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Sample records for boron 16

  1. 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...

  2. 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, ...

  3. PREFACE: The 16th International Symposium on Boron, Borides and Related Materials (ISBB 2008)

    Science.gov (United States)

    Tanaka, Takaho

    2009-07-01

    This volume of Journal of Physics: Conference Series contains invited and contributed peer-reviewed papers that were presented at the 16th International Symposium on Boron, Borides and Related Materials (ISBB 2008), which was held on 7-12 September 2008, at Kunibiki Messe, Matsue, Japan. This triennial symposium has a half-century long history starting from the 1st meeting in 1959 at Asbury Park, New Jersey. We were very pleased to organize ISBB 2008, which gathered chemists, physicists, materials scientists as well as diamond and high-pressure researchers. This meeting had a strong background in the boron-related Japanese research history, which includes the discovery of superconductivity in MgB2 and development of Nd-Fe-B hard magnets and of YB66 soft X-ray monochromator. The scope of ISBB 2008 spans both basic and applied interdisciplinary research that is centered on boron, borides and related materials, and the collection of articles defines the state of the art in research on these materials. The topics are centered on: 1. Preparation of new materials (single crystals, thin films, nanostructures, ceramics, etc) under normal or extreme conditions. 2. Crystal structure and chemical bonding (new crystal structures, nonstoichiometry, defects, clusters, quantum-chemical calculations). 3. Physical and chemical properties (band structure, phonon spectra, superconductivity; optical, electrical, magnetic, emissive, mechanical properties; phase diagrams, thermodynamics, catalytic activity, etc) in a wide range of temperatures and pressures. 4. Applications and prospects (thermoelectric converters, composites, ceramics, coatings, etc) There were a few discoveries of new materials, such as nanomaterials, and developments in applications. Many contributions were related to 4f heavy Fermion systems of rare-earth borides. Exotic mechanisms of magnetism and Kondo effects have been discussed, which may indicate another direction of development of boride. Two special sessions

  4. 1,6-asymmetric induction in boron-mediated aldol reactions: application to a practical total synthesis of (+)-discodermolide.

    Science.gov (United States)

    Paterson, Ian; Delgado, Oscar; Florence, Gordon J; Lyothier, Isabelle; Scott, Jeremy P; Sereinig, Natascha

    2003-01-01

    By relying solely on substrate-based stereocontrol, a practical total synthesis of the microtubule-stabilizing anticancer agent (+)-discodermolide has been realized. This exploits a novel aldol bond construction with 1,6-stereoinduction from the boron enolate of (Z)-enone 3 in addition to aldehyde 2. The 1,3-diol 7 is employed as a common building block for the C(1)-C(5), C(9)-C(16), and C(17)-C(24) subunits. [reaction--see text

  5. Probing the structures of neutral boron clusters using infrared/vacuum ultraviolet two color ionization: B[sub 11], B[sub 16], and B[sub 17

    NARCIS (Netherlands)

    Romanescu, C.; Harding, D. J.; Fielicke, A.; Wang, L. S.

    2012-01-01

    The structures of neutral boron clusters, B11, B16, and B17, have been investigated using vibrational spectroscopy and ab initio calculations. Infrared absorption spectra in the wavelength range of 650 to 1550 cm−1 are obtained for the three neutral boron clusters from the enhancement of their near-

  6. Probing the structures of neutral boron clusters using infrared/vacuum ultraviolet two color ionization: B11, B16, and B17

    Science.gov (United States)

    Romanescu, Constantin; Harding, Dan J.; Fielicke, André; Wang, Lai-Sheng

    2012-07-01

    The structures of neutral boron clusters, B11, B16, and B17, have been investigated using vibrational spectroscopy and ab initio calculations. Infrared absorption spectra in the wavelength range of 650 to 1550 cm-1 are obtained for the three neutral boron clusters from the enhancement of their near-threshold ionization efficiency at a fixed UV wavelength of 157 nm (7.87 eV) after resonant absorption of the tunable infrared photons. All three clusters, B11, B16, and B17, are found to possess planar or quasi-planar structures, similar to their corresponding anionic counterparts (Bn-), whose global minima were found previously to be planar, using photoelectron spectroscopy and theoretical calculations. Only minor structural changes are observed between the neutral and the anionic species for these three boron clusters.

  7. 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.

  8. Electroextraction of boron from boron carbide scrap

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Ashish [Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102 (India); Anthonysamy, S., E-mail: sas@igcar.gov.in [Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102 (India); Ghosh, C. [Physical Metallurgy Group, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102 (India); Ravindran, T.R. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102 (India); Divakar, R.; Mohandas, E. [Physical Metallurgy Group, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102 (India)

    2013-10-15

    Studies were carried out to extract elemental boron from boron carbide scrap. The physicochemical nature of boron obtained through this process was examined by characterizing its chemical purity, specific surface area, size distribution of particles and X-ray crystallite size. The microstructural characteristics of the extracted boron powder were analyzed by using scanning electron microscopy and transmission electron microscopy. Raman spectroscopic examination of boron powder was also carried out to determine its crystalline form. Oxygen and carbon were found to be the major impurities in boron. Boron powder of purity ∼ 92 wt. % could be produced by the electroextraction process developed in this study. Optimized method could be used for the recovery of enriched boron ({sup 10}B > 20 at. %) from boron carbide scrap generated during the production of boron carbide. - Highlights: • Recovery of {sup 10}B from nuclear grade boron carbide scrap • Development of process flow sheet • Physicochemical characterization of electroextracted boron • Microscopic examination of electroextracted boron.

  9. Banishing brittle bones with boron

    Energy Technology Data Exchange (ETDEWEB)

    A 6-month study indicates that boron, not even considered an essential nutrient for people and animals, may be a key to preventing osteoporosis, say nutritionist Forrest H. Nielsen and anatomist Curtiss D. Hunt at ARS' Grand Forks, North Dakota, Human Nutrition Research Center. They believe the results of the study - the first to look at the nutritional effects of boron in humans - will generate a lot of interest in the element. In the study, 12 postmenopausal women consumed a very low boron diet (0.25 milligrams per day) for 17 weeks then were given a daily 3-mg supplement - representing the boron intake from a well-balanced diet - for 7 more weeks. Within 8 days after the supplement was introduced, the lost 40 percent less calcium, one-third less magnesium, and slightly less phosphorus through the urine. In fact, their calcium and magnesium losses were lower than prestudy levels, when they were on their normal diets. Since boron isn't considered essential for people, there is not recommended intake and no boron supplement on the market. Nielsen says the supplement of sodium borate used in the study was specially prepared based on the amount of boron a person would get from a well-balanced diet containing fruits and vegetables. He says the average boron intake is about 1.5 mg - or half the experimental dose - but average means a lot of people get less and a lot get more. Hunt cautioned that large doses of boron can be toxic, even lethal. The lowest reported lethal dose of boric acid is about 45 grams (1.6 ounces) for an adult and only 2 grams (0.07 ounce) for an infant.

  10. MicroPET image of radiolabeled boron compound {sup 124}I-BPA in C57BL/6 mouse bearing B16-F10 melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Ki-Jung; Kim, Woo-Jung [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Kim, Mi-Sook; Chun, Kwon-Soo; Cheon, Gi-Jeong [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

    2006-07-01

    Boron Neutron Capture therapy(BNCT) uses thermal or epithermal neutron source to bombard {sup 10}B atoms inside cancer tissue and this produces short-range alpha particles via a nuclear reaction that are able to kill tumor cells effectively. Preclinical and clinical trials have been conducted in the USA, Europe and Japan using {sup 10}B containing compounds such as BPA or BSH. This success will mainly depend on a differential uptake of {sup 10}B-BPA between tumor and normal tissue. According to Soloway et al. (1998), a tumor-to-normal tissue uptake ratio (T/N) of 3:1 is desirable. However, it is difficult to directly measure {sup 10}B levels at the time of BNCT. Many researchers used radioactive analogs of {sup 10}B ([{sup 18}F]-FBPA) as a probe to analyze its kinetics in vivo using PET. However, the production of {sup 18}FBPA is more difficult than that of {sup 124}I-BPA and its half life is too short. The aim of our study obtain to image C57BL/6 mice bearing melanoma on the thigh by a small animal PET scanner(microPET) using {sup 124}I-BPA instead of {sup 18}F-BPA and to calculate boron contents by the radioactivity in the tumor and the blood.

  11. 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.

  12. 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.

  13. First boronization in KSTAR: Experiences on carborane

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Suk-Ho, E-mail: sukhhong@nfri.re.kr [National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon 305-333 (Korea, Republic of); Center for Edge Plasma Science (cEps), Hanyang University, Seoul 133-791 (Korea, Republic of); Lee, Kun-Su; Kim, Kwang-Pyo; Kim, Kyung-Min; Kim, Hong-Tack [National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon 305-333 (Korea, Republic of); Sun, Jong-Ho; Woo, Hyun-Jong [Center for Edge Plasma Science (cEps), Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Electrical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Park, Jae-Min [National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon 305-333 (Korea, Republic of); Park, Eun-Kyong [Center for Edge Plasma Science (cEps), Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Electrical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Woong-Chae; Kim, Hak-Kun; Park, Kap-Rai; Yang, Hyung-Lyeol; Oh, Yeong-Kook; Na, Hoon-Kyun [National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon 305-333 (Korea, Republic of); Lho, Taehyeop [National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon 305-333 (Korea, Republic of); Center for Edge Plasma Science (cEps), Hanyang University, Seoul 133-791 (Korea, Republic of); Chung, Kyu-Sun [Center for Edge Plasma Science (cEps), Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Electrical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2011-08-01

    First boronization was performed in KSTAR tokamak during 2009 campaign in order to reduce oxygen impurities and to lower the power loss due to radiation. We report the results from the experiences on carborane during the first boronization in KSTAR. After the boronization, H{sub 2}O and O{sub 2} level in the vacuum vessel are reduced significantly. The characteristics of the deposited thin films were analyzed by variable angle spectroscopic ellipsometry, XPS, and AES. {approx}1.78 x 10{sup 16} cm{sup -2} s{sup -1} of carbon flux on the wall is estimated by using cavity technique.

  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. Boron nitride converted carbon fiber

    Energy Technology Data Exchange (ETDEWEB)

    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.

  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. Coadsorption of lanthanum with boron and gadolinium with boron on Mo(1 1 0)

    Science.gov (United States)

    Magkoev, Tamerlan T.; Vladimirov, Georgij G.; Rump, Gennadij A.

    2008-05-01

    Submonolayer to multilayer coadsorption of lanthanum (La) with boron (B) and gadolinium (Gd) with boron on the surface of Mo(1 1 0) has been studied by means of Auger electron spectroscopy (AES), electron energy loss spectroscopy (EELS) and work function ( ϕ) measurements. The equilibrium state of double adsorbate systems achieved either by adsorption of rare-earth metal (REM) on boron precovered Mo(1 1 0) surface held at room temperature or after moderate annealing of the system with opposite order of adsorption (B on REM films) is the layer which is the inhomogeneous mixture of boron and REM atoms with preferential concentration of boron in the surface area of the mixed film. The work function of such films even at REM to boron concentration ratio much higher than 1/6 are very close to the values of corresponding bulk LaB 6 and GdB 6, favoring assumption of surface rearrangement as the dominant reason of high electron emission efficiency of hexaborides. Almost total similarity of the results for La-B and Gd-B systems can be viewed as the consequence of weak participation of Gd f-electrons in determining the thermionic properties of corresponding double layers.

  18. First boronization in KSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Hong, S.H., E-mail: sukhhong@nfri.re.kr [National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon 305-333 (Korea, Republic of); Center for Edge Plasma Science (cEps), Hanyang University, Seoul 133-791 (Korea, Republic of); Lee, K.S.; Kim, K.M.; Kim, H.T.; Kim, G.P. [National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon 305-333 (Korea, Republic of); Sun, J.H.; Woo, H.J. [Department of Electrical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Center for Edge Plasma Science (cEps), Hanyang University, Seoul 133-791 (Korea, Republic of); Park, J.M.; Kim, W.C.; Kim, H.K.; Park, K.R.; Yang, H.L.; Na, H.K. [National Fusion Research Institute, 113 Gwahangno, Yusung-Gu, Daejeon 305-333 (Korea, Republic of); Chung, K.S. [Department of Electrical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Center for Edge Plasma Science (cEps), Hanyang University, Seoul 133-791 (Korea, Republic of)

    2010-11-15

    First boronization in KSTAR is reported. KSTAR boronization system is based on a carborane (C{sub 2}B{sub 10}H{sub 12}) injection system. The design, construction, and test of the system are accomplished and it is tested by using a small vacuum vessel before it is mounted to a KSTAR port. After the boronization in KSTAR, impurity levels are significantly reduced by factor of 3 (oxygen) and by 10 (carbon). Characteristics of a-C/B:H thin films deposited by carborane vapor are investigated. Re-condensation of carborane vapor during the test phase has been reported.

  19. Boron in sillimanite.

    Science.gov (United States)

    Grew, E S; Hinthorne, J R

    1983-08-01

    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. PMID:17830955

  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. 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...

  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. 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.

  4. Boron chemistry in relation to its variations in eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; Singbal, S.Y.S.

    in the offshore waters. Percent addition and removal of boron computEd. by taking into consideration the world average B/Cl of 0.232 indicated an addition up to 16% and removal up to 11.65% resulting in a net addition of boron to the coastal waters. At few...

  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. 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.

  7. Quantification of corrosion resistance of a new-class of criticality control materials: thermal-spray coatings of high-boron iron-based amorphous metals - Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J C; Choi, J S; Shaw, C K; Rebak, R; Day, S D; Lian, T; Hailey, P; Payer, J H; Branagan, D J; Aprigliano, L F

    2007-03-28

    An iron-based amorphous metal, Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4} (SAM2X5), with very good corrosion resistance was developed. This material was produced as a melt-spun ribbon, as well as gas atomized powder and a thermal-spray coating. Chromium (Cr), molybdenum (Mo) and tungsten (W) provided corrosion resistance, and boron (B) enabled glass formation. The high boron content of this particular amorphous metal made it an effective neutron absorber, and suitable for criticality control applications. Earlier studies have shown that ingots and melt-spun ribbons of these materials have good passive film stability in these environments. Thermal spray coatings of these materials have now been produced, and have undergone a variety of corrosion testing, including both atmospheric and long-term immersion testing. The modes and rates of corrosion have been determined in the various environments, and are reported here.

  8. 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.

  9. 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.

  10. Colorimetric determination of Boron-10 in macromolecular delivery agents

    International Nuclear Information System (INIS)

    A polyglycerol with dendritic structure (PGLD) was synthesized by the ring opening polymerization of deprotonated glycidol using a polyglycerol as core functionality in a step-growth process denominated divergent synthesis. After PGLD reaction with 10B-enriched boric acid there was a marked increase in the bulk viscosity of the PGLD dendrimer evidencing the polyester formation. Gel permeation chromatography (GPC) analysis was used to characterize the molecular weight and the polydispersivity of the synthesized PGLD dendrimer. A dendritic polyglycerol structure with Mn value of 16.7 kDa and a narrow polydispersivity (Mw/Mn = 1.05) was obtained in this work. 1H-NMR and 13C-NMR measurements were employed to assess the degree of branching (DB) in PGLD. The DB of 0.85 indicates the tendency of a dentritic structure for the PGLD synthesized in this work. The boron-10 concentration was dependent of the PGLD generation. A selective reagent, curcumine, was studied for spectrophotometric determination of boron in polyglycerol dendrimers. Boron reacts with curcumine to form a complex, which has a maximum absorption peak at 552 nm. Under the optimal conditions, Beer's law was obeyed over the range 0∼20 μg of boron in 25 mL of solution. The biological assays indicate the PGLD-B with boron-10 concentration of 25 mg10B/gPGLD as the most promising macromolecule enriched with boron-10 for the BNCT therapy. (author)

  11. An overview of male reproductive studies of boron with an emphasis on studies of highly exposed Chinese workers

    DEFF Research Database (Denmark)

    Scialli, Anthony R; Bonde, Jens Peter; Brüske-Hohlfeld, Irene;

    2010-01-01

    Boron treatment of rats, mice, and dogs has been associated with testicular toxicity, characterized by inhibited spermiation at lower dose levels and a reduction in epididymal sperm count at higher dose levels. The no-adverse-effect level for reproductive effects in male rats is 17.5mg B/kg bw...... working in boron (B) mining or processing in Liaoning province in northeast China has been published in several Chinese and a few English language papers. This study included individual assessment of boron exposure, interview data on reproductive experience and semen analysis. Employed men living...... in the same community and in a remote community were used as controls. Boron workers (n=75) had a mean daily boron intake of 31.3mg B/day, and a subset of 16 of these men, employed at a plant where there was heavy boron contamination of the water supply, had an estimated mean daily boron intake of 125 mg B...

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

    OpenAIRE

    Chaoyu He; Zhong, J. X.

    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...

  13. 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.

  14. Boron-lined proportional counters with improved neutron sensitivity

    CERN Document Server

    Dighe, P M; Prasad, K R; Kataria, S K; Athavale, S N; Pappachan, A L; Grover, A K

    2003-01-01

    Boron-lined proportional counters with higher neutron sensitivity have been developed by introducing baffle structures within the sensitive volume. the results are compared to devices developed with multiple cathode assemblies in a single enclosure. in either case, the increase in the boron-coated surface area results in higher neutron sensitivity. one of these counters has 51 annular baffles coated with natural boron with 10 mm hole for the anode wire to pass through. filled with p-10 gas at 20 cm hg, it has an overall diameter of 30 and 300 mm length. multiple dip coating method was employed for better uniformity in boron thickness. the neutron sensitivity of this counter is 1.6 cps/nv, which is 2.5 times that of a counter with standard electrode geometry. another counter was developed with three cathode assemblies (30 mm IDx300 mm) coated with 92% sup 1 sup 0 B while the third has seven assemblies coated with natural boron (16 mm IDx750 mm length). the neutron sensitivity is 10 and 5.5 cps/nv, respectively...

  15. 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.

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

    Science.gov (United States)

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

    2006-03-01

    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 transmission electron microscopy, photon correlation spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, vibrational spectroscopy, gel electrophoresis and chemical assays and reveal profound changes in surface chemistry and structural characteristics. In vitro thermal neutron irradiation of B16 melanoma cells incubated with sub-100 nm nanoparticles (381.5 microg/g (10)B) induces complete cell death. The nanoparticles alone induce no toxicity.

  17. Dietary boron, brain function, and cognitive performance.

    OpenAIRE

    Penland, J G

    1994-01-01

    Although the trace element boron has yet to be recognized as an essential nutrient for humans, recent data from animal and human studies suggest that boron may be important for mineral metabolism and membrane function. To investigate further the functional role of boron, brain electrophysiology and cognitive performance were assessed in response to dietary manipulation of boron (approximately 0.25 versus approximately 3.25 mg boron/2000 kcal/day) in three studies with healthy older men and wo...

  18. Tumor cell killing effect of boronated dipeptide. Boromethylglycylphenylalanine on boron neutron capture therapy for malignant brain tumors

    Energy Technology Data Exchange (ETDEWEB)

    Takagaki, Masao; Ono, Koji; Masunaga, Shinichiro; Kinashi, Yuko; Kobayashi, Toru [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst.; Oda, Yoshifumi; Kikuchi, Haruhiko; Spielvogel, B.F.

    1994-03-01

    The killing effect of Boron Neutron Capture Therapy; BNCT, is dependant on the boron concentration ratio of tumor to normal brain (T/N ratio), and also that of tumor to blood (T/B ratio). The clinical boron carrier of boro-captate (BSH) showed the large T/N ratio of ca. 8, however the T/B ratio was around 1, which indicated nonselective accumulation into tumor. Indeed high boron concentration of blood restrict the neutron irradiation dose in order to circumvent the normal endothelial damage, especially in the case of deeply seated tumor. Phenylalanine analogue of para borono-phenylalanine (BPA) is an effective boron carrier on BNCT for malignant melanoma. For the BNCT on brain tumors, however, BPA concentration in normal brain was reported to be intolerably high. In order to improve the T/N ratio of BPA in brain, therefore, a dipeptide of boromethylglycylphenylalanine (BMGP) was synthesized deriving from trimethylglycine conjugated with BPA. It is expected to be selectively accumulated into tumor with little uptake into normal brain. Because a dipeptide might not pass through the normal blood brain barrier (BBB). Its killing effect on cultured glioma cell, T98G, and its distribution in rat brain bearing 9L glioma have been investigated in this paper. The BNCT effect of BMGP on cultured cells was nearly triple in comparison with DL-BPA. The neutron dose yielding 1% survival ratio were 7x10{sup 12}nvt for BMGP and 2x10{sup 13}nvt for BPA respectively on BNCT after boron loading for 16 hrs in the same B-10 concentration of 20ppm. Quantitative study of boron concentration via the {alpha}-auto radiography and the prompt gamma ray assay on 9L brain tumor rats revealed that T/N ratio and T/B ratio are 12.0 and 3.0 respectively. Those values are excellent for BNCT use. (author).

  19. 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.

  20. 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. PMID:26877036

  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. 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.

  3. Boron toxicity in Lemna gibba

    OpenAIRE

    Mayra Sánchez Villavicencio; Carlos Álvarez Silva; Guadalupe Miranda Arce

    2007-01-01

    Total soluble phenols and total chlorophylls content, changes of biomass and concentration factor in Lemna gibba exposed to different concentrations of boron were measured. Day six soluble phenols showed significant differences in treatment with 10 mg/L of boron. At day ten, chlorophylls content in treatment 2 mg/L concentration increased respect to other experimental groups and control group, there were no significant differences. Biomass of Lemna gibba decreased significant in treatments wi...

  4. Room-Temperature Near-Infrared Electroluminescence from Boron-Diffused Silicon Pn-Junction Diodes

    OpenAIRE

    Li, Si; Gao, Yuhan; Fan, Ruixin; Li, Dongsheng; Yang, Deren

    2015-01-01

    Silicon pn-junction diodes with different doping concentrations were prepared by boron diffusion into Czochralski n-type silicon substrate. Their room-temperature near-infrared electroluminescence (EL) was measured. In the EL spectra of the heavily boron doped diode, a luminescence peak at ~1.6 μm (0.78 eV) was observed besides the band-to-band line (~1.1 eV) under the condition of high current injection, while in that of the lightly boron doped diode only the band-to-band line was observed. ...

  5. Room-temperature near-infrared electroluminescence from boron-diffused silicon pn junction diodes

    OpenAIRE

    Si eLi; Yuhan eGao; Ruixin eFan; Dongsheng eLi; Deren eYang

    2015-01-01

    Silicon pn junction diodes with different doping concentrations were prepared by boron diffusion into Czochralski (CZ) n-type silicon substrate. Their room-temperature near-infrared electroluminescence (EL) was measured. In the EL spectra of the heavily boron doped diode, a luminescence peak at ~1.6 m (0.78 eV ) was observed besides the band-to-band line (~1.1eV) under the condition of high current injection, while in that of the lightly boron doped diode only the band-to-band line was obser...

  6. Boron Fullerenes: A First-Principles Study

    Directory of Open Access Journals (Sweden)

    Gonzalez Szwacki Nevill

    2007-01-01

    Full Text Available AbstractA family of unusually stable boron cages was identified and examined using first-principles local-density functional method. The structure of the fullerenes is similar to that of the B12icosahedron and consists of six crossing double-rings. The energetically most stable fullerene is made up of 180 boron atoms. A connection between the fullerene family and its precursors, boron sheets, is made. We show that the most stable boron sheets are not necessarily precursors of very stable boron cages. Our finding is a step forward in the understanding of the structure of the recently produced boron nanotubes.

  7. Colorimetric determination of Boron-10 in macromolecular delivery agents

    Energy Technology Data Exchange (ETDEWEB)

    Camillo, Maria A.P.; Moura, Eduardo [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Centro de Biologia Molecular]. E-mail: mcamillo@ipen.br; Queiroz, Alvaro A.A.A.de [Universidade Federal de Itajuba, MG (Brazil). Inst. de Ciencias Exatas. Dept. de Fisica e Quimica]. E-mail: alencar@unifei.edu.br

    2005-07-01

    A polyglycerol with dendritic structure (PGLD) was synthesized by the ring opening polymerization of deprotonated glycidol using a polyglycerol as core functionality in a step-growth process denominated divergent synthesis. After PGLD reaction with {sup 10}B-enriched boric acid there was a marked increase in the bulk viscosity of the PGLD dendrimer evidencing the polyester formation. Gel permeation chromatography (GPC) analysis was used to characterize the molecular weight and the polydispersivity of the synthesized PGLD dendrimer. A dendritic polyglycerol structure with M{sub n} value of 16.7 kDa and a narrow polydispersivity (M{sub w}/M{sub n} = 1.05) was obtained in this work. {sup 1}H-NMR and {sup 13}C-NMR measurements were employed to assess the degree of branching (DB) in PGLD. The DB of 0.85 indicates the tendency of a dentritic structure for the PGLD synthesized in this work. The boron-10 concentration was dependent of the PGLD generation. A selective reagent, curcumine, was studied for spectrophotometric determination of boron in polyglycerol dendrimers. Boron reacts with curcumine to form a complex, which has a maximum absorption peak at 552 nm. Under the optimal conditions, Beer's law was obeyed over the range 0{approx}20 {mu}g of boron in 25 mL of solution. The biological assays indicate the PGLD-B with boron-10 concentration of 25 mg{sup 10}B/gPGLD as the most promising macromolecule enriched with boron-10 for the BNCT therapy. (author)

  8. Adsorption of boron from boron-containing wastewaters by ion exchange in a continuous reactor

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-01-31

    In this study, boron removal from boron-containing wastewaters prepared synthetically was investigated. The experiments in which Amberlite IRA 743, boron specific resin was used were carried out in a column reactor. The bed volume of resin, boron concentration, flow rate and temperature were selected as experimental parameters. The experimental results showed that percent of boron removal increased with increasing amount of resin and with decreasing boron concentration in the solution. Boron removal decreased with increasing of flow rate and the effect of temperature on the percent of total boron removal increased the boron removal rate. As a result, it was seen that about 99% of boron in the wastewater could be removed at optimum conditions.

  9. The boron trifluoride nitromethane adduct

    Science.gov (United States)

    Ownby, P. Darrell

    2004-02-01

    The separation of the boron isotopes using boron trifluoride·organic-donor, Lewis acid·base adducts is an essential first step in preparing 10B enriched and depleted crystalline solids so vital to nuclear studies and reactor applications such as enriched MgB 2, boron carbide, ZrB 2, HfB 2, aluminum boron alloys, and depleted silicon circuits for radiation hardening and neutron diffraction crystal structure studies. The appearance of this new adduct with such superior properties demands attention in the continuing search for more effective and efficient means of separation. An evaluation of the boron trifluoride nitromethane adduct, its thermodynamic and physical properties related to large-scale isotopic separation is presented. Its remarkably high separation factor was confirmed to be higher than the expected theoretical value. However, the reportedly high acid/donor ratio was proven to be an order of magnitude lower. On-going research is determining the crystal structure of deuterated and 11B enriched 11BF 3·CD 3NO 2 by X-ray and neutron diffraction.

  10. 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.

  11. 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...

  12. 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.

  13. Mechanical properties of boron coatings

    International Nuclear Information System (INIS)

    Internal stress of coatings will cause reliability problems, such as adhesion failure and peeling. We measured the internal stress in boron coatings, which was prepared by the ion plating method, with an apparatus based on the optically levered laser technique. The boron coatings exhibited large compressive stress in the range from -0.5 GPa to -2.6 GPa. It was found that these compressive stresses were decreasing functions of the deposition rate and were increasing functions of the ion bombardment energy. ((orig.))

  14. Analytical boron diffusivity model in silicon for thermal diffusion from boron silicate glass film

    Science.gov (United States)

    Kurachi, Ikuo; Yoshioka, Kentaro

    2015-09-01

    An analytical boron diffusivity model in silicon for thermal diffusion from a boron silicate glass (BSG) film has been proposed in terms of enhanced diffusion due to boron-silicon interstitial pair formation. The silicon interstitial generation is considered to be a result of the silicon kick-out mechanism by the diffused boron at the surface. The additional silicon interstitial generation in the bulk silicon is considered to be the dissociation of the diffused pairs. The former one causes the surface boron concentration dependent diffusion. The latter one causes the local boron concentration dependent diffusion. The calculated boron profiles based on the diffusivity model are confirmed to agree with the actual diffusion profiles measured by secondary ion mass spectroscopy (SIMS) for a wide range of the BSG boron concentration. This analytical diffusivity model is a helpful tool for p+ boron diffusion process optimization of n-type solar cell manufacturing.

