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Sample records for boron complexes

  1. Investigation into organic boron compounds complexing

    International Nuclear Information System (INIS)

    Yuzhakova, G.A.; Belonovich, M.I.; Rybakova, M.N.; Morozova, T.L.; Lapkin, I.I.

    1983-01-01

    Triarylboranes interact with 4-amino-1, 2, 4-triazole With the formation of complexes of the composition 1:1. Ligand forms coordination bond with boron at the expense of pyridine atom of triazole cycle nitrogen. IR spectra, yields and decomposition temperatures of the complexes are presented

  2. Defect complexes in carbon and boron nitride nanotubes

    CSIR Research Space (South Africa)

    Mashapa, MG

    2012-05-01

    Full Text Available The effect of defect complexes on the stability, structural and electronic properties of single-walled carbon nanotubes and boron nitride nanotubes is investigated using the ab initio pseudopotential density functional method implemented...

  3. Strongly Phosphorescent Transition Metal π-Complexes of Boron-Boron Triple Bonds.

    Science.gov (United States)

    Braunschweig, Holger; Dellermann, Theresa; Dewhurst, Rian D; Hupp, Benjamin; Kramer, Thomas; Mattock, James D; Mies, Jan; Phukan, Ashwini K; Steffen, Andreas; Vargas, Alfredo

    2017-04-05

    Herein are reported the first π-complexes of compounds with boron-boron triple bonds with transition metals, in this case Cu I . Three different compounds were isolated that differ in the number of copper atoms bound to the BB unit. Metalation of the B-B triple bonds causes lengthening of the B-B and B-C NHC bonds, as well as large upfield shifts of the 11 B NMR signals, suggesting greater orbital interactions between the boron and transition metal atoms than those observed with recently published diboryne/alkali metal cation complexes. In contrast to previously reported fluorescent copper(I) π-complexes of boron-boron double bonds, the Cu n -π-diboryne compounds (n = 2, 3) show intense phosphorescence in the red to near-IR region from their triplet excited states, according to their microsecond lifetimes, with quantum yields of up to 58%. While the Cu diborene bond is dominated by electrostatic interactions, giving rise to S 1 and T 1 states of pure IL(π-π*) nature, DFT studies show that the Cu I π-complexes of diborynes reported herein exhibit enhanced metal d orbital contributions to HOMO and HOMO-1, which results in S 1 and T 1 having significant MLCT character, enabling strong spin-orbit coupling for highly efficient intersystem-crossing S 1 → T n and phosphorescence T 1 → S 0 .

  4. Electrochemistry of the Oxofluoro Complexes of Boron in Fluoride Melts

    DEFF Research Database (Denmark)

    Polyakova, L.P.; Bukatova, G.A.; Polyakov, E.G.

    1997-01-01

    Electrochemical behavior of oxofluoro complexes of boron, synthesized both in situ in FLINAK melt and added into the melt as Na3B3O3F6 compound, was by linear voltammetry within the range of 570-750 oC. It was shown that in lower part of this range the electrochemical reduction of BOF2- complexes...... energy of 61.6 kJ/mol. Study of the thermal stability of boron containing oxofluoro melts showed that O/B ratio changes in time due to evaporation of BF3. As a result borate complexes emerge in the melt alongside with oxofluoro ones....

  5. The Binary Boron Trifluoride-Hydroxylamine Molecular Complex: N ...

    African Journals Online (AJOL)

    South African Journal of Chemistry ... Recent computational results on a number of complexes with some oxygen and nitrogen bases have indicated relationships between the properties of the adducts, such as the interaction energies and the wavenumber shifts of some of the modes of the boron trifluoride sub-molecule, ...

  6. Boron biodistribution in Beagles after intravenous infusion of 4-dihydroxyborylphenylalanine-fructose complex

    International Nuclear Information System (INIS)

    Kulvik, M.E.; Vaehaetalo, J.K.; Benczik, J.; Snellman, M.; Laakso, J.; Hermans, R.; Jaerviluoma, E.; Rasilainen, M.; Faerkkilae, M.; Kallio, M.E.

    2004-01-01

    Boron biodistribution after intravenous infusion of 4-dihydroxyborylphenylalanine-fructose (BPA-F) complex was investigated in six dogs. Blood samples were evaluated during and following doses of 205 and 250 mg/kgbw BPA in a 30 min infusion, and 500 mg/kgbw in a 1 h infusion. Samples from whole blood, urine, brain and other organs were analysed for boron content after varying times following the onset of infusion. The whole blood boron concentrations declined from 27 to 8.4 ppm over the period of 39-165 min after the onset of infusion and the levels increased from 1.9 to 12 ppm in the grey matter of the brain over the same period. The boron concentrations in whole blood decreased steadily, whereas the boron values in brain tissue rose steadily with time. It was concluded that whole blood boron concentrations do not seem to reflect accurately the boron concentration in brain tissue at respective time points

  7. Vacancy complexes in carbon and boron nitride nanotubes

    CSIR Research Space (South Africa)

    Mashapa, MG

    2012-10-01

    Full Text Available The effect of divacancies on the stability, structural and electronic properties of carbon and boron nitride nanotubes is studied using the ab initio density functional method. VBBN is more stable in the boron-rich and less stable in the nitrogen...

  8. Surface glycosylation of polysulfone membrane towards a novel complexing membrane for boron removal.

    Science.gov (United States)

    Meng, Jianqiang; Yuan, Jing; Kang, Yinlin; Zhang, Yufeng; Du, Qiyun

    2012-02-15

    In this study, a novel complexing membrane was synthesized for boron removal from aqueous solution. A glycopolymer, poly(2-gluconamidoethyl methacrylate) (PGAMA), was grafted onto the chloromethylated polysulfone (CMPSF) microporous membrane via surface-initiated ATRP (SIATRP). The glycosylated PSF (GlyPSF) membrane was characterized by attenuated total refection-Flourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FESEM). It was demonstrated that PGAMA was successfully anchored onto the membrane surface and the grafting yield can be tuned in a wide range up to 5.9 mg/cm(2) by varying the polymerization time. The complexing membrane can adsorb boron rapidly with the equilibrium reached within 2h and has a remarkable high boron adsorption capacity higher than 2.0 mmol/g at optimized conditions. Freundlich, Langmuir, and Dubinin-Radushkevich adsorption isotherms were applied, and the data were best described by Langmuir model. Kinetic data were analyzed, and the data fitted very well to the pseudo-second-order rate expression. The optimal pH for boron uptake is in a wide range of 6-9, and the optimal initial boron concentration is over 300 mg/L. Studies of ionic strength effects indicated the formation of inner-sphere surface complexes. The complexed boron can be leached quantitatively under acid condition. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. The Binary Boron Trifluoride-Hydroxylamine Molecular Complex: N ...

    African Journals Online (AJOL)

    NJD

    Hydroxylamine represents an example of a base containing two potential sites of electron donation, the nitrogen and the oxygen atoms. Predictions based on our earlier investigations of systems of this type suggest that hydroxylamine would bind to boron trifluoride preferentially through its nitrogen atom. Whether such a.

  10. Quantum chemical investigation of levofloxacin-boron complexes: A computational approach

    Science.gov (United States)

    Sayin, Koray; Karakaş, Duran

    2018-04-01

    Quantum chemical calculations are performed over some boron complexes with levofloxacin. Boron complex with fluorine atoms are optimized at three different methods (HF, B3LYP and M062X) with 6-31 + G(d) basis set. The best level is determined as M062X/6-31 + G(d) by comparison of experimental and calculated results of complex (1). The other complexes are optimized by using the best level. Structural properties, IR and NMR spectrum are examined in detail. Biological activities of mentioned complexes are investigated by some quantum chemical descriptors and molecular docking analyses. As a result, biological activities of complex (2) and (4) are close to each other and higher than those of other complexes. Additionally, NLO properties of mentioned complexes are investigated by some quantum chemical parameters. It is found that complex (3) is the best candidate for NLO applications.

  11. Synthesis and ligand-based reduction chemistry of boron difluoride complexes with redox-active formazanate ligands

    NARCIS (Netherlands)

    Chang, M. -C.; Otten, E.

    2014-01-01

    Mono(formazanate) boron difluoride complexes (LBF2), which show remarkably facile and reversible ligand-based redox-chemistry, were synthesized by transmetallation of bis(formazanate) zinc complexes with boron trifluoride. The one-electron reduction product [LBF2](-)[Cp2Co](+) and a key intermediate

  12. Impact of different environmental stimuli on the release of 1-MCP from boron-MCP complexes

    Science.gov (United States)

    In our previous report, boron derivatives of methylene cyclopropane complexes (B-MCP) were developed to stabilize the gaseous 1-MCP (1-methylcyclopropene), a commercial plant growth regulator, for eventual release in open crop fields when under humid conditions or in contact with water. To meet the ...

  13. Targeted and non-targeted boron complex formation followed by electrospray Fourier transform ion cyclotron mass spectrometry: a novel approach for identifying boron esters with natural organic matter.

    Science.gov (United States)

    Gaspar, Andras; Lucio, Marianna; Harir, Mourad; Schmitt-Kopplin, Philippe

    2011-01-01

    The formation of boron esters was investigated in peat-soluble humified materials with a detailed molecular-level description of boron-organic interactions. Thousands of individually baseline separated signals were obtained from the analysis of natural organic matter of peat samples, using Fourier transform ion cyclotron resonance mass spectrometry. This technique offers unsurpassed isotope-specific mass resolution that can lead to precise molecular formula assignments by means of mathematical data analysis and visualisation techniques, such as mass defect (Kendrick) or elemental ratio (van Krevelen) plots. The analysis of potential boron binding structures within the sample of natural organic matter was described based on prior results. Herein, we describe an algorithm that can be used to effectively distinguish and filter complexes through data obtained from boron-enriched systems with highly intricate mass spectra, such as natural organic matter.

  14. The effect of carbon and boron on the accumulation of vacancy-oxygen complexes in silicon

    International Nuclear Information System (INIS)

    Akhmetov, V.D.; Bolotov, V.V.

    1980-01-01

    By means of IR-absorption measurements the dose dependencies of the concentrations of vacancy-oxygen complexes (VO), interstitial oxygen atoms (Osub(I)), substitutional carbon atoms (Csub(S)) and interstitial carbon-oxygen complexes (Csub(I)Osub(I)) in n- and p-type silicon irradiated with 1.1 MeV electrons have been investigated. The observed increase of the production rate of VO-complexes with the rise of carbon and boron atoms concentrations (these impurities act as sinks for silicon interstitial atoms) has been explained in terms of annihilation of the vacancies and interstitials on the oxygen atoms. The results obtained show that boron atoms are more effective sinks than carbon atoms for the interstitial silicon atoms. That seems to be connected not only with the higher probability of boron injection into interstitial position but also with the further capture of interstitial silicon atoms on the interstitial boron, i.e. with the interstitial cluster formation. (author)

  15. Simple boron removal from seawater by using polyols as complexing agents: A computational mechanistic study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min-Kyung; Eom, Ki Heon; Lim, Jun-Heok; Lee, Jea-Keun; Lee, Ju Dong; Won, Yong Sun [Pukyong National University, Busan (Korea, Republic of)

    2015-11-15

    The complexation of boric acid (B(OH){sub 3}), the primary form of aqueous boron at moderate pH, with polyols is proposed and mechanistically studied as an efficient way to improve membrane processes such as reverse osmosis (RO) for removing boron in seawater by increasing the size of aqueous boron compounds. Computational chemistry based on the density functional theory (DFT) was used to manifest the reaction pathways of the complexation of B(OH){sub 3} with various polyols such as glycerol, xylitol, and mannitol. The reaction energies were calculated as −80.6, −98.1, and −87.2 kcal/mol for glycerol, xylitol, and mannitol, respectively, indicating that xylitol is the most thermodynamically favorable for the complexation with B(OH){sub 3}. Moreover, the 1 : 2 molar ratio of B(OH)3 to polyol was found to be more favorable than the ratio of 1 : 1 for the complexation. Meanwhile, latest lab-scale actual RO experiments successfully supported our computational prediction that 2 moles of xylitol are the most effective as the complexing agent for 1 mole of B(OH){sub 3} in aqueous solution.

  16. Boron-selective reactions as powerful tools for modular synthesis of diverse complex molecules.

    Science.gov (United States)

    Xu, Liang; Zhang, Shuai; Li, Pengfei

    2015-12-21

    In the context of modular and rapid construction of molecular diversity and complexity for applications in organic synthesis, biomedical and materials sciences, a generally useful strategy has emerged based on boron-selective chemical transformations. In the last decade, these types of reactions have evolved from proof-of-concept to some advanced applications in the efficient preparation of complex natural products and even automated precise manufacturing on the molecular level. These advances have shown the great potential of boron-selective reactions in simplifying synthetic design and experimental operations, and should inspire new developments in related chemical and technological areas. This tutorial review will highlight the original contributions and representative advances in this emerging field.

  17. Forward current enhanced elimination of the radiation induced boron-oxygen complex in silicon n+-p diodes

    CERN Document Server

    Makarenko, L F; Yakushevich, H S; Moll, M; Pintilie, I

    2014-01-01

    Using forward current injection with densities in the range 15-30A/cm(2) we can effectively eliminate the radiation-induced boron-oxygen complex, which is the main compensating center in irradiated Si solar cells. It was found that for a given forward current density the elimination rate is decreasing with increasing irradiation dose. Additionally, some evidences have been obtained on the negative-U properties of the radiation-induced boron-oxygen complex.

  18. Boron neutron capture therapy of glioblastoma multiforme using the p- boronophenylalanine-fructose complex and epithermal neutrons

    International Nuclear Information System (INIS)

    Coderre, J.A.; Chanana, A.D.; Joel, D.D.; Liu, H.B.; Slatkin, D.N.; Wielopolski, L.; Bergland, R.; Elowitz, E.; Chadha, M.

    1994-01-01

    The amino acid analogue p-boronophenylalanine (BPA) is under investigation as a neutron capture agent for BNCT of glioblastoma multiforme. A series of patients undergoing surgical removal of tumor received BPA orally as the free amino acid. Favorable tumor/blood boron concentration ratios were obtained but the absolute amount of boron in the tumor would have been insufficient for BNCT. BPA can be solubilized at neutral pH by complexation with fructose (BPA-F). Studies with rats suggest that intraperitoneal injection of BPA-F complex produces a much higher tumor boron concentration to rat intracerebral 9L gliosarcoma that were possible with oral BPA. Higher boron concentrations have allowed higher tumor radiation doses to be delivered while maintaining the dose to the normal brain vascular endothelium below the threshold of tolerance. The experience to date of the administration of BPA-F to one patient is provided in this report

  19. Boron neutron capture therapy of glioblastoma multiforme using the p- boronophenylalanine-fructose complex and epithermal neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Coderre, J.A.; Chanana, A.D.; Joel, D.D.; Liu, H.B.; Slatkin, D.N.; Wielopolski, L. [Brookhaven National Lab., Upton, NY (United States); Bergland, R.; Elowitz, E. [Beth Israel Medical Center, New York, NY (United States). Dept. of Neurosurgery; Chadha, M. [Beth Israel Medical Center, New York, NY (United States). Dept. of Radiation Oncology

    1994-12-31

    The amino acid analogue p-boronophenylalanine (BPA) is under investigation as a neutron capture agent for BNCT of glioblastoma multiforme. A series of patients undergoing surgical removal of tumor received BPA orally as the free amino acid. Favorable tumor/blood boron concentration ratios were obtained but the absolute amount of boron in the tumor would have been insufficient for BNCT. BPA can be solubilized at neutral pH by complexation with fructose (BPA-F). Studies with rats suggest that intraperitoneal injection of BPA-F complex produces a much higher tumor boron concentration to rat intracerebral 9L gliosarcoma that were possible with oral BPA. Higher boron concentrations have allowed higher tumor radiation doses to be delivered while maintaining the dose to the normal brain vascular endothelium below the threshold of tolerance. The experience to date of the administration of BPA-F to one patient is provided in this report.

  20. Evaluating the complexation behavior and regeneration of boron selective glucaminium-based ionic liquids when used as extraction solvents

    International Nuclear Information System (INIS)

    Joshi, Manishkumar D.; Steyer, Daniel J.; Anderson, Jared L.

    2012-01-01

    Highlights: ► Glucaminium-based ILs exhibit high selectivity for boron species using DLLME. ► The concentration of glucaminium-based IL affects type of boron complex formed. ► Use of 0.1 M HCl allows for regeneration of the IL solvent following extraction. ► Selectivity of the glucaminium-based ILs for boron species in seawater is similar to Milli-Q water. - Abstract: Glucaminium-based ionic liquids are a new class of solvents capable of extracting boron-species from water with high efficiency. The complexation behavior of these ILs with borate was thoroughly studied using 11 B NMR. Two different complexes, namely, monochelate complex and bischelate complex, were observed. 11 B NMR was used extensively to determine the formation constants for monochelate and bischelate complexes. The IL concentration was observed to have a significant effect on the IL–borate complexes. Using an in situ dispersive liquid–liquid microextraction (in situ DLLME) method, the extraction efficiency for boron species was increased dramatically when lithium bis[(trifluoromethyl)sulfonyl]imide (LiNTf 2 ) was used as the metathesis salt in an aqueous solution containing 0.1 M sodium chloride. IL regeneration after extraction was achieved using 0.1 M hydrochloric acid. The extraction efficiency of boron species was consistent when the IL was employed after three regeneration cycles. The selectivity of the IL for boron species in synthetic seawater samples was similar to performing the same extraction from Milli-Q water samples.

  1. An improved procedure for separation/purification of boron from complex matrices and high-precision measurement of boron isotopes by positive thermal ionization and multicollector inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Wei, Hai-Zhen; Jiang, Shao-Yong; Hemming, N Gary; Yang, Jing-Hong; Yang, Tao; Wu, He-Pin; Yang, Tang-Li; Yan, Xiong; Pu, Wei

    2014-06-01

    In order to eliminate boron loss and potential isotopic fractionation during chemical pretreatment of natural samples with complex matrices, a three-column ion-exchange separation/purification procedure has been modified, which ensures more than 98% recovery of boron from each step for a wide range of sample matrices, and is applicable for boron isotope analysis by both TIMS and MC-ICP-MS. The PTIMS-Cs2BO2(+)-static double collection method was developed, ensuring simultaneous collection of (133)Cs2(11)B(16)O2(+)(m/z 309) and (133)Cs2(10)B(16)O2(+) (m/z 308) ions in adjacent H3-H4 Faraday cups with typical zoom optics parameters (Focus Quad: 15 V, Dispersion Quad: -85 V). The external reproducibilities of the measured (11)B/(10)B ratios of the NIST 951 boron standard solutions of 1000 ng, 100 ng and 10 ng of boron by PTIMS method are ±0.06‰, ±0.16‰ and ±0.25‰, respectively, which indicates excellent precision can be achieved for boron isotope measurement at nanogram level boron in natural samples. An on-peak zero blank correction procedure was employed to correct the residual boron signals effect in MC-ICP-MS, which gives consistent δ(11)B values with a mean of 39.66±0.35‰ for seawater in the whole range of boron content from 5 ppb to 200 ppb, ensuring accurate boron isotope analysis in few ppb boron. With the improved protocol, consistent results between TIMS and MC-ICP-MS data were obtained in typical geological materials within a wide span of δ(11)B values ranging from -25‰ to +40‰. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. The structure study of boron carbonitride films obtained by use of trimethylamine borane complex

    CERN Document Server

    Kosinova, M L; Fainer, N I; Maximovski, E A; Kuznetsov, F A

    2001-01-01

    Diffraction of synchrotron radiation (SR) was used to investigate crystalline structure and phase composition of thin films (1500-5000 A) of boron carbonitride. These films were synthesized by plasma-enhanced chemical vapor deposition using nontraditional volatile single source precursor trimethylamine borane complex (CH sub 3) sub 3 N centre dot BH sub 3 and its mixture with ammonia. The effect of the gas ratio and substrate temperature on chemical and phase composition as well as the structure of the films were investigated. The XRD peculiarities of texture films and ways of increasing sensibility of measurements were considered. A possibility of the information density rise of the thin film XRD was shown due to application of different methods for recording diffraction patterns.

  3. The coordination chemistry of boron porphyrin complexes B2OX2 ...

    Indian Academy of Sciences (India)

    Unknown

    therapeutic method that utilizes porphyrin deriva- tives localized in tumors, as in situ photosensitizers for the production of singlet oxygen on irradiation with red light.2 Candidate porphyrin derivatives that contain boron for boron neutron capture therapy (BNCT) ... in small animal glioma models.4,5 BNCT is a two-step.

  4. Deep levels of nitrogen vacancies complexes in graphite-like boron nitride

    CERN Document Server

    Grinyaev, S N; Lopatin, V V

    2002-01-01

    Paper presents results of theoretical studies using methods of model pseudopotential and of extended elementary cell of deep levels of nitrogen vacancies, small clusters from di- and trivacancies of nitrogen covering nearest defects in one layer of graphite-like boron nitride. On the basis of calculated spectra and intensities of oscillators one interpreted local bands of optical absorption, luminescence, photoconductivity in pyrolytic boron nitride prior to and subsequent to irradiation by fast neutrons, protons and ions of carbon (50-150 keV). One identified not deep levels of activation of thermally stimulated luminescence and conductivity prior to and subsequent to irradiation

  5. Boron and Zirconium from Crucible Refractories in a Complex Heat-Resistant Alloy

    Science.gov (United States)

    Decker, R F; Rowe, John P; Freeman, J W

    1958-01-01

    In a laboratory study of the factors involved in the influence of induction vacuum melting on 55ni-20cr-15co-4mo-3ti-3al heat resistant alloy, it was found that the major factor was the type of ceramic used as the crucible. The study concluded that trace amounts of boron or zirconium derived from reaction of the melt with the crucible refactories improved creep-rupture properties at 1,600 degrees F. Boron was most effective and, in addition, markedly improved hot-workability.

  6. Photometric method to determining boron microamounts in the form of β-diketonate complex in steel and alloys bsed on nickel

    International Nuclear Information System (INIS)

    Ishchenko, A.V.; Stashkova, N.V.; Timoteus, Kh.R.; Fedorova, S.F.

    1988-01-01

    A sensitive technique of determining boron microamounts in steels and alloys based on nickel, doped with chromium, tungsten, molybdenum, titanium and vanadium is developed. After boron preextraction by β-diol chloroform solutions its determination is carried out directly in organic phase in acidic and sulfuric acids by β-diketone class reagent: 4,4'-dihydroxydibensoylmethane (I) or 4,4'-dimethoxydibenzoylmethane. Molar light-absorption coefficient for reagent I at formation of boroxalate complex is 8.48x10 4 , at of complexing in presence of sulfuric acid -10.63x10 4 , of acetic acid-17.27x10 4

  7. Polyhomologation based on in situ generated Boron-thexyl-silaboracyclic initiating sites: a novel strategy towards the synthesis of polyethylene-based complex architectures

    KAUST Repository

    Zhang, Zhen

    2015-04-10

    A novel strategy, based on the in situ generated Boron-thexyl-silaboracyclic initiating sites for the polyhomologation of dimethylsulfoxonium methylide, has been developed for the synthesis of complex polyethylene-based architectures. As examples, the synthesis of a 4-arm polyethylene star, three (polystyrene)(polyethylene)2 3-miktoarm stars and a PE-branched double graft copolymers are given.

  8. A comparative study of the spectral, fluorometric properties and photostability of natural curcumin, iron- and boron- complexed curcumin

    Science.gov (United States)

    Mohammed, Fatima; Rashid-Doubell, Fiza; Cassidy, Seamas; Henari, Fryad

    2017-08-01

    Curcumin is a yellow phenolic compound with a wide range of reported biological effects. However, two main obstacles hinder the use of curcumin therapeutically, namely its poor bioavailability and photostability. We have synthesized two curcumin complexes, the first a boron curcumin complex (B-Cur2) and the second an iron (Fe-Cur3) complex of curcumin. Both derivatives showed high fluorescence efficiency (quantum yield) and greater photostability in solution. The improved photostability could be attributed to the coordination structures and the removal of β-diketone group from curcumin. The fluorescence and ultra violet/visible absorption spectra of curcumin, B-Cur2 and Fe-Cur3 all have a similar spectral pattern when dissolved in the same organic solvent. However, a shift towards a lower wavelength was observed when moving from polar to non-polar solvents, possibly due to differences in solvent polarity. A plot of Stokes' shift vs the orientation polarity parameter (Δf) or vs the solvent polarity parameter (ET 30) showed an improved correlation between the solvent polarity parameter than with the orientation polarity parameter and indicating that the red shift observed could be due to hydrogen-bonding between the solvent molecules. A similar association was obtained when Stokes' shift was replaced by maximum synchronous fluorescence. Both B-Cur2 and Fe-Cur3 had larger quantum yields than curcumin, suggesting they may be good candidates for medical imaging and in vitro studies.

  9. Oscillo-polarographic determination of boron based on its complex formation with polyphenol

    International Nuclear Information System (INIS)

    Fukushi, Norio

    1978-01-01

    A test solution in a 50-ml measuring flask contained the following reagents, 5 ml of 1 M KCl as a supporting electrolyte, 10 ml of NH 4 Cl-NH 3 buffer solution (pH 8 -- 10), 0 -- 5 ml of 10 -2 M H 3 BO 3 , and (1 -- 5) ml of 10 -3 M of a polyphenol, such as Pyrocatechol Violet (PV), Pyrogallol Red, Bromopyrogallol Red. Difference between the oscillopolarograms of the solutions containing and not containing boric acid together with certain amounts of a polyphenol was only the variation of the peak currents based on the electrode reaction of the polyphenol, being accompanied with some variation in their peak currents with time elapsed. In the case of using PV as the polyphenol, the relation between the concentration of PV and the peak current was quantitative at the peak potential of -0.69 V vs. SCE. The decrease of the peak current (Δi sub(p)) by the addition of boric acid in various concentrations was measured. To this procedure, the concentration ratio of PV to boric acid must be considered, too. Results obtained under various experimental conditions showed that an indirect determination of boron by oscillographic polarographic method is very promising. (author)

  10. Controlled release of astaxanthin from nanoporous silicified-phospholipids assembled boron nitride complex for cosmetic applications

    Science.gov (United States)

    Lee, Hye Sun; Sung, Dae Kyung; Kim, Sung Hyun; Choi, Won Il; Hwang, Ee Tag; Choi, Doo Jin; Chang, Jeong Ho

    2017-12-01

    Nanoporous silicified-phospholipids assembled boron nitride (nSPLs@BN) powder was prepared and demonstrated for use in controlled release of anti-oxidant astaxanthin (AX) as a cosmetic application. The nanoporous silicified phospholipids (nSPLs) were obtained by the silicification with tetraethyl orthosilicate (TEOS) of the hydrophilic region of phospholipid bilayers. This process involved the co-assembly of chemically active phospholipid bilayers within the porous silica matrix. In addition, nSPLs@BN was characterized using several analytical techniques and tested to assess their efficiency as drug delivery systems. We calculated the maximum release amounts as a function of time and various pH. The release rate of AX from the nSPLs@BN for the initial 24 h was 10.7 μmol/(h mg) at pH 7.4. Furthermore, we determined the antioxidant activity (KD) for the released AX with DPPH (1,1-diphenyl-2-picryl-hydrazyl) radical and the result was 34.6%.

  11. Complex Boron Redistribution in P+ Doped-polysilicon / Nitrogen Doped Silicon Bi-layers during Activation Annealing

    Science.gov (United States)

    Abadli, S.; Mansour, F.; Perrera, E. Bedel

    We have investigated and modeled the complex phenomenon of boron (B) redistribution process in strongly doped silicon bilayers structure. A one-dimensional two stream transfer model well adapted to the particular structure of bi- layers and to the effects of strong-concentrations has been developed. This model takes into account the instantaneous kinetics of B transfer, trapping, clustering and segregation during the thermal B activation annealing. The used silicon bi-layers have been obtained by low pressure chemical vapor deposition (LPCVD) method, using in-situ nitrogen- doped-silicon (NiDoS) layer and strongly B doped polycrystalline-silicon (P+) layer. To avoid long redistributions, thermal annealing was carried out at relatively lowtemperatures (600 °C and 700 °C) for various times ranging between 30 minutes and 2 hours. The good adjustment of the simulated profiles with the experimental secondary ion mass spectroscopy (SIMS) profiles allowed a fundamental understanding about the instantaneous physical phenomena giving and disturbing the complex B redistribution profiles-shoulders kinetics.

  12. Complex boron redistribution kinetics in strongly doped polycrystalline-silicon/nitrogen-doped-silicon thin bi-layers

    Energy Technology Data Exchange (ETDEWEB)

    Abadli, S. [Department of Electrical Engineering, University Aout 1955, Skikda, 21000 (Algeria); LEMEAMED, Department of Electronics, University Mentouri, Constantine, 25000 (Algeria); Mansour, F. [LEMEAMED, Department of Electronics, University Mentouri, Constantine, 25000 (Algeria); Pereira, E. Bedel [CNRS-LAAS, 7 avenue du colonel Roche, 31077 Toulouse (France)

    2012-10-15

    We have investigated the complex behaviour of boron (B) redistribution process via silicon thin bi-layers interface. It concerns the instantaneous kinetics of B transfer, trapping, clustering and segregation during the thermal B activation annealing. The used silicon bi-layers have been obtained by low pressure chemical vapor deposition (LPCVD) method at 480 C, by using in-situ nitrogen-doped-silicon (NiDoS) layer and strongly B doped polycrystalline-silicon (P{sup +}) layer. To avoid long-range B redistributions, thermal annealing was carried out at relatively low-temperatures (600 C and 700 C) for various times ranging between 30 min and 2 h. To investigate the experimental secondary ion mass spectroscopy (SIMS) doping profiles, a redistribution model well adapted to the particular structure of two thin layers and to the effects of strong-concentrations has been established. The good adjustment of the simulated profiles with the experimental SIMS profiles allowed a fundamental understanding about the instantaneous physical phenomena giving and disturbing the complex B redistribution profiles-shoulders. The increasing kinetics of the B peak concentration near the bi-layers interface is well reproduced by the established model. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Conversion of dimethyl ether--boron trifluoride complex to potassium fluoborate

    Science.gov (United States)

    Eberle, A.R.

    1957-06-18

    A method of preparing KBF/sub 4/ from the dimethyl ether complex of BF/sub 3/ is given. This may be accomplished by introducing the dimethyl ether complex of BF/sub 3/ into an aqueous solution of KF and alcohol, expelling the ether liberated from the complex by heating or stirring and recovering the KBF/sub 4/ so formed. The KBF/sub 4/ is then filtered from the alcohol-water solution, which may be recycled, to reduce the loss of KBF/sub 4/ which is not recovered by filtration.

  14. Separation of glycols from dilute aqueous solutions via complexation with boronic acids

    Energy Technology Data Exchange (ETDEWEB)

    Randel, L.A.; King, C.J.

    1991-07-01

    This work examines methods of separating low molecular weight glycols from dilute aqueous solution. Extraction into conventional solvents is generally not economical, since, in the literature reviewed, distribution ratios for the two- to four-carbon glycols are all less than one. Distribution ratios can be increased, however, by incorporating into the organic phase an extracting agent that will complex with the solute of interest. The extracting agent investigated in this work is 3-nitrophenylboronic acid (NPBA). NPBA, a boric acid derivative, reversibly complexes with many glycols. The literature on complexation of borate and related compounds with glycols, including mechanistic data, measurement techniques, and applications to separation processes, provides information valuable for designing experiments with NPBA and is reviewed herein. 88 refs., 15 figs., 24 tabs.

  15. Boron reclamation

    International Nuclear Information System (INIS)

    Smith, R.M.

    1980-07-01

    A process to recover high purity 10 B enriched crystalline boron powder from a polymeric matrix was developed on a laboratory basis and ultimately scaled up to production capacity. The process is based on controlled pyrolysis of boron-filled scrap followed by an acid leach and dry sieving operation to return the powder to the required purity and particle size specifications. Typically, the recovery rate of the crystalline powder is in excess of 98.5 percent, and some of the remaining boron is recovered in the form of boric acid. The minimum purity requirement of the recovered product is 98.6 percent total boron

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

    OpenAIRE

    LI Jian-ping

    2014-01-01

    The boron isotopes separation test was performed by chemical exchange reaction in the benzene ether -three boron fluoride system, which resulted to the boron isotopic enrichment of -10 in the liquid phase, the boron isotopic enrichment of -11 in the gas phase. After then, boron isotope separation trial production has been finished. In this process, the exchange column and complex tower normal operating parameters and the complex tower technology have been obtained, the problems of material di...

  17. Deuterium exchange at terminal boron--hydrogen bonds catalyzed by certain transition metal complexes. A qualitative study of selectivity and mechanism

    International Nuclear Information System (INIS)

    Hoel, E.L.; Talebinasab-Savari, M.; Hawthorne, M.F.

    1977-01-01

    A wide variety of substrates, including carboranes, metallocarboranes, and boron hydrides, were found to undergo catalytic isotopic exchange of terminal hydrogen with deuterium gas in the presence of various transition metal complexes. With (PPh 3 ) 3 RuHCl as catalyst, exchange was found to proceed with stereoselectivity indicative of nucleophilic attack at boron; e.g., the order of rates for deuterium incorporation at chemically nonequivalent sites in 1,2-C 2 B 10 H 12 was B(3,6) greater than B(4,5,7,11) greater than B(8,10) greater than B(9,12). Other catalysts, most notably the series of hydridometallocarboranes, (PPh 3 ) 2 HMC 2 B 9 H 11 (M = Rh, Ir), showed little or no stereoselectivity during deuterium exchange. Intermediate stereoselectivity was found with (PPh 3 ) 2 (CO)IrCl and (PPh 3 ) 2 IrCl species as catalysts, while exchange catalyzed by (AsPh 3 ) 2 IrCl exhibited the stereoselectivity found with (PPh 3 ) 3 RuHCl. A mechanism is postulated which rationalizes the varied results and which involves oxidative addition of boron--hydrogen bonds to catalytic species

  18. Preparação e caracterização espectroscópica de complexos de boro: uma proposta para uma prática integrada de química inorgânica Preparation and spectroscopic characterization of boron complexes: a proposal for an integrated inorganic laboratory

    Directory of Open Access Journals (Sweden)

    Karl Eberhard Bessler

    2010-01-01

    Full Text Available As a proposal for an undergraduate second or third year inorganic laboratory course, the present paper describes the preparation of three representative boron complexes: potassium tetrafluoroborate, pyridoxin boron complex and potassium bis(oxalatoborate. The complexes are characterised by infrared and multinuclear magnetic resonance spectroscopy (¹H, 11B and 19F where isotopic effects are demonstrated.

  19. Crystal structures of Leishmania mexicana arginase complexed with α,α-disubstituted boronic amino-acid inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Hai, Yang; Christianson, David W.

    2016-03-16

    Leishmaniaarginase is a potential drug target for the treatment of leishmaniasis because this binuclear manganese metalloenzyme initiatesde novopolyamine biosynthesis by catalyzing the hydrolysis of L-arginine to generate L-ornithine and urea. The product L-ornithine subsequently undergoes decarboxylation to yield putrescine, which in turn is utilized for spermidine biosynthesis. Polyamines such as spermidine are essential for the growth and survival of the parasite, so inhibition of enzymes in the polyamine-biosynthetic pathway comprises an effective strategy for treating parasitic infections. To this end, two X-ray crystal structures ofL. mexicanaarginase complexed with α,α-disubstituted boronic amino-acid inhibitors based on the molecular scaffold of 2-(S)-amino-6-boronohexanoic acid are now reported. Structural comparisons with human and parasitic arginase complexes reveal interesting differences in the binding modes of the additional α-substituents,i.e.the D side chains, of these inhibitors. Subtle differences in the three-dimensional contours of the outer active-site rims among arginases from different species lead to different conformations of the D side chains and thus different inhibitor-affinity trends. The structures suggest that it is possible to maintain affinity while fine-tuning intermolecular interactions of the D side chain of α,α-disubstituted boronic amino-acid inhibitors in the search for isozyme-specific and species-specific arginase inhibitors.

  20. Crystalline boron nitride aerogels

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-12-12

    This disclosure provides methods and materials related to boron nitride aerogels. For example, one aspect relates to a method for making an aerogel comprising boron nitride, comprising: (a) providing boron oxide and an aerogel comprising carbon; (b) heating the boron oxide to melt the boron oxide and heating the aerogel; (c) mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide; and (d) converting at least a portion of the carbon to boron nitride to obtain the aerogel comprising boron nitride. Another aspect relates to a method for making an aerogel comprising boron nitride, comprising heating boron oxide and an aerogel comprising carbon under flow of a nitrogen-containing gas, wherein boron oxide vapor and the nitrogen-containing gas convert at least a portion of the carbon to boron nitride to obtain the aerogel comprising boron nitride.

  1. Metal interactions with boron clusters

    International Nuclear Information System (INIS)

    Grimes, R.N.

    1982-01-01

    This book presents information on the following topics: the structural and bonding features of metallaboranes and metallacarboranes; transition-metal derivatives of nido-boranes and some related species; interactions of metal groups with the octahydrotriborate (1-) anion, B 3 H 8 ; metallaboron cage compounds of the main group metals; closo-carborane-metal complexes containing metal-carbon and metal-boron omega-bonds; electrochemistry of metallaboron cage compounds; and boron clusters with transition metal-hydrogen bonds

  2. Crystal Structures of KPC-2[beta]-Lactamase in Complex with 3-Nitrophenyl Boronic Acid and the Penam Sulfone PSR-3-226

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Wei; Bethel, Christopher R.; Papp-Wallace, Krisztina M.; Pagadala, Sundar Ram Reddy; Nottingham, Micheal; Fernandez, Daniel; Buynak, John D.; Bonomo, Robert A.; van den Akker, Focco (Case Western); (Stokes); (SMU)

    2012-08-01

    Class A carbapenemases are a major threat to the potency of carbapenem antibiotics. A widespread carbapenemase, KPC-2, is not easily inhibited by {beta}-lactamase inhibitors (i.e., clavulanic acid, sulbactam, and tazobactam). To explore different mechanisms of inhibition of KPC-2, we determined the crystal structures of KPC-2 with two {beta}-lactamase inhibitors that follow different inactivation pathways and kinetics. The first complex is that of a small boronic acid compound, 3-nitrophenyl boronic acid (3-NPBA), bound to KPC-2 with 1.62-{angstrom} resolution. 3-NPBA demonstrated a Km value of 1.0 {+-} 0.1 {micro}M (mean {+-} standard error) for KPC-2 and blocks the active site by making a reversible covalent interaction with the catalytic S70 residue. The two boron hydroxyl atoms of 3-NPBA are positioned in the oxyanion hole and the deacylation water pocket, respectively. In addition, the aromatic ring of 3-NPBA provides an edge-to-face interaction with W105 in the active site. The structure of KPC-2 with the penam sulfone PSR-3-226 was determined at 1.26-{angstrom} resolution. PSR-3-226 displayed a K{sub m} value of 3.8 {+-} 0.4 {micro}M for KPC-2, and the inactivation rate constant (kinact) was 0.034 {+-} 0.003 s{sup -1}. When covalently bound to S70, PSR-3-226 forms a trans-enamine intermediate in the KPC-2 active site. The predominant active site interactions are generated via the carbonyl oxygen, which resides in the oxyanion hole, and the carboxyl moiety of PSR-3-226, which interacts with N132, N170, and E166. 3-NPBA and PSR-3-226 are the first {beta}-lactamase inhibitors to be trapped as an acyl-enzyme complex with KPC-2. The structural and inhibitory insights gained here could aid in the design of potent KPC-2 inhibitors.

  3. Boron nitride composites

    Science.gov (United States)

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

    2017-02-21

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

  4. Boron Nitride Nanotubes

    Science.gov (United States)

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

    2012-01-01

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

  5. Comparative analysis of electron-density and electron-localization function for dinuclear manganese complexes with bridging boron- and carbon-centered ligands.

    Science.gov (United States)

    Götz, Kathrin; Kaupp, Martin; Braunschweig, Holger; Stalke, Dietmar

    2009-01-01

    Bonding in borylene-, carbene-, and vinylidene-bridged dinuclear manganese complexes [MnCp(CO)(2)](2)X (X = B-tBu, B = NMe(2), CH(2), C=CH(2)) has been compared by analyses based on quantum theory of atoms in molecules (QTAIM), on the electron-localization function (ELF), and by natural-population analyses. All of the density functional theory based analyses agree on the absence of a significant direct Mn-Mn bond in these complexes and confirm a dominance of delocalized bonding via the bridging ligand. Interestingly, however, the topology of both charge density and ELF related to the Mn-bridge-Mn bonding depend qualitatively on the chosen density functional (except for the methylene-bridged complex, which exhibits only one three-center-bonding attractor both in -nabla(2)rho and in ELF). While gradient-corrected functionals provide a picture with localized two-center X-Mn bonding, increasing exact-exchange admixture in hybrid functionals concentrates charge below the bridging atom and suggests a three-center bonding situation. For example, the bridging boron ligands may be described either as substituted boranes (e.g., at BLYP or BP86 levels) or as true bridging borylenes (e.g., at BHLYP level). This dependence on the theoretical level appears to derive from a bifurcation between two different bonding situations and is discussed in terms of charge transfer between X and Mn, and in the context of self-interaction errors exhibited by popular functionals.

  6. Boron isotopic enrichment by displacement chromatography

    International Nuclear Information System (INIS)

    Mohapatra, K.K.; Bose, Arun

    2014-01-01

    10 B 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 10 B 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 10 B and 11 B

  7. Methods of forming boron nitride

    Science.gov (United States)

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

    2015-03-03

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

  8. 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. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. A simple ratiometric fluorescent sensor for fructose based on complexation of 10-hydroxybenzo[h]quinoline with boronic acid

    Science.gov (United States)

    Li, Huihui; Yang, Cailing; Zhu, Xinyue; Zhang, Haixia

    2017-06-01

    A simple ratiometric fluorescent sensor for fructose was presented. It consisted of 10-hydroxybenzo[h]quinoline (HBQ) which showed emission at 572 nm and 3-pyridylboronic acid (PDBA) whose complex with HBQ gave emission at 500 nm. The reaction of fructose with PDBA inhibited the complexation of HBQ with PDBA, resulting in the change of dual-emission intensity ratio. The sensor well quantified fructose in the range of 0.015-2.5 mM with detection limit of 0.005 mM. Besides, this sensor exhibited excellent selectivity and was successfully applied to fructose detection in food. This work provides a simple ratiometric sensing platform for sensitive and selective detection of fructose.

