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Sample records for boron 7

  1. 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.

  2. Boron

    International Nuclear Information System (INIS)

    The trace element boron (B) is of interest in reclamation situations for several reasons. It plays an essential through largely unidentified role in the growth of higher plants. In argronomic situations B deficiencies are common, and deficiencies in reclamation situations have been suggested but not documented. Among micronutrients, B is unique because the range from deficient concentrations to toxic concentrations either in the soil solution or in plant tissue is narrower than for any other micronutrient. In reclamation situations excessive amounts of B can occur in the soil or in near-surface mining wastes and thus interfere with reclamation objectives, especially in arid and semiarid regions. Also, B is mobile and appears subject to both upward transport (and possible contamination of overlying material) and downward transport (and possible contamination of surface water and groundwater)

  3. Surface analysis of VPS-W coatings boronized by an ICRF discharge in HT-7

    Energy Technology Data Exchange (ETDEWEB)

    Yang Zhongshi, E-mail: zsyang@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, PO. Box 1126, Hefei 230031 (China); Wang Wanjing [Institute of Plasma Physics, Chinese Academy of Sciences, PO. Box 1126, Hefei 230031 (China); Radiosicence Research Laboratory, Shizuoka University, 836 Oya, Shizuoka 422-8529 (Japan); Li Qiang; Wu Jing [Institute of Plasma Physics, Chinese Academy of Sciences, PO. Box 1126, Hefei 230031 (China); Okuno, Kenji; Oya, Yasuhisa [Radiosicence Research Laboratory, Shizuoka University, 836 Oya, Shizuoka 422-8529 (Japan); Luo Guangnan, E-mail: gnluo@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, PO. Box 1126, Hefei 230031 (China)

    2011-10-01

    To understand the surface compositions and the hydrogen isotope behavior in boronized Vacuum plasma spraying (VPS)-W, the boron coating has been achieved by means of Ion Cyclotron Radio Frequency (ICRF) boronization using carborane (C{sub 2}B{sub 10}H{sub 12}) powder as the precursor material in HT-7. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were used to observe the morphology of the VPS-W and boronized W surfaces. The X-ray Photoelectron Spectroscopy (XPS) of W-4f, O-1s, C-1s and B-1s on the VPS-W sample before and after boronization and after plasma exposure have been measured. The B-B and B-C bonds were observed after boronization treatment for VPS-W. Thermal Desorption Spectroscopy (TDS) experiments were also carried out to investigate the thermal desorption behavior of D implanted into the samples. After HT-7 plasma exposure, the desorption spectrum had a low temperature peak associated with trapping in intrinsic defects in polycrystalline W and a high temperature peak associated with B-O-D and B-C-D bonds.

  4. Halo effective field theory constrains the solar Beryllium-7 + proton -> Boron-8 + photon rate

    CERN Document Server

    Zhang, Xilin; Phillips, D R

    2015-01-01

    We report an improved low-energy extrapolation of the cross section for the process Beryllium-7+proton -> Boron-8+photon, which determines the Boron-8 neutrino flux from the Sun. Our extrapolant is derived from Halo Effective Field Theory (EFT) at next-to-leading order. We apply Bayesian methods to determine the EFT parameters and the low-energy S-factor, using measured cross sections and scattering lengths as inputs. Asymptotic normalization coefficients of Boron-8 are tightly constrained by existing radiative capture data, and contributions to the cross section beyond external direct capture are detected in the data at E < 0.5 MeV. Most importantly, the S-factor at zero energy is constrained to be S(0)= 21.3 + - 0.7 eV b, which is an uncertainty smaller by a factor of two than previously recommended. That recommendation was based on the full range for S(0) obtained among a discrete set of models judged to be reasonable. In contrast, Halo EFT subsumes all models into a controlled low-energy approximant, w...

  5. Determination of degradation constants of energetic 7*Li ion in liquid media using a thin boron film on silicon wafer

    International Nuclear Information System (INIS)

    A novel method to determine degradation constants has been developed for energetic 7*Li ions produced from the 10B (n, α) 7*Li reaction, moving in liquid media. The energetic 7*Li generated in a thin boron film on silicon wafer plunged into a liquid sample in which the wafer was immersed. The degradation constants were determined by analyzing the Doppler-broadened lineshapes of prompt γ-ray at 478 keV emitted from 7*Li. For comparison, degradation constants were also measured for solutions of boron compounds. Values obtained by the two methods gave fair agreement. (author)

  6. Metallic Borides, La2Re3B7 and La3Re2B5, Featuring Extensive Boron-Boron Bonding.

    Science.gov (United States)

    Bugaris, Daniel E; Malliakas, Christos D; Chung, Duck Young; Kanatzidis, Mercouri G

    2016-02-15

    La2Re3B7 and La3Re2B5 have been synthesized in single-crystalline form from a molten La/Ni eutectic at 1000 °C in the first example of the flux crystal growth of ternary rare-earth rhenium borides. Both compounds crystallize in their own orthorhombic structure types, with La2Re3B7 (space group Pcca) having lattice parameters a = 7.657(2) Å, b = 6.755(1) Å, and c = 11.617(2) Å, and La3Re2B5 (space group Pmma) having lattice parameters a = 10.809(2) Å, b = 5.287(1) Å, and c = 5.747(1) Å. The compounds possess three-dimensional framework structures that are built up from rhenium boride polyhedra and boron-boron bonding. La3Re2B5 features fairly common B2 dumbbells, whereas La2Re3B7 has unique one-dimensional subunits composed of alternating triangular B3 and trans-B4 zigzag chain fragments. Also observed in La3Re2B5 is an unusual coordination of B by an octahedron of La atoms. Electronic band structure calculations predict that La2Re3B7 is a semimetal, which is observed in the electrical resistivity data as measured on single crystals, with behavior obeying the Bloch-Grüneisen model and a room-temperature resistivity ρ300 K of ∼375 μΩ cm. The electronic band structure calculations also suggest that La3Re2B5 is a regular metal. PMID:26812202

  7. Scoping Test on the Effects of Boron and Buffer in the Mockup PLUS7 Fuel Assembly of the APR1400

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Jeong Kwan; Kwon, Sun Guk; Kim, Jae Won; Lee, Jae Yong [KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    Test results of the repeatability and the boron/buffer effects are presented, and compared with the acceptance basis for the LTCC of the APR1400. To address GSI-191 of the APR1400, we have performed a series of FA tests using a mockup PLUS7. The test results of repeatability performed at limiting conditions meet the acceptance basis compared with the reference results (SK34-61∼64) within 7% difference. Boron and buffer in the fluid lowered pressure drop across the entire FA compared with the condition without them. The test results of boron and buffer effects meet the acceptance head loss (91.8 kPa) of the APR1400 with a sufficient margin. To address U. S. Nuclear Regulatory Commission (NRC) Generic Safety Issue (GSI)-191, we have performed a series of fuel assembly (FA) head loss tests. The goal of this test is to confirm that there is sufficient available head when the debris reaches the core inlets of the APR1400 during a loss-of-coolant accident (LOCA), and that the long-term core cooling (LTCC) is not impeded. To move forward with the resolution of GSI-191 in-vessel effects, we have performed a scoping test on the effects of boron and buffer at ambient temperature. In test SK34-205, repeatability of the tests was confirmed at the limiting conditions. In a scoping test SK34-245, boron and Tri-Sodium Phosphate (TSP) buffer were added prior to the debris addition.

  8. Face-capping μ3-BO in B6(BO)7-: boron oxide analogue of B6H7- with rhombic 4c-2e bonds.

    Science.gov (United States)

    Guo, Jin-Chang; Lu, Hai-Gang; Zhai, Hua-Jin; Li, Si-Dian

    2013-11-14

    Using the first-principle approaches, we predict a B6(BO)7(-) cluster with a face-capping μ(3)-BO, which is the boron oxide analogue of closo-B6H7(-) with a face-capping μ(3)-H. Detailed topological analysis of electron density clearly reveals the existence of three rhombic 4c-2e bonds around the B/H apex in both C3v B6(BO)7(-) and C3v B6H7(-), which possesses similar electron densities at their bond and ring critical points. The adaptive natural density partitioning (AdNDP) analysis provides a direct and visual picture of the B-B-B-B/H 4c-2e bonds for the first time. Adiabatic and vertical electron detachment energies of the concerned monoanions are calculated to facilitate their future photoelectron spectroscopy measurements and characterizations. The presence of the B6(BO)7(-) and B6H7(-) clusters extends the BO/H isolobal analogy to the whole μ(n)-BO/H series (n = 1, 2, and 3) and enriches the chemistry of boronyl. PMID:24147988

  9. Manufacturing of thin films of boron for the measurement of the {sup 10}B(n, {alpha}){sup 7} Li reaction used in BNCT

    Energy Technology Data Exchange (ETDEWEB)

    Smilgys, Barbara; Oliveira, Sandro Guedes de; Hadler Neto, Julio Cesar; Vellame, Igor Alencar [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Inst. de Fisica Gleb Wataghin; Soares, Cleber Jose; Salim, Leonardo Alfredo [Universidade Estadual Paulista (UNESP), Rio Claro, SP (Brazil). Inst. de Geociencias e Ciencias Exatas; Coelho, Paulo Rogerio Pinto [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Engenharia Nuclear

    2011-07-01

    Full text: The Boron Neutron Capture Therapy (BNCT) is considered to be a possible treatment for different types of aggressive cancers located in areas of difficult access or which already have metastasis. The working principle of this therapy is the selective delivery of a greater amount of boron to the tumor cells than to the healthy ones, followed by the neutron irradiation that will induce the emission of {alpha} particles through the {sup 10}B(n, {alpha}){sup 7} Li reaction used in BNCT reaction. The high energy deposition of the product particles causes the death of the cells and this therapy becomes much effective if the healthy tissue is less exposed to this radiation. The objective of this work is to develop a method for measuring the rate of this reaction by using thin films of boron. We have manufactured thin films with different concentrations of boron deposited on mica and the thin films were exposed to different irradiation time intervals at the reactor IEA-R1 located at IPEN, Sao Paulo. Here we show our first results on the density and uniformity of the thin films, where the detection of the particles is made using plastic track detectors (CR-39) which have their structures damaged by the passage of ions. (author)

  10. How well do we understand Beryllium-7 + proton -> Boron-8 + photon? An Effective Field Theory perspective

    CERN Document Server

    Zhang, Xilin; Phillips, D R

    2015-01-01

    We have studied the 7Be(p,photon)8B reaction in the Halo effective field theory (EFT) framework. The leading order (LO) results were published in Phys.Rev.C89,051602(2014) after the isospin mirror process, 7Li(n,photon)8Li, was addressed in Phys.Rev.C89,024613(2014). In both calculations, one key step was using the final shallow bound state asymptotic normalization coefficients (ANCs) computed by ab initio methods to fix the EFT couplings. Recently we have developed the next-to-LO (NLO) formalism (to appear soon), which could reproduce other model results by no worse than 1% when the 7Be-p energy was between 0 and 0.5 MeV. In our recent report (arXiv:1507.07239), a different approach from that in Phys.Rev.C89,051602(2014) was used. We applied Bayesian analysis to constrain all the NLO-EFT parameters based on measured S-factors, and found tight constraints on the S-factor at solar energies. Our S(E=0 MeV)= 21.3 + - 0.7 eV b. The uncertainty is half of that previously recommended. In this proceeding, we provide...

  11. 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.

  12. Electroextraction of boron from boron carbide scrap

    International Nuclear Information System (INIS)

    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 (10B > 20 at. %) from boron carbide scrap generated during the production of boron carbide. - Highlights: • Recovery of 10B from nuclear grade boron carbide scrap • Development of process flow sheet • Physicochemical characterization of electroextracted boron • Microscopic examination of electroextracted boron

  13. Implementation of control rod movement and boron injection options by using control variables in RELAP5/PARCS v2.7 coupled code

    International Nuclear Information System (INIS)

    To efficiently characterize realistic transients, as the Reactivity Insertion Accidents (RIA), using coupled neutronic-thermal-hydraulic 3D best estimate system codes, like RELAP5/PARCS v2.7 coupled code, it is necessary to introduce some improvements in simulations by adding the capability of control rod movement and boron injection by means of RELAP5 control variables, with the aim of being able to analyze dynamically asymmetric transient accidents in a nuclear power reactor, like RIA, reproducing all control systems present in commercial reactors. In actual neutron kinetics codes, control rods banks do not have the possibility of dynamic movement during the simulation of a transient; besides it is necessary to send the boron concentration from the thermal-hydraulic code to the neutronic code to account for changes in cross-sections due to boron dilution. For instance, control rod movements are pre-programmed with simple instructions introduced before the beginning of the calculation. Hence, control rod positions are not related to the core characteristics and the control systems at any time of the simulation. This work presents the changes introduced in RELAP5/PARCS v2.7 codes to achieve that control rods and the boron injection become more dynamic and realistic components in such kind of simulators. With these modifications, control rods can be moved automatically, activated by the RELAP code control system, and also they can depend on signals related to the reactor activity, like pressure, fuel temperature or moderator temperature, etc., improving the realism of the calculation and widening the simulation possibilities. RELAP5 calculates the boron concentration in each node of the channels representing the reactor core, sending this information to the PARCS neutronic code. The environment of work chosen have been the graphical environment of programming Compaq Visual Fortran 6.6A (CVF 6.6A). The fundamental reasons have been, on the one hand the facility of

  14. Macropolyhedral boron-containing cluster chemistry. The reversible disassembly and reassembly of the hexagonal pyramidal {B7} feature in the [S2B18H19]- anion.

    Science.gov (United States)

    Ormsby, Daniel L; Greatrex, Robert; Kennedy, John D

    2008-03-28

    The [S(2)B(18)H(19)](-) anion 1, from syn-B(18)H(22) 2 with NaH and elemental sulfur, has an unusual arachno-type eleven-vertex {SB(10)} subcluster that has an open hexagonal pyramidal {B(7)} structural feature. This is conjoined, with two boron atoms in common, to a second {SB(10)} subcluster of conventional nido eleven-vertex geometry. Protonation of 1 forms neutral [S(2)B(18)H(20)] 4. Subsequent deprotonation of 4 yields the fluxional [S(2)B(18)H(19)](-) anion 5, which is isomeric with 1. Neutral 4and anion 5 do not have the {B(7)} hexagonal pyramidal feature. Neutral 4 consists of conventional nido eleven-vertex {SB(10)} and arachno ten-vertex {SB(9)} subclusters conjoined with a single spiro boron atom in common. Anion 5 is closely related to 4, but with an additional inter-boron intercluster link. Anion 5 spontaneously reverts to anion 1 over a few hours at room temperature, remarkable in that the open {B(7)} hexagonal pyramid is regenerated. DFT B3LYP/6-31G* calculations suggest definitive structures for 4 and 5 that are substantiated by agreement between observed NMR delta((11)B) values and boron nuclear shielding as calculated by the GIAO approach on the DFT-calculated structures. Extension of this approach additionally defines transition states and intermediates for the fluxionality of 5, and also for the reassembly of the starting anion 1, together with its {B(7)} feature, from fluxional 5. The fluxionality of 5 involves the inter-subcluster transfer of a {BH} unit. The reassembly of 1 from 5 involves a DSD rearrangement and two successive hydrogen-atom hops. Confidence in the application of this method to these large macropolyhedral assemblies is afforded in the first instance by good agreement between delta((11)B)(OBS) and delta((11)B)(CALC) for the structurally characterised original anion 1, the only species amongst these to be crystallographically established. PMID:18335146

  15. Determination of boron range distribution in ion-implanted silicon by the 10B(n, α) 7Li reaction

    International Nuclear Information System (INIS)

    A measuring technique based on the alpha particles being released by the 10B(n, α) nuclear reaction and using the time-of-flight technique at a periodically pulsing reactor was developed. Nondestructive determinations for the range distribution of boron impurities in ion-implanted silicon have been performed. In a silicon sample of 1016 atoms/cm2 concentration, irradiated with a neutron beam of 106ncm-2sec-1 flux, the range of the B+ ions could be determined up to an accuracy of +-200 A, which is higher than the accuracy of the electric measurements. Projected ranges obtained in the energy region 20-80 keV are compared with calculated results and other experiments. Examples are shown for some typical boron distributions before and after annealing the sample. The depth resolution permits the study of the mechanism of diffusion in silicon. (T.G.)

  16. Effect of boron additions on phase formation and magnetic properties of TbCu7-type melt spun SmFe ribbons

    Science.gov (United States)

    Zheng, Chuanjiang; Yu, Dunbo; Li, Kuoshe; Luo, Yang; Jin, Jinling; Lu, Shuo; Li, Hongwei; Mao, Yongjun; Quan, Ningtao

    2016-08-01

    Melt spun ribbons of a series of SmFe12Bx (x=0.0, 0.5, 0.75, 1.0, 1.25, and 1.5) have been prepared by the melt spinning technique. Sm-Fe-B melt spun ribbons with single phase TbCu7-type structure were prepared from the SmFe12Bx (x=0.5, 0.75, and 1.0) alloys at the surface velocity around 40 m/s. The addition of boron not only inhibits the appearance of soft magnetic phase α-Fe, but also enhances the ability of amorphous formation for melt spun Sm-Fe ribbons. The concentration of boron atoms, however, exceeds the limit of the solubility (x>1.0) of Sm-Fe alloys, which does not impede the appearance of α-Fe but accelerates the formation of metastable phase Sm2Fe23B3 that is unfavorable to their magnetic properties. Moreover, it is found that the addition of boron whose concentration is 0.0≤x≤0.75 can stabilize the metastable TbCu7-type structure because of the increase of the lattice parameter ratio c/a. The magnetic properties of as-annealed SmFe12B1.0 melt spun ribbons with an energy product of 2.19MGOe, a coercivity of 2.36 kOe and a remanence of 4.8 kGs have been achieved. The microstructural characteristics of as-annealed melt spun SmFe12 and SmFe12B1.0 ribbons have been discussed as well. The following sequence of the hyperfine field H(6l)boron content is added gradually, the hyperfine fields of 3g and 6l sites increase slightly due to the competition of the positive electron polarization and the negative polarization. However, the value of H(2e) is almost constant.

  17. Determination of boron content in boron carbide, boron nitride and amorphous boron

    International Nuclear Information System (INIS)

    In the present article an analyzing method of determination of boron content in boron carbide, boron nitride and amorphous boron described. Examined samples were digested with potassium hydroxide and potassium nitrate in nickel crucible and the boron contents determined subsequently by an alcalimetric titration of boric acid in presence of mannite resp. sorbite. (author)

  18. Possible toxicity of boron on sugar cane

    Energy Technology Data Exchange (ETDEWEB)

    Bravo C., M.

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

  19. 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.

  20. Elementary boron and metal-boron compounds

    International Nuclear Information System (INIS)

    Elementary boron is of interest for its peculiar and difficult bonding behaviour in solids. Due to its high oxygen affinity we find no elementary boron in nature. For the same reason it is difficult to isolate pure, elementary boron, and much confusion about 'boron crystals' has been the result of more than 100 years of research. The polymorphic forms of elementary boron and its closely related higher carbides and higher metal borides as well as the simple metal borides, B3C and BN are reported. The quantum-mechanical background responsible for structure and stoichiometry of these crystals is given. (orig.)

  1. Proceedings of workshop on 'Boron Chemistry and Boron Neutron Capture Therapy'

    International Nuclear Information System (INIS)

    This volume contains the proceedings of the 3rd Workshop on 'the Boron Chemistry and Boron Neutron Capture Therapy' held on February 12, in 1991. In this workshop, our attention was focused on the chemical nature of boron compounds and the boron neutron capture therapy (BNCT). First, clinical experiences of BNCT in KURRI in 1990 and 1991 were reported (Chap. 3). The feasibility of the gadolinium neutron capture therapy for brain tumors was discussed (Chap. 4). In the chemical field, a rapid spectrophotometric determination of trace amounts of borons in biological samples is described (Chap. 5). The chemical behaviours of p-boronophenylalanine and its analogs in aqueous solutions were investigated by a paper electrophoresis and infrared spectroscopy (Chap. 6). On the molecular design and synthesis of new boron carriers for BNCT, several new synthetic methods for B-10 containing nucleoside derivatives were shown (Chap. 7). (author)

  2. 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.

  3. Analysis of the electron density features of small boron clusters and the effects of doping with C, P, Al, Si, and Zn: Magic B7P and B8Si clusters

    Science.gov (United States)

    Saha, P.; Rahane, A. B.; Kumar, V.; Sukumar, N.

    2016-05-01

    Boron atomic clusters show several interesting and unusual size-dependent features due to the small covalent radius, electron deficiency, and higher coordination number of boron as compared to carbon. These include aromaticity and a diverse array of structures such as quasi-planar, ring or tubular shaped, and fullerene-like. In the present work, we have analyzed features of the computed electron density distributions of small boron clusters having up to 11 boron atoms, and investigated the effect of doping with C, P, Al, Si, and Zn atoms on their structural and physical properties, in order to understand the bonding characteristics and discern trends in bonding and stability. We find that in general there are covalent bonds as well as delocalized charge distribution in these clusters. We associate the strong stability of some of these planar/quasiplanar disc-type clusters with the electronic shell closing with effectively twelve delocalized valence electrons using a disc-shaped jellium model. {{{{B}}}9}-, B10, B7P, and B8Si, in particular, are found to be exceptional with very large gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital, and these are suggested to be magic clusters.

  4. Sputtering behavior of boron and boron carbide

    International Nuclear Information System (INIS)

    Sputtering yields of boron were measured with D+ and B+ ions for normal and oblique angles of incidence. Self-sputtering data of boron carbide were simulated in the experiment by using Ne+ ions. The energies of the impinging ions were between 20 eV and 10 keV. The measured data are compared with computer simulated values calculated with the TRIMSP program. The boron data for normal ion impact are higher than the calculated values, whereas those for oblique ion incidence are smaller than the calculation predicts. This discrepancy is explained by the surface roughness and supported by SEM micrographs. The comparison of the boron carbide data with TRIMSP calculations shows much better agreement than the boron data. In this case the target surface was much smoother. (orig.)

  5. 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.

  6. The Bo1-specific PCR marker AWW5L7 is predictive of boron tolerance status in a range of exotic durum and bread wheats.

    Science.gov (United States)

    Schnurbusch, Thorsten; Langridge, Peter; Sutton, Tim

    2008-12-01

    High soil boron (B) constitutes a major soil problem in many parts of the world, particularly in low-rainfall areas and land under irrigation. Low accumulation of B in the shoot or grain of cereal crops is correlated with the maintenance of biomass production and grain yield under high B conditions, suggesting that this trait is an important component of field tolerance. A novel screening protocol to measure B accumulation in aerated and supported hydroponics was validated using a set of known and exotic bread wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum L. subsp. durum (Desf.) Husn.) accessions. Furthermore, B accumulation in two Triticum urartu Tumanian ex Gandilyan and 54 Triticum monococcum L. accessions was measured and showed considerable phenotypic variation. However, B accumulation in these lines was higher than that observed in the most tolerant durum or bread wheats. Mapping of high B tolerance in the durum population AUS14010/Yallaroi revealed a locus possibly allelic to Bo1, a major source of B toxicity tolerance previously identified in bread wheat. Here, we show that the Bo1-specific codominant PCR marker AWW5L7 is predictive of B tolerance status among exotic durum and bread wheat accessions. All tolerant durum accessions assayed carried very similar AWW5L7 marker fragments, indicating wide distribution of this allele among tolerant durum wheats. Three bread wheat accessions had tolerance that was independent of Bo1 and is probably located on chromosome 4A. These lines represent a valuable genetic resource for B toxicity tolerance breeding in wheat. PMID:19088810

  7. Mass spectrometric determination of boron isotope in boron carbide

    International Nuclear Information System (INIS)

    Boron isotopes in boron carbide are measured by thermionic ionization mass spectrometry with no prior chemical separation. Boron is converted to sodium borate by fusion of the boron carbide with sodium hydroxide (or sodium carbonate) directly on the rhenium filament. The boron isotopic ratios are measured by using the Na2BO2+ ion

  8. 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.

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

    International Nuclear Information System (INIS)

    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

  10. 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.

  11. Inefficiency of high boron concentrations for cell killing in boron neutron capture therapy

    International Nuclear Information System (INIS)

    This study is to investigate the relationship between the cell-killing effect of the 10B(n, α)7Li capture reaction, intracellular boron concentration, and thermal neutron fluence in boron neutron capture therapy using in vitro cell survival based on a clonogenic assay, and biophysical analysis. Our results showed that the cell-killing yield of the 10B(n, α)7Li capture reaction per unit thermal neutron fluence declined with an increase in the intracellular boron concentration above 45 μg/ml 10B. The cell-killing effect was well described using an empirical power function of the intracellular boron concentration, with exponent 0.443. Knowledge of this effect will help in the optimization of BNCT. (author)

  12. 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.))

  13. Determination of boron and silicon in boron carbide

    International Nuclear Information System (INIS)

    A sodium carbonate fusion technique for the dissolution of boron carbide followed by the determination of boron by alkalimetric titration and silicon impurity by spectrophotometry is described. The elemental boron content in the commercially available boron carbide ranged from 77.2 to 77.60 % and the silicon in the range 1170 to 2500 ppm. (author)

  14. 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

  15. 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)

  16. 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.

  17. 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.

  18. Differentiation in boron distribution in adult male and female rats' normal brain: A BNCT approach

    International Nuclear Information System (INIS)

    Boron distribution in adult male and female rats' normal brain after boron carrier injection (0.005 g Boric Acid+0.005 g Borax+10 ml distilled water, pH: 7.4) was studied in this research. Coronal sections of control and trial animal tissue samples were irradiated with thermal neutrons. Using alpha autoradiography, significant differences in boron concentration were seen in forebrain, midbrain and hindbrain sections of male and female animal groups with the highest value, four hours after boron compound injection. - Highlights: ► Boron distribution in male and female rats' normal brain was studied in this research. ► Coronal sections of animal tissue samples were irradiated with thermal neutrons. ► Alpha and Lithium tracks were counted using alpha autoradiography. ► Different boron concentration was seen in brain sections of male and female rats. ► The highest boron concentration was seen in 4 h after boron compound injection.

  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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-02-16

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

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

    International Nuclear Information System (INIS)

    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

  2. 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.

  3. Boron nitride nanosheets reinforced glass matrix composites

    Czech Academy of Sciences Publication Activity Database

    Saggar, Richa; Porwal, H.; Tatarko, P.; Dlouhý, Ivo; Reece, M. J.

    2015-01-01

    Roč. 114, SEP (2015), S26-S32. ISSN 1743-6753 R&D Projects: GA MŠk(CZ) 7AMB14SK155 EU Projects: European Commission(XE) 264526 Institutional support: RVO:68081723 Keywords : Boron nitride nanosheets * Borosilicate glass * Mechanical properties Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.163, year: 2014

  4. 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.

  5. 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.

  6. Enhanced surface hardness by boron implantation in Nitinol alloy.

    Science.gov (United States)

    Lee, D H; Park, B; Saxena, A; Serene, T P

    1996-10-01

    Boron implantation into Nitinol alloy has a potential for developing improved Nitinol root canal instruments with excellent cutting properties, without affecting their superelastic bulk-mechanical properties. The surface hardness of nickel-titanium (NiTi) alloy, also known as "Nitinol" (50 atm% nickel+50 atm% titanium), has been improved by ion-beam surface modification. With an implantation dose of 4.8 x 10(17) boron/cm2, a high concentration of boron (30 atm%) is incorporated into NiTi alloy by 110 keV boron ions at room temperature (25 degrees C). Boron-implanted and unimplanted (pure) Nitinol alloys show surface hardness of 7.6 +/- 0.2 and 3.2 +/- 0.2 GPa, respectively, at the nanoindentation depth of 0.05 micron. The ion-beam-modified NiTi alloy exceeds the surface hardness of stainless steel. PMID:9198443

  7. 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)

  8. 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.

  9. Development of cancer therapy facility of HANARO and medical research in BNCT; development of the technique for boron concentration analysis

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hee Dong; Byun, Soo Hyun; Sun, Gwang Min; Kim, Suk Kwon; Kim, In Jung; Park, Chang Su [Seoul National University, Seoul (Korea)

    2002-03-01

    Objective and Necessity of the Project- Development of a boron concentration analysis facility used for BNCT. - Development of the technique for boron concentration analysis. Contents and Scopes of the Project - Construction of the boron concentration analysis facility based on PGAA. Estimation of the neutron beam characteristics. -Establishment of the technique for the boron concentration analysis. - Estimation of the reliability for the boron analysis. Results of the Project -Installation of the boron concentration analysis facility at Hanaro. - Neutron beam characteristics are the sample position (neutron flux : 7.9 x 10{sup 7} n/cm{sup 2}s, Cd-ratio : 266) Technique for the boron concentration analysis. - Boron detection sensitivity and limit (detection sensitivity : 2, 131 cps/mg-B, detection limit : 67 ng for 10,000 sec). 63 refs., 37 figs., 13 tabs. (Author)

  10. Magnetron sputter deposition of boron and boron carbide

    International Nuclear Information System (INIS)

    The fabrication of X-ray optical coatings with greater reflectivity required the development of sputter deposition processes for boron and boron carbide. The use of high density boron and boron carbide (B4C) and a vacuum-brazed target design was required to achieve the required sputter process stability and resistance to the thermal stress created by high rate sputtering. Our results include a description of the target fabrication procedures and sputter process parameters necessary to fabricate B4C and boron modulated thin film structures. (orig.)

  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. 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

  13. Neutron capture radiography to determine the concentration of natural boron in leaves using the nuclear reaction 10B(n,α)7Li

    International Nuclear Information System (INIS)

    ) of these tracks are characteristic of the nuclides involved in the neutron induced nuclear reactions, thus rendering their discrimination possible. NCR is used in Costa Rica as a nuclear analytical technique to determine the boron concentration in vegetal samples, boron being a stable isotope whose concentration is difficult to evaluate by chemical methods

  14. Boron cures cancer

    International Nuclear Information System (INIS)

    In this work the authors cite a few examples of the use of radiopharmaceuticals for diagnostic and therapeutic purposes in nuclear medicine. They point to the possibility of boron neutron capture therapy and the use for the neutron capture therapy of other light elements.

  15. 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.

  16. The possibilities of applying marker assisted selection in breeding boron tolerant wheat

    Directory of Open Access Journals (Sweden)

    Brdar-Jokanović Milka

    2013-01-01

    Full Text Available The aim of this study was to investigate the possibilities of applying molecular markers-microsatellites in breeding boron tolerant wheat. The study comprised the investigation of allelic variability of sixty bread wheat accessions in two microsatellite loci (Xgwm46-7B and Xgwm577-7B for which was assumed that are placed near the 7B chromosome locus involved in the expression of boron tolerance in wheat. Phenotypic variability concerning boron tolerance was assessed via root length reduction of wheat seedlings grown in the presence of high external boron, applied as boric acid solution (concentrations 50, 100 and 150 mg/l, boron treatments B50, B100 and B150. The indication of marker-trait associations was determined by comparing the allelic variability in the two microsatellite loci with the phenotypic variability in boron tolerance. Nonparametric Kruskal-Wallis test was used for the comparisons. The indication of marker-trait association was found for both Xgwm46-7B and Xgwm577-7B; on B150 and B50 treatments, respectively. Allelic forms identified in Xgwm577-7B locus may be related to tolerance, medium tolerance and sensitivity to high boron. This was not the case for Xgwm46-7B, where the identified alleles were related only to boron tolerance and sensitivity. Therefore, Xgwm577-7B may be preferred over Xgwm46-7B when studying boron tolerance in wheat. However, a considerable portion of boron tolerant accessions carried different alleles in the investigated loci, implying boron tolerance as a quantitative trait with more than one chromosomal region involved in its expression. Therefore, the allelic variability of more than the analyzed two loci should be investigated. [Projekat Ministarstva nauke Republike Srbije, br. TR 31066

  17. Process for microwave sintering boron carbide

    International Nuclear Information System (INIS)

    A method of microwave sintering boron carbide comprises leaching boron carbide powder with an aqueous solution of nitric acid to form a leached boron carbide powder. The leached boron carbide powder is coated with a glassy carbon precursor to form a coated boron carbide powder. The coated boron carbide powder is consolidated in an enclosure of boron nitride particles coated with a layer of glassy carbon within a container for microwave heating to form an enclosed coated boron carbide powder. The enclosed coated boron carbide powder is sintered within the container for microwave heating with microwave energy

  18. 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.

  19. 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...

  20. 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.

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

    International Nuclear Information System (INIS)

    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/cm2, 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]=7.6x106x[OH]0.11x[CD]0.62x[IBC]-0.57x[DSE]-0.04x[T] -2.98x[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.

  2. 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.

  3. Boron content of the Freetown drinking water

    International Nuclear Information System (INIS)

    A method is described for the analyses of water samples in the Freetown area of Sierra Leone for their boron concentrations. The method involves alpha counting during thermal neutron irradiation of the samples utilising the 10Ba(n,α)7Li reaction. The alpha counting is via a liquid scintillator which also incorporates the water samples. A detailed outline of the experimental setup is given and the results obtained from measurement on water samples presented. (author)

  4. Experimental core electron density of cubic boron nitride

    DEFF Research Database (Denmark)

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

    boron nitride we may obtain a deeper understanding of the effect of bonding on the total density. We report here a thorough investigation of the charge density of cubic boron nitride with a detailed modelling of the inner atom charge density. By combining high resolution powder X-ray diffraction data...... has been obtained. The displacement parameters reported here are significantly lower than those previously reported, stressing the importance of an adequate description of the core density. The charge transfer from boron to nitrogen clearly affects the inner electron density, which is evident from...... theoretical as well as experimental result. The redistribution of electron density will, if not accounted for, result in increased thermal parameters. It is estimated that 1.7-2 electrons is transferred from boron to nitrogen. [1]: N. Bindzus, T. Straasø, N. Wahlberg, J. Becker, L. Bjerg, N. Lock, A...

  5. Corrosion resistance testing of high-boron-content stainless steels

    International Nuclear Information System (INIS)

    Boron steels, i.e. stainless steels with boron contents of 0.2 to 2.25 wt.%, are employed in nuclear engineering for the manufacture of baskets or wells in which radioactive fissile materials are stored, mostly spent nuclear fuel elements. The resistance of such steels to intergranular corrosion and uniform corrosion was examined in the Strauss solution and in boric acid; the dependence of the corrosion rate of the steels on their chemical composition was investigated, and their resistance was compared with that of AISI 304 type steel. Corrosion resistance tests in actual conditions of ''wet'' compact storage (demineralized water or a weak boric acid solution) gave evidence that boron steels undergo nearly no uniform corrosion and, as electrochemical measurements indicated, match standard corrosion-resistant steels. Corrosion resistance was confirmed to decrease slightly with increasing boron content and to increase somewhat with increasing molybdenum content. (Z.S.). 3 tabs., 4 figs., 7 refs

  6. 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)

  7. Thin boron nitride nanotubes formed during annealing in ammonia gas

    International Nuclear Information System (INIS)

    Full text: We present a mechano-thermal process to synthesis thin boron nitride nanotubes of diameter around 7 nanometers. They were produced by mechanical milling of amorphous boron powder at ambient temperature, followed by thermal annealing in ammonia gas. High energy ball milling creates a precursor containing a high density of nanocrystalline BN seeds and fine particles of metal catalyst. Nanotubes grow out from the milled boron powder during subsequent annealing. The novelty of this approach lies in the formation of the thin BN nanotubes by annealing in ammonia gas instead of nitrogen gas. The boron nitride nanotubes produced have a well-defined crystalline structure and there is no iron within them. If nitrogen gas is used, thicker nanotubes of diameter in the range of 20-100 nm were obtained and iron was more likely to be found inside the nanotubes. Copyright (2005) Australian Institute of Physics

  8. Electrodialysis of boron-containing solutions using homogeneuos ionite membranes

    International Nuclear Information System (INIS)

    Electrodialysis of boron-containing solutions is studied when preparing potable water from the sea one with the limiting admissible concentration (LAC) of boron 0.5 mg/dm3. It is ascertained that at pH>7 diffusion permeability of anion- and cation-exchange membranes as regards boron reduces both in the absence of external field and at current density 0.3 A/dm3. It is shown that when MK-100 homogeneous cationic membranes and MA-100 homogeneous anionic membranes are used, boron concentration in dialyzate decreases to LAC, if the process is realized in acid and low-acid media and if the depth of freshening increases to 0.2g/l

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

    Science.gov (United States)

    Rinaldo, Steven G.

    formation of boron nitride nanotubes (BNNTs). In Chapter 6, we look at various methods of producing BNNTs from boron droplets, and introduce a new method involving injection of boron powder into an induction furnace. In Chapter 7 we consider another useful process, where ammonia is reacted with boron vapor generated in situ, either through the reaction of boron with metal oxides or through the decomposition of metal borides.