  15. Analysis of boronized wall in LHD

    International Nuclear Information System (INIS)

    Boronization has been carried out in some experimental fusion devices as one of wall conditioning Methods. The well-known merits of the boronization are as follows: 1) coated-boron on the first wall has strong gettering function for oxygen impurities and oxygen has been kept into boron films as a boron-oxide and 2) boron film covers first wall with apparently low Z materials facing the plasma. However, an operation scenario of boronization for next generation devices such as ITER is not optimized. In this paper, we discuss an optimized method of coated film uniformity in a wide area and a lifetime of boron film as an oxygen getter using experimental data in the large helical device (LHD). In LHD, boronization by glow discharges has been carried out a few times during each experimental campaign. Helium-diborane mixtured gas is used and plasma facing components (PFM) are stainless steel (SS) for the first wall and carbon for the divertor plates kept in the room temperature. Material probes made of SS316 and Si were installed in the vacuum vessel and exposed during the experimental campaign. Depth profiles of their impurities were analyzed using the X-ray Photoelectron Spectroscopy (XPS) and the Auger electron spectroscopy (AES). Two types of gettering process by boron film have been investigated. One is the process during boronization and the other is that after boronization. Concerning a lifetime of boron film, the distribution of oxygen near the top surface region (0 to 20 nm) indicates a process of oxygen gettering, it shows a contribution after boronization. In this paper, these kinds of process using material probes are shown. (authors)

  16. Boron Poisoning of Plutonium Solutions

    International Nuclear Information System (INIS)

    The results of a theoretical investigation into the possible relaxation of criticality concentration limits in wet chemical reprocessing plants, due to the introduction of boron poisoning, are reported. The following systems were considered: 1. 1 in. stainless steel tubes filled with boron carbide at various pitches in homogeneous mixtures of 239Pu (NO3)4, 5H2O and water. 2. 1 in. and 2 in borosilicate glass Raschig rings in homogeneous mixtures of 239Pu (NO3)4, 5H2O and water. 3. The concentration of natural boron required for k∞ = 1 in homogeneous mixtures of 239Pu-B-H2O. The method of calculation was Monte Carlo using the GEM code with Nuclear Data File cross-sections. The Raschig rings used are those commercially available. The core model consisted of a cubic arrangement of unit cubes of solution within each of which a Raschig ring was centrally placed. The arrangement was such that the rings were regularly stacked with axes parallel, but the side of the unit cube was fixed to preserve the random packing density. Comparison is made with other reported results on boron poisoning. (author)

  17. Boron isotopes in geothermal systems

    International Nuclear Information System (INIS)

    Boron is a highly mobile element and during water-rock reactions, boron is leached out of rocks with no apparent fractionation. In geothermal systems where the water recharging the systems are meteoric in origin, the B isotope ratio of the geothermal fluid reflects the B isotope ratio of the rocks. Seawater has a distinctive B isotope ratio and where seawater recharges the geothermal system, the B isotope ratio of the geothermal system reflects the mixing of rock derived B and seawater derived B. Any deviations of the actual B isotope ratio of a mixture reflects subtle differences in the water-rock ratios in the cold downwelling limb of the hydrothermal system. This paper will present data from a variety of different geothermal systems, including New Zealand; Iceland; Yellowston, USA; Ibusuki, Japan to show the range in B isotope ratios in active geothermal systems. Some of these systems show well defined mixing trends between seawater and the host rocks, whilst others show the boron isotope ratios of the host rock only. In geothermal systems containing high amounts of CO2 boron isotope ratios from a volatile B source can also be inferred. (auth)

  18. Suitability of boron carriers for BNCT: Accumulation of boron in malignant and normal liver cells after treatment with BPA, BSH and BA

    Energy Technology Data Exchange (ETDEWEB)

    Chou, F.I. [Nuclear Science and Technology Development Center, National Tsing Hua University, Taiwan (China)], E-mail: fichou@mx.nthu.edu.tw; Chung, H.P.; Liu, H.M. [Nuclear Science and Technology Development Center, National Tsing Hua University, Taiwan (China); Chi, C.W. [Department of Medical Research and Education, Taipei Veterans General Hospital, Taiwan (China); Institute of Pharmacology, School of Medicine, National Yang-Ming University, Taiwan (China); Lui, W.Y. [Department of Surgery, Taipei Veterans General Hospital, Taiwan (China); Department of Surgery, School of Medicine, National Yang-Ming University, Taiwan (China)

    2009-07-15

    Hepatocellular carcinoma remains widely prevalent in tropical Africa and south-east Asia. At present, there are no effective treatments for hepatoma and its prognosis is extremely poor unless the tumor was diagnosed in an early stage and resected before metastasis. Therefore, boron neutron capture therapy (BNCT) may provide an alternative therapy for treatment of hepatocellular carcinoma. In this study, the intracellular concentrations of L-boronophenylalanine (BPA), sodium borocaptate (BSH) and boric acid (BA) were examined in human hepatoma HepG2 and liver Clone 9 cell cultures. With the use of 25 {mu}g B/mL media of BPA, BSH and BA, the intracellular uptake of boron in HepG2 and Clone 9 cells was compared. The suitability of BPA, BSH and BA were further evaluated on the basis of organ-specific boron distribution in normal rat tissues. BPA, BSH and BA were administered via intraperitoneal injection into rats with corresponding boron concentrations of 7, 25, and 25 mg/kg body weight, respectively. The accumulation rates of BPA, BSH and BA in HepG2 cells were higher than that of Clone 9 cells. Boron concentration in BPA, BSH and BA treated HepG2 cells were 1.8, 1.5, and 1.6-fold of Clone 9 cells at 4 h, respectively. In both HepG2 and Clone 9 cells, although the concentration of boron in BPA-treated cells exceeded that in BA-treated ones, however, cells treated with BPA had similar surviving fraction as those treated with BA after neutron irradiation. The accumulation ratios of boron in liver, pancreas and kidney to boron in blood were 0.83, 4.16 and 2.47, respectively, in BPA treated rats, and 0.75, 0.35 and 2.89, respectively, in BSH treated rats at 3 h after treatment. However, boron does not appear to accumulate specifically in soft tissues in BA treated rats. For in situ BNCT of hepatoma, normal organs with high boron concentration and adjacent to liver may be damaged in neutron irradiation. BPA showed high retention in pancreas and may not be a good drug for

  19. Evaluation of unnatural cyclic amino acids as boron delivery agents for treatment of melanomas and gliomas

    International Nuclear Information System (INIS)

    Unnatural cyclic amino acids (UNAAs) are a new class of boron delivery agents that are in a pre-clinical stage of evaluation. In the present study, the biodistribution of racemic forms of the cis- and trans-isomers of the boronated UNAA 1-amino-3-boronocyclopentanecarboxylic acid (ABCPC) and 1-amino-3-boronocycloheptanecarboxylic acid (ABCHC) were evaluted in B16 melanoma bearing mice and this was compared to L-p-boronophenylalanine (BPA). Boron concentrations were determined by inductively coupled plasma-optical emission spectroscopy (ICP-OES) at 2.5 h following intraperitoneal (i.p.) injection of the test agents at a concentration equivalent to 24 mg/B/kg. While all compounds attained comparable tumor boron concentrations, the tumor/blood (T/Bl) boron concentration ratios were far superior for both cis-ABCPC and cis-ABCHC compared to BPA (T/Bl=16.4, and 15.1 vs. 5.4). Secondary ion mass spectrometry (SIMS) imaging revealed that the cis-ABCPC delivered boron to the nuclei, as well as the cytoplasm of B16 cells. Next, a biodistribution study of cis-ABCPC and BPA was carried out in F98 glioma bearing rats following i.p. administration. Both compounds attained comparable tumor boron concentrations but the tumor/brain (T/Br) boron ratio was superior for cis-ABCPC compared to BPA (6 vs. 3.3). Since UNAAs are water soluble and cannot be metabolized by tumor cells, they could be potentially more effective boron delivery agents than BPA. Our data suggest that further studies are warranted to evaluate these compounds prior to the initiation of clinical studies. - Highlights: • Unnatural cyclic amino acids (UNAAs) are a new class of boron delivery agents for neutron capture therapy. • ABCPC and ABCHC attained higher tumor/blood ratios vs. BPA in B16 melanoma bearing mice. • The tumor/brain ratio of cis-ABCPC was superior to BPA (6 vs. 3.3) suggesting that further studies are warranted

  20. Raman spectroscopy of boron carbides and related boron-containing materials

    International Nuclear Information System (INIS)

    Raman spectra of crystalline boron, boron carbide, boron arsenide (B12As2), and boron phosphide (B12P2) are reported. The spectra are compared with other boron-containing materials containing the boron icosahedron as a structural unit. The spectra exhibit similar features some of which correlate with the structure of the icosahedral units of the crystals. The highest Raman lines appear to be especially sensitive to the B-B distance in the polar triangle of the icosahedron. Such Raman structural markers are potentially useful in efforts to tailor electronic properties of these high temperature semiconductors and thermoelectrics

  1. 16 CFR 16.16 - Compensation.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Compensation. 16.16 Section 16.16 Commercial... MANAGEMENT § 16.16 Compensation. (a) Committee members. Unless otherwise provided by law, the Commission... cost to the Commission. The compensation to be paid to such consultant may not exceed the maximum...

  2. 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.

  3. Friction anisotropy in boronated graphite

    International Nuclear Information System (INIS)

    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

  4. 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.

  5. 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.

  6. 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.

  7. Boron clusters in luminescent materials.

    Science.gov (United States)

    Mukherjee, Sanjoy; Thilagar, Pakkirisamy

    2016-01-21

    In recent times, luminescent materials with tunable emission properties have found applications in almost all aspects of modern material sciences. Any discussion on the recent developments in luminescent materials would be incomplete if one does not account for the versatile photophysical features of boron containing compounds. Apart from triarylboranes and tetra-coordinate borate dyes, luminescent materials consisting of boron clusters have also found immense interest in recent times. Recent studies have unveiled the opportunities hidden within boranes, carboranes and metalloboranes, etc. as active constituents of luminescent materials. From simple illustrations of luminescence, to advanced applications in LASERs, OLEDs and bioimaging, etc., the unique features of such compounds and their promising versatility have already been established. In this review, recent revelations about the excellent photophysical properties of such materials are discussed. PMID:26574714

  8. CVD-produced boron filaments

    Science.gov (United States)

    Wawner, F. E.; Debolt, H. E.; Suplinskas, R. D.

    1980-01-01

    A technique for producing boron filaments with an average tensile strength of 6.89 GPa has been developed which involves longitudinal splitting of the filament and core (substrate) removal by etching. Splitting is accomplished by a pinch wheel device which continuously splits filaments in lengths of 3.0 m by applying a force to the side of the filament to create a crack which is then propagated along the axis by a gentle sliding action. To facilitate the splitting, a single 10 mil tungsten substrate is used instead of the usual 0.5 mil substrate. A solution of hot 30% hydrogen peroxide is used to remove the core without attacking the boron. An alternative technique is to alter the residual stress by heavily etching the filament. Average strengths in the 4.83-5.52 GPa range have been obtained by etching an 8 mil filament to 4 mil.

  9. Boron Enrichment in Martian Clay

    OpenAIRE

    James D Stephenson; Lydia J Hallis; Kazuhide Nagashima; Freeland, Stephen J.

    2013-01-01

    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 minera...

  10. 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.

  11. 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

    boron in geological materials, Anal. Chim.Acta, 1988, 211: 243-256.[13]Xiao, Y. K., Beary, E. S., Fassett, J. D., An improved method for the high-precision isotopic measurement of boron by thermal ionization mass spectrometry, Int. J. Mass Spectrom. Ion Proc., 1988, 85: 203-213.[14]Xiao, Y. K., Zhang, C. G., High precision isotopic measurement of chlorine by thermal ionisation mass spectrometry of the Cs2Cl+ ion, Int. J. Mass Spectrom. Ion Proc., 1992, 116: 183-192.[15]Bruyevich, S. V., Korzh, V. D., Boron exchange between the sea and the atmosphere, Oceanology, 1971, 11: 345-351.[16]Martens, C., Harriss, R., Boron in coastal North Florida rainfall, J. Geoph. Res., 1976, 81: 6371-6375.[17]Byrne, R. H., Kester, D. R., Inorganic speciation of boron in seawater, J. Mar. Res., 1974, 32: 119-127.[18]Kakihana, H., Kotaka, M., Satoh, S. et al., Fundamental studies on the ion-exchange separation of boron isotopes, Bull.Chem. Soc. Japan, 1977, 50: 158-163.

  12. 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%.

  13. 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.

  14. Method for determination of boron carbide in wurtzite-like boron nitride

    International Nuclear Information System (INIS)

    A technique for increase of sensitivity and analysis accuracy while boron carbide determination in wurtzite-like boron nitride is proposed. Boron nitride with an addition of boron carbide is bjected to treatment by the mixture of concentrated sulphuric acid and 0.1-0.5 N of porassium bichromate solution at ratio of (2-1):1 at the temperature of mixture boiling. Boron carboide content is calculated according to the quantity of restored Cr(3+), which is determined by titration of Cr(6+) excess with the Mohr's salt solution

  15. Boron water quality for the Plynlimon catchments

    Directory of Open Access Journals (Sweden)

    C. Neal

    1997-01-01

    Full Text Available Boron concentrations in rainfall, throughfall and stemflow for Spruce stands, mist, streamwater and groundwater are compared with chloride to assess atmospheric sources and catchment input-output balances for the Plynlimon catchments. In rainfall, boron concentration averages about 4.5 μg-B l-1 and approximately two thirds of this comes from anthropogenic sources. In through-fall and stemflow, boron concentrations are approximately a factor of ten times higher than in rainfall. This increase is associated with enhanced scavenging of mist and dry deposition by the trees. As the sampling sites were close to a forest edge, this degree of scavenging is probably far higher than in the centre of the forest. The throughfall and stemflow concentrations of boron show some evidence of periodic variations with time with peak concentrations occurring during the summer months indicating some vegetational cycling. In mist, boron concentrations are almost twenty times higher than in rainfall and anthropogenic sources account for about 86% of this. Within the Plynlimon streams, boron concentrations are about 1.4 to 1.7 times higher than in rainfall. However, after allowance for mist and dry deposition contributions to atmospheric deposition, it seems that, on average, about 30% of the boron input is retained within the catchment. For the forested catchments, felling results in a disruption of the biological cycle and a small increase in boron leaching from the catchment results in the net retention by the catchment being slightly reduced. Despite the net uptake by the catchment, there is clear evidence of a boron component of weathering from the bedrock. This is shown by an increased boron concentration in a stream influenced by a nearby borehole which increased groundwater inputs. The weathering component for boron is also observed in Plynlimon groundwaters as boron concentrations and boron to chloride ratios are higher than for the streams. For these

  16. 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

  17. 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.

  18. Some physical properties of compacted specimens of highly dispersed boron carbide and boron suboxide

    International Nuclear Information System (INIS)

    Structure, shear modulus and internal friction (IF) of compacted specimens of boron carbide and boron suboxide have been investigated. Microtwins and stacking faults were observed along the {100} plane systems of polycrystalline specimens of boron carbide. Electrical conductivity of the specimens was that of p-type. Concentration of holes varied from 1017 to 1019 cm-3. The IF was measured in the temperature range 80-300 K. It was shown that the IF of boron carbide and that of boron suboxide were characterized with a set of similar relaxation processes. Mechanisms of the relaxation processes in boron carbide and boron suboxide are discussed in terms of the Hasiguti model of interaction between dislocations and point defects

  19. New techniques for producing thin boron films

    International Nuclear Information System (INIS)

    A review will be presented of methods for producing thin boron films using an electron gun. Previous papers have had the problem of spattering of the boron source during the evaporation. Methods for reducing this problem will also be presented. 12 refs., 4 figs

  20. 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.

  1. Fabrication of boron-phosphide neutron detectors

    International Nuclear Information System (INIS)

    Boron phosphide is a potentially viable candidate for high neutron flux neutron detectors. The authors have explored chemical vapor deposition methods to produce such detectors and have not been able to produce good boron phosphide coatings on silicon carbide substrates. However, semi-conducting quality films have been produced. Further testing is required

  2. 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.

  3. Reduction-melting behaviors of boron-bearing iron concentrate/carbon composite pellets with addition of CaO

    Institute of Scientific and Technical Information of China (English)

    Jing-song Wang

    2015-01-01

    Although the total amount of boron resources in China is high, the grades of these resources are low. The authors have already proposed a new comprehensive utilization process of boron-bearing iron concentrate based on the iron nugget process. The present work de-scribes a further optimization of the conditions used in the previous study. The effects of CaO on the reduction–melting behavior and proper-ties of the boron-rich slag are presented. CaO improved the reduction of boron-bearing iron concentrate/carbon composite pellets when its content was less than 1wt%. Melting separation of the composite pellets became difficult with the CaO content increased. The sulfur content of the iron nugget gradually decreased from 0.16wt%to 0.046wt%as the CaO content of the pellets increased from 1wt%to 5wt%. CaO negatively affected the iron yield and boron extraction efficiency of the boron-rich slag. The mineral phase evolution of the boron-rich slag during the reduction–melting separation of the composite pellets with added CaO was also deduced.

  4. 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.

  5. 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.

  6. 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.

  7. Boron enrichment in martian clay.

    Science.gov (United States)

    Stephenson, James D; Hallis, Lydia J; Nagashima, Kazuhide; Freeland, Stephen J

    2013-01-01

    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. PMID:23762242

  8. 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.

  9. Colorimetric Sugar Sensing Using Boronic Acid-Substituted Azobenzenes

    OpenAIRE

    Yuya Egawa; Ryotaro Miki; Toshinobu Seki

    2014-01-01

    In association with increasing diabetes prevalence, it is desirable to develop new glucose sensing systems with low cost, ease of use, high stability and good portability. Boronic acid is one of the potential candidates for a future alternative to enzyme-based glucose sensors. Boronic acid derivatives have been widely used for the sugar recognition motif, because boronic acids bind adjacent diols to form cyclic boronate esters. In order to develop colorimetric sugar sensors, boronic acid-conj...

  10. Synthesis and characterization of ammonium phosphate fertilizers with boron

    OpenAIRE

    ANGELA MAGDA; RODICA PODE; CORNELIA MUNTEAN; MIHAI MEDELEANU; ALEXANDRU POPA

    2010-01-01

    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 ...

  11. Boron-Loaded Silicone Rubber Scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Z.W.; Maya, L.; Brown, G.M.; Sloop, F.V.Jr

    2003-05-12

    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 response were obtained, and although the light output was found to be much poorer than from samples in which boron was dissolved, the higher boron concentrations enabled essentially 100% neutron absorption in only a few millimeters' thickness of rubber.

  12. The determination of boron and carbon in reactor grade boron carbide

    International Nuclear Information System (INIS)

    The sealed tube method of dissolution at high temperature and pressure has been successfully applied in the analysis of reactor grade boron carbide for the determination of boron. A 50 mg sample of boron carbide is completely dissolved by heating with concentrated nitric acid in a sealed tube at 3000C. The boron content of the resultant sample solution is determined by the mannitol potentiometric titration method. The precision of the method for the determination of 2.5 mg of boron using the Harwell automatic potentiometric titrator is 0.2% (coefficient of variation). The carbon content of a boron carbide sample is determined by combustion of the sample at 10500C in a stream of oxygen using vanadium pentoxide to ensure the complete oxidation of the sample. The carbon dioxide produced from the sample is measured manometrically and the precision of the method for the determination of 4 mg of carbon is 0.4% (coefficient of variation). (author)

  13. 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

  14. Synthesis of Boron Nanorods by Smelting Non-Toxic Boron Oxide in Liquid Lithium

    OpenAIRE

    Amartya Chakrabarti; Tao Xu; Laura K. Paulson; Krise, Kate J.; Maguire, John A; Hosmane, Narayan S.

    2010-01-01

    In contrast to the conventional bottom-up syntheses of boron nanostructures, a unique top-down and greener synthetic strategy is presented for boron nanorods involving nontoxic boron oxide powders ultrasonically smelted in liquid lithium under milder conditions. The product was thoroughly characterized by energy dispersive X-ray analysis, atomic emission spectroscopy, thermogravimetric analysis and, UV-Vis spectroscopy, including structural characterization by transmission electron microscop...

  15. 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.

  16. 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...

  17. Investigation of boron extraction process with aid magnesium hydroxide from mother liquor of boron production

    International Nuclear Information System (INIS)

    Conditions of boron - magnesium concentrate preparation from mother liquor by coprecipitation of borate - ions by magnesium hydroxide are investigated. It is shown that boron - magnesium concentrate and products of its heat treatment at 100 - 500 deg C in water are dissolved partially, and in ammonium citrate - practically completely. Suppositions are made on the composition of the product prepared, on the the structure of its crystal lattice and the processes taking place in it during heat treatment. The conclusion is made on the perspectiveness of processing of mother liquor of boron industry for boron - magnesium concentrate

  18. 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

  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 adsorption on hematite and clinoptilolite

    International Nuclear Information System (INIS)

    This thesis describes experiments performed to determine the suitability of boron as a potential reactive tracer for use in saturated-zone C-well reactive tracer studies for the Yucca Mountain Project (YMP). Experiments were performed to identify the prevalent sorption mechanism of boron and to determine adsorption of boron on hematite and clinoptilolite as a function of pH. These minerals are present in the Yucca Mountain tuff in which the C-well studies will be conducted. Evaluation of this sorption mechanism was done by determining the equilibration time of boron-mineral suspensions, by measuring changes in equilibrium to titrations, and by measuring electrophoretic mobility. Experiments were performed with the minerals suspended in NaCl electrolytes of concentrations ranging from 0.1 N NaCl to 0.001 N NaCl. Experimentalconditions included pH values between 3 and 12 and temperature of about 38 degrees C

  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. High temperature thermoelectric properties of boron carbide

    International Nuclear Information System (INIS)

    Boron carbides are refractory solids with potential for application as very high temperature p-type thermoelectrics in power conversion applications. The thermoelectric properties of boron carbides are unconventional. In particular, the electrical conductivity is consistent with the thermally activated hopping of a high density (∼1021/cm3) of bipolarons; the Seebeck coefficient is anomalously large and increases with increasing temperature; and the thermal conductivity is surprisingly low. In this paper, these unusual properties and their relationship to the unusual structure and bonding present in boron carbides are reviewed. Finally, the potential for utilization of boron carbides at very high temperatures (up to 2200 degrees C) and for preparing n-type materials is discussed

  3. 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

  4. Innovative boron nitride-doped propellants

    OpenAIRE

    Thelma Manning; Richard Field; Kenneth Klingaman; Michael Fair; John Bolognini; Robin Crownover; Carlton P. Adam; Viral Panchal; Eugene Rozumov; Henry Grau; Paul Matter; Michael Beachy; Christopher Holt; Samuel Sopok

    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 ...

  5. Lithium-Beryllium-Boron : Origin and Evolution

    OpenAIRE

    Vangioni-Flam, Elisabeth; Casse, Michel; Audouze, Jean

    1999-01-01

    The origin and evolution of Lithium-Beryllium-Boron is a crossing point between different astrophysical fields : optical and gamma spectroscopy, non thermal nucleosynthesis, Big Bang and stellar nucleosynthesis and finally galactic evolution. We describe the production and the evolution of Lithium-Beryllium-Boron from Big Bang up to now through the interaction of the Standard Galactic Cosmic Rays with the interstellar medium, supernova neutrino spallation and a low energy component related to...

  6. Metallogenic Chronology of Boron Deposits in the Eastern Liaoning Paleoproterozoic Rift Zone

    Institute of Scientific and Technical Information of China (English)

    LU Yuanfa; CHEN Yuchuan; LI Huaqing; XUE Chunji; CHEN Fuwen

    2005-01-01

    Lead isotopic analytic data of 30 ores gathered from the Zhuanmiao boron deposit, Wengquangou boron (iron) deposit and its Dongtaizi Ore Member constitute three isochrons, the corresponding ages of which are 1902±12 Ma,1852±9 Ma and 1917±48 Ma. Lead isotopic analyses of marble from the Xiquegou Member of the Qingchenzi orefield yield a Pb-Pb isochron age of 1844±27 Ma. 40Ar-39Ar quick neutron activation dating of phlogopites and microclines coexisting with ore minerals in the Wengquangou boron (iron) and Zhuanmiao boron deposits shows that: (1) the phlogopite from the Wengquangou has a plateau age of 1923±1.5 Ma and an isochron age of 1924±2.5 Ma; (2) the microcline from the Wengquangou has the plateau age of 1407±5.4 Ma and 220±12 Ma and an isochron age of 1403±19Ma; (3) the phlogopites from the Zhuanmiao yield a plateau age 1918±1.3 Ma and an isochron age of 1918±2.9 Ma; (4) the microclines from the Zhuanmiao yield the plateau age of 1420±16 Ma and 250±8 Ma and an isochron age of 1425±19 Ma and 269±16 Ma. These ages indicate that the eastern Liaoning area happened around 1900 Ma, an important tectonomagmatic event, which is consistent with the worldwide Mid-Proterozoic tectonomagmatic event. During this period, the Proterozoic Liaohe Group was folded and underwent strong normal metamorphism, and the (hydrothermal)sedimentary boron deposits (or source beds) formed earlier were strongly superimposed by mineralization, resulting in enrichment of boron; later regional geological processes made little contribution to the formation of the boron deposits.Lead isotopic components show that the U-Pb and Th-Pb isotopic system reached homogenization in the ores whereas only the U-Pb isotopic system reached homogenization in the marble from the Xiquegou district, which indicates that the boron deposits superimposed in the studied area endured a relatively strong process of hydrothermal migmatization during the end phase of early Proterozoic metamorphism.

  7. 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.

  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. Inheritance of Boron Efficiency in Oilseed Rape

    Institute of Scientific and Technical Information of China (English)

    SHI Lei; WANG Yun-Hua; NIAN Fu-Zhao; LU Jian-Wei; MENG Jin-Ling; XU Fang-Sen

    2009-01-01

    Field experiments were conducted to study the inheritance of boron efficiency in oilseed rape (Brassica napus L.) by evaluating the boron (B) efficiency coefficient (BEC,the ratio of the seed yield at below the critical boron level to that at the boron-sufficient level) with 657 F2:3 fines of a population derived from a cross between a B-efficient cultivar,Qingyou 10,and a B-inefficient cultivar,Bakow.Qingyou i0 had high BEC as well as high seed yield at low available soil B.On the contrary,Bakow produced low seed yield at low B status.Boron deficiency decreased the seed yield of the F2:3 lines to different extents and the distribution of BEC of the population showed a bimodal pattern.When the 657 F2:3 lines were grouped into B-efficient lines and B-inefficient lines according to their BEC,the ratio of B-efficient lines to B-inefficient lines fitted the expected ratio (3:1),indicating that one major gene controlled the B-efficiency trait.127 F2:3 lines selected from the population at random,with distribution of BEC similar to that of the overall population,were used to identify the target region for fine mapping of the boron efficiency gene.

  10. Boronization of Russian tokamaks from carborane precursors

    International Nuclear Information System (INIS)

    A new and cheap boronization technique using the nontoxic and nonexplosive solid substance carborane has been developed and successfully applied to the Russian tokamaks T-11M, T-3M, T-10 and TUMAN-3. The glow discharge in a mixture of He and carborane vapor produced the amorphous B/C coating with the B/C ratio varied from 2.0-3.7. The deposition rate was about 150 nm/h. The primary effect of boronization was a significant reduction of the impurity influx and the plasma impurity contamination, a sharp decrease of the plasma radiated power, and a decrease of the effective charge. Boronization strongly suppressed the impurity influx caused by additional plasma heating. ECR- and ICR-heating as well as ECR current drive were more effective in boronized vessels. Boronization resulted in a significant extension of the Ne- and q-region of stable tokamak operation. The density limit rose strongly. In Ohmic H-mode energy confinement time increased significantly (by a factor of 2) after boronization. It rose linearly with plasma current Ip and was 10 times higher than Neo-Alcator time at maximum current. ((orig.))

  11. Discharge cleaning on TFTR after boronization

    International Nuclear Information System (INIS)

    At the beginning of the 1990 TFTR experimental run, after replacement of POCO-AXF-5Q graphite tiles on the midplane of the bumper limiter by carbon fiber composite (CFC) tiles and prior to any Pulse Discharge Cleaning (PDC), boronization was performed. Boronization is the deposition of a layer of boron and carbon on the vacuum vessel inner surface by a glow discharge in a diborane, methane and helium mixture. The amount of discharge cleaning required after boronization was substantially reduced compared to that which was needed after previous openings when boronization was not done. Previously, after a major shutdown, about 105 low current (∼20 kA) Taylor Discharge Cleaning (TDC) pulses were required before high current (∼400 kA) aggressive Pulse Discharge Cleaning (PDC) pulses could be performed successfully. Aggressive PDC is used to heat the limiters from the vessel bakeout temperature of 150 degrees C to 250 degrees C for a period of several hours. Heating the limiters is important to increase the rate at which water is removed from the carbon limiter tiles. After boronization, the number of required TDC pulses was reduced to <5000. The number of aggressive PDC pulses required was approximately unchanged. 14 refs., 1 tab

  12. Synthesis and properties of low-carbon boron carbides

    International Nuclear Information System (INIS)

    This paper reports on the production of boron carbides of low carbon content (3 and CCl4 at 1273-1673 K in a chemical vapor deposition (CVD) reactor. Transmission electron microscopy (TEM) revealed that phase separation had occurred, and tetragonal boron carbide was formed along with β-boron or α-boron carbide under carbon-depleted gas-phase conditions. At temperatures greater than 1390 degrees C, graphite substrates served as a carbon source, affecting the phases present. A microstructure typical of CVD-produced α-boron carbide was observed. Plan view TEM of tetragonal boron carbide revealed a blocklike structure

  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. 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.)

  16. Some Lewis acid-base adducts involving boron trifluoride as electrolyte additives for lithium ion cells

    Science.gov (United States)

    Nie, Mengyun; Madec, L.; Xia, J.; Hall, D. S.; Dahn, J. R.

    2016-10-01

    Three complexes with boron trifluoride (BF3) as the Lewis acid and different Lewis bases were synthesized and used as electrolyte additives in Li[Ni1/3Mn1/3Co1/3]O2/graphite and Li[Ni0.42Mn0.42Co0.16]O2/graphite pouch cells. Lewis acid-base adducts with a boron-oxygen (Bsbnd O) bond were trimethyl phosphate boron trifluoride (TMP-BF) and triphenyl phosphine oxide boron trifluoride (TPPO-BF). These were compared to pyridine boron trifluoride (PBF) which has a boron-nitrogen (Bsbnd N) bond. The experimental results showed that cells with PBF had the least voltage drop during storage at 4.2 V, 4.4 V and 4.7 V at 40 °C and the best capacity retention during long-term cycling at 55 °C compared to cells with the other additives. Charge-hold-discharge cycling combined with simultaneous electrochemical impedance spectroscopy measurements showed that impedance growth in TMP-BF and TPPO-BF containing cells was faster than cells containing 2%PBF, suggesting that PBF is useful for impedance control at high voltages (>4.4 V). XPS analysis of the SEI films highlighted a specific reactivity of the PBF-derived SEI species that apparently hinders the degradation of both LiPF6 and solvent during formation and charge-hold-discharge cycling. The modified SEI films may explain the improved impedance, the smaller voltage drop during storage and the improved capacity retention during cycling of cells containing the PBF additive.

  17. The energy landscape of fullerene materials: a comparison between boron, boron-nitride and carbon

    CERN Document Server

    De, Sandip; Amsler, Maximilian; Pochet, Pascal; Genovese, Luigi; Goedecker, Stefan

    2010-01-01

    Using the minima hopping global geometry optimization method on the density functional potential energy surface we study medium size and large boron clusters. Even though for isolated medium size clusters the ground state is a cage like structure they are unstable against external perturbations such as contact with other clusters. The energy landscape of larger boron clusters is glass like and has a large number of structures which are lower in energy than the cages. This is in contrast to carbon and boron nitride systems which can be clearly identified as structure seekers in our minima hopping runs. The differences in the potential energy landscape explain why carbon and boron nitride systems are found in nature whereas pure boron fullerenes have not been found.