  10. Determination of boron concentration in biopsy-sized tissue samples

    International Nuclear Information System (INIS)

    Hou, Yougjin; Fong, Katrina; Edwards, Benjamin; Autry-Conwell, Susan; Boggan, James

    2000-01-01

    Inductively coupled plasma mass spectrometry (ICP-MS) is the most sensitive analytical method for boron determination. However, because boron is volatile and ubiquitous in nature, low-concentration boron sample measurement remains a challenge. In this study, an improved ICP-MS method was developed for quantitation of tissue samples with low (less than 10 ppb) and high (100 ppb) boron concentrations. The addition of an ammonia-mannitol solution converts volatile boric acid to the non-volatile ammonium borate in the spray chamber and with the formation of a boron-mannitol complex, the boron memory effect and background are greatly reduced. This results in measurements that are more accurate, repeatable, and efficient. This improved analysis method has facilitated rapid and reliable tissue biodistribution analyses of newly developed boronated compounds for potential use in neutron capture therapy. (author)

  11. High solid-state luminescence in propeller-shaped AIE-active pyridine-ketoiminate-boron complexes.

    Science.gov (United States)

    Wu, Yanping; Li, Zhenyu; Liu, Qingsong; Wang, Xiaoqing; Yan, Hui; Gong, Shuwen; Liu, Zhipeng; He, Weijiang

    2015-05-28

    Two pyridine-ketoiminate-based organoboron complexes (2 and 3) were developed. 2 and 3 showed very weak emission in low-viscosity organic solvents because of the intramolecular rotation induced non-radiative process. Their emission can be dramatically enhanced by the increase in solvent viscosity or by molecular aggregation in the solid state. Moreover, 2 and 3 exhibited intense emission with high quantum yield of 0.53 and 0.46, respectively. X-ray crystallographic analysis showed that the weak intermolecular interactions such as C-H···F and C-H···π by fixing the molecular conformations of 2 and 3 were responsible for intense luminescence in the solid state. The large Stokes shifts and high efficient solid-state emission of 2 and 3 make them valuable AIE luminophores for further potential applications in the fields of fluorescence imaging and materials science.

  12. Boron nitride converted carbon fiber

    Science.gov (United States)

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

    2016-04-05

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

  13. High performance ligands for the removal of aqueous boron species by continuous polymer enhanced ultrafiltration

    OpenAIRE

    Yürüm, Alp; Yurum, Alp; Taralp, Alpay; Bıçak, Niyazi; Bicak, Niyazi; Özbelge, Hilmi Önder; Ozbelge, Hilmi Onder; Yılmaz, Levent; Yilmaz, Levent

    2013-01-01

    Boron is an essential element for plant growth, but it may also result in toxicity when present in excessive amounts. In this study, continuous polymer enhanced ultrafiltration (PEUF) was developed to selectively recover aqueous boron species (collectively termed “boron” hereafter) from solution. The PEUF process consisted of complexing boron to a water-soluble polymer, removing all non-complexed solutes by UF, restoring the unloaded polymer, and isolating the newly freed boron by UF. Three d...

  14. Advanced microstructure of boron carbide.

    Science.gov (United States)

    Werheit, Helmut; Shalamberidze, Sulkhan

    2012-09-26

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

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

    International Nuclear Information System (INIS)

    Kitaoka, Yoshinori

    1992-09-01

    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. Biological evaluation of boronated unnatural amino acids as new boron carriers

    Energy Technology Data Exchange (ETDEWEB)

    Kabalka, G.W. [Departments of Radiology and Chemistry, University of Tennessee, Knoxville, TN (United States)], E-mail: kabalka@utk.edu; Yao, M.-L.; Marepally, S.R. [Departments of Radiology and Chemistry, University of Tennessee, Knoxville, TN (United States); Chandra, S. [Cornell SIMS Laboratory, Department of Earth and Atmospheric Sciences, Snee Hall, Cornell University, Ithaca, NY (United States)

    2009-07-15

    There is a pressing need for new and more efficient boron delivery agents to tumor cells for use in boron neutron capture therapy (BNCT). A class of boronated unnatural cyclic amino acids has demonstrated a remarkable selectivity toward tumors in animal and cell culture models, far superior to currently used agents in clinical BNCT. One of these amino acids, 1-amino-3-boronocyclopentanecarboxylic acid (ABCPC), has shown a tumor to blood ratio of 8 and a tumor to normal brain ratio of nearly 21 in a melanoma bearing mouse model. This work represents further biological characterization of this compound for tumor targeting in an EMT6 murine mammary carcinoma mouse model and a T98G human glioblastoma cell line. Female BALB/c mice bearing EMT6 tumors were injected with the fructose complex form of racemic mixtures of cis and trans isomers of ABCPC in identical concentrations. Boron concentrations were measured in the tumor, blood, brain, skin, and liver tissues at 1, 3, and 5 h post-injection. These observations revealed a remarkable difference in racemic mixtures of cis and trans isomers in tumor targeting by boron. This implies that further separation of the L and D forms of this compound may enhance tumor targeting to an even higher degree than that provided by the racemic mixtures. Since the uptake measurements were made in homogenized tumor and normal tissues, little is known about the subcellular location of the boron arising from the various isomeric forms of the amino acid. To study subcellular delivery of boron from ABCPC in T98G human glioblastoma cells, we employed secondary ion mass spectrometry (SIMS) based technique of ion microscopy, which is capable of quantitatively imaging isotopic (elemental) gradients in cells and tissues at 500 nm spatial resolution. The T98G cells were exposed to the nutrient medium containing 100 ppm boron equivalent of a mixture of both L and D isomers of ABCPC in the form of a fructose complex for 1 h. Following this treatment

  17. Biological Evaluation of Boronated Unnatural Amino Acids as New Boron Carriers

    Science.gov (United States)

    Kabalka, G.W.; Yao, M.-L.; Marepally, S.R.; Chandra, S.

    2010-01-01

    There is a pressing need for new and more efficient boron delivery agents to tumor cells for use in boron neutron capture therapy (BNCT). A class of boronated unnatural cyclic amino acids has demonstrated a remarkable selectivity toward tumors in animal and cell culture models, far superior to currently used agents in clinical BNCT. One of these amino acids, 1-amino-3-boronocyclopentanecarboxylic acid (ABCPC), has shown a tumor to blood ratio of 8 and a tumor to normal brain ratio of nearly 21 in a melanoma bearing mouse model. This work represents further biological characterization of this compound for tumor targeting in an EMT6 murine mammary carcinoma mouse model and a T98G human glioblastoma cell line. Female BALB/c mice bearing EMT6 tumors were injected with the fructose complex form of racemic mixtures of cis- and trans isomers of ABCPC in identical concentrations. Boron concentrations were measured in the tumor, blood, brain, skin, and liver tissues at 1, 3, and 5 hr post injection. These observations revealed a remarkable difference in racemic mixtures of cis and trans isomers in tumor targeting by boron. This implies that further separation of the L and D forms of this compound may enhance tumor targeting to an even higher degree than that provided by the racemic mixtures. Since the uptake measurements were made in homogenized tumor and normal tissues, little is known about the subcellular location of the boron arising from the various isomeric forms of the amino acid. To study subcellular delivery of boron from ABCPC in T98G human glioblastoma cells, we employed secondary ion mass spectrometry (SIMS) based technique of ion microscopy, which is capable of quantitatively imaging isotopic (elemental) gradients in cells and tissues at 500 nm spatial resolution. The T98G cells were exposed to the nutrient medium containing 100 ppm boron equivalent of a mixture of both L and D isomers of ABCPC in the form of a fructose complex for 1 hr. Following this

  18. Pulverization of boron element and proportions of boron carbide in boron

    International Nuclear Information System (INIS)

    Lang, F.M.; Finck, C.

    1956-01-01

    It is possible to reduce boron element into fine powder by means of a mortar and pestle made of sintered boron carbide, the ratio of boron carbide introduced being less than one per cent. Boron element at our disposal is made of sharp edged, dark brown, little grains of average size greater than 5 μ. Grain sizes smaller than 1μ are required for applying thin layers of such boron. (author) [fr

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

    Science.gov (United States)

    Hunt, Curtiss D

    2012-06-01

    This review summarizes the progress made in establishing essential roles for boron in human physiology and assesses that progress in view of criteria for essentiality of elements. The evidence to date suggests that humans and at least some higher animals may use boron to support normal biological functions. These include roles in calcium metabolism, bone growth and maintenance, insulin metabolism, and completion of the life cycle. The biochemical mechanisms responsible for these effects are poorly understood but the nature of boron biochemistry suggests further characterization of the cell signaling molecules capable of complexing with boron. Such characterization may provide insights into the biochemical function(s) of boron in humans. Copyright © 2012 Elsevier GmbH. All rights reserved.

  20. Additive Manufacturing of Dense Hexagonal Boron Nitride Objects

    Energy Technology Data Exchange (ETDEWEB)

    Marquez Rossy, Andres E [ORNL; Armstrong, Beth L [ORNL; Elliott, Amy M [ORNL; Lara-Curzio, Edgar [ORNL

    2017-05-12

    The feasibility of manufacturing hexagonal boron nitride objects via additive manufacturing techniques was investigated. It was demonstrated that it is possible to hot-extrude thermoplastic filaments containing uniformly distributed boron nitride particles with a volume concentration as high as 60% and that these thermoplastic filaments can be used as feedstock for 3D-printing objects using a fused deposition system. Objects 3D-printed by fused deposition were subsequently sintered at high temperature to obtain dense ceramic products. In a parallel study the behavior of hexagonal boron nitride in aqueous solutions was investigated. It was shown that the addition of a cationic dispersant to an azeotrope enabled the formulation of slurries with a volume concentration of boron nitride as high as 33%. Although these slurries exhibited complex rheological behavior, the results from this study are encouraging and provide a pathway for manufacturing hexagonal boron nitride objects via robocasting.

  1. Update on human health effects of boron.

    Science.gov (United States)

    Nielsen, Forrest H

    2014-10-01

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

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

    International Nuclear Information System (INIS)

    Rao, Radhika M.; Aggarwal, S.K.

    2002-11-01

    Experiments were conducted for the determination of boron in U 3 O 8 powder, aluminium metal and milliQ water using dynamically modified Reversed Phase High Pressure Liquid Chromatography (RP-HPLC) and using two precolumn chromogenic agents viz. chromotropic acid and curcumin for complexing boron. The complex was separated from the excess of reagent and determined by HPLC. When present in subppm levels, chromotropic acid was used successfully only for determination boron in water samples. For determination of boron at subppm levels in uranium and aluminium samples, curcumin was used as the precolumn chromogenic agent. The boron curcumin complex (rosocyanin) was formed after extraction of boron with 2-ethyl-l, 3-hexane diol (EHD). The rosocyanin complex was then separated from excess curcumin by displacement chromatography. Linear calibration curves for boron amounts in the range of 0.02 μg to 0.5 μg were developed with correlation coefficients varying from 0.997 to 0.999 and were used for the determination of boron in aluminium and uranium samples. Precision of about 10% was achieved in samples containing less than 1 ppmw of boron. Detection limit of this method is 0.01 μg boron. (author)

  3. Determination of boron in silicon related nuclear materials by spectrophotometry

    International Nuclear Information System (INIS)

    Ramanjaneyulu, P.S.; Sayi, Y.S.; Ramakumar, K.L.

    2007-01-01

    Boron is one of the important specifications in all-nuclear materials. The present paper describes in detail about the determination of boron in U-Al-Si and SILUMIN. The sample is treated with H 2 O 2 and 3 M HCl. Silicon will be left as precipitate. It was removed by centrifugation. Boron was selectively separated by solvent extraction with 10% 2-ethyl hexane 1,3-diol and was quantitatively determined by spectrophotometry using curcumin as complexing agent. Since standard reference materials are not available, standard addition method was employed to confirm the results. (author)

  4. Boronated liposome development and evaluation

    International Nuclear Information System (INIS)

    Hawthorne, M.F.

    1995-01-01

    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

  5. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

    mental phase contrast images and the diffraction pattern. Figure 3. (a) Bright field image of electrodeposited boron spec- imen showing a crystallite of size ∼10 × 5 nm; (b) phase contrast image of electrodeposited boron specimen showing a resolved la- ttice and (c) power spectrum of electrodeposited boron specimen.

  6. Enrichment of boron 10

    International Nuclear Information System (INIS)

    Coutinho, C.M.M.; Rodrigues Filho, J.S.R.; Umeda, K.; Echternacht, M.V.

    1990-01-01

    A isotopic separation pilot plant with five ion exchange columns interconnected in series were designed and built in the IEN. The columns are charged with a strong anionic resin in its alkaline form. The boric acid solution is introduced in the separation columns until it reaches a absorbing zone length which is sufficient to obtain the desired boron-10 isotopic concentration. The boric acid absorbing zone movement is provided by the injection of a diluted hydrochloric acid solution, which replace the boric acid throughout the columns. The absorbing zone equilibrium length is proportional to its total length. The enriched boron-10 and the depleted boron are located in the final boundary and in the initial position of the absorbing zones, respectively. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-06-06

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

  8. Modeling of interstitial diffusion of ion-implanted boron

    International Nuclear Information System (INIS)

    Velichko, O.I.; Knyazheva, N.V.

    2009-01-01

    A model of the interstitial diffusion of ion-implanted boron during rapid thermal annealing of silicon layers previously amorphized by implantation of germanium has been proposed. It is supposed that the boron interstitials are created continuously during annealing due to generation, dissolution, or rearrangement of the clusters of impurity atoms which are formed in the ion-implanted layers with impurity concentration above the solubility limit. The local elastic stresses arising due to the difference of boron atomic radius and atomic radius of silicon also contribute to the generation of boron interstitials. A simulation of boron redistribution during thermal annealing for 60 s at a temperature of 850 C has been carried out. The calculated profile agrees well with the experimental data. A number of the parameters of interstitial diffusion have been derived. In particular, the average migration length of nonequilibrium boron interstitials is equal to 12 nm. It was also obtained that approximately 1.94% of boron atoms were converted to the interstitial sites, participated in the fast interstitial migration, and then became immobile again transferring into a substitutional position or forming the electrically inactive complexes with crystal lattice defects. (authors)

  9. Effect of Carbon Doping on the Electronic Structure and Elastic Properties of Boron Suboxide

    Science.gov (United States)

    2015-06-01

    bonding complexity . When one equatorial boron atom neighboring a C-B-C chain is replaced by carbon, a Ce-CO bond forms between the equatorial carbon...Scripta Materialia. 2014;76:9. 8. Wang Z, Zhao Y. In situ pressure Raman spectroscopy and mechanical stability of superhard boron suboxide. Appl Phys...Lett. 2005;86:041911. 9. Nifise E. Study of sintering and structure property relationships in boron suboxide – alkaline earth metal oxide, cobalt

  10. Process for microwave sintering boron carbide

    Science.gov (United States)

    Holcombe, C.E.; Morrow, M.S.

    1993-10-12

    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.

  11. Bright prospects for boron

    NARCIS (Netherlands)

    Nanver, L.; Wassink, J.

    2012-01-01

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

  12. Methods of producing continuous boron carbide fibers

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-05-08

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

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

    OpenAIRE

    Chaoyu He; J. X. Zhong

    2013-01-01

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

  15. Two photon absorption energy transfer in the light-harvesting complex of photosystem II (LHC-II) modified with organic boron dye

    Science.gov (United States)

    Chen, Li; Liu, Cheng; Hu, Rui; Feng, Jiao; Wang, Shuangqing; Li, Shayu; Yang, Chunhong; Yang, Guoqiang

    2014-07-01

    The plant light-harvesting complexes of photosystem II (LHC-II) play important roles in collecting solar energy and transferring the energy to the reaction centers of photosystems I and II. A two photon absorption compound, 4-(bromomethyl)-N-(4-(dimesitylboryl)phenyl)-N-phenylaniline (DMDP-CH2Br), was synthesized and covalently linked to the LHC-II in formation of a LHC-II-dye complex, which still maintained the biological activity of LHC-II system. Under irradiation with femtosecond laser pulses at 754 nm, the LHC-II-dye complex can absorb two photons of the laser light effectively compared with the wild type LHC-II. The absorbed excitation energy is then transferred to chlorophyll a with an obvious fluorescence enhancement. The results may be interesting and give potentials for developing hybrid photosystems.

  16. Synthesis of Aryliron Complexes [CpFe(CO2Ar] by Palladium-Catalyzed Reactions of [CpFe(CO2I] with Arylzinc, -Boron, or -Indium Reagents

    Directory of Open Access Journals (Sweden)

    Koichiro Oshima

    2009-08-01

    Full Text Available Transmetalation between [CpFe(CO2I] and arylzinc iodide-lithium chloride complexes proceeds in the presence of catalytic amounts of palladium acetate and N,N,N’,N’-tetramethyl-1,2-cyclohexanediamine to yield the corresponding aryliron complexes [CpFe(CO2Ar]. Phenylation of [CpFe(CO2I] also takes place when triphenylindium is used under similar conditions. Arylboronic acids undergo arylation in the presence of cesium carbonate and a palladium-N-heterocyclic carbene complex, PEPPSI. The present methods are useful for the facile synthesis of various functionalized [CpFe(CO2Ar]. The products [CpFe(CO2Ar] represent an interesting class of aryl metals that undergo several transformation.

  17. Fivefold twinned boron carbide nanowires.

    Science.gov (United States)

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

    2009-09-09

    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.

  18. Reversible Coordination of Boron-, Aluminum-, Zinc-, Magnesium-, and Calcium-Hydrogen Bonds to Bent {CuL2} Fragments: Heavy σ Complexes of the Lightest Coinage Metal.

    Science.gov (United States)

    Hicken, Alexandra; White, Andrew J P; Crimmin, Mark R

    2017-08-07

    A series of copper(I) complexes bearing electron-deficient β-diketiminate ligands have been prepared. The study includes [{{ArNC(CR 3 )} 2 CH}Cu(η 2 -toluene) n ] (Ar = Mes, R = F, n = 0.5, [1 2 ·tol]; Ar = C 6 F 5 , R = Me, n = 1, [2·tol]; Ar = 2,6-Cl 2 C 6 H 3 , R = H, n = 0.5, [3 2 ·tol]). Reactions of [1-3 n ·tol] with boranes, alanes, a zinc hydride, a magnesium hydride, and a calcium hydride generate the corresponding σ complexes ([1-3·B], [3·B'], [3·Al], [3·Al'], [1-3·Zn], [1·Mg], and [1·Ca]). These species all form reversibly, being in equilibrium with the arene solvates in solution. With the exception of the calcium complex, the complexes have all been characterized by single-crystal X-ray diffraction studies. In solution, the σ-hydride of the aluminum, zinc, magnesium, and calcium derivatives resonates between -0.12 and -1.77 ppm (C 6 D 6 or toluene-d 8 , 193-298 K). For the σ-borane complexes, the hydrides are observed as a single resonance between 2 and 3.5 ppm (C 6 D 6 , 298 K) and bridging and terminal hydrides rapidly exchange on the NMR time scale even at 193 K. Quantification of the solution dynamics by van't Hoff analysis yields expectedly small values of ΔH° and negative values of ΔS° consistent with weak binding and a reversible process that does not involve aggregation of the copper species. The donor-acceptor complexes can be rationalized in terms of the Dewar-Chatt-Duncanson model. Density functional theory calculations show that the donation of σ-M-H (or E-H) electrons into the 4s-based orbital (LUMO or LUMO+1) of the copper fragment is accompanied by weak back-donation from a d xz -based orbital (HOMO or HOMO-1) into the σ*-M-H (or E-H) orbital.

  19. A critical study of the alkalimetric titration of mannitoboric acid complex in relation to the determination of boron in glass and related materials

    International Nuclear Information System (INIS)

    Sinha, B.C.; Dasgupta, S.

    1976-01-01

    The effect of mannitol concentration on the slope of ΔpH/Δv at the equivalence point of neutralisation of mannitoboric acid has been studied. The slope is observed to be dependent on mannitol concentration and it increases with increasing reagent concentration. The minimum pH at which titration of mannitoboric acid complex is possible without any significant error has been found to be 6.4 with a mannitol concentration of at least 15 g/50 ml of solution although the stoichiometric equivalence pH is 9.0. Based on the result of the study, a simple and accurate method has been worked out for the determination of B 2 0 3 up to 141 mg/50 ml in glass and related materials. The titration of mannitoboric acid complex is carried out at the minimum equivalence pH of 6.4 to minimise precipitation of hydroxides and phosphates of certain cations. The interference due to various elements such as Al, Fe, Zr, Pb and Zn when present are eliminated by complexing them with EDTA. Fluorine above 40 mg/50 ml interferes with the determination. (author)

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

    Science.gov (United States)

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

    2016-02-01

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

  1. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

    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 ...

  2. Considerations for boron neutron capture therapy studies

    International Nuclear Information System (INIS)

    Faria Gaspar, P. de.

    1994-01-01

    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

  3. Functionalized boron nitride nanotubes

    Science.gov (United States)

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

    2014-04-22

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

  4. Boron Activated Neutron Thermometer

    Energy Technology Data Exchange (ETDEWEB)

    Lapsley, A. C. [Argonne National Lab. (ANL), Argonne, IL (United States). Instrument Research & Development

    1952-01-09

    The Brown Instrument Division of Minneapolis-Honeywell Regulator Co. have been making pilot models of boron coated neutron sensitive thermopiles, which show considerable promise of being effective indicators of slow neutron flux. Their loss in sensitivity in a year of operation in the maximum flux of CP-6 calculates to be less than 6 per cent. When used as rooftop indicators, the ratio of the signal of the two units would change by about 2 per cent in a year's time.

  5. Boron atom reactions

    International Nuclear Information System (INIS)

    Estes, R.; Tabacco, M.B.; Digiuseppe, T.G.; Davidovits, P.

    1982-01-01

    The reaction rates of atomic boron with various epoxides have been measured in a flow tube apparatus. The bimolecular rate constants, in units of cm 3 molecule -1 s -1 , are: 1,2-epoxypropane (8.6 x 10 -11 ), 1,2-epoxybutane (8.8 x 10 -11 ), 1,2,3,4-diepoxybutane (5.5 x 10 -11 ), 1-chloro-2,3-epoxypropane (5.7 x 10 -11 ), and 1,2-epoxy-3,3,3-trichloropropane (1.5 x 10 -11 ). (orig.)

  6. Boron isotopes and groundwater pollution

    International Nuclear Information System (INIS)

    Vengosh, A.

    1999-01-01

    Boron can be used as a tracer in ground water because of its high solubility in aqueous solutions, natural abundance in all waters, and the lack of effects by evaporation, volatilisation, oxidation-reduction reactions. Since the boron concentrations in pristine ground waters are generally low and contaminant sources are usually enriched in boron, the δ 11 B of groundwater is highly sensitive to the impact of contamination. The large isotopic variations of the potential sources can be used to trace the origin of the contamination and to reconstruct mixing and flow paths

  7. Lattice dynamics of α boron and of boron carbide

    International Nuclear Information System (INIS)

    Vast, N.

    1999-01-01

    The atomic structure and the lattice dynamics of α boron and of B 4 C boron carbide have been studied by Density Functional Theory (D.F.T.) and Density Functional Perturbation Theory (D.F.P.T.). The bulk moduli of the unit-cell and of the icosahedron have been investigated, and the equation of state at zero temperature has been determined. In 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 B 4 C. Finally, the effects of isotopic disorder have been modeled by an exact method beyond the mean-field approximation, and the effects onto the Raman lines has been investigated. The method has been applied to isotopic alloys of diamond and germanium. (author)

  8. The Vibrational Spectra of the Boron Halides and their Molecular ...

    African Journals Online (AJOL)

    The structures, interaction energies and vibrational spectra of the van derWaals complexes formed between boron trifluoride, as Lewis acid, and water and hydrogen sulphide, as Lewis bases, have been determined by means of ab initio calculations at the second-order level of Møller-Plesset perturbation theory, using a ...

  9. 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.

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

    International Nuclear Information System (INIS)

    Kitaoka, Yoshinori

    1993-09-01

    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.)

  11. Nothing Boring About Boron

    Science.gov (United States)

    Pizzorno, Lara

    2015-01-01

    The trace mineral boron is a micronutrient with diverse and vitally important roles in metabolism that render it necessary for plant, animal, and human health, and as recent research suggests, possibly for the evolution of life on Earth. As the current article shows, boron has been proven to be an important trace mineral because it (1) is essential for the growth and maintenance of bone; (2) greatly improves wound healing; (3) beneficially impacts the body’s use of estrogen, testosterone, and vitamin D; (4) boosts magnesium absorption; (5) reduces levels of inflammatory biomarkers, such as high-sensitivity C-reactive protein (hs-CRP) and tumor necrosis factor α (TNF-α); (6) raises levels of antioxidant enzymes, such as superoxide dismutase (SOD), catalase, and glutathione peroxidase; (7) protects against pesticide-induced oxidative stress and heavy-metal toxicity; (8) improves the brains electrical activity, cognitive performance, and short-term memory for elders; (9) influences the formation and activity of key biomolecules, such as S-adenosyl methionine (SAM-e) and nicotinamide adenine dinucleotide (NAD+); (10) has demonstrated preventive and therapeutic effects in a number of cancers, such as prostate, cervical, and lung cancers, and multiple and non-Hodgkin’s lymphoma; and (11) may help ameliorate the adverse effects of traditional chemotherapeutic agents. In none of the numerous studies conducted to date, however, do boron’s beneficial effects appear at intakes > 3 mg/d. No estimated average requirements (EARs) or dietary reference intakes (DRIs) have been set for boron—only an upper intake level (UL) of 20 mg/d for individuals aged ≥ 18 y. The absence of studies showing harm in conjunction with the substantial number of articles showing benefits support the consideration of boron supplementation of 3 mg/d for any individual who is consuming a diet lacking in fruits and vegetables or who is at risk for or has osteopenia; osteoporosis

  12. Analytical methods for the determination of boron in reactor materials programme

    International Nuclear Information System (INIS)

    Chitre, R.S.; Joshi, V.R.; Iyer, C.S.P.

    1983-01-01

    Spectrophotometric methods of determination of boron based on the complexation reaction between boric acid and protonated curcumin are briefly reviewed. Direct determination of boron in heavy water, plant leaves, copper and its alloys, and aluminium and its alloys using a modified method of Hayes and Metcalfe is described. A method for determination of boron, when its content is very low as in case of uranium metal, diuranate, uranium oxide and thorium nitrate, is also described. In this method, boron is first separated as methyl borate by distillation of the sample with methanol in acid media. The distilled ester is absorbed by hydroxide solution and boron is analysed after removal of methanol. The precision obtained is indicated. (M.G.B.)

  13. The boron connection: Roots (routes), grounds, horizons

    Science.gov (United States)

    Zdetsis, Aristides D.

    2012-12-01

    Isoelectronic and isolobal silicon-based analogues to boranes and borane complexes are considered and studied. The framework and the implementation of such isoelectronic and isolobal analogies initially between silicon clusters (cluster dianions) and isovalent boranes, known under the scoptical and synoptical name "boron connection" is critically analyzed and reviewed in considerable depth and breadth, paying special attention to its conceptual simplicity, origin, and originality. It is illustrated that such a concept can be extended to several borane complexes producing analogous silicon based (nano)structures. This is achieved by considering and evaluating several vertical, horizontal and diagonal relationships on the periodical table rooted on Si. It is shown that this type of simple and transparent relationships can lead to far reaching extensions and generalizations of the "boron connection" to encompass structural and electronic relationships between additional simple and mixed clusters based in addition to Si on other group 14 elements. Such clusters include, among others, simple Gen2- and Snn2- dianions and mixed Si-Bi, Ge-Bi and Sn-Bi clusters. Special emphasis is placed on molecular and material engineering and functionalization, in analogy to similar functionalization of borane based molecules and materials. It is illustrated that this enlarged and expanded project is very promising and could be very successful for the design of a practically unlimited number of new group-14-based complexes as well as the rationalization and fictionalization of newly synthesized materials.

  14. Annealing of deep boron centers in silicon carbide

    CERN Document Server

    Ballandovich, V S

    2002-01-01

    Effect of thermal annealing on the high temperature luminescence efficiency (HTL) in 6H-SiC samples grown in different conditions and doped with boron impurity was investigated. Some of the crystals were irradiated by reactor neutrons or fast electrons. The HTL efficiency was shown to depend on the abundance of deep boron centers discovered by capacitive spectroscopy as D-centers. High temperature treatment of samples results in decomposition of D-centers which is identified as B sub S sub i -V sub C complexes. The deep boron centers are shown to be stable at temperature as low as 1500 deg C. Conservation of these centers in SiC crystals at higher temperatures (up to 2600 deg C) is caused by presence of clusters which are the sources of nonequilibrium carbon vacancies

  15. Nano boron nitride flatland.

    Science.gov (United States)

    Pakdel, Amir; Bando, Yoshio; Golberg, Dmitri

    2014-02-07

    Recent years have witnessed many breakthroughs in research on two-dimensional (2D) nanomaterials, among which is hexagonal boron nitride (h-BN), a layered material with a regular network of BN hexagons. This review provides an insight into the marvellous nano BN flatland, beginning with a concise introduction to BN and its low-dimensional nanostructures, followed by an overview of the past and current state of research on 2D BN nanostructures. A comprehensive review of the structural characteristics and synthetic routes of BN monolayers, multilayers, nanomeshes, nanowaves, nanoflakes, nanosheets and nanoribbons is presented. In addition, electronic, optical, thermal, mechanical, magnetic, piezoelectric, catalytic, ecological, biological and wetting properties, applications and research perspectives for these novel 2D nanomaterials are discussed.

  16. 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.

  17. Gold intercalation of boron-doped graphene on Ni(111): XPS and DFT study.

    Science.gov (United States)

    Zhao, W; Gebhardt, J; Gotterbarm, K; Höfert, O; Gleichweit, C; Papp, C; Görling, A; Steinrück, H-P

    2013-11-06

    The intercalation of a graphene layer adsorbed on a metal surface by gold or other metals is a standard procedure. While it was previously shown that pristine, i.e., undoped, and nitrogen-doped graphene sheets can be decoupled from a nickel substrate by intercalation with gold atoms in order to produce quasi-free-standing graphene, we find the gold intercalation behavior for boron-doped graphene on a Ni(111) surface to be more complex: for low boron contents (2-5%) in the graphene lattice only partial gold intercalation occurs and for higher boron contents (up to 20%) no intercalation is observed. In order to understand this different behavior, a density functional theory investigation is carried out, comparing undoped as well as substitutional nitrogen- and boron-doped graphene on Ni(111). We identify the stronger binding of the boron atoms to the nickel substrate as the factor responsible for the different intercalation behavior in the case of boron doping. However, the calculations predict that this energetic effect prevents the intercalation process only for large boron concentrations and that it can be overcome for smaller boron coverages, in line with our x-ray photoelectron spectroscopy experiments.

  18. The biodistribution of boron in normal canine tissues following borocaptate sodium administration and the effect of plasma exchange

    International Nuclear Information System (INIS)

    Kraft, S.L.; Gavin, P.R.; DeHaan, C.E.; Ary, T.E.; Bauer, W.F.

    1992-01-01

    Normal tissue tolerance establishes the dose limitations for any form of radiation therapy. The complexity of the mixed form of radiation from Boron Neutron Capture Therapy (BNCT) makes it difficult to predict normal tissue tolerance. A premise for BNCT is that the ideal boron compound should result in minimal boron concentrations in normal tissues and blood and high concentrations in tumor tissue. Borocaptate sodium (Na 2 B 12 H 11 SH or BSH) was administered to a set of dogs with naturally-occurring, intracranial tumors to evaluate the relative boron distribution in neoplastic and normal tissue. Data on the biodistribution of boron to these normal tissues is presented here in context of normal tissue tolerance. Since boron from BSH binds significantly to plasma proteins, plasma exchange following BSH infusion in a set of normal laboratory dogs was performed to evaluate the effect on blood and tissue concentrations as a potential means to increase normal tissue tolerance

  19. 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.

  20. 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)

  1. Future boronated molecules for neutron capture therapy

    International Nuclear Information System (INIS)

    Soloway, A.H.; Alam, F.; Barth, R.F.

    1986-01-01

    The ability of several boron compounds to localize in tumor cells is examined. A number of first and second generation compounds which were not synthesized specifically for localization are described. Among these are the boron hydrides and boranes. A third generation of boron compounds are designed for selective localization. These fall into two groups: relatively small organic compounds and boronated antibodies, both of which are discussed here

  2. Compression and Associated Properties of Boron Carbide

    Science.gov (United States)

    2008-12-01

    Klandadze, G.I., and Eristavi, A.M., 1999: IR- Active Phonons and Structure Elements of Isotope - Enriched Boron Carbide, J. Sol. State Chem. 154, 79- 86...COMPRESSION AND ASSOCIATED PROPERTIES OF BORON CARBIDE D. P. Dandekar*and J. A. Ciezak Army Research Laboratory, APG, MD 21005 M. Somayazulu...of the observed loss of shear strength in boron carbide under plane shock wave compression to amorphization in boron carbide under triaxial stress

  3. Lattice vibrations in α-boron

    International Nuclear Information System (INIS)

    Richter, W.

    1976-01-01

    α-rhombohedral boron is the simplest boron modification, with only 12 atoms per unit cell. The boron atoms are arranged in B 12 icosahedra, which are centered at the lattice points of a primitive rhombohedral lattice. The icosahedra are slightly deformed, as the five-fold symmetry of the ideal icosahedron is incompatible with any crystal structure. The lattice dynamics of α-boron are discussed in terms of the model developed by Weber and Thorpe. (Auth.)

  4. Synthesis of oligomeric boron-containing phospolyols

    International Nuclear Information System (INIS)

    Bondarenko, S.N.; Khokhlova, T.V.; Orlova, S.A.; Tuzhikov, O.I.

    2006-01-01

    Structure is investigated and reactivity of oligomeric boron-containing phospolyols is studied. Oligomeric boron-containing compound interacts with ethylene glycol, diethylene glycol, glycerol, 1,4-butandiol with formation of linear boron-containing phospolyols. Reactions proceed in noncatalytic conditions with stoichiometric quantities of reagents at 170-200 Deg C in inert gas media. Boron-containing phospolyols are viscous uncolored liquids, their physicochemical characteristics are represented [ru

  5. Studies on the phase diagram of boron employing a neural network potential

    Energy Technology Data Exchange (ETDEWEB)

    Morawietz, Tobias; Behler, Joerg [Lehrstuhl fuer Theoretische Chemie, Ruhr-Universitaet Bochum (Germany); Parrinello, Michele [Department of Chemistry and Applied Biosciences, ETH Zuerich (Switzerland)

    2009-07-01

    The crystalline phases of elemental boron have a structural complexity unique in the periodic table. The complex connection pattern of the icosahedral building blocks forms a formidable challenge for the construction of accurate but efficient potentials. We present a high-dimensional neural network potential for boron, which is based on first-principles calculations and can be systematically improved. The potential is several orders of magnitude faster to evaluate than the underlying density-functional theory calculations and allows to perform long molecular dynamics and metadynamics simulations of large system. By a stepwise refinement of the potential and an application of the potential in metadynamics simulations we show that starting from random atomic positions the structure of {alpha}-boron is predicted in agreement with experiment. Further, pressure-induced phase transitions of {alpha}-boron are discussed.

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

    OpenAIRE

    He, Chaoyu; Zhong, Jianxin

    2013-01-01

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

  7. Boron steel. I Part. Preparation

    International Nuclear Information System (INIS)

    Jaraiz Franco, E.; Esteban Hernandez, J. A.

    1960-01-01

    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 Fe 2 B phase and its subsequent X-Ray identification has proved to be satisfactory. (Author) 11 refs

  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. New Icosahedral Boron Carbide Semiconductors

    Science.gov (United States)

    Echeverria Mora, Elena Maria

    Novel semiconductor boron carbide films and boron carbide films doped with aromatic compounds have been investigated and characterized. Most of these semiconductors were formed by plasma enhanced chemical vapor deposition. The aromatic compound additives used, in this thesis, were pyridine (Py), aniline, and diaminobenzene (DAB). As one of the key parameters for semiconducting device functionality is the metal contact and, therefore, the chemical interactions or band bending that may occur at the metal/semiconductor interface, X-ray photoemission spectroscopy has been used to investigate the interaction of gold (Au) with these novel boron carbide-based semiconductors. Both n- and p-type films have been tested and pure boron carbide devices are compared to those containing aromatic compounds. The results show that boron carbide seems to behave differently from other semiconductors, opening a way for new analysis and approaches in device's functionality. By studying the electrical and optical properties of these films, it has been found that samples containing the aromatic compound exhibit an improvement in the electron-hole separation and charge extraction, as well as a decrease in the band gap. The hole carrier lifetimes for each sample were extracted from the capacitance-voltage, C(V), and current-voltage, I(V), curves. Additionally, devices, with boron carbide with the addition of pyridine, exhibited better collection of neutron capture generated pulses at ZERO applied bias, compared to the pure boron carbide samples. This is consistent with the longer carrier lifetimes estimated for these films. The I-V curves, as a function of external magnetic field, of the pure boron carbide films and films containing DAB demonstrate that significant room temperature negative magneto-resistance (> 100% for pure samples, and > 50% for samples containing DAB) is possible in the resulting dielectric thin films. Inclusion of DAB is not essential for significant negative magneto

  10. Chemical separation of boron isotopes

    International Nuclear Information System (INIS)

    Palko, A.A.

    1978-06-01

    This is the final report of the research performed at ORNL on the chemical fractionation of boron isotopes between BF 3 gas and the liquid molecular addition compounds of BF 3 . Thirty compounds were studied, ten of them in detail. Graphs and equations are given for variation of isotopic equilibrium constant, vapor pressure, and BF 3 solubility as a function of temperature. Rate of isotopic exchange and melting points were determined. Several of the compounds are likely candidates for use in a gas-liquid countercurrent exchange system for large-scale separation of boron isotopes. 23 figs, 53 tables, 39 references

  11. Chemical separation of boron isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Palko, A.A.

    1978-06-01

    This is the final report of the research performed at ORNL on the chemical fractionation of boron isotopes between BF/sub 3/ gas and the liquid molecular addition compounds of BF/sub 3/. Thirty compounds were studied, ten of them in detail. Graphs and equations are given for variation of isotopic equilibrium constant, vapor pressure, and BF/sub 3/ solubility as a function of temperature. Rate of isotopic exchange and melting points were determined. Several of the compounds are likely candidates for use in a gas-liquid countercurrent exchange system for large-scale separation of boron isotopes. 23 figs, 53 tables, 39 references.

  12. Boron cycling in subduction zones

    OpenAIRE

    Palmer, Martin R.

    2017-01-01

    Subduction zones are geologically dramatic features, with much of the drama being driven by the movement of water. The “light and lively” nature of boron, coupled with its wide variations in isotopic composition shown by the different geo-players in this drama, make it an ideal tracer for the role and movement of water during subduction. The utility of boron ranges from monitoring how the fluids that are expelled from the accretionary prism influence seawater chemistry, to the subduction of c...

  13. Determination of boron spectrophotometry in thorium sulfate

    International Nuclear Information System (INIS)

    Federgrun, L.; Abrao, A.

    1976-01-01

    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 ThF 4 . To overcome this difficulty, the thorium sulfate is dissolved using a strong cationic ion exchanger, Th 4+ 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 [pt

  14. Synthesis and characterizaton of some new coordination compounds of boron with mixed azines

    Directory of Open Access Journals (Sweden)

    MANISH GODARA

    2007-04-01

    Full Text Available Some new boron complexes have been synthesized by the reaction of triisopropohxyborane with the mixed azines, prepared by the condensation of salicylaldehyde and hydrazine with aldehydes/ketones in a 1:1:1 mole ratio to give a new series of (OPri2B(NO type of complexes. Their structures were confirmed on the basis of elemental analyses, ultraviolet, infrared, 1H-NMR and 11B-NMR spectral studies. The ligands and their boron complexes were also screened for their antifungal activity. Several of these complexes were found to be quite active in this respect.

  15. Boron Nitride Nanoribbons from Exfoliation of Boron Nitride Nanotubes

    Science.gov (United States)

    Hung, Ching-Cheh; Hurst, Janet; Santiago, Diana

    2017-01-01

    Two types of boron nitride nanotubes (BNNTs) were exfoliated into boron nitride nanoribbons (BNNR), which were identified using transmission electron microscopy: (1) commercial BNNTs with thin tube walls and small diameters. Tube unzipping was indicated by a large decrease of the sample's surface area and volume for pores less than 2 nm in diameter. (2) BNNTs with large diameters and thick walls synthesized at NASA Glenn Research Center. Here, tube unraveling was indicated by a large increase in external surface area and pore volume. For both, the exfoliation process was similar to the previous reported method to exfoliate commercial hexagonal boron nitride (hBN): Mixtures of BNNT, FeCl3, and NaF (or KF) were sequentially treated in 250 to 350 C nitrogen for intercalation, 500 to 750 C air for exfoliation, and finally HCl for purification. Property changes of the nanosized boron nitride throughout this process were also similar to the previously observed changes of commercial hBN during the exfoliation process: Both crystal structure (x-ray diffraction data) and chemical properties (Fourier-transform infrared spectroscopy data) of the original reactant changed after intercalation and exfoliation, but most (not all) of these changes revert back to those of the reactant once the final, purified products are obtained.

  16. Synthesis of boron nitride from boron containing poly (vinyl alcohol ...

    Indian Academy of Sciences (India)

    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 ...

  17. Boron analysis and boron imaging in biological materials for Boron Neutron Capture Therapy (BNCT).

    Science.gov (United States)

    Wittig, Andrea; Michel, Jean; Moss, Raymond L; Stecher-Rasmussen, Finn; Arlinghaus, Heinrich F; Bendel, Peter; Mauri, Pier Luigi; Altieri, Saverio; Hilger, Ralf; Salvadori, Piero A; Menichetti, Luca; Zamenhof, Robert; Sauerwein, Wolfgang A G

    2008-10-01

    Boron Neutron Capture Therapy (BNCT) is based on the ability of the stable isotope 10B to capture neutrons, which leads to a nuclear reaction producing an alpha- and a 7Li-particle, both having a high biological effectiveness and a very short range in tissue, being limited to approximately one cell diameter. This opens the possibility for a highly selective cancer therapy. BNCT strongly depends on the selective uptake of 10B in tumor cells and on its distribution inside the cells. The chemical properties of boron and the need to discriminate different isotopes make the investigation of the concentration and distribution of 10B a challenging task. The most advanced techniques to measure and image boron are described, both invasive and non-invasive. The most promising approach for further investigation will be the complementary use of the different techniques to obtain the information that is mandatory for the future of this innovative treatment modality.

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

    International Nuclear Information System (INIS)

    Agarwal, A.; Eaglesham, D.J.; Gossmann, H.J.; Pelaz, L.; Herner, S.B.; Jacobson, D.C.

