sliding contact with itself and various transition metals. It is indicated that the surfaces of atomically cleaned BN coating film contain a small amount of oxides and carbides, in addition to boron nitride. The coefficients of friction for the BN in contact with metals are related to the relative chemical activity of the metals. The more active the metal, the higher is the coefficient of friction. The adsorption of oxygen on clean metal and BN increases the shear strength of the metal - BN contact and increases the friction. The friction for BN-BN contact is a function of the shear strength of the elastic contacts. Clean BN surfaces exhibit relatively strong interfacial adhesion and high friction. The presence of adsorbates such as adventitious carbon contaminants on the BN surfaces reduces the shear strength of the contact area. In contrast, chemically adsorbed oxygen enhances the shear strength of the BN-BN contact and increases the friction.

  18. Methods of Boron-carbon Deposited Film Removal

    Science.gov (United States)

    Airapetov, A.; Terentiev, V.; Voituk, A.; Zakharov, A.

    Boron carbide was proposed as a material for in-situ renewable protecting coating for tungsten tiles of the ITER divertor. It is necessary to develop a method of gasification of boron-carbon film which deposits during B4C sputtering. In this paper the results of the first stage investigation of gasification methods of boron-carbon films are presented. Two gasification methods of films are investigated: interaction with the ozone-oxygen mixture and irradiation in plasma with the working gas composed of oxygen, ethanol, and, in some cases, helium. The gasification rate in the ozone-oxygen mixture at 250 °C for B/C films with different B/C ratio and carbon fiber composite (CFC), was measured. For B/C films the gasification rate decreased with increasing B/C ratio (from 45 nm/h at B/C=0.7 to 4 nm/h at B/C=2.1; for CFC - 15 μm/h). Films gasification rates were measured under ion irradiation from ethanol-oxygen-helium plasma at different temperatures, with different ion energies and different gas mixtures. The maximum obtained removal rate was near 230 nm/h in case of ethanol-oxygen plasma and at 150°C of the sample temperature.

  19. Study of helium embrittlement in boron doped EUROFER97 steels

    Science.gov (United States)

    Gaganidze, E.; Petersen, C.; Aktaa, J.

    2009-04-01

    To simulate helium effects in Reduced Activation Ferritic/Martensitic steels, experimental heats ADS2, ADS3 and ADS4 with the basic composition of EUROFER97 (9%Cr-WVTa) were doped with different contents of natural boron and separated 10B-isotope (0.008-0.112 wt.%) and irradiated in High Flux Reactor (HFR) Petten up to 16.3 dpa at 250-450 °C and in Bor-60 fast reactor in Dimitrovgrad up to 31.8 dpa at 332-338 °C. The embrittlement and hardening are investigated by instrumented Charpy-V tests with subsize specimens. Complete burn-up of 10B isotope under neutron irradiation in HFR Petten led to generation of 84, 432 and 5580 appm He and partial boron-to-helium transformation in Bor-60 led to generation of 9, 46, 880 appm He in ADS2, ADS3 and ADS4 heats, respectively. At low irradiation temperatures Tirr ⩽ 340 °C the boron doped steels show progressive embrittlement with increasing helium amount. Irradiation induced DBTT shift of EUROFER97 based heat doped with 1120 wppm separated 10B isotope could not be quantified due to large embrittlement found in the investigated temperature range. At Tirr ⩽ 340 °C helium induced extra embrittlement is attributed to material hardening induced by helium bubbles and described in terms of phenomenological model.

  20. Embedding Ba Monolayers and Bilayers in Boron Carbide Nanowires

    Science.gov (United States)

    Yu, Zhiyang; Luo, Jian; Shi, Baiou; Zhao, Jiong; Harmer, Martin P.; Zhu, Jing

    2015-11-01

    Aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) was employed to study the distribution of barium atoms on the surfaces and in the interiors of boron carbide based nanowires. Barium based dopants, which were used to control the crystal growth, adsorbed to the surfaces of the boron-rich crystals in the form of nanometer-thick surficial films (a type of surface complexion). During the crystal growth, these dopant-based surface complexions became embedded inside the single crystalline segments of fivefold boron-rich nanowires collectively, where they were converted to more ordered monolayer and bilayer modified complexions. Another form of bilayer complexion stabilized at stacking faults has also been identified. Numerous previous works suggested that dopants/impurities tended to segregate at the stacking faults or twinned boundaries. In contrast, our study revealed the previously-unrecognized possibility of incorporating dopants and impurities inside an otherwise perfect crystal without the association to any twin boundary or stacking fault. Moreover, we revealed the amount of barium dopants incorporated was non-equilibrium and far beyond the bulk solubility, which might lead to unique properties.