  10. Sintered boron, production and properties

    International Nuclear Information System (INIS)

    Microhardness HV, tensile properties and Young modulus of sintered boron of different porosity were studied. It was shown that with density growth tensile properties improve. HV and brittle-ductile transition temperature Tsub(b) of sintered boron on the one hand and for silicon and titanium carbide on the other were compared and discussed. It was noted that the general level of HV and Tsub(b) for boron is rather high and at similar relative temperatures these characteristics are much higher. Temperature dependences of linear expansion coefficient, thermal capacity, thermal and temperature conductivity of sintered boron of 20% porosity were studied. Gruneisen parameter was evaluated

  11. Fivefold twinned boron carbide nanowires.

    Science.gov (United States)

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

    2009-09-01

    Chemical composition and crystal structure of fivefold twinned boron carbide nanowires have been determined by electron energy-loss spectroscopy and electron diffraction. The fivefold cyclic twinning relationship is confirmed by systematic axial rotation electron diffraction. Detailed chemical analysis reveals a carbon-rich boron carbide phase. Such boron carbide nanowires are potentially interesting because of their intrinsic hardness and high temperature thermoelectric property. Together with other boron-rich compounds, they may form a set of multiply twinned nanowire systems where the misfit strain could be continuously tuned to influence their mechanical properties. PMID:19687534

  12. Boron concentrations in brain during boron neutron capture therapy: in vivo measurements from the Phase I trial EORTC 11961 using a gamma-ray telescope

    International Nuclear Information System (INIS)

    Purpose: Gamma-ray spectroscopic scans to measure boron concentrations in the irradiated volume were performed during treatment of 5 patients suffering from brain tumors with boron neutron capture therapy (BNCT). In BNCT, the dose that is meant to be targeted primarily to the tumor is the dose coming from the reaction 10B(n,α)7Li, which is determined by the boron concentration in tissue and the thermal neutron fluence rate. The boron distribution throughout the head of the patient during the treatment is therefore of major interest. The detection of the boron distribution during the irradiation was until now not possible. Methods and Materials: Five patients suffering from glioblastoma multiforme and treated with BNCT in a dose escalation study were administered the boron compound, boron sulfhydryl (BSH; Na2B12H11SH). Boron concentrations were reconstructed from measurements performed with the gamma-ray telescope which detects locally the specific gamma rays produced by neutron capture in 10B and 1H. Results: For all patients, at a 10B concentration in blood of 30 ppm, the boron concentration in nonoperated areas of the brain was very low, between 1 and 2.5 ppm. In the target volume, which included the area where the tumor had been removed and where remaining tumor cells have to be assumed, much higher boron concentrations were measured with large variations from one patient to another. Superficial tissue contained a higher concentration of 10B than the nonoperated areas of the brain, ranging between 8 and 15 ppm. Conclusions: The measured results correspond with previous tissue uptake studies, confirming that normal brain tissue hardly absorbs the boron compound BSH. Gamma-ray telescope measurements seem to be a promising method to provide information on the biodistribution of boron during therapy. Furthermore, it also opens the possibility of in vivo dosimetry

  13. The effect of boron supplementation on lean body mass, plasma testosterone levels, and strength in male bodybuilders

    Science.gov (United States)

    Ferrando, A. A.; Green, N. R.

    1993-01-01

    The effect of boron supplementation was investigated in 19 male bodybuilders ages 20-27 years. Ten were given a 2.5-mg boron supplement while 9 were given a placebo every day for 7 weeks. Plasma total and free testosterone, plasma boron, lean body mass, and strength measurements were determined on Days 1 and 49 of the study. Plasma boron values were significantly (p bodybuilding can increase total testosterone, lean body mass, and strength in lesser trained bodybuilders, and that boron supplementation had no effect on these measures.

  14. 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

  15. High-power electron beam tests of a liquid-lithium target and characterization study of (7)Li(p,n) near-threshold neutrons for accelerator-based boron neutron capture therapy.

    Science.gov (United States)

    Halfon, S; Paul, M; Arenshtam, A; Berkovits, D; Cohen, D; Eliyahu, I; Kijel, D; Mardor, I; Silverman, I

    2014-06-01

    A compact Liquid-Lithium Target (LiLiT) was built and tested with a high-power electron gun at Soreq Nuclear Research Center (SNRC). The target is intended to demonstrate liquid-lithium target capabilities to constitute an accelerator-based intense neutron source for Boron Neutron Capture Therapy (BNCT) in hospitals. The lithium target will produce neutrons through the (7)Li(p,n)(7)Be reaction and it will overcome the major problem of removing the thermal power >5kW generated by high-intensity proton beams, necessary for sufficient therapeutic neutron flux. In preliminary experiments liquid lithium was flown through the target loop and generated a stable jet on the concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power densities of more than 4kW/cm(2) and volumetric power density around 2MW/cm(3) at a lithium flow of ~4m/s, while maintaining stable temperature and vacuum conditions. These power densities correspond to a narrow (σ=~2mm) 1.91MeV, 3mA proton beam. A high-intensity proton beam irradiation (1.91-2.5MeV, 2mA) is being commissioned at the SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator. In order to determine the conditions of LiLiT proton irradiation for BNCT and to tailor the neutron energy spectrum, a characterization of near threshold (~1.91MeV) (7)Li(p,n) neutrons is in progress based on Monte-Carlo (MCNP and Geant4) simulation and on low-intensity experiments with solid LiF targets. In-phantom dosimetry measurements are performed using special designed dosimeters based on CR-39 track detectors. PMID:24387907

  16. 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.

  17. 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)

  18. Design, synthesis and structure of new potential electrochemically active boronic acid-based glucose sensors

    DEFF Research Database (Denmark)

    Norrild, Jens Chr.; Søtofte, Inger

    2002-01-01

    In the course of our investigations on new boronic acid based carbohydrate sensors three new boronic acids 3, 7 and 11 containing a ferrocene moiety were synthesised. Their design includes an intramolecular B-N bonding motif in order to facilitate binding at physiological pH. We report...

  19. Boron thermal regeneration system

    International Nuclear Information System (INIS)

    An ion exchanger which allows flow in both directions along a selected flow path is described. A separator plate divides the exchanger tank into two chambers each of which has a flow conduit so that flow may enter or leave from either chamber while prohibiting the resin particles from migrating from one side of the tank to the other. This ion exchanger permits a dual-directional flow process to be practised which results in immediate changes in the boron concentration within a nuclear reactor coolant system even if the ion exchanger resins have not been completely equilibrated during a previous operation. (author)

  20. BORONIZING OF STEEL

    Directory of Open Access Journals (Sweden)

    Arzum ULUKÖY

    2006-02-01

    Full Text Available Boride layer has many advantages in comparison with traditional hardening methods. The boride layer has high hardening value and keeps it's hardeness at high temperatures, and it also shows favorible properties, such as the resistance to wear, oxidation and corrosion. The process can be applied at variety of materials, for instance steel, cast iron, cast steel, nickel and cobalt alloys and cermets. In this rewiew, boronizing process properties, boride layer on steel surfaces and specifications and the factors that effect boride layer are examined

  1. 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...

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

    Directory of Open Access Journals (Sweden)

    Azhar Abdul Halim

    2012-01-01

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

  3. 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...

  4. Spectrophotometric determination of boron by solvent extraction with 2-hydroxy-2-methylbutyric acid and malachite green

    International Nuclear Information System (INIS)

    A very simple and sensitive method for the spectrophotometric determination of boron was developed. Boron was found to react with 2-hydroxy-2-methylbutyric acid in weak acidic aqueous solution at room temperature to form a complex anion which can be extracted into chlorobenzene with malachite green in a single extraction; boron is determined indirectly by measuring the absorbance of malachite green in the extract at 629 nm. The calibration graph is linear over the range (7.50 x 10-7 - 2.00 x 10-5) mol dm-3 boron; the apparent molar absorptivity is 6.50 x 104 dm3 mol-1 cm-1. The method is applied to the determination of micro amounts of boron in natural waters with satisfactory results. (author)

  5. Lattice dynamics of α boron and of boron carbide

    International Nuclear Information System (INIS)

    The atomic structure and the lattice dynamics of α boron and of B4C 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 α 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 B4C. 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)

  6. 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

  7. 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.

  8. 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.

  9. 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).

  10. 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.

  11. Modelling structure and properties of amorphous silicon boron nitride ceramics

    OpenAIRE

    Johann Christian Schön; Alexander Hannemann; Guneet Sethi; Ilya Vladimirovich Pentin; Martin Jansen

    2011-01-01

    Silicon boron nitride is the parent compound of a new class of high-temperature stable amorphous ceramics constituted of silicon, boron, nitrogen, and carbon, featuring a set of properties that is without precedent, and represents a prototypical random network based on chemical bonds of predominantly covalent character. In contrast to many other amorphous materials of technological interest, a-Si3B3N7 is not produced via glass formation, i.e. by quenching from a melt, the reason being that th...

  12. 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.

  13. B4C solid target boronization of the MST reversed-field pinch

    International Nuclear Information System (INIS)

    A solid rod of hot-pressed boron carbide is being used as the source of boron during boronization of MST. The most striking result of this procedure is the reduction in oxygen contamination of the plasma (O III radiation, characteristic of oxygen at the edge, falls by about a factor of 3 after boronization.). The radiated power fraction drops to about half its initial value. Particle reflux from the wall is also lowered, making density control simpler. The rod (12.7 mm diameter) is inserted into the edge plasma of normal high-power RFP discharges. B4C is ablated from the surface of the rod and deposited in a thin film (a-B/C:H) on the walls and limiters. The energy flux carried by ''superthermal'' (not ''runaway'') electrons at the edge of MST appears to enhance the efficient, non-destructive ablation of the boron carbide rod

  14. Wettability of boron carbide

    International Nuclear Information System (INIS)

    The wettability of boron carbide has been examined by means of the sessile drop method, using the following candidate alloys: (96wt%AG-4wt%Ti), (Ag-26.5wt%Cu-3wt%Ti), (Sn-10wt%Ag-4wt%Ti), Sn(99.95wt%) and Al(99.99wt%). The results show that B4C is completely wetted by the Ag-based alloys. Sn-10wt%Ag-4wt%Ti alloy and pure Al partly wet the B4C surface, while pure Sn does not wet B4C at all. For all the alloys used, except pure Sn, a reaction layer was observed at the interface between the ceramic part and the metal drop. Although the spreading kinetics of the Al-drop was much slower compared with the Ti-containing alloys, the reaction rate was considerably higher in the former case. This suggests that aluminium is an attractive candidate material for brazing of B4C. Formation of the low melting B2O3 at the B4C surface may cause oxidation of the filler metal during joining, which, in turn, leads to a low bond strength

  15. Thermal conductivity of boron carbide-boron nitride composites

    International Nuclear Information System (INIS)

    This paper reports that because of their preferred orientation, the addition of boron nitride dispersions to hot-pressed boron carbide was found to result in a considerable degree of anisotropy in thermal conductivity of the resulting composite, indicated by an increase in the thermal conductivity perpendicular to the hot-pressing direction by as much as a factor of 3 at the highest boron nitride volume fractions of this study, and a decrease in the thermal conductivity parallel to the hot-pressing direction by as much as a factor of 2. The composite data were found to be below the values expected from composite theory, which may represent indirect evidence for the existence of an interfacial thermal barrier

  16. 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.

  17. 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.)

  18. 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.

  19. Boron carbide nanolumps on carbon nanotubes

    Science.gov (United States)

    Lao, J. Y.; Li, W. Z.; Wen, J. G.; Ren, Z. F.

    2002-01-01

    Boron carbide nanolumps are formed on the surface of multiwall carbon nanotubes by a solid-state reaction between boron and carbon nanotubes. The reaction is localized so that the integrity of the structure of carbon nanotubes is maintained. Inner layers of multiwall carbon nanotubes are also bonded to boron carbide nanolumps. These multiwall carbon nanotubes with boron carbide nanolumps are expected to be the ideal reinforcing fillers for high-performance composites because of the favorable morphology.

  20. 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

  1. NEW ADVANCES IN BORON SOIL CHEMISTRY

    Science.gov (United States)

    Boron is an essential micronutrient element required for plant growth. Boron deficiency is wide-spread in crop plants throughout the world especially in coarse-textured soils in humid areas. Boron toxicity can also occur, especially in arid regions under irrigation. Plants respond directly to the...

  2. 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.

  3. 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)

  4. Titanium effect on the microstructure and properties of laminated high boron steel plates

    Science.gov (United States)

    Yuan, Lin-lin; Han, Jing-tao; Liu, Jing; Wei, Dong-bin; Abathun, Mehari Zelalem

    2015-05-01

    High-boron steel is an important material used for thermal neutron shielding. The appropriate amount of added boron must be determined because excessive boron may deteriorate the steel's workability. A uniform microstructure can be formed by adding titanium to boron steel. In this study, casting and hot rolling were used to fabricate laminated high-boron steel plates whose cores contained 2.25wt% boron and 0wt%-7.9wt% titanium. The effects of titanium content and hot-rolling and heat-treatment processes on the microstructure and properties of the laminated plates were studied. The results indicated that the optimum titanium content was 5.7wt% when the boron content was 2.25wt%, and that the best overall properties were obtained after heat treatment at 1100°C for 4 h. The tensile strength, yield strength, and elongation at the specified temperature and holding time were as high as 526.88 MPa, 219.36 MPa, and 29%, respectively.

  5. The shocking development of lithium (and boron) in supernovae

    International Nuclear Information System (INIS)

    It is shown that significant amounts of Li-7 and B-11 are produced in Type 2 supernovae. The synthesis of these rare elements occurs as the supernova shock traverses the base of the hydrogen envelope burning He-3 to masses 7 and 11 via alpha capture. The yields in this process are sufficient to account for the difference in lithium abundance observed between Pop 2 and Pop 1 stars. Since lithium (and boron) would, in this manner, be created in the same stars that produce the bulk of the heavy elements, the lithium abundance even in old Pop 1 stars would be high (as observed). The B-11 production may remedy the long-standing problem of the traditional spallation scenario to account for the observed isotopic ratio of boron. Observational consequences of this mechanism are discussed, including the evolution of lithium and boron isotope ratios in the Galaxy and the possible use of the boron yields to constrain the number of blue progenitor Type 2 supernovae

  6. Boron steel. I Part. Preparation

    International Nuclear Information System (INIS)

    With the advent of the first nuclear reactors arise the need for control rods and shielding duties for some types of radiations. One of the materials used for this purpose has been the high boron steel. This paper describes the melting and casting procedures employed for the production, at laboratory scale, of steels with Boron content ranging from 1 to 4 per cent, as well as the metallographic and X-Ray techniques used for the identification of the present phases. The electrolytic technique employed for the isolation of the Fe2B phase and its subsequent X-Ray identification has proved to be satisfactory. (Author) 11 refs

  7. Shear amorphization of boron suboxide

    International Nuclear Information System (INIS)

    We report for the first time the shear-induced local amorphization of boron suboxide subjected to nanoindentation. The amorphous bands have a width of ∼1–3 nm and a length of 200–300 nm along the (01¯11) crystal plane. We show direct experimental evidence that the amorphous shear bands of boron suboxide are driven from the coalescence of dislocation loops under high shear stresses. These observations provide insights into the microscopic deformation and failure of high-strength and lightweight ceramics

  8. 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.

  9. 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.))

  10. Removal of boron from aqueous solution by using neutralized red mud

    International Nuclear Information System (INIS)

    The adsorptive removal of boron from aqueous solution by using the neutralized red mud was studied in batch equilibration technique. The effects of pH, adsorbent dosage, initial boron concentration and contact time on the adsorption were investigated. The experiments demonstrated that boron removal was of a little fluctuation in pH range of 2-7 and it takes 20 min to attain equilibrium. The adsorption data was analyzed using the Langmuir and the Freundlich isotherm models and it was found that the Freundlich isotherm model represented the measured sorption data well

  11. Boron-enhanced diffusion of boron from ultralow-energy boron implantation

    International Nuclear Information System (INIS)

    The authors have investigated the diffusion enhancement mechanism of BED (boron enhanced diffusion), wherein the boron diffusivity is enhanced three to four times over the equilibrium diffusivity at 1,050 C in the proximity of a silicon layer containing a high boron concentration. It is shown that BED is associated with the formation of a fine-grain polycrystalline silicon boride phase within an initially amorphous Si layer having a high B concentration. For 0.5 keV B+, the threshold implantation dose which leads to BED lies between 3 x 1014 and of 1 x 1015/cm-2. Formation of the shallowest possible junctions by 0.5 keV B+ requires that the implant dose be kept lower than this threshold

  12. 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.

  13. The effects of stoichiometry on the mechanical properties of icosahedral boron carbide under loading.

    Science.gov (United States)

    Taylor, DeCarlos E; McCauley, James W; Wright, T W

    2012-12-19

    The effects of stoichiometry on the atomic structure and the related mechanical properties of boron carbide (B(4)C) have been studied using density functional theory and quantum molecular dynamics simulations. Computational cells of boron carbide containing up to 960 atoms and spanning compositions ranging from 6.7% to 26.7% carbon were used to determine the effects of stoichiometry on the atomic structure, elastic properties, and stress-strain response as a function of hydrostatic, uniaxial, and shear loading paths. It was found that different stoichiometries, as well as variable atomic arrangements within a fixed stoichiometry, can have a significant impact on the yield stress of boron carbide when compressed uniaxially (by as much as 70% in some cases); the significantly reduced strength of boron carbide under shear loading is also demonstrated. PMID:23165091

  14. The effects of stoichiometry on the mechanical properties of icosahedral boron carbide under loading

    International Nuclear Information System (INIS)

    The effects of stoichiometry on the atomic structure and the related mechanical properties of boron carbide (B4C) have been studied using density functional theory and quantum molecular dynamics simulations. Computational cells of boron carbide containing up to 960 atoms and spanning compositions ranging from 6.7% to 26.7% carbon were used to determine the effects of stoichiometry on the atomic structure, elastic properties, and stress-strain response as a function of hydrostatic, uniaxial, and shear loading paths. It was found that different stoichiometries, as well as variable atomic arrangements within a fixed stoichiometry, can have a significant impact on the yield stress of boron carbide when compressed uniaxially (by as much as 70% in some cases); the significantly reduced strength of boron carbide under shear loading is also demonstrated.

  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 sorption characteristics in resins

    International Nuclear Information System (INIS)

    The purpose of boron addition in a nuclear power plant is to control the reactivity. In PHWRs, it is injected into the moderator system in the form of boric anhydride solution, while in PHWRs, it is added to the primary heat transport system in the form of boric acid solution. The required boron levels in PHWRs are controlled by valving in strong base anion exchangers having exchangeable species in OD- form while in PHWRs, the same can be achieved by restoring to the use of Boron Thermal Regeneration System (BTRS). This system operates on the principle of existence of different amounts of various polyborate ions at different temperatures, solution pH's and the boric acid concentrations and on the reversible sorption of these polyions on strong base anion exchange resins. This report describes the salient features of boron sorption characteristics on four types of anion exchange resins, based on experimental data generated in the chemical laboratories of Reactor Engineering Division of the Bhabha Atomic Research Centre, Bombay. The report further makes an attempt to calculate the pH of the resin and solution phases and the percentages of different polyborates and undissociated boric acid, under the experimental conditions investigated. (author). 30 refs., 4 figs., 20 tables

  18. 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. PMID:22945740

  19. 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)

  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. 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.

  2. 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

  3. 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

  4. Effects of Edge Passivations on the Electronic and Magnetic Properties of Zigzag Boron-Nitride Nanoribbons with Even and Odd-Line Stone-Wales (5-7 Pair) Defects

    OpenAIRE

    Yamijala, Sharma SRKC; Pati, Swapan K.

    2014-01-01

    First-principles spin-polarized calculations have been performed on passivated Boron-Nitride Nanoribbons (BNNRs) with pentagon-heptagon line-defects (PHLDs) (also called as Stone-Wales line-defects). Two kinds of PHLDs, namely, even-line and odd-line PHLDs, have been added either at one edge or at both edges of BNNRs. Single-edge (with all its different possibilities, for example, for a BNNR with 2-line PHLD at single-edge there are 8 possibilities) as well as both-edge passivations have been...

  5. Synthesis of boron nitride nanotubes by boron ink annealing.

    Science.gov (United States)

    Li, Lu Hua; Chen, Ying; Glushenkov, Alexey M

    2010-03-12

    Ball-milling and annealing is one effective method for the mass production of boron nitride nanotubes (BNNTs). We report that the method has been modified to a boron (B) ink annealing method. In this new process, the nanosize ball-milled B particles are mixed with metal nitrate in ethanol to form an ink-like solution, and then the ink is annealed in nitrogen-containing gas to form nanotubes. The new method greatly enhances the yield of BNNTs, giving a higher density of nanotubes. These improvements are caused by the addition of metal nitrate and ethanol, both of which can strongly boost the nitriding reaction, as revealed by thermogravimetric analysis. The size and structure of BNNTs can be controlled by varying the annealing conditions. This high-yield production of BNNTs in large quantities enables the large-scale application of BNNTs. PMID:20154372

  6. Synthesis of boron nitride nanotubes by boron ink annealing

    International Nuclear Information System (INIS)

    Ball-milling and annealing is one effective method for the mass production of boron nitride nanotubes (BNNTs). We report that the method has been modified to a boron (B) ink annealing method. In this new process, the nanosize ball-milled B particles are mixed with metal nitrate in ethanol to form an ink-like solution, and then the ink is annealed in nitrogen-containing gas to form nanotubes. The new method greatly enhances the yield of BNNTs, giving a higher density of nanotubes. These improvements are caused by the addition of metal nitrate and ethanol, both of which can strongly boost the nitriding reaction, as revealed by thermogravimetric analysis. The size and structure of BNNTs can be controlled by varying the annealing conditions. This high-yield production of BNNTs in large quantities enables the large-scale application of BNNTs.

  7. Selection of anion exchange resins for boron thermal regeneration systems

    International Nuclear Information System (INIS)

    Boron concentration changes in the reactor coolant are effected using a new development called the boron thermal regeneration system (BTRS). Thermal regeneration refers to the use of ion-exchange resins in either retaining or releasing borate ions as a function of temperature. For the BTRS the equilibrium capacity of commercial and special anion exchange resins was investigated for the degree of cross-linking of anion resins. The equilibrium capacity increases with decreased temperature and depends strongly on the degree of cross-linking having the maximum point at about 7% of DVB. The temperature coefficient of equilibrium capacity of boric acid is also a function of the concentration of external solution and of the cross-linking having a maximum point of around 7% of DVB. Other basic characteristics of anion exchange resin were also investigated. (author)

  8. Synthesis of vinyl boronates from aldehydes by a practical boron-Wittig reaction.

    Science.gov (United States)

    Coombs, John R; Zhang, Liang; Morken, James P

    2015-04-01

    A highly stereoselective boron-Wittig reaction between stable and readily accessible 1,1-bis(pinacolboronates) and aldehydes furnishes a variety of synthetically useful di- and trisubstituted vinyl boronate esters. PMID:25799147

  9. 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.

  10. Analysis of magnetron sputtered boron oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Buc, Dalibor [Slovak University of Technology in Bratislava (Slovakia); Bello, Igor [City University of Hong Kong, Kowloon, Hong Kong (China); Caplovicova, Maria [Comenius University in Bratislava (Slovakia); Mikula, Milan; Kovac, Jaroslav; Hotovy, Ivan [Slovak University of Technology in Bratislava (Slovakia); Chong, Yat Min [City University of Hong Kong, Kowloon, Hong Kong (China); Siu, Guei Gu [City University of Hong Kong, Kowloon, Hong Kong (China)], E-mail: apggsiu@cityu.edu.hk

    2007-10-15

    Boron oxide films were grown on silicon substrates by radio-frequency (rf) unbalanced magnetron sputtering of a boron target in argon-oxygen gas mixtures with different compositions. Microscopic analyses show that overall boron oxide films are amorphous. The film prepared at oxygen/argon flow rate ratio > 0.05 developed large crystallites of boric acid in localize areas of amorphous boron oxide matrices. These crystallites were unstable and at electron microscopic analysis they continuously transformed to a cubic HBO{sub 2} phase and then completely vanished leaving an underlying amorphous boron oxide film behind. The analyses indicate the coexistence of B{sub 6}O, HBO{sub 2} crystallites and amorphous boron oxide matrices. Fourier transform infrared (FTIR) spectra revealed spectral bands of BOH, BO, BOB and BH groups. Nanohardness and elastic modulus of a film prepared at low oxygen concentration approach 30 and 300 GPa, respectively. These parameters however vary with deposition conditions.

  11. Microwave sintering of boron carbide composites

    International Nuclear Information System (INIS)

    Boron carbide is an important ceramic material because of its high hardness and low specific gravity. it is used for applications involving impact and wear resistance. The disadvantages of boron carbide materials are difficulty in fabrication and sensitivity to brittle fracture. These problems are significantly reduced by production of cermets based on boron carbide and aluminum or aluminum alloys. Microwave heating of boron carbide materials results in ultrarapid heating and high temperatures. Therefore, a finer microstructure is obtained. The objective of this work was to define a technology that would allow the manufacture of boron carbide ceramics having mechanical properties similar to those exhibited by hot-pressed specimens. microwave heating would be used for the densification step. Mixtures of boron carbide and aluminum were considered for this research because aluminum simultaneously acts as a sintering aid and introduces phases that contribute to toughness enhancement

  12. 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.

  13. The production of nitrogen-13 by neutron capture in boron compounds

    International Nuclear Information System (INIS)

    The 10B(α,n)13N reaction is studied as an activation process in a variety of solid boron-containing neutron shielding materials. The source of α-particles is the neutron capture reaction 10B(n,α)7Li. Samples of boron carbide, boron oxide, and boron nitride are irradiated with thermal neutrons and the rate of 13N production is determined. 13N promptly decays, emitting a positron. This positron efficiently annihilates with electrons in the material and the resultant 511 keV gamma ray is detected. For each of the above-mentioned materials, the rate of 13N production is (1-2) x 10-10 per captured neutron

  14. Synthesis of boron carbide nano particles using polyvinyl alcohol and boric acid

    Directory of Open Access Journals (Sweden)

    Amir Fathi

    2012-03-01

    Full Text Available In this study boron carbide nano particles were synthesized using polyvinyl alcohol and boric acid. First, initial samples with molar ratio of PVA : H3BO3 = 2.7:2.2 were prepared. Next, samples were pyrolyzed at 600, 700 and 800°C followed by heat treatment at 1400, 1500 and 1600°C. FTIR analysis was implemented before and after pyrolysis in order to study the reaction pathway. XRD technique was used to study the composition of produced specimens of boron carbide. Moreover, SEM and PSA analysis were also carried out to study the particle size and morphology of synthesized boron carbide. Finally, according to implemented tests and analyses, carbon-free boron carbide nano particles with an average size of 81 nm and mainly spherical morphology were successfully produced via this method.

  15. 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.

  16. 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

  17. 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.

  18. Sintering behavior of boron carbide

    International Nuclear Information System (INIS)

    Pressureless sintering behavior of boron carbide (B4C) in argon was studied, with change in time and temperature, using carbon as sintering aid. Carbon was added via fenolic resin, acting also as a binder. After isostatic pressing the specimens were sintered in a graphite furnace at 19600C/1h, 21600C/15 minutes and 1h and 22000C/1h. The achieved density was 97% of the theoretical. Some mechanical properties and microstructural aspects have been evaluated. (author)

  19. 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...

  20. Boron removal from geothermal waters by electrocoagulation

    International Nuclear Information System (INIS)

    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/cm2, 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%

  1. 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%.

  2. Boron deposition from fused salts. Final report

    International Nuclear Information System (INIS)

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

  3. 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

  4. Three-chain B{sub 6n+14} cages as possible precursors for the syntheses of boron fullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Haigang, E-mail: luhg@sxu.edu.cn; Li, Si-Dian [Key Laboratory of Chemical Biology and Molecular Engineering of the Education Ministry, Institute of Molecular Science, Shanxi University, Taiyuan, Shanxi 030006 (China)

    2013-12-14

    Using the first principle methods, we proposed a series of three-chain boron cages B{sub 6n+14} (n = 1–12) which are mainly built by fusing three boron semi-double-rings. Their simple geometric structures (approximate D{sub 3} or C{sub 3} symmetry) facilitate their bottom-up syntheses from the hexagonal B{sub 7} and the double-chain boron clusters, such as B{sub 2}, B{sub 4}, B{sub 6}, B{sub 8}H{sub 2}, B{sub 10}H{sub 2}, B{sub 12}H{sub 2}, and the double ring B{sub 20}. The spherical shapes of these three-chain boron cages show that they could be taken as the possible precursors to further synthesize the boron fullerenes, such as B{sub 80}. Therefore, these three-chain boron cages provide a possible synthesis pathway of the boron fullerenes from the experimentally synthesized small planar boron clusters.

  5. Differentiation in boron distribution in adult male and female rats' normal brain: A BNCT approach

    Energy Technology Data Exchange (ETDEWEB)

    Goodarzi, Samereh, E-mail: samere.g@gmail.com [Department of Nuclear Engineering, Science and Research Branch, Islamic Azad University, PO Box 19395-1943, Tehran (Iran, Islamic Republic of); Pazirandeh, Ali, E-mail: paziran@yahoo.com [Department of Nuclear Engineering, Science and Research Branch, Islamic Azad University, PO Box 19395-1943, Tehran (Iran, Islamic Republic of); Jameie, Seyed Behnamedin, E-mail: behnamjameie@tums.ac.ir [Basic Science Department, Faculty of Allied Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Department of Anatomy, Faculty of Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Baghban Khojasteh, Nasrin, E-mail: khojasteh_n@yahoo.com [Department of Nuclear Engineering, Science and Research Branch, Islamic Azad University, PO Box 19395-1943, Tehran (Iran, Islamic Republic of)

    2012-06-15

    Boron distribution in adult male and female rats' normal brain after boron carrier injection (0.005 g Boric Acid+0.005 g Borax+10 ml distilled water, pH: 7.4) was studied in this research. Coronal sections of control and trial animal tissue samples were irradiated with thermal neutrons. Using alpha autoradiography, significant differences in boron concentration were seen in forebrain, midbrain and hindbrain sections of male and female animal groups with the highest value, four hours after boron compound injection. - Highlights: Black-Right-Pointing-Pointer Boron distribution in male and female rats' normal brain was studied in this research. Black-Right-Pointing-Pointer Coronal sections of animal tissue samples were irradiated with thermal neutrons. Black-Right-Pointing-Pointer Alpha and Lithium tracks were counted using alpha autoradiography. Black-Right-Pointing-Pointer Different boron concentration was seen in brain sections of male and female rats. Black-Right-Pointing-Pointer The highest boron concentration was seen in 4 h after boron compound injection.

  6. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Durmazucar, Hasan H.; Guenduez, Guengoer E-mail: ggunduz@metu.edu.tr

    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.

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

    International Nuclear Information System (INIS)

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

  9. Application of neutron induced radiography technique in determination of boron in aluminium

    International Nuclear Information System (INIS)

    The technique of Neutron Induced Radiography has been applied to determine boron concentration and its spatial distribution in aluminium using Allyl diglycol carbonate (CR-39) detectors. The technique is based upon the simultaneous irradiation of sample and a standard fixed on a track detector with thermal neutrons and the counting of alpha and /sup 7/Li tracks produced in the detector from the nuclear reaction /sup 10/B(n,α)/sup 7/Li after chemical etching. Boron concentration is determined by comparing the /sup 7/Li and alpha particle tracks density with that of a standard of known boron concentration. Boron concentration in aluminium has been found to be (135.8 ±0.7) ppm in this study which is on the higher side within the normal range reported in the literature. The technique of boron determination by Neutron Induced Radiography is a simple and reliable. It can be used to study the other α-emitting radionuclides in minerals and other materials. (author)

  10. 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

  11. Boron carbide synthesis by carbothermic reduction of boron oxide

    International Nuclear Information System (INIS)

    Boron carbide (B4C) is a ceramic material of technological applications due to its extreme hardness and high chemical as well as thermal stability. Some parameters of the process for obtaining B4C by carbothermic reduction of B2O3 have been determined. The starting powders and the final products have been analysed by chemical, spectrographic and X-ray diffraction methods. The results show that the B4C obtained by the carbothermic reduction process is suitable for applications with a definite determination of the free carbon content. (author)

  12. Nuclear Physics meets Medicine and Biology: Boron Neutron Capture Therapy

    CERN Document Server

    F. Ballarini, F; S. Bortolussi, S; P. Bruschi, P; A.M. Clerici, A M; A. De Bari, A; P. Dionigi, P; C. Ferrari, C; M.A. Gadan, M A; N. Protti, N; S. Stella, S; C. Zonta, C; A. Zonta, A; S. Altieri, S

    2010-01-01

    BNCT is a tumour treatment based on thermal-neutron irradiation of tissues enriched with 10B, which according to the 10B(n, )7Li reaction produces particles with high Linear Energy Transfer and short range. Since this treatment can deliver a therapeutic tumour dose sparing normal tissues, BNCT represents an alternative for diffuse tumours and metastases, which show poor response to surgery and photontherapy. In 2001 and 2003, in Pavia BNCT was applied to an isolated liver, which was infused with boron, explanted, irradiated and re-implanted. A new project was then initiated for lung tumours, developing a protocol for Boron concentration measurements and performing organ-dose Monte Carlo calculations; in parallel, radiobiology studies are ongoing to characterize the BNCT effects down to cellular level. After a brief introduction, herein we will present the main activities ongoing in Pavia including the radiobiological ones, which are under investigation not only experimentally but also theoretically, basing on...

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

    Institute of Scientific and Technical Information of China (English)

    XIAO; Yingkai

    2001-01-01

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

  14. Investigation of Properties of Asphalt Concrete Containing Boron Waste as Mineral Filler

    Directory of Open Access Journals (Sweden)

    Cahit GÜRER

    2016-05-01

    Full Text Available During the manufacture of compounds in the boron mining industry a large quantity of waste boron is produced which has detrimental effects on the environment. Large areas have to be allocated for the disposal of this waste. Today with an increase in infrastructure construction, more efficient use of the existing sources of raw materials has become an obligation and this involves the recycling of various waste materials. Road construction requires a significant amount of raw materials and it is possible that substantial amounts of boron-containing waste materials can be recycled in these applications. This study investigates the usability of boron wastes as filler in asphalt concrete. For this purpose, asphalt concrete samples were produced using mineral fillers containing 4%, 5%, 6%, 7% and 8% boron waste as well as a 6% limestone filler (6%L as the control sample. The Marshall Design, mechanical immersion and Marshall Stability test after a freeze-thaw cycle and indirect tensile stiffness modulus (ITSM test were performed for each of the series. The results of this experimental study showed that boron waste can be used in medium and low trafficked asphalt concrete pavements wearing courses as filler.

  15. Determination of plant available boron in agricultural soil by using voltammetric method

    Directory of Open Access Journals (Sweden)

    Ebru Çetinkaya

    2014-08-01

    Full Text Available In this study, a novel voltammetric method has been developed to determine the amount of boron in soil. 50 soil samples were collected from 5 typical sites of agricultural area. After hot water extraction of available boron in the soil samples, all boron is complexed by addition of Alizarin Red S (ARS to the extraction solutions.Differential pulse anodic stripping voltammetry was used to determine the amount of the boron complexes. The electrochemical parameters have been optimized according to the experimental results. The optimum scan rate, stirring rate, deposition potential, deposition time and pH values were determined as 5 mVs-1 , 200 rpm, -0.5 V (vs. Ag/AgCl, sat., 15sec. and 7.5, respectively. An oxidation peak was occurred at the peak potential of -0.45 V for Boron-Alizarin complex. The limit of detection, limit of quantification and linear working range were determined for the voltammetric soil-boron analysis. In addition, the interference effects of coexisting ions were successfully investigated. Comparison of the analytical data for analyzing real samples was carried out between the differential pulse anodic stripping voltammetric method and the Azometine H spectrophotometric method have shown good agreement. A great advantage of voltammetry over the spectrophotometric method is found to be simplicity, selectivity and shortening of the analysis time.