    1998-01-01

    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 10 14 and of 1 x 10 15 /cm -2 . Formation of the shallowest possible junctions by 0.5 keV B + requires that the implant dose be kept lower than this threshold

  19. 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.

  20. Boron removal from wastewater using adsorbents.

    Science.gov (United States)

    Kluczka, J; Trojanowska, J; Zolotajkin, M; Ciba, J; Turek, M; Dydo, P

    2007-01-01

    In the present study, boron adsorption on activated alumina and activated carbon impregnated with calcium chloride, tartaric acid and mannitol was investigated. The adsorbate in question was the wastewater from the chemical landfill in Tarnowskie Gory of 25-70 mg l(-1) boron content. The removal of boron from the above-described wastewater was examined in the static (batch) and dynamic (column) experiments. The static experiments were carried out to assess boron adsorption isotherms, based on which the most efficient adsorbent as well as the rough resin load was determined. On the basis of the dynamic experiment results, the boron adsorptive capacities of the examined resins were deduced. It was concluded that the use of the impregnants increased the ability of activated carbon to adsorb boron. Granulated activated carbon WG-12 impregnated with mannitol was found to be the most promising for the boron removal from wastewater of the Chemical Wastewater Plant in Tarnowskie Gory.

  1. Boron isotopes in geothermal systems

    International Nuclear Information System (INIS)

    Aggarwal, J.

    1997-01-01

    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 CO 2 boron isotope ratios from a volatile B source can also be inferred. (auth)

  2. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

    electrolysis was crystalline in nature, X-ray diffraction pat-. ∗. Author for correspondence (sas@igcar.gov.in) .... Elemental boron was synthesized by the electrolysis of molten potassium fluroborate dissolved in a ... A high-throughput Renishaw micro-Raman spectrome- ter (model Invia) was employed to record Raman ...

  3. Preparation process of boron nitride

    International Nuclear Information System (INIS)

    Mignani, G.; Ardaud, P.

    1990-01-01

    High purity boron nitride, without Si and a low carbon content, is prepared by pyrolysis, under an ammoniac atmosphere, of the reaction product between a B-trihalogenoborazole and a primary amine RNH 2 when R is a hydrocarbon radical eventually substituted containing from 1 to 6 carbon atoms inclusively [fr

  4. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

    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 ...

  5. Method of separating boron isotopes

    Science.gov (United States)

    Jensen, Reed J.; Thorne, James M.; Cluff, Coran L.; Hayes, John K.

    1984-01-01

    A method of boron isotope enrichment involving the isotope preferential photolysis of (2-chloroethenyl)dichloroborane as the feed material. The photolysis can readily be achieved with CO.sub.2 laser radiation and using fluences significantly below those required to dissociate BCl.sub.3.

  6. Prevention of uncontrolled boron dilution

    International Nuclear Information System (INIS)

    Sere, J. L.

    1997-01-01

    The paper presents a synthesis of the global analysis of uncontrolled boron dilution risk performed by (European Consortium Mochovce (EUCOM) in the frame of Safety Measures RC 01 and AA 11. Recommendation for additional improvements (mainly I and C interlocks or inhibition) are presented. (author)

  7. Boron-11 MRI and MRS of intact animals infused with a boron neutron capture agent

    International Nuclear Information System (INIS)

    Kabalka, G.W.; Davis, M.; Bendel, P.

    1988-01-01

    Boron neutron capture therapy (BNCT) depends on the delivery of boron-containing drugs to a targeted lesion. Currently, the verification and quantification of in vivo boron content is a difficult problem. Boron-11 spectroscopy was utilized to confirm the presence of a dimeric sulfhydryl dodecaborane BNCT agent contained in an intact animal. Spectroscopy experiments revealed that the decay time of transverse magnetization of the boron-11 spins was less than 1 ms which precluded the use of a 2DFT imaging protocol. A back-projection protocol was developed and utilized to generate the first boron-11 image of a BNCT agent in the liver of an intact Fisher 344 rat

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

    International Nuclear Information System (INIS)

    2011-01-01

    was grafted by PEG and Poli(Ac)-g 1 -2-AEPB-g 2 -PEG macro branched polymer was synthesized. - Poly(ethylene-alt-maleic anhyride)-PEG-2AEPB was synthesized by esterication of PEG and amidification of 2-AEPB. - Firstly, Poly(ethylene-alt-maleic anhydride) was hydrolized to form water-solube Poly(ethylene-alt-maleic acid). Then, at different mole ratio, 2-AEPB compound was bound to this water soluble polymer. Finally, Poly(ethylene-alt-maleic anhydride)-2-AEPB-PEG was synthesized by esterification of Poly(ethylene-alt-maleic anhydride)-2-AEPB and PEG. Characterization of these macro complex polymers were performed by FTIR, DSC, TGA and NMR analysis. Functional groups which have tumor targeting property will be determined and related experiments will be started. In order to start the cell culture experiments, the required coordination will be done. The second study has been carried out with METU and Adnan Menderes University. Experimental studies have been done in Polymer Chemistry Laboratory and Organic Chemistry Laboratory of Adnan Menderes University. In this study, polyester dendrimer structure was synthesized and characterized by FTIR and NMR analysis. Carborane compound purchased from foreign chemical firm. In order to incorporate polyester dendrimer by carborane, carborane will be functioned by organic synthesis. This study has been carried out in Laboratory of Adnan Menderes University. In this technical report, the first experimental study carried out together with Hacettepe University of boron chemistry group will be discussed.

  9. Separation of the isotopes of boron by chemical exchange reactions

    Science.gov (United States)

    McCandless, F.P.; Herbst, R.S.

    1995-05-30

    The isotopes of boron, {sup 10}B and {sup 11}B, are separated by means of a gas-liquid chemical exchange reaction involving the isotopic equilibrium between gaseous BF{sub 3} and a liquid BF{sub 3} donor molecular addition complex formed between BF{sub 3} gas and a donor chosen from the group consisting of: nitromethane, acetone, methyl isobutyl ketone, or diisobutyl ketone. 1 Fig.

  10. Separation of the isotopes of boron by chemical exchange reactions

    Science.gov (United States)

    McCandless, Frank P.; Herbst, Ronald S.

    1995-01-01

    The isotopes of boron, .sup.10 B and .sup.11 B, are separated by means of a gas-liquid chemical exchange reaction involving the isotopic equilibrium between gaseous BF.sub.3 and a liquid BF.sub.3 . donor molecular addition complex formed between BF.sub.3 gas and a donor chosen from the group consisting of: nitromethane, acetone, methyl isobutyl ketone, or diisobutyl ketone.

  11. Study of extraction-spectrophotometric micro-determination of boron with methylene blue and its application

    International Nuclear Information System (INIS)

    Zhu Daohong

    1990-08-01

    A sensitive extraction-spectrophotometric method for microdetermination of boron with methylene blue was investigated. The method was based on the extraction of a BF 4 - -methylene blue complex into dichloroethane. Boron was determined directly by measuring the absorbance at 658 nm. The calibration graph was linear over the range of 2.5 x 10 -9 to 8 x 10 -8 g/mL. The blank, mechanism of the reactions, interference of other ions and some optimum conditions of the method were studied in detail. The main source of the blank resulted from methylene blue and the complex of F - -methylene blue. In order to reduce the blank, the amounts of methylene blue, H 2 SO 4 and HF were used as less as possible. Only one to one complex BF 4 - -methylene blue was formed in the medium of H 2 SO 4 . About 90% of methylene blue and F - -methylene blue complex was removre with 5 ml of water and only a little amount of BF 4 -methylene blue complex was decomposed. The extraction-spectrophotometric method with methylene blue was first applied to the microdetermination of boron in sodium metal and UF 6 . The sample of sodium metal was taken and weighed in the glovebox filled with argon. Then sodium metal was oxidized, hydrolyzed, netralized and fluorizated with H 2 O, H 2 SO 4 and HF, respectively. The 0.5 ppm of boron in sodium metal was determined with a relative error about ±4%. This method can be applied to the determination of boron in sodium metal, sodium sulfate and sodium hydroxide at diffeent grades. The species of boron in the hydrolysate of UF 6 is BF 4 - anion, so the sample can be directly analyzed. Boron contents in the range of 0.1 to 0.5 ppm was determined with a relative error about ±3%. Six samples could be analysed in 2h

  12. Boron hydride analogues of the fullerenes

    International Nuclear Information System (INIS)

    Quong, A.A.; Pederson, M.R.; Broughton, J.Q.

    1994-01-01

    The BH moiety is isoelectronic with C. We have studied the stability of the (BH) 60 analogue of the C 60 fullerene as well as the dual-structure (BH) 32 icosahedron, both of them being putative structures, by performing local-density-functional electronic calculations. To aid in our analysis, we have also studied other homologues of these systems. We find that the latter, i.e., the dual structure, is the more stable although the former is as stable as one of the latter's lower homologues. Boron hydrides, it seems, naturally form the dual structures used in algorithmic optimization of complex fullerene systems. Fully relaxed geometries are reported as well as electron affinities and effective Hubbard U parameters. These systems form very stable anions and we conclude that a search for BH analogues of the C 60 alkali-metal supeconductors might prove very fruitful

  13. Contribution to the study by infrared spectroscopy of addition compounds of boron fluorides and ethers-oxides or organic sulphides

    International Nuclear Information System (INIS)

    Le Calve, Jacques

    1964-01-01

    This research thesis reports the study of complexes formed with boron fluoride and ethers or organic sulphides. In a first part, the author recalls vibration modes of free boron fluoride and of this compound in a complex. In the next parts, he reports the analysis of infrared spectra of groups present in addition compounds (between 400 and 1500 cm -1 ). He discusses spectrum modifications of electron donors by formation of a coordination bound. Experimental conditions are presented in appendix [fr

  14. Effects of boron-water on cattle

    Energy Technology Data Exchange (ETDEWEB)

    Green, G.H.; Weeth, H.J.

    1975-01-01

    To determine the effects of subtoxic concentrations of boron in drinking water, 12 Hereford heifers were used in a 3 x 3 latin-square experiment with four squares. Treatments were tap-water (0.8 ppm boron), 150 ppm boron-water, and 300 ppm boron-water. Periods were 30 days each. Total urine was collected during the last week of each period, and renal clearance observations (based on creatinine) were made on the last day of each period. While water consumption and total urine weight were not affected by the boron treatments, hay consumption decreased, and weight loss was noted. Plasma boron concentrations were 0.53 +/- 0.151 ppm, 11.2 +/- 0.91 ppm, and 18.9 +/- 0.60 ppm while the heifers were drinking tap-water, 150 ppm boron-water, and 300 ppm boron-water respectively. Urinary boron excretion rates were tap water, 64 +/- 5.6 mg/day; 150 ppm, 2841 +/- 181.2 mg/day; 300 ppm, 4932 +/- 173.3 mg/day. Although glomerular filtration and osmolal clearance were unaffected by the boron-waters, a relative diuresis was indicated by the free water clearance effects. The percent of filtered boron which was reabsorbed decreased with increased exogenous boron, as well as both plasma and urinary phosphate. These data indicate that 300 ppm boron is not acutely toxic to heifers when consumed via the drinking water. The safe tolerance concentration, however, must lie below 150 ppm because this concentration was responsible for some deleterious effects.

  15. Boron removal from hydraulic fracturing wastewater by aluminum and iron coagulation: Mechanisms and limitations.

    Science.gov (United States)

    Chorghe, Darpan; Sari, Mutiara Ayu; Chellam, Shankararaman

    2017-12-01

    One promising water management strategy during hydraulic fracturing is treatment and reuse of flowback/produced water. In particular, the saline flowback water contains many of the chemicals employed for fracking, which need to be removed before possible reuse as "frac water." This manuscript targets turbidity along with one of the additives; borate-based cross-linkers used to adjust the rheological characteristics of the frac-fluid. Alum and ferric chloride were evaluated as coagulants for clarification and boron removal from saline flowback water obtained from a well in the Eagle Ford shale. Extremely high dosages (> 9000 mg/L or 333 mM Al and 160 mM Fe) corresponding to Al/B and Fe/B mass ratios of ∼70 and molar ratios of ∼28 and 13 respectively were necessary to remove ∼80% boron. Hence, coagulation does not appear to be feasible for boron removal from high-strength waste streams. X-ray photoelectron spectroscopy revealed BO bonding on surfaces of freshly precipitated Al(OH) 3 (am) and Fe(OH) 3 (am) suggesting boron uptake was predominantly via ligand exchange. Attenuated total reflection-Fourier transform infrared spectroscopy provided direct evidence of inner-sphere boron complexation with surface hydroxyl groups on both amorphous aluminum and iron hydroxides. Only trigonal boron was detected on aluminum flocs since possible presence of tetrahedral boron was masked by severe AlO interferences. Both trigonal and tetrahedral conformation of boron complexes were identified on Fe(OH) 3 surfaces. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Re-sintered boron-rich polycrystalline cubic boron nitride and method for making same

    Energy Technology Data Exchange (ETDEWEB)

    Lavens, T.R.; Corrigan, F.R.; Shott, R.L.; Bovenkerk, H.P.

    1987-06-16

    A method is described for making re-sintered polycrystalline cubic boron nitride (CBN) which comprises: (a) placing sintered substantially catalyst-free boron-rich polycrystalline cubic boron nitride particles in a high pressure/high temperature apparatus, the particles being substantially free of sintering inhibiting impurities; (b) subjecting the boron-rich cubic boron nitride particles to a pressure and a temperature adequate to re-sinter the particles, the temperature being below the CBN reconversion temperature; (c) maintaining the temperature and pressure for a time sufficient to re-sinter the boron-rich cubic boron nitride particles in the apparatus, and (d) recovering the re-sintered polycrystalline cubic boron nitride from the apparatus.

  17. Encapsulation of cisplatin as an anti-cancer drug into boron-nitride and carbon nanotubes: Molecular simulation and free energy calculation

    Energy Technology Data Exchange (ETDEWEB)

    Roosta, Sara [Molecular Simulation Research Laboratory, Department of Chemistry, Iran University of Science & Technology, Tehran (Iran, Islamic Republic of); Hashemianzadeh, Seyed Majid, E-mail: hashemianzadeh@iust.ac.ir [Molecular Simulation Research Laboratory, Department of Chemistry, Iran University of Science & Technology, Tehran (Iran, Islamic Republic of); Ketabi, Sepideh, E-mail: sepidehketabi@yahoo.com [Department of Chemistry, East Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2016-10-01

    Encapsulation of cisplatin anticancer drug into the single walled (10, 0) carbon nanotube and (10, 0) boron-nitride nanotube was investigated by quantum mechanical calculations and Monte Carlo Simulation in aqueous solution. Solvation free energies and complexation free energies of the cisplatin@ carbon nanotube and cisplatin@ boron-nitride nanotube complexes was determined as well as radial distribution functions of entitled compounds. Solvation free energies of cisplatin@ carbon nanotube and cisplatin@ boron-nitride nanotube were − 4.128 kcal mol{sup −1} and − 2457.124 kcal mol{sup −1} respectively. The results showed that cisplatin@ boron-nitride nanotube was more soluble species in water. In addition electrostatic contribution of the interaction of boron- nitride nanotube complex and solvent was − 281.937 kcal mol{sup −1} which really more than Van der Waals and so the electrostatic interactions play a distinctive role in the solvation free energies of boron- nitride nanotube compounds. On the other hand electrostatic part of the interaction of carbon nanotube complex and solvent were almost the same as Van der Waals contribution. Complexation free energies were also computed to study the stability of related structures and the free energies were negative (− 374.082 and − 245.766 kcal mol{sup −1}) which confirmed encapsulation of drug into abovementioned nanotubes. However, boron-nitride nanotubes were more appropriate for encapsulation due to their larger solubility in aqueous solution. - Highlights: • Solubility of cisplatin@ boron-nitride nanotube is larger than cisplatin@ carbon nanotube. • Boron- nitride nanotube complexes have larger electrostatic contribution in solvation free energy. • Complexation free energies confirm encapsulation of drug into the nanotubes in aqueous solution. • Boron- nitride nanotubes are appropriate drug delivery systems compared with carbon nanotubes.

  18. 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.

  19. Boron-10 ABUNCL Active Testing

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-09

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

  20. Boron removal from geothermal waters by electrocoagulation.

    Science.gov (United States)

    Yilmaz, A Erdem; Boncukcuoğlu, Recep; Kocakerim, M Muhtar; Yilmaz, M Tolga; Paluluoğlu, Cihan

    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(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%.

  1. Removal of boron (B) from waste liquors.

    Science.gov (United States)

    Jiang, J Q; Xu, Y; Simon, J; Quill, K; Shettle, K

    2006-01-01

    This paper explores the use of electrocoagulation to remove boron from waste effluent in comparison with alum coagulation. In treating model test wastes, greater boron removals were achieved with electrocoagulation at low doses than conventional alum coagulation when reaction was undertaken for the same conditions (pH 8.5, and initial boron concentration was 500 mg/L). Al electrocoagulation can achieve good boron removal performance (68.3%) at a dose of 2.1 (as molar ratio of Al:B, and for current density of 62.1 A/m2), while alum coagulation can only achieve the maximum boron removal of 56% at a dose of 2.4. Also, Al electrocoagulation can remove 15-20% more boron than alum coagulation for the same dose compared in the treatment of both model test wastes and industry effluent. The estimation of running costs shows that to achieve 75% boron removal from industry waste effluent, i.e. removing 150 g of boron from 1 m3 of effluent, electrocoagulation was 6.2 times cheaper than alum coagulation. The economic advantage of electrocoagulation in the treatment of boron-containing waste effluent is thus significant.

  2. The boron geochemistry of siliceous sponges

    Science.gov (United States)

    de Leon, A.; Wille, M.; Eggins, S. M.; Ellwood, M. J.

    2009-12-01

    The boron content and isotopic composition (δ11B) of marine carbonate organisms can be linked to the pH of the seawater in which they have grown, making carbonates a useful tool for palaeo-seawater pH reconstruction. A study by Furst (1981) documented unusually high boron concentrations in siliceous sponge spicules, in range from hundreds to a thousand ppm. This observation and the potential for preferential incorporation of the tetrahedral borate species into biogenic silica raises the question as to whether the boron chemistry of biogenic silica might also be influenced by seawater pH. We have measured the boron concentration and isotopic composition of siliceous sponges from the Southern Ocean region, with a view to (1) confirming the observations of Furst (1981), (2) assessing the factors that control boron incorporation and isotopic compositions of sponge silica, and (3) investigating the potentially significant role of siliceous sponges in the marine boron cycle. The measured boron concentrations in a diverse range of both demosponge and hexactinellid sponges confirm the high boron concentrations previously reported. The boron isotope compositions of these sponges vary from around +2‰ to +25‰ and greatly exceed the range in marine carbonates. This isotopic variation is inconsistent with seawater pH control but is correlated with ambient seawater silicon concentration, in a manner that suggests a link to silicon uptake kinetics and demand by sponges.

  3. Mineral resource of the month: boron

    Science.gov (United States)

    Crangle, Robert D.

    2012-01-01

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

  4. 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.

  5. Solidification phenomena in nickel base brazes containing boron and silicon

    International Nuclear Information System (INIS)

    Tung, S.K.; Lim, L.C.; Lai, M.O.

    1996-01-01

    Nickel base brazes containing boron and/or silicon as melting point depressants are used extensively in the repair and joining of aero-engine hot-section components. These melting point depressants form hard and brittle intermetallic compounds with nickel which are detrimental to the mechanical properties of brazed joints. The present investigation studied the microstructural evolution in nickel base brazes containing boron and/or silicon as melting point depressant(s) in simple systems using nickel as the base metal. The basic metallurgical reactions and formation of intermetallic compounds uncovered in these systems will be useful as a guide in predicting the evolution of microstructures in similar brazes in more complex systems involving base metals of nickel base superalloys. The four filler metal systems investigated in this study are: Ni-Cr-Si; Ni-Cr-B; Ni-Si-B and Ni-Cr-Fe-Si-B

  6. An Assessment of the Potential Use of BNNTs for Boron Neutron Capture Therapy.

    Science.gov (United States)

    Ferreira, Tiago H; Miranda, Marcelo C; Rocha, Zildete; Leal, Alexandre S; Gomes, Dawidson A; Sousa, Edesia M B

    2017-04-12

    Currently, nanostructured compounds have been standing out for their optical, mechanical, and chemical features and for the possibilities of manipulation and regulation of complex biological processes. One of these compounds is boron nitride nanotubes (BNNTs), which are a nanostructured material analog to carbon nanotubes, but formed of nitrogen and boron atoms. BNNTs present high thermal stability along with high chemical inertia. Among biological applications, its biocompatibility, cellular uptake, and functionalization potential can be highlighted, in addition to its eased utilization due to its nanometric size and tumor cell internalization. When it comes to new forms of therapy, we can draw attention to boron neutron capture therapy (BNCT), an experimental radiotherapy characterized by a boron-10 isotope carrier inside the target and a thermal neutron beam focused on it. The activation of the boron-10 atom by a neutron generates a lithium atom, a gamma ray, and an alpha particle, which can be used to destroy tumor tissues. The aim of this work was to use BNNTs as a boron-10 carrier for BNCT and to demonstrate its potential. The nanomaterial was characterized through XRD, FTIR, and SEM. The WST-8 assay was performed to confirm the cell viability of BNNTs. The cells treated with BNNTs were irradiated with the neutron beam of a Triga reactor, and the apoptosis caused by the activation of the BNNTs was measured with a calcein AM/propidium iodide test. The results demonstrate that this nanomaterial is a promising candidate for cancer therapy through BNCT.

  7. Boron isotopes in the Seine River, France: a probe of anthropogenic contamination.

    Science.gov (United States)

    Chetelat, Benjamin; Gaillardet, Jérôme

    2005-04-15

    Boron concentrations and isotopic compositions have been measured in the dissolved load of the Seine Basin rivers, France. Hydrology and chemistry of the Seine River and its tributaries are strongly influenced by human activities, as the anthropogenic pressure on the Seine catchment is one of the highest in Europe. The samples were collected between 1994 and 1996 during various stages of flow, complemented by a time-series of the Seine River in Paris for 1 yr. In particular, the decennial flood event of winter 1994 was sampled. Boron appears to be conservative in rivers and not influenced by adsorption onto suspended matter and/or consumption by microorganisms. Despite the complexity of the Seine River system, dissolved boron and its isotopes are found to be suitable tracers of contamination. The total dissolved boron of the Seine River at Paris is explained by the contribution from three distinct components: Urban effluents constitute 65% of the boron discharge measured in the Seine River whereas agriculture-affected waters contribute less than 10% with a more marked influence during high water discharges. Rainwater contribution is important (25% mean), reaching 30% of dissolved boron during high flood events.

  8. Methods for separating boron from borated paraffin wax and its determination by ion chromatography

    International Nuclear Information System (INIS)

    Jeyakumar, S.

    2015-01-01

    Boron compounds are found to be useful in shielding against high-energy neutrons. In radiotherapy treatments, in order to protect occupational workers and patients from the undesirable neutron and gamma doses, paraffin wax containing B 4 C/boric acid is used. Low-level borate wastes generated from the nuclear power plants have been immobilized with paraffin wax using a concentrate waste drying system (CWDS). Borated paraffin waxes are prepared by mixing calculated amounts of either boric acid or boron carbide with the molten wax. This necessitates the determination of boron at different locations in order to check the homogeneous distribution of B over the borated wax. The determination of boron in nuclear materials is inevitable due to its high neutron absorption cross section. For the determination of boron in borated waxes, not many methods have been reported. A method based on the pyrohydrolysis extraction of boron and its quantification with ion chromatography was proposed for paraffin waxes borated with H 3 BO 3 and B 4 C. The B 4 C optimum pyrohydrolysis conditions were identified. Wax samples were mixed with U 3 O 8 , which prevents the sample from flare up, and also accelerates the extraction of boron. Pyrohydrolysis was carried out with moist O 2 at 950℃ for 60 and 90 min for wax with H 3 BO 3 and wax with B 4 C, respectively. Two simple methods of separation based on alkali extraction and melting wax in alkali were also developed exclusively for wax with H 3 BO 3 . In all the separations, the recovery of B was above 98%. During IC separation, B was separated as boron-mannitol anion complex. Linear calibration was obtained between 0.1 and 50 ppm of B, and LOD was calculated as 5 ppb (S/N=3). The reproducibility was better than 5% (RSD)

  9. Boron carbide synthesis by carbothermic reduction of boron oxide

    International Nuclear Information System (INIS)

    Castro, A.R.M. de; Paschoal, J.O.A.

    1988-01-01

    Boron carbide (B 4 C) 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 B 4 C by carbothermic reduction of B 2 O 3 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 B 4 C obtained by the carbothermic reduction process is suitable for applications with a definite determination of the free carbon content. (author) [pt

  10. 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.

  11. 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.

  12. Hot flow behavior of boron microalloyed steels

    International Nuclear Information System (INIS)

    Lopez-Chipres, E.; Mejia, I.; Maldonado, C.; Bedolla-Jacuinde, A.; El-Wahabi, M.; Cabrera, J.M.

    2008-01-01

    This research work studies the effect of boron contents on the hot flow behavior of boron microalloyed steels. For this purpose, uniaxial hot-compression tests were carried out in a low carbon steel microalloyed with four different amounts of boron over a wide range of temperatures (950, 1000, 1050 and 1100 deg. C) and constant true strain rates (10 -3 , 10 -2 and 10 -1 s -1 ). Experimental results revealed that both peak stress and peak strain tend to decrease as boron content increases, which indicates that boron additions have a solid solution softening effect. Likewise, the flow curves show a delaying effect on the kinetics of dynamic recrystallization (DRX) when increasing boron content. Deformed microstructures show a finer austenitic grain size in the steel with higher boron content (grain refinement effect). Results are discussed in terms of boron segregation towards austenitic grain boundaries during plastic deformation, which increases the movement of dislocations, enhances the grain boundary cohesion and modificates the grain boundary structure

  13. Compression and associated properties of boron carbide

    Science.gov (United States)

    Ciezak, Jennifer; Dandekar, Dattatraya

    2009-06-01

    The observed loss of shear strength of boron carbide around 22 GPa has been attributed to presence of amorphous material in the shock recovered, and statically indented and pressurized boron carbide. The present work presents a more direct association of the observed loss of shear strength in boron carbide under plane shock wave compression to amorphization in boron carbide under triaxial stress compression. This evidence is obtained from in-situ measurement of Raman, and infrared vibrational spectra of boron carbide confined in a Diamond Anvil Cell (DAC) under hydrostatic and non-hydrostatic pressures. X-ray-diffraction measurements do show a shift in the compression of boron carbide around 27 GPa. However, X-ray diffraction measurements indicate that the amorphization does not extend to micron scale, as there is no evidence of a loss of crystallinity in the recorded diffraction pattern of boron carbide to 47 GPa. Our work shows that shear plays a very dominant role in the stress-induced amorphization of boron carbide.

  14. Ultratough single crystal boron-doped diamond

    Science.gov (United States)

    Hemley, Russell J [Carnegie Inst. for Science, Washington, DC ; Mao, Ho-Kwang [Carnegie Inst. for Science, Washington, DC ; Yan, Chih-Shiue [Carnegie Inst. for Science, Washington, DC ; Liang, Qi [Carnegie Inst. for Science, Washington, DC

    2015-05-05

    The invention relates to a single crystal boron doped CVD diamond that has a toughness of at least about 22 MPa m.sup.1/2. The invention further relates to a method of manufacturing single crystal boron doped CVD diamond. The growth rate of the diamond can be from about 20-100 .mu.m/h.

  15. Spectral tailoring for boron Neutron capture therapy

    NARCIS (Netherlands)

    Nievaart, V.A.

    2007-01-01

    In several places in the world, such as Petten and Delft in the Netherlands, investigations are in progress in the fight against certain types of cancer with Boron Neutron Capture Therapy. The basic idea is very simple: boron is loaded only into the cancer cells, using a special drug, after which

  16. Fabrication of boron-phosphide neutron detectors

    International Nuclear Information System (INIS)

    Fitzsimmons, M.; Pynn, R.

    1997-01-01

    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

  17. 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.

  18. 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.

  19. Continuum modeling of boron nitride nanotubes

    International Nuclear Information System (INIS)

    Song, J; Wu, J; Hwang, K C; Huang, Y

    2008-01-01

    Boron nitride nanotubes display unique properties and have many potential applications. A finite-deformation shell theory is developed for boron nitride nanotubes directly from the interatomic potential to account for the effect of bending and curvature. Its constitutive relation accounts for the nonlinear, multi-body atomistic interactions, and therefore can model the important effect of tube chirality and radius. The theory is then used to determine whether a single-wall boron nitride nanotube can be modeled as a linear elastic isotropic shell. Instabilities of boron nitride nanotubes under different loadings (e.g., tension, compression, and torsion) are also studied. It is shown that the tension instability of boron nitride nanotubes is material instability, while the compression and torsion instabilities are structural instabilities.

  20. 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.

  1. Luminescent materials: locking π-conjugated and heterocyclic ligands with boron(III).

    Science.gov (United States)

    Frath, Denis; Massue, Julien; Ulrich, Gilles; Ziessel, Raymond

    2014-02-24

    Multidisciplinary research on novel organic luminescent dyes is propelled by potential applications in plastic electronics and biomedical sciences. The construction of sophisticated fluorescent dyes around a tetrahedral boron(III) center is a particular approach that has fueled the creativity of chemists. Success in this enterprise has been readily achieved with simple synthetic protocols, the products of which display unusual spectroscopic behavior. This account is a critical review of recent advances in the field of boron(III) complexes (excluding BODIPYs and acetylacetonate boron complexes) involving species displaying similar coordination features, and we outline their potential development in several disciplines. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Spectrophotometric determination of microamounts of boron in water

    International Nuclear Information System (INIS)

    Weber de D'Alessio, Ana; Guido, O.O.; Bandin, N.A.

    1980-01-01

    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) [es

  3. Analysis of boron nitride by flame spectrometry methods

    International Nuclear Information System (INIS)

    Telegin, G.F.; Chapysheva, G.Ya.; Shilkina, N.N.

    1989-01-01

    A rapid method has been developed for determination of free and total boron contents as well as trace impurities in boron nitride by using autoclave sample decomposition followed by atomic emission and atomic absorption determination. The relative standard deviation is not greater than 0.03 in the determination of free boron 0.012 in the determination of total boron content

  4. Chemical vapor deposited boron carbide

    International Nuclear Information System (INIS)

    Mackinnon, I.D.R.; Smith, K.L.

    1987-01-01

    Detailed analytical electron microscope (AEM) studies of yellow whiskers produced by chemical vapor deposition (CVD) show that two basic types of whiskers are produced at low temperatures (between 1200 0 C and 1400 0 C) and low boron to carbon gas ratios. Both whisker types show planar microstructures such as twin planes and stacking faults oriented parallel to, or at a rhombohedral angle to, the growth direction. For both whisker types, the presence of droplet-like terminations containing both Si and Ni indicate that the growth process during CVD is via a vapor-liquid-solid (VLS) mechanisms

  5. 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.

  6. Boron Enrichment in Martian Clay

    Science.gov (United States)

    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

  7. Positron annihilation in boron nitride

    Directory of Open Access Journals (Sweden)

    N.Amrane

    2006-01-01

    Full Text Available Electron and positron charge densities are calculated as a function of position in the unit cell for boron nitride. Wave functions are derived from pseudopotential band structure calculations and the independent particle approximation (IPM, respectively, for electrons and positrons. It is observed that the positron density is maximum in the open interstices and is excluded not only from ion cores but also to a considerable degree from valence bonds. Electron-positron momentum densities are calculated for (001,110 planes. The results are used in order to analyse the positron effects in BN.

  8. Boron nutrition and yield of alfalfa cultivar crioula in relation to boron supply

    Directory of Open Access Journals (Sweden)

    Santos Anacleto Ranulfo dos

    2004-01-01

    Full Text Available Alfalfa cultivar Crioula (Medicago sativa cv. Crioula is grown in South Brazil and only a few studies on the plants' boron requirement are available. A greenhouse experiment was carried out with alfalfa to measure boron acquisition, production and distribution in the plant; data on critical level and production potentials were recorded. Plants were grown in ground quartz added with 1 L of solution, with the following boron rates: 0, 0.0625, 0.125, 0.25, 0.50, 1.00, and 2.00 mg L-1. Plants were harvested at 46 days of growth. Forage dry mass was increased by boron supply and dry matter accumulation was considerably low in control. Boron concentration in the leaves was higher than in the stems or roots. Boron utilization from the external solution reached 90% at 0.0625 mg L-1 and sharply decreased with further increasing boron rates. Boron concentration and content in the leaves and in plant tops were at maximum when applied boron was between 1.5 and 1.6 mg L-1. Critical levels of boron in plant were 61 mg kg-1 in the leaves and 39 mg kg-1 in plant tops for this cultivar of alfalfa.

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

    International Nuclear Information System (INIS)

    Coderre, J.A.; Glass, J.D.; Micca, P.; Greenberg, D.; Packer, S.

    1990-01-01

    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

  10. Large animal normal tissue tolerance with boron neutron capture

    International Nuclear Information System (INIS)

    Gavin, P.R.; Swartz, C.D.; Kraft, S.L.; Briebenow, M.L.; DeHaan, C.E.

    1994-01-01

    Normal tissue tolerance of boron neutron capture irradiation using borocaptate sodium (NA 2 B 12 H 11 SH) in an epithermal neutron beam was studied. Large retriever-type dogs were used and the irradiations were performed by single dose, 5 x 10 dorsal portal. Fourteen dogs were irradiated with the epithermal neutron beam alone and 35 dogs were irradiated following intravenous administration of borocaptate sodium. Total body irradiation effect could be seen from the decreased leukocytes and platelets following irradiation. Most values returned to normal within 40 days postirradiation. Severe dermal necrosis occurred in animals given 15 Gy epithermal neutrons alone and in animals irradiated to a total peak physical dose greater than 64 Gy in animals following borocaptate sodium infusion. Lethal brain necrosis was seen in animals receiving between 27 and 39 Gy. Lethal brain necrosis occurred at 22-36 weeks postirradiation. A total peak physical dose of approximately 27 Gy and blood-boron concentrations of 25-50 ppm resulted in abnormal magnetic resonance imaging results in 6 months postexamination. Seven of eight of these animals remained normal and the lesions were not detected at the 12-month postirradiation examination. The bimodal therapy presents a complex challenge in attempting to achieve dose response assays. The resultant total radiation dose is a composite of low and high LET components. The short track length of the boron fission fragments and the geometric effect of the vessels causes much of the intravascular dose to miss the presumed critical target of the endothelial cells. The results indicate a large dose-sparing effect from the boron capture reactions within the blood. 23 refs., 6 figs., 2 tabs

  11. Study of ceramic mixed boron element as a neutron shielding

    International Nuclear Information System (INIS)

    Ismail Mustapha; Mohd Reusmaazran Yusof; Md Fakarudin Ab Rahman; Nor Paiza Mohamad Hasan; Samihah Mustaffha; Yusof Abdullah; Mohamad Rabaie Shari; Airwan Affandi Mahmood; Nurliyana Abdullah; Hearie Hassan

    2012-01-01

    Shielding upon radiation should not be underestimated as it can causes hazard to health. Precautions on the released of radioactive materials should be well concerned and considered. Therefore, the combination of ceramic and boron make them very useful for shielding purpose in areas of low and intermediate neutron. A six grades of ceramic tile have been produced namely IMN05 - 5 % boron, IMN06 - 6 % boron, IMN07 - 7 % boron, IMN08 - 8 % boron, IMN09 - 9 % boron, IMN10 - 10 % boron from mixing, press and sintered process. Boron is a material that capable of absorbing and capturing neutron, so that neutron and gamma test were conducted to analyze the effectiveness of boron material in combination with ceramic as shielding. From the finding, percent reduction number of count per minute shows the ceramic tiles are capable to capture neutron. Apart from all the percentage of boron used, 10 % is the most effective shields since the percent reduction indicating greater neutron captured increased. (author)

  12. Analysis of Boron Distribution in Steel using Neutron at HANARO

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Eun-Joo; Seong, Baek-Seok; Kim, Hark-Rho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2007-07-01

    Boron is very useful element in steels to improve the mechanical properties. In steel matrix, boron exist several types such as solute, segregation in grain boundary and many kinds of precipitate, which influence the properties of the steel. But, detecting of boron using X-ray or ion-beam is not easy because boron is very light atom than iron. However neutron gives the clear image of boron distribution from the particle tracking autoradiography (PTA) method. The PTA method of boron uses the phenomenon that boron irradiated by neutron emits Liion and alpha particle. Boron distribution can be obtained by observing the traces of the emitted Li-ion and alpha particle. At HANARO, the study for observing of boron distribution has been performed several years ago. Recently, the experimental techniques were improved for the reactor power of 30 MW. In this paper, improved experimental techniques were described and some results for boron added low-carbon steel plate were introduced.

  13. Composite boron nitride neutron detectors

    Science.gov (United States)

    Roth, M.; Mojaev, E.; Khakhan, O.; Fleider, A.; Dul`kin, E.; Schieber, M.

    2014-09-01

    Single phase polycrystalline hexagonal boron nitride (BN) or mixed with boron carbide (BxC) embedded in an insulating polymeric matrix acting as a binder and forming a composite material as well as pure submicron size polycrystalline BN has been tested as a thermal neutron converter in a multilayer thermal neutron detector design. Metal sheet electrodes were covered with 20-50 μm thick layers of composite materials and assembled in a multi-layer sandwich configuration. High voltage was applied to the metal electrodes to create an interspacing electric field. The spacing volume could be filled with air, nitrogen or argon. Thermal neutrons were captured in converter layers due to the presence of the 10B isotope. The resulting nuclear reaction produced α-particles and 7Li ions which ionized the gas in the spacing volume. Electron-ion pairs were collected by the field to create an electrical signal proportional to the intensity of the neutron source. The detection efficiency of the multilayer neutron detectors is found to increase with the number of active converter layers. Pixel structures of such neutron detectors necessary for imaging applications and incorporation of internal moderator materials for field measurements of fast neutron flux intensities are discussed as well.

  14. Boron-Loaded Silicone Rubber Scintillators

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-05-12

    Silicone rubber received attention as an alternative to polyvinyltoluene in applications in which the scintillator is exposed to high doses because of the increased resistance of the rubber to the formation of blue-absorbing color centers. Work by Bowen, et al., and Harmon, et al., demonstrated their properties under gamma/x-ray irradiation, and Bell, et al. have shown their response to thermal neutrons. This last work, however, provided an example of a silicone in which both the boron and the scintillator were contained in the rubber as solutes, a formulation which led to the precipitation of solids and sublimation of the boron component. In the present work we describe a scintillator in which the boron is chemically bonded to the siloxane and so avoids the problem of precipitation and loss of boron to sublimation. Material containing up to 18% boron, by weight, was prepared, mounted on photomultipliers, and exposed to both neutron and gamma fluxes. Pulse height spectra showing the neutron and photon response were obtained, and although the light output was found to be much poorer than from samples in which boron was dissolved, the higher boron concentrations enabled essentially 100% neutron absorption in only a few millimeters' thickness of rubber.

  15. Density separation of boron particles. Final report

    International Nuclear Information System (INIS)

    Smith, R.M.

    1980-04-01

    A density distribution much broader than expected was observed in lots of natural boron powder supplied by two different sources. The material in both lots was found to have a rhombohedral crystal structure, and the only other parameters which seemed to account for such a distribution were impurities within the crystal structure and varying isotopic ratios. A separation technique was established to isolate boron particles in narrow densty ranges. The isolated fractions were subsequently analyzed for B 10 and total boron content in an effort to determine whether selective isotopic enrichment and nonhomogeneous impurity distribution were the causes for the broad density distribution of the boron powders. It was found that although the B 10 content remained nearly constant around 18%, the total boron content varied from 37.5 to 98.7%. One of the lots also was found to contain an apparently high level of alpha rhombohedral boron which broadened the density distribution considerably. During this work, a capability for removing boron particles containing gross amounts of impurities and, thereby, improving the overall purity of the remaining material was developed. In addition, the separation technique used in this study apparently isolated particles with alpha and beta rhombohedral crystal structures, although the only supporting evidence is density data

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

    International Nuclear Information System (INIS)

    Kitaoka, Y.

    1991-07-01

    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)

  17. Electrical and thermal conductivities of the graphene, boron nitride and silicon boron honeycomb monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Mousavi, Hamze, E-mail: hamze.mousavi@gmail.com [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of); Khodadadi, Jabbar [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of); Moradi Kurdestany, Jamshid [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65201 (United States); Yarmohammadi, Zahra [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of)

    2016-11-25

    Density of states, electrical and thermal conductivities of electrons in graphene, boron nitride and silicon boron single sheets are studied within the tight-binding Hamiltonian model and Green's function formalism, based on the linear response theory. The results show that while boron nitride keeps significantly the lowest amounts overall with an interval of zero value in low temperatures, due to its insulating nature, graphene exhibits the most electrical and thermal conductivities, slightly higher than silicon boron except for low temperature region where the latter surpasses, owing to its metallic character. This work might make ideas for creating new electronic devices based on honeycomb nanostructures. - Highlights: • Electronic properties of graphene, silicon boron, and boron nitride planes are compared. • Tight-binding Hamiltonian model and Green's function formalism are implemented. • This work might make ideas for creating new electronic devices based on honeycomb nanostructures.

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

    International Nuclear Information System (INIS)

    Crossley, D.; Wood, A.J.; McInnes, C.A.J.; Jones, I.G.

    1978-09-01

    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 300 0 C. 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 1050 0 C 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)

  19. Quantitative boron detection by neutron transmission method

    International Nuclear Information System (INIS)

    Okka, M.; Genceli, M.; Eren, E.; Bayulken, A.

    2008-01-01

    //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)

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

    Energy Technology Data Exchange (ETDEWEB)

    Keru, Godfrey; Ndungu, Patrick G.; Nyamori, Vincent O., E-mail: nyamori@ukzn.ac.za

    2015-03-01

    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.

  1. Boron Isotope Fractionation in Bell Pepper

    OpenAIRE

    Geilert, Sonja; Vogl, Jochen; Rosner, Martin; Voerkelius, Susanne; Eichert, Thomas

    2015-01-01

    Various plant compartments of a single bell pepper plant were studied to verify the variability of boron isotope composition in plants and to identify possible intra-plant isotope fractionation. Boron mass fractions varied from 9.8 mg/kg in the fruits to 70.0 mg/kg in the leaves. Boron (B) isotope ratios reported as δ11B ranged from -11.0‰ to +16.0‰ (U ≤ 1.9‰, k=2) and showed a distinct trend to heavier δ11B values the higher the plant compartments were located in the plant. A fractionatio...

