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Sample records for boron 10

  1. Boron-10 ABUNCL Active Testing

    SciTech Connect

    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.

  2. Boron-10 ABUNCL Models of Fuel Testing

    SciTech Connect

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

    2013-10-01

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

  3. Boron-10 ABUNCL Prototype Initial Testing

    SciTech Connect

    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.

  4. Boron-10 Lined Proportional Counter Wall Effects

    SciTech Connect

    Siciliano, Edward R.; Kouzes, Richard T.

    2012-05-01

    The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube based system in the configuration of a coincidence counter. This report provides information about how variations in proportional counter radius and gas pressure in a typical coincident counter design might affect the observed signal from boron-lined tubes. A discussion comparing tubes to parallel plate counters is also included.

  5. Boron-10 Lined Proportional Counter Model Validation

    SciTech Connect

    Lintereur, Azaree T.; Siciliano, Edward R.; Kouzes, Richard T.

    2012-06-30

    The Department of Energy Office of Nuclear Safeguards (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 an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube-based alternative system in the configuration of a coincidence counter. This report discusses the validation studies performed to establish the degree of accuracy of the computer modeling methods current used to simulate the response of boron-lined tubes. This is the precursor to developing models for the uranium neutron coincidence collar under Task 2 of this project.

  6. Boron/aluminum skins for the DC-10 aft pylon

    NASA Technical Reports Server (NTRS)

    Elliott, S. Y.

    1975-01-01

    Boron/aluminum pylon boat tail skins were designed and fabricated and installed on the DC-10 aircraft for a 5-year flight service demonstration test. Inspection and tests of the exposed skins will establish the ability of the boron/aluminum composite to withstand long time flight service conditions, which include exposure to high temperatures, sonic fatigue, and flutter. The results of a preliminary testing program yield room temperature and elevated temperature data on the tension, compression, in-plane shear, interlaminar shear, bolt bearing, and tension fatigue properties of the boron/aluminum laminates. Present technology was used in the fabrication of the skins. Although maximum weight saving was not sought, weight of the constant thickness boron/aluminum skin is 26% less than the chemically milled titanium skin.

  7. Uranium Neutron Coincidence Collar Model Utilizing Boron-10 Lined Tubes

    SciTech Connect

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

    2012-09-18

    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, providing results for model development of Alternative Boron-Based Uranium Neutron Coincidence Collar (ABUNCL) designs, is a deliverable under Task 2 of the project.

  8. Boron

    USDA-ARS?s Scientific Manuscript database

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

  9. Boron-10 ABUNCL Prototype Models And Initial Active Testing

    SciTech Connect

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

    2013-04-23

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Coincidence Counting With Boron-Based Alternative Neutron Detection Technology at Pacific Northwest National Laboratory (PNNL) for the development of a 3He proportional counter alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a system based upon 10B-lined proportional tubes in a configuration typical for 3He-based coincidence counter applications. This report provides results from MCNPX model simulations and initial testing of the active mode variation of the Alternative Boron-Based Uranium Neutron Coincidence Collar (ABUNCL) design built by General Electric Reuter-Stokes. Initial experimental testing of the as-delivered passive ABUNCL was previously reported.

  10. Over 1.0 mm-long boron nitride nanotubes

    NASA Astrophysics Data System (ADS)

    Chen, Hua; Chen, Ying; Liu, Yun; Fu, Lan; Huang, Cheng; Llewellyn, David

    2008-09-01

    Over 1.0 mm boron nitride nanotubes (BNNTs) were successfully synthesized by an optimized ball milling and annealing method. The annealing temperature of 1100 °C is crucial for the growth of the long BNNTs because at this temperature there is a fast nitrogen dissolution rate in Fe and the B/N ratio in Fe is 1. Such long BNNTs enable a reliable single tube configuration for electrical property characterization and consequently the average resistivity of the long BNNTs is determined to be 7.1 ± 0.9 × 10 4 Ω cm. Therefore, these BNNTs are promising insulators for three dimensional microelectromechanical system.

  11. Boron

    MedlinePlus

    ... body handles other minerals such as magnesium and phosphorus. It also seems to increase estrogen levels in ... happens in men.PhosphorusSupplemental boron might reduce blood phosphorus levels in some people.

  12. Double helix boron-10 powder thermal neutron detector

    DOEpatents

    Wang, Zhehui; Morris, Christopher L.; Bacon, Jeffrey D.

    2015-06-02

    A double-helix Boron-10 powder detector having intrinsic thermal neutron detection efficiency comparable to 36'' long, 2-in diameter, 2-bar Helium-3 detectors, and which can be used to replace such detectors for use in portal monitoring, is described. An embodiment of the detector includes a metallic plate coated with Boron-10 powder for generating alpha and Lithium-7 particles responsive to neutrons impinging thereon supported by insulators affixed to at least two opposing edges; a grounded first wire wound in a helical manner around two opposing insulators; and a second wire having a smaller diameter than that of the first wire, wound in a helical manner around the same insulators and spaced apart from the first wire, the second wire being positively biased. A gas, disposed within a gas-tight container enclosing the plate, insulators and wires, and capable of stopping alpha and Lithium-7 particles and generating electrons produces a signal on the second wire which is detected and subsequently related to the number of neutrons impinging on the plate.

  13. 10-Boronic acid substituted camptothecin as prodrug of SN-38.

    PubMed

    Wang, Lei; Xie, Shao; Ma, Longjun; Chen, Yi; Lu, Wei

    2016-06-30

    Malignant tumor cells have been found to have high levels of reactive oxygen species such as hydrogen peroxide (H2O2), supporting the hypothesis that a prodrug could be activated by intracellular H2O2 and lead to a potential antitumor therapy. In this study, the 7-ethyl-10-boronic acid camptothecin (B1) was synthesized for the first time as prodrug of SN-38, by linking a cleavable aryl carbon-boron bond to the SN-38. Prodrug B1 selectively activated by H2O2, converted rapidly to the active form SN-38 under favorable oxidative conditions in cancer cells with elevated levels of H2O2. The cell survival assay showed that prodrug B1 was equally or more effective in inhibiting the growth of six different cancer cells, as compared to SN-38. Unexpectedly, prodrug B1 displayed even more potent Topo I inhibitory activity than SN-38, suggesting that it was not only a prodrug of SN-38 but also a typical Topo I inhibitor. Prodrug B1 also demonstrated a significant antitumor activity at 2.0 mg/kg in a xenograft model using human brain star glioblastoma cell lines U87MG.

  14. 1H and 10B NMR and MRI investigation of boron- and gadolinium-boron compounds in boron neutron capture therapy.

    PubMed

    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.

  15. Boron uptake in normal melanocytes and melanoma cells and boron biodistribution study in mice bearing B16F10 melanoma for boron neutron capture therapy.

    PubMed

    Faião-Flores, Fernanda; Coelho, Paulo Rogério Pinto; Arruda-Neto, João Dias Toledo; Camillo, Maria Aparecida Pires; Maria-Engler, Silvya Stuchi; Rici, Rose Eli Grassi; Sarkis, Jorge Eduardo Souza; Maria, Durvanei Augusto

    2012-08-01

    Information on (10)B distribution in normal tissues is crucial to any further development of boron neutron capture therapy (BNCT). The goal of this study was to investigate the in vitro and in vivo boron biodistribution in B16F10 murine melanoma and normal tissues as a model for human melanoma treatment by a simple and rapid colorimetric method, which was validated by HR-ICP-MS. The B16F10 melanoma cell line showed higher melanin content than human melanocytes, demonstrating a greater potential for boronophenylalanine uptake. The melanocytes showed a moderate viability decrease in the first few minutes after BNCT application, stabilizing after 75 min, whereas the B16F10 melanoma showed the greatest intracellular boron concentration at 150 min after application, indicating a different boron uptake of melanoma cells compared to normal melanocytes. Moreover, at this time, the increase in boron uptake in melanoma cells was approximately 1.6 times higher than that in normal melanocytes. The (10)B concentration in the blood of mice bearing B16F10 melanoma increased until 90 min after BNCT application and then decreased after 120 min, and remained low until the 240th minute. On the other hand, the (10)B concentration in tumors was increased from 90 min and maximal at 150 min after application, thus confirming the in vitro results. Therefore, the present in vitro and in vivo study of (10)B uptake in normal and tumor cells revealed important data that could enable BNCT to be possibly used as a treatment for melanoma, a chemoresistant cancer associated with high mortality.

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

    SciTech Connect

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

    2012-01-22

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

  17. Biodistribution of the boron carriers boronophenylalanine (BPA) and/or decahydrodecaborate (GB-10) for Boron Neutron Capture Therapy (BNCT) in an experimental model of lung metastases

    SciTech Connect

    D.W. Nigg; Various Others

    2014-06-01

    BNCT was proposed for the treatment of diffuse, non-resectable tumors in the lung. We performed boron biodistribution studies with 5 administration protocols employing the boron carriers BPA and/or GB-10 in an experimental model of disseminated lung metastases in rats. All 5 protocols were non-toxic and showed preferential tumor boron uptake versus lung. Absolute tumor boron concentration values were therapeutically useful (25–76 ppm) for 3 protocols. Dosimetric calculations indicate that BNCT at RA-3 would be potentially therapeutic without exceeding radiotolerance in the lung.

  18. Electroextraction of boron from boron carbide scrap

    SciTech Connect

    Jain, Ashish; Anthonysamy, S.; Ghosh, C.; Ravindran, T.R.; Divakar, R.; Mohandas, E.

    2013-10-15

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

  19. Folate receptor-mediated boron-10 containing carbon nanoparticles as potential delivery vehicles for boron neutron capture therapy of nonfunctional pituitary adenomas.

    PubMed

    Dai, Congxin; Cai, Feng; Hwang, Kuo Chu; Zhou, Yongmao; Zhang, Zizhu; Liu, Xiaohai; Ma, Sihai; Yang, Yakun; Yao, Yong; Feng, Ming; Bao, Xinjie; Li, Guilin; Wei, Junji; Jiao, Yonghui; Wei, Zhenqing; Ma, Wenbin; Wang, Renzhi

    2013-02-01

    Invasive nonfunctional pituitary adenomas (NFPAs) are difficult to completely resect and often develop tumor recurrence after initial surgery. Currently, no medications are clinically effective in the control of NFPA. Although radiation therapy and radiosurgery are useful to prevent tumor regrowth, they are frequently withheld because of severe complications. Boron neutron capture therapy (BNCT) is a binary radiotherapy that selectively and maximally damages tumor cells without harming the surrounding normal tissue. Folate receptor (FR)-targeted boron-10 containing carbon nanoparticles is a novel boron delivery agent that can be selectively taken up by FR-expressing cells via FR-mediated endocytosis. In this study, FR-targeted boron-10 containing carbon nanoparticles were selectively taken up by NFPAs cells expressing FR but not other types of non-FR expressing pituitary adenomas. After incubation with boron-10 containing carbon nanoparticles and following irradiation with thermal neutrons, the cell viability of NFPAs was significantly decreased, while apoptotic cells were simultaneously increased. However, cells administered the same dose of FR-targeted boron-10 containing carbon nanoparticles without neutron irradiation or received the same neutron irradiation alone did not show significant decrease in cell viability or increase in apoptotic cells. The expression of Bcl-2 was down-regulated and the expression of Bax was up-regulated in NFPAs after treatment with FR-mediated BNCT. In conclusion, FR-targeted boron-10 containing carbon nanoparticles may be an ideal delivery system of boron to NFPAs cells for BNCT. Furthermore, our study also provides a novel insight into therapeutic strategies for invasive NFPA refractory to conventional therapy, while exploring these new applications of BNCT for tumors, especially benign tumors.

  20. Engineering Novel Targeted Boron-10-Enriched Theranostic Nanomedicine to Combat against Murine Brain Tumors via MR Imaging-Guided Boron Neutron Capture Therapy.

    PubMed

    Kuthala, Naresh; Vankayala, Raviraj; Li, Yi-Nan; Chiang, Chi-Shiun; Hwang, Kuo Chu

    2017-08-01

    Glioblastoma multiforme (GBM) is a very common type of "incurable" malignant brain tumor. Although many treatment options are currently available, most of them eventually fail due to its recurrence. Boron neutron capture therapy (BNCT) emerges as an alternative noninvasive therapeutic treatment modality. The major challenge in treating GBMs using BNCT is to achieve selective imaging, targeting, and sufficient accumulation of boron-containing drug at the tumor site so that effective destruction of tumor cells can be achieved without harming the normal brain cells. To tackle this challenge, this study demonstrates for the first time that an unprecedented (10) B-enriched (96% (10) B enrichment) boron nanoparticle nanomedicine ((10) BSGRF NPs) surface-modified with a Fluorescein isothiocyanate (FITC)-labeled RGD-K peptide can pass through the brain blood barrier, selectively target at GBM brain tumor sites, and deliver high therapeutic dosage (50.5 µg (10) B g(-1) cells) of boron atoms to tumor cells with a good tumor-to-blood boron ratio of 2.8. The (10) BSGRF NPs not only can enhance the contrast of magnetic resonance (MR) imaging to help diagnose the location/size/progress of brain tumor, but also effectively suppress murine brain tumors via MR imaging-guided BNCT, prolonging the half-life of mice from 22 d (untreated group) to 39 d. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Boron-10 concentration measurements using CR-39 and automatic image analysis

    SciTech Connect

    Blue, T.E.; Roberts, T.C.; Barth, R.F.

    1986-01-01

    As part of a study of the effectiveness of /sup 10/B as a capture agent for neutron capture therapy, the /sup 10/B concentrations of samples of tissue taken from brains, from tumors within the brains, and from the blood of rats are being measured following administration of pharmaceuticals. The measurements are made with the polycarbonate solid-state nuclear track detector (SSNTD) CR-39, using an autoradiographic procedure and an image analysis system for automatic track counting. Boron-10 concentrations in tissue have been measured by others using autoradiography and lexan and cellulose nitrate SSNTDs. This paper reports our procedure for measuring /sup 10/B concentrations using CR-39.

  2. Catalytic growth of vertically aligned neutron sensitive 10Boron nitride nanotubes

    NASA Astrophysics Data System (ADS)

    Ahmad, Pervaiz; Khandaker, Mayeen Uddin; Amin, Yusoff Mohd; Khan, Ghulamullah; Ramay, Shahid M.; Mahmood, Asif; Amin, Muhammad; Muhammad, Nawshad

    2016-01-01

    10Boron nitride nanotubes (10BNNTs) are a potential neutron sensing element in a solid-state neutron detector. The aligned 10BNNT can be used for its potential application without any further purification. Argon-supported thermal CVD is used to achieve vertically aligned 10BNNT with the help of nucleation sites produced in a thin layer of magnesium-iron alloy deposited at the top of Si substrate. FESEM shows vertically aligned 10BNNTs with ball-like catalytic tips at top. EDX reveals magnesium (Mg) contents in the tips that refer to catalytic growth of 10BNNT. HR-TEM shows tubular morphology of the synthesized 10BNNT with lattice fringes on its outer part having an interlayer spacing of 0.34 nm. XPS shows B 1 s and N 1 s peaks at 190.5 and 398 eV that correspond to hexagonal 10Boron nitride (10h-BN) nature of the synthesized 10BNNT, whereas the Mg kll auger peaks at 301 and 311 eV represents Mg contents in the sample. Raman spectrum has a peak at 1390 (cm-1) that corresponds to E 2g mode of vibration in 10h-BN.

  3. CASCADE - a multi-layer Boron-10 neutron detection system

    NASA Astrophysics Data System (ADS)

    Köhli, M.; Klein, M.; Allmendinger, F.; Perrevoort, A.-K.; Schröder, T.; Martin, N.; Schmidt, C. J.; Schmidt, U.

    2016-09-01

    The globally increased demand for helium-3 along with the limited availability of this gas calls for the development of alternative technologies for the large ESS instrumentation pool. We report on the CASCADE Project - a novel detection system, which has been developed for the purposes of neutron spin echo spectroscopy. It features 2D spatially resolved detection of thermal neutrons at high rates. The CASCADE detector is composed of a stack of solid 10B coated Gas Electron Multiplier foils, which serve both as a neutron converter and as an amplifier for the primary ionization deposited in the standard Argon-CO2 counting gas environment. This multi-layer setup efficiently increases the detection efficiency and serves as a helium-3 alternative. It has furthermore been possible to extract the signal of the charge traversing the stack to identify the very thin conversion layer of about 1 micrometer. This allows the precise determination of the time-of-flight, necessary for the application in MIEZE spin echo techniques.

  4. Boron reclamation

    SciTech Connect

    Smith, R.M.

    1980-07-01

    A process to recover high purity /sup 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.

  5. Boron-10 quantification and microdosimetric studies in a clinical trial of BNCT

    SciTech Connect

    Kiger, W.S. III; Solares, G.R.; Yam, C.S.

    1996-12-31

    Five boron neutron capture therapy (BNCT) treatments have been delivered as part of the New England Deaconess Hospital-Massachusetts Institute of Technology (MIT) phase-I BNCT dose-escalation protocol for the treatment of metastatic melanoma. The first four irradiations, in which the boron agent boronophenylalanine (L-BPA) was administered orally in a fruit juice suspension, were done using epithermal neutrons from the MIT research reactor employing four fractions. The fifth irradiation, in which the subject received the fructose form of BPA (BPA-f) via intravenous infusion, was delivered in a single fraction. This paper presents the results from the measurements of {sup 10}B concentrations in tumor, normal tissue, and blood for the subjects who underwent this protocol because, to ascribe potential efficacy to BNCT, it is necessary to show that there is an adequate differential uptake of boron by tumor cells relative to normal cells, These measurements used high-resolution quantitative autoradiography, prompt gamma neutron activation analysis, and inductively coupled plasma atomic emissions spectroscopy.

  6. Boron uptake in tumors, cerebrum and blood from [10B]NA4B24H22S2

    DOEpatents

    Slatkin, Daniel N.; Micca, Peggy L.; Fairchild, Ralph G.

    1988-08-02

    A stable boronated (.sup.10 B-labeled) compound, sodium mercaptoundecahydrododecaborate is infused in the form of the disulfide dimer, [.sup.10 B]Na.sub.4 B.sub.24 H.sub.22 S.sub.2, at a dose of about 200 .mu.g .sup.10 B per gm body weight. The infusion is performed into the blood or peritoneal cavity of the patient slowly over a period of many days, perhaps one week or more, at the rate of roughly 1 .mu.g .sup.10 B per gm body weight per hour. Use of this particular boronated dimer in the manner or similarly to the manner so described permits radiotherapeutically effective amounts of boron to accumulate in tumors to be treated by boron neutron capture radiation therapy and also permits sufficient retention of boron in tumor after the cessation of the slow infusion, so as to allow the blood concentration of .sup.10 B to drop or to be reduced artificially to a radiotherapeutically effective level, less than one-half of the concentration of .sup.10 B in the tumor.

  7. Boron uptake in tumors, cerebrum and blood from [10B]NA4B24H22S2

    DOEpatents

    Slatkin, Daniel N.; Micca, Peggy L.; Fairchild, Ralph G.

    1988-01-01

    A stable boronated (.sup.10 B-labeled) compound, sodium mercaptoundecahydrododecaborate is infused in the form of the disulfide dimer, [.sup.10 B]Na.sub.4 B.sub.24 H.sub.22 S.sub.2, at a dose of about 200 .mu.g .sup.10 B per gm body weight. The infusion is performed into the blood or peritoneal cavity of the patient slowly over a period of many days, perhaps one week or more, at the rate of roughly 1 .mu.g .sup.10 B per gm body weight per hour. Use of this particular boronated dimer in the manner or similarly to the manner so described permits radiotherapeutically effective amounts of boron to accumulate in tumors to be treated by boron neutron capture radiation therapy and also permits sufficient retention of boron in tumor after the cessation of the slow infusion, so as to allow the blood concentration of .sup.10 B to drop or to be reduced artificially to a radiotherapeutically effective level, less than one-half of the concentration of .sup.10 B in the tumor.

  8. Helium-3 and boron-10 concentration and depth measurements in alloys and semiconductors using NDP

    NASA Astrophysics Data System (ADS)

    Ünlü, Kenan; Saglam, Mehmet; Wehring, Bernard W.

    1999-02-01

    Neutron Depth Profiling (NDP) is a nondestructive near surface technique that is used to measure concentration versus absolute depth of several isotopes of light mass elements in various substrates. NDP is based on absorption reaction of thermal neutrons with the isotope of interest. Charged particles and recoil atoms are generated in the reaction. The depth profiles are determined by measuring the residual energy of the charged particles or the recoil atoms. The NDP technique has became an increasingly important method to measure depth profiles of 3He and 10B in alloys and semiconductor materials. A permanent NDP facility has been installed on the tangential beam port of the University of Texas (UT) TRIGA Mark-II research reactor. One of the standard applications of the UT-NDP facility involves the determination of boron profiles of borophosphosilicate glass (BPSG) samples. NDP is also being used in combination with electron microscopy measurements to determine radiation damage and microstructural changes in stainless steel samples. This is done to study the long-term effects of high-dose alpha irradiation for weapons grade plutonium encapsulation. Measurements of implanted boron-10 concentration and depth profiles of semiconductor materials in order to calibrate commercial implanters is another application at the UT-NDP facility. The concentration and depth profiles measured with NDP and SIMS are compared with reported data given by various vendors or different implanters in order to verify implant quality of semiconductor wafers. The results of the measurements and other possible applications of NDP are presented.

  9. The Multi-Blade Boron-10-based neutron detector for high intensity neutron reflectometry at ESS

    NASA Astrophysics Data System (ADS)

    Piscitelli, F.; Messi, F.; Anastasopoulos, M.; Bryś, T.; Chicken, F.; Dian, E.; Fuzi, J.; Höglund, C.; Kiss, G.; Orban, J.; Pazmandi, P.; Robinson, L.; Rosta, L.; Schmidt, S.; Varga, D.; Zsiros, T.; Hall-Wilton, R.

    2017-03-01

    The Multi-Blade is a Boron-10-based gaseous detector introduced to face the challenge arising in neutron reflectometry at pulsed neutron sources. Neutron reflectometers are the most challenging instruments in terms of instantaneous counting rate and spatial resolution. This detector has been designed to cope with the requirements set for the reflectometers at the upcoming European Spallation Source (ESS) in Sweden. Based on previous results obtained at the Institut Laue-Langevin (ILL) in France, an improved demonstrator has been built at ESS and tested at the Budapest Neutron Centre (BNC) in Hungary and at the Source Testing Facility (STF) at the Lund University in Sweden. A detailed description of the detector and the results of the tests are discussed in this manuscript.

  10. Boron-10 analyses using prompt gamma neutron activation and ICP-AES

    SciTech Connect

    Riley, K.J.; Harling, O.K.

    1996-12-31

    Boron-10 quantification is a vital part of the phase I clinical trials that are in progress under the Massachusetts Institute of Technology (MIT)/New England Deaconess Hospital (NEDH) joint BNCT project. Accurate knowledge of the {sup 10}B content of blood as a function of time and immediately prior to irradiation is needed to calculate the total dose delivered to healthy tissue. The MIT/NEDH group continually seeks to improve and refine quantification methods to achieve greater sensitivity and faster analysis time. Rapid analysis is desirable so that irradiation can be initiated quickly, while high sensitivity will be needed to analyze very small samples. Brain tumor biopsies may be quite small, especially in cases where the tumor is not resectable. An upgraded version of the MIT prompt gamma neutron activation analysis (PGNAA) facility and an inductively coupled plasma atomic emission spectroscopy (ICP-AES) machine with a high-efficiency nebulizer (HEN) have been used to analygze {sup 10}B content in small samples down to the size range of needle biopsies ({approx} 0.03 ml).

  11. Neutron depth profiling measurements for implanted boron-10 characterization in semiconductor materials

    SciTech Connect

    Uenlue, K.; Saglam, M.; Wehring, B.W.

    1997-12-01

    The implantation of boron and other elements affects the physical and electrical properties of semiconductor materials. The quality of semiconductor devices is determined mainly by the dose and depth distribution of boron in the near-surface region and across interfacial boundaries. The capability to measure these quantities accurately is becoming more important with the production of {open_quotes}shallow junction{close_quotes} devices. A number of techniques are available to measure the boron doses and depth distribution in semiconductor materials, some of which have been developed in the past two decades. Traditionally, the semiconductor industry uses second ion mass spectroscopy (SIMS) for this purpose.

  12. Biodistribution of GB-10 (Na(2)(10)B10H10 compound for boron neutron capture therapy (BNCT) in an experimental model of oral cancer in the hamster cheek pouch.

    PubMed

    Heber, Elisa; Trivillin, Verónica A; Nigg, David; Kreimann, Erica L; Itoiz, Maria E; Rebagliati, Raúl J; Batistoni, Daniel; Schwint, Amanda E

    2004-04-01

    We previously proposed the hamster cheek pouch model of oral cancer for BNCT studies. We herein present the biodistribution of a non-toxic boron compound, GB-10 (Na(2)(10)B10H10), in this model to assess its potential for BNCT or BNCT enhanced Fast Neutron Therapy. We evaluated the uptake and retention of GB-10 in tumour and precancerous tissue and in potentially dose-limiting, clinically relevant normal tissues. Mean tumour boron concentration delivered by GB-10 (50mgB/kg) peaked to 77.7+/-28.0 ppm at 20min post-administration and remained at therapeutically useful values of 31.9+/-21.4 ppm at 3h. The clearance rate for normal tissues was faster than for tumour tissue. The consistently low brain and spinal cord values would preclude normal tissue toxicity. The uptake of GB-10 by precancerous tissue may be of potential use in the treatment of field cancerized areas. GB-10 was deposited homogeneously in different tumour areas, an asset when treating heterogenous tumours. The data suggests that the joint administration of BPA and GB-10 may improve the therapeutic efficacy of BNCT. GB-10 is a potential boron carrier for BNCT of head and neck tumours and for BNCT-FNT.

  13. Microstructure of a Creep-Resistant 10 Pct Chromium Steel Containing 250 ppm Boron

    NASA Astrophysics Data System (ADS)

    Golpayegani, Ardeshir; Liu, Fang; Svensson, Henrik; Andersson, Marcus; Andrén, Hans-Olof

    2011-04-01

    The microstructure of a trial martensitic chromium steel containing a high content of boron (250 ppm) was characterized in detail in the as-tempered and aged conditions. This steel has a similar composition and heat treatment as the TAF steel that still is unsurpassed in creep strength among all 9 to 12 pct chromium steels. Characterization was performed by using scanning electron microscopy, energy-filtered transmission electron microscopy, secondary ion mass spectroscopy, and atom probe tomography. Focus was placed on investigating different types of precipitates that play a key role in improving the creep resistance of these steels. The low tempering temperature of 963 K (690 °C) is enough for the precipitation of the full volume fraction of both MX and M23C6. A high boron content, more than 1 at. pct, was found in M23C6 precipitates and they grow slowly during aging. The high boron level in the steel results in metal borides rather than BN with the approximate formula (Mo0.66Cr0.34)2(Fe0.75V0.25)B2. Two families of MX precipitates were found, one at lath boundaries about 35 nm in size and one dense inside the laths, only 5 to 15 nm in size.

  14. Boron uptake in tumors, cerebrum and blood from (/sup 10/B)Na/sub 4/B/sub 24/H/sub 22/S/sub 2/

    DOEpatents

    Slatkin, D.N.; Micca, P.L.; Fairchild, R.G.

    1986-03-11

    A stable boronated (/sup 10/B-labeled) compound, sodium mercaptoundecahydrododecaborate is infused in the form of the disulfide dimer, (/sup 10/B)Na/sub 4/B/sub 24/H/sub 22/S/sub 2/, at a dose of about 200 ..mu..g /sup 10/B per gm body weight. The infusion is preformed into the blood or peritoneal cavity of the patient slowly over a period of many days, perhaps one week or more, at the rate of roughly 1 ..mu..g /sup 10/B per gm body weight per hour. Use of this particular boronated dimer in the manner or similarly to the manner so described permits radiotherapeutically effective amounts of boron to accumulate in tumors to be treated by boron neutron capture radiation therapy and also permits sufficient retention of boron in tumor after the cessation of the slow infusion, so as to allow the blood concentration of /sup 10/B to drop or to be reduced artificially to a radiotherapeutically effective level, less than one-half of the concentration of /sup 10/B in the tumor. 1 tab.

  15. Boron-Based Drug Design.

    PubMed

    Ban, Hyun Seung; Nakamura, Hiroyuki

    2015-06-01

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

  16. Status of Boron Combustion Research

    DTIC Science & Technology

    1984-10-01

    layer . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5 Vaporization of boron oxide drops In wet and dry .-. environments. From Turns et al . ([1...19 10 SEN photographs of boron slurry agglomerates: a. Oxide layer present: b. Oxide layer absent.From Turns et al . [7...21 -- f- 11 Ignition of boron agglomerates as a function of particle and agglomerate diameters. From Shevahuk et al . [26

  17. Advances in analytical techniques for neutron capture therapy: thin layer chromatography matrix and track etch thin layer chromatography methods for boron-10 analysis

    SciTech Connect

    Schremmer, J.M.; Noonan, D.J.

    1987-09-01

    A new track etch autoradiographic technique for quantitating boron-10 containing compounds used for neutron capture therapy is described. Instead of applying solutions of Cs2B12H11SH and its oxidation products directly to solid-state nuclear track detectors, diethylaminoethyl cellulose thin layer chromatography (TLC) plates are utilized as sample matrices. The plates are juxtaposed with Lexan polycarbonate detectors and irradiated in a beam of thermal neutrons. The detectors are then chemically etched, and the resultant tracks counted with an optoelectronic image analyzer. Sensitivity to boron-10 in solution reaches the 1 pg/microliter level, or 1 ppb. In heparinized blood samples, 100 pg boron-10/microliter are detected. This TLC matrix method has the advantage that sample plates can be reanalyzed under different reactor conditions to optimize detector response to the boron-10 carrier material. Track etch/TLC allows quantitation of the purity of boron neutron capture therapy compounds by utilizing the above method with TLC plates developed in solvent systems that resolve Cs2B12H11SH and its oxidative analogs. Detectors irradiated in juxtaposition to the thin layer chromatograms are chemically etched, and the tracks are counted in the sample lane from the origin of the plate to the solvent front. A graphic depiction of the number of tracks per field yields a quantitative analysis of compound purity.

  18. Pilot clinical study of boron neutron capture therapy for recurrent hepatic cancer involving the intra-arterial injection of a (10)BSH-containing WOW emulsion.

    PubMed

    Yanagie, Hironobu; Higashi, Syushi; Seguchi, Koji; Ikushima, Ichiro; Fujihara, Mituteru; Nonaka, Yasumasa; Oyama, Kazuyuki; Maruyama, Syoji; Hatae, Ryo; Suzuki, Minoru; Masunaga, Shin-ichiro; Kinashi, Tomoko; Sakurai, Yoshinori; Tanaka, Hiroki; Kondo, Natsuko; Narabayashi, Masaru; Kajiyama, Tetsuya; Maruhashi, Akira; Ono, Koji; Nakajima, Jun; Ono, Minoru; Takahashi, Hiroyuki; Eriguchi, Masazumi

    2014-06-01

    A 63-year-old man with multiple HCC in his left liver lobe was enrolled as the first patient in a pilot study of boron neutron capture therapy (BNCT) involving the selective intra-arterial infusion of a (10)BSH-containing water-in-oil-in-water emulsion ((10)BSH-WOW). The size of the tumorous region remained stable during the 3 months after the BNCT. No adverse effects of the BNCT were observed. The present results show that (10)BSH-WOW can be used as novel intra-arterial boron carriers during BNCT for HCC.

  19. Fabrication of boron articles

    DOEpatents

    Benton, Samuel T.

    1976-01-01

    This invention is directed to the fabrication of boron articles by a powder metallurgical method wherein the articles are of a density close to the theoretical density of boron and are essentially crackfree. The method comprises the steps of admixing 1 to 10 weight percent carbon powder with amorphous boron powder, cold pressing the mixture and then hot pressing the cold pressed compact into the desired article. The addition of the carbon to the mixture provides a pressing aid for inhibiting the cracking of the hot pressed article and is of a concentration less than that which would cause the articles to possess significant concentrations of boron carbide.

  20. Bulk synthesis, growth mechanism and properties of highly pure ultrafine boron nitride nanotubes with diameters of sub-10 nm.

    PubMed

    Huang, Yang; Lin, Jing; Tang, Chengchun; Bando, Yoshio; Zhi, Chunyi; Zhai, Tianyou; Dierre, Benjamin; Sekiguchi, Takashi; Golberg, Dmitri

    2011-04-08

    As a structural analogue of the carbon nanotube (CNT), the boron nitride nanotube (BNNT) has become one of the most intriguing non-carbon nanostructures. However, up to now the pre-existing restrictions/limitations of BNNT syntheses have made the progress in their research rather modest. This work presents a new route toward the synthesis of highly pure ultrafine BNNTs based on a modified boron oxide (BO) CVD method. A new effective precursor--a mixture of Li₂O and B--has been proposed for the growth of thin, few-layer BNNTs in bulk amounts. The Li₂O utilized as the precursor plays the crucial role for the present nanotube growth. The prepared BNNTs have average external diameters of sub-10 nm and lengths of up to tens of µm. Electron energy loss spectrometry and Raman spectroscopy demonstrate the ultimate phase purity of the ultrafine BNNTs. Property studies indicate that the ultrafine nanotubes are perfect electrical insulators exhibiting superb resistance to oxidation and strong UV emission. Moreover, their reduced diameters lead to a dramatically decreased population of defects within the tube walls and result in the observation of near-band-edge (NBE) emission at room temperature.

  1. Bulk synthesis, growth mechanism and properties of highly pure ultrafine boron nitride nanotubes with diameters of sub-10 nm

    NASA Astrophysics Data System (ADS)

    Huang, Yang; Lin, Jing; Tang, Chengchun; Bando, Yoshio; Zhi, Chunyi; Zhai, Tianyou; Dierre, Benjamin; Sekiguchi, Takashi; Golberg, Dmitri

    2011-04-01

    As a structural analogue of the carbon nanotube (CNT), the boron nitride nanotube (BNNT) has become one of the most intriguing non-carbon nanostructures. However, up to now the pre-existing restrictions/limitations of BNNT syntheses have made the progress in their research rather modest. This work presents a new route toward the synthesis of highly pure ultrafine BNNTs based on a modified boron oxide (BO) CVD method. A new effective precursor—a mixture of Li2O and B—has been proposed for the growth of thin, few-layer BNNTs in bulk amounts. The Li2O utilized as the precursor plays the crucial role for the present nanotube growth. The prepared BNNTs have average external diameters of sub-10 nm and lengths of up to tens of µm. Electron energy loss spectrometry and Raman spectroscopy demonstrate the ultimate phase purity of the ultrafine BNNTs. Property studies indicate that the ultrafine nanotubes are perfect electrical insulators exhibiting superb resistance to oxidation and strong UV emission. Moreover, their reduced diameters lead to a dramatically decreased population of defects within the tube walls and result in the observation of near-band-edge (NBE) emission at room temperature.

  2. Method for separating boron isotopes

    DOEpatents

    Rockwood, Stephen D.

    1978-01-01

    A method of separating boron isotopes .sup.10 B and .sup.11 B by laser-induced selective excitation and photodissociation of BCl.sub.3 molecules containing a particular boron isotope. The photodissociation products react with an appropriate chemical scavenger and the reaction products may readily be separated from undissociated BCl.sub.3, thus effecting the desired separation of the boron isotopes.

  3. Investigation of the Effective NN Interaction in the Nuclear Medium Through BORON-10(POLARIZED Proton, Polarized Proton') BORON-10 Polarization Transfer.

    NASA Astrophysics Data System (ADS)

    Chang, Shining X.

    An investigation of transitions in ^ {10}rm B(vec p,vec p^ ')^{10}B was undertaken to characterize changes to the NN effective interaction that take place in the nuclear medium. The K600 high resolution spectrometer provided a means to observe the excitation of discrete states in the recoil ^{10 }B nucleus. The use of polarized beam at 200 MeV and the polarimeter mounted after the K600 focal plane detectors produced a variety of observables that can delineate the spin-dependence of the effective interaction. In this experiment measurements have been made for the ^{10}B in-plane polarization transfer observables D_sigma=D_{SS ^'} cos alpha+D _{SL^'} sin alpha and D_lambda=D _{LS^'} cos alpha+D_{LL^'} sin alpha over five scattering angles ranging from theta_{lab}=20 ^circ to 60^circ. The angle alpha is the spin -precession angle for protons passing through the K600 spectrometer. This is an extension of former measurements (E338) on the normal component polarization observables for transitions in ^{10}rm B(vec p,vec p^')^{10}B.. Distorted-wave Born approximation calculations made with the programs LEA and DW81 were carried out for a number of low-lying, natural-parity transitions. The calculations are more consistent with the experimental data when the interaction does not include corrections to the isoscalar central and spin-orbit portions of the effective NN interaction that arise from Pauli blocking effects. Further study is needed since this conclusion contradicts results on nearby nuclei such as ^ {16}O. To provide information on the isovector part of the spin-orbit and tensor portions of the effective NN interaction, a detailed study was made of the 0 ^+, T = 1 state at E_{x } = 1.74 MeV. Constraints on the transition formfactor were taken from electron scattering measurements. The structure of this state is well-described by assuming a single particle-hole component (1p_{3/2 }1p_sp{3/2}{-1}), and the reaction mechanism was taken E_ {x}=1.71 MeV. Constraints on

  4. Boron isotope exchange in a heterogeneous boron-boron fluoride system

    SciTech Connect

    Begak, O.Yu.; Fedorov, V.V.

    1988-11-01

    Studies have been made on exchange between /sup 10/B and /sup 11/B in heterogeneous systems containing finely divided amorphous boron and BF/sub 3/ gas. The kinetic and thermodynamic parameters have been examined. The self-diffusion coefficient for boron in amorphous boron has been determined at 973-1273 K.

  5. The vibrational spectra of the boron halides and their molecular complexes. Part 10. The complexes of boron trifluoride with ammonia and its methyl derivatives. An ab initio study

    NASA Astrophysics Data System (ADS)

    Gaffoor, Fatima; Ford, Thomas A.

    2008-11-01

    Ab initio calculations, at the level of second order Møller-Plesset perturbation theory, and using a triple-zeta Gaussian basis set with polarization and diffuse functions on all atoms, have been carried out on the donor-acceptor complexes of boron trifluoride with ammonia and its mono-, di- and trimethyl derivatives. The structures, interaction energies and vibrational spectra of the complexes have been determined. An eclipsed and a staggered conformer have been examined for each complex, and the preferred conformer was found to be the staggered species in each case. The computed data have been compared with those for some similar complexes containing boron trifluoride and a series of oxygen and sulphur electron donors (water, hydrogen sulphide, methanol, methanethiol, dimethyl ether and dimethyl sulphide) and the effect of successive methyl substitution in all three series has been investigated.

  6. Why nanoscale tank treads move? Structures, chemical bonding, and molecular dynamics of a doped boron cluster B10C.

    PubMed

    Wang, Ying-Jin; Guo, Jin-Chang; Zhai, Hua-Jin

    2017-07-13

    Planar boron clusters form dynamic rotors, either as molecular Wankel motors or subnanoscale tank treads, the latter being exemplified by an elongated B11(-) cluster. For an in-depth mechanistic understanding of the rotors, we investigate herein a doped boron cluster, B10C, in which a C atom isovalently substitutes B(-) in the B11(-) tank tread. Two critical structures are achieved: the Cs ((1)A') global minimum (GM) with C positioned in the peripheral ring and the C2v ((1)A1) local minimum (LM) with C in the diatomic core. In the GM the C atom completely halts the rotation of B10C, whereas in the LM the dynamic fluxionality remains. The energy barriers for in-plane rotation differ markedly: 12.93/18.31 kcal mol(-1) for GM versus 1.84 kcal mol(-1) for LM at the single-point CCSD(T) level. The GM rotates via two transition states (TS), compared to one for the LM. Chemical bonding in the structures is elucidated via canonical molecular orbital (CMO) analysis, adaptive natural density partitioning (AdNDP), electron localization functions (ELFs), and Wiberg bond indices (WBI). Electron delocalization is shown to be essential for structural fluxionality. In particular, the variation of WBI from the GM or LM geometries to their TS structures correlates positively with the energy barrier, which offers a quasi-quantitative measure of the barrier height and hence controls the dynamics. This finding may be extended to all molecular rotors. It also helps rationalize why a strongly covalently bound system can behave dynamically in a manner similar to a weakly bound one; it is the latter that is generally anticipated to be structurally fluxional.

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

    NASA Astrophysics Data System (ADS)

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

    2008-05-01

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

  8. (10)B/(11)B isotopic ratio and atomic composition of boron carbide: Determination by proton induced γ-ray emission and proton elastic backscattering spectrometry.

    PubMed

    Sunitha, Y; Kumar, Sanjiv

    2017-10-01

    The (10)B/(11)B isotopic ratio and the atomic composition of boron carbide, an important non-metallic ceramic, have been determined non-destructively by the particle induced γ-ray emission (PIGE) and elastic backscattering spectrometry (EBS) techniques with proton beams. The analysis has been performed on powder as well as sintered ceramics containing boron in natural or (10)B enriched composition. The PIGE technique, performed at a 4.0-4.2MeV proton energy, utilizes the (10)B(p,αγ)(7)Be, (10)B(p,p'γ)(10)B and (11)B(p, p'γ)(11)B nuclear reactions for (a) the isotopic analysis of boron and (b) the determination of total boron, and the (13)C(p,p'γ)(13)C nuclear reaction for the determination of carbon. The irradiation conditions were optimized by determining the thick targets yields of prompt γ-rays, characteristic of these reactions, in the 3.0-4.2MeV proton energy range. The quantitative analysis was performed by comparison with standards taking into account the attenuation of γ-rays in the specimens. The uncertainty in the determination of the (10)B/(11)B isotopic ratio and the B/C atomic ratio is about 2% and about 5% respectively. The analysis by EBS, on the other hand, involves the (10)B(p,p)(10)B, (11)B(p,p)(11)B and (12)C(p,p)(12)C elastic scatterings at the 2.0MeV proton energy. This method too yields satisfactory results. Between the two, PIGE is the method of choice for bulk analysis while EBS is useful in discerning compositional variations in surface regions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Assessment of (10)B concentration in boron neutron capture therapy: potential of image-guided therapy using (18)FBPA PET.

    PubMed

    Shimosegawa, Eku; Isohashi, Kayako; Naka, Sadahiro; Horitsugi, Genki; Hatazawa, Jun

    2016-12-01

    In boron neutron capture therapy (BNCT) for cancer, the accurate estimation of (10)B tissue concentrations, especially in neighboring normal organs, is important to avoid adverse effects. The (10)B concentration in normal organs after loading with (10)B, however, has not been established in humans. In this study, we performed 4-borono-2-[(18)F]-fluoro-phenylalanine ((18)FBPA) PET in healthy volunteers and estimated the chronological changes in the (10)B concentrations of normal organs. In 6 healthy volunteers, whole-body (18)FBPA PET scans were repeated 7 times during 1 h, and the mean (18)FBPA distributions of 13 organs were measured. Based on the (18)FBPA PET data, we then estimated the changes in the (10)B concentrations of the organs when the injection of a therapeutic dose of (10)BPA-fructose complex ((10)BPA-fr; 30 g, 500 mg/kg body weight) was assumed. The maximum mean (18)FBPA concentrations were reached at 2-6 min after injection in all the organs except the brain and urinary bladder. The mean (18)FBPA concentration in normal brain plateaued at 24 min after injection. When the injection of a therapeutic dose of (10)BPA-fr was assumed, the estimated mean (10)B concentration in the kidney increased to 126.1 ± 24.2 ppm at 3 min after injection and then rapidly decreased to 30.9 ± 7.4 ppm at 53 min. The estimated mean (10)B concentration in the bladder gradually increased and reached 383.6 ± 214.7 ppm at 51 min. The mean (10)B concentration in the brain was estimated to be 7.6 ± 1.5 ppm at 57 min. (18)FBPA PET has a potential to estimate (10)B concentration of normal organs before neutron irradiation of BNCT when several assumptions are validated in the future studies.

  10. Zeolitic Boron Imidazolate Frameworks**

    PubMed Central

    Zhang, Jian; Wu, Tao; Zhou, Cong; Chen, Shumei; Feng, Pingyun; Bu, Xianhui

    2009-01-01

    From porous AlPO4 to porous BIFs Reported here are a family of crystalline materials based on boron imidazolate frameworks (BIFs). It is demonstrated that the synthetic method, which is based on the crosslinking of various pre-synthesized boron imidazolates by monovalent cations (Li+ and Cu+), is capable of generating a large variety of open frameworks ranging from the 4-connected zeolitic sodalite type to the 3-connected chiral (10,3)-a type. PMID:19241428

  11. Effect of electroporation on cell killing by boron neutron capture therapy using borocaptate sodium (10B-BSH).

    PubMed

    Ono, K; Kinashi, Y; Masunaga, S; Suzuki, M; Takagaki, M

    1998-12-01

    The cell membrane permeability of 10B-enriched borocaptate sodium (BSH) and the extent to which BSH is accumulated in cells are controversial. To elucidate these points and to enhance the accumulation of BSH in cells, the effect of electroporation on boron neutron capture therapy (BNCT) using BSH was investigated. The first group of SCCVII tumor cells was incubated in culture medium with 10B-BSH or 10B-enriched boric acid, and exposed to neutrons from the heavy water facility of the Kyoto University Reactor. More than 99% of neutrons were thermal neutrons at flux base. The second group was pretreated with electroporation in combination with 10B-BSH, and thereafter the cells were irradiated with neutrons. The cell-killing effect of BNCT was measured by colony formation assay. The surviving cell fraction decreased exponentially with neutron fluence, and addition of BSH significantly enhanced the cell-killing effect of NCT depending on 10B concentration and the preincubation time of cells in the BSH-containing culture medium. The electroporation of cells with BSH markedly enhanced the BNCT effect in comparison with that obtained with preincubation alone. The effect of BSH-BNCT with electroporation was almost equal to that of BNCT using 10B-boric acid at the same 10B concentration. The effect of BNCT on cells pretreated with BSH and electroporation was not reduced by repeated washing of the cells before neutron irradiation. Decrease of the effect of BSH-BNCT plus electroporation with increase in the waiting time between the electroporation and the neutron irradiation could be explained in terms of the extent of cell growth during that time. These data suggest that BSH penetrates the cells slowly and remains after washing. Electroporation can introduce BSH into the cells very efficiently, and BSH thus introduced stays in the cells and is not lost in spite of the intensive washing of the cells. Therefore, if electroporation is applied to tumors after BSH injection, 10B

  12. Boron cosmochemistry

    NASA Technical Reports Server (NTRS)

    Curtis, D. B.; Gladney, E. S.

    1985-01-01

    The abundances of boron, silicon, sulfur, and sodium were determined in 50 pieces of 28 chondritic meteorites. Boron abundances are found to define compositionally distinct domains within type C2M carbonaceous chondrites and petrologic type 5 and 6 ordinary chondrites. These domains may manifest the redistribution of boron within meteorites in response to low-temperature hydrous processes in C2M chondrites and high-temperature metamorphic processes in high petrologic type ordinary chondrites. Assuming that the redistribution was limited to regions comparable in size to the mass of the available meteorites, the boron abundance in unaltered material is determined. The depletion factors for boron in chondritic subgroups correlate with those for sulfur in the same subgroups. This correlation indicates that boron, like sulfur, is a moderately volatile element with a condensation temperature between 400 and 900 K.

  13. Boron supercapacitors

    DOE PAGES

    Zhan, Cheng; Zhang, Pengfei; Dai, Sheng; ...

    2016-11-16

    Supercapacitors based on the electric double-layer mechanism use porous carbons or graphene as electrodes. To move beyond this paradigm, we propose boron supercapacitors to leverage two-dimensional (2D) boron sheets’ metallicity and low weight. Six 2D boron sheets from both previous theoretical design and experimental growth are chosen as test electrodes. By applying joint density functional theory (JDFT) to the electrode–electrolyte system, we examine how the 2D boron sheets charge up against applied potential. JDFT predicts that these 2D boron sheets exhibit specific capacitance on the order of 400 F/g, about four times that of graphene. As a result, our workmore » suggests that 2D boron sheets are promising electrodes for supercapacitor applications.« less

  14. Boron supercapacitors

    SciTech Connect

    Zhan, Cheng; Zhang, Pengfei; Dai, Sheng; Jiang, De -en

    2016-11-16

    Supercapacitors based on the electric double-layer mechanism use porous carbons or graphene as electrodes. To move beyond this paradigm, we propose boron supercapacitors to leverage two-dimensional (2D) boron sheets’ metallicity and low weight. Six 2D boron sheets from both previous theoretical design and experimental growth are chosen as test electrodes. By applying joint density functional theory (JDFT) to the electrode–electrolyte system, we examine how the 2D boron sheets charge up against applied potential. JDFT predicts that these 2D boron sheets exhibit specific capacitance on the order of 400 F/g, about four times that of graphene. As a result, our work suggests that 2D boron sheets are promising electrodes for supercapacitor applications.