  16. Investigation of Properties of Asphalt Concrete Containing Boron Waste as Mineral Filler

    Directory of Open Access Journals (Sweden)

    Cahit GÜRER

    2016-03-01

    Full Text Available During the manufacture of compounds in the boron mining industry a large quantity of waste boron is produced which has detrimental effects on the environment. Large areas have to be allocated for the disposal of this waste. Today with an increase in infrastructure construction, more efficient use of the existing sources of raw materials has become an obligation and this involves the recycling of various waste materials. Road construction requires a significant amount of raw materials and it is possible that substantial amounts of boron-containing waste materials can be recycled in these applications. This study investigates the usability of boron wastes as filler in asphalt concrete. For this purpose, asphalt concrete samples were produced using mineral fillers containing 4%, 5%, 6%, 7% and 8% boron waste as well as a 6% limestone filler (6%L as the control sample. The Marshall design, mechanical immersion and Marshall stability test after a freeze-thaw cycle and indirect tensile stiffness modulus (ITSM test were performed for each of the series. The results of this experimental study showed that boron waste can be used in medium and low trafficked asphalt concrete pavements wearing courses as filler.

  17. Removal of Boron in Silicon by H2-H2O Gas Mixtures

    Science.gov (United States)

    Tang, Kai; Andersson, Stefan; Nordstrand, Erlend; Tangstad, Merete

    2012-08-01

    The removal of boron in pure silicon by gas mixtures has been examined in the laboratory. Water-vapor-saturated hydrogen was used to remove boron doped in electronic-grade silicon in a vacuum frequency furnace. Boron concentrations in silicon were reduced from 52 ppm initially to 0.7 ppm and 3.4 ppm at 1450°C and 1500°C, respectively, after blowing a H2-3.2%H2O gas mixture for 180 min. The experimental results indicate that the boron removal as a function of gas-blowing time follows the law of exponential decay. After 99% of the boron is removed, approximately 90% of the silicon can be recovered. In order to better understand the gaseous refining mechanism, the quantum chemical coupled cluster with single and double excitations and a perturbative treatment of triple excitations method was used to accurately predict the enthalpy and entropy of formation of the HBO molecule. A simple refining model was then used to describe the boron refining process. This model can be used to optimize the refining efficiency.

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

    Institute of Scientific and Technical Information of China (English)

    赵志琦; 刘丛强; 肖应凯; 郎赟超

    2003-01-01

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

  19. Ferrocenyl-substituted Schiff base complexes of boron: Synthesis, structural, physico-chemical and biochemical aspects

    Science.gov (United States)

    Yadav, Sunita; Singh, R. V.

    2011-01-01

    Biological important complexes of boron(III) derived from 1-acetylferrocenehydrazinecarboxamide (L 1H), 1-acetylferrocenehydrazinecarbothioamide (L 2H) and 1-acetylferrocene carbodithioic acid (L 3H) have been prepared and investigated using a combination of microanalytical analysis, melting point, electronic, IR, 1H NMR and 13C NMR spectral studies, cyclic voltammetry and X-ray powder diffraction studies. Boron isopropoxide interacts with the ligands in 1:1, 1:2 and 1:3 molar ratios (boron:ligand) resulting in the formation of coloured products. On the basis of conductance and spectral evidences, tetrahedral structures for boron(III) complexes have been assigned. The ligands are coordinated to the boron(III) via the azomethine nitrogen atom and the thiolic sulfur atom/enolic oxygen atom. On the basis of X-ray powder diffraction study one of the representative boron complex was found to have orthorhombic lattice, having lattice parameters: a = 9.9700, b = 15.0000 and c = 7.0000. Both the ligands and their complexes have been screened for their biological activity on several pathogenic fungi and bacteria and were found to possess appreciable fungicidal and bactericidal properties. Plant growth regulating activity of one of the ligand and its complexes has also been recorded on gram plant, and results have been discussed.

  20. 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

  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. 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.

  4. Boron Carbides As Thermo-electric Materials

    Science.gov (United States)

    Wood, Charles

    1988-01-01

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

  5. Nuclear fuel management and boron carbide coating

    International Nuclear Information System (INIS)

    In recent years one way of introducing burnable absorber is to coat the fuel pellets by a thin layer of burnable absorber so called integral fuel burnable absorber (IFBA). In this method the fuel is coated with boron nitride or boron carbide. Boron has low absorption cross-section and when it exists on the surface of the fuel, it interacts with thermalized neutron. B4C is a boron compound, which can be used for coating the nuclear fuel. It has high thermal stability and withstands high pressure and temperatures. High technology product of boron carbide has different ratio of B: C. But in nuclear reactor when boron carbide is used, it must be rich with boron. In this research chemical vapor decomposition (CVD) has been using boron trichloride and carbon tetra chloride for reactant materials. The experiments were carried out at high temperatures (1050 degree Celsius, 1225 degree Celsius and 1325 degree Celsius). The coated samples were analyzed using X-Ray diffractometer (XRD), scanning electron microscopy (SEM) and will be presented in this paper. It was seen that decreasing the reaction temperature caused an increase on the quality and thickness of the coating

  6. Boron and Coumaphos Residues in Hive Materials Following Treatments for the Control of Aethina tumida Murray.

    Directory of Open Access Journals (Sweden)

    Cesar Valdovinos-Flores

    Full Text Available In the search of alternatives for controlling Aethina tumida Murray, we recently proposed the BAA trap which uses boric acid and an attractant which mimics the process of fermentation caused by Kodamaea ohmeri in the hive. This yeast is excreted in the feces of A. tumida causing the fermentation of pollen and honey of infested hives and releasing compounds that function as aggregation pheromones to A. tumida. Since the boron is the toxic element in boric acid, the aim of this article is to assess the amount of boron residues in honey and beeswax from hives treated with the BAA trap. For this aim, the amount of bioaccumulated boron in products of untreated hives was first determined and then compared with the amount of boron of products from hives treated with the BAA trap in two distinct climatic and soil conditions. The study was conducted in the cities of Padilla, Tamaulipas, and Valladolid, Yucatan (Mexico from August 2014 to March 2015. The quantity of boron in honey was significantly less in Yucatan than in Tamaulipas; this agrees with the boron deficiency among Luvisol and Leptosol soils found in Yucatan compared to the Vertisol soil found in Tamaulipas. In fact, the honey from Yucatan has lower boron levels than those reported in the literature. The BAA treatment was applied for four months, results show that the BAA trap does not have any residual effect in either honey or wax; i.e., there is no significant difference in boron content before and after treatment. On the other hand, the organophosphate pesticide coumaphos was found in 100% of wax samples and in 64% of honey samples collected from Yucatan. The concentration of coumaphos in honey ranges from 0.005 to 0.040 mg/kg, which are below Maximum Residue Limit (MRL allowed in the European Union (0.1 mg/kg but 7.14% of samples exceeded the MRL allowed in Canada (0.02 mg/kg.

  7. Distribution and excretion of boron after intravenous administration of disodium mercaptoundecahydro-closo-dodecaborate to rats

    International Nuclear Information System (INIS)

    Disodium mercaptoundecahydro-closo-dodecaborate (BSH) is an important compound for boron neutron capture therapy. The pharmacokinetics of boron by BSH were studied in normal rats after rapid intravenous injection at three doses (30, 100, 300 mg/kg) or continuous infusion (100 mg/kg/ 30 min). The boron concentration in biological samples was measured by inductively coupled plasma atomic emission spectroscopy. The blood half-lives of boron in the elimination phase (t1/2 β) after rapid injection of BSH at doses of 30, 100 and 300 mg/kg were 1.7, 17 and 19 hr, respectively. AUC (32, 219 and 4030 μg·hr/ml) increased with the dose, but there was no proportionality among the values. Total clearance decreased drastically from 233 ml/hr/kg (100 mg/kg) to 38 ml/hr/kg (300 mg/kg). As boron was excreted mainly into urine, these results suggest that renal function failure might occur with dosing of 300 mg/kg. In the case of continuous infusion of 100 mg/kg of BSH for 30 min, the pharmacokinetic parameters were similar to those of rapid injection of 100 mg/kg. The highest boron concentration was observed in the kidney and the lowest in the brain. After multiple dosing of BSH at 100 mg/kg/day x 14 days, the boron concentrations in blood, liver, lung and kidney at 24 hr after the last dosing were higher than those after single dosing and were similar to those of simulated values calculated from the single dosing parameters. These results clearly indicated that boron does not accumulate unexpectedly in any tissue with multiple dosing of 100 mg/kg of BSH for two weeks. (author)

  8. Improving the electrochemical properties of nanosized LiFePO4-based electrode by boron doping

    International Nuclear Information System (INIS)

    Highlights: • Thermal treatment of boron phosphate with LiFePO4 provides electrode materials with high performance in lithium half-cells: 160 mAh·g-1 (90% of theoretical capacity) under C/5 rate • The products are composites containing boron-modified LiFePO4, FePO4 and an amorphous phase with ionic diffusion properties • The boron treatment affects textural, conductive and lithium diffusivity of the electrode material leading to higher performance • A limited boron-doping of the phospholivine structure is observed - Abstract: Electrode materials with homogeneous distribution of boron were obtained by heating mixtures of nanosized carbon-coated lithium iron phosphate and BPO4 in 3-9% weight at 700 °C. The materials can be described as nanocomposites containing i) LiFePO4, possibly doped with a low amount of boron, ii) FePO4 and iii) an amorphous layer based on Li4P2O7-derived material that surrounds the phosphate particles. The thermal treatment with BPO4 also triggered changes in the carbon coating graphitic order. Galvanostatic and voltammetric studies in lithium half-cells showed smaller polarisation, higher capacity and better cycle life for the boron-doped composites. For instance, one of the solids, called B6-LiFePO4, provided close to 150 and 140 mAhg-1 (87% and 81% of theoretical capacity, respectively) under C/2.5 and C regimes after several cycles. Improved specific surface area, carbon graphitization, conductivity and lithium ion diffusivity in the boron-doped phospholivine network account for this excellent rate performance. The properties of an amorphous layer surrounding the phosphate particles also account for such higher performance

  9. Boron and Coumaphos Residues in Hive Materials Following Treatments for the Control of Aethina tumida Murray

    Science.gov (United States)

    Valdovinos-Flores, Cesar; Gaspar-Ramírez, Octavio; Heras–Ramírez, María Elena; Dorantes-Ugalde, José Antonio; Saldaña-Loza, Luz María

    2016-01-01

    In the search of alternatives for controlling Aethina tumida Murray, we recently proposed the BAA trap which uses boric acid and an attractant which mimics the process of fermentation caused by Kodamaea ohmeri in the hive. This yeast is excreted in the feces of A. tumida causing the fermentation of pollen and honey of infested hives and releasing compounds that function as aggregation pheromones to A. tumida. Since the boron is the toxic element in boric acid, the aim of this article is to assess the amount of boron residues in honey and beeswax from hives treated with the BAA trap. For this aim, the amount of bioaccumulated boron in products of untreated hives was first determined and then compared with the amount of boron of products from hives treated with the BAA trap in two distinct climatic and soil conditions. The study was conducted in the cities of Padilla, Tamaulipas, and Valladolid, Yucatan (Mexico) from August 2014 to March 2015. The quantity of boron in honey was significantly less in Yucatan than in Tamaulipas; this agrees with the boron deficiency among Luvisol and Leptosol soils found in Yucatan compared to the Vertisol soil found in Tamaulipas. In fact, the honey from Yucatan has lower boron levels than those reported in the literature. The BAA treatment was applied for four months, results show that the BAA trap does not have any residual effect in either honey or wax; i.e., there is no significant difference in boron content before and after treatment. On the other hand, the organophosphate pesticide coumaphos was found in 100% of wax samples and in 64% of honey samples collected from Yucatan. The concentration of coumaphos in honey ranges from 0.005 to 0.040 mg/kg, which are below Maximum Residue Limit (MRL) allowed in the European Union (0.1 mg/kg) but 7.14% of samples exceeded the MRL allowed in Canada (0.02 mg/kg). PMID:27092938

  10. Development of a boron-copper neutron absorber composite

    International Nuclear Information System (INIS)

    This report describes the fabrication of a new boron-copper neutron absorbing material that was developed to meet the upgrading needs of the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory. To increase the intensity of the neutron beams from the IPNS, the target uranium was changed from depleted uranium to uranium enriched to 77.5% 235U. To keep the multiplication factor, keff (number of fissions in one generation/number of fissions in preceding generation) at a safe level, a new neutron absorber material was needed. The previous materials, boral and cadmium, could not meet the new requirements and a search of the literature showed that no currently available material was acceptable. With previous powder metallurgy used as a base, the composite was fabricated with 43 vol. % 10B (81% enriched 10B) and the balance copper and voids. The powder metallurgy techniques was followed by hot-rolling the composite to a sheet. The material composed of boron particles dispersed in a pure copper matrix and clad with pure copper on both sides, exhibits the following properties: Loadings up to 43 vol. % boron, with the balance copper and voids. A loading of 0.5 x 102210B atoms/cm2 in sections as thin as 0.067 in. (1.7 mm), with copper cladding as thin as 0.010 in. (0.25 mm). Formability to radii as small as 2.1 in. (53.3 mm). No observed reaction between boron and the copper matrix and cladding at temperatures up to 900 degrees C for times as long as 7 h. Retains structural integrity at 900 degrees C

  11. Boron isotopic enrichment by displacement chromatography

    International Nuclear Information System (INIS)

    10B enriched boron is used in applications requiring high volumetric neutron absorption (absorption cross section- 3837 barn for thermal and 1 barn for 1 MeV fast neutron). It is used in fast breeder reactor (as control rod material), in neutron counter, in Boron Neutron Capture Therapy etc. Owing to very small separation factor, boron isotopic enrichment is a complex process requiring large number of separation stages. Heavy Water Board has ventured in industrial scale production of 10B enriched boron using Exchange Distillation Process as well as Ion Displacement Chromatography Process. Ion Displacement Chromatography process is used in Boron Enrichment Plant at HWP, Manuguru. It is based on isotopic exchange between borate ions (B(OH)4-) on anion exchange resin and boric acid passing through resin. The isotopic exchange takes place due to difference in zero point energy of 10B and 11B

  12. 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. PMID:25427850

  13. 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.

    2015-01-01

    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.

  14. Optimal timing of neutron irradiation for boron neutron capture therapy after intravenous infusion of sodium borocaptate in patients with glioblastoma

    International Nuclear Information System (INIS)

    Purpose: A cooperative study in Europe and Japan was conducted to determine the pharmacokinetics and boron uptake of sodium borocaptate (BSH: Na2B12H11SH), which has been introduced clinically as a boron carrier for boron neutron capture therapy in patients with glioblastoma. Methods and Materials: Data from 56 patients with glioblastoma who received BSH intravenous infusion were retrospectively reviewed. The pharmacokinetics were evaluated in 50 patients, and boron uptake was investigated in 47 patients. Patients received BSH doses between 12 and 100 mg/kg of body weight. For the evaluation, the infused boron dose was scaled linearly to 100 mg/kg BSH. Results: In BSH pharmacokinetics, the average value for total body clearance, distribution volume of steady state, and mean residence time was 3.6±1.5 L/h, 223.3±160.7 L, and 68.0±52.5 h, respectively. The average values of the boron concentration in tumor adjusted to 100 mg/kg BSH, the boron concentration in blood adjusted to 100 mg/kg BSH, and the tumor/blood boron concentration ratio were 37.1±35.8 ppm, 35.2±41.8 ppm, and 1.53±1.43, respectively. A good correlation was found between the logarithmic value of Tadj and the interval from BSH infusion to tumor tissue sampling. About 12-19 h after infusion, the actual values for Tadj and tumor/blood boron concentration ratio were 46.2±36.0 ppm and 1.70±1.06, respectively. The dose ratio between tumor and healthy tissue peaked in the same interval. Conclusion: For boron neutron capture therapy using BSH administered by intravenous infusion, this work confirms that neutron irradiation is optimal around 12-19 h after the infusion is started

  15. Burnup performances of boron nitride and boron coated nuclear fuels

    International Nuclear Information System (INIS)

    The nuclear fuels of urania (UOV) and 5% and 10% gadolinia (Gd2O3) containing UO2 previously produced by sol-gel technique were coated with first boron nitride (BN) then boron (B) thin layer by chemical vapor deposition (CVD) and also by plasma enhanced chemical vapor deposition (PECVD) techniques to increase the fuel cycle length and to improve the physical properties. From the cross-sectional view of BN and B layers taken from scanning electron microscope (SEM), the excellent adherence of BN onto fuel and B onto BN layer was observed in both cases. The behavior of fuel burnup, depletion of BN and B, the effect of coating thickness and also Gd2O3 content on the burnup performances of the fuels were identified by using the code WIMS-D/4 for Pressurized Water Reactor (PWR) and Boiling Water Reactor (BWR) cores. The optimum thickness ratio of B to BN was found as 4 and their thicknesses were chosen as 40 mm and 10 mm respectively in both reactor types to get extended cycle length. The assemblies consisting of fuels with 5% Gd2O3 and also coated with 10 mm BN and 40 mm B layers were determined as candidates for getting higher burnup in both types of reactors

  16. Sodium borocaptate (BSH) for Boron Neutron Capture Therapy (BNCT) in the hamster cheek pouch oral cancer model: boron biodistribution at 9 post administration time-points

    International Nuclear Information System (INIS)

    The therapeutic success of Boron Neutron Capture Therapy (BNCT) depends centrally on boron concentration in tumor and healthy tissue. We previously demonstrated the therapeutic efficacy of boronophenylalanine (BPA) and sodium decahydrodecaborate (GB-10) as boron carriers for BNCT in the hamster cheek pouch oral cancer model. Given the clinical relevance of sodium mercaptoundecahydro-closo-dodecaborate (BSH) as a boron carrier, the aim of the present study was to expand the ongoing BSH biodistribution studies in the hamster cheek pouch oral cancer model. In particular, we studied 3 additional post-administration time-points and increased the sample size corresponding to the time-points evaluated previously, to select more accurately the post-administration time at which neutron irradiation would potentially confer the greatest therapeutic advantage. BSH was dissolved in saline solution in anaerobic conditions to avoid the formation of the dimer BSSB and its oxides which are toxic. The solution was injected intravenously at a dose of 50 mg 10 B/kg (88 mg BSH / kg). Different groups of animals were killed humanely at 7, 8, and 10 h after administration of BSH. The sample size corresponding to the time-points 3, 4, 6, 9 and 12 h was increased. Samples of blood, tumor, precancerous tissue, normal pouch tissue, cheek mucosa, parotid gland, palate, skin, tongue, spinal cord marrow, brain, liver, kidney, spleen and lung were processed for boron measurement by Optic Emission Spectroscopy (ICP-OES). Boron concentration in tumor peaked to 24-34 ppm, 3-10 h post-administration of BSH, with a spread in values that resembled that previously reported in other experimental models and human subjects. The boron concentration ratios tumor/normal pouch tissue and tumor/blood ranged from 1.3 to 1.8. No selective tumor uptake was observed at any of the time points evaluated. The times post-administration of BSH that would be therapeutically most useful would be 5, 7 and 9 h. The

  17. 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.

  18. 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

  19. Experimental boron neutron capture therapy for melanoma: Systemic delivery of boron to melanotic and amelanotic melanoma

    International Nuclear Information System (INIS)

    The boron-containing melanin precursor analogue p-boronophenylalanine (BPA) has previously been shown to selectively deliver boron to pigmented murine melanomas when administered in a single intragastric dose. If boron neutron capture therapy is to become a clinically useful method of radiation therapy for human malignant melanoma, the boron carrier must be capable of delivering useful amounts of boron to remote tumor sites (metastases) and to poorly pigmented melanomas. The authors have now determined the ability of BPA to accumulate in several nonpigmented melanoma models including human melanoma xenografts in nude mice. The absolute amount of boron in the nonpigmented melanomas was about 50% of the observed in the pigmented counterparts but was still selectively concentrated in the tumor relative to normal tissues in amounts sufficient for effective neutron capture therapy. Single intragastric doses of BPA resulted in selective localization of boron in the amelanotic Greene melanoma carried in the anterior chamber of the rabbit eye and in a pigmented murine melanoma growing in the lungs. The ratio of the boron concentration in these tumors to the boron concentration in the immediately adjacent normal tissue was in the range of 3:1 to 4:1. These distribution studies support the proposal that boron neutron capture therapy may be useful as a regional therapy for malignant melanoma

  20. Carborane derivative development for boron neutron capture therapy. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Barnum, Beverly A.; Yan Hao; Moore, Roger; Hawthorne, M. Frederick; Baum, Kurt

    1999-04-01

    Boron Neutron Capture Therapy [BNCT] is a binary method of cancer therapy based on the capture of neutrons by a boron-10 atom [{sup 10}B]. Cytotoxic {sup 7}Li nuclei and {alpha}-particles are emitted, with a range in tissue of 9 and 5 {micro}m, respectively, about one cell diameter. The major obstacle to clinically viable BNCT is the selective localization of 5-30 ppm {sup 10}B in tumor cells required for effective therapy. A promising approach to BNCT is based on hydrophilic boron-rich oligomeric phosphate diesters, or ''trailers'' that have been shown to concentrate selectively in tumor tissue. Examples of these compounds were prepared previously at high cost using an automated DNA synthesizer. Direct synthesis methods are needed for the production of gram-scale quantities for further biological evaluation. The work accomplished as a result of the collaboration between Fluorochem, Inc. and UCLA demonstrates that short oligomers containing at least five carborane units with four phosphodiester linkages can be prepared in substantial quantities. This work was accomplished by the application of standard phosphoramidite coupling chemistry.

  1. Methods of Boron-carbon Deposited Film Removal

    Science.gov (United States)

    Airapetov, A.; Terentiev, V.; Voituk, A.; Zakharov, A.

    Boron carbide was proposed as a material for in-situ renewable protecting coating for tungsten tiles of the ITER divertor. It is necessary to develop a method of gasification of boron-carbon film which deposits during B4C sputtering. In this paper the results of the first stage investigation of gasification methods of boron-carbon films are presented. Two gasification methods of films are investigated: interaction with the ozone-oxygen mixture and irradiation in plasma with the working gas composed of oxygen, ethanol, and, in some cases, helium. The gasification rate in the ozone-oxygen mixture at 250 °C for B/C films with different B/C ratio and carbon fiber composite (CFC), was measured. For B/C films the gasification rate decreased with increasing B/C ratio (from 45 nm/h at B/C=0.7 to 4 nm/h at B/C=2.1; for CFC - 15 μm/h). Films gasification rates were measured under ion irradiation from ethanol-oxygen-helium plasma at different temperatures, with different ion energies and different gas mixtures. The maximum obtained removal rate was near 230 nm/h in case of ethanol-oxygen plasma and at 150°C of the sample temperature.

  2. Spectrophotometric determination of microamounts of boron in water

    International Nuclear Information System (INIS)

    A fast method of boron in water determination has been studied for the 0.5 .- 2 μg ml-1 concentration range. The procedure is based on the formation of a coloured complex of the tetrafluoroborate of a thionine derivate cation, its extraction by an organic solvent and the further absorptiometric measurement in such media. Methylene blue and azur C were comparatively tested as organic reagents, with 1.2-dichloroethane as the extractant. The absorbance was measured at the maximum (658 nm). The tetrafluoroboric acid formation was reached in 20 min on a water-bath kept at 60 deg C. The sensitivity with methylene blue was higher than with azur C. The molar absorptivities were 65,000 and 38,000 (l mol-1 cm-1) respectively. For a boron concentration of 0.1 μg ml-1 the relative standard deviation was 9% for methylene blue and 7% for azur C. The procedure is applicable to the control of boron traces in heavy water of nuclear reactors refrigerating loops. (author)

  3. Automatic spectrophotometric determination of trace amounts of boron with curcumin

    International Nuclear Information System (INIS)

    The proposed method utilizes a rosocyanin complex formed by the reaction of boric acid and curcumin without evaporation to dryness. The automatic determination of boron in aqueous solution is performed according to the predetermined program (Fig. 8), after manual injection of a sample solution (2.00 ml) to the reaction vessel. Glacial acetic acid (5.40 ml) and propionic anhydride (13.20 ml) are added and the solution is circulated through the circulating pipe consisting of a bubble remover, an absorbance measuring flow cell, an air blowing tube and a drain valve. Oxalyl chloride (0.81 ml) is added and the solution is circulated for 80 seconds to eliminate water. Sulfuric acid (1.08 ml) and curcumin reagent (3.01 ml) are added and the solution is circulated for 120 seconds to form a rosocyanin complex. After addition of an acetate buffer solution (21.34 ml) for the neutralisation of an interfering proton complex of curcumin, the absorbance of the orange solution is measured at 545 nm. This automatic analysis is sensitive (Fig. 9) and rapid; less than 1.5 μg of boron is determined in 7 minutes. It can be applied to the determination of trace amounts of boron in steel samples, combined with an automatic distillation under development. (auth.)

  4. Phenol removal from wastewaters by electrochemical oxidation using boron doped diamond (BDD) and Ti/Ti{sub 0.7}Ru{sub 0.3}O{sub 2} DSA Registered-Sign electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Britto-Costa, P.H.; Ruotolo, L.A.M., E-mail: pluis@ufscar.br [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Dept. de Engenharia Quimica

    2012-10-15

    Industrial wastewater containing non-biodegradable organic pollutants consists of highly toxic effluents whose treatment is necessary due to environmental and economical restrictions. In order to treat these effluents, an electrochemical process using a dimensionally stable anode (DSA Registered-Sign ) and boron-doped diamond (BDD) electrode was studied. The performance of these electrodes for COD removal from aqueous phenol solution was evaluated in the absence and presence of different chloride concentrations. The results showed that DSA Registered-Sign could be successfully used to remove COD when high chloride concentration (3035 mg L{sup -1}Cl{sup -}) and mild current density are employed (50 mA cm{sup -2}). On the other hand, the presence of chloride did not have the same significant effect on the COD depletion rate using BDD; however, under mild conditions (50 mA cm{sup -2}, 0.190 m s{sup -1}), the addition of 607 mg L{sup -1} Cl{sup -} improved the COD removal by approximately 52% after 8 hours of electrolysis. The effect of current density (i) and flow velocity (v) were also studied, and it was verified that they have an important role on the process performance, especially when DSA Registered-Sign is used. (author)

  5. 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...

  6. 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 ...

  7. Quantitative evaluation of boron neutron capture therapy (BNCT) drugs for boron delivery and retention at subcellular scale resolution in human glioblastoma cells with imaging secondary ion mass spectrometry (SIMS)

    Science.gov (United States)

    Chandra, S.; Ahmad, T.; Barth, R. F.; Kabalka, G. W.

    2014-01-01

    Boron neutron capture therapy (BNCT) of cancer depends on the selective delivery of a sufficient number of boron-10 (10B) atoms to individual tumor cells. Cell killing results from the 10B (n, α)7Li neutron capture and fission reactions that occur if a sufficient number of 10B atoms are localized in the tumor cells. Intranuclear 10B localization enhances the efficiency of cell killing via damage to the DNA. The net cellular content of 10B atoms reflects both bound and free pools of boron in individual tumor cells. The assessment of these pools, delivered by a boron delivery agent, currently cannot be made at subcellular scale resolution by clinically applicable techniques such as PET and MRI. In this study, secondary ion mass spectrometry (SIMS) based imaging instrument, a CAMECA IMS 3f ion microscope, capable of 500 nm spatial resolution was employed. Cryogenically prepared cultured human T98G glioblastoma cells were evaluated for boron uptake and retention of two delivery agents. The first, L-p-boronophenylalanine (BPA), has been used clinically for BNCT of high grade gliomas, recurrent tumors of the head and neck region and melanomas. The second, a boron analogue of an unnatural amino acid, 1-amino-3-borono-cyclopentanecarboxylic acid (cis-ABCPC), has been studied in rodent glioma and melanoma models by quantification of boron in the nucleus and cytoplasm of individual tumor cells. The bound and free pools of boron were assessed by exposure of cells to boron-free nutrient medium. Both BPA and cis-ABCPC delivered almost 70% of the pool of boron in the free or loosely bound form to the nucleus and cytoplasm of human glioblastoma cells. This free pool of boron could be easily mobilized out of the cell and was in some sort of equilibrium with extracellular boron. In the case of BPA, the intracellular free pool of boron also was affected by the presence of phenylalanine in the nutrient medium. This suggests that it might be advantageous if patients were placed on a

  8. 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)

  9. Quantitative boron detection by neutron transmission method

    International Nuclear Information System (INIS)

    //Quantitative boron detection is mainly performed by chemical methods like colorimetric titration. High neutron absorption cross section of natural boron makes attractive its detection by absorption measurements. This work is an extension of earlier investigations where neutron radiography technique was used for boron detection. In the present investigation, the neutron absorption rate of boron containing solutions is the way to measure quantitatively the boron content of the solutions. The investigation was carried out in Istanbul TRIGA Mark-II reactor. In the end of the experiments, it was observed that even |ppw| grade boron in aqueous solution can be easily detected. The use of this method is certainly very useful for boron utilizing industries like glass and steel industries.The major disadvantage of the method is the obligation to use always aqueous solutions to be able to detect homogeneously the boron content. Then, steel or glass samples have to be put first in an appropriate solution form. The irradiation of steel samples can give the distribution of boron by the help of a imaging and this suggested method will give its quantitative measurement. The superiority of this method are its quick response time and its accuracy. To test this accuracy, a supposed unknown , solution of boric acid is irradiated and then calculated by the help of the calibration curve. The measured value of boric acid was 0.89 mg and the calculated value was found to be 0.98 mg which gives an accuracy of 10 %. It was also seen that the method is more accurate for low concentration. (authors)

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

    Science.gov (United States)

    Rosenberg, David

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

  11. Plasma-assisted Recoil Implantation for Shallow Boron Doping in Silicon

    Science.gov (United States)

    Liu, H. L.; Gearhart, S. S.; Booske, J. H.; Wang, W.

    1997-10-01

    An ion beam mixing technique is used to fabricate ultra-shallow p+/n junctions for the application of sub-micron CMOS source/drain formation. In this method, a thin boron layer is first sputtered onto the Si wafer. Then -3kV argon Plasma Source Ion Implantation (PSII) drives the boron atoms into the Si substrate by means of ion beam mixing. This process avoids the hazardous toxic gases, undesirable F co-implantation and F etching effects. Sub-100nm deep p+/n junctions have been formed with this method. Numerical simulations were performed to predict the recoiled boron profiles, which are in agreement with the experimental data. The boron sputter deposition process has been optimized. Auger electron spectroscopy (AES) confirms high purity of the deposited boron films. Numerical Simulations show that the B films with thickness ranging from 5nm to 10nm result in very similar recoiled B profiles. The thickness of 7.5nm is chosen for the deposited B layer to make the entire process more reproducible. Moreover, a part of the implantation damage will be contained in the B layer, which will be removed prior to the annealing step. This should help to alleviate the transient enhanced B diffusion. The research for the recoil implantation of 7.5nm thick B layer is currently underway.

  12. Sintering of boron carbide (B4C)

    International Nuclear Information System (INIS)

    Boron carbide (B4C) is used as a control element in different types of reactors due to the high fast and thermal neutron absorption cross-section of B-10. Requirements of the Advanced Reactor Division of the Bariloche Atomic Center triggered the study of the possibilities of fabricating B4C pellets by cold-pressing and sintering. The results of essays of sinterability of two different commercial boron carbide powders, sintered at temperatures between 1200 and 2200 deg C, are given. Characterizations of the samples were made to determine the evolution of density, porosity, microstructure and boron content as a function of sintering temperature. (Author)

  13. Developments in boron magnetic resonance imaging (MRI)

    Energy Technology Data Exchange (ETDEWEB)

    Schweizer, M.

    1995-11-01

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

  14. 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.

  15. Boron site preference in ternary Ta and Nb boron silicides

    International Nuclear Information System (INIS)

    X-ray single crystal (XSC) and neutron powder diffraction data (NPD) were used to elucidate boron site preference for five ternary phases. Ta3Si1−xBx (x=0.112(4)) crystallizes with the Ti3P-type (space group P42/n) with B-atoms sharing the 8g site with Si atoms. Ta5Si3−x (x=0.03(1); Cr5B3- type) crystallizes with space group I4/mcm, exhibiting a small amount of vacancies on the 4a site. Both, Ta5(Si1−xBx)3, x=0.568(3), and Nb5(Si1−xBx)3, x=0.59(2), are part of solid solutions of M5Si3 with Cr5B3-type into the ternary M–Si–B systems (M=Nb or Ta) with B replacing Si on the 8h site. The D88-phase in the Nb–Si–B system crystallizes with the Ti5Ga4-type revealing the formula Nb5Si3B1−x (x=0.292(3)) with B partially filling the voids in the 2b site of the Mn5Si3 parent type. - Graphical abstract: The crystal structures of a series of compounds have been solved from X-ray single crystal diffractometry revealing details on the boron incorporation. Highlights: ► Structure of a series of compounds have been solved by X-ray single crystal diffractometry. ► Ta3(Si1−xBx) (x=0.112) crystallizes with the Ti3P-type, B and Si atoms randomly share the 8g site. ► Structure of Nb5Si3B1−x (x=0.292; Ti5Ga4-type) was solved from NPD.

  16. 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...

  17. Determination of boron isotope ratios in boron carbide by mass spectrometry

    International Nuclear Information System (INIS)

    This paper introduces the direct determination of boron isotope ratios in the boron carbide powder by thermal ionization mass spectrometry. The technique for sample loading, the procedure for heating and the eliminating of effects induced by oxygen are studied. The study indicates that the preparing process for the sample will be shorted, and the time for determination and the exposure dose of the laboratory assistant will be reduced for the reason of directly determination of boron carbide. (authors)

  18. Effect of boron concentration on physicochemical properties of boron-doped carbon nanotubes

    International Nuclear Information System (INIS)

    Boron-doped carbon nanotubes (B-CNTs) were synthesized using chemical vapour deposition (CVD) floating catalyst method. Toluene was used as the carbon source, triphenylborane as boron as well as the carbon source while ferrocene was used as the catalyst. The amount of triphenylborane used was varied in a solution of toluene and ferrocene. Ferrocene was kept constant at 2.5 wt.%. while a maximum temperature of 900 °C was used for the synthesis of the shaped carbon nanomaterial (SCNMs). SCNMs obtained were characterized by the use of transmission electron microscope (TEM), scanning electron microscope (SEM), high resolution-electron microscope, electron dispersive X-ay spectroscopy (EDX), Raman spectroscopy, inductively coupled plasma-optical emission spectroscopy (ICP-OES), vibrating sample magnetometer (VSM), nitrogen adsorption at 77 K, and inverse gas chromatography. TEM and SEM analysis confirmed SCNMs obtained were a mixture of B-CNTs and carbon nanofibres (B-CNF). EDX and ICP-OES results showed that boron was successively incorporated into the carbon hexagonal network of CNTs and its concentration was dependent on the amount of triphenylborane used. From the VSM results, the boron doping within the CNTs introduced ferromagnetic properties, and as the percentage of boron increased the magnetic coactivity and squareness changed. In addition, boron doping changed the conductivity and the surface energy among other physicochemical properties of B-CNTs. - Highlights: • Boron-doping of carbon nanotubes (CNTs) changes their physiochemical properties. • Amount of boron-doping was dependent on the wt.% of boron precursor used. • Boron-doping changed CNTs surfaces and the distribution of dispersive energy sites. • Boron-doping affected the conductivity and ferromagnetic properties. • Increased boron-doping results in a more favourable interaction with polar probes

  19. Study of boron detection limit using the in-air PIGE set-up at LAMFI-USP

    Science.gov (United States)

    Moro, M. V.; Silva, T. F.; Trindade, G. F.; Added, N.; Tabacniks, M. H.