  2. Study on plasma sprayed boron carbide coating

    Science.gov (United States)

    Zeng, Yi; Lee, Soo W.; Ding, Chuanxian

    2002-03-01

    The microstructure, phase composition, and mechanical properties of boron carbide coatings formed by atmospheric plasma spraying (APS) are studied in the present work. The boron carbide coating with high microhardness and low porosity could be produced by APS. The decomposition of boron carbide powder during the plasma spray process would result in the formation of the BxC phase and an increase of the carbon phase, which is confirmed by transmission electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction results.

  3. Coping with naturally high levels of soil salinity and boron in the westside of central California

    Science.gov (United States)

    In the Westside of central California, over 200,000 ha exhibit naturally high levels of salinity and boron (B). The Coast Ranges of the west central California evolved from complex folding and faulting of sedimentary and igneous rocks of Mesozoic and Tertiary age. Cretaceous and Tertiary marine sedi...

  4. Comparative study of the interfaces of graphene and hexagonal boron nitride with silver

    DEFF Research Database (Denmark)

    Garnica, Manuela; Schwarz, Martin; Ducke, Jacob

    2016-01-01

    Silver opens up interesting perspectives in the fabrication of complex systems based on heteroepitaxial layers after the growth of a silicene layer on its (111) face has been proposed. In this work we explore different synthesis methods of hexagonal boron nitride (h-BN) and graphene sheets...

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

    Science.gov (United States)

    Edward Raja, Chellaiah; Omine, Kiyoshi

    2013-08-01

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

  6. Assessing cytotoxicity of boron nitride nanotubes: Interference with the MTT assay

    Energy Technology Data Exchange (ETDEWEB)

    Ciofani, Gianni, E-mail: g.ciofani@sssup.it [Italian Institute of Technology, Smart Materials Lab, Center of MicroBioRobotics at Scuola Superiore Sant' Anna, Viale Rinaldo Piaggio, 34, 56025 Pontedera (Pisa) (Italy); Danti, Serena; D' Alessandro, Delfo [Otology-Cochlear Implants, Cisanello Hospital, Via Paradisa 2, 56124 Pisa (Italy); Moscato, Stefania [Department of Human Morphology and Applied Biology, University of Pisa, Via Roma 55, 56126 Pisa (Italy); Menciassi, Arianna [Italian Institute of Technology, Smart Materials Lab, Center of MicroBioRobotics at Scuola Superiore Sant' Anna, Viale Rinaldo Piaggio, 34, 56025 Pontedera (Pisa) (Italy); CRIM Lab, Scuola Superiore Sant' Anna, Viale Rinaldo Piaggio, 34, 56025 Pontedera (Pisa) (Italy)

    2010-04-02

    Thanks to a non-covalent wrapping with glycol-chitosan, highly biocompatible and highly concentrated dispersions of boron nitride nanotubes were obtained and tested on human neuroblastoma cells. A systematic investigation of the cytotoxicity of these nanovectors with several complementary qualitative and quantitative assays allowed a strong interference with the MTT metabolic assay to be highlighted, similar to a phenomenon already observed for carbon nanotubes, that would wrongly suggest toxicity of boron nitride nanotubes. These results confirm the high complexity of these new nanomaterials, and the needing of extensive investigations on their exciting potential applications in the biomedical field.

  7. Functionalization of regenerated cellulose membrane via surface initiated atom transfer radical polymerization for boron removal from aqueous solution.

    Science.gov (United States)

    Wei, Yu-Ting; Zheng, Yu-Ming; Chen, J Paul

    2011-05-17

    In this study, an adsorptive membrane was prepared for efficient boron removal. Poly(glycidyl methacrylate) was grafted on the surfaces of the regenerated cellulose (RC) membrane via surface-initiated atom transfer radical polymerization, and N-methylglucamine was used to further react with epoxide rings to introduce polyhydroxyl functional groups, which served as the major binding sites for boron. The pristine and modified membranes were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), dynamic water contact angle measurement, and scanning electron microscopy. It was shown that the designed functional groups were successfully grafted onto the RC membrane, and surface modification contributed to higher boron binding capability. The optimal pH range for boron adsorption was 4-8. Under a neutral pH condition, the maximum adsorption capacity of the modified membrane was determined to be 0.75 mmol/g, which was comparable with those of commercial resins. Studies of electrolyte influence indicated the formation of inner-sphere surface complexes on the membrane surface. The ATR-FTIR and XPS analyses showed that secondary alcohol and tertiary amine groups were mainly involved in boron adsorption, and tetrahedral boron complexes were found on the membrane surface.

  8. Determination of boron in Jabroc wood used as a shielding material in nuclear reactors

    International Nuclear Information System (INIS)

    Kamble, Granthali S.; Manisha, V.; Venkatesh, K.

    2015-01-01

    Jabroc are non-impregnated, densified wood laminates developed commercially for a wide range of industrial applications. Jabroc can be used with other neutron shielding materials such as Lead to form complex shielding structures. Its relative light weight and cleanliness in handling are additional features that make it a suitable candidate for the standard design of neutron shielding equipment. Jabroc can also be impregnated with Boron up to a maximum of 4% to be used in areas where Gamma radiation produced on Neutron capture reaches unacceptable dose rates. Boron impregnated Jabroc wood finds application in TAPS 3 and 4 as a shielding material for the Ion Chambers and the Horizontal Flux Units (HFU). The shielding property of this material is optimized by incorporating requisite amount of boron in wood. Boron content in this material has to be determined accurately prior to its use in the nuclear reactors. In this work a method was standardized to determine boron in Jabroc wood samples to check for conformance to specifications. The wood sample flakes were wetted with saturated barium hydroxide solution and dries under IR. The sample was ashed in a muffle furnace at 600℃ for 2 h

  9. Study of boron distribution in silicon structure by side long section technique

    International Nuclear Information System (INIS)

    Kadirova, M.; Zhumaev, N.; Simakhin, Yu.F.; Usmanova, M.M.

    1997-01-01

    To study deep boron diffusion in the complex silicon structures, consisting of interchange boron doping layers of mono- and polycrystalline silicon, separated by oxide films a technique of side long section by using Solid State Nuclear Track Detector (SSNTD) has been elaborated. The boron distribution technique is based on the detection of alpha-particles from the 10 B(n,α) 7 Li reaction with cellulose nitrate film. The etched α-track registering cellulose nitrite film show the structure image magnified 1/sinφ fold. Boron concentration defined by density of the etched pits appearing on the film surface. An optical microscope analysis of the sample track-mapping image is realised by examination with closely spaced (Δl < Δx/sinφ) and largely spaced (Δl ≥ Δx/sinφ) movements. For analysis of both experimental data the computer application programs have been developed. An universal algorithm for determination of the boron profiles has been created to take into account influence of a deeper layers on a total measurement of track density when Δl < Δx/sinφ. (author)

  10. Boron carbide: hydrocode simulation of plate-impact experiments with an improved failure model

    Science.gov (United States)

    Dyachkov, Sergey; Parshikov, Anatoly; Zhakhovsky, Vasily

    2017-06-01

    Unique strength properties of boron carbide make it useful for numerous applications. However, shock compression accompanied by high strains rates involves material into the process of failure what significantly reduces its strength. In this research we compare simulation results for two sets of plate-impact experiments where samples were manufactured using different technology. Simulations are performed using our 3D SPH hydrocode and the improved Johnson-Holmquist failure model. Complex wave profiles obtained via VISAR are properly reproduced in our modeling. However, it was found that the failed boron carbide strength have a strong effect on the wave profiles and should be different for the each set of experiments. Moreover, heterogeneous distribution of failed boron carbide is shown to affect wave propagation to the rear surface of sample what results in spatial velocity profile variations obtained via line-VISAR system.

  11. Trichlorosilane and silicon tetrachloride sample preparation for determination of boron, phosphorus and arsenic microelements

    International Nuclear Information System (INIS)

    Stolyarova, I.V.; Orlova, V.A.

    1995-01-01

    The conditions of sample preparation ensuring virtually complete elimination of boron, phosphorus, and arsenic losses are elaborated. Analysis procedures are proposed that involve hydrolysis in an autoclave for exothermic reactions and/or in an open reaction reservoir on frozen twice-distilled water with complexing-agent and oxidant solutionsd applied layer-by-layer, with the possible subsequent atomic-emission, extraction-spectrophotometric, or extraction-colorimetric determination of boron, phosphorus, and arsenic. The procedures improve the accuracy and precision of the results and reduce the duration of chemical preparation due to the quantitative preconcentration of boron, phosphorus, and arsenic; they almost completely eliminate the possibility of the formation of volatile fluoride forms of these elements. 11 refs.; 3 tabs

  12. Boron Doped Graphene 3-Dimensi untuk Superkapasitor Kapasitas Tinggi

    Directory of Open Access Journals (Sweden)

    Nurlia Pramita Sari

    2017-08-01

    Full Text Available Chemical doping is an effective approach to improve the property of carbon material. In this study boron doped graphene with 3D structure used as the electrode was investigated. Boron doped graphene was prepared through freeze-dried process followed by pyrolysis of graphene oxide (GO with three types of chemical substances; boron oxide, boric acid, and boron powder in an argon and hydrogen atmosphere at 1000 C for 3 hours. The difference of chemical composition generated a different percentage of boron bond with GO. The results shows that the highest electrochemical performance was found in graphene samples with the addition of boric acid (BA 86 F/g, followed by boron oxide (BO 59.2 F/g, and boron powder (BP 2 F/g. It can be caused by boron concentration bound with graphene. The higher concentration of boron could be increased the electrochemical performance due to better of ion movement.

  13. Breaking the icosahedra in boron carbide.

    Science.gov (United States)

    Xie, Kelvin Y; An, Qi; Sato, Takanori; Breen, Andrew J; Ringer, Simon P; Goddard, William A; Cairney, Julie M; Hemker, Kevin J

    2016-10-25

    Findings of laser-assisted atom probe tomography experiments on boron carbide elucidate an approach for characterizing the atomic structure and interatomic bonding of molecules associated with extraordinary structural stability. The discovery of crystallographic planes in these boron carbide datasets substantiates that crystallinity is maintained to the point of field evaporation, and characterization of individual ionization events gives unexpected evidence of the destruction of individual icosahedra. Statistical analyses of the ions created during the field evaporation process have been used to deduce relative atomic bond strengths and show that the icosahedra in boron carbide are not as stable as anticipated. Combined with quantum mechanics simulations, this result provides insight into the structural instability and amorphization of boron carbide. The temporal, spatial, and compositional information provided by atom probe tomography makes it a unique platform for elucidating the relative stability and interactions of primary building blocks in hierarchically crystalline materials.

  14. Boron adsorption on hematite and clinoptilolite

    International Nuclear Information System (INIS)

    Gainer, G.M.

    1993-01-01

    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

  15. Determination of boron in amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Grazhulene, S.S.; Grossman, O.V.; Kuntscher, K.K.; Malygina, L.I.; Muller, E.N.; Telegin, G.F.

    1985-10-01

    In the determination of boron in amorphous alloys containingFe, Co, B, Si, Ni, and P having unusal magnetic and electrical properties, precise analysis and rapid analysis are necessary. To improve the metrological properties of the existing procedure, to find a rapid determination of boron in amorphous alloys, and to verify the accuracy of the results, in the present work the optimization of the photometric determination after extraction of the BF/sup -//sub 4/ ion pair with methylene blue has been studied, and a boron determination by flame photometry using selective methylation has been developed. The determination of boron by the flame photometric and spectrophotometric methods is shown. When a highly precise determination is needed, the spectrophotometric procedure can be used. This procedure is distinguished by its labor intensity and duration. When the need for reproducibility is less severe, the rapid flame photometric procedure is best.

  16. Boron precipitates in ion implanted silicon

    International Nuclear Information System (INIS)

    Wu, W.K.; Washburn, J.

    1975-03-01

    Long rod-like defects are observed in ion implanted silicon when boron is present either as a prior dopant addition or as the implanted species. Results of recent work indicates that these defects have the characteristics of narrow extrinsic dipoles or elongated dislocation loops and that there are two different types along each of the six (110) directions. An annealing kinetics method has been used to identify the nature of these defects formed during post-implantation annealing in boron ion (100 keV) implanted silicon irradiated at room temperature to a dose of 2 x 10 14 /cm 2 . It is concluded that at least two different kinds of rod-like defects exist in boron ion implanted silicon. From the activation energy for shrinkage, it is also concluded that one type (anti A) is composed largely of boron atoms. (U.S.)

  17. Spectromicroscopy in Boron Neutron Capture Therapy Research

    Science.gov (United States)

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

    1998-03-01

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

  18. Behaviour of boron in Mandovi estuary (Goa)

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; Anand, S.P.

    and alkalinity gave positive correlations with a linear variation. Though the overall behavioural pattern of boron indicated non-conservative nature, it showed a quasi-conservative character during premonsoon and a non-conservative during rest of the seasons...

  19. Boron

    Science.gov (United States)

    ... feeding women over 19 years of age. For adolescents 14 to 18 years of age and pregnant or breast-feeding women 14 to 18 years of age, the ... be expected, is 17 mg per day for adolescents 14 to 18 years of age and pregnant or breast-feeding women 14 to 18 years of age. For ...

  20. Abrasive slurry composition for machining boron carbide

    Science.gov (United States)

    Duran, Edward L.

    1985-01-01

    An abrasive slurry particularly suited for use in drilling or machining boron carbide consists essentially of a suspension of boron carbide and/or silicon carbide grit in a carrier solution consisting essentially of a dilute solution of alkylaryl polyether alcohol in octyl alcohol. The alkylaryl polyether alcohol functions as a wetting agent which improves the capacity of the octyl alcohol for carrying the grit in suspension, yet without substantially increasing the viscosity of the carrier solution.

  1. Boron-rich oligomers for BNCT

    International Nuclear Information System (INIS)

    Gula, M.; Perleberg, O.; Gabel, D.

    2000-01-01

    The synthesis of two BSH derivatives is described, which can be used for oligomerization in DNA-synthesizers. Synthesis pathways lead to final products in five and six steps, respectively. Because of chirality interesting results were expected. NMR-measurements confirm this expectation. Possible oligomers with high concentrations of boron can be attached to biomolecules. These oligomers can be explored with several imaging methods (EELS, PEM) to determine the lower detection limit of boron with these methods. (author)

  2. Discharge cleaning on TFTR after boronization

    International Nuclear Information System (INIS)

    Mueller, D.; Dylla, H.F.; LaMarche, P.H.; Bell, M.G.; Blanchard, W.; Bush, C.E.; Gentile, C.; Hawryluk, R.J.; HIll, K.W.; Janos, A.C.; Jobes, F.C; Owens, D.K.; Pearson, G.; Schivell, J.; Ulrickson, M.A.; Vannoy, C.; Wong, K.L.

    1991-05-01

    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 10 5 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

  3. 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.

  4. Homologation of boronic esters with organolithium compounds: a computational assessment of mechanism.

    Science.gov (United States)

    Essafi, Stéphanie; Tomasi, Simone; Aggarwal, Varinder K; Harvey, Jeremy N

    2014-12-19

    Ab initio calculations are reported for the reaction of methyl boronic ester with organolithium reagents with α-leaving groups. The best calculations rely on density functional theory prediction of structures and coupled-cluster theory calculation of accurate potential energies. The results provide strong confirmation of the feasibility of a two-step mechanism with rapid initial formation of a boron-ate complex followed by slower migration of methyl from boron to carbon with loss of the leaving group. The calculated free energy of activation is consistent with observed kinetic behavior, and the calculations provide a framework for exploring substituent and other effects on reactivity. Obtaining reasonable agreement with experiment in this way is not trivial and requires careful treatment of level of theory (density functional theory calculations tend to yield inaccurate results), of conformational complexity, especially for the ate complexes, and of the nature of the microscopic model of reactants and solvent. The methodological challenges and possible pitfalls, many of which are relevant more broadly to computational modeling of organic reaction mechanisms, are discussed in detail.

  5. Real-time boronization in PBX-M using erosion of solid boronized targets

    International Nuclear Information System (INIS)

    Kugel, H.W.; Timberlake, J.; Bell, R.

    1994-01-01

    Thirty one real-time boronizations were applied to PBX-M using the plasma ablation of solid target probes. More than 17 g of boron was deposited in PBX-M using this technique. The probes were positioned at the edge plasma to optimize ablation and minimize spallation. Auger depth profile analysis of poloidal and toroidal deposition sample coupon arrays indicate that boron was transported by the plasma around the torus and deep into the divertors. During discharges with continuous real-time boronization, low-Z and high-Z impurities decreased rapidly as plasma surfaces were covered during the first 20--30 discharges. After boronization, a short-term improvement in plasma conditions persisted prior to significant boron erosion from plasma surfaces, and a longer term, but less significant, improvement persisted as boron farther from the edge continued gettering. Real-time solid target boronization has been found to be very effective for accelerating conditioning to new regimes and maintaining high performance plasma conditions

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

    Science.gov (United States)

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

  7. 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.)

  8. 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.

  9. Enhanced diffusion of boron by oxygen precipitation in heavily boron-doped silicon

    Science.gov (United States)

    Torigoe, Kazuhisa; Ono, Toshiaki

    2017-06-01

    The enhanced diffusion of boron has been investigated by analyzing out-diffusion profiles in the vicinity of the interface between a lightly boron-doped silicon epitaxial layer and a heavily boron-doped silicon substrate with a resistivity of 8.2 mΩ cm and an oxide precipitate (O.P.) density of 108-1010 cm-3. It is found that the boron diffusion during annealing at 850-1000 °C is enhanced with the increase of the oxide precipitate density. On the basis of a model for boron diffusion mediated by silicon self-interstitials, we reveal that the enhanced diffusion is attributed to self-interstitials supersaturated as a result of the emission from oxide precipitates and the absorption by punched-out dislocations. In addition, the temperature dependence of the fraction of the self-interstitial emission obtained analyzing the diffusion enhancement well explains the morphology changes of oxide precipitates reported in literature.

  10. Boron-containing thioureas for neutron capture therapy

    International Nuclear Information System (INIS)

    Ketz, H.

    1993-01-01

    Melanin is produced in large amounts in malignant melanotic melanomas. Because thiourea compounds are covalently incorporated into melanin during its biosynthesis, the preparation of boronated thiourea-derivatives is of particular interest for the BNCT (Boron Neutron Capture Therapy). Accumulation of boron in tumors by means of boronated thiourea-derivatives may therefore provide levels of 10 B which are useful for BNCT. In BNCT the tumor containing the boron compound is irradiated with epithermal neutrons to generate He- and Li-nuclei from the 10 B which can then destroy the tumor cells. Because of the short ranges of these particles (approximately one cell diameter) the damage will be almost exclusively confined to the tumor leaving normal tissue unharmed. High accumulation of 2-mercapto-1-methylimidazole (methimazole) in melanotic melanomas has been described in the literature. Boronated derivatives of methimazole were therefore synthesized. Boron was in the form of a boronic acid, a nido-carbonate and a mercaptoundeca hydro-closo-dodecaborate (BSH). The synthesis of the boron cluster derivatives of methimazole (nido-carborate- and BSH-derivatives) with 9 resp. 12 boron atoms in the molecule were expected to achieve higher concentrations of boron in the tumor than in the case of the boronic acid compound with its single boron atom. (orig.) [de

  11. Atmospheric contribution to boron enrichment in aboveground wheat tissues.

    Science.gov (United States)

    Wang, Cheng; Ji, Junfeng; Chen, Mindong; Zhong, Cong; Yang, Zhongfang; Browne, Patrick

    2017-05-01

    Boron is an essential trace element for all organisms and has both beneficial and harmful biological functions. A particular amount of boron is discharged into the environment every year because of industrial activities; however, the effects of environmental boron emissions on boron accumulation in cereals has not yet been estimated. The present study characterized the accumulation of boron in wheat under different ecological conditions in the Yangtze River Delta (YRD) area. This study aimed to estimate the effects of atmospheric boron that is associated with industrial activities on boron accumulation in wheat. The results showed that the concentrations of boron in aboveground wheat tissues from the highly industrialized region were significantly higher than those from the agriculture-dominated region, even though there was no significant difference in boron content in soils. Using the model based on the translocation coefficients of boron in the soil-wheat system, we estimated that the contribution of atmosphere to boron accumulation in wheat straw in the highly industrialized region exceeded that in the agriculture-dominated region by 36%. In addition, from the environmental implication of the model, it was estimated that the development of boron-utilizing industries had elevated the concentration of boron in aboveground wheat tissues by 28-53%. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. 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

  13. Removal of boron from aqueous solution using cryptocrystalline magnesite

    CSIR Research Space (South Africa)

    Masindi, Vhahangwele

    2016-05-01

    Full Text Available The present study aimed to evaluate the efficiency of using cryptocrystalline magnesite to remove boron ions from aqueous systems. Batch experimental protocols were used to evaluate the adsorption capacity of magnesite for boron. Parameters...

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

    International Nuclear Information System (INIS)

    Kuehl, D.K.

    1975-01-01

    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.)

  15. Method of manufacture of atomically thin boron nitride

    Science.gov (United States)

    Zettl, Alexander K

    2013-08-06

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

  16. Spectrophotometric determination of boron by solvent extraction with hydrobenzoin and crystal violet

    International Nuclear Information System (INIS)

    Sato, Shigeya; Uchikawa, Sumio

    1982-01-01

    A highly sensitive and simple method for the spectrophotometric determination of boron was developed. Boron was found to react with hydrobenzoin in weak alkaline medium to form a complex anion extractable into benzene with crystal violet, and the measurement of the absorbance of crystal violet in the extract at 600 nm enabled the determination of boron indirectly. The recommended procedure is as follows: Take an aliquot of the boron solution (2.0 x 10 - 4 mol l - 1 ) into a 10-ml test tube. Add 1 ml of carbonate buffer solution (pH 9.4) and 0.25 ml of crystal violet solution (1.0 x 10 - 2 mol l - 1 ), and dilute the mixed solution to 4 ml with deionized water. Shake the solution with 4 ml of benzene solution containing hydrobenzoin (2.0 x 10 - 2 mol l - 1 ) for 2 min. Measure the absorbance of the organic phase at 600 nm using a 10-mm glass cell against benzene. The calibration curve obeyed Beer's law on the concentration range from 2.5 x 10 - 6 mol l - 1 to 2.5 x 10 - 5 mol l - 1 of boron, and the apparent molar absorptivity was 3.0 x 10 4 l mol - 1 cm - 1 at 20 0 C. It was found that many kinds of co-existing ions interfered with the determination. However, this method was applicable to the determination of boron in sea water when chloride ion and cations such as Ca(II) and Mg(II) were previously eliminated by treating the sample solution with Ag 2 O and cation exchanger resin. The proposed method is a very simple and rapid one, because this method does not require apparatus other than common laboratories and the evaporation to dryness of sample or removal of the excess of reagent. (author)

  17. The radiation biology of Boron Neutron Capture Therapy

    International Nuclear Information System (INIS)

    Coderre, J.A.

    2003-01-01

    Boron Neutron Capture Therapy (BNCT) produces a complex mixture of high and low-LET radiations in tissue. Using data on the biological effectiveness of these various dose components, derived primarily in small animals irradiated with thermal neutrons, it has been possible to express clinical BNCT doses in photon-equivalent units. The accuracy of these calculated doses in normal tissue and tumor will be reviewed. Clinical trials are underway at a number of centers. There are differences in the neutron beams at these centers, and differences in the details of the clinical protocols. Ideally, data from all centers using similar boron compounds and treatment protocols should be compared and combined, if appropriate, in a multi-institutional study in order to strengthen statistical analysis. An international dosimetry exchange is underway that will allow the physical doses from the various treatment centers to be quantitatively compared. As a first step towards the comparison of the clinical data, the normal brain tolerance data from the patients treated in the initial Brookhaven National Laboratory and the Harvard/MIT BNCT clinical trials have been compared. The data provide a good estimate of the normal brain tolerance for a somnolence syndrome endpoint, and provide guidance for setting normal brain tolerance limits in ongoing and future clinical trials. Escalation of the dose in BNCT can be accomplished by increasing the amount of the boron compound administered, increasing the duration of the neutron exposure, or both. The dose escalations that have been carried out to date at the various treatment centers will be compared and contrasted. Possible future clinical trials using BNCT in combination with other modalities will be discussed

  18. 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.

  19. Impact scenarios in boron carbide: A computational study

    OpenAIRE

    Bell, R. G.; Sugden, I. J.; Plant, D. F.

    2016-01-01

    The effect of radiative impacts on the structure of boron carbide has been studied by both classical and ab initio simulations. As a part of this study, a new forcefield was developed for use in studying boron carbide materials. Impact scenarios in boron carbide were simulated in order to investigate the exceptional resistance of this material, and other icosahedral boron solids, to high-energy impact events. It was observed that interstitial defects created by radiative impacts are likely to...

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

    International Nuclear Information System (INIS)

    Aldabergenov, M.K.; Balakaeva, T.G.

    1995-01-01

    A technology is developed for producing 'Phosphobor' fertilizer based on the rock phosphate weal (17-18% P 2 O 5 ) 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

  1. Determination of free carbon content in boron carbide ceramic powders

    International Nuclear Information System (INIS)

    Castro, A.R.M. de; Lima, N.B. de; Paschoal, J.O.A.

    1990-01-01

    Boron carbide is a ceramic material of technological importance due to its hardness and high chemical and thermal stabilities. Free carbon is always found as a process dependent impurity in boron carbide. The development of procedures for its detection is required because its presence leads to a degradation of the boron carbide properties. In this work, several procedures for determining free carbon content in boron carbide specimens are reported and discussed for comparison purposes. (author) [pt

  2. 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

  3. Adsorption Isotherms of Boron in Soil: the effects of Sodium Adsorption Ratio (SAR, pH and Ionic strength

    Directory of Open Access Journals (Sweden)

    Mojtaba Moqbeli

    2017-03-01

    adsorption of boron, the effect of ionic strength on boron adsorption can be partly dependent on it. Due to the high variability of soil minerals and the differences in their chemical properties, interpretation of the effect of ionic strength on adsorption of boron is not easy, but we can say that it is the sum of the effects of the above-mentioned factors. The positive effect of ionic strength on boron adsorption may suggest that the formation of inner sphere complex is the dominant mechanism for boron adsorption.

  4. Boron-Loaded Silicone Rubber Scintillators

    CERN Document Server

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

    2003-01-01

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

  5. Hot ductility behavior of boron microalloyed steels

    International Nuclear Information System (INIS)

    Lopez-Chipres, E.; Mejia, I.; Maldonado, C.; Bedolla-Jacuinde, A.; Cabrera, J.M.

    2007-01-01

    The current study analyses the influence of boron contents (between 29 and 105 ppm) on the hot ductility of boron microalloyed steels. For this purpose, hot tensile tests were carried out at different temperatures (700, 800, 900 and 1000 deg. C) at a constant true strain rate of 0.001 s -1 . In general, results revealed an improvement of the hot ductility of steels at increasing boron content. At 700, 900 and 1000 deg. C the ductility is higher than at 800 deg. C, where boron microalloyed steels exhibit a region of ductility loss (trough region). Likewise, dynamic recrystallization only occurred at 900 and 1000 deg. C. The fracture surfaces of the tested steels at temperatures giving the high temperature ductility regime show that the fracture mode is a result of ductile failure, whereas it is ductile-brittle failure in the trough region. Results are discussed in terms of dynamic recrystallization and boron segregation towards austenite grain boundaries, which may retard the formation of pro-eutectoid ferrite and increase grain boundary cohesion

  6. Mechanisms of boron removal from hydraulic fracturing wastewater by aluminum electrocoagulation.

    Science.gov (United States)

    Sari, Mutiara Ayu; Chellam, Shankararaman

    2015-11-15

    Boron uptake from highly saline hydraulic fracturing wastewater by freshly precipitated amorphous Al(OH)3 precipitates is due to ligand exchange and complexation with surface hydroxyl groups. Consequently, aluminum electrocoagulation can be a feasible approach to remove boron from flowback/produced water. Actual hydraulic fracturing wastewater containing ∼120mg/L boron from the Eagle Ford shale play was employed. Electrocoagulation was performed over a range of aluminum dosages (0-1350mg/L), pH 6.4 and 8, and high current densities (20-80mA/cm(2)) using a cylindrical aluminum anode encompassed by a porous cylindrical 316-stainless steel cathode. Direct measurements of boron uptake along with its chemical state and coordination were made using Attenuated Total Reflection-Fourier Transform Infrared spectroscopy (ATR-FTIR) and X-Ray Photoelectron Spectroscopy. Boron removal increased monotonically with aluminum dosage and was higher at pH 8, but remained relatively constant at ⩾20mA/cm(2). Chloride ions induced anodic pitting and super-Faradaic (131% efficiency) aluminum dissolution and their electrooxidation produced free chlorine. ATR-FTIR suggested outer-sphere and inner-sphere complexation of trigonal B(OH)3 with Al(OH)3, which was confirmed by the BO bond shifting toward lower binding energies in XPS. Severe AlO interferences precluded evidence for tetrahedral B(OH)4(-) complexation. No evidence for co-precipitation was obtained. Copyright © 2015 Elsevier Inc. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    N. F. Nevar

    2010-01-01

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

  8. Simulating the effect of boron doping in superconducting carbon

    Science.gov (United States)

    Sakai, Yuki; Chelikowsky, James R.; Cohen, Marvin L.

    2018-02-01

    We examine the effect of boron doping in superconducting forms of amorphous carbon. By judiciously optimizing boron substitutional sites in simulated amorphous carbon, we predict a superconducting transition temperature near 37 K at 14% boron concentration. Our findings have direct implications for understanding the recently discovered high-Tc superconductivity in Q-carbon.

  9. Effects of dietary boron on performance, egg production, egg quality ...

    African Journals Online (AJOL)

    engin

    Body weight was not affected by dietary boron supplementation at 16 and 40 weeks of age. ... and human nutrition. In bone metabolism, boron interacts with Ca, vitamin D and Mg (Chapin et al., 1998). In animals and plants, boron affects at least 26 enzymes involved in substrate metabolism, insulin release, oxidation and.

  10. Mesoscale Modeling of Dynamic Compression of Boron Carbide Polycrystals

    Science.gov (United States)

    2013-05-01

    occurs in ballistic impact, and accompanies amorphization in diamond anvil cell (DAC) experiments (Yan et al., 2009). Fracture in boron carbide ...Mesoscale Modeling of Dynamic Compression of Boron Carbide Polycrystals by J. D. Clayton ARL-RP-440 May 2013...Ground, MD 21005-5069 ARL-RP-440 May 2013 Mesoscale Modeling of Dynamic Compression of Boron Carbide Polycrystals J. D. Clayton

  11. 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.

  12. Screening of Wheat Genotypes for Boron Efficiency in Bangladesh

    Science.gov (United States)

    A number of Bangladeshi wheat genotypes (varieties and advanced lines) have been tested for boron efficiency through sand culture experiments over two years (2007-08 & 2008-09) against two Thai check varieties ‘Fang 60’ (boron efficient) and ‘SW41’ (boron inefficient). Performances of the genotypes ...

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

    Science.gov (United States)

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

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

    Science.gov (United States)

    Halverson, Danny C.; Landingham, Richard L.

    1988-01-01

    A chemical pretreatment method is used to produce boron carbide-, boron-, and boride-reactive metal composites by an infiltration process. The boron carbide or other starting constituents, in powder form, are immersed in various alcohols, or other chemical agents, to change the surface chemistry of the starting constituents. The chemically treated starting constituents are consolidated into a porous ceramic precursor which is then infiltrated by molten aluminum or other metal by heating to wetting conditions. Chemical treatment of the starting constituents allows infiltration to full density. The infiltrated precursor is further heat treated to produce a tailorable microstructure. The process at low cost produces composites with improved characteristics, including increased toughness, strength.

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

    International Nuclear Information System (INIS)

    Hodapp, T.R.; Jackson, G.L.; Phillips, J.; Holtrop, K.L.; Petersen, P.I.; Winter, J.

    1991-09-01

    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

  16. Accelerator-driven boron neutron capture therapy

    Science.gov (United States)

    Edgecock, Rob

    2014-05-01

    Boron Neutron Capture Therapy is a binary treatment for certain types of cancer. It works by loading the cancerous cells with a boron-10 carrying compound. This isotope has a large cross-section for thermal neutrons, the reaction producing a lithium nucleus and alpha particle that kill the cell in which they are produced. Recent studies of the boron carrier compound indicate that the uptake process works best in particularly aggressive cancers. Most studied is glioblastoma multiforme and a trial using a combination of BNCT and X-ray radiotherapy has shown an increase of nearly a factor of two in mean survival over the state of the art. However, the main technical problem with BNCT remains producing a sufficient flux of neutrons for a reasonable treatment duration in a hospital environment. This paper discusses this issue.

  17. The ternary system nickel-boron-silicon

    International Nuclear Information System (INIS)

    Lugscheider, E.; Reimann, H.; Knotek, O.

    1975-01-01

    The ternary system Nickel-Boron-Silicon was established at 850 0 C by means of X-ray diffraction, metallographic and micro-hardness examinations. The well known binary nickel borides and silicides resp. were confirmed. In the boron-silicon system two binary phases, SiBsub(4-x) with x approximately 0.7 and SiB 6 were found the latter in equilibrium with the β-rhombohedral boron. Confirming the two ternary silicon borides a greater homogeneity range was found for Ni 6 Si 2 B, the phase Nisub(4,6)Si 2 B published by Uraz and Rundqvist can better be described by the formula Nisub(4.29)Si 2 Bsub(1.43). In relation to further investigations we measured melting temperatures in ternary Ni-10 B-Si alloys by differential thermoanalysis. (author)

  18. Structure of Boron Carbide: Where's the Carbon?

    Science.gov (United States)

    Marx, David; Seidler, Gerald; Fister, Timothy; Nagle, Kenneth; Segre, Carlo

    2008-03-01

    Although the structure of the boron carbide series, B12-xCx with 0.06 x x-ray scattering (LERIX) spectrometer on the PNC-CAT beamline at the Advanced Photon Source at Argonne National Lab has enabled differentiation of the boron and carbon absorption edge data for the various crystallographic sites. The structure (R-3m) consists of twelve-atom icosahedra and three-atom chains. Boron carbide may have a maximum of three carbon atoms, which may be located on the two end of chain sites and in one of two inequivalent sites on the icosahedra. At least one carbon atom must be present in the structure for it to be stable. In this presentation, structural results from non-resonant x-ray scattering for seven samples, ranging from B4C to B10.1C will be presented.

  19. On the Mechanism of Boron Ignition

    Science.gov (United States)

    Keil, D. G.; Dreizin, E. L.; Felder, W.; Vicenzi, E. P.

    1997-01-01

    Boron filaments were electrically heated in air and argon/oxygen mixtures while their resistance, temperature, and radiation at the wavelengths of BO and BO2 bands were monitored. The filaments 'burned' in two distinct stages. Samples of the filaments were quenched at different times before and during the burning and analyzed using electron microscopy. The beginning of the first stage combustion characterized by a local resistance minimum, a sharp spike in boron oxide radiation emission, and a rapid rise in temperature, occurred at 1500 +/- 70 deg. C, independent of pre-heating history and oxygen content (540%) in the gas environment. The data suggest that a phase transition occurs in the filaments at this temperature that triggers stage one combustion. Significant amounts of oxygen were found inside quenched filaments. Large spherical voids formed in the boron filaments during their second stage combustion which is interpreted to indicate a crucial role for the gas dissolution processes in the combustion scenario.

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

    NARCIS (Netherlands)

    Mohammadi, V.; Nihtianov, S.

    2016-01-01

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

  1. Enhancement and retardation of thermal boron diffusion in silicon from atmospheric pressure chemical vapor deposited boron silicate glass film

    Science.gov (United States)

    Kurachi, Ikuo; Yoshioka, Kentaro

    2014-03-01

    Thermal boron diffusion into silicon from boron silicate glass (BSG) prepared by atmospheric pressure CVD (AP-CVD) has been investigated in terms of the BSG boron concentration dependence on diffusion mechanism for N-type solar cell applications. With thermal diffusion at 950 °C in N2 for 20 min, the sheet resistance of the boron-diffused layer decreases with BSG boron concentration up to approximately 4 × 1021 cm-3 at which a boron-rich layer (BRL) is formed at the surface. However, the resistance increases with BSG boron concentration when the BSG boron concentration is higher than 4 × 1021 cm-3. It is also confirmed that the diffusion depth decreases with increasing BSG boron concentration within this BSG concentration region. To clarify this mechanism, the BSG boron concentration dependence on boron diffusivity has also been studied. From extracted diffusivities, the anomalous diffusion can be explained by silicon interstitials formed owing to kick-out by diffused boron atoms and by silicon interstitial generation-degradation due to BRL formation.

  2. Chemical and mechanical analysis of boron-rich boron carbide processed via spark plasma sintering

    Science.gov (United States)

    Munhollon, Tyler Lee

    Boron carbide is a material of choice for many industrial and specialty applications due to the exceptional properties it exhibits such as high hardness, chemical inertness, low specific gravity, high neutron cross section and more. The combination of high hardness and low specific gravity makes it especially attractive for high pressure/high strain rate applications. However, boron carbide exhibits anomalous behavior when high pressures are applied. Impact pressures over the Hugoniot elastic limit result in catastrophic failure of the material. This failure has been linked to amorphization in cleavage planes and loss of shear strength. Atomistic modeling has suggested boron-rich boron carbide (B13C2) may be a better performing material than the commonly used B4C due to the elimination of amorphization and an increase in shear strength. Therefore, a clear experimental understanding of the factors that lead to the degradation of mechanical properties as well as the effects of chemistry changes in boron carbide is needed. For this reason, the goal of this thesis was to produce high purity boron carbide with varying stoichiometries for chemical and mechanical property characterization. Utilizing rapid carbothermal reduction and pressure assisted sintering, dense boron carbides with varying stoichiometries were produced. Microstructural characteristics such as impurity inclusions, porosity and grain size were controlled. The chemistry and common static mechanical properties that are of importance to superhard materials including elastic moduli, hardness and fracture toughness of the resulting boron-rich boron carbides were characterized. A series of six boron carbide samples were processed with varying amounts of amorphous boron (up to 45 wt. % amorphous boron). Samples with greater than 40 wt.% boron additions were shown to exhibit abnormal sintering behavior, making it difficult to characterize these samples. Near theoretical densities were achieved in samples with

  3. Boron removal by electrocoagulation and recovery.

    Science.gov (United States)

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

    2014-03-15

    This work investigated the removal of boron from wastewater and its recovery by electrocoagulation and hydrothermal mineralization methods respectively. The experimental design was developed using Box-Behnken Model. An initial study was performed based on four preselected variables (pH, current density, concentration and time) using synthetic wastewater. Response surface methodology (RSM) was used to evaluate the effect of process variables and their interaction on boron removal. The optimum conditions were obtained as pH 6.3, current density 17.4 mA/cm(2), and time 89 min. At these applied optimum conditions, 99.7% boron removal from an initial concentration of 10.4 mg/L was achieved. The process was effectively optimized by RSM with a desirability value of 1.0. The results showed that boron removal efficiency enhanced with increase in current density and treatment time. Removal efficiency also increased when pH was increased from 4 to 7 and subsequently decreased at pH 10. Adsorption kinetics study revealed that the reaction followed pseudo second order kinetic model; evidenced by high correlation and goodness of fit. Thermodynamics study showed that mechanism of boron adsorption was chemisorption and the reaction was endothermic in nature. Furthermore, the adsorption process was spontaneous as indicated by negative values of the adsorption free energy. Treatment of real produced water using electrocoagulation resulted in 98% boron removal. The hydrothermal mineralization study showed that borate minerals (Inyoite, Takadaite and Nifontovite) can be recovered as recyclable precipitate from electrocoagulation flocs of produced water. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. 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.

  5. 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.

  6. Designing your boron-charging system

    International Nuclear Information System (INIS)

    Miller, J.

    1979-01-01

    High-pressure positive-displacement pumps used in the boron-charging setups of pressurized-water (PWR) nuclear plants because of their inherently high efficiencies over a wide range of pressures and speeds are described. Hydrogen-saturated water containing 4-12% boric acid is fed to the pump from a volume-control tank under a gas blanket. Complicated piping and the pulsation difficulties associated with reciprocating pumps make hydrogen-saturated boron-charging systems a challenge to the designer. The article describes the unusual hydraulics of the systems to help assure a trouble-free design

  7. Unveiling polytype transformation assisted growth mechanism in boron carbide nanowires

    Science.gov (United States)

    Song, Ningning; Li, Xiaodong

    2018-01-01

    We demonstrate direct evidence that the lattice distortion, induced by boron carbide (BxCy) stoichiometry, assists the growth of boron carbide nanowires. The transformation between different polytypic boron carbide phases lowers the energy barrier for boron diffusion, promoting boron migration in the nanowire growth. An atomistic mass transport model has been established to explain such volume-diffusion-induced nanowire growth which cannot be explained by the conventional surface diffusion model alone. These findings significantly advance our understanding of nanowire growth processes and mass transport mechanisms and provide new guidelines for the design of nanowire-structured devices.

  8. Model for calculating the boron concentration in PWR type reactors

    International Nuclear Information System (INIS)

    Reis Martins Junior, L.L. dos; Vanni, E.A.

    1986-01-01

    A PWR boron concentration model has been developed for use with RETRAN code. The concentration model calculates the boron mass balance in the primary circuit as the injected boron mixes and is transported through the same circuit. RETRAN control blocks are used to calculate the boron concentration in fluid volumes during steady-state and transient conditions. The boron reactivity worth is obtained from the core concentration and used in RETRAN point kinetics model. A FSAR type analysis of a Steam Line Break Accident in Angra I plant was selected to test the model and the results obtained indicate a sucessfull performance. (Author) [pt

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

    Science.gov (United States)

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

    2016-09-01

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

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

    International Nuclear Information System (INIS)

    Camillo, M.A.P.; Tomac Junior, U.

    1990-01-01

    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 Na 2 10 B 12 H 11 SH 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) [pt

  11. A colorimetric determination of boron in biological sample for boron neutron capture therapy

    International Nuclear Information System (INIS)

    Camilo, M.A.P.; Tomac Junior, U.