  18. 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.

  19. 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.

  20. 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. PMID:15574397

  1. Study and optimization of boronization in Alcator C-Mod using the Surface Science Station (S{sup 3})

    Energy Technology Data Exchange (ETDEWEB)

    Ochoukov, Roman, E-mail: ochoukov@psfc.mit.edu [Plasma Science and Fusion Center MIT, NW17, 175 Albany Street, Cambridge, MA 02139 (United States); Whyte, Dennis; Lipschultz, Bruce; LaBombard, Brian [Plasma Science and Fusion Center MIT, NW17, 175 Albany Street, Cambridge, MA 02139 (United States); Gierse, Niels [Institute of Energy and Climate Research - Plasma Physics, Forschungszentrum Juelich GmbH, Association EURATOM-FZJ, Partner in the Trilateral Euregio Cluster, Juelich (Germany); Physikalisches Institut, Universitaet zu Koeln, D-50937 Cologne (Germany); Harrison, Soren [Fusion Research Technologies, 519 Somerville Avenue 243, Somerville, MA 02143 (United States)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Boron deposition profiles measured on Alcator C-Mod during boronization. Black-Right-Pointing-Pointer Boron deposition profile is consistent with ionic deposition. Black-Right-Pointing-Pointer Monte Carlo simulation of boron deposition agrees with experiment assuming warm ({approx}1-10 eV) boron{sup +1} ions. - Abstract: A Surface Science Station (S{sup 3}) on the Alcator C-Mod tokamak is used to study and optimize the location and rate of boron film deposition in situ during electron cyclotron (EC) discharge plasmas using 2.45 GHz radio-frequency (RF) heating and a mixture of helium and diborane (B{sub 2}D{sub 6}) gasses. The radial profile of boron deposition is measured with a pair of quartz microbalances (QMB) on S{sup 3}, the faces of which can be rotated 360 Degree-Sign including orientations parallel and perpendicular to the toroidal magnetic field B{sub T} {approx}0.1 T. The plasma electron density is measured with a Langmuir probe, also on S{sup 3} in the vicinity of the QMBs, and typical values are {approx}1 Multiplication-Sign 10{sup 16} m{sup -3}. A maximum boron deposition rate of 0.82 {mu}g/cm{sup 2}/min is obtained, which corresponds to 3.5 nm/min if the film density is that of solid boron. These deposition rates are sufficient for boron film applications between tokamak discharges. However the deposition does not peak at the EC resonance as previously assumed. Rather, deposition peaks near the upper hybrid (UH) resonance, {approx}5 cm outboard of the EC resonance. This has implications for RF absorption, with the RF waves being no longer damped on the electrons at the EC resonance. The previously inferred radial locations of critical erosion zones in Alcator C-Mod also need to be re-evaluated. The boron deposition profile versus major radius follows the ion flux/density profile, implying that the boron deposition is primarily ionic. The application of a vertical magnetic field (B{sub V} {approx}0.01 T) was

  2. 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.

  3. 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

  4. 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.

  5. Technology of boron-containing polyphosphate fertilizer 'Phosphobor'

    International Nuclear Information System (INIS)

    A technology is developed for producing 'Phosphobor' fertilizer based on the rock phosphate weal (17-18% P2O5) with additions of boron-magnesium compound. Boron is part of polyphosphate fertilizer in the form of polymeric compounds of phosphorus and boron. Phosphorus and boron copolymers -boratophosphates - are easily formed in the process of polyphosphate fertilizers production, since borates undergo a mutual polycondensation reaction with phosphates. 8 refs., 1 fig

  6. 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.

  7. 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.

  8. Proceedings of workshop on 'boron chemistry and boron neutron capture therapy'

    International Nuclear Information System (INIS)

    This volume contains the proceedings of the 4th Workshop on 'the Boron Chemistry and Boron Neutron Capture Therapy' held on February 24 in 1992. First, clinical experiences of BNCT in the Kyoto University Research Reactor in 1992 were briefly reported. Then, the killing effects of boron cluster-containing nucleic acid precursors on tumor cells were shown (Chap. 2). The various trials of the optical resolution of B-p-boronophenylalanine for neutron capture therapy were made (Chap. 3). The borate-dextran gel complexes were investigated by the nuclear magnetic resonance spectroscopy. The stability constants of borate complexes were listed, and are useful in the solution chemistry of boron compounds (Chap. 4). The interactions between boron compounds and biological materials were studied by the paper electrophoresis which had been developed by us (Chap. 5). Molecular design of boron-10 carriers and their organic synthesis were reported (Chap. 6). Carborane-containing aziridine boron carriers which were directed to the DNA alkylation were synthesized and their cancer cell killing efficacies were tested (Chap. 7). The solution chemistry of deuterium oxide which is a good neutron moderator was reported, relating to the BNCT (Chap. 8). (author)

  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. Colorimetric Sugar Sensing Using Boronic Acid-Substituted Azobenzenes

    Directory of Open Access Journals (Sweden)

    Yuya Egawa

    2014-02-01

    Full Text Available In association with increasing diabetes prevalence, it is desirable to develop new glucose sensing systems with low cost, ease of use, high stability and good portability. Boronic acid is one of the potential candidates for a future alternative to enzyme-based glucose sensors. Boronic acid derivatives have been widely used for the sugar recognition motif, because boronic acids bind adjacent diols to form cyclic boronate esters. In order to develop colorimetric sugar sensors, boronic acid-conjugated azobenzenes have been synthesized. There are several types of boronic acid azobenzenes, and their characteristics tend to rely on the substitute position of the boronic acid moiety. For example, o-substitution of boronic acid to the azo group gives the advantage of a significant color change upon sugar addition. Nitrogen-15 Nuclear Magnetic Resonance (NMR studies clearly show a signaling mechanism based on the formation and cleavage of the B–N dative bond between boronic acid and azo moieties in the dye. Some boronic acid-substituted azobenzenes were attached to a polymer or utilized for supramolecular chemistry to produce glucose-selective binding, in which two boronic acid moieties cooperatively bind one glucose molecule. In addition, boronic acid-substituted azobenzenes have been applied not only for glucose monitoring, but also for the sensing of glycated hemoglobin and dopamine.

  11. Room-temperature near-infrared electroluminescence from boron-diffused silicon pn junction diodes

    Science.gov (United States)

    Li, Si; Gao, Yuhan; Fan, Ruixin; Li, Dongsheng; Yang, Deren

    2015-02-01

    Silicon pn junction diodes with different doping concentrations were prepared by boron diffusion into Czochralski (CZ) n-type silicon substrate. Their room-temperature near-infrared electroluminescence (EL) was measured. In the EL spectra of the heavily boron doped diode, a luminescence peak at ~1.6 μm (0.78 eV ) was observed besides the band-to-band line (~1.1eV) under the condition of high current injection, while in that of the lightly boron doped diode only the band-to-band line was observed. The intensity of peak at 0.78 eV increases exponentially with current injection with no observable saturation at room temperature. Furthermore, no dislocations were found in the cross-sectional transmission electron microscopy image, and no dislocation-related luminescence was observed in the low-temperature photoluminescence spectra. We deduce the 0.78 eV emission originates from the irradiative recombination in the strain region of diodes caused by the diffusion of large number of boron atoms into silicon crystal lattice.

  12. Room-temperature near-infrared electroluminescence from boron-diffused silicon pn junction diodes

    Directory of Open Access Journals (Sweden)

    Si eLi

    2015-02-01

    Full Text Available Silicon pn junction diodes with different doping concentrations were prepared by boron diffusion into Czochralski (CZ n-type silicon substrate. Their room-temperature near-infrared electroluminescence (EL was measured. In the EL spectra of the heavily boron doped diode, a luminescence peak at ~1.6 m (0.78 eV was observed besides the band-to-band line (~1.1eV under the condition of high current injection, while in that of the lightly boron doped diode only the band-to-band line was observed. The intensity of peak at 0.78 eV increases exponentially with current injection with no observable saturation at room temperature. Furthermore, no dislocations were found in the cross-sectional transmission electron microscopy image, and no dislocation-related luminescence was observed in the low-temperature photoluminescence spectra. We deduce the 0.78 eV emission originates from the irradiative recombination in the strain region of diodes caused by the diffusion of large number of boron atoms into silicon crystal lattice.

  13. A system to deposit boron films (boronization) in the DIII-D tokamak

    International Nuclear Information System (INIS)

    A system has been added to the D3-D tokamak to coat its plasma facing surfaces with a film of boron using diborane gas. The system includes special health and safety equipment for handling the diborane gas which is toxic and inflammable. The purpose of the boron film is to reduce the levels of impurity atoms in the D3-D plasmas. Experiments following the application of the boron film in D3-D have led to significant reductions in plasma impurity levels and the observation of a new, very high confinement regime. 9 refs., 1 fig

  14. 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.

  15. Enhanced Plasma Performance by ICRF Boronization

    Institute of Scientific and Technical Information of China (English)

    万宝年; 赵燕平; 李建刚; 宋梅; 吴振伟; 罗家融; 李成富; 王小明

    2002-01-01

    Boronization with carborane (C2B10H12) by ICRF has been applied routinely to the walls of HT-7 super-conducting tokamak for the reduction of impurity influx, especially carbon and oxygen. Significant suppression of metallic impurities and radiating power fraction are achieved. The improved confinement for both particle and energy is observed in full range of operation parameters. Energy balance analysis shows that electron heat diffusion coefficient is strongly reduced. Measurements by Langmuir probes at the edge plasma show that the poloidal velocity shear after boronization is changed to a profile favoring to good confinement. The main emphasis of this paper is to describe effects of boronization on aspects of the enhanced plasma performance.

  16. 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.

  17. 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.

  18. 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

  19. Boron Nitride Nanotubes for Spintronics

    Directory of Open Access Journals (Sweden)

    Kamal B. Dhungana

    2014-09-01

    Full Text Available 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. Boron nitride nanotubes for spintronics.

    Science.gov (United States)

    Dhungana, Kamal B; Pati, Ranjit

    2014-01-01

    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. PMID:25248070

  1. Computational Aspects of Carbon and Boron Nanotubes

    Directory of Open Access Journals (Sweden)

    Paul Manuel

    2010-11-01

    Full Text Available Carbon hexagonal nanotubes, boron triangular nanotubes and boron a-nanotubes are a few popular nano structures. Computational researchers look at these structures as graphs where each atom is a node and an atomic bond is an edge. While researchers are discussing the differences among the three nanotubes, we identify the topological and structural similarities among them. We show that the three nanotubes have the same maximum independent set and their matching ratios are independent of the number of columns. In addition, we illustrate that they also have similar underlying broadcasting spanning tree and identical communication behavior.

  2. Direct evidence of metallic bands in a monolayer boron sheet

    Science.gov (United States)

    Feng, Baojie; Zhang, Jin; Liu, Ro-Ya; Iimori, Takushi; Lian, Chao; Li, Hui; Chen, Lan; Wu, Kehui; Meng, Sheng; Komori, Fumio; Matsuda, Iwao

    2016-07-01

    The search for metallic boron allotropes has attracted great attention in the past decades and recent theoretical works predict the existence of metallicity in monolayer boron. Here, we synthesize the β12-sheet monolayer boron on a Ag(111) surface and confirm the presence of metallic boron-derived bands using angle-resolved photoemission spectroscopy. The Fermi surface is composed of one electron pocket at the S ¯ point and a pair of hole pockets near the X ¯ point, which is supported by the first-principles calculations. The metallic boron allotrope in β12 sheet opens the way to novel physics and chemistry in material science.

  3. 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

  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. A colorimetric determination of boron in biological sample for boron neutron capture therapy (BNCT)

    International Nuclear Information System (INIS)

    The boron neutron capture therapy (BNCT) has shown better prognosis in the treatment of glyemas and gluoblastomas grade III and IV than other therapies. During the treatment the levels of Na210B12H11SH must be known in several compartiments of the organism and with this purpose the method of colorimetric determination of boron using curcumine was established. This method is simple, reprodutible and adequate sensitivity for this control. (author)

  7. The structure and local chemical properties of boron-terminated tetravacancies in hexagonal boron-nitride

    OpenAIRE

    Cretu, Ovidiu; Lin, Yung-Chang; Koshino, Masanori; Tizei, Luiz H. G.; Liu, Zheng; Suenaga, Kazutomo

    2014-01-01

    Imaging and spectroscopy performed in a low-voltage scanning transmission electron microscope (LV-STEM) are used to characterize the structure and chemical properties of boron-terminated tetravacancies in hexagonal boron nitride (h-BN). We confirm earlier theoretical predictions about the structure of these defects and identify new features in the electron energy-loss spectra (EELS) of B atoms using high resolution chemical maps, highlighting differences between these areas and pristine sampl...

  8. Valence band offset and Schottky barrier at amorphous boron and boron carbide interfaces with silicon and copper

    International Nuclear Information System (INIS)

    In order to understand the fundamental charge transport in a-B:H and a-BX:H (X = C, N, P) compound heterostructure devices, X-ray photoelectron spectroscopy has been utilized to determine the valence band offset and Schottky barrier present at amorphous boron compound interfaces formed with (1 0 0) Si and polished poly-crystalline Cu substrates. For interfaces formed by plasma enhanced chemical vapor deposition of a-B4–5C:H on (1 0 0) Si, relatively small valence band offsets of 0.2 ± 0.2 eV were determined. For a-B:H/Cu interfaces, a more significant Schottky barrier of 0.8 ± 0.16 eV was measured. These results are in contrast to those observed for a-BN:H and BP where more significant band discontinuities (>1–2 eV) were observed for interfaces with Si and Cu.

  9. Effects of boron number per unit volume on the shielding properties of composites made with boron ores form China

    International Nuclear Information System (INIS)

    The total macroscopic removal cross sections, deposited energies and the absorbed doses of three new shielding composites loaded with specific boron-rich slag, boron concentrate ore and boron mud of China for 252Cf neutron source were investigated by experimental and Monte Carlo calculation. The results were evaluated by boron mole numbers per unit volume in composites. The half value layers of the composites were calculated and compared with that of Portland concrete, indicating that ascending boron mole numbers per unit volume in the composites can enhance the shielding properties of the composites for 252Cf neutron source. (authors)

  10. Oilseed rape genotypes response to boron toxicity

    Directory of Open Access Journals (Sweden)

    Savić Jasna

    2013-01-01

    Full Text Available Response of 16 oilseed rape genotypes to B (boron toxicity was analyzed by comparing the results of two experiments conducted in a glasshouse. In Experiment 1 plants were grown in standard nutrient solutions with 10 µMB (control and 1000 µM B. Relative root and shoot growth varied from 20-120% and 31-117%, respectively. Variation in B concentration in shoots was also wide (206.5-441.7 µg B g-1 DW as well as total B uptake by plant (62.3-281.2 µg B g1. Four selected genotypes were grown in Experiment 2 in pots filled with high B soil (8 kg ha-1 B; B8. Shoot growth was not affected by B8 treatment, while root and shoot B concentration was significantly increased compared to control. Genotypes Panther and Pronto which performed low relative root and shoot growth and high B accumulation in plants in Experiment 1, had good growth in B8 treatment. In Experiment 2 genotype NS-L-7 had significantly lower B concentration in shots under treatment B8, but also very high B accumulation in Experiment 1. In addition, cluster analyses classified genotypes in three groups according to traits contrasting in their significance for analyzing response to B toxicity. The first group included four varieties based on their shared characteristics that have small value for the relative growth of roots and shoots and large values of B concentration in shoot. In the second largest group were connected ten genotypes that are heterogeneous in traits and do not stand out on any characteristic. Genotypes NS-L-7 and Navajo were separated in the third group because they had big relative growth of root and shoot, but also a high concentration of B in the shoot, and high total B uptake. Results showed that none of tested genotypes could not be recommended for breeding process to tolerance for B toxicity. [Projekat Ministarstva nauke Republike Srbije, br. OI 173028

  11. 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.

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

    International Nuclear Information System (INIS)

    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

  13. 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.

  14. 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. PMID:18961131

  15. 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.

  16. 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.

  17. Novel Boron Based Multilayer Thermal Neutron Detector

    CERN Document Server

    SCHIEBER, M

    2010-01-01

    The detector contains four or more layers of natural Boron absorbing thermal neutrons. Thickness of a layer is 0.4 - 1.2 mg/cm2. The layers are deposited on one or on both sides of a metal surface used as contacts. Between the absorbing layers there are gas-filled gaps 3 - 6 mm thick. Electric field of 100 - 200 V/cm is applied to the gas-filled gaps. Natural Boron contains almost 20% of 10B isotope. When atoms of 10B capture a thermal neutron, nuclear reaction occurs, as a result of which two heavy particles - alpha particle and ion 7Li - from the thin absorber layer are emitted in opposing sides. One of the two particles penetrates into gas-filled gap between Boron layers and ionizes the gas. An impulse of electric current is created in the gas-filled gap actuated by the applied electric field. The impulse is registered by an electronic circuit. We have made and tested detectors containing from two to sixteen layers of natural Boron with an efficiency of thermal neutron registration from 2.9% to 12.5% accor...

  18. 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.

  19. 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...

  20. 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$_{n}^{+}$.

  1. 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. ...

  2. 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...

  3. 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. ...

  4. 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 %.

  5. 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)

  6. BCM6: New Generation of Boron Meter

    International Nuclear Information System (INIS)

    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

  7. A mass spectrometric study of the vaporization of boron phosphate (BPO(4))

    Science.gov (United States)

    Lopatin; Semenov

    1999-01-01

    The vaporization behavior of boron phosphate has been studied by using Knudsen effusion mass spectrometry. The vapor over BPO(4) consists of B(2)O(3), P(4)O(10), PO(2), BPO(4) (platinum cell) and B(2)O(3), PO, PO(2), BPO(3), BPO(4) (molybdenum cell). Standard enthalpies of formation and atomization (kJ/mol) were derived for BPO(4) (g) (-1000 +/- 15 and 2863 +/- 16) and for BPO(3) (g) (-731 +/- 15 and 2347 +/- 16), respectively. Copyright 1999 John Wiley & Sons, Ltd.

  8. 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.

  9. Boron removal from aqueous solution by direct contact membrane distillation

    International Nuclear Information System (INIS)

    The removal of boron from aqueous solution by direct contact membrane distillation (DCMD) was studied with self-prepared polyvinylidene fluoride (PVDF) hollow fiber membranes in the present work. The effect of pH, boron concentration, temperature and salt concentration of the feed solution on the boron rejection was investigated. The experimental results indicated that boron rejection was less dependent on the feed pH and salt concentration. DCMD process had high boron removal efficiency (>99.8%) and the permeate boron was below the maximum permissible level even at feed concentration as high as 750 mg/L. Although the permeate flux was enhanced exponentially with the feed temperature increasing, the influence of feed temperature on the boron rejection could be neglected. Finally, the natural groundwater sample containing 12.7 mg/L of boron was treated by DCMD process. The permeate boron kept below 20 μg/L whether the feed was acidified or not, but pre-acidification was helpful to maintain the permeate flux stability. All the experimental results indicated that DCMD could be efficiently used for boron removal from aqueous solution.

  10. 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.

  11. Hot rolling of chromium - nickel - manganese stainless steel containing nitrogen and boron

    International Nuclear Information System (INIS)

    The strength of stainless steel of the 03Kh2ON16AG6 type increases perceptibly with an increase in the nitrogen content from 0.11 to 0.37%. At the same time, however, its ductility in the region of hot deformation temperatures (red brittleness range of 800 to 1,000 deg C) decreases. Microalloying with boron (0.002 to 0.005% by calculation) permits enhancing the hot ductility to an acceptable level without adversely affecting the working properties. The mechaniusm of boron effect is analyzed. The temperature at which ingots are heated prior to rolling to achieve the desired effect must be sufficiently low. Optimum condition for two stage heating of 6.2-ton ingots are recommeded

  12. The electronic transport behavior of hybridized zigzag graphene and boron nitride nanoribbons

    International Nuclear Information System (INIS)

    In this present work, we have investigated the electronic transport properties of the hybridized structure constructed by the zigzag graphene and boron-nitride (BN) nanoribbons (Z-BnNmCp, n + m + p = 16) through employing nonequilibrium Green's functions in combination with the density-functional theory. The results demonstrate that the electronic transport properties of the hybridized Z-BnNmCp nanoribbons are strongly dependent on the width of boron-nitride or graphene nanoribbons. When the numbers of n and m are not equal, the negative differential resistance behavior is observed, which can be modulated by varying the width of BN nanoribbons. The conductance of the hybridized Z-BnNmCp nanoribbons with odd numbers of zigzag carbon chains also increases by the width of BN nanoribbons

  13. 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.

  14. 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.

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

    International Nuclear Information System (INIS)

    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 μg 10B/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 10B/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. 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...

  17. 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.

  18. 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.

  19. 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.

  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. 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.

  2. The spectrophotometric determination of boron in tourmalines

    Directory of Open Access Journals (Sweden)

    LJILJANA JAKSIC

    2005-02-01

    Full Text Available A procedure for the spectrophotometric determination of macro amounts of boron in tourmaline with azomethine H is described. The used tourmaline concentrate was obtained by magnetic separation and heavy-liquids purification of the schorl zone of pegmatite or granite aplite. The samples of tourmaline were decomposed by fusion with anhydrous sodium carbonate and taken up in dilute hydrochloric acid. The interfering effects of iron and aluminium were eliminated by masking with an EDTA – NTA solution. After pH adjustment, the boron was reacted with azomethine H and the absorbance of the obtained coloured complex was measured at 415 nm. The results are compared with those obtained by other procedures. The relative error of the determination was less than 3 %.

  3. Techniques for increasing boron fiber fracture strain

    Science.gov (United States)

    Dicarlo, J. A.

    1977-01-01

    Improvement in the strain-to-failure of CVD boron fibers is shown possible by contracting the tungsten boride core region and its inherent flaws. The 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 micrometers (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. 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 are presented and discussed both for high vacuum and argon gas heat treatment environments.

  4. 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.

  5. Synthesis and characterization of boron nitrides nanotubes

    International Nuclear Information System (INIS)

    This paper presents a new synthesis for the production of boron nitride nanotubes (BNNT) from boron powder, ammonium nitrate and hematite tube furnace CVD method. The samples were subjected to some characterization techniques as infrared spectroscopy, thermal analysis, X-ray diffraction and scanning electron microscopy and transmission. By analyzing the results can explain the chemical reactions involved in the process and confirm the formation of BNNT with several layers and about 30 nanometers in diameter. Due to excellent mechanical properties and its chemical and thermal stability this material is promising for various applications. However, BNNT has received much less attention than carbon nanotubes, it is because of great difficulty to synthesize appreciable quantities from the techniques currently known, and this is one of the main reasons this work.(author)

  6. 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.

  7. Multidimensional boron transport modeling in subchannel approach

    International Nuclear Information System (INIS)

    The main objective of this study is to implement a solute tracking model into the subchannel code CTF for simulations of boric acid transients. Previously, three different boron tracking models have been implemented into CTF and based on the applied analytical and nodal sensitivity studies the Modified Godunov Scheme approach with a physical diffusion term has been selected as the most accurate and best estimate solution. This paper will present the implementation of a multidimensional boron transport modeling with Modified Godunov Scheme within a thermal-hydraulic code based on a subchannel approach. Based on the cross flow mechanism in a multiple-subchannel rod bundle geometry, heat transfer and lateral pressure drop effects will be discussed in deboration and boration case studies. (author)

  8. 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.

  9. 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.

  10. Functionalized boron-dipyrromethenes and their applications

    OpenAIRE

    M. Ravikanth, M; Vellanki,Lakshmi; Sharma,Ritambhara

    2016-01-01

    Vellanki Lakshmi, Ritambhara Sharma, Mangalampalli Ravikanth Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, IndiaAbstract: Boron-dipyrromethenes/BF2-dipyrrins (BODIPYs) are highly fluorescent dyes with a wide range of applications in various fields because of their attractive photophysical properties. One of the salient features of BODIPYs is that the properties of the BODIPY can be fine-tuned at will by selectively introducing the substituent(s) at the desired locati...

  11. 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.

  12. 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.

  13. Boron Nitride Nanosheets for Metal Protection

    OpenAIRE

    Li, Lu Hua; Xing, Tan; Chen, Ying; Jones, Rob

    2015-01-01

    Although the high impermeability of graphene makes it an excellent barrier to inhibit metal oxidation and corrosion, graphene can form a galvanic cell with the underlying metal that promotes corrosion of the metal in the long term. Boron nitride (BN) nanosheets which have a similar impermeability could be a better choice as protective barrier, because they are more thermally and chemically stable than graphene and, more importantly, do not cause galvanic corrosion due to their electrical insu...

  14. Anomalous thermal conductivity of monolayer boron nitride

    Science.gov (United States)

    Tabarraei, Alireza; Wang, Xiaonan

    2016-05-01

    In this paper, we use nonequilibrium molecular dynamics modeling to investigate the thermal properties of monolayer hexagonal boron nitride nanoribbons under uniaxial strain along their longitudinal axis. Our simulations predict that hexagonal boron nitride shows an anomalous thermal response to the applied uniaxial strain. Contrary to three dimensional materials, under uniaxial stretching, the thermal conductivity of boron nitride nanoribbons first increases rather than decreasing until it reaches its peak value and then starts decreasing. Under compressive strain, the thermal conductivity of monolayer boron nitride ribbons monolithically reduces rather than increasing. We use phonon spectrum and dispersion curves to investigate the mechanism responsible for the unexpected behavior. Our molecular dynamics modeling and density functional theory results show that application of longitudinal tensile strain leads to the reduction of the group velocities of longitudinal and transverse acoustic modes. Such a phonon softening mechanism acts to reduce the thermal conductivity of the nanoribbons. On the other hand, a significant increase in the group velocity (stiffening) of the flexural acoustic modes is observed, which counteracts the phonon softening effects of the longitudinal and transverse modes. The total thermal conductivity of the ribbons is a result of competition between these two mechanisms. At low tensile strain, the stiffening mechanism overcomes the softening mechanism which leads to an increase in the thermal conductivity. At higher tensile strain, the softening mechanism supersedes the stiffening and the thermal conductivity slightly reduces. Our simulations show that the decrease in the thermal conductivity under compressive strain is attributed to the formation of buckling defects which reduces the phonon mean free path.

  15. Clinical aspects of boron neutron capture therapy

    International Nuclear Information System (INIS)

    Boron neutron capture therapy is potentially useful in treating malignant tumors of the central nervous system and is technically possible. Additional in vitro and in vivo testing is required to determine toxicities, normal tissue tolerances and tissue responses to treatment parameters. Adequate tumor uptake of the capture agent can be evaluated clinically prior to implementation of a finalized treatment protocol. Phase I and Phase II protocol development, clinical pharmacokinetic studies and neutron beam development

  16. Dosage of boron traces in graphite, uranium and beryllium oxide

    International Nuclear Information System (INIS)

    The problem of the dosage of the boron in the materials serving to the construction of nuclear reactors arises of the following way: to determine to about 0,1 ppm close to the quantities of boron of the order of tenth ppm. We have chosen the colorimetric analysis with curcumin as method of dosage. To reach the indicated contents, it is necessary to do a previous separation of the boron and the materials of basis, either by extraction of tetraphenylarsonium fluoborate in the case of the boron dosage in uranium and the beryllium oxide, either by the use of a cations exchanger resin of in the case of graphite. (M.B.)

  17. 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.

  18. 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.

  19. 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.

  20. Production process for boron carbide coated carbon material and boron carbide coated carbon material obtained by the production process

    International Nuclear Information System (INIS)

    A boron carbide coated carbon material is used for a plasma facing material of a thermonuclear reactor. The surface of a carbon material is chemically reacted with boron oxide to convert it into boron carbide. Then, it is subjected to heat treatment at a temperature of not lower than 1600degC in highly evacuated or inactive atmosphere to attain a boron carbide coated carbon material. The carbon material used is an artificial graphite or a carbon fiber reinforced carbon composite material. In the heat treatment, when the atmosphere is in vacuum, it is highly evacuated to less than 10Pa. Alternatively, in a case of inactive atmosphere, argon or helium gas each having oxygen and nitrogen content of not more than 20ppm is used. With such procedures, there can be obtained a boron carbide-coated carbon material with low content of oxygen and nitrogen impurities contained in the boron carbide coating membrane thereby hardly releasing gases. (I.N.)

  1. 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.

  2. 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.

  3. Considerations for boron neutron capture therapy studies

    International Nuclear Information System (INIS)

    Radiotherapy is indispensable as a mean to eradicate deeply or infiltrating tumor tissue that can not be removed surgically. Therefore, it is not selective and may also kill the surrounding health tissue. The principle of BNCT (Boron Neutron Capture Therapy) consist in targeting a tumor selectively with a boron-10 compound. This nuclide has a large capture cross section for thermal neutrons and the nuclear reaction and the delivered energy in locus will selective the tumor. Since its initial proposal in 1963 BNCT has made much progress, however it is not used in a routine treatment. In this work it was approached some complex procedures, as the obtention of selective boron compounds, the adequate set up of neutron beams, the biodistribution, the in vivo and in vitro studies, and also human patients treatments. This work provide fundamentals about BNCT to professional of different areas of knowledge since it comprises multidisciplinary study. It includes appendixes for the ones not related to the field for a better comprehension of the many aspects involved. It is also presented a glossary containing technical and basic aspects involved. It is also presented a glossary containing technical and basic terms referred in the work. (author). 174 refs, 1 fig, 12 apps

  4. 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. PMID:17046244

  5. Longitudinal residual stresses in boron fibers

    Science.gov (United States)

    Behrendt, D. R.