    2014-11-01

    The quantification of small amounts of boron in materials is of extreme importance in different areas of materials science. Boron is an important contaminant and also a silicon dopant in the semiconductor industry. Boron is also extensively used in nuclear power plants, either for neutron shielding or for safety control and boron is an essential nutrient for life, either vegetable or animal. The production of silicon solar cells, by refining metallurgical-grade silicon (MG-Si) requires the control and reduction of several silicon contaminants to very low concentration levels. Boron is one of the contaminants of solar-grade silicon (SG-Si) that must be controlled and quantified at sub-ppm levels. In the metallurgical purification, boron quantification is usually made by Inductive Coupled Plasma Mass Spectrometry, (ICP-MS) but the results need to be verified by an independent analytical method. In this work we present the results of the analysis of silicon samples by Particle Induced Gamma-Ray Emission (PIGE) aiming the quantification of low concentrations of boron. PIGE analysis was carried out using the in-air external beam line of the Laboratory for Materials Analysis with Ion Beans (LAMFI-USP) by the 10B ( p ,αγ(7Be nuclear reaction, and measuring the 429 keV γ-ray. The in-air PIGE measurements at LAMFI have a quantification limit of the order of 1016 at/cm2.

  20. Influence of boron addition to Ti–13Zr–13Nb alloy on MG63 osteoblast cell viability and protein adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Majumdar, P., E-mail: m.pallab@gmail.com [School of Mechanical Science, Indian Institute of Technology, Bhubaneswar (India); Singh, S.B. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur (India); Dhara, S. [School Medical Science and Technology, Indian Institute of Technology, Kharagpur (India); Chakraborty, M. [School of Mechanical Science, Indian Institute of Technology, Bhubaneswar (India)

    2015-01-01

    Cell proliferation, cell morphology and protein adsorption on near β-type Ti–13Zr–13Nb (TZN) alloy and Ti–13Zr–13Nb–0.5B (TZNB) composite have been investigated and compared to evaluate the effect of boron addition which has been added to the Ti alloy to improve their poor tribological properties by forming in situ TiB precipitates. MG63 cell proliferation on substrates with different chemistry but the same topography was compared. The MTT assay test showed that the cell viability on the TZN alloy was higher than the boron containing TZNB composite after 36 h of incubation and the difference was pronounced after 7 days. However, both the materials showed substantially higher cell attachment than the control (polystyrene). For the same period of incubation in fetal bovine serum (FBS), the amount of protein adsorbed on the surface of boron free TZN samples was higher than that in the case of boron containing TZNB composite. The presence of boron in the TZN alloy influenced protein adsorption and cell response and they are lower in TZNB than in TZN as a result of the associated difference in chemical characteristics. - Highlights: • The influence of boron addition on biocompatibility of Ti–13Zr–13Nb • Boron forms in situ TiB in TZN matrix and decreases cell proliferation on TZN surfaces. • Protein adsorption is lower in TZNB than in TZN. • Compared to TZNB composite, TZN alloy is more suitable for bone grafting applications.

  1. Green synthesis of boron doped graphene and its application as high performance anode material in Li ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, Madhumita; Sreena, K.P.; Vinayan, B.P.; Ramaprabhu, S., E-mail: ramp@iitm.ac.in

    2015-01-15

    Graphical abstract: Boron doped graphene (B-G), synthesized by simple hydrogen induced reduction technique using boric acid as boron precursor, have more uneven surface as a result of smaller bonding distance of boron compared to carbon, showed high capacity and high rate capability compared to pristine graphene as an anode material for Li ion battery application. - Abstract: The present work demonstrates a facile route for the large-scale, catalyst free, and green synthesis approach of boron doped graphene (B-G) and its use as high performance anode material for Li ion battery (LIB) application. Boron atoms were doped into graphene framework with an atomic percentage of 5.93% via hydrogen induced thermal reduction technique using graphite oxide and boric acid as precursors. Various characterization techniques were used to confirm the boron doping in graphene sheets. B-G as anode material shows a discharge capacity of 548 mAh g{sup −1} at 100 mA g{sup −1} after 30th cycles. At high current density value of 1 A g{sup −1}, B-G as anode material enhances the specific capacity by about 1.7 times compared to pristine graphene. The present study shows a simplistic way of boron doping in graphene leading to an enhanced Li ion adsorption due to the change in electronic states.

  2. 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

  3. Boron

    International Nuclear Information System (INIS)

    This paper reports that borate minerals and refined borates are used extensively for the manufacture of vitreous materials such as insulation and textile fiberglasses, borosilicate glass, and porcelain enamels and frits. In North America, these applications are estimated to account for over 54% of the borate consumption. Other substantial uses are in soaps and detergents, metallurgy, fire retardants, industrial biocides, agriculture, and various miscellaneous applications. Reported domestic borate consumption in 1990 was estimated by the U.S. Bureau of Mines to be 320 000 metric tons B2O3 versus 354 000 metric tons B2O3 in 1989. Consumption is projected to remain essentially static in 1991. Imports were estimated by the Bureau to be 50 000 metric tons B2O3 in 1990. Exports of boric acid and refined borates were approximately 650 000 metric tons of product, a 15 000 metric ton increase from the 1989 level. This increase partially offsets the drop in the 1990 consumption level

  4. Studies of boron hydrides: new heteroboranes

    International Nuclear Information System (INIS)

    I. The chemistry of the bipentaborane 2,2'-(B5H8)2 is investigated to some extent. Pyrolysis of 2,2'-(B5H8)2 resulted in the formation of non-volatile solid boron hydrides and hydrogen. Treatment of 2,2'-(B5H8)2 with bromine in the presence of AlBr3 resulted in the isolation of 1,1'Br2-2,2'-(B5H7)2. Reaction of 2,2'-(B5H8)2 with deprotonating agents resulted in the formation of the corresponding anions. Reaction of 2,2'-(B5H8)2 with diborane followed by acidification afforded n-B9H15 and B10H14 in moderate yield. II. Reaction of K+B9H12S- with potassium polyselenide resulted in the isolation of stable white crystals of B9H9SSe. Treatment of B9H9SSe with one equivalent of base in methanol gave the unstable heteroborane B8H9(OCH3)SSE and treatment with two equivalents of base afforded yellow crystals of B7H9SSe. Reaction of K+B9H12S- with arsenic trioxide in aqueous basic solution gave the electron-rich heteroborane, B8H8As2S in moderate yield. This resulted in the isolation and identification of Et3N.BH3 and the new metalloborane B7H7As2SCo(C5H5). Treatment of B10H11Se- with As2O3 resulted in the isolation of the stable nido-heteroborane B8H8As2Se in low yield. Reaction of B7C2H13 with potassium polyselenide gave the arachno selenacarborane B7H2C11Se in low yield. The structure of the new heteroborane is proposed on the basis of 11B and 1H nmr spectra. Reaction of B7C2H13 with AsCl3 resulted in the isolation of white stable crystals of B7C2H9As2 in 40 percent yield

  5. Boron-isotope fractionation in plants

    International Nuclear Information System (INIS)

    Naturally-occurring variations in the abundance of stable isotopes of carbon, nitrogen, oxygen, and other elements in plants have been reported and are now used to understand various physiological processes in plants. Boron (B) isotopic variation in several plant species have been documented, but no determination as to whether plants fractionate the stable isotopes of boron, 11B and 10B, has been made. Here, we report that plants with differing B requirements (wheat, corn and broccoli) fractionated boron. The whole plant was enriched in 11B relative to the nutrient solution, and the leaves were enriched in 10B and the stem in 11B relative to the xylem sap. Although at present, a mechanistic role for boron in plants is uncertain, potential fractionating mechanisms are discussed. (author)

  6. Synthesis of Boron-Containing Primary Amines

    Directory of Open Access Journals (Sweden)

    Sheng-Hsuan Chung

    2013-10-01

    Full Text Available In this study, boron-containing primary amines were synthesized for use as building blocks in the study of peptoids. In the first step, Gabriel synthesis conditions were modified to enable the construction of seven different aminomethylphenyl boronate esters in good to excellent yields. These compounds were further utilized to build peptoid analogs via an Ugi four-component reaction (Ugi-4CR under microwave irradiation. The prepared Ugi-4CR boronate esters were then successfully converted to the corresponding boronic acids. Finally, the peptoid structures were successfully modified by cross-coupling to aryl/heteroaryl chlorides via a palladium-mediated Suzuki coupling reaction to yield the corresponding derivatives in moderate to good yields.

  7. Boron toxicity in oil palm (Elaeis guineensis)

    Energy Technology Data Exchange (ETDEWEB)

    Rajaratnam, J.A.

    1973-01-01

    Potted oil palms were treated with fertilizer of borate-46 at several concentrations and the plants were observed for boron toxicity effects. Toxicity symptoms were apparent at high rates but not at rates equivalent to typical Malaysian soils.

  8. 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

  9. 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

  10. Boron neutron capture therapy. What is next?

    International Nuclear Information System (INIS)

    BNCT (Boron Neutron Capture Therapy) will have difficulties establishing itself without efficient and conclusive clinical trials of glioma, without the expansion to other tumors, and without efficient programs for compound development and testing. (author)

  11. Ni doping of semiconducting boron carbide

    International Nuclear Information System (INIS)

    The wide band gap, temperature stability, high resistivity, and robustness of semiconducting boron carbide make it an attractive material for device applications. Undoped boron carbide is p type; Ni acts as a n-type dopant. Here we present the results of controlled doping of boron carbide with Ni on thin film samples grown using plasma enhanced chemical vapor deposition. The change in the dopant concentration within the thin film as a function of the dopant flow rate in the precursor gas mixture was confirmed by x-ray photoelectron spectroscopy measurements; with increasing dopant concentration, current-voltage (I-V) curves clearly establish the trend from p-type to n-type boron carbide.

  12. Analysis of boron at Koeberg Power Station

    International Nuclear Information System (INIS)

    Soluble reactivity poisons, also called chemical shim, produce spatially uniform neutron absorption when dissolved in reactor coolant water. The boron-10 isotope having a high neutron absorption coefficient is used in commercial pressurised water reactors (PWR) to limit and control reactivity. This is achieved at Koeberg Nuclear Power Station (KNPS) and the majority of commercial PWR's worldwide by the addition of natural boric acid to the reactor coolant. The boric acid dissolved in the coolant decreases the thermal utilisation factor, causing a decrease in reactivity. By varying the concentration of boric acid (and hence also the B-10 concentration) in the coolant, a process referred to as boration and dilution, the reactivity of the core can be easily managed. An increase in boron concentration (boration) creates negative reactivity and if the boron concentration is reduced (dilution), positive reactivity is added. The changing of boron concentration in a PWR is used primarily to compensate for fuel burn-up or poison build-up. The variation in boron concentration allows control rod use to be minimised, which results in a flatter flux profile over the core than can be produced by control rod manipulation. Accurate laboratory and on-line chemical analysis of boron concentration is important because of its operational implications associated with reactivity control and also for nuclear safety. In a normal fuel cycle, as the nuclear fuel is being consumed, the reactor coolant boric acid (B-10) concentration must be reduced by dilution with purified water to maintain the reactor at constant power. Besides in the reactor coolant water, boric acid concentration is also important in the chemical and volume control system and reactor make-up system for operation. For nuclear safety, boric acid concentrations are technical specification parameters, maintained and monitored in the spent fuel system and safety injection systems. Boron concentration determination is

  13. 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

  14. 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...

  15. 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 ...

  16. A neutron diffraction study of amorphous boron

    Science.gov (United States)

    Delaplane, R. G.; Lundström, T.; Dahlborg, U.; Howells, W. S.

    1991-07-01

    The structure of amorphous boron has been studied with pulsed neutron diffraction techniques using the ISIS facilities at the Rutherford Appleton Laboratory. The experimental static structure factor S(Q) and radial distribution function support a structural model based on units of B12 icosahedra resembling those found in crystalline β-rhombohedral boron, but with a certain degree of disorder occurring in the linking between these subunits.

  17. Pyrolytic synthesis of boron-doped graphene and its application as electrode material for supercapacitors

    International Nuclear Information System (INIS)

    Highlights: • Boron-doped graphene was prepared by pyrolysis of graphene oxide with boric acid at 900 °C under an argon atmosphere. • The boron doping content reached the highest value of 4.7% after 3 h of pyrolysis at 900 °C. • The BG-900-3h electrode exhibited the highest specific capacitance of 172.5 F g−1 at 0.5 A g−1 and maintained 96.5% of initial capacity after a continuous of 5000 times cycling. -- Abstract: Chemical doping with foreign atoms is an effective approach to intrinsically modify the properties of the carbon materials. Herein, boron-doped graphene (BG) was prepared through pyrolysis of graphene oxide (GO) with boric acid (H3BO3) in an argon atmosphere at 900 °C. Both boron-doping and reduction of GO to graphene were simultaneously achieved under the thermal treatment processing. Namely, at high temperature condition, H3BO3 was converted into boron oxide (B2O3) accompanied by diffusing B2O3 vapor into the graphene nanosheets, then boron atoms can replace the carbon atoms inside the graphene layers and thereby substitutionally doped into the graphene lattice. The boron content in BG increased with prolonging the reaction time and reached the highest value of 4.7% after 3 h of pyrolysis, which in turn affected their electrochemical properties. The as-prepared electrode of BG-900-3h exhibits the highest capacitive behavior (172.5 F g−1, 0.5 A g−1) and superior cycling stability (maintaining 96.5% of initial capacity after 5000 times of cycling). Remarkably, the boron-doping increased the capacitance of BG-900-3h by about 80% compared to pristine graphene. These results imply that the doping of boron into graphene lattice induces remarkable performance enhancement, and thus make the doped materials superior to those of pristine graphene as electrode materials for supercapacitors

  18. 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

  19. Amorphous boron nitride at high pressure

    Science.gov (United States)

    Durandurdu, Murat

    2016-06-01

    The pressure-induced phase transformation in hexagonal boron nitrite and amorphous boron nitrite is studied using ab initio molecular dynamics simulations. The hexagonal-to-wurtzite phase transformation is successfully reproduced in the simulation with a transformation mechanism similar to one suggested in experiment. Amorphous boron nitrite, on the other hand, gradually transforms to a high-density amorphous phase with the application of pressure. This phase transformation is irreversible because a densified amorphous state having both sp3 and sp2 bonds is recovered upon pressure release. The high-density amorphous state mainly consists of sp3 bonds and its local structure is quite similar to recently proposed intermediate boron nitrite phases, in particular tetragonal structure (P42/mnm), rather than the known the wurtzite or cubic boron nitrite due to the existence of four membered rings and edge sharing connectivity. On the basis of this finding we propose that amorphous boron nitrite might be best candidate as a starting structure to synthesize the intermediate phase(s) at high pressure and temperature (probably below 800 °C) conditions.

  20. 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.

  1. 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.

  2. 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.

  3. Boron delivery with liposomes for boron neutron capture therapy (BNCT): biodistribution studies in an experimental model of oral cancer demonstrating therapeutic potential

    Energy Technology Data Exchange (ETDEWEB)

    David W. Nigg

    2012-05-01

    Boron neutron capture therapy (BNCT) combines selective accumulation of 10B carriers in tumor tissue with subsequent neutron irradiation. We previously demonstrated the therapeutic efficacy of BNCT in the hamster cheek pouch oral cancer model. Optimization of BNCT depends largely on improving boron targeting to tumor cells. Seeking to maximize the potential of BNCT for the treatment for head and neck cancer, the aim of the present study was to perform boron biodistribution studies in the oral cancer model employing two different liposome formulations that were previously tested for a different pathology, i.e., in experimental mammary carcinoma in BALB/c mice: (1) MAC: liposomes incorporating K[nido-7-CH3(CH2)15-7,8-C2B9H11] in the bilayer membrane and encapsulating a hypertonic buffer, administered intravenously at 6 mg B per kg body weight, and (2) MAC-TAC: liposomes incorporating K[nido-7-CH3(CH2)15-7,8-C2B9H11] in the bilayer membrane and encapsulating a concentrated aqueous solution of the hydrophilic species Na3 [ae-B20H17NH3], administered intravenously at 18 mg B per kg body weight. Samples of tumor, precancerous and normal pouch tissue, spleen, liver, kidney, and blood were taken at different times post-administration and processed to measure boron content by inductively coupled plasma mass spectrometry. No ostensible clinical toxic effects were observed with the selected formulations. Both MAC and MAC-TAC delivered boron selectively to tumor tissue. Absolute tumor values for MAC-TAC peaked to 66.6 {+-} 16.1 ppm at 48 h and to 43.9 {+-} 17.6 ppm at 54 h with very favorable ratios of tumor boron relative to precancerous and normal tissue, making these protocols particularly worthy of radiobiological assessment. Boron concentration values obtained would result in therapeutic BNCT doses in tumor without exceeding radiotolerance in precancerous/normal tissue at the thermal neutron facility at RA-3.

  4. A study of boron determination in high purity aluminium by capture gamma-ray measurement

    International Nuclear Information System (INIS)

    The boron content in reactor grade aluminium has been determined by means of a capture gamma-ray counting method. The experimental detection limit is found to be 5.7 ppm with 10% uncertainty. In order to improve the sensitivity, the boron is preconcentrated from aluminium by cation exchange resin system. The accuracies of both methods, i.e., one by the direct measurement and the other by the measurement after preconcentration, are checked by an additive method. The results show good agreements with less than 5% deviation. (author)

  5. Boronated porphyrins in NCT: Results with a new potent tumor localizer

    International Nuclear Information System (INIS)

    Several chemical methods are available for the solubilization of boronated porphyrins. We have previously reported the tumor localization of nido carboranyl porphyrins in which the icosahedral carborane cages have been opened to give B9C2 anions. One of these species has shown tumor boron levels of nearly 50 μg B/g when delivered by week-long subcutaneous infusions. We report here recent in vivo experiments with a new, highly water-soluble porphyrin based on the hematoporphyrin-type of compound in which aqueous solubility is achieved using the two propionic acid side chains of the ''natural'' porphyrin frame. 7 refs

  6. (n,α) Reaction study with LR-115 for binary glass metal boron distribution

    International Nuclear Information System (INIS)

    Binary glass metal (Fe75B25) theories of glass formation require boron distribution knowledge; this can be achieved by thermal neutron α-radiography employing the 10B(n,α)7Li reaction and LR-115 detectors. Non-uniform distribution within up to a depth of 1.4μm is observed

  7. Site-specific synthesis of a hybrid boron-graphene salt.

    Science.gov (United States)

    Kahlert, Jan U; Austin, Christopher J D; Hall, Andrew J; Rawal, Aditya; Hook, James M; Rendina, Louis M; Choucair, Mohammad

    2016-01-21

    We report the first example of an ionic graphene salt containing boron. An anionic charge is introduced to the graphene surface by means of 7,8-nido-[C2B9H11](-) carborane clusters covalently and electronically bound to the graphene lattice, and this new material was isolated as its Cs(+) salt. PMID:26627051

  8. Determination of boron concentration in oilfield water with a microfluidic ion exchange resin instrument.

    Science.gov (United States)

    Floquet, Cedric F A; Sieben, Vincent J; MacKay, Bruce A; Mostowfi, Farshid

    2016-07-01

    We developed and validated a microfluidic instrument for interference-free determination of boron in produced water. The instrument uses a boron-specific chelating resin to separate the analyte from its complex matrix. Ten produced water samples were analyzed with the instrument and the results were successfully validated against ICP-MS measurements. Removing interference effects enables precise boron measurement for wastewater even with high total dissolved solid (TDS) levels. 1,4-Piperazinediethanesulfonic acid conditions the resin and maintains the optimum pH for boron adsorption from the sample. Boron is then eluted from the resin using a 10% sulfuric acid solution and its concentration measured with the colorimetric carminic acid assay in 95% sulfuric acid. The use of a microfluidic mixer greatly enhances the sensitivity and kinetics of the carminic acid assay, by factors of 2 and 7.5, respectively, when compared against the same assay performed manually. A maximum sensitivity of 2.5mg(-1)L, a precision of 4.2% over the 0-40.0mgL(-1) measuring range, a 0.3mgL(-1) limit of detection, and a sampling rate of up to four samples per hour were achieved. Automation and microfluidics reduce the operator workload and fluid manipulation errors, translating into safer and higher-quality measurements in the field. PMID:27154679

  9. Tuning the electronic properties of armchair carbon nanoribbons by a selective boron doping

    International Nuclear Information System (INIS)

    Armchair carbon nanoribbons (ACNRs) substitutionally doped with boron atoms are investigated in the framework of first-principles density functional theory. Different boron-boron arrangements and concentrations are considered in order to simulate possible aggregation patterns, their structural stability and electronic behavior are determined as a function of ribbon size. In agreement with previous studies, our results show that the dopant atoms have in general a preference for edge sites, but specific effects appear as a function of concentration that importantly modify the properties of the ribbons compared to the pristine case. Interesting tendencies are discovered as a function of dopant concentration that significantly affect the electronic properties of the ribbons. We have found that BC3 island formation and edge doping are the most important factors for the structural stabilization of the ribbons with high boron concentration (>7%) whereas for the cases of low boron concentrations (3 island patterns give rise to highly localized B states on top of the Fermi level, resulting in semiconducting behavior. On the other hand, when the average distance between the B atoms increases beyond island stoichiometry, the localization of their states is reduced and the ribbons may become metallic due to a band crossing caused by the lowering of the Fermi level resulting from the positive charge doping. Thus, tuning the dopant interaction would be an appropriate way to tailor the electronic properties of the ribbons in a convenient manner in view of potential technological applications.

  10. Boron imaging with a microstrip silicon detector for applications in BNCT

    International Nuclear Information System (INIS)

    Boron Neutron Capture Therapy (BNCT) is a radiotherapic technique exploiting the α particles produced after the irradiation of the isotope 10 of boron with thermal neutrons in the capture reaction 10B(n,α)7Li. It is used to treat tumours that for their features (radioresistance, extension, localization near vital organs) cannot be treated through conventional photon-beams radiotherapy. One of the main limitations of this technique is the lack of specificity (i.e. the ability of localizing in tumour cells, saving the healthy tissues) of the compounds used to carry the 10B isotope in the organs to be treated. This work, developed in the framework of the INFN PhoNeS project, describes the possibility of boron imaging performed exploiting the neutrons photoproduced by a linac (the Clinac 2100C/D of the S. Anna Hospital Radiotherapy Unit in Como, Italy) and detecting the α s with a non-depleted microstrip silicon detector: the result is a 1D scan of the boron concentration. Several boron doped samples have been analysed, from solutions of H3BO3 (reaching a minimum detectable amount of 25 ng of 10B) to biological samples of urine containing BPA and BSH (the two molecules currently used for the clinical trials in BNCT) in order to build kinetic curves (showing the absolute 10B concentration as a function of time). Further measurements are under way to test the imaging system with 10BPA-Fructose complex perfused human lung samples.

  11. 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

  12. Development of magnetic resonance technology for noninvasive boron quantification

    International Nuclear Information System (INIS)

    Boron magnetic resonance imaging (MRI) and spectroscopy (MRS) were developed in support of the noninvasive boron quantification task of the Idaho National Engineering Laboratory (INEL) Power Burst Facility/Boron Neutron Capture Therapy (PBF/BNCT) program. The hardware and software described in this report are modifications specific to a GE Signa trademark MRI system, release 3.X and are necessary for boron magnetic resonance operation. The technology developed in this task has been applied to obtaining animal pharmacokinetic data of boron compounds (drug time response) and the in-vivo localization of boron in animal tissue noninvasively. 9 refs., 21 figs

  13. A novel method of boron delivery using sodium iodide symporter for boron neutron capture therapy

    International Nuclear Information System (INIS)

    Boron Neutron Capture Therapy (BNCT) effectiveness depends on the preferential sequestration of boron in cancer cells relative to normal tissue cells. We present a novel strategy for sequestering boron using an adenovirus expressing the sodium iodide symporter (NIS). Human glioma grown subcutaneously in athymic mice and orthotopic rat brain tumors were transfected with NIS using a direct tumor injection of adenovirus. Boron bound as sodium tetrafluoroborate (NaBF4) was administered systemically several days after transfection. Tumors were excised hours later and assessed for boron concentration using inductively coupled plasma atomic emission spectroscopy. In the human glioma transfected with NIS, boron concentration was more than 10 fold higher with 100 mg/kg of NaBF4, compared to tumor not transfected. In the orthotopic tumor model, the presence of NIS conferred almost 4 times the boron concentration in rat tumors transfected with human virus compared with contralateral normal brain not transfected. We conclude that adenovirus expressing NIS has the potential to be used as a novel boron delivery agent and should be explored for future clinical applications. (author)

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

    International Nuclear Information System (INIS)

    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 10B in tumour cells after injection of a boron compound (in our case B12H11SH, 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. Laser-initiated primary and secondary nuclear reactions in Boron-Nitride

    Science.gov (United States)

    Labaune, C.; Baccou, C.; Yahia, V.; Neuville, C.; Rafelski, J.

    2016-02-01

    Nuclear reactions initiated by laser-accelerated particle beams are a promising new approach to many applications, from medical radioisotopes to aneutronic energy production. We present results demonstrating the occurrence of secondary nuclear reactions, initiated by the primary nuclear reaction products, using multicomponent targets composed of either natural boron (B) or natural boron nitride (BN). The primary proton-boron reaction (p + 11B → 3 α + 8.7 MeV), is one of the most attractive aneutronic fusion reaction. We report radioactive decay signatures in targets irradiated at the Elfie laser facility by laser-accelerated particle beams which we interpret as due to secondary reactions induced by alpha (α) particles produced in the primary reactions. Use of a second nanosecond laser beam, adequately synchronized with the short laser pulse to produce a plasma target, further enhanced the reaction rates. High rates and chains of reactions are essential for most applications.

  17. Superconductivity in boron carbide? Clarification by low-temperature MIR/FIR spectra.

    Science.gov (United States)

    Werheit, H; Kuhlmann, U

    2011-11-01

    The electronic structure and phonon density of B(13)B(2) boron carbide calculated by Calandra et al (2004 Phys. Rev. B 69 224505) defines this compound as metallic, and the authors predict superconductivity with T(C)s up to 36.7 K. Their results are affected by the same deficiencies as former band structure calculations on boron carbides based on hypothetical crystal structures deviating significantly from the real ones. We present optical mid IR/far IR (MIR/FIR) spectra of boron carbide with compositions between B(4.3)C and B(10.37)C, evidencing semiconducting behaviour at least down to 30 K. There is no indication of superconductivity. The spectra yield new information on numerous localized gap states close to the valence band edge. PMID:21997120

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

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2004-01-01

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

  19. 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.

  20. Photon energy absorption parameters for composite mixtures with boron compounds

    International Nuclear Information System (INIS)

    Highlights: → An experimental investigation of photon energy absorption parameters for 12 composite mixture samples with boron compounds. → Calculations of total mass attenuation coefficients and effective atomic numbers for the energy up to 100 keV. → Radiation shielding properties varied with concentration of composite materials. → In general, the mixture with K2B4O7· 4H2O is more absorber than with H3BO3. - Abstract: Boron compounds that are used in the manufacturing of a variety of products are introduced to the environment in the form of waste. The radiation shielding measurements of mixtures that contain boron compounds is considered to be a topic of concern. The mass attenuation coefficients of (PbO and K2B4O7.4H2O) and (PbO and H3BO3) as functions of their changing contents have been measured in the X-ray energy range from 25.191 to 57.903 keV. These values are used to determine the effective atomic number of mixtures. The γ-rays emitted from an Am241 annular source have been sent to secondary sources whose characteristic X-rays have been used for transmission arrangement. The characteristic X-rays of the secondary sources have been counted by a Si(Li) detector with a resolution of 149 eV at 5.9 keV. Also, the total effective atomic number of each mixture was determined by using the mixture rule. The measured values were compared with theoretically calculated values.

  1. Boron-11 NMR spectroscopy of excised mouse tissues after infusion of boron compound used in neutron capture therapy

    International Nuclear Information System (INIS)

    Boron neutron capture therapy (BNCT) is based on selective boron uptake by the tumor and in situ activation by neutron beam. The authors propose the use of B-11 MR spectroscopy to noninvasively study boron uptake in animal tumor models. Sodium mercaptoundeca-hydrododecaborate was infused into female BALB/cJ mice and liver, brain, spleen, kidney, and tumor tissues were excised for MR (27.4MHz) and total boron content measurements. Boron-11 was easily detectable in tumor, liver, spleen, and skin. The results gave a very good correlation (correlation coefficient of .997) between B-11 MR measurements and total boron content of excised mouse tissues

  2. Application of drug delivery system for boron neutron capture therapy. Basic research toward clinical application

    International Nuclear Information System (INIS)

    Tumour cell destruction in boron neutron-capture therapy (BNCT) is due to the nuclear reaction between 10B and thermal neutrons (10B+1n → 7Li+4He (α) +2.31 MeV (93.7%)/2.79 MeV (6.3%)). The resulting lithium ions and αparticles are high linear energy transfer (LET) particles which give high biological effect. Their short range in tissue (5-9 μm) restricts radiation damage to those cells in which boron atoms are located at the time of neutron irradiation. BNCT has been applied clinically for the treatment of malignant brain tumors, malignant melanoma, head and neck cancer and hepatoma etc, recently. Sodium borocaptate (Na210B12H11SH; BSH) and borono-phenylalanine (10BPA) are currently being used in clinical treatments. To achieve the selective delivery of boron atoms to cancer cells, drug delivery system (DDS) becomes an attractive intelligent technology as targeting and controlled release of drugs. We have firstly reported that 10B atoms delivered by immunoliposomes are cytotoxic to human pancreatic carcinoma cells (AsPC-1) after thermal neutron irradiation in vitro. The intra-tumoural injection of boronated immunoliposomes can increase the retention of 10B atoms in tumour cells, causing suppression of tumour growth in vivo following thermal neutron irradiation. We prepared polyethylene-glycol binding liposomes (PEG-liposomes) as an effective 10B carrier to obviate phagocytosis by reticuloendotherial systems. We had prepared 10BSH entrapped Water-in-Oil-in-Water (WOW) emulsion. The 10B concentration in VX-2 tumour after intra-arterial injection of 10BSH entrapped WOW emulsion was superior to the groups of 10BSH entrapped conventional Lipiodol mix emulsion. 10Boron entrapped WOW emulsion is one of the most useful for intra-arterial boron delivery carrier on BNCT to hepatocellular carcinoma. (author)

  3. Simultaneous determination of boron-10 and boron-11 under proton bombardment

    International Nuclear Information System (INIS)

    The isotopic analysis of boron gained importance with increased use of boron-10 in nuclear technology. Former techniques for determining the stable boron isotope either were limited to the determination of a single isotope or required tedious experimental prodecure. The use of proton induced reactions was therefore investigated as an alternative method for the simultaneous analysis of both stable isotopes of boron through a relatively simple experimental procedure. Aqueous solutions of natural boric acid (19,78 at. % 10B) and enriched boric acid (92,41 at. % 10B) were mixed and evaporated to dryness in order to obtain samples in which the isotopic concentration of boron was known. Thin targets were produced by evaporating boron oxide, converted by heat from the boric acid mixture, onto tantalum backing material. Standard samples with known contents of boron oxide were prepared by dry mixing standard reference boron-containing glass powers in a ball mill. Thick targets containing boron of different isotopic compositions were prepared in matrices of potassium bromide and of ion-exchange resins by mixing the matrix with aqueous solutions of boric acid and of sodium carbonate by fusion with boric oxide. The most intense prompt gamma-rays emitted from boron isotopes under irradiation with protons up to 4,5 MeV were the 428-KeV 10B α(1,0), 718-KeV 10B p(1,0) and the 2124-KeV 11B p(1,0) gamma-rays. Excitation functions for the production of each of these were measured using both thick and thin targets

  4. Boron: out of the sky and onto the ground

    International Nuclear Information System (INIS)

    Now an accepted, engineered material for aerospace applications, boron is taking its place on the ground. Both current production applications, prototype (development) applications, and speculative applications abound. In the leisure product market, boron epoxy or boron aluminum has been used or tried in golf clubs (in combination with graphite epoxy or to reinforce aluminum or steel), in tennis racquets, in bicycles, racing shells, skis and skipoles, bows and arrows, and others. In the industrial area, boron has been used to reduce fatigue, increase stiffness, or for its abrasive properties. Textile machinery, honing tools, and cut off wheels or saws are among the applications. In the medical field, prosthetics and orthotic braces, wheel chairs, canes, and crutches are all good applications for boron. Applications for boron in transportation, construction, and heavy industry are also possible. The volume of boron used in these applications could have a major impact on prices, making boron composite parts cost competitive with conventional materials. (U.S.)

  5. 15th International Conference on Boron Chemistry (IMEBORON XV)

    Czech Academy of Sciences Publication Activity Database

    Grüner, Bohumír; Štíbr, Bohumil

    2015-01-01

    Roč. 87, č. 2 (2015), s. 121. ISSN 0033-4545 Institutional support: RVO:61388980 Keywords : boranes * boron * boron materials * carboranes * IMEBORON XV * medicinal chemistry Subject RIV: CA - Inorganic Chemistry

  6. 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

  7. Interaction of iron with boron in metal-rich metallaboranes resulting in large deshielding and rapid relaxation processes of the boron-11 nucleus

    International Nuclear Information System (INIS)

    A first-order, parameterized model for calculating 11B chemical shifts in metal-rich ferraboranes and a correlation of chemical shift with boron Mulliken populations from Fenske-Hall calculations are presented. These correlations are qualitatively different from those reported earlier for boranes and suggest that direct iron-boron interactions lead to large deshielding due to substantial increases in multiple-bond contributions to the shielding tensor. Relaxation rates have been measured for [Fe4(CO)12BH/sub 3-n/]/sup n-/ (n = 0-2) and correlated with electric field gradients at the boron nucleus estimated from Fenske-Hall calculations. These results demonstrate that formation of the boride, [Fe4(CO)12B]3-, by deprotonation is accompanied by the development of large asymmetries in the electronic charge distribution around the boron nucleus. Finally, 7Li NMR is used to probe the nature of the anions [Fe4(CO)12BH/sub 3-n/]/sup n-/ (n = 1-3), and observed line shapes suggest close association of Li+ with the trianion. 28 references, 3 figures, 4 tables

  8. 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.

  9. Boron isotope fractionation during brucite deposition from artificial seawater

    OpenAIRE

    J. Xiao; Xiao, Y. K.; Liu, C. Q.; Z. D. Jin

    2011-01-01

    Experiments involving boron incorporation into brucite (Mg(OH)2) from magnesium-free artificial seawater with pH values ranging from 9.5 to 13.0 were carried out to better understand the incorporation behavior of boron into brucite. The results show that both concentration of boron in deposited brucite ([B]d) and its boron partition coefficient (Kd) between deposited brucite and final seawater are controll...

  10. 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.

  11. 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

  12. Glass manufacturing process having boron and fluorine pollution abating features

    Energy Technology Data Exchange (ETDEWEB)

    Froberg, M.L.; Schroeder, C.F.

    1981-11-03

    Boron and/or fluorine values are reclaimed from a boron and/or fluorine laden gas stream emanating from a glass melter by means of a preheating bed of glass-forming batch agglomerates. The boron and/or fluorine values in such gases are first reacted with a boron and/or fluorine reactive material and the gases then conveyed into such a preheating bed to separate at least a portion of the reaction products.

  13. Glass manufacturing process having boron and fluorine pollution abating features

    International Nuclear Information System (INIS)

    Boron and/or fluorine values are reclaimed from a boron and/or fluorine laden gas stream emanating from a glass melter by means of a preheating bed of glass-forming batch agglomerates. The boron and/or fluorine values in such gases are first reacted with a boron and/or fluorine reactive material and the gases then conveyed into such a preheating bed to separate at least a portion of the reaction products

  14. Synthesis of multiwall boron nitride nanotubes dependent on crystallographic structure of boron

    International Nuclear Information System (INIS)

    Synthesis and growth of multiwall boron nitride nanotubes (BNNTs) under the B and ZrO2 seed system in the milling–annealing process were investigated. BNNTs were synthesized by annealing a mechanically activated boron powder under nitrogen environment. We explored the aspects of the mechanical activation energy transferred to milled crystalline boron powder producing structural disorder and borothermal reaction of the ZrO2 seed particles on the synthesis of BNNTs during annealing. Under these circumstances, the chemical reaction of amorphous boron coated on the seed nanoparticles with nitrogen synthesizing amorphous BN could be enhanced. It was found that amorphous BN was crystallized to the layer structure and then grown to multiwall BNNTs during annealing. Especially, bamboo-type multiwall BNNTs were mostly produced and grown to the tail-side of the nanotube not to the round head-side. Open gaps with ∼0.3 nm of the bamboo side walls of BNNTs were also observed. Based on these understandings, it might be possible to produce bamboo-type multiwall BNNTs by optimization of the structure and shape of boron coat on the seed nanoparticles. -- Highlights: ► Structure of B is a key factor for BNNT synthesis for milling–annealing method. ► Amorphous boron is coated on the seed during milling of crystalline boron. ► Amorphous BN nanoclusters are crystallized during annealing. ► Growing of bamboo BNNTs is not to the round head-side but to the tail-side.