    1989-01-01

    The boron neutron capture therapy (BNCT) has shown better prognosis in the treatment of gliomas and glioblastomas grade III and IV than other therapies. During the treatment of levels of Na 2 10 B 12 H 11 S H must be known in several compartments of the organism and with this purpose the method of colorimetric determination of boron using curcumin was established. This method is simples, reproducible and has adequate sensitivity for this control. (author). 7 refs, 3 figs, 1 tab

  12. Effect of low temperature oxidation (LTO) in reducing boron skin in boron spin on dopant diffused emitter

    Energy Technology Data Exchange (ETDEWEB)

    Singha, Bandana; Solanki, Chetan Singh [Department of Energy Science and Technology, Indian Institute of Technology, Bombay Mumbai-400076, Maharashtra (India)

    2016-05-06

    Formation of boron skin is an unavoidable phenomenon in p-type emitter formation with boron dopant source. The boron skin thickness is generally less than 100 nm and difficult to remove by chemical and physical means. Low temperature oxidation (LTO) used in this work is useful in removing boron skin thickness up to 30 nm and improves the emitter performance. The effective minority carrier lifetime gets improved by more than 30% after using LTO and leakage current of the emitter gets lowered by 100 times thereby showing the importance of low temperature oxidation in boron spin on dopant diffused emitters.

  13. Synthetic approach of norbadione A: new preparation of alcohols from sulfones and boron compounds

    International Nuclear Information System (INIS)

    Billaud, C.

    2005-12-01

    The synthetic approach of norbadione A, a pigment from mushrooms related to pulvinic acids, was studied. This compound has the property to complex caesium and has shown an antioxidant activity. The first strategy, based on a double Suzuki-Miyaura coupling between a naphtho-lactone with two boron functions and two pulvinic moieties with a triflate was unsuccessful and has shown a deactivating effect of the lactone. Modifications aimed to inhibit the electro-attracting character of the lactone permitted to obtain a bis(coupled) product with a poor yield. A second approach based on a the cyclization of enol aryl-acetates was studied in order to build the pulvinic moiety in several steps. The important reaction of introduction of an alkyl-acetate from a triflate was realised by a palladium-mediated coupling. The cyclization attempts carried out using a naphthalenic compound allowed us to isolate a monocyclised product. A parallel study was to first build a tetronic moiety and then to construct the exocyclic double bond by a method developed in the laboratory for the preparation of an iodated pulvinic compound. Finally, a new preparation of alcohols from sulfones and boron compounds was developed. Two known reactions in the chemistry of boron were combined. The first one is the reaction between anions of sulfones and tri-alkyl-boranes, the second one is a thermal isomerization which places the boron atom in a terminal position. A new preparation of primary alcohols was thus carried out. (author)

  14. Influence of point defects on the near edge structure of hexagonal boron nitride

    Science.gov (United States)

    McDougall, Nicholas L.; Partridge, Jim G.; Nicholls, Rebecca J.; Russo, Salvy P.; McCulloch, Dougal G.

    2017-10-01

    Hexagonal boron nitride (hBN) is a wide-band-gap semiconductor with applications including gate insulation layers in graphene transistors, far-ultraviolet light emitting devices and as hydrogen storage media. Due to its complex microstructure, defects in hBN are challenging to identify. Here, we combine x-ray absorption near edge structure (XANES) spectroscopy with ab initio theoretical modeling to identify energetically favorable defects. Following annealing of hBN samples in vacuum and oxygen, the B and N K edges exhibited angular-dependent peak modifications consistent with in-plane defects. Theoretical calculations showed that the energetically favorable defects all produce signature features in XANES. Comparing these calculations with experiments, the principle defects were attributed to substitutional oxygen at the nitrogen site, substitutional carbon at the boron site, and hydrogen passivated boron vacancies. Hydrogen passivation of defects was found to significantly affect the formation energies, electronic states, and XANES. In the B K edge, multiple peaks above the major 1 s to π* peak occur as a result of these defects and the hydrogen passivated boron vacancy produces the frequently observed doublet in the 1 s to σ* transition. While the N K edge is less sensitive to defects, features attributable to substitutional C at the B site were observed. This defect was also calculated to have mid-gap states in its band structure that may be responsible for the 4.1-eV ultraviolet emission frequently observed from this material.

  15. Study of boron effect on FeAl alloys with an ordered B2 structure; Etude de l'effet du bore sur les alliages FeAl ordonnes de structure B2

    Energy Technology Data Exchange (ETDEWEB)

    Gay-Brun, A.S

    1998-06-01

    FeAl alloys with an ordered B2 structure have good corrosion resistance and mechanical properties at high temperature. Nevertheless, their use is limited by the intergranular embrittlement at ambient temperature. It has already been shown that a doping by low amounts of boron can solve the problem of intergranular embrittlement. The aim of this work is to better understand the boron effect on the FeAl alloys. It has been confirmed that the boron doping change the mode of rupture of the FeAl alloys with a B2 structure; their strain on breaking point is increased. The limit of solubility of boron in Fe-40Al has been estimated between 400 and 800 ppm at 500 degrees Celsius. Above this limit, Fe{sub 2}B precipitates. The intergranular segregation of boron has been observed by Auger electron spectroscopy for all the FeAl alloys. The intergranular amount of boron is low (below 12%). In the range of boron solubility, the intergranular concentration of boron increases with its voluminal amount. From this result, boron segregation has been described by different models of equilibrium segregation; thus has been shown that it exists a strong repulsion energy between the segregated boron atoms. On the other hand, no equilibrium segregation model can describe the independence to temperature of the boron segregation and its very fast kinetics: these two characteristics have certainly to be explained by a segregation mechanism under equilibrium. The existence of a segregation mechanism under equilibrium has been confirmed by the observation of the acceleration of the vacancies elimination kinetics by boron. The interaction between the boron atoms and the thermal vacancies which migrates to grain boundaries lead to the formation of complexes. The importance of the boron effect is not limited to its role to grain boundaries. Indeed, has been observed a strong decrease of the long order distance in the alloys doped with boron. The structure of the dislocations created by the

  16. Boron exposure through drinking water during pregnancy and birth size.

    Science.gov (United States)

    Igra, Annachiara Malin; Harari, Florencia; Lu, Ying; Casimiro, Esperanza; Vahter, Marie

    2016-10-01

    Boron is a metalloid found at highly varying concentrations in soil and water. Experimental data indicate that boron is a developmental toxicant, but the few human toxicity data available concern mostly male reproduction. To evaluate potential effects of boron exposure through drinking water on pregnancy outcomes. In a mother-child cohort in northern Argentina (n=194), 1-3 samples of serum, whole blood and urine were collected per woman during pregnancy and analyzed for boron and other elements to which exposure occurred, using inductively coupled plasma mass spectrometry. Infant weight, length and head circumference were measured at birth. Drinking water boron ranged 377-10,929μg/L. The serum boron concentrations during pregnancy ranged 0.73-605μg/L (median 133μg/L) and correlated strongly with whole-blood and urinary boron, and, to a lesser extent, with water boron. In multivariable-adjusted linear spline regression analysis (non-linear association), we found that serum boron concentrations above 80μg/L were inversely associated with birth length (B-0.69cm, 95% CI -1.4; -0.024, p=0.043, per 100μg/L increase in serum boron). The impact of boron appeared stronger when we restricted the exposure to the third trimester, when the serum boron concentrations were the highest (0.73-447μg/L). An increase in serum boron of 100μg/L in the third trimester corresponded to 0.9cm shorter and 120g lighter newborns (p=0.001 and 0.021, respectively). Considering that elevated boron concentrations in drinking water are common in many areas of the world, although more screening is warranted, our novel findings warrant additional research on early-life exposure in other populations. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  17. Design of polymeric carrier containing boron for boron neutron capture therapy and its use in tissue cultures

    International Nuclear Information System (INIS)

    Kahraman, G.

    2004-01-01

    The aim of this study is the synthesis of a new alternative boron containing polymer carrier to be used for Boron Neutron Capture Therapy (BNCT) (one of the treatment methods for brain tumours) and to investigate its use in cell cultures. First of all, B-containing copolymer were synthesized by complex-radical copolymerization of vinylphenylboronic acid and maleic anhydride with 2, 2- azobisisobutyronitrile as an initiator in DMF solvent at 65 degree Celsius under nitrogen atmosphere. Macro branched derivatives of these polymers were synthesized by the partial grafting with α-hydroxy,ω -methoxy-poly(ethylene oxide). Characterization of Poly(VPBA-co-MA) and these macro branched copolymers were performed by FTIR, 1 H NMR spectroscopy, X-Ray diffraction, DSC and TGA analyses. As a result of these analyses, it was observed that these macro branched copolymers had a higher crystallinity and thermal stability than the copolymer. These properties of macro branched copolymers are explained by self-organized H-bonding effect in radical copolymerization and grafting reactions and by the formation of self assembled supramolecular architecture. The selected macro branched copolymer was incorporated by poly(ethylene imine) in order to uptake to cell and thus, this synthesized macro complex copolymer [(VFBA-co-MA)-g-PEG/PEI] was charged with positive charge. As a result of FTIR analysis, it was observed that COO - .NH + complex was formed. After the cell culture experiment, it was observed that this macro complex copolymer labelled with fluorescein up took to HeLa cells with 7 % efficiency. And then, folic acid was incorporated in [(VFBA-co-MA)-g-PEG/PEI] macro complex in order to provide selective targeting properties with tumour cells. As a result of the experiment of cell culture containing mixture of HeLa and fibroblast cell, it was observed that [(VFBA-co-MA)-g-PEG/PEI]-FA macro complex went towards to HeLa cells selectively by means of fluorescence microscopy. Poly

  18. 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.

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

    Directory of Open Access Journals (Sweden)

    Joo-Young Jung

    2016-09-01

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

  20. Testing boron carbide under triaxial compression

    Science.gov (United States)

    Anderson, Charles; Chocron, Sidney; Dannemann, Kathryn A.; Nicholls, Arthur E.

    2012-03-01

    This article focuses on the pressure dependence and summarizes the characterization work conducted on intact and predamaged specimens of boron carbide under confinement in a pressure vessel and in a thick steel sleeve. The failure curves obtained are presented, and the data compared to experimental data from the literature.

  1. Kinetic analysis of boron carbide sintering

    International Nuclear Information System (INIS)

    Borchert, W.; Kerler, A.R.

    1975-01-01

    The kinetics of the sintering of boron carbide were investigated by shrinkage measurements with a high-temperature dilatometer under argon atmosphere in dependence on temperature, grain size, and pressure. The activation energies and the reaction mechanisms of the different stages of sintering were determined. (orig.) [de

  2. Compaction of amorphous iron–boron powder

    DEFF Research Database (Denmark)

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

    1993-01-01

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

  3. 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: 1.162, year: 2015

  4. Energetics of Boron Doping of Carbon Pores

    Science.gov (United States)

    Wexler, Carlos; St. John, Alexander; Connolly, Matthew

    2014-03-01

    Carbon-based materials show promise, given their light weight, large surface areas and low cost for storage of hydrogen and other gases, e.g., for energy applications. Alas, the interaction of H2 and carbon, 4-5kJ/mol, is insufficient for room-temperature operation. Boron doping of carbon materials could raise the binding energy of H2 to 12-15kJ/mol. The nature of the incorporation of boron into a carbon structure has not been studied so far. In this talk we will address the energetics of boron incorporation into a carbon matrix via adsorption and decomposition of decaborane by first principles calculations. These demonstrate: (a) A strong adsorption of decaborane to carbon (70-80kJ/mol) resulting in easy incorporation of decaborane, sufficient for up to 10-20% B:C at low decaborane vapour pressures. (b) Identification that boron acts as an electron acceptor when incorporated substitutionally into a graphene-like material, as expected due to its valence. (c) The electrostatic field near the molecule is responsible for ca. 2/3 of the enhancement of the H2-adsorbent interaction in aromatic compounds such as pyrene, coronene and ovalene. Supported by DOE DE-FG36-08GO18142, ACS-PRF 52696-ND5, and NSF 1069091.

  5. Anomalous Seebeck coefficient in boron carbides

    International Nuclear Information System (INIS)

    Aselage, T.L.; Emin, D.; Wood, C.; Mackinnon, I.D.R.; Howard, I.A.

    1987-01-01

    Boron carbides exhibit an anomalously large Seebeck coefficient with a temperature coefficient that is characteristic of polaronic hopping between inequivalent sites. The inequivalence in the sites is associated with disorder in the solid. The temperature dependence of the Seebeck coefficient for materials prepared by different techniques provides insight into the nature of the disorder

  6. Reaction of boron carbide with molybdenum disilicide

    International Nuclear Information System (INIS)

    Novikov, A.V.; Melekhin, V.F.; Pegov, V.S.

    1989-01-01

    The investigation results of interaction in the B 4 C-MoSi 2 system during sintering in vacuum are presented. Sintering of boron carbide with molybdenum disilicide is shown to lead to the formation of MoB 2 , SiC, Mo 5 Si 3 compounds, the presence of carbon-containing covering plays an important role in sintering

  7. 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...

  8. NEW ADVANCES IN BORON SOIL CHEMISTRY - Paper

    Science.gov (United States)

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

  9. NEW ADVANCES IN BORON SOIL CHEMISTRY

    Science.gov (United States)

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

  10. Perfomance analysis of boron carbide in LMFBR

    International Nuclear Information System (INIS)

    Pitner, A.L.; Birney, K.R.

    1975-01-01

    Reactivity control in the FFTF and LMFBR's will be maintained by control elements utilizing boron carbide pellets contained in stainless steel pins. Computer performance codes predict irradiation service conditions of absorber pellets and identify required experimental testing. Test results are incorporated in the codes to improve performance prediction capabilities

  11. Bandgap engineered graphene and hexagonal boron nitride

    Indian Academy of Sciences (India)

    In this article a double-barrier resonant tunnelling diode (DBRTD) has been modelled by taking advantage of single-layer hexagonal lattice of graphene and hexagonal boron nitride (h-BN). The DBRTD performance and operation are explored by means of a self-consistent solution inside the non-equilibrium Green's ...

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

    DEFF Research Database (Denmark)

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

    2008-01-01

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

  13. Biological activity of N(4)-boronated derivatives of 2'-deoxycytidine, potential agents for boron-neutron capture therapy.

    Science.gov (United States)

    Nizioł, Joanna; Uram, Łukasz; Szuster, Magdalena; Sekuła, Justyna; Ruman, Tomasz

    2015-10-01

    Boron-neutron capture therapy (BNCT) is a binary anticancer therapy that requires boron compound for nuclear reaction during which high energy alpha particles and lithium nuclei are formed. Unnatural, boron-containing nucleoside with hydrophobic pinacol moiety was investigated as a potential BNCT boron delivery agent. Biological properties of this compound are presented for the first time and prove that boron nucleoside has low cytotoxicity and that observed apoptotic effects suggest alteration of important functions of cancer cells. Mass spectrometry analysis of DNA from cancer cells proved that boron nucleoside is inserted into nucleic acids as a functional nucleotide derivative. NMR studies present very high degree of similarity of natural dG-dC base pair with dG-boron nucleoside system. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Effect of electron injection on defect reactions in irradiated silicon containing boron, carbon, and oxygen

    Science.gov (United States)

    Makarenko, L. F.; Lastovskii, S. B.; Yakushevich, H. S.; Moll, M.; Pintilie, I.

    2018-04-01

    Comparative studies employing Deep Level Transient Spectroscopy and C-V measurements have been performed on recombination-enhanced reactions between defects of interstitial type in boron doped silicon diodes irradiated with alpha-particles. It has been shown that self-interstitial related defects which are immobile even at room temperatures can be activated by very low forward currents at liquid nitrogen temperatures. Their activation is accompanied by the appearance of interstitial carbon atoms. It has been found that at rather high forward current densities which enhance BiOi complex disappearance, a retardation of Ci annealing takes place. Contrary to conventional thermal annealing of the interstitial boron-interstitial oxygen complex, the use of forward current injection helps to recover an essential part of charge carriers removed due to irradiation.

  15. 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

  16. Synthesis of glucaminium-based ionic liquids and their application in the removal of boron from water.

    Science.gov (United States)

    Joshi, Manishkumar D; Chalumot, Guillaume; Kim, Yong-wah; Anderson, Jared L

    2012-02-01

    A novel class of ionic liquids (ILs), exhibiting high selectivity towards boron species as well as the ability to phase separate from water, were synthesized from N-methyl-D-glucamine. The complexation of boric acid/borate with the ILs was confirmed using (11)B NMR. This journal is © The Royal Society of Chemistry 2012

  17. Contributions te the study of methods and factors affecting the spectrophotometric determination of boron traces with carmin uranium compounds

    International Nuclear Information System (INIS)

    Fernandez Cellini, R.; Gasco Sanchez, L.

    1956-01-01

    The study of some factors affecting the spectrophotometric determination of boron traces with carmin is made; the influence of carmin from different origin, the stability of complex carmin-boric acid in relation with the sulphuric acid concentration, the interference produced by ion nitrate, and the ion uraline and light influence are discussed. (Author) 36 refs

  18. Rhodium-Catalyzed Direct Ortho C-H Arylation Using Ketone as Directing Group with Boron Reagent.

    Science.gov (United States)

    Zhang, Bing; Wang, Huai-Wei; Kang, Yan-Shang; Zhang, Ping; Xu, Hua-Jin; Lu, Yi; Sun, Wei-Yin

    2017-11-03

    A general method for selective ortho C-H arylation of ketone, with boron reagent enabled by rhodium complexes with excellent yields, is developed. The transformation is characterized by the use of air-stable Rh catalyst, high monoarylation selectivity, and excellent yields of most of the substrates.

  19. Raman spectroscopy of boron-doped single-layer graphene.

    Science.gov (United States)

    Kim, Yoong Ahm; Fujisawa, Kazunori; Muramatsu, Hiroyuki; Hayashi, Takuya; Endo, Morinobu; Fujimori, Toshihiko; Kaneko, Katsumi; Terrones, Mauricio; Behrends, Jan; Eckmann, Axel; Casiraghi, Cinzia; Novoselov, Kostya S; Saito, Riichiro; Dresselhaus, Mildred S

    2012-07-24

    The introduction of foreign atoms, such as nitrogen, into the hexagonal network of an sp(2)-hybridized carbon atom monolayer has been demonstrated and constitutes an effective tool for tailoring the intrinsic properties of graphene. Here, we report that boron atoms can be efficiently substituted for carbon in graphene. Single-layer graphene substitutionally doped with boron was prepared by the mechanical exfoliation of boron-doped graphite. X-ray photoelectron spectroscopy demonstrated that the amount of substitutional boron in graphite was ~0.22 atom %. Raman spectroscopy demonstrated that the boron atoms were spaced 4.76 nm apart in single-layer graphene. The 7-fold higher intensity of the D-band when compared to the G-band was explained by the elastically scattered photoexcited electrons by boron atoms before emitting a phonon. The frequency of the G-band in single-layer substitutionally boron-doped graphene was unchanged, which could be explained by the p-type boron doping (stiffening) counteracting the tensile strain effect of the larger carbon-boron bond length (softening). Boron-doped graphene appears to be a useful tool for engineering the physical and chemical properties of graphene.

  20. Laser-induced photochemical enrichment of boron isotopes

    International Nuclear Information System (INIS)

    Freund, S.M.; Ritter, J.J.

    1976-01-01

    A boron trichloride starting material containing both boron-10 isotopes and boron-11 isotopes is selectively enriched in one or the other of these isotopes by a laser-induced photochemical method involving the reaction of laser-excited boron trichloride with either H 2 S or D 2 S. The method is carried out by subjecting a low pressure gaseous mixture of boron trichloride starting material and the sulfide to infrared radiation from a carbon dioxide TE laser. The wave length of the radiation is selected so as to selectively excite one or the other of boron-10 BCl 3 molecules or boron-11 BCl 3 molecules, thereby making them preferentially more reactive with the sulfide. The laser-induced reaction produces both a boron-containing solid phase reaction product and a gaseous phase containing mostly unreacted BCl 3 and small amounts of sulfhydroboranes. Pure boron trichloride selectively enriched in one of the isotopes is recovered as the primary product of the method from the gaseous phase by a multi-step recovery procedure. Pure boron trichloride enriched in the other isotope is recovered as a secondary product of the method by the subsequent chlorination of the solid phase reaction product followed by separation of BCl 3 from the mixture of gaseous products resulting from the chlorination

  1. 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.

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

    Science.gov (United States)

    Hou, Deyin; Wang, Jun; Sun, Xiangcheng; Luan, Zhaokun; Zhao, Changwei; Ren, Xiaojing

    2010-05-15

    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 microg/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. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  3. Boron isotope determinations in waters and other geological materials: analytical techniques and inter-calibration of measurements.

    Science.gov (United States)

    Tonarini, Sonia; Pennisi, Maddalena; Gonfiantini, Roberto

    2009-06-01

    The (11)B/(10)B ratio exhibits wide variations in nature; thus, boron isotopes have found numerous applications in geochemistry, hydrology, and environmental studies. The main analytical techniques used are as follows: positive thermal ionisation mass spectrometry is the most precise (about 0.2 per thousand of the boron isotope ratio), but requires complex and laborious sample preparation; negative thermal ionisation mass spectrometry is less precise (about 0.5 per thousand), but rapid and suitable for water samples, whereas total evaporation-NTIMS allows for identification of the precise boron isotope composition of marine carbonates. It is expected that multi-collection system inductively coupled plasma mass spectrometry (MC-ICPMS) will eventually combine high precision with simple analytical procedures. Secondary ion mass spectrometry and laser ablation (LA)-MC-ICPMS allow in situ determinations on solid samples, but require the availability of calibration materials which are chemically and mineralogically similar to samples. These features of boron isotope measurement techniques were confirmed by the results of the first inter-laboratory comparison of measurements, organised by the Istituto di Geoscienze e Georisorse in Pisa. Finally, two examples of boron isotope applications in groundwater investigations are reported.

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

    Science.gov (United States)

    Chu, T. L.

    1975-01-01

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

  5. Analytical techniques for boron and boron 10 analysis in a solid experimental tumor EO.771

    International Nuclear Information System (INIS)

    Porschen, W.; Marx, J.; Feinendegen, L.E.

    1987-01-01

    If a tumor can be preferentially loaded with a suitable boron-10 compound and irradiated with thermal neutrons, malignant cells can be selectively destroyed via the α-particle + Li 7-nucleus from the reaction 10 B(n,α) 7 Li. Neutron capture therapy with two boron-10 amino acid analogs of low toxicity has been tested in recent years: (a) trimethylamine carboxyborane, (A3) and (b) amine-carboxyborane, (A7). Now the boron-10 glycineamide analog (A8), amineboryl carboxamide has been synthsized; it contains 13.81% boron (90% Boron 10+10% Boron 11) and shows a very low toxicity in mice. The effects of this compund were tested on the syngeneic solid adenocarcinoma EO 771 on the right hind leg of male C57 BL/6J mice under standard conditions, by measuring tumor volume growth delay and cell cycle changes using flow cytometry. Boron distribution between tumor and muscle was analyzed by emission spectroscopy with inductively coupled plasma (ICP) following injection of a suspension of peanut oil emulsion. In addition, boron-10 concentration in the tumor were analyzed with prompt γ-activation analysis and neutron capture radiography (Kodak-Pathe LR115) at the MRR reactor in Brookhaven after i.p. injection of 0.4 mg/g A8. Application of A8 alone (0.4 mg/g i.p.) or thermal neutron irradiation of the tumor EO. 771 produced a tumor growth delay of 1-2 days for tumor volume doubling. Application of the boron 10 glycine-amide analog A8 i.p. plus 5x10 12 n/cm 2 resulted in a growth delay of 3-6 days. In contrast intratumoral application of A8 plus 4x10 12 n/cm 2 neutrons gave a growth delay of 7-14 days; the fraction of (G2+M) cells rose from 35% (neutrons alone) to 52%, as evaluated from flow cytometry. (orig.)

  6. 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.

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

    Science.gov (United States)

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

    2015-12-18

    At the atomic-cluster scale, pure boron is markedly similar to carbon, forming simple planar molecules and cage-like fullerenes. Theoretical studies predict that two-dimensional (2D) boron sheets will adopt an atomic configuration similar to that of boron atomic clusters. We synthesized atomically thin, crystalline 2D boron sheets (i.e., borophene) on silver surfaces under ultrahigh-vacuum conditions. Atomic-scale characterization, supported by theoretical calculations, revealed structures reminiscent of fused boron clusters with multiple scales of anisotropic, out-of-plane buckling. Unlike bulk boron allotropes, borophene shows metallic characteristics that are consistent with predictions of a highly anisotropic, 2D metal. Copyright © 2015, American Association for the Advancement of Science.

  8. Influence of dopants, particularly carbon, on β-rhombohedral boron

    Science.gov (United States)

    Werheit, H.; Flachbart, K.; Pristáš, G.; Lotnyk, D.; Filipov, V.; Kuhlmann, U.; Shitsevalova, N.; Lundström, T.

    2017-09-01

    Due to the high affinity of carbon to boron, the preparation of carbon-free boron is problematic. Even high-purity (6 N) β-rhombohedral boron contains 30-60 ppm of C. Hence, carbon affects the boron physical properties published so far more or less significantly. We studied well-defined carbon-doped boron samples based on pure starting material carefully annealed with up to about 1% C, thus assuring homogeneity. We present and discuss their electrical conductivity, optical absorption, luminescence and phonon spectra. Earlier attempts of other authors to determine the conductivity of C-doped boron are revised. Our results allow estimating the effects of oxygen and iron doping on the electrical conductivity using results taken from literature. Discontinuities at low T impair the electronic properties.

  9. Synthesis of Boron Nano wires, Nano tubes, and Nano sheets

    International Nuclear Information System (INIS)

    Patel, R.B.; Chou, T.; Iqbal, Z.

    2014-01-01

    The synthesis of boron nano wires, nano tubes, and nano sheets using a thermal vapor deposition process is reported. This work confirms previous research and provides a new method capable of synthesizing boron nano materials. The materials were made by using various combinations of MgB 2 , Mg(BH 4 ) 2 , 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 nano wires, boron nano tubes, and boron nano sheets 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. Boron autoradiography method applied to the study of steels

    International Nuclear Information System (INIS)

    Gugelmeier, R.; Barcelo, G.N.; Boado, J.H.; Fernandez, C.

    1986-01-01

    The boron state, contained in the steel microestructure, is determined. The autoradiography by neutrons is used, permiting to obtain boron distribution images by means of additional information which is difficult to acquire by other methods. The application of the method is described, based on the neutronic irradiation of a polished steel sample, over which a celulose nitrate sheet or other appropriate material is fixed to constitute the detector. The particles generated by the neutron-boron interaction affect the detector sheet, which is subsequently revealed with a chemical treatment and can be observed at the optical microscope. In the case of materials used for the construction of nuclear reactors, special attention must be given to the presence of boron, since owing to the exceptionaly high capacity of neutron absorption, lowest quantities of boron acquire importance. The adaption of the method to metallurgical problems allows the obtainment of a correlation between the boron distribution images and the material's microstructure. (M.E.L.) [es

  11. Boron nitride - Composition, optical properties, and mechanical behavior

    Science.gov (United States)

    Pouch, John J.; Alterovitz, Samuel A.; Miyoshi, Kazuhisa; Warner, Joseph D.

    1987-01-01

    A low energy ion beam deposition technique was used to grow boron nitride films on quartz, germanium, silicon, gallium arsenide, and indium phosphate. The film structure was amorphous with evidence of a hexagonal phase. The peak boron concentration was 82 at. percent. The carbon and oxygen impurities were in the 5 to 8 at. percent range. Boron-nitrogen and boron-boron bonds were revealed by X-ray photoelectron spectroscopy. The index of refraction varied from 1.65 to 1.67 for films deposited on III-V compound semiconductors. The coefficient of friction for boron nitride in sliding contact with diamond was less than 0.1. The substrate was silicon.

  12. Boron nitride: Composition, optical properties and mechanical behavior

    Science.gov (United States)

    Pouch, John J.; Alterovitz, Samuel A.; Miyoshi, Kazuhisa; Warner, Joseph D.

    1987-01-01

    A low energy ion beam deposition technique was used to grow boron nitride films on quartz, germanium, silicon, gallium arsenide, and indium phosphate. The film structure was amorphous with evidence of a hexagonal phase. The peak boron concentration was 82 at %. The carbon and oxygen impurities were in the 5 to 8 at % range. Boron-nitrogen and boron-boron bonds were revealed by X-ray photoelectron spectroscopy. The index of refraction varied from 1.65 to 1.67 for films deposited on III-V compound semiconductors. The coefficient of friction for boron nitride in sliding contact with diamond was less than 0.1. The substrate was silicon.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-12-15

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

  14. Separation and Analysis of Boron Isotope in High Plant by Thermal Ionization Mass Spectrometry

    OpenAIRE

    Xu, Qingcai; Dong, Yuliang; Zhu, Huayu; Sun, Aide

    2015-01-01

    Knowledge of boron and its isotope in plants is useful to better understand the transposition and translocation of boron within plant, the geochemical behavior in the interface between soil and plant, and the biogeochemical cycle of boron. It is critical to develop a useful method to separate boron from the plant for the geochemical application of boron and its isotope. A method was developed for the extraction of boron in plant sample, whose isotope was determined by thermal ionization mass ...

  15. Characterization of Boron Atom Aggregation

    National Research Council Canada - National Science Library

    Maler, John

    2002-01-01

    ... in rare gas cryogenic solids. A number of experiments were undertaken and theoretical calculations in order to understand the details of the complex vibronic structure in the electronic absorption spectra of B3 and B3 - in 5K neon matrices...

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

    Science.gov (United States)

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

    2010-10-06

    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.

  17. Apparatus for the production of boron nitride nanotubes

    Science.gov (United States)

    Smith, Michael W; Jordan, Kevin

    2014-06-17

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

  18. Behavior of disordered boron carbide under stress.

    Science.gov (United States)

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

    2006-07-21

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

  19. Steam activation of boron doped diamond electrodes

    International Nuclear Information System (INIS)

    Ohashi, Tatsuya; Zhang Junfeng; Takasu, Yoshio; Sugimoto, Wataru

    2011-01-01

    Highlights: → Steam activation of boron doped diamond (BDD) electrodes. → Steam activated BDD has a porous columnar texture. → Steam activated BDD has a wide potential window. - Abstract: Boron doped diamond (BDD) electrodes were activated in steam at various temperatures, resulting in high quality BDD electrodes with a porous microstructure. Distinct columnar structures were observed by scanning electron microscopy. The electrochemically active surface area of the steam-activated BDD was up to 20 times larger than the pristine BDD electrode owing to the porous texture. In addition, a widening of the potential window was observed after steam activation, suggesting that the quality of BDD was enhanced due to oxidative removal of graphitic impurities during the activation process.

  20. 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.

  1. CVD mechanism of pyrolytic boron nitride

    International Nuclear Information System (INIS)

    Tanji, H.; Monden, K.; Ide, M.

    1987-01-01

    Pyrolytic boron nitride (P-BN) has become a essential material for III-V compound semiconductor manufacturing process. As the demand from electronics industry for larger single crystals increases, the demand for larger and more economical P-BN components is growing rapidly. P-BN is manufactured by low pressure CVD using boron-trihalides and ammonia as the reactants. In spite that P-BN has been in the market for quite a long time, limited number of fundamental studies regarding the kinetics and the formation mechanism of P-BN have been reported. As it has been demonstrated in CVD of Si, knowledge and both theoretical and empirical modeling of CVD process can be applied to improve the deposition technology and to give more uniform deposition with higher efficiency, and it should also apply to the deposition of P-BN

  2. Boron Nitride Nanotube: Synthesis and Applications

    Science.gov (United States)

    Tiano, Amanda L.; Park, Cheol; Lee, Joseph W.; Luong, Hoa H.; Gibbons, Luke J.; Chu, Sang-Hyon; Applin, Samantha I.; Gnoffo, Peter; Lowther, Sharon; Kim, Hyun Jung; hide

    2014-01-01

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

  3. Synthesis and characterization of boron nitrides nanotubes

    International Nuclear Information System (INIS)

    Ferreira, T.H.; Sousa, E.M.B.

    2010-01-01

    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)

  4. Characterization of boron doped nanocrystalline diamonds

    International Nuclear Information System (INIS)

    Peterlevitz, A C; Manne, G M; Sampaio, M A; Quispe, J C R; Pasquetto, M P; Iannini, R F; Ceragioli, H J; Baranauskas, V

    2008-01-01

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

  5. Development of boron epoxy rocket motor chambers.

    Science.gov (United States)

    Jensen, W. M.; Knoell, A. C.; Zweben, C.

    1972-01-01

    A 71 cm diameter 74 cm length boron/epoxy composite rocket motor chamber was designed based on the geometric configuration of the JPL Applications Technology Satellite titanium alloy apogee motor chamber. Because analyses showed large stress concentrations in the domes, the configuration was modified using the same basic constraints for openings and attachments. The rocket motor chamber was then fabricated by filament winding with boron/epoxy tape and hydrostatically tested to failure at 264 N/sq cm, 57.2 N/sq cm above the design value. Two more rocket motor chambers were fabricated with the same basic constraints, but shortened to 57.6 cm for a smaller propellant load. The first of these short chambers failed in proof because of filament winding fabrication difficulties. The second chamber was successfully fabricated and passed the hydrostatic proof test.

  6. 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.

  7. 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.

  8. Dependence of boron cluster dissolution on the annealing ambient

    International Nuclear Information System (INIS)

    Radic, Ljubo; Lilak, Aaron D.; Law, Mark E.

    2002-01-01

    Boron is introduced into silicon via implantation to form p-type layers. This process creates damage in the crystal that upon annealing causes enhanced diffusion and clustering of the boron layer. Reactivation of the boron is not a well-understood process. In this letter we experimentally investigate the effect of the annealing ambient on boron reactivation kinetics. An oxidizing ambient which injects silicon interstitials is compared to an inert ambient. Contrary to published theory, an excess of interstitials does not accelerate the reactivation process

  9. Molecular Dynamics Modeling of Piezoelectric Boron Nirtride Nanotubes

    Data.gov (United States)

    National Aeronautics and Space Administration — Conduct a systematic computational study on the physical and electro-mechanical properties of Boron Nitride Nanotubes (BNNTs) to evaluate their functional...

  10. Cobalt Doping of Semiconducting Boron Carbide Using Cobaltocene

    National Research Council Canada - National Science Library

    Carlson, Lonnie

    2007-01-01

    .... This temperature dependent surface photovoltage effect is not compelling evidence for the majority carrier type but does suggest an increase in the carrier concentration in semiconducting boron...

  11. 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.

  12. High resolution imaging of boron carbide microstructures

    International Nuclear Information System (INIS)

    MacKinnon, I.D.R.; Aselage, T.; Van Deusen, S.B.

    1986-01-01

    Two samples of boron carbide have been examined using high resolution transmission electron microscopy (HRTEM). A hot-pressed B 13 C 2 sample shows a high density of variable width twins normal to (10*1). Subtle shifts or offsets of lattice fringes along the twin plane and normal to approx.(10*5) were also observed. A B 4 C powder showed little evidence of stacking disorder in crystalline regions

  13. 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.

  14. Boron isotopes as an artificial tracer.

    Science.gov (United States)

    Quast, Konrad W; Lansey, Kevin; Arnold, Robert; Bassett, Randy L; Rincon, Martha

    2006-01-01

    A field study was conducted using a combination of intrinsic and artificial tracers to estimate travel times and dilution during transport of infiltrate from a reclaimed water infiltration basin to nearby monitoring wells. A major study objective was to validate boric acid enriched in (10)B as an artificial tracer. Basin 10E at the Rio Hondo Spreading Grounds in Whittier, California, was the site of the test. The basin normally receives a mixture of treated municipal waste water, purchased State Project water, and local runoff from the San Gabriel River. Approximately 3.5 kg of (10)B-enriched boric acid was dispersed among 2.05 x 10(5) m(3) of basin water to initiate the experiment. The resultant median delta(11)B in the infiltration basin was -71 per thousand. Prior to tracer addition, the basin water had an intrinsic delta(11)B of +2 per thousand. Local monitoring wells that were used to assess travel times had delta(11)B values of +5 per thousand and +8 per thousand at the time of tracer addition. Analytic results supported an assumption that boron is conserved during ground water transport and that boron enriched in (10)B is a useful artificial tracer. Several intrinsic tracers were used to reinforce the boric acid tracer findings. These included stable isotopes of oxygen (delta(18)O) and hydrogen (deltaD), sulfate concentration, and the boron to chloride ratio. Xenon isotopes, (136)Xe and (124)Xe, also supported boron isotope results. Xenon isotopes were added to the recharge basin as dissolved gases by investigators from the Lawrence Livermore National Laboratory.

  15. Boron Isotopes Enrichment via Continuous Annular Chromatography

    OpenAIRE

    Sağlam, Gonca

    2016-01-01

    ABSTRACT Boron has two stable isotopes namely 10B and 11B isotopes. The large cross section of 10B isotope for thermal neutrons is used for reactor control in nuclear fission reactors. The thermal neutrons absorption cross sections of pure 10B and 11B are 3837 and 0.005 barns respectively. In the literature, amongst others, batch elution chromatography techniques are reported for 10B isotope enrichment. This work focuses on continuous chromatographic 10B isotope separation system via continuo...

  16. Clinical aspects of boron neutron capture therapy

    International Nuclear Information System (INIS)

    Goodman, J.H.; Gahbauer, R.; Clendenon, N.

    1986-01-01

    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

  17. Nanotwins soften boron-rich boron carbide (B13C2)

    Science.gov (United States)

    An, Qi; Goddard, William A.

    2017-03-01

    Extensive studies of metals and alloys have observed that nanotwins lead to strengthening, but the role of nanotwins in ceramics is not well established. We compare here the shear strength and the deformation mechanism of nanotwinned boron-rich boron carbide (B13C2) with the perfect crystal under both pure shear and biaxial shear deformations. We find that the intrinsic shear strength of crystalline B13C2 is higher than that of crystalline boron carbide (B4C). But nanotwins in B13C2 lower the strength, making it softer than crystalline B4C. This reduction in strength of nanotwinned B13C2 arises from the interaction of the twin boundary with the C-B-C chains that connect the B12 icosahedra.

  18. Boron-carbide-aluminum and boron-carbide-reactive metal cermets

    Science.gov (United States)

    Halverson, Danny C.; Pyzik, Aleksander J.; Aksay, Ilhan A.

    1986-01-01

    Hard, tough, lightweight boron-carbide-reactive metal composites, particularly boron-carbide-aluminum composites, are produced. These composites have compositions with a plurality of phases. A method is provided, including the steps of wetting and reacting the starting materials, by which the microstructures in the resulting composites can be controllably selected. Starting compositions, reaction temperatures, reaction times, and reaction atmospheres are parameters for controlling the process and resulting compositions. The ceramic phases are homogeneously distributed in the metal phases and adhesive forces at ceramic-metal interfaces are maximized. An initial consolidation step is used to achieve fully dense composites. Microstructures of boron-carbide-aluminum cermets have been produced with modulus of rupture exceeding 110 ksi and fracture toughness exceeding 12 ksi.sqroot.in. These composites and methods can be used to form a variety of structural elements.

  19. Boron determination in U3O8

    International Nuclear Information System (INIS)

    Ogura, Nadia S.; Sarkis, Jorge E.S.; Rosa, Daniele S.; Ulrich, Joao C.

    2009-01-01

    There exist specifications of the concentration as far the limit of impurities in the used uranium compounds is concerned. Among those impurities the boron element is detached. that in the uranium compounds acts as neutron absorber in nuclear reactions. Therefore, the determination of this element in uranium compounds, it is fundamental for the quality and performance of the nuclear fuels. However, the determination of this element is many times prejudiced by the presence of the uranium. For solving this problem, it is performed a chemical separation of the uranium (matrix) out of the interest. The most used methods to accomplish that separation are the solvent extraction and the ion exchange. In this work, the boron concentration will be done through the ion exchange technique, using polypropylene columns and Dowex AG 50W - X8 100-200 mesh cation resin in chloricide medium 0.25 M. The boron concentration will be determined through high resolution inductive coupling plasma mass spectrometry (HRICP-MS)

  20. A fundamental study of industrial boron carbide

    International Nuclear Information System (INIS)

    Zuppiroli, L.; Kormann, R.; Lesueur, D.

    1983-09-01

    Some of the physical properties of boron carbide, before and after irradiation are reviewed on the basis of several new experiments performed in our laboratory. The layered aspect of the grains of this ceramic, due to a microtwinning of the rhomboedral structure, is emphasized first. Then, the location of free carbon in samples of composition close to B 4 C is discussed in relation with new sputtering experiments. Coupled studies of the electric conductivities and the electron spin resonance lines have demonstrated the important role of free carbon in the electronic properties of boron carbide and revealed the existence of a homogeneous short range disorder, the origin of which is not very clear (amorphous concept). The elementary processes responsible of the swelling and microcracking of neutron irradiated boron carbide are rather well understood. The role of the point defects in these processes is reported. The displacement threshold energies and formation volumes are discussed in relation with electron irradiation experiments, and displacement rates are calculated in different irradiation situations including neutron irradiations [fr

  1. Application of ICPMS for performance evaluation of boron enrichment plant at HWP, Manuguru

    International Nuclear Information System (INIS)

    Murthy, P.K.; Mohapatra, C.; Vithal, G.K.

    2011-01-01

    10 B enriched compounds are used in neutron control rod in Fast Breeder Reactors (FBR), Neutron Detector, Neutron Capture Therapy, and Neutron Shielding. Heavy Water Board (HWB) is given a mandate to produce enriched elemental boron which is being produced using Ion exchange chromatography and BF 3 - ether complex distillation methods. Ion Exchange Chromatography based Boron Enrichment Plant is operating at HWP, Manuguru. Ion Exchange Chromatography based process depends, besides other process parameters, on column run time and movement of band length. For effective process and quality control, it is necessary to analyze 10 B/ 11 B ratio in feed, process stream, waste and the product. 10 B/ 11 B ratio measurements are possible by Thermal Ionization Mass Spectrometer (TIMS) and Inductively Coupled Plasma Mass Spectrometer (ICPMS), the former offers better accuracy but takes longer analysis time whereas the later offers quick analysis of isotopic ratios and as well as trace metal impurities in the Boric acid

  2. Easy access to nucleophilic boron through diborane to magnesium boryl metathesis

    Science.gov (United States)

    Pécharman, Anne-Frédérique; Colebatch, Annie L.; Hill, Michael S.; McMullin, Claire L.; Mahon, Mary F.; Weetman, Catherine

    2017-04-01

    Organoboranes are some of the most synthetically valuable and widely used intermediates in organic and pharmaceutical chemistry. Their synthesis, however, is limited by the behaviour of common boron starting materials as archetypal Lewis acids such that common routes to organoboranes rely on the reactivity of boron as an electrophile. While the realization of convenient sources of nucleophilic boryl anions would open up a wealth of opportunity for the development of new routes to organoboranes, the synthesis of current candidates is generally limited by a need for highly reducing reaction conditions. Here, we report a simple synthesis of a magnesium boryl through the heterolytic activation of the B-B bond of bis(pinacolato)diboron, which is achieved by treatment of an easily generated magnesium diboranate complex with 4-dimethylaminopyridine. The magnesium boryl is shown to act as an unambiguous nucleophile through its reactions with iodomethane, benzophenone and N,N'-di-isopropyl carbodiimide and by density functional theory.