  15. A 10-fold improvement in the precision of boron isotopic analysis by negative thermal ionization mass spectrometry.

    PubMed

    Shen, Jason Jiun-San; You, Chen-Feng

    2003-05-01

    Boron isotopes are potentially very important to cosmochemistry, geochemistry, and paleoceanography. However, the application has been hampered by the large sample required for positive thermal ionization mass spectrometry (PTIMS), and high mass fractionation for negative-TIMS (NTIMS). Running as BO(2)(-), NTIMS is very sensitive and requires only nanogram sized samples, but it has rather poor precision (approximately 0.7-2.0 per thousand) as a result of the larger mass fractionation associated with the relatively light ion. In contrast, running as the much heavier molecule of Cs(2)BO(2)(+), PTIMS usually achieves better precision around 0.1-0.4 per thousand. Moreover, there is a consistent 10 per thousand offset in the (11)B/(10)B ratio for NIST SRM 951 standard boric acid between the NTIMS and the certified value, but the cause of this offset is unclear. In this paper, we have adapted a technique we developed earlier to measure the (138)La/(139)La using LaO(+) (1) to improve the NTIMS technique for BO(2). We were able to correct for instrumental fractionation by measuring BO(2)(-) species not only at masses of 42 and 43, but also at 45, which enabled us to normalize (45)BO(2)/(43)BO(2) to an empirical (18)O/(16)O value. We found that both I(45)/I(42) = ((11)B(16)O(18)O/(10)B(16)O(16)O) and (I(43)/I(42))(C) = ((11)B(16)O(16)O/(10)B(16)O(16)O) vary linearly with (I(45)/I(43))(C) x 0.5 = ((11)B(16)O(18)O/(11)B(16)O(16)O) x 0.5 = (18)O/(16)O. In addition, different activators and different chemical forms of B yield different slopes for the fractionation lines. After normalizing (11)B(16)O(18)O/(11)B(16)O(16)O x 0.5 to a fixed (18)O/(16)O value, we obtained a mean (11)B/(10)B value of NIST SRM 951 that matches the NIST certified value at 4.0430 +/- 0.0015 (+/-0.36 per thousand, n = 11). As a result, our technique can achieve precision and accuracy comparable to that of PTIMS with only 1 per thousand of the sample required. This new NTIMS technique for B isotopes is

  16. Application of 10(13) ohm Faraday cup current amplifiers for boron isotopic analyses by solution mode and laser ablation MC-ICP-MS.

    PubMed

    Lloyd, Nicholas S; Sadekov, Aleksey Yu; Misra, Sambuddha

    2017-10-09

    Boron isotope ratios (δ(11) B values) are used as a proxy for seawater paleo-pH, amongst several other applications. The analytical precision can be limited by the detection of low intensity ion beams from limited sample amounts. High-gain amplifiers offer improvements in signal/noise ratio and can be used to increase measurement precision and reduce sample amounts. 10(13) ohm amplifier technology has previously been applied to several radiogenic systems, but has thus far not been applied to non-traditional stable isotopes. Here we apply 10(13) ohm amplifier technology for the measurement of boron isotope ratios using solution mode MC-ICP-MS and laser ablation mode (LA-) MC-ICP-MS techniques. Precision is shown for reference materials as well as for low-volume foraminifera samples. The baseline uncertainty for a 0.1 pA (10) B ion beam is reduced to < 0.1 ‰ for a typical measurement period. The external precision is better than 0.2 ‰ (2SD) for δ(11) B measurements for solution samples containing as little as 0.8 ng total boron. For in-situ microanalyses with LA-MC-ICP-MS, the external precision of (11) B/(10) B from an in-house calcite standard was 1 ‰ (2SD) for individual spot analyses, and 0.3 ‰ for the mean of ≥ 10 replicate spot analyses. 10(13) ohm amplifier technology is demonstrated to offer advantages for the determination of δ(11) B values by both MC-ICP-MS and LA-MC-ICP-MS for small samples of biogenic carbonates, such as foraminifera shells. 10(13) ohm amplifier technology will also be of benefit to other non-traditional stable isotope measurements. This article is protected by copyright. All rights reserved.

  17. LITHIUM-BERYLLIUM-BORON ISOTOPIC COMPOSITIONS IN METEORITIC HIBONITE: IMPLICATIONS FOR ORIGIN OF {sup 10}Be AND EARLY SOLAR SYSTEM IRRADIATION

    SciTech Connect

    Liu, Ming-Chang; Nittler, Larry R.; Alexander, Conel M. O'D.; Lee, Typhoon

    2010-08-10

    NanoSIMS isotopic measurements of Li, Be, and B in individual hibonite grains extracted from the Murchison meteorite revealed that {sup 10}B excesses correlate with the {sup 9}Be/{sup 11}B ratios in {sup 26}Al-free PLAty hibonite Crystals. From these data, an initial {sup 10}Be/{sup 9}Be = (5.5 {+-} 1.6) x 10{sup -4} (2{sigma}) and {sup 10}B/{sup 11}B = 0.2508 {+-} 0.0015 can be inferred. On the other hand, chondritic boron isotopic compositions were found in {sup 26}Al-bearing Spinel-HIBonite spherules, most likely due to contamination with normal boron. No {sup 7}Li excesses due to {sup 7}Be decay were observed. When combined with previously reported data, the new data yield the best defined {sup 10}Be/{sup 9}Be = (5.3 {+-} 1.0) x 10{sup -4} (2{sigma}) and {sup 10}B/{sup 11}B = 0.2513 {+-} 0.0012 for PLACs. A comparison of this value and the best constrained {sup 10}Be/{sup 9}Be = (8.8 {+-} 0.6) x 10{sup -4} in CV Ca-Al-rich inclusions supports a heterogeneous distribution of {sup 10}Be and its protosolar irradiation origin. We consider two possible irradiation scenarios that could potentially lead to the observed Li-Be-B isotopic compositions in PLACs. Although in situ irradiation of solids with hibonite chemistry seems to provide the simplest explanation, more high quality data will be needed for quantitatively constraining the irradiation history.

  18. Experimental Studies of Boronophenylalanine ((10)BPA) Biodistribution for the Individual Application of Boron Neutron Capture Therapy (BNCT) for Malignant Melanoma Treatment.

    PubMed

    Carpano, Marina; Perona, Marina; Rodriguez, Carla; Nievas, Susana; Olivera, Maria; Santa Cruz, Gustavo A; Brandizzi, Daniel; Cabrini, Romulo; Pisarev, Mario; Juvenal, Guillermo Juan; Dagrosa, Maria Alejandra

    2015-10-01

    Patients with the same histopathologic diagnosis of cutaneous melanoma treated with identical protocols of boron neutron capture therapy (BNCT) have shown different clinical outcomes. The objective of the present studies was to evaluate the biodistribution of boronophenilalanina ((10)BPA) for the potential application of BNCT for the treatment of melanoma on an individual basis. The boronophenilalanine (BPA) uptake was evaluated in 3 human melanoma cell lines: MEL-J, A375, and M8. NIH nude mice were implanted with 4 10(6) MEL-J cells, and biodistribution studies of BPA (350 mg/kg intraperitoneally) were performed. Static infrared imaging using a specially modified infrared camera adapted to measure the body infrared radiance of small animals was used. Proliferation marker, Ki-67, and endothelial marker, CD31, were analyzed in tumor samples. The in vitro studies demonstrated different patterns of BPA uptake for each analyzed cell line (P<.001 for MEL-J and A375 vs M8 cells). The in vivo studies showed a maximum average boron concentration of 25.9 ± 2.6 μg/g in tumor, with individual values ranging between 11.7 and 52.0 μg/g of (10)B 2 hours after the injection of BPA. Tumor temperature always decreased as the tumors increased in size, with values ranging between 37 °C and 23 °C. A significant correlation between tumor temperature and tumor-to-blood boron concentration ratio was found (R(2) = 0.7, rational function fit). The immunohistochemical studies revealed, in tumors with extensive areas of viability, a high number of positive cells for Ki-67, blood vessels of large diameter evidenced by the marker CD31, and a direct logistic correlation between proliferative status and boron concentration difference between tumor and blood (R(2) = 0.81, logistic function fit). We propose that these methods could be suitable for designing new screening protocols applied before melanoma BNCT treatment for each individual patient and lesion. Copyright © 2015 Elsevier Inc

  19. Experimental Studies of Boronophenylalanine ({sup 10}BPA) Biodistribution for the Individual Application of Boron Neutron Capture Therapy (BNCT) for Malignant Melanoma Treatment

    SciTech Connect

    Carpano, Marina; Perona, Marina; Rodriguez, Carla; Nievas, Susana; Olivera, Maria; Santa Cruz, Gustavo A.; Brandizzi, Daniel; Cabrini, Romulo; Pisarev, Mario; Juvenal, Guillermo Juan; Dagrosa, Maria Alejandra

    2015-10-01

    Purpose: Patients with the same histopathologic diagnosis of cutaneous melanoma treated with identical protocols of boron neutron capture therapy (BNCT) have shown different clinical outcomes. The objective of the present studies was to evaluate the biodistribution of boronophenilalanina ({sup 10}BPA) for the potential application of BNCT for the treatment of melanoma on an individual basis. Methods and Materials: The boronophenilalanine (BPA) uptake was evaluated in 3 human melanoma cell lines: MEL-J, A375, and M8. NIH nude mice were implanted with 4 10{sup 6} MEL-J cells, and biodistribution studies of BPA (350 mg/kg intraperitoneally) were performed. Static infrared imaging using a specially modified infrared camera adapted to measure the body infrared radiance of small animals was used. Proliferation marker, Ki-67, and endothelial marker, CD31, were analyzed in tumor samples. Results: The in vitro studies demonstrated different patterns of BPA uptake for each analyzed cell line (P<.001 for MEL-J and A375 vs M8 cells). The in vivo studies showed a maximum average boron concentration of 25.9 ± 2.6 μg/g in tumor, with individual values ranging between 11.7 and 52.0 μg/g of {sup 10}B 2 hours after the injection of BPA. Tumor temperature always decreased as the tumors increased in size, with values ranging between 37°C and 23°C. A significant correlation between tumor temperature and tumor-to-blood boron concentration ratio was found (R{sup 2} = 0.7, rational function fit). The immunohistochemical studies revealed, in tumors with extensive areas of viability, a high number of positive cells for Ki-67, blood vessels of large diameter evidenced by the marker CD31, and a direct logistic correlation between proliferative status and boron concentration difference between tumor and blood (R{sup 2} = 0.81, logistic function fit). Conclusion: We propose that these methods could be suitable for designing new screening protocols applied before melanoma BNCT

  20. Effects of boron addition on a-Si(90)Ge(10):H films obtained by low frequency plasma enhanced chemical vapour deposition.

    PubMed

    Pérez, Arllene M; Renero, Francisco J; Zúñiga, Carlos; Torres, Alfonso; Santiago, César

    2005-06-29

    Optical, structural and electric properties of (a-(Si(90)Ge(10))(1-y)B(y):H) thin film alloys, deposited by low frequency plasma enhanced chemical vapour deposition, are presented. The chemical bonding structure has been studied by IR spectroscopy, while the composition was investigated by Raman spectroscopy. A discussion about boron doping effects, in the composition and bonding of samples, is presented. Transport of carriers has been studied by measurement of the conductivity dependence on temperature, which increases from 10(-3) to 10(1) Ω(-1) cm(-1) when the boron content varies from 0 to 50%. Similarly, the activation energy is between 0.62 and 0.19 eV when the doping increases from 0 to 83%. The optical properties have been determined from the film's optical transmission, using Swanepoel's method. It is shown that the optical gap varies from 1.3 to 0.99 eV.

  1. Neutron detectors comprising boron powder

    DOEpatents

    Wang, Zhehui; Morris, Christopher; Bacon, Jeffrey Darnell; Makela, Mark F; Spaulding, Randy Jay

    2013-05-21

    High-efficiency neutron detector substrate assemblies comprising a first conductive substrate, wherein a first side of the substrate is in direct contact with a first layer of a powder material comprising .sup.10boron, .sup.10boron carbide or combinations thereof, and wherein a conductive material is in proximity to the first layer of powder material; and processes of making said neutron detector substrate assemblies.

  2. Boron neutron capture therapy for cancer

    SciTech Connect

    Barth, R.E.; Soloway, A.H. ); Fairchild, R.G. State Univ. of New York, Stony Brook )

    1990-10-01

    Boron neutron capture therapy (BNCT) bring together two components that when kept separate have only minor effects on normal cells. The first component is a stable isotope of boron (boron 10) that can be concentrated in tumor cells. The second is a beam of low-energy neutrons that produces short-range radiation when absorbed, or captured, by the boron. The combination of these two conditions at the site of a tumor releases intense radiation that can destroy malignant tissues. BNCT is based on the nuclear reaction that occurs when boron 10 is irradiated with an absorbs neutrons. The neutrons that it takes up are called thermal, or slow, neutrons. They are of such low energy that they cause little tissue damage as compared with other forms of radiation such as protons, gamma rays and fast neutrons. When an atom of boron 10 captures a neutron, an unstable isotope, boron 11, forms. The boron 11 instantly fissions, yielding lithium 7 nuclei and energetic alpha particles. These heavy particles, which carry 2.79 million electron volts of energy, are a highly lethal form of radiation. If the treatment proceeds as intended, the destructive effects of the capture reaction would occur primarily in those cancer cells that have accumulated boron 10. Normal cells with low concentrations of boron would be spared.

  3. Subcellular localization of p-boronophenylalanine-delivered boron-10 in the rat 9L gliosarcoma: Cryogenic preparation in vitro and in vivo

    SciTech Connect

    Bennett, B.D.; Mumford-Zisk, J.; Morrison, G.H.; Coderre, J.A.

    1994-10-01

    A well-characterized in vitro cryogenic preparation for ion microscopic isotope imaging, which minimizes redistribution of diffusible species, was used to determine the distribution of boron in GS-9L gliosarcoma cells incubated with the boron neutron capture therapy agent, p-boronophenylalanine (BPA). At the subcellular level, boron from BPA distributes relatively homogeneously within the glioma cell. Boron from BPA was eliminated rapidly, indicating that most is unbound. Thus a large pool of boron is susceptible to diffusion artifact. Removal of this artifact increases the degree of confidence in microdosimetric results inferred from the homogeneous subcellular distribution. The ion microscopic imaging of boron in subcutaneous tumors cryofixed in situ was achieved in rats treated with BPA. Boron signals from BPA were adequate to image microdistributions at the 1-{mu}m resolution level. As in the in vitro case, boron did not localize discretely at the subcellular level. However, boron heterogeneity was seen at the tissue level. Physiologically valid cellular potassium and sodium levels were seen, which demonstrates minimized redistribution artifact. Future tissue studies designed to correlate ion microscopic boron images to microscopic structure are feasible using cryogenic sample preparation and ion microscopy. 32 refs., 4 figs.

  4. Direct current sputtering of boron from boron/boron mixtures

    DOEpatents

    Timberlake, J.R.; Manos, D.; Nartowitz, E.

    1994-12-13

    A method for coating a substrate with boron by sputtering includes lowering the electrical resistance of a boron-containing rod to allow electrical conduction in the rod; placing the boron-containing rod inside a vacuum chamber containing substrate material to be coated; applying an electrical potential between the boron target material and the vacuum chamber; countering a current avalanche that commences when the conduction heating rate exceeds the cooling rate, and until a steady equilibrium heating current is reached; and, coating the substrate material with boron by sputtering from the boron-containing rod. 2 figures.

  5. Initial boronization of PBX-M using ablation of solid boronized probes

    SciTech Connect

    Kugel, H.W.; Hirooka, Y.; Kaita, R.; Kaye, S.; Khandagle, M.; Timberlake, J.; Bell, R.; England, A.; Isler, R.; Okabayashi, M.; Paul, S.; Takahashi, H.; Tighe, W.; von Goeler, S.; Post-Zwicker, A.P.; Jones, S.

    1993-05-01

    The initial boronization of PBX-M was performed using the sequential ablation of two types of solid target probes. Probe-1 in a mushroom shape consisted of a 10.7% boronized 2-D C-C composite containing 3.6 g of boron in a B{sub 4}C binder. Probe-2 in a rectangular shape consisted of an 86% boronized graphite felt composite containing 19.5 g of 40 {mu} boron particles. After boronization with Probe-1, the loop voltage during 1 MW neutral beam heated plasmas decreased 27% and volt-sec consumption decreased 20%. Strong peripheral spectral lines from low-Z elements decreased by factors of about 5. The central oxygen density decreased 15--20%. The total radiated power during neutral beam injection decreased by 43%. Probe-2 boronization exhibited improved operating conditions similar to Probe-1, but for some parameters, a smaller percentage change occurred due to the residual boron from the previous boronization using Probe-1. The ablation rates of both probes were consistent with front face temperatures at or slightly above the boron melting point. These results confirm the effectiveness of the solid target boronization (STB) technique as a real-time impurity control method for replenishing boron depositions without the use of hazardous borane compounds.

  6. Initial boronization of PBX-M using ablation of solid boronized probes

    SciTech Connect

    Kugel, H.W.; Hirooka, Y.; Kaita, R.; Kaye, S.; Khandagle, M. . Inst. of Plasma and Fusion Research); Timberlake, J.; Bell, R.; England, A.; Isler, R.; Okabayashi, M.; Paul, S.; Takahashi, H.; Tighe, W.; von Goeler, S.; Post-Zwicker, A.P. ); Jones, S. )

    1993-05-01

    The initial boronization of PBX-M was performed using the sequential ablation of two types of solid target probes. Probe-1 in a mushroom shape consisted of a 10.7% boronized 2-D C-C composite containing 3.6 g of boron in a B[sub 4]C binder. Probe-2 in a rectangular shape consisted of an 86% boronized graphite felt composite containing 19.5 g of 40 [mu] boron particles. After boronization with Probe-1, the loop voltage during 1 MW neutral beam heated plasmas decreased 27% and volt-sec consumption decreased 20%. Strong peripheral spectral lines from low-Z elements decreased by factors of about 5. The central oxygen density decreased 15--20%. The total radiated power during neutral beam injection decreased by 43%. Probe-2 boronization exhibited improved operating conditions similar to Probe-1, but for some parameters, a smaller percentage change occurred due to the residual boron from the previous boronization using Probe-1. The ablation rates of both probes were consistent with front face temperatures at or slightly above the boron melting point. These results confirm the effectiveness of the solid target boronization (STB) technique as a real-time impurity control method for replenishing boron depositions without the use of hazardous borane compounds.

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

    NASA Astrophysics Data System (ADS)

    Durmazuçar, Hasan H.; Gündüz, Güngör

    2000-12-01

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

  8. Distribution of 10B after infusion of Na210B12H11SH into a patient with malignant astrocytoma: implications for boron neutron capture therapy.

    PubMed

    Finkel, G C; Poletti, C E; Fairchild, R G; Slatkin, D N; Sweet, W H

    1989-01-01

    If a sufficient concentration of the stable isotope 10B is introduced into a neoplasm, radiation therapy can be effected by short-range heavy charged particles from the disintegration of 10B by slow neutrons. Brain tumors were irradiated postoperatively by Hatanaka and co-workers in Japan using a 1 to 2 hour intraarterial infusion of 10B-enriched Na2B12H11SH (Na210B12H11SH) before exposure of the tumor-bearing area of the brain to slow neutrons from a 100 kilowatt nuclear reactor. The clinical outcome of such boron neutron capture therapy has been favorably impressive in some patients, but its efficacy in brain tumors needs improvement. In our study, a terminally ill patient with malignant astrocytoma was infused intravenously with Na210B12H11SH for 25 hours. The postmortem distribution of 10B in unfixed, frozen, tumor-bearing brain and spinal cord tissues was studied by comparing representative cryostat sections of these specimens with neutron-induced heavy charged particle radiographs of the same sections. Preferential accumulation of 10B was observed in the tumor, with relatively little accumulation of 10B in the parenchyma of the central nervous system.

  9. Nothing Boring About Boron.

    PubMed

    Pizzorno, Lara

    2015-08-01

    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; osteoarthritis (OA

  10. Boron Clusters as a Platform for New Materials: Synthesis of Functionalized o-Carborane (C2 B10 H12 ) Derivatives Incorporating DNA Fragments.

    PubMed

    Janczak, Slawomir; Olejniczak, Agnieszka; Balabańska, Sandra; Chmielewski, Marcin K; Lupu, Marius; Viñas, Clara; Lesnikowski, Zbigniew J

    2015-10-19

    A synthetic strategy for functionalization of the three vertices of o-carborane and the attachment of the obtained triped to the solid support was developed. Further functionalization of the triped with short DNA sequences by automated DNA synthesis was achieved. The proposed methodology is a first example of boron cluster chemistry on a solid support opening new perspectives in boron cluster functionalization.

  11. Boron Nitride Nanotube Mat as a Low- k Dielectric Material with Relative Dielectric Constant Ranging from 1.0 to 1.1

    NASA Astrophysics Data System (ADS)

    Hong, Xinghua; Wang, Daojun; Chung, D. D. L.

    2016-01-01

    This paper reports that a boron nitride nanotube (BNNT) mat containing air and 1.4 vol.% BNNTs is a low- k dielectric material for microelectronic packaging, exhibiting relative dielectric constant of 1.0 to 1.1 (50 Hz to 2 MHz) and elastic modulus of 10 MPa. The mat is prepared by compacting BNNTs at 5.8 kPa. This paper also presents measurements of the dielectric properties of BNNTs (mostly multiwalled). The relative dielectric constant of the BNNT solid in the mat decreases with increasing frequency, with attractively low values ranging from 3.0 to 6.2; the alternating-current (AC) electrical conductivity increases with increasing frequency, with attractively low values ranging from 10-10 S/m to 10-6 S/m and an approximately linear relationship between log conductivity and log frequency. The specific contact capacitance of the interface between BNNTs and the electrical contact decreases with increasing frequency, with attractively high values ranging from 1.6 μF/m2 to 2.3 μF/m2. The AC electrical resistivity of the BNNT-contact interface decreases with increasing frequency, with high values ranging from 0.14 MΩ cm2 to 440 MΩ cm2.

  12. Boron dose determination for BNCT using Fricke and EPR dosimetry

    SciTech Connect

    Wielopolski, L.; Ciesielski, B.

    1995-02-01

    In Boron Neutron Capture Therapy (BNCT) the dominant dose delivered to the tumor is due to {alpha} and {sup 7}Li charged particles resulting from a neutron capture by {sup 10}B and is referred to herein as the boron dose. Boron dose is directly attributable to the following two independent factors, one boron concentration and the neutron capture energy dependent cross section of boron, and two the energy spectrum of the neutrons that interact with boron. The neutron energy distribution at a given point is dictated by the incident neutron energy distribution, the depth in tissue, geometrical factors such as beam size and patient`s dimensions. To account for these factors can be accommodated by using Monte Carlo theoretical simulations. However, in conventional experimental BNCT dosimetry, e.g., using TLDs or ionization chambers, it is only possible to estimate the boron dose. To overcome some of the limitations in the conventional dosimetry, modifications in ferrous sulfate dosimetry (Fricke) and Electron Paramagnetic Resonance (EPR) dosimetry in alanine, enable to measure specifically boron dose in a mixed gamma neutron radiation fields. The boron dose, in either of the dosimeters, is obtained as a difference between measurements with boronated and unboronated dosimeters. Since boron participates directly in the measurements, the boron dosimetry reflects the true contribution, integral of the neutron energy spectrum with boron cross section, of the boron dose to the total dose. Both methods are well established and used extensively in dosimetry, they are presented briefly here.

  13. Crystalline boron nitride aerogels

    DOEpatents

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

    2017-04-04

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

  14. [Minimally invasive cytoselective radiation therapy using boron neutron capture reaction].

    PubMed

    Nakamura, Hiroyuki

    2010-12-01

    The cell-killing effect of boron neutron capture therapy (BNCT) is due to the nuclear reaction of two essentially nontoxic species, boron-10 ((10)B) and thermal neutrons, whose destructive effect is well observed in boron-loaded tissues. High accumulation and selective delivery of boron into tumor tissue are the most important requirements to achieve efficient neutron capture therapy of cancers. This review focuses on liposomal boron delivery system (BDS) as a recent promising approach that meet these requirements for BNCT. BDS involves two strategies: (1) encapsulation of boron in the aqueous core of liposomes and (2) accumulation of boron in the liposomal bilayer. In this review, recent development of liposomal boron delivery system is summarized.

  15. The potential of transferrin-pendant-type polyethyleneglycol liposomes encapsulating decahydrodecaborate-{sup 1}B (GB-10) as {sup 1}B-carriers for boron neutron capture therapy

    SciTech Connect

    Masunaga, Shin-ichiro . E-mail: smasuna@rri.kyoto-u.ac.jp; Kasaoka, Satoshi; Maruyama, Kazuo; Nigg, David; Sakurai, Yoshinori; Nagata, Kenji; Suzuki, Minoru; Kinashi, Yuko; Maruhashi, Akira; Ono, Koji

    2006-12-01

    Purpose: To evaluate GB-10-encapsulating transferrin (TF)-pendant-type polyethyleneglycol (PEG) liposomes as tumor-targeting {sup 1}B-carriers for boron neutron capture therapy. Methods and Materials: A free mercaptoundecahydrododecaborate-{sup 1}B (BSH) or decahydrodecaborate-{sup 1}B (GB-10) solution, bare liposomes, PEG liposomes, or TF-PEG liposomes were injected into SCC VII tumor-bearing mice, and {sup 1}B concentrations in the tumors and normal tissues were measured by {gamma}-ray spectrometry. Meanwhile, tumor-bearing mice were continuously given 5-bromo-2'-deoxyuridine (BrdU) to label all intratumor proliferating cells, then injected with these {sup 1}B-carriers containing BSH or GB-10 in the same manner. Right after thermal neutron irradiation, the response of quiescent (Q) cells was assessed in terms of the micronucleus frequency using immunofluorescence staining for BrdU. The frequency in the total tumor cells was determined from the BrdU nontreated tumors. Results: Transferrin-PEG liposomes showed a prolonged retention in blood circulation, low uptake by reticuloendothelial system, and the most enhanced accumulation of {sup 1}B in solid tumors. In general, the enhancing effects were significantly greater in total cells than Q cells. In both cells, the enhancing effects of GB-10-containing {sup 1}B-carriers were significantly greater than BSH-containing {sup 1}B-carriers, whether loaded in free solution or liposomes. In both cells, whether BSH or GB-10 was employed, the greatest enhancing effect was observed with TF-PEG liposomes followed in decreasing order by PEG liposomes, bare liposomes, and free BSH or GB-10 solution. In Q cells, the decrease was remarkable between PEG and bare liposomes. Conclusions: In terms of biodistribution characteristics and tumor cell-killing effect as a whole, including Q cells, GB-10 TF-PEG liposomes were regarded as promising {sup 1}B-carriers.

  16. Boron Nitride Nanotubes

    NASA Technical Reports Server (NTRS)

    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.

  17. Boron nitride nanotubes

    DOEpatents

    Smith, Michael W [Newport News, VA; Jordan, Kevin [Newport News, VA; Park, Cheol [Yorktown, VA

    2012-06-06

    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.

  18. Boron nitride composites

    DOEpatents

    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.

  19. Boron removal from geothermal waters by electrocoagulation.

    PubMed

    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%.

  20. Effects of employing a 10B-carrier and manipulating intratumour hypoxia on local tumour response and lung metastatic potential in boron neutron capture therapy

    PubMed Central

    Masunaga, S; Sakurai, Y; Tanaka, H; Suzuki, M; Liu, Y; Kondo, N; Maruhashi, A; Kinashi, Y; Ono, K

    2012-01-01

    Objectives To evaluate the effects of employing a 10B-carrier and manipulating intratumour hypoxia on local tumour response and lung metastatic potential in boron neutron capture therapy (BNCT) by measuring the response of intratumour quiescent (Q) cells. Methods B16-BL6 melanoma tumour-bearing C57BL/6 mice were continuously given 5-bromo-2′-deoxyuridine (BrdU) to label all proliferating (P) cells. The tumours received reactor thermal neutron beam irradiation following the administration of a 10B-carrier [L-para-boronophenylalanine-10B (BPA) or sodium mercaptoundecahydrododecaborate-10B (BSH)] in combination with an acute hypoxia-releasing agent (nicotinamide) or mild temperature hyperthermia (MTH). Immediately after the irradiation, cells from some tumours were isolated and incubated with a cytokinesis blocker. The responses of the Q and total (P+Q) cell populations were assessed based on the frequency of micronuclei using immunofluorescence staining for BrdU. In other tumour-bearing mice, macroscopic lung metastases were enumerated 17 days after irradiation. Results BPA-BNCT increased the sensitivity of the total tumour cell population more than BSH-BNCT. However, the sensitivity of Q cells treated with BPA was lower than that of BSH-treated Q cells. With or without a 10B–carrier, MTH enhanced the sensitivity of the Q cell population. Without irradiation, nicotinamide treatment decreased the number of lung metastases. With irradiation, BPA-BNCT, especially in combination with nicotinamide treatment, showed the potential to reduce the number of metastases more than BSH-BNCT. Conclusion BSH-BNCT in combination with MTH improves local tumour control, while BPA-BNCT in combination with nicotinamide may reduce the number of lung metastases. PMID:22391496

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

    PubMed

    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.

  2. Beryllium-Boron Systematics of Refractory Inclusions in CR2 and CV3 Chondrites: Evidence for 10Be Heterogeneity

    NASA Astrophysics Data System (ADS)

    Dunham, E.; Wadhwa, M.; Simon, S.; Grossman, L.

    2016-08-01

    Be-B systematics of Allende (CV3), Axtell (CV3), and NWA 5028 (CR2) CAIs suggests that 10Be was distributed heterogeneously in the early solar system which implies that 10Be was produced in the solar nebula by irradiation of nebular gas or dust.

  3. Boron depletion: indirect measurement of the 10B(p,α)7Be S(E)-factor

    NASA Astrophysics Data System (ADS)

    Lamia, L.; Romano, S.; Carlin, N.; Cherubini, S.; Crucillà, V.; de Moura, M. M.; Del Santo, M. G.; Munhoz, M. G.; Gulino, M.; Liguori Neto, R.; La Cognata, M.; Mudò, F.; Pizzone, R. G.; Puglia, S. M. R.; Sergi, M. L.; Souza, F. A.; Spitaleri, C.; Suaide, A. A. P.; Szanto, E.; Szanto de Toledo, A.; Tudisco, S.; Tumino, A.

    2007-05-01

    The 10B(p,α)7Be reaction is the main responsible for 10B destruction in stellar interior. In such environments this p-capture process occurs at a Gamow energy of ˜10 keV, and takes places mainly through a resonant state (E=8.701 MeV) of the compound 11C nucleus. Thus, a resonance right in the region of the Gamow peak is expected to significantly influence the behaviour of the astrophysical S(E)-factor. The 10B(p,α)7Be reaction has been investigated by means of the Trojan Horse Method (THM) applied to the 2H(10B,α7Be)n three-body process. The experiment was performed at E=27 MeV at the Instituto de Fisica Nuclear de São Paulo. Preliminary results concerning the extraction of the bare-nucleus S(E)-factor will be presented.

  4. Methods of forming boron nitride

    DOEpatents

    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.

  5. Cosmic abundance of boron.

    NASA Technical Reports Server (NTRS)

    Cameron, A. G. W.; Colgate, S. A.; Grossman, L.

    1973-01-01

    All abundances are expressed relative to a million atoms of Si. An average abundance of boron in ordinary chondrites is 6.2. The boron abundance in meteorites is highly variable. It has been found that the abundances in carbonaceous chondrites are very much higher than those in ordinary chondrites. The condensation of boron and beryllium from a cooling, low-pressure gas of solar composition is discussed together with the occurrence of boron in the interstellar medium, questions of element abundances in the sun, problems of boron production by cosmic rays, and boron production from supernovae.

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

    SciTech Connect

    Agarwal, A.; Eaglesham, D.J.; Gossmann, H.J.; Pelaz, L.; Herner, S.B.; Jacobson, D.C.; Haynes, T.E.; Erokhin, Y.E.

    1998-05-03

    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{sup +}, the threshold implantation dose which leads to BED lies between 3 {times} 10{sup 14} and of 1 {times} 10{sup 15}/cm{sup {minus}2}. Formation of the shallowest possible junctions by 0.5 keV B{sup +} requires that the implant dose be kept lower than this threshold.

  7. Primitive boron isotope composition of the mantle.

    PubMed

    Chaussidon, M; Marty, B

    1995-07-21

    Boron isotope ratios are homogeneous in volcanic glasses of oceanic island basalts [-9.9 +/- 1.3 per mil, relative to standard NBS 951 (defined by the National Bureau of Standards)], whereas mid-oceanic ridge basalts (MORBs) and back-arc basin basalts (BABBs) show generally higher and more variable ratios. Melts that have assimilated even small amounts of altered basaltic crust show significant variations in the boron isotope ratios. Assimilation may thus account for the higher boron ratios of MORBs and BABBs. A budget of boron between mantle and crust implies that the primitive mantle had a boron isotope ratio of -10 +/- 2 per mil and that this ratio was not fractionated significantly during the differentiation of the mantle.

  8. Boron implanted strontium titanate

    NASA Astrophysics Data System (ADS)

    Cooper, C. J. M.

    Single crystals of strontium titanate implanted with boron were found to have highly conductive surface layers. The effects of varying dose from 10 to the 16th power to 10 to the 17th power ions/sq cm, implantation voltage from 50 to 175 keV and annealing conditions on the room temperature surface resistance and Hall mobility are presented. Variation of the implantation voltage did not have a major effect on the sheet resistances obtained by boron implantation of strontium titanate, while dose and annealing conditions have major effects. Doses of 5 x 10 to the 16th power ions/sq cm required annealing on the order of one hour at 500 K for maximum reduction of the room temperature resistance in the implanted layer. Samples implanted with a dose of 1 x 10 to the 17th power ions/sq cm required slightly higher temperatures (approximately 575 K) to obtain a minimum resistance at room temperature. Long term (several weeks) room temperature annealing was found to occur in high dose samples. After one to two months at room temperature followed by an anneal to 575 K, the surface resistances were found to be lower than those produced by the annealing of a freshly implanted sample to 575 K.

  9. Boron doping a semiconductor particle

    DOEpatents

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

    1998-06-09

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

  11. Boron Neutron Capture Therapy - A Literature Review

    PubMed Central

    Nedunchezhian, Kavitaa; Thiruppathy, Manigandan; Thirugnanamurthy, Sarumathi

    2016-01-01

    Boron Neutron Capture Therapy (BNCT) is a radiation science which is emerging as a hopeful tool in treating cancer, by selectively concentrating boron compounds in tumour cells and then subjecting the tumour cells to epithermal neutron beam radiation. BNCT bestows upon the nuclear reaction that occurs when Boron-10, a stable isotope, is irradiated with low-energy thermal neutrons to yield α particles (Helium-4) and recoiling lithium-7 nuclei. A large number of 10 Boron (10B) atoms have to be localized on or within neoplastic cells for BNCT to be effective, and an adequate number of thermal neutrons have to be absorbed by the 10B atoms to maintain a lethal 10B (n, α) lithium-7 reaction. The most exclusive property of BNCT is that it can deposit an immense dose gradient between the tumour cells and normal cells. BNCT integrates the fundamental focusing perception of chemotherapy and the gross anatomical localization proposition of traditional radiotherapy. PMID:28209015

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

    NASA Astrophysics Data System (ADS)

    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.

  13. FBPA PET in boron neutron capture therapy for cancer: prediction of (10)B concentration in the tumor and normal tissue in a rat xenograft model.

    PubMed

    Hanaoka, Kohei; Watabe, Tadashi; Naka, Sadahiro; Kanai, Yasukazu; Ikeda, Hayato; Horitsugi, Genki; Kato, Hiroki; Isohashi, Kayako; Shimosegawa, Eku; Hatazawa, Jun

    2014-12-01

    Boron neutron capture therapy (BNCT) is a molecular radiation treatment based on the (10)B (n, α) (7)Li nuclear reaction in cancer cells, in which delivery of (10)B by 4-borono-phenylalanine conjugated with fructose (BPA-fr) to the cancer cells is of critical importance. The PET tracer 4-borono-2-(18) F-fluoro-phenylalanine (FBPA) has been used to predict the accumulation of BPA-fr before BNCT. However, because of the difference in chemical structure between BPA-fr and FBPA and the difference in the dose administered between BPA-fr (therapeutic dose) and FBPA (tracer dose), the predictive value of FBPA PET for BPA-fr accumulation in the tumor and normal tissues is not yet clearly proven. We conducted this study to validate FBPA PET as a useful test to predict the accumulation of BPA-fr in the tumor and normal tissues before BNCT. RGC-6 rat glioma cells (1.9 × 10(7)) were implanted subcutaneously in seven male F344 rats. On day 20 after the tumor implantation, dynamic PET scan was performed on four rats after injection of FBPA for 1 h. Whole-body PET/CT was performed 1 h after intravenous injection of the FBPA solution (30.5 ± 0.7 MBq, 1.69 ± 1.21 mg/kg). PET accumulation of FBPA in the tumor tissue and various normal tissues was estimated as a percentage of the injected dose per gram (%ID/g). One hour after the PET/CT scan, BPA-fructose (167.32 ± 18.65 mg/kg) was injected intravenously, and the rats were dissected 1 h after the BPA-fr injection. The absolute concentration of (10)B in the autopsied tissues and blood was measured by inductively coupled plasma optical emission spectrometry (ICP-OES). The highest absolute concentration of (10)B determined by ICP-OES was found in the kidney (4.34 ± 0.84 %ID/g), followed by the pancreas (2.73 ± 0.63 %ID/g), and the tumor (1.44 ± 0.44 %ID/g). A significant positive correlation was found between the accumulation levels of BPA-fr and FBPA (r = 0.91, p < 0.05). FBPA PET can

  14. Synthesis and in vivo murine evaluation of Na4[1-(1′-B10H9)-6-SHB10H8] as a potential agent for boron neutron capture therapy

    PubMed Central

    Feakes, Debra A.; Waller, R. Corey; Hathaway, Deborah K.; Morton, Veronica S.

    1999-01-01

    Reaction of the normal isomer of [B20H18]2− and the protected thiol anion, [SC(O)OC(CH3)3]−, produces an unexpected isomer of [B20H17SC(O)OC(CH3)3]4− directly and in good yield. The isomer produced under mild conditions is characterized by an apical–apical boron atom intercage connection as well as the location of the thiol substituent on an equatorial belt adjacent to the terminal boron apex. Although the formation of this isomer from nucleophilic attack of the normal isomer of [B20H18]2− has not been reported previously, the isomeric assignment has been unambiguously confirmed by one-dimensional and two-dimensional 11B NMR spectroscopy. Deprotection of the thiol substituent under acidic conditions produces a protonated intermediate, [B20H18SH]3−, which can be deprotonated with a suitable base to yield the desired product, [B20H17SH]4−. The sodium salt of the resulting [B20H17SH]4− ion has been encapsulated in small, unilamellar liposomes, which are capable of delivering their contents selectively to tumors in vivo, and investigated as a potential agent for boron neutron capture therapy. The biodistribution of boron was determined after intravenous injection of the liposomal suspension into BALB/c mice bearing EMT6 mammary adenocarcinoma. At low injected doses, the tumor boron concentration increased throughout the time-course experiment, resulting in a maximum observed boron concentration of 46.7 μg of B per g of tumor at 48 h and a tumor to blood boron ratio of 7.7. The boron concentration obtained in the tumor corresponds to 22.2% injected dose (i.d.) per g of tissue, a value analogous to the most promising polyhedral borane anions investigated for liposomal delivery and subsequent application in boron neutron capture therapy. PMID:10339600

  15. Boron nitride converted carbon fiber

    SciTech Connect

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

    2016-04-05

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

  16. Boron isotopic compositions of some boron minerals

    SciTech Connect

    Oi, Takao; Musashi, Masaaki; Ossaka, Tomoko; Kakihana, Hidetake ); Nomura, Masao; Okamoto, Makoto )

    1989-12-01

    Boron minerals that have different structural formulae but are supposed to have the same geologic origin have been collected and analyzed for the {sup 11}B/{sup 10}B isotopic ratio. It has been reconfirmed that minerals of marine origin have higher {sup 11}B/{sup 10}B ratios than those of nonmarine origin. It has been found that the sequence of decreasing {sup 11}B/{sup 10}B values among the minerals with the same geologic origin is; borax, tincal, kernite (Na borates) > ulexite (Na/Ca borate) > colemanite, iyoite, meyerhofferite (Ca borates). This sequence is explainable on the basis of the difference in crystal structure among the minerals. That is, minerals with high BO{sub 3}/BO{sub 4} ratios, (the ratio of the number of the BO{sub 3} triangle units to the number of the BO{sub 4} tetrahedron units in the structural formula of a mineral) have higher {sup 11}B/{sup 10}B ratios.

  17. Prediction of Boron-Boron Triple-Bond Polymers Stabilized by Janus-Type Bis(N-heterocyclic) Carbenes.

    PubMed

    Fantuzzi, Felipe; Chaer Nascimento, Marco A

    2015-05-18

    A class of polymeric compounds containing boron-boron triple bonds stabilized by N-heterocyclic biscarbenes is proposed. Since a triply bonded B2 is related to its third excited state, the predicted macromolecule would be composed by several units of an electronically excited first-row homonuclear dimer. Moreover, it is shown that the replacement of biscarbene with N2 or CO as spacers could change the bonding profile of the boron-boron units to a cumulene-like structure. Based on these results, different types of diboryne polymers are proposed, which could lead to an unprecedented set of boron materials with distinct physical properties. The novel diboryne macromolecules could be synthesized by the reaction of Janus-type biscarbenes with tetrabromodiborane, B2 Br4 , and sodium naphthalenide, [Na(C10 H8 )], similarly to Braunschweig's work on the room temperature stable boron-boron triple bond compounds (Science, 2012, 336, 1420).

  18. Chemical Behaviors of Energetic Deuterium Implanted into Boron Coatings

    SciTech Connect

    Kodama, H.; Morimoto, Y.; Sasaki, M.; Oyaidu, M.; Oya, Y.; Sagara, A.; Noda, N.; Okuno, K.

    2003-09-15

    To study chemical behaviors of energetic deuterium implanted into boron coating deposited by boronization in fusion devices, two types of boron coating film deposited on silicon and IG-430U were prepared by Plasma Chemical Vapor Deposition (PCVD) technique. Boron polycrystal was used as the reference sample. The chemical behavior of deuterium was investigated by XPS (X-ray photoelectron spectroscopy) and TDS (Thermal adsorption spectroscopy).The 1.0 keV D{sub 2}{sup +} ions were implanted into the samples and the deuterium desorption behavior was studied by TDS. The TDS spectra showed that there were two deuterium release peaks at around 550 and 750 K, which were attributed to the release from deuterium trapped by boron and carbon, respectively. It was also found that most of implanted deuterium was trapped in carbon trapping site compared with boron one.In XPS measurements, the chemical shift of B-1s towards positive side was observed in the film on IG-430U after D{sub 2}{sup +} ion implantation. However, no chemical shifts were found in the film on silicon and boron polycrystal. In highly concentrated boron materials, even if deuterium was implanted into the boron materials, the amount of B-D bond was too low to be measured by XPS. This suggests that deuterium implanted into highly pure boron materials wasn't almost trapped, so that the retention of deuterium in the boron materials would be reduced, compared that in carbon materials.

  19. The effect of boron oxide on the crystallization behavior of MgAl2O4 spinel phase during the cooling of the CaO-SiO2-10 mass.% MgO-30 mass.%Al2O3 systems

    NASA Astrophysics Data System (ADS)

    Park, Joo Hyun

    2010-12-01

    The microstructural characteristics of the CaO-SiO2-B2O3-10 mass.% MgO-30 mass.% Al2O3 systems solidified during slow cooling from 1600 °C were investigated using SEM-EDS and a thermochemical computation package. The effect of boron oxide on the crystallization behavior of the spinel in the aluminosilicate system was observed because boron oxide is believed to become a potential flux to reduce the melting point of the liquid oxides. The primary crystalline phase was spinel, mainly MgAl2O4, irrespective of the boron content. The liquidus temperature T L continuously decreased as the boron oxide content increased, indicating that the boron oxide decreased the activity of the MgAl2O4 spinel phase in liquid melts at high temperatures. The size of the spinel crystals increased as the temperature range for the solid + liquid coexisting region, viz. the mushy zone, increased. In the present systems, because the T L continuously decreased with the increase in the boron oxide content, the viscosity of the liquid oxide may have affected the crystallization behavior of the spinel during cooling. Based on these results, an injection of a small amount of B2O3 flux into molten steel containing liquid aluminosilicate inclusions is not recommended because large spinel crystals can originate from the changes in the thermophysical properties of the liquid inclusions due to the incorporation of boron oxide into the aluminosilicate networks.

  20. In vitro and in vivo studies of boron neutron capture therapy: boron uptake/washout and cell death.

    PubMed

    Ferrari, C; Bakeine, J; Ballarini, F; Boninella, A; Bortolussi, S; Bruschi, P; Cansolino, L; Clerici, A M; Coppola, A; Di Liberto, R; Dionigi, P; Protti, N; Stella, S; Zonta, A; Zonta, C; Altieri, S

    2011-04-01

    Boron neutron capture therapy (BNCT) is a binary radiotherapy based on thermal-neutron irradiation of cells enriched with (10)B, which produces α particles and (7)Li ions of short range and high biological effectiveness. The selective uptake of boron by tumor cells is a crucial issue for BNCT, and studies of boron uptake and washout associated with cell survival studies can be of great help in developing clinical applications. In this work, boron uptake and washout were characterized both in vitro for the DHDK12TRb (DHD) rat colon carcinoma cell line and in vivo using rats bearing liver metastases from DHD cells. Despite a remarkable uptake, a large boron release was observed after removal of the boron-enriched medium from in vitro cell cultures. However, analysis of boron washout after rat liver perfusion in vivo did not show a significant boron release, suggesting that organ perfusion does not limit the therapeutic effectiveness of the treatment. The survival of boron-loaded cells exposed to thermal neutrons was also assessed; the results indicated that the removal of extracellular boron does not limit treatment effectiveness if adequate amounts of boron are delivered and if the cells are kept at low temperature. Cell survival was also investigated theoretically using a mechanistic model/Monte Carlo code originally developed for radiation-induced chromosome aberrations and extended here to cell death; good agreement between simulation outcomes and experimental data was obtained. © 2011 by Radiation Research Society

  1. Properties of boron/boron-nitride multilayers

    SciTech Connect

    Jankowski, A.F.; Wall, M.A.; Hayes, J.P.; Alexander, K.B.

    1996-06-01

    Boron-Nitride films are of interest for their high hardness and wear resistance. Large intrinsic stresses and poor adhesion which often accompany high hardness materials can be moderated through the use of a layered structure. Alternate layers of boron (B) and boron-nitride (BN) are formed by modulating the composition of the sputter gas during deposition from a pure B target. The thin films are characterized with TEM to evaluate the microstructure and with nanoindentation to determine hardness. Layer pair spacing and continuity effects on hardness are evaluated for the B/BN films.

  2. [Development of high boron content liposomes and their promising antitumor effect for neutron capture therapy].

    PubMed

    Nakamura, Hiroyuki

    2013-01-01

      High accumulation and selective delivery of boron into tumor tissue are the most important requirements to achieve the efficient cell-killing effect of boron neutron capture therapy (BNCT) that relies on the nuclear reaction of two essentially nontoxic species, boron-10 ((10)B) and thermal neutrons in boron-loaded tissues. Recent development of boron cluster lipids and their liposomal boron delivery system (BDS) are summarized in this article. Boron compounds that have no affinity to tumor can potentially be delivered to tumor tissues by liposomes, therefore, liposomal BDS would be one of the most attractive approaches for efficient BNCT of various cancers. There are two approaches for BDS: encapsulation of boron compounds into liposomes and incorporation of boron-conjugated lipids into the liposomal bilayer. The combination of both approaches has a potential for reduction of the total dose of liposomes without reducing the efficacy of BNCT.

  3. Combustion synthesis of novel boron carbide

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  4. Feasibility of a boron loaded scintillation detector for dose measurements related to boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Kim, Don-Soo; Egan, James J.; Kegel, Gunter H. R.; Desimone, David

    2002-04-01

    The feasibility of the use of a boron loaded scintillation detector in a head phantom for boron neutron capture therapy dose estimates was evaluated. Several monoenergetic neutron groups were produced via the ^7Li(p,n)^7Be reaction in a metallic lithium target using the Van de Graaff accelerator at University of Massachusetts Lowell. The pulse-height spectra were taken from a natural boron loaded (10205-, 304-, 407-, 507-, 570-, 702-, and 780-keV incident neutrons. The results shows that a boron loaded scintillator could be used to distinguish the doses from different radiation sources in boron neutron capture therapy. This detector may be used in the estimation of doses due to fast neutrons, alpha particles and recoil lithium from ^10B(n,α)^7Li, and photons at the same time during neutron irradiation procedures.

  5. Influence of Neutron Sources and 10B Concentration on Boron Neutron Capture Therapy for Shallow and Deeper Non-small Cell Lung Cancer.

    PubMed

    Yu, Haiyan; Tang, Xiaobin; Shu, Diyun; Liu, Yuanhao; Geng, Changran; Gong, Chunhui; Hang, Shuang; Chen, Da

    2017-03-01

    Boron Neutron Capture Therapy (BNCT) is a radiotherapy that combines biological targeting and high Linear Energy Transfer (LET). It is considered a potential therapeutic approach for non-small cell lung cancer (NSCLC). It could avoid the inaccurate treatment caused by the lung motion during radiotherapy, because the dose deposition mainly depends on the boron localization and neutron source. Thus, B concentration and neutron sources are both principal factors of BNCT, and they play significant roles in the curative effect of BNCT for different cases. The purpose was to explore the feasibility of BNCT treatment for NSCLC with either of two neutron sources (the epithermal reactor at the Massachusetts Institute of Technology named "MIT source" and the accelerator neutron source designed in Argentina named "MEC source") and various boron concentrations. Shallow and deeper lung tumors were defined in the Chinese hybrid radiation phantom, and the Monte Carlo method was used to calculate the dose to tumors and healthy organs. The MEC source was more appropriate to treat the shallow tumor (depth of 6 cm) with a shorter treatment time. However, the MIT source was more suitable for deep lung tumor (depth of 9 cm) treatment, as the MEC source is more likely to exceed the skin dose limit. Thus, a neutron source consisting of more fast neutrons is not necessarily suitable for deep treatment of lung tumors. Theoretical distribution of B in tumors and organs at risk (especially skin) was obtained to meet the treatable requirement of BNCT, which may provide the references to identify the feasibility of BNCT for the treatment of lung cancer using these two neutron sources in future clinical applications.

  6. Fluorine-enhanced boron diffusion in germanium-preamorphized silicon

    SciTech Connect

    Jacques, J.M.; Jones, K.S.; Robertson, L.S.; Li-Fatou, A.; Hazelton, C.M.; Napolitani, E.; Rubin, L.M.

    2005-10-01

    Silicon wafers were preamorphized with 60 keV Ge{sup +} or 70 keV Si{sup +} at a dose of 1x10{sup 15} atoms/cm{sup 2}. F{sup +} was then implanted into some samples at 6 keV at doses ranging from 1x10{sup 14} to 5x10{sup 15} atoms/cm{sup 2}, followed by {sup 11}B{sup +} implants at 500 eV, 1x10{sup 15} atoms/cm{sup 2}. Secondary-ion-mass spectrometry confirmed that fluorine enhances boron motion in germanium-preamorphized materials in the absence of annealing. The magnitude of boron diffusion scales with increasing fluorine dose. Boron motion in as-implanted samples occurs when fluorine is concentrated above 1x10{sup 20} atoms/cm{sup 3}. Boron atoms are mobile in as-implanted, amorphous material at concentrations up to 1x10{sup 19} atoms/cm{sup 3}. Fluorine directly influences boron motion only prior to activation annealing. During the solid-phase epitaxial regrowth process, fluorine does not directly influence boron motion, it simply alters the recrystallization rate of the silicon substrate. Boron atoms can diffuse in germanium-amorphized silicon during recrystallization at elevated temperatures without the assistance of additional dopants. Mobile boron concentrations up to 1x10{sup 20} atoms/cm{sup 3} are observed during annealing of germanium-preamorphized wafers.

  7. Environmental boron contamination in waters of Hisarcik area in the Kutahya Province of Turkey.

    PubMed

    Cöl, Meltem; Cöl, Cavit

    2003-10-01

    Our aim was to determine boron levels in waters of rich boron mine areas in Turkey. There is a naturally occurring high level of boron in the ground waters of some parts of Turkey. Our study area is Hisarcik village in the Kutahya Province of Turkey which has a large number of boron mines. Boron occurs in combined form, usually borax (Na2B4O7 x 10H2O) and colemanite (Ca2B6O11 x 5H2O). Water samples were collected from many springs in order to determine boron concentrations and the amount of boron that is exposed to 88 samples from the drinking water (tap water), 37 from ground water and 257 from stream or pond water (surface water). Urine samples taken from 42 residents in this area were analyzed for boron and compared with its levels in drinking waters. The inductively coupled plasma/mass spectrometry (ICP/MS) method was used for the analysis of boron concentrations. Water boron contents at differing locations of this area ranged from 2.05 to 29.00 mg B/l. Mean value of boron was 10.20+/-4.08 mg B/l. Total urinary boron excretion was ranged from 0.04 to 50.70 mg B/l and mean value was 8.30+/-10.91 mg B/l. Current information on sources, occurrence, pollution potential and toxicity of environmental boron is discussed.

  8. Model studies directed toward the application of boron neutron capture therapy to rheumatoid arthritis: Boron delivery by liposomes in rat collagen-induced arthritis

    PubMed Central

    Watson-Clark, Rachel A.; Banquerigo, Mona Lisa; Shelly, Kenneth; Hawthorne, M. Frederick; Brahn, Ernest

    1998-01-01

    The application of boron neutron capture therapy to rheumatoid arthritis requires the selective delivery of the boron-10 isotope to the synovitic tissue. The use of liposomes as a boron delivery method has been explored through the measurement of the time course biodistribution of boron in rats with collagen-induced arthritis (CIA). Small unilamellar vesicles were composed of a 1:1 mixture of distearoylphosphatidylcholine and cholesterol, incorporated K[nido-7-CH3(CH2)15-7,8-C2B9H11] as an addend in the lipid bilayer and encapsulated Na3[a2-B20H17NH2CH2CH2NH2] in the aqueous core. The tissue concentration of boron delivered by liposomes was determined by inductively coupled plasma–atomic emission spectroscopy after intravenous injection of liposome suspensions into Louvain rats with CIA. With the low injected doses of boron used [13–18 mg of boron per kg (body weight)], the peak boron concentration observed in arthritic synovium was 29 μg of boron per g of tissue. The highest synovium/blood boron ratio observed was 3.0, when the synovial boron concentration was 22 μg of boron per g of tissue. In an attempt to increase the synovium/blood boron ratio by lowering the blood boron concentration, a liposomal formulation characterized by a shorter blood clearance time was examined. Thus, the biodistribution of liposomes with additional K[nido-7-CH3(CH2)15-7,8-C2B9H11] incorporated in the vesicle membrane not only demonstrated more rapid blood clearance and slightly higher synovium/blood boron ratios but also exhibited reduced boron uptake in synovial tissue. These studies with boron neutron capture therapy for CIA suggest that this form of therapy may be feasible in the treatment of rheumatoid arthritis. PMID:9482920

  9. Nothing Boring About Boron

    PubMed Central

    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

  10. Longitudinal splitting of boron nitride nanotubes for the facile synthesis of high quality boron nitride nanoribbons.

    PubMed

    Erickson, Kris J; Gibb, Ashley L; Sinitskii, Alexander; Rousseas, Michael; Alem, Nasim; Tour, James M; Zettl, Alex K

    2011-08-10

    Boron nitride nanoribbons (BNNRs), the boron nitride structural equivalent of graphene nanoribbons (GNRs), are predicted to possess unique electronic and magnetic properties. We report the synthesis of BNNRs through the potassium-intercalation-induced longitudinal splitting of boron nitride nanotubes (BNNTs). This facile, scalable synthesis results in narrow (down to 20 nm), few sheet (typically 2-10), high crystallinity BNNRs with very uniform widths. The BNNRs are at least 1 μm in length with minimal defects within the ribbon plane and along the ribbon edges.

  11. The structure of boron in boron fibres

    NASA Technical Reports Server (NTRS)

    Bhardwaj, J.; Krawitz, A. D.

    1983-01-01

    The structure of noncrystalline, chemically vapour-deposited boron fibres was investigated by computer modelling the experimentally obtained X-ray diffraction patterns. The diffraction patterns from the models were computed using the Debye scattering equation. The modelling was done utilizing the minimum nearest-neighbour distance, the density of the model, and the broadening and relative intensity of the various peaks as boundary conditions. The results suggest that the fibres consist of a continuous network of randomly oriented regions of local atomic order, about 2 nm in diameter, containing boron atoms arranged in icosahedra. Approximately half of these regions have a tetragonal structure and the remaining half a distorted rhombohedral structure. The model also indicates the presence of many partial icosahedra and loose atoms not associated with any icosahedra. The partial icosahedra and loose atoms indicated in the present model are in agreement with the relaxing sub-units which have been suggested to explain the anelastic behavior of fibre boron and the loosely bound boron atoms which have been postulated to explain the strengthening mechanism in boron fibres during thermal treatment.

  12. Magnetron sputtered boron films

    DOEpatents

    Makowiecki, D.M.; Jankowski, A.F.

    1998-06-16

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence. 8 figs.

  13. Magnetron sputtered boron films

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    1998-01-01

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence.

  14. Boronization on NSTX using Deuterated Trimethylboron

    SciTech Connect

    W.R. Blanchard; R.C. Gernhardt; H.W. Kugel; P.H. LaMarche

    2002-01-28

    Boronization on the National Spherical Torus Experiment (NSTX) has proved to be quite beneficial with increases in confinement and density, and decreases in impurities observed in the plasma. The boron has been applied to the interior surfaces of NSTX, about every 2 to 3 weeks of plasma operation, by producing a glow discharge in the vacuum vessel using deuterated trimethylboron (TMB) in a 10% mixture with helium. Special NSTX requirements restricted the selection of the candidate boronization method to the use of deuterated boron compounds. Deuterated TMB met these requirements, but is a hazardous gas and special care in the execution of the boronization process is required. This paper describes the existing GDC, Gas Injection, and Torus Vacuum Pumping System hardware used for this process, the glow discharge process, and the automated control system that allows for remote operation to maximize both the safety and efficacy of applying the boron coating. The administrative requirements and the detailed procedure for the setup, operation and shutdown of the process are also described.

  15. Microwave sintering of boron carbide

    DOEpatents

    Blake, R.D.; Katz, J.D.; Petrovic, J.J.; Sheinberg, H.

    1988-06-10

    A method for forming boron carbide into a particular shape and densifying the green boron carbide shape. Boron carbide in powder form is pressed into a green shape and then sintered, using a microwave oven, to obtain a dense boron carbide body. Densities of greater than 95% of theoretical density have been obtained. 1 tab.

  16. Reverse annealing and low-temperature diffusion of boron in boron-implanted silicon

    SciTech Connect

    Huang, J.; Fan, D.; Jaccodine, R.J.

    1988-06-01

    Low-temperature annealing (525 /sup 0/C--800 /sup 0/C) of 50-keV, 1 x 10/sup 15/-cm/sup -2/, boron-implanted silicon was studied with the emphasis on the mechanisms responsible for the reverse annealing as well as the enhanced diffusion of the implanted boron. The electrical properties of boron-implanted silicon were analyzed with Hall measurement. Boron depth profiles were also measured using secondary-ion mass spectrometry. These results were then correlated with cross-section transmission electron microscopy studies and deep-level transient spectroscopy studies. It is shown that reverse annealing is possibly due to boron-silicon interstitial complexes, rather than the formation of the commonly observed rodlike defects or precipitates. On the other hand, the enhanced tail diffusion of boron is found to be most likely associated with self-interstitials. Consequently, vacancy trapping of the silicon interstitial component may account for both the charge carrier recovery and the ending of the enhanced tail diffusion of implanted boron.

  17. The geochemical cycle of boron: Constraints from boron isotope partitioning experiments between mica and fluid

    NASA Astrophysics Data System (ADS)

    Wunder, Bernd; Meixner, Anette; Romer, Rolf L.; Wirth, Richard; Heinrich, Wilhelm

    2005-10-01

    The fractionation of boron isotopes between synthetic boromuscovite and fluid was experimentally determined at 3.0 GPa/500 °C and 3.0 GPa/700 °C. For near-neutral fluids Δ 11B (mica-fluid) = δ 11B (mica) - δ 11B (fluid) is - 10.9 ± 1.3‰ at 500 °C, and - 6.5 ± 0.4‰ at 700 °C. This supports earlier assumptions that the main fractionation effect is due to the change from trigonal coordination of boron in neutral fluids to tetrahedrally coordinated boron in micas, clays and melts. The T-dependence of this effect is approximated by the equation Δ 11B (mica,clay,melt-neutral fluid) = - 10.69 · (1000/ T [K]) + 3.88; R2 = 0.992, valid from 25 °C for fluid-clay up to about 1000 °C for fluid-silicate melt. Experiments at 0.4 GPa that used strongly basic fluids produced significantly lower fractionations with Δ 11B (mica-fluid) of - 7.4 ± 1.0‰ at 400 °C, and - 4.8 ± 1.0‰ at 500 °C, showing the reduced fractionation effect when large amounts of boron in basic fluids are tetrahedrally coordinated. Field studies have shown that boron concentrations and 11B/ 10B-ratios in volcanic arcs systematically decrease across the arc with increasing distance from the trench, thus reflecting the thermal structure of the subducting slab. Our experiments show that the boron isotopic signature in volcanic arcs probably results from continuous dehydration of micas along a distinct P- T range. Continuous slab dehydration and boron transport via fluid into the mantle wedge is responsible for the boron isotopic signature in volcanic arcs.

  18. Liposomal boron delivery for neutron capture therapy.

    PubMed

    Nakamura, Hiroyuki

    2009-01-01

    Tumor cell destruction in boron neutron capture therapy (BNCT) is due to the nuclear reaction between (10)B and thermal neutrons. The thermal neutrons have an energy of 0.025 eV, clearly below the threshold energy required to ionize tissue components. However, neutron capture by (10)B produces lithium ion and helium (alpha-particles), which are high linear energy transfer (LET) particles, and dissipate their kinetic energy before traveling one cell diameter (5-9 microm) in biological tissues, ensuring their potential for precise cell killing. BNCT has been applied clinically for the treatment of malignant brain tumors, malignant melanoma, head and neck cancer, and hepatoma using two boron compounds: sodium borocaptate (Na(2)(10)B(12)H(11)SH; Na(2)(10)BSH) and l-p-boronophenylalanine (l-(10)BPA). These low molecular weight compounds are cleared easily from the cancer cells and blood. Therefore, high accumulation and selective delivery of boron compounds into tumor tissues are most important to achieve effective BNCT and to avoid damage of adjacent healthy cells. Much attention has been focused on the liposomal drug delivery system (DDS) as an attractive, intelligent technology of targeting and controlled release of (10)B compounds. Two approaches have been investigated for incorporation of (10)B into liposomes: (1) encapsulation of (10)B compounds into liposomes and (2) incorporation of (10)B-conjugated lipids into the liposomal bilayer. Our laboratory has developed boron ion cluster lipids for application of the latter approach. In this chapter, our boron lipid liposome approaches as well as recent developments of the liposomal boron delivery system are summarized.

  19. Low temperature boron doped diamond

    NASA Astrophysics Data System (ADS)

    Zeng, Hongjun; Arumugam, Prabhu U.; Siddiqui, Shabnam; Carlisle, John A.

    2013-06-01

    Low temperature boron doped diamond (LT-BDD) film deposited under 600 °C (460 °C minimum) has been reported. Study reveals that the deposition temperature and boron dopant cause nanocrystalline diamond (NCD) instead of ultrananocrystalline diamond (UNCD®). Unlike conventional NCD, LT-BDD has faster renucleation rate, which ensures a low surface roughness (approximately 10 nm at 0.6 μm thickness). The overall characteristics of LT-BDD are mixed with the characteristics of conventional NCD and UNCD. Raman spectrum and electrochemical characterization prove that the quality of LT-BDD is similar to those grown under 650-900 °C. LT-BDD enables diamond applications on microelectromechanical systems, bio- and optical technologies.

  20. Boron and the kidney.

    PubMed

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

    2005-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  2. Model studies directed toward the boron neutron-capture therapy of cancer: boron delivery to murine tumors with liposomes.

    PubMed Central

    Shelly, K; Feakes, D A; Hawthorne, M F; Schmidt, P G; Krisch, T A; Bauer, W F

    1992-01-01

    The successful treatment of cancer by boron neutron-capture therapy (BNCT) requires the selective concentration of boron-10 within malignant tumors. The potential of liposomes to deliver boron-rich compounds to tumors has been assessed by the examination of the biodistribution of boron delivered by liposomes in tumor-bearing mice. Small unilamellar vesicles with mean diameters of 70 nm or less, composed of a pure synthetic phospholipid (distearoyl phosphatidylcholine) and cholesterol, have been found to stably encapsulate high concentrations of water-soluble ionic boron compounds. The hydrolytically stable borane anions B10H10(2-), B12H11SH2-, B20H17OH4-, B20H19(3-), and the normal form and photoisomer of B20H18(2-) were encapsulated in liposomes as their soluble sodium salts. The tissue concentration of boron in tumor-bearing mice was measured at several time points over 48 h after i.v. injection of emulsions of liposomes containing the borane anions. Although the boron compounds used do not exhibit an affinity for tumors and are normally rapidly cleared from the body, liposomes were observed to selectively deliver the borane anions to tumors. The highest tumor concentrations achieved reached the therapeutic range (greater than 15 micrograms of boron per g of tumor) while maintaining high tumor-boron/blood-boron ratios (greater than 3). The most favorable results were obtained with the two isomers of B20H18(2-). These boron compounds have the capability to react with intracellular components after they have been deposited within tumor cells by the liposome, thereby preventing the borane ion from being released into blood. PMID:1409600

  3. Experimental Study on Application of Boron Mud Secondary Resource to Oxidized Pellets Production

    NASA Astrophysics Data System (ADS)

    Fu, Xiao-Jiao; Chu, Man-Sheng; Zhao, Jia-Qi; Chen, Shuang-Yin; Liu, Zheng-Gen; Wang, Si-Yuan

    2017-07-01

    In order to realize comprehensive and massive treatment of boron mud secondary resource, fundamental study on boron mud applied to oxidized pellets production as additive was carried out in the paper under laboratory conditions. The effects of boron mud on the performance of oxidized pellets were investigated systemically, and boron mud was combined with other boron-rich material innovatively. The results showed that, within certain limits, boron mud can improve properties of oxidized pellets. The bentonite content decreased to 0.3 % when adding 1.0 % boron mud additive and the pellets met blast furnace requirements. With the combination additive content 0.8 %, bentonite content can be further decreased to 0.2 %, and the pellets properties were better than base pellet. Therefore, it was an effective way to reduce environmental pollution and optimize blast furnace operation by developing boron mud secondary resource as pellets additive.

  4. Direct current sputtering of boron from boron/coron mixtures

    DOEpatents

    Timberlake, John R.; Manos, Dennis; Nartowitz, Ed

    1994-01-01

    A method for coating a substrate with boron by sputtering includes lowering the electrical resistance of a boron-containing rod to allow electrical conduction in the rod; placing the boron-containing rod inside a vacuum chamber containing substrate material to be coated; applying an electrical potential between the boron target material and the vacuum chamber; countering a current avalanche that commences when the conduction heating rate exceeds the cooling rate, and until a steady equilibrium heating current is reached; and, coating the substrate material with boron by sputtering from the boron-containing rod.

  5. Wettability of boron carbide

    SciTech Connect

    Torvund, T.; Akselsen, O.M.; Ulvensoeen, J.H.; Grong, O.

    1994-12-31

    The wettability of boron carbide has been examined by means of the sessile drop method, using the following candidate alloys: (96wt%AG-4wt%Ti), (Ag-26.5wt%Cu-3wt%Ti), (Sn-10wt%Ag-4wt%Ti), Sn(99.95wt%) and Al(99.99wt%). The results show that B{sub 4}C is completely wetted by the Ag-based alloys. Sn-10wt%Ag-4wt%Ti alloy and pure Al partly wet the B{sub 4}C surface, while pure Sn does not wet B{sub 4}C at all. For all the alloys used, except pure Sn, a reaction layer was observed at the interface between the ceramic part and the metal drop. Although the spreading kinetics of the Al-drop was much slower compared with the Ti-containing alloys, the reaction rate was considerably higher in the former case. This suggests that aluminium is an attractive candidate material for brazing of B{sub 4}C. Formation of the low melting B{sub 2}O{sub 3} at the B{sub 4}C surface may cause oxidation of the filler metal during joining, which, in turn, leads to a low bond strength.

  6. Boron nitride composites

    DOEpatents

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

    2016-02-16

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

  7. Effect of boron on carbon-fiber microstructure and reactivity

    SciTech Connect

    Jones, L.E.

    1987-01-01

    A mesophase pitch P55 and a PAN T-300 carbon filter were substitutionally doped with boron at concentration levels ranging from 4 x 10/sup -5/ to 0.05 B/C atom ratio. Boron enhanced graphitization in these fibers at concentrations greater than 2 x 10/sup -4/ B/C. Below this concentration level, the microstructure of the pitch P55 fiber was unaffected. High concentrations of boron were found to modulate the (001) diffraction profiles in both fibers. This indicated the presence of two separate graphite fractions in the same fiber (one fraction was much more turbostratic than the other). The presence of boron was also found to increase the L/sub c/ and decrease the L/sub a/ dimensions of the more graphitic fractions of the fiber structure. The decrease in the L/sub a/ is the result of an increase in tilt boundaries along the a direction, parallel to the fiber axis. The presence of boron inhibits fiber gasification. The cause of gasification inhibition at high boron concentrations is related to changes in the fiber microstructure; however, there is a pronounced effect of specific-site blockage by an oxide of boron that develops on the surface during gasification. At relatively low boron concentrations, decrease in the reactivity of the fiber was correlated to changes in fiber electronic structure which, in turn, influences the chemistry of the active surface sites.

  8. Chemical disposition of boron in animals and humans.

    PubMed Central

    Moseman, R F

    1994-01-01

    Elemental boron was isolated in 1808. It typically occurs in nature as borates hydrated with varying amounts of water. Important compounds are boric acid and borax. Boron compounds are also used in the production of metals, enamels, and glasses. In trace amounts, boron is essential for the growth of many plants, and is found in animal and human tissues at low concentrations. Poisoning in humans has been reported as the result of accidental ingestion or use of large amounts in the treatment of burns. Boron as boric acid is fairly rapidly absorbed and excreted from the body via urine. The half-life of boric acid in humans is on the order of 1 day. Boron does not appear to accumulate in soft tissues of animals, but does accumulate in bone. Normal levels of boron in soft tissues, urine, and blood generally range from less than 0.05 ppm to no more than 10 ppm. In poisoning incidents, the amount of boric acid in brain and liver tissue has been reported to be as high as 2000 ppm. Recent studies at the National Institute of Environmental Health Sciences have indicated that boron may contribute to reduced fertility in male rodents fed 9000 ppm of boric acid in feed. Within a few days, boron levels in blood and most soft tissues quickly reached a plateau of about 15 ppm. Boron in bone did not appear to plateau, reaching 47 ppm after 7 days on the diet. Cessation of exposure to dietary boron resulted in a rapid drop in bone boron.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7889870

  9. Processing of boron carbide

    NASA Astrophysics Data System (ADS)

    Cho, Namtae

    The processing of boron carbide powder including sintering optimization, green body optimization and sintering behavior of nano-sized boron carbide was investigated for the development of complex shaped body armor. Pressureless sintered B4C relative densities as high as 96.7% were obtained by optimizing the soak temperature, and holding at that temperature for the minimum time required to reach terminal density. Although the relative densities of pressureless sintered specimens were lower than that of commercially produced hot-pressed B4C, their (Vickers) hardness values were comparable. For 4.45 cm dia. 1.35 cm height disk-shaped specimens, pressureless sintered to at least 93.0% relative density, post-hot isostatic pressing resulted in vast increases in relative densities (e.g. 100.0%) and hardness values significantly greater than that of commercially produced hot-pressed B 4C. The densification behavior of 20-40nm graphite-coated B4C nano-particles was studied using dilatometry, x-ray diffraction and electron microscopy. The higher than expected sintering onset from a nano-scale powder (˜1500°C) was caused by remnant B2O3 not removed by methanol washing, keeping particles separated until volatilization, and the carbon coatings, which imposed particle to particle contact of a substance more refractory than B4C. Solid state sintering (1500-1850°C) was followed by an arrest in contraction attributed to formation of eutectic liquid droplets of size more than 10X the original nano-particles. These droplets, induced to form well below known B4C-graphite eutectic temperatures by the high surface energy of nanoparticles, are interpreted to have quickly solidified to form a vast number of voids in particle packing, which in turn, impeded continued solid state sintering. Starting at 2200°C, a permanent liquid phase formed which facilitated a rapid measured contraction by liquid phase sintering and/or compact slumping.

  10. Update on human health effects of boron.

    PubMed

    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.

  11. Boron removal by electrocoagulation and recovery.

    PubMed

    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.

  12. Boron Partitioning Coefficient above Unity in Laser Crystallized Silicon

    PubMed Central

    Lill, Patrick C.; Dahlinger, Morris; Köhler, Jürgen R.

    2017-01-01

    Boron pile-up at the maximum melt depth for laser melt annealing of implanted silicon has been reported in numerous papers. The present contribution examines the boron accumulation in a laser doping setting, without dopants initially incorporated in the silicon wafer. Our numerical simulation models laser-induced melting as well as dopant diffusion, and excellently reproduces the secondary ion mass spectroscopy-measured boron profiles. We determine a partitioning coefficient kp above unity with kp=1.25±0.05 and thermally-activated diffusivity DB, with a value DB(1687K)=(3.53±0.44)×10−4 cm2·s−1 of boron in liquid silicon. For similar laser parameters and process conditions, our model predicts the anticipated boron profile of a laser doping experiment. PMID:28772548

  13. Boron Carbide Deposition on Urania and Urania-Gadolinia Fuels

    SciTech Connect

    Disbudak, H.; Uslu, I.; Bilgesu, A.Y.; Guenduez, G.

    2001-09-15

    Pure uranium dioxide and uranium dioxide-gadolinium oxide (5 and 10%) fuels used in this study were prepared by the solution-gelation (sol-gel) technique. The fuels were then coated with boron carbide by chemical vapor deposition. Boron carbide was produced from the reaction of carbon tetrachloride and boron trichloride with excess hydrogen, in a tube furnace at 1000, 1100, and 1175 deg. C. The Fourier transform infrared data of boron carbide deposited on a silica glass were in agreement with the ones in the literature. The experiments showed that the composition of the coating changed with deposition temperature. There was boron-rich coating at low-temperature deposition, and carbon-rich coating at high-temperature deposition. The morphology and the thickness of the coating have been investigated by using scanning electron microscopy and X-ray diffraction spectroscopy.

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

    PubMed

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

    2015-09-01

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

  15. Enhanced boron diffusion in excimer laser preannealed Si

    SciTech Connect

    Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.; La Magna, A.; Spinella, C.; Bongiorno, C.; Privitera, V.; Fortunato, G.; Mariucci, L.

    2005-04-11

    We have investigated boron diffusion during rapid thermal annealing in Si implanted with boron using an energy of 1 keV and a dose of 1x10{sup 16} cm{sup -2}. Two types of samples have been studied: As-implanted and pretreated with excimer laser annealing. For both types an enhanced diffusion of boron has been observed with an enhancement by a factor of 3-5 over the 'standard' diffusion. It is suggested that the high concentration of implanted boron is a dominant factor for the diffusion enhancement as compared to the effect of implantation-induced damage. The data indicate that the proximity of the surface can also affect the boron diffusion enhancement.

  16. Process for making boron nitride using sodium cyanide and boron

    DOEpatents

    Bamberger, Carlos E.

    1990-02-06

    This a very simple process for making boron nitride by mixing sodium cyanide and boron phosphate and heating the mixture in an inert atmosphere until a reaction takes place. The product is a white powder of boron nitride that can be used in applications that require compounds that are stable at high temperatures and that exhibit high electrical resistance.

  17. Process for making boron nitride using sodium cyanide and boron

    DOEpatents

    Bamberger, Carlos E.

    1990-01-01

    This a very simple process for making boron nitride by mixing sodium cyanide and boron phosphate and heating the mixture in an inert atmosphere until a reaction takes place. The product is a white powder of boron nitride that can be used in applications that require compounds that are stable at high temperatures and that exhibit high electrical resistance.

  18. Boron diffusion in nanocrystalline 3C-SiC

    SciTech Connect

    Schnabel, Manuel; Weiss, Charlotte; Rachow, Thomas; Löper, Philipp; Janz, Stefan; Canino, Mariaconcetta; Summonte, Caterina; Mirabella, Salvo; Wilshaw, Peter R.

    2014-05-26

    The diffusion of boron in nanocrystalline silicon carbide (nc-SiC) films with a grain size of 4–7 nm is studied using a poly-Si boron source. Diffusion is found to be much faster than in monocrystalline SiC as it takes place within the grain boundary (GB) network. Drive-in temperatures of 900–1000°C are suitable for creating shallow boron profiles up to 100 nm deep, while 1100°C is sufficient to flood the 200 nm thick films with boron. From the resulting plateau at 1100 °C a boron segregation coefficient of 28 between nc-SiC and the Si substrate, as well as a GB boron solubility limit of 0.2 nm{sup −2} is determined. GB diffusion in the bulk of the films is Fickian and thermally activated with D{sub GB}(T)=(3.1−5.6)×10{sup 7}exp(−5.03±0.16  eV/k{sub B}T) cm{sup 2}s{sup −1}. The activation energy is interpreted in terms of a trapping mechanism at dangling bonds. Higher boron concentrations are present at the nc-SiC surface and are attributed to immobilized boron.

  19. Proton linacs for boron neutron capture therapy

    SciTech Connect

    Lennox, A.J. |

    1993-08-01

    Recent advances in the ability to deliver boron-containing drugs to brain tumors have generated interest in {approximately}4 MeV linacs as sources of epithermal neutrons for radiation therapy. In addition, fast neutron therapy facilities have been studying methods to moderate their beams to take advantage of the high cross section for epithermal neutrons on boron-10. This paper describes the technical issues involved in each approach and presents the motivation for undertaking such studies using the Fermilab linac. the problems which must be solved before therapy can begin are outlined. Status of preparatory work and results of preliminary measurements are presented.

  20. Can Two-Dimensional Boron Superconduct?

    PubMed

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

    2016-04-13

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

  1. Accelerator-driven boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    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.

  2. Challenges and Opportunities for the Application of Boron Clusters in Drug Design.

    PubMed

    Leśnikowski, Zbigniew J

    2016-09-08

    There are two branches in boron medicinal chemistry: the first focuses on single boron atom compounds, and the second utilizes boron clusters. Boron clusters and their heteroatom counterparts belong to the family of cage compounds. A subset of this extensive class of compounds includes dicarbadodecaboranes, which have the general formula C2B10H12, and their metal biscarboranyl complexes, metallacarboranes, with the formula [M(C2B10H12)2(-2)]. The unique properties of boron clusters have resulted in their utilization in applications such as in pharmacophores, as scaffolds in molecular construction, and as modulators of bioactive compounds. This Perspective presents an overview of the properties of boron clusters that are pertinent for drug discovery, recent applications in the design of various classes of drugs, and the potential use of boron clusters in the construction of new pharmaceuticals.

  3. Boron-based nanostructures: Synthesis, functionalization, and characterization

    NASA Astrophysics Data System (ADS)

    Bedasso, Eyrusalam Kifyalew

    Boron-based nanostructures have not been explored in detail; however, these structures have the potential to revolutionize many fields including electronics and biomedicine. The research discussed in this dissertation focuses on synthesis, functionalization, and characterization of boron-based zero-dimensional nanostructures (core/shell and nanoparticles) and one-dimensional nanostructures (nanorods). The first project investigates the synthesis and functionalization of boron-based core/shell nanoparticles. Two boron-containing core/shell nanoparticles, namely boron/iron oxide and boron/silica, were synthesized. Initially, boron nanoparticles with a diameter between 10-100 nm were prepared by decomposition of nido-decaborane (B10H14) followed by formation of a core/shell structure. The core/shell structures were prepared using the appropriate precursor, iron source and silica source, for the shell in the presence of boron nanoparticles. The formation of core/shell nanostructures was confirmed using high resolution TEM. Then, the core/shell nanoparticles underwent a surface modification. Boron/iron oxide core/shell nanoparticles were functionalized with oleic acid, citric acid, amine-terminated polyethylene glycol, folic acid, and dopamine, and boron/silica core/shell nanoparticles were modified with 3-(amino propyl) triethoxy silane, 3-(2-aminoethyleamino)propyltrimethoxysilane), citric acid, folic acid, amine-terminated polyethylene glycol, and O-(2-Carboxyethyl)polyethylene glycol. A UV-Vis and ATR-FTIR analysis established the success of surface modification. The cytotoxicity of water-soluble core/shell nanoparticles was studied in triple negative breast cancer cell line MDA-MB-231 and the result showed the compounds are not toxic. The second project highlights optimization of reaction conditions for the synthesis of boron nanorods. This synthesis, done via reduction of boron oxide with molten lithium, was studied to produce boron nanorods without any

  4. Boronated liposome development and evaluation

    SciTech Connect

    Hawthorne, M.F.

    1995-11-01

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

  5. Mineral of the month: boron

    USGS Publications Warehouse

    Lyday, Phyllis A.

    2005-01-01

    What does boron have to do with baseball, apple pie, motherhood and Chevrolet? Boron minerals and chemicals are used in the tanning of leather baseballs and gloves; in micro-fertilizer to grow apples and in the glass and enamels of bakewares to cook apple pie; in boron detergents for soaking baby clothes and diapers; and in fiberglass parts for the Chevrolet Corvette.

  6. Boron-enhanced diffusion of boron from ultralow-energy ion implantation

    SciTech Connect

    Agarwal, A.; Gossmann, H.; Eaglesham, D.J.; Herner, S.B.; Fiory, A.T.; Haynes, T.E.

    1999-04-01

    We have investigated the diffusion enhancement mechanism of boron-enhanced diffusion (BED), wherein boron diffusivity is enhanced four to five times over the equilibrium diffusivity at 1050&hthinsp;{degree}C in the proximity of a silicon layer containing a high boron concentration. It is demonstrated that BED is driven by excess interstitials injected from the high boron concentration layer during annealing. For evaporated layers, BED is observed above a threshold boron concentration between 1{percent} and 10{percent}, though it appears to be closer to 1{percent} for B-implanted layers. For sub-keV B implants above the threshold, BED dominates over the contribution from transient-enhanced diffusion to junction depth. For 0.5 keV B, this threshold implantation dose lies between 3{times}10{sup 14} and 1{times}10{sup 15} cm{sup {minus}2}. It is proposed that the excess interstitials responsible for BED are produced during the formation of a silicon boride phase in the high B concentration layers. {copyright} {ital 1999 American Institute of Physics.}

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

    SciTech Connect

    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. Effects of dietary boron on cervical cytopathology and on micronucleus frequency in exfoliated buccal cells.

    PubMed

    Korkmaz, Mehmet; Uzgören, Engin; Bakirdere, Sezgin; Aydin, Firat; Ataman, O Yavuz

    2007-02-01

    Recent evidence indicates that boron and borates may have anticarcinogenic properties. In this study, we have investigated the incidence of adverse cytological findings in cervical smears and the micronucleus (MN) frequency in women living in boron-rich and boron-poor regions. Cervical smears were prepared from 1059 women with low socioeconomic status; 472 of the women lived in relatively boron-rich rural areas, while 587 lived in relatively boron-poor regions. The average and standard deviation values for the age of the women screened with the cervical Pap smear test were 41.55 +/- 8.38. The mean dietary intake of boron was 8.41 mg/day for women from the boron-rich regions, and 1.26 mg/day for women living in the boron-poor regions (P < 0.0001). Women from the boron-rich regions had no cytopathological indications of cervical cancer, while there were cytopathological findings for 15 women from the boron-poor areas (chi(2) = 10.473, P < 0.05). Sixty women, 30 from each region, were chosen for evaluating MN frequencies in exfoliated buccal cells. MN frequencies for women from the boron-rich and boron-poor regions were not significantly different (t = -0.294, P > 0.05). Also, there were no significant correlations between age and MN frequency for women from both the boron-rich (r = 0.133, P = 0.48, P > 0.05) and boron-poor (r = -0.033, P = 0.861, P > 0.05) regions. The results suggest that ingestion of boron in the drinking water decreases the incidence of cervical cancer-related histopathological findings. There was no correlation between the pathological findings from the cervical smears and buccal cell MN frequency suggesting that the two study populations were exposed equally to gentotoxic agents. Nonetheless, cervical cancer-related histopathological findings should be validated by other researchers.

  9. Annealing studies of highly doped boron superlattices

    SciTech Connect

    Jackman, T. E.; Houghton, D. C.; Jackman, J. A.; Denhoff, M. W.; Kechang, S.; McCaffrey, J.; Rockett, A.

    1989-09-01

    Coevaporation of B/sub 2/ O/sub 3/ during silicon molecular-beam epitaxy at growth temperatures (/ital T//sub /ital G// ) varying from 540 to 800 /degree/C has been used to prepare superlattice structures (/ital pipi/'s) of varying boron concentration (3/times/10/sup 18/ --3/times/10/sup 20/ B cm/sup /minus/3/). The superlattices were subsequently subjected to various annealing procedures and the layers were examined by secondary ion mass spectrometry, electrochemical profiling, and cross-sectional transmission electron microscopy. A significant redistribution of boron was observed even before annealing for /ital T//sub /ital G// /gt/700 /degree/C and high boron concentrations. In addition, significant oxygen was incorporated for /ital T//sub /ital G// /le/700 /degree/C, with a growth rate of 0.5 nm s/sup /minus/1/ and a B/sub 2/ O/sub 3/ flux of 2/times/10/sup 13/ cm/sup /minus/2/ s/sup /minus/1/. After annealing, the boron diffusion coefficients were determined for the layers and found to vary significantly with /ital T//sub /ital G//.

  10. Neutron detectors comprising ultra-thin layers of boron powder

    DOEpatents

    Wang, Zhehul; Morris, Christopher

    2013-07-23

    High-efficiency neutron detector substrate assemblies comprising a first conductive substrate, wherein a first side of the substrate is in direct contact with a first layer of a powder material having a thickness of from about 50 nm to about 250 nm and comprising .sup.10boron, .sup.10boron carbide or combinations thereof, and wherein a conductive material is in proximity to the first layer of powder material; and processes of making said neutron detector substrate assemblies.

  11. Minerals Yearbook 1989: Boron

    SciTech Connect

    Lyday, P.A.

    1990-08-01

    U.S. production and sales of boron minerals and chemicals decreased during the year. Domestically, glass fiber insulation was the largest use for borates, followed by sales to distributors, textile-grade glass fibers, and borosilicate glasses. California was the only domestic source of boron minerals. The United States continued to provide essentially all of its own supply while maintaining a strong position as a source of sodium borate products and boric acid exported to foreign markets. Supplementary U.S. imports of Turkish calcium borate and calcium-sodium borate ores, borax, and boric acid, primarily for various glass uses, continued.

  12. Boron hydride polymer coated substrates

    DOEpatents

    Pearson, Richard K.; Bystroff, Roman I.; Miller, Dale E.

    1987-01-01

    A method is disclosed for coating a substrate with a uniformly smooth layer of a boron hydride polymer. The method comprises providing a reaction chamber which contains the substrate and the boron hydride plasma. A boron hydride feed stock is introduced into the chamber simultaneously with the generation of a plasma discharge within the chamber. A boron hydride plasma of ions, electrons and free radicals which is generated by the plasma discharge interacts to form a uniformly smooth boron hydride polymer which is deposited on the substrate.

  13. Boron hydride polymer coated substrates

    DOEpatents

    Pearson, R.K.; Bystroff, R.I.; Miller, D.E.

    1986-08-27

    A method is disclosed for coating a substrate with a uniformly smooth layer of a boron hydride polymer. The method comprises providing a reaction chamber which contains the substrate and the boron hydride plasma. A boron hydride feed stock is introduced into the chamber simultaneously with the generation of a plasma discharge within the chamber. A boron hydride plasma of ions, electrons and free radicals which is generated by the plasma discharge interacts to form a uniformly smooth boron hydride polymer which is deposited on the substrate.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    PubMed

    Hsu, C F; Lin, S Y; Peir, J J; Liao, J W; Lin, Y C; Chou, F I

    2011-12-01

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

  16. Receptor-mediated uptake of boron-rich neuropeptide y analogues for boron neutron capture therapy.

    PubMed

    Ahrens, Verena M; Frank, René; Boehnke, Solveig; Schütz, Christian L; Hampel, Gabriele; Iffland, Dorothée S; Bings, Nicolas H; Hey-Hawkins, Evamarie; Beck-Sickinger, Annette G

    2015-01-01

    Peptidic ligands selectively targeting distinct G protein-coupled receptors that are highly expressed in tumor tissue represent a promising approach in drug delivery. Receptor-preferring analogues of neuropeptide Y (NPY) bind and activate the human Y1 receptor subtype (hY1 receptor), which is found in 90% of breast cancer tissue and in all breast-cancer-derived metastases. Herein, novel highly boron-loaded Y1 -receptor-preferring peptide analogues are described as smart shuttle systems for carbaboranes as (10) B-containing moieties. Various positions in the peptide were screened for their susceptibility to carbaborane modification, and the most promising positions were chosen to create a multi-carbaborane peptide containing 30 boron atoms per peptide with excellent activation and internalization patterns at the hY1 receptor. Boron uptake studies by inductively coupled plasma mass spectrometry revealed successful uptake of the multi-carbaborane peptide into hY1 -receptor-expressing cells, exceeding the required amount of 10(9) boron atoms per cell. This result demonstrates that the NPY/hY receptor system can act as an effective transport system for boron-containing moieties.

  17. Fabrication of boron sputter targets

    DOEpatents

    Makowiecki, D.M.; McKernan, M.A.

    1995-02-28

    A process is disclosed for fabricating high density boron sputtering targets with sufficient mechanical strength to function reliably at typical magnetron sputtering power densities and at normal process parameters. The process involves the fabrication of a high density boron monolithe by hot isostatically compacting high purity (99.9%) boron powder, machining the boron monolithe into the final dimensions, and brazing the finished boron piece to a matching boron carbide (B{sub 4}C) piece, by placing aluminum foil there between and applying pressure and heat in a vacuum. An alternative is the application of aluminum metallization to the back of the boron monolithe by vacuum deposition. Also, a titanium based vacuum braze alloy can be used in place of the aluminum foil. 7 figs.

  18. Fabrication of boron sputter targets

    DOEpatents

    Makowiecki, Daniel M.; McKernan, Mark A.

    1995-01-01

    A process for fabricating high density boron sputtering targets with sufficient mechanical strength to function reliably at typical magnetron sputtering power densities and at normal process parameters. The process involves the fabrication of a high density boron monolithe by hot isostatically compacting high purity (99.9%) boron powder, machining the boron monolithe into the final dimensions, and brazing the finished boron piece to a matching boron carbide (B.sub.4 C) piece, by placing aluminum foil there between and applying pressure and heat in a vacuum. An alternative is the application of aluminum metallization to the back of the boron monolithe by vacuum deposition. Also, a titanium based vacuum braze alloy can be used in place of the aluminum foil.

  19. Determination of phase stability of elemental boron.

    PubMed

    White, Mary Anne; Cerqueira, Anthony B; Whitman, Catherine A; Johnson, Michel B; Ogitsu, Tadashi

    2015-03-16

    Boron is an important element, used in applications from superhard materials to superconductors. Boron exists in several forms (allotropes) and, surprisingly, it was not known which form (α or β) is stable at ambient conditions. Through experiment, we quantify the relative stability of α-boron and β-boron as a function of temperature. The ground-state energies of α-boron and β-boron are nearly identical. For all temperatures up to 2000 K, the complicated β-boron structure is more stable than the simpler α-boron structure at ambient pressure. Below 1000 K, β-boron is entropically stabilized with respect to α-boron owing to its partially occupied sites, whereas at higher temperatures β-boron is enthalpically stabilized with respect to α-boron. We show that α-boron only becomes stable on application of pressure.

  20. Risk assessment of boron in glass wool insulation.

    PubMed

    Jensen, Allan Astrup

    2009-01-01

    inhalation rate of the individuals at moderate work load was set to 2 m3/h. A worst-case scenario also corresponds to 100% retention and to 100% solubility of the retained fibres in the lungs. With the normal boron content of 1.5% in glass wool fibres for building insulation, the extra daily occupational boron intake/uptake will be 0.03-0.06 mg B for 5 days a week. For more uncommon glass wool with maximum boron content of 3.5%, the worst-case daily boron intake/uptake will be 0.08-0.16 mg B. The main boron exposure in the general population is from vegetarian food, and the average daily dietary intake with food is estimated to 1.2-1.5 mg B/day. In addition, significant intakes may come with drinking water, especially from mineral water. In some instances, exposure from mineral supplements, cosmetics and other consumer products may be significant. For example, individuals taking mineral supplements, e.g. for bodybuilding, may have an additional intake to that of 1-10 mg/day. During the years, various organisations have recommended safe intake values for boron. Recently, the Scientific Panel on Dietetic Products, Nutrition and Allergies of the European Food Safety Authority (EFSA) has established the 'Tolerable Upper Intake Level' (UL) for the intake of boron (boric acid and borates) at 0.16 mg B/kg body weight per day or about 10 mg B/day for an adult. The calculated, worst-case exposure scenario during an 8-h work day will result in an extra daily boron intake that only corresponds to about 10% of the average daily adult boron intakes through food and drinks of about 1.5 mg. The inter-individual variations in boron intakes from foods, water and supplements will be much greater than an eventual, very worst-case, additional intake of boron from inhalation of glass wool fibres. In addition, the combined intakes are far lower than the 'Tolerable Upper Intake Level' of 10 mg B/day for a person weighing 60 kg, as recommended by the European Food Safety Agency. The potential boron

  1. Process for microwave sintering boron carbide

    DOEpatents

    Holcombe, Cressie E.; Morrow, Marvin S.

    1993-01-01

    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.

  2. Process for microwave sintering boron carbide

    DOEpatents

    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.

  3. Chemoradiotherapy of cancer: Boronated antibodies and boron-containing derivatives of chlorpromazine and porphyrins for neutron capture therapy

    SciTech Connect

    Soloway, A.H.

    1988-01-01

    Monoclonal antibodies directed against tumor associated antigens have been proposed for the selective targeting of malignant cells with boron-10. The purpose of this task was to optimize the conditions for linking a large number of boron atoms to antibody molecules without compromising the antibody's immunoreactivity. There has been a need to develop methodologies for the separation, purification and characterization of such immunoconjugates prior to their evaluation both under in vitro and in vivo conditions. During this project period, much of the effort has concentrated on MoAb 17-1A which is directed against human colorectal cancer. The observed selective concentration of chlorpromazine in melanotic tissue and its high localization in murine melanoma indicated that boronated analogues of chlorpromazine potentially could be used to deliver sufficient concentration of boron-10 for BNCT of melanomas. Five boronated promazines have been synthesized and fully characterized. The phthalocyanines, as with various porphyrins, have been shown to be incorporated to a significant extent in malignant tumors. As a consequence, we have undertaken the synthesis of boron-containing phthalocyanines. Initial efforts have concentrated on the sulfonation of copper phthalocyanine by chlorosulfonation followed by reaction with aminocarboranes such as p-amino-phenylcarborane. We have achieved an average of 18 boron atoms per phthalocyanine molecule. 1 fig.

  4. Biological efficacy of boronated low-density lipoprotein for boron neutron capture therapy as measured in cell culture.

    PubMed

    Laster, B H; Kahl, S B; Popenoe, E A; Pate, D W; Fairchild, R G

    1991-09-01

    Low-density lipoproteins (LDLs) are known to be internalized by the cell through receptor-mediated mechanisms. There is evidence that LDLs may be taken up avidly by tumor cells to provide cholesterol for the synthesis of cell membranes. Thus, the possibility exists that LDLs may provide an ideal vehicle for the transport of boron to tumor cells for boron neutron capture therapy. A boronated analogue of LDL has recently been synthesized for possible application in boron neutron capture therapy. The analogue was tested in cell culture for uptake and biological efficacy in the thermal neutron beam at the Brookhaven Medical Research Reactor. It was found that boron concentrations 10 times higher than that required in tumors for boron neutron capture therapy were easily obtained and that the amount of uptake was consistent with a receptor-mediated binding mechanism. The measured intracellular concentration of approximately 240 micrograms 10B/g cells is significantly higher than that obtained with any other boron compound previously evaluated for possible clinical application.

  5. Comment on: "Is linear group X-Y-Z in boron carbide the weakest link in the structure?" by S. V. Konovalikhin and V. I. Ponomarev (Russ. J. Phys. Chem. A 89 (10), 1850 (2015))

    NASA Astrophysics Data System (ADS)

    Werheit, H.

    2016-07-01

    The characterization of the boron carbide investigated in the above-mentioned paper and some of the conclusions made on it by the authors are critically appraised with regard to reliable results obtained earlier by other scientists.

  6. Methods of producing continuous boron carbide fibers

    SciTech Connect

    Garnier, John E.; Griffith, George W.

    2015-12-01

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

  7. Boron and Compounds

    Integrated Risk Information System (IRIS)

    EPA 635 / 04 / 052 www.epa.gov / iris TOXICOLOGICAL REVIEW OF BORON AND COMPOUNDS ( CAS No . 7440 - 42 - 8 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) June 2004 U.S . Environmental Protection Agency Washington , DC DISCLAIMER This document has been reviewed

  8. Autoionizing states of atomic boron

    NASA Astrophysics Data System (ADS)

    Argenti, Luca; Moccia, Roberto

    2016-04-01

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

  9. Composite boron nitride neutron detectors

    NASA Astrophysics Data System (ADS)

    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.

  10. Boron-copper neutron absorbing material and method of preparation

    DOEpatents

    Wiencek, Thomas C.; Domagala, Robert F.; Thresh, Henry

    1991-01-01

    A composite, copper clad neutron absorbing material is comprised of copper powder and boron powder enriched with boron 10. The boron 10 content can reach over 30 percent by volume, permitting a very high level of neutron absorption. The copper clad product is also capable of being reduced to a thickness of 0.05 to 0.06 inches and curved to a radius of 2 to 3 inches, and can resist temperatures of 900.degree. C. A method of preparing the material includes the steps of compacting a boron-copper powder mixture and placing it in a copper cladding, restraining the clad assembly in a steel frame while it is hot rolled at 900.degree. C. with cross rolling, and removing the steel frame and further rolling the clad assembly at 650.degree. C. An additional sheet of copper can be soldered onto the clad assembly so that the finished sheet can be cold formed into curved shapes.

  11. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Slatkin, Daniel N.

    1995-10-03

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na.sub.4 B.sub.12 I.sub.11 SSB.sub.12 I.sub.11, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy.

  12. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Slatkin, Daniel N.

    1997-03-18

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na.sub.4 B.sub.12 I.sub.11 SSB.sub.12 I.sub.11, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy.

  13. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Slatkin, Daniel N.

    1997-08-05

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized. by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na.sub.4 B.sub.12 I.sub.11 SSB.sub.12 I.sub.11, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy.

  14. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, M.; Slatkin, D.N.

    1997-08-05

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na{sub 4}B{sub 12}I{sub 11}SSB{sub 12}I{sub 11}, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy. 1 fig.

  15. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, M.; Slatkin, D.N.

    1995-10-03

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na{sub 4}B{sub 12}I{sub 11}SSB{sub 12}I{sub 11}, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy. 1 fig.

  16. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, M.; Slatkin, D.N.

    1997-03-18

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na{sub 4}B{sub 12}I{sub 11}SSB{sub 12}I{sub 11}, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy. 1 fig.

  17. Prevalence of prostate cancer in high boron-exposed population: a community-based study.

    PubMed

    Müezzinoğlu, Talha; Korkmaz, Mehmet; Neşe, Nalan; Bakırdere, Sezgin; Arslan, Yasin; Ataman, O Yavuz; Lekili, Murat

    2011-12-01

    We investigated the possible relationship between boron exposure and prostate cancer (PCa) for men living and being employed at boron mines in villages with rich boron minerals. Out of 456 men studied, 159 were from villages with rich boron sources and boron levels in drinking water of >1 mg L(-1) and these men formed the study group, while 63 from villages with rich boron sources and boron levels in drinking water of <1 mg L(-1) were enrolled into control group 1. A further 234 subjects from other villages with no boron mines were considered as control group 2. Prostate specific antigen (PSA) levels could be obtained from a total of 423 men. Urinary boron concentration as an indicator of boron exposure in 63 subjects, prostatic volumes by transrectal ultrasonography in 39 subjects, and prostatic biopsies in 36 subjects were obtained for study and control groups. The daily boron exposure was calculated according to urinary boron levels. Although there was no significant difference among the groups in terms of total PSA levels, the number of subjects with tPSA ≥2.5 and tPSA ≥10.0 ng dL(-1) prostatic volumes in men whose prostates were biopsied (p < 0.012) was significantly lower in the study group as compared with those in the control group 2. These results suggested that high exposure to boron might have an implication within the prostatic cellular processes related to hyperplasia and carcinogenesis, even though we did not find a statistically significant association between PCa and boron exposure.

  18. Energetics of Boron Doping of Carbon Pores

    NASA Astrophysics Data System (ADS)

    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.

  19. Boron neutron capture therapy (BNCT) for the treatment of liver metastases: biodistribution studies of boron compounds in an experimental model.

    PubMed

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

    2011-03-01

    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 (10)B 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 (Na(2)(10)B(10)H(10)), 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. © Springer-Verlag 2010

  20. Impact of boron dilution accidents on low boron PWR safety

    SciTech Connect

    Papukchiev, A.; Liu, Y.; Schaefer, A.

    2006-07-01

    In conventional pressurized water reactor (PWR) designs, soluble boron is used for reactivity control over core fuel cycle. As an inadvertent reduction of the boron concentration during a boron dilution accident could introduce positive reactivity and have a negative impact on PWR safety, design changes to reduce boron concentration in the reactor coolant are of general interest. In the framework of an investigation into the feasibility of low boron design, a PWR core configuration based on fuel with higher gadolinium (Gd) load has been developed which permits to reduce the natural boron concentration at begin of cycle (BOC) to 518 ppm. For the assessment of the potential safety advantages, a boron dilution accident due to small break loss-of-coolant-accident (SBLOCA) has been simulated with the system code ATHLET for two PWR core designs: a low boron design and a standard core design. The results from the comparative analyses showed that the impact of the boron dilution accident on the new PWR design safety is significantly lower in comparison with the standard design. The new reactor design provided at least 4, 4% higher reactivity margin to recriticality during the whole accident which is equivalent to the negative reactivity worth of additional 63% of all control rods fully inserted in to the core. (authors)

  1. Boronizing protects metals against wear

    SciTech Connect

    Stewart, K.

    1997-03-01

    Boronizing is a thermochemical surface treatment that involves diffusion of boron into a base metal at a high temperature. The resulting metallic boride provides high hardness and resistance to acid corrosion, and lengthens service life by a factor of three to ten. Boronizing fills a gap between conventional surface treatments and the more exotic chemical and physical vapor deposition. In a number of applications, boronizing has replaced such processes as carburizing, nitriding, and nitrocarburizing. It has even replaced hard chrome plating in some cases, while achieving similar service life improvements. Boron can be uniformly applied to irregular surfaces, and can be applied to specific areas of a surface. It is also suitable for high-volume production applications, as first demonstrated in the European automotive industry. This article describes the boronizing process, provides material selection/preparation criteria, and lists industrial applications.

  2. Effect of fluorine implantation dose on boron thermal diffusion in silicon

    SciTech Connect

    El Mubarek, H.A.W.; Bonar, J.M; Dilliway, G.D.; Ashburn, P.; Karunaratne, M.; Willoughby, A.F.; Wang, Y.; Hemment, P.L.F.; Price, R.; Zhang, J.; Ward, P.

    2004-10-15

    This paper investigates how the thermal diffusion of boron in silicon is influenced by a high energy fluorine implant with a dose in the range 5x10{sup 14}-2.3x10{sup 15} cm{sup -2}. Secondary Ion Mass Spectroscopy (SIMS) profiles of boron marker layers are presented for different fluorine doses and compared with fluorine profiles to establish the conditions under which thermal boron diffusion is suppressed. The (SIMS) profiles show significantly reduced boron thermal diffusion above a critical F{sup +} dose of 0.9-1.4x10{sup 15} cm{sup -2}. Fitting of the measured boron profiles gives suppressions of the boron thermal diffusion coefficient by factors of 1.9 and 3.7 for F{sup +} implantation doses of 1.4x10{sup 15} and 2.3x10{sup 15} cm{sup -2}, respectively. The suppression of boron thermal diffusion above the critical fluorine dose correlates with the appearance of a shallow fluorine peak on the (SIMS) profile in the vicinity of the boron marker layer. This shallow fluorine peak is present in samples with and without boron marker layers, and hence it is not due to a chemical interaction between the boron and the fluorine. Analysis of the (SIMS) profiles and cross-section Transmission Electron Microscope micrographs suggests that it is due to the trapping of fluorine at vacancy-fluorine clusters, and that the suppression of the boron thermal diffusion is due to the effect of the clusters in suppressing the interstitial concentration in the vicinity of the boron profile.

  3. Boron Neutron Capture Therapy (BNCT) Dose Calculation using Geometrical Factors Spherical Interface for Glioblastoma Multiforme

    SciTech Connect

    Zasneda, Sabriani; Widita, Rena

    2010-06-22

    Boron Neutron Capture Therapy (BNCT) is a cancer therapy by utilizing thermal neutron to produce alpha particles and lithium nuclei. The superiority of BNCT is that the radiation effects could be limited only for the tumor cells. BNCT radiation dose depends on the distribution of boron in the tumor. Absorbed dose to the cells from the reaction 10B (n, {alpha}) 7Li was calculated near interface medium containing boron and boron-free region. The method considers the contribution of the alpha particle and recoiled lithium particle to the absorbed dose and the variation of Linear Energy Transfer (LET) charged particles energy. Geometrical factor data of boron distribution for the spherical surface is used to calculate the energy absorbed in the tumor cells, brain and scalp for case Glioblastoma Multiforme. The result shows that the optimal dose in tumor is obtained for boron concentrations of 22.1 mg {sup 10}B/g blood.

  4. Heavy boron doping in low-temperature Si photoepitaxy

    SciTech Connect

    Yamazaki, T.; Watanabe, S.; Ito, T. )

    1990-01-01

    Heavy boron doping of up to 1.5 {times} 10{sup 20} cm{sup {minus} 3} was achieved in a photoepitaxial layer grown at 650{degrees}C. Under UV irradiation, the doped carrier concentration was independent of the diborane flow rate in the heavily doped region and doped boron atoms were completely activated up to 1.5 {times} 10{sup 20} cm{sup {minus} 3}. Without UV irradiation, no single crystals were grown and very few boron atoms were activated in the heavily doped region. The authors studied the crystal quality using Raman scattering spectroscopy and found that, under UV irradiation, single crystals could be grown up to 1.5 {times} 10{sup 20} cm{sup {minus} 3}. The boron atom activation ratio depended strongly on the crystal quality. UV irradiation markedly increased carrier doping efficiency due to photo-enhancement of the diborane vapor phase reaction, which we studied using FTIR and the surface reaction of adsorbed species. The electrical properties of low-temperature photoepitaxial layer with heavy boron doping were studied using a bipolar transistor. Excellent device characteristics were achieved. Low-temperature photoepitaxy also produced very abrupt boron profiles.

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

    SciTech Connect

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

    2011-03-01

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

  6. Computational assessment of deep-seated tumor treatment capability of the 9Be(d,n)10B reaction for accelerator-based boron neutron capture therapy (AB-BNCT).

    PubMed

    Capoulat, M E; Minsky, D M; Kreiner, A J

    2014-03-01

    The 9Be(d,n)10B reaction was studied as an epithermal neutron source for brain tumor treatment through Boron Neutron Capture Therapy (BNCT). In BNCT, neutrons are classified according to their energies as thermal (<0.5 eV), epithermal (from 0.5 eV to 10 keV) or fast (>10 keV). For deep-seated tumors epithermal neutrons are needed. Since a fraction of the neutrons produced by this reaction are quite fast (up to 5-6 MeV, even for low-bombarding energies), an efficient beam shaping design is required. This task was carried out (1) by selecting the combinations of bombarding energy and target thickness that minimize the highest-energy neutron production; and (2) by the appropriate choice of the Beam Shaping Assembly (BSA) geometry, for each of the combinations found in (1). The BSA geometry was determined as the configuration that maximized the dose deliverable to the tumor in a 1 h treatment, within the constraints imposed by the healthy tissue dose adopted tolerance. Doses were calculated through the MCNP code. The highest dose deliverable to the tumor was found for an 8 μm target and a deuteron beam of 1.45 MeV. Tumor weighted doses ≥40 Gy can be delivered up to about 5 cm in depth, with a maximum value of 51 Gy at a depth of about 2 cm. This dose performance can be improved by relaxing the treatment time constraint and splitting the treatment into two 1-h sessions. These good treatment capabilities strengthen the prospects for a potential use of this reaction in BNCT. Copyright © 2013 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  7. Microstructure Analysis of Boron Nanotubes

    DTIC Science & Technology

    2012-05-01

    figure 1 2 3 High resolution TEM showing very small elongated BNT filaments 3 4 SAED from an area in figure 3 showing exactly the same kind of...scattered large numbers of BNT 4 7 EDAX analyses of boron nitride nano powder showing boron and oxygen 5 8 Low magnification SEM picture of folded 600...Picatinny Arsenal, New Jersey. INTRODUCTION Boron nanotubes ( BNT ) have never been produced in a reliable manner, yet they remain a promising

  8. Structures, stability, mechanical and electronic properties of α-boron and α∗-boron

    NASA Astrophysics Data System (ADS)

    He, Chaoyu; Zhong, J. X.

    2013-04-01

    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 α*-boron are confirmed dynamically and mechanically stable. The mechanical and electronic properties of α-boron and α*-boron indicate that they are potential superhard semiconducting phases of element boron.

  9. Understanding boron through size-selected clusters: structure, chemical bonding, and fluxionality.

    PubMed

    Sergeeva, Alina P; Popov, Ivan A; Piazza, Zachary A; Li, Wei-Li; Romanescu, Constantin; Wang, Lai-Sheng; Boldyrev, Alexander I

    2014-04-15

    Boron is an interesting element with unusual polymorphism. While three-dimensional (3D) structural motifs are prevalent in bulk boron, atomic boron clusters are found to have planar or quasi-planar structures, stabilized by localized two-center-two-electron (2c-2e) σ bonds on the periphery and delocalized multicenter-two-electron (nc-2e) bonds in both σ and π frameworks. Electron delocalization is a result of boron's electron deficiency and leads to fluxional behavior, which has been observed in B13(+) and B19(-). A unique capability of the in-plane rotation of the inner atoms against the periphery of the cluster in a chosen direction by employing circularly polarized infrared radiation has been suggested. Such fluxional behaviors in boron clusters are interesting and have been proposed as molecular Wankel motors. The concepts of aromaticity and antiaromaticity have been extended beyond organic chemistry to planar boron clusters. The validity of these concepts in understanding the electronic structures of boron clusters is evident in the striking similarities of the π-systems of planar boron clusters to those of polycyclic aromatic hydrocarbons, such as benzene, naphthalene, coronene, anthracene, or phenanthrene. Chemical bonding models developed for boron clusters not only allowed the rationalization of the stability of boron clusters but also lead to the design of novel metal-centered boron wheels with a record-setting planar coordination number of 10. The unprecedented highly coordinated borometallic molecular wheels provide insights into the interactions between transition metals and boron and expand the frontier of boron chemistry. Another interesting feature discovered through cluster studies is boron transmutation. Even though it is well-known that B(-), formed by adding one electron to boron, is isoelectronic to carbon, cluster studies have considerably expanded the possibilities of new structures and new materials using the B(-)/C analogy. It is

  10. Reduced boron diffusion under interstitial injection in fluorine implanted silicon

    SciTech Connect

    Kham, M. N.; Matko, I.; Chenevier, B.; Ashburn, P.

    2007-12-01

    Point defect injection studies are performed to investigate how fluorine implantation influences the diffusion of boron marker layers in both the vacancy-rich and interstitial-rich regions of the fluorine damage profile. A 185 keV, 2.3x10{sup 15} cm{sup -2} F{sup +} implant is made into silicon samples containing multiple boron marker layers and rapid thermal annealing is performed at 1000 deg. C for times of 15-120 s. The boron and fluorine profiles are characterized by secondary ion mass spectroscopy and the defect structures by transmission electron microscopy (TEM). Fluorine implanted samples surprisingly show less boron diffusion under interstitial injection than those under inert anneal. This effect is particularly noticeable for boron marker layers located in the interstitial-rich region of the fluorine damage profile and for short anneal times (15 s). TEM images show a band of dislocation loops around the range of the fluorine implant and the density of dislocation loops is lower under interstitial injection than under inert anneal. It is proposed that interstitial injection accelerates the evolution of interstitial defects into dislocation loops, thereby giving transient enhanced boron diffusion over a shorter period of time. The effect of the fluorine implant on boron diffusion is found to be the opposite for boron marker layers in the interstitial-rich and vacancy-rich regions of the fluorine damage profile. For marker layers in the interstitial-rich region of the fluorine damage profile, the boron diffusion coefficient decreases with anneal time, as is typically seen for transient enhanced diffusion. The boron diffusion under interstitial injection is enhanced by the fluorine implant at short anneal times but suppressed at longer anneal times. It is proposed that this behavior is due to trapping of interstitials at the dislocation loops introduced by the fluorine implant. For boron marker layers in the vacancy-rich region of the fluorine damage profile

  11. Boron nitride nanotubes.

    PubMed

    Chopra, N G; Luyken, R J; Cherrey, K; Crespi, V H; Cohen, M L; Louie, S G; Zettl, A

    1995-08-18

    The successful synthesis of pure boron nitride (BN) nanotubes is reported here. Multi-walled tubes with inner diameters on the order of 1 to 3 nanometers and with lengths up to 200 nanometers were produced in a carbon-free plasma discharge between a BN-packed tungsten rod and a cooled copper electrode. Electron energy-loss spectroscopy on individual tubes yielded B:N ratios of approximately 1, which is consistent with theoretical predictions of stable BN tube structures.

  12. L-Phenylalanine preloading reduces the (10)B(n, α)(7)Li dose to the normal brain by inhibiting the uptake of boronophenylalanine in boron neutron capture therapy for brain tumours.

    PubMed

    Watanabe, Tsubasa; Tanaka, Hiroki; Fukutani, Satoshi; Suzuki, Minoru; Hiraoka, Masahiro; Ono, Koji

    2016-01-01

    Boron neutron capture therapy (BNCT) is a cellular-level particle radiation therapy that combines the selective delivery of boron compounds to tumour tissue with neutron irradiation. Previously, high doses of one of the boron compounds used for BNCT, L-BPA, were found to reduce the boron-derived irradiation dose to the central nervous system. However, injection with a high dose of L-BPA is not feasible in clinical settings. We aimed to find an alternative method to improve the therapeutic efficacy of this therapy. We examined the effects of oral preloading with various analogues of L-BPA in a xenograft tumour model and found that high-dose L-phenylalanine reduced the accumulation of L-BPA in the normal brain relative to tumour tissue. As a result, the maximum irradiation dose in the normal brain was 19.2% lower in the L-phenylalanine group relative to the control group. This study provides a simple strategy to improve the therapeutic efficacy of conventional boron compounds for BNCT for brain tumours and the possibility to widen the indication of BNCT to various kinds of other tumours.

  13. Accumulation and loss of arsenic and boron, alone and in combination, in mallard ducks

    SciTech Connect

    Pendleton, G.W.; Whitworth, M.R.; Olsen, G.H.

    1995-08-01

    Arsenic and boron are common in the environment, and wildlife can be exposed to toxic concentrations through both natural and human-influenced processes. The authors exposed adult male mallard ducks to dietary concentrations of 300 ppm arsenic as sodium arsenate, 1,600 ppm boron as boric acid, or both and estimated the tissue accumulation and loss rates when the ducks were returned to uncontaminated food. Both elements were accumulated rapidly; equilibrium levels were reached for arsenic in 10 to 30 d and for boron in 2 to 15 d. Accumulation of each element was slowed by the presence of the other in the diet. Boron was eliminated by mallards very rapidly, with few detectable residues {ge}1 d after removal of boron from the diet; arsenic was also rapidly lost with half-lives of 1 to 3 d (half-lives were not constant throughout the loss period). Arsenic loss rate was not affected by the presence of boron. Arsenic accumulated to the highest level in liver tissue, with blood and brain levels lower; concentrations in the liver and blood were proportional but affected by the presence of boron. Boron concentrations were highest in the blood, followed by the brain and liver; concentrations in the liver and blood were proportional but affected by the presence of boron. Boron concentrations were highest in the blood, followed by the brain and liver; concentrations in the blood and liver were proportional.

  14. Interstitial-boron solution strengthened WB3+x

    NASA Astrophysics Data System (ADS)

    Cheng, Xiyue; Zhang, Wei; Chen, Xing-Qiu; Niu, Haiyang; Liu, Peitao; Du, Kui; Liu, Gang; Li, Dianzhong; Cheng, Hui-Ming; Ye, Hengqiang; Li, Yiyi

    2013-10-01

    By means of variable-composition evolutionary algorithm coupled with density functional theory and in combination with aberration-corrected high-resolution transmission electron microscopy experiments, we have studied and characterized the composition, structure, and hardness properties of WB3+x (x < 0.5). We provide robust evidence for the occurrence of stoichiometric WB3 and non-stoichiometric WB3+x, both crystallizing in the metastable hP16 (P63/mmc) structure. No signs for the formation of the highly debated WB4 (both hP20 and hP10) phases were found. Our results rationalize the seemingly contradictory high-pressure experimental findings and suggest that the interstitial boron atom is located in the tungsten layer and vertically interconnect with four boron atoms, thus forming a typical three-center boron net with the upper and lower boron layers in a three-dimensional covalent network, which thereby strengthen the hardness.

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

    USGS Publications Warehouse

    Eisler, R.

    1990-01-01

    Ecological and toxicological aspects of boron (B) in the environment are reviewed, with emphasis on natural resources. Subtopics covered include environmental chemistry, background concentrations, effects, and current recommendations for the protection of living resources. Boron is not now considered essential in mammalian nutrition, although low dietary levels protect against fluorosis and bone demineralization. Excessive consumption (i.e., >1,000 mg B/kg diet, >15 mg B/kg body weight daily, >1.0 mg B/L drinking water, or >210 mg B/kg body weight in a single dose) adversely affects growth, survival, or reproduction in sensitive mammals. Boron and its compounds are potent teratogens when applied directly to the mammalian embryo, but there is no evidence of mutagenicity or carcinogenicity. Boron`s unique affinity for cancerous tissues has been exploited in neutron capture radiation therapy of malignant human brain tumors. Current boron criteria recommended for the protection of sensitive species include <0.3 mg B/L in crop irrigation waters, <1.0 mg B/L for aquatic life, <5.0 mg B/L in livestock drinking waters, <30 mg B/kg in waterfowl diets, and <100 mg B/kg in livestock diets.

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

    PubMed

    Bortolussi, S; Altieri, S

    2013-11-01

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

  17. Method of fabricating boron containing coatings

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    1999-01-01

    Hard coatings are fabricated from boron nitride, cubic boron nitride, and multilayer boron/cubic boron nitride, and the fabrication thereof involves magnetron sputtering in a selected atmosphere. These hard coatings may be applied to tools and engine and other parts, as well to reduce wear on tribological surfaces and electronic devices. These boron coatings contain no morphological growth features. For example, the boron is formed in an inert (e.g. argon) atmosphere, while the cubic boron nitride is formed in a reactive (e.g. nitrogen) atmosphere. The multilayer boron/cubic boron nitride, is produced by depositing alternate layers of boron and cubic boron nitride, with the alternate layers having a thickness of 1 nanometer to 1 micrometer, and at least the interfaces of the layers may be discrete or of a blended or graded composition.

  18. Method of fabricating boron containing coatings

    DOEpatents

    Makowiecki, D.M.; Jankowski, A.F.

    1999-04-27

    Hard coatings are fabricated from boron nitride, cubic boron nitride, and multilayer boron/cubic boron nitride, and the fabrication thereof involves magnetron sputtering in a selected atmosphere. These hard coatings may be applied to tools and engine and other parts, as well to reduce wear on tribological surfaces and electronic devices. These boron coatings contain no morphological growth features. For example, the boron is formed in an inert (e.g. argon) atmosphere, while the cubic boron nitride is formed in a reactive (e.g. nitrogen) atmosphere. The multilayer boron/cubic boron nitride, is produced by depositing alternate layers of boron and cubic boron nitride, with the alternate layers having a thickness of 1 nanometer to 1 micrometer, and at least the interfaces of the layers may be discrete or of a blended or graded composition. 3 figs.

  19. Validation of the scanning γ-ray telescope for in vivo dosimetry and boron measurements during BNCT

    NASA Astrophysics Data System (ADS)

    Verbakel, W. F. A. R.

    2001-12-01

    γ-ray telescope scans of a box phantom with inhomogeneous boron concentrations have proven the feasibility of in vivo measurements of different boron distributions in the head of a patient during boron neutron capture therapy (BNCT). Small structures with enhanced boron concentration can be reconstructed in a head phantom, even if the brain compartment of the phantom is surrounded by a skin layer with a ten times higher boron concentration. The motor-controlled telescope can scan the head/phantom, detecting boron and hydrogen prompt γ-rays emitted at neutron capture reactions with a two-dimensional spatial resolution of 14 mm full width at half maximum. For reconstruction of the boron concentrations from the measured γ-ray detection rates, a mathematical reconstruction algorithm is derived and discussed. Proper reconstruction requires position-dependent γ-ray measurements combined with treatment planning programme calculations of the thermal neutron distribution. In a head phantom, in which the brain and the skull (bulk) were represented using a homogeneous boron distribution of 5.2 +/- 0.5 ppm 10B, surrounded by a skin layer with a ten times higher boron concentration, the bulk concentration was reconstructed to 4.7 +/- 0.3 ppm 10B. Telescope scans along and perpendicular to the beam axis showed the influence of inhomogeneities with a high boron concentration such as skin and a simulated blood vessel, respectively with a low boron concentration such as white matter. The profiles of the boron and hydrogen γ-ray detection rates indicate how future patient measurements can be interpreted. In clinical trials, the telescope can then be used to investigate the averaged boron concentration in the bulk of a patient and local enhanced boron concentrations (e.g. in tumour tissue) in order to relate the measured boron dose distributions to the clinical effects of BNCT. Simultaneously, it can serve as quality control of the dosimetry during the irradiation.

  20. Neutron autoradiography to study boron compound microdistribution in an oral cancer model.

    PubMed

    Portu, Agustina; Molinari, Ana Julia; Thorp, Silvia Inés; Pozzi, Emiliano César Cayetano; Curotto, Paula; Schwint, Amanda Elena; Saint Martin, Gisela

    2015-04-01

    We previously reported the therapeutic efficacy of Sequential Boron Neutron Capture Therapy (Seq-BNCT), i.e., BPA (boronophenylalanine) - BNCT followed by GB-10 (decahydrodecaborate) - BNCT 1 or 2 days later, in the hamster cheek pouch oral cancer model. We have utilized the neutron autoradiography methodology to study boron microdistribution in tissue. The aim was to use this method to evaluate if the distribution of GB-10 is altered by prior application of BPA-BNCT in Sequential BNCT protocols. Extensive qualitative and quantitative autoradiography analyses were performed in the following groups: G1 (animals without boron); G2 (animals injected with BPA); G3 (animals injected with GB-10); G4 (same as G3, 24 h after BPA-BNCT); and G5 (same protocol as G4, 48 h interval). A detailed study of boron localization in the different tissue structures of tumor, premalignant and normal tissue in the hamster cheek pouch was performed. GB-10 accumulated preferentially in non-neoplastic connective tissue, whereas for BPA neoplastic cells showed the highest boron concentration. Boron distribution was less heterogeneous for GB-10 than for BPA. In premalignant and normal tissue, GB-10 and BPA accumulated mostly in connective tissue and epithelium, respectively. BPA-BNCT could alter boron microlocalization of GB-10 administered subsequently. Boron targeting homogeneity is essential for therapeutic success.

  1. Understanding Boron through Size-Selected Clusters: Structure, Chemical Bonding, and Fluxionality

    SciTech Connect

    Sergeeva, Alina P.; Popov, Ivan A.; Piazza, Zachary A.; Li, Wei-Li; Romanescu, Constantin; Wang, Lai S.; Boldyrev, Alexander I.

    2014-04-15

    Conspectus Boron is an interesting element with unusual polymorphism. While three-dimensional (3D) structural motifs are prevalent in bulk boron, atomic boron clusters are found to have planar or quasi-planar structures, stabilized by localized two-center–two-electron (2c–2e) σ bonds on the periphery and delocalized multicenter–two-electron (nc–2e) bonds in both σ and π frameworks. Electron delocalization is a result of boron’s electron deficiency and leads to fluxional behavior, which has been observed in B13+ and B19–. A unique capability of the in-plane rotation of the inner atoms against the periphery of the cluster in a chosen direction by employing circularly polarized infrared radiation has been suggested. Such fluxional behaviors in boron clusters are interesting and have been proposed as molecular Wankel motors. The concepts of aromaticity and antiaromaticity have been extended beyond organic chemistry to planar boron clusters. The validity of these concepts in understanding the electronic structures of boron clusters is evident in the striking similarities of the π-systems of planar boron clusters to those of polycyclic aromatic hydrocarbons, such as benzene, naphthalene, coronene, anthracene, or phenanthrene. Chemical bonding models developed for boron clusters not only allowed the rationalization of the stability of boron clusters but also lead to the design of novel metal-centered boron wheels with a record-setting planar coordination number of 10. The unprecedented highly coordinated borometallic molecular wheels provide insights into the interactions between transition metals and boron and expand the frontier of boron chemistry. Another interesting feature discovered through cluster studies is boron transmutation. Even though it is well-known that B–, formed by adding one electron to boron, is isoelectronic to carbon, cluster studies have considerably expanded the possibilities of new structures and new materials using the B

  2. Nondestructive determination of boron doses in semiconductor materials using neutron depth profiling

    SciTech Connect

    Uenlue, K.; Saglam, M.; Wehring, B.W.

    1996-12-31

    The physical and electrical properties of semiconductor materials are greatly effected by implantation of boron and other elements. The dose and depth distribution of boron in the near surface region and across interfacial boundaries determine the quality of semiconductor devices. Therefore, a number of analytical techniques has been developed in the last two decades to measure boron doses and depth profiles in semiconductor materials. Neutron Depth Profiling (NDP) is one of the techniques which is capable of determining the boron dose as well as the concentration distribution in the near surface region of semiconductor materials. NDP is a nuclear technique which is based on the absorption reaction of thermal/cold neutrons by certain isotopes of low mass elements e.g., boron-10. In this study, boron doses in semiconductor materials were measured using NDP. The results will be used to complement the measurements done with other techniques and provide a basis for accurate dose calibration of commercial ion implant systems.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  4. Hydrophobic boron compound-loaded poly(l-lactide-co-glycolide) nanoparticles for boron neutron capture therapy.

    PubMed

    Takeuchi, Issei; Nomura, Kensuke; Makino, Kimiko

    2017-08-04

    Poly(DL-lactide-co-glycolide) (PLGA) has been widely used and studied because of its biocompatibility and biodegradability. Recently, the usefulness of nanoparticles using poly(L-lactide-co-glycolide) (PLLGA) having a higher glass transition temperature than PLGA was suggested. In this study, we investigated the availability of boron compound-loaded PLGA and PLLGA nanoparticles for boron neutron capture therapy (BNCT) by conducting biodistribution study using tumor-bearing mice. o-Carborane, a hydrophobic boron compound, was used as a boron carrier, and o-carborane-albumin conjugate was used as a control. We prepared PLGA and PLLGA nanoparticles with diameters of 100nm and 150nm. In 100-nm PLLGA nanoparticles, the boron concentration in the tumor reached 113.9±15.8μg/g of tissue at 8h after administration. This result indicated that 100-nm PLLGA nanoparticles were able to achieve an intratumoral (10)B concentration of 20μg/g without replacing the (11)B with (10)B. In addition, by nanoparticulation using PLGA7510 and PLLGA7510, intratumoral boron concentration was 1.7-3.2 and 3.5-4.2 times higher than that of the o-carborane-albumin conjugate, respectively. The tumor/blood ratios of boron concentration reached over 5 at 8-12h after injection. Boron atoms in nanoparticles were excreted mainly in the urine, and characteristic accumulation was not observed in other organs. These results suggested that 100-nm PLLGA nanoparticles were particularly useful for BNCT. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. The loss of boron in ultra-shallow boron implanted Si under heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Pelicon, P.; El Bouanani, M.; Prasad, G. V. R.; Razpet, A.; Simcic, J.; Guo, B. N.; Birt, D.; Duggan, J. L.; McDaniel, F. D.

    2006-08-01

    Heavy ion impact has been known to cause a loss of light elements from the near-surface region of the irradiated sample. One of the possible approaches to a better understanding of the processes responsible for the release of specific elements is to irradiate shallow-implanted samples, which exhibit a well-known depth distribution of the implanted species. In this work, the samples studied were produced by implantation of Si wafers with 11 B at implantation energies of 250 and 500 eV and fluence of 1.0x10(15) atoms/cm 2 . Elastic Recoil Detection Analysis was applied to monitor the remnant boron fluence in the sample. Irradiation of the samples by a 14.2 (MeVF4+)-F-19 beam resulted in a slow decrease of boron remnant fluence with initial loss rates of the order of 0.05 B atom per impact ion. Under irradiation with 12 (MeVS3+)-S-32 ions, the remnant boron fluence in Si decreased exponentially with a much faster loss rate of boron and became constant after a certain heavy ion irradiation dose. A simple model, which assumes a finite desorption range and corresponding depletion of the near-surface region, was used to describe the observations. The depletion depths under the given irradiation conditions were calculated from the measured data.

  6. Boron containing multilayer coatings and method of fabrication

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    1997-01-01

    Hard coatings are fabricated from multilayer boron/boron carbide, boron carbide/cubic boron nitride, and boron/boron nitride/boron carbide, and the fabrication thereof involves magnetron sputtering in a selected atmosphere. These hard coatings may be applied to tools and engine and other parts, as well to reduce wear on tribological surfaces and electronic devices. These boron coatings contain no morphological growth features. For example, the boron and boron carbide used in forming the multilayers are formed in an inert (e.g. argon) atmosphere, while the cubic boron nitride is formed in a reactive (e.g. nitrogen) atmosphere. The multilayer boron/boron carbide, and boron carbide/cubic boron nitride is produced by depositing alternate layers of boron, cubic boron nitride or boron carbide, with the alternate layers having a thickness of 1 nanometer to 1 micrometer, and at least the interfaces of the layers may be of a discrete or a blended or graded composition.

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

    PubMed

    Goodarzi, Samereh; Pazirandeh, Ali; Jameie, Seyed Behnamedin; Khojasteh, Nasrin Baghban

    2012-06-01

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

  8. Boron Clusters Come of Age

    ERIC Educational Resources Information Center

    Grimes, Russell N.

    2004-01-01

    Boron is the only element other than carbon that can build molecules of unlimited size by covalently boding to itself, a property known as catenation. In contrast to the chains and rings favored by carbon, boron arguably adopts a cluster motif that is reflected in the various forms of the pure element and in the huge area of polyhedral borane…

  9. Boron Clusters Come of Age

    ERIC Educational Resources Information Center

    Grimes, Russell N.

    2004-01-01

    Boron is the only element other than carbon that can build molecules of unlimited size by covalently boding to itself, a property known as catenation. In contrast to the chains and rings favored by carbon, boron arguably adopts a cluster motif that is reflected in the various forms of the pure element and in the huge area of polyhedral borane…

  10. Optical properties of boron carbide near the boron K edge evaluated by soft-x-ray reflectometry from a Ru/B4C multilayer

    SciTech Connect

    Ksenzov, Dmitriy; Panzner, Tobias; Schlemper, Christoph; Morawe, Christian; Pietsch, Ullrich

    2009-12-10

    Soft-x-ray Bragg reflection from two Ru/B4C multilayers with 10 and 63 periods was used for independent determination of both real and imaginary parts of the refractive index n = 1 -{delta} + i{beta} close to the boron K edge ({approx}188 eV). Prior to soft x-ray measurements, the structural parameters of the multilayers were determined by x-ray reflectometry using hard x rays. For the 63-period sample, the optical properties based on the predictions made for elemental boron major deviations were found close to the K edge of boron for the 10-period sample explained by chemical bonding of boron to B4C and various boron oxides.

  11. Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates

    SciTech Connect

    Vengosh, A. Hebrew Univ., Jerusalem ); Chivas, A.R.; McCulloch, M.T. ); Kolodny, Y.; Starinsky, A. )

    1991-10-01

    The abundances and isotopic composition of boron in modern, biogenic calcareous skeletons from the Gulf of Elat, Israel, the Great Barrier Reef, Australia, and in deep-sea sediments have been examined by negative thermal-ionization mass spectrometry. The selected species (Foraminifera, Pteropoda, corals, Gastropoda, and Pelecypoda) yield large variations in boron concentration that range from 1 ppm in gastropod shells to 80 ppm in corals. The variations of {delta}{sup 11}B may be controlled by isotopic exchange of boron species in which {sup 10}B is preferentially partitioned into the tetrahedral species, and coprecipitation of different proportions of trigonal and tetrahedral species in the calcium carbonates. The B content and {delta}{sup 11}B values of deep-sea sediments, Foraminifera tests, and corals are used to estimate the global oceanic sink of elemental boron by calcium carbonate deposition. As a result of enrichment of B in corals, a substantially higher biogenic sink of 6.4 {plus minus} 0.9 {times} 10{sup 10} g/yr is calculated for carbonates. This is only slightly lower than the sink for desorbable B in marine sediments (10 {times} 10{sup 10} g/yr) and approximately half that of altered oceanic crust (14 {times} 10{sup 10} g/yr). Thus, carbonates are an important sink for B in the oceans being {approximately}20% of the total sinks. The preferential incorporation of {sup 10}B into calcium carbonate results in oceanic {sup 11}B-enrichment, estimated as 1.2 {plus minus} 0.3 {times} 10{sup 12} per mil {center dot} g/yr. The boron-isotope composition of authigenic, well-preserved carbonate skeletons may provide a useful tool to record secular boron-isotope variations in seawater at various times in the geological record.

  12. Graphene-like Two-Dimensional Ionic Boron with Double Dirac Cones at Ambient Condition.

    PubMed

    Ma, Fengxian; Jiao, Yalong; Gao, Guoping; Gu, Yuantong; Bilic, Ante; Chen, Zhongfang; Du, Aijun

    2016-05-11

    Recently, partially ionic boron (γ-B28) has been predicted and observed in pure boron, in bulk phase and controlled by pressure [ Nature 2009 , 457 , 863 ]. By using ab initio evolutionary structure search, we report the prediction of ionic boron at a reduced dimension and ambient pressure, namely, the two-dimensional (2D) ionic boron. This 2D boron structure consists of graphene-like plane and B2 atom pairs with the P6/mmm space group and six atoms in the unit cell and has lower energy than the previously reported α-sheet structure and its analogues. Its dynamical and thermal stability are confirmed by the phonon-spectrum and ab initio molecular dynamics simulation. In addition, this phase exhibits double Dirac cones with massless Dirac Fermions due to the significant charge transfer between the graphene-like plane and B2 pair that enhances the energetic stability of the P6/mmm boron. A Fermi velocity (vf) as high as 2.3 × 10(6) m/s, which is even higher than that of graphene (0.82 × 10(6) m/s), is predicted for the P6/mmm boron. The present work is the first report of the 2D ionic boron at atmospheric pressure. The unique electronic structure renders the 2D ionic boron a promising 2D material for applications in nanoelectronics.

  13. A high boronate avidity monolithic capillary for the selective enrichment of trace glycoproteins.

    PubMed

    Li, Daojin; Li, Yang; Li, Xinglin; Bie, Zijun; Pan, Xianghua; Zhang, Qian; Liu, Zhen

    2015-03-06

    Boronate affinity materials, as effective sample enrichment sorbents for glycoproteomic analysis, have attracted increasing attention in recent years. However, most of boronate affinity materials suffer from an apparent limitation, limited binding strength. As a result, extraction of glycoproteins of trace concentration is rather difficult or impossible. In this study, we present a high boronate avidity monolithic capillary. Branched polyethyleneimine (PEI) was used as a scaffold to amplify the number of boronic acid moieties. While 2,4-difluoro-3-formyl-phenylboronic acid (DFFPBA), which exhibited ultrahigh affinity toward cis-diol-containing compounds, was employed as an affinity ligand. Due to the PEI-assisted synergistic multivalent binding, the monolithic column exhibited high boronate avidity toward glycoproteins, with binding constants of 10(-6)-10(-7)M. Such binding strength was the highest among already reported boronic acid-functionalized materials that can be used for glycoproteomic analysis. Besides, the boronate avidity monolithic column exhibited one additional beneficial feature, lowered binding pH (≥6.5). These features greatly favored the selective enrichment of trace glycoproteins from real samples. The feasibility for practical applications was demonstrated with the selective enrichment of trace glycoproteins in human saliva. As compared with other boronate avidity/affinity materials, the boronate avidity monolithic capillary exhibited the best performance.

  14. Boron enhances strength and alters mineral composition of bone in rabbits fed a high energy diet.

    PubMed

    Hakki, Sema S; Dundar, Niyazi; Kayis, Seyit Ali; Hakki, Erdogan E; Hamurcu, Mehmet; Kerimoglu, Ulku; Baspinar, Nuri; Basoglu, Abdullah; Nielsen, Forrest H

    2013-04-01

    An experiment was performed to determine whether boron had a beneficial effect on bone strength and composition in rabbits with apparent adiposity induced by a high energy diet. Sixty female New Zealand rabbits, aged 8 months, were randomly divided into five groups with the following treatments for seven months: control 1, fed alfalfa hay only (5.91 MJ/kg); control 2, high energy diet (11.76 MJ and 3.88 mg boron/kg); B10, high energy diet+10 mg/kg body weight boron gavage/96 h; B30, high energy diet+30 mg/kg body weight boron gavage/96 h; B50, high energy diet+50mg/kg body weight boron gavage/96 h. Bone boron concentrations were lowest in rabbits fed the high energy diet without boron supplementation, which suggested an inferior boron status. Femur maximum breaking force was highest in the B50 rabbits. Tibia compression strength was highest in B30 and B50 rabbits. All boron treatments significantly increased calcium and magnesium concentrations, and the B30 and B50 treatments increased the phosphorus concentration in tibia of rabbits fed the high energy diet. The B30 treatment significantly increased calcium, phosphorus and magnesium concentrations in femur of rabbits fed the high energy diet. Principal component analysis of the tibia minerals showed that the three boron treatments formed a separate cluster from controls. Discriminant analysis suggested that the concentrations of the minerals in femur could predict boron treatment. The findings indicate boron has beneficial effects on bone strength and mineral composition in rabbits fed a high energy diet. Copyright © 2012 Elsevier GmbH. All rights reserved.

  15. Suppression of oxidation enhanced boron diffusion in silicon by carbon implantation and characterization of MOSFETs with carbon implanted channels

    SciTech Connect

    Ban, I.; Oeztuerk, M.C.; Demirlioglu, E.

    1996-12-31

    Scaling of MOSFETs into the deep submicron regime requires shallow doping profiles with abrupt doping transitions in the MOSFET active region. In NMOS transistors with boron doped channels, oxidation enhanced diffusion is a key contributor to boron profile broadening. Starting from the arguments presented in several recent reports on the role of carbon in silicon as a sink for self-interstitials, we have explored the feasibility of using carbon in the MOSFET in the active region to retard boron diffusion during gate oxidation. MOSFETs with carbon and boron implanted channels have been fabricated. Boron diffusion, activation, and critical electrical parameters such as subthreshold swing, threshold voltage, and off-state leakage current have been evaluated as a function of the carbon dose. We have shown that carbon can effectively suppress boron diffusion during gate oxidation. However, at dose levels around 10{sup 14}cm{sup -2} carbon results in poor boron activation and degradation in MOSFET performance.

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

    PubMed

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

    2006-12-01

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

  17. Functionalized boron nitride nanotubes

    DOEpatents

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  20. METHOD OF COATING SURFACES WITH BORON

    DOEpatents

    Martin, G.R.

    1949-10-11

    A method of forming a thin coating of boron on metallic, glass, or other surfaces is described. The method comprises heating the article to be coated to a temperature of about 550 d C in an evacuated chamber and passing trimethyl boron, triethyl boron, or tripropyl boron in the vapor phase and under reduced pressure into contact with the heated surface causing boron to be deposited in a thin film.

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

    PubMed

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

    2016-11-01

    Boron removal is an arising issue in desalination plants due to boron's toxicity. As an emerging treatment concept, bioelectrochemical systems (BES) can achieve potentially cost-effective boron removal by taking advantage of cathodic-produced alkali. Prior studies have demonstrated successful removal of boron in microbial desalination cells (MDCs) and microbial fuel cells (MFCs), both of which are representative BES. Herein, mathematical models were developed to further evaluate boron removal by different BES and understand the key operating factors. The models delivered very good prediction of the boron concentration in the MDC integrated with Donnan Dialysis (DD) system with the lowest relative root-mean-square error (RMSE) of 0.00%; the predication of the MFC performance generated the highest RMSE of 18.55%. The model results of salt concentration, solution pH, and current generation were well fitted with experimental data for RMSE values mostly below 10%. The long term simulation of the MDC-DD system suggests that the accumulation of salt in the catholyte/stripping solution could have a positive impact on the removal of boron due to osmosis-driven convection. The current generation in the MDC may have little influence on the boron removal, while in the MFC the current-driven electromigration can contribute up to 40% of boron removal. Osmosis-induced convection transport of boron could be the major driving force for boron removal to a low level <2mgL(-1). The ratio between the anolyte and the catholyte flow rates should be kept >22.2 in order to avoid boron accumulation in the anolyte effluent.

  2. Characterization of Boron Diffusion Phenomena According to the Specific Resistivity of N-Type Si Wafer.

    PubMed

    Lee, Woo-Jin; Choi, Chel-Jong; Park, Gye-Choon; Yang, O-Bong

    2016-02-01

    This paper is directed to characterize the boron diffusion process according to the specific resistivity of the Si wafer. N-type Si wafers were used with the specific resistivity of 0.5-3.2 omega-cm, 1.0-6.5 omega-cm and 2.0-8.0 omega-cm. The boron tribromide (BBr3) was used as boron source to create the PN junction on N-type Si wafer. The boron diffusion in N-type Si wafer was characterized by sheet resistance of wafer surface, secondary ion mass spectroscopy measurements (SIMS) and surface life time analysis. The degree of boron diffusion was depended on the variation in specific resistivity and sheet resistance of the bare N-type Si wafer. The boron diffused N-Si wafer exhibited the average junction depth of 750 nm and boron concentration of 1 x 10(19). N-type Si wafer with the different specific resistance considerably affected the boron diffusion length and life time of Si wafer. It was found that the lifetime of boron diffused wafer was proportional to the sheet resistance and resistivity. However, optimization process may necessary to achieve the high efficiency through the high sheet resistance wafer, because the metallization process control is very sensitive.

  3. Synthesis and Raman Characterization of Boron Doped Single Walled Carbon Nanotubes (SWNTs)

    NASA Astrophysics Data System (ADS)

    McGuire, K.; Gothard, N.; Gai, P. L.; Chao, S. G.; Dresselhaus, M. S.; Rao, A. M.

    2003-11-01

    Boron-doped SWNTs were prepared by pulsed laser vaporization of carbon targets containing boron with concentrations ranging between 0.5 - 10 at%. As-prepared samples were characterized using Raman spectroscopy and HRTEM measurements. Above a threshold boron concentration of 3 at%, the growth of SWNT bundles ceases due to the low solubility of boron in carbon at ˜1200 ^oC. Interestingly, a few ˜0.5 nm diameter single walled tubes are found, along with nanographitic material in the soot generated from a target with a boron concentration of ˜7 at%. As expected, the intensity of the ˜1350 cm-1 D-band increases with increasing boron concentration due to boron substitution into the honeycomb lattice. Both the radial breathing mode and tangential G- bands were observed in the Raman spectra in samples with <3 at % boron at ˜186 cm-1 and ˜1591 cm-1, respectively. Implications of boron doping in the nanotube shell will be discussed.

  4. Synthesis and Raman Characterization of Boron Doped Single Walled Carbon Nanotubes (SWNTs)

    NASA Astrophysics Data System (ADS)

    McGuire, K.; Gothard, N.; Gai, P. L.; Chou, S. G.; Dresselhaus, M. S.; Rao, A. M.

    2003-03-01

    Boron-doped SWNTs were prepared by pulsed laser vaporization of carbon targets containing boron with concentrations ranging between 0.5 - 10 at%. As-prepared samples were characterized using Raman spectroscopy and HRTEM measurements. Above a threshold boron concentration of 3 at%, the growth of SWNT bundles ceases due to the low solubility of boron in carbon at ˜1200 ^oC. Interestingly, a few ˜0.5 nm diameter single walled tubes are found, along with nanographitic material in the soot generated from a target with a boron concentration of ˜7 at%. As expected, the intensity of the ˜1350 cm-1 D-band increases with increasing boron concentration due to boron substitution into the honeycomb lattice. Both the radial breathing mode and tangential G- bands were observed in the Raman spectra in samples with <3 at % boron at ˜186 cm-1 and ˜1591 cm-1, respectively. Implications of boron doping in the nanotube shell will be discussed.

  5. Functional characterization of Citrus macrophylla BOR1 as a boron transporter.

    PubMed

    Cañon, Paola; Aquea, Felipe; Rodríguez-Hoces de la Guardia, Amparo; Arce-Johnson, Patricio

    2013-11-01

    Plants have evolved to develop an efficient system of boron uptake and transport using a range of efflux carriers named BOR proteins. In this work we isolated and characterized a boron transporter of citrus (Citrus macrophylla), which was named CmBOR1 for its high homology to AtBOR1. CmBOR1 has 4403 bp and 12 exons. Its coding region has 2145 bp and encodes for a protein of 714 amino acids. CmBOR1 possesses the molecular features of BORs such as an anion exchanger domain and the presence of 10 transmembrane domains. Functional analysis in yeast indicated that CmBOR1 has an efflux boron transporter activity, and transformants have increased tolerance to excess boron. CmBOR1 is expressed in leaves, stem and flowers and shows the greatest accumulation in roots. The transcript accumulation was significantly increased under boron deficiency conditions in shoots. In contrast, the accumulation of the transcript did not change in boron toxicity conditions. Finally, we observed that constitutive expression of CmBOR1 was able to increase tolerance to boron deficiency conditions in Arabidopsis thaliana, suggesting that CmBOR1 is a xylem loading boron transporter. Based on these results, it was determined that CmBOR1 encodes a boric acid/borate transporter involved in tolerance to boron deficiency in plants.

  6. [Boron neutron capture therapy of human gastric cancer by boron-containing immunoliposomes under thermal neutron irradiation].

    PubMed

    Xu, L

    1991-10-01

    Boron neutron capture therapy (BNCT) is based on the nuclear reaction yielding high LET Li-7 and alpha particles when boron-10 is irradiated with thermal neutrons. (Et4N)2(10)B10H10 was entrapped in 40 nm liposomes coating the monoclonal antibody, MGb 2, against human gastric cancer. There were 1.4 x 10(4) 10B atoms encapsulated and 20 molecules of MGb 2 incorporated per liposomes ELISA indicated that the immunoreactivity of antibodies on liposomes retained 80%. Preferred binding to human gastric cancer cell line SGC-7901 was observed as many as 15.1 x 10(9) 10B atoms/tumor cell, 38-fold more than that to normal human embryonic lung cell line SL 7. The fluorescent immunoliposome-stained tumor cells showed membrane-fluorescence while SL 7 cells showed no obvious fluorescence. Irradiated with thermal neutrons (0.025 eV, 3.12 x 10(11)n/cm2, gamma-ray 0.84 Gy), 10B-containing immunoliposomes pretreated SGC-7901 cells survived 27%, significantly lower than non-irradiated cells or non-pretreated cells with irradiation (P less than 0.001). The results demonstrated that boron-containing immunoliposomes could bind selectively and deliver sufficient amount of boron-10 to the target tumor cells.

  7. Boron transient enhanced diffusion in heavily phosphorus doped silicon

    SciTech Connect

    Huang, M.B.; Myler, U.; Simpson, T.W.; Simpson, P.J.; Mitchell, I.V.

    1997-11-01

    A study has been made of B transient enhanced diffusion (TED) in heavily P-doped Si using secondary ion mass spectroscopy (SIMS) and positron annihilation spectroscopy (PAS). The P-doped silicon was implanted with boron ions of 40 keV energy to a dose of 3 {times} 10{sup 14} cm{sup {minus}2}, and then annealed at temperatures ranging from 700--1,000 C in a N{sub 2} ambient for varying durations. As P doping concentration increased from 3 {times} 10{sup 19} to 1 {times} 10{sup 20} cm{sup {minus}3}, boron diffusivity and the immobile boron fraction decreased. The experimental results are inconsistent with the predictions of the Fermi-level model and suggest that the clustering between B atoms and Si interstitials should be invoked in order to explain the immobile portion of the B peak during TED.

  8. Pairwise cobalt doping of boron carbides with cobaltocene

    SciTech Connect

    Ignatov, A. Yu.; Losovyj, Ya. B.; Carlson, L.; LaGraffe, D.; Brand, J. I.; Dowben, P. A.

    2007-10-15

    We have performed Co K-edge x-ray absorption fine structure and x-ray absorption near edge structure measurements of Co-doped plasma enhanced chemical vapor phase deposition (PECVD) grown 'C{sub 2}B{sub 10}H{sub x}' semiconducting boron carbides, using cobaltocene. Cobalt does not dope PECVD grown boron carbides as a random fragment of the cobaltocene source gas. The Co atoms are fivefold boron coordinated (R=2.10{+-}0.02 A) and are chemically bonded to the icosahedral cages of B{sub 10}CH{sub x} or B{sub 9}C{sub 2}H{sub y}. Pairwise Co doping occurs, with the cobalt atoms favoring sites some 5.28{+-}0.02 A apart.

  9. Modeling of Boron and Phosphorus Implantation into (100) Germanium

    SciTech Connect

    Suh,Y.; Carroll, M.; Levy, R.; Sahiner, M.; Bisognin, G.; King, C.

    2005-01-01

    Boron and phosphorus implants into germanium and silicon with energies from 20 to 320 keV and ion doses from 5x10{sup 13} to 5x10{sup 16} cm{sup -2} were characterized using secondary ion mass spectrometry. The first four moments of all implants were calculated from the experimental data. Both the phosphorus and boron implants were found to be shallower in the germanium than in the silicon for the same implant parameters and high hole concentrations, as high as 2x10{sup 20} cm{sup -3}, were detected by spreading resistance profiling immediately after boron implants without subsequent annealing. Channeling experiments using nuclear reaction analysis also indicated high substitutional fractions ({approx}19%) even in the highest dose case immediately after implant. A greater straggle (second moment) is, however, observed in the boron implants in the germanium than in the silicon despite having a shorter projected range in the germanium. Implant profiles predicted by Monte Carlo simulations and Lindhard-Scharff-Schiott theory were calculated to help clarify the implant behavior. Finally, the experimentally obtained moments were used to calculate Pearson distribution fits to the boron and phosphorus implants for rapid simulation of nonamorphizing doses over the entire energy range examined.

  10. 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

    PubMed Central

    2009-01-01

    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. PMID:20596476

  11. 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.

    PubMed

    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.

  12. 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

    NASA Astrophysics Data System (ADS)

    Ciofani, Gianni; Raffa, Vittoria; Menciassi, Arianna; Cuschieri, Alfred

    2009-02-01

    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 10B 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.

  13. Entropy of gaseous boron monobromide

    NASA Astrophysics Data System (ADS)

    Wang, Jian-Feng; Peng, Xiao-Long; Zhang, Lie-Hui; Wang, Chao-Wen; Jia, Chun-Sheng

    2017-10-01

    We present an explicit representation of molar entropy for gaseous boron monobromide in terms of experimental values of only three molecular constants. Fortunately, through comparison of theoretically calculated results and experimental data, we find that the molar entropy of gaseous boron monobromide can be well predicted by employing the improved Manning-Rosen oscillator to describe the internal vibration of boron monobromide molecule. The present approach provides also opportunities for theoretical predictions of molar entropy for other gases with no use of large amounts of experimental spectroscopy data.

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

    PubMed

    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.

  15. Boron and Boron-Rich Solids at High Pressures

    NASA Astrophysics Data System (ADS)

    Polian, Alain; Ovsyannikov, Sergey V.; Gauthier, Michel; Munsch, Pascal; Chervin, Jean-Claude; Lemarchand, Gilles

    Boron seems to be the indispensable ingredient to obtain materials with high hardness. It exists under many different structures. The simplest member of the family, α-boron is based on an arrangement of slightly distorted B12 icosahedra in a rhombohedral unit cell. B12X2 compounds, with X = O, P, As, are based on the α-boron structure, with the X atoms in the inter-icosahedra space. The stability of α-boron has been studied by x-ray diffraction and Raman scattering up to 100 GPa, showing no sign of phase transformation, and by Raman scattering for B12P2 and B12As2 with the observation of phase transformation in the 80 GPa range.

  16. Development and validation of non-aqueous capillary electrophoresis methods to analyze boronic esters and acids.

    PubMed

    Forst, Mindy B; Warner, Anne M

    2012-05-01

    the development of methodology to determine residual levels of boronic acids in the corresponding boronic ester. Using the ten boronic ester and acid pairs, eight of the ten pairs were shown to have acceptable sensitivity (S/N of 10 or better at 0.5%) and spike recoveries (within the range of 80-120%). The potential for hydrolysis during analysis was also addressed by using a subset of the ten boronic ester and acid pairs and spiking water into the diluent. There was no observed conversion of the ester to the acid. The lack of hydrolysis during analysis and the high success in separating and validating these methods for the boronic ester and acid pairs supports the utility of NACE as a technique for the analysis of boronic esters and acids.

  17. Boron isotope geochemistry of the oceanic crust from DSDP/ODP Hole 504B

    SciTech Connect

    Ishikawa, Tsuyoshi; Nakamura, Eizo )

    1992-04-01

    Boron contents and boron isotopic compositions were determined for the uppermost 1.3 km section of typical 6.2 Ma oceanic crust from DSDP/ODP Hole 504B, Costa Rica Rift, Galapagos Spreading Center. Both the boron content and the {delta}{sup 11}B value in the oceanic crust are controlled by two types of alteration: (1) low-temperature alteration (0 to 60C; Zones 1 and 2) and (2) high-temperature hydrothermal alteration (200 to 400C; Zones 3 and 4). Basalts subjected to the low-temperature alteration are characterized by their relatively high boron contents (0.69 to 19.3 ppm) and high {delta}{sup 11}B values (+2.2 to +10.6{per thousand}), indicating uptake of boron into secondary phases in equilibrium with seawater or evolved seawater. Hydrothermally altered basalts contain less abundant boron (0.17 to 0.52 ppm) and relatively constant {delta}{sup 11}B values ({minus}0.1 to +1.0{per thousand}). Although basalts from the upper part of these hydrothermal zones (< 1,300 mbsf) show equilibrated boron content and {delta}{sup 11}B value with aqueous fluid, effective leaching of boron from basalt is predominant in the lower part (> 1,300 mbsf). Original boron content and {delta}{sup 11}B value of the Hole 504B MORB were 0.35 ppm and +0.2{per thousand}, respectively. The present data provide fundamental information in understanding of the distribution of boron and boron isotopes in the oceanic crust.

  18. Copper passivation of boron in silicon and boron reactivation kinetics

    NASA Astrophysics Data System (ADS)

    Aboelfotoh, M. O.; Svensson, B. G.

    1991-12-01

    Copper passivation of substitutional boron in single-crystal silicon and the reactivation kinetics of the passivated boron have been investigated with the use of Schottky-barrier structures formed by the deposition of copper on boron-doped silicon at room temperature. It is found that passivation of the boron acceptors occurs after copper deposition. The results suggest that the fast-diffusing interstitial Cu+ passivates the boron acceptors by forming neutral B-Cu complexes, rather than by direct compensation. No compensating donor levels associated with Cu are observed. These results are consistent with recent theoretical predictions. The reactivation kinetics are first order with an activation energy of 0.89 eV, and the annealing process is found to be controlled by long-range diffusion, rather than by pure dissociation. The thermal dissociation of the B-Cu complexes is driven by the formation of the copper silicide η'-Cu3Si, indicating the importance of silicide formation in the reactivation of the boron acceptors.

  19. Compositions for boron delivery to mammalian tissue

    DOEpatents

    Hawthorne, M. Frederick; Feaks, Debra Arlene; Shelly, Kenneth John

    2001-01-01

    Boron neutron capture therapy can utilize X.sub.y B.sub.20 H.sub.17 L where X is an alkali metal, y is 1 to 4, and L is a two electron donor such as NH.sub.3, and Na.sub.2 B.sub.10 H.sub.9 NCO, among others. These borane salts may be used free or encapsulated in liposomes. Liposomes may also have embedded within their bilayers carboranes to increase the amount of delivered .sup.10 B and/or to increase the tumor specificity of the liposome.

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

    PubMed

    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.

  1. Subcellular boron and fluorine distributions with SIMS ion microscopy in BNCT and cancer research

    SciTech Connect

    Subhash Chandra

    2008-05-30

    The development of a secondary ion mass spectrometry (SIMS) based technique of Ion Microscopy in boron neutron capture therapy (BNCT) was the main goal of this project, so that one can study the subcellular location of boron-10 atoms and their partitioning between the normal and cancerous tissue. This information is fundamental for the screening of boronated drugs appropriate for neutron capture therapy of cancer. Our studies at Cornell concentrated mainly on studies of glioblastoma multiforme (GBM). The early years of the grant were dedicated to the development of cryogenic methods and correlative microscopic approaches so that a reliable subcellular analysis of boron-10 atoms can be made with SIMS. In later years SIMS was applied to animal models and human tissues of GBM for studying the efficacy of potential boronated agents in BNCT. Under this grant the SIMS program at Cornell attained a new level of excellence and collaborative SIMS studies were published with leading BNCT researchers in the U.S.

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

    SciTech Connect

    Torigoe, Kazuhisa Fujise, Jun; Ono, Toshiaki; Nakamura, Kozo

    2014-11-21

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

  3. Reducing Boron Toxicity by Microbial Sequestration

    SciTech Connect

    Hazen, T.; Phelps, T.J.

    2002-01-01

    While electricity is a clean source of energy, methods of electricity-production, such as the use of coal-fired power plants, often result in significant environmental damage. Coal-fired electrical power plants produce air pollution, while contaminating ground water and soils by build-up of boron, which enters surrounding areas through leachate. Increasingly high levels of boron in soils eventually overcome boron tolerance levels in plants and trees, resulting in toxicity. Formation of insoluble boron precipitates, mediated by mineral-precipitating bacteria, may sequester boron into more stable forms that are less available and toxic to vegetation. Results have provided evidence of microbially-facilitated sequestration of boron into insoluble mineral precipitates. Analyses of water samples taken from ponds with high boron concentrations showed that algae present contained 3-5 times more boron than contained in the water in the samples. Boron sequestration may also be facilitated by the incorporation of boron within algal cells. Experiments examining boron sequestration by algae are in progress. In bacterial experiments with added ferric citrate, the reduction of iron by the bacteria resulted in an ironcarbonate precipitate containing boron. An apparent color change showing the reduction of amorphous iron, as well as the precipitation of boron with iron, was more favorable at higher pH. Analysis of precipitates by X-ray diffraction, scanning electron microscopy, and inductively coupled plasma mass spectroscopy revealed mineralogical composition and biologicallymediated accumulation of boron precipitates in test-tube experiments.

  4. Boron hazards to fish, wildlife, and invertebrates: A synoptic review

    SciTech Connect

    Eisler, R.

    1990-04-01

    Ecological and toxicological aspects of boron (B) in the environment are reviewed, with emphasis on natural resources. Subtopics covered include environmental chemistry, background concentrations, effects, and current recommendations for the protection of living resources. Boron is not now considered essential in mammalian nutrition, although low dietary levels protect against fluorosis and bone demineralization. Excessive consumption (i.e., >1,000 mg B/kg diet, >15 mg B/kg body weight daily, >1.0 mg B/L drinking water, or >210 mg B/kg body weight in a single dose) adversely affects growth, survival, or reproduction in sensitive mammals. Boron and its compounds are potent teratogens when applied directly to the mammalian embryo, but there is no evidence of mutagenicity or carcinogenicity. Boron's unique affinity for cancerous tissues has been exploited in neutron capture radiation therapy of malignant human brain tumors. Current boron criteria recommended for the protection of sensitive species include <0.3 mg B/L in crop irrigation waters, <1.0 mg B/L for aquatic life, <5.0 mg B/L in livestock drinking waters, <30 mg B/kg in waterfowl diets, and <100 mg B/kg in livestock diets.

  5. Molecular medicine: Synthesis and in-vivo detection of agents for use in boron neutron capture therapy. Final report, May 1, 1993--April 30, 1996

    SciTech Connect

    Kabalka, G.W.

    1997-08-01

    During the early stages of this project, the author developed the first whole-body boron MRI technique. They found that, for the first time, information concerning both the location and the quantity of boron present in living tissues could be obtained through the use of magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) respectively. However, it was also discovered that boron MRI was not without problems. Both naturally occurring isotopes of boron (boron-10 and boron-11) possess magnetic moments, making them amenable to MR detection. The author found that there are difficulties in obtaining boron MRI images which are a consequence of the inherently poor magnetic resonance characteristics of the boron nucleus. The magnetogyric ratios of both boron-10 and boron-11 are smaller than those of hydrogen, which makes boron much less sensitive to magnetic resonance detection. In addition, both isotopes of boron posses nuclear electric quadrupole moments which serve to shorten their magnetization relaxation times; this causes the MR signal to broaden and decay rapidly, often before the receiver coils can collect the MR information. The rapid rate of signal decay is enhanced in biological systems which leads to further signal loss and a decrease in the signal to noise ratio (SNR).

  6. Nano boron nitride flatland.

    PubMed

    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.

  7. Biodistribution of boronophenylalanine in patients with glioblastoma multiforme: boron concentration correlates with tumor cellularity.

    PubMed

    Coderre, J A; Chanana, A D; Joel, D D; Elowitz, E H; Micca, P L; Nawrocky, M M; Chadha, M; Gebbers, J O; Shady, M; Peress, N S; Slatkin, D N

    1998-02-01

    Boron-10 (10B) concentrations were measured in 107 surgical samples from 15 patients with glioblastoma multiforme who were infused with 95 atom% 10B-enriched p-boronophenylalanine (BPA) intravenously for 2 h just prior to surgery at doses ranging from 98 to 290 mg BPA/kg body weight. The blood 10B concentration reached a maximum at the end of the infusion (ranging from 9.3 to 26.0 microg 10B/g) and was proportional to the amount of BPA infused. The boron concentrations in excised tumor samples ranged from 2.7 to 41.3 microg 10B/g over the range of administered BPA doses and varied considerably among multiple samples from individual patients and among patients at the same BPA dose. A morphometric index of the density of viable-appearing tumor cells in histological sections obtained from samples adjacent to, and macroscopically similar to, the tumor samples used for boron analysis correlated linearly with the boron concentrations. From that correlation it is estimated that 10B concentrations in glioblastoma tumor cells were over four times greater than concurrent blood 10B concentrations. Thus, in the dose range of 98 to 290 mg BPA/kg, the accumulation of boron in tumor cells is a linear function of BPA dose and the variations observed in boron concentrations of tumor specimens obtained surgically are largely due to differences in the proportion of nontumor tissue (i.e. necrotic tissue, normal brain) present in the samples submitted for boron analysis. The tumor:blood 10B concentration ratio derived from this analysis provides a rationale for estimating the fraction of the radiation dose to viable tumor cells resulting from the boron neutron capture reaction based on measured boron concentrations in the blood at the time of BNCT without the need for analysis of tumor samples from individual patients.

  8. Boron diffusion in silicon devices

    DOEpatents

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

    2010-09-07

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

  9. Characterization of electrodeposited elemental boron

    SciTech Connect

    Jain, Ashish; Anthonysamy, S. Ananthasivan, K.; Ranganathan, R.; Mittal, Vinit; Narasimhan, S.V.; Vasudeva Rao, P.R.

    2008-07-15

    Elemental boron was produced through electrowinning from potassium fluoroborate dissolved in a mixture of molten potassium fluoride and potassium chloride. The characteristics of the electrodeposited boron (raw boron) as well as the water and acid-leached product (processed boron) were studied. The chemical purity, specific surface area, size distribution of particles and X-ray crystallite size of the boron powders were investigated. The morphology of the deposits was examined using scanning electron microscopy (SEM). The chemical state of the matrix, as well as the impurity phases present in them, was established using X-ray photoelectron spectroscopy (XPS). In order to interpret and understand the results obtained, a thermodynamic analysis was carried out. The gas-phase corrosion in the head space as well as the chemistry behind the leaching process were interpreted using this analysis. The ease of oxidation of these powders in air was investigated using differential thermal analysis (DTA) coupled with thermogravimetry (TG). From the results obtained in this study it was established that elemental boron powder with a purity of 95-99% could be produced using a high temperature molten salt electrowinning process. The major impurities were found to be oxygen, carbon, iron and nickel.

  10. Dietary boron and hormone replacement therapy as risk factors for lung cancer in women.

    PubMed

    Mahabir, S; Spitz, M R; Barrera, S L; Dong, Y Q; Eastham, C; Forman, M R

    2008-05-01

    Hormone replacement therapy (HRT) may reduce lung cancer risk. Dietary boron may have actions similar to those of HRT; however, no previous study has reported the associations between dietary boron intake and lung cancer risk or the joint effects of boron intake and HRT use on lung cancer risk. The authors examined the associations between boron intake and the joint effects of boron intake and HRT on lung cancer risk in women. In an ongoing case-control study in Houston, Texas (July 1995 through April 2005, end date for this analysis), 763 women were diagnosed with lung cancer, and 838 were matched healthy controls with data on both diet and HRT. Multiple logistic regression analyses were conducted to assess the associations between dietary boron and HRT with lung cancer risk. After adjustment for potential confounders, the odds ratios for lung cancer with decreasing quartiles of dietary boron intake were 1.0, 1.39 (95% confidence interval (CI): 1.02, 1.90), 1.64 (95% CI: 1.20, 2.24), and 1.95 (95% CI: 1.42, 2.68) mg/day, respectively, for all women (p(trend) < 0.0001). In joint-effects analyses, compared with women with high dietary boron intake who used HRT, the odds ratio for lung cancer for low dietary boron intake and no HRT use was 2.07 (95% CI: 1.53, 2.81). Boron intake was inversely associated with lung cancer in women, whereas women who consumed low boron and did not use HRT were at substantial increased odds.

  11. Dietary Boron and Hormone Replacement Therapy as Risk Factors for Lung Cancer in Women

    PubMed Central

    Mahabir, S.; Spitz, M. R.; Barrera, S. L.; Dong, Y. Q.; Eastham, C.; Forman, M. R.

    2012-01-01

    Hormone replacement therapy (HRT) may reduce lung cancer risk. Dietary boron may have actions similar to those of HRT; however, no previous study has reported the associations between dietary boron intake and lung cancer risk or the joint effects of boron intake and HRT use on lung cancer risk. The authors examined the associations between boron intake and the joint effects of boron intake and HRT on lung cancer risk in women. In an ongoing case-control study in Houston, Texas (July 1995 through April 2005, end date for this analysis), 763 women were diagnosed with lung cancer, and 838 were matched healthy controls with data on both diet and HRT. Multiple logistic regression analyses were conducted to assess the associations between dietary boron and HRT with lung cancer risk. After adjustment for potential confounders, the odds ratios for lung cancer with decreasing quartiles of dietary boron intake were 1.0, 1.39 (95% confidence interval (CI): 1.02, 1.90), 1.64 (95% CI: 1.20, 2.24), and 1.95 (95% CI: 1.42, 2.68) mg/day, respectively, for all women (ptrend < 0.0001). In joint-effects analyses, compared with women with high dietary boron intake who used HRT, the odds ratio for lung cancer for low dietary boron intake and no HRT use was 2.07 (95% CI: 1.53, 2.81). Boron intake was inversely associated with lung cancer in women, whereas women who consumed low boron and did not use HRT were at substantial increased odds. PMID:18343880

  12. Amorphous boron nanorod as an anode material for lithium-ion batteries at room temperature.

    PubMed

    Deng, Changjian; Lau, Miu Lun; Barkholtz, Heather M; Xu, Haiping; Parrish, Riley; Xu, Meiyue Olivia; Xu, Tao; Liu, Yuzi; Wang, Hao; Connell, Justin G; Smith, Kassiopeia A; Xiong, Hui

    2017-08-03

    We report an amorphous boron nanorod anode material for lithium-ion batteries prepared through smelting non-toxic boron oxide in liquid lithium. Boron in theory can provide capacity as high as 3099 mA h g(-1) by alloying with Li to form B4Li5. However, experimental studies of the boron anode have been rarely reported for room temperature lithium-ion batteries. Among the reported studies the electrochemical activity and cycling performance of the bulk crystalline boron anode material are poor at room temperature. In this work, we utilized an amorphous nanostructured one-dimensional (1D) boron material aiming at improving the electrochemical reactivity between boron and lithium ions at room temperature. The amorphous boron nanorod anode exhibited, at room temperature, a reversible capacity of 170 mA h g(-1) at a current rate of 10 mA g(-1) between 0.01 and 2 V. The anode also demonstrated good rate capability and cycling stability. The lithium storage mechanism was investigated by both sweep voltammetry measurements and galvanostatic intermittent titration techniques (GITTs). The sweep voltammetric analysis suggested that the contributions from lithium ion diffusion into boron and the capacitive process to the overall lithium charge storage are 57% and 43%, respectively. The results from GITT indicated that the discharge capacity at higher potentials (>∼0.2 V vs. Li/Li(+)) could be ascribed to a capacitive process and at lower potentials (<∼0.2 V vs. Li/Li(+)) to diffusion-controlled alloying reactions. Solid state nuclear magnetic resonance (NMR) measurement further confirmed that the capacity is from electrochemical reactions between lithium ions and the amorphous boron nanorod. This work provides new insights into designing nanostructured boron materials for lithium-ion batteries.

  13. Experimental measurement of boron isotope fractionation in seawater

    NASA Astrophysics Data System (ADS)

    Klochko, Kateryna; Kaufman, Alan J.; Yao, Wengsheng; Byrne, Robert H.; Tossell, John A.

    2006-08-01

    The boron isotopic composition of marine carbonates is considered to be a tracer of seawater pH. Use of this proxy benefits from an intimate understanding of chemical kinetics and thermodynamic isotope exchange reactions between the two dominant boron-bearing species in seawater: boric acid B(OH) 3 and borate ion B(OH) 4-. However, because of our inability to quantitatively separate these species in solution, the degree of boron isotope exchange has only been known through theoretical estimates. In this study, we present results of a spectrophotometric procedure wherein the boron isotope equilibrium constant ( 11-10KB) is determined empirically from the difference in the dissociation constants of 11B(OH) 3 and 10B(OH) 3 in pure water, 0.6 mol kg - 1 H 2O KCl and artificial seawater. Within experimental uncertainty, our results show no dependence of 11-10KB on temperature, but 11-10KB at 25 °C in pure water was statistically different than results obtained in solutions at high ionic strength. 11-10KB of the seawater ( S = 35, B T = 0.01 mol kg - 1 H 2O) at 25 °C is 1.0272 ± 0.0006. This result is significantly larger than the theoretical value used in numerous paleo-pH studies ( 11-10KB = 1.0194).

  14. Influence of Boron Substitution on the Crystal and Electronic Properties of LiCrO2 Battery Cathode

    NASA Astrophysics Data System (ADS)

    Ozkendir, Osman Murat; Ates, Sule; Celik, Gultekin; Klysubun, Wantana

    2017-06-01

    Boron-substituted LiCrO2 battery cathode material samples were investigated by X-ray-based techniques to probe the influence of boron on their crystal and electronic structure properties. Studies were carried on a series of Li-ion battery cathode materials with the general formula LiCr1- x B x O2. Up to 10 pct boron substitution amounts, light boron atoms were determined to sit in Cr coordinations. However, for more substitutions (>10 pct), higher electronegativity of boron was determined to govern the crystal structure by obtaining isolated boron-centered domains and built Li2BO4 structures. Electronic structure studies and further crystal structure analysis were carried by X-ray absorption fine structure technique. In the studied samples, increasing boron concentration in the samples ( i.e., >10 pct substitution) were determined to cause a decrease in oxygen bond distances as a result of boron sitting in some chromium locations. As a result of this study, 10 pct boron substitution was determined as a threshold to protect the LiCrO2 crystal structure.

  15. In vitro determination of uptake, retention, distribution, biological efficacy, and toxicity of boronated compounds for neutron capture therapy: a comparison of porphyrins with sulfhydryl boron hydrides.

    PubMed

    Fairchild, R G; Kahl, S B; Laster, B H; Kalef-Ezra, J; Popenoe, E A

    1990-08-15

    A major problem remaining in the evaluation of boronated compounds for neutron capture therapy (NCT) is the need to know the intra- or extracellular microdistribution of boron. This is a consequence of the short range of the 10B(n,alpha)7Li reaction products (approximately 10 microns), such that biological efficacy is dependent upon intracellular distribution. In particular, if boron location is predominantly extracellular, a significant reduction in efficacy would be expected. The in vitro procedure described here was developed mainly to provide information regarding the intra- and extracellular location and concentration of boron. However, use of the technique also allows the measurement of compound uptake and retention (binding) and the determination of biological efficacy by the evaluation of survival curves obtained following irradiation with thermal neutrons. Comparison is made to results obtained with boric acid (H3(10)BO3) and to results calculated for various boron distributions. Concomitantly, an indication of compound toxicity can be obtained from the plating efficiency of unirradiated control cells. Currently, most investigators utilize in vivo systems for testing and evaluating boron uptake from various carrier molecules. Given the large number of boron compounds being synthesized and needing evaluation as to their usefulness for NCT, the in vitro technique described here is simple and advantageous for initial compound screening. In addition to sparing animal lives, it is both time and cost effective and utilizes much smaller quantities of test compound than are required for an in vivo assay. A boronated porphyrin (BOPP) evaluated by the above procedure shows an uptake and retention approximately 20 times that of sulfhydryl boron hydride monomer (BSH); the latter compound is currently being used clinically for NCT in Japan and is anticipated for use in clinical trials in the United States. If the advantages demonstrated by BOPP in these in vitro

  16. The relationship of blood- and urine-boron to boron exposure in borax-workers and usefulness of urine-boron as an exposure marker.

    PubMed Central

    Culver, B D; Shen, P T; Taylor, T H; Lee-Feldstein, A; Anton-Culver, H; Strong, P L

    1994-01-01

    Daily dietary-boron intake and on-the-job inspired boron were compared with blood- and urine-boron concentrations in workers engaged in packaging and shipping borax. Fourteen workers handling borax at jobs of low, medium, and high dust exposures were sampled throughout full shifts for 5 consecutive days each. Airborne borax concentrations ranged from means of 3.3 mg/m3 to 18 mg/m3, measured gravimetrically. End-of-shift mean blood-boron concentrations ranged from 0.11 to 0.26 microgram/g; end-of-shift mean urine concentrations ranged from 3.16 to 10.72 micrograms/mg creatinine. Creatinine measures were used to adjust for differences in urine-specific gravity such that 1 ml of urine contains approximately 1 mg creatinine. There was no progressive increase in end-of-shift blood- or urine-boron concentrations across the days of the week. Urine testing done at the end of the work shift gave a somewhat better estimate of borate exposure than did blood testing, was sampled more easily, and was analytically less difficult to perform. Personal air samplers of two types were used: one, the 37-mm closed-face, two-piece cassette to estimate total dust and the other, the Institute of Occupational Medicine (IOM) sampler to estimate inspirable particulate mass. Under the conditions of this study, the IOM air sampler more nearly estimated human exposure as measured by blood- and urine-boron levels than did the sampler that measured total dust.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7889874

  17. The relationship of blood- and urine-boron to boron exposure in borax-workers and usefulness of urine-boron as an exposure marker.

    PubMed

    Culver, B D; Shen, P T; Taylor, T H; Lee-Feldstein, A; Anton-Culver, H; Strong, P L

    1994-11-01

    Daily dietary-boron intake and on-the-job inspired boron were compared with blood- and urine-boron concentrations in workers engaged in packaging and shipping borax. Fourteen workers handling borax at jobs of low, medium, and high dust exposures were sampled throughout full shifts for 5 consecutive days each. Airborne borax concentrations ranged from means of 3.3 mg/m3 to 18 mg/m3, measured gravimetrically. End-of-shift mean blood-boron concentrations ranged from 0.11 to 0.26 microgram/g; end-of-shift mean urine concentrations ranged from 3.16 to 10.72 micrograms/mg creatinine. Creatinine measures were used to adjust for differences in urine-specific gravity such that 1 ml of urine contains approximately 1 mg creatinine. There was no progressive increase in end-of-shift blood- or urine-boron concentrations across the days of the week. Urine testing done at the end of the work shift gave a somewhat better estimate of borate exposure than did blood testing, was sampled more easily, and was analytically less difficult to perform. Personal air samplers of two types were used: one, the 37-mm closed-face, two-piece cassette to estimate total dust and the other, the Institute of Occupational Medicine (IOM) sampler to estimate inspirable particulate mass. Under the conditions of this study, the IOM air sampler more nearly estimated human exposure as measured by blood- and urine-boron levels than did the sampler that measured total dust.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Temporally and Spatially Resolved Plasma Spectroscopy in Pulsed Laser Deposition of Ultra-Thin Boron Nitride Films (Postprint)

    DTIC Science & Technology

    2015-04-24

    in the plasma plume. Boron, being the lighter of the two species ( atomic weights: B¼ 10.81, N¼ 14.01), will escape the Knudsen layer of plasma plume...AFRL-RX-WP-JA-2016-0196 TEMPORALLY AND SPATIALLY RESOLVED PLASMA SPECTROSCOPY IN PULSED LASER DEPOSITION OF ULTRA-THIN BORON NITRIDE...AND SPATIALLY RESOLVED PLASMA SPECTROSCOPY IN PULSED LASER DEPOSITION OF ULTRA-THIN BORON NITRIDE FILMS (POSTPRINT) 5a. CONTRACT NUMBER FA8650

  19. Electrical Characterization of Boron-Carbon Thin Films

    NASA Astrophysics Data System (ADS)

    Diaz, Manuel; Adenwalla, Shireen

    2004-03-01

    P-N junction diodes of boron-carbide and silicon have been previously fabricated and used in thermal neutron detection [1, 2]. However, the relation between the structure and electronic behavior of the boron-carbon layer are not fully understood. Thin films of p-type boron-carbon were deposited on Al2O3 substrates using plasma-enhanced chemical vapor deposition (PECVD), approximately 300 nm thick. The precursor compound used was Orthocarborane (closo-1,2-dicarbadodecaborane; C_2B_10H_12). Transport measurements of boron-carbon films on Al_2O3 were performed over a wide range of temperatures (20 K to 500 K). The resistivity at room temperature was found to be approximately 10000 ohm cm, and the temperature dependence showed a linear increase with temperature Analysis of the resistivity revealed the boron-carbon films to be a highly-doped degenerate semiconductor [2]. We discuss the relationship between structure and doping levels in this semiconducting material. [1] Adenwalla, S; Welsch, P; Harken A; Brand, JI; Sezer, A; Robertson, BW; Applied Physics Letters 79(26): 4357-4359 (2001) [2] Robertson, BW; Adenwalla, S; Harken A; Welsch, P; Brand, JI; Dowben, PA; Claasen, JP; Applied Physics Letters 80(19): 3644-3646 (2002) [3] Ashcroft, Neil W., & Mermin, N. David 1976, in Solid State Physics, ed. Thomson (New York: Thomson), 561-585

  20. Boron biodistribution study in colorectal liver metastases patients in Argentina.

    PubMed

    Cardoso, J; Nievas, S; Pereira, M; Schwint, A; Trivillin, V; Pozzi, E; Heber, E; Monti Hughes, A; Sanchez, P; Bumaschny, E; Itoiz, M; Liberman, S

    2009-07-01

    Ex-situ BNCT for multifocal unresectable liver metastases employing whole or partial autograft techniques requires knowledge of boron concentrations in healthy liver and metastases following perfusion and immersion in Wisconsin solution (W), the procedure employed for organ preservation during ex-situ irradiation. Measurements of boron concentration in blood, liver and metastases following an intravenous infusion of BPA-F in five colorectal liver metastases patients scheduled for surgery were performed. Tissue samples were evaluated for boron content pre and post perfusion and immersion in W. Complementary histological studies were performed. The data showed a dose-dependent BPA uptake in liver, a boron concentration ratio liver/blood close to 1 and a wide spread in the metastases/liver concentration ratios in the range 0.8-3.6, partially attributable to histological variations between samples. Based on the boron concentrations and dose considerations (liver < or =15 Gy-Eq and tumor> or =40 Gy-Eq) at the RA-3 thermal neutron facility (mean flux of about (6+/-1) x 10(9) n cm(-2)s(-1)), ex-situ treatment of liver metastases at RA-3 would be feasible.

  1. Boron in Calcium Sulfate Vein at Catabola, Mars

    NASA Image and Video Library

    2016-12-13

    The highest concentration of boron measured on Mars, as of late 2016, is in this mineral vein, called "Catabola," examined with the Chemistry and Camera (ChemCam) instrument on NASA's Curiosity rover on Aug, 25, 2016, during Sol 1441 of the mission. This two-part illustration shows the context of the erosion-resistant, raised vein, in an image from Curiosity's Mast Camera (Mastcam), and a detailed inset image from ChemCam's remote micro-imager. The inset includes indicators of the boron content measured at 10 points along the vein that were analyzed with ChemCam's laser-firing spectrometer. The vein's main component is calcium sulfate. The highest boron content identified is less than one-tenth of one percent. The heights of the orange bars at each point indicate relative abundance of boron, compared with boron content at other points. The scale bar for the inset is 9.2 millimeters, or about 0.36 inch. The ChemCam image is enhanced with color information from Mastcam. http://photojournal.jpl.nasa.gov/catalog/PIA21251

  2. Structure and superconductivity of isotope-enriched boron-doped diamond

    PubMed Central

    Ekimov, Evgeny A; Sidorov, Vladimir A; Zoteev, Andrey V; Lebed, Julia B; Thompson, Joe D; Stishov, Sergey M

    2008-01-01

    Superconducting boron-doped diamond samples were synthesized with isotopes of 10B, 11B, 13C and 12C. We claim the presence of a carbon isotope effect on the superconducting transition temperature, which supports the ‘diamond-carbon’-related nature of superconductivity and the importance of the electron–phonon interaction as the mechanism of superconductivity in diamond. Isotope substitution permits us to relate almost all bands in the Raman spectra of heavily boron-doped diamond to the vibrations of carbon atoms. The 500 cm−1 Raman band shifts with either carbon or boron isotope substitution and may be associated with vibrations of paired or clustered boron. The absence of a superconducting transition (down to 1.6 K) in diamonds synthesized in the Co–C–B system at 1900 K correlates with the small boron concentration deduced from lattice parameters. PMID:27878027

  3. Dirac Nodal Lines and Tilted Semi-Dirac Cones Coexisting in a Striped Boron Sheet.

    PubMed

    Zhang, Honghong; Xie, Yuee; Zhang, Zhongwei; Zhong, Chengyong; Li, Yafei; Chen, Zhongfang; Chen, Yuanping

    2017-04-20

    The enchanting Dirac fermions in graphene stimulated us to seek other 2D Dirac materials, and boron monolayers may be a good candidate. So far, a number of monolayer boron sheets have been theoretically predicted, and three have been experimentally prepared. However, none of intrinsic sheets possess Dirac electrons near the Fermi level. Herein, by means of density functional theory computations, we identified a new boron monolayer, namely, hr-sB, with two types of Dirac fermions coexisting in the sheet: One type is related to Dirac nodal lines traversing Brillouin zone (BZ) with velocities approaching 10(6) m/s, and the other is related to tilted semi-Dirac cones with strong anisotropy. This newly predicted boron monolayer consists of hexagon and rhombus stripes. With an exceptional stability comparable to the experimentally achieved boron sheets, it is rather optimistic to grow hr-sB on some suitable substrates such as the Ag (111) surface.

  4. Optimizing boron junctions through point defect and stress engineering using carbon and germanium co-implants

    SciTech Connect

    Moroz, Victor; Oh, Yong-Seog; Pramanik, Dipu; Graoui, Houda; Foad, Majeed A.

    2005-08-01

    We report the fabrication of p{sup +}/n junctions using Ge{sup +}, C{sup +}, and B{sup +} co-implantation and a spike anneal. The best junction exhibits a depth of 26 nm, vertical abruptness of 3 nm/decade, and sheet resistance of 520 Ohm/square. The junction location is defined by where the boron concentration drops to 10{sup 18} cm{sup -3}. These junctions are close to the International Technology Roadmap specifications for the 65 nm technology node and are achieved by careful engineering of amorphization, stresses, and point defects. Advanced simulation of boron diffusion is used to understand and optimize the process window. The simulations show that the optimum process completely suppresses the transient-enhanced diffusion of boron and the formation of boron-interstitial clusters. This increases the boron solubility to 20% above the equilibrium solid-state solubility.

  5. Applications and perspectives of boron-enriched nanocomposites in cancer therapy.

    PubMed

    Yinghuai, Zhu; Hosmane, Narayan S

    2013-04-01

    Recently, boron compounds have attracted increasing attention both in academic laboratories and in the pharmaceutical industry. Boron, in particular the (10)B isotope, has the unique capability of absorbing a slow neutron to initiate a nuclear reaction with release of energetic particles such as α- and Li-particles, which is not observed in its carbon analogues. The nuclear capture reaction concept has been adopted in radiation therapy and used in boron neutron capture therapy (BNCT). BNCT is a potentially promising treatment for malignant brain tumors as well as other cancers, despite the limitation of a scarcity of neutron sources. There is the need in advanced research centers to construct high boron-containing composites as BNCT agents and develop more efficient drug carriers. This review discusses recent works on the development of boron-based therapeutic nanomaterials as BNCT agents.

  6. Commercial Clinical Application of Boron Neutron Capture Therapy

    SciTech Connect

    N /A

    1999-09-03

    CRADA No. 95-CR-09 among the LITCO--now Bechtel BWXT Idaho, LLC; a private company, Neutron Therapies Limited Liability Company, NTL formerly Ionix Corporation; and Washington State University was established in 1996 to further the development of BNCT. NTL has established a laboratory for the synthesis, under US FDA approved current Good Manufacturing Practices (cGMP) guidelines, of key boron intermediates and final boron agents for BNCT. The company has focused initially on the development of the compound GB-10 (Na{sub 2}B{sub 10}H{sub 10}) as the first boron agent of interest. An Investigational New Drug (IND) application for GB-10 has been filed and approved by the FDA for a Phase I human biodistribution trial in patients with non-small cell lung cancer and glioblastoma multiforme at UW under the direction of Professor Keith Stelzer, Principal Investigator (PI). These trials are funded by NTL under a contract with the UW, Department of Radiation Oncology, and the initial phases are nearing completion. Initial results show that boron-10 concentrations on the order of 100 micrograms per gram (100 ppm) can be achieved and maintained in blood with no indication of toxicity.

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

    SciTech Connect

    Gierga, D.P.; Yanch, J.C.; Shefer, R.E.

    1997-12-01

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

  8. Chromium boron surfaced nickel-iron base alloys

    NASA Technical Reports Server (NTRS)

    Rashid, James M. (Inventor); Friedrich, Leonard A. (Inventor); Freling, Melvin (Inventor)

    1984-01-01

    Chromium boron diffusion coatings on nickel iron alloys uniquely provide them with improvement in high cycle fatigue strength (up to 30%) and erosion resistance (up to 15 times), compared to uncoated alloy. The diffused chromium layer extends in two essential concentration zones to a total depth of about 40.times.10.sup.-6 m, while the succeeding boron layer is limited to 50-90% of the depth of the richest Cr layer nearest the surface. Both coatings are applied using conventional pack diffusion processes.

  9. Distribution of Boron Atoms in Ion Implanted Compound Semiconductors

    DTIC Science & Technology

    1988-11-22

    The nondestructive neutron depth profiling (NDP) technique has been used to measure the boron (10B) distributions in GaAs, CdTe, Hg0.7Cd0.3Te, and Hg0.85Mn0.15Te after multiple energy ion implants. The NDP results are found to be in good agreement with the theoretical ion ranges obtained from Monte Carlo computer simulations. Only minor changes in the boron profiles were seen for the chosen annealing conditions. Keywords

  10. Electron transport in HBr adsorbed boron doped carbon nanotube

    NASA Astrophysics Data System (ADS)

    Srivastava, Reena; Shahzad Khan, Md.; Shrivastava, Sadhna; Srivastava, Anurag

    2017-01-01

    A 10,0 pristine as well as boron doped zigzag single walled carbon nanotube has been analyzed as possible HBr sensor using DFT based ab-initio approach. The variation in band structures, Mulliken charge, NBO charge, binding energy and conductance variation has been analyzed. The CNT observes a lowering of bandgap in presence of HBr molecule near its surface and reduces the metallicity of Boron doped CNT. The B-CNT shows semiconducting to metallic transition and on introducing the HBr molecule near the surface, changes its conductance drastically. Strong physisorption is observed for HBr over B-CNT surface as a consequence of electrostatic interaction.

  11. Oxygen plasma damage in boron-diffused silicon

    SciTech Connect

    Frieser, R.G.; Bondur, J.A.; Gorey, E.F.

    1987-02-01

    Transistor p-n junctions are observed to have leaky electrical characteristics and increased resistivity after exposure to oxygen plasma. Heating the devices above 180/sup 0/C for at least 10 min in vacuum, nitrogen, forming gas, or air eliminates the problem and returns the desired electrical characteristics. Experiments indicate that the increase in resistivity is associated with a boron displacement from silicon lattice sites. Additional experiments indicate that this phenomenon can be caused by reactively ion etching or plasma ashing a bare silicon surface which is doped with boron.

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

    SciTech Connect

    Cherednichenko, Kirill A.; Sokolov, Petr S.; Solozhenko, Vladimir L.; Kalinko, Aleksandr; Le Godec, Yann; Polian, Alain; Itié, Jean-Paul

    2015-05-14

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

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

    SciTech Connect

    Binello, E.; Yanch, J.C.; Shortkroff, S.

    1997-12-01

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

  14. Azomethine H colorimetric method for determining dissolved boron in water

    USGS Publications Warehouse

    Spencer, R.R.; Erdmann, D.E.

    1979-01-01

    An automated colorimetric method for determining dissolved boron in water is described. The boron is complexed with azomethine H, which is readily available as the condensation product of H acid (8-amino-1-naphthol-3,6-disulfonic acid) and salicylaldehyde. The absorbance of the yellow complex formed is then measured colorimetrically at 410 nm. Interference effects from other dissolved species are minimized by the addition of diethylenetriaminepentaacetic acid (DTPA); however, iron, zinc, and bicarbonate interfere at concentrations above 400 ??g/L, 2000 ??g/L, and 200 mg/L, respectively. The bicarbonate interference can be eliminated by careful acidification of the sample with concentrated HCl to a pH between 5 and 6. Thirty samples per hour can be routinely analyzed over the range of from 10 to 400 ??g/L, boron.

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

    SciTech Connect

    Wang, Zhehui; Morris, Christopher L

    2010-01-01

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

  16. Transient enhanced diffusion of boron in silicon: The interstitial flux

    SciTech Connect

    Simpson, T.W.; Goldberg, R.D.; Mitchell, I.V.; Baribeau, J.M.

    1997-11-01

    Delta-doped boron marker layers in silicon have been used to test further the relationship between B transient enhanced diffusion (TED) and the flux of silicon interstitials released during the annealing stage following self implantation. The authors present new data which address a number of questions raised by the present models. They show that in the experiments bulk trapping of interstitials is significant only for low implant fluences ({approximately}10{sup 12} cm{sup {minus}2}). The origin of the observed diffusion-like profiles for the interstitial flux is instead found to lie in local trapping within the {delta}-doped layers themselves. Boron trapped in immobile clusters may be associated with Si interstitials in approximately a 1:1 ratio; nevertheless this trapping contribution alone may not entirely account for the observed gradient. They suggest that some part of the observed TED response with depth is attributable to local trapping of silicon interstitials within the boron doped layers.

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

    NASA Astrophysics Data System (ADS)

    Zhou, Jian-Rong; Sun, Zhi-Jia; Liu, Ben; Wang, Yan-Feng; Yang, Gui-An; Zhou, Liang; Xu, Hong; Dong, Jing; Yang, Lei; Li, Yi

    2011-07-01

    A new thermal neutron beam monitor with a Gas Electron Multiplier (GEM) is developed to meet the needs of the next generation of neutron facilities. A prototype chamber has been constructed with two 100 mm×100 mm GEM foils. Enriched boron-10 is coated on one surface of the aluminum cathode plate as the neutron convertor. 96 channel pads with an area of 8 mm×8 mm each are used for fast signal readout. In order to study the basic characteristics of a boron-coated GEM, several irradiation tests were carried out with α source 239Pu and neutron source 241Am(Be). The signal induced by the neutron source has a high signal-to-noise ratio. A clear image obtained from α source 239Pu is presented, which shows that the neutron beam monitor based on a boron-coated GEM has a good two-dimensional imaging ability.

  18. Tensile stress-strain behavior of boron/aluminum laminates

    NASA Technical Reports Server (NTRS)

    Sova, J. A.; Poe, C. C., Jr.

    1978-01-01

    The tensile stress-strain behavior of five types of boron/aluminum laminates was investigated. Longitudinal and transverse stress-strain curves were obtained for monotonic loading to failure and for three cycles of loading to successively higher load levels. The laminate strengths predicted by assuming that the zero deg plies failed first correlated well with the experimental results. The stress-strain curves for all the boron/aluminum laminates were nonlinear except at very small strains. Within the small linear regions, elastic constants calculated from laminate theory corresponded to those obtained experimentally to within 10 to 20 percent. A limited amount of cyclic loading did not affect the ultimate strength and strain for the boron/aluminum laminates. The laminates, however, exhibited a permanent strain on unloading. The Ramberg-Osgood equation was fitted to the stress-strain curves to obtain average curves for the various laminates.

  19. Boronated porhyrins and methods for their use

    DOEpatents

    Miura, Michiko; Shelnutt, John A.; Slatkin, Daniel N.

    1999-03-02

    The present invention covers boronated porphyrins containing multiple carborane cages which selectively accumulate in neoplastic tissue within the irradiation volume and thus can be used in cancer therapies such as boron neutron capture therapy and photodynamic therapy.

  20. Boronated porhyrins and methods for their use

    DOEpatents

    Miura, M.; Shelnutt, J.A.; Slatkin, D.N.

    1999-03-02

    The present invention covers boronated porphyrins containing multiple carborane cages which selectively accumulate in neoplastic tissue within the irradiation volume and thus can be used in cancer therapies such as boron neutron capture therapy and photodynamic therapy. 3 figs.

  1. Synthesis and Utility of Dihydropyridine Boronic Esters**

    PubMed Central

    Panda, Santanu; Coffin, Aaron; Nguyen, Q. Nhu; Tantillo, Dean; Ready, Joseph M.

    2016-01-01

    When activated by an acylating agent, pyridine boronic esters react with organometallic reagents to form a dihydropyridine boronic ester. This intermediate allows access to a number of valuable substituted pyridine, dihydropyridine and piperidine products. PMID:26694785

  2. Synthesis and Utility of Dihydropyridine Boronic Esters.

    PubMed

    Panda, Santanu; Coffin, Aaron; Nguyen, Q Nhu; Tantillo, Dean J; Ready, Joseph M

    2016-02-05

    When activated by an acylating agent, pyridine boronic esters react with organometallic reagents to form a dihydropyridine boronic ester. This intermediate allows access to a number of valuable substituted pyridine, dihydropyridine, and piperidine products.

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

    PubMed

    Nielsen, Forrest Harold

    2009-01-01

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

  4. Boron Abundances in A and B-type Stars

    NASA Technical Reports Server (NTRS)

    Lambert, David L.

    1997-01-01

    Boron abundances in A- and B-type stars may be a successful way to track evolutionary effects in these hot stars. The light elements - Li, Be, and B - are tracers of exposure to temperatures more moderate than those in which the H-burning CN-cycle operates. Thus, any exposure of surface stellar layers to deeper layers will affect these light element abundances. Li and Be are used in this role in investigations of evolutionary processes in cool stars, but are not observable in hotter stars. An investigation of boron, however, is possible through the B II 1362 A resonance line. We have gathered high resolution spectra from the IUE database of A- and B-type stars near 10 solar mass for which nitrogen abundances have been determined. The B II 1362 A line is blended throughout; the temperature range of this program, requiring spectrum syntheses to recover the boron abundances. For no star could we synthesize the 1362 A region using the meteoritic/solar boron abundance of log e (B) = 2.88; a lower boron abundance was necessary which may reflect evolutionary effects (e.g., mass loss or mixing near the main-sequence), the natal composition of the star forming regions, or a systematic error in the analyses (e.g., non-LTE effects). Regardless of the initial boron abundance, and despite the possibility of non-LTE effects, it seems clear that boron is severely depleted in some stars. It may be that the nitrogen and boron abundances are anticorrelated, as would be expected from mixing between the H-burning and outer stellar layers. If, as we suspect, a residue of boron is present in the A-type supergiants, we may exclude a scenario in which mixing occurs continuously between the surface and the deep layers operating the CN-cycle. Further exploitation of the B II 1362 A line as an indicator of the evolutionary status of A- and B-type stars will require a larger stellar sample to be observed with higher signal-to-noise as attainable with the Hubble Space Telescope.

  5. Analysis of boron distribution in vivo for boron neutron capture therapy using two different boron compounds by secondary ion mass spectrometry.

    PubMed

    Yokoyama, Kunio; Miyatake, Shin-Ichi; Kajimoto, Yoshinaga; Kawabata, Shinji; Doi, Atsushi; Yoshida, Toshiko; Okabe, Motonori; Kirihata, Mitsunori; Ono, Koji; Kuroiwa, Toshihiko

    2007-01-01

    The efficiency of boron neutron capture therapy (BNCT) for malignant gliomas depends on the selective and absolute accumulation of (10)B atoms in tumor tissues. Only two boron compounds, BPA and BSH, currently can be used clinically. However, the detailed distributions of these compounds have not been determined. Here we used secondary ion mass spectrometry (SIMS) to determine the histological distribution of (10)B atoms derived from the boron compounds BSH and BPA. C6 tumor-bearing rats were given 500 mg/kg of BPA or 100 mg/kg of BSH intraperitoneally; 2.5 h later, their brains were sectioned and subjected to SIMS. In the main tumor mass, BPA accumulated heterogeneously, while BSH accumulated homogeneously. In the peritumoral area, both BPA and BSH accumulated measurably. Interestingly, in this area, BSH accumulated distinctively in a diffuse manner even 800 microm distant from the interface between the main tumor and normal brain. In the contralateral brain, BPA accumulated measurably, while BSH did not. In conclusion, both BPA and BSH each have advantages and disadvantages. These compounds are considered to be essential as boron delivery agents independently for clinical BNCT. There is some rationale for the simultaneous use of both compounds in clinical BNCT for malignant gliomas.

  6. Methods for boron delivery to mammalian tissue

    DOEpatents

    Hawthorne, M. Frederick; Feaks, Debra A.; Shelly, Kenneth J.

    2003-01-01

    Boron neutron capture therapy can be used to destroy tumors. This treatment modality is enhanced by delivering compounds to the tumor site where the compounds have high concentrations of boron, the boron compounds being encapsulated in the bilayer of a liposome or in the bilayer as well as the internal space of the liposomes. Preferred compounds, include carborane units with multiple boron atoms within the carborane cage structure. Liposomes with increased tumor specificity may also be used.

  7. Methods and compositions for boronizing metallic surfaces

    SciTech Connect

    Reid, D. K.

    1985-11-26

    The present disclosure is directed to methods and compositions for boronizing metal and in particular ferrous surfaces. It has been discovered that if hydrocarbons are processed in metallic equipment which have been previously boronized, that coke formation and deposition which is commonly experienced at high temperatures can be minimized if not totally eliminated. The compositions utilized for this purpose are comprised of boron or boron compounds contained in an organic solvent or carrier together with specific activating materials.

  8. A theranostic approach based on the use of a dual boron/Gd agent to improve the efficacy of Boron Neutron Capture Therapy in the lung cancer treatment.

    PubMed

    Alberti, Diego; Protti, Nicoletta; Toppino, Antonio; Deagostino, Annamaria; Lanzardo, Stefania; Bortolussi, Silva; Altieri, Saverio; Voena, Claudia; Chiarle, Roberto; Geninatti Crich, Simonetta; Aime, Silvio

    2015-04-01

    This study aims at developing an innovative theranostic approach for lung tumor and metastases treatment, based on Boron Neutron Capture Therapy (BNCT). It relies on to the use of low density lipoproteins (LDL) as carriers able to maximize the selective uptake of boron atoms in tumor cells and, at the same time, to quantify the in vivo boron distribution by magnetic resonance imaging (MRI). Tumor cells uptake was initially assessed by ICP-MS and MRI on four types of tumor (TUBO, B16-F10, MCF-7, A549) and one healthy (N-MUG) cell lines. Lung metastases were generated by intravenous injection of a Her2+ breast cancer cell line (i.e. TUBO) in BALB/c mice and transgenic EML4-ALK mice were used as primary tumor model. After neutron irradiation, tumor growth was followed for 30-40 days by MRI. Tumor masses of boron treated mice increased markedly slowly than the control group. From the clinical editor: In this article, the authors described an improvement to existing boron neutron capture therapy. The dual MRI/BNCT agent, carried by LDLs, was able to maximize the selective uptake of boron in tumor cells, and, at the same time, quantify boron distribution in tumor and in other tissues using MRI. Subsequent in vitro and in vivo experiments showed tumor cell killing after neutron irradiation. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Cobalt Doping of Semiconducting Boron Carbide Using Cobaltocene

    DTIC Science & Technology

    2007-03-01

    a semiconducting boron carbide homojunction diode has been fabricated. This diode has potential applications in neutron detection, direct neutron ...REF-1 viii List of Figures Figure Page 1-1. Prototype handheld neutron ...to corrosive, high temperature, and mechanically abrasive environments. [1] Because 10B has a large thermal neutron capture cross section (3840

  10. Diffusion of boron in alloys

    SciTech Connect

    Wang, W.; Zhang, S; He, X.

    1995-04-01

    By means of particle tracking autoradiography (PTA), the diffusion coefficients of boron between 900 and 1,200 C were measured in 04MnNbB steel, 25MnTiB steel, Ni-B, Fe-30%Ni-B and Fe-3%Si-B alloys, and the frequency factor D{sub 0} and activation energy Q were obtained respectively. The experiment results indicated that there was an obvious difference between the present result and the result obtained by Busby (in 1953). It was found that the boron diffusivity in {gamma}-Fe increased as Ni was added. The diffusivity of boron in Fe-3%Si-B alloy with b.c.c. structure was much slower than one obtained by Busby in {alpha}-Fe (1954), which, however, was much faster than the results obtained in {gamma}-Fe (with f.c.c. structure). Based on the present data of boron diffusion coefficients, the mechanism of segregation of boron to grain boundaries is discussed.

  11. Boron intake and prostate cancer risk.

    PubMed

    Gonzalez, Alejandro; Peters, Ulrike; Lampe, Johanna W; White, Emily

    2007-12-01

    Experimental studies suggest that boron may prevent prostate cancer. Only one small epidemiological study has been conducted of boron, which found that those in the highest quartile of boron intake had less than half the risk of prostate cancer versus those in the lowest quartile. We evaluated the association between boron intake and prostate cancer within the VITamins And Lifestyle (VITAL) cohort. A total of 35,244 men completed the baseline supplement and food frequency questionnaire (FFQ) in 2000-2002. A boron database was constructed from published sources to estimate boron intake from the FFQ and from multivitamins. A total of 832 men developed prostate cancer from baseline to 31 December 2004. Dietary boron intake and total boron intake from diet plus multivitamins were not associated with prostate cancer risk. The hazard ratio of prostate cancer for those in the highest versus lowest quartile of total boron intake was 1.17 (95% CI 0.85, 1.61). This risk did not vary by prostate cancer stage or Gleason score. Furthermore, none of the foods high in boron content was associated with a decreased risk of prostate cancer. This cohort study provides no evidence for a preventive role of boron intake on prostate cancer. Since few studies exist on this topic, future research is needed to better elucidate any role that boron may play in the prevention of prostate cancer.

  12. Mineral resource of the month: boron

    USGS Publications Warehouse

    Lyday, Phyllis A.

    2005-01-01

    What does boron have to do with baseball, apple pie, motherhood and Chevrolet? Boron minerals and chemicals are used in the tanning of leather baseballs and gloves; in micro-fertilizer to grow apples and in the glass and enamels of bakewares to cook apple pie; in boron detergents for soaking baby clothes and diapers; and in fiberglass parts for the Chevrolet Corvette.

  13. The use of amorphous boron powder enhances mechanical alloying in soft magnetic FeNbB alloy: A magnetic study

    SciTech Connect

    Ipus, J. J.; Blazquez, J. S.; Franco, V.; Conde, A.

    2013-05-07

    Saturation magnetization and magnetic anisotropy have been studied during mechanical alloying of Fe{sub 75}Nb{sub 10}B{sub 15} alloys prepared using crystalline and commercial amorphous boron. The evolution of saturation magnetization indicates a more efficient dissolution of boron into the matrix using amorphous boron, particularly for short milling times. The magnetization of the crystalline phase increases as boron is incorporated into this phase. Two milling time regimes can be used to describe the evolution of magnetic anisotropy: a first regime governed by microstrains and a second one mainly governed by crystal size and amorphous fraction.

  14. The effect of boron implant energy on transient enhanced diffusion in silicon

    SciTech Connect

    Liu, J.; Krishnamoorthy, V.; Gossman, H.; Rubin, L.; Law, M.E.; Jones, K.S.

    1997-02-01

    Transient enhanced diffusion (TED) of boron in silica after low energy boron implantation and annealing was investigated using boron-doping superlattices (DSLs) grown by low temperature molecular beam epitaxy. Boron ions were implanted at 5, 10, 20, and 40 keV at a constant dose of 2{times}10{sup 14}/cm{sup 2}. Subsequent annealing was performed at 750{degree}C for times of 3 min, 15 min, and 2 h in a nitrogen ambient. The broadening of the boron spikes was measured by secondary ion mass spectroscopy and simulated. Boron diffusivity enhancement was quantified as a function of implant energy. Transmission electron microscopy results show that {l_angle}311{r_angle} defects are only seen for implant energies {ge}10 keV at this dose and that the density increases with energy. DSL studies indicate the point defect concentration in the background decays much slower when {l_angle}311{r_angle} defects are present. These results imply there are at least two sources of TED for boron implants (B-I): short time component that decays rapidly consistent with nonvisible B-I pairs and a longer time component consistent with interstitial release from the {l_angle}311{r_angle} defects. {copyright} {ital 1997 American Institute of Physics.}

  15. Ultrahard nanotwinned cubic boron nitride.

    PubMed

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

    2013-01-17

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

  16. Graphene on hexagonal boron nitride

    NASA Astrophysics Data System (ADS)

    Yankowitz, Matthew; Xue, Jiamin; LeRoy, B. J.

    2014-07-01

    The field of graphene research has developed rapidly since its first isolation by mechanical exfoliation in 2004. Due to the relativistic Dirac nature of its charge carriers, graphene is both a promising material for next-generation electronic devices and a convenient low-energy testbed for intrinsically high-energy physical phenomena. Both of these research branches require the facile fabrication of clean graphene devices so as not to obscure its intrinsic physical properties. Hexagonal boron nitride has emerged as a promising substrate for graphene devices as it is insulating, atomically flat and provides a clean charge environment for the graphene. Additionally, the interaction between graphene and boron nitride provides a path for the study of new physical phenomena not present in bare graphene devices. This review focuses on recent advancements in the study of graphene on hexagonal boron nitride devices from the perspective of scanning tunneling microscopy with highlights of some important results from electrical transport measurements.

  17. Boron doping a semiconductor particle

    DOEpatents

    Stevens, G.D.; Reynolds, J.S.; Brown, L.K.

    1998-06-09

    A method of boron doping a semiconductor particle using boric acid to obtain a p-type doped particle. Either silicon spheres or silicon powder is mixed with a diluted solution of boric acid having a predetermined concentration. The spheres are dried, with the boron film then being driven into the sphere. A melt procedure mixes the driven boron uniformly throughout the sphere. In the case of silicon powder, the powder is metered out into piles and melted/fused with an optical furnace. Both processes obtain a p-type doped silicon sphere with desired resistivity. Boric acid is not a restricted chemical, is inexpensive, and does not pose any special shipping, handling, or disposal requirements. 2 figs.

  18. The boron conundrum: which principles underlie the formation of large hollow boron cages?

    PubMed

    Muya, Jules Tshishimbi; Lijnen, Erwin; Nguyen, Minh Tho; Ceulemans, Arnout

    2013-02-04

    Extensive optimisation calculations are performed for the B(80) isomers in order to find out which principles underlie the formation of large hollow boron cages. Our analysis shows that the most stable isomers contain triangular B(10) or rhombohedral B(16) building blocks. The lowest-energy isomer has C(3v) symmetry and is characterised by a belt of three interconnected B(16) units and two separate B(10) units. At the B3LYP/6-31G(d) level of theory, this newly discovered isomer is 2.29, 1.48, and 0.54 eV below the leapfrog B(80) of Szwacki et al., the T(h) -B(80) of Wang, and the D(3d) -B(80) of Pochet et al., respectively. Our C(3v) isomer is therefore identified as the most stable hollow cage isomer of B(80) presently known. Its HOMO-LUMO gap of 1.6 eV approaches that of the leapfrog B(80). The leapfrog principle still remains a reliable scheme for producing boron cages with larger HOMO-LUMO gaps, whereas the thermodynamically most stable B(80) cages are formed when all pentagonal faces are capped. We show that large hollow cages of boron retain a preference for fullerene frames. The additional capping is in accordance with the following rules: preference for capping of pentagonal faces, formation of B(10) and/or B(16) units, homogeneous distribution of the hexagonal caps, and hole density approaching 1/9. Although our most stable B(80) isomer still remains higher in energy than the B(80) core-shell structure, we show that by applying the bonding principles to larger structures it is possible to construct boron cages with higher stabilisation energy per boron atom than the core-shell structure; a prototypical example is B(160). This clearly shows the continuous competition between the two suggested construction schemes, namely, the formation of multiple-shell structures and hollow cages. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Synthesis of boron suboxide from boron and boric acid under mild pressure and temperature conditions

    SciTech Connect

    Jiao, Xiaopeng; Jin, Hua; Ding, Zhanhui; Yang, Bin; Lu, Fengguo; Zhao, Xudong; Liu, Xiaoyang; Peng, Liping

    2011-05-15

    Graphical abstract: Well-crystallized and icosahedral B{sub 6}O crystals were prepared by reacting boron and boric acid at milder reaction conditions (1 GPa and 1300 {sup o}C for 2 h) as compared to previous work.. Research highlights: {yields} Well-crystallized icosahedral B{sub 6}O was synthesized by reacting boric acid and boron. {yields} The synthesis conditions (1 GPa and 1300 {sup o}C for 2 h) are milder in comparison with previous work. {yields} The more practical synthesis method may make B{sub 6}O as a potential substitute for diamond in industry. -- Abstract: Boron suboxide (B{sub 6}O) was synthesized by reacting boron and boric acid (H{sub 3}BO{sub 3}) at pressures between 1 and 10 GPa, and at temperatures between 1300 and 1400 {sup o}C. The B{sub 6}O samples prepared were icosahedral with diameters ranging from 20 to 300 nm. Well-crystallized and icosahedral crystals with an average size of {approx}100 nm can be obtained at milder reaction conditions (1 GPa and 1300 {sup o}C for 2 h) as compared to previous work. The bulk B{sub 6}O sample was stable in air at 600 {sup o}C and then slowly oxidized up to 1000 {sup o}C. The relatively mild synthetic conditions developed in this study provide a more practical synthesis of B{sub 6}O, which may potentially be used as a substitute for diamond in industry as a new superhard material.

  20. Temperature admittance spectroscopy of boron doped chemical vapor deposition diamond

    SciTech Connect

    Zubkov, V. I. Kucherova, O. V.; Zubkova, A. V.; Ilyin, V. A.; Afanas'ev, A. V.; Bogdanov, S. A.; Vikharev, A. L.; Butler, J. E.

    2015-10-14

    Precision admittance spectroscopy measurements over wide temperature and frequency ranges were carried out for chemical vapor deposition epitaxial diamond samples doped with various concentrations of boron. It was found that the experimentally detected boron activation energy in the samples decreased from 314 meV down to 101 meV with an increase of B/C ratio from 600 to 18000 ppm in the gas reactants. For the heavily doped samples, a transition from thermally activated valence band conduction to hopping within the impurity band (with apparent activation energy 20 meV) was detected at temperatures 120–150 K. Numerical simulation was used to estimate the impurity DOS broadening. Accurate determination of continuously altering activation energy, which takes place during the transformation of conduction mechanisms, was proposed by numerical differentiation of the Arrhenius plot. With increase of boron doping level the gradual decreasing of capture cross section from 3 × 10{sup −13} down to 2 × 10{sup −17} cm{sup 2} was noticed. Moreover, for the hopping conduction the capture cross section becomes 4 orders of magnitude less (∼2 × 10{sup −20} cm{sup 2}). At T > T{sub room} in doped samples the birth of the second conductance peak was observed. We attribute it to a defect, related to the boron doping of the material.

  1. Boron compounds reduce vanadium tetraoxide genotoxicity in human lymphocytes.

    PubMed

    Geyikoglu, Fatime; Turkez, Hasan

    2008-11-01

    Vanadium has potential medical and pharmacological uses although it may also show genotoxic effects. Biological effects of boron are defined, but its interaction with vanadium is not known for therapeutic uses. The objective of present study was especially to determine whether boron compounds (boric acid and borax) conferred the protection against vanadium(IV) tetraoxide genotoxicity. After the application of vanadium (5, 10 and 20mg/l) and boron compounds (5 and 10mg/l), blood cultures were assessed by genetic endpoints and total antioxidant capacity (TAC). According to our results, vanadium(IV) tetraoxide induced a reduction in proliferation index (PI). Besides, the frequencies of sister-chromatid exchanges (SCEs), micronuclei (MN) rates and chromosomal aberrations (CAs) in peripheral lymphocytes were significantly increased by vanadium(IV) tetraoxide (10 and 20mg/l) compared to controls. On the other hand, boric acid and borax did not show cytotoxic and genotoxic effects at the concentrations tested. Moreover, these compounds elevated TAC in erythrocytes. The order of anti-genotoxicity efficacy against vanadium was boric acid and borax, respectively. In conclusion, boron compounds have been shown to protect vanadium-induced DNA damage in vitro for the first time. Copyright © 2008 Elsevier B.V. All rights reserved.

  2. On Boron Diffusion in MgF{sub 2}

    SciTech Connect

    Vacik, J.; Hnatowicz, V.; Cervena, J.; Posta, S.; Koester, U.; Pasold, G.

    2009-03-10

    The MgF{sub 2} monocrystals were irradiated at room temperature with 390 keV B{sup +} ions up to the fluence of 10{sup 16} cm{sup -2}. The irradiated samples were (isochronally and isothermally) annealed in high vacuum at the temperatures 200 deg. C, 300 deg. C, 400 deg. C, 500 deg. C, 600 deg. C and 700 deg. C for the times ranging from 2-100 hours. After each annealing step, the boron depth distribution was determined using the neutron depth profiling technique. As implanted, the depth distributions of boron exhibited standard Gaussian-like forms, but the evaluated profile parameters, R{sub P} = 960 nm and {delta}R{sub P} = 140 nm, were higher than those calculated using the SRIM code (R{sub P} = 870 nm and {delta}R{sub P} = 115 nm). Annealing at temperatures up to 400 deg. C did not change the depth profiles. Annealing at 600 deg. C, however, led to a one-way gradual transfer of the boron atoms from the site of implantation towards the sample surface, and in this way a bimodal profile was created. The amount of boron atoms, transferred to the sample surface, was an increasing function of the annealing time. After annealing at 700 deg. C for 64 hours the bimodal profile collapsed into a single broad distribution, extending from the sample surface up to the implantation depth. The observed phenomena clearly points out the stability of the as-implanted boron depth profiles at lower annealing temperatures. Thermal annealing above 600 deg. C, however, liberates boron atoms, which then predominantly migrate from the implantation site towards the sample surface, where they are captured on some unspecified surface defects.

  3. Boron oxygen complexes in Si

    NASA Astrophysics Data System (ADS)

    Sanati, M.; Estreicher, S. K.

    2006-04-01

    The carrier lifetime in boron-doped Czochralski Si is strongly reduced by irradiation (space-based solar cells) or illumination (terrestrial cells). The culprits are believed to be boron-oxygen complexes. We use first-principles theory to predict the structure, electrical activity, and stability of complexes involving substitutional or interstitial B and interstitial O or oxygen dimers. Four complexes with comparable binding energies and thermodynamic gap levels are identified and their local vibrational modes predicted. Replacing B with Ga yields complexes with much smaller binding energies.

  4. Boron Derivatives of 3-Methylpyrazole.

    DTIC Science & Technology

    1984-12-01

    AD-A14$ 988 BORON DERIVRTIYES OF 3 -IETHYLPYRRZOLECU) KENTUCKY UNIV i/i LEXINGTON DEPT OF CHEMISTRY K NIEDENZU ET AL. DEC 84 UK/DC/TR- 5 N8@814-83-K...REPORT DOCUMENTATION PAGE BEFORE CO.!?OVE~r;G FORM UK/DC/TR- 5 I - -_ E. ’and Subtitle) OF 21-P R & PZRIOD COVER=~ BORON DERIVATIVES OF 3 -METHYLPYRAZOLE...pathways for the latter process. In addition, the compounds 4 ,4 ,8,8-tetrabromo- and 4 ,4 ,8 ,8-tetrakis( 3 -methylpyrazole-l-yl)-l, 5 (7)-dimethyl

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Toward deep blue nano hope diamonds: heavily boron-doped diamond nanoparticles.

    PubMed

    Heyer, Steffen; Janssen, Wiebke; Turner, Stuart; Lu, Ying-Gang; Yeap, Weng Siang; Verbeeck, Jo; Haenen, Ken; Krueger, Anke

    2014-06-24

    The production of boron-doped diamond nanoparticles enables the application of this material for a broad range of fields, such as electrochemistry, thermal management, and fundamental superconductivity research. Here we present the production of highly boron-doped diamond nanoparticles using boron-doped CVD diamond films as a starting material. In a multistep milling process followed by purification and surface oxidation we obtained diamond nanoparticles of 10-60 nm with a boron content of approximately 2.3 × 10(21) cm(-3). Aberration-corrected HRTEM reveals the presence of defects within individual diamond grains, as well as a very thin nondiamond carbon layer at the particle surface. The boron K-edge electron energy-loss near-edge fine structure demonstrates that the B atoms are tetrahedrally embedded into the diamond lattice. The boron-doped diamond nanoparticles have been used to nucleate growth of a boron-doped diamond film by CVD that does not contain an insulating seeding layer.

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

    PubMed

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

    2014-11-01

    Boron neutron capture synovectomy (BNCS) is explored for the treatment of rheumatoid arthritis (RA). The aim of the present study was to perform boron biodistribution studies in a model of antigen-induced arthritis (AIA) in female New Zealand rabbits, with the boron carriers boronophenylalanine (BPA) and sodium decahydrodecaborate (GB-10) to assess the potential feasibility of BNCS for RA. Rabbits in chronic phase of AIA were used for biodistribution studies employing the following protocols: intra-articular (ia) (a) BPA-f 0.14 M (0.7 mg (10)B), (b) GB-10 (5 mg (10)B), (c) GB-10 (50 mg (10)B) and intravenous (iv), (d) BPA-f 0.14 M (15.5 mg (10)B/kg), (e) GB-10 (50 mg (10)B/kg), and (f) BPA-f (15.5 mg (10)B/kg) + GB-10 (50 mg (10)B/kg). At different post-administration times (13-85 min for ia and 3 h for iv), samples of blood, pathological synovium (target tissue), cartilage, tendon, muscle, and skin were taken for boron measurement by inductively coupled plasma mass spectrometry. The intra-articular administration protocols at <40 min post-administration both for BPA-f and GB-10, and intravenous administration protocols for GB-10 and [GB-10 + BPA-f] exhibited therapeutically useful boron concentrations (>20 ppm) in the pathological synovium. Dosimetric estimations suggest that BNCS would be able to achieve a therapeutically useful dose in pathological synovium without exceeding the radiotolerance of normal tissues in the treatment volume, employing boron carriers approved for use in humans. Radiobiological in vivo studies will be necessary to determine the actual therapeutic efficacy of BNCS to treat RA in an experimental model.

  8. Boron Nitride Nanoribbons from Exfoliation of Boron Nitride Nanotubes

    NASA Technical Reports Server (NTRS)

    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.

  9. Computational Studies of Nanostructures of Boron

    NASA Astrophysics Data System (ADS)

    Tandy, P.; Yu, M.; Leahy, C.; Tian, W. Q.; Wu, S. Y.; Jayanthi, C. S.

    2009-03-01

    The goal of this work is to develop a reliable semi-empirical Hamiltonian for boron that may be used to predict nanostructures of boron. It is well known that bonding in boron is complicated as it may form three-center, two-electron bonds. The semi-empirical Hamiltonian used here was recently developed by Leahy et al. in the framework of linear combination of atomic orbitals[1]. The salient feature of this Hamiltonian is that it treats environment dependency and charge redistributions on equal footing. It will be shown that such a parameterized Hamiltonian can predict the B80 cage structure with C1 symmetry as found in a recent first-principles study [2]. Having validated our semi-empirical Hamiltonian for boron with small boron clusters and the B80 cage, we have performed a systematic study of other boron nanostructures: (i) larger cage structures (e.g., B215), (ii) boron clusters cut from the bulk alpha boron, and (iii) boron sheets (triangular sheets with and without holes). We will discuss the ground state structures of these boron nanostructures as well as the energetics and HOMO-LUMO gaps of different families of boron clusters as a function their diameters. 1. C. Leahy et al. Phys. Rev. B74, 155408 (2006). 2. N. G. Szwacki et al. PRL 100, 159901 (2008).

  10. Thermionic properties of the molybdenum boron system

    SciTech Connect

    Storms, E.K.

    1980-01-01

    The thermionic work function has been measured as a function of composition within the various two phase regions between Mo and MoB/sub 2/. Values at the low boron and high boron phase boundaries for the various compounds were obtained by extrapolation. The following effective work functions were obtained: Mo/sub 2/B (low boron) = 3.08 eV; Mo/sub 2/B (high boron) = 3.63 eV; ..cap alpha..-MoB (low boron) = 3.38 eV; ..cap alpha..-MoB (high boron) = 4.30 eV; ..beta..-MoB (low boron) = 2.83 eV; ..beta..-MoB (high boron) = 3.92; Mo/sub 2/B/sub 3/ (low boron) = 4.65 eV; Mo/sub 2/B/sub 3/ (high boron) = 3.85 eV; and MoB/sub 2/ (low boron) = 3.52 eV. Because the composition range of these compounds is very narrow, the work function is very sensitive to the composition within the single phase regions.

  11. High fluence boron implantation into polyimide

    NASA Astrophysics Data System (ADS)

    Vacík, J.; Hnatowicz, V.; Červená, J.; Peřina, V.; Popok, V.; Odzhaev, V.; Fink, D.

    1999-01-01

    100 keV B + ions are implanted at high fluences into polyimide and the boron depth distributions are measured by the neutron depth profiling technique. Subsequently the implanted samples are annealed isochronally to determine the diffusional, trapping and detrapping behaviour of the boron atoms. The boron depth profiles of as-implanted samples differ significantly from those predicted by TRIM code. Pronounced inward and outward profile tails point at increased mobility and redistribution of boron atoms after implantation. Thermal annealing to the temperatures below 150°C does not change the total boron content in 1 μm thick surface layer and the boron depth profiles as well. For higher annealing temperatures a continuous desorption and significant redistribution of boron atoms is observed.

  12. A new boronic acid fluorescent sensor based on fluorene for monosaccharides at physiological pH

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh, Rahman; Mohadjerani, Maryam; Pooryousef, Mona; Eslami, Abbas; Emami, Saeed

    2015-06-01

    Fluorescent boronic acids are very useful fluorescent sensor for detection of biologically important saccharides. Herein we synthesized a new fluorene-based fluorescent boronic acid that shows significant fluorescence changes upon addition of saccharides at physiological pH. Upon addition of fructose, sorbitol, glucose, galactose, ribose, and maltose at different concentration to the solution of 7-(dimethylamino)-9,9-dimethyl-9H-fluoren-2-yl-2-boronic acid (7-DMAFBA, 1), significant decreases in fluorescent intensity were observed. It was found that this boronic acid has high affinity (Ka = 3582.88 M-1) and selectivity for fructose over glucose at pH = 7.4. The sensor 1 showed a linear response toward D-fructose in the concentrations ranging from 2.5 × 10-5 to 4 × 10-4 mol L-1 with the detection limit of 1.3 × 10-5 mol L-1.

  13. Research in boron neutron capture synovectomy

    NASA Astrophysics Data System (ADS)

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

    1997-02-01

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

  14. Boron deficiency decreases plasmalemma H+-ATPase expression and nitrate uptake, and promotes ammonium assimilation into asparagine in tobacco roots.

    PubMed

    Camacho-Cristóbal, Juan J; González-Fontes, Agustín

    2007-07-01

    The effects of short-term boron deficiency on several aspects (growth, biomass allocation, metabolite concentrations, gene expression, enzyme activities) related with nitrate assimilation were studied in tobacco (Nicotiana tabacum L.) plants in order to know the early changes caused by this mineral deficiency. For this purpose, plants were grown hydroponically in a nutrient solution supplemented with 10 microM boron and then transferred to a boron-free medium for 1-5 days. Nitrate concentration decreased in both leaves and roots under boron deficiency, which was not observed in control plants. This correlated with the lower net nitrate uptake rate found in boron-deficient plants when compared to boron-sufficient ones. Results suggest that boron deficiency decreases net nitrate uptake by declining the activity of nitrate transporters rather than affecting their transcript levels. This is supported by a drop in the levels of root PMA2 transcript during the boron deficient treatment, which could lead to a decrease in the plasma membrane H+-ATPase activity necessary to get protons out of cell for the cotransport with nitrate inwards. In addition, boron deficiency led to an increase in root Asn content and a decline in glutamine synthetase activity when compared to control plants, which suggest that this mineral deficiency may promote ammonium assimilation via asparagine synthetase in tobacco roots.

  15. Boron Neutron Capture Therapy for Malignant Brain Tumors.

    PubMed

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

    2016-07-15

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

  16. Boron Neutron Capture Therapy for Malignant Brain Tumors

    PubMed Central

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

    2016-01-01

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

  17. Tribological properties of nitrogen implanted and boron implanted steels

    SciTech Connect

    Kern, K.T.; Walter, K.C.; Griffin, A.J. Jr.; Kung, H.; Lu, Y.; Nastasi, M.; Tesmer, J.R.; Fayeulle, S.

    1996-06-01

    Samples of a steel with high chrome content was implanted separately with 75 keV nitrogen ions and with 75 keV boron ions. Implanted doses of each ion species were 2-, 4-, and 8 {times} 10{sup 17}/cm{sup 2}. Retained doses were measured using resonant non-Rutherford Backscattering Spectrometry. Tribological properties were determined using a pin-on-disk test with a 6-mm diameter ruby pin with a velocity of 0.94 m/min. Testing was done at 10% humidity with a load of 377 g. Wear rate and coefficient of friction were determined from these tests. While reduction in the wear rate for nitrogen implanted materials was observed, greater reduction (more than an order of magnitude) was observed for boron implanted materials. In addition, reduction in the coefficient of friction for high-dose boron implanted materials was observed. Nano-indentation revealed a hardened layer near the surface of the material. Results from grazing incidence x-ray diffraction suggest the formation of Fe{sub 2}N and Fe{sub 3}N in the nitrogen implanted materials and Fe{sub 3}B in the boron implanted materials. Results from transmission electron microscopy will be presented.

  18. Structure of boron nitride nanotubes

    NASA Astrophysics Data System (ADS)

    Buranova, Yu. S.; Kulnitskiy, B. A.; Perezhogin, I. A.; Blank, V. D.

    2015-01-01

    The crystallographic structure of boron nitride nanotubes has been investigated. Various defects that may arise during nanotube synthesis are revealed by electron microscopy. Nanotubes with different numbers of walls and different diameters are modeled by molecular dynamics methods. Structural features of single-wall nanotubes are demonstrated. The causes of certain defects in multiwall nanotubes are indicated.

  19. Boron trifluoride coatings for plastics

    NASA Technical Reports Server (NTRS)

    Kubacki, R. M.

    1978-01-01

    Tough, durable coatings of boron triflouride can be deposited on plastic optical components to protect them from destructive effects of abrasion, scratching, and environment. Coating material can be applied simultaneously with organic polymers, using plasma glow-discharge methods, or it can be used as base material for other coatings to increase adhesion.

  20. Method of separating boron isotopes

    DOEpatents

    Jensen, R.J.; Thorne, J.M.; Cluff, C.L.

    1981-01-23

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

  1. Method of separating boron isotopes

    DOEpatents

    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.

  2. Structure of boron nitride nanotubes

    SciTech Connect

    Buranova, Yu. S. Kulnitskiy, B. A.; Perezhogin, I. A.; Blank, V. D.

    2015-01-15

    The crystallographic structure of boron nitride nanotubes has been investigated. Various defects that may arise during nanotube synthesis are revealed by electron microscopy. Nanotubes with different numbers of walls and different diameters are modeled by molecular dynamics methods. Structural features of single-wall nanotubes are demonstrated. The causes of certain defects in multiwall nanotubes are indicated.

  3. Method of separating boron isotopes

    SciTech Connect

    Jensen, R.J.; Cluff, C.L.; Hayes, J.K.; Thorne, J.M.

    1984-05-08

    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/.

  4. Coupling of dextrans conjugated with boron to gamma globulin: a model for NCT

    SciTech Connect

    Elmore, J.J. Jr.; Borg, D.C.; Micca, P.; Gabel, D.

    1983-01-01

    Our project is to meet more effectively the well known primary requirement for treatment with boron-10 neutron capture therapy (NCT): namely, the selective localization of a sufficient amount of boron in or on target cells. Monoclonal antibodies (MCA) to tumor-associated antigens are attractive targeting carriers for boron-10 in terms of the needed selective localization. However the densities of surface receptors on tumor cells have seemed deficient to achieve successful NCT. If one seeks the necessary radiotherapeutic ratios by increasing the numbers of boron atoms or carborane cages bound per MCA, then inactivation of the antibody can occur through loss of receptor specificity and/or by precipitation of the protein. To achieve the goal of overcoming the limitations of antibody binding capacity, we have elected to use water-soluble dextrans as intermediate carriers. This permits each MCA molecule to target many atoms of boron-10 to the specified antigenic receptors while only 5 to 10 of the amino acid residues of the protein are conjugated by dextrans carrying boron-10.

  5. Analysis of boron carbides' electronic structure

    NASA Technical Reports Server (NTRS)

    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.

  6. PMMA functionalized boron nitride sheets as nanofillers

    NASA Astrophysics Data System (ADS)

    Cui, Zhenhua; Martinez, Andre P.; Adamson, Douglas H.

    2015-05-01

    We report the functionalization of hexagonal boron nitride (hBN) with polymer chains. These chains are grown by atom transfer radical polymerization (ATRP) from hBN following thermal treatment. When used as a nanofiller, the material shows improved dispersion resulting in significantly improved toughness as compared to pristine hBN without polymer functionalization. The polymer functionalized BN is also characterized by TGA, FTIR and FESEM.We report the functionalization of hexagonal boron nitride (hBN) with polymer chains. These chains are grown by atom transfer radical polymerization (ATRP) from hBN following thermal treatment. When used as a nanofiller, the material shows improved dispersion resulting in significantly improved toughness as compared to pristine hBN without polymer functionalization. The polymer functionalized BN is also characterized by TGA, FTIR and FESEM. Electronic supplementary information (ESI) available: More information on the details for characterization of reaction intermediates by FTIR, FESEM, GPC and stress-strain curve of composites. See DOI: 10.1039/c5nr00936g

  7. Boron modified molybdenum silicide and products

    DOEpatents

    Meyer, Mitchell K.; Akinc, Mufit

    1999-02-02

    A boron-modified molybdenum silicide material 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.sub.5 Si.sub.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.sub.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.sub.5 Si.sub.3 for structural integrity.

  8. Boron modified molybdenum silicide and products

    DOEpatents

    Meyer, M.K.; Akinc, M.

    1999-02-02

    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{sub 5}Si{sub 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{sub 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{sub 5}Si{sub 3} for structural integrity. 7 figs.

  9. Controlling the Morphology and Oxidation Resistance of Boron Carbide Synthesized Via Carbothermic Reduction Reaction

    NASA Astrophysics Data System (ADS)

    Ahmed, Yasser M. Z.; El-Sheikh, Said M.; Ewais, Emad M. M.; Abd-Allah, Asmaa A.; Sayed, Said A.

    2017-02-01

    Boron carbide powder was synthesized from boric acid and lactose mixtures via easy procedure. Boric acid and lactose solution mixtures were roasted in stainless steel pot at 280 °C for 24 h. Boron carbide was obtained by heating the roasted samples under flowing of industrial argon gas at 1500 °C for 3 h. The amount of borate ester compound in the roasted samples was highly influenced by the boron/carbon ratio in the starting mixtures and plays a versatile role in the produced boron carbide. The high-purity boron carbide powder was produced with a sample composed of lowest boron/carbon ratio of 1:1 without calcination step. Particle morphology was changed from nano-needles like structure of 8-10 nm size with highest carbon ratio mixture to spherical shape of >150 nm size with lowest one. The oxidation resistance performance of boron carbide is highly dependent on the morphology and grain size of the synthesized powder.

  10. Early-life exposure to lithium and boron from drinking water.

    PubMed

    Harari, Florencia; Ronco, Ana María; Concha, Gabriela; Llanos, Miguel; Grandér, Margaretha; Castro, Francisca; Palm, Brita; Nermell, Barbro; Vahter, Marie

    2012-12-01

    The transfer of lithium and boron from exposed mothers to fetuses and breast-fed infants was investigated in areas in northern Argentina and Chile with up to 700 μg lithium/L and 5-10 mg boron/L in drinking water. Maternal and cord blood concentrations were strongly correlated and similar in size for both lithium (47 and 70 μg/L, respectively) and boron (220 and 145 μg/L, respectively). The first infant urine produced after birth contained the highest concentrations (up to 1700 μg lithium/L and 14,000 μg boron/L). Breast-milk contained 40 and 60% of maternal blood concentrations of lithium and boron, respectively (i.e. about 30 and 250 μg/L, respectively, in high exposure areas), and infant urine concentrations decreased immediately after birth (120 μg lithium/L and 920 μg boron/L). We conclude that lithium and boron easily passed the placenta to the fetus, and that exclusively breast-fed infants seemed to have lower exposure than formula-fed infants.

  11. Controlling the Morphology and Oxidation Resistance of Boron Carbide Synthesized Via Carbothermic Reduction Reaction

    NASA Astrophysics Data System (ADS)

    Ahmed, Yasser M. Z.; El-Sheikh, Said M.; Ewais, Emad M. M.; Abd-Allah, Asmaa A.; Sayed, Said A.

    2017-03-01

    Boron carbide powder was synthesized from boric acid and lactose mixtures via easy procedure. Boric acid and lactose solution mixtures were roasted in stainless steel pot at 280 °C for 24 h. Boron carbide was obtained by heating the roasted samples under flowing of industrial argon gas at 1500 °C for 3 h. The amount of borate ester compound in the roasted samples was highly influenced by the boron/carbon ratio in the starting mixtures and plays a versatile role in the produced boron carbide. The high-purity boron carbide powder was produced with a sample composed of lowest boron/carbon ratio of 1:1 without calcination step. Particle morphology was changed from nano-needles like structure of 8-10 nm size with highest carbon ratio mixture to spherical shape of >150 nm size with lowest one. The oxidation resistance performance of boron carbide is highly dependent on the morphology and grain size of the synthesized powder.

  12. Cytotoxicity of Boron-Doped Nanocrystalline Diamond Films Prepared by Microwave Plasma Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Liu, Dan; Gou, Li; Ran, Junguo; Zhu, Hong; Zhang, Xiang

    2015-07-01

    Boron-doped nanocrystalline diamond (NCD) exhibits extraordinary mechanical properties and chemical stability, making it highly suitable for biomedical applications. For implant materials, the impact of boron-doped NCD films on the character of cell growth (i.e., adhesion, proliferation) is very important. Boron-doped NCD films with resistivity of 10-2 Ω·cm were grown on Si substrates by the microwave plasma chemical vapor deposition (MPCVD) process with H2 bubbled B2O3. The crystal structure, diamond character, surface morphology, and surface roughness of the boron-doped NCD films were analyzed using different characterization methods, such as X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The contact potential difference and possible boron distribution within the film were studied with a scanning kelvin force microscope (SKFM). The cytotoxicity of films was studied by in vitro tests, including fluorescence microscopy, SEM and MTT assay. Results indicated that the surface roughness value of NCD films was 56.6 nm and boron was probably accumulated at the boundaries between diamond agglomerates. MG-63 cells adhered well and exhibited a significant growth on the surface of films, suggesting that the boron-doped NCD films were non-toxic to cells. supported by the Open Foundation of State Key Laboratory of Electronic Thin Films and Integrated Devices (University of Electronic Science and Technology of China) (No. KFJJ201313)

  13. Homogeneous immunoconjugates for boron neutron-capture therapy: Design, synthesis, and preliminary characterization

    PubMed Central

    Guan, Lufeng; Wims, Letitia A.; Kane, Robert R.; Smuckler, Mark B.; Morrison, Sherie L.; Hawthorne, M. Frederick

    1998-01-01

    The application of immunoprotein-based targeting strategies to the boron neutron-capture therapy of cancer poses an exceptional challenge, because viable boron neutron-capture therapy by this method will require the efficient delivery of 103 boron-10 atoms by each antigen-binding protein. Our recent investigations in this area have been focused on the development of efficient methods for the assembly of homogeneous immunoprotein conjugates containing the requisite boron load. In this regard, engineered immunoproteins fitted with unique, exposed cysteine residues provide attractive vehicles for site-specific modification. Additionally, homogeneous oligomeric boron-rich phosphodiesters (oligophosphates) have been identified as promising conjugation reagents. The coupling of two such boron-rich oligophosphates to sulfhydryls introduced to the CH2 domain of a chimeric IgG3 has been demonstrated. The resulting boron-rich immunoconjugates are formed efficiently, are readily purified, and have promising in vitro and in vivo characteristics. Encouragingly, these studies showed subtle differences in the properties of the conjugates derived from the two oligophosphate molecules studied, providing a basis for the application of rational design to future work. Such subtle details would not have been as readily discernible in heterogeneous conjugates, thus validating the rigorous experimental design employed here. PMID:9789066

  14. Chronic boron exposure and human semen parameters.

    PubMed

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

    2010-04-01

    Boron found as borates in soil, food, and water has important industrial and medical applications. A panel reviewing NTP reproductive toxicants identified boric acid as high priority for occupational studies to determine safe versus adverse reproductive effects. To address this, we collected boron exposure/dose measures in workplace inhalable dust, dietary food/fluids, blood, semen, and urine from boron workers and two comparison worker groups (n=192) over three months and determined correlations between boron and semen parameters (total sperm count, sperm concentration, motility, morphology, DNA breakage, apoptosis and aneuploidy). Blood boron averaged 499.2 ppb for boron workers, 96.1 and 47.9 ppb for workers from high and low environmental boron areas (p<0.0001). Boron concentrated in seminal fluid. No significant correlations were found between blood or urine boron and adverse semen parameters. Exposures did not reach those causing adverse effects published in animal toxicology work but exceeded those previously published for boron occupational groups.

  15. Determination of boron in materials by cold neutron prompt gamma-ray activation analysis.

    PubMed

    Paul, Rick L

    2005-01-01

    An instrument for cold neutron prompt gamma-ray activation analysis (PGAA), located at the NIST Center for Neutron Research (NCNR), has proven useful for the measurement of boron in a variety of materials. Neutrons, moderated by passage through liquid hydrogen at 20 K, pass through a (58)Ni coated guide to the PGAA station in the cold neutron guide hall of the NCNR. The thermal equivalent neutron fluence rate at the sample position is 9 x 10(8) cm(-2) s(-1). Prompt gamma rays are measured by a cadmium- and lead-shielded high-purity germanium detector. The instrument has been used to measure boron mass fractions in minerals, in NIST SRM 2175 (Refractory Alloy MP-35-N) for certification of boron, and most recently in semiconductor-grade silicon. The limit of detection for boron in many materials is <10 ng g(-1).

  16. Ferromagnetism and semiconducting of boron nanowires

    PubMed Central

    2012-01-01

    More recently, motivated by extensively technical applications of carbon nanostructures, there is a growing interest in exploring novel non-carbon nanostructures. As the nearest neighbor of carbon in the periodic table, boron has exceptional properties of low volatility and high melting point and is stronger than steel, harder than corundum, and lighter than aluminum. Boron nanostructures thus are expected to have broad applications in various circumstances. In this contribution, we have performed a systematical study of the stability and electronic and magnetic properties of boron nanowires using the spin-polarized density functional calculations. Our calculations have revealed that there are six stable configurations of boron nanowires obtained by growing along different base vectors from the unit cell of the bulk α-rhombohedral boron (α-B) and β-rhombohedral boron (β-B). Well known, the boron bulk is usually metallic without magnetism. However, theoretical results about the magnetic and electronic properties showed that, whether for the α-B-based or the β-B-based nanowires, their magnetism is dependent on the growing direction. When the boron nanowires grow along the base vector [001], they exhibit ferromagnetism and have the magnetic moments of 1.98 and 2.62 μB, respectively, for the α-c [001] and β-c [001] directions. Electronically, when the boron nanowire grows along the α-c [001] direction, it shows semiconducting and has the direct bandgap of 0.19 eV. These results showed that boron nanowires possess the unique direction dependence of the magnetic and semiconducting behaviors, which are distinctly different from that of the bulk boron. Therefore, these theoretical findings would bring boron nanowires to have many promising applications that are novel for the boron bulk. PMID:23244063

  17. Boron microlocalization in oral mucosal tissue: implications for boron neutron capture therapy

    PubMed Central

    Morris, G M; Smith, D R; Patel, H; Chandra, S; Morrison, G H; Hopewell, J W; Rezvani, M; Micca, P L; Coderre, J A

    2000-01-01

    Clinical studies of the treatment of glioma and cutaneous melanoma using boron neutron capture therapy (BNCT) are currently taking place in the USA, Europe and Japan. New BNCT clinical facilities are under construction in Finland, Sweden, England and California. The observation of transient acute effects in the oral mucosa of a number of glioma patients involved in the American clinical trials, suggests that radiation damage of the oral mucosa could be a potential complication in future BNCT clinical protocols, involving higher doses and larger irradiation field sizes. The present investigation is the first to use a high resolution surface analytical technique to relate the microdistribution of boron-10 (10B) in the oral mucosa to the biological effectiveness of the 10B(n,α)7Li neutron capture reaction in this tissue. The two boron delivery agents used clinically in Europe/Japan and the USA, borocaptate sodium (BSH) and p-boronophenylalanine (BPA), respectively, were evaluated using a rat ventral tongue model. 10B concentrations in various regions of the tongue mucosa were estimated using ion microscopy. In the epithelium, levels of 10B were appreciably lower after the administration of BSH than was the case after BPA. The epithelium:blood 10B partition ratios were 0.2:1 and 1:1 for BSH and BPA respectively. The 10B content of the lamina propria was higher than that measured in the epithelium for both BSH and BPA. The difference was most marked for BSH, where 10B levels were a factor of six higher in the lamina propria than in the epithelium. The concentration of 10B was also measured in blood vessel walls where relatively low levels of accumulation of BSH, as compared with BPA, was demonstrated in blood vessel endothelial cells and muscle. Vessel wall:blood 10B partition ratios were 0.3:1 and 0.9:1 for BSH and BPA respectively. Evaluation of tongue mucosal response (ulceration) to BNC irradiation indicated a considerably reduced radiation sensitivity using BSH as

  18. Boron isotope fractionation in magma via crustal carbonate dissolution

    PubMed Central

    Deegan, Frances M.; Troll, Valentin R.; Whitehouse, Martin J.; Jolis, Ester M.; Freda, Carmela

    2016-01-01

    Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low δ11B values down to −41.5‰, reflecting preferential partitioning of 10B into the assimilating melt. Loss of 11B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports 11B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ11B melt values in arc magmas could flag shallow-level additions to the subduction cycle. PMID:27488228

  19. Design and fabrication of a boron reinforced intertank skirt

    NASA Technical Reports Server (NTRS)

    Henshaw, J.; Roy, P. A.; Pylypetz, P.

    1974-01-01

    Analytical and experimental studies were performed to evaluate the structural efficiency of a boron reinforced shell, where the medium of reinforcement consists of hollow aluminum extrusions infiltrated with boron epoxy. Studies were completed for the design of a one-half scale minimum weight shell using boron reinforced stringers and boron reinforced rings. Parametric and iterative studies were completed for the design of minimum weight stringers, rings, shells without rings and shells with rings. Computer studies were completed for the final evaluation of a minimum weight shell using highly buckled minimum gage skin. The detail design is described of a practical minimum weight test shell which demonstrates a weight savings of 30% as compared to an all aluminum longitudinal stiffened shell. Sub-element tests were conducted on representative segments of the compression surface at maximum stress and also on segments of the load transfer joint. A 10 foot long, 77 inch diameter shell was fabricated from the design and delivered for further testing.

  20. Boron isotope fractionation in magma via crustal carbonate dissolution.

    PubMed

    Deegan, Frances M; Troll, Valentin R; Whitehouse, Martin J; Jolis, Ester M; Freda, Carmela

    2016-08-04

    Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low δ(11)B values down to -41.5‰, reflecting preferential partitioning of (10)B into the assimilating melt. Loss of (11)B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports (11)B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ(11)B melt values in arc magmas could flag shallow-level additions to the subduction cycle.

  1. Selecting boron fullerenes by cage-doping mechanisms

    NASA Astrophysics Data System (ADS)

    Boulanger, Paul; Morinière, Maxime; Genovese, Luigi; Pochet, Pascal

    2013-05-01

    So far, no boron fullerenes were synthesized: more compact sp3-bonded clusters are energetically preferred. To circumvent this, metallic clusters have been suggested by Pochet et al. [Phys. Rev. B 83, 081403(R) (2011), 10.1103/PhysRevB.83.081403] as "seeds" for a possible synthesis which would topologically protect the sp2 sector of the configuration space. In this paper, we identify a basic pentagonal unit which allows a balance between the release of strain and the self-doping rule. We formulate a guiding principle for the stability of boron fullerenes, which takes the form of an isolated filled pentagon rule (IFPR). The role of metallic clusters is then reexamined. It is shown that the interplay of the IFPR and the seed-induced doping breaks polymorphism and its related problems: it can effectively select between different isomers and reduce the reactivity of the boron shells. The balance between self and exterior doping represents the best strategy for boron buckyball synthesis.

  2. Reductive Insertion of Elemental Chalcogens into Boron-Boron Multiple Bonds.

    PubMed

    Braunschweig, Holger; Dellermann, Theresa; Ewing, William C; Kramer, Thomas; Schneider, Christoph; Ullrich, Stefan

    2015-08-24

    The syntheses of sulfur- and selenium-bridged cyclic compounds containing boron stabilized by N-heterocyclic carbenes (NHCs) have been achieved by the reductive insertion of elemental chalcogens into boron-boron multiple bonds. The three pairs of bonding electrons between the boron atoms in the triply bonded diboryne enabled six-electron reduction reactions, resulting in the formation of [2.2.1]-bicyclic systems wherein bridgehead boron atoms are spanned by three chalcogen bridges. A similar reaction using a diborene (boron-boron double bond) resulted in the reductive transfer of both pairs of bonding electrons to three sulfur atoms, yielding a NHC-stabilized trisulfidodiborolane. The demonstration of these six- and four-electron reductions lends support to the presence of three and two pairs of bonding electrons between the boron atoms of the diboryne and diborene, respectively, a fact that may be useful in future discussions on bond order.

  3. Distribution of boron atoms in ion-implanted-compound semiconductors. Technical report

    SciTech Connect

    Bowman, R.C.; Knudsen, J.F.; Downing, R.G.; Kremer, R.E.

    1988-11-22

    The nondestructive neutron depth profiling (NDP) technique was used to measure the boron (10B) distributions in GaAs, CdTe, Hg0.7Cd0.3Te, and Hg0.85Mn0.15Te after multiple energy ion implants. The NDP results are found to be in good agreement with the theoretical ion ranges obtained from Monte Carlo computer simulations. Only minor changes in the boron profiles were seen for the chosen annealing conditions.

  4. Gate-dependent Pseudospin Mixing in Graphene/boron Nitride Moire Superlattices

    DTIC Science & Technology

    2014-08-31

    LETTERS PUBLISHED ONLINE: 31 AUGUST 2014 | DOI: 10.1038/NPHYS3075 Gate-dependent pseudospin mixing in graphene/boron nitride moiré superlattices ...nitride moiré superlattices , where a fast sublattice oscillation due to boron and nitrogen atoms is superimposed on the slow moiré period, provides an...attractive approach to engineer the electron pseudospin in graphene13–18. This unusual moiré superlattice leads to a spinor potential with unusual

  5. Jaguar Procedures for Detonation Behavior of Explosives Containing Boron

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  6. Amorphous boron nanorod as an anode material for lithium-ion batteries at room temperature

    DOE PAGES

    Deng, Changjian; Lau, Miu Lun; Barkholtz, Heather; ...

    2017-08-14

    We report an amorphous boron nanorod anode material for lithium ion batteries prepared through smelting non-toxic boron oxide in liquid lithium. Boron in theory can provide capacity as high as 3099 mAh g-1 by alloying with Li to form B4Li5. However, experimental studies of boron anode were rarely reported for room temperature lithium-ion batteries. Among the reported studies the electrochemical activity and cycling performance of bulk crystalline boron anode material are poor at room temperature. In this work, we developed amorphous nanostructured one-dimensional (1D) boron material aiming at improving lithium ion diffusion in boron at room temperature. The amorphous boronmore » nanorod anode exhibited, at room temperature, a reversible capacity of 170 mAh g-1 at a current rate of 10 mA g-1 between 0.01 and 2 V. The anode also demonstrated good rate capability and cycling stability. Lithium storage mechanism was investigated by both sweep voltammetry measurements and galvanostatic intermittent titration technique (GITT). The sweep voltammetric analysis suggested that the contributions from lithium ions diffusion into boron as well as the capacitive process are 42.44% and 57.56%, respectively. Results from GITT indicated that the discharge capacity at higher potentials (> ~ 0.2 V vs, Li/Li+) could be ascribed to a capacitive process and at lower potentials (< ~0.2 V vs, Li/Li+) to diffusion control. Solid state nuclear magnetic resonance (NMR) measurement further confirmed that the capacity is from electrochemical reactions between lithium ions and the amorphous boron nanorod.« less

  7. Synthesis of boron nitride nanotubes by boron ink annealing

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

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

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

    PubMed

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

    2010-03-12

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

  9. Development of high boron content liposomes and their promising antitumor effect for neutron capture therapy of cancers.

    PubMed

    Koganei, Hayato; Ueno, Manabu; Tachikawa, Shoji; Tasaki, Lisa; Ban, Hyun Seung; Suzuki, Minoru; Shiraishi, Kouichi; Kawano, Kumi; Yokoyama, Masayuki; Maitani, Yoshie; Ono, Koji; Nakamura, Hiroyuki

    2013-01-16

    Mercaptoundecahydrododecaborate (BSH)-encapsulating 10% distearoyl boron lipid (DSBL) liposomes were developed as a boron delivery vehicle for neutron capture therapy. The current approach is unique because the liposome shell itself possesses cytocidal potential in addition to its encapsulated agents. BSH-encapsulating 10% DSBL liposomes have high boron content (B/P ratio: 2.6) that enables us to prepare liposome solution with 5000 ppm boron concentration. BSH-encapsulating 10% DSBL liposomes displayed excellent boron delivery efficacy to tumor: boron concentrations reached 174, 93, and 32 ppm at doses of 50, 30, and 15 mg B/kg, respectively. Magnescope was also encapsulated in the 10% DSBL liposomes and the real-time biodistribution of the Magnescope-encapsulating DSBL liposomes was measured in a living body using MRI. Significant antitumor effect was observed in mice injected with BSH-encapsulating 10% DSBL liposomes even at the dose of 15 mg B/kg; the tumor completely disappeared three weeks after thermal neutron irradiation ((1.5-1.8) × 10(12) neutrons/cm(2)). The current results enabled us to reduce the total dose of liposomes to less than one-fifth compared with that of the BSH-encapsulating liposomes without reducing the efficacy of boron neutron capture therapy (BNCT).

  10. Longitudinal Splitting of Boron Nitride Nanotubes for the Facile Synthesis of High Quality Boron Nitride Nanoribbons

    DTIC Science & Technology

    2011-05-24

    Boron Nitride Nanotubes for the Facile Synthesis of High Quality Boron Nitride Nanoribbons Kris J. Erickson,†,‡,§ Ashley...We report the synthesis of BNNRs through the potassium-intercalation-induced longitudinal splitting of boron nitride nanotubes (BNNTs). This facile...COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE Longitudinal Splitting of Boron Nitride Nanotubes for the Facile Synthesis of High

  11. Mapping Boron Dioxide (BO2) Light Emission During Ballistic Initiation of Boron

    DTIC Science & Technology

    2016-03-03

    ARL-TN-0738 ● FEB 2016 US Army Research Laboratory Mapping Boron Dioxide (BO2) Light Emission During Ballistic Initiation of...ARL-TN-0738 ● FEB 2016 US Army Research Laboratory Mapping Boron Dioxide (BO2) Light Emission During Ballistic Initiation of Boron...Technical Note 3. DATES COVERED (From - To) February 2013–February 2015 4. TITLE AND SUBTITLE Mapping Boron Dioxide (BO2) Light Emission During

  12. Behavior of Boron Doped Graphites and Boron Carbide under Ion Beam and Plasma Irradiation

    NASA Astrophysics Data System (ADS)

    Begrambekov, L. B.; Buzhinsky, O. I.; Zakharovi, A.

    The paper shortly describes the methods of boron carbide coating deposition and presents the experimental results characterizing the properties of boron carbide coatings and of boron doped graphites important to their application as the plasma facing materials of fusion devices and other plasma apparatus dealing with dense and high temperature plasma. Conclusion is made that thick renewable boron carbide coating can successfully be used as the protecting coating of plasma facing elements of ITER.

  13. Prediction of boron carbon nitrogen phase diagram

    NASA Astrophysics Data System (ADS)

    Yao, Sanxi; Zhang, Hantao; Widom, Michael

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

  14. Method for preparing boron-carbide articles

    DOEpatents

    Benton, S.T.; Masters, D.R.

    1975-10-21

    The invention is directed to the preparation of boron carbide articles of various configurations. A stoichiometric mixture of particulate boron and carbon is confined in a suitable mold, heated to a temperature in the range of about 1250 to 1500$sup 0$C for effecting a solid state diffusion reaction between the boron and carbon for forming the boron carbide (B$sub 4$C), and thereafter the resulting boron-carbide particles are hot-pressed at a temperature in the range of about 1800 to 2200$sup 0$C and a pressure in the range of about 1000 to 4000 psi for densifying and sintering the boron carbide into the desired article.

  15. A new class of boron nanotube.

    PubMed

    Wang, Jing; Liu, Ying; Li, You-Cheng

    2009-12-07

    The configurations, stability and electronic structures of a new class of boron sheet and related boron nanotubes are predicted within the framework of density functional theory. This boron sheet is sparser than those of recent proposals. Our theoretic results show that the stable boron sheet remains flat and is metallic. There are bands similar to the pi-bands in graphite near the Fermi level. Stable nanotubes with various diameters and chiral vectors can be rolled from the sheet. Within our study, only the thin (8, 0) nanotube with a band gap of 0.44 eV is semiconducting, while all the other thicker boron nanotubes are metallic, independent of their chirality. It indicates the possibility, in the design of nanodevices, to control the electronic transport properties of the boron nanotube through the diameter.

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

    PubMed Central

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

    2017-01-01

    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. PMID:28417903

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

    PubMed Central

    Penland, J G

    1994-01-01

    Although the trace element boron has yet to be recognized as an essential nutrient for humans, recent data from animal and human studies suggest that boron may be important for mineral metabolism and membrane function. To investigate further the functional role of boron, brain electrophysiology and cognitive performance were assessed in response to dietary manipulation of boron (approximately 0.25 versus approximately 3.25 mg boron/2000 kcal/day) in three studies with healthy older men and women. Within-subject designs were used to assess functional responses in all studies. Spectral analysis of electroencephalographic data showed effects of dietary boron in two of the three studies. When the low boron intake was compared to the high intake, there was a significant (p < 0.05) increase in the proportion of low-frequency activity, and a decrease in the proportion of higher-frequency activity, an effect often observed in response to general malnutrition and heavy metal toxicity. Performance (e.g., response time) on various cognitive and psychomotor tasks also showed an effect of dietary boron. When contrasted with the high boron intake, low dietary boron resulted in significantly poorer performance (p < 0.05) on tasks emphasizing manual dexterity (studies II and III); eye-hand coordination (study II); attention (all studies); perception (study III); encoding and short-term memory (all studies); and long-term memory (study I). Collectively, the data from these three studies indicate that boron may play a role in human brain function and cognitive performance, and provide additional evidence that boron is an essential nutrient for humans. PMID:7889884

  18. Synthesis, Properties, and Applications Of Boron Nitride

    NASA Technical Reports Server (NTRS)

    Pouch, John J.; Alterovitz, Samuel A.

    1993-01-01

    Report describes synthesis, properties, and applications of boron nitride. Especially in thin-film form. Boron nitride films useful as masks in x-ray lithography; as layers for passivation of high-speed microelectronic circuits; insulating films; hard, wear-resistant, protective films for optical components; lubricants; and radiation detectors. Present status of single-crystal growth of boron nitride indicates promising candidate for use in high-temperature semiconductor electronics.

  19. Toxic effects of boron on mallard reproduction

    USGS Publications Warehouse

    Smith, G.J.; Anders, V.P.

    1989-01-01

    Boron, a naturally occurring trace element generally considered environmentally innocuous, was documented to severely impair mallard reproduction. Boron is leached from irrigated agricultural soils and transported in drainage water that contaminates wetlands. Until now, only the selenium accumulated in aquatic food chains has been documented to pose a toxic hazard to wildlife in drainage water wetlands. Management of drainage water-contaminated environments must now also consider the adverse effects of boron, as well as the possible interactions of drainage water contaminants.

  20. Stereodivergent Olefination of Enantioenriched Boronic Esters

    PubMed Central

    Armstrong, Roly J.; García‐Ruiz, Cristina; Myers, Eddie L.

    2016-01-01

    Abstract A stereodivergent coupling reaction between vinyl halides and boronic esters is described. This coupling process proceeds without a transition‐metal catalyst, instead proceeding by electrophilic selenation or iodination of a vinyl boronate complex followed by stereospecific syn or anti elimination. Chiral, nonracemic boronic esters could be coupled with complete enantiospecificity. The process enables the highly stereoselective synthesis of either the E or Z alkene from a single isomer of a vinyl coupling partner. PMID:27958668

  1. Synthesis, Properties, and Applications Of Boron Nitride

    NASA Technical Reports Server (NTRS)

    Pouch, John J.; Alterovitz, Samuel A.

    1993-01-01

    Report describes synthesis, properties, and applications of boron nitride. Especially in thin-film form. Boron nitride films useful as masks in x-ray lithography; as layers for passivation of high-speed microelectronic circuits; insulating films; hard, wear-resistant, protective films for optical components; lubricants; and radiation detectors. Present status of single-crystal growth of boron nitride indicates promising candidate for use in high-temperature semiconductor electronics.

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-06-01

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

  4. Boron containing multilayer coatings and method of fabrication

    DOEpatents

    Makowiecki, D.M.; Jankowski, A.F.

    1997-09-23

    Hard coatings are fabricated from multilayer boron/boron carbide, boron carbide/cubic boron nitride, and boron/boron nitride/boron carbide, and the fabrication thereof involves magnetron sputtering in a selected atmosphere. These hard coatings may be applied to tools and engine and other parts, as well to reduce wear on tribological surfaces and electronic devices. These boron coatings contain no morphological growth features. For example, the boron and boron carbide used in forming the multilayers are formed in an inert (e.g. argon) atmosphere, while the cubic boron nitride is formed in a reactive (e.g. nitrogen) atmosphere. The multilayer boron/boron carbide, and boron carbide/cubic boron nitride is produced by depositing alternate layers of boron, cubic boron nitride or boron carbide, with the alternate layers having a thickness of 1 nanometer to 1 micrometer, and at least the interfaces of the layers may be of a discrete or a blended or graded composition. 6 figs.

  5. An Exploration of Neutron Detection in Semiconducting Boron Carbide

    NASA Astrophysics Data System (ADS)

    Hong, Nina

    The 3He supply problem in the U.S. has necessitated the search for alternatives for neutron detection. The neutron detection efficiency is a function of density, atomic composition, neutron absorption cross section, and thickness of the neutron capture material. The isotope 10B is one of only a handful of isotopes with a high neutron absorption cross section---3840 barns for thermal neutrons. So a boron carbide semiconductor represents a viable alternative to 3He. This dissertation provides an evaluation of the performance of semiconducting boron carbide neutron detectors grown by plasma enhance chemical vapor deposition (PECVD) in order to determine the advantages and drawbacks of these devices for neutron detection. Improved handling of the PECVD system has resulted in an extremely stable plasma, enabling deposition of thick films of semiconducting boron carbide. A variety of material and semiconducting characterization tools have been used to investigate the structure and electronic properties of boron carbide thin films, including X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, infrared/Raman spectroscopy, current-voltage measurements and capacitance-voltage measurements. Elemental concentrations in the boron carbide films have been obtained from Rutherford backscattering and elastic recoil detection analysis. Solid state neutron detection devices have been fabricated in the form of heterostructured p-n diodes, p-type boron carbide/n-type Si. Operating conditions, including applied bias voltage, and time constants, have been optimized for maximum detection efficiency and correlated to the semiconducting properties investigated in separate electronic measurements. Accurate measurements of the neutron detection efficiency and the response of the detector to a wide range of neutron wavelengths have been performed at a well calibrated, tightly collimated, "white" cold neutron beam source using time-of-flight neutron detection technique

  6. Mineral resource of the month: boron

    USGS Publications Warehouse

    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.

  7. Premixed Combustion Model for Boron Clouds

    NASA Astrophysics Data System (ADS)

    Wang, Mengze; Han, Wang; Chen, Zheng

    2015-11-01

    Boron particle is an ideal additive in solid propellants and fuels due to its very high volumetric heat release. In this study, a premixed combustion model for boron clouds is developed based on a previous combustion model for single boron particle. The flame structure is assumed to be composed of three zones: the preheat zone, the ignition zone, and the reaction zone, and analytical solutions are derived from the governing equations. Consequently the influence of the boron clouds' physical properties on the flame propagation process is investigated.

  8. Producing carbon stripper foils containing boron

    SciTech Connect

    Stoner, J. O. Jr.

    2012-12-19

    Parameters being actively tested by the accelerator community for the purpose of extending carbon stripper foil lifetimes in fast ion beams include methods of deposition, parting agents, mounting techniques, support (fork) materials, and inclusion of alloying elements, particularly boron. Specialized production apparatus is required for either sequential deposition or co-deposition of boron in carbon foils. A dual-use vacuum evaporator for arc evaporation of carbon and electron-beam evaporation of boron and other materials has been built for such development. Production of both carbon and boron foils has begun and improvements are in progress.

  9. Boron deposition from fused salts. Final report

    SciTech Connect

    Smith, M.L.

    1980-08-01

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

  10. METHOD OF PREPARING POLONIUM-BORON SOURCES

    DOEpatents

    Birden, J.H.

    1959-08-01

    An improved technique is described for preparation of a polonium-boron neutron source. A selected amount of Po-210 is vaporized into a thin walled nickel container, then the desired amcunt of boron powder is added. After sealing the container, it is heated quickly by induction heating to vaporize the Po-210 and deposit it in the still cool boron powder. The unit is then quickly cooled to prevent revaporization of the Po-210 from the boron. The build-up of neutron emission may be followed by means of a neutron counter in order to terminate the heating at the optimum level of neutron yield.

  11. Boron Isotopes in Diatoms: a Proxy for pH?

    NASA Astrophysics Data System (ADS)

    Donald, H.; Foster, G. L.; Poulton, A. J.; Moore, C. M.; Swann, G. E. A.; Hendry, K. R.

    2016-12-01

    High latitudes are important regions to consider in terms of ocean acidification, as they are climatically sensitive regions where the greenhouse gas CO2 is exchanged between the ocean and atmosphere. In theory, an improved understanding of these regions could be achieved using the boron isotope palaeo-pH proxy, in which CaCO3-based organisms including foraminifera are traditionally measured. The Southern Ocean is of particular interest in the global carbon cycle, however, foraminifera are scarce in sediments from this region. In contrast, siliceous diatoms are a dominant group of microfossils found within sediments, but as yet, the boron isotope-pH proxy has not been extended to opal. This is the major goal of the current study. Diatoms construct their frustules from biogenic silica by polymerising Si(OH)4, and boron content of these frustules, previously investigated by LA-ICP-MS (Mejía et al. 2013), is around 5-10 ppm. Here, current solution MC-ICP-MS methods used to measure boron isotopes in calcifying organisms have been adapted and developed for use with diatom opal. Preliminary results for sediment diatoms from the onset of major Northern Hemisphere glaciation will be presented (subarctic Northwest Pacific ODP site 882), as well as results for the cultured diatom species Thalassiosira weissflogii grown at varied pCO2. In light of these results, we will speculate on the nature of boron incorporation into diatom opal and its potential as an archive for palaeo-pH reconstructions.

  12. Determination of the aquatic PNEC0.05 for boron.

    PubMed

    Dyer, S D

    2001-07-01

    Several weight of the evidence approaches for the effects assessment of boron to aquatic organisms have been conducted. The focal point for all of these assessments is the appropriate interpretation of the LC1 for rainbow trout (Oncorhynchus mykiss) from W.J. Birge, J.A. Black, Report No. EPA5601176408. Environmental Protection Agency, Office of Toxic Substances, Washington, DC, 1977, as the LC1 from their studies provided the lowest chronic toxicity values for boron. Other studies by these investigators (W.J. Birge, J.A. Black, Completion Report prepared for the Procter & Gamble Company, Cincinnati, USA, 1981; W.J. Birge, J.A. Black, A.G. Westermann, T.M. Short, S.B. Taylor, M.C. Parekh. Completion Report prepared for the Procter & Gamble Company, Cincinnati, USA, 1984; J.A. Black, J.B. Barnum, W.J. Birge, Chemosphere 26 (1993) 1383-1413) further indicate this species to be particularly sensitive to boron. While weight of the evidence approaches have been necessary for diverse risk assessment needs, they each suffer from potential bias via professional judgment. In order to allay these issues and to update the effects assessment for boron, a probabilistic approach was used. Raw data from the Birge and Black studies were reanalyzed to generate chronic values representative of the adverse effects threshold (e.g., LC10) for several species. A comprehensive list of chronic data from these studies and other studies were combined into a cumulative probability term, allowing for the determination of the fifth percentile protection value, or PNEC0.05. The PNEC0.05 for boron was determined to be at least 1.3 mg B/l.

  13. Making Microscopic Cubes Of Boron

    NASA Technical Reports Server (NTRS)

    Faulkner, Joseph M.

    1993-01-01

    Production of finely divided cubes of boron involves vacuum-deposition technology and requires making of template. Template supports pattern of checkered squares 25 micrometers on side, which are etched 25 micrometers into template material. Template coasted uniformly with paralyene or some similar vacuum coating with low coefficient of adhesion. Intended application to solid rocket fuels, explosives, and pyrotechnics; process used for other applications, from manufacture of pharmaceuticals to processing of nuclear materials.

  14. Conduction mechanism in boron carbide

    NASA Technical Reports Server (NTRS)

    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.

  15. Making Microscopic Cubes Of Boron

    NASA Technical Reports Server (NTRS)

    Faulkner, Joseph M.

    1993-01-01

    Production of finely divided cubes of boron involves vacuum-deposition technology and requires making of template. Template supports pattern of checkered squares 25 micrometers on side, which are etched 25 micrometers into template material. Template coasted uniformly with paralyene or some similar vacuum coating with low coefficient of adhesion. Intended application to solid rocket fuels, explosives, and pyrotechnics; process used for other applications, from manufacture of pharmaceuticals to processing of nuclear materials.

  16. Conduction mechanism in boron carbide

    NASA Technical Reports Server (NTRS)

    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.

  17. Improved tribological behavior of boron implanted Ti-6Al-4V

    SciTech Connect

    Baker, N.P.; Walter, K.C.; Nastasi, M.

    1998-03-01

    Boron implanted of Ti6Al4V has been conducted at combinations of 32 and 40 keV to supplement that done previously at 75 keV. Shallower boron depth profiles with higher B-concentrations in the Ti64 surface have been obtained by tailoring the combinations of ion energy and dose. This work used three different ion energy and dose combinations of 4 {times} 10{sup 17} B-at/cm{sup 2} at 40 keV plus 2 {times} 10{sup 17} B-at/cm{sup 2} at 32 keV, 4 {times} 10{sup 17} B-at/cm{sup 2} at 40 keV, and 4 {times} 10{sup 17} B-at/cm{sup 2} at 32 keV plus 2 {times} 10{sup 17} B-at/cm{sup 2} at 40 keV. Comparisons are made between Ti6Al4V with a shallow implanted boron depth profile, Ti6Al4V with a deeper boron depth profile and nitrogen implanted using a plasma source ion implantation process. It has been previously shown that while boron implanted Ti64 has a {approximately} 30% higher surface hardness than nitrogen implanted Ti64, the N-implantation reduced the wear coefficient of Ti64 by 25--120x, while B-implantation reduced the wear coefficient by 6.5x or less. The results show that no significant improvement is made in the wear resistance of boron implanted Ti6Al4V by increasing the concentration of boron at the surface from approximately 10% to 43%. Transmission electron microscopy (TEM) and selected area diffraction (SAD) indicated the formation of crystalline TiB in the implanted surface layer. Shallower depth profiles result in reductions of the Ti6Al4V wear coefficient by 6.5x or less which is the same result obtained earlier with the deeper boron depth profile. Surface hardness of Ti6Al4V with shallower boron depth profiles was improved approximately 10% compared to the results previously acquired with deeper boron depth profiles.

  18. Boron neutron capture therapy of ocular melanoma and intracranial glioma using p-boronophenylalanine

    SciTech Connect

    Coderre, J.A.; Greenberg, D.; Micca, P.L.; Joel, D.D.; Saraf, S. ); Packer, S. . Div. of Ophthalmology)

    1990-01-01

    During conventional radiotherapy, the dose that can be delivered to the tumor is limited by the tolerance of the surrounding normal tissue within the treatment volume. Boron Neutron Capture Therapy (BNCT) represents a promising modality for selective tumor irradiation. The key to effective BNCT is selective localization of {sup 10}B in the tumor. We have shown that the synthetic amino acid p-boronophenylalanine (BPA) will selectively deliver boron to melanomas and other tumors such as gliosarcomas and mammary carcinomas. Systemically delivered BPA may have general utility as a boron delivery agent for BNCT. In this paper, BNCT with BPA is used in treatment of experimentally induced gliosarcoma in rats and nonpigmented melanoma in rabbits. The tissue distribution of boron is described, as is response to the BNCT. 6 refs., 4 figs., 1 tab.

  19. Boron-rich benzene and pyrene derivatives for the detection of thermal neutrons

    NASA Astrophysics Data System (ADS)

    Yemam, Henok A.; Mahl, Adam; Koldemir, Unsal; Remedes, Tyler; Parkin, Sean; Greife, Uwe; Sellinger, Alan

    2015-09-01

    A synthetic methodology is developed to generate boron rich aromatic small molecules based on benzene and pyrene moieties for the detection of thermal neutrons. The prepared aromatic compounds have a relatively high boron content up to 7.4 wt%, which is important for application in neutron detection as 10B (20% of natural abundance boron) has a large neutron induced reaction cross-section. This is demonstrated by preparing blends of the synthesized molecules with fluorescent dopants in poly(vinyltoluene) matrices resulting in comparable scintillation light output and neutron capture as state-of-the art commercial scintillators, but with the advantage of much lower cost. The boron-rich benzene and pyrene derivatives are prepared by Suzuki conditions using both microwave and traditional heating, affording yields of 40-93%. This new procedure is simple and straightforward, and has the potential to be scaled up.

  20. Boronization in DIII-D

    SciTech Connect

    Jackson, G.L.; Burrell, K.H.; DeBoo, J.C.; Greenfield, C.M.; Groebner, R.J.; Hodapp, T.; Kellman, A.G.; Lee, R.; Lippman, S.I.; Phillips, J.; Taylor, T.S.; West, W.P.; Winter, J.; Moyer, R.; Watkins, J.

    1992-05-01

    A thin boron film has been applied to the DIII-D tokamak plasma facing surfaces to reduce impurity influx, particularly oxygen and carbon. A direct result of this surface modification was the observation of a regime of very high energy confinement, VH-mode, with confinement times from 1.5 to 2 times greater than predicted by H-mode scaling relation for the same set of parameters. VH-mode discharges are characterized by low ohmic target densities, low edge neutral pressure, and reduced cycling. These conditions have reduced the collisionality, {nu}*, in the edge region producing a higher edge pressure gradient and a significant bootstrap current, up to 30% of the total current. We will describe the edge plasma properties after boronization including reductions in recycling inferred from measurements of {tau}{sup p}*. In particular we will discuss the edge plasma conditions necessary for access to VH-mode including the boronization process and properties of the deposited film.

  1. Quantum emission from hexagonal boron nitride monolayers

    NASA Astrophysics Data System (ADS)

    Aharonovich, Igor; Tran, Toantrong; Bray, Kerem; Ford, Michael J.; Toth, Milos; MTEE Collaboration

    Artificial atomic systems in solids are widely considered the leading physical system for a variety of quantum technologies, including quantum communications, computing and metrology. To date, however, room-temperature quantum emitters have only been observed in wide-bandgap semiconductors such as diamond and silicon carbide, nanocrystal quantum dots, and most recently in carbon nanotubes. Here, we demonstrate room-temperature, polarized single-photon emission from a colour centre in two-dimensional hexagonal boron nitride. The emitters emit at the red and the near infrared spectral range and exhibit narrowband ultra bright emission (~full width at half maximum of below 10 nm with more than three million counts/s). Density functional theory calculations indicate that vacancy-related defects are a probable source of the emission. Our results demonstrate the unprecedented potential of van der Waals crystals for large-scale nanophotonics and quantum information processing.

  2. Laser Induced Fluorescence Spectroscopy of Boron Carbide

    NASA Astrophysics Data System (ADS)

    Cheung, A. S.-C.; Ng, Y. W.; Pang, H. F.

    2011-06-01

    Laser induced fluorescence spectrum of boron carbide (BC) between 490 and 560 nm has been recorded and analyzed. Gas-phase BC molecule was produced by the reaction of B2H6 and CH4 in the presence of magnesium atom from laser ablation process. The (0, 0), (1, 0), and (2, 0) bands of the B4 Σ- - X4 Σ- transition were recorded and rotationally analyzed. Spectra of both isotopes: 10BC and 11BC were observed. Equilibrium molecular constants for the B4 Σ- and the X4 Σ- states for both isotopes were determined. A comparison of the determined gas-phase molecular constants with those obtained using matrix isolation spectroscopy and the theoretical calculations will be presented. Financial support from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. HKU 701008P) is gratefully acknowledged.

  3. Boron neutron capture enhancement of fast neutron radiotherapy

    NASA Astrophysics Data System (ADS)

    Stelzer, K. J.; Laramore, G. E.; Risler, R.; Wiens, L.; Griffin, T. W.

    1997-02-01

    Clinical trials have revealed a therapeutic advantage for fast neutron radiation over conventional photon radiation for salivary gland cancer, prostate cancer, sarcoma, and a subgroup of lung cancer. Conversely, fast neutron treatment of high grade astrocytic brain tumors [glioblastoma multiforme (GBM)] resulted in tumor sterilization, but also caused significant brain injury such that no therapeutic gain was attained. This effect was important, however, in that photon radiation and other conventional treatments have not demonstrated sterilization of GBM at any dose. Recent laboratory studies demonstrated that the hospital-based fast neutron beam from the University of Washington cyclotron has a thermal neutron component that may be used in a boron-10 neutron capture (BNC) reaction to enhance cell kill. The degree of enhancement was approximately 10 fold, and was dependent upon the boron-10 concentration, the boron-10 carrier agent, and the fast neutron dose per fraction. The results of these experiments will be discussed in the context of creating a therapeutic window for treatment of glioblastoma using BNC-enhanced fast neutron radiation in a clinically tolerable regimen.

  4. Oxynitridation-enhanced diffusion of boron in <100> silicon

    SciTech Connect

    Chen, N.K.; Lee, C. . Dept. of Chemical Engineering)

    1993-08-01

    Diffusion of boron in pure N[sub 2] pure NH[sup 3], and mixtures of NH[sub 3] and N[sub 2] has been investigated to study the effect of the oxynitridation reaction on the diffusivity. The oxynitridation-enhanced diffusion can be explained by a dual mechanism involving both vacancy and interstitial silicon atoms. There is no effect on the enhancement diffusivity due to the junction depths used here. The interstitial and probably the vacancy concentrations are flat. With a thin SiO[sub 2] layer on the silicon wafer and a low boron concentration, the diffusion coefficient can be expressed as a function of the partial pressure of NH[sub 3] and temperature as D = 0.105 exp [[minus]3.22eV/kT] + 1.0 [times] 10[sup [minus]6] exp [[minus]1.71 eV/kT]p[sub nh[sub 3

  5. Energy Landscape of Fullerene Materials: A Comparison of Boron to Boron Nitride and Carbon

    NASA Astrophysics Data System (ADS)

    de, Sandip; Willand, Alexander; Amsler, Maximilian; Pochet, Pascal; Genovese, Luigi; Goedecker, Stefan

    2011-06-01

    Using the minima hopping global geometry optimization method on the density functional potential energy surface we show that the energy landscape of boron clusters is glasslike. Larger boron clusters have many structures which are lower in energy than the cages. This is in contrast to carbon and boron nitride systems which can be clearly identified as structure seekers. The differences in the potential energy landscape explain why carbon and boron nitride systems are found in nature whereas pure boron fullerenes have not been found. We thus present a methodology which can make predictions on the feasibility of the synthesis of new nanostructures.

  6. Boron-containing folate receptor-targeted liposomes as potential delivery agents for neutron capture therapy.

    PubMed

    Pan, Xing Q; Wang, Huaqing; Shukla, Supriya; Sekido, Masaru; Adams, Dianne M; Tjarks, Werner; Barth, Rolf F; Lee, Robert J

    2002-01-01

    Boron neutron capture therapy (BNCT) depends on the selective delivery of a sufficient number of (10)B atoms to tumor cells to sustain a lethal (10)B(n,alpha)(7)Li reaction. Expression of FR frequently is amplified among human tumors. The goal of the present study was to investigate folate receptor (FR)-targeted liposomes as potential carriers for a series of boron-containing agents. Two highly ionized boron compounds, Na(2)[B(12)H(11)SH] and Na(3) (B(20)H(17)NH(3)), were incorporated into liposomes by passive loading with encapsulation efficiencies of 6% and 15%, respectively. In addition, five weakly basic boronated polyamines were investigated. Two were the spermidine derivatives: N(5)-(4-carboranylbutyl)spermidine.3HCl (SPD-5), N(5)-[4-(2-aminoethyl-o-carboranyl)butyl]spermidine.4HCl (ASPD-5). Three were the spermine derivatives: N(5)-(4-carboranylbutyl)spermine.4HCl (SPM-5), N(5)-[4-(2-aminoethyl-o-carboranyl)butyl]spermine.5HCl (ASPM-5), and N(5),N(10)-bis(4-carboranylbutyl)spermine.4 HCl (SPM-5,10). These were incorporated into liposomes by a pH-gradient-driven remote-loading method with varying loading efficiencies, which were influenced by the specific trapping agent and the structure of the boron compound. Greater loading efficiencies were obtained with lower molecular weight boron derivatives, using ammonium sulfate as the trapping agent, compared to those obtained with sodium citrate. The in vitro uptake of folate-derivatized, boronated liposomes was investigated using human KB squamous epithelial cancer cells, which have amplified FR expression. Higher cellular boron uptake (up to 1584 microg per 10(9) cells) was observed with FR-targeted liposomes than with nontargeted control liposomes (up to 154 microg per 10(9) cells), irrespective of the chemical form of the boron and the method used for liposomal preparation. KB cell binding of the FR-targeted liposomes was saturable and could be blocked by 1 mM free folic acid. Our findings suggest that further

  7. Pharmacokinetics of core-polymerized, boron-conjugated micelles designed for boron neutron capture therapy for cancer.

    PubMed

    Sumitani, Shogo; Oishi, Motoi; Yaguchi, Tatsuya; Murotani, Hiroki; Horiguchi, Yukichi; Suzuki, Minoru; Ono, Koji; Yanagie, Hironobu; Nagasaki, Yukio

    2012-05-01

    Core-polymerized and boron-conjugated micelles (PM micelles) were prepared by free radical copolymerization of a PEG-b-PLA block copolymer bearing an acetal group and a methacryloyl group (acetal-PEG-b-PLA-MA), with 1-(4-vinylbenzyl)-closo-carborane (VB-carborane), and the utility of these micelles as a tumor-targeted boron delivery system was investigated for boron neutron capture therapy (BNCT). Non-polymerized micelles (NPM micelles) that incorporated VB-carborane physically showed significant leakage of VB-carborane (ca. 50%) after 12 h incubation with 10% fetal bovine serum (FBS) at 37 °C. On the other hand, no leakage from the PM micelles was observed even after 48 h of incubation. To clarify the pharmacokinetics of the micelles, (125)I (radioisotope)-labeled PM and NPM micelles were administered to colon-26 tumor-bearing BALB/c mice. The (125)I-labeled PM micelles showed prolonged blood circulation (area under the concentration curve (AUC): 943.4) than the (125)I-labeled NPM micelles (AUC: 495.1), whereas tumor accumulation was similar for both types of micelles (AUC(PM micelle): 249.6, AUC(NPM micelle): 201.1). In contrast, the tumor accumulation of boron species in the PM micelles (AUC: 268.6) was 7-fold higher than the NPM micelles (AUC: 37.1), determined by ICP-AES. Thermal neutron irradiation yielded tumor growth suppression in the tumor-bearing mice treated with the PM micelles without reduction in body weight. On the basis of these data, the PM micelles represent a promising approach to the creation of boron carrier for BNCT. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

    SciTech Connect

    Lu, Haigang Li, Si-Dian

    2013-12-14

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

  9. The Arabidopsis-related halophyte Thellungiella halophila: boron tolerance via boron complexation with metabolites?

    PubMed

    Lamdan, Netta Li; Attia, Ziv; Moran, Nava; Moshelion, Menachem

    2012-04-01

    Tolerance to boron (B) is still not completely understood. We tested here the hypothesis that Thellungiella halophila, an Arabidopsis thaliana-related 'extremophile' plant, with abundance of B in its natural environment, is tolerant to B, and examined the potential mechanisms of this tolerance. With 1-10 mm B applied ([B](ext)) to Thellungiella and Arabidopsis grown in hydroponics, the steady-state accumulated B concentration ([B](int)) in the root was below [B](ext), and was similar in both, suggesting both extrude B actively. Whether grown in soil or hydroponically, the shoot [B](int) was higher in Arabidopsis than in Thellungiella, suggesting more effective net B exclusion by Thellungiella root. Arabidopsis exhibited toxicity symptoms including reduced shoot fresh weight (FW), but Thellungiella was not affected, even at similar levels of shoot-accumulated [B](int) (about 10 to 40 mm B in 'shoot water'), suggesting additional B tolerance mechanism in Thellungiella shoot. At [B](ext) = 5 mm, the summed shoot concentration of the potentially B-binding polyhydroxyl metabolites (malic acid, fructose, glucose, sucrose and citric acid) in Arabidopsis was below [B](int) , but in Thellungiella it was over twofold higher than [B](int) , and therefore likely to allow appreciable 1:2 boron-metabolite complexation in the shoot. This, we suggest, is an important component of Thellungiella B tolerance mechanism.

  10. Boron isotopes at the Shale Hills Critical Zone Observatory

    NASA Astrophysics Data System (ADS)

    Gaillardet, J.; Noireaux, J.; Sullivan, P. L.; Steinhoefel, G.; Louvat, P.; Brantley, S. L.

    2015-12-01

    The Shale Hills Critical Zone Observatory is a Northern Appalachian catchment site where a series of geochemical tracers have been applied in order to build a multi-isotope integrative model (referred to as "CZ-tope"). The catchment is small (8ha) and relief is about 30 m. It receives about 107 cm of precipitation per year. Mean annual temperature is 10°C. Shales Hills observatory has a relatively simple lithology consisting of organic-poor shales rich in illite and relatively infrequent interbedded carbonates and sandstones. Vegetation consists mainly of deciduous trees. Soil thickness ranges from 0.3 m at the ridgetop to 3 m in the valley floor. Following the CZ-tope concept, boron isotopes were analysed in the main geochemical reservoirs of the SH catchment (stream, vegetation, soil pore waters, solid phases, groundwaters). Measurements were conducted using MC-ICPMS and a direct injection system after a chemical procedure aiming at isolating boron from geological matrix. Results are expressed as δ11B. Error bars are better than 0.5‰ Boron isotopes in Shale Hills catchment show a large range of variation. While bedrock values are within a narrow range around -5‰, stream waters range between 10‰ and 15‰, and exhibit temporal variations. This very strong 11B enrichment is also observed in the vegetation, groundwater and rainwater reservoirs but with a much larger range of variation. The input of 11B-enriched water by precipitation is contributing to the B budget at the catchment outlet but cannot explain all the 11B enrichment with respect to parent bedrock. The solid phases collected along two different soil profiles and as suspended sediments in the stream are close to the bedrock value or slightly 10B-enriched. The most important conclusion from boron isotope investigation at Shale Hills CZO is that a simple mass budget is not able to reconcile the strong 11B-enrichment measured in the water phases and vegetation with the isotopic signature of the

  11. Development of particle induced gamma-ray emission methods for nondestructive determination of isotopic composition of boron and its total concentration in natural and enriched samples.

    PubMed

    Chhillar, Sumit; Acharya, Raghunath; Sodaye, Suparna; Pujari, Pradeep K

    2014-11-18

    We report simple particle induced gamma-ray emission (PIGE) methods using a 4 MeV proton beam for simultaneous and nondestructive determination of the isotopic composition of boron ((10)B/(11)B atom ratio) and total boron concentrations in various solid samples with natural isotopic composition and enriched with (10)B. It involves measurement of prompt gamma-rays at 429, 718, and 2125 keV from (10)B(p,αγ)(7)Be, (10)B(p, p'γ)(10)B, and (11)B(p, p'γ)(11)B reactions, respectively. The isotopic composition of boron in natural and enriched samples was determined by comparing peak area ratios corresponding to (10)B and (11)B of samples to natural boric acid standard. An in situ current normalized PIGE method, using F or Al, was standardized for total B concentration determination. The methods were validated by analyzing stoichiometric boron compounds and applied to samples such as boron carbide, boric acid, carborane, and borosilicate glass. Isotopic compositions of boron in the range of 0.247-2.0 corresponding to (10)B in the range of 19.8-67.0 atom % and total B concentrations in the range of 5-78 wt % were determined. It has been demonstrated that PIGE offers a simple and alternate method for total boron as well as isotopic composition determination in boron based solid samples, including neutron absorbers that are important in nuclear technology.

  12. The noble gases adsorption on boron-rich boron nitride nanotubes: A theoretical investigation

    NASA Astrophysics Data System (ADS)

    Wang, Chong; Guo, Chen

    2017-07-01

    In this work, using density functional theory (DFT) calculations, we have systematically explored the noble gases (Ng = He, Ne, Ar, Kr) adsorption on boron-rich boron nitride nanotubes (BNNTs) surface with antisite boron atom. One or two nitrogen atoms of BNNTs are replaced by boron atoms, which are considered as boron-rich BNNTs for Ng adsorption. It is found that the boron-rich BNNTs can adsorb Ng in exothermic process, and the adsorption energies increase in order from He to Kr. The quantum theory of atoms in molecules (QTAIM) and noncovalent interactions (NCIs) calculations show that the interactions between boron-rich BNNTs and Ng are noncovalent, and the interactions for Ar and Kr are obviously larger than those for He and Ne. The charge transfer from Ng to boron-rich BNNTs and the changes of energy gap caused by Ng adsorption demonstrate that the boron-rich BNNTs are expected to become the Ng adsorption and sensing materials. Moreover, the 2B-BNNTs do not decrease the Ng adsorption interactions on boron-rich BNNTs, compared with 1B-BNNTs. It is expected that the present results will provide a useful guide to develop novel boron nitride nanomaterials for storage and application of Ng.

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

    DOEpatents

    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.

  14. Stopping characteristics of boron and indium ions in silicon

    SciTech Connect

    Veselov, D. S. Voronov, Yu. A.

    2016-12-15

    The mean range and its standard deviation are calculated for boron ions implanted into silicon with energies below 10 keV. Similar characteristics are calculated for indium ions with energies below 200 keV. The obtained results are presented in tabular and graphical forms. These results may help in the assessment of conditions of production of integrated circuits with nanometer-sized elements.

  15. Development of a boron-copper neutron absorber composite

    SciTech Connect

    Wiencek, T.C.; Thresh, H.R.; Summers, J.R.

    1991-05-01

    This report describes the fabrication of a new boron-copper neutron absorbing material that was developed to meet the upgrading needs of the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory. To increase the intensity of the neutron beams from the IPNS, the target uranium was changed from depleted uranium to uranium enriched to 77.5% {sup 235}U. To keep the multiplication factor, k{sub eff} (number of fissions in one generation/number of fissions in preceding generation) at a safe level, a new neutron absorber material was needed. The previous materials, boral and cadmium, could not meet the new requirements and a search of the literature showed that no currently available material was acceptable. With previous powder metallurgy used as a base, the composite was fabricated with 43 vol. % {sup 10}B (81% enriched {sup 10}B) and the balance copper and voids. The powder metallurgy techniques was followed by hot-rolling the composite to a sheet. The material composed of boron particles dispersed in a pure copper matrix and clad with pure copper on both sides, exhibits the following properties: Loadings up to 43 vol. % boron, with the balance copper and voids. A loading of 0.5 {times} 10{sup 22}{sup 10}B atoms/cm{sup 2} in sections as thin as 0.067 in. (1.7 mm), with copper cladding as thin as 0.010 in. (0.25 mm). Formability to radii as small as 2.1 in. (53.3 mm). No observed reaction between boron and the copper matrix and cladding at temperatures up to 900{degrees}C for times as long as 7 h. Retains structural integrity at 900{degrees}C.

  16. Boron Carbide Aluminum Cermets for External Pressure Housing Applications

    DTIC Science & Technology

    1992-09-01

    TABLES 1. Phase chemistry of B4C/A1 composites as a function of baking temperature (by stereology) .................. ...... 10 2. Summary of the...diffractometer using CuKo radiation and a scan rate of 2° per minute. The chemistry of all phases was determined from electron microprobe analysis of... a change in the chemistry of the boron carbide. The depth of the ESCA beam into the surface is only about 50A. Further analysis of the BC powders

  17. Utilization of clay wastes containing boron as cement additives

    SciTech Connect

    Oezdemir, Mine; Oeztuerk, Nese Uygan

    2003-10-01

    The utilization of clay wastes (CW) containing boron as cement additives was investigated. The effect of CW on mechanical and chemical properties of cement prepared by adding CW to clinker and gypsum was determined. The results obtained were compared with Portland cement properties and Turkish standards (TS) values. It was determined that the first clay waste (CW1) and the second clay waste (CW2) may be used as cement additives up to 5% and 10%, respectively.

  18. Crystal structure refinement of reedmergnerite, the boron analog of albite

    USGS Publications Warehouse

    Clark, J.R.; Appleman, D.E.

    1960-01-01

    Ordering of boron in a feldspar crystallographic site T1(0) has been found in reedmergnerite, which has silicon-oxygen and sodium-oxygen distances comparable to those in isostructural low albite. If a simple ionic model is assumed, calculated bond strengths yield a considerable charge imbalance in reedmergnerite, an indication of the inadequacy of the model with respect to these complex structures and of the speculative nature of conclusions based on such a model.

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

    DOEpatents

    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.

  20. The symmetry of the boron buckyball and a related boron nanotube

    NASA Astrophysics Data System (ADS)

    Gonzalez Szwacki, N.; Tymczak, C. J.

    2010-07-01

    We investigate the symmetry of the boron buckyball and a related boron nanotube. Using large-scale ab initio calculations up to second-order Møller-Plesset perturbation theory, we have determined unambiguously the equilibrium geometry/symmetry of two structurally related boron clusters: the B 80 fullerene and the finite-length (5 0) boron nanotube. The B 80 cluster was found to have the same symmetry, Ih, as the C 60 molecule since its 20 additional boron atoms are located exactly at the centers of the 20 hexagons. Additionally, we also show that the (5 0) boron nanotube does not suffer from atomic buckling and its symmetry is D5d instead of C5v as has been described by previous calculations. Therefore, we predict that all the boron nanotubes rolled from the α-sheet will be free from structural distortions, which has a significant impact on their electronic properties.

  1. Nuclear magnetic resonance study of Gd-based nanoparticles to tag boron compounds in boron neutron capture therapy

    SciTech Connect

    Corti, M.; Bonora, 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.

    2011-04-01

    We report the investigation of new organic complexes containing a magnetic moment (Gd-based molecular nanomagnets), which can serve the double purpose of acting as boron neutron capture therapy (BNCT) agents, and at the same time act as contrast agents to detect the molecule in the tissue by a proton magnetic resonance imaging (MRI). We also explore the possibility of monitoring the concentration of the BNCT agent directly via proton and boron NMR relaxation. The absorption of {sup 10}B-enriched molecules inside tumoral liver tissues has been shown by NMR measurements and confirmed by {alpha} spectroscopy. A new molecular Gd-tagged nanomagnet and BNCT agent (GdBPA) has been synthesized and characterized measuring its relaxivity R{sub 1} between 10 kHz and 66 MHz, and its use as a contrast agent in MRI has been demonstrated. The NMR-based evidence of the absorption of GdBPA into living tumoral cells is also shown.

  2. Implantation and Activation of High Concentrations of Boron in Germanium

    SciTech Connect

    Suh,Y.; Carroll, M.; Levy, R.; Sahiner, A.; King, C.

    2005-01-01

    There is renewed interest in the development of Ge-based devices. Implantation and dopant activation are critical process steps for future Ge devices fabrication. Boron is a common p-type dopant, which remarkably is active immediately after implantation in Ge at low doses. This paper examines the effect of increasing dose (i.e., 5/spl times/10/sup 13/-5/spl times/10/sup 16/ cm/sup -2/) and subsequent annealing (400/spl deg/C-800/spl deg/C for 3 h in nitrogen) on activation and diffusion of boron in Ge. Secondary ion mass spectrometry (SIMS), spreading resistance profiling (SRP), high resolution X-ray diffraction (HRXRD), Rutherford backscattering spectrometry (RBS), and nuclear reaction analysis (NRA) are used to characterize the implants before and after annealing. It is found that very high fractions of the boron dose (/spl sim/5%-55%) can be incorporated substitutionally immediately after implantation leading to very high hole concentrations, /spl ges/2/spl times/10/sup 20/ cm/sup -3/, deduced from SRP. Small increases in activation after annealing are observed, however, 100% activation is not indicated by either SRP or NRA. Negligible diffusion after annealing at either 400/spl deg/C or 600/spl deg/C for 3 h was, furthermore, observed.

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

    SciTech Connect

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

    1999-04-01

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

  4. Study of helium embrittlement in boron doped EUROFER97 steels

    NASA Astrophysics Data System (ADS)

    Gaganidze, E.; Petersen, C.; Aktaa, J.

    2009-04-01

    To simulate helium effects in Reduced Activation Ferritic/Martensitic steels, experimental heats ADS2, ADS3 and ADS4 with the basic composition of EUROFER97 (9%Cr-WVTa) were doped with different contents of natural boron and separated 10B-isotope (0.008-0.112 wt.%) and irradiated in High Flux Reactor (HFR) Petten up to 16.3 dpa at 250-450 °C and in Bor-60 fast reactor in Dimitrovgrad up to 31.8 dpa at 332-338 °C. The embrittlement and hardening are investigated by instrumented Charpy-V tests with subsize specimens. Complete burn-up of 10B isotope under neutron irradiation in HFR Petten led to generation of 84, 432 and 5580 appm He and partial boron-to-helium transformation in Bor-60 led to generation of 9, 46, 880 appm He in ADS2, ADS3 and ADS4 heats, respectively. At low irradiation temperatures Tirr ⩽ 340 °C the boron doped steels show progressive embrittlement with increasing helium amount. Irradiation induced DBTT shift of EUROFER97 based heat doped with 1120 wppm separated 10B isotope could not be quantified due to large embrittlement found in the investigated temperature range. At Tirr ⩽ 340 °C helium induced extra embrittlement is attributed to material hardening induced by helium bubbles and described in terms of phenomenological model.

  5. Boron concentration profiling by high angle annular dark field-scanning transmission electron microscopy in homoepitaxial δ-doped diamond layers

    SciTech Connect

    Araújo, D.; Alegre, M. P.; Piñero, J. C.; Fiori, A.; Bustarret, E.; Jomard, F.

    2013-07-22

    To develop further diamond related devices, the concentration and spatial location of dopants should be controlled down to the nanometer scale. Scanning transmission electron microscopy using the high angle annular dark field mode is shown to be sensitive to boron doping in diamond epilayers. An analytical procedure is described, whereby local boron concentrations above 10{sup 20} cm{sup −3} were quantitatively derived down to nanometer resolution from the signal dependence on thickness and boron content. Experimental boron local doping profiles measured on diamond p{sup −}/p{sup ++}/p{sup −} multilayers are compared to macroscopic profiles obtained by secondary ion mass spectrometry, avoiding reported artefacts.

  6. Boron Discovered in Ancient Habitable Mars Groundwater

    SciTech Connect

    Gasda, Patrick

    2016-12-13

    Boron was recently discovered in calcium-sulfate veins on Mars using the ChemCam instrument on NASA’s Curiosity Mars Rover. This is the first Mars mission to detect boron on the Red Planet. Los Alamos Post-Doctoral Student Patrick Gasda explains how this discovery helps us better understand the timescale of habitability on Mars.

  7. Boron Carbides As Thermo-electric Materials

    NASA Technical Reports Server (NTRS)

    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.

  8. Boron chemicals in diagnosis and therapeutics

    PubMed Central

    Das, Bhaskar C; Thapa, Pritam; Karki, Radha; Schinke, Caroline; Das, Sasmita; Kambhampati, Suman; Banerjee, Sushanta K; Van Veldhuizen, Peter; Verma, Amit; Weiss, Louis M; Evans, Todd

    2013-01-01

    Advances in the field of boron chemistry have expanded the application of boron from material use to medicine. Boron-based drugs represent a new class of molecules that possess several biomedical applications including use as imaging agents for both optical and nuclear imaging as well as therapeutic agents with anticancer, antiviral, antibacterial, antifungal and other disease-specific activities. For example, bortezomib (Velcade®), the only drug in clinical use with boron as an active element, was approved in 2003 as a proteasome inhibitor for the treatment of multiple myeloma and non-Hodgkin’s lymphoma. Several other boron-based compounds are in various phases of clinical trials, which illustrates the promise of this approach for medicinal chemists working in the area of boron chemistry. It is expected that in the near future, several boron-containing drugs should become available in the market with better efficacy and potency than existing drugs. This article discusses the current status of the development of boron-based compounds as diagnostic and therapeutic agents in humans. PMID:23617429

  9. Boron chemicals in diagnosis and therapeutics.

    PubMed

    Das, Bhaskar C; Thapa, Pritam; Karki, Radha; Schinke, Caroline; Das, Sasmita; Kambhampati, Suman; Banerjee, Sushanta K; Van Veldhuizen, Peter; Verma, Amit; Weiss, Louis M; Evans, Todd

    2013-04-01

    Advances in the field of boron chemistry have expanded the application of boron from material use to medicine. Boron-based drugs represent a new class of molecules that possess several biomedical applications including use as imaging agents for both optical and nuclear imaging as well as therapeutic agents with anticancer, antiviral, antibacterial, antifungal and other disease-specific activities. For example, bortezomib (Velcade(®)), the only drug in clinical use with boron as an active element, was approved in 2003 as a proteasome inhibitor for the treatment of multiple myeloma and non-Hodgkin's lymphoma. Several other boron-based compounds are in various phases of clinical trials, which illustrates the promise of this approach for medicinal chemists working in the area of boron chemistry. It is expected that in the near future, several boron-containing drugs should become available in the market with better efficacy and potency than existing drugs. This article discusses the current status of the development of boron-based compounds as diagnostic and therapeutic agents in humans.

  10. Porphyrins for boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Gabel, Detlef

    1990-01-01

    Novel compounds for treatment of brain tumors in Boron Neutron Capture Therapy are disclosed. A method for preparing the compounds as well as pharmaceutical compositions containing said compounds are also disclosed. The compounds are water soluble, non-toxic and non-labile boronated porphyrins which show significant uptake and retention in tumors.

  11. Ultratough single crystal boron-doped diamond

    DOEpatents

    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.

  12. Boron neutron capture therapy demonstrated in mice bearing EMT6 tumors following selective delivery of boron by rationally designed liposomes.

    PubMed

    Kueffer, Peter J; Maitz, Charles A; Khan, Aslam A; Schuster, Seth A; Shlyakhtina, Natalia I; Jalisatgi, Satish S; Brockman, John D; Nigg, David W; Hawthorne, M Frederick

    2013-04-16

    The application of boron neutron capture therapy (BNCT) following liposomal delivery of a (10)B-enriched polyhedral borane and a carborane against mouse mammary adenocarcinoma solid tumors was investigated. Unilamellar liposomes with a mean diameter of 134 nm or less, composed of an equimolar mixture of cholesterol and 1,2-distearoyl-sn-glycero-3-phosphocholine and incorporating Na3[1-(2'-B10H9)-2-NH3B10H8] in the aqueous interior and K[nido-7-CH3(CH2)15-7,8-C2B9H11] in the bilayer, were injected into the tail veins of female BALB/c mice bearing right flank EMT6 tumors. Biodistribution studies indicated that two identical injections given 24 h apart resulted in tumor boron levels exceeding 67 µg/g tumor at 54 h--with tumor/blood boron ratios being greatest at 96 h (5.68:1; 43 µg boron/g tumor)--following the initial injection. For BNCT experiments, tumor-bearing mice were irradiated 54 h after the initial injection for 30 min with thermal neutrons, resulting in a total fluence of 1.6 × 10(12) neutrons per cm(2) (±7%). Significant suppression of tumor growth was observed in mice given BNCT vs. control mice (only 424% increase in tumor volume at 14 d post irradiation vs. 1551% in untreated controls). In a separate experiment in which mice were given a second injection/irradiation treatment 7 d after the first, the tumor growth was vastly diminished (186% tumor volume increase at 14 d). A similar response was obtained for mice irradiated for 60 min (169% increase at 14 d), suggesting that neutron fluence was the limiting factor controlling BNCT efficacy in this study.

  13. Boronated mesophase pitch coke for lithium insertion

    NASA Astrophysics Data System (ADS)

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

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

  14. Stabilization of boron carbide via silicon doping.

    PubMed

    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.

  15. Stabilization of boron carbide via silicon doping

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  16. Transition-Metal Planar Boron Clusters: a New Class of Aromatic Compounds with High Coordination

    NASA Astrophysics Data System (ADS)

    Wang, Lai-Sheng

    2012-06-01

    Photoelectron spectroscopy in combination with computational studies over the past decade has shown that boron clusters possess planar or quasi-planar structures, in contrast to that of bulk boron, which is dominated by three-dimensional cage-like building blocks. All planar or quasi-planar boron clusters are observed to consist of a monocyclic circumference with one or more interior atoms. The propensity for planarity has been found to be due to both σ and π electron delocalization throughout the molecular plane, giving rise to concepts of σ and π double aromaticity. We have found further that the central boron atoms can be substituted by transition metal atoms to form a new class of aromatic compounds, which consist of a central metal atom and a monocyclic boron ring (M B_n). Eight-, nine-, and ten-membered rings of boron have been observed, giving rise to octa-, ennea-, and deca-coordinated aromatic transition metal compounds [1-3]. References: [1] ``Aromatic Metal-Centered Monocyclic Boron Rings: Co B_9^- and Ru B_9^-" (Constantin Romanescu, Timur R. Galeev, Wei-Li Li, A. I. Boldyrev, and L. S. Wang), Angew. Chem. Int. Ed. {50}, 9334-9337 (2011). [2] ``Transition-Metal-Centered Nine-Membered Boron Rings: M B_9 and M B_9^- (M = Rh, Ir)" (Wei-Li Li, Constantin Romanescu, Timur R. Galeev, Zachary Piazza, A. I. Boldyrev, and L. S. Wang), J. Am. Chem. Soc. {134}, 165-168 (2012). [3] ``Observation of the Highest Coordination Number in Planar Species: Decacoordinated Ta B10^- and Nb B_9^- Anions" (Timur R. Galeev, Constantin Romanescu, Wei-Li Li, L. S. Wang, and A. I. Boldyrev), Angew. Chem. Int. Ed. {51}, 2101-2105 (2012).

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

    PubMed

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

    2013-08-01

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

  18. Reprocessing of 10B-contaminated 10Be AMS targets

    NASA Astrophysics Data System (ADS)

    Simon, K. J.; Pedro, J. B.; Smith, A. M.; Child, D. P.; Fink, D.

    2013-01-01

    10Be accelerator mass spectrometry (AMS) is an increasingly important tool in studies ranging from exposure age dating and palaeo-geomagnetism to the impact of solar variability on the Earth’s climate. High levels of boron in BeO AMS targets can adversely impact the quality of 10Be measurements through interference from the isobar 10B. Numerous methods in chemical sample preparation and AMS measurement have been employed in order to reduce the impact of excessive boron rates. We present details of a method developed to chemically reprocess a set of forty boron-contaminated BeO targets derived from modern Antarctic ice. Previously, the excessive boron levels in these samples, as measured in an argon-filled absorber cell preceding the ionisation detector, had precluded routine AMS measurement. The procedure involved removing the BeO + Nb mixture from the target holders and dissolving the BeO in hot concentrated H2SO4. The solution was then heated with HF to remove the boron as volatile BF3 before re-precipitating as Be(OH)2 and calcining to BeO. This was again mixed with niobium and pressed into fresh target holders. Following reprocessing, the samples gave boron rates reduced by 10-100×, which were sufficiently low and similar to previous successful batches of ice core, snow and associated blank samples, thus allowing a successful 10Be measurement in the absence of any boron correction. Overall recovery of the BeO for this process averaged 40%. Extensive testing of relevant processing equipment and reagents failed to determine the source of the boron. As a precautionary measure, a similar H2SO4 + HF step has been subsequently added to the standard ice processing method.

  19. Neutron autoradiography imaging of selective boron uptake in human metastatic tumours.

    PubMed

    Altieri, S; Bortolussi, S; Bruschi, P; Chiari, P; Fossati, F; Stella, S; Prati, U; Roveda, L; Zonta, A; Zonta, C; Ferrari, C; Clerici, A; Nano, R; Pinelli, T

    2008-12-01

    The ability to selectively hit the tumour cells is an essential characteristic of an anti-tumour therapy. In boron neutron capture therapy (BNCT) this characteristic is based on the selective uptake of (10)B in the tumour cells with respect to normal tissues. An important step in the BNCT planning is the measurement of the boron concentration in the tissue samples, both tumour and healthy. When the tumour is spread through the healthy tissue, as in the case of metastases, the knowledge of the different kinds of tissues in the sample being analysed is crucial. If the percentage of tumour and normal tissues cannot be evaluated, the obtained concentration is a mean value depending on the composition of the different samples being measured. In this case an imaging method that could give information both on the morphology and on the spatial distribution of boron concentration in the sample would be a fundamental support. In this paper, the results of the boron uptake analysis in the tumour and in the healthy samples taken from human livers after boron phenylalanine (BPA) infusion are shown; boron imaging was performed using neutron autoradiography.

  20. An insight into what superconducts in polycrystalline boron-doped diamonds based on investigations of microstructure

    PubMed Central

    Dubrovinskaia, N.; Wirth, R.; Wosnitza, J.; Papageorgiou, T.; Braun, H. F.; Miyajima, N.; Dubrovinsky, L.

    2008-01-01

    The discovery of superconductivity in polycrystalline boron-doped diamond (BDD) synthesized under high pressure and high temperatures [Ekimov, et al. (2004) Nature 428:542–545] has raised a number of questions on the origin of the superconducting state. It was suggested that the heavy boron doping of diamond eventually leads to superconductivity. To justify such statements more detailed information on the microstructure of the composite materials and on the exact boron content in the diamond grains is needed. For that we used high-resolution transmission electron microscopy and electron energy loss spectroscopy. For the studied superconducting BDD samples synthesized at high pressures and high temperatures the diamond grain sizes are ≈1–2 μm with a boron content between 0.2 (2) and 0.5 (1) at %. The grains are separated by 10- to 20-nm-thick layers and triangular-shaped pockets of predominantly (at least 95 at %) amorphous boron. These results render superconductivity caused by the heavy boron doping in diamond highly unlikely. PMID:18697937

  1. Determination of boron contents in water samples collected from the Neelum valley, Azad Kashmir, Pakistan.

    PubMed

    Akram, Muhammad; Matiullah; Iqbal, Arshid; Husaini, S N; Malik, Fariha

    2011-03-01

    Intake of boron from food and drinking water may pose a risk to the public health above a certain concentration level. Therefore, knowledge of boron concentration in drinking water and food items is essential. In this context, samples of drinking water were collected from natural springs of the Neelum valley, Azad Kashmir, hit by devastating earthquake in 2005. In these samples, boron concentration was determined using neutron-induced radiography technique. To do so, unknown water samples, along with standard of known boron dried on CR-39 detectors, were irradiated with thermal neutrons. After exposure, CR-39 detectors were etched in 6 M NaOH at 70°C. The tracks produced due to the alpha particles and (7)Li ions as a result of (10)B(n,α)(7)Li reaction were counted under an optical microscope. The tracks produced in theses samples were then related to the boron contents. The measured boron concentration in water samples was found to vary from 0.105 ± 0.005 to 0.247 ± 0.013 mg/l with an average value of 0.17 ± 0.04 mg/l, which are within the acceptable limits.

  2. Serum and urinary boron levels in rats after single administration of sodium tetraborate.

    PubMed

    Usuda, K; Kono, K; Orita, Y; Dote, T; Iguchi, K; Nishiura, H; Tominaga, M; Tagawa, T; Goto, E; Shirai, Y

    1998-01-01

    The pharmacokinetics of boron was studied in rats by administering a 1 ml oral dose of sodium tetraborate solution to several groups of rats (n=20) at eleven different dose levels ranging from 0 to 0.4 mg/100 g body weight as boron. Twenty-four-hour urine samples were collected after boron administration. After 24 h the average urinary recovery rate for this element was 99.6+/-7.9. The relationship between boron dose and excretion was linear (r=0.999) with a regression coefficient of 0.954. This result suggests that the oral bioavailability (F) of boron was complete. Another group of rats (n=10) was given a single oral injection of 2 ml of sodium tetraborate solution containing 0.4 mg of boron/100 g body wt. The serum decay of boron was followed and found to be monophasic. The data were interpreted according to a one-compartment open model. The appropriate pharmacokinetic parameters were estimated as follows: absorption half-life, t1/2a=0.608+/-0.432 h; elimination half-life, t1/2=4.64+/-1.19 h; volume of distribution, Vd = 142.0+/-30.2 ml/100 g body wt.; total clearance, Ctot=0.359+/-0.0285 ml/min per 100 g body wt. The maximum boron concentration in serum after administration (Cmax) was 2.13+/-0.270 mg/l, and the time needed to reach this maximum concentration (Tmax) was 1.76+/-0.887 h. Our results suggest that orally administered boric acid is rapidly and completely absorbed from the gastrointestinal tract into the blood stream. Boric acid in the intravascular space does not have a strong affinity to serum proteins, and rapidly diffuses to the extravascular space in proportion to blood flow without massive accumulation or binding in tissues. The main route of boron excretion from the body is via glomerular filtration. It may be inferred that there is partial tubular resorption at low plasma levels. The animal model is proposed as a useful tool to approach the problem of environmental or industrial exposure to boron or in cases of accidental acute boron

  3. Recombination Activity of Iron in Boron Doped Silicon

    NASA Astrophysics Data System (ADS)

    Yli-Koski, M.; Palokangas, M.; Sokolov, V.; Storgårds, J.; Väinölä, H.; Holmberg, H.; Sinkkonen, J.

    The charge carrier lifetime in iron contaminated boron doped silicon wafers was determined by surface photovoltage, SPV, and microwave photoconductive decay, µPCD, techniques. Our results show that the charge carrier lifetime in boron doped silicon wafers depends on the boron concentration when the lifetime is limited by iron-boron pairs.

  4. Estimation of human daily boron exposure in a boron-rich area.

    PubMed

    Korkmaz, Mehmet; Sayli, Uğur; Sayli, Bekir Sitki; Bakirdere, Sezgin; Titretir, Serap; Yavuz Ataman, Osman; Keskin, Siddik

    2007-09-01

    Although, the safe limits of human daily boron (B) exposure are not absolutely clear, there is a growing interest in B and its effects on human health. The aim of the present study was to estimate daily B exposure in 66 males in Turkey living in a B-rich area using water containing at least 2 mg/l boron, with an average age of 38.55 (se 1.66) years and an average number of years of residence in the B-rich area of 35.89 (se 1.73). Another group of males (n 57), living in the city centres of Balikesir and Ankara, were taken as controls; the average age and number of years of residence for this group were 29.44 (se 1.43) and 10.26 (se 1.83) years, respectively. As it is assumed that the B level in urine reflects daily B exposure, the amount of urinary B of both the study and control groups was analysed by using an inductively coupled plasma optical emission spectrometry (ICP-OES) technique. The average daily B exposure value was calculated as 6.77 (se 0.47) mg in the study group and 1.26 (se 0.1) mg in the controls. The results of this study are expected to contribute to creating a reference value for a safe daily B exposure.

  5. New Pathways and Metrics for Enhanced, Reversible Hydrogen Storage in Boron-Doped Carbon Nanospaces

    SciTech Connect

    Pfeifer, Peter; Wexler, Carlos; Hawthorne, M. Frederick; Lee, Mark W.; Jalistegi, Satish S.

    2014-08-14

    This project, since its start in 2007—entitled “Networks of boron-doped carbon nanopores for low-pressure reversible hydrogen storage” (2007-10) and “New pathways and metrics for enhanced, reversible hydrogen storage in boron-doped carbon nanospaces” (2010-13)—is in support of the DOE's National Hydrogen Storage Project, as part of the DOE Hydrogen and Fuel Cells Program’s comprehensive efforts to enable the widespread commercialization of hydrogen and fuel cell technologies in diverse sectors of the economy. Hydrogen storage is widely recognized as a critical enabling technology for the successful commercialization and market acceptance of hydrogen powered vehicles. Storing sufficient hydrogen on board a wide range of vehicle platforms, at energy densities comparable to gasoline, without compromising passenger or cargo space, remains an outstanding technical challenge. Of the main three thrust areas in 2007—metal hydrides, chemical hydrogen storage, and sorption-based hydrogen storage—sorption-based storage, i.e., storage of molecular hydrogen by adsorption on high-surface-area materials (carbons, metal-organic frameworks, and other porous organic networks), has emerged as the most promising path toward achieving the 2017 DOE storage targets of 0.055 kg H2/kg system (“5.5 wt%”) and 0.040 kg H2/liter system. The objective of the project is to develop high-surface-area carbon materials that are boron-doped by incorporation of boron into the carbon lattice at the outset, i.e., during the synthesis of the material. The rationale for boron-doping is the prediction that boron atoms in carbon will raise the binding energy of hydro- gen from 4-5 kJ/mol on the undoped surface to 10-14 kJ/mol on a doped surface, and accordingly the hydro- gen storage capacity of the material. The mechanism for the increase in binding energy is electron donation from H2 to electron-deficient B atoms, in the form of sp2 boron-carbon bonds. Our team is proud to have

  6. Boron- and phosphorus-doped polycrystalline silicon thin films prepared by silver-induced layer exchange

    SciTech Connect

    Antesberger, T.; Wassner, T. A.; Jaeger, C.; Algasinger, M.; Kashani, M.; Scholz, M.; Matich, S.; Stutzmann, M.

    2013-05-27

    Intentional boron and phosphorus doping of polycrystalline silicon thin films on glass prepared by the silver-induced layer exchange is presented. A silver/(titanium) oxide/amorphous silicon stack is annealed at temperatures below the eutectic temperature of the Ag/Si system, leading to a complete layer exchange and simultaneous crystallization of the amorphous silicon. Intentional doping of the amorphous silicon prior to the exchange process results in boron- or phosphorus-doped polycrystalline silicon. Hall effect measurements show carrier concentrations between 2 Multiplication-Sign 10{sup 17} cm{sup -3} and 3 Multiplication-Sign 10{sup 20} cm{sup -3} for phosphorus and 4 Multiplication-Sign 10{sup 18} cm{sup -3} to 3 Multiplication-Sign 10{sup 19} cm{sup -3} for boron-doped layers, with carrier mobilities up to 90 cm{sup 2}/V s.

  7. Synthesis of boron nitride nanotubes from unprocessed colemanite.

    PubMed

    Kalay, Saban; Yilmaz, Zehra; Culha, Mustafa

    2013-01-01

    Colemanite (Ca2B6O11·5H2O) is a natural and new precursor material for the synthesis of boron nitride nanotubes (BNNTs). BNNTs have been synthesized from unprocessed colemanite for the first time. The reaction parameters such as time, catalyst type, catalyst amount and temperature were optimized. It was found that the BNNT formation follows the base growth mechanism, which was initiated with a complex of boron nitride (BN) and iron atoms. The obtained BNNTs were characterized by using SEM, TEM, and spectroscopic techniques such as UV-vis, Raman, FTIR and XRD. The BNNTs were randomly oriented and multi-walled with an outer diameter of 10-30 nm and a wall thickness of 5 nm. This novel BNNT synthesis method can be used to obtain high yield, low cost and pure BNNTs.

  8. Diffusion of copper, aluminum and boron in nickel

    SciTech Connect

    Hasaka, Masayuki; Morimura, Takao; Uchiyama, Yasuo; Kondo, Shinichiro; Furuse, Tatsuji . Dept. of Materials Science and Engineering); Watanabe, Tetsuya . Dept. of Chemical and Biological Engineering); Hisatsune, Kunihiro . Dept. of Dental Materials Science)

    1993-10-01

    Secondary ion mass spectroscopy (SIMS) is a valuable technique for analyzing the distributions of solutes which diffused from the surface to the interior side of metals. The high resolution of SIMS can determine small diffusion coefficients below 10[sup [minus]12] cm[sup 2]/s observed at low temperature, and also measure the diffusion coefficients of various solutes including aluminum and boron isotopes which are not easily available. By means of a radioactive tracer technique, the diffusion coefficients of various solutes in nickel have been measured only at temperature higher than 0.7T[sub m], where T[sub m] is the melting temperature of nickel. With the benefit of SIMS, the present paper investigates the diffusion coefficients of copper, aluminum and boron in the blocks and the melt-spun ribbons of nickel from 0.7T[sub m] to 0.36T[sub m].

  9. Silica - Boronate affinity material for quick enrichment of intracellular nucleosides.

    PubMed

    Wang, Shuxia; Li, Huihui; Guan, Xiujuan; Cheng, Ting; Zhang, Haixia

    2017-05-01

    Boronic acid modified materials have been widely used to adsorb nucleosides, but their adsorption capacities require further improvement. Most cis-diol containing biomolecules are in very low abundance along with interfering components in real samples, and need to be enriched specially. In this study, we synthesize a kind of silica absorbent modified with boronic acid derivative, using amorphous silica as raw material and obtaining high adsorption capacity for adenosine. In addition, the adsorption equilibrium can be completed within 10s and 1min for the desorption. Finally, the material was successfully applied to enrich nucleosides from cells and the spiked recoveries were found between 82.21% and 118.9%. The results showed that the prepared adsorbent has potential to effectively enrich cis-diol substances from cell samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Boron neutron capture therapy demonstrated in mice bearing EMT6 tumors following selective delivery of boron by rationally designed liposomes

    PubMed Central

    Kueffer, Peter J.; Maitz, Charles A.; Khan, Aslam A.; Schuster, Seth A.; Shlyakhtina, Natalia I.; Jalisatgi, Satish S.; Brockman, John D.; Nigg, David W.; Hawthorne, M. Frederick

    2013-01-01

    The application of boron neutron capture therapy (BNCT) following liposomal delivery of a 10B-enriched polyhedral borane and a carborane against mouse mammary adenocarcinoma solid tumors was investigated. Unilamellar liposomes with a mean diameter of 134 nm or less, composed of an equimolar mixture of cholesterol and 1,2-distearoyl-sn-glycero-3-phosphocholine and incorporating Na3[1-(2′-B10H9)-2-NH3B10H8] in the aqueous interior and K[nido-7-CH3(CH2)15-7,8-C2B9H11] in the bilayer, were injected into the tail veins of female BALB/c mice bearing right flank EMT6 tumors. Biodistribution studies indicated that two identical injections given 24 h apart resulted in tumor boron levels exceeding 67 µg/g tumor at 54 h—with tumor/blood boron ratios being greatest at 96 h (5.68:1; 43 µg boron/g tumor)—following the initial injection. For BNCT experiments, tumor-bearing mice were irradiated 54 h after the initial injection for 30 min with thermal neutrons, resulting in a total fluence of 1.6 × 1012 neutrons per cm2 (±7%). Significant suppression of tumor growth was observed in mice given BNCT vs. control mice (only 424% increase in tumor volume at 14 d post irradiation vs. 1551% in untreated controls). In a separate experiment in which mice were given a second injection/irradiation treatment 7 d after the first, the tumor growth was vastly diminished (186% tumor volume increase at 14 d). A similar response was obtained for mice irradiated for 60 min (169% increase at 14 d), suggesting that neutron fluence was the limiting factor controlling BNCT efficacy in this study. PMID:23536304

  11. Boron enrichment in martian clay.

    PubMed

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

    2013-01-01

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

  12. Boron Enrichment in Martian Clay

    PubMed Central

    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

  13. Boron foils for RDDS experiment

    NASA Astrophysics Data System (ADS)

    Lipski, A. R.; Rainovski, G.; Pietralla, N.; Dewald, A.

    2008-06-01

    Application of the deposition method based on the vibrational motion of micro particles in an electrostatic field [I. Sugai, Nucl. Instr. and Meth. A 397 (1997) 81] is described for the production of isotopic 11B foils. The method proved suitable for target production of this typically brittle material when a very flat target surface was required. The goal to produce 11B targets of 160-350 μg/cm 2 was achieved by depositing the boron on a thin foil substrate, such as Nb and Sn. The coated foil was stretched flat before it was mounted on a frame.

  14. Improved Boron for Enhanced Combustion

    DTIC Science & Technology

    1990-06-01

    2, p. 74F - 80F, 1955. 11. Perry and Chilton, " Chemical Engineer ’ Handbook," McGraw-Hill, 5th Edition, 1973, and 6th Edition, 1986. 12. Levenspiel ...0., " Chemical Reaction Engineering ," Wiley & Sons, 2nd Edition, 1972. 13. Hern, R. B, and R. G. Sidall, M. W. Thring, "Flow Patterns in a Phase Change...wet chemical method, allows the use of higher solution concentrations of boron than AAS, provides better precision, and allows us to simultaneously

  15. Hydrocarbon analogues of boron clusters - planarity, aromaticity and antiaromaticity

    NASA Astrophysics Data System (ADS)

    Zhai, Hua-Jin; Kiran, Boggavarapu; Li, Jun; Wang, Lai-Sheng

    2003-12-01

    An interesting feature of elemental boron and boron compounds is the occurrence of highly symmetric icosahedral clusters. The rich chemistry of boron is also dominated by three-dimensional cage structures. Despite its proximity to carbon in the periodic table, elemental boron clusters have been scarcely studied experimentally and their structures and chemical bonding have not been fully elucidated. Here we report experimental and theoretical evidence that small boron clusters prefer planar structures and exhibit aromaticity and antiaromaticity according to the Hückel rules, akin to planar hydrocarbons. Aromatic boron clusters possess more circular shapes whereas antiaromatic boron clusters are elongated, analogous to structural distortions of antiaromatic hydrocarbons. The planar boron clusters are thus the only series of molecules other than the hydrocarbons to exhibit size-dependent aromatic and antiaromatic behaviour and represent a new dimension of boron chemistry. The stable aromatic boron clusters may exhibit similar chemistries to that of benzene, such as forming sandwich-type metal compounds.

  16. Epidermal growth factor (EGF) as a potential targeting agent for delivery of boron to malignant gliomas

    SciTech Connect

    Capala, J.; Barth, R.F.; Adams, D.M.; Bailey, M.Q.; Soloway, A.H.; Carlsson, J.

    1994-12-31

    The majority of high grade gliomas express an amplified epidermal growth factor receptor (EGFR) gene, and this often is associated with an increase in cell surface receptor expression. The rapid internalization and degradation of EGF-EGFR complexes, as well as their high affinity make EGF a potential targeting agent for delivery of {sup 10}B to tumor cells with an amplified number of EGFR. Human glioma cells can expresses as many as 10{sup 5} {minus}10{sup 6} EGF receptors per cell, and if these could be saturated with boronated EGF, then > 10{sup 8} boron atoms would be delivered per cell. Since EGF has a comparatively low molecular weight ({approximately} 6 kD), this has allowed us to construct relatively small bioconjugates containing {approximately} 900 boron atoms per EGF molecule{sup 3}, which also had high affinity for EGFR on tumor cells. In the present study, the feasibility of using EGF receptors as a potential target for therapy of gliomas was investigated by in vivo scintigraphic studies using {sup 131}I{minus} or {sup 99m}{Tc}-labeled EGF in a rat brain tumor model. Our results indicate that intratumorally delivered boron- EGF conjugates might be useful for targeting EGFR on glioma cells if the boron containing moiety of the conjugates persisted intracellularly. Further studies are required, however, to determine if this approach can be used for BNCT of the rat glioma.

  17. Fabrication of vertically aligned diamond whiskers from highly boron-doped diamond by oxygen plasma etching.

    PubMed

    Terashima, Chiaki; Arihara, Kazuki; Okazaki, Sohei; Shichi, Tetsuya; Tryk, Donald A; Shirafuji, Tatsuru; Saito, Nagahiro; Takai, Osamu; Fujishima, Akira

    2011-02-01

    Conductive diamond whiskers were fabricated by maskless oxygen plasma etching on highly boron-doped diamond substrates. The effects of the etching conditions and the boron concentration in diamond on the whisker morphology and overall substrate coverage were investigated. High boron-doping levels (greater than 8.4 × 10(20) cm(-3)) are crucial for the formation of the nanosized, densely packed whiskers with diameter of ca. 20 nm, length of ca. 200 nm, and density of ca. 3.8 × 10(10) cm(-2) under optimal oxygen plasma etching conditions (10 min at a chamber pressure of 20 Pa). Confocal Raman mapping and scanning electron microscopy illustrate that the boron distribution in the diamond surface region is consistent with the distribution of whisker sites. The boron dopant atoms in the diamond appear to lead to the initial fine column formation. This simple method could provide a facile, cost-effective means for the preparation of conductive nanostructured diamond materials for electrochemical applications as well as electron emission devices.

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

    SciTech Connect

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

    2014-11-11

    The quantification of small amounts of boron in materials is of extreme importance in different areas of materials science. Boron is an important contaminant and also a silicon dopant in the semiconductor industry. Boron is also extensively used in nuclear power plants, either for neutron shielding or for safety control and boron is an essential nutrient for life, either vegetable or animal. The production of silicon solar cells, by refining metallurgical-grade silicon (MG-Si) requires the control and reduction of several silicon contaminants to very low concentration levels. Boron is one of the contaminants of solar-grade silicon (SG-Si) that must be controlled and quantified at sub-ppm levels. In the metallurgical purification, boron quantification is usually made by Inductive Coupled Plasma Mass Spectrometry, (ICP-MS) but the results need to be verified by an independent analytical method. In this work we present the results of the analysis of silicon samples by Particle Induced Gamma-Ray Emission (PIGE) aiming the quantification of low concentrations of boron. PIGE analysis was carried out using the in-air external beam line of the Laboratory for Materials Analysis with Ion Beams (LAMFI-USP) by the {sup 10}B(p,αγ({sup 7}Be nuclear reaction, and measuring the 429 keV γ-ray. The in-air PIGE measurements at LAMFI have a quantification limit of the order of 10{sup 16} at/cm{sup 2}.

  19. Thermodynamic and kinetic studies of laser thermal processing of heavily boron-doped amorphous silicon using molecular dynamics

    NASA Astrophysics Data System (ADS)

    Wang, Liguo; Clancy, Paulette; Thompson, Michael O.; Murthy, Cheruvu S.

    2002-09-01

    Laser thermal processing (LTP) has been proposed as a means to avoid unwanted transient enhanced diffusion and deactivation of dopants, especially boron and arsenic, during the formation of ultrashallow junctions. Although experimental studies have been carried out to determine the efficacy of LTP for pure Si and lightly B-doped junctions, the effects of high concentrations of dopants (above 2% B) on the thermodynamic and kinetic properties of the regrown film are unknown. In this study, a classical interatomic potential model [Stillinger-Weber (SW)] is used with a nonequilibrium molecular dynamics computer simulation technique to study the laser thermal processing of heavily B-doped Si in the range 2-10 at. % B. We observe only a small effect of boron concentration on the congruent melting temperature of the B:Si alloy, and thus the narrowing of the "process window" for LTP is predicted to be small. No significant tendency for boron to segregate was observed at either the regrowth front or the buried c-Si interface during fast regrowth. The B-doped region regrew as defect-free crystal with full activation of the boron atoms at low boron concentrations (2%), in good agreement with experiments. As the concentration of boron increased, the number of intrinsic Si defects and boron interstitials in the regrown materials increased, with a minor amount of boron atoms in clusters (<2%). An instability limit for crystal regrowth was observed at around 8%-10% boron atoms during fast regrowth; systems with 10% B showed partial amorphization during regrowth. Comparison with tight-binding quantum mechanical calculations showed that the SW model gives similar diffusivities in the liquid and tendency to cluster, but the lifetimes of the SW clusters are considerably too long (>150 ps, compared to 5 ps in tight binding). The importance of adequate system size is discussed.

  20. The effect of boron additions on irradiation-induced order changes in Ni{sub 3}Al intermetallic compounds

    SciTech Connect

    Njah, N.; Gilbon, D.; Dimitrov, O.

    1995-11-01

    The effects of boron additions (0.1 wt%) on the kinetics of atomic order changes in a Ni{sub 76}Al{sub 24} intermetallic compound, under 1 MeV electron irradiation, were investigated at temperatures of 293 K and 410 K and displacement rates of 0.09 {times} 10{sup {minus}3} to 4.7 {times} 10{sup {minus}3} dpa.s{sup {minus}1}. In these irradiation conditions, a state of residual order was obtained for long irradiation times, characterized by a steady state order parameter S{infinity}; it corresponds to a competition between two opposite features: irradiation disordering and thermal reordering enhanced by irradiation. Boron additions did not affect the efficiency of irradiation-induced disordering: the disordering cross-section (or, equivalently, the number of replacements per displacement {var_epsilon}) were comparable with and without a boron addition. By contrast, the S{infinity} values at 293 K were much lower in the alloy containing boron. Since boron does not change the disordering rate, the large difference between the values obtained in undoped and in boron-doped alloys shows that the reordering rate is strongly reduced by the presence of boron. Thus, boron modifies the mobility of the defects responsible for the irradiation-enhanced diffusion. The data on dislocation-loop size and the reordering kinetics suggest that vacancies are trapped by boron at low temperatures and immobilized, probably by the formation of a boron-vacancy complex. The effect becomes weaker at higher displacement rates and higher temperatures, probably due to the boron-vacancy complexes becoming unstable. It is proposed that two different reordering mechanisms may be operative at 293 K, according to the presence of boron: reordering is promoted by vacancy migration in the Ni{sub 76}Al{sub 24} alloy, whereas in the Ni{sub 76}Al{sub 24} (0.1 wt%B) alloy, it is promoted by the migration of split-interstitials or/and of low-mobility vacancy-boron complexes.

  1. First-principles simulations of boron diffusion in graphite.

    PubMed

    Suarez-Martinez, I; El-Barbary, A A; Savini, G; Heggie, M I

    2007-01-05

    Boron strongly modifies electronic and diffusion properties of graphite. We report the first ab initio study of boron interaction with the point defects in graphite, which includes structures, thermodynamics, and diffusion. A number of possible diffusion mechanisms of boron in graphite are suggested. We conclude that boron diffuses in graphite by a kick-out mechanism. This mechanism explains the common activation energy, but large magnitude difference, for the rate of boron diffusion parallel and perpendicular to the basal plane.

  2. First-Principles Simulations of Boron Diffusion in Graphite

    SciTech Connect

    Suarez-Martinez, I.; El-Barbary, A. A.; Savini, G.; Heggie, M. I.

    2007-01-05

    Boron strongly modifies electronic and diffusion properties of graphite. We report the first ab initio study of boron interaction with the point defects in graphite, which includes structures, thermodynamics, and diffusion. A number of possible diffusion mechanisms of boron in graphite are suggested. We conclude that boron diffuses in graphite by a kick-out mechanism. This mechanism explains the common activation energy, but large magnitude difference, for the rate of boron diffusion parallel and perpendicular to the basal plane.

  3. The measurement of thermal neutron flux depression for determining the concentration of boron in blood.

    PubMed

    Brooke, S L; Green, S; Charles, M W; Beddoe, A H

    2001-03-01

    Boron neutron capture therapy (BNCT) is a form of targeted radiotherapy that relies on the uptake of the capture element boron by the volume to be treated. The treatment procedure requires the measurement of boron in the patient's blood. The investigation of a simple and inexpensive method for determining the concentration of the capture element 10B in blood is described here. This method, neutron flux depression measurement, involves the determination of the flux depression of thermal neutrons as they pass through a boron-containing sample. It is shown via Monte Carlo calculations and experimental verification that, for a maximum count rate of 1 x 10(4) counts/s measured by the detector, a 10 ppm 10B sample of volume 20 ml can be measured with a statistical precision of 10% in 32 +/- 2 min. For a source activity of less than 1.11 x 10(11) Bq and a maximum count rate of less than 1 x 10(4) counts/s, a 10 ppm 10B sample of volume 20 ml can be measured with a statistical precision of 10% in 58 +/- 3 min. It has also been shown that this technique can be applied to the measurement of the concentration of any element with a high thermal neutron cross section such as 157Gd.

  4. High fluence boron implantation into polymers

    NASA Astrophysics Data System (ADS)

    Vacik, J.; Cervena, J.; Fink, D.; Klett, R.; Hnatowicz, V.; Popok, V.; Odzhaev, V.

    100 keV B+ ions are implanted at high fluence into three polymers of technological importance and into a polymeric mixture, respectively. The boron depth distributions are measured by the neutron depth profiling technique. It is shown that the boron atoms redistribute after their implantation according to the nuclear (collisional) energy transfer distribution. This contrasts to low fluence implantation, where the boron atoms redistribute according to their electronic energy transfer distributions. Subsequently, the samples are annealed isochronally. The change of the boron depth profiles with annealing temperature is then evaluated to determine the diffusional, trapping and detrapping behavior of the boron atoms. At, or slightly above room temperature, intrinsic boron impurities of the examined polymer foils become mobile and getter in the ion-implanted region. At higher temperatures, the thermal desorption spectra show a nearly continuous desorption of both the implanted and gettered boron, with no pronounced desorption peaks. Due to the high polymeric destruction yield, the different polymers show little difference in their desorption behavior.

  5. Atomistic study of boron-doped silicon

    SciTech Connect

    Fearn, M.; Pettifor, D.G.; Jefferson, J.H.

    1996-12-31

    Atomistic simulations using both tight-binding and density-functional approaches have been performed to investigate boron-related defects in silicon. In agreement with experiment, the boron interstitial is shown to be a negative-U center in the sense that its neutral charge state, with an associated Jahn-Teller distortion off the ideal tetrahedral site, is never the ground state for any value of the chemical potential in the gap. The possible consequences for an electron-assisted migration of the interstitial are discussed. The authors also find the boron substitutional defect to be a next-nearest neighbor of a silicon vacancy in agreement with EPR spectra. A semi-empirical tight-binding model of the boron-silicon system is validated by direct comparison with the accurate density-functional results and is then used to perform molecular dynamics simulations of boron diffusion at high temperatures. The mobility of the interstitial is found to be strongly charge-state dependent. Termination of the boron interstitial migration path by recombination with a silicon vacancy is shown to be a very likely process with a number of configurations having no