  15. Evaluation of Ground-Water and Boron Sources by Use of Boron Stable-Isotope Ratios, Tritium, and Selected Water-Chemistry Constituents near Beverly Shores, Northwestern Indiana, 2004

    Science.gov (United States)

    Buszka, Paul M.; Fitzpatrick, John A.; Watson, Lee R.; Kay, Robert T.

    2007-01-01

    from human-affected boron sources. Boron concentrations in potential ground-water sources of boron were largest (15,700 to 24,400 ?g/L) in samples of CCP-affected surficial aquifer water from four wells at a CCP landfill and smallest (27 to 63 ?g/L) in three wells in the surficial aquifer that were distant from human-affected boron sources. Boron concentrations in water from the basal sand aquifer ranged from 656 ?g/L to 1,800 ?g/L. Boron concentrations in water from three domestic-wastewater-affected surficial aquifer wells ranged from 84 to 387 ?g/L. Among the representative ground-water samples, boron concentrations from all four samples of CCP-affected surficial aquifer water and four of five samples of water from the basal sand aquifer had concentrations greater than the RAL. A comparison of boron concentrations in acid-preserved and unacidified samples indicated that boron concentrations reported for this investigation may be from about 11 to 16 percent less than would be reported in a standard analysis of an acidified sample. The stable isotope boron-11 was most enriched in comparison to boron-10 in ground water from a confined aquifer, the basal sand aquifer (d11B, 24.6 to 34.0 per mil, five samples); it was most depleted in CCP-affected water from the surficial aquifer (d11B, 0.1 to 6.6 per mil, four samples). Domestic-wastewater-affected water from the surficial aquifer (d11B, 8.7 to 11.7 per mil, four samples) was enriched in boron-11, in comparison to individual samples of a borax detergent additive and a detergent with perborate bleach; it was intermediate in composition between basal sand aquifer water and CCP-affected water from the surficial aquifer. The similarity between a ground-water sample from the surficial aquifer and a hypothetical mixture of unaffected surficial aquifer and basal sand aquifer waters indicates the potential for long-term upward discharge of ground water into the surficial aquifer from one or more confined aquifers. Est

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

    Directory of Open Access Journals (Sweden)

    N. F. Nevar

    2016-02-01

    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.

  17. Determination of boron in human serum by inductively coupled plasma mass spectrometry after a simple dilution of the sample

    International Nuclear Information System (INIS)

    A method for the determination of boron in human serum is described. Serum samples were only treated with 0.14 M HNO3 (a five-fold dilution). After addition of beryllium as internal standard to correct for matrix effects, samples were introduced with a concentric nebulizer to an inductively coupled plasma mass spectrometer. The magnitude of the boron ion signal was optimized by adjusting the lens voltages and the nebulizer gas flow rate and memory effects, which can be experienced with the conventional methodology for sample introduction, were reduced to an acceptable level by the use of a short (2 min) cleanout procedure. To avoid the overlap from the intense 12C+-peak with the 11B+-peak, the 10B+-peak was used for the boron determinations. This procedure gave a boron blank level of about 1.7 μg l-1 and a detection limit of 0.5 μg l-1 for human serum. External calibration was applied for the quantitation of boron. The proposed method was tested by analysing a 'second-generation' biological reference material Freeze-Dried Human Serum (University of Ghent). Results are also given for three other biological reference materials, namely Wheat Flour SRM 1567a, Bovine Liver SRM 1577a and Total Diet SRM 1548 (National Institute of Standards and Technology). Analyses of serum samples from twelve healthy individuals yielded boron concentrations ranging from 4.1 to 25.8 μg l-1

  18. Boron isotope composition of geothermal fluids and borate minerals from salar deposits (central Andes/NW Argentina)

    Science.gov (United States)

    Kasemann, Simone A.; Meixner, Anette; Erzinger, Jörg; Viramonte, José G.; Alonso, Ricardo N.; Franz, Gerhard

    2004-06-01

    We have measured the boron concentration and isotope composition of regionally expansive borate deposits and geothermal fluids from the Cenozoic geothermal system of the Argentine Puna Plateau in the central Andes. The borate minerals borax, colemanite, hydroboracite, inderite, inyoite, kernite, teruggite, tincalconite, and ulexite span a wide range of δ11B values from -29.5 to -0.3‰, whereas fluids cover a range from -18.3 to 0.7‰. The data from recent coexisting borate minerals and fluids allow for the calculation of the isotope composition of the ancient mineralizing fluids and thus for the constraint of the isotope composition of the source rocks sampled by the fluids. The boron isotope composition of ancient mineralizing fluids appears uniform throughout the section of precipitates at a given locality and similar to values obtained from recent thermal fluids. These findings support models that suggest uniform and stable climatic, magmatic, and tectonic conditions during the past 8 million years in this part of the central Andes. Boron in fluids is derived from different sources, depending on the drainage system and local country rocks. One significant boron source is the Paleozoic basement, which has a whole-rock isotopic composition of δ11B=-8.9±2.2‰ (1 SD); another important boron contribution comes from Neogene-Pleistocene ignimbrites ( δ11B=-3.8±2.8‰, 1 SD). Cenozoic andesites and Mesozoic limestones ( δ11B≤+8‰) provide a potential third boron source.

  19. Therapeutic efficacy of boron neutron capture therapy mediated by boron-rich liposomes for oral cancer in the hamster cheek pouch model

    International Nuclear Information System (INIS)

    Unilamellar liposomes formulated with an equimolar mixture of cholesterol and 1,2-distearoyl-sn-glycero-3-phosphocholine, incorporating K[nido-7-CH3(CH2)15-7,8-C2B9H11] in the lipid bilayer, and encapsulating Na3[ae-B10-H9)-2-NH3B10H8] were prepared by probe sonication and investigated in vivo. Microwave assisted digestion followed by inductively coupled plasma-optical emission spectroscopy was utilized to determine the biodistribution of boron in various tissues following either a single tail vein injection or two identical injections (separated by 24 hours) of the liposomal suspension in BALB/c mice bearing EMT6 mammary adenocarcinomas in their right flank. Double-injection protocols resulted in a boron content in the tumor exceeding 50 µg of boron per gram of tissue for 48 to 72 hours subsequent to the initial injection while tumor:blood boron ratios were more ideal from 54 hours (1.9:1) to 96 hours (5.7:1) subsequent to the initial injection. Tumor bearing mice were given a double-injection of liposomes containing the 10B-enriched analogs of the aforementioned agents and subjected to a 30 minute irradiation by thermal neutrons with a flux of 8.8 x 108 (±7%) neutrons/cm2 s integrated over the energy range of 0.0 - 0.414 eV. Significant tumor response for a single BNCT treatment was demonstrated by growth curves versus a control group. Vastly diminished tumor growth was witnessed at 14 days (186% increase versus 1551% in controls) in mice that were given a second injection/radiation treatment 7 days after the first. Mice given a one hour neutron irradiation following the double-injection of liposomes had a similar response (169% increase at 14 days) suggesting that neutron fluence is the limiting factor towards BNCT efficacy in this study.

  20. 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.

  1. Boron-containing amino carboxylic acid compounds and uses thereof

    International Nuclear Information System (INIS)

    Novel compounds which are useful for boron neutron capture therapy (BNCT) are disclosed. The compounds comprise a stable boron-containing group and an aminocycloalkane carboxylic acid group or a boronated acyclic hydrocarbon-linked amino carboxylic acid. Methods for synthesis of the compounds and for use of the compounds in BNCT are disclosed

  2. Anomalous electronic transport in boron carbides

    Science.gov (United States)

    Emin, D.; Samara, G. A.; Wood, C.

    The boron carbides are composed of icosahedral units, B12 and B11C1, linked together by strong intericosahedral bonds. With such distributions of icosahedral and intericosahedral compositions, boron carbides, B/sub 1-x/C/sub x/, are single phase over 0.1 less than or equal to x less than or equal to 0.2. The electronic transport properties of the boron carbides were examined within this single-phase region. Results are inconsistent with conventional analyses of both itinerant and hopping transport. Most striking are Seebeck coefficients which are both large and rapidly increasing functions of temperature despite thermally activated dc conductivities. These results manifest the hopping of small bipolaronic holes between carbon-containing icosahedral that are inequivalent in energy and electron-lattice coupling strength. Under hydrostatic pressures up to approx. 25 kbar, the dc conductivities increase with pressure. This anomalous behavior for hopping conduction reflects the distinctive structure and bonding of these materials.

  3. Synthesis and anti-oxidation performance of nanoflake-decorated boron nitride hollow microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Li, Juan [College of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Lin, Hong [Department of Materials Science and Engineering, State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084 (China); Chen, Yongjun, E-mail: chenyj99@163.com [College of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); College of Material and Chemical Engineering, Hainan University, Haikou 570228 (China); Su, Qiaoqiao; Bi, Xiaofan [College of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China)

    2013-02-15

    Highlights: Black-Right-Pointing-Pointer A novel boron nitride (BN) composite structure composed of nanoflake and hollow microspheres was synthesized. Black-Right-Pointing-Pointer The raw materials are simple precursors of boron and Fe(NO{sub 3}){sub 3}{center_dot}9H{sub 2}O ethanol solution. Black-Right-Pointing-Pointer The structures have a high anti-oxidation temperature of 900 Degree-Sign C. Black-Right-Pointing-Pointer The growth mechanism consists of a combined vapor-liquid-solid (VLS) and vapor-solid (VS) model. - Abstract: In this study, a novel boron nitride composite structure composed of nanoflake-decorated hollow microspheres is demonstrated. A paste-like mixture is firstly prepared by mixing amorphous boron with ferric nitrate ethanol solution, followed by heating at 1300 Degree-Sign C in a flowing ammonia atmosphere for 5 h. Both the nanoflakes and microspheres are composed of crystalline hexagonal boron nitride. The hollow spheres have outer diameters of 0.8-3 {mu}m with thickness of about 300 nm, while the nanoflakes have thicknesses of 2-7 nm and lengths of 10-100 nm. Heating temperature is found to be crucial for the formation of this composite structure. The growth process consists of a vapor-liquid-solid growth stage of smooth hollow microspheres at lower temperature and a vapor-solid growth stage of nanoflakes on the surface of the microspheres at higher temperature. The boron nitride composite structure exhibits excellent anti-oxidation performance up to 900 Degree-Sign C.

  4. Single step synthesis of nanostructured boron nitride for boron neutron capture therapy

    International Nuclear Information System (INIS)

    Nanostructured Boron Nitride (BN) has been successfully synthesized by carbo-thermic reduction of Boric Acid (H3BO3). This method is a relatively low temperature synthesis route and it can be used for large scale production of nanostructured BN. The synthesized nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analyzer (DTA). XRD analysis confirmed the formation of single phase nanostructured Boron Nitride. SEM analysis showed that the particles are spherical in shape. DTA analysis showed that the phase is stable upto 900 °C and the material can be used for high temperature applications as well boron neutron capture therapy (BNCT)

  5. Single step synthesis of nanostructured boron nitride for boron neutron capture therapy

    Science.gov (United States)

    Singh, Bikramjeet; Singh, Paviter; Kumar, Manjeet; Thakur, Anup; Kumar, Akshay

    2015-05-01

    Nanostructured Boron Nitride (BN) has been successfully synthesized by carbo-thermic reduction of Boric Acid (H3BO3). This method is a relatively low temperature synthesis route and it can be used for large scale production of nanostructured BN. The synthesized nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analyzer (DTA). XRD analysis confirmed the formation of single phase nanostructured Boron Nitride. SEM analysis showed that the particles are spherical in shape. DTA analysis showed that the phase is stable upto 900 °C and the material can be used for high temperature applications as well boron neutron capture therapy (BNCT).

  6. boron and boron nitride coated nuclear fuel production in plasma atmosphere

    International Nuclear Information System (INIS)

    In these study uranium dioxide (UO2) and 5, 10 % gadolinium oxide (Gd2O3) containing UO2 nuclear fuel pellets were coated with first boron nitride (BN) then boron (B) layers as the results of the reactions between boron trichloride (BCl3) with ammonia (NH3) and BCl3 with hydrogen (H2) in the medium of argon (Ar) plasma created at 650 W and 500 W and 27.12 MHz to increase the fuel burnup efficiency and reactor core life by the method of plasma enhanced chemical vapor deposition (PECVD). Grainy BN and B structures were observed on the photographs taken from scanning electron microscope (SEM)

  7. 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

  8. 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.

  9. The influence of boron on the abrasion wear resistance of 17%Cr white cast iron

    International Nuclear Information System (INIS)

    A study of the abrasion wear resistance of the 2.7C-17Cr-0.7Mo white cast irons with different structures alloyed with boron ranging from 0.1% to 1.3% is carried out. Eleven heat treatments were used to find the optimum treatment. Three conditions (as-cast, martensitic and austenitic) are adopted for various tests. The microstructure and three-dimensional morphology of compounds are examined by optical microscope and SEM respectively. X-ray diffractometer is employed to analyze the compound phases. A high-stress abrasive wear tests is performed with loose SiO/sub 2/ and SiC abrasives in a metal track wear tester. Another abrasive wear test is conducted with wet SiO/sub 2/ abrasives in a rubber wheel tester. The hardness and fracture toughness of these alloys was also measured. With increasing boron content fracture toughness decreases. It is noted that if the irons contained about same compound volume, the abrasion wear resistance in present wear systems are much better than the irons without boron against SiO/sub 2/ abrasives, and the toughness is equivalent to 15 Cr irons without boron. Finally, considering the wear resistance and fracture toughness, the test results would provide a basis for optimizing these properties in selecting materials for a given wear component

  10. Boron neutron capture therapy of malignant brain tumors at the Brookhaven Medical Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Joel, D.D.; Coderre, J.A.; Chanana, A.D. [Brookhaven National Lab., Upton, NY (United States). Medical Dept.

    1996-12-31

    Boron neutron capture therapy (BNCT) is a bimodal form of radiation therapy for cancer. The first component of this treatment is the preferential localization of the stable isotope {sup 10}B in tumor cells by targeting with boronated compounds. The tumor and surrounding tissue is then irradiated with a neutron beam resulting in thermal neutron/{sup 10}B reactions ({sup 10}B(n,{alpha}){sup 7}Li) resulting in the production of localized high LET radiation from alpha and {sup 7}Li particles. These products of the neutron capture reaction are very damaging to cells, but of short range so that the majority of the ionizing energy released is microscopically confined to the vicinity of the boron-containing compound. In principal it should be possible with BNCT to selectively destroy small nests or even single cancer cells located within normal tissue. It follows that the major improvements in this form of radiation therapy are going to come largely from the development of boron compounds with greater tumor selectivity, although there will certainly be advances made in neutron beam quality as well as the possible development of alternative sources of neutron beams, particularly accelerator-based epithermal neutron beams.

  11. Modelling structure and properties of amorphous silicon boron nitride ceramics

    Directory of Open Access Journals (Sweden)

    Johann Christian Schön

    2011-06-01

    Full Text Available Silicon boron nitride is the parent compound of a new class of high-temperature stable amorphous ceramics constituted of silicon, boron, nitrogen, and carbon, featuring a set of properties that is without precedent, and represents a prototypical random network based on chemical bonds of predominantly covalent character. In contrast to many other amorphous materials of technological interest, a-Si3B3N7 is not produced via glass formation, i.e. by quenching from a melt, the reason being that the binary components, BN and Si3N4, melt incongruently under standard conditions. Neither has it been possible to employ sintering of μm-size powders consisting of binary nitrides BN and Si3N4. Instead, one employs the so-called sol-gel route starting from single component precursors such as TADB ((SiCl3NH(BCl2. In order to determine the atomic structure of this material, it has proven necessary to simulate the actual synthesis route.Many of the exciting properties of these ceramics are closely connected to the details of their amorphous structure. To clarify this structure, it is necessary to employ not only experimental probes on many length scales (X-ray, neutron- and electron scattering; complex NMR experiments; IR- and Raman scattering, but also theoretical approaches. These address the actual synthesis route to a-Si3B3N7, the structural properties, the elastic and vibrational properties, aging and coarsening behaviour, thermal conductivity and the metastable phase diagram both for a-Si3B3N7 and possible silicon boron nitride phases with compositions different from Si3N4: BN = 1 : 3. Here, we present a short comprehensive overview over the insights gained using molecular dynamics and Monte Carlo simulations to explore the energy landscape of a-Si3B3N7, model the actual synthesis route and compute static and transport properties of a-Si3BN7.

  12. Reactive sputter deposition of boron nitride

    International Nuclear Information System (INIS)

    The preparation of fully dense, boron targets for use in planar magnetron sources has lead to the synthesis of Boron Nitride (BN) films by reactive rf sputtering. The deposition parameters of gas pressure, flow and composition are varied along with substrate temperature and applied bias. The films are characterized for composition using Auger electron spectroscopy, for chemical bonding using Raman spectroscopy and for crystalline structure using transmission electron microscopy. The deposition conditions are established which lead to the growth of crystalline BN phases. In particular, the growth of an adherent cubic BN coating requires 400--500 C substrate heating and an applied -300 V dc bias

  13. Can Two-Dimensional Boron Superconduct?

    Science.gov (United States)

    Penev, Evgeni S; Kutana, Alex; Yakobson, Boris I

    2016-04-13

    Two-dimensional boron is expected to exhibit various structural polymorphs, all being metallic. Additionally, its small atomic mass suggests strong electron-phonon coupling, which in turn can enable superconducting behavior. Here we perform first-principles analysis of electronic structure, phonon spectra, and electron-phonon coupling of selected 2D boron polymorphs and show that the most stable structures predicted to feasibly form on a metal substrate should also exhibit intrinsic phonon-mediated superconductivity, with estimated critical temperature in the range of Tc ≈ 10-20 K. PMID:27003635

  14. Thermal conductivity behavior of boron carbides

    Science.gov (United States)

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

    1983-01-01

    Knowledge of the thermal conductivity of boron carbides is necessary to evaluate its potential for high temperature thermoelectric energy conversion applications. The thermal diffusivity of hot pressed boron carbide B/sub 1-x/C/sub x/ samples as a function of composition, temperature and temperature cycling was measured. These data in concert with density and specific heat data yield the thermal conductivities of these materials. The results in terms of a structural model to explain the electrical transport data and novel mechanisms for thermal conduction are discussed.

  15. 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

  16. Boron neutron capture synovectomy (BNCS) as a potential therapy for rheumatoid arthritis: boron biodistribution study in a model of antigen-induced arthritis in rabbits.

    Science.gov (United States)

    Trivillin, Verónica A; Abramson, David B; Bumaguin, Gaston E; Bruno, Leandro J; Garabalino, Marcela A; Monti Hughes, Andrea; Heber, Elisa M; Feldman, Sara; Schwint, Amanda E

    2014-11-01

    Boron neutron capture synovectomy (BNCS) is explored for the treatment of rheumatoid arthritis (RA). The aim of the present study was to perform boron biodistribution studies in a model of antigen-induced arthritis (AIA) in female New Zealand rabbits, with the boron carriers boronophenylalanine (BPA) and sodium decahydrodecaborate (GB-10) to assess the potential feasibility of BNCS for RA. Rabbits in chronic phase of AIA were used for biodistribution studies employing the following protocols: intra-articular (ia) (a) BPA-f 0.14 M (0.7 mg (10)B), (b) GB-10 (5 mg (10)B), (c) GB-10 (50 mg (10)B) and intravenous (iv), (d) BPA-f 0.14 M (15.5 mg (10)B/kg), (e) GB-10 (50 mg (10)B/kg), and (f) BPA-f (15.5 mg (10)B/kg) + GB-10 (50 mg (10)B/kg). At different post-administration times (13-85 min for ia and 3 h for iv), samples of blood, pathological synovium (target tissue), cartilage, tendon, muscle, and skin were taken for boron measurement by inductively coupled plasma mass spectrometry. The intra-articular administration protocols at 20 ppm) in the pathological synovium. Dosimetric estimations suggest that BNCS would be able to achieve a therapeutically useful dose in pathological synovium without exceeding the radiotolerance of normal tissues in the treatment volume, employing boron carriers approved for use in humans. Radiobiological in vivo studies will be necessary to determine the actual therapeutic efficacy of BNCS to treat RA in an experimental model. PMID:25156017

  17. Boron carbide-based ceramics via polymer route synthesis

    International Nuclear Information System (INIS)

    Boron carbide is a ceramic material with excellent high temperature physical properties. As compared to conventional techniques, the preparation of boron carbide from polymeric precursors is attractive as this technique offers a number of unique advantages. In this paper, the screening of polymeric precursors to boron carbide will be discussed. Two promising boron carbide, carborane containing polymeric precursors have resulted in 60-70 wt.% ceramic yields. The chemistry of polymer synthesis and the transformations from the polymer to amorphous and crystalline boron carbide were investigated with infrared spectroscopy, NMR spectroscopy, thermal analysis, and x-ray diffraction

  18. Determination of carbon and sulphur in boron carbide

    International Nuclear Information System (INIS)

    Boron carbide is used in control rods of nuclear power reactors. The chemical specification for carbon in boron carbide ranges between 15 - 24 wt.% depending upon the grade of boron carbide. Hence carbon in boron carbide is to be determined accurately to find out the stoichiometry. Sulphur, which is present in trace quantities, is also to be determined to find out the purity of boron carbide. Carbon is determined by combustion followed by (i) thermal conductivity detection and (ii) infrared detection. Sulphur is determined by (i) combustion followed by infrared detection and (ii) vacuum combustion extraction - quadrupole mass spectrometry. The results are compared. (author)

  19. 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.

  20. Medical chemistry of boron neutron capture agents having pharmacological activity

    International Nuclear Information System (INIS)

    Boron neutron capture therapy (BNCT) is a cancer treatment that selectively destroys cancer cells following administering a cancer-selective drug containing stable isotope boron-10 and neutron irradiation. In clinical trial of BNCT, disodium mercaptoundecahydro-closo-dodecaborate (BSH) and p-boronophenylalanine (BPA) have been used, however, development of a new drugs with high cancer selectivity and therapeutic efficiency is expected. Therefore, we review boron-containing drugs as a boron neutron capture agents having pharmacological activity, BNCT research on boron-modified porphyrin derivatives which have photosensitivity and neutron capture activity and our proposed neutron sensitizing agent. (author)

  1. A new monoclinic structure for compressed hexagonal boron nitride

    International Nuclear Information System (INIS)

    A prominent contraction of the interplanar spacing between sp2 sheets from 3.33 to 3.10 angstrom in so-called compressed h-BN, which appears on the phase transition from h(hexagonal)- to c(cubic)-boron nitride (BN) under high pressure (7.7 GPa) at high temperature (1,800 C), is examined by high-resolution transmission electron microscopy (HRTEM). It is attributable to a monoclinic lattice distortion of the residual h-BN, which originates from the difference in the compressibility as well as the thermal expansion between adjoining h- and c-BN grains. The parameters of the monoclinic unit-cell are am = 4.33, bm = 2.50, cm = 3.1--3.3 angstrom and β = 92--95 degree. Thin plates of h-BN are often folded and the folding also causes the monoclinic structure

  2. Effect of metal hydrides on the burning characteristics of boron

    International Nuclear Information System (INIS)

    Highlights: • The effect of some metal hydrides on the burning characteristics of boron is studied for the first time. • We are the first to conduct a TG experiment on boron samples at high temperatures (a maximum of 1750 °C). • The thermal reaction process of boron is firstly divided into five stages according to the weight gain rate of the sample. • Specific values of metal hydrides on ignition delay time and combustion intensity of boron are obtained. - Abstract: In this study, the effect of four metal hydrides on the burning characteristics of boron was investigated. Thermogravimetric experiment results show that the thermal reaction process of boron samples can be divided into five stages. The thermal reactions of boron can be significantly promoted with LiH, which can reduce the initial temperature of the first violent reaction stage by ∼140 °C. The starting temperature of the post-reaction stage also decreases by ∼260 °C. The results of the laser ignition experiment suggest that all four metal hydrides can promote boron burning. Nonetheless, different metal hydrides display varied promotional effects. Among the studied hydrides, LiH is the most effective additive and shortens the ignition delay time of boron by ∼34.1%. Moreover, it enhances the combustion intensity of boron by ∼117.6%. The other three metal hydrides (CaH2, TiH2, and ZrH2) can also contribute to boron burning

  3. Removal properties of dissolved boron by glucomannan gel.

    Science.gov (United States)

    Oishi, Kyoko; Maehata, Yugo

    2013-04-01

    Boron ions have long been known to form complexes with the cis-diol group of a polysaccharide. Konjac glucomannan (KGM) which is one of polysaccharides was used to remove dissolved boron in this study. KGM forms a complex with boron, but does not remove boron from contaminated waters as well as other polysaccharides because of its high water solubility. Therefore, the removal efficiencies of dissolved boron were examined using both an insoluble KGM gel and KGM semi-gel. The former did not remove dissolved boron, but the latter did. The difference in the ability of boron removal was due to the presence of diol group inside. KGM loses free diol group during the process of gelation. On the other hand, the semi-gel gelated only surface layer in water has diol group inside. The boron removal capacity of the semi-gel was highest at pHs⩾11, when the boron species is present as B(OH)4(-). The capacity was slightly increased by the addition of Al, Ca and Mg under high pH conditions. This was due to co-precipitation of boron with Ca dissolved from the semi-gel. The boron adsorbed to the semi-gel easily was desorbed under low pH conditions and the hysteresis was not found. PMID:23260255

  4. Ground-water pollution determined by boron isotope systematics

    International Nuclear Information System (INIS)

    Boron isotopic systematics as related to ground-water pollution is reviewed. We report isotopic results of contaminated ground water from the coastal aquifers of the Mediterranean in Israel, Cornia River in north-western Italy, and Salinas Valley, California. In addition, the B isotopic composition of synthetic B compounds used for detergents and fertilizers was investigated. Isotopic analyses were carried out by negative thermal ionization mass spectrometry. The investigated ground water revealed different contamination sources; underlying saline water of a marine origin in saline plumes in the Mediterranean coastal aquifer of Israel (δ11B=31.7 per mille to 49.9 per mille, B/Cl ratio ∼1.5x10-3), mixing of fresh and sea water (25 per mille to 38 per mille, B/Cl∼7x10-3) in saline water associated with salt-water intrusion to Salinas Valley, California, and a hydrothermal contribution (high B/Cl of ∼0.03, δ11B=2.4 per mille to 9.3 per mille) in ground water from Cornia River, Italy. The δ11B values of synthetic Na-borate products (-0.4 per mille to 7.5 per mille) overlap with those of natural Na-borate minerals (-0.9 per mille to 10.2 per mille). In contrast, the δ11B values of synthetic Ca-borate and Na/Ca borate products are significantly lower (-15 per mille to -12.1 per mille) and overlap with those of the natural Ca-borate minerals. We suggest that the original isotopic signature of the natural borate minerals is not modified during the manufacturing process of the synthetic products, and it is controlled by the crystal chemistry of borate minerals. The B concentrations in pristine ground-waters are generally low (11B=39 per mille), salt-water intrusion and marine-derived brines (40 per mille to 60 per mille) are sharply different from hydrothermal fluids (δ11B=10 per mille to 10 per mille) and anthropogenic sources (sewage effluent: δ11B=0 per mille to 10 per mille; boron-fertilizer: δ11B=-15 per mille to 7 per mille). some differences (up to 15

  5. 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.

  6. 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...

  7. 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)

  8. Boron neutrino flux and resonant conversion of solar neutrinos

    International Nuclear Information System (INIS)

    In view of large uncertainties in the prediction of the boron neutrino flux from the Sun we consider the magnitude of this flux, ΦB, as a parameter to be found from experiment. A consistent description of the data in terms of neutrino resonance conversion admits ΦB/Φ0B=0.4 - 2.5 in small mixing domain and ΦB/Φ0B=1 - 3 in large mixing domain, (here φ0B ≡ 5.7 · 106 cm-2s-1 is the flux in the reference SSM). Variations of the flux within these intervals enlarge the allowed region of mixing angles to sin22θ=(0.06 -2) · 10-2 and sin22θ=0.2 - 0.9 correspondingly. If the value of ΦB is about that measured by Kamiokande, the data fix the region Δm2 ∼ (4-9) · 10-6 eV2 and sin2 2θ ∼ (0.6 - 2) · 10-3 (''very small mixing solution''). We comment on the possibility to measure the neutrino parameters and the original boron neutrino flux in future experiments. (author). 31 refs, 3 figs, 2 tabs

  9. Salt rejection and water transport through boron nitride nanotubes.

    Science.gov (United States)

    Hilder, Tamsyn A; Gordon, Daniel; Chung, Shin-Ho

    2009-10-01

    Nanotube-based water-purification devices have the potential to transform the field of desalination and demineralization through their ability to remove salts and heavy metals without significantly affecting the fast flow of water molecules. Boron nitride nanotubes have shown superior water flow properties compared to carbon nanotubes, and are thus expected to provide a more efficient water purification device. Using molecular dynamics simulations it is shown that a (5, 5) boron nitride nanotube embedded in a silicon nitride membrane can, in principle, obtain 100% salt rejection at concentrations as high as 1 M owing to a high energy barrier while still allowing water molecules to flow at a rate as high as 10.7 water molecules per nanosecond (or 0.9268 L m(-2) h(-1)). Furthermore, ions continue to be rejected under the influence of high hydrostatic pressures up to 612 MPa. When the nanotube radius is increased to 4.14 A the tube becomes cation-selective, and at 5.52 A the tube becomes anion-selective. PMID:19582727

  10. Recombination methods for boron neutron capture therapy dosimetry

    International Nuclear Information System (INIS)

    The radiation effects of boron neutron capture therapy (BNCT) are associated with four-dose-compartment radiation field - boron dose (from 10B(n,α)7Li) reaction), proton dose from 14N(n,p)14C reaction, neutron dose (mainly fast and epithermal neutrons) and gamma-ray dose (external and from capture reaction 1H(n,γ)2D). Because of this the relation between the absorbed dose and the biological effects is very complex and all the above mentioned absorbed dose components should be determined. From this point of view, the recombination chambers can be very useful instruments for characterization of the BNCT beams. They can be used for determination of gamma and high-LET dose components for the characterization of radiation quality of mixed radiation fields by recombination microdosimetric method (RMM). In present work, a graphite high-pressure recombination chamber filled with nitrogen, 10BF3 and tissue equivalent gas was used for studies on application of RMM for BNCT dosimetry. The use of these gases or their mixtures opens a possibility to design a recombination chamber for determination of the dose fractions due to gamma radiation, fast neutrons, neutron capture on nitrogen and high LET particles from (n,10B) reaction in simulated tissue with different content of 10B. (author)

  11. 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)

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. PWR core response to boron dilution transient

    International Nuclear Information System (INIS)

    This paper illustrates the steps followed in order to set up a tool (composed of a plant model and of a procedure) that allows accounting for boron reactivity feedbacks during plant transients. The procedure that has been developed allows to find out the values of the boron feedback coefficients, given the differential boron worth, and to properly initialize the Thermal Hydraulic and the Neutronic (TH/NEU) system. Once the tool has been developed, it has been used to analyze different scenarios, resulting from deborated water injection from the reactor make-up system. The most important parameter, during this Reactivity Insertion Accidents (RIAs), is the Energy Released to the Fuel (ERF) and it has been monitored, in order to identify the situations when the fuel might be damaged (ERF > 250 kJ/kg, for high burnup fuel). The analyses have been performed using the RELAP5-3D computer code. The conclusion of the study is that the limited capability of modeling mixing phenomena provided by most common plant codes (such as RELAP5-3D) is not suitable to perform BE analyses of RIAs, since those accidents are so sensitive to boron concentration changes that the effect of uncertainties cannot be neglected. The use of Computational Fluid Dynamics (CFD) codes could reduce uncertainties enough to perform BE analyses and thus it should be recommended. (author)

  17. 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 %.

  18. 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...

  19. Channeling of boron ions into silicon

    International Nuclear Information System (INIS)

    Channeled and random distributions of boron ions implanted over the energy range 50 keV--1.8 MeV into silicon have been measured using the differential capacitance technique. When implantations are performed along the or axis, profiles exhibit a strong orientation dependance. The best channeled profiles shows that more than 70% of the implanted dose is in the channeled peak

  20. Influence of pollution of boron chlorinity ratio

    Digital Repository Service at National Institute of Oceanography (India)

    Narvekar, P.V.; Zingde, M.D.

    Presence of boron in domestic wastewater has resulted in high B/CI ratio at some locations in the coastal water around Bombay. A widest range (0.215-0.281) of B/CI was observed at a location with high influence of wastewater release. The mean B...

  1. 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.

  2. Boron carbide synthesis at plasma spray process

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Brožek, Vlastimil; Hofman, R.

    Bari : Department of Chemistry, University of Bari, 2003 - (d'Agostino, R.; Favia, P.; Fracassi, F.; Palumbo, F.). s. 631 [International Symposium on Plasma Chemistry/16th./. 22.06.2003-27.06.2003, Taormina] Institutional research plan: CEZ:AV0Z2043910 Keywords : boron carbide , plasma spray process Subject RIV: BL - Plasma and Gas Discharge Physics

  3. Joining of boron carbide using nickel interlayer

    International Nuclear Information System (INIS)

    Carbide ceramics such as boron carbide due to their unique properties such as low density, high refractoriness, and high strength to weight ratio have many applications in different industries. This study focuses on direct bonding of boron carbide for high temperature applications using nickel interlayer. The process variables such as bonding time, temperature, and pressure have been investigated. The microstructure of the joint area was studied using electron scanning microscope technique. At all the bonding temperatures ranging from 1150 to 1300degC a reaction layer formed across the ceramic/metal interface. The thickness of the reaction layer increased by increasing temperature. The strength of the bonded samples was measured using shear testing method. The highest strength value obtained was about 100 MPa and belonged to the samples bonded at 1250 for 75 min bonding time. The strength of the joints decreased by increasing the bonding temperature above 1250degC. The results of this study showed that direct bonding technique along with nickel interlayer can be successfully utilized for bonding boron carbide ceramic to itself. This method may be used for bonding boron carbide to metals as well.