  3. Large Eddy Simulation for an inherent boron dilution transient

    International Nuclear Information System (INIS)

    Jayaraju, S.T.; Sathiah, P.; Komen, E.M.J.; Baglietto, E.

    2013-01-01

    Highlights: • Large Eddy Simulation is performed for a transient boron dilution scenario in the scaled experimental facility of ROCOM. • Fully conformal polyhedral grid of 14 million is created to capture all details of the domain. • Systematic multi-step validation methodology is followed to assess the accuracy of LES model. • For the presently simulated BDT scenario, the LES results lend support to its reliability in consistently predicting the slug transport in the RPV. -- Abstract: The present paper focuses on the validation and applicability of large eddy simulation (LES) to analyze the transport and mixing in the reactor pressure vessel (RPV) during an inherent boron dilution transient (BDT) scenario. Extensive validation data comes from relevant integral tests performed in the scaled ROCOM experimental facility. The modeling of sub-grid-scales is based on the WALE model. A fully conformal polyhedral grid of about 15 million cells is constructed to capture all details in the domain, including the complex structures of the lower-plenum. Detailed qualitative and quantitative validations are performed by following a systematic multi-step validation methodology. Qualitative comparisons to the experimental data in the cold legs, downcomer and the core inlet showed good predictions by the LES model. Minor deviations seen in the quantitative comparisons are rigorously quantified. A key parameter which is affecting the core neutron kinetics response is the value of highest deborated slug concentration that occurs at the core inlet during the transient. Detailed analyses are made at the core inlet to evaluate not only the value of the maximum slug concentration, but also the location and the time at which it occurs during the transient. The relative differences between the ensemble averaged experimental data and CFD predictions were within the range of relative differences seen within 10 different experimental realizations. For the studied scenario, the

  4. Bismuth-boron multiple bonding in BiB{sub 2}O{sup -} and Bi{sub 2}B{sup -}

    Energy Technology Data Exchange (ETDEWEB)

    Jian, Tian; Cheung, Ling Fung; Chen, Teng-Teng; Wang, Lai-Sheng [Department of Chemistry, Brown University, Providence, RI (United States)

    2017-08-01

    Despite its electron deficiency, boron is versatile in forming multiple bonds. Transition-metal-boron double bonding is known, but boron-metal triple bonds have been elusive. Two bismuth boron cluster anions, BiB{sub 2}O{sup -} and Bi{sub 2}B{sup -}, containing triple and double B-Bi bonds are presented. The BiB{sub 2}O{sup -} and Bi{sub 2}B{sup -} clusters are produced by laser vaporization of a mixed B/Bi target and characterized by photoelectron spectroscopy and ab initio calculations. Well-resolved photoelectron spectra are obtained and interpreted with the help of ab initio calculations, which show that both species are linear. Chemical bonding analyses reveal that Bi forms triple and double bonds with boron in BiB{sub 2}O{sup -} ([Bi≡B-B≡O]{sup -}) and Bi{sub 2}B{sup -} ([Bi=B=Bi]{sup -}), respectively. The Bi-B double and triple bond strengths are calculated to be 3.21 and 4.70 eV, respectively. This is the first experimental observation of Bi-B double and triple bonds, opening the door to design main-group metal-boron complexes with multiple bonding. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Synovectomy by neutron capture in boron

    International Nuclear Information System (INIS)

    Vega C, H.R.

    2002-01-01

    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

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

    Science.gov (United States)

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

    2011-12-01

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

  7. A new adsorbent for boron removal from aqueous solutions.

    Science.gov (United States)

    Kluczka, Joanna; Korolewicz, Teofil; Zołotajkin, Maria; Simka, Wojciech; Raczek, Malwina

    2013-01-01

    A new adsorbent based on natural clinoptilolite and amorphous zirconium dioxide (ZrO2) was prepared for the uptake of boron from fresh water. The sorption behaviour of this adsorbent for boron was investigated using a batch system and found to obey Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. The ZrO2 loading level, pH, temperature, contact time, initial boron concentration and adsorbent dose, on the removal of boron were studied. It was found that the removal of boron increased while the adsorbent dose increased and the temperature decreased at an optimum pH (pH = 8) and a contact time of 30 min. At optimum conditions, the maximum boron percentage removal was 75%. According to the D-R model, the maximum capacity was estimated to be > 3 mg B/g of the adsorbent. The adsorption energy value (calculated as 9.13 kJ/mol) indicated that the adsorption of boron on clinoptilolite modified with ZrO2 was physical in nature. The parameters of the adsorption models and the pH investigations pointed to the possibility of a chemisorption process. The thermodynamic parameters (standard entropy deltaS degrees, enthalpy deltaH degrees , and free energy deltaG degrees changes) of boron adsorption were also calculated. The negative value of deltaS degrees indicated a decreased randomness at the solid-solution interface during the boron adsorption. Negative values of deltaH degrees showed the exothermic nature of the process. The negative values of deltaG degrees implied that the adsorption of boron on clinoptilolite modified with amorphous ZrO2 at 25 degrees C was spontaneous. It was considered that boron dissolved in water had been adsorbed both physically and chemically on clinoptilolite modified with 30% ZrO2.

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

    International Nuclear Information System (INIS)

    Hwang, Dooseong; Choi, Hei Min; Lee, Kune Woo; Moon Jeikwon

    2014-01-01

    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

  9. Studies on the oxygen precipitation in highly boron doped silicon; Untersuchungen zur Sauerstoffausscheidung in hoch bordotiertem Silicium

    Energy Technology Data Exchange (ETDEWEB)

    Zschorsch, Markus

    2007-12-14

    The aim of this thesis was the getting of new knowledge on the elucidation of the oxygen precipitation in highly doped silicon. In the study of the early phases of the oxygen precipitation boron-oxygen complexes and their kinetics could be indirectly detected. These arise already during the cooling of the crystal and can be destroyed by subsequent temperature processes. The formation of the here as BO assumed species during the cooling after the silicon crystal fabrication could be numerically reproduced. Furthermore the study of early precipitation phases by means of neutron small angle scattering a maximum of the oxygen precipitation at {rho}=9 m{omega}cm. It could be shown that the decreasing of this at increasing boron concentration can be most probably reduced to boron precipitations. Furthermore it could be shown that after a tempering time of 24 hours at 700 C in silicon with {rho}=9 m{omega}cm platelet-shaped precipitates form. By the study of the precipitate growth could be shown that also in this phase the oxygen precipitation in silicon is strongest with a specific resistance of {rho}=9 m{omega}cm. By means of FTIR spectroscopy a new absorption band at a wave number of 1038 cm{sup -1} was found, which could be assigned to a boron species. By different experiments it is considered as probable that at this species it deals with BI respectively B{sub 2}I complexes.

  10. Identification of limiting case between DBA and SBDBA (CL break area sensitivity): A new model for the boron injection system

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Gonzalez, R., E-mail: r.gonzalez@ing.unipi.it [San Piero a Grado Nuclear Research Group (GRNSPG), University of Pisa, Via Livornese 1291, 56122 San Piero a Grado, Pisa (Italy); Petruzzi, A., E-mail: a.petruzzi@ing.unipi.it [San Piero a Grado Nuclear Research Group (GRNSPG), University of Pisa, Via Livornese 1291, 56122 San Piero a Grado, Pisa (Italy); D’Auria, F., E-mail: f.dauria@ing.unipi.it [San Piero a Grado Nuclear Research Group (GRNSPG), University of Pisa, Via Livornese 1291, 56122 San Piero a Grado, Pisa (Italy); Mazzantini, O., E-mail: mazzantini@na-sa.com.ar [Nucleo-electrica Argentina Sociedad Anonima (NA-SA), Buenos Aires (Argentina)

    2014-08-15

    Atucha-2 is a Siemens-designed Pressurized Heavy Water Reactor (PHWR) reactor under construction in the Republic of Argentina. Its geometrical complexity and peculiarity (e.g. oblique Control Rods, Positive Void coefficient) required a developed and validated complex three dimensional (3D) neutron kinetics (NK) coupled thermal hydraulic (TH) model. Reactor shut-down is obtained by oblique CRs and, during accidental conditions, by an emergency shut-down system (JDJ) injecting a highly concentrated boron solution (boron clouds) in the moderator tank. The boron clouds reconstruction is obtained using a Computational Fluid Dynamics (CFD) CFX code calculation. A complete Large Break Loss Of Coolant Accident (LBLOCA) calculation implies the application of the RELAP5-3D{sup ©} system code. Within the framework of the third Agreement “Nucleoelèctrica Argentina-Sociedad Anonima (NA-SA) – University of Pisa/GRNSPG” (Contract, 2009), a new RELAP5-3D control system for the boron injection system was developed and implemented in the validated coupled RELAP5-3D/NESTLE model of the Atucha 2 NPP. The aim of this activity is to find out the limiting case (maximum break area size) for the Peak Cladding Temperature for LOCAs under fixed boundary conditions.

  11. DFT investigation of endohedral boron oxide nanocapsules: Encapsulation of He, Ne, Ar, H, N, and Cl atoms

    Energy Technology Data Exchange (ETDEWEB)

    Dabbagh, Hossein A., E-mail: dabbagh@cc.iut.ac.ir [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Zamani, Mehdi [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Farrokhpour, Hossein, E-mail: h-farrokh@cc.iut.ac.ir [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2012-01-17

    Graphical abstract: Electronic structure and stabilization energy of fullerene shape boron oxide nanocapsules (X-B{sub 20}O{sub 30}, X = He, Ne, Ar, H, N, Cl) were calculated at B3LYP/6-31G{sup Asterisk-Operator Asterisk-Operator} level of theory. Encapsulation of B{sub 20}O{sub 30} by dopant atoms does not change the energy and degeneracy of HOMO with the exception of Cl-B{sub 20}O{sub 30}. Highlights: Black-Right-Pointing-Pointer Electronic structure and stabilization energy of fullerene shape boron oxide nanocapsules (X-B{sub 20}O{sub 30}). Black-Right-Pointing-Pointer Encapsulation of He, Ne, Ar, H, N, and Cl atoms. Black-Right-Pointing-Pointer Boron oxide buckyball are potential candidate for gas storage. - Abstract: The electronic structure and stabilization energy of spherical and pyramidal shapes of boron oxide nanocapsules (X-B{sub 20}O{sub 30}, X = He, Ne, Ar, H, N, Cl) were investigated by long-range and dispersion corrected density functional theory (DFT + Disp) including CAM-B3LYP, B3LYP-D3, {omega}B97X-D and B2PLYP-D methods. Based on these calculations, the formation of nanocapsules is an exothermic process (except for Cl-B{sub 20}O{sub 30}). The spherical boron oxide nanocapsules are mainly stabilized by dispersion, while the stability of pyramidal complexes is mainly due to monomer relaxation energy. The theoretical results obtained in this work show that the boron oxide capsule is a good potential candidate for gas storage.

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

    Science.gov (United States)

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

    2013-07-15

    Boron, which is an essential element for plants, is toxic to humans and animals at high concentrations. Layered double hydroxides (LDHs) and thermally activated LDHs have shown good uptake of a range of boron species in laboratory scale experiments when compared to current available methods, which are for the most part ineffective or prohibitively expensive. LDHs were able to remove anions from water by anion exchange, the reformation (or memory) effect and direct precipitation. The main mechanism of boron uptake appeared to be anion exchange, which was confirmed by powder X-ray diffraction (XRD) measurements. Solution pH appeared to have little effect on boron sorption while thermal activation did not always significantly improve boron uptake. In addition, perpetration of numerous LDHs with varying boron anions in the interlayer region by direct co-precipitation and anion exchange have been reported by a number of groups. The composition and orientation of the interlayer boron ions could be identified with reasonable certainty by applying a number of characterisation techniques including: powder XRD, nuclear magnetic resonance spectroscopy (NMR), X-ray photoelectron spectroscopy (XPS) and infrared (IR) spectroscopy. There is still considerable scope for future research on the application of LDHs for the removal of boron contaminants. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Activation and deprotection of F-BODIPYs using boron trihalides.

    Science.gov (United States)

    Lundrigan, Travis; Cameron, T Stanley; Thompson, Alison

    2014-07-07

    The activation of F-BODIPYs with boron trihalides, followed by treatment with a nucleophile, effects facile substitution at boron; using water as the nucleophile promotes deprotective removal of the -BF2 moiety and thereby production of the corresponding parent dipyrrin salt in quantitative yield under extremely mild conditions.

  14. Method for removal of phosgene from boron trichloride

    Science.gov (United States)

    Freund, S.M.

    1983-09-20

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

  15. Finite Element Analysis Of Boron Diffusion In Wood

    DEFF Research Database (Denmark)

    Krabbenhøft, Kristian; Hoffmeyer, Preben; Bechgaard, Carl

    2002-01-01

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

  16. Boron Diffusion in Surface-Treated Framing Lumber

    Science.gov (United States)

    Patricia K. Lebow; Stan T. Lebow; Steven A. Halverson

    2013-01-01

    The extent of boron penetration in framing lumber treated by spray applications during construction is not well quantified. This study evaluated the effect of formulation and concentration on diffusion of boron in lumber specimens that were equilibrated in conditions that produced wood moisture contents of 18 to 21 percent. One set of specimens was pressure treated...

  17. 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.

  18. New applications of the interaction between diols and boronic acids

    NARCIS (Netherlands)

    Duval, F.L.

    2015-01-01

    Florine Duval - New applications of the interaction between diols and boronic acids – Summary Chapter 1 introduces the theory and known applications of the interaction between boronic acids and diols, and explains the context of this thesis. Diagnosis of

  19. Appraisal of SIMS applicability to boron studies in plants.

    Science.gov (United States)

    Dérue, Cedric; Gibouin, David; Verdus, Marie-Claire; Lefebvre, Fabrice; Demarty, Maurice; Ripoll, Camille; Thellier, Michel

    2002-07-15

    In the search for a new methodological approach applicable to the determination of the still poorly known primary role of boron in plant physiology, we have undertaken to appraise the potential of the SIMS method for the analytical imaging of the boron isotopes, (10)B and (11)B, at physiological concentrations in plants. With our own, CAMECA IMS4F SIMS ion analyser, and using O(2)(+) as primary ions for the detection of B(+) (plus (12)C(+) and (40)Ca(+)) secondary ions, we have been able to map quantitatively the two boron isotopes in control and boron-enriched plants, to evaluate boron concentrations at the level of individual cells and to determine boron isotopic ratios. This provides the opportunity to carry out the simultaneous labeling and imaging of boron, using enrichment with the stable isotopes, (10)B and (11)B. The method has also the potential for the simultaneous, quantitative detection of the boron isotopes and of the borate-binding sites in plant cells. Copyright 2002 Wiley-Liss, Inc.

  20. Feasibility study of SMART core with soluble boron

    International Nuclear Information System (INIS)

    Kim, Kang Seog; Lee, Chung Chan; Zee, Sung Quun

    2000-11-01

    The excess reactivity of SMART core without soluble boron is effectively controlled by 49 CEDM. We suggest another method to control the core excess reactivity using both the checkerboard type of 25 CEDM and soluble boron and perform a feasibility calculation. The soluble boron operation is categorized into the on-line and the off-line mechanisms. The former is to successively control the boron concentration according to the excess reactivity during operation and the latter is to add and change some soluble boron during refueling and repairing. Since the on-line soluble boron control system of SMART is conceptually identical to that of the commercial pressurized water reactor, we did not perform the analysis. Since the soluble boron in the complete off-line system increases the moderator temperature coefficient, the reactivity defect between hot and cold moderator temperature is decreased. However, the decrease of the reactivity is not big to satisfy the core reactivity limits. When using 25 CEDM, the possible mechanism is to control the excess reactivity by both control rod and on-line boron control mechanism between cold and hot zero power and by only control rod at hot full power. We selected the loading pattern satisfying the requirement in the view of nuclear design

  1. Effect of boron on growth criteria of some wheat cultivars

    Directory of Open Access Journals (Sweden)

    Ashraf Metwally

    2012-01-01

    Full Text Available Introduction: Toxic soil concentrations of the essential micronutrient boron (B represent major limitations to crop production worldwide. Plants have a range of defense systems that might be involved in their affinity to resist and tolerate nutrients stress.Materials and methods: The experiments were carried out to study the differential responses in five wheat cultivars to boron toxicity. Results: The fresh and dry matter yield of the test wheat cultivars showed marked decrease as the concentration of boron was increased. Elevated concentration of boron had a notable inhibitory effect on the biosynthesis of pigments fractions in the test wheat cultivars as severely as dry matter gain. The adverse concentration effects of boron on some metabolic responses were clearly displayed by shoot and root systems, exhibited in the elevated rates of proline, hydrogen peroxide and malondialdehyde formation. Potassium leakage was severely affected by boron-stress in some cultivars at all tested concentrations, while in some others a moderate damage was manifested only at the higher boron concentrations.Conclusions: Sakha 93 out of all the different cultivars investigated was found to display the lowest sensitivity to boron-stress, while Gemmeza 9 was the most sensitive one.

  2. Production of boron carbide powder by carbothermal synthesis of ...

    Indian Academy of Sciences (India)

    TECS

    weight armour plates etc (Alizadeh et al 2004). It can also be used as a reinforcing material for ceramic matrix composites. It is an excellent neutron absorption material in nuclear industry due to its high neutron absorption co- efficient (Sinha et al 2002). Boron carbide can be prepared by reaction of elemental boron and ...

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

    International Nuclear Information System (INIS)

    2002-01-01

    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 [ru

  4. Production of boron carbide powder by carbothermal synthesis of ...

    Indian Academy of Sciences (India)

    TECS

    Production of boron carbide powder by carbothermal synthesis of gel material. A K KHANRA. Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur 721 302, India. MS received 21 August 2006; revised 29 January 2007. Abstract. Boron carbide (B4C) powder has been produced ...

  5. Research on weed species for phytoremediation of boron polluted soil

    African Journals Online (AJOL)

    STORAGESEVER

    2009-09-15

    Sep 15, 2009 ... This research was aimed to investigate the application of weed species for phytoremediation of soil polluted with boron. A greenhouse experiment was conducted to study the effect of increasing boron. (B) application on the growth and B uptake of common weed species, Sorghum halepense L. Pers.,.

  6. Comparison of boron and neon damage effects in boron ion-implanted resistors

    International Nuclear Information System (INIS)

    MacIver, B.A.

    1975-01-01

    Boron and neon damage implants were used in fabricating integrated-circuit resistors in silicon. Resistor properties were studied as functions of damaging ion species and dose. Sheet resistances in the 10 000 Ω/square range were obtained with low temperature and voltage sensitivities and d.c. isolation. (author)

  7. Isotopic Enrichment of Boron in the Sputtering of Boron Nitride with Xenon Ions

    Science.gov (United States)

    Ray, P. K.; Shutthanandan, V.

    1998-01-01

    An experimental study is described to measure the isotopic enrichment of boron. Xenon ions from 100 eV to 1.5 keV were used to sputter a boron nitride target. An ion gun was used to generate the ion beam. The ion current density at the target surface was approximately 30 microA/sq cm. Xenon ions impinged on the target surface at 50 deg angle to the surface normal. Since boron nitride is an insulator, a flood electron gun was used in our experiments to neutralize the positive charge buildup on the target surface. The sputtered secondary ions of boron were detected by a quadrupole mass spectrometer. The spectrometer entrance aperture was located perpendicular to the ion beam direction and 10 mm away from the target surface. The secondary ion flux was observed to be enriched in the heavy isotopes at lower ion energies. The proportion of heavy isotopes in the sputtered secondary ion flux was found to decrease with increasing primary ion energy from 100 to 350 eV. Beyond 350 eV, light isotopes were sputtered preferentially. The light isotope enrichment factor was observed to reach an asymptotic value of 1.27 at 1.5 keV. This trend is similar to that of the isotopic enrichment observed earlier when copper was sputtered with xenon ions in the same energy range.

  8. Synthesis of boron nitride from boron containing poly(vinyl alcohol ...

    Indian Academy of Sciences (India)

    acid or borax, and a nitrogen-containing compound such as melamine, urea or dicyandiamide are heated in an atmo- sphere of non-oxidizing gas such as nitrogen or ammonia. ∗. Author for correspondence (mitun@cgcri.res.in). These h-BN powders have low crystallinity and crystal- lographically it belongs to boron nitride ...

  9. Synthesis of boron nitride from boron containing poly(vinyl alcohol)

    Indian Academy of Sciences (India)

    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 ...

  10. From boron analogues of amino acids to boronated DNA: potential new pharmaceuticals and neutron capture agents

    International Nuclear Information System (INIS)

    Spielvogel, B.F.; Sood, Anup; Duke Univ., Durham, NC; Shaw, B.R.; Hall, I.H.

    1991-01-01

    Isoelectronic and isostructural boron analogues of the α-amino acids ranging from simple glycine analogues such as H 3 NBH 2 COOH and Me 2 NHBH 2 COOH to alanine analogues have been synthesised. A diverse variety of analogues, including precursors and derivatives (such as peptides) have potent pharmacological activity, including anticancer, antiinflammatory, analgesic, and hypolipidemic activity in animal model studies and in vitro cell cultures. Boronated nucleosides and (oligo)nucleotides, synthetic oligonucleotide analogues of ''antisense'' agents interact with a complementary nucleic acid sequence blocking the biological effect of the target sequence. Nucleosides boronated on the pyrimidine and purine bases have been prepared. It has been established that an entirely new class of nucleic acid derivatives is feasible in which one of the non-bridging oxygens in the internucleotide phosphodiester linkage can be replaced by an isoelectronic analogue, the borane group, (BH 3 ). The boronated oligonucleotides can be viewed as hybrids of the normal oxygen oligonucleotides and the methylphosphonate oligonucleotides. (author)

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

    Science.gov (United States)

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

    2015-01-01

    The Cosmetic Ingredient Review Expert Panel (Panel) assessed the safety of boron nitride which functions in cosmetics as a slip modifier (ie, it has a lubricating effect). Boron nitride is an inorganic compound with a crystalline form that can be hexagonal, spherical, or cubic; the hexagonal form is presumed to be used in cosmetics. The highest reported concentration of use of boron nitride is 25% in eye shadow formulations. Although boron nitride nanotubes are produced, boron nitride is not listed as a nanomaterial used in cosmetic formulations. The Panel reviewed available chemistry, animal data, and clinical data and concluded that this ingredient is safe in the present practices of use and concentration in cosmetic formulations. © The Author(s) 2015.

  12. Boron effect on stainless steel plasticity under hot deformation

    International Nuclear Information System (INIS)

    Bulat, S.I.; Kardonov, B.A.; Sorokina, N.A.

    1978-01-01

    The effect of boron on plasticity of stainless steels at temperatures of hot deformation has been studied at three levels of alloying, i.e. 0-0.01% (micro-alloying or modifying), 0.01-0.02% (low alloying) and 0.02-2.0% (high alloying). Introduction of 0.001-0.005% of boron increases hot plasticity of both low and high carbon stainless steels due to decrease in grain size and strengthening of grain boundaries. Microalloying by boron has a positive effect at temperatures below 1200-1220 deg C. At higher temperatures, particularly when its content exceeds 0.008%, boron deteriorates plasticity by increasing the size of grains and weakening their boundaries. 0.1-2% boron strengthen the stainless steel and dectease its plasticity

  13. Fracture toughness of borides formed on boronized ductile iron

    International Nuclear Information System (INIS)

    Sen, Ugur; Sen, Saduman; Koksal, Sakip; Yilmaz, Fevzi

    2005-01-01

    In this study, fracture toughness properties of boronized ductile iron were investigated. Boronizing was realized in a salt bath consisting of borax, boric acid and ferro-silicon. Boronizing heat treatment was carried out between 850 and 950 deg. C under the atmospheric pressure for 2-8 h. Borides e.g. FeB, Fe 2 B formed on ductile iron was verified by X-ray diffraction (XRD) analysis, SEM and optical microscope. Experimental results revealed that longer boronizing time resulted in thicker boride layers. Optical microscope cross-sectional observation of borided layers showed dentricular morphology. Both microhardness and fracture toughness of borided surfaces were measured via Vickers indenter. The harnesses of borides formed on the ductile iron were in the range of 1160-2140 HV 0.1 and fracture toughness were in the range of 2.19-4.47 MPa m 1/2 depending on boronizing time and temperature

  14. Metal-Free Boron-Containing Heterogeneous Catalysts.

    Science.gov (United States)

    Fang, Yuanxing; Wang, Xinchen

    2017-12-04

    Metal-free catalysts have distinct advantages over metal and metal oxide catalysts, such as lower cost as well as higher reliability and sustainability. Among the nonmetal compounds used in catalysis, boron-containing compounds with a few unique properties have been developed. In this Minireview, the recent advances in the field of boron-containing metal-free catalysts are presented, including binary and ternary boron-containing catalytic materials. Additionally, the three main applications in catalysis are considered, namely, electrocatalysis, thermal catalysis, and photocatalysis, with the role of boron discussed in depth for each specific catalytic application. Boron-containing compounds could have a substantial impact on the field of metal-free catalysts in the future. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Problems and possibilities of development of boron nitride ceramics

    International Nuclear Information System (INIS)

    Rusanova, L.N.; Romashin, A.G.; Kulikova, G.I.; Golubeva, O.P.

    1988-01-01

    The modern state of developments in the field of technology of ceramics produced from boron nitride is analyzed. Substantial difficulties in production of pure ceramics from hexagonal and wurtzite-like boron nitride are stated as related to the structure peculiarities and inhomogeneity of chemical bonds in elementary crystal cells of various modifications. Advantages and disadvantages of familiar technological procedures in production of boron nitride ceramics are compared. A new technology is suggested, which is based on the use of electroorganic compounds for hardening and protection of porous high-purity boron-nitride die from oxidation, and as high-efficient sintered elements for treatment of powders of various structures and further pyrolisis. The method is called thermal molecular lacing (TML). Properties of ceramics produced by the TML method are compared with characteristics of well-known brands of boron nitride ceramics

  16. Density functional calculations of hydrogen adsorption on boron nanotubes and boron sheets

    Science.gov (United States)

    Cabria, I.; López, M. J.; Alonso, J. A.

    2006-02-01

    Hydrogen adsorption on the recently discovered boron nanotubes, BNTs, and on boron sheets is investigated by density functional calculations. Both molecular physisorption and dissociative atomic chemisorption are considered. The geometric and electronic structures of BNTs and boron sheets have been elucidated. These two novel boron structures present buckled surfaces with alternating up and down rows of B atoms, with a large buckling height of about 0.8 Å. The buckled structures are about 0.20 eV/atom more stable than the corresponding flat ones. However, the helicity of some BNTs does not allow for the formation of alternating up and down B rows in the surface and, therefore, these nanotubes have flat surfaces. The buckled and flat nanostructures have different geometric and bonding characteristics, but both are metallic. Molecular hydrogen physisorption energies are about 30-60 meV/molecule on boron sheets and nanotubes, actually lower than in graphene and in carbon nanotubes and far from the energies of 300-400 meV/molecule necessary for efficient hydrogen storage at room temperature and moderate pressures for onboard automotive applications. Chemisorption binding energies on BNTs are about 2.4-2.9 eV/H atom, similar to the ones obtained in CNTs. Finally, the energy barrier from molecular physisorption to dissociative chemisorption of hydrogen is about 1.0 eV /molecule. Therefore, the calculations predict physisorption as the leading adsorption mechanism of hydrogen at moderate temperatures and pressures. The expected hydrogen adsorption capacity of these novel B materials is even smaller than that of CNTs.

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

    International Nuclear Information System (INIS)

    Lee, Mark W.; Shelly, Kenneth; Kane, Robert R.; Hawthorne, M. Frederick

    2006-01-01

    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)

  18. Meeting the challenge of homogenous boron targeting of heterogeneous tumors for effective boron neutron capture therapy (BNCT)

    International Nuclear Information System (INIS)

    Heber, Elisa M.; Trivillin, Veronica A.; Itoiz, Maria E.; Rebagliati, J. Raul; Batistoni, Daniel; Kreimann, Erica L.; Schwint, Amanda E.; Nigg, David W.; Gonzalez, Beatriz N.

    2006-01-01

    BNCT is a tumor cell targeted radiation therapy. Inadequately boron targeted tumor populations jeopardize tumor control. Meeting the to date unresolved challenge of homogeneous targeting of heterogeneous tumors with effective boron carriers would contribute to therapeutic efficacy. The aim of the present study was to evaluate the degree of variation in boron content delivered by boronophenylalanine (BPA), GB-10 (Na 2 10 B 10 H 10 ) and the combined administration of (BPA+GB-10) in different portions of tumor, precancerous tissue around tumor and normal pouch tissue in the hamster cheek pouch oral cancer model. Boron content was evaluated by ICP-AES. The degree of homogeneity in boron targeting was assessed in terms of the coefficient of variation ([S.D./Mean]x100) of boron values. Statistical analysis of the results was performed by one-way ANOVA and the least significant difference test. GB-10 and GB-10 plus BPA achieved respectively a statistically significant 1.8-fold and 3.3-fold increase in targeting homogeneity over BPA. The combined boron compound administration protocol contributes to homogeneous targeting of heterogeneous tumors and would increase therapeutic efficacy of BNCT by exposing all tumor populations to neutron capture reactions in boron. (author)

  19. The Combined Action of Duplicated Boron Transporters Is Required for Maize Growth in Boron-Deficient Conditions.

    Science.gov (United States)

    Chatterjee, Mithu; Liu, Qiujie; Menello, Caitlin; Galli, Mary; Gallavotti, Andrea

    2017-08-01

    The micronutrient boron is essential in maintaining the structure of plant cell walls and is critical for high yields in crop species. Boron can move into plants by diffusion or by active and facilitated transport mechanisms. We recently showed that mutations in the maize boron efflux transporter ROTTEN EAR (RTE) cause severe developmental defects and sterility. RTE is part of a small gene family containing five additional members ( RTE2 - RTE6 ) that show tissue-specific expression. The close paralogous gene RTE2 encodes a protein with 95% amino acid identity with RTE and is similarly expressed in shoot and root cells surrounding the vasculature. Despite sharing a similar function with RTE , mutations in the RTE2 gene do not cause growth defects in the shoot, even in boron-deficient conditions. However, rte2 mutants strongly enhance the rte phenotype in soils with low boron content, producing shorter plants that fail to form all reproductive structures. The joint action of RTE and RTE2 is also required in root development. These defects can be fully complemented by supplying boric acid, suggesting that diffusion or additional transport mechanisms overcome active boron transport deficiencies in the presence of an excess of boron. Overall, these results suggest that RTE2 and RTE function are essential for maize shoot and root growth in boron-deficient conditions. Copyright © 2017 by the Genetics Society of America.

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

    Science.gov (United States)

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

  1. Determination of nitrogen in boron carbide by instrumental photon activation analysis.

    Science.gov (United States)

    Merchel, Silke; Berger, Achim

    2007-05-01

    Boron carbide is widely used as industrial material, because of its extreme hardness, and as a neutron absorber. As part of a round-robin exercise leading to certification of a new reference material (ERM-ED102) which was demanded by the industry we analysed nitrogen in boron carbide by inert gas fusion analysis (GFA) and instrumental photon activation analysis (IPAA) using the 14N(gamma,n)13N nuclear reaction. The latter approach is the only non-destructive method among all the methods applied. By using photons with energy below the threshold of the 12C(gamma,n)11C reaction, we hindered activation of matrix and other impurities. A recently installed beam with a very low lateral activating flux gradient enabled us to homogeneously activate sample masses of approximately 1 g. Taking extra precautions, i.e. self-absorption correction and deconvolution of the complex decay curves, we calculated a nitrogen concentration of 2260+/-100 microg g-1, which is in good agreement with our GFA value of 2303+/-64 microg g-1. The values are the second and third highest of a rather atypical (non-S-shape) distribution of data of 14 round-robin participants. It is of utmost importance for the certification process that our IPAA value is the only one not produced by inert gas fusion analysis and, therefore, the only one which is not affected by a possible incomplete release of nitrogen from high-melting boron carbide.

  2. 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

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

    International Nuclear Information System (INIS)

    Rámila, Consuelo d.P.; Contreras, Samuel A.; Di Domenico, Camila; Molina-Montenegro, Marco A.; Vega, Andrea; Handford, Michael; Bonilla, Carlos A.

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Rámila, Consuelo d.P. [Departamento de Ingeniería Hidráulica y Ambiental, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, 7820436 Santiago (Chile); Contreras, Samuel A.; Di Domenico, Camila [Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, 7820436 Santiago (Chile); Molina-Montenegro, Marco A. [Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo (Chile); Instituto de Ciencias Biológicas, Universidad de Talca, Avda. Lircay s/n, Talca (Chile); Vega, Andrea [Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, 7820436 Santiago (Chile); Handford, Michael [Departmento de Biología, Facultad de Ciencias, Universidad de Chile, Avenida Las Palmeras 3425, 7800024 Santiago (Chile); Bonilla, Carlos A. [Departamento de Ingeniería Hidráulica y Ambiental, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, 7820436 Santiago (Chile); Centro de Desarrollo Urbano Sustentable (CEDEUS), Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, 7820436 Santiago (Chile); and others

    2016-11-05

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

  5. Study of the boron distribution in pea and alfalfa plants using SSNTD

    International Nuclear Information System (INIS)

    Li Jianming; Inst. for Application of Atomic Energy)" data-affiliation=" (Chinese Academy of Agricultural Sciences, Beijing, BJ (China)> Inst. for Application of Atomic Energy)" >Deng Hongmin

    1988-01-01

    The distribution of boron in pea (Pisum sativum L.) and alfalfa (Medicago sativa L.) was determined by using SSNTD. The results show that boron concentrations in leaves are highest, furthermore boron concentrations of the base leaves are higher than those of the top leaves. Among flower tissues, calyx has the highest boron concentration

  6. Wettability of Pyrolytic Boron Nitride by Aluminum

    Science.gov (United States)

    Chiaramonte, Francis P.; Rosenthal, Bruce N.

    1991-01-01

    The wetting of pyrolytic boron nitride by molten 99.9999 percent pure aluminum was investigated by using the sessile drop method in a vacuum operating at approximately 660 micro-Pa at temperatures ranging from 700 to 1000 C. The equilibrium contact angle decreased with an increase in temperature. For temperatures at 900 C or less, the equilibrium contact angle was greater than 90 deg. At 1000 C a nonwetting-to-wetting transition occurred and the contact angle stabilized at 49 deg.

  7. Fabrication of boron nitride planar field emitters

    Science.gov (United States)

    Yokota, Yuuko; Tagawa, Shigeru; Sugino, Takashi

    1999-05-01

    Boron nitride (BN) films are grown on sapphire substrates by plasma-assisted chemical vapor deposition (PACVD). BN films are doped with sulfur. Insertion of the GaN layer between the BN film and sapphire leads to a tight adhesion of the BN film. The electrical resistivity of the sulfur-doped BN film is reduced to 10 3 Ω cm. The cathode electrode is formed on the BN film and the anode electrode on the sapphire substrate by evaporating Ti and Au. An emission current of 1 μA is obtained at an electric field strength of 16 V/μm.

  8. 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.

  9. Stability analysis of zigzag boron nitride nanoribbons

    International Nuclear Information System (INIS)

    Rai, Hari Mohan; Late, Ravikiran; Saxena, Shailendra K.; Kumar, Rajesh; Sagdeo, Pankaj R.; Jaiswal, Neeraj K.; Srivastava, Pankaj

    2015-01-01

    We have explored the structural stability of bare and hydrogenated zigzag boron nitride nanoribbons (ZBNNRs). In order to investigate the structural stability, we calculate the cohesive energy for bare, one-edge and both edges H-terminated ZBNNRs with different widths. It is found that the ZBNNRs with width Nz=8 are energetically more favorable than the lower-width counterparts (Nz<8). Bare ZBNNRs have been found energetically most stable as compared to the edge terminated ribbons. Our analysis reveals that the structural stability is a function of ribbon-width and it is not affected significantly by the type of edge-passivation (one-edge or both-edges)

  10. Processing of boron carbide-aluminum composites

    International Nuclear Information System (INIS)

    Halverson, D.C.; Pyzik, A.J.; Aksay, I.A.

    1989-01-01

    The processing problems associated with boron carbide and the limitations of its mechanical properties can be significantly reduced when a metal phase (e.g., aluminum) is added. Lower densification temperatures and higher fracture toughness will result. Based on fundamental capillarity thermodynamics, reaction thermodynamics, and densification kinetics, we have established reliable criteria for fabricating B 4 C-Al particulate composites. Because chemical reactions cannot be eliminated, it is necessary to process B 4 C-Al by rapidly heating to near 1200 degrees C (to ensure wetting) and subsequently heat-treating below 1200 degrees C (for microstructural development)

  11. Method for exfoliation of hexagonal boron nitride

    Science.gov (United States)

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

    2012-01-01

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

  12. Synthesis of a boron modified phenolic resin

    Directory of Open Access Journals (Sweden)

    Aparecida M. Kawamoto

    2010-08-01

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

  13. Hydrothermal synthesis of cubic boron nitride crystals

    International Nuclear Information System (INIS)

    Yu Meiyan; Cui Deliang; Kai Li; Yin Yansheng; Wang Qilong; Lei Chu

    2005-01-01

    Cubic boron nitride (cBN) crystals have been successfully synthesized by in situ hydrothermal method. In order to obtain cBN pure phase crystals, two comparative experiments were carried out. The experimental results indicated that compared to one-step in situ hydrothermal method, multi-step in situ hydrothermal method was beneficial to the synthesis of cBN. It is believed that the multi-step in situ hydrothermal method is the optimal route to synthesize pure cBN bulk crystals

  14. Boron carbide nanowires with uniform CNx coatings

    Science.gov (United States)

    Zhang, H. Z.; Wang, R. M.; You, L. P.; Yu, J.; Chen, H.; Yu, D. P.; Chen, Y.

    2007-01-01

    Boron carbide nanowires with uniform carbon nitride coating layers were synthesized on a silicon substrate using a simple thermal process. The structure and morphology of the as-synthesized nanowires were characterized using x-ray diffraction, scanning and transmission electron microscopy and electron energy loss spectroscopy. A correlation between the surface smoothness of the nanowire sidewalls and their lateral sizes has been observed and it is a consequence of the anisotropic formation of the coating layers. A growth mechanism is also proposed for these growth phenomena.

  15. 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)

    Gunduz, G.

    1997-11-01

    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

  16. 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).

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

    Science.gov (United States)

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

    2015-01-01

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

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

    International Nuclear Information System (INIS)

    Sherlock Huang, Lin-Chiang; Hsieh, Wen-Yuan; Chen, Jiun-Yu; Huang, Su-Chin; Chen, Jen-Kun; Hsu, Ming-Hua

    2014-01-01

    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

  20. Flame-photometric determination of boron in alloys with chromatographic separation

    International Nuclear Information System (INIS)

    Telegin, G.F.; Popandopulo, Yu.I.; Grazhuiene, S.S.

    1983-01-01

    A study was made on the possibility of using flame-photometric method for boron determination in iron base alloys. The method of extraction chromatography was used for boron separation from iron. It is possible to reliably determine boron in Fesub(x)Bsub(100-x) alloys only at a concentration ratio of iron to boron <=0.2. The technique for determination of boron in Fesub(x)Bsub(100-x) alloys was developed on the base of the conducted investigation

  1. Flame-photometric determination of boron in alloys with chromatographic separation

    Energy Technology Data Exchange (ETDEWEB)

    Telegin, G.F.; Popandopulo, Yu.I.; Grazhuiene, S.S. (AN SSSR, Chernogolovka. Inst. Fiziki Tverdogo Tela)

    1983-01-01

    A study was made on the possibility of using flame-photometric method for boron determination in iron base alloys. The method of extraction chromatography was used for boron separation from iron. It is possible to reliably determine boron in Fesub(x)Bsub(100-x) alloys only at a concentration ratio of iron to boron <=0.2. The technique for determination of boron in Fesub(x)Bsub(100-x) alloys was developed on the base of the conducted investigation.

  2. 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.

  3. Microdosimetry for Boron Neutron Capture Therapy

    International Nuclear Information System (INIS)

    Maughan, R.L.; Kota, C.

    2000-01-01

    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

  4. Boron modified molybdenum silicide and products

    International Nuclear Information System (INIS)

    Meyer, M.K.; Akinc, M.

    1999-01-01

    A boron-modified molybdenum silicide material is disclosed having the composition comprising about 80 to about 90 weight % Mo, about 10 to about 20 weight % Si, and about 0.1 to about 2 weight % B and a multiphase microstructure including Mo 5 Si 3 phase as at least one microstructural component effective to impart good high temperature creep resistance. The boron-modified molybdenum silicide material is fabricated into such products as electrical components, such as resistors and interconnects, that exhibit oxidation resistance to withstand high temperatures in service in air as a result of electrical power dissipation, electrical resistance heating elements that can withstand high temperatures in service in air and other oxygen-bearing atmospheres and can span greater distances than MoSi 2 heating elements due to improved creep resistance, and high temperature structural members and other fabricated components that can withstand high temperatures in service in air or other oxygen-bearing atmospheres while retaining creep resistance associated with Mo 5 Si 3 for structural integrity. 7 figs

  5. Boron-10 ABUNCL Prototype Initial Testing

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-12-01

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

  6. Transport properties of polycrystalline boron doped diamond

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, J.R. de [Instituto Nacional de Pesquisas Espaciais, INPE/LAS, S.J. Campos, SP 12227-010 (Brazil); Berengue, O.M. [Universidade Estadual Paulista, UNESP Departamento de Física, Guaratinguetá 12.516-410 (Brazil); Moro, J. [Instituto Federal de Educação, Ciência e Tecnologia de São Paulo, Bragança Paulista 12929-600 (Brazil); Ferreira, N.G. [Instituto Nacional de Pesquisas Espaciais, INPE/LAS, S.J. Campos, SP 12227-010 (Brazil); Chiquito, A.J. [Universidade Federal de São Carlos, Departamento de Física, São Carlos 13565-905 (Brazil); Baldan, M.R., E-mail: baldan@las.inpe.br [Instituto Nacional de Pesquisas Espaciais, INPE/LAS, S.J. Campos, SP 12227-010 (Brazil)

    2014-08-30

    Highlights: • Synthetic boron doped diamond films were grown by hot filament chemical vapor deposition. • We characterized the films by hall effects as a function of temperature and magnetic field. • The resistivity was investigated. • The conduction mechanism was dominated by variable range hopping (VRH). - Abstract: The influence of doping level in the electronic conductivity and resistivity properties of synthetic diamond films grown by hot filament chemical vapor deposition (HFCVD) was investigated. Eight different doping level concentrations varied from 500 to 30,000 ppm were considered. The polycrystalline morphology observed by scanning electron microscopy and Raman spectra was strongly affected by the addition of boron. The electric characterization by Hall effect as a function of temperature and magnetic field showed that at sufficiently low temperatures, electrical conduction is dominated by variable range hopping (VRH) conducting process. The resistivity was also investigated by temperature-dependent transport measurements in order to investigate the conduction mechanism in the doped samples. The samples exhibited the VRH (m = 1/4) mechanism in the temperature range from 77 to 300 K. The interface between metal, and our HFCVD diamond was also investigated for the lower doped samples.