    1976-01-01

    A technique is proposed for measuring the longitudinal residual stress distribution in commercial CVD (Chemical Vapor Deposition) boron on tungsten fibers of 102, 142, and 203 microns in diameter. The experimental apparatus is so designed that continuous measurements are made of the length changes of a boron fiber specimen as the surface of the fiber is removed by electropolishing. The effects of surface removal on core residual stress and core-initiated fracture are discussed. The three sizes of boron fibers investigated show similar residual stress distributions, i.e., compressive at the surface, tensile near the core, and for the 102-micron fiber compressive again in the core. It is shown that an increase in UTS is due to the increase in the compressive stress at the core produced by fiber contraction during surface removal. An expression is derived for calculating the longitudinal residual stress at a given radius for an as-received fiber of a certain radius from measurements of the axial strain produced by removal of the surface by electropolishing.

  6. Boron dose enhancement for Cf-252 brachytherapy

    International Nuclear Information System (INIS)

    Full text: Monte Carlo modelling of a Cf-252 source in water and in tissue has shown that there is a significant therapeutic advantage obtained if B-10 is present in the tumour cells. This study analyses the advantage in terms of therapeutic margin, defined as the distance from the border of the treatment volume where boron-loaded tumour cells will receive a therapeutic dose. Calculations were made with MCNP version 4a on a Pentium 60 MHz computer. Large voxel sizes allowed 70 minute runs to achieve statistical uncertainties of 5% or less for 100,000 source neutrons. Later runs with smaller voxels confirmed the accuracy of the initial calculations. Calculations were made for treatment volume radii up to 11 cm and 30 ppm boron-10. The therapeutic margin for radii in the range 3-9 cm is approximately 10% of the tumour radius. This results in a 30% increase in the volume inside which peripheral tumour cells may receive a therapeutic dose. The median therapeutic ratio within the therapeutic margin varied from 1.05 at 3 cm up to 1.25 at 10 cm. Thus there is little benefit for less advanced tumours with thickness less than 3 cm. However, cervical cancer frequently presents in an advanced state in Southeast Asia and in Aboriginal communities in Australia, partially attributable to low Pap smear screening rates. These conclusions support the development and testing of boron compounds in in vitro and in vivo models for cervical cancer

  7. Structure and local chemical properties of boron-terminated tetravacancies in hexagonal boron nitride.

    Science.gov (United States)

    Cretu, Ovidiu; Lin, Yung-Chang; Koshino, Masanori; Tizei, Luiz H G; Liu, Zheng; Suenaga, Kazutomo

    2015-02-20

    Imaging and spectroscopy performed in a low-voltage scanning transmission electron microscope are used to characterize the structure and chemical properties of boron-terminated tetravacancies in hexagonal boron nitride. We confirm earlier theoretical predictions about the structure of these defects and identify new features in the electron energy-loss spectra of B atoms using high resolution chemical maps, highlighting differences between these areas and pristine sample regions. We correlate our experimental data with calculations which help explain our observations. PMID:25763963

  8. Synovectomy by neutron capture in boron

    International Nuclear Information System (INIS)

    The rheumatoid arthritis is an illness which affect approximately at 3% of the World population. This illness is characterized by the inflammation of the joints which reduces the quality of life and the productivity of the patients. Since, it is an autoimmune illness, the inflammation is due to the overproduction of synovial liquid by the increase in the quantity of synoviocytes. The rheumatoid arthritis does not have a definitive recovery and the patients have three options of treatment: the use of drugs, the surgery and the radio synovectomy. The synovectomy by neutron capture in Boron is a novel proposal of treatment of the rheumatoid arthritis that consists in using a charged compound with Boron 10 that is preferently incorporated in the synoviocytes and to a less extent in the rest of surrounding tissues of the joint. Then, the joint is exposed to a thermal neutron field that induces the reaction (n, α) in the 10 B. the products of this reaction place their energy inside synoviocytes producing their reduction and therefore the reduction of the joint inflammation. Since it is a novel procedure, the synovectomy by neutron capture in boron has two problems: the source design and the design of the adequate drug. In this work it has been realized a Monte Carlo study with the purpose to design a moderating medium that with a 239 Pu Be source in its center, produces a thermal neutron field. With the produced neutron spectra, the neutrons spectra and neutron doses were calculated in different sites inside a model of knee joint. In Monte Carlo studies it is necessary to know the elemental composition of all the joint components, for the case of synovia and the synovial liquid this information does not exist in such way that it is supposed that its composition is equal than the water. In this work also it has been calculated the kerma factors by neutrons of synovia and the synovial liquid supposing that their elemental composition are similar to the blood tissue

  9. Cosmis Lithium-Beryllium-Boron Story

    Science.gov (United States)

    Vangioni-Flam, E.; Cassé, M.

    Light element nucleosynthesis is an important chapter of nuclear astrophysics. Specifically, the rare and fragile light nuclei Lithium, Beryllium and Boron (LiBeB) are not generated in the normal course of stellar nucleosynthesis (except Lithium-7) and are, in fact, destroyed in stellar interiors. This characteristic is reflected in the low abundance of these simple species. Up to recently, the most plausible interpretation was that galactic cosmic rays (GCR) interact with interstellar CNO to form LiBeB. Other origins have been also identified, primordial and stellar (Lithium-7) and supernova neutrino spallation (Lithium-7 and Boron-11). In contrast, Beryllium-9, Boron-10 and Lithium-6 are pure spallative products. This last isotope presents a special interest since the Lithium-7/Lithium-6 ratio has been measured in a few halo stars offering a new constraint on the early galactic evolution. However, in the nineties, new observations prompted astrophysicists to reassess the question. Optical measurements of the beryllium and boron abundances in halo stars have been achieved by the 10 meters KECK telescope and the Hubble Space Telescope. These observations indicate a quasi linear correlation between Be and B vs Fe, at least at low metallicity, unexpected on the basis of GCR scenario, predicting a quadratic relationship. As a consequence, the origin and the evolution of the LiBeB nuclei has been revisited. This linearity implies the acceleration of C and O nuclei freshly synthesized and their fragmentation on the the interstellar Hydrogen and Helium. Wolf-Rayet stars and supernovae via the shock waves induced, are the best candidates to the acceleration of their own material enriched into C and O; so LiBeB is produced independently of the Interstellar Medium chemical composition. Moreover, neutrinos emitted by the newly born neutron stars interacting with the C layer of the supernova could produce specifically Lithium-7 and Boron-11. This process is supported by the

  10. Implementation of Low Boron Core for APR1400 Initial Cycle

    International Nuclear Information System (INIS)

    Low boron capability of a nuclear power plant is rather a qualitative specification requiring the nuclear power plant to be shut down by control rods alone at any time of a plant cycle according to EUR. The reduction of soluble boron is beneficial since it gives the reduction of the corrosive effects in the plant system and improves plant safety giving more negative MTC. Thus, it is necessary to reduce the amount of soluble boron for the criticality to achieve the low boron capability. However, the reduction of soluble boron has its own set of specific challenges that must be overcome. There are two methods to enable the reduction of soluble boron without modifying plant system significantly. The goal of this study is to investigate the loading pattern to achieve the soluble boron reduction for Shin-Kori Unit 5 APR1400 initial core using the low and high content gadolinia burnable absorbers with standard fuel rod enrichment and to verify the feasibility of low boron core with conventional gadolinia burnable absorbers only. For this study, KARMA has been employed to solve 2-D Transport equation, and ASTRA is used for full core analysis. It was possible to achieve the low boron core for APR1400 Cycle 1 using extended usage of two types of gadolinia burnable absorbers sacrificing fuel cycle economy a little bit while enhancing plant safety significantly. Gd rod patterns within an assembly were optimized through geometrical weighting and loading pattern was developed based on these patterns. The amount of soluble boron reduction achieved is 45.4%. The improvement in plant safety is significant resulting in the reduction of least negative best-estimate MTC by about 4 pcm. Also shutdown margin is increased slightly for low boron core. However, the behavior of axial power shape turns out to be undesirable showing a relatively large fluctuation caused by the more negative MTC. It was found that the low boron core might impose kind of operational difficulty. It is usually

  11. 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.

  12. Carborane derivatives loaded into liposomes as efficient delivery systems for boron neutron capture therapy.

    Science.gov (United States)

    Altieri, S; Balzi, M; Bortolussi, S; Bruschi, P; Ciani, L; Clerici, A M; Faraoni, P; Ferrari, C; Gadan, M A; Panza, L; Pietrangeli, D; Ricciardi, G; Ristori, S

    2009-12-10

    Boron neutron capture therapy (BNCT) is an anticancer therapy based on the incorporation of (10)B in tumors, followed by neutron irradiation. Recently, the synthesis and delivery of new boronated compounds have been recognized as some of the main challenges in BNCT application. Here, we report on the use of liposomes as carriers for BNCT active compounds. Two carborane derivatives, i.e., o-closocarboranyl beta-lactoside (LCOB) and 1-methyl-o-closocarboranyl-2-hexylthioporphyrazine (H(2)PzCOB), were loaded into liposomes bearing different surface charges. The efficacy of these formulations was tested on model cell cultures, that is, DHD/K12/TRb rat colon carcinoma and B16-F10 murine melanoma. These induce liver and lung metastases, respectively, and are used to study the uptake of standard BNCT drugs, including borophenylalanine (BPA). Boron concentration in treated cells was measured by alpha spectrometry at the TRIGA mark II reactor (University of Pavia). Results showed high performance of the proposed formulations. In particular, the use of cationic liposomes increased the cellular concentration of (10)B by at least 30 times more than that achieved by BPA. PMID:19954249

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhonglu

    2006-08-01

    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 cm{sup 2} treatment beam. The calculated boron dose enhancement at 5.7-cm depth in a water-filled head phantom in the assembly with a 5x5 cm{sup 2} collimation was 21.9% per 100-ppm {sup 10}B 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 cm{sup 2} fast neutron treatment beam. To validate the design calculations, a simplified BNCEFNT assembly was built using four lead bricks to form a 5x5 cm{sup 2} collimator. Five 1.0-cm thick 20x20 cm{sup 2} 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 {sup 10}B) to measure dose due to boron neutron capture. The measured dose enhancement at 5.0-cm depth

  14. 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

  15. Influence of Boron on transformation behavior during continuous cooling of low alloyed steels

    Energy Technology Data Exchange (ETDEWEB)

    Terzic, A., E-mail: Adnan.Terzic@imf.tu-freiberg.de [Technische Universität Bergakademie Freiberg, Institute of Metal Forming, Bernhard-von-Cotta-Str. 4, 09596 Freiberg (Germany); Calcagnotto, M. [Salzgitter Mannesmann Forschung GmbH, Eisenhüttenstr. 99, 38239 Salzgitter (Germany); Guk, S. [Technische Universität Bergakademie Freiberg, Institute of Metal Forming, Bernhard-von-Cotta-Str. 4, 09596 Freiberg (Germany); Schulz, T. [Salzgitter Mannesmann Forschung GmbH, Eisenhüttenstr. 99, 38239 Salzgitter (Germany); Kawalla, R. [Technische Universität Bergakademie Freiberg, Institute of Metal Forming, Bernhard-von-Cotta-Str. 4, 09596 Freiberg (Germany)

    2013-11-01

    Abstracts: The phase transformation behavior during continuous cooling of low-carbon (LC) Boron-treated steels was studied. Furthermore, the influence of combining Boron with Nb or Ti or V on transformation kinetics was investigated. Additions of Boron to LC steels have a strong influence on the ferrite transformation. By adding 30 ppm Boron to a Boron-free reference alloy the suppressing effect on the ferrite transformation is most pronounced, whereas 10 ppm Boron has almost no effect and 50 ppm Boron the same effect as 30 ppm Boron. Thereby the critical Boron concentration for transformation kinetics in this alloying concept is 30 ppm. The combination of Boron with Ti shifts the phase fields to shorter times and increase the ferrite start temperature, whereas the combination of B+V and B+Nb only affects the ferrite start temperature. Hardness values are mostly influenced by the presence of Boron and strongly depend on the cooling rate.

  16. 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.

  17. 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 .

  18. Adsorption characteristics of arsenic and boron by soil

    Energy Technology Data Exchange (ETDEWEB)

    Sakata, M.

    1986-01-01

    In order to obtain baseline data concerning the surface and ground water pollution caused by coal ash disposal, adsorption characteristics of arsenic (III) and boron by soil have been studied through laboratory experiments. The main results are as follows: (1) Arsenic (III) and boron adsorption on soil was strongly dependent on pH with adsorption maxima at pH 8 and 8-9, respectively. (2) Arsenic (III) and boron adsorption on soil over the entire concentration ranges investigated could be described by the Langmuir adsorption isotherm and the Freundlich adsorption isotherm, respectively. The Henry adsorption isotherm was also applicable over the lower concentration ranges of arsenic (III) and boron (As (III): < 0.1 deltag/ml; B: < 5deltag/ml.) (3) Arsenic (III) and boron adsorption on soil is controlled mainly by the contents of extractable Fe oxide and hydroxide for arsenic (III) and by the contents of extractable Al hydroxide and allophane (amorphous aluminium silicates) for boron. (4) Adsorption and movement of arsenic (III) and boron during the infiltration of coal ash leachate in soil layer were investigated by means of the unsteady-state, one-dimensional convective-diffusive mass transport model. This model is very useful for evaluation and prediction of the contamination of ground water by trace elements such as arsenic (III) and boron leached at coal ash disposal site.

  19. Removal of boron species by layered double hydroxides: a review.

    Science.gov (United States)

    Theiss, Frederick L; Ayoko, Godwin A; Frost, Ray L

    2013-07-15

    Boron, which is an essential element for plants, is toxic to humans and animals at high concentrations. Layered double hydroxides (LDHs) and thermally activated LDHs have shown good uptake of a range of boron species in laboratory scale experiments when compared to current available methods, which are for the most part ineffective or prohibitively expensive. LDHs were able to remove anions from water by anion exchange, the reformation (or memory) effect and direct precipitation. The main mechanism of boron uptake appeared to be anion exchange, which was confirmed by powder X-ray diffraction (XRD) measurements. Solution pH appeared to have little effect on boron sorption while thermal activation did not always significantly improve boron uptake. In addition, perpetration of numerous LDHs with varying boron anions in the interlayer region by direct co-precipitation and anion exchange have been reported by a number of groups. The composition and orientation of the interlayer boron ions could be identified with reasonable certainty by applying a number of characterisation techniques including: powder XRD, nuclear magnetic resonance spectroscopy (NMR), X-ray photoelectron spectroscopy (XPS) and infrared (IR) spectroscopy. There is still considerable scope for future research on the application of LDHs for the removal of boron contaminants. PMID:23635479

  20. Design, Fabrication and Performance of Boron-Carbide Control Elements

    International Nuclear Information System (INIS)

    A control blade design, incorporating boron-carbide (B4C) in stainless-steel tubes, was introduced into service in boiling water reactors in April 1961. Since that time this blade has become the standard reference control element in General Electric boiling-water reactors, replacing the 2% boron-stainless-steel blades previously used. The blades consist of a sheathed, cruciform array of small vertical stainless-steel tubes filled with compácted boron-carbide powder. The boron-carbide powder is confined longitudinally into several independent compartments by swaging over ball bearings located inside the tubes. The development and use of boron-carbide control rods is discussed in five phases: 1. Summary of experience with boron-steel blades and reasons for transition to boron-carbide control; 2. Design of the boron-carbide blade, beginning with developmental experiments, including early measurements performed in the AEC ''Control Rod Material and Development Program'' at the Vallecitos Atomic Laboratory, through a description of the final control blade configuration; 3. Fabrication of the blades and quality control procedures; 4. Results of confirmatory pre-operational mechanical and reactivity testing; and 5. Post-operational experience with the blades, including information on the results of mechanical inspection and reactivity testing after two years of reactor service. (author)

  1. 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.

  2. Determination of boron in silicates after ion exchange separation

    Science.gov (United States)

    Kramer, H.

    1955-01-01

    Existing methods for the determination of boron in silicates are not entirely satisfactory. Separation as the methyl ester is lengthy and frequently erratic. An accurate and rapid method applicable to glass, mineral, ore, and water samples uses ion exchange to remove interfering cations, and boron is determined titrimetrically in the presence of mannitol, using a pH meter to indicate the end point.

  3. 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.

  4. 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...

  5. Eleventh international conference on boron chemistry. Programme and abstracts

    International Nuclear Information System (INIS)

    Abstracts of reports at the Eleventh International Conference on Boron Chemistry are presented. Born chemistry as a connecting bridge between many fields maintains one of the leading positions in modern chemistry. Methods of synthesis of different boron compounds, properties of the compounds, their use in other regions of chemistry and medicine are widely presented in reports

  6. Boron Speciation in Soda-Lime Borosilicate Glasses Containing Zirconium

    International Nuclear Information System (INIS)

    Boron speciation was investigated in soda-lime borosilicate glass containing zirconium. In such compositions, competition between charge compensators (here, sodium and calcium) can occur for the compensation of tetrahedral boron or octahedral zirconium units. 11B MAS NMR is particularly suitable for obtaining data on preferential compensation behavior that directly affects the boron coordination number. In addition to the classical proportions of tri- and tetrahedral boron, additional data can be obtained on the contributions involved in these two coordination numbers. An approach is described here based on simultaneous MAS spectrum analysis of borosilicate glass with variable Zr/Si and Ca/Na ratios at two magnetic field strengths (11. 7 and 18. 8 T), with constraints arising from MQMAS spectroscopy, detailed analysis of satellite transitions, and spin-echo experiments. New possibilities of 11B NMR were presented for improving the identification and quantification of the different contributions involved in tri- and tetrahedral boron coordination. Both NMR and Raman revealed a trend of decreased tetrahedral boron proportion with the increase of Ca/Na ratio or the Zr/Si ratio. This strongly suggests that zirconium compensation takes preference over boron compensation, and that zirconium and boron are both compensated mainly by sodium rather than calcium. (authors)

  7. 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.

  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. Does boron affect hormone levels of barley cultivars?

    Directory of Open Access Journals (Sweden)

    Muavviz Ayvaz

    2012-11-01

    Full Text Available Background: When mineral nutrients are present in excess or in inadequate amounts, their effects can be severe in plants and can be considered as abiotic stress. In this study, we report how hormonal levels in barley cultivars respond to the toxic effect of boron, an essential plant micronutrient. Material and methods: Two different barley (Hordeum vulgare cultivars (Vamik Hoca and Efes 98 were used as a study material. Boron was applied in three different concentrations (0, 10, 20 ppm to plants that had grown from seeds for four weeks. Plants were harvested, stem-root length and stem-root dry-fresh weight content were determined. For further analysis, chlorophyll, total protein, endogenic IAA and ABA content analyses were carried out. Results: According to the data obtained, plant growth and development decreased with increasing boron concentrations. With increasing boron concentrations, soluble total protein increased in both cultivars. Boron application led to increased endogenic IAA content in both cultivars. 10 and 20 ppm boron application led to increased endogenic ABA content in Vamik Hoca cultivar whereas endogenic ABA content decreased in Efes 98. Absence of boron application led to increased endogenic IAA and ABA content in both cultivars. Conclusion: As a result, the response to boron is different in the two cultivars and Efes 98 may be more resistant to the toxicity than Vamik Hoca cultivar.

  10. Composition and microhardness of CAE boron nitride films

    International Nuclear Information System (INIS)

    The paper deals with boron nitride produced by cathodic arc evaporation techniques.The films were applied on titanium and cemented carbide substrates. Their characterization was carried out using X-ray diffraction and Knoop microhardness tests. Demonstrated are the high properties of two-phase films, containing β (cubic) and γ (wurtzitic) modifications of boron nitride. (author). 7 refs., 1 fig., 3 tabs

  11. Heterogeneous and homogeneous chiral Cu(II) catalysis in water: enantioselective boron conjugate additions to dienones and dienoesters.

    Science.gov (United States)

    Kitanosono, Taku; Xu, Pengyu; Kobayashi, Shū

    2013-09-25

    It was proved that a judicious choice of counteranion played a prominent role in Cu(II) catalysis for enantioselective boron conjugate additions in water; the use of Cu(OH)2 renders heterogeneous catalysis, whereas Cu(OAc)2 renders homogeneous catalysis; cyclic dienones underwent a remarkable switch of regioselectivity between 1,4- and 1,6-modes of the additions through these catalyses.

  12. 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.

  13. 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.

  14. 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.

  15. Optical characteristic analysis of the boronization process by using carborane

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Wonwook; Park, Kyungdeuk; Choi, Youngsun; Oh, Chahwan [Hanyang University, Seoul (Korea, Republic of)

    2014-09-15

    Boronization with carborane (C{sub 2}B{sub 10}H{sub 12}) was achieved in a vacuum vessel coupled to a filament discharge system. Optical emission spectroscopy was employed to characterize the boronization process. The Balmer lines of hydrogen and deuterium were measured, and the boronization process was analyzed by using the intensity ratio of the H{sub α} to the D{sub α} line (I{sub H}/I{sub D}). The relation between the pressure and the intensity ratio was investigated, and the thickness of the deposited boron film was predicted. Also, the dilution ratio H/(H + D) of the boron film was analyzed and compared with the one predicted from an optical analysis of the emission spectrum.

  16. Ion implantation of boron in germanium

    Energy Technology Data Exchange (ETDEWEB)

    Jones, K.S.

    1985-05-01

    Ion implantation of /sup 11/B/sup +/ into room temperature Ge samples leads to a p-type layer prior to any post implant annealing steps. Variable temperature Hall measurements and deep level transient spectroscopy experiments indicate that room temperature implantation of /sup 11/B/sup +/ into Ge results in 100% of the boron ions being electrically active as shallow acceptor, over the entire dose range (5 x 10/sup 11//cm/sup 2/ to 1 x 10/sup 14//cm/sup 2/) and energy range (25 keV to 100 keV) investigated, without any post implant annealing. The concentration of damage related acceptor centers is only 10% of the boron related, shallow acceptor center concentration for low energy implants (25 keV), but becomes dominant at high energies (100 keV) and low doses (<1 x 10/sup 12//cm/sup 2/). Three damage related hole traps are produced by ion implantation of /sup 11/B/sup +/. Two of these hole traps have also been observed in ..gamma..-irradiated Ge and may be oxygen-vacancy related defects, while the third trap may be divacancy related. All three traps anneal out at low temperatures (<300/sup 0/C). Boron, from room temperature implantation of BF/sub 2//sup +/ into Ge, is not substitutionally active prior to a post implant annealing step of 250/sup 0/C for 30 minutes. After annealing additional shallow acceptors are observed in BF/sub 2//sup +/ implanted samples which may be due to fluorine or flourine related complexes which are electrically active.

  17. Effect of acoustic, deformation on radiation-induced luminescence of pyrolytic boron nitride

    CERN Document Server

    Kardashev, B K; Plaksin, O A; Stepanov, V A; Stepanov, P A; Chernov, V M

    2001-01-01

    The effect of the ultrasound oscillations with the frequency of approximately 100 kHz on the radiation-induced luminescence on the pyrolytic boron nitride, originating by the protons irradiation (the energy of 8 MeV, the flux of 1.6 x 10 sup 1 sup 2 p/cm s), is studied. The impact of the ultrasound oscillations manifests itself by high deformation amplitudes (approximately 10 sup - sup 4), when the nonlinear, amplitude-dependent ultrasound absorption is observed. The obtained data are explained by the change in the kinetics of recrystallization, induced by irradiation, whereby the disappearance (radiation annealing) of the small angle boundaries occurs

  18. 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

  19. Continued biological investigations of boron-rich oligomeric phosphate diesters (OPDs). Tumor-selective boron agents for BNCT

    International Nuclear Information System (INIS)

    Clinical success of Boron Neutron Capture Therapy will rely on the selective intracellular delivery of high concentrations of boron-10 to tumor tissue. In order for a boron agent to facilitate clinical success, the simultaneous needs of obtaining a high tumor dose, high tumor selectivity, and low systemic toxicity must be realized. Boron-rich oligomeric phosphate diesters (OPDs) are a class of highly water-soluble compounds containing up to 40% boron by weight. Previous work in our groups demonstrated that once placed in the cytoplasm of tumor cells, OPDs quickly accumulate within the cell nucleus. The objective of the current study was to determine the biodistribution of seven different free OPDs in BALB/c mice bearing EMT6 tumors. Fructose solutions containing between 1.4 and 6.4 micrograms of boron per gram of tissue were interveinously injected in mice seven to ten days after tumor implantation. At intervals during the study, animals were euthanized and samples of tumor, blood, liver, kidney, brain and skin were collected and analyzed for boron content using ICP-AES. Tumor boron concentrations of between 5 and 29 ppm were achieved and maintained over the 72-hour time course of each experiment. Several OPDs demonstrated high tumor selectivity with one oligomer exhibiting a tumor to blood ratio of 35:1. The apparent toxicity of each oligomer was assessed through animal behavior during the experiment and necropsy of each animal upon sacrifice. (author)

  20. 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 ...

  1. Ballistic thermoelectric properties in boron nitride nanoribbons

    Science.gov (United States)

    Xie, Zhong-Xiang; Tang, Li-Ming; Pan, Chang-Ning; Chen, Qiao; Chen, Ke-Qiu

    2013-10-01

    Ballistic thermoelectric properties (TPs) in boron nitride nanoribbons (BNNRs) are studied using the nonequilibrium Green's function atomistic simulation of electron and phonon transport. A comparative analysis for TPs between BNNRs and graphene nanoribbons (GNRs) is made. Results show that the TPs of BNNRs are better than those of GNRs stemming from the higher power factor and smaller thermal conductance of BNNRs. With increasing the ribbon width, the maximum value of ZT (ZTmax) of BNNRs exhibits a transformation from the monotonic decrease to nonlinear increase. We also show that the lattice defect can enhance the ZTmax of these nanoribbons strongly depending on its positions and the edge shape.

  2. Low-dimensional boron nitride nanomaterials

    Directory of Open Access Journals (Sweden)

    Amir Pakdel

    2012-06-01

    Full Text Available In this review, a concise research history of low-dimensional boron nitride (BN nanomaterials followed by recent developments in their synthesis, morphology, properties, and applications are presented. Seventeen years after the initial synthesis of BN nanotubes, research on BN nanomaterials has developed far enough to establish them as one of the most promising inorganic nanosystems. In this regard, it is envisaged that the unique properties of low-dimensional BN systems, such as superb mechanical stiffness, high thermal conductivity, wide optical bandgap, strong ultraviolet emission, thermal stability and chemical inertness will play a key role in prospective developments.

  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. Boron nitride nanomaterials for thermal management applications.

    Science.gov (United States)

    Meziani, Mohammed J; Song, Wei-Li; Wang, Ping; Lu, Fushen; Hou, Zhiling; Anderson, Ankoma; Maimaiti, Halidan; Sun, Ya-Ping

    2015-05-18

    Hexagonal boron nitride nanosheets (BNNs) are analogous to their two-dimensional carbon counterparts in many materials properties, in particular, ultrahigh thermal conductivity, but also offer some unique attributes, including being electrically insulating, high thermal stability, chemical and oxidation resistance, low color, and high mechanical strength. Significant recent advances in the production of BNNs, understanding of their properties, and the development of polymeric nanocomposites with BNNs for thermally conductive yet electrically insulating materials and systems are highlighted herein. Major opportunities and challenges for further studies in this rapidly advancing field are also discussed. PMID:25652360

  6. Exploiting the enantioselectivity of Baeyer-Villiger monooxygenases via boron oxidation

    NARCIS (Netherlands)

    Brondani, Patricia B.; Dudek, Hanna; Reis, Joel S.; Fraaije, Marco W.; Andrade, Leandro H.

    2012-01-01

    The enantioselective carbon-boron bond oxidation of several chiral boron-containing compounds by Baeyer-Villiger monooxygenases was evaluated. PAMO and M446G PAMO conveniently oxidized 1-phenylethyl boronate into the corresponding 1-(phenyl)ethanol (ee = 82-91%). Cyclopropyl boronic esters were also

  7. 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.

  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. 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.

  10. 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.

  11. 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.

  12. Efficient boron nitride nanotube formation via combined laser-gas flow levitation

    Energy Technology Data Exchange (ETDEWEB)

    Whitney, R. Roy; Jordan, Kevin; Smith, Michael

    2014-03-18

    A process for producing boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula B.sub.xC.sub.yN.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.xC.sub.yN.sub.z.

  13. 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.

  14. 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).

  15. Efficient boron-carbon-nitrogen nanotube formation via combined laser-gas flow levitation

    Energy Technology Data Exchange (ETDEWEB)

    Whitney, R Roy; Jordan, Kevin; Smith, Michael W

    2015-03-24

    A process for producing boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula B.sub.xC.sub.yN.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.xC.sub.yN.sub.z.

  16. 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.

  17. Irradiation studies on carbon nanotube-reinforced boron carbide

    Energy Technology Data Exchange (ETDEWEB)

    Aitkaliyeva, Assel [Department of Materials Science and Engineering, Texas A and M University, College Station, TX 77843 (United States); McCarthy, Michael C.; Jeong, Hae-Kwon [Artie McFerrin Department of Chemical Engineering, Texas A and M University, College Station, TX 77843 (United States); Shao, Lin, E-mail: lshao@ne.tamu.edu [Department of Materials Science and Engineering, Texas A and M University, College Station, TX 77843 (United States); Department of Nuclear Engineering, Texas A and M University, College Station, TX 77843 (United States)

    2012-02-01

    Radiation response of carbon nanotube (CNT) reinforced boron carbide composite has been studied for its application as a structural component in nuclear engineering. The composite was bombarded by 140 keV He ions at room temperature to a fluence ranging from 1 Multiplication-Sign 10{sup 14} to 1 Multiplication-Sign 10{sup 17} cm{sup -2}. Two-dimensional Raman mapping shows inhomogeneous distribution of CNTs, and was used to select regions of interest for damage characterization. For CNTs, the intensities ratio of D-G bands (I{sub D}/I{sub G}) increased with fluence up to a certain value, and decreased at the fluence of 5 Multiplication-Sign 10{sup 16} cm{sup -2}. This fluence also corresponds to a trend break in the plot of FWHM (full width at half maximum) of G band vs. I{sub D}/I{sub G} ratio, which indicates amorphization of CNTs. The study shows that Raman spectroscopy is a powerful tool to quantitatively characterize radiation damage in CNT-reinforced composites.