  4. The manufacturing method of boron carbide

    International Nuclear Information System (INIS)

    The new method for manufacturing of boron carbide as powder with controlled purity and surface development has been described. The suspension of boric acid aqueous solution and carbon black in alcohol has been homogenized mechanically. Water and alcohol are then evaporated during mixing. After drying homogenous mixture is heated in temperature range of 1270-1870 C during one hour

  5. 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

  6. Boron carbide nanowires: Synthesis and characterization

    Science.gov (United States)

    Guan, Zhe

    Bulk boron carbide has been widely used in ballistic armored vest and the property characterization has been heavily focused on mechanical properties. Even though boron carbides have also been projected as a promising class of high temperature thermoelectric materials for energy harvesting, the research has been limited in this field. Since the thermal conductivity of bulk boron carbide is still relatively high, there is a great opportunity to take advantage of the nano effect to further reduce it for better thermoelectric performance. This dissertation work aims to explore whether improved thermoelectric performance can be found in boron carbide nanowires compared with their bulk counterparts. This dissertation work consists of four main parts. (1) Synthesis of boron carbide nanowires. Boron carbide nanowires were synthesized by co-pyrolysis of diborane and methane at low temperatures (with 879 °C as the lowest) in a home-built low pressure chemical vapor deposition (LPCVD) system. The CVD-based method is energy efficient and cost effective. The as-synthesized nanowires were characterized by electron microscopy extensively. The transmission electron microscopy (TEM) results show the nanowires are single crystalline with planar defects. Depending on the geometrical relationship between the preferred growth direction of the nanowire and the orientation of the defects, the as-synthesized nanowires could be further divided into two categories: transverse fault (TF) nanowires grow normal to the defect plane, while axial fault (AF) ones grow within the defect plane. (2) Understanding the growth mechanism of as-synthesized boron carbide nanowires. The growth mechanism can be generally considered as the famous vapor-liquid-solid (VLS) mechanism. TF and AF nanowires were found to be guided by Ni-B catalysts of two phases. A TF nanowire is lead by a hexagonal phase catalyst, which was proved to be in a liquid state during reaction. While an AF nanowires is catalyzed by a

  7. 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

    [1]Palmer, M. R., Swihart, G. H., Boron isotope geochemistry: An overview, in Rev. Mineral 33, Boron Mineralogy, Petrology and Geochemistry (eds. Grew, E. S., Anovitz, L. M.), Washington, D. C.: Mineral Soc. Am., 1996, 709-744.[2]Chaussidon, M., Albarède, F., Secular boron isotope variations in the continental crust: An ion microprobe study, Earth Planet Sci. Lett., 1992, 108: 229-241.[3]Spivack, A. J., Edmond, J. M., Boron isotope exchange between seawater and the oceanic crust, Geochim. Cosmochim. Acta, 1987, 51: 1033-1043.[4]Vengosh, A., Chivas, A. R., Mcculloch, M. T. et al., Boron isotope geochemistry of Australian salt lakes, Geochim. Cosmochim. Acta, 1991, 55: 2591-2606.[5]Xiao, Y. K., Sun, D. P., Wang, Y. H. et al., Boron isotopic compositions of brine, sediments and source water in Da Qaidam Lake, Qinghai, China, Geochim Cosmochim Acta, 1992,56: 1561-1568.[6]Mcmullen, C. C., Cragg, C. B., Thode, H. G., Absolute rations of 11B/10B in Searles Lake borax, Geochim. Cosmochim. Acta, 1961, 23: 147-150.[7]Palmer, M. R., Sturchio, N. C., The boron isotope systematics of the Yellowstone National Park (Wyoming) hydrothermal system: A reconnaissance, Geochim. Cosmochim. Acta, 1990, 54: 2811-2815.[8]Arndsson, S., Andrèsdèttir, A., Processes controlling the distribution of boron and chlorine in natural waters in Iceland, Geochim. Cosmochim. Acta, 1995, 59: 4125-4146.[9]Aggarwal, J. K., Palmer, M. R., Bullen, T. D. et al., The boron isotope systematics of Iceland geothermal waters: 1. Meteoric water charged systems, Geochim. Cosmochim. Acta, 2000, 64: 579-585.[10]Spivack, A. J., Palmer, M. R., Edmond, J. M., The sedimentary cycle of the boron isotopes, Geochim. Cosmochim. Acta, 1987, 51: 1939-1949.[11]Liu Yingjun, Cao Liming, Li Zhaolin et al., Element Geochemistry (in Chinese), Beijing: Science Press, 1984, 422-428.[12]Schwarcz, H. P., Agyei, E. K., Mcmullen, C. C., Boron isotopic fractionation during clay adsorption

  8. Intra-Shell boron isotope ratios in benthic foraminifera: Implications for paleo-pH reconstructions

    Science.gov (United States)

    Rollion-Bard, C.; Erez, J.

    2009-12-01

    The boron isotope composition of marine carbonates is considered to be a seawater pH proxy. Nevertheless, the use of δ11B has some limitations: 1) the knowledge of fractionation factor (α4-3) between the two boron dissolved species (boric acid and borate ion), 2) the δ11B of seawater may have varied with time and 3) the amplitude of the "vital effects" of this proxy. Using secondary ion mass spectrometry (SIMS), we looked at the internal variability in the boron isotope ratio of the shallow water, symbionts bearing foraminiferan Amphistegina lobifera. Specimens were cultured at constant temperature (24±0.1 °C) in seawater with pH ranging between 7.90 and 8.45. We performed 6 to 8 measurements of δ11B in each foraminifera. Intra-shell boron isotopes show large variability with an upper threshold value of pH ~ 9. The ranges of the skeletal calculated pH values in different cultured foraminifera, show strong correlation with the culture pH values and may thus serve as proxy for pH in the past ocean.

  9. About effect of magnesium chloride and some ions in brines on boron coprecipitation by iron hydroxide

    International Nuclear Information System (INIS)

    Studies were made of conditions of precipitation of boron with iron hydroxide from the brines of the mixing zone of the Kara-Bogaz Gol, the mother liquor after the precipitation of potassium salts and artificial manganese chloride solutions at a temperature of 7-45 dee C. The maximum extraction of boron from the brines investigated is observed both in a weakly acid and a weakly alkaline medium. The extraction intensity increases drastically in the range of the maximum with an increase in brine concentration. The anions Cl-, SO42-, and HCO3- present in the brines produce the maximum effect on boron precipitation at a definite pH. This effect depends on the nature of the anions and their ratio in the brine. With a rise in temperature the degree of boron precipitations from the magnesium chloride brine and the precipitate capacity increase as a result of the release of active magnesium hydroxide. When the ratio of Fe2O3 to 100 ml initial solution changes towards increase in precipitating agent at a constant temperature, the precipitate capacity for B2O3 decreases

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  11. Characteristics of Boron Decorated TiO2 Nanoparticles for Dye-Sensitized Solar Cell Photoanode

    Directory of Open Access Journals (Sweden)

    Ching-Yuan Ho

    2015-01-01

    Full Text Available Different boron weight percents on mixed-phase (anatase and rutile TiO2 nanoparticles were synthesized to investigate structure morphology, defect states, luminescence properties, and energy conversion. The measured results indicate that boron doping of TiO2 both increases the crystallite size and rutile-phase percent in an anatase matrix. Decreasing the band gap by boron doping can extend the absorption to the visible region, while undoped TiO2 exhibits high UV absorption. Oxygen vacancy defects generated by boron ions reduce Ti+4 and affect electron transport in dye-sensitized solar cells. Excess electrons originating from the oxygen vacancies of doped TiO2 downward shift in the conduction band edge and prompt the transfer of photoelectrons from the conduction band of the rutile phase to the lower energy anatase trapping sites; they then separate charges to enhance the photocurrent and Jsc. Although the resistance of the electron recombination (Rk between doped TiO2 photoanode and the electrolyte for the doped TiO2 sample is lower, a longer electron lifetime (τ of 19.7 ms with a higher electron density (ns of 2.1 × 1018 cm−3 contributes to high solar conversion efficiency.

  12. Hemorrhage in mouse tumors induced by dodecaborate cluster lipids intended for boron neutron capture therapy

    Directory of Open Access Journals (Sweden)

    Schaffran T

    2014-07-01

    Full Text Available Tanja Schaffran,1 Nan Jiang,1 Markus Bergmann,2,3 Ekkehard Küstermann,4 Regine Süss,5 Rolf Schubert,5 Franz M Wagner,6 Doaa Awad,7 Detlef Gabel1,2,8 1Department of Chemistry, University of Bremen, 2Institute of Neuropathology, Klinikum Bremen-Mitte; 3Cooperative Center Medicine, University of Bremen, 4“In-vivo-MR” AG, FB2, University of Bremen, Bremen, 5Pharmaceutical Technology, University of Freiburg, Freiburg im Breisgau, 6Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II, Technische Unversitaet Muenchen, Garching, Germany; 7Department of Biochemistry, Alexandria University, Alexandria, Egypt; 8School of Engineering and Science, Jacobs University Bremen, Bremen, Germany Abstract: The potential of boron-containing lipids with three different structures, which were intended for use in boron neutron capture therapy, was investigated. All three types of boron lipids contained the anionic dodecaborate cluster as the headgroup. Their effects on two different tumor models in mice following intravenous injection were tested; for this, liposomes with boron lipid, distearoyl phosphatidylcholine, and cholesterol as helper lipids, and containing a polyethylene glycol lipid for steric protection, were administered intravenously into tumor-bearing mice (C3H mice for SCCVII squamous cell carcinoma and BALB/c mice for CT26/WT colon carcinoma. With the exception of one lipid (B-THF-14, the lipids were well tolerated, and no other animal was lost due to systemic toxicity. The lipid which led to death was not found to be much more toxic in cell culture than the other boron lipids. All of the lipids that were well tolerated showed hemorrhage in both tumor models within a few hours after administration. The hemorrhage could be seen by in vivo magnetic resonance and histology, and was found to occur within a few hours. The degree of hemorrhage depended on the amount of boron administered and on the tumor model. The observed unwanted effect of the lipids

  13. 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.

  14. ISOBORDAT: An Online Data Base on Boron Isotopes

    International Nuclear Information System (INIS)

    From 1986, boron isotope data in natural substances increased sharply in scientific publications. Analytical difficulties derived from complex geochemical matrices have been faced and interlaboratory calibrations reported in the boron literature. Boron isotopes are nowdays applied to investigate boron origin and migration in natural waters, sources of boron contamination, water-rock interactions and also contribute to water resource management. This is especially important in those areas where boron content exceeds the local regulations for drinking water supply and boron sources need to be identified. ISOBORDAT, an interactive database on boron isotope composition and content in natural waters is presented to the wider community of boron isotope users. The database's structure, scope and applications are reported, along with a discussion on δ11B values obtained in Italian waters. In the database boron data are structured in the following categories: rainwater, rivers, lakes, groundwater and potential contaminants. New categories (medium and high enthalpy fluids from volcanic and geothermal areas) are anticipated. ISOBORDAT aims to be as interactive as possible and will be developed taking into account information and suggestions received. The database is continually undergoing revision to keep pace with continuous data publication. Indications of data that are missing at present are greatly appreciated. (author)

  15. 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.

  16. Effect of boron doping in the microwave surface resistance of neutron irradiated melt-textured Y{sub 1.6}Ba{sub 2.3}Cu{sub 3.3}O{sub 7-x} samples

    Energy Technology Data Exchange (ETDEWEB)

    Agliolo Gallitto, A.; La Duca, M. [CNISM and Dipartimento di Fisica, Universita di Palermo, via Archirafi 36, 90123 Palermo (Italy); Li Vigni, M., E-mail: livigni@fisica.unipa.it [CNISM and Dipartimento di Fisica, Universita di Palermo, via Archirafi 36, 90123 Palermo (Italy); Topal, U. [TUBITAK-UME, National Metrology Institute, PK 54, 41470 Gebze-Kocaeli (Turkey); Yildiz, S. [Department of Physics, Faculty of Science and Arts, Gaziosmanpasa University, 60240 Tokat (Turkey)

    2012-12-14

    We report on the microwave surface resistance of melt-textured Y{sub 1.6}Ba{sub 2.3}Cu{sub 3.3}O{sub 7-x} samples, doped with different amount of B{sub 2}O{sub 3} and, subsequently, irradiated by thermal neutrons at the fluence of 1.476 Multiplication-Sign 10{sup 17} cm{sup -2}. The microwave surface resistance has been measured as a function of temperature and DC magnetic field. The experimental results are quantitatively discussed in the framework of the Coffey and Clem theory, properly adapted to take into account the d-wave nature of cuprate superconductors. By fitting the experimental data at zero DC field, we have highlighted the effects of the induced defects in the general properties of the samples, including the intergranular region. The analysis of the results obtained at high DC fields allowed us to investigate the fluxon dynamics and deduce the depinning frequency; in particular, we show that the addition of B{sub 2}O{sub 3} up to 0.1 wt.% increases the effectiveness of the defects to hinder the fluxon motion induced by the microwave current.

  17. Structure and single-phase regime of boron carbides

    Science.gov (United States)

    Emin, David

    1988-09-01

    The boron carbides are composed of twelve-atom icosahedral clusters which are linked by direct covalent bonds and through three-atom intericosahedral chains. The boron carbides are known to exist as a single phase with carbon concentrations from about 8 to about 20 at. %. This range of carbon concentrations is made possible by the substitution of boron and carbon atoms for one another within both the icosahedra and intericosahedral chains. The most widely accepted structural model for B4C (the boron carbide with nominally 20% carbon) has B11C icosahedra with C-B-C intericosahedral chains. Here, the free energy of the boron carbides is studied as a function of carbon concentration by considering the effects of replacing carbon atoms within B4C with boron atoms. It is concluded that entropic and energetic considerations both favor the replacement of carbon atoms with boron atoms within the intericosahedral chains, C-B-C-->C-B-B. Once the carbon concentration is so low that the vast majority of the chains are C-B-B chains, near B13C2, subsequent substitutions of carbon atoms with boron atoms occur within the icosahedra, B11C-->B12. Maxima of the free energy occur at the most ordered compositions: B4C,B13C2,B14C. This structural model, determined by studying the free energy, agrees with that previously suggested by analysis of electronic and thermal transport data. These considerations also provide an explanation for the wide single-phase regime found for boron carbides. The significant entropies associated with compositional disorder within the boron carbides, the high temperatures at which boron carbides are formed (>2000 K), and the relatively modest energies associated with replacing carbon atoms with boron atoms enable the material's entropy to be usually important in determining its composition. As a result, boron carbides are able to exist in a wide range of compositions.

  18. Neutron dosimetry by the spark counting of tracks in boron-doped film

    International Nuclear Information System (INIS)

    Thin cellulose nitrate films are doped with a boron compound. After thermal neutron irradiation, the films are etched in an aqueous solution of 10% NaOH, at 50 deg C, for 1.5 hr, during which the 27 μm thick films are reduced to about 7 μm. The etch-pits caused by 10B(n,α)7Li reactions are punched twice at 600 V and then counted at 500 V. The ratio of the spark density to the thermal neutron fluence was found to be 1.0 x 10-4 for a boron concentration of 1%. After due consideration of background counts, a thermal neutron dose of 0.3 mrem (3 x 10-6 Sv) can be measured with this system. (author)

  19. Nucleation of amorphous shear bands at nanotwins in boron suboxide.

    Science.gov (United States)

    An, Qi; Reddy, K Madhav; Qian, Jin; Hemker, Kevin J; Chen, Ming-Wei; Goddard Iii, William A

    2016-01-01

    The roles of grain boundaries and twin boundaries in mechanical properties are well understood for metals and alloys. However, for covalent solids, their roles in deformation response to applied stress are not established. Here we characterize the nanotwins in boron suboxide (B6O) with twin boundaries along the planes using both scanning transmission electron microscopy and quantum mechanics. Then, we use quantum mechanics to determine the deformation mechanism for perfect and twinned B6O crystals for both pure shear and biaxial shear deformations. Quantum mechanics suggests that amorphous bands nucleate preferentially at the twin boundaries in B6O because the twinned structure has a lower maximum shear strength by 7.5% compared with perfect structure. These results, which are supported by experimental observations of the coordinated existence of nanotwins and amorphous shear bands in B6O, provide a plausible atomistic explanation for the influence of nanotwins on the deformation behaviour of superhard ceramics. PMID:27001922

  20. 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.

  1. Diffusion Boronizing of H11 Hot Work Tool Steel

    Science.gov (United States)

    Jurči, Peter; Hudáková, Mária

    2011-10-01

    The H11 hot work tool steel was boronized at various processing parameters, austenitized, quenched, and tempered to a core hardness of 47-48 HRC. Microstructure, phase constitution, and microhardness of boronized layers were investigated. Effect of boronized region on the bulk properties was determined by the Charpy impact test. Structure of boronized regions is formed by the compound layers and diffusion inter-layer. The compound layers consisted of only (Fe,Cr)2B phase, but in the case of longer processing time, they contained also of the (Fe,Cr)B-phase. The inter-layer contained enhanced portion of carbides, formed due to carbon diffusion from the boride compounds toward the substrate. Microhardness of boronized layers exceeded considerably 2000 HV 0.1. However, boronizing led to a substantial lowering of the Charpy impact toughness of the material.

  2. 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...

  3. Boron carbide whisker and platelet reinforced ceramic matrix composites

    International Nuclear Information System (INIS)

    Boron carbide whisker and platelet-reinforced alumina and boron-carbide-whisker-reinforced silicon carbide composites were prepared by hot-pressing. The mechanical properties of hot-pressed boron carbide platelet and whisker-reinforced composites are better than the inherent ceramic matrix. A maximum fracture toughness, K(lc), of 9.5 MPa sq rt m is achieved for alumina/boron carbide whisker composites, 8.6 MPa sq rt m is achieved for alumina/boron carbide platelet composites, and 3.8 MPa sq rt m is achieved for silicon carbide/boron carbide whisker composites. The fracture toughness is dependent on the volume fraction of the platelets and whiskers. 12 refs

  4. 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.

  5. Fabrication and characterization of n-type zinc oxide/p-type boron doped diamond heterojunction

    Czech Academy of Sciences Publication Activity Database

    Marton, M.; Mikolášek, M.; Bruncko, J.; Novotný, I.; Ižák, Tibor; Vojs, M.; Kozak, Halyna; Varga, Marián; Artemenko, Anna; Kromka, Alexander

    2015-01-01

    Roč. 66, č. 5 (2015), s. 277-281. ISSN 1335-3632 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk(CZ) 7AMB14SK024 Institutional support: RVO:68378271 Keywords : boron doped diamond * zinc oxide * Raman spectroscopy * bipolar heterostructure * wide-bandgap Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.378, year: 2014

  6. Concentration of boron compounds in the process of electrodialysis freshening of thermal water

    International Nuclear Information System (INIS)

    Regularities of boron compounds concentration during electrodialysis freshening of model solution of thermal water of Pauzhet geothermal power plant were investigated. It is shown that brines containing 4.7 g/l of boric acid are formed in condition of using membranes MF-4-SK and MA-40 and decreasing total salt content (pH > 10) up to 300 mg/dm3. 6 refs., 1 fig., 1 tab

  7. Formation of argon-boron bonds in the reactions of BFn+/2+ cations with neutral argon

    Czech Academy of Sciences Publication Activity Database

    Levee, L.; Calogero, C.; Barbieri, E.; Byrne, S.; Donahue, C.; Eisenberg, M.; Hattenbach, S.; Le, J.; Capitani, J. F.; Roithová, J.; Schröder, Detlef

    2012-01-01

    Roč. 323, 1 Jun (2012), s. 2-7. ISSN 1387-3806 R&D Projects: GA ČR GA203/09/1223 Grant ostatní: European Research Council(XE) AdG HORIZOMS Institutional support: RVO:61388963 Keywords : argon compound * boron fluoride * dication * gas phase reactivity * mass spectrometry * neon compound Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.142, year: 2012

  8. Tuning the electronic properties of armchair carbon nanoribbons by a selective boron doping

    Energy Technology Data Exchange (ETDEWEB)

    Navarro-Santos, P; Ricardo-Chavez, J L; Lopez-Sandoval, R [Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la presa San Jose 2055, San Luis Potosi 78216 (Mexico); Reyes-Reyes, M [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi 78000 (Mexico); Rivera, J L, E-mail: sandov@ipicyt.edu.m [Facultad de Ingenieria Quimica, Universidad Michoacana de San Nicolas de Hidalgo, Santiago Tapia 403, Morelia, Michoacan, 58000 (Mexico)

    2010-12-22

    Armchair carbon nanoribbons (ACNRs) substitutionally doped with boron atoms are investigated in the framework of first-principles density functional theory. Different boron-boron arrangements and concentrations are considered in order to simulate possible aggregation patterns, their structural stability and electronic behavior are determined as a function of ribbon size. In agreement with previous studies, our results show that the dopant atoms have in general a preference for edge sites, but specific effects appear as a function of concentration that importantly modify the properties of the ribbons compared to the pristine case. Interesting tendencies are discovered as a function of dopant concentration that significantly affect the electronic properties of the ribbons. We have found that BC{sub 3} island formation and edge doping are the most important factors for the structural stabilization of the ribbons with high boron concentration (>7%) whereas for the cases of low boron concentrations (<5%) the structural stabilities are similar. For all the doped cases, we have found that the BC{sub 3} island patterns give rise to highly localized B states on top of the Fermi level, resulting in semiconducting behavior. On the other hand, when the average distance between the B atoms increases beyond island stoichiometry, the localization of their states is reduced and the ribbons may become metallic due to a band crossing caused by the lowering of the Fermi level resulting from the positive charge doping. Thus, tuning the dopant interaction would be an appropriate way to tailor the electronic properties of the ribbons in a convenient manner in view of potential technological applications.

  9. Boron imaging with a microstrip silicon detector for applications in BNCT

    Energy Technology Data Exchange (ETDEWEB)

    Mattera, A. [Universita degli Studi dell' Insubria (Italy); INFN, sez. Milano Bicocca (Italy)], E-mail: andrea.mattera@gmail.com; Basilico, F. [CNR di Milano (Italy); Bolognini, D. [Universita degli Studi dell' Insubria (Italy); INFN, sez. Milano Bicocca (Italy); Borasio, P. [Azienda Universitaria Ospedaliera ' S. Luigi' Orbassano (Tonga) (Italy); Cappelletti, P. [Azienda Ospedaliera Sant' Anna di Como (Italy); Chiari, P. [Universita degli Studi di Pavia (Italy); Conti, V. [Universita degli Studi di Milano (Italy); Frigerio, M.; Gelosa, S. [Azienda Ospedaliera Sant' Anna di Como (Italy); Giannini, G. [INFN, sez. Trieste (Italy); Hasan, S. [Universita degli Studi dell' Insubria (Italy); INFN, sez. Milano Bicocca (Italy); Mascagna, V. [Universita degli Studi dell' Insubria (Italy); Universita degli Studi di Brescia (Italy); Mauri, P. [CNR di Milano (Italy); Monti, A.F. [Azienda Ospedaliera Sant' Anna di Como (Italy); Mozzanica, A. [Paul Scherrer Institut, Villigen (Switzerland); Ostinelli, A. [Azienda Ospedaliera Sant' Anna di Como (Italy); Prest, M. [Universita degli Studi dell' Insubria (Italy); INFN, sez. Milano Bicocca (Italy); Scazzi, S. [Universita degli Studi dell' Insubria (Italy); Vallazza, E. [INFN, sez. Trieste (Italy); Zanini, A. [INFN, sez. Torino (Italy)

    2009-06-01

    Boron Neutron Capture Therapy (BNCT) is a radiotherapic technique exploiting the {alpha} particles produced after the irradiation of the isotope 10 of boron with thermal neutrons in the capture reaction {sup 10}B(n,{alpha}){sup 7}Li. It is used to treat tumours that for their features (radioresistance, extension, localization near vital organs) cannot be treated through conventional photon-beams radiotherapy. One of the main limitations of this technique is the lack of specificity (i.e. the ability of localizing in tumour cells, saving the healthy tissues) of the compounds used to carry the {sup 10}B isotope in the organs to be treated. This work, developed in the framework of the INFN PhoNeS project, describes the possibility of boron imaging performed exploiting the neutrons photoproduced by a linac (the Clinac 2100C/D of the S. Anna Hospital Radiotherapy Unit in Como, Italy) and detecting the {alpha} s with a non-depleted microstrip silicon detector: the result is a 1D scan of the boron concentration. Several boron doped samples have been analysed, from solutions of H{sub 3}BO{sub 3} (reaching a minimum detectable amount of 25 ng of {sup 10}B) to biological samples of urine containing BPA and BSH (the two molecules currently used for the clinical trials in BNCT) in order to build kinetic curves (showing the absolute {sup 10}B concentration as a function of time). Further measurements are under way to test the imaging system with {sup 10}BPA-Fructose complex perfused human lung samples.

  10. Determination of boron in aqueous solutions by solid state nuclear track detectors technique, using a filtered neutron beam

    International Nuclear Information System (INIS)

    The solid state nuclear track detectors technique has been used for determination of boron in aqueous solutions, using a filtered neutron beam. The particles tracks from the 10B(n,α)Li7 reaction were registered in the CR-39 film, chemically etched in a (30%) KOH solution 700C during 90 minutes. The obtained results showed the usefulness of this technique for boron determination in the ppm range. The inferior detectable limit was 9 ppm. The combined track registration efficiency factor K has been evaluated in the solutions, for the CR-39 detector and its values is K= (4,60 -+ 0,06). 10 -4 cm. (Author)

  11. Investigation of optical, structural and morphological properties of nanostructured boron doped TiO2 thin films

    Indian Academy of Sciences (India)

    Savaş Sönmezoǧlu; Banu Erdoǧan; İskender Askeroǧlu

    2013-12-01

    Pure and different ratios (1, 3, 5, 7 and 10%) of boron doped TiO2 thin films were grown on the glass substrate by using sol–gel dip coating method having some benefits such as basic and easy applicability compared to other thin film production methods. To investigate the effect of boron doped on the physical properties of TiO2, structural, morphological and optical properties of growth thin films were examined. 1% boron-doping has no effect on optical properties of TiO2 thin film; however, optical properties vary with > 1%. From X-ray diffraction spectra, it is seen that TiO2 thin films together with doping of boron were formed along with TiB2 hexagonal structure having (111) orientation, B2O3 cubic structure having (310) orientation, TiB0.024O2 tetragonal structure having rutile phase (110) orientation and polycrystalline structures. From SEM images, it is seen that particles together with doping of boron have homogeneously distributed and held onto surface.

  12. Boron dilution transient simulation analyses in a PWR with neutronics/thermal-hydraulics coupled codes in the NURISP project

    International Nuclear Information System (INIS)

    Highlights: • We simulated three boron dilution transient with different NK–TH coupled codes. • We extensively analyzed the sensitivity to the main parameters. • We found the most balanced combination to reproduce the results. - Abstract: The detailed 3D calculation of a boron slug transient with neutronics/thermal-hydraulics coupled systems has been a highly demanding exercise because of the difficulty coupling with boron transport models. Within subproject 3 of the FP7 European Project NURISP, two neutron kinetics codes, COBAYA3 and DYN3D, coupled with the thermal-hydraulics code FLICA4 in the NURESIM platform were employed to simulate boron dilution transients. Three transients were defined in the project, involving increasing volumes of diluted water entering the core inlet, to test the adequacy of the coupling between the codes. The results obtained with COBAYA3/FLICA4 and DYN3D/FLICA4 couplings for the PWR boron dilution benchmark defined are presented. Additionally, results from the coupled codes DYN3D/FLOCAL are applied for further verification. The results verify the applicability of the implemented couplings to this type of problems, where peak powers reached can be very high during short periods after which the reactor stabilizes at a few per cent of the nominal power. Also generation of vapour is obtained in the simulations

  13. 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)

  14. 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)

  15. 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.

  16. 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 %.

  17. 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.

  18. Boron-10 ABUNCL Models of Fuel Testing

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-10-01

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

  19. Behavior of Disordered Boron Carbide under Stress

    Science.gov (United States)

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

    2006-07-01

    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 6GPa≈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.

  20. Investigation of boron segregation in low carbon steel

    OpenAIRE

    J. Lis; Lis, A; Kolan, C.

    2011-01-01

    Traces of born in the range 0,002-0,009 % are usually added to many grades of steel. The effect of boron on phase transformations and hardenability of low carbon low alloy steels depends on the form of its behavior in solid solution either in segregations or in precipitations. Temperature and cooling rate determine the existence of boron segregations on grain boundaries. In present paper simulations of boron concentrations were calculated with computer programme DICTRA for low carbon 0,08 %C ...

  1. Boron/aluminum shelf for shuttle orbiter

    International Nuclear Information System (INIS)

    Boron/aluminum skins and channels were used in the fabrication of a prototype honeycomb sandwich avionics shelf. The avionic shelves are stiffness-critical and must be vibration tolerant. In conjunction with the shelf mounting system, they must isolate the avionics equipment from the severe vibration of the primary and secondary structure nearby. Design rationale, fabrication procedures, vibration test criteria and test results are presented. (9 fig) (U.S.)

  2. 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...

  3. 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.

  4. 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.

  5. Thermal conductivity of nanostructured boron nitride materials.

    Science.gov (United States)

    Tang, Chengchun; Bando, Yoshio; Liu, Changhong; Fan, Shoushan; Zhang, Jun; Ding, Xiaoxia; Golberg, Dmitri

    2006-06-01

    We have measured the thermal conductivity of bulky pellets made of various boron nitride (BN)-based nanomaterials, including spherical nanoparticles, perfectly structured, bamboo-like nanotubes, and collapsed nanotubes. The thermal conductivity strongly depends on the morphology of the BN nanomaterials, especially on the surface structure. Spherical BN particles have the lowest thermal conductivity while the collapsed BN nanotubes possess the best thermoconductive properties. A model was proposed to explain the experimental observations based on the heat percolation passage considerations. PMID:16722739

  6. Channeling of boron ions into silicon

    Energy Technology Data Exchange (ETDEWEB)

    Lecrosnier, D.; Paugam, J.; Gallou, J.

    1977-04-01

    Channeled and random distributions of boron ions implanted over the energy range 50 keV--1.8 MeV into silicon have been measured using the differential capacitance technique. When implantations are performed along the <110> or <111> axis, profiles exhibit a strong orientation dependance. The best channeled profiles shows that more than 70% of the implanted dose is in the channeled peak.

  7. Boron carbide synthesis by plasma spray process

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Brožek, Vlastimil; Hofman, R.

    Bari : Department of Chemistry, University of Bari, 2003 - (d'Agostino, R.; Favia, P.; Fracassi, F.; Palumbo, F.), s. - [International Symposium on Plasma Chemistry/16th./. Taormina (IT), 22.06.2003-27.06.2003] R&D Projects: GA ČR GA104/01/0149 Institutional research plan: CEZ:AV0Z2043910 Keywords : boron carbide , plasma spray, synthesis Subject RIV: BL - Plasma and Gas Discharge Physics

  8. Plasma Spray Deposition of Boron Carbide

    Czech Academy of Sciences Publication Activity Database

    Brožek, Vlastimil; Hofman, R.; Ctibor, Pavel; Hrabovský, Milan

    Praha : MAXDORF, s.r.o., 2002 - (Nitsch, K.; Rodová, M.). s. 11-12 [Development of Materials Science in Research and Education.. 10.09.2002-12.09.2002, Ostravice] R&D Projects: GA ČR GA104/01/0149; GA ČR GA202/01/1563 Institutional research plan: CEZ:AV0Z2043910 Keywords : plasma spray, boron carbide Subject RIV: BL - Plasma and Gas Discharge Physics

  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. 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

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

    OpenAIRE

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

    2010-01-01

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

  14. 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

  15. 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

  16. Analysis of heterogeneous boron dilution sequences

    International Nuclear Information System (INIS)

    In the scope of the international SETH project (focused on boron dilution sequences), the Spanish Nuclear Regulatory Commission (CSN) and the electric energy industry of Spain (UNESA) have promoted in Spain a national project for the analysis and application of the SETH results to the Spanish nuclear power plants. As part of this project, our team has performed a review and analysis of the different sequences that could lead to a boron dilution in the primary circuit of a pressurized water reactor (PWR). On a first stage of the project we have analyzed the different sequences and the phenomenologies that could lead to inadvertent boron dilution in the primary system (about twenty different sequences are described in the literature), the core damage frequency of each one, the projects and experiments carried out on several experimental facilities and the modifications performed in order to avoid or to mitigate this kind of sequences. On a second one we have reviewed the relation between the operating procedures, Westinghouse design reactors, and this kind of sequences. Finally we have analyzed the simulation problems of these kind of sequences and performed several numerical simulations with the TRAC-M (TRACE) code applied to numerical benchmarks and also to a 3D vessel model. (author)

  17. Boron-containing nuclear safety materials

    International Nuclear Information System (INIS)

    As insurance against reactor runaway or other unplanned excursions, gas-cooled, graphite-moderated reactors are provided with a secondary shut-down mechanism which serves as a back-up to the primary control rod system. This back-up includes a hopper located above fuel channels in the core, equipped with a quick discharge mechanism, which is filled with boron-containing spheres. In an emergency, this hopper discharges the spheres which then cascade down the channels and ''poison'' the uranium fission reaction by absorbing thermal neutrons - the propagators of the chain reaction. Within six months time, a process was successfully developed based on silicon carbide reaction-bonding, which yielded a strong, hard, oxidation-resistant, boron-containing shut-down ball. Test materials were exposed to water saturated argon for three hours at each of several temperatures. While normal boron carbide-graphite balls were completely vaporized, the Cerashield balls remained basically unaffected. Had the reactor at Chernobyl been outfitted with Cerashield shut-down balls, it might never have become famous

  18. 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

  19. 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.

  20. Boron distribution in normal and impaired vascular tissue

    International Nuclear Information System (INIS)

    The microdistribution of boron compounds and the response to Boron Neutron Capture Therapy (BNCT) in normal or impaired vascular structures have not been fully investigated. In this study, we measured the boron concentrations in rat normal vascular tissue for a potential application of BNCT to prevent restenosis following carotid stenting. Male inbred Wistar rats, 6 weeks of age, were used. After intravenous administration of boron compounds (BSH, BPA, or boron porphyrins), rats were killed at either 1, 2, or 3 hours, and the aortic arch, vena cava, blood, liver, kidney, muscle, skin, and brain were collected for measuring boron concentrations in the sample. Boron concentrations in vascular structures, although dependent on the time after administration, are higher than those in blood and surrounding tissue such as muscle or skin. Given that boron compounds such as boron porphyrins are incorporated into arterial tissues, and more into impaired than in normal intima, BNCT might be effective in inhibiting restenosis following carotid artery stenting or coronary artery stenting. (author)

  1. Boron isotope fractionation during brucite deposition from artificial seawater

    OpenAIRE

    J. Xiao; Xiao, Y. K.; Liu, C. Q.; Z. D. Jin

    2011-01-01

    Experiments involving boron incorporation into brucite (Mg(OH)2) from magnesium-free artificial seawater with pH values ranging from 9.5 to 13.0 were carried out to better understand the incorporation behavior of boron into brucite and the influence of it on Mg/Ca-SST proxy and δ11B-pH proxy. The results show that both the concentration of boron in deposited brucite ([B]d) and its boron partition coefficient (

  2. Boron isotope fractionation during brucite deposition from artificial seawater

    OpenAIRE

    J. Xiao; Xiao, Y. K.; Liu, C. Q.; Z. D. Jin

    2011-01-01

    Experiments involving boron incorporation into brucite (Mg(OH)2) from magnesium-free artificial seawater with pH values ranging from 9.5 to 13.0 were carried out to better understand the incorporation behavior of boron into brucite and the influence of it on Mg/Ca-SST proxy and δ11B-pH proxy. The results show that both the concentration of boron in deposited brucite ([B]d) and its boron partition coefficient (Kd) between deposited brucite and final seawater are control...

  3. Combustion synthesis of boron carbide - a spectroscopic studies

    International Nuclear Information System (INIS)

    Boron Carbide is one of the hardest materials known, ranking third behind diamond and cubic boron nitride. It is the hardest material produced in tonnage quantities. Boron carbide (BxCx) enriched in the 10B isotope is used as a control rod material in the nuclear industry due to its high neutron absorption cross section and other favorable physico-chemical properties. Conventional methods of preparation of boron carbide are energy intensive processes accompanied by huge loss of boron. Attempts were made at IGCAR Kalpakkam to develop energy efficient and cost effective methods to prepare boron carbide. Nuclear applications of boron carbide include shielding, control rod and shut down pellets. Within control rods, boron carbide is often powdered, to increase its surface area. The products of the gel combustion and microwave synthesis experiments were characterized for phase purity by X-ray diffraction (XRD). The carbide formation was ascertained using finger-print spectroscopy of Fourier transform infrared (FTIR). Samples of pyrolized/microwave heated powder were characterized for surface morphology using electron microscope (SEM). The present work shows the recent advances in understanding of structural and chemical variation in boron carbide and their influence on morphology, optical and vibrational property result discussed in details. (author)

  4. 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.)

  5. 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.

  6. ADSORPTION POTENTIAL OF UNMODIFIED RICE HUSK FOR BORON REMOVAL

    OpenAIRE

    Hasfalina Che Man,; Wei Hong Chin,; Maryam Rahmati Zadeh,; Mohd Rashid Mohd Yusof

    2012-01-01

    A batch study of boron removal from aqueous solutions by adsorption using rice husk was carried out. The effect of selected parameters such as particle size, pH, adsorbent dosage, and initial concentration of adsorbate on boron removal was investigated in the study. Results showed that the maximum boron removal was obtained with the rice husk particle size between 0.425 mm and 1.0 mm at pH 5. Boron removal was increased with an increasing amount of adsorbent dosage but decreased as the initia...

  7. 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.

  8. 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.

  9. Mechanisms of the boron carbide and boron nitride preferred sputtering by low energy ions bombardment

    International Nuclear Information System (INIS)

    The ion irradiation of BN and B4C leads to enriching of the materials with the lighter component - borons as the experiment shows . With a view to explain this effect sputtering of BN and B4C under the irradiation by the He+ and Ar+ ions with the energy E0=0,5-5 keV has been calculated with computer modelling and the real structure of BN has been considered. In the case of B4C the calculations have been carried with Monte-Carlo code. It was shown that enriching of BN by boron may be accounted for building up the molecules N2 on the irradiated surface and their desorbing. The enriching of B4C with boron results from the difference of the binding energy of the B and C atoms. (author). 10 refs., 5 tabs

  10. 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.)