  7. Aluminum/boron composite - fatigue life prediction

    International Nuclear Information System (INIS)

    Plumtree, A.; Glinka, G.

    2002-01-01

    The fatigue behaviour of a 6061-0 aluminum alloy reinforce with 0.25 volume fraction undirectional boron fibres of 100 μm diameter has been investigated. The specimens were tested under constant stress amplitude using a stress ratio (minimum/maximum stress) of 0.2 with the fibres oriented at an angle to the loading direction in order to study the matrix dominated fatigue behaviour. Two sets of data were obtained for unidirectional specimens tested with fibre to load axis angles of 200 and 450 A third set of data was obtained with V 45 angle-ply specimens. It is shown that a microstress/strain analysis in conjunction with a multiaxial fatigue parameter can be applied to successfully predict the fatigue lives of these boron reinforced aluminum alloy composites. The multiaxial parameter enables a generalized strain-life relationship to be determined using limited experimental data. Once this generalized relationship is known, the life of the composite cycled under different loads and load-fibre angles can be predicted. (author)

  8. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-04-28

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

  10. No evidence that boron influences tree species distributions in lowland tropical forests of Panama.

    Science.gov (United States)

    Turner, Benjamin L; Zalamea, Paul-Camilo; Condit, Richard; Winter, Klaus; Wright, S Joseph; Dalling, James W

    2017-04-01

    It was recently proposed that boron might be the most important nutrient structuring tree species distributions in tropical forests. Here we combine observational and experimental studies to test this hypothesis for lowland tropical forests of Panama. Plant-available boron is uniformly low in tropical forest soils of Panama and is not significantly associated with any of the > 500 species in a regional network of forest dynamics plots. Experimental manipulation of boron supply to seedlings of three tropical tree species revealed no evidence of boron deficiency or toxicity at concentrations likely to occur in tropical forest soils. Foliar boron did not correlate with soil boron along a local scale gradient of boron availability. Fifteen years of boron addition to a tropical forest increased plant-available boron by 70% but did not significantly change tree productivity or boron concentrations in live leaves, wood or leaf litter. The annual input of boron in rainfall accounts for a considerable proportion of the boron in annual litterfall and is similar to the pool of plant-available boron in the soil, and is therefore sufficient to preclude boron deficiency. We conclude that boron does not influence tree species distributions in Panama and presumably elsewhere in the lowland tropics. No claim to original US government works New Phytologist © 2016 New Phytologist Trust.

  11. Next generation of the self-consistent and environment-dependent Hamiltonian: Applications to various boron allotropes from zero- to three-dimensional structures.

    Science.gov (United States)

    Tandy, P; Yu, Ming; Leahy, C; Jayanthi, C S; Wu, S Y

    2015-03-28

    An upgrade of the previous self-consistent and environment-dependent linear combination of atomic orbitals Hamiltonian (referred as SCED-LCAO) has been developed. This improved version of the semi-empirical SCED-LCAO Hamiltonian, in addition to the inclusion of self-consistent determination of charge redistribution, multi-center interactions, and modeling of electron-electron correlation, has taken into account the effect excited on the orbitals due to the atomic aggregation. This important upgrade has been subjected to a stringent test, the construction of the SCED-LCAO Hamiltonian for boron. It was shown that the Hamiltonian for boron has successfully characterized the electron deficiency of boron and captured the complex chemical bonding in various boron allotropes, including the planar and quasi-planar, the convex, the ring, the icosahedral, and the fullerene-like clusters, the two-dimensional monolayer sheets, and the bulk alpha boron, demonstrating its transferability, robustness, reliability, and predictive power. The molecular dynamics simulation scheme based on the Hamiltonian has been applied to explore the existence and the energetics of ∼230 compact boron clusters BN with N in the range from ∼100 to 768, including the random, the rhombohedral, and the spherical icosahedral structures. It was found that, energetically, clusters containing whole icosahedral B12 units are more stable for boron clusters of larger size (N > 200). The ease with which the simulations both at 0 K and finite temperatures were completed is a demonstration of the efficiency of the SCED-LCAO Hamiltonian.

  12. Next generation of the self-consistent and environment-dependent Hamiltonian: Applications to various boron allotropes from zero- to three-dimensional structures

    Energy Technology Data Exchange (ETDEWEB)

    Tandy, P.; Yu, Ming; Leahy, C.; Jayanthi, C. S.; Wu, S. Y. [Department of Physics and Astronomy, University of Louisville, Louisville, Kentucky 40292 (United States)

    2015-03-28

    An upgrade of the previous self-consistent and environment-dependent linear combination of atomic orbitals Hamiltonian (referred as SCED-LCAO) has been developed. This improved version of the semi-empirical SCED-LCAO Hamiltonian, in addition to the inclusion of self-consistent determination of charge redistribution, multi-center interactions, and modeling of electron-electron correlation, has taken into account the effect excited on the orbitals due to the atomic aggregation. This important upgrade has been subjected to a stringent test, the construction of the SCED-LCAO Hamiltonian for boron. It was shown that the Hamiltonian for boron has successfully characterized the electron deficiency of boron and captured the complex chemical bonding in various boron allotropes, including the planar and quasi-planar, the convex, the ring, the icosahedral, and the fullerene-like clusters, the two-dimensional monolayer sheets, and the bulk alpha boron, demonstrating its transferability, robustness, reliability, and predictive power. The molecular dynamics simulation scheme based on the Hamiltonian has been applied to explore the existence and the energetics of ∼230 compact boron clusters B{sub N} with N in the range from ∼100 to 768, including the random, the rhombohedral, and the spherical icosahedral structures. It was found that, energetically, clusters containing whole icosahedral B{sub 12} units are more stable for boron clusters of larger size (N > 200). The ease with which the simulations both at 0 K and finite temperatures were completed is a demonstration of the efficiency of the SCED-LCAO Hamiltonian.

  13. Next generation of the self-consistent and environment-dependent Hamiltonian: Applications to various boron allotropes from zero- to three-dimensional structures

    International Nuclear Information System (INIS)

    Tandy, P.; Yu, Ming; Leahy, C.; Jayanthi, C. S.; Wu, S. Y.

    2015-01-01

    An upgrade of the previous self-consistent and environment-dependent linear combination of atomic orbitals Hamiltonian (referred as SCED-LCAO) has been developed. This improved version of the semi-empirical SCED-LCAO Hamiltonian, in addition to the inclusion of self-consistent determination of charge redistribution, multi-center interactions, and modeling of electron-electron correlation, has taken into account the effect excited on the orbitals due to the atomic aggregation. This important upgrade has been subjected to a stringent test, the construction of the SCED-LCAO Hamiltonian for boron. It was shown that the Hamiltonian for boron has successfully characterized the electron deficiency of boron and captured the complex chemical bonding in various boron allotropes, including the planar and quasi-planar, the convex, the ring, the icosahedral, and the fullerene-like clusters, the two-dimensional monolayer sheets, and the bulk alpha boron, demonstrating its transferability, robustness, reliability, and predictive power. The molecular dynamics simulation scheme based on the Hamiltonian has been applied to explore the existence and the energetics of ∼230 compact boron clusters B N with N in the range from ∼100 to 768, including the random, the rhombohedral, and the spherical icosahedral structures. It was found that, energetically, clusters containing whole icosahedral B 12 units are more stable for boron clusters of larger size (N > 200). The ease with which the simulations both at 0 K and finite temperatures were completed is a demonstration of the efficiency of the SCED-LCAO Hamiltonian

  14. INFLUENCE OF MICROALLOYING BY BORON ON HARDENABILITY OF STEEL

    Directory of Open Access Journals (Sweden)

    E. P. Baradyntseva

    2016-01-01

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

  15. Electrophoretic deposition of boron-10 in neutron detectors electrodes

    International Nuclear Information System (INIS)

    Oliveira Sampa, M.H. de; Vinhas, L.A.; Vieira, J.M.

    1990-01-01

    Process of boron-10 electrophoresis on large area of aluminum substrates was developed with the aim of using them in the construction of neutron detectors. After definition and optimization of the boron electrophoresis parameters, depositions of boron-10 on aluminum cylinders were performed and used as electrodes in gamma compensated and non-compensated ionization chambers and in proportional detectors. These prototypes were designed and builded at IPEN-CNEN-SP, and submited for characterization tests at IEA-R1 reactor, and they fulfil the technical specifications of the project. (author) [pt

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

    International Nuclear Information System (INIS)

    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. (orig.) [de

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

    Science.gov (United States)

    Grady, Dennis E.

    2015-04-01

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

  18. 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.

  19. Photoelectron spectroscopy of boron aluminum hydride cluster anions.

    Science.gov (United States)

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Gantefoer, Gerd; Bowen, Kit H; Li, Xiang; Kiran, Boggavarapu; Kandalam, Anil K

    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, BxAlyHz(-), 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.

  20. Coordination Networks Based on Boronate and Benzoxaborolate Ligands

    Directory of Open Access Journals (Sweden)

    Saad Sene

    2016-05-01

    Full Text Available Despite the extensive range of investigations on boronic acids (R-B(OH2, some aspects of their reactivity still need to be explored. This is the case for the coordination chemistry of boronate anions (R-B(OH3−, which has only recently been started to be studied. The purpose of this review is to summarize some of the key features of boronate ligands (and of their cyclic derivatives, benzoxaborolates in materials: (i coordination properties; (ii spectroscopic signatures; and (iii emerging applications.

  1. Kinetics of chemical vapor deposition of boron on molybdenum

    International Nuclear Information System (INIS)

    Tanaka, W.; Nakaanishi, N.; Kato, E.

    1987-01-01

    Experimental rate data of chemical vapor deposition of boron by reduction of boron trichloride with hydrogen are analyzed to determine the reaction mechanism. The reaction orders with respect to the partial pressures of hydrogen and boron trichloride are one half and one third, respectively. It has been found that the outer layer of a deposited film is Mo/sub 2/B/sub 5/ and the inner layer is MoB by the use of X-ray diffraction and EPMA line analysis

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

    Science.gov (United States)

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

    2017-04-01

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

  3. First Principles Atomistic Model for Carbon-Doped Boron Suboxide

    Science.gov (United States)

    2014-09-01

    Sutherland DG, Van Buuren T, Carlisle JA, Terminello LJ, Himpsel FJ. Photoemission and x - ray -absorption study of boron carbide and its surface thermal...along the C-C chain. If the interstitial dopant is either B or C, a local boron carbide (B4C)-like structure with either a C-B-C or C-C-C chain is...strength, high oxidation resistance (򒱰 °C), and chemical inertness.1–8 However, unlike other high-performance ceramics, boron carbide (B4C) and

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

    Directory of Open Access Journals (Sweden)

    Chaofeng Dai

    2010-08-01

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

  5. 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.

  6. On certain topological indices of boron triangular nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Aslam, Adnan [Univ. of Engineering and Technology, Lahore (Pakistan). Dept. of Natural Sciences and Humanities; Ahmad, Safyan [GC Univ. Lahore (Pakistan). Abdus Salam School of Mathematical Sciences; Gao, Wei [Yunnan Normal Univ., Kunming (China). School of Information Science and Technology

    2017-11-01

    The topological index gives information about the whole structure of a chemical graph, especially degree-based topological indices that are very useful. Boron triangular nanotubes are now replacing usual carbon nanotubes due to their excellent properties. We have computed general Randic (R{sub a}), first Zagreb (M{sub 1}) and second Zagreb (M{sub 2}), atom-bond connectivity (ABC), and geometric-arithmetic (GA) indices of boron triangular nanotubes. Also, we have computed the fourth version of atom-bond connectivity (ABC{sub 4}) and the fifth version of geometric-arithmetic (GA{sub 5}) indices of boron triangular nanotubes.

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

    International Nuclear Information System (INIS)

    Slack, G.A.; Rosolowski, J.H.; Miller, M.L.; Huseby, I.C.

    1984-12-01

    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 B 68 Y, α-B 12 Al, B 4 C, and B 6 Si are described. Transition metals appear to be effective dopants for B 68 Y and B 4 C

  8. Genotypic effects on boron concentrations and response on boron fertilization in maize inbred lines

    Directory of Open Access Journals (Sweden)

    Andrić Luka

    2016-01-01

    Full Text Available Boron (B deficiency in maize can result in barren cobs attributed to silks being nonreceptive which is particularly important for the female parent in seed production. The objectives of this study were 1 to investigate genotypic differences among nine female inbred lines used in seed production for B concentration in ear-leaf and grain, as well as for grain yield and moisture in a three-year experiment (2006-2008 and 2 to determine response and relations among the traits when four of the female inbred lines are treated by foliar boron fertilization - three times in 10-days interval with 0.5% Solubor solution (17.5% B during one growing season (2008. The investigations were performed on Experimental field of Agricultural Institute Osijek, (soil type: eutrical cambisol. Highly significant differences among the nine female inbred lines were detected for B concentration in ear-leaf (from 14.7 to 46.7 mg B kg-1 and grain (from 1.20 to 2.06 mg B kg-1 as well as for grain yield (from 3.33 to 4.83 t ha-1 and grain moisture (from 14.7% to 26.6%. However, there were also significant effects of growing season and the genotype by environment interaction for all four traits. Positive and moderate correlations were found between the boron status in plant and grain yield. Although B concentrations were considerably increased by foliar boron fertilization (averages 41.7 and 125.3 mg B kg-1 in leaves, 1.79 and 2.80 mg B kg-1 in grain, for control and fertilization, respectively, in general grain yield differences among treatments were non-significant. (averages 5.21 and 5.15 t ha-1, respectively.

  9. Genotypic effects on boron concentrations and response on boron fertilization in maize inbred lines

    OpenAIRE

    Andrić Luka; Kovačević Vlado; Kadar Imre; Jambrović Antun; Plavšić Hrvoje; Šimić Domagoj

    2016-01-01

    Boron (B) deficiency in maize can result in barren cobs attributed to silks being nonreceptive which is particularly important for the female parent in seed production. The objectives of this study were 1) to investigate genotypic differences among nine female inbred lines used in seed production for B concentration in ear-leaf and grain, as well as for grain yield and moisture in a three-year experiment (2006-2008) and 2) to determine response and relation...

  10. Simultaneous Disulfide and Boronic Acid Ester Exchange in Dynamic Combinatorial Libraries

    DEFF Research Database (Denmark)

    Diemer, Sanna L.; Kristensen, Morten; Rasmussen, Brian

    2015-01-01

    combinatorial libraries (DCLs) ensuring thermodynamic control over the system. If more than one reversible reaction operates in a single dynamic combinatorial library, the complexity of the system increases dramatically, and so does its possible applications. One can imagine two reversible reactions...... that operate simultaneously or two reversible reactions that operate independently. Both these scenarios have advantages and disadvantages. In this contribution, we show how disulfide exchange and boronic ester transesterification can function simultaneous in dynamic combinatorial libraries under appropriate...... conditions. We describe the detailed studies necessary to establish suitable reaction conditions and highlight the analytical techniques appropriate to study this type of system....

  11. Segregation of boron implanted into silicon on angular configurations of silicon/silicon dioxide oxidation interface

    CERN Document Server

    Tarnavskij, G A; Obrekht, M S

    2001-01-01

    One studies segregation of boron implanted into silicon when a wave (interface) of oxidation moves within it. There are four types of angular configurations of SiO sub 2 /Si oxidation interface, that is: direct and reverse shoulders, trench type cavities and a square. By means of computer-aided simulation one obtained and analyzed complex patterns of B concentration distribution within Si, SiO sub 2 domains and at SiO sub 2 /Si interface for all types of angular configurations of the oxidation interface

  12. Palladium-catalyzed cross-coupling reactions of aryl boronic acids with aryl halides in water.

    Science.gov (United States)

    Wang, Shaoyan; Zhang, Zhiqiang; Hu, Zhizhi; Wang, Yue; Lei, Peng; Chi, Haijun

    2009-01-01

    An efficient Suzuki cross-coupling reaction using a variety of aryl halides in neat water was developed. The Pd-catalyzed reaction between aryl bromides or chlorides and phenyl boronic acids was compatible with various functional groups and affords biphenyls in good to excellent yields without requirement of organic cosolvents. The air stability and solubility in water of the palladium-phosphinous acid complexes were considered to facilitate operation of the coupling reaction and product isolation. The reaction conditions including Pd catalyst selection, temperature, base and catalyst recoverability were also investigated.

  13. Determination of boron-containing compounds in urine and blood plasma from boron neutron capture therapy patients. The importance of using coupled techniques.

    Science.gov (United States)

    Svantesson, Eva; Capala, Jacek; Markides, Karin E; Pettersson, Jean

    2002-10-15

    The necessity of using coupled techniques to analyze samples from boron neutron capture therapy (BNCT) patients prior to element-specific detection has been demonstrated. BNCT patients were infused with p-boronophenylalanine (BPA)-fructose complex before the therapy started. Urine and blood plasma samples were collected at different times after the start of the BPA administration and were run on a porous graphitic carbon column coupled on-line to an inductively coupled plasma-atomic emission spectrometer (ICP-AES) and an ICP time-of-flight mass spectrometer (TOF-MS). In addition to BPA, a possible metabolite to BPA and some minor boron-containing compounds, eluting close to the front, were also found in the urine and plasma samples. Because only the total concentration of boron has been measured so far in earlier studies, the suspected metabolite could not be detected, and this is the first report indicating its presence in urine and plasma of BNCT patients. The abundance of 10B in urine was about the same for BPA and its possible metabolite (98-99%). The ratio between the possible metabolite and BPA was found to differ in the urine from different patients. Most of the patients had a metabolite concentration of approximately 10 mol % of the BPA content in their urine 5-11 h after the start of the BPA administration. This ratio increased to between 30 and 80% when 24 h had passed. The ratio of metabolite to BPA was found to be lower in the plasma than in the urine samples at comparable time after the start of BPA infusion. Preliminary results from micro-LC-electrospray ionization (ESI)-MS/MS measurements on four urine samples indicate that the metabolite has a higher mass than BPA.

  14. B-decachloro-o-carborane derivatives as suitable boron carriers for the preparation of water-soluble boron-conjugated macromolecules

    International Nuclear Information System (INIS)

    Gabel, D.; Walczyna, R.; Wellmann, F.; Riesenberg, H.; Hocke, I.

    1982-01-01

    The preparation of boron-containing macromolecules, especially immunoglobulins, for boron neutron capture therapy, has so far been rather unsuccessful, because of the increased water insolubility of heavily substituted proteins. By using polar boron compounds, some of the difficulties previously encountered in the preparation of boron-conjugated immunoglobulins might be overcome. To this end, the authors have investigated the use of B-decachloro-o-carborane (B 10 Cl 10 C 2 H 2 ) for the preparation of water-soluble macromolecules

  15. Novel boron channel-based structure of boron carbide at high pressures

    Science.gov (United States)

    Zhang, Xinxin; Zhao, Yu; Zhang, Miao; Liu, Hanyu; Yao, Yansun; Cheng, Taimin; Chen, Hui

    2017-11-01

    Boron carbide (B4C) is one of the hardest materials known to date. The extreme hardness of B4C arises from architecturally efficient B12 or B11C icosahedrons and strong inter-icosahedral B-C bonding. As an excellent material for use in ballistic armor, the mechanic limit of B4C and possible phase transitions under extreme stress conditions are of great interest. Here we systematically explored the post-icosahedral solid structures of B4C under high pressure, using an unbiased structure search method. A new structure composed of extended framework of B and zigzag chains of C is predicted to be stable above 96 GPa. The new structure was predicted to have a high Vickers hardness of 55 GPa and simultaneously to retain a metallic ground state. The exceptional mechanical properties found in this structure are attributed to strong sp 3 covalent network formed under extreme pressure conditions. The predicted structure represents a new type of superhard boron carbides that form under high pressure without the presence of boron icosahedrons, which encourages experimental exploration in this direction.

  16. Biocompatibility of functionalized boron phosphate (BPO4) nanoparticles for boron neutron capture therapy (BNCT) application.

    Science.gov (United States)

    Achilli, Cesare; Grandi, Stefania; Ciana, Annarita; Guidetti, Gianni F; Malara, Alessandro; Abbonante, Vittorio; Cansolino, Laura; Tomasi, Corrado; Balduini, Alessandra; Fagnoni, Maurizio; Merli, Daniele; Mustarelli, Piercarlo; Canobbio, Ilaria; Balduini, Cesare; Minetti, Giampaolo

    2014-04-01

    Boron neutron capture therapy (BNCT) is a radiotherapy treatment based on the accumulation in the tumor of a (10)B-containing drug and subsequent irradiation with low energy neutrons, which bring about the decay of (10)B to (7)Li and an α particle, causing the death of the neoplastic cell. The effectiveness of BNCT is limited by the low delivery and accumulation of the used boron-containing compounds. Here we report the development and the characterization of BPO4 nanoparticles (NPs) as a novel possible alternative drug for BNCT. An extensive analysis of BPO4 NP biocompatibility was performed using both mature blood cells (erythrocytes, neutrophils and platelets) and a model of hematopoietic progenitor cells. A time- and concentration-dependent cytotoxicity study was performed on neoplastic coloncarcinoma and osteosarcoma cell lines. BPO4 functionalization with folic acid, introduced to improve the uptake by tumor cells, appeared to effectively limit the unwanted effects of NPs on the analyzed blood components. Boron neutron capture therapy (BNCT) is a radiotherapy treatment modality based on the accumulation of a (10)B-containing drug and subsequent irradiation with low energy neutrons, inducing the decay of (10)B to (7)Li and an α particle, causing neoplastic cell death. This team of authors reports on a folic acid functionalized BPO4 nanoparticle with improved characteristics compared with conventional BNCT approaches, as demonstrated in tumor cell lines, and hopefully to be followed by translational human studies. © 2014.

  17. Microstructure and some properties of boron modified graphite USB-15

    Science.gov (United States)

    Chernikov, V. N.; Alimov, V. Kh.; Gorodetsky, A. E.; Sharapov, V. M.; Zakharov, A. P.; Kurolenkin, E. I.

    1992-09-01

    Boronized graphites, in particular USB-15, have some unique properties which make them applicable in thermonuclear confinement experiments. The optimization of USB-15 manufacture technology demands more detailed knowledge of its properties and, first of all, its microstructure. In this connection microstructure of USB-15 was studied in detail by means of X-ray diffraction, microanalysis, analytical TEM, SEM and other methods, both in original state and after annealing at 2300, 2700 and 3100 K. The erosion resistance to low energy bombardment from deuterium plasma was investigated between 350 and 900 K. In the course of 3 keV D +-ion implantation up to a dose ~ 5 × 10 20 D + m -2 deuterium is mainly trapped in vacancy complexes, which were studied by means of TDS and deuterium profiling using SIMS and RGA. The ratio of CD 4 to D 2 molecules emitted from USB-15 during post-implantation thermal desorption is considerably less than that from other types of graphites, indicating that the recombination desorption of deuterium is greatly enhanced by B in solid solution. Summary is given on property evolution of USB-15 (before and after thermal treatment) as a result of irradiation up to a fast neutron fluence ( E > 0.18 MeV) of 2.5 × 10 25 n m -2 in a temperature range 360-1100 K. Thermal annealing of USB-15 in the range 2200-2400 K is recommended for improvement of its thermal strength and radiation stability.

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

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  19. Photoelectron spectra and electronic structure of nitrogen analogues of boron β-diketonates with aromatic substituents

    Energy Technology Data Exchange (ETDEWEB)

    Tikhonov, Sergey A., E-mail: allser@bk.ru [Far Eastern Federal University, 8 Sukhanova St., Vladivostok, 690950 (Russian Federation); Vovna, Vitaliy I. [Far Eastern Federal University, 8 Sukhanova St., Vladivostok, 690950 (Russian Federation); Borisenko, Aleksandr V. [Vladivostok Branch of Russian Customs Academy, 16v Strelkovaya St., Vladivostok, 690034 (Russian Federation)

    2016-11-15

    Highlights: • The electronic structures of three nitrogen analogues of boron β-diketonates have been investigated. • UV photoelectron spectra have been interpreted. • The structure of the UV photoelectron spectra is in good agreement with the energies and compositions of Kohn-Sham orbitals. - Abstract: The electronic structure of three nitrogen analogoues of boron β-diketonates containing aromatic substituents was studied by the ultraviolet photoelectron spectroscopy and within the density functional theory. In order to determine effects of heteroatom substitution in the chelate ligand, a comparative analysis was carried out for the electronic structure of three model compounds. In a range of model compounds, the HOMO's nature was revealed to be the same. The HOMO-1 orbital of nitrogen containing compounds is determined by the presence of lone electron pairs of nitrogen. In a range of the complexes under study, the influence of aromatic substituents on the electronic structure was defined. In the imidoylamidinate complex, in contrast to formazanates and β-diketonates, it was found the absence of any noticeable mixing of π-orbitals of the chelate and benzene rings. It was shown that within energy range to 11 eV, the calculated results reproduce well the energy differences between the ionized states of complexes.

  20. Study of the interaction of boron-containing amino acids for the neutron capture therapy with biologically interesting compounds by using 'three-spot zone electrophoresis'

    International Nuclear Information System (INIS)

    Kitaoka, Yoshinori; Kobayashi, Mitsue; Morimoto, Tsuguhiro; Kirihata, Mitsunori; Ichimoto, Itsuo.

    1995-01-01

    As the boron carriers for boron neutron capture therapy, p-borono phenylalanine (BPA) is the boron compound which has been clinically used together with sodium borocaptate. It was found by the electrophoresis behavior that the BPA interacted with organic carboxylic acids in its dissolved state. In this paper, the electrophoresis behavior of general amino acids as seen in three-spot zone electrophoresis and the peculiar interaction of the amino acids having dihydroxyboryl radical are described. Zone electrophoresis has been developed as separation means, and three-spot process excludes the errors due to accidental factors as far as possible. The behaviors of zone electrophoresis of ordinary neutral amino acids, orthoboric acid and p-BPA are reported. For utilizing the features of boron neutron capture therapy, it is necessary to develop the carrier which is singularly taken into cancer cells. There is not a good method for discriminating normal cells and cancer cells. As for the administration of BPA to patients, its solubility is insufficient, therefore, its fructose complex has been used. The research on the biochemical peculiarity of boron is important. (K.I.)

  1. Synthesis and in-vivo detection of boronated compounds for use in BNCT. Final progress report, August 1, 1989--April 30, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Kabalka, G.W.

    1993-08-01

    Carboranes contain ten boron atoms in a three-dimensional space equivalent to a benzene ring; consequently, the carborane isomers can be utilized to prepare a variety of boron-rich agents for potential use in boron-neutron capture therapy. We developed synthetic methodology suitable for use with carboranes preparing amino acids and other physio-logically active compounds of potential use in BNCT. The methodology involves the conversion of simple carboranes into more complex, reactive organometallic reagents which can then be utilized to prepare agents which will target the nuclei of tumor cells. Specific examples include the projected syntheses of boron analogs of known intercolators such as Diazaquone (AZQ) which have been proven effectiveness in chemotherapy. We have also synthesized and carried out biodistribution studies of gadolinium labeled liposomes (GLL) which were developed in our laboratory. Gadolinium like boron-10, has an excellent neutron cross section and is considered to be of potential use in neutron capture therapy. GLL are constructed by adding gadolinium based amphiphiles.

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

    Science.gov (United States)

    Feingold, E.

    1967-01-01

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

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

    Science.gov (United States)

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

    2010-02-03

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

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

    Science.gov (United States)

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

    2013-01-01

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

  5. Plasmonic Properties of Silicon Nanocrystals Doped with Boron and Phosphorus.

    Science.gov (United States)

    Kramer, Nicolaas J; Schramke, Katelyn S; Kortshagen, Uwe R

    2015-08-12

    Degenerately doped silicon nanocrystals are appealing plasmonic materials due to silicon's low cost and low toxicity. While surface plasmonic resonances of boron-doped and phosphorus-doped silicon nanocrystals were recently observed, there currently is poor understanding of the effect of surface conditions on their plasmonic behavior. Here, we demonstrate that phosphorus-doped silicon nanocrystals exhibit a plasmon resonance immediately after their synthesis but may lose their plasmonic response with oxidation. In contrast, boron-doped nanocrystals initially do not exhibit plasmonic response but become plasmonically active through postsynthesis oxidation or annealing. We interpret these results in terms of substitutional doping being the dominant doping mechanism for phosphorus-doped silicon nanocrystals, with oxidation-induced defects trapping free electrons. The behavior of boron-doped silicon nanocrystals is more consistent with a strong contribution of surface doping. Importantly, boron-doped silicon nanocrystals exhibit air-stable plasmonic behavior over periods of more than a year.

  6. Plasma Spray Synthesis of High Purity Boron Nitride Nanotubes

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this project is the efficient synthesis of high quality boron nitride nanotubes (BNNT’s) using the LaRC radio frequency plasma spray (RFPS)...

  7. Anesthetic management of Boron Neutron Capture Therapy for glioblastoma

    International Nuclear Information System (INIS)

    Shinomura, T.; Furutani, H.; Osawa, M.; Ono, K.; Fukuda, K.

    2000-01-01

    General anesthesia was given to twenty-seven patients who received Boron Neutron Capture Therapy (BNCT) under craniotomy at Kyoto University Research Reactor from 1991 to 1999. Special considerations are required for anesthesia. (author)

  8. Microstructural characterization aluminium alloys from the addition of boron

    International Nuclear Information System (INIS)

    Nunes, A.G.P.; Pipano, T.F.; Mota, M.A.; Mariano, N.A.; Ramos, E.C.T.

    2014-01-01

    In the electrical industry, the aluminum becomes attractive because it has excellent characteristics for transmitting electricity. The liquid aluminum has in its composition transition elements (zirconium, titanium, vanadium and chromium) that interfere negatively on the quality of the product. The addition of aluminum-boron alloys have been used to remove transition metals through the formation of borides, enabling an increase in electrical conductivity. However, no detailed reports of reactions between boron, transition metals and primary aluminum engines. However, the objective is to determine the stoichiometric composition that enables an increase in electrical conductivity of an aluminum alloy. Samples with different concentrations of boron were characterized by optical emission spectrometry, electrical conductivity and X-ray diffraction. The addition of boron in excess reduces the time in the formation of borides, and enable an increase in electrical conductivity. (author)

  9. Spectrographic determination of traces of boron in steels

    International Nuclear Information System (INIS)

    Alduan, F.A.; Roca, M.

    1976-01-01

    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: CuF 2 , LiF, NaF, and SrF 2 . CuF 2 , 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)

  10. Fractionation of Boron Isotopes in Icelandic Hydrothermal Systems

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-01-01

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

  11. Preliminary evaluation of boron release and biological resistance of ...

    African Journals Online (AJOL)

    DOT) and a commercial water repellent compound. Leachates sampled from the leaching cycles for 10 days and extracts from treated wood specimens were analyzed for boron content. Treated wood specimens were exposed to wood degrading ...

  12. Effect of Boronization on Ohmic Plasmas in NSTX

    International Nuclear Information System (INIS)

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

    2001-01-01

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

  13. Preparation of boron nitride fiber by organic precursor method

    Directory of Open Access Journals (Sweden)

    Yingying Zhou

    Full Text Available In this paper, boron nitride polymer precursor was made by boric acid, melamine, twelve sodium alkyl sulfate as raw materials and pure water as medium which is heated to 70 °C. Boron nitride precursor polymer was soluble in formic acid solution. The boron nitride precursor can be electrostatically spun at the voltage in 23 kV and the distance between the positive and negative poles is 15 cm. The formed fiber is very uniform. The properties of the precursors were analyzed through electron microscope, infrared spectrum, X-ray and ultraviolet spectrum. The aim of the job is to got the precursor of BN and spun it. Keywords: Melamine, Boric acid, Boron nitride precursor, Electrostatic spinning

  14. Calculation of local boron dilution accidents with the Hextran code

    International Nuclear Information System (INIS)

    Kyrki-Rajamaeki, R.; Stenius, T.

    1995-01-01

    Possibilities of Reactivity Initiated Accidents (RIA) due to local boron dilution slugs entering the core of PWRs have been widely studied in recent years. In Finland the main analysis tool for reactor dynamics RIA calculations has been the three dimensional HEXTRAN code which also includes full circuit models. Reliable calculation of propagating boron fronts is very difficult with standard numerical algorithms because numerical diffusion tends to smoothen the front. Thus the reactivity effect of the boron dilution can be significantly lowered and conservatism of the analyses cannot be guaranteed. In normal flow conditions this problem has been avoided in HEXTRAN analyses by simulating the dilution front directly to the core inlet. In natural circulation conditions there occurs significant numerical diffusion even during the propagation of boron front inside the core. Therefore a new hydraulics solution method PLIM (Piecewise Linear Interpolation Method) has been applied to HEXTRAN. Examples are given of analyses made with HEXTRAN in both flow conditions

  15. Anesthetic management of Boron Neutron Capture Therapy for glioblastoma

    Energy Technology Data Exchange (ETDEWEB)

    Shinomura, T.; Furutani, H.; Osawa, M.; Ono, K.; Fukuda, K. [Kyoto Univ. (Japan)

    2000-10-01

    General anesthesia was given to twenty-seven patients who received Boron Neutron Capture Therapy (BNCT) under craniotomy at Kyoto University Research Reactor from 1991 to 1999. Special considerations are required for anesthesia. (author)

  16. Isotopic compositions of boron in sediments and their implications

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; Yingkai, X.

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

  17. Spectrophotometric Determination of Boron in Environmental Water Samples

    International Nuclear Information System (INIS)

    San San; Khin Win Kyi; Kwaw Naing

    2002-02-01

    The present paper deals with the study on the methods for the determination of boron in the environmental water samples. The standard methods which are useful for this determination are discussed thoroughly in this work. Among the standard methods approved by American Public Health Association, the carmine method was selected for this study. Prior to the determination of boron in the water samples, the precision and accuracy of the methods of choice were examined by using standard boron solutions. The determination of Boron was carried out by using water samples, waste water from Aquaculture Research Centre, University of Yangon, the Ayeyarwady River water near Magway Myathalon Pagoda in Magway Division, ground water from Sanchaung Township, and tap water from Universities' Research Centre, University of Yangon. Analyses of these water samples were done and statistical treatment of the results was carried out. (author)

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

    International Nuclear Information System (INIS)

    Petrman, I.; Safek, V.

    1994-01-01

    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

  19. Defect characteristics by boron cluster ion implantation

    International Nuclear Information System (INIS)

    Aoki, Takaaki; Matsuo, Jiro; Takaoka, Gikan; Toyoda, Noriaki; Yamada, Isao

    2003-01-01

    Cluster ion implantation using decaborane (B 10 H 14 ) has been proposed as a shallow implantation technique for LSI devices with gate lengths of several-tens nanometers. Experiments and computer simulations of low-energy boron monomers and decaborane clusters implantation were performed. Molecular dynamics simulations of B 10 cluster implantation have shown similar implant depth but different damage density and damage structure compared to monomer (B 1 ) ion implantation with the same energy-per-atom. For monomer implantation, point-defects such as vacancy-interstitial pairs are mainly formed. On the other hand, B 10 generates large numbers of defects within a highly-amorphised region at the impact location. This difference in damage structure produced during implantation is expected to cause different annihilation processes

  20. Boronic acids for fluorescence imaging of carbohydrates.

    Science.gov (United States)

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

    2016-02-28

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

  1. Calculation of inherent boron dilution scenarios

    International Nuclear Information System (INIS)

    Kereszturi, A.; Toth, E.L.; Telbisz, M.; Trosztel, I.

    1999-01-01

    Two inherent boron dilution scenarios have been investigated in the frame of the PH2.08 PHARE project supported by the EC[1]. The Small Break LOCA (SBLOCA) initiating event was investigated by the SMABRE[2] and ATHLET[3] codes, while the SMATRA[4] code was used for the study of an ATWS initiating event. The results show that in case of SBLOCA slug formation is possible if the operator starts to cool down the secondary loop but the slug does not enter the core because it is removed by the Low Pressure Safety Injection. In case of ATWS, it was concluded that the maximum void fraction in the hot leg remained below 95% and that there was sufficient water in the two-phase flow to prevent formation of un borated slugs. Furthermore at the time the condensation of steam was already impossible in the steam generators because of drying out. (Authors)

  2. Enhanced reactivity of boron, through adding nano-aluminum and wet ball milling

    Science.gov (United States)

    Zhang, Baoyun; Huang, Chuan; Yan, Shi; Li, Yanchun; Cheng, Yi

    2013-12-01

    Boron is a significant component of energetic materials due to its high energy release on both a mass and volumetric basis. However, due to long-term exposure in air, boron is easily oxidized to form thick surface oxidation layer which significantly decreases the activity of boron. In this study, we demonstrate the wet high-energy milling method to purify the long-term storage boron and assemble the nanoaluminum and boron together to improve the activity of boron. The results show that after wet ball milling, the surface of boron particles becomes rough, and the aluminum is uniformly distributed on the surface of boron observed by scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS), respectively. Determined by simultaneous thermal analysis thermogravimetric-differential scanning calorimetric (TG-DSC) in oxygen, the heat release of boron is 444% higher than the boron without any processing. Combustion analyses of delay compositions consisting of boron powder with and without wet ball milling combined with barium dichromate were conducted to study the reactivity activity. The result shows that the average combustion rate for delay composition containing functionalization boron is 2.4 to 3.4 times than the others containing common boron. Overall, our work demonstrates that wet ball milling with adding nanoaluminum can be used an effective method to improve the reactivity activity of long-storage boron.

  3. Enhanced reactivity of boron, through adding nano-aluminum and wet ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Baoyun; Huang, Chuan [School of Chemical Engineering, Nanjing University of Science and Technology, Xiao lingwei 200, Nanjing 210094 (China); Yan, Shi [School of Optoelectronics, Beijing Institute of Technology, Nanjing 210094 (China); Li, Yanchun, E-mail: ychunli@gmail.com [School of Chemical Engineering, Nanjing University of Science and Technology, Xiao lingwei 200, Nanjing 210094 (China); Cheng, Yi [School of Chemical Engineering, Nanjing University of Science and Technology, Xiao lingwei 200, Nanjing 210094 (China)

    2013-12-01

    Boron is a significant component of energetic materials due to its high energy release on both a mass and volumetric basis. However, due to long-term exposure in air, boron is easily oxidized to form thick surface oxidation layer which significantly decreases the activity of boron. In this study, we demonstrate the wet high-energy milling method to purify the long-term storage boron and assemble the nanoaluminum and boron together to improve the activity of boron. The results show that after wet ball milling, the surface of boron particles becomes rough, and the aluminum is uniformly distributed on the surface of boron observed by scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS), respectively. Determined by simultaneous thermal analysis thermogravimetric–differential scanning calorimetric (TG–DSC) in oxygen, the heat release of boron is 444% higher than the boron without any processing. Combustion analyses of delay compositions consisting of boron powder with and without wet ball milling combined with barium dichromate were conducted to study the reactivity activity. The result shows that the average combustion rate for delay composition containing functionalization boron is 2.4 to 3.4 times than the others containing common boron. Overall, our work demonstrates that wet ball milling with adding nanoaluminum can be used an effective method to improve the reactivity activity of long-storage boron.

  4. Helium behaviour in implanted boron carbide

    Directory of Open Access Journals (Sweden)

    Motte Vianney

    2015-01-01

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

  5. Folate Functionalized Boron Nitride Nanotubes and their Selective Uptake by Glioblastoma Multiforme Cells: Implications for their Use as Boron Carriers in Clinical Boron Neutron Capture Therapy.

    Science.gov (United States)

    Ciofani, Gianni; Raffa, Vittoria; Menciassi, Arianna; Cuschieri, Alfred

    2008-11-25

    Boron neutron capture therapy (BNCT) is increasingly being used in the treatment of several aggressive cancers, including cerebral glioblastoma multiforme. The main requirement for this therapy is selective targeting of tumor cells by sufficient quantities of (10)B atoms required for their capture/irradiation with low-energy thermal neutrons. The low content of boron targeting species in glioblastoma multiforme accounts for the difficulty in selective targeting of this very malignant cerebral tumor by this radiation modality. In the present study, we have used for the first time boron nitride nanotubes as carriers of boron atoms to overcome this problem and enhance the selective targeting and ablative efficacy of BNCT for these tumors. Following their dispersion in aqueous solution by noncovalent coating with biocompatible poly-l-lysine solutions, boron nitride nanotubes were functionalized with a fluorescent probe (quantum dots) to enable their tracking and with folic acid as selective tumor targeting ligand. Initial in vitro studies have confirmed substantive and selective uptake of these nanovectors by glioblastoma multiforme cells, an observation which confirms their potential clinical application for BNCT therapy for these malignant cerebral tumors.

  6. Folate Functionalized Boron Nitride Nanotubes and their Selective Uptake by Glioblastoma Multiforme Cells: Implications for their Use as Boron Carriers in Clinical Boron Neutron Capture Therapy

    Directory of Open Access Journals (Sweden)

    Ciofani Gianni

    2008-01-01

    Full Text Available Abstract Boron neutron capture therapy (BNCT is increasingly being used in the treatment of several aggressive cancers, including cerebral glioblastoma multiforme. The main requirement for this therapy is selective targeting of tumor cells by sufficient quantities of10B atoms required for their capture/irradiation with low-energy thermal neutrons. The low content of boron targeting species in glioblastoma multiforme accounts for the difficulty in selective targeting of this very malignant cerebral tumor by this radiation modality. In the present study, we have used for the first time boron nitride nanotubes as carriers of boron atoms to overcome this problem and enhance the selective targeting and ablative efficacy of BNCT for these tumors. Following their dispersion in aqueous solution by noncovalent coating with biocompatible poly-l-lysine solutions, boron nitride nanotubes were functionalized with a fluorescent probe (quantum dots to enable their tracking and with folic acid as selective tumor targeting ligand. Initial in vitro studies have confirmed substantive and selective uptake of these nanovectors by glioblastoma multiforme cells, an observation which confirms their potential clinical application for BNCT therapy for these malignant cerebral tumors.