  18. Microdosimetry for Boron Neutron Capture Therapy

    International Nuclear Information System (INIS)

    The specific aims of the research proposal were as follows: (1) To design and construct small volume tissue equivalent proportional counters for the dosimetry and microdosimetry of high intensity thermal and epithermal neutron beams used in BNCT, and of modified fast neutron beams designed for boron neutron capture enhanced fast neutron therapy (BNCEFNT). (2) To develop analytical methods for estimating the biological effectiveness of the absorbed dose in BNCT and BNCEFNT based on the measured microdosimetric spectra. (3) To develop an analytical framework for comparing the biological effectiveness of different epithermal neutron beams used in BNCT and BNCEFNT, based on correlated sets of measured microdosimetric spectra and radiobiological data. Specific aims (1) and (2) were achieved in their entirety and are comprehensively documented in Jay Burmeister's Ph.D. dissertation entitled ''Specification of physical and biologically effective absorbed dose in radiation therapies utilizing the boron neutron capture reaction'' (Wayne State University, 1999). Specific aim (3) proved difficult to accomplish because of a lack of sufficient radiobiological data

  19. 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.

  20. Thermal properties of boron and borides

    International Nuclear Information System (INIS)

    The influence of point defects on the thermal conductivity of polycrystalline β-B has been measured from 1 to 1000 K. Above 300 K, samples containing 2 at. % Hf and Zr have thermal conductivities close to that of amorphous boron, indicating very strong phonon scattering. A thermal conductivity of equal magnitude has also been measured near and below room temperature for nearly stoichiometric single crystals of the theoretical composition YB68. On the basis of a comparison with earlier measurements to temperatures as low as 0.1 K, it is concluded that the thermal conductivity of crystalline YB68 is indeed very similar, if not identical, to that expected for amorphous boron over the entire temperature range of measurement (0.1--300 K). Measurements of the specific heat of nearly stoichiometric YB68 between 1.5 and 30 K also reveal a linear-specific-heat anomaly of the same magnitude as is characteristic for amorphous solids, in fair agreement with earlier measurements by Bilir et al. It is concluded that the lattice vibrations of crystalline YB68 are glasslike

  1. 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.

  2. Determination of boron spectrophotometry in thorium sulfate

    International Nuclear Information System (INIS)

    A procedure for the determination of microquantities of boron in nuclear grade thorium sulfate is described. The method is based on the extraction of BF-4 ion associated to monomethylthionine (MMT) in 1,2 - dichloroethane. The extraction of the colored BF-4-MMT complex does not allow the presence of sulfuric and phosphoric acids; other anions interfere seriously. This fact makes the dissolution of the thorium sulfate impracticable, since it is insoluble in both acids. On the other hand, the quantitative separation of thorium is mandatory, to avoid the precipitation of ThF4. To overcome this difficulty, the thorium sulfate is dissolved using a strong cationic ion exchanger, Th4+ being totally retained into the resin. Boron is then analysed in the effluent. The procedure allows the determination of 0.2 to 10.0 microgramas of B, with a maximum error of 10%. Thorium sulfate samples with contents of 0.2 to 2.0μg B/gTh have being analysed

  3. Arsamas-16

    International Nuclear Information System (INIS)

    Arsamas - 16 is the Russian counterpart to Los Alamos. It is the place where the Soviets have developed their atomic bomb and where Andrej Sacharov has been working on the hydrogen bomb. Since 1946, the Soviet gevernment has been sending the best of the best of the country's scientists and engineers to work at this top secret research center and join their forces in the nuclear arms race with the U.S.A. The author of the book has been among the first journalists ever to meet the leading heads (one woman among them) of the institute for an interview. His report offers insight into the life and personality of the scientists as well as the current situation of the institute, telling about the motivation and sense of responsibility of individual interview partners or the mental background and conception of themselves as an outstanding group of nuclear experts, or their view of the future with regard to specific topics such as the growing danger of nuclear accidents, the problems encountered in disarmament measures, or the exodus of experts and resulting problems. (orig.)

  4. 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.

  5. 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.

  6. Physical properties of CVD boron-doped multiwalled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Kartick C. [Molecular Sciences Institute and School of Chemistry, University of the Witwatersrand, P.O. Wits, 2050 Johannesburg (South Africa); DST/NRF Centre of Excellence in Strong Materials, P.O. Wits, 2050 Johannesburg (South Africa); Strydom, Andre M. [Department of Physics, University of Johannesburg, PO Box 524, Auckland Park 2006 (South Africa)], E-mail: amstrydom@uj.ac.za; Erasmus, Rudolph M.; Keartland, Jonathan M. [DST/NRF Centre of Excellence in Strong Materials, P.O. Wits, 2050 Johannesburg (South Africa); School of Physics, University of the Witwatersrand, P.O. Wits, 2050 Johannesburg (South Africa); Coville, Neil J. [Molecular Sciences Institute and School of Chemistry, University of the Witwatersrand, P.O. Wits, 2050 Johannesburg (South Africa); DST/NRF Centre of Excellence in Strong Materials, P.O. Wits, 2050 Johannesburg (South Africa)], E-mail: Neil.Coville@wits.ac.za

    2008-10-15

    The effects of boron doping and electron correlation on the transport properties of CVD boron-doped multiwalled carbon nanotubes are reported. The boron-doped multiwalled carbon nanotubes were characterized by TEM as well as Raman spectroscopy using different laser excitations (viz. 488, 514.5 and 647 nm). The intensity of the D-band laser excitation line increased after the boron incorporation into the carbon nanotubes. The G-band width increased on increasing the boron concentration, indicating the decrease of graphitization with increasing boron concentration. Electrical conductivity of the undoped and boron-doped carbon nanotubes reveal a 3-dimensional variable-range-hopping conductivity over a wide range of temperature, viz. from room temperature down to 2 K. The electrical conductivity is not found to be changed significantly by the present levels of B-doping. Electron Paramagnetic Resonance (EPR) results for the highest B-doped samples showed similarities with previously reported EPR literature measurements, but the low concentration sample gives a very broad ESR resonance line.

  7. 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.

  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. Nuclear characterizations and applications of boron-containing materials

    International Nuclear Information System (INIS)

    Materials either doped with traces of boron or containing this element as a matrix component have important technological and research applications. For most applications in technology, semiconductor doping, chemical vapor deposition of glass films, and optical waveguide fiber manufacture, boron levels or distribution must be controlled precisely. Thus, methods for quantitation of boron are needed, and its analytical chemistry still receives considerable study. Several nondestructive nuclear methods are described in this paper that have unique capabilities for quantitative analyses of boron at the trace and macro levels. Excellent high-sensitivity determinations are based on alpha track counting. For micro- and macroanalyses, the nuclear track technique using the 10B(n,α)7 Li reaction has been applied to map qualitatively the distribution of boron in borosilicate glass and in optical waveguide glass and fibers. Boron in the 1.59 to 7.75% range is determinable in silicate glasses. Similar information has also been obtained by prompt gamma neutron activation. Neuron depth profiling of boron in glass has been performed also. Results for several of these methods are reported

  12. Boron doping of graphene-pushing the limit.

    Science.gov (United States)

    Chaban, Vitaly V; Prezhdo, Oleg V

    2016-08-25

    Boron-doped derivatives of graphene have been intensely investigated because of their electronic and catalytic properties. The maximum experimentally observed concentration of boron atoms in graphite was 2.35% at 2350 K. By employing quantum chemistry coupled with molecular dynamics, we identified the theoretical doping limit for single-layer graphene at different temperatures, demonstrating that it is possible to achieve much higher boron doping concentrations. According to the calculations, 33.3 mol% of boron does not significantly undermine thermal stability, whereas 50 mol% of boron results in critical backbone deformations, which occur when three or more boron atoms enter the same six-member ring. Even though boron is less electro-negative than carbon, it tends to act as an electron acceptor in the vicinity of C-B bonds. The dipole moment of B-doped graphene depends strongly on the distribution of dopant atoms within the sheet. Compared with N-doped graphene, the dopant-dopant bonds are less destructive in the present system. The reported results motivate efforts to synthesize highly B-doped graphene for semiconductor and catalytic applications. The theoretical predictions can be validated through direct chemical synthesis. PMID:27533648

  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. 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.

  15. 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.

  16. 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

  17. 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

  18. Photometric and emission-spectrometric determination of boron in steels

    International Nuclear Information System (INIS)

    A method for the photometric determination of boron in unalloyed and alloyed steels is described, in which Curcumine is used as reagent. A separation of boron is not necessary. Limit of detection: 0.0003% B. The decomposition of boron nitride in the steel is achieved by heating the whole sample in fuming sulphuric acid/phosphoric acid. For the emission spectrometric investigation of solid steel samples and for the spectrochemical analysis of solutions with plasma excitation working parameters are given and possibilities of interferences are demonstrated. (orig.)

  19. Photometric and emission-spectrometric determination of boron in steels

    Energy Technology Data Exchange (ETDEWEB)

    Thierig, D.

    1982-01-01

    A method for the photometric determination of boron in unalloyed and alloyed steels is described, in which Curcumine is used as reagent. A separation of boron is not necessary. Limit of detection: 0.0003% B. The decomposition of boron nitride in the steel is achieved by heating the whole sample in fuming sulphuric acid/phosphoric acid. For the emission spectrometric investigation of solid steel samples and for the spectrochemical analysis of solutions with plasma excitation working parameters are given and possibilities of interferences are demonstrated.

  20. 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

  1. Process for producing wurtzitic or cubic boron nitride

    International Nuclear Information System (INIS)

    Disclosed is a process for producing wurtzitic or cubic boron nitride comprising the steps of: [A] preparing an intimate mixture of powdered boron oxide, a powdered metal selected from the group consisting of magnesium or aluminum, and a powdered metal azide; [B] igniting the mixture and bringing it to a temperature at which self-sustaining combustion occurs; [C] shocking the mixture at the end of the combustion thereof with a high pressure wave, thereby forming as a reaction product, wurtzitic or cubic boron nitride and occluded metal oxide; and, optionally [D] removing the occluded metal oxide from the reaction product. Also disclosed are reaction products made by the process described

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Photoelectron spectroscopy of boron aluminum hydride cluster anions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Gantefoer, Gerd; Bowen, Kit H., E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Li, Xiang [Center for Space Science and Technology, University of Maryland–Baltimore County, Baltimore, Maryland 21250 (United States); Kiran, Boggavarapu, E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry and Physics, McNeese State University, Lake Charles, Louisiana 70609 (United States); Kandalam, Anil K. [Department of Physics, West Chester University, West Chester, Pennsylvania 19383 (United States)

    2014-04-28

    Boron aluminum hydride clusters are studied through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations. Boron aluminum hydride cluster anions, B{sub x}Al{sub y}H{sub z}{sup −}, were generated in a pulsed arc cluster ionization source and identified by time-of-flight mass spectrometry. After mass selection, their photoelectron spectra were measured by a magnetic bottle-type electron energy analyzer. The resultant photoelectron spectra as well as calculations on a selected series of stoichiometries reveal significant geometrical changes upon substitution of aluminum atoms by boron atoms.

  8. 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.

  9. Nitrogen implantation effects on the chemical bonding and hardness of boron and boron nitride coatings

    Energy Technology Data Exchange (ETDEWEB)

    Anders, S; Felter, T; Hayes, J; Jankowski, A F; Patterson, R; Poker, D; Stamler, T

    1999-02-08

    Boron nitride (BN) coatings are deposited by the reactive sputtering of fully dense, boron (B) targets utilizing an argon-nitrogen (Ar-N{sub 2}) reactive gas mixture. Near-edge x-ray absorption fine structure analysis reveals features of chemical bonding in the B 1s photoabsorption spectrum. Hardness is measured at the film surface using nanoindentation. The BN coatings prepared at low, sputter gas pressure with substrate heating are found to have bonding characteristic of a defected hexagonal phase. The coatings are subjected to post-deposition nitrogen (N{sup +} and N{sub 2}{sup +}) implantation at different energies and current densities. The changes in film hardness attributed to the implantation can be correlated to changes observed in the B 1s NEXAFS spectra.

  10. Thermoelectric properties of β-boron and some boron compounds. Final report, August 1981-September 1984

    International Nuclear Information System (INIS)

    The thermoelectric properties, that is the Seebeck coefficient, and electrical and thermal conductivity, of doped β-boron have been measured from 300 to 1600 K. Most of the useful doping elements are transition metals and occupy interstitial sites in the lattice. The highest figure of merit so far achieved at 1000 K is ZT = 0.11 for P-type, polycrystalline, hot-pressed β-boron doped with copper. Higher values may be achievable once a better P-type dopant is found. Some experiments on B68Y, α-B12Al, B4C, and B6Si are described. Transition metals appear to be effective dopants for B68Y and B4C

  11. 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.

  12. 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).

  13. 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.

  14. Proceedings of workshop on 'boron chemistry and boron neutron capture therapy'

    International Nuclear Information System (INIS)

    This volume contains the proceedings of the 5th Workshop on 'the Boron Chemistry and Boron Neutron Capture Therapy' held on February 22 in 1993. The solubility of the boron carrier play an important role in the BNCT. New water-soluble p-boronophenylalanine derivatives are synthesized and their biological activities are investigated (Chap. 2 and 3). Some chemical problems on the BNCT were discussed, and the complex formation reaction of hydroxylboryl compounds were studied by the paper electrophoresis (Chap. 4). The results of the medical investigation on the BNCT using BSH compounds are shown in Chap. 5. Syntheses of o- and m-boronophenylalanine were done and their optical resolution was tried (Chap. 6). The complex formation reaction of p-boronophenylalanine (BPA) with L-DOPA and the oxidation reaction of the analogs are found in Chap. 7. The pka of BPA were determined by the isotachophoresis (Chap. 8). The chemical nature of dihydroxyboryl compounds were investigated by an infrared spectroscopy and electrophoresis (Chap. 9). New synthetic methods of BPA and p-boronophenylserine using ester of isocyanoacetic acid are described in Chap. 10. The induction of chromosomal aberations by neutron capture reaction are discussed from a point of the biological view. The a of the presented papers are indexed individually. (J.P.N.)

  15. 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.

  16. 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.

  17. 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. PMID:26501751

  18. Boron nitride: A new photonic material

    Energy Technology Data Exchange (ETDEWEB)

    Chubarov, M., E-mail: mihcu@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Pedersen, H., E-mail: henke@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Högberg, H., E-mail: hanho@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Filippov, S., E-mail: stafi@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Engelbrecht, J.A.A., E-mail: Japie.Engelbrecht@nmmu.ac.za [Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); O' Connel, J., E-mail: jacques.oconnell@gmail.com [Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Henry, A., E-mail: anne.henry@liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden)

    2014-04-15

    Rhombohedral boron nitride (r-BN) layers were grown on sapphire substrate in a hot-wall chemical vapor deposition reactor. Characterization of these layers is reported in details. X-ray diffraction (XRD) is used as a routine characterization tool to investigate the crystalline quality of the films and the identification of the phases is revealed using detailed pole figure measurements. Transmission electron microscopy reveals stacking of more than 40 atomic layers. Results from Fourier Transform InfraRed (FTIR) spectroscopy measurements are compared with XRD data showing that FTIR is not phase sensitive when various phases of sp{sup 2}-BN are investigated. XRD measurements show a significant improvement of the crystalline quality when adding silicon to the gas mixture during the growth; this is further confirmed by cathodoluminescence which shows a decrease of the defects related luminescence intensity.

  19. Hexagonal boron nitride and water interaction parameters

    Science.gov (United States)

    Wu, Yanbin; Wagner, Lucas K.; Aluru, Narayana R.

    2016-04-01

    The study of hexagonal boron nitride (hBN) in microfluidic and nanofluidic applications at the atomic level requires accurate force field parameters to describe the water-hBN interaction. In this work, we begin with benchmark quality first principles quantum Monte Carlo calculations on the interaction energy between water and hBN, which are used to validate random phase approximation (RPA) calculations. We then proceed with RPA to derive force field parameters, which are used to simulate water contact angle on bulk hBN, attaining a value within the experimental uncertainties. This paper demonstrates that end-to-end multiscale modeling, starting at detailed many-body quantum mechanics and ending with macroscopic properties, with the approximations controlled along the way, is feasible for these systems.

  20. Boron nitride: A new photonic material

    International Nuclear Information System (INIS)

    Rhombohedral boron nitride (r-BN) layers were grown on sapphire substrate in a hot-wall chemical vapor deposition reactor. Characterization of these layers is reported in details. X-ray diffraction (XRD) is used as a routine characterization tool to investigate the crystalline quality of the films and the identification of the phases is revealed using detailed pole figure measurements. Transmission electron microscopy reveals stacking of more than 40 atomic layers. Results from Fourier Transform InfraRed (FTIR) spectroscopy measurements are compared with XRD data showing that FTIR is not phase sensitive when various phases of sp2-BN are investigated. XRD measurements show a significant improvement of the crystalline quality when adding silicon to the gas mixture during the growth; this is further confirmed by cathodoluminescence which shows a decrease of the defects related luminescence intensity.

  1. 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.

  2. Excitons in boron nitride single layer

    Science.gov (United States)

    Galvani, Thomas; Paleari, Fulvio; Miranda, Henrique P. C.; Molina-Sánchez, Alejandro; Wirtz, Ludger; Latil, Sylvain; Amara, Hakim; Ducastelle, François

    2016-09-01

    Boron nitride single layer belongs to the family of two-dimensional materials whose optical properties are currently receiving considerable attention. Strong excitonic effects have already been observed in the bulk and still stronger effects are predicted for single layers. We present here a detailed study of these properties by combining ab initio calculations and a tight-binding Wannier analysis in both real and reciprocal space. Due to the simplicity of the band structure with single valence (π ) and conduction (π*) bands the tight-binding analysis becomes quasiquantitative with only two adjustable parameters and provides tools for a detailed analysis of the exciton properties. Strong deviations from the usual hydrogenic model are evidenced. The ground-state exciton is not a genuine Frenkel exciton, but a very localized tightly bound one. The other ones are similar to those found in transition-metal dichalcogenides and, although more localized, can be described within a Wannier-Mott scheme.

  3. Hexagonal boron nitride and water interaction parameters.

    Science.gov (United States)

    Wu, Yanbin; Wagner, Lucas K; Aluru, Narayana R

    2016-04-28

    The study of hexagonal boron nitride (hBN) in microfluidic and nanofluidic applications at the atomic level requires accurate force field parameters to describe the water-hBN interaction. In this work, we begin with benchmark quality first principles quantum Monte Carlo calculations on the interaction energy between water and hBN, which are used to validate random phase approximation (RPA) calculations. We then proceed with RPA to derive force field parameters, which are used to simulate water contact angle on bulk hBN, attaining a value within the experimental uncertainties. This paper demonstrates that end-to-end multiscale modeling, starting at detailed many-body quantum mechanics and ending with macroscopic properties, with the approximations controlled along the way, is feasible for these systems. PMID:27131542

  4. 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.

  5. 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...

  6. 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.

  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. Isotopic compositions of boron in sediments and their implications

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; Yingkai, X.

    of sediments are mostly closer to the boron isotopic composition of minerals. Such low delta sup(11)B values are attributed to the presence of borates, ulexite and other carbonate minerals in sediments of the salt lakes of Qaidam Basin....

  11. Spectrographic determination of traces of boron in steels

    International Nuclear Information System (INIS)

    A spectrographic method has been developed to determine quantitatively boron in steels in the 0.5 to 250 ppm concentration range. The samples are dissolved in acids and transformed into oxides, avoiding boron losses by the addition of mannitol. For the fluoride evolution of boron in the dc arc the following compounds have been considered: CuF2, LiF, NaF, and SrF2. CuF2, at a concentration of 10%, provides the highest line-to-background intensity ratio. An arc current of 5 amperes eliminates the interference from iron spectrum on the most sensitive boron line - B 2497.7 A. Variations in chromium and nickel contents have no effect on the analytical results. (author)

  12. 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.

  13. Boron removal from metallurgical grade silicon by oxidizing refining

    Institute of Scientific and Technical Information of China (English)

    WU Ji-jun; MA Wen-hui; YANG Bin; DAI Yong-nian; K. MORITA

    2009-01-01

    A purification process was developed to remove impurity element boron from the metallurgical grade silicon by the electric arc furnace refining. The thermodynamic equilibria calculation and experiment to remove boron in the oxidizing atmosphere were performed and analyzed. Boron is removed as the gaseous species BxOy and BxHzOy in O2 and H2O-O2 atmosphere respectively. The equilibrium pressure of BxHzOy is 105-1010 times that of BxOy. Boron is removed and its content in silicon is reduced from 18×10-6 to 2×10-6 in the Ar-H2O-O2 atmosphere in the electric arc furnace.

  14. 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...

  15. 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.

  16. 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...

  17. Electronic structure of boron-interstitial clusters in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Deak, Peter [Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki ut 8, Budapest, H-1111 (Hungary); Gali, Adam [Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki ut 8, Budapest, H-1111 (Hungary); Solyom, Andras [Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki ut 8, Budapest, H-1111 (Hungary); Buruzs, Adam [Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki ut 8, Budapest, H-1111 (Hungary); Frauenheim, Thomas [University of Paderborn, Theoretical Physics, Paderborn, D-33095 (Germany)

    2005-06-08

    Hybrid functional calculations within density functional theory are carried out to investigate the electronic structure of boron-interstitial clusters (BICs). A one-parameter hybrid functional is chosen is to give accurate results for the whole electronic structure (including the gap) and the elastic properties of crystalline silicon. It is shown that this approach provides dependable defect level positions in the gap. Investigation of the boron+vacancy and boron+self-interstitial centres gives a consistent description of the experimentally observed G10 and G28 centres. The electronic structure of BICs, which may affect the activation rate of boron implantation, are reported. The one-electron level positions of isolated B{sub n}I{sub m} defects are given.

  18. Analytical chemistry methods for boron carbide absorber material. [Standard

    Energy Technology Data Exchange (ETDEWEB)

    DELVIN WL

    1977-07-01

    This standard provides analytical chemistry methods for the analysis of boron carbide powder and pellets for the following: total C and B, B isotopic composition, soluble C and B, fluoride, chloride, metallic impurities, gas content, water, nitrogen, and oxygen. (DLC)

  19. 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.

  20. For boron neutron capture therapy,synthesizing boron-polymer compounds and testing in laboratory conditions

    International Nuclear Information System (INIS)

    The aim of this project is to establish a focus point at Turkish Atomic Energy Authority (TAEA) in the field of Boron Neutron Capture Therapy which is a binary radiotherapy method for brain tumours. Moreover in the scope of the project, a new alternative of 10B-carrier compounds will be synthesized, the neutron source will be determined and the infrastructure to start the clinical trials of BNCT in our country will be established. BNCT is a binary radiotherapy method and the successful of this method is depend on the synthesized boron compounds which have the selective targeting property with tumour cells and neutron optimization. The water-soluble polymer based boron compounds having biochemical and physiological properties will be synthesized and cell culture experiment will be done. In addition, after the neutron source is set up in our country, the infrastructure studies will be started in order to start the clinical trials of BNCT. In this project, there are three different groups as boron compounds, neutron physics and medical group. Neutron physics group is starting the calculations of neutron beam parameters using in BNCT application. But, medical group has no active studies yet. Boron compounds group has been carried out two different experimental studies. In the first experimental study, functional groups have been bound to boron containing polymers to enhance the selectively targeting property and characterized by various analysis methods. Later, cell culture experiment will be done. The first study has been carried out with Hacettepe University. Up to present, completed studies are listed as: -Maleic anhydride oligomer was synthesized and then 2-aminoethyl diphenyl borate (2-AEPB) and monomethoxy poly(ethylene glycol) (PEG) was bound to this oligomer, respectively. Thus, [MAH]n-g1-2-AEPB-g2-PEG was synthesized. -2-AEPB compound were bound to poly(acrylic acid) polymer at different three mole ratio.Then, the selected Poli(Ac)-g1-2-AEPB polymer was

  1. 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.

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

    International Nuclear Information System (INIS)

    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

  3. Lateral boron distribution in polycrystalline SiC source materials

    DEFF Research Database (Denmark)

    Linnarsson, M. K.; Kaiser, M.; Liljedahl, R.;

    2013-01-01

    . The materials are co-doped materials with nitrogen and boron to a concentration of 1x1018 cm-3 and 1x1019 cm-3, respectively. Depth profiles as well as ion images have been recorded. According to ocular inspection, the analyzed poly-SiC consists mainly of 4H-SiC and 6H-SiC grains. In these grains, the boron...

  4. Determination of boron in nuclear grade sodium metal

    International Nuclear Information System (INIS)

    Determination of boron in nuclear grade sodium metal as rosocyanin and rubrocurcumin complexes is described. Separation of sodium matrix was attempted by vacuum distillation of sodium, methyl borate distillation and ion exchange methods. The ion exchange method was found to be most suitable. Optimum conditions were standardised for the estimation of boron in nuclear grade sodium. In the 200 ppb range an RSD of 5 per cent was obtained. (author). 12 refs

  5. 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.

  6. Disorder and defects are not intrinsic to boron carbide

    OpenAIRE

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

    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, stoichio...

  7. Research of nanocomposite structure of boron nitride at proton radiation

    OpenAIRE

    Borodin, Yuri Viktorovich; Ermolaev, D. S.; Pak, V.; Zhang, K.

    2016-01-01

    Using roentgen diffraction and electron microscopy, the influence of nanosecond irradiation by ion beams of high energy on forming of self-organized nanoblocks in near surface's layers of boron nitride (BN) has been studied. It was shown that low temperature transitions from hexagonal to wrutz boron nitrides is associated with changes of shape and sizes of self-organized particles consisting the nanoblocks. We have calculated the parameters of nanoblocks using the meanings of interplane dista...

  8. Cubic boron nitride- a new material for ultracold neutron application

    International Nuclear Information System (INIS)

    For the first time, the Fermi potential of cubic boron nitride (cBN) was measured at the ultra cold neutron source at the TRIGA reactor, Mainz using the time of flight method (TOF). The investigated samples have a Fermi potential of about 300 neV. Because of its good dielectric characteristics, cubic boron nitride could be used as suitable coating for insulator in storage chambers of future EDM projects. This talk presents recent results and an outlook on further investigations.

  9. 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.

  10. Vertical transport in graphene-hexagonal boron nitride heterostructure devices

    OpenAIRE

    Samantha Bruzzone; Demetrio Logoteta; Gianluca Fiori; Giuseppe Iannaccone

    2015-01-01

    Research in graphene-based electronics is recently focusing on devices based on vertical heterostructures of two-dimensional materials. Here we use density functional theory and multiscale simulations to investigate the tunneling properties of single- and double-barrier structures with graphene and few-layer hexagonal boron nitride (h-BN) or hexagonal boron carbon nitride (h-BC2N). We find that tunneling through a single barrier exhibit a weak dependence on energy. We also show that in double...

  11. Does boron affect hormone levels of barley cultivars?

    OpenAIRE

    Muavviz Ayvaz; Mesut Koyuncu; Avni Guven; FAGERSTEDT, KURT V.

    2012-01-01

    Background: When mineral nutrients are present in excess or in inadequate amounts, their effects can be severe in plants and can be considered as abiotic stress. In this study, we report how hormonal levels in barley cultivars respond to the toxic effect of boron, an essential plant micronutrient. Material and methods: Two different barley (Hordeum vulgare) cultivars (Vamik Hoca and Efes 98) were used as a study material. Boron was applied in three different concentrations (0, 10, 20 ppm) ...

  12. Boron-oxygen polyanion in the crystal structure of tunellite

    Science.gov (United States)

    Clark, J.R.

    1963-01-01

    The crystal structure of tunellite, SrO??3B2O 3??4H2O, with infinite sheets of composition n[B6O9(OH)2]2-, has cations and water molecules in the spaces within the sheets. Adjacent sheets are held together by hydrogen bonding through the water molecules. The boron-oxygen polyanions provide the first example in hydrated borate crystals of one oxygen linked to three borons.

  13. Chemoradiotherapy of cancer using boronated monoclonal antibodies. Comprehensive progress report, April 1, 1982-October 31, 1984

    International Nuclear Information System (INIS)

    Research to develop boron neutron capture for radiotherapy applications is summarized. Work is reported in the following areas: (1) chemical and biochemical research with B12H11SH2-; (2) chemical and protein-binding studies with B12H11NCO2- and (CH3)3NB10H8NCO1-; (3) effects of neutron irradiation and capture on phytomitogen stimulated lymphocyte blastogenesis; (4) production and characterization of monoclonal antibodies directed against the murine B16 melanoma; (5) reactor description and determination of flux profile; (6) determination of neutron profile; (7) improvement of the neutron beam by the bismuth scatterer method; and (8) in vitro sensitivity of B16 melanoma cells to thermal neutrons and 10B(n,α) capture. 11 references

  14. 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 sp2 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.

  15. Spontaneous Boron-doping of Graphene at Room Temperature

    Science.gov (United States)

    Pan, Lida; Que, Yande; Du, Shixuan; Gao, Hongjun; Pantelides, Sokrates T.

    2015-03-01

    Doping graphene with boron or nitrogen is an effective way to modify its electronic properties. However, the reaction barrier for introducing these impurities is quite high, making the doping process difficult. In this work, we propose a low-energy reaction route derived from first-principles calculations and subsequently validated by experiments. The calculations show that, when graphene is placed on a ruthenium substrate and exposed to atomic boron, boron atoms can incorporate substitutionally into the graphene sheet with an energy barrier about 0.1 eV, displacing carbon atoms below the graphene sheet where they migrates away. This result suggests that spontaneous doping by boron can take place at room temperature. Following the prediction, we grew high-quality graphene on the Ru(0001) surface and then expose it to B2H6 which decomposes into atomic boron. XPS and STM results indicate that boron dopes graphene substantially without disturbing the graphene lattice, confirming the theoretical predictions. Doping by nitrogen and co-doping by B and N will also be discussed.

  16. Boron biodistribution after boronophenylalanine-fructose (BPA-F) infusion

    Energy Technology Data Exchange (ETDEWEB)

    Kallio, M.; Kulvik, M.; Laakso, J.; Ruokonen, I.; Vaehaetalo, J.; Faerkkilae, M. [University of Helsinki (Finland); Rasilainen, M.; Jaerviluoma, E. [Helsinki University Central Hospital, Pharmacy, Helsinki (Finland)

    2000-10-01

    In vivo dynamic tissue boron concentration measurements are not available for BNCT in clinical settings. Whole blood boron concentrations and converting factors are currently used in stead to estimate the boron concentrations in the target tissues and the ensuing radiation doses. We studied with ICP-AES the boron concentrations in blood after 2 hour intravenous infusions of BPA-F in 8 patients (290 mg/kg). As BPA-F is water soluble we calculated respective doses per lean body weight (LBW) (360 - 471 mg/kg) - the peak plasma concentrations and area under plasma boron concentration time curve correlated with the mg/LBW dose, but not with dose per skin surface area (mg/m{sup 2}). The mean boron concentrations in plasma, whole blood and red cells at the infusion were 32.1 {+-} 3.3, 23.3 {+-} 2.4 and 9.5 {+-} 2.8, respectively. LBW doses should be considered to ensure more homogenous dosing and BNCT irradiation. (author)

  17. 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.