  11. 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.

  12. Determination of isotopic composition of boron in boron carbide by TIMS and PIGE: an inter-comparison study

    International Nuclear Information System (INIS)

    The paper reports a comparison of results on the determination of isotopic composition of boron in boron carbide (B4C) samples by Thermal Ionisation Mass Spectrometry (TIMS) and Particle Induced Gamma ray Spectrometry (PIGE). B4C samples having varying boron isotopic composition (natural, enriched with respect to 10B) and their synthetic mixtures) have been analysed by both the techniques. The 10B atom% was found to be in the range of 20-67%. (author)

  13. 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

  14. Determination of boron in graphite, boron carbide and glass by ICP-MS, ICP-OES and conventional wet chemical methods

    International Nuclear Information System (INIS)

    Boron is an important element of interest in nuclear reactor materials due to its high neutron absorption cross section (σ0 =3837 barns for 10B). In the present paper, R and D work and routinely used methods have been described for the analysis of case samples (1) Graphite where boron is present at trace levels, (2) Boron Carbide having boron concentration of about 80% and (3) Glass containing 4-6 % boron. (author)

  15. 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

  16. 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

  17. 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

  18. Boron isotope fractionation during brucite deposition from artificial seawater

    Directory of Open Access Journals (Sweden)

    J. Xiao

    2011-03-01

    Full Text Available Experiments involving boron incorporation into brucite (Mg(OH2 from magnesium-free artificial seawater with pH values ranging from 9.5 to 13.0 were carried out to better understand the incorporation behavior of boron into brucite. The results show that both concentration of boron in deposited brucite ([B]d and its boron partition coefficient (Kd between deposited brucite and final seawater are controlled by pH of the solution. The incorporation capacity of boron into brucite is much stronger than that into oxides and clay minerals. The isotopic compositions of boron in deposited brucite (δ11Bd are higher than those in the associated artificial seawater (δ11Bisw with fractionation factors ranging between 1.0177 and 1.0569, resulting from the preferential incorporation of B(OH3 into brucite. Both boron adsorptions onto brucite and precipitation reaction of H3BO3 with brucite exist during deposition of brucite from artificial seawater. The simultaneous occurrence of both processes determines the boron concentration and isotopic fractionation of brucite. The isotopic fractionation behaviors and mechanisms of boron incorporated into brucite are different from those into carbonates. Furthermore, the isotopic compositions of boron in modern corals might be affected by the existence of brucite in madrepore and the preferential incorporation of B(OH3 into brucite. An exploratory study for the influence of brucite on the boron isotopic composition in modern corals is justifiable.

  19. Extractability, plant yield and toxicity thresholds for boron in compost

    Energy Technology Data Exchange (ETDEWEB)

    Brinton, W.F.; Evans, E.; Blewett, C. [Woods End Labs Inc., Mt. Vernon, ME (United States)

    2008-04-01

    Boron (B) is a trace element essential to crop growth in small soil concentrations (0.2-1.5ppm), yet may produce plant toxicity symptoms readily as the amount in the soil solution increases over 2ppm. Our study examined commercial compost made with coal fly-ash used to prepare growing media for cultivars of varying sensitivity (corn, beans, cucumber, peas). We examined total vs. extractable boron content and relate final visual symptoms of B-toxicity to yields and tissue concentrations. Visual toxicity effects included tip burn (corn), leaf mottling and necrosis (beans and peas) and leaf mottling and cupping (cucumbers). Fly ash added to compost increased hot-water soluble (HWS) B in proportion to rate and in dependence on pH, with 30% and 10% of total-B expressed as HWS-B at a media pH of 6 and 7.5, respectively. Biomass for bean and cucumber was significantly reduced by 45 to 55%, respectively, by addition of 33% fly-ash compost to growing media (28ppm total-B) while plant tissue-B increased by 6- to 4-fold, respectively. Economic yield depressions in compost media are evident for all crops and appeared at levels of HWS-B in compost media exceeding 5 ppm. The study underscores the need for careful management of exogenous factors that may be present in composts and suggests detailed understanding of media-pH and cultivar preferences may be required in preparation of growing media in order to reduce potential negative growth effects.

  20. 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.

  1. Feasibility study on pinhole camera system for online dosimetry in boron neutron capture therapy

    International Nuclear Information System (INIS)

    The feasibility of a pinhole camera system for online dosimetry in boron neutron capture therapy (BNCT) was studied. A prototype system was designed and built. Prompt γ-rays from the 10B(n,α)7Li reaction from a phantom irradiated with neutrons were detected with the prototype system. An image was reconstructed from the experimental data. The reconstructed image showed a good separation of the two borated regions in the phantom. The counting rates and signal-to-noise ratio when using the system in actual BNCT applications are also discussed. - Author-Highlights: • The feasibility of a pinhole camera system for online dosimetry in BNCT was studied. • A prototype pinhole camera system for online dose imaging for BNCT was built. • Prompt γ-rays from a phantom irradiated with neutrons were detected. • The boron-10 reaction rate distribution was reconstructed from the experimental data

  2. Sintering boron carbide ceramics without grain growth by plastic deformation as the dominant densification mechanism

    Science.gov (United States)

    Ji, Wei; Rehman, Sahibzada Shakir; Wang, Weimin; Wang, Hao; Wang, Yucheng; Zhang, Jinyong; Zhang, Fan; Fu, Zhengyi

    2015-10-01

    A new ceramic sintering approach employing plastic deformation as the dominant mechanism is proposed, at low temperature close to the onset point of grain growth and under high pressure. Based on this route, fully dense boron carbide without grain growth can be prepared at 1,675-1,700 °C and under pressure of (≥) 80 MPa in 5 minutes. The dense boron carbide shows excellent mechanical properties, including Vickers hardness of 37.8 GPa, flexural strength of 445.3 MPa and fracture toughness of 4.7 MPa•m0.5. Such a process should also facilitate the cost-effective preparation of other advanced ceramics for practical applications.

  3. Early clinical experience of boron neutron capture therapy for glioblastoma multiforme

    International Nuclear Information System (INIS)

    Boron neutron capture therapy (BNCT) is a binary treatment modality that can selectively irradiate tumor tissue. BNCT uses drugs containing a stable isotope of boron. 10B, to sensitize tumor cells to irradiation by low energy (thermal) neutrons. The interaction of the 10B with a thermal neutron (neutron capture) causes the 10B nucleus to split, releasing an alpha particle and a lithium nucleus. These products of the 10B(n, α)7Li reaction are very damaging to cells but have a combined path length in tissue of approximately 14 μm, or roughly the diameter of one or two cells. Thus, most of the ionizing energy imparted to tissue is localized to 10B-loaded cells

  4. Early clinical experience of boron neutron capture therapy for glioblastoma multiforme

    Energy Technology Data Exchange (ETDEWEB)

    Joel, D.D.; Bergland, R.; Capala, J. [and others

    1995-12-31

    Boron neutron capture therapy (BNCT) is a binary treatment modality that can selectively irradiate tumor tissue. BNCT uses drugs containing a stable isotope of boron. {sup 10}B, to sensitize tumor cells to irradiation by low energy (thermal) neutrons. The interaction of the {sup 10}B with a thermal neutron (neutron capture) causes the {sup 10}B nucleus to split, releasing an alpha particle and a lithium nucleus. These products of the {sup 10}B(n, {alpha}){sup 7}Li reaction are very damaging to cells but have a combined path length in tissue of approximately 14 {mu}m, or roughly the diameter of one or two cells. Thus, most of the ionizing energy imparted to tissue is localized to {sup 10}B-loaded cells.

  5. Thermal reduction reactions in the exothermal processes of boron nitride synthesis by CVD

    International Nuclear Information System (INIS)

    Thermodynamic analysis of adiabatic heat-up of reactions and equilibrium composition of products in the systems BCl3-N2-M (M = Li, Na, Cs), BCl3-M, BCl3-N2-H2, BCl3-H2 has been carried out to fit the preparation of boron nitride on the basis of exothermal CVD-processes, based on chemical deposition from vapor phase. In temperature range 300-3000 K and at atmospheric pressure optimal regions of boron nitride yield are determined and general mechanism of the process is suggested. Strong effect of chemical heat release on equilibrium products composition and mechanism of their formation has been detected. 7 refs.; 4 figs

  6. Combined action of thermal neutron irradiation and boron-10-amino acid analogs on a solid experimental tumor (EO771 C57 B1/6J)

    International Nuclear Information System (INIS)

    Two boron-amino acid analogs were synthesized with enriched boron (90% 10B): (a) The compound Trimethylamine-carboxyborane (Mol weight: 116.2) contains 8.7% boron, and (b) Amine-carboxyborane (Mol weight: 74.1) contains 13.6% boron and shows a good solubility in water. The solid Adenocarcinoma EO 771 on C57 B1/6J mice was used as test object. The tumor-bearing animals were irradiated in a thermal column of the swimming-pool type reactor FRJ-1 (MERLIN); the bodies were shielded against thermal neutrons by a boron carbide-plastic mixture. The thermal neutron flux was 2.3 x 1010n/cm2 sec. at the tumor. Boron concentrations in tumor, liver, muscle and in blood were analysed by emission spectroscopy. The effects of the tumor treatment were evaluated by tumor volume measurements. Cell cycle changes were analysed by means of flow cytometry using the ICP-22 from Phywe

  7. Design of boron carbide-shielded irradiation channel of the outer irradiation channel of the Ghana Research Reactor-1 using MCNP

    International Nuclear Information System (INIS)

    The MCNP model for the Ghana Research Reactor-1 was redesigned to incorporate a boron carbide-shielded irradiation channel in one of the outer irradiation channels. Extensive investigations were made before arriving at the final design of only one boron carbide covered outer irradiation channel; as all the other designs that were considered did not give desirable results of neutronic performance. The concept of redesigning a new MCNP model, which has a boron carbide-shielded channel is to equip the Ghana Research Reactor-1 with the means of performing efficient epithermal neutron activation analysis. After the simulation, a comparison of the results from the original MCNP model for the Ghana Research Reactor-1 and the new redesigned model of the boron carbide shielded channel was made. The final effective criticality of the original MCNP model for the GHARR-1 was recorded as 1.00402 while that of the new boron carbide designed model was recorded as 1.00282. Also, a final prompt neutron lifetime of 1.5245x10-4 s was recorded for the new boron carbide designed model while a value of 1.5571x10-7 s was recorded for the original MCNP design of the GHARR-1.

  8. Design of boron carbide-shielded irradiation channel of the outer irradiation channel of the Ghana Research Reactor-1 using MCNP.

    Science.gov (United States)

    Abrefah, R G; Sogbadji, R B M; Ampomah-Amoako, E; Birikorang, S A; Odoi, H C; Nyarko, B J B

    2011-01-01

    The MCNP model for the Ghana Research Reactor-1 was redesigned to incorporate a boron carbide-shielded irradiation channel in one of the outer irradiation channels. Extensive investigations were made before arriving at the final design of only one boron carbide covered outer irradiation channel; as all the other designs that were considered did not give desirable results of neutronic performance. The concept of redesigning a new MCNP model, which has a boron carbide-shielded channel is to equip the Ghana Research Reactor-1 with the means of performing efficient epithermal neutron activation analysis. After the simulation, a comparison of the results from the original MCNP model for the Ghana Research Reactor-1 and the new redesigned model of the boron carbide shielded channel was made. The final effective criticality of the original MCNP model for the GHARR-1 was recorded as 1.00402 while that of the new boron carbide designed model was recorded as 1.00282. Also, a final prompt neutron lifetime of 1.5245 × 10(-4)s was recorded for the new boron carbide designed model while a value of 1.5571 × 10(-7)s was recorded for the original MCNP design of the GHARR-1. PMID:20637646

  9. Therapeutic efficacy of boron neutron capture therapy mediated by boron-rich liposomes for oral cancer in the hamster cheek pouch model

    Energy Technology Data Exchange (ETDEWEB)

    Heber, Elisa M. [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Hawthorne, M. Frederick [Univ. of Missouri, Columbia, MO (United States). International Inst. of Nano and Molecular Medicine; Kueffer, Peter J. [Univ. of Missouri, Columbia, MO (United States). International Inst. of Nano and Molecular Medicine; Garabalino, Marcela A. [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Thorp, Silvia I. [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Pozzi, Emiliano C. C. [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Hughes, Andrea Monti [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Maitz, Charles A. [Univ. of Missouri, Columbia, MO (United States). International Inst. of Nano and Molecular Medicine; Jalisatgi, Satish S. [Univ. of Missouri, Columbia, MO (United States). International Inst. of Nano and Molecular Medicine; Nigg, David W. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Curotto, Paula [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Trivillin, Verónica A. [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Schwint, Amanda E. [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina)

    2014-11-11

    Unilamellar liposomes formulated with an equimolar mixture of cholesterol and 1,2-distearoyl-sn-glycero-3-phosphocholine, incorporating K[nido-7-CH3(CH2)15-7,8-C2B9H11] in the lipid bilayer, and encapsulating Na3[1-(2’-B10-H9)-2-NH3B10H8] were prepared by probe sonication and investigated in vivo. Microwave assisted digestion followed by inductively coupled plasma-optical emission spectroscopy was utilized to determine the biodistribution of boron in various tissues following either a single tail vein injection or two identical injections (separated by 24 hours) of the liposomal suspension in BALB/c mice bearing EMT6 mammary adenocarcinomas in their right flank. Double-injection protocols resulted in a boron content in the tumor exceeding 50 µg of boron per gram of tissue for 48 to 72 hours subsequent to the initial injection while tumor:blood boron ratios were more ideal from 54 hours (1.9:1) to 96 hours (5.7:1) subsequent to the initial injection. Tumor bearing mice were given a double-injection of liposomes containing the 10B-enriched analogs of the aforementioned agents and subjected to a 30 minute irradiation by thermal neutrons with a flux of 8.8 x 1087%) neutrons/cm2 s integrated over the energy range of 0.0 – 0.414 eV. Significant tumor response for a single BNCT treatment was demonstrated by growth curves versus a control group. Vastly diminished tumor growth was witnessed at 14 days (186% increase versus 1551% in controls) in mice that were given a second injection/radiation treatment 7 days after the first. Mice given a one hour neutron irradiation following the double-injection of liposomes had a similar response (169% increase at 14 days) suggesting that neutron fluence is the limiting factor towards BNCT efficacy in this study.

  10. 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.

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

    International Nuclear Information System (INIS)

    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/cm2. 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 CaCl2. Added CaCl2 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

  12. 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.

  13. 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.

  14. 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.

  15. 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)

  16. 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.

  17. Finite Element Analysis Of Boron Diffusion In Wood

    DEFF Research Database (Denmark)

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

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

  18. Brazed boron-silicon carbide/aluminum structural panels

    Science.gov (United States)

    Arnold, W. E., Jr.; Bales, T. T.; Brooks, T. G.; Lawson, A. G.; Mitchell, P. D.; Royster, D. M.; Wiant, R.

    1978-01-01

    Fluxless brazing process minimizes degradation of mechanical properties composite material of silicon carbide coated boron fibers in an aluminum matrix. Process is being used to fabricate full-scale Boron-Silicon Carbide/Aluminum-Titanium honeycomb core panels for flight testing and ground testing.

  19. Highly thermal conductive carbon fiber/boron carbide composite material

    International Nuclear Information System (INIS)

    In a composite member for use in walls of a thermonuclear reactor, if carbon fibers and boron carbide are mixed, since they are brought into contact with each other directly, boron is reacted with the carbon fibers to form boron carbide to lower thermal conductivity of the carbon fibers. Then, in the present invention, graphite or amorphous carbon is filled between the carbon fibers to provide a fiber bundle of not less than 500 carbon fibers. Further, the surface of the fiber bundle is coated with graphite or amorphous carbon to suppress diffusion or solid solubilization of boron to carbon fibers or reaction of them. Then, lowering of thermal conductivity of the carbon fibers is prevented, as well as the mixing amount of the carbon fiber bundles with boron carbide, a sintering temperature and orientation of carbon fiber bundles are optimized to provide a highly thermal conductive carbon fiber/boron carbide composite material. In addition, carbide or boride type short fibers, spherical graphite, and amorphous carbon are mixed in the boron carbide to prevent development of cracks. Diffusion or solid solubilization of boron to carbon fibers is reduced or reaction of them if the carbon fibers are bundled. (N.H.)

  20. 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.

  1. Boron compounds as potential HIV-1 protease inhibitors

    Czech Academy of Sciences Publication Activity Database

    Plešek, Jaromír; Grüner, Bohumír; Král, V.; Cígler, Petr; Kožíšek, Milan; Prejdová, Jana; Pokorná, Jana; Kräusslich, H. G.; Bodem, J.; Konvalinka, Jan

    Tohoku: Graduate School of Science, 2005, s. 46. [International Conference on Boron Chemistry /12./. Sendai (JP), 11.09.2005-15.09.2005] R&D Projects: GA MŠk(CZ) LC523 Institutional research plan: CEZ:AV0Z40320502 Keywords : boron cluster compounds Subject RIV: CA - Inorganic Chemistry

  2. 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

  3. 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 .

  4. Safety assessment of boron in aquatic and terrestrial environments.

    Science.gov (United States)

    Butterwick, L; de Oude, N; Raymond, K

    1989-06-01

    Boron is a naturally occurring material and is used in industrial and domestic products. Its major release into the environment is through weathering processes and wastewater discharge. Boron is an essential nutrient for plants, but can above certain concentrations be toxic to aquatic and terrestrial organisms. This paper assesses the ecotoxicology and environmental safety of boron. It draws together the data for toxicological effects of boron and compares these with environmental concentrations of boron, measured in Europe and the U.S.A. Generally, environmental concentrations of boron found in surface water are below levels identified as toxic to aquatic organisms. Concentrations high enough to produce toxic effects in laboratory tests are found in areas where weathering of boron-rich formations and deposits occurs, such as in the southwestern United States. However, reproducing populations of the most sensitive species, rainbow trout, have been observed in surface waters in these regions, indicating no cause for concern. The prime concern for effects on terrestrial plants centers on the use of irrigation water with elevated levels of boron. At present, there is no evidence of widespread damage to crops resulting from this practice. In some areas, wastewater is used for irrigation and crops grown under these conditions are generally confined to those relatively insensitive to boron toxicity. Good irrigation practices will be necessary, however, in arid regions with high evapotranspiration rates and care will be needed when using wastewater, particularly in areas with naturally high boron levels. It is not anticipated that there will be any significant increase in the discharge of boron to the environment in the foreseeable future. The use of boron-containing products is expected to increase, but glass will remain the dominant market and the use of boron in detergents in Europe is expected to decrease due to the introduction of bleach activators and liquid

  5. Neutron capture therapy of epidermal growth factor (+) gliomas using boronated cetuximab (IMC-C225) as a delivery agent

    International Nuclear Information System (INIS)

    Cetuximab (IMC-C225) is a monoclonal antibody directed against both the wild-type and mutant vIII isoform of the epidermal growth factor receptor (EGFR). The purpose of the present study was to evaluate the monoclonal antibody (MoAb), cetuximab, as a boron delivery agent for neutron capture therapy (NCT) of brain tumors. Twenty-four hours following intratumoral (i.t.) administration of boronated cetuximab (C225-G5-B1100), the mean boron concentration in rats bearing either F98EGFR or F98WT gliomas were 92.3±23.3 μg/g and 36.5±18.8 μg/g, respectively. In contrast, the uptake of boronated dendrimer (G5-B1000) was 6.7±3.6 μg/g. Based on its favorable in vivo uptake, C225-G5-B1100 was evaluated as a delivery agent for BNCT in F98EGFR glioma bearing rats. The mean survival time (MST) of rats that received C225-G5-B1100, administered by convection enhanced delivery (CED), was 45±3 d compared to 25±3 d for untreated control animals. A further enhancement in MST to >59 d was obtained by administering C225-G5-B1100 in combination with i.v. boronophenylalanine (BPA). These data are the first to demonstrate the efficacy of a boronated MoAb for BNCT of an intracerebral (i.c.) glioma and are paradigmatic for future studies using a combination of boronated MoAbs and low molecular weight delivery agents

  6. Neutron capture therapy of epidermal growth factor (+) gliomas using boronated cetuximab (IMC-C225) as a delivery agent

    Energy Technology Data Exchange (ETDEWEB)

    Barth, Rolf F. E-mail: barth.1@osu.edu; Wu Gong; Yang Weilian; Binns, Peter J.; Riley, Kent J.; Patel, Hemant; Coderre, Jeffrey A.; Tjarks, Werner; Bandyopadhyaya, A.K.; Thirumamagal, B.T.S.; Ciesielski, Michael J.; Fenstermaker, Robert A

    2004-11-01

    Cetuximab (IMC-C225) is a monoclonal antibody directed against both the wild-type and mutant vIII isoform of the epidermal growth factor receptor (EGFR). The purpose of the present study was to evaluate the monoclonal antibody (MoAb), cetuximab, as a boron delivery agent for neutron capture therapy (NCT) of brain tumors. Twenty-four hours following intratumoral (i.t.) administration of boronated cetuximab (C225-G5-B{sub 1100}), the mean boron concentration in rats bearing either F98{sub EGFR} or F98{sub WT} gliomas were 92.3{+-}23.3 {mu}g/g and 36.5{+-}18.8 {mu}g/g, respectively. In contrast, the uptake of boronated dendrimer (G5-B{sub 1000}) was 6.7{+-}3.6 {mu}g/g. Based on its favorable in vivo uptake, C225-G5-B{sub 1100} was evaluated as a delivery agent for BNCT in F98{sub EGFR} glioma bearing rats. The mean survival time (MST) of rats that received C225-G5-B{sub 1100}, administered by convection enhanced delivery (CED), was 45{+-}3 d compared to 25{+-}3 d for untreated control animals. A further enhancement in MST to >59 d was obtained by administering C225-G5-B{sub 1100} in combination with i.v. boronophenylalanine (BPA). These data are the first to demonstrate the efficacy of a boronated MoAb for BNCT of an intracerebral (i.c.) glioma and are paradigmatic for future studies using a combination of boronated MoAbs and low molecular weight delivery agents.

  7. Depletion modeling of integral burnable absorbers containing enriched boron

    International Nuclear Information System (INIS)

    Depletion modeling of fuel assembly with different integral fuel burnable absorber loadings containing enriched boron has been performed by WIMSD transport code. Equivalent boron concentration that represents depletion of the integral fuel burnable absorbers containing enriched boron has been calculated using modified PSU/LEOPARD code. The calculated equivalent boron concentrations have been introduced into FUMACS computer code package master files, upgrading the code package with new global calculation feature for core modeling with different integral fuel burnable absorber loadings containing enriched boron. This new feature of FUMACS/FEEC2001 code package has been verified and validated on 12-month and 18-month operating cycle core loading patterns of NPP Krsko.(author)

  8. The sorption capacity of boron on anionic-exchange resin

    International Nuclear Information System (INIS)

    Boron sorption capacities on anionic-exchange resins vary with temperature, concentration, and resin cross-linkage. A semiempirical correlation, developed from boron solution chemistry, is presented to account for these variations. The relationship, based on boron chemistry and changes in Gibb's energy, can be stated approximately as Q = a1CBa2Za3 exp[-(a4T + a5T2 + a6Z0.5)]. Correlation parameters, which vary with resin type, are evaluated experimentally. Parameter values for macroporous resin Diaion PA 300 and for gel-type resins Diaion SA10 and Amberlite IRN 78LC are presented. The resulting expression is used to determine boron sorption and desorption limitations on ion exchangers at various temperatures and concentrations, and to determine the interfacial boron concentration in equilibrium and rate models

  9. Investigation of boron segregation in low carbon steel

    Directory of Open Access Journals (Sweden)

    J. Lis

    2011-04-01

    Full Text Available Traces of born in the range 0,002-0,009 % are usually added to many grades of steel. The effect of boron on phase transformations and hardenability of low carbon low alloy steels depends on the form of its behavior in solid solution either in segregations or in precipitations. Temperature and cooling rate determine the existence of boron segregations on grain boundaries. In present paper simulations of boron concentrations were calculated with computer programme DICTRA for low carbon 0,08 %C steel with 0,006 % boron. Investigations were carried out for temperature 1300 – 700°C and cooling rates from 1°C/s to 100°C/s. The changes of boron concentrations in austenite and ferrite after commencement of γ→α phase transformation were established.

  10. Boronization during the first plasma operation on EAST

    International Nuclear Information System (INIS)

    Both ion cyclotron rf and glow discharge boronization have been successfully used for wall conditioning on EAST tokamak device. The whole process is monitored continuously by residual gas analyzer and film thickness monitor. These diagnostics provide detailed information about the boronization. High hydrogen inventory level observed after boronization maybe due to the boronization material used (C2B10H12). Ion cyclontron rf conditioning is proved to be an efficient wall conditioning method for superconducting device because it could be carried out under toroidal magnetic field. In this paper, the procedure of boronization is described, and subsequently sample analysis and the effect on plasma operation are introduced. Conclusion is given at the end

  11. Steam oxidation of boron carbide–stainless steel liquid mixtures

    International Nuclear Information System (INIS)

    In the framework of nuclear reactor core meltdown accidents studies, the oxidation kinetics of boron carbide–stainless steel liquid mixtures exposed to argon/steam atmospheres was investigated at temperatures up to 1527 °C. A B–Cr–Si–O liquid protective layer forms on the surface of the mixtures in contact with steam. This protective layer gradually transforms into a Cr2O3-rich slag. Important quantities of liquid can be projected from the melt during oxidation. These projections are favoured by high B4C contents in the melt, high steam partial pressures and low temperatures. In addition to stainless steel–boron carbide melts, simpler compositions (pure 304L stainless steel, iron–boron, iron–boron carbide and stainless steel–boron) were studied, in order to identify the basic oxidation mechanisms.

  12. Synthesis and photoluminescence property of boron carbide nanowires

    International Nuclear Information System (INIS)

    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. (condensed matter: structure, thermal and mechanical properties)

  13. Advancements in Tumor Targeting Strategies for Boron Neutron Capture Therapy.

    Science.gov (United States)

    Luderer, Micah John; de la Puente, Pilar; Azab, Abdel Kareem

    2015-09-01

    Boron neutron capture therapy (BNCT) is a promising cancer therapy modality that utilizes the nuclear capture reaction of epithermal neutrons by boron-10 resulting in a localized nuclear fission reaction and subsequent cell death. Since cellular destruction is limited to approximately the diameter of a single cell, primarily only cells in the neutron field with significant boron accumulation will be damaged. However, the emergence of BNCT as a prominent therapy has in large part been hindered by a paucity of tumor selective boron containing agents. While L-boronophenylalanine and sodium borocaptate are the most commonly investigated clinical agents, new agents are desperately needed due to their suboptimal tumor selectivity. This review will highlight the various strategies to improve tumor boron delivery including: nucleoside and carbohydrate analogs, unnatural amino acids, porphyrins, antibody-dendrimer conjugates, cationic polymers, cell-membrane penetrating peptides, liposomes and nanoparticles. PMID:26033767

  14. 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.

  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. Boron-nitride coated nuclear fuels

    Energy Technology Data Exchange (ETDEWEB)

    Guenduez, G. [Orta Dogu Teknik Univ., Ankara (Turkey); Uslu, I. [Tuerkiye Atom Enerjisi Kurumu, Ankara (Turkey); Durmazucar, H.H. [Cumhuriyet Univ., Sivas (Turkey)

    1996-10-01

    Pure urania- and urania-gadolinia-containing fuel pellets were coated with boron nitride (BN) to improve the physical and neutronic properties of the fuel. The BN coating seems to have a technological advantage over zirconium-diboride coating. The BN is chemically inert, corrosion resistant, withstands rapid temperature changes, and has a high thermal conductivity. Since gadolinia fuel has low thermal conductivity. Since gadolinia fuel has low thermal conductivity, the gadolinia content can be lowered in the fuel by coating it with BN. In fact, the existence of two burnable absorbers in a fuel introduces desired nuclear properties since gadolinia is a fast-burning and boron a slow-burning element. The BN was deposited on fuel from two different sources, (a) from the reaction of boron trichloride (BCl{sub 3}) and ammonia (NH{sub 3}) at 875 K and (b) from the decomposition of trimethylamine borate complex at 1200 K. The infrared and X-ray diffraction (XRD) spectra of BN from both precursors agreed with the available data in the literature. However BN powder from borane complex had a shifted XRD peak due to the presence of carbonaceous material in the structure. The BN powder-coated fuels were heated to 1400, 1525, and 1600 K to sinter the BN. The examination under scanning electron microscope showed that grainy, rod-shaped and layered BN coatings were achieved. Rod-shaped structures were usually seen on gadolinia fuels. The increased thickness of coating favors the formation of a glassy looking layer. The BN from a borane complex seems to form a layered structure more easily than the BN from BCl{sub 3}. The BN coated the surface of the fuels, and it did not penetrate into the fuels.

  18. Boron-nitride coated nuclear fuels

    International Nuclear Information System (INIS)

    Pure urania- and urania-gadolinia-containing fuel pellets were coated with boron nitride (BN) to improve the physical and neutronic properties of the fuel. The BN coating seems to have a technological advantage over zirconium-diboride coating. The BN is chemically inert, corrosion resistant, withstands rapid temperature changes, and has a high thermal conductivity. Since gadolinia fuel has low thermal conductivity. Since gadolinia fuel has low thermal conductivity, the gadolinia content can be lowered in the fuel by coating it with BN. In fact, the existence of two burnable absorbers in a fuel introduces desired nuclear properties since gadolinia is a fast-burning and boron a slow-burning element. The BN was deposited on fuel from two different sources, (a) from the reaction of boron trichloride (BCl3) and ammonia (NH3) at 875 K and (b) from the decomposition of trimethylamine borate complex at 1200 K. The infrared and X-ray diffraction (XRD) spectra of BN from both precursors agreed with the available data in the literature. However BN powder from borane complex had a shifted XRD peak due to the presence of carbonaceous material in the structure. The BN powder-coated fuels were heated to 1400, 1525, and 1600 K to sinter the BN. The examination under scanning electron microscope showed that grainy, rod-shaped and layered BN coatings were achieved. Rod-shaped structures were usually seen on gadolinia fuels. The increased thickness of coating favors the formation of a glassy looking layer. The BN from a borane complex seems to form a layered structure more easily than the BN from BCl3. The BN coated the surface of the fuels, and it did not penetrate into the fuels

  19. 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.

  20. 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.

  1. 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

  2. Boron Pile v-bar Measurements

    International Nuclear Information System (INIS)

    Accurate absolute measurements of v, the average number of neutrons per fission, have been made with the boron pile. The experimental method is described and results are presented of the v values obtained for the thermal-neutron-induced fission of U233, U235, Pu239 and Pu241, the spontaneous fission of Pu240 and Cf252, and the fast neutron-induced fission of U235 in the energy range 100 keV to 2.6 MeV. (author)

  3. 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.

  4. Boron-containing neutron shielding building ceramics

    International Nuclear Information System (INIS)

    The data are presented on the composition of raw materials as well as on the properties and chemical composition of finished products of ceramics intended for neutron shielding. It is shown that 0.8 % content of B2O3 in bricks of ceramic mass proposed halves neutron radiation from the source of 106 neutr·s-1 close rate compared to bricks of boron free ceramic mass. Results of tests on water absorption and compression strength make it possible to recommend new ceramics to be used as tiles and facade building materials

  5. Salinity’s influence on boron toxicity in broccoli: II. Impacts on boron uptake, uptake mechanisms and tissue ion relations.

    Science.gov (United States)

    Limited research has been conducted on the interactive effects of salinity and boron stresses on plants despite their common occurrence in natural systems. The purpose of this research was to determine and quantify the interactive effects of salinity, salt composition and boron on broccoli (Brassica...

  6. 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)

  7. Boron carbide particles formed from an amorphous boron/graphite powder mixture using a shock-wave technique

    International Nuclear Information System (INIS)

    Boron carbide (B4C) particles with filamental, distorted ellipsoidal, platelike, and polyhedral shapes were formed from vapor generated from an amorphous boron/graphite powder mixture with 14% starting density using a cylindrical shock-wave technique. The crystal phases of shocked compact and microstructures of the B4C particles were characterized by X-ray diffractometry and electron microscopy, respectively

  8. Formulation and preliminary evaluation of delivery vehicles for the boron neutron capture therapy of cancer

    OpenAIRE

    Olusanya, Temidayo; Stich, Theresia; Higgins, Samantha Caroline; Lloyd, Rhiannon Eleanor Iris; Smith, James Richard; Fatouros, Dimitrios; Calabrese, Gianpiero; Pilkington, Geoffrey John; Tsibouklis, John

    2015-01-01

    Boron neutron capture therapy (BNCT) is a method for selectively destroying malignant (normally glioma) cells whilst sparing normal tissue1. Irradiation of 10B (large neutron capture cross-section) with thermal neutrons effects the nuclear fission reaction: 10B + 1n → → 7Li+ + α + γ; where the penetration of α-particles and 7Li+ is only 8 and 5 µm, respectively, i.e., within a single cell thickness, assuming 10B can be preferentially located within glioma cells2. Poor selectivity is the main ...

  9. Formulation and preliminary evaluation of delivery vehicles for the boron neutron capture therapy of cancer

    OpenAIRE

    Olusanya, Temidayo Olajumoke Bolanle

    2015-01-01

    Boron neutron capture therapy (BNCT) is a method for selectively destroying malignant (normally glioma) cells whilst sparing normal tissue. Irradiation of 10B (large neutron capture cross-section) with thermal neutrons effects the nuclear fission reaction: 10B + 1n → → 7Li+ + α + γ; where the penetration of -particles and 7Li+ is only 8 and 5 μm, respectively, i.e., within a single cell thickness, assuming 10B can be preferentially located within glioma cells. Poor selectivity is the main r...

  10. A basic study for the boron thermal regeneration system using anion exchange resins

    International Nuclear Information System (INIS)

    For the boron thermal regeneration system (BTRS), the basic characteristics of commercial anion exchange resin have been investigated on the swelling characteristics, absorption, desorption and temperature coefficient of exchange capacity for boric acid. The equilibrium capacity increases as decrease of temperature and depends strongly on the degrees of cross linking having a maximum point at about 7% of DVB. The temperature coefficient of equilibrium capacity of boric acid is also a function of the concentration of external solution and of the cross linking having a maximum point around 7% of DVB. (author)

  11. 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.

  12. 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

  13. Boron nitride - boron hybrid coating on uranium dioxide-gadolinium oxide fuel. Final report for the period 1 November 1996 - 1 November 1997

    International Nuclear Information System (INIS)

    The report describes work to develop laboratory-scale technology of the deposition of hybrid boron nitrate-metallic boron coating onto the surface of uranium dioxide ore uranium dioxide - gadolinia dioxide fuel pellets. Methods of chemical vapour deposition and plasma enhanced chemical vapour deposition were used in the Department of Chemical Engineering of the Middle East Technical University, Ankara, Turkey. An excellent adherence of boron onto the boron nitrate layer and boron nitrate layer onto the fuel pellet surface was demonstrated. Fine grain-type structure of boron coating and its excellent adherence are good indices for integrated fuel burnable absorber fuels

  14. 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.

  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. 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.

  17. 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.

  18. 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).

  19. 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.