  7. Folate-conjugated boron nitride nanospheres for targeted delivery of anticancer drug

    Directory of Open Access Journals (Sweden)

    Feng S

    2016-09-01

    Full Text Available Shini Feng,1 Huijie Zhang,1 Ting Yan,1 Dandi Huang,1 Chunyi Zhi,2 Hideki Nakanishi,1 Xiao-Dong Gao1 1Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, People’s Republic of China; 2Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR, People’s Republic of China Abstract: With its unique physical and chemical properties and structural similarity to carbon, boron nitride (BN has attracted considerable attention and found many applications. Biomedical applications of BN have recently started to emerge, raising great hopes in drug and gene delivery. Here, we developed a targeted anticancer drug delivery system based on folate-conjugated BN nanospheres (BNNS with receptor-mediated targeting. Folic acid (FA was successfully grafted onto BNNS via esterification reaction. In vitro cytotoxicity assay showed that BNNS-FA complexes were non-toxic to HeLa cells up to a concentration of 100 µg/mL. Then, doxorubicin hydrochloride (DOX, a commonly used anticancer drug, was loaded onto BNNS-FA complexes. BNNS-FA/DOX complexes were stable at pH 7.4 but effectively released DOX at pH 5.0, which exhibited a pH sensitive and sustained release pattern. BNNS-FA/DOX complexes could be recognized and specifically internalized by HeLa cells via FA receptor-mediated endocytosis. BNNS-FA/DOX complexes exhibited greater cytotoxicity to HeLa cells than free DOX and BNNS/DOX complexes due to the increased cellular uptake of DOX mediated by the FA receptor. Therefore, BNNS-FA complexes had strong potential for targeted cancer therapy. Keywords: boron nitride nanospheres, folic acid, doxorubicin, targeted delivery, cancer therapy

  8. Thin boron phosphide coating as a corrosion-resistant layer

    Science.gov (United States)

    Not Available

    1982-08-25

    A surface prone to corrosion in corrosive environments is rendered anticorrosive by CVD growing a thin continuous film, e.g., having no detectable pinholes, thereon, of boron phosphide. In one embodiment, the film is semiconductive. In another aspect, the invention is an improved photoanode, and/or photoelectrochemical cell with a photoanode having a thin film of boron phosphide thereon rendering it anticorrosive, and providing it with unexpectedly improved photoresponsive properties.

  9. Modeling solid-state boron carbide low energy neutron detectors

    International Nuclear Information System (INIS)

    Lundstedt, C.; Harken, A.; Day, E.; Robertson, B.W.; Adenwalla, S.

    2006-01-01

    Two independent techniques for modeling boron-based solid-state neutron detectors are presented-one using the GEANT4 Monte Carlo toolkit and the other one an analytical approach using a simplified physical model. Results of these techniques are compared for three different types of solid-state boron carbide detector. These results provide the basis for distinguishing between conversion layer and other solid-state detectors

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

    KAUST Repository

    Zeboudji, B.

    2013-04-01

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

  11. Application of the boron autoradiography in structural steels

    International Nuclear Information System (INIS)

    Azevedo, A.L.T. de

    1984-01-01

    The development of boron containing steels requires a knowledge of the microstructural state of that element, determined by the competition between precipitation and solution.An example of the use of the autoradiographic method for obtaining boron distribution images is described and showed. The technique is based on an α emitting nuclear reaction, which leaves a latent track in cellulose. This detector material is revealed by chemical etching and observed by optical and electron transmission microscopy. (Author) [pt

  12. Self-assembly of boron-based supramolecular structures

    OpenAIRE

    Christinat, Nicolas

    2008-01-01

    This work describes the synthesis and characterization of boronic acid-based supramolecular structures. Macrocycles, dendritic structures, polymers, rotaxanes, and cages were assembled using four types of reversible reactions. The key point of the strategy is the parallel utilization of two –or more– of these reactions. Initially, aryl and alkylboronic acids were condensed with dihydroxypyridine ligands to give tetrameric or pentameric macrocycles, in which four or five boronate esters are co...

  13. Effect of boron on growth criteria of some wheat cultivars

    OpenAIRE

    Ashraf Metwally; Rasha El-Shazoly; Afaf Mohamed Hamada

    2012-01-01

    Introduction: Toxic soil concentrations of the essential micronutrient boron (B) represent major limitations to crop production worldwide. Plants have a range of defense systems that might be involved in their affinity to resist and tolerate nutrients stress.Materials and methods: The experiments were carried out to study the differential responses in five wheat cultivars to boron toxicity. Results: The fresh and dry matter yield of the test wheat cultivars showed marked decrease as the conc...

  14. Lateral boron distribution in polycrystalline SiC source materials

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  15. Infrared reflectiity and transmissivity of boron implanted, laser annealed silicon

    International Nuclear Information System (INIS)

    Engstrom, H.

    1979-01-01

    The mid-infrared reflectance and transmittance of boron implanted, laser annealed silicon was measured. A Drude model of free holes was used to obtain the dielectric constant of the implanted layer. A least squares adjustment of (1) the ratio of boron concentration to effective hole mass; and (2) the relaxation time gave a fairly good fit to the data and permitted determination of these parameters

  16. NEUTRON IRRADIATION EFFECTS ON SPARK PLASMA SINTERED BORON CARBIDE

    OpenAIRE

    Buyuk, Bulent; Cengiz, Meral; Tugrul, A. Beril

    2015-01-01

    In this study, spark plasma sintered boron carbide (B4C) was examined against neutrons. The specimens were irradiated by reactor neutrons (include both thermal and fast neutrons) up to fluence of 1.37x1021n m-2. Thermal and fast neutrons cause swelling by different interactions with boron (10B) atoms in the related materials. X-Ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images were investigated for initial and irradiated samples. In addition, lattice parameters and ...

  17. Disorder and defects are not intrinsic to boron carbide

    OpenAIRE

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

    2016-01-01

    A unique combination of useful properties in boron-carbide, such as extreme hardness, excellent fracture toughness, a low density, a high melting point, thermoelectricity, semi-conducting behavior, catalytic activity and a remarkably good chemical stability, makes it an ideal material for a wide range of technological applications. Explaining these properties in terms of chemical bonding has remained a major challenge in boron chemistry. Here we report the synthesis of fully ordered, stoichio...

  18. The boron filter for the ROSAT X-ray telescope

    Science.gov (United States)

    Stephan, K.-H.; Schmitt, J. H. M. M.; Snowden, S. L.; Maier, H. J.; Frischke, D.

    1991-05-01

    We have developed multilayered films composed of boron carbide and carbon, which serve as spectral filters in the focal plane of the Wolter type I X-ray telescope on board the X-ray astronomy satellite ROSAT (Röntgensatellit). We describe the manufacturing process and qualification measurements of the filters and present the resulting performance data. Finally the pulse height spectrum of the active star AR Lac observed by ROSAT with and without boron filter will be shown.

  19. Universal reaction mechanism of boronic acids with diols in aqueous solution: kinetics and the basic concept of a conditional formation constant.

    Science.gov (United States)

    Furikado, Yuki; Nagahata, Tomomi; Okamoto, Takuya; Sugaya, Tomoaki; Iwatsuki, Satoshi; Inamo, Masahiko; Takagi, Hideo D; Odani, Akira; Ishihara, Koji

    2014-10-06

    To establish a detailed reaction mechanism for the condensation between a boronic acid, RB(OH)2, and a diol, H2L, in aqueous solution, the acid dissociation constants (Ka(BL)) of boronic acid diol esters (HBLs) were determined based on the well-established concept of conditional formation constants of metal complexes. The pKa values of HBLs were 2.30, 2.77, and 2.00 for the reaction systems, 2,4-difluorophenylboronic acid and chromotropic acid, 3-nitrophenylboronic acid and alizarin red S, and phenylboronic acid and alizarin red S, respectively. A general and precise reaction mechanism of RB(OH)2 with H2L in aqueous solution, which can serve as a universal reaction mechanism for RB(OH)2 and H2L, was proposed on the basis of (a) the relative kinetic reactivities of the RB(OH)2 and its conjugate base, that is, the boronate ion, toward H2L, and (b) the determined pKa values of HBLs. The use of the conditional formation constant, K', based on the main reaction: RB(OH)2 + H2L (K1)⇌ RB(L)(OH)(-) + H3O(+) instead of the binding constant has been proposed for the general reaction of uncomplexed boronic acid species (B') with uncomplexed diol species (L') to form boronic acid diol complex species (esters, BL') in aqueous solution at pH 5-11: B' + L' (K')⇌ BL'. The proposed reaction mechanism explains perfectly the formation of boronic acid diol ester in aqueous solution. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Defect-Based Modulation of Optoelectronic Properties for Biofunctionalized Hexagonal Boron Nitride Nanosheets.

    Science.gov (United States)

    Shakourian-Fard, Mehdi; Heydari, Hadiseh; Kamath, Ganesh

    2017-09-06

    Defect engineering potentially allows for dramatic tuning of the optoelectronic properties of two-dimensional materials. With the help of DFT calculations, a systematic study of DNA nucleobases adsorbed on hexagonal boron-nitride nanoflakes (h-BNNFs) with boron (V B ) and nitrogen (V N ) monovacancies is presented. The presence of V N and V B defects increases the binding strength of nucleobases by 9 and 34 kcal mol -1 , respectively (h-BNNF-V B >h-BNNF-V N >h-BNNF). A more negative electrostatic potential at the V B site makes the h-BNNF-V B surface more reactive than that of h-BNNF-V N , enabling H-bonding interactions with nucleobases. This binding energy difference affects the recovery time-a significant factor for developing DNA biosensors-of the surfaces in the order h-BNNF-V B >h-BNNF-V N >h-BNNF. The presence of V B and V N defect sites increases the electrical conductivity of the h-BNNF surface, V N defects being more favorable than V B sites. The blueshift of absorption peaks of the h-BNNF-V B -nucleobase complexes, in contrast to the redshift observed for h-BNNF-V N -nucleobase complexes, is attributed to their observed differences in binding energies, the HOMO-LUMO energy gap and other optoelectronic properties. Time-dependent DFT calculations reveal that the monovacant boron-nitride-sheet-nucleobase composites absorb visible light in the range 300-800 nm, thus making them suitable for light-emitting devices and sensing nucleobases in the visible region. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Hydrolytic Stability of Boronate Ester-Linked Covalent Organic Frameworks

    KAUST Repository

    Li, Huifang

    2018-01-30

    The stability of covalent organic frameworks (COFs) is essential to their applications. However, the common boronate ester-linked COFs are susceptible to attack by nucleophiles (such as water molecules) at the electron-deficient boron sites. To provide an understanding of the hydrolytic stability of the representative boronate ester-linked COF-5 and of the associated hydrolysis mechanisms, density functional theory (DFT) calculations were performed to characterize the hydrolysis reactions of the molecule formed by the condensation of 1,4-phenylenebis(boronic acid) (PBBA) and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) monomers; two cases were considered, one dealing with the freestanding molecule and the other with the molecule interacting with COF layers. It was found that the boronate ester (B–O) bond dissociation, which requires one H2O molecule, has a relatively high energy barrier of 22.3 kcal mol−1. However, the presence of an additional H2O molecule significantly accelerates hydrolysis by reducing the energy barrier by a factor of 3. Importantly, the hydrolysis of boronate ester bonds situated in a COF environment follows reaction pathways that are different and have increased energy barriers. These results point to an enhanced hydrolytic stability of COF-5 crystals.

  2. Boronization study for application to large helical device

    Science.gov (United States)

    Noda, N.; Sagara, A.; Yamada, H.; Kubota, Y.; Inoue, N.; Akaishi, K.; Motojima, O.; Iwamoto, K.; Hashiba, M.; Fujita, I.; Hino, T.; Yamashina, T.; Okazaki, K.; Rice, J.; Yamage, M.; Toyoda, H.; Sugai, H.

    1995-04-01

    An experimental device named SUT ( SUrface modification Teststand) was constructed for a boronization study. An ultra high vacuum (UHV) condition, a changeable high temperature liner and in situ AES are three distinctive feature of the SUT device. Saturation density of oxygen atoms was as large as 1.2 × 10 17/cm 2 on a boronized surface, whereas 1.5 × 10 16/cm 2 on a bare stainless steel surface. It is found by AES analysis that the oxygen-contained layer was as thick as 50 nm from the top surface of the boron film. From such a large oxygen-saturation density, we expect that the oxygen-gettering ability of the boronized surface is likely to be maintained during one-day experiment of LHD. The oxygen-saturation behavior was quite similar between the boronized surfaces obtained with decaborane and diborane, which indicates that, as a working gas of the boronization, the decaborane works well compared with diborane, as far as oxygen gettering is concerned.

  3. Preparation of in-house graphite reference material for boron

    International Nuclear Information System (INIS)

    Kumar, Sanjukta A.; Venkatesh, K.; Swain, Kallola K.; Manisha, V.; Kamble, Granthali S.; Pandey, Shailaja P.; Remya Devi, P.S.; Ghosh, M.; Verma, R.

    2016-05-01

    Graphite is extensively used in nuclear technology. Boron concentration in graphite is one of the important parameters that decide its acceptability for nuclear applications. Reliable analytical methods are essential for the determination of boron in graphite at concentration about 5 mg kg -1 . Reference materials are used for validation of existing analytical methods and developing new methodologies. In view of the importance of determination of boron in graphite and unavailability of graphite reference material, an In-house graphite reference material was prepared in Analytical Chemistry Division. Graphite source material was procured, processed to obtain powder of ≤ 75 μm (200 mesh) and bottled. Procedures were developed for the determination of boron in graphite using inductively coupled plasma optical emission spectrometry (ICPOES) and inductively coupled plasma mass spectrometry (ICPMS) techniques. Homogeneity testing was carried out on the bottled units and boron content along with the combined and expanded uncertainties were established. The assigned boron concentration in the In-house graphite reference material is (7.3±0.46) mg kg -1 . (author)

  4. Boron isotope fractionation in column chromatography with glucamine type fibers

    International Nuclear Information System (INIS)

    Sonoda, Akinari; Makita, Yoji; Hirotsu, Takahiro

    2008-01-01

    Glucamine type polymers have specific affinity toward boric acid and borate ion. Among them, Chelest Fiber GRY-L showed larger fractionation for boron isotopes than other polymers in our previous study. For this study, we used Chelest Fibers with different fiber lengths (1.0 mm, 0.5 mm, and 0.3 mm) as column packing materials to perform chromatographic separation of boron isotopes. The shorter fiber has larger packing density when packed into the column using a dry method. The 0.3-mm-long fiber has a larger backpressure than fibers of other lengths. Boron adsorption capacities were measured using the breakthrough operation. At this time, the 0.5-mm-long fiber showed the highest capacity. When we measured the isotope ratio profile for fibers of different length using column chromatography, 0.5-mm-long fibers displayed the highest boron isotope fractionation. The 0.5-mm-long fiber is promising as a packing material of column chromatography for boron isotope separation. We also changed operation methods. The lower eluent concentration and the slower flow rate are suitable for boron isotope separation. (author)

  5. Neutron sensitivity improvement in boron-lined proportional counters

    International Nuclear Information System (INIS)

    Dighe, P.M.; Prasad, K.R.; Kataria, S.K.

    2002-01-01

    Various techniques have been employed to improve the neutron sensitivity of boron-coated proportional counters developed indigenously. A boron-lined proportional counter (67 mm ID x 750 mm length) of 17 cps/nv thermal neutron sensitivity is developed by coating 92% enriched 10 B on the inner wall of the counter. This counter can be used for low thermal neutron flux (∼0.2 nv) at various applications such as neutron area monitoring, reactor start-up instrumentation, assay of fissile materials and detection of fuel failure. An improvement in sensitivity was also achieved by summing the output signals from four 10 B lined counters and two BF 3 proportional counters. The summation did not change the susceptibility of the device to gamma interference. In view of the scarcity of enriched 10 B isotope, indigenously available natural boron coated two prototype proportional counters are developed of 0.8 cps/nv and 1.1 cps/nv thermal neutron sensitivity. Efforts have been made to improve the sensitivity with boron coated 3-dimensional structures introduced into the sensitive volume. Tests in thermal neutron flux showed 50% improvement in the sensitivity due to the introduction of additional boron coated wires. Another counter with 51 boron-coated annular discs (23 mm OD X 10 mm ID X 1 mm thick) mounted perpendicular to the axis of the cathode showed 1.7 cps/nv neutron sensitivity, an improvement by a factor of 2.5. (author)

  6. 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.

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

    Science.gov (United States)

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

    2006-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Vast, N

    1999-07-01

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

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  10. Influence of boron content on the morphological, spectral, and electroanalytical characteristics of anodically oxidized boron-doped diamond electrodes

    Czech Academy of Sciences Publication Activity Database

    Schwarzová-Pecková, K.; Vosáhlová, J.; Barek, J.; Šloufová, I.; Pavlova, Ewa; Petrák, Václav; Zavázalová, J.

    2017-01-01

    Roč. 243, 20 July (2017), s. 170-182 ISSN 0013-4686 R&D Projects: GA TA ČR(CZ) TE01020118 Institutional support: RVO:61389013 ; RVO:68378271 Keywords : 2-aminobiphenyl * boron content * boron-doped diamond Subject RIV: CD - Macromolecular Chemistry; CG - Electrochemistry (FZU-D) OBOR OECD: Polymer science; Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) (FZU-D) Impact factor: 4.798, year: 2016

  11. Application of bisphosphomide-palladium (II) pincer complex in ...

    Indian Academy of Sciences (India)

    The bisphosphomide-based pincer complex [PdBr{2,6-{Ph2PC(O)}2(C6H3)}] (2) has shown very high catalytic activity in Suzuki-Miyaura cross coupling reaction under microwave irradiation for a variety of aryl bromides and aryl boronic acids. The complex showed the same efficiency for gram scale reactions.

  12. 1H and 10B NMR and MRI investigation of boron- and gadolinium–boron compounds in boron neutron capture therapy

    International Nuclear Information System (INIS)

    Bonora, M.; Corti, M.; Borsa, F.; Bortolussi, S.; Protti, N.; Santoro, D.; Stella, S.; Altieri, S.; Zonta, C.; Clerici, A.M.; Cansolino, L.; Ferrari, C.; Dionigi, P.; Porta, A.; Zanoni, G.; Vidari, G.

    2011-01-01

    10 B molecular compounds suitable for Boron Neutron Capture Therapy (BNCT) are tagged with a Gd(III) paramagnetic ion. The newly synthesized molecule, Gd-BPA, is investigated as contrast agent in Magnetic Resonance Imaging (MRI) with the final aim of mapping the boron distribution in tissues. Preliminary Nuclear Magnetic Resonance (NMR) measurements, which include 1 H and 10 B relaxometry in animal tissues, proton relaxivity of the paramagnetic Gd-BPA molecule in water and its absorption in tumoral living cells, are reported.

  13. 1H and 10B NMR and MRI investigation of boron- and gadolinium-boron compounds in boron neutron capture therapy.

    Science.gov (United States)

    Bonora, M; Corti, M; Borsa, F; Bortolussi, S; Protti, N; Santoro, D; Stella, S; Altieri, S; Zonta, C; Clerici, A M; Cansolino, L; Ferrari, C; Dionigi, P; Porta, A; Zanoni, G; Vidari, G

    2011-12-01

    (10)B molecular compounds suitable for Boron Neutron Capture Therapy (BNCT) are tagged with a Gd(III) paramagnetic ion. The newly synthesized molecule, Gd-BPA, is investigated as contrast agent in Magnetic Resonance Imaging (MRI) with the final aim of mapping the boron distribution in tissues. Preliminary Nuclear Magnetic Resonance (NMR) measurements, which include (1)H and (10)B relaxometry in animal tissues, proton relaxivity of the paramagnetic Gd-BPA molecule in water and its absorption in tumoral living cells, are reported. Copyright © 2011 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2013-11-01

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

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

    Science.gov (United States)

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

    2016-11-05

    Phytoremediation is a promising technology to tackle boron toxicity, which restricts agricultural activities in many arid and semi-arid areas. Puccinellia frigida is a perennial grass that was reported to hyperaccumulate boron in extremely boron-contaminated sites. To further investigate its potential for phytoremediation, we determined its response to boron stress under controlled conditions (hydroponic culture). Also, as a first step towards understanding the mechanisms underlying its extreme tolerance, we evaluated the presence and expression of genes related with boron tolerance. We found that P. frigida grew normally even at highly toxic boron concentrations in the medium (500mg/L), and within its tissues (>5000mg/kg DW). We postulate that the strategies conferring this extreme tolerance involve both restricting boron accumulation and an internal tolerance mechanism; this is consistent with the identification of putative genes involved in both mechanisms, including the expression of a possible boron efflux transporter. We also found that P. frigida hyperaccumulated boron over a wide range of boron concentrations. We propose that P. frigida could be used for boron phytoremediation strategies in places with different soil characteristics and boron concentrations. Further studies should pave the way for the development of clean and low-cost solutions to boron toxicity problems. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Electrochemical Incineration of Phenolic Compounds from the Hydrocarbon Industry Using Boron-Doped Diamond Electrodes

    Directory of Open Access Journals (Sweden)

    Alejandro Medel

    2012-01-01

    Full Text Available Electrochemical incineration using boron-doped diamond electrodes was applied to samples obtained from a refinery and compared to the photo-electro-Fenton process in order to selectively eliminate the phenol and phenolic compounds from a complex matrix. Due to the complex chemical composition of the sample, a pretreatment to the sample in order to isolate the phenolic compounds was applied. The effects of the pretreatment and of pH on the degradation of the phenolic compounds were evaluated. The results indicate that the use of a boron-doped diamond electrode in an electrochemical incineration process mineralizes 99.5% of the phenolic sample content. Working in acidic medium (pH = 1, and applying 2 A at 298 K under constant stirring for 2 hours, also results in the incineration of the reaction intermediates reflected by 97% removal of TOC. In contrast, the photo-electro-Fenton process results in 99.9% oxidation of phenolic compounds with only a 25.69% removal of TOC.

  17. Synergistic methods for the production of high-strength and low-cost boron carbide

    Science.gov (United States)

    Wiley, Charles Schenck

    2011-12-01

    Boron carbide (B4C) is a non-oxide ceramic in the same class of nonmetallic hard materials as silicon carbide and diamond. The high hardness, high elastic modulus and low density of B4C make it a nearly ideal material for personnel and vehicular armor. B4C plates formed via hot-pressing are currently issued to U.S. soldiers and have exhibited excellent performance; however, hot-pressed articles contain inherent processing defects and are limited to simple geometries such as low-curvature plates. Recent advances in the pressureless sintering of B4C have produced theoretically-dense and complex-shape articles that also exhibit superior ballistic performance. However, the cost of this material is currently high due to the powder shape, size, and size distribution that are required, which limits the economic feasibility of producing such a product. Additionally, the low fracture toughness of pure boron carbide may have resulted in historically lower transition velocities (the projectile velocity range at which armor begins to fail) than competing silicon carbide ceramics in high-velocity long-rod tungsten penetrator tests. Lower fracture toughness also limits multi-hit protection capability. Consequently, these requirements motivated research into methods for improving the densification and fracture toughness of inexpensive boron carbide composites that could result in the development of a superior armor material that would also be cost-competitive with other high-performance ceramics. The primary objective of this research was to study the effect of titanium and carbon additives on the sintering and mechanical properties of inexpensive B4C powders. The boron carbide powder examined in this study was a sub-micron (0.6 mum median particle size) boron carbide powder produced by H.C. Starck GmbH via a jet milling process. A carbon source in the form of phenolic resin, and titanium additives in the form of 32 nm and 0.9 mum TiO2 powders were selected. Parametric studies of

  18. Non-isothermal kinetics model to predict accurate phase transformation and hardness of 22MnB5 boron steel

    Energy Technology Data Exchange (ETDEWEB)

    Bok, H.-H.; Kim, S.N.; Suh, D.W. [Graduate Institute of Ferrous Technology, POSTECH, San 31, Hyoja-dong, Nam-gu, Pohang, Gyeongsangbuk-do (Korea, Republic of); Barlat, F., E-mail: f.barlat@postech.ac.kr [Graduate Institute of Ferrous Technology, POSTECH, San 31, Hyoja-dong, Nam-gu, Pohang, Gyeongsangbuk-do (Korea, Republic of); Lee, M.-G., E-mail: myounglee@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Anam-dong, Seongbuk-gu, Seoul (Korea, Republic of)

    2015-02-25

    A non-isothermal phase transformation kinetics model obtained by modifying the well-known JMAK approach is proposed for application to a low carbon boron steel (22MnB5) sheet. In the modified kinetics model, the parameters are functions of both temperature and cooling rate, and can be identified by a numerical optimization method. Moreover, in this approach the transformation start and finish temperatures are variable instead of the constants that depend on chemical composition. These variable reference temperatures are determined from the measured CCT diagram using dilatation experiments. The kinetics model developed in this work captures the complex transformation behavior of the boron steel sheet sample accurately. In particular, the predicted hardness and phase fractions in the specimens subjected to a wide range of cooling rates were validated by experiments.

  19. Non-isothermal kinetics model to predict accurate phase transformation and hardness of 22MnB5 boron steel

    International Nuclear Information System (INIS)

    Bok, H.-H.; Kim, S.N.; Suh, D.W.; Barlat, F.; Lee, M.-G.

    2015-01-01

    A non-isothermal phase transformation kinetics model obtained by modifying the well-known JMAK approach is proposed for application to a low carbon boron steel (22MnB5) sheet. In the modified kinetics model, the parameters are functions of both temperature and cooling rate, and can be identified by a numerical optimization method. Moreover, in this approach the transformation start and finish temperatures are variable instead of the constants that depend on chemical composition. These variable reference temperatures are determined from the measured CCT diagram using dilatation experiments. The kinetics model developed in this work captures the complex transformation behavior of the boron steel sheet sample accurately. In particular, the predicted hardness and phase fractions in the specimens subjected to a wide range of cooling rates were validated by experiments

  20. 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.

  1. Removal of Boron from aqueous solutions by adsorption using fly ash, zeolite and demineralized lignite

    OpenAIRE

    Yüksel, Seren; Yuksel, Seren; Yürüm, Yuda; Yurum, Yuda

    2009-01-01

    In the present study for the purpose of removal of boron from water by adsorption using adsorbents like fly ash, natural zeolite and demineralized lignite was investigated. Boron in water was removed with fly ash, zeolite and demineralized lignite with different capacities. 94% boron was removed using fly ash. Batch experiments were conducted to test removal capacity, to obtain adsorption isotherms, thermodynamic and kinetic parameters. Boron removal by all adsorbents was affected by pH of...

  2. Removal of Boron from Waste Waters by Ion- Exchange in a Batch System

    OpenAIRE

    Pelin Demirçivi; Gülhayat Nasün-Saygılı

    2008-01-01

    Boron minerals are very useful for various industrial activities, such as glass industry and detergent industry, due to its mechanical and chemical properties. During the production of boron compounds, many of these are introduced into the environment in the form of waste. Boron is also an important micro nutrient for the plants to vegetate but if it exists in high concentrations, it could have toxic effects. The maximum boron level in drinking water for human health is g...

  3. Boron removal from saline water by a microbial desalination cell integrated with donnan dialysis

    OpenAIRE

    Ping, Q.; Abu-Reesh, I.M.; He, Z.

    2015-01-01

    Boron has toxic effects on plant growth and thus its removal is necessary from desalinated saline water for irrigation application. Microbial desalination cells (MDCs) are a new approach for effective desalination but boron removal has not been addressed before. Herein, MDCs were studied for boron removal with aid of Donnan Dialysis (DD). The alkaline solution generated by the MDC cathode was used to ionize boric acid to facilitate boron removal. An MDC system with DD pretreatment removed 60 ...

  4. Free-standing polycrystalline boron phosphide film and method for production thereof

    Science.gov (United States)

    Baughman, R.J.; Ginley, D.S.

    1982-09-09

    A process for producing a free-standing polycrystalline boron phosphide film comprises growing a film of boron phosphide in a vertical growth apparatus on a metal substrate. The metal substrate has a coefficient of thermal expansion sufficiently different from that of boron phosphide that the film separates cleanly from the substrate upon cooling thereof, and the substrate is preferably titanium. The invention also comprises a free-standing polycrystalline boron phosphide film for use in electronic device fabrication.

  5. Method for production of free-standing polycrystalline boron phosphide film

    Science.gov (United States)

    Baughman, Richard J.; Ginley, David S.

    1985-01-01

    A process for producing a free-standing polycrystalline boron phosphide film comprises growing a film of boron phosphide in a vertical growth apparatus on a metal substrate. The metal substrate has a coefficient of thermal expansion sufficiently different from that of boron phosphide that the film separates cleanly from the substrate upon cooling thereof, and the substrate is preferably titanium. The invention also comprises a free-standing polycrystalline boron phosphide film for use in electronic device fabrication.

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

    Science.gov (United States)

    Andrade, Leandro H; Barcellos, Thiago

    2009-07-16

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

  7. Adjustment methodology for preliminary study on the distribution of bone tissue boron. Potential therapeutic applications

    International Nuclear Information System (INIS)

    Brandizzi, D; Dagrosa, A; Carpano, M.; Olivera, M. S.; Nievas, S; Cabrini, R.L.

    2013-01-01

    Boron is an element that has an affinity for bone tissue and represents a considered element in bone health . Other boron compounds are used in the Boron Neutron Capture Therapy (BNCT ) in the form of sodium borocaptate (BSH ) and borono phenylalanine (BPA). The results of clinical trials up to date are encouraging but not conclusive . At an experimental level , some groups have applied BNCT in osteosarcomas . We present preliminary methodological adjustments for the presence of boron in bone. (author)

  8. Boron- and salt-tolerant trees and shrubs for northern Nevada

    Science.gov (United States)

    Heidi Kratsch

    2012-01-01

    Boron is a mineral that, in small quantities, is essential for plant growth and development , but becomes toxic at levels above 0.5 to 1 part per million (ppm) in the soil. Excess boron may be naturally present in the soil, and it can accumulate by irrigating with water high in boron. Boron occurs naturally in arid soils originating from geologically young deposits. It...

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

    Science.gov (United States)

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

    2017-02-01

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

  10. Deposition of Boron in Possible Evaporite Deposits in Gale Crate

    Science.gov (United States)

    Gasda, P. J.; Peets, E.; Lamm, S. N.; Rapin, W.; Lanza, N.; Frydenvang, J.; Clark, B. C.; Herkenhoff, K. E.; Bridges, J.; Schwenzer, S. P.; Haldeman, E. B.; Wiens, R. C.; Maurice, S.; Clegg, S. M.; Delapp, D.; Sanford, V.; Bodine, M. R.; McInroy, R.

    2017-12-01

    Boron has been previously detected in Gale crater using the ChemCam instrument on board the NASA Curiosity rover within calcium sulfate fracture fill hosted by lacustrine mudstone and eolian sandstone units. Recent results show that up to 300 ppm B is present in the upper sections of the lacustrine unit. Boron has been detected in both the groundwater-emplaced calcium sulfate fracture fill materials and bedding-parallel calcium sulfate layers. The widespread bedding-parallel calcium sulfate layers within the upper strata of the lacustrine bedrock that Curiosity has encountered recently could be interpreted as primary evaporite deposits. We have two hypotheses for the history of boron in Gale crater. In both hypotheses, borates were first deposited as lake water evaporated, depositing primary evaporates that were later re-dissolved by groundwater, which redistributed the boron into secondary evaporitic calcium sulfate fracture fill deposits. In the first scenario, Gale crater may have undergone a period of perennial lake formation during a drier period of martian history, depositing layers of evaporitic minerals (including borates) among lacustrine mudstone layers. In the second scenario, lake margins could have become periodically exposed during cyclic drops in lake level and subsequently desiccated. Evaporites were deposited and desiccation features were formed in lowstand deposits. Either hypothetical scenario of evaporite deposition would promote prebiotic chemical reactions via wet-dry cycles. Boron may be an important prebiotic element, and as such, its presence in ancient martian surface and groundwater provides evidence that important prebiotic chemical reactions could occur on Mars if organics were present. The presence of boron in ancient Gale crater groundwater also provides additional evidence that a habitable environment existed in the martian subsurface well after the expected disappearance of liquid water on the surface of Mars. We will report on the

  11. Graphene nanoribbons epitaxy on boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Xiaobo; Wang, Shuopei; Wu, Shuang; Chen, Peng; Zhang, Jing; Zhao, Jing; Meng, Jianling; Xie, Guibai; Wang, Duoming; Wang, Guole; Zhang, Ting Ting; Yang, Rong; Shi, Dongxia [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Yang, Wei [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Laboratoire Pierre Aigrain, ENS-CNRS UMR 8551, Universités Pierre et Marie Curie and Paris-Diderot, 24 rue Lhomond, 75231 Paris Cedex 05 (France); Watanabe, Kenji; Taniguchi, Takashi [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Zhang, Guangyu, E-mail: gyzhang@aphy.iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100190 (China)

    2016-03-14

    In this letter, we report a pilot study on epitaxy of monolayer graphene nanoribbons (GNRs) on hexagonal boron nitride (h-BN). We found that GNRs grow preferentially from the atomic steps of h-BN, forming in-plane heterostructures. GNRs with well-defined widths ranging from ∼15 nm to ∼150 nm can be obtained reliably. As-grown GNRs on h-BN have high quality with a carrier mobility of ∼20 000 cm{sup 2} V{sup −1} s{sup −1} for ∼100-nm-wide GNRs at a temperature of 1.7 K. Besides, a moiré pattern induced quasi-one-dimensional superlattice with a periodicity of ∼15 nm for GNR/h-BN was also observed, indicating zero crystallographic twisting angle between GNRs and h-BN substrate. The superlattice induced band structure modification is confirmed by our transport results. These epitaxial GNRs/h-BN with clean surfaces/interfaces and tailored widths provide an ideal platform for high-performance GNR devices.

  12. From ``structural democracy'' to ``boron connection''

    Science.gov (United States)

    Zdetsis, Aristides D.

    2009-03-01

    It is shown here that the Si62--B6H62- analogy [A. D. Zdetsis J. Chem. Phys., 127, 014314 (2007)] originated from the fluxionality of Si6 cluster can be extended and generalized in such a way as to include silicon-carbon clusters of the form Sin-2C2H2, n = 3-7, which are fully homologous and isolobal to the corresponding isovalent carboranes C2Bn_-Hn. This is an extended version of the "boron connection" suggested recently by the author [J. Chem. Phys., 128, 184305 (2008)]. Further extensions and generalizations are possible, but not necessarily as successful as the Si62--B6H62 and Sin-2C2H2-C2Bn-2Hn, n = 3-7, isolobal analogies. It is furthermore demonstrated that these ideas and concepts which are "aesthetically appealing" are also very useful and powerful despite their simplicity. It is anticipated that such strong and successful analogies would facilitate the exploitation of the rich borane/carborane Chemistry for the design and development of novel silicon, carbon, and silicon-carbon composite materials.

  13. Scratch-resistant transparent boron nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Dekempeneer, E.H.A.; Kuypers, S.; Vercammen, K.; Meneve, J.; Smeets, J. [Vlaamse Instelling voor Technologisch Onderzoek (VITO), Mol (Belgium); Gibson, P.N.; Gissler, W. [Joint Research Centre of the Commission of the European Communities, Institute for Advanced Materials, Ispra (Vatican City State, Holy See) (Italy)

    1998-03-01

    Transparent boron nitride (BN) coatings were deposited on glass and Si substrates in a conventional capacitively coupled RF PACVD system starting from diborane (diluted in helium) and nitrogen. By varying the plasma conditions (bias voltage, ion current density), coatings were prepared with hardness values ranging from 2 to 12 GPa (measured with a nano-indenter). Infrared absorption measurements indicated that the BN was of the hexagonal type. A combination of glancing-angle X-ray diffraction measurements and simulations shows that the coatings consist of hexagonal-type BN crystallites with different degrees of disorder (nanocrystalline or turbostratic material). High-resolution transmission electron microscopy analysis revealed the presence of an amorphous interface layer and on top of this interface layer a well-developed fringe pattern characteristic for the basal planes in h-BN. Depending on the plasma process conditions, these fringe patterns showed different degrees of disorder as well as different orientational relationships with respect to the substrate surface. These observations were correlated with the mechanical properties of the films. (orig.) 14 refs.

  14. Boron filled siloxane polymers for radiation shielding

    Science.gov (United States)

    Labouriau, Andrea; Robison, Tom; Shonrock, Clinton; Simmonds, Steve; Cox, Brad; Pacheco, Adam; Cady, Carl

    2018-03-01

    The purpose of the present work was to evaluate changes to structure-property relationships of 10B filled siloxane-based polymers when exposed to nuclear reactor radiation. Highly filled polysiloxanes were synthesized with the intent of fabricating materials that could shield high neutron fluences. The newly formulated materials consisted of cross-linked poly-diphenyl-methylsiloxane filled with natural boron and carbon nanofibers. This polymer was chosen because of its good thermal and chemical stabilities, as well as resistance to ionizing radiation thanks to the presence of aromatic groups in the siloxane backbone. Highly isotopically enriched 10B filler was used to provide an efficient neutron radiation shield, and carbon nanofibers were added to improve mechanical strength. This novel polymeric material was exposed in the Annular Core Research Reactor (ACRR) at Sandia National Labs to five different neutron/gamma fluxes consisting of very high neutron fluences within very short time periods. Thermocouples placed on the specimens recorded in-situ temperature changes during radiation exposure, which agreed well with those obtained from our MCNP simulations. Changes in the microstructural, thermal, chemical, and mechanical properties were evaluated by SEM, DSC, TGA, FT-IR NMR, solvent swelling, and uniaxial compressive load measurements. Our results demonstrate that these newly formulated materials are well-suitable to be used in applications that require exposure to different types of ionizing conditions that take place simultaneously.

  15. Boronline, a new generation of boron meter

    International Nuclear Information System (INIS)

    Pirat, P.

    2011-01-01

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

  16. Raman effect in icosahedral boron-rich solids

    Directory of Open Access Journals (Sweden)

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

    2010-01-01

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

  17. Embrittling Components in Sintered Steels: Comparison of Phosphorus and Boron

    Science.gov (United States)

    Danninger, Herbert; Vassileva, Vassilka; Gierl-Mayer, Christian

    2017-12-01

    In ferrous powder metallurgy, both boron and phosphorus have been known to be sintering activators for a long time. However, the use has been widely different: while P is a standard additive to sintered iron and steels, boron has been frequently studied, but its use in practice is very limited. Both additives are also known to be potentially embrittling, though in a different way. In the present study the differences between the effects of both elements are shown: while P activates sintering up to a certain threshold, in part by stabilizing ferrite, in part by forming a transient liquid phase, boron is the classical additive enhancing persistent liquid phase, being virtually insoluble in the iron matrix. The consequence is that sintered steels can tolerate quite a proportion of phosphorus, depending on composition and sintering process; boron however is strongly embrittling in particular in combination with carbon, which requires establishing a precisely defined content that enhances sintering but is not yet embrittling. The fracture mode of embrittled materials is also different: while with Fe-P the classical intergranular fracture is observed, with boron a much more rugged fracture surface appears, indicating some failure through the eutectic interparticle network but mostly transgranular cleavage. If carbon is added, in both cases transgranular cleavage dominates even in the severely embrittled specimens, indicating that no more the grain boundaries and sintering necks are the weakest links in the systems.

  18. Iron solubility in highly boron-doped silicon

    International Nuclear Information System (INIS)

    McHugo, S.A.; McDonald, R.J.; Smith, A.R.; Hurley, D.L.; Weber, E.R.

    1998-01-01

    We have directly measured the solubility of iron in high and low boron-doped silicon using instrumental neutron activation analysis. Iron solubilities were measured at 800, 900, 1000, and 1100thinsp degree C in silicon doped with either 1.5x10 19 or 6.5x10 14 thinspboronthinspatoms/cm 3 . We have measured a greater iron solubility in high boron-doped silicon as compared to low boron-doped silicon, however, the degree of enhancement is lower than anticipated at temperatures >800thinsp degree C. The decreased enhancement is explained by a shift in the iron donor energy level towards the valence band at elevated temperatures. Based on this data, we have calculated the position of the iron donor level in the silicon band gap at elevated temperatures. We incorporate the iron energy level shift in calculations of iron solubility in silicon over a wide range of temperatures and boron-doping levels, providing a means to accurately predict iron segregation between high and low boron-doped silicon. copyright 1998 American Institute of Physics

  19. Boron solubility in Fe-Cr-B cast irons

    International Nuclear Information System (INIS)

    Guo Changqing; Kelly, P.M.

    2003-01-01

    Boron solubility in the as-cast and solution treated martensite of Fe-Cr-B cast irons, containing approximately 1.35 wt.% of boron, 12 wt.% of chromium, as well as other alloying elements, has been investigated using conventional microanalysis. The significant microstructural variations after tempering at 750 deg. C for 0.5-4 h, compared with the original as-cast and solution treated microstructures, indicated that the matrix consisted of boron and carbon supersaturated solid solutions. The boron solubility detected by electron microprobe was between 0.185-0.515 wt.% for the as-cast martensite and 0.015-0.0589 wt.% for the solution treated martensite, much higher than the accepted value of 0.005 wt.% in pure iron. These remarkable increases are thought to be associated with some metallic alloying element addition, such as chromium, vanadium and molybdenum, which have atomic diameters larger than iron, and expand the iron lattice to sufficiently allow boron atoms to occupy the interstitial sites in iron lattice

  20. Boron incorporation into rutile: phase equilibria and structural considerations

    Energy Technology Data Exchange (ETDEWEB)

    Grey, I.E.; Li, C.; MacRae, C.M. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), East Melbourne, VIC (Australia). Div of Minerals; Bursill, L.A. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1997-06-01

    Reduction of rutile in the presence of borate flux stabilised the rutile phase relative to reduced rutiles due to incorporation of boron from the flux. In the presence of borates the rutile phase is stabilised to oxygen fugacities that are lower by almost two orders of magnitude compared with fugacities at the limit of the single-phase rutile phase field in the pure Ti-O system. Boron incorporation is accompanied by reduction of titanium to the trivalent state, according to the charge compensation relation: 3Ti{sup 4+}{identical_to} 3 Ti{sup 3+} + B{sup 3+}. Results of powder X-ray diffraction and transmission electron microscopy studies on samples prepared in the temperature range 1100 to 1300 deg C have been used to establish a model for boron incorporation. It is proposed that at the temperatures studied, local defects in boron doped rutile result from displacement of titanium atoms to adjacent interstitial sites coupled with occupation by boron of the triangular face of the vacated octahedral sites. This atomic grouping represents a small element of the TiBO{sub 3} (calcite-type) structure. Annealing at a lower temperature results in ordering of the local defects to form (101){sub r} planar intergrowths of rutile and calcite-type structures. 14 refs., 3 tabs., 8 figs.