  18. 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. PMID:26679972

  19. 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. PMID:27219700

  20. Adsorption of boron on a Mo(110) surface

    Energy Technology Data Exchange (ETDEWEB)

    Magkoev, Tamerlan T; Turiev, Anatolij M; Tsidaeva, Natal' ja I; Panteleev, Dmitrij G [Department of Physics, University of North Ossetia, Kesaev 121-83, Vladikavkaz 362020 (Russian Federation); Vladimirov, Georgij G; Rump, Gennadij A [Department of Physics, University of Saint Petersburg, Uljanovskaya 1-1, Saint Petersburg 198904 (Russian Federation)], E-mail: t_magkoev@mail.ru

    2008-12-03

    Adsorption of boron atoms in submonolayer to multilayer coverage on atomically clean Mo(110) surfaces has been studied by Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy (EELS) and work function measurements. According to Auger results there is a layer-by-layer growth mode of the film on the substrate held at room temperature. In the submonolayer region the work function gradually increases with boron coverage until a saturation value of 5.8 eV is achieved after completion of the first monoatomic layer. The B-Mo(110) adsorbate system formed on the substrate at room temperature is not stable, dominated by a strong tendency of the boron atoms to diffuse into the bulk of the crystal. The latter is manifested by dramatic Mo(110) surface plasmon mode transformation upon boron adsorption, presumably as a result of penetration of boron atoms into the topmost substrate layer even at T = 300 K. Slight annealing up to 450 K facilitates this trend, leading to total dissolution of deposited boron atoms in the bulk of the crystal under further annealing, restoring the initial state of the Mo(110) surface after achieving a temperature of approximately 2000 K.

  1. Adsorption of boron on a Mo(110) surface

    Science.gov (United States)

    Magkoev, Tamerlan T.; Turiev, Anatolij M.; Tsidaeva, Natal'ja I.; Panteleev, Dmitrij G.; Vladimirov, Georgij G.; Rump, Gennadij A.

    2008-12-01

    Adsorption of boron atoms in submonolayer to multilayer coverage on atomically clean Mo(110) surfaces has been studied by Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy (EELS) and work function measurements. According to Auger results there is a layer-by-layer growth mode of the film on the substrate held at room temperature. In the submonolayer region the work function gradually increases with boron coverage until a saturation value of 5.8 eV is achieved after completion of the first monoatomic layer. The B-Mo(110) adsorbate system formed on the substrate at room temperature is not stable, dominated by a strong tendency of the boron atoms to diffuse into the bulk of the crystal. The latter is manifested by dramatic Mo(110) surface plasmon mode transformation upon boron adsorption, presumably as a result of penetration of boron atoms into the topmost substrate layer even at T = 300 K. Slight annealing up to 450 K facilitates this trend, leading to total dissolution of deposited boron atoms in the bulk of the crystal under further annealing, restoring the initial state of the Mo(110) surface after achieving a temperature of approximately 2000 K.

  2. 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.

  3. High order boron transport scheme in TRAC-BF1

    International Nuclear Information System (INIS)

    In boiling water reactors (BWR), unlike pressurized water reactors (PWR) in which the reactivity control is accomplished through movement of the control rods and boron dilution, the importance of boron transport lies in maintaining the core integrity during ATWS-kind severe accidents in which under certain circumstances a boron injection is required. This is the reason for implementing boron transport models thermal-hydraulic codes as TRAC-BF1, RELAP5 and TRACE, bringing an improvement in the accuracy of the simulations. TRAC-BF1 code provides a best estimate analysis capability for the analysis of the full range of postulated accidents in boiling water reactors systems and related facilities. The boron transport model implemented in TRAC-BF1 code is based on a calculation according to a first order accurate upwind difference scheme. There is a need in reviewing and improving this model. Four numerical schemes that solve the boron transport model have been analyzed and compared with the analytical solution that provides the Burgers equation. The studied numerical schemes are: first order Upwind, second order Godunov, second-order modified Godunov adding physical diffusion term and a third-order QUICKEST using the ULTIMATE universal limiter (UL). The modified Godunov scheme has been implemented in TRAC-BF1 source code. The results using these new schemes are presented in this paper. (author)

  4. 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)

  5. 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.

  6. 16 CFR 1204.16 - Production testing.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Production testing. 1204.16 Section 1204.16... STANDARD FOR OMNIDIRECTIONAL CITIZENS BAND BASE STATION ANTENNAS Certification § 1204.16 Production testing... production testing. Each production test shall be conducted at a production interval short enough to...

  7. 16 CFR 1212.16 - Production testing.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Production testing. 1212.16 Section 1212.16... STANDARD FOR MULTI-PURPOSE LIGHTERS Certification Requirements § 1212.16 Production testing. (a) General... determine the types of tests for production testing. Each production test shall be conducted at a...

  8. 16 CFR 1210.16 - Production testing.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Production testing. 1210.16 Section 1210.16... STANDARD FOR CIGARETTE LIGHTERS Certification Requirements § 1210.16 Production testing. (a) General... production testing. Each production test shall be conducted at a production interval short enough to...

  9. 16 CFR 1025.16 - Service.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Service. 1025.16 Section 1025.16 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION GENERAL RULES OF PRACTICE FOR ADJUDICATIVE PROCEEDINGS Pleadings, Form, Execution, Service of Documents § 1025.16 Service. (a) Mandatory service. Every...

  10. Thermodynamic approach to boron nitride nanotube solubility and dispersion

    Science.gov (United States)

    Tiano, A. L.; Gibbons, L.; Tsui, M.; Applin, S. I.; Silva, R.; Park, C.; Fay, C. C.

    2016-02-01

    Inadequate dispersion of nanomaterials is a critical issue that significantly limits the potential properties of nanocomposites and when overcome, will enable further enhancement of material properties. The most common methods used to improve dispersion include surface functionalization, surfactants, polymer wrapping, and sonication. Although these approaches have proven effective, they often achieve dispersion by altering the surface or structure of the nanomaterial and ultimately, their intrinsic properties. Co-solvents are commonly utilized in the polymer, paint, and art conservation industries to selectively dissolve materials. These co-solvents are utilized based on thermodynamic interaction parameters and are chosen so that the original materials are not affected. The same concept was applied to enhance the dispersion of boron nitride nanotubes (BNNTs) to facilitate the fabrication of BNNT nanocomposites. Of the solvents tested, dimethylacetamide (DMAc) exhibited the most stable, uniform dispersion of BNNTs, followed by N,N-dimethylformamide (DMF), acetone, and N-methyl-2-pyrrolidone (NMP). Utilizing the known Hansen solubility parameters of these solvents in comparison to the BNNT dispersion state, a region of good solubility was proposed. This solubility region was used to identify co-solvent systems that led to improved BNNT dispersion in poor solvents such as toluene, hexane, and ethanol. Incorporating the data from the co-solvent studies further refined the proposed solubility region. From this region, the Hansen solubility parameters for BNNTs are thought to lie at the midpoint of the solubility sphere: 16.8, 10.7, and 9.0 MPa1/2 for δd, δp, and δh, respectively, with a calculated Hildebrand parameter of 21.8 MPa1/2.Inadequate dispersion of nanomaterials is a critical issue that significantly limits the potential properties of nanocomposites and when overcome, will enable further enhancement of material properties. The most common methods used to

  11. Fabrication and Radiocharacterization of Boron Carbide and Tungsten Incorporated Rubber Shields

    Directory of Open Access Journals (Sweden)

    Marzieh Salimi

    2013-10-01

    Full Text Available Radioactive ray safeguard is a physical impediment which is placed between radioactive source and the protected object in order to decrease the amount of rays' radiation in the protected area. Different materials such as lead, iron, graphite, water, poly ethylene, concrete, or rubber can be used for protection against nuclear radiations. In safeguard's common designing, two types of Gama and Neutron radiations are usually considered. The weakening amount of Gama radiations is proportional to the mass and atomic number of the safeguard's material. Covering Neutron source varies with regard to the source power and its application. However, what is always true is having the least dose with the least dimensions outside the safeguard. The dose of the safeguard's outside partition is resulted from quick, slow and thermal neutrons, and also from the source's Gammas and secondary Gammas. Neutrons use retarding and neutron-absorbing materials in order to reduce the dose. Due to the weak mechanical characteristics of the pure elastic composites, fillers are used to strengthen and improve their characteristics. Strengthening the elastic material is often defined through increasing the characteristics such as hardness, module, refraction energy, solidity, tear resistance, tensile solidity, lassitude resistance, abrasion resistance. In this paper, rubber shielding materials with boron carbide and tungsten as impurities have been fabricated. The optimum boron carbide contents (5% weight percent have been evaluated using the Monte Carlo code, MCNP. The gamma attenuation coefficients for different boron carbide and tungsten contents have been measured for a number of rubber shields with dimensions of 1×9×16cm3.

  12. Boron stress response and accumulation potential of the extremely tolerant species Puccinellia frigida.

    Science.gov (United States)

    Rámila, Consuelo D P; Contreras, Samuel A; Di Domenico, Camila; Molina-Montenegro, Marco A; Vega, Andrea; Handford, Michael; Bonilla, Carlos A; Pizarro, Gonzalo E

    2016-11-01

    Phytoremediation is a promising technology to tackle boron toxicity, which restricts agricultural activities in many arid and semi-arid areas. Puccinellia frigida is a perennial grass that was reported to hyperaccumulate boron in extremely boron-contaminated sites. To further investigate its potential for phytoremediation, we determined its response to boron stress under controlled conditions (hydroponic culture). Also, as a first step towards understanding the mechanisms underlying its extreme tolerance, we evaluated the presence and expression of genes related with boron tolerance. We found that P. frigida grew normally even at highly toxic boron concentrations in the medium (500mg/L), and within its tissues (>5000mg/kg DW). We postulate that the strategies conferring this extreme tolerance involve both restricting boron accumulation and an internal tolerance mechanism; this is consistent with the identification of putative genes involved in both mechanisms, including the expression of a possible boron efflux transporter. We also found that P. frigida hyperaccumulated boron over a wide range of boron concentrations. We propose that P. frigida could be used for boron phytoremediation strategies in places with different soil characteristics and boron concentrations. Further studies should pave the way for the development of clean and low-cost solutions to boron toxicity problems. PMID:27322905

  13. Effect of boron fertilization of apple trees (Malus domestica Borth. on yield and fruit quality

    Directory of Open Access Journals (Sweden)

    Paweł Wójcik

    2013-12-01

    Full Text Available Aim of this work was to examine effect of boron fertilization on yield of apple trees and fruit quality. The experiment was carried out during 1994-1996 in Dąbrowice Experimental Orchard belonging to Research Institute of Pomology and Floriculture in Skiemiewice, on Š a m p i o n cultivar, grafted on M26 rootstock. Trees were planted in the autumn of 1991 at the distance 4 x 2,5 m, on sandy-loam soil. Before starting and during carrying out the study there were not visual symptoms of boron deficiency. In the experiment applied boron fertilization to the soil at the dose 2 g B per tree or three times boron sprays before or after bloom at the dose 0,67 g B per tree. Apple trees without any boron fertilization were served as a control. Results of experiment showed that only boron sprays after bloom increased fruit set and yield. There were no significant differences between treatments in fruit maturity at harvest, fruit weight losses dunng storage, apple number infected by Penicillium, Monilina and Botrytis cinerea. Boron sprays after bloom increased firmness of apples after storage and decreased sensibility to bitter pit, internal breakdown and Gloeosporium-rot. All boron treatments increased boron concentration in apples in comparison with control ones. However, the highest increase of boron concentration in apples was observed when boron sprays were done after bloom and soil boron application. Only boron sprays applied after bloom increased calcium concentration in apples.

  14. 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.

  15. Endocytosis and degradation of BOR1, a boron transporter of Arabidopsis thaliana, regulated by boron availability

    OpenAIRE

    Takano, Junpei; Miwa, Kyoko; Yuan, Lixing; von Wirén, Nicolaus; Fujiwara, Toru

    2005-01-01

    Boron (B) is essential for plants but toxic when present in excess. Arabidopsis thaliana BOR1 is a B exporter for xylem loading and is essential for efficient B translocation from roots to shoots under B limitation. B translocation to shoots was enhanced under B limitation in WT but not in bor1-1 mutant plants. The enhanced translocation was suppressed upon resupply of high levels of B within several hours. Unlike a number of transporters for essential mineral nutrients, BOR1 mRNA accumulatio...

  16. Photoluminescence properties of boron doped InSe single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ertap, H., E-mail: huseyinertap@kafkas.edu.tr [Kafkas University, Faculty of Arts and Sciences, Department of Physics, 36100 Kars (Turkey); Bacıoğlu, A. [Hacattepe University, Department of Physics Engineering, 06800, Beytepe, Ankara (Turkey); Karabulut, M. [Kafkas University, Faculty of Arts and Sciences, Department of Physics, 36100 Kars (Turkey)

    2015-11-15

    Undoped and boron doped InSe single crystals were grown by Bridgman–Stockbarger technique. The PL properties of undoped, 0.1% and 0.5% boron doped InSe single crystals have been investigated at different temperatures. PL measurements revealed four emission bands labeled as A, B, C and D in all the single crystals studied. These emission bands were associated with the radiative recombination of direct free excitons (n=1), impurity-band transitions, donor–acceptor recombinations and structural defect related band (impurity atoms, defects, defect complexes, impurity-vacancy complex etc.), respectively. The direct free exciton (A) bands of undoped, 0.1% and 0.5% boron doped InSe single crystals were observed at 1.337 eV, 1.335 eV and 1.330 eV in the PL spectra measured at 12 K, respectively. Energy positions and PL intensities of the emission bands varied with boron addition. The FWHM of direct free exciton band increases while the FWHM of the D emission band decreases with boron doping. Band gap energies of undoped and boron doped InSe single crystals were calculated from the PL measurements. It was found that the band gap energies of InSe single crystals decreased with increasing boron content. - Highlights: • PL spectra of InSe crystals have been studied as a function of temperature. • Four emission bands were observed in the PL spectra at low temperatures. • PL intensity and position of free exciton band vary with doping and temperature. • Temperature dependences of the bands observed in the PL spectra were analyzed.

  17. Synthesis of conjugates of polyhedral boron compounds with tumor-seeking molecules for neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Bregadze, V., E-mail: bre@ineos.ac.ru [A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov Str. 28, Moscow 119991 (Russian Federation); Semioshkin, A.; Sivaev, I. [A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov Str. 28, Moscow 119991 (Russian Federation)

    2011-12-15

    Recent achievements in design and synthesis of boronated acids, amino acids, glycerols as well as conjugates of polyhedral boron hydrides (ortho-carborane, closo-dodecaborate and cobalt bis(dicarbollide)) with natural porphyrins, carbohydrates and nucleosides are described.

  18. 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.

  19. Hydrogen adsorption on boron doped graphene: an {\\it ab initio} study

    OpenAIRE

    Miwa, R. H.; Martins, T B; Fazzio, A.

    2007-01-01

    The electronic and structural properties of (i) boron doped graphene sheets, and (ii) the chemisorption processes of hydrogen adatoms on the boron doped graphene sheets have been examined by {\\it ab initio} total energy calculations.

  20. Novel Boron Subphthalocyanines for Organic Electronic Devices

    Science.gov (United States)

    Castrucci, Jeffrey Stephen

    Boron subphthalocyanines (BsubPcs) are a class of organic semiconductor materials that have been identified as having desirable properties for use in photovoltaic devices due to their strong light absorbance and the flexibility to develop tunable chemical derivatives. In particular, a lack of variety in available electron acceptors is an area where BsubPc derivatives can be readily substituted into existing photovoltaic device architectures. There are, however, no metrics to facilitate the rapid screening of different BsubPc derivatives. In this thesis, admittance spectroscopy is used to measure charge carrier mobility of these BsubPc derivatives, and photovoltaic cells are fabricated to evaluate these derivatives' performance in devices. We find that the measured electron carrier mobilities in thin films of BsubPc correlate with the single crystal structural parameters determined by X-ray diffraction. We also find that for BsubPcs, electron mobility measured by admittance spectroscopy is insufficient to predict photovoltaic performance when BsubPcs are used as an electron accepting layer in a device. BsubPc derivatives, however, are discovered as a new class of versatile molecules that can be designed and synthesized for use in photovoltaic devices to harvest singlet fission derived triplet excitons and consequently boost photovoltaic device photocurrent. This thesis also reports vacuum system design and construction to address experimental challenges arising from dealing with low solubility, high molar mass materials and limited amounts of high purity material.

  1. Global boron cycle in the Anthropocene

    Science.gov (United States)

    Schlesinger, William H.; Vengosh, Avner

    2016-02-01

    This paper presents a revised and updated synthesis of the biogeochemical cycle of boron at the Earth's surface, where the largest fluxes are associated with the injection of sea-salt aerosols to the atmosphere (1.44 Tg B/yr), production and combustion of fossil fuels (1.2 Tg B/yr), atmospheric deposition (3.48 Tg B/yr), the mining of B ores (1.1 Tg B/yr), and the transport of dissolved and suspended matter in rivers (0.80 Tg B/yr). The new estimates show that anthropogenic mobilization of B from the continental crust exceeds the naturally occurring processes, resulting in substantial fluxes to the ocean and the hydrosphere. The anthropogenic component contributes 81% of the flux in rivers. The mean residence time for B in seawater supports the use of δ11B in marine carbonates as an index of changes in the pH of seawater over time periods of > 1 Ma.

  2. Boron thermal/epithermal neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Fairchild, R.G.

    1982-01-01

    The development of various particle beams for radiotherapy represents an attempt to improve dose distribution, and to provide high LET radiations which are less sensitive to ambient physical and radiobiological factors such as oxygen tension, cell cycle, and dose rate. In general, a compromise is necessary as effective RBE is reduced in order to spread the dose distribution over the anticipated tumor volume. The approach of delivering stable non-toxic isotopes to tumor, and then activating these atoms subsequently via an external radiation beam has mator advantages; problems associated with high uptake of these isotopes in competing cell pools are obviated, and the general tumor volume can be included in the treatment field of the activating beam. As long as the normal tissues supporting tumor show a low uptake of the isotope to be activated, and as long as the range of the reaction products is short, dose will be restricted to tumor, with a consequent high therapeutic ratio. Neutron Capture Therapy (NCT) is generally carried out by activating boron-10 with low energy neutrons. The range of the high LET, low OER particles from the /sup 10/B(n, ..cap alpha..)/sup 7/Li reaction is approx. 10..mu.., or one cell diameter, a situation that is optimal for cell killing. Significant advantages may be gained by using the NCT procedure in conjunction with improved tissue penetration provided with epithermal or filtered beams, and new compounds showing physiological binding to tumor.

  3. Electrochemical synthesis on boron-doped diamond

    International Nuclear Information System (INIS)

    Boron-doped diamond (BDD) is a novel and innovative electrode material. In protic media and particular aqueous electrolytes BDD exhibits a large over potential for the evolution of molecular hydrogen and oxygen. The large chemical window allows a variety of electrochemical conversions to be conducted. The anodic process treatment generates oxyl species directly which are known to be extremely reactive. Usually, the electrochemical mineralization of the organic components in the electrolyte occurs. However, with control of the reactivity of these intermediates the use in electroorganic synthesis can be realized. Until today mostly anodic conversions have been studied at BDD. Since hydroxyl radicals can be efficiently formed and exhibit an enormous oxidative power they are exploited for the electroorganic synthesis. In general, two strategies can be applied to circumvent electrochemical incineration: First, the substrate serves as solvent and partial conversion exploits statistics to gain selectivity for the desired product. This particular approach is useful when the excess of substrate can subsequently be evaporated, and is readily available and inexpensive. The second strategy uses fluorinated alcohols as additives which enlarge the chemical window. The specific role of these fluorinated solvents can be attributed to the stabilization of hydroxyl or methoxyl radicals by supramolecular taming of these intermediates. Moreover, these additives paved the way to the first anodic phenol–arene cross-coupling reaction.

  4. 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.

  5. Plasma immersion ion implantation of boron for ribbon silicon solar cells

    Directory of Open Access Journals (Sweden)

    Derbouz K.

    2013-09-01

    Full Text Available In this work, we report for the first time on the solar cell fabrication on n-type silicon RST (for Ribbon on Sacrificial Template using plasma immersion ion implantation. The experiments were also carried out on FZ silicon as a reference. Boron was implanted at energies from 10 to 15 kV and doses from 1015 to 1016 cm-2, then activated by a thermal annealing in a conventional furnace at 900 and 950 °C for 30 min. The n+ region acting as a back surface field was achieved by phosphorus spin-coating. The frontside boron emitter was passivated either by applying a 10 nm deposited SiOX plasma-enhanced chemical vapor deposition (PECVD or with a 10 nm grown thermal oxide. The anti-reflection coating layer formed a 60 nm thick SiNX layer. We show that energies less than 15 kV and doses around 5 × 1015 cm-2 are appropriate to achieve open circuit voltage higher than 590 mV and efficiency around 16.7% on FZ-Si. The photovoltaic performances on ribbon silicon are so far limited by the bulk quality of the material and by the quality of the junction through the presence of silicon carbide precipitates at the surface. Nevertheless, we demonstrate that plasma immersion ion implantation is very promising for solar cell fabrication on ultrathin silicon wafers such as ribbons.

  6. Plasma immersion ion implantation of boron for ribbon silicon solar cells

    Science.gov (United States)

    Derbouz, K.; Michel, T.; De Moro, F.; Spiegel, Y.; Torregrosa, F.; Belouet, C.; Slaoui, A.

    2013-09-01

    In this work, we report for the first time on the solar cell fabrication on n-type silicon RST (for Ribbon on Sacrificial Template) using plasma immersion ion implantation. The experiments were also carried out on FZ silicon as a reference. Boron was implanted at energies from 10 to 15 kV and doses from 1015 to 1016 cm-2, then activated by a thermal annealing in a conventional furnace at 900 and 950 °C for 30 min. The n+ region acting as a back surface field was achieved by phosphorus spin-coating. The frontside boron emitter was passivated either by applying a 10 nm deposited SiOX plasma-enhanced chemical vapor deposition (PECVD) or with a 10 nm grown thermal oxide. The anti-reflection coating layer formed a 60 nm thick SiNX layer. We show that energies less than 15 kV and doses around 5 × 1015 cm-2 are appropriate to achieve open circuit voltage higher than 590 mV and efficiency around 16.7% on FZ-Si. The photovoltaic performances on ribbon silicon are so far limited by the bulk quality of the material and by the quality of the junction through the presence of silicon carbide precipitates at the surface. Nevertheless, we demonstrate that plasma immersion ion implantation is very promising for solar cell fabrication on ultrathin silicon wafers such as ribbons.

  7. Synthesis and in Vitro Studies of a Series of Carborane-Containing Boron Dipyrromethenes (BODIPYs).

    Science.gov (United States)

    Xuan, Sunting; Zhao, Ning; Zhou, Zehua; Fronczek, Frank R; Vicente, M Graça H

    2016-03-10

    A series of seven BODIPYs functionalized with ortho-carborane groups at the 8(meso) or 3/5(α) position were synthesized and characterized by NMR, HRMS, HPLC, and in the cases of 2b and 5b, by X-ray analysis. The BODIPYs exhibited low dark toxicity and phototoxicity toward human glioma T98G cells, and their cellular uptake varied significantly, with 5b accumulating the most and 7 the least. All BODIPYs localized mainly within the cell ER. The BODIPYs showed higher permeabilities than lucifer yellow across human hCMEC/D3 brain endothelial cell monolayers as the BBB model. Among this series, 1b showed the highest BBB permeability (Pe = 16.4 × 10(-5) cm/s), probably as a result of its lower MW (366 Da) and favorable hydrophobicity (log P = 1.5). The combination of low cytotoxicity, amphiphilicity, high boron content, high cellular uptake, and moderate BBB permeability renders these compounds promising boron delivery agents for the BNCT of brain tumors. PMID:26849474

  8. 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.

  9. Lipase-catalyzed highly enantioselective kinetic resolution of boron-containing chiral alcohols.

    Science.gov (United States)

    Andrade, Leandro H; Barcellos, Thiago

    2009-07-16

    The first application of enzymes as catalysts to obtain optically pure boron compounds is described. The kinetic resolution of boron-containing chiral alcohols via enantioselective transesterification catalyzed by lipases was studied. Aromatic, allylic, and aliphatic secondary alcohols containing a boronate ester or boronic acid group were resolved by lipase from Candida antartica (CALB), and excellent E values (E > 200) and high enantiomeric excesses (up to >99%) of both remaining substrates and acetylated product were obtained.

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

    Science.gov (United States)

    Chen, Zhiyuan; Morita, Kazuki

    2016-05-01

    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 <1 ppmw within 6 hours, meeting the purity requirement of solar-grade silicon. Nickel was tested in place of iron but showed no catalytic effect on boron removal. The result confirmed the catalytic role of iron in boron removal from molten silicon in ammonia. Possible mechanisms of catalysis, influence from iron concentration, and temperature effect on the catalytic reaction were explored. An apparent activation energy of 329 ± 129 kJ mol-1 was calculated from experimental data.

  11. 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.

  12. 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.

  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. PMID:27669055

  14. 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. PMID:26777140

  15. Microstructure of a high boron 9-12% chromium steel

    Energy Technology Data Exchange (ETDEWEB)

    Andren, H.O. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Applied Physics

    2008-07-01

    Additions of small amounts of boron (10-100 ppm) to 9-12% chromium steels are often made since they have been found to be beneficial for the creep strength up to and above 600 C. The effect of boron is to restrict the coarsening of M{sub 23}C{sub 6} precipitates during service. It was found that increasing the boron content from 9 to 40 ppm gave a decrease in coarsening constant at 600 C by a factor of 2. The present understanding of boron solution, non-equilibrium grain boundary segregation, incorporation into M{sub 23}C{sub 6}, and diffusion is reviewed in the paper. A very high boron addition (300 ppm) was made in the trial TAF steel already in the 1950'ies. The microstructure of a similar trial steel, FT3B, has been studied detail. In this steel large Mo, Cr, Fe and V containing metal borides are formed rather than the expected BN, with the crystal structure M{sub 2}B{sub 2}. Nitrogen is therefore still available for the formation of VN. Due to tempering at a low temperature (690 C) to a high strength (830 MPa), this steel contained a dense distribution of very small VN precipitates, 5-15 nm in size. A similar VN distribution is probably the cause of the still unsurpassed creep strength of the TAF steel. (orig.)

  16. 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.

  17. Synthesis of Boron Nitride Nanotubes for Engineering Applications

    Science.gov (United States)

    Hurst, Janet; Hull, David; Gorican, Dan

    2005-01-01

    Boron Nitride nanotubes (BNNT) are of interest to the scientific and technical communities for many of the same reasons that carbon nanotubes (CNT) have attracted large amounts of attention. Both materials have potentially unique and significant properties which may have important structural and electronic applications in the future. However of even more interest than their similarities may be the differences between carbon and boron nanotubes. Whilt boron nitride nanotubes possess a very high modulus similaar to CNT, they are also more chemically and thermally inert. Additionally BNNT possess more uniform electronic properties, having a uniform band gap of approximately 5.5 eV while CNT vary from semi-conductin to conductor behavior. Boron Nitride nanotubes have been synthesized by a variety of methods such as chemical vapor deposition, arc discharge and reactive milling. Consistently producing a reliable product has proven difficult. Progress in synthesis of 1-2 gram sized batches of Boron Nitride nanotubes will be discussed as well as potential uses for this unique material.

  18. New Ground-State Crystal Structure of Elemental Boron.

    Science.gov (United States)

    An, Qi; Reddy, K Madhav; Xie, Kelvin Y; Hemker, Kevin J; Goddard, William A

    2016-08-19

    Elemental boron exhibits many polymorphs in nature based mostly on an icosahedral shell motif, involving stabilization of 13 strong multicenter intraicosahedral bonds. It is commonly accepted that the most thermodynamic stable structure of elemental boron at atmospheric pressure is the β rhombohedral boron (β-B). Surprisingly, using high-resolution transmission electron microscopy, we found that pure boron powder contains grains of two different types, the previously identified β-B containing a number of randomly spaced twins and what appears to be a fully transformed twinlike structure. This fully transformed structure, denoted here as τ-B, is based on the Cmcm orthorhombic space group. Quantum mechanics predicts that the newly identified τ-B structure is 13.8  meV/B more stable than β-B. The τ-B structure allows 6% more charge transfer from B_{57} units to nearby B_{12} units, making the net charge 6% closer to the ideal expected from Wade's rules. Thus, we predict the τ-B structure to be the ground state structure for elemental boron at atmospheric pressure. PMID:27588864

  19. 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.

  20. 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.

  1. Spectrophotometric determination of boric acid in boron powder with curcumin

    International Nuclear Information System (INIS)

    A rapid and accurate method was needed to determine trace amounts of boric acid for quality control and specification testing of elemental boron. The reaction between boric acid and curcumin occurs at a measurable rate only when the curcumin molecule is protonated. Protonation takes place at the carbonyl groups in the presence of a strong acid and occurs completely and rapidly when sulfuric acid is added to a solution of curcumin in acetic acid. Spectrophotometric measurements were made. The extraction of boric acid from boron powder was found to be complete within 2h when either water or the diol solution was used. Whatman No. 40 cr 42 filter paper was used to obtain diol samples free of boron particles. The extraction efficiency of 2-ethyl-1,3-hexanediol was evaluated by adding 1 ml of 500 ppM aqueous boric acid and 1 drop of 10% NaOH to accurately weighed samples of boron powder. The water then was evaporated at room temperature and the samples were extracted with diol solution. The data obtained are included. The extraction efficiency also was evaluated by determining the boric acid content of boron which had been recovered from a previous extraction and boric acid determination. The determination of boric acid using curcumin is unaffected by the presence of other compounds, except for fluoride and nitrate ions. 2 tables

  2. Proceedings of a specialist meeting on boron reactivity transients

    International Nuclear Information System (INIS)

    The CSNI Specialist Meeting on Boron Dilution Reactivity Transients was hosted by the Penn State University in collaboration with the US Nuclear Regulatory Commission and the TRAC Users Group. More than 70 experts from 12 OECD countries, as well as experts from Russia and other non-OECD countries attended the meeting. Thirty papers were presented in five technical sessions. The purpose of the meeting was to bring together experts involved in the different activities related to boron dilution transients. The experts came from all involved parties, including research organizations, regulatory authorities, vendors and utilities. Information was openly shared and discussed on the experimental results, plant and systems analysis, numerical analysis of mixing and probability and consequences of these transients. Regulatory background and licensing implications were also included to provide the proper frame work for the technical discussion. Each of these areas corresponded to a separate session. The meeting focused on the thermal-hydraulic aspects because of the current interest in that subject and the significant amount of new technical information being generated. Three papers of the same conference are already available in INIS as individual reports: Potential for boron dilution during small-break LOCAs in PWRs (Ref. number: 27029412); Analysis of boron dilution in a four-loop PWR (Ref. number: 27051651); Probability and consequences of a rapid boron dilution sequence in a PWR (Ref. number: 27029411)

  3. 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.

  4. 16 CFR 1018.16 - Membership selection.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Membership selection. 1018.16 Section 1018... Establishment of Advisory Committees § 1018.16 Membership selection. (a) Whenever new applicants are required... qualified, staff members of the Commission, including the Advisory Committee Management Officer. (d)...

  5. Influence of boron on the morphological and physiological growth parameters of bean

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, S.A. de (Brasilia Univ. (Brazil). Dept. de Engenharia Agronomica); Blanco, S.A.; Engleman, E.M. (Colegio de Post-graduados, Chapingo (Mexico))

    1982-05-01

    Effect of boron on Phaseolus vulgaris L. var. Cacahuate was studied in nutrient solutions containing 0.000; 0.005; 0.050 and 0.500 ppm of the element. The deficiency of boron affected root growth, leaf development and plant growth. Lower values of net assimilation rate (NAR) indicated reduced photosynthetic activity in the case of boron deficiency.

  6. 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. PMID:27387806

  7. 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.

  8. 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.

  9. High Purity and Yield of Boron Nitride Nanotubes Using Amorphous Boron and a Nozzle-Type Reactor

    Directory of Open Access Journals (Sweden)

    Jaewoo Kim

    2014-08-01

    Full Text Available Enhancement of the production yield of boron nitride nanotubes (BNNTs with high purity was achieved using an amorphous boron-based precursor and a nozzle-type reactor. Use of a mixture of amorphous boron and Fe decreases the milling time for the preparation of the precursor for BNNTs synthesis, as well as the Fe impurity contained in the B/Fe interdiffused precursor nanoparticles by using a simple purification process. We also explored a nozzle-type reactor that increased the production yield of BNNTs compared to a conventional flow-through reactor. By using a nozzle-type reactor with amorphous boron-based precursor, the weight of the BNNTs sample after annealing was increased as much as 2.5-times with much less impurities compared to the case for the flow-through reactor with the crystalline boron-based precursor. Under the same experimental conditions, the yield and quantity of BNNTs were estimated as much as ~70% and ~1.15 g/batch for the former, while they are ~54% and 0.78 g/batch for the latter.

  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. Stealth Amphiphiles: Self-Assembly of Polyhedral Boron Clusters.

    Science.gov (United States)

    Ďorďovič, Vladimír; Tošner, Zdeněk; Uchman, Mariusz; Zhigunov, Alexander; Reza, Mehedi; Ruokolainen, Janne; Pramanik, Goutam; Cígler, Petr; Kalíková, Květa; Gradzielski, Michael; Matějíček, Pavel

    2016-07-01

    This is the first experimental evidence that both self-assembly and surface activity are common features of all water-soluble boron cluster compounds. The solution behavior of anionic polyhedral boranes (sodium decaborate, sodium dodecaborate, and sodium mercaptododecaborate), carboranes (potassium 1-carba-dodecaborate), and metallacarboranes {sodium [cobalt bis(1,2-dicarbollide)]} was extensively studied, and it is evident that all the anionic boron clusters form multimolecular aggregates in water. However, the mechanism of aggregation is dependent on size and polarity. The series of studied clusters spans from a small hydrophilic decaborate-resembling hydrotrope to a bulky hydrophobic cobalt bis(dicarbollide) behaving like a classical surfactant. Despite their pristine structure resembling Platonic solids, the nature of anionic boron cluster compounds is inherently amphiphilic-they are stealth amphiphiles. PMID:27287067

  12. Carbon-rich icosahedral boron carbide designed from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Jay, Antoine; Vast, Nathalie; Sjakste, Jelena; Duparc, Olivier Hardouin [Ecole Polytechnique, Laboratoire des Solides Irradiés, CEA-DSM-IRAMIS, CNRS UMR 7642, F-91120 Palaiseau (France)

    2014-07-21

    The carbon-rich boron-carbide (B{sub 11}C)C-C has been designed from first principles within the density functional theory. With respect to the most common boron carbide at 20% carbon concentration B{sub 4}C, the structural modification consists in removing boron atoms from the chains linking (B{sub 11}C) icosahedra. With C-C instead of C-B-C chains, the formation of vacancies is shown to be hindered, leading to enhanced mechanical strength with respect to B{sub 4}C. The phonon frequencies and elastic constants turn out to prove the stability of the carbon-rich phase, and important fingerprints for its characterization have been identified.

  13. 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.)

  14. Neutron beam monitor based on a boron-coated GEM

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jian-Rong; LI Yi; SUN Zhi-Jia; LIU Ben; WANG Yan-Feng; YANG Gui-An; ZHOU Liang; XU Hong; DONG Jing; YANG Lei

    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 one surface of the aluminum cathode plate as the neutron convertor. 96 channel pads with an area of 8 mm×8 mm each are used for fast signal readout.In order to study the basic characteristics of a boron-coated GEM, several irradiation tests were carried out with α source 239pu and neutron source 241Am(Be). The signal induced by the neutron source has a high signal-to-noise ratio. A clear image obtained from α source 239pu is presented, which shows that the neutron beam monitor based on a boron-coated GEM has a good two-dimensional imaging ability.

  15. Investigations on the characterization of ion implanted hexagonal boron nitride

    Science.gov (United States)

    Aradi, E.; Naidoo, S. R.; Erasmus, R. M.; Julies, B.; Derry, T. E.

    2013-07-01

    The effect of ion implantation on hexagonal boron nitride (h-BN) is studied herein. We use boron as an ion of choice to introduce radiation damage into h-BN, at fluences ranging from 1 × 1014-1 × 1016 ions/cm2 and implantation energy ranges from 40 to 160 keV. The thermal dependence is also investigated by varying the annealing temperature from room temperature to 400 °C after implantation. Raman spectroscopy showed Raman active defects one of which is possibly related to the formation of cubic boron nitride nanocrystals (nc-BN) within the implanted range. The relationship of these defect induced Raman active peaks was investigated by varying the implantation parameters. The preliminary Transmission Electron Microscopy (TEM) results also are reported briefly.

  16. A novel boron-loaded liquid scintillator for neutron detection

    Energy Technology Data Exchange (ETDEWEB)

    Bentoumi, G.; Dai, X.; Pruszkowski, E.; Li, L.; Sur, B., E-mail: bentoumg@aecl.ca [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2012-06-15

    A boron-loaded liquid scintillator (LS) has been optimized for neutron detection application in a high gamma field environment. It is composed of the solvent linear alkylbenzene (LAB), a boron containing material, o-carborane (C{sub 2}B{sub 10}H{sub 12}); a fluor, 2,5-diphenyloxazole (PPO); and a wavelength shifter, 1,4-bis[2-methylstyryl] benzene (bis-MSB). Preparation of the liquid scintillator and optimization of its chemical composition are described. The boron-loaded LS has been tested with a neutron beam at the National Research Universal (NRU) reactor. A peak at an equivalent energy of 60 keV is observed in the energy spectrum and is attributed to neutrons. The results confirm the possibility of using B-10 loaded scintillator as a sensitive medium for neutron detection in a relatively large background of gamma rays. (author)

  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. Architecting boron nanostructure on the diamond particle surface

    Energy Technology Data Exchange (ETDEWEB)

    Bai, H.; Dai, D.; Yu, J.H. [Key Laboratory of Marine New Materials and Application Technology, Ningbo Institute of Materials Technologies and Engineering, Chinese Academy of Sciences, 519 Zhuangshi Road, Zhenhai, Ningbo 315201 (China); Nishimura, K. [Key Laboratory of Marine New Materials and Application Technology, Ningbo Institute of Materials Technologies and Engineering, Chinese Academy of Sciences, 519 Zhuangshi Road, Zhenhai, Ningbo 315201 (China); Kochi FEL Co. Ltd., 3-1,Shinonome-cho, Kochi-shi 780-0805 (Japan); Sasaoka, S. [Kochi FEL Co. Ltd., 3-1,Shinonome-cho, Kochi-shi 780-0805 (Japan); Jiang, N., E-mail: jiangnan@nimte.ac.cn [Key Laboratory of Marine New Materials and Application Technology, Ningbo Institute of Materials Technologies and Engineering, Chinese Academy of Sciences, 519 Zhuangshi Road, Zhenhai, Ningbo 315201 (China)

    2014-02-15

    The present study provides an efficient approach for nano-functionalization of diamond powders. Boron nanostructure can be grown on diamond particle entire surface by a simple heat-treatment process. After treatment, various boron nanoforms were grown on the diamond particle surface at different processing temperature. High-density boron nanowires (BNWs) grow on the diamond particle entire surface at 1333 K, while nanopillars cover diamond powders when the heat treatment process is performed at 1393 K. The influence of the pretreatment temperature on the microstructure and thermal conductivity of Cu/diamond composites were investigated. Cu/diamond composites with high thermal conductivity of 670 W (m K){sup −1} was obtained, which was achieved by the formation of large number of nanowires and nanopillars on the diamond particle surface.

  19. Studies of boron-interstitial clusters in Si

    International Nuclear Information System (INIS)

    The large number of self-interstitials created during implantation mediate the fast transient diffusion of implanted boron, leading to clustering. Sophisticated annealing strategies based on knowledge of the formation energy of the clusters are required to achieve full activation of the implant. In recent years attempts have been made to determine these data a priori from theoretical calculations. However, energy calculations alone are not sufficient to establish the key players in the clustering process of boron. The present paper describes a systematic first-principles quantum mechanical study of the characteristic vibration frequencies of a large number of boron-interstitial clusters (including possible configurational isomers). Comparison with the first Raman spectra obtained on B-implanted samples after high temperature annealing is presented

  20. 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.

  1. 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.

  2. 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.

  3. Studies of boron-interstitial clusters in Si

    Energy Technology Data Exchange (ETDEWEB)

    Deak, Peter [Budapest University of Technology and Economics, Department of Atomic Physics, Budafoki ut 8, H-1111 Budapest (Hungary); Gali, Adam [Budapest University of Technology and Economics, Department of Atomic Physics, Budafoki ut 8, H-1111 Budapest (Hungary); Solyom, Andras [Budapest University of Technology and Economics, Department of Atomic Physics, Budafoki ut 8, H-1111 Budapest (Hungary); Ordejon, Pablo [Institut de Ciencia de Materials de Barcelona, E-08193 Bellaterra, Barcelona (Spain); Kamaras, Katalin [Research Institute for Solid State Physics and Optics, Hungarian Academy of Science, H-1128 Budapest (Hungary); Battistig, Gabor [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Science, H-1128 Budapest (Hungary)

    2003-07-30

    The large number of self-interstitials created during implantation mediate the fast transient diffusion of implanted boron, leading to clustering. Sophisticated annealing strategies based on knowledge of the formation energy of the clusters are required to achieve full activation of the implant. In recent years attempts have been made to determine these data a priori from theoretical calculations. However, energy calculations alone are not sufficient to establish the key players in the clustering process of boron. The present paper describes a systematic first-principles quantum mechanical study of the characteristic vibration frequencies of a large number of boron-interstitial clusters (including possible configurational isomers). Comparison with the first Raman spectra obtained on B-implanted samples after high temperature annealing is presented.

  4. 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.

  5. Osmium Atoms and Os2 Molecules Move Faster on Selenium-Doped Compared to Sulfur-Doped Boronic Graphenic Surfaces

    OpenAIRE

    Barry, Nicolas P. E.; Pitto-Barry, Anaïs; Tran, Johanna; Spencer, Simon E. F.; Johansen, Adam M.; Sanchez, Ana M.; Dove, Andrew P.; O’Reilly, Rachel K.; Deeth, Robert J; Beanland, Richard; Sadler, Peter J

    2015-01-01

    We deposited Os atoms on S- and Se-doped boronic graphenic surfaces by electron bombardment of micelles containing 16e complexes [Os(p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-diselenate/dithiolate)] encapsulated in a triblock copolymer. The surfaces were characterized by energy-dispersive X-ray (EDX) analysis and electron energy loss spectroscopy of energy filtered TEM (EFTEM). Os atoms moved ca. 26× faster on the B/Se surface compared to the B/S surface (233 ± 34 pm·s–1 versus 8.9 ± 1.9 ...

  6. Measured variation in boron loads reaching European sewage treatment works.

    Science.gov (United States)

    Fox, K K; Cassani, G; Facchi, A; Schröder, F R; Poelloth, C; Holt, M S

    2002-05-01

    Per capita boron loads reaching 48 sewage treatment works (STWs) in The Netherlands, Germany, Italy, and the UK have been determined from monitoring data. These have been compared with the per capita input predicted from boron in detergents, as determined from detergent product sales data. The resulting distribution of the ratios of measured boron to boron predicted from consumer usage has a 90th percentile of less than 1.5. Boron has previously been shown to be a good marker for substances contained in detergent products, as it cannot be biodegraded and is not substantially adsorbed in the sewer, and there is little or no removal during sewage treatment processes. The monitoring information on the distribution of boron loads found at the different STWs should thus be indicative of the distribution of other substances released to the environment by detergent products, as specified by the relevant industrial category (IC 5-personal/domestic) in the Technical Guidance Documents. Variation in detergent product consumption figures from 18 European countries is also low, with the country with the highest per capita detergent consumption having only 1.3 times the European average detergent use. Thus the present practice of determining a "reasonable worst case" by multiplying the average per capita consumption by a factor of four to account for geographic differences in distribution, is considered to be inappropriate. This should be replaced by a factor of less than two, which combines within country and between country variations to provide a reasonable worst case approximation of the load reaching the sewage treatment facility. PMID:11996125

  7. Substrate-induced bandgap in graphene on hexagonal boron nitride

    OpenAIRE

    Giovannetti, Gianluca; Khomyakov, Petr A.; Brocks, Geert; Paul J. Kelly; Brink, Jeroen van den

    2007-01-01

    We determine the electronic structure of a graphene sheet on top of a lattice-matched hexagonal boron nitride (h-BN) substrate using ab initio density functional calculations. The most stable configuration has one carbon atom on top of a boron atom, the other centered above a BN ring. The resulting inequivalence of the two carbon sites leads to the opening of a gap of 53 meV at the Dirac points of graphene and to finite masses for the Dirac fermions. Alternative orientations of the graphene s...

  8. 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.

  9. 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.

  10. 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.

  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. An automated boron management system for WWER-1000 nuclear reactors

    Directory of Open Access Journals (Sweden)

    Taisiya O. Tsiselskaya

    2015-03-01

    Full Text Available The article is devoted to the problem of creating a system of automated control with boron regulation for reactor WWER-1000 series. Using the boron regulation to control WWER-1000 allows to extend its maximum output operation period, ensuring the economic efficiency of the power unit, as well as to maintain the reactor facility within relevant safety limits that prevents from emergencies occurrence and development. The results of this problem solution, related to the process simulation, optimization and prediction, were used at further development of computer-integrated control system increasing the efficiency of decisions, taken by operational staff at reactor control.

  13. 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.

  14. Boron neutron capture therapy; Radioterapia per cattura neutronica del boro

    Energy Technology Data Exchange (ETDEWEB)

    Mattioda, F. [Turin Politecnico, Turin (Italy); Merlone, A. [Pisa Univ., Pisa (Italy); Agosteo, S. [Milan Politecnico, Milan (Italy); Istituto Nazionale di Fisica Nucleare, Milan (Italy); Burn, K.W.; Tinti, R. [ENEA, Bologna (Italy). Dipt. energia; Capannesi, G.; Rosi, G. [ENEA, Casaccia (Italy). Dipt. innovazione; Casali, F.; Nava, E. [Bologna UNiv., Bologna (Italy); Gambarini, G. [Milan Univ., Milan (Italy)

    1999-08-01

    Boron radiotherapy in cancer treatment and the feasibility of using the Tapiro reactor as a neutron source is discussed. In particle, the article aims to focus attention on the possibility using ENEA's (National Agency for New Technology, Energy and the Environment) Tapiro reactor, appropriately modified, as a suitable neutron source for the experimental phase of boron neutron capture therapy in Italy. [Italian] Sono presentati gli studi sulla radioterapia per cattura neutronica del boro nella cura di alcune neoplasie e l'utilizzo del reattore Tapiro come sorgente di neutroni nel progetto italiano di ricerca condotto dall'ENEA.

  15. Medical and biological requirements for boron neutron capture therapy

    International Nuclear Information System (INIS)

    In conventional radiation therapy, tumor doses applied to most solid tumors are limited by the tolerance of normal tissues. The promise of Boron Neutron Capture Therapy lies in its potential to deposit high doses of radiation very specifically to tumor tissue. Theoretically ratios of tumor to normal tissue doses can be achieved significantly higher than conventional radiotherapeutic techniques would allow. Effective dose distributions obtainable are a complex function of the neutron beam characteristics and the macro and micro distributions of boron in tumor and normal tissues. Effective RBE doses are calculated in tumors and normal tissue for thermal, epithermal and 2 keV neutrons

  16. 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

  17. 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.

  18. THE EFFECT OF BORON DOSES ON PARICA (Schizolobium amazonicum Herb.)

    OpenAIRE

    Sebastião Ferreira de Lima; Rodrigo Luz da Cunha; Janice Guedes de Carvalho; Carlos Alberto Spaggiari Souza; Fernando Luiz de Oliveira Corrêa

    2003-01-01

    An experiment was conducted in a greenhouse in order to evaluate the effects of boron on parica growth and on concentration and contents of macro and micronutrients indry matter of shoots and roots. Six treatments constituted by boron doses of 0.0; 0.1; 0.3; 0.9;1.5 and 2.1 mg/dm3 in four replications were used. It was evaluated the characteristics:visual diagnostic, plants height and diameter, dry matter production of shoots and roots,concentration and contents of nutrients in dry matter of ...

  19. Hydrogen storage in pillared Li-dispersed boron carbide nanotubes

    OpenAIRE

    Wu, Xiaojun; Gao, Yi; Zeng, Xiao Cheng

    2007-01-01

    Ab initio density-functional theory study suggests that pillared Li-dispersed boron carbide nanotubes is capable of storing hydrogen with a mass density higher than 6.0 weight% and a volumetric density higher than 45 g/L. The boron substitution in carbon nanotube greatly enhances the binding energy of Li atom to the nanotube, and this binding energy (~ 2.7 eV) is greater than the cohesive energy of lithium metal (~1.7 eV), preventing lithium from aggregation (or segregation) at high lithium d...

  20. 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.

  1. 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.

  2. Fabrication of particular structures of hexagonal boron nitride and boron-carbon-nitrogen layers by anisotropic etching

    Science.gov (United States)

    Vishwakarma, Riteshkumar; Sharma, Subash; Shinde, Sachin M.; Sharma, Kamal P.; Thangaraja, Amutha; Kalita, Golap; Tanemura, Masaki

    2016-05-01

    Anisotropic etching of hexagonal boron nitride (h-BN) and boron-carbon-nitrogen (BCN) basal plane can be an exciting platform to develop well-defined structures with interesting properties. Here, we developed an etching process of atomically thin h-BN and BCN layers to fabricate nanoribbons (NRs) and other distinct structures by annealing in H2 and Ar gas mixture. BCN and h-BN films are grown on Cu foil by chemical vapor deposition (CVD) using solid camphor and ammonia borane as carbon, nitrogen and boron source, respectively. Formation of micron size well-defined etched holes and NRs are obtained in both h-BN and BCN layers by the post growth annealing process. The etching process of h-BN and BCN basal plane to fabricate NRs and other structures with pronounced edges can open up new possibilities in 2D hybrid materials.

  3. Structure of boron clusters revisited, Bn with n = 14-20

    Science.gov (United States)

    Tai, Truong Ba; Tam, Nguyen Minh; Nguyen, Minh Tho

    2012-03-01

    We reinvestigate the structures of neutral boron clusters Bn, with n = 14-20. G3B3 calculations confirm that a transition between 2D and 3D shape occurs at B20, which has a tubular form. In disagreement with Boustani et al. (Phys. Rev. B, 83 (2011) 193405), we find a planar B19 cluster. Standard heats of formation are obtained and used to evaluate the clusters stability. The average binding energy tends to increase with increasing size toward a limit. Higher stability is found B14, B16, B18 and B20. All Bn have negative NICS-values. The bonding nature and electron delocalization of B20 are re-examined using CMO and LOL.

  4. Boron removal from metallurgical grade silicon using a FeCl2 molten salt refining technique

    OpenAIRE

    Jia B.J.; Wu J. J.; Ma W.H.; Yang B; Liu D.C.; Dai Y.N.

    2013-01-01

    The slag refining for boron removal from metallurgical grade silicon is a promising metallurgical process for producing solar grade silicon. In this paper, FeCl2 molten salt has been used as a new refining agent to remove boron from MG-Si. The effects of refining time and mass ratio of MG-Si to FeCl2 molten salt on boron removal have been investigated in detail. The results showed that boron can be efficiently removed in form of BCl3 and boron concentration...

  5. 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.

  6. Preparation and characterization of sputtered boron nitride and boron carbide films and their modification by ion implantation

    International Nuclear Information System (INIS)

    Nanocrystalline cubic boron nitride and boron carbide films have been synthesized using sputtering. The relationship between the structures and properties as well as the influence of the deposition parameters, such as rf power, bias voltage, substrate temperature, composition and flow rate of the sputtering gas, on the structures and properties have been studied. The influence of the ion bombardment could be described by the specific ion momentum P*=[ion momentum.(ion flux/atom flux)]. The specific ion momentum was found to be proportional to the rf power and to the 1.5th power of the bias voltage. Two phases have been identified in our boron nitride films: hexagonal boron nitride (h-BN) and cubic boron nitride (c-BN); the films were either single phase or contained a mixture of these two phases. Nanocrystalline boron films have been grown with a deposition rate of 2 nm/s not only on Si but also on hard metal (WC-6%Co) substrates. Stoichiometric and crystalline films have already been grown at room temperature (about 0.1 Tm, Tm=melting point-3900 K). All the films contained about 8 at% carbon and 6 at% oxygen as impurities, which come mainly from the targt. The concentration of the impurities is independent of the deposition paramters. The growth of c-BN appears after the specific ion momentum larger than a threshold value, which is dependent on the substrate temperature, composition and on the flow rate of the sputtering gas. The volume content of c-BN runs through a maximum value with increasing specific ion momentum. (orig.)

  7. Biodistribution and subcellular localization of an unnatural boron-containing amino acid (cis-ABCPC by imaging secondary ion mass spectrometry for neutron capture therapy of melanomas and gliomas.

    Directory of Open Access Journals (Sweden)

    Subhash Chandra

    Full Text Available The development of new boron-delivery agents is a high priority for improving the effectiveness of boron neutron capture therapy. In the present study, 1-amino-3-borono-cyclopentanecarboxylic acid (cis-ABCPC as a mixture of its L- and D-enantiomers was evaluated in vivo using the B16 melanoma model for the human tumor and the F98 rat glioma as a model for human gliomas. A secondary ion mass spectrometry (SIMS based imaging instrument, CAMECA IMS 3F SIMS Ion Microscope, was used for quantitative imaging of boron at 500 nm spatial resolution. Both in vivo and in vitro studies in melanoma models demonstrated that boron was localized in the cytoplasm and nuclei with some cell-to-cell variability. Uptake of cis-ABCPC in B16 cells was time dependent with a 7.5:1 partitioning ratio of boron between cell nuclei and the nutrient medium after 4 hrs. incubation. Furthermore, cis-ABCPC delivered boron to cells in all phases of the cell cycle, including S-phase. In vivo SIMS studies using the F98 rat glioma model revealed an 8:1 boron partitioning ratio between the main tumor mass and normal brain tissue with a 5:1 ratio between infiltrating tumor cells and contiguous normal brain. Since cis-ABCPC is water soluble and can cross the blood-brain-barrier via the L-type amino acid transporters (LAT, it may accumulate preferentially in infiltrating tumor cells in normal brain due to up-regulation of LAT in high grade gliomas. Once trapped inside the tumor cell, cis-ABCPC cannot be metabolized and remains either in a free pool or bound to cell matrix components. The significant improvement in boron uptake by both the main tumor mass and infiltrating tumor cells compared to those reported in animal and clinical studies of p-boronophenylalanine strongly suggest that cis-ABCPC has the potential to become a novel new boron delivery agent for neutron capture therapy of gliomas and melanomas.

  8. 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 %.

  9. 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

    2013-12-01

    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.

  10. Wich Parameter of the Carbonate System Influences the Boron Isotopic Composition and the Boron Calcium Ratio in Foraminiferal Tests?

    Science.gov (United States)

    Kaczmarek, K.; Nehrke, G.; Horn, I.; Langer, G.; Misra, S.; Bijma, J.

    2013-12-01

    We performed culture experiments with the benthic symbiont bearing foraminifer Amphistegina lessonii in order to determine which parameter of the marine carbonate system influences the boron isotopic composition (δ11B) and the boron calcium ratio (B/Ca) in the test. A. lessonii grew for two months in treatments of culture media with decoupled pH-carbonate chemistry. We measured δ11B and B/Ca simultaneously on single tests using a recently new developed mass spectrometric technique. Our results show a clear pH dependence on δ11B. The B/Ca in the shell show a positive correlation with aqueous B(OH)4-/HCO3-.

  11. 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.

  12. 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.

  13. Prompt gamma activation analysis of boron in reference materials using diffracted polychromatic neutron beam

    International Nuclear Information System (INIS)

    Boron concentrations were analyzed for standard reference materials by prompt gamma activation analysis (PGAA). The measurements were performed at the SNU-KAERI PGAA facility installed at Hanaro, the research reactor of Korea Atomic Energy Research Institute (KAERI). The facility uses a diffracted polychromatic beam with a neutron flux of 7.9 x 107 n/cm2 s. Elemental sensitivity for boron was calibrated from the prompt gamma-ray spectra of boric acid samples containing 2-45 μg boron. The sensitivity of 2131 cps/mg-B was obtained from the linearity of the boron peak count rate versus the boron mass. The detection limit for boron was estimated to be 67 ng from an empty sample bag spectrum for a counting time of 10,000 s. The measured boron concentrations for standard reference materials showed good consistency with the certified or information values

  14. 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.

  15. Prompt gamma activation analysis of boron in reference materials using diffracted polychromatic neutron beam

    Science.gov (United States)

    Byun, S. H.; Sun, G. M.; Choi, H. D.

    2004-01-01

    Boron concentrations were analyzed for standard reference materials by prompt gamma activation analysis (PGAA). The measurements were performed at the SNU-KAERI PGAA facility installed at Hanaro, the research reactor of Korea Atomic Energy Research Institute (KAERI). The facility uses a diffracted polychromatic beam with a neutron flux of 7.9 × 10 7 n/cm 2 s. Elemental sensitivity for boron was calibrated from the prompt gamma-ray spectra of boric acid samples containing 2-45 μg boron. The sensitivity of 2131 cps/mg-B was obtained from the linearity of the boron peak count rate versus the boron mass. The detection limit for boron was estimated to be 67 ng from an empty sample bag spectrum for a counting time of 10,000 s. The measured boron concentrations for standard reference materials showed good consistency with the certified or information values.

  16. Recent results of boronization on EAST and HT-7 superconducting tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J.H., E-mail: wujinhua@ipp.ac.cn [Institute of Plasma Physics, P.O. Box 1126, Hefei, Anhui 230031 (China); Hu, J.S., E-mail: hujs@ipp.ac.cn [Institute of Plasma Physics, P.O. Box 1126, Hefei, Anhui 230031 (China); Chen, Y. [Institute of Plasma Physics, P.O. Box 1126, Hefei, Anhui 230031 (China); Ashikawa, N. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Yu, Y.W.; Li, J.H.; Zuo, G.Z.; Wang, X.M.; Zhao, Y.P.; Li, J.G. [Institute of Plasma Physics, P.O. Box 1126, Hefei, Anhui 230031 (China)

    2011-08-01

    The importance of wall conditionings for the reduction of the impurities in plasmas has been recognized in most tokamaks. Boronization associated with Ion Cyclotron Resonance Frequency discharge (ICRF boronization) has been developed on HT-7 superconducting tokamak since 1998, and now this boronization technique has become a routine method for wall conditioning on HT-7 and also on EAST. Carborane (C{sub 2}B{sub 10}H{sub 12}) was used for the boronization and helium was usually provided as the auxiliary gas. However, after this kind boronization, lots of H{sub 2} released from the boron film make the controlling of the plasma density very difficulty. Recently, to reduce H{sub 2} content in the film, we change the auxiliary gas from He to D{sub 2} during the whole boronization procedure and find the release of H{sub 2} during plasma discharges was greatly reduced.

  17. 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.

  18. 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. PMID:26298436

  19. Proton nuclear magnetic resonance measurement of p-boronophenylalanine (BPA): A therapeutic agent for boron neutron capture therapy

    OpenAIRE

    Zuo, C. S.; Prasad, P V; Busse, Paul; L. Tang; Zamenhof, R. G.

    1999-01-01

    Noninvasive in vivo quantitation of boron is necessary for obtaining pharmacokinetic data on candidate boronated delivery agents developed for boron neutron capture therapy (BNCT). Such data, in turn, would facilitate the optimization of the temporal sequence of boronated drug infusion and neutron irradiation. Current approaches to obtaining such pharmacokinetic data include: positron emission tomography employing F-18 labeled boronated delivery agents (e.g., p-boronophenylalanine), ex vivo n...

  20. 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.

  1. The determination of boron in aluminium of high purity

    International Nuclear Information System (INIS)

    A description is given of the investigations that led to the development of chemical methods for the determination of boron within the range 0,25 to 1,0 p.p.m. in aluminium of high purity. Methods were developed that incorporated fluorimetry, directly in solutions containing aluminium and after separation of boron by liquid-liquid extraction into 2-ethyl-1,3 hexanediol. A published spectrophotometric method, involving extraction of the BF4sup(-) complex with methylene blue into dichloroethane, was modified for application to alluminium samples. Details of this modified procedure and the fluorimetric-extraction procedure are appended. The precision of the methylene-blue method is about 6 percent relative and is recommended for precision and speed in preference to others. Separation of boron by distillation and spectrophotometric determination with curcumin gave low values in comparison with those obtained by the other methods. Agreement between the boron values obtained on the samples tested was good for the fluorimetric and methylene-blue spectrophotometric methods

  2. 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...

  3. The feasibility of boron removal from water by capacitive deionization

    Energy Technology Data Exchange (ETDEWEB)

    Avraham, Eran, E-mail: eranchem@gmail.com [Department of Chemistry, Bar Ilan University, Ramat-Gan 52900 (Israel); Noked, Malachi; Soffer, Abraham; Aurbach, Doron [Department of Chemistry, Bar Ilan University, Ramat-Gan 52900 (Israel)

    2011-07-15

    Highlights: > Boron removal by electrochemical means. > Temporary local pH changes developed within the pores were indicated by using MgCl{sub 2} in the solution as a probe. > The process of Boron extraction from water takes place in two stages: 1. dissociation of boric acid on the negatively polarized electrode. 2. Electro-adsorption of borate ion onto the positively polarized electrode. - Abstract: We report on the possibility of removing boron (in the form of boric acid) from water by electrochemical means. We explore capacitive de-ionization (CDI) processes in which local changes in pH near the surface of high-surface-area activated carbon fiber (ACF) electrodes during charging are utilized, in order to dissociate boric acid into borate ions which can be electro-adsorbed onto the positive electrode in the CDI cells. For this purpose, a special flow-through CDI cell was constructed in which the feed solution flows through the electrodes. Local pH changes near the carbon electrode surface were investigated using a MgCl{sub 2} solution probe in three- (with reference) and two-electrode cells, and described qualitatively. We show that, to a certain extent, boron can indeed be removed from water by CDI.

  4. Safety analyses and evaluations for an increased refueling boron concentration

    Energy Technology Data Exchange (ETDEWEB)

    Harrell, J.R.

    1989-01-01

    Virginia Power has recently completed the requisite safety analyses and evaluations to support an increase in the refueling boron concentration from 2000 to 2300 ppm at its two Surry nuclear units. It is expected that the applicable technical specifications will be amended in mid-1989 following U.S. Nuclear Regulatory Commission review and approval of the technical specifications change package. The primary benefit of the proposed technical specifications changes is an increased cycle length made possible by increased reactivity hold-down at beginning of life (BOL). By using boron rather than burnable poison (BP) rods to compensate for the additional reactivity requirements of an uprated core power, the reactivity deficit at end of life due to the displacement of moderator by the BP and due to the negative reactivity of the BP rods themselves is avoided. The increased boron concentration permits more effective use of BP rods for control of the local power distribution. A rigorous evaluation of the impact of an increased refueling boron concentration on current safety limits would include, but is not limited to, an examination of the following: (1) non-loss-of-coolant-accident (LOCA) final safety analysis report (FSAR) transient analyses, (2) LOCA analysis, (3) containment analysis, (4) environmental qualification of equipment within containment, (5) primary coolant chemistry, and (6) measurement and calculational uncertainties.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  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. 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.

  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. 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.

  13. 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

    2016-01-01

    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. PMID:27488228

  14. Radiation-enhanced self- and boron diffusion in germanium

    DEFF Research Database (Denmark)

    Schneider, S.; Bracht, H.; Klug, J.N.;

    2013-01-01

    We report experiments on proton radiation-enhanced self- and boron (B) diffusion in germanium (Ge) for temperatures between 515 ∘ C and 720 ∘ C. Modeling of the experimental diffusion profiles measured by means of secondary ion mass spectrometry is achieved on the basis of the Frenkel pair reaction...

  15. Modification of optical surfaces employing CVD boron carbide coatings

    International Nuclear Information System (INIS)

    Non-reflective or high emissivity optical surfaces require materials with given roughness or surface characteristics wherein interaction with incident radiation results in the absorption and dissipation of a specific spectrum of radiation. Coatings have been used to alter optical properties, however, extreme service environments, such as experienced by satellite systems and other spacecraft, necessitate the use of materials with unique combinations of physical, chemical, and mechanical properties. Thus, ceramics such as boron carbide are leading candidates for these applications. Boron carbide was examined as a coating for optical baffle surfaces. Boron carbide coatings were deposited on graphite substrates from BCl3, CH4, and H2 gases employing chemical vapor deposition (CVD) techniques. Parameters including temperature, reactant gas compositions and flows, and pressure were explored. The structures of the coatings were characterized using electron microscopy and compositions were determined using x-ray diffraction. The optical properties of the boron carbide coatings were measured, and relationships between processing conditions, deposit morphology, and optical properties were determined

  16. 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....

  17. 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....

  18. 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....

  19. 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)

  20. 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.

  1. Predicted boron-carbide compounds: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, De Yu; Yan, Qian; Wang, Bing; Wang, Yuan Xu, E-mail: wangyx@henu.edu.cn; Yang, Jueming; Yang, Gui [Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004 (China)

    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 B{sub 5}C indicates its high stability. The density of states of B{sub 5}C show that it is p-type semiconducting. The calculated theoretical Vickers hardnesses of B-C exceed 40 GPa except B{sub 4}C, BC, and BC{sub 4}, 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. Seebeck coefficient and electrical conductivity of doped Beta-Boron

    International Nuclear Information System (INIS)

    Beta-rhombohedral boron (β-B) was investigated to determine its potential for use as a high temperature thermoelectric material. Single dopants to produce n or p-type material were found. The figure of merit for both types of materials is less than that of silicongermanium thermoelectric alloys

  3. Electron deformation density distribution in α-boron

    International Nuclear Information System (INIS)

    The bonding features of α-boron were studied using electron density analysis procedures. Deformation density maps and valence density were calculated and the structure analysed by so-called multipole refinements, yielding R = 0.0119. The refinement model correctly describes the bonding and results in a difference density distribution free from any meaningful residual peaks

  4. 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.

  5. Boron nitride elastic and thermal properties. Irradiation effects

    International Nuclear Information System (INIS)

    The anisotropy of boron nitride (BN) and especially thermal and elastic properties were studied. Specific heat and thermal conductivity between 1.2 and 300K, thermal conductivity between 4 and 350K and elastic constants C33 and C44 were measured. BN was irradiated with electrons at 77K and with neutrons at 27K to determine properties after irradiation

  6. 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

    2016-08-01

    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 δ11B values down to ‑41.5‰, reflecting preferential partitioning of 10B into the assimilating melt. Loss of 11B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports 11B 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 δ11B melt values in arc magmas could flag shallow-level additions to the subduction cycle.

  7. 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. PMID:27250576

  8. In vivo prompt gamma neutron activation analysis for the screening of boron-10 distribution in a rabbit knee: a simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, X; Yanch, J [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA (United States); Clackdoyle, R [Laboratoire Hubert Curien, Mixed Research Unit (UMR) 5516, CNRS and Universite Jean Monnet, Saint Etienne (France); Shortkroff, S [Department of Orthopedic Surgery, Brigham and Women' s Hospital, Harvard Medical School, Boston, MA (United States)

    2008-05-21

    Boron neutron capture synovectomy (BNCS) is under development as a potential treatment modality for rheumatoid arthritis (RA). RA is characterized by the inflammation of the synovium (the membrane lining articular joints), which leads to pain and a restricted range of motion. BNCS is a two-part procedure involving the injection of a boronated compound directly into the diseased joint followed by irradiation with a low-energy neutron beam. The neutron capture reactions taking place in the synovium deliver a local, high-linear energy transfer (LET) dose aimed at destroying the inflamed synovial membrane. For successful treatment via BNCS, a boron-labeled compound exhibiting both high synovial uptake and long retention time is necessary. Currently, the in vivo uptake behavior of potentially useful boronated compounds is evaluated in the knee joints of rabbits in which arthritis has been induced. This strategy involves the sacrifice and dissection of a large number of animals. An in vivo {sup 10}B screening approach is therefore under investigation with the goal of significantly reducing the number of animals needed for compound evaluation via dissection studies. The 'in vivo prompt gamma neutron activation analysis' (IVPGNAA) approach uses a narrow neutron beam to irradiate the knee from several angular positions following the intra-articular injection of a boronated compound whose uptake characteristics are unknown. A high-purity germanium detector collects the 478 keV gamma photons produced by the {sup 10}B capture reactions. The {sup 10}B distribution in the knee is then reconstructed by solving a system of simultaneous equations using a weighted least squares algorithm. To study the practical feasibility of IVPGNAA, simulation data were generated with the Monte Carlo N-particle transport code. The boron-containing region of a rabbit knee was partitioned into 8 compartments, and the {sup 10}B prompt gamma signals were tallied from 16 angular positions

  9. In vivo prompt gamma neutron activation analysis for the screening of boron-10 distribution in a rabbit knee: a simulation study

    Science.gov (United States)

    Zhu, X.; Clackdoyle, R.; Shortkroff, S.; Yanch, J.

    2008-05-01

    Boron neutron capture synovectomy (BNCS) is under development as a potential treatment modality for rheumatoid arthritis (RA). RA is characterized by the inflammation of the synovium (the membrane lining articular joints), which leads to pain and a restricted range of motion. BNCS is a two-part procedure involving the injection of a boronated compound directly into the diseased joint followed by irradiation with a low-energy neutron beam. The neutron capture reactions taking place in the synovium deliver a local, high-linear energy transfer (LET) dose aimed at destroying the inflamed synovial membrane. For successful treatment via BNCS, a boron-labeled compound exhibiting both high synovial uptake and long retention time is necessary. Currently, the in vivo uptake behavior of potentially useful boronated compounds is evaluated in the knee joints of rabbits in which arthritis has been induced. This strategy involves the sacrifice and dissection of a large number of animals. An in vivo 10B screening approach is therefore under investigation with the goal of significantly reducing the number of animals needed for compound evaluation via dissection studies. The 'in vivo prompt gamma neutron activation analysis' (IVPGNAA) approach uses a narrow neutron beam to irradiate the knee from several angular positions following the intra-articular injection of a boronated compound whose uptake characteristics are unknown. A high-purity germanium detector collects the 478 keV gamma photons produced by the 10B capture reactions. The 10B distribution in the knee is then reconstructed by solving a system of simultaneous equations using a weighted least squares algorithm. To study the practical feasibility of IVPGNAA, simulation data were generated with the Monte Carlo N-particle transport code. The boron-containing region of a rabbit knee was partitioned into 8 compartments, and the 10B prompt gamma signals were tallied from 16 angular positions. Results demonstrate that for this

  10. Toxicity assessment of boron (B) by Lemna minor L. and Lemna gibba L. and their possible use as model plants for ecological risk assessment of aquatic ecosystems with boron pollution.

    Science.gov (United States)

    Gür, Nurcan; Türker, Onur Can; Böcük, Harun

    2016-08-01

    As many of the metalloid-based pollutants, the boron (B) toxicity issues have aroused more and more global attentions, especially concerning drinking water sources which flow through boron-rich areas. Therefore, feasible and innovative approaches are required in order to assess B toxicity in aquatic ecosystems. In this study, the toxic effects of B on Lemna minor L. and Lemna gibba L. were investigated using various endpoints including number of fronds, growth rates, dry biomass and antioxidants enzymatic activities. Lemna species were exposed to B concentrations of 2 (control), 4, 8, 16, 32, 64 and 128 mg L(-1) for a test period of 7 days. The results demonstrated that plant growth was significantly reduced when the B concentration reached 16 mg L(-1). Furthermore, our results also concluded that among the antioxidative enzymes, SOD, APX and GPX can serve as important biomarkers for B-rich environment. The present results suggested that L. minor and L. gibba are very useful model plants for phytoremediation of low-B contaminated wastewater and they are also suitable options for B biomonitoring due to high phototoxic sensitivity against B. In this respect, the scientific insight of the present study is to fill the gaps in the research about the use of L. minor and L. gibba in ecotoxicological research associated with B toxicity. PMID:27192627

  11. Grain refinement by boron nitride; Gefuegemodifizierung durch Bornitrid

    Energy Technology Data Exchange (ETDEWEB)

    Bach, F.W.; Guenther, A.; Phan-Tan, T.; Kruessel, T.; Wilk, P. [Institut fuer Werkstoffkunde der Universitaet Hannover, Struktur- und Biomedizinwerkstoffe, Garbsen (Germany)

    2005-01-01

    Grain refinement of magnesium alloys aims at better deformation behaviour, higher strength and improved corrosion resistance. Besides mechanical treatment like pressing, it is possible to refine the grainsize by using nucleation materials. Whereas calcium and rare earth elements are already widely used, the use of boron nitride offers a cheap alternative to refine grains of magnesium aluminum alloys. The effect is achieved by the reaction of boron nitride with aluminum which cracks the chemical compound to form aluminum nitride with the nitrogen while boron is forming different magnesium borides. These two compounds both exhibit very high melting points and are stable in this environment so that they can act as seed crystals. Because boron nitride shows a bad wettability to metal molds, it would float on top of the mold. Therefore, it is necessary to produce pellets out of boron nitride and aluminum powder to improve contact to the mold and enhance reaction velocity. (Abstract Copyright [2005], Wiley Periodicals, Inc.) [German] Durch die Kornfeinung von Magnesiumlegierungen wird das Ziel einer Festigkeitssteigerung, einer verbesserten Umformbarkeit und einer erhoehten Korrosionsbestaendigkeit verfolgt. Neben mechanischen Loesungswegen (Strangpressen etc.) besteht die Moeglichkeit legierungstechnisch durch den Einsatz keimbildender Stoffe eine Kornfeinung zu erzielen. Neben dem Einsatz von Kalzium oder Seltenen Erden bietet Bornitrid eine kostenguenstige Moeglichkeit eine Kornfeinung fuer aluminiumhaltige Magnesiumlegierungen zu erzeugen. Die Kornfeinung beruht dabei auf der Reaktion des Bornitrids mit dem Aluminium in der Schmelze, durch welche das Bornitrid zersetzt wird und mit dem freiwerdenden Stickstoff zu Aluminiumnitrid reagiert, waehrend sich das Bor mit Magnesium zu Magnesiumboriden verbindet. Bei beiden Produkten handelt es sich um hochschmelzende, in dieser Umgebung stabile Verbindungen, die als Kristallisationskeime wirken koennen. Die Zugabe des

  12. Graphite–boron composite heater in a Kawai-type apparatus: the inhibitory effect of boron oxide and countermeasures

    Science.gov (United States)

    Xie, Longjian; Yoneda, Akira; Yoshino, Takashi; Fei, Hongzhan; Ito, Eiji

    2016-04-01

    We have investigated the performance of a graphite-boron composite (GBC) with 3 wt % boron as a precursor for a boron-doped diamond heater in a Kawai-type apparatus at 15 GPa. We first tested a machinable cylinder of GBC sintered at 1000°C in Ar/H2 gas (99:1 molar ratio). Boron oxide (B2O3) formed during sintering frequently hindered the GBC heater from stable operation at temperatures higher than 1400°C by producing melt throughout the heater together with oxide and/or silicates. We then rinsed the GBC heater in hydrochloric acid to remove B2O3. After rinsing, we succeeded in stably generating temperatures higher than 2000°C. We also improved a molding process of different-sized GBC tubes for convenient use and tested the molded GBC heater. It was free from the B2O3 problem. The electromotive force of the W/Re thermocouple was successfully monitored up to 2400°C.

  13. 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 ...

  14. Boron removal by the duckweed Lemna gibba: a potential method for the remediation of boron-polluted waters.

    Science.gov (United States)

    Del-Campo Marín, Claudia M; Oron, Gideon

    2007-12-01

    Boron (B) is often found in polluted and desalinated waters. Despite its potentially environmental damaging effects, efficient treatments are lacking. The duckweed Lemna gibba has been shown to remove toxic elements from water; however, its applicability to B removal is unknown. In this study, L. gibba was examined for its tolerance to B in water and its B removal efficiency. Duckweed plants were grown in outdoor 12-day batch experiments in nutrient solution containing 0.3-10 mg B L(-1). Plant biomass production was not affected by B over the tested concentrations during the 12-day cultivation period. Boron removal and the bioconcentration factor of B in L. gibba were highest at initial B concentrations below 2 mg L(-1), and decreased as the initial B concentration increased. Boron content in the plants at the end of the experiment ranged between 930 and 1900 mg kg(-1) dry weight, and was comparable to that of wetland plants reported to be good B accumulators. Boron removal by L. gibba may therefore be a suitable option for the treatment of water containing B concentrations below 2 mg L(-1). PMID:17643472

  15. Formation of Boron-Carbon Nanosheets and Bilayers in Boron-Doped Diamond: Origin of Metallicity and Superconductivity.

    Science.gov (United States)

    Polyakov, S N; Denisov, V N; Mavrin, B N; Kirichenko, A N; Kuznetsov, M S; Martyushov, S Yu; Terentiev, S A; Blank, V D

    2016-12-01

    The insufficient data on a structure of the boron-doped diamond (BDD) has frustrated efforts to fully understand the fascinating electronic properties of this material and how they evolve with doping. We have employed X-ray diffraction and Raman scattering for detailed study of the large-sized BDD single crystals. We demonstrate a formation of boron-carbon (B-C) nanosheets and bilayers in BDD with increasing boron concentration. An incorporation of two boron atoms in the diamond unit cell plays a key role for the B-C nanosheets and bilayer formation. Evidence for these B-C bilayers which are parallel to {111} planes is provided by the observation of high-order, super-lattice reflections in X-ray diffraction and Laue patterns. B-C nanosheets and bilayers minimize the strain energy and affect the electronic structure of BDD. A new shallow acceptor level associated with B-C nanosheets at ~37 meV and the spin-orbit splitting of the valence band of ~6 meV are observed in electronic Raman scattering. We identified that the superconducting transitions occur in the (111) BDD surfaces only. We believe that the origin of Mott and superconducting transitions is associated with the two-dimensional (2D) misfit layer structure of BDD. A model for the BDD crystal structure, based on X-ray and Raman data, is proposed and confirmed by density functional theoretical calculation. PMID:26754937

  16. Synthesis of carboranes containing an azulene framework and in vitro evaluation as boron carriers.

    Science.gov (United States)

    Nakamura, H; Sekido, M; Yamamoto, Y

    1997-08-29

    3-(o-Carboranylhydroxymethyl)-7-isopropylazulene sodium carboxylate (1) and 3-(o-carboranylmethyl)-7-isopropylazulene sodium sulfonate (2) were synthesized from the palladium-catalyzed addition reaction of 1-carboranyltributylstannane (4) to azulene aldehydes (3 and 9). Although the water solubility of 1 was of the order of 10(-6) M, that of 2 was of the order of 10(-3) M and was enough for clinical use. The cytotoxicity of 1 (IC50) toward B-16 melanoma cells was of the order of 10(-5) M, whereas that of 2 was of the order of 10(-4) M. This value was close to that of BPA (approximately 9 x 10(-3) M) which is utilized for clinical use. The boron uptake by B-16 cells was 0.17 microgram of B/10(6) cells for 1 and 0.25 microgram of B/10(6) cells for 2. It is clear that compound 2 accumulates in B-16 melanoma cells with a significantly high level although it is highly water soluble and its cytotoxicity is significantly low. PMID:9288164

  17. Biodistribution of Boron compounds in an experimental model of liver metastases for Boron Neutron Capture (BNCT) Studies

    International Nuclear Information System (INIS)

    Boron Neutron Capture Therapy (BNCT) is a binary treatment modality that involves the selective accumulation of 10B carriers in tumors followed by irradiation with thermal or epithermal neutrons. The high linear energy transfer alpha particles and recoiling 7Li nuclei emitted during the capture of a thermal neutron by a 10B nucleus have a short range and a high biological effectiveness. Thus, BNCT would potentially target neoplastic tissue selectively. In previous studies we demonstrated the therapeutic efficacy of different BNCT protocols in an experimental model of oral cancer. More recently we performed experimental studies in normal rat liver that evidenced the feasibility of treating liver metastases employing a novel BNCT protocol proposed by JEC based on ex-situ treatment and partial liver auto-transplant. The aim of the present study was to perform biodistribution studies with different boron compounds and different administration protocols to determine the protocols that would be therapeutically useful in 'in vivo' BNCT studies at the RA-3 Nuclear Reactor in an experimental model of liver metastases in rats. Materials and Methods. A total of 70 BDIX rats (Charles River Lab., MA, USA) were inoculated in the liver with syngeneic colon cancer cells DH/DK12/TRb (ECACC, UK) to induce the development of subcapsular metastatic nodules. 15 days post-inoculation the animals were used for biodistribution studies. A total of 11 protocols were evaluated employing the boron compounds boronophenylalanine (BPA) and GB-10 (Na210B1-0H10), alone or combined employing different doses and administration routes. Tumor, normal tissue and blood samples were processed for boron measurement by ICP-OES. Results. Several protocols proved potentially useful for BNCT studies in terms of absolute boron concentration in tumor and preferential uptake of boron by tumor tissue, i.e. BPA 15.5 mg 10B/kg iv + GB-10 50 mg 10B/kg iv; BPA 46.5 mg 10B/kg ip; BPA 46.5 mg 10B/kg ip + iv; BPA 46

  18. High sensitivity boron quantification in bulk silicon using the 11B(p,α0)8Be nuclear reaction

    International Nuclear Information System (INIS)

    There is a great need to quantify sub-ppm levels of boron in bulk silicon. There are several methods to analyze B in Si: Nuclear Reaction Analysis using the 11B(p,α0)8Be reaction exhibits a quantification limit of some hundreds ppm of B in Si. Heavy Ion Elastic Recoil Detection Analysis offers a detection limit of 5 to 10 at. ppm. Secondary Ion Mass Spectrometry is the method of choice of the semiconductor industry for the analysis of B in Si. This work verifies the use of NRA to quantify B in Si, and the corresponding detection limits. Proton beam with 1.6 up to 2.6 MeV was used to obtain the cross-section of the 11B(p,α0)8Be nuclear reaction at 170° scattering angle. The results show good agreementwith literature indicating that the quantification of boron in silicon can be achieved at 100 ppm level (high sensitivity) at LAMFI-IFUSP with about 16% uncertainty. Increasing the detection solid angle and the collected beam charge, can reduce the detection limit to less than 100 ppm meeting present technological needs.

  19. 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.

  20. SU-D-304-07: Application of Proton Boron Fusion Reaction to Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Jung, J; Yoon, D; Shin, H; Kim, M; Suh, T [The Catholic University Seoul (Korea, Republic of)

    2015-06-15

    Purpose: we present the introduction of a therapy method using the proton boron fusion reaction. The purpose of this study is to verify the theoretical validity of proton boron fusion therapy using Monte Carlo simulations. Methods: 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 (PBFT) was verified using Monte Carlo simulations. Results: 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 (BUR). In addition, the 719 keV prompt gamma ray peak produced by the proton boron fusion reaction was positively detected. Conclusion: 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.

  1. Boron exposure assessment using drinking water and urine in the North of Chile

    International Nuclear Information System (INIS)

    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−1, with a median value of 2.9 mg L−1, while concentrations of boron in bottled water varied from 0.01 to 12.2 mg L−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−1, with a median of 4.28 mg L−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.

  2. Determination of boron in nuclear materials at subppm levels by high pressure liquid chromatography (HPLC)

    International Nuclear Information System (INIS)

    Experiments were conducted for the determination of boron in U3O8 powder, aluminium metal and milliQ water using dynamically modified Reversed Phase High Pressure Liquid Chromatography (RP-HPLC) and using two precolumn chromogenic agents viz. chromotropic acid and curcumin for complexing boron. The complex was separated from the excess of reagent and determined by HPLC. When present in subppm levels, chromotropic acid was used successfully only for determination boron in water samples. For determination of boron at subppm levels in uranium and aluminium samples, curcumin was used as the precolumn chromogenic agent. The boron curcumin complex (rosocyanin) was formed after extraction of boron with 2-ethyl-l, 3-hexane diol (EHD). The rosocyanin complex was then separated from excess curcumin by displacement chromatography. Linear calibration curves for boron amounts in the range of 0.02 μg to 0.5 μg were developed with correlation coefficients varying from 0.997 to 0.999 and were used for the determination of boron in aluminium and uranium samples. Precision of about 10% was achieved in samples containing less than 1 ppmw of boron. Detection limit of this method is 0.01 μg boron. (author)

  3. 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.

  4. 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.

  5. 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.

  6. 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.)

  7. 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.

  8. 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.

  9. 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

  10. Effect of pH on boron adsorption in some soils of Paraná, Brazil

    Directory of Open Access Journals (Sweden)

    Fábio Steiner

    2013-06-01

    Full Text Available Temporary B deficiency can be triggered by liming of acid soils because of increased B adsorption at higher soil pH. Plants respond directly to the activity of B in soil solution and only indirectly to B adsorbed on soil constituents. Because the range between deficient and toxic B concentration is relatively narrow, this poses difficulty in maintaining appropriate B levels in soil solution. Thus, knowledge of the chemical behavior of B in the soil is particularly important. The present study investigated the effect of soil pH on B adsorption in four soils of Paraná State, and to correlate these values with the physical and chemical properties of the soils. Surface samples were taken from a Rhodic Hapludox, Arenic Hapludalf, Arenic Hapludult, and one Typic Usthorthent. To evaluate the effect of pH on B adsorption, subsamples soil received the application of increasing rates of calcium carbonate. Boron adsorption was accomplished by shaking 2.0 g soil, for 24 h, with 20 mL of 0.01 mol L¹ NaCl solution containing different concentrations (0.0, 0.1, 0.2, 0.4, 0.8, 1.2, 1.6, 2.0, and 4.0 mg B L-1. Sorption was fitted to non-linear form of the Langmuir adsorption isotherm. Boron adsorption increased as concentration increased. Boron adsorption was dependent on soil pH, increasing as a function of pH in the range between 4.6 and 7.4, although the bonding energy has decreased. Maximum adsorption capacity (MAC of B was observed in the Arenic Hapludalf (49.8 mg B kg-1 soil followed by Arenic Hapludult (22.5 mg kg-1, Rhodic Hapludox (17.4 mg kg-1, and Typic Usthorthent (7.0 mg kg-1. The organic matter content, clay content, and aluminum oxide content (Al2O3 were the soils properties that affecting the B adsorption on Paraná soils.

  11. 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.

  12. 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

    International Nuclear Information System (INIS)

    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. - Highlights: • We performed experimental boron biodistribution studies for lung metastases. • 3 protocols employing BPA and GB-10 would be therapeutically useful. • BNCT at RA-3 would be potentially therapeutic for experimental lung metastases

  13. 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.

  14. 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. PMID:27530734

  15. 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.

  16. Trace Analysis of Boron in Nuclear Graphite by Means of Gas Chromatography

    International Nuclear Information System (INIS)

    No literature is available about the application of gas chromatography in trace analysis of boron in graphite. The following methods of transformation of boron into its volatile compounds are discussed: (a) Ignition of graphite in a stream of oxygen and subsequent transformation of boron oxide into volatile methyl borate which is then analysed on a Dilkens Aerograph H Model 96 gas chromatograph with silicone column and hydrogen as carrier (concentration method). (b) Extraction of boron from the graphite by means of sodium fluoride at 2800oC with simultaneous chlorination and trapping of boron trichloride, which is then analysed (direct method). A home-made gas chromatograph with a thermal conductivity detector and nitrogen as a carrier was used. The column was made of glass with a 20% (wt./wt.) fluorocarbon oil on kieselguhr. Special precautions were taken on account of the sensitivity of boron trichloride to moisture. (author)

  17. 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

  18. B28: the smallest all-boron cage from an ab initio global search

    Science.gov (United States)

    Zhao, Jijun; Huang, Xiaoming; Shi, Ruili; Liu, Hongsheng; Su, Yan; King, R. Bruce

    2015-09-01

    Our ab initio global searches reveal the lowest-energy cage for B28, which is built from two B12 units and prevails over the competing structural isomers such as planar, bowl, and tube. This smallest boron cage extends the scope of all-boron fullerene and provides a new structural motif of boron clusters and nanostructures.Our ab initio global searches reveal the lowest-energy cage for B28, which is built from two B12 units and prevails over the competing structural isomers such as planar, bowl, and tube. This smallest boron cage extends the scope of all-boron fullerene and provides a new structural motif of boron clusters and nanostructures. Electronic supplementary information (ESI) available: Planar isomer structures of B28 and spatial distributions of front molecular orbitals. See DOI: 10.1039/c5nr04034e

  19. 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.

  20. Effect of boron on creep characteristics in 9Cr-1.5Mo alloys

    Science.gov (United States)

    Kim, Bumjoon; Yun, Haksu; Lee, Dongbok; Lim, Byeongsoo

    2009-01-01

    For thick-section components such as headers and pipes of the power plants, high creep rupture strength and oxidation resistance are required. It is known that the addition of boron can improve the creep strength and oxidation resistance through the stabilization of M23C6 carbides in the vicinity of prior austenite grain boundaries. In this study, the effect of boron addition with the range of 0.0033~0.0133 wt% on the creep behavior of 9Cr-1.5Mo steel was investigated. Small punch creep tests were carried out to investigate the effect of boron addition on creep properties. Microstructure observation was performed to analyze the effect of boron addition on creep strength and rupture life. Also, the relationship between the minimum creep rate and the amount of boron addition were analyzed. The addition of boron is beneficial in lowering the steady-state creep rate.