  20. Drug delivery system design and development for boron neutron capture therapy on cancer treatment

    International Nuclear Information System (INIS)

    We have already synthesized a boron-containing polymeric micellar drug delivery system for boron neutron capture therapy (BNCT). The synthesized diblock copolymer, boron-terminated copolymers (Bpin-PLA-PEOz), consisted of biodegradable poly(D,L-lactide) (PLA) block and water-soluble polyelectrolyte poly(2-ethyl-2-oxazoline) (PEOz) block, and a cap of pinacol boronate ester (Bpin). In this study, we have demonstrated that synthesized Bpin-PLA-PEOz micelle has great potential to be boron drug delivery system with preliminary evaluation of biocompatibility and boron content. - Highlights: • Herein, we have synthesized boron-modified diblock copolymer. • Bpin-PLA-PEOz, which will be served as new boron containing vehicle for transporting the boron drug. • This boron containing Bpin-PLA-PEOz micelle was low toxicity can be applied to drug delivery

  1. 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

  2. Boron-10 ABUNCL Prototype Initial Testing

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-12-01

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

  3. Boron Removal from Silicon by Humidified Gases

    Science.gov (United States)

    Safarian, Jafar; Tang, Kai; Hildal, Kjetil; Tranell, Gabriella

    2014-01-01

    Boron (B) is one of the most problematic impurities to remove from metallurgical grade silicon in the production of more pure solar grade silicon (SoG-Si). In the present work, recent progresses in the application of reactive gases for B removal from molten silicon is reviewed. Moreover, in order to clarify the mechanisms and kinetics of gas-based B-refining, an experimental procedure using humidified Ar, N2, and H2 gases applied to boron-doped silicon melt is described. It is shown that the kinetics and extent of B removal is depending on the type of humidified gas. The thermodynamics and kinetics of B removal from molten silicon are studied to explain experimental observations. The mass transfer coefficients of B are calculated and possible mechanisms for B removal by the reactive gases are proposed: 1/2{{H}}2 ({{g}}) &= \\underset{-{H} ,} \\underset{-}{B} + \\underset{H} + {H}2 {O(g)} &= {HBO(g)} + {H}2 . It is shown that the lower equilibrium partial pressure of HBO gas at higher temperatures causes slower B removal rate.

  4. 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.

  5. 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

  6. 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

  7. Axial channeling of boron ions into silicon

    Science.gov (United States)

    La Ferla, A.; Galvagno, G.; Raineri, V.; Setola, R.; Rimini, E.; Carbera, A.; Gasparotto, A.

    1992-04-01

    Channeling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5 × 10 11 and 1 × 10 15 atoms/cm 2. The axial channeling concentration profiles of implanted B + were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, Sc, was extracted from the experimental maximum ranges for the [100] and [110] axis. The energ dependence of the electronic stopping power is given by Sc = KEp with p[100] = 0.469±0.010 and p[110] = 0.554±0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles.

  8. Axial channeling of boron ions into silicon

    International Nuclear Information System (INIS)

    Channeling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5x1011 and 1x1015 atoms/cm2. The axial channeling concentration profiles of implanted B+ were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, Sc, was extracted from the experimental maximum ranges for the [100] and [110] axis. The energy dependence of the electronic stopping power is given by Se = KEp with p[100] = 0.469±0.010 and p[110] = 0.554±0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles. (orig.)

  9. Axial channeling of boron ions into silicon

    Energy Technology Data Exchange (ETDEWEB)

    La Ferla, A.; Galvagno, G. (Ist. di Tecnologie e Metodologie per la Microelettronica, CNR, Dipt. di Fisica, Catania (Italy)); Raineri, V.; Setola, R.; Rimini, E. (Dipt. di Fisica, Univ. di Catania (Italy)); Carnera, A.; Gasparotto, A. (Dipt. di Fisica, Univ. di Padova (Italy))

    1992-04-01

    Channeling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5x10{sup 11} and 1x10{sup 15} atoms/cm{sup 2}. The axial channeling concentration profiles of implanted B{sup +} were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, S{sub c}, was extracted from the experimental maximum ranges for the (100) and (110) axis. The energy dependence of the electronic stopping power is given by S{sub e} = KE{sup p} with p{sub (100)} = 0.469{+-}0.010 and p{sub (110)} = 0.554{+-}0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles. (orig.).

  10. 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.

  11. Tracing recycled volatiles in a heterogeneous mantle with boron isotopes

    Science.gov (United States)

    Walowski, Kristina; Kirstein, Linda; de Hoog, Cees-Jan; Elliot, Tim; Savov, Ivan; Devey, Colin

    2016-04-01

    Recycling of oceanic lithosphere drives the chemical evolution of the Earth's mantle supplying both solids and volatiles to the Earth's interior. Yet, how subducted material influences mantle composition remains unclear. A perfect tracer for slab recycling should be only fractionated at the Earth's surface, have a strong influence on mantle compositions but be resistant to perturbations en route back to the surface. Current understanding suggests that boron concentrations linked to B isotope determinations fulfil all these requirements and should be an excellent tracer of heterogeneity in the deep mantle. Here, we present the trace element, volatile and the B isotope composition of basaltic glasses and melt inclusions in olivine from distinct end-member ocean island basalts (OIB) to track the fate of recycled lithosphere and ultimately document how recycling contributes to mantle heterogeneity. The chosen samples represent the different end member OIB compositions and include: EMI (Pitcairn), EMII (MacDonald), HIMU (St. Helena), and FOZO (Cape Verde & Reunion). The data is derived from both submarine and subaerial deposits, with B isotope determination of both basaltic glass and melt inclusions from each locality. Preliminary results suggest OIB have B isotopic compositions that overlap the MORB array (-7.5‰±0.7; Marschall et al., 2015) but extend to both lighter and heavier values. These results suggest that B isotopes will be useful for resolving mantle source heterogeneity at different ocean islands and contribute to our understanding of the volatile budget of the deep mantle.

  12. Boron neutron capture therapy for recurrent head and neck malignancies

    International Nuclear Information System (INIS)

    To avoid severe impairment of oro-facial structures and functions, it is necessary to explore new treatments for recurrent head and neck malignancies (HNM). Boron neutron capture therapy (BNCT) is tumor-cell targeted radiotherapy that has significant superiority over conventional radiotherapies in principle. So far for 4 years and 3 months, we have treated with 37 times of BNCT for 21 patients (14 squamous cell carcinomas (SCC), 4 salivary gland carcinomas and 3 sarcomas) with a recurrent and far advanced HNM since 2001. Results are (1) 10B concentration of tumor/normal tissue ratio (T/N ratio) of FBPA-PET studies were SCC: 1.8-5.7, sarcoma: 2.5-4.0, parotid tumor: 2.5-3.7. (2) Therapeutic effects were CR: 6cases, PR: 11cases, PD: 3cases NE (not evaluated): 1case. Response rate was 81%. (3) Improvement of QOL such as a relief of severe pain, bleeding, and exudates at the local lesion, improvement of PS, disappearance of ulceration, covered with normal skin and preserved oral and maxillofacial functions and tissues. (4) Survival periods after BNCT were 1-51 months (mean: 9.8 months). 4-year survival rate was 39% by Kaplan-Meier analysis. (5) A few adverse-effects such as transient mucositis, alopecia were recognized. These results indicate that BNCT represents a new and promising treatment approach for advanced HNM. (author)

  13. Online detection of radiation produced in Boron-10 neutron capture reaction: preliminary studies

    International Nuclear Information System (INIS)

    Boron microdistribution in both tumor and normal tissue sections can be studied by the autoradiography technique in solid state nuclear track detectors (SSNTD). A measurement of boron concentration in tissue is obtained through the evaluation of the density of tracks produced by alpha and lithium ions generated in the neutron capture reaction 10B(n,α) 7Li. This knowledge is pivotal when a BNCT (Boron Neutron Capture Therapy) protocol is considered. A new methodology is proposed in order to record alpha and lithium events in real time, as light spots superimposed to the tissue section image. CCD (Charge-Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor) are used as detectors, with the advantage of avoiding the superposition of events. Commercial web cams were employed for the preliminary experiments. They were partially disassembled in order to get the sensor chip uncovered. These devices were exposed to different radiation sources: 6.118 MeV alpha particles (252Cf), 0.662 MeV gamma rays (137Cs) and thermal neutrons (moderated 241Am-Be source, 103n.cm2.seg-1), to analyze the characteristics of the respective images. Pictures from tissue sections put in contact with the sensor surface were also acquired. A software was developed in Matlab to perform the image capture and processing. Early results show the feasibility of using these devices to study the distribution 10B in tissue samples. (author)

  14. The influence of metal Mg on micro-morphology and crystallinity of spherical hexagonal boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ning, E-mail: zhangning5832@163.com; Liu, Huan; Kan, Hongmin; Wang, Xiaoyang; Long, Haibo; Zhou, Yonghui

    2015-08-15

    Highlights: • The action mechanism of Mg to the synthesis of spherical BN was explored. • The influence of Mg content on the crystallinity of h-BN powders was studied. • Even if not added any template, the spherical h-BN could be prepared. - Abstract: This search used the boric acid and borax as a source of boron, urea as a nitrogen source, Mg as metal catalyst, and thus prepared different micro-morphology and crystallinity hexagonal boron nitride powders under a flowing ammonia atmosphere at a nitriding temperature of 750 °C. The effect of Mg content on the crystallinity and micro-morphology of hexagonal boron nitride powders was studied, and the Mg action mechanism was explored. Without the added surfactant, the graphitization index (GI) was 6.87, and the diameter of the spherical h-BN was bigger. When the added Mg were 0.1 g, 0.3 g, 0.5 g and 0.7 g, the (GI) decreased to 6.04, 5.67, 4.62 and 4.84, respectively. When the Mg content was higher (0.9 g), GI value increased rapidly, and the crystallinity became bad. When the Mg content was 0.5 g, the dispersion of h-BN powders was at its optimum and refinement apparently, and the crystallinity at its highest.

  15. The influence of metal Mg on micro-morphology and crystallinity of spherical hexagonal boron nitride

    International Nuclear Information System (INIS)

    Highlights: • The action mechanism of Mg to the synthesis of spherical BN was explored. • The influence of Mg content on the crystallinity of h-BN powders was studied. • Even if not added any template, the spherical h-BN could be prepared. - Abstract: This search used the boric acid and borax as a source of boron, urea as a nitrogen source, Mg as metal catalyst, and thus prepared different micro-morphology and crystallinity hexagonal boron nitride powders under a flowing ammonia atmosphere at a nitriding temperature of 750 °C. The effect of Mg content on the crystallinity and micro-morphology of hexagonal boron nitride powders was studied, and the Mg action mechanism was explored. Without the added surfactant, the graphitization index (GI) was 6.87, and the diameter of the spherical h-BN was bigger. When the added Mg were 0.1 g, 0.3 g, 0.5 g and 0.7 g, the (GI) decreased to 6.04, 5.67, 4.62 and 4.84, respectively. When the Mg content was higher (0.9 g), GI value increased rapidly, and the crystallinity became bad. When the Mg content was 0.5 g, the dispersion of h-BN powders was at its optimum and refinement apparently, and the crystallinity at its highest

  16. Boron microquantification in oral mucosa and skin following administration of a neutron capture therapy agent

    Energy Technology Data Exchange (ETDEWEB)

    Kiger, S.W. III; Micca, P.L.; Morris, G.M.; Coderre, J.A

    2002-07-01

    Clinical trials of boron neutron capture therapy (BNCT) for intracranial tumours using boronphenylalanine-fructose undertaken at Harvard-MIT and Brookhaven National Laboratory have observed acute normal tissue reactions in the skin and oral mucosa. Because the range of the {sup 10}B(n,a){sup 7}Li reaction products is very short, 10-14 {mu}m combined, knowledge of the 10B microdistribution in tissue is critical for understanding the microdosimetry and radiobiology of BNCT. This paper reports measurements of the microdistribution of {sup 10}B in an animal model, rat skin and tongue, using high resolution quantitative autoradiography (HRQAR), a neutron-induced track etch autoradiographic technique. The steep spatial gradient and high absolute value relative to blood of the {sup 10}B concentration observed in some strata of the rat tongue epithelium and skin are important for properly evaluating the radiobiology and the biological effectiveness factors for normal tissue reactions such as oral mucositis, which are generally assessed using the blood boron concentration rather than the tissue boron concentration. (author)

  17. Nominal effective radiation doses delivered during clinical trials of boron neutron capture therapy

    International Nuclear Information System (INIS)

    Boron neutron capture therapy (BNCT) is a binary system that, in theory, should selectively deliver lethal, high linear energy transfer (LET) radiation to tumor cells dispersed within normal tissues. It is based on the nuclear reaction 10-B(n, α)7-Li, which occurs when the stable nucleus of boron-10 captures a thermal neutron. Due to the relatively high cross-section of the 10-B nucleus for thermal neutron capture and short ranges of the products of this reaction, tumor cells in the volume exposed to thermal neutrons and containing sufficiently high concentration of 10-B would receive a much higher radiation dose than the normal cells contained within the exposed volume. Nevertheless, radiation dose deposited in normal tissue by gamma and fast neutron contamination of the neutron beam, as well as neutron capture in nitrogen, 14-N(n,p)14-C, hydrogen, 1-H(n,γ)2-H, and in boron present in blood and normal cells, limits the dose that can be delivered to tumor cells. It is, therefore, imperative for the success of the BNCT the dosed delivered to normal tissues be accurately determined in order to optimize the irradiation geometry and to limit the volume of normal tissue exposed to thermal neutrons. These are the major objectives of BNCT treatment planning

  18. Experimental evaluation of neutron performance in boron-doped low activation concrete

    International Nuclear Information System (INIS)

    Reaction rate distribution in concrete with/without boron dopant up to a thickness of 60 cm was measured using Yayoi fast reactor located at Univ. of Tokyo. The 7 reaction rates such as 197Au(n, γ), 59Co(n, γ), 115In(n, n'), 55Mn(n, γ), 23Na(n, γ), 94Zr(n, γ) and 96Zr(n, γ) were measured at 12 different depths, and the reduction of the reaction rate as a result of boron doping was quantitatively analysed. These reaction rates were also used to determine epithermal neutron spectrum shape parameter. Monte Carlo simulations of the experimental setup were performed using the MCNP-5 code. Simulated depth profiles of reaction rates and the epithermal neutron spectrum shape parameter agreed with the experimental results with fair accuracy. This experimental results provide useful data to benchmark the accuracy of neutron transport codes in the prediction of transmission and neutron spectrum distortion in boron-doped concrete. (authors)

  19. Single photon emission tomography approach for online patient dose assessment in boron neutron capture therapy

    International Nuclear Information System (INIS)

    A tomographic imaging system for the measurement of the spatial distribution of the absorbed dose during a Boron Neutron Capture Therapy (BNCT) session is presented. The 10B(n,α)7Li boron neutron capture reaction produces a 478 keV gamma ray in 94% of the cases. Therefore its detection can serve as a basis for a non-invasive online absorbed dose determination since the dose absorbed by the tumor and healthy tissue strongly depends on the boron uptake and the neutron flux. For this purpose, a dedicated tomographic imaging system based on Single Photon Emission Computed Tomography is proposed. Monte Carlo numerical simulations are used for the system design aimed to have a spatial resolution of 1 cm. Prototypes based on CdZnTe semiconductor detectors and LaBr3(Ce) scintillators with optimized shielding were designed with Monte Carlo simulations. They were built and tested in reactor and accelerator based BNCT facilities. A projection of a phantom with two tumors with 400 ppm of 10B was successfully measured at the accelerator facility of the University of Birmingham. (author)

  20. The Immunosuppressive drug – Rapamycin – Electroanalytical Sensing Using Boron- Doped Diamond electrode

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted -- Abstract: This paper presents for the first time the study of electrochemical behavior of well known immunosuppressant drug – rapamycin (sirolimus) using boron-doped diamond electrode. Rapamycin provided single and oval-shaped oxidation peak at +1.1 V vs. Ag/AgCl electrode in Britton–Robinson buffer solution at pH 3 confirming highly irreversible behavior of analyte at boron-doped diamond electrode. A differential pulse voltammetry was used for quantification of tested drug under the optimum experimental conditions. The calibration curve was linear over the range from 0.5 to 19.5 μM (R2 = 0.9976) with detection limit of 0.22 μM. Repeatability of ten successfully measurements of three different concentrations (5, 10 and 15 μM) was 2.5, 1.9 and 1,7 %, respectively. Influence of most common biomolecules presented in urine samples was evaluated. The suggested analytical methodology was successfully applied for determination of rapamycin in four urine samples with excellent recoveries. The developed approach could be beneficial in analysis of rapamycin in biological samples using boron-doped diamond electrode as up-to-date electrochemical sensor and could represent inexpensive analytical alternative to separation methods

  1. Neutron capture therapy of murine melanoma on new boron carriers with use of capillary neutron optics

    Science.gov (United States)

    Borisov, G. I.; Naidenov, M. G.; Koldaeva, E. Y.; Petrov, S. A.; Zhizhin, K. Y.; Kuznettsov, N. T.; Brattsev, V. A.; Grigorieva, E. Y.

    2005-07-01

    The Boron-10 NCT is one of the most perspective methods of human anticancer treatment. The introduction of this efficient method into medical practice makes possible more selective and precise destruction of tumour cells without any damage of normal tissues. The basis of NCT method is destructive effect of products of nuclear reaction 10B(n,α,γ)7Li. This reaction produces particles-helium nuclei (alpha-particles) and lithium nuclei-with too high linear energetic loss in animal tissues and poor integrated sweep (to 14 μm) what is comparable with single cell diameter. Actual use of BNCT for treatment of human malignant tumours is dependent on resolution of various and complex scientific and technical problems. Namely: the development of novel boron preparations selectively carrying 10B into cancer cells, providing optimal concentration and microdistribution of 10B in these and remaining there during all necessary irradiation time; formation of therapeutic neutron fluxes of needed power, spectrum and intensity; provision of adequate planning and monitoring methods for current 10B-NCT making possible to evaluate a boron concentration in animal tissues in real time, to see macro- and microdistribution of the same, allowing precise microdosimetry; optimization of irradiation regimens and of drug administration schedules conformably to concrete neutron flux in different objects.

  2. 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.

  3. Grade A boron-stainless steel: your flexible friend

    International Nuclear Information System (INIS)

    Boron-containing stainless steels were first used for neutron flux control in reactors. Today they are also used as neutron absorbing materials for spent fuel storage pools and transportation casks. These boron-enriched stainless steels provide a higher thermal neutron absorption cross section than conventional Type 304. Up to 2.25% boron may be added, depending upon attenuation requirements. While adding boron increases neutron attenuation, it has an adverse effect on the alloy's ductility and impact resistance. In the past this has limited the use of borated stainless steels as a structural material for the storage and transportation of spent fuel. Growing needs in the industry, along with improvements in speciality steel processing, led to the development of an advanced type of boron stainless steel which combines neutron absorption capability with the ductility and impact resistance needed for structural applications. It is available with total boron contents up to 2.25% of natural boron, the enriched B-10 isotope, or a combination of these. (author)

  4. 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.

  5. Boron carbide/carbon composite material and production process therefor

    International Nuclear Information System (INIS)

    The boron carbide/carbon composite material of the present invention comprises from 15 to 40% by volume of graphite and the balance of two kinds of powdery boron carbides X and Y having different average grain sizes. The average grain size of the powdery boron carbide X is less than 1/2 of the average grain size of the boron carbide Y, and the composite material comprises more than 10% by volume of the powdery boron carbide X and more than 30% by volume of the powdery boron carbide Y. They are press-molded under heating at a temperature range of 480 to 600degC, followed by sintering. A binder pitch of less evaporation ingredient melting upon heating is used as a binder. Since the pitch of satisfactory melting property is used, there is no worry that binding property lacks to reduce the lowering of the strength even if a great amount of powdery boron carbide is added. Further, since a carbonization yield is improved due to less evaporation content, density and strength of the composite material can be increased. (T.M.)

  6. 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.

  7. 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.

  8. Epithermal neutron beam adoption for liver cancer treatment by boron and gadolinium neutron capture therapy

    International Nuclear Information System (INIS)

    Comparative evaluation was made on depth-dose distribution in boron neutron capture therapy (B-NCT) and gadolinium one (Gd-NCT) for the treatments of liver cancers. At present, epithermal neutron beam is expected to be applicable to the treatment of deep and widespread tumors. ICRU computational model of ADAM and EVA was used as a liver phantom loading a tumor at depth of 6 cm in its central region. Epithermal neutron beam of Musashi reactor was used as the primary neutron beam for the depth-dose calculation. Calculation was conducted using the three-dimensional continuous-energy Monte Carlo code MCNP4A. The doses observed in both NCTs were bumped over the tumor region but the dose for Gd-NCT was not so tumor-specific compared with that for BNCT because radiation in Gd-NCT was due to γ-ray. The mean physical dose was 4 Gy/h for boron 30 ppm and 5 Gy/h for Gd 1000 ppm when exposed to an epithermal neutron flux of 5x108 n/cm-2/sec and the dose ratio of tumor-to normal tissue was 2.7 for boron and 2.5 for Gd. The lethal dose of 50 Gy for the liver can be accomplished under conditions where the dose has not reached 25 Gy, the tolerance dose of the normal tissue. This seems very encouraging and indicating that both B-NCT and Gd-NCT are applicable for the treatment for liver cancer. However, if normal tissue contain 1/4 of the tumor concentration of boron or Gd, the BNCT would still possible when considering a large RBE value for 10B(n, α) reaction but the Gd-NCT would impossible for deep liver treatment. (M.N.)

  9. Synthesis and characterization of alanine boron hydrate for its use in thermal neutron dosimetry

    International Nuclear Information System (INIS)

    Alanine boron hydrate was synthesized for its possible use as intercomparison dosimeter for thermal neutron irradiation. The irradiations were performed in the Nuclear Reactor of the Nuclear Center of Mexico. The salt was prepared by reacting alanine and boric acid in a (1:1) stoichiometric ratio in neutral pH 7.5 aqueous solution and also in a basic pH 13 solution. The latter reaction was prepared with the addition of ammonia hydroxide (25%). Solutions were stirred and afterwards were let to evaporate. The obtained product in each reaction is a white solid. Dosimeters were prepared with the obtained reaction products and irradiated under thermal neutron flux of 5 x 107 n/cm2 s. For 30 hours. The analysis of irradiated samples was made in a Variant E-15 Electron Paramagnetic Resonance spectrometer. The observed response of the samples prepared with the reaction product at the basic pH is approximately 50% higher than the neutral pH samples. In order to investigate the optimum signal enhancement samples were prepared in a basic pH medium in the following stoichiometric ratios: (1:0.5); (1:0.75); (1:1.25); (1:1.5) and (1:1.75). It was observed that the samples of the reaction (1:0.75) produced the higher response. The response was 2728% higher than the alanine only dosimeters. The reaction product was chemically characterized by X-ray diffraction, Nuclear Magnetic Resonance, Chromatography, Refractometry and Solubility tests. Results indicate that alanine boron hydrate is formed in basic media and in a stoichiometric ratio (1:0.75). The dosimetric characterization of alanine boron hydrate was performed, results are reported. It is concluded that alanine boron hydrate may be a good intercomparison dosimeter for thermal neutron irradiation. (Author)

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

    International Nuclear Information System (INIS)

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

  11. Evaluation of the in pile performance of boron containing fuel pellets

    International Nuclear Information System (INIS)

    The world rare earth resource are heavily concentrated in certain area and if these natural resources are weaponized by a country, we may confront serious difficulty because rare earth element gadolinium(Gd) is used as burnable poison material in some nuclear power plants (NPP) in Korea. Gd is used as a neutron absorbing material in Gd2O3 form and mixed with UO2 When boron is used as burnable poison in nuclear fuel, in fuel pellets. The burnable poison mixed in the fuel pellets is called integral burnable absorber (BA) design which differentiates it from the old separate BA design. In the old separate BA design, boron(B) was used in borosilicate glass (PYREX) form and placed in guide tubes. With the development of the concern over the availability of rare earth material Gd, B is considered as a candidate material replacing Gd for the case when the rare earth material is weaponized. However the idea for new boron BA design is integral type because the integral type BA design has several benefits over the separate BA design, such as reduction of radioactive waste, more positions for BA location, etc. 10B absorbs a neutron and produces helium by the following reaction: 10B + n → 7Li + 4He The helium produced by the nuclear reaction may cause the increase of rod internal pressure and change the gap conductivity if the significant amount of helium gas is released to the gap between the pellet and the cladding. Thus, it is necessary to investigate the in-pile behaviors of B containing pellet. However, few experiment have been carried out so far on the behavior of in-pile produced helium in UO2 fuel pellets, especially for the cases boron compound is mixed with UO2 In this paper, we will evaluate the production and the release of helium depending on fuel. 10B concentration in the fuel

  12. A comparative study of boron and arsenic (III) rejection from brackish water by reverse osmosis membranes

    KAUST Repository

    Teychene, Benoît

    2013-02-01

    This study aims to compare at lab-scale the rejection efficiency of several reverse osmosis membranes (RO) toward arsenic (III) and boron during the filtration of a synthetic brackish water. The effect of pH and operating conditions on the rejection of each RO membrane was studied. Two types of membrane were investigated: "brackish water" and "sea water" membranes. Our results showed that the metalloid rejection depends on the membrane type, pH and transmembrane pressure applied. Increasing pH above the dissociation constant (pKa) of each specie improves significantly the metalloid rejection by RO membranes, whatever the membrane type. Moreover, at identical operating conditions (pH, transmembrane pressure), results showed that the brackish water membranes have a higher water flux and exhibit lower metalloid rejection. The highest As(III) rejection value for the tested brackish water membranes was 99% obtained at pH = 9.6 and 40 bars, whereas it was found that the sea water RO membranes could highly reject As(III), more than 99%, even at low pH and low pressure (pH = 7.6 and 24 bars).Regarding Boron rejection, similar conclusions could be drawn. The sea water RO membranes exert higher removal, with a high rejection value above 96% over the tested conditions. More generally, this study showed that, whatever the operating conditions or the tested membranes, the boron and As(III) permeate concentrations are below the WHO guidelines. In addition, new data about the boron and arsenic permeability of each tested RO membrane was brought thanks to a theoretical calculation. © 2012 Elsevier B.V.

  13. 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.

  14. MICROSTRUCTURE OF BORONIZED PM Cr-V COLD WORK LEDEBURITIC TOOL STEEL

    OpenAIRE

    Peter Jurči; Mária Hudáková

    2010-01-01

    The PM Vanadis 6 cold work tool steel has been boronized at various processing parameters, austenitized, quenched and tempered to a core hardness of 700 HV. Microstructure, phase constitution and microhardness of boronized layers were investigated. It was found that the boronized layers are of two-phase FeB/Fe2B constitution, with an addition of small portion of CrB. Below the boronized layer, intermediate region with elevated carbides ratio was developed. Boronized layers contain also carbid...

  15. Generation of a boron ion beam in a modified ion source for semiconductor applications

    International Nuclear Information System (INIS)

    Presented here are results of experimental studies on the production of intense beams of boron ions using a modified Bernas-Calutron ion source. Instead of using the conventional boron-trifluoride gas, a solid lithium-boron-tetrafluoride compound was heated to release boron-trifluoride. For optimum ion source parameters the measured 25-41 mA of total ion beam current was composed of 70% singly charged and about 1% doubly charged boron ions

  16. 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.

  17. Infiltration processing of boron carbide-, boron-, and boride-reactive metal cermets

    International Nuclear Information System (INIS)

    This patent describes a method of fabricating metal-ceramic composites from previously formed ceramic precursor starting constituents selected from boron-carbide, boron and borides and metals reactive therewith selected from reactive metals, alloys thereof, and compounds thereof which reduce to reactive metals or alloys thereof. It comprises: chemically pretreating the previously formed starting constituents of a ceramic precursor; consolidating the chemically pretreated starting constituents into a porous ceramic precursor; infiltrating molten reactive metal into the chemically pretreated ceramic precursor; wherein the step of chemically pretreating the starting constituents of the ceramic precursor alters the surface chemistry to enhance infiltration of the precursor by the molten reactive metal by slowing the kinetics of reaction relative to the kinetics of densification

  18. Phase and property studies of boron carbide-boron nitride composites

    International Nuclear Information System (INIS)

    This paper reports on boron carbide-boron nitride particulate composites that were fabricated by vacuum hot-pressing. Near-theoretical densities of B4C were obtained, but percent theoretical densities decreased with increasing amounts of BN. The grain size of B4C and BN was not affected by composition, but the amount of twinning in B4C decreased with increasing BN content. No third phase was found at the B4C-BN interface by analytical STEM analysis. Lattice parameter measurements indicated slight solubility of B4C in BN, but no solubility of BN in B4C for samples hot-pressed at 2250 degrees C. Room-temperature flexural strength measurements revealed a sharply decreasing strength with increasing BN content up to 40% BN, and then relatively constant values with greater amounts of BN

  19. Nickel-boron nanolayer evolution on boron carbide particle surfaces during thermal treatment

    International Nuclear Information System (INIS)

    This study is focused on reduction of Ni2O3 and B2O3 in the Ni-B nanolayer on B4C particle surfaces and understanding of the nanolayer composition and morphology changes. Initially, the nanolayer contains Ni2O3, B2O3, and amorphous boron. After 400 oC thermal treatment in a H2-Ar atmosphere, Ni2O3 is reduced to nickel; the nanolayer morphology is maintained and the coated particles demonstrate magnetism. As the thermal treatment temperature is increased to 550 oC, B2O3 is reduced to boron, which reacts with nickel and forms Ni2B. Simultaneously, the nanolayer evolves into nanoparticles. Thermal treatment temperature increase to 700-900 oC only causes Ni2B particle growth but does not fundamentally change the composition or phase.

  20. 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.

  1. 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

  2. Development of TIMS for isotopic ratio analysis of boron

    International Nuclear Information System (INIS)

    A magnetic sector based Thermal Ionisation Mass Spectrometer (TIMS) has been developed at Technical Physics Division, for high precision isotope ratio analysis of Boron (in the form of Sodium Meta-borate) at the Boron enrichment facility, Heavy Water Plant, Manuguru. The performance of this indigenously developed TIMS has been tested for sensitivity, isotope ratio precision and accuracy for different levels of enrichment in the plant samples. The sensitivity of this instrument was found to be 1 ion per 200 atoms. The internal and external precision for natural concentration levels Boron isotopes were better than 0.05%. (author)

  3. 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.

  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. Proceedings of workshop on 'boron chemistry for neutron capture therapy'

    International Nuclear Information System (INIS)

    This volume contains the proceedings of the workshop on the chemistry of Boron Neutron Capture Therapy held on 1st of August in 1988 and on 22nd of January in 1990. In this workshop, our attention was mainly focused on the chemical reactions and chemical analyses of boron compounds used for the therapy. There is additionally shown the basic knowledge of immunology related with the neutron capture therapy. We do hope that this proceedings will contribute to the development of new boron carriers for the therapy. (J.P.N.)

  6. 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. PMID:21403227

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

    International Nuclear Information System (INIS)

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

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

    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

  9. 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

  10. 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.)

  11. 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.

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

    International Nuclear Information System (INIS)

    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. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

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

    International Nuclear Information System (INIS)

    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.

  14. 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).

  15. In vitro determination of toxicity, binding, retention, subcellular distribution and biological efficacy of the boron neutron capture agent DAC-1

    International Nuclear Information System (INIS)

    In boron neutron capture therapy (BNCT), 10B is delivered selectively to the tumour cells and the nuclide then forms high-LET radiation (4He2+ and 7Li3+) upon neutron capture. Today much research is focused on development of a variety of boron compounds aimed for BNCT. The compounds must be thoroughly analysed in preclinical tests regarding basic characteristics such as binding and subcellular distribution to enable accurate estimations of dose-modifying factors. DAC-1, 2-[2-(3-amino-propyl)-1,2-dicarba-closo-dodecaboran(12)-1-yl-methoxyl]-1,3 -propanediol was synthesized at our laboratories and the human colon carcinoma cells LS-174T were used as an in vitro model. The boron compound showed a remarkable intracellular accumulation, 20-100 times higher than the boron content in the culture medium, in cultured cells and was not removed by extensive washes. Approximately half of the boron taken up also remained within the cells for at least 4 days. The DAC-1 compound alone was not toxic at boron concentrations below 2.5 μg B/g. The intracellular distribution of the boron compound was investigated by subcellular fractionation experiments and low pH treatments. It is possible that DAC-1 binds to some intracellular molecules or to membranes connected with organelles in the cytoplasm or even to the inside of the outer cell membrane. Another possibility is that the compound, due to the somewhat lipophilic properties, is embedded in the membranes. Thermal neutron irradiations were carried out at the Brookhaven Medical Research Reactor (BMRR). At a survival level of 0.1, DAC-1 + thermal neutrons were about 10.5 times more effective in cell inactivation than the thermal neutrons alone. Monte Carlo calculations gave a mean value of the 10B-dependent specific energy, the dose, of 0.22 Gy. The total physical dose during irradiation of DAC-1-containing cells with a neutron fluence of 0.18 x 1012 n/cm2 was 0.39 Gy. The dose-modifying factor, at survival level 0.1, when comparing

  16. In vitro determination of toxicity, binding, retention, subcellular distribution and biological efficacy of the boron neutron capture agent DAC-1.

    Science.gov (United States)

    Tilly, N; Olsson, P; Hartman, T; Coderre, J; Makar, M; Malmquist, J; Sjöberg, S; Pettersson, J; Carlsson, J; Glimelius, B

    1996-01-01

    In boron neutron capture therapy (BNCT), 10B is delivered selectively to the tumour cells and the nuclide then forms high-LET radiation (4He2+ and 7Li3+) upon neutron capture. Today much research is focused on development of a variety of boron compounds aimed for BNCT. The compounds must be thoroughly analysed in preclinical tests regarding basic characteristics such as binding and subcellular distribution to enable accurate estimations of dose-modifying factors. DAC-1,2-[2-(3-amino-propyl)-1,2-dicarba-closo-dodecaboran (12)-1-yl-methoxy]- 1,3-propanediol was synthesized at our laboratories and the human colon carcinoma cells LS-174T were used as an in vitro model. The boron compound showed a remarkable intracellular accumulation, 20-100 times higher than the boron content in the culture medium, in cultured cells and was not removed by extensive washes. Approximately half of the boron taken up also remained within the cells for at least 4 days. The DAC-1 compound alone was not toxic at boron concentrations below 2.5 micrograms B/g. The intracellular distribution of the boron compound was investigated by subcellular fractionation experiments and low pH treatments. It is possible that DAC-1 binds to some intracellular molecules or to membranes connected with organelles in the cytoplasm or even to the inside of the outer cell membrane. Another possibility is that the compound, due to the somewhat lipophilic properties, is embedded in the membranes. Thermal neutron irradiations were carried out at the Brookhaven Medical Research Reactor (BMRR). At a survival level of 0.1, DAC-1 + thermal neutrons were about 10.5 times more effective in cell inactivation than the thermal neutrons alone. Monte Carlo calculations gave a mean value of the 10B-dependent specific energy, the dose, of 0.22 Gy. The total physical dose during irradiation of DAC-1-containing cells with a neutron fluence of 0.18 x 10(12) n/cm2 was 0.39 Gy. The dose-modifying factor, at survival level 0.1, when

  17. The optical properties of boron carbide near boron K-edge inside periodical multilayers

    International Nuclear Information System (INIS)

    Multilayer mirrors made for the use in the wavelength range near K-edge of boron (188 eV) are of great interest for X-ray fluorescence analysis of boron content in doped semiconductors, plasma diagnostics, astronomy and lithography. Moreover, multilayer mirrors composed by a metal and a low Z element like boron are used as optical elements in both the soft x-ray spectral range as well as at higher photon energies on 3rd generation synchrotron beamlines. Using an energy-resolved photon-in-photon-out method we reconstructed the optical data from energy dependence of both integrated peak intensity and FWHM of the 1st order ML Bragg peak measured at the UHV triple axis soft-x-ray reflectometer at BESSY II. The experiments clearly demonstrate that the peak shape of the ML Bragg peak is most sensitive to any kind of electronic excitation and recombination in solid. The soft-ray reflectivity can give detailed information for MLs with thickness up to several tens of nanometers. In addition, measurements close to a resonance edge probe the chemical state of the respective constituent accompanied with a high sensitivity of changes close to the sample surface.

  18. 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

  19. Optical absorption of boron nitride nanomaterials

    International Nuclear Information System (INIS)

    Optical absorption spectra have been measured for hexagonal boron nitride (h-BN), rhombohedral BN(rh-BN), and material obtained by laser vaporization of BN target under a nitrogen atmosphere and contained single-wall BN-nanotubes. Band gap of the BN materials was found to have a value of 6.0-6.3 eV. The spectra of h -BN and vaporized material exhibited a peak at ∝5.5 eV, moreover, the latter sample showed an absorption band around 4.5 eV. The vaporized material has been fractionated to the BN-platelets and single-wall BN-nanotubes. Absorption peaks, located bellow the bottom of the conductance band, were found to be characteristics of thin BN-platelets and they could be attributed to defects in BN network. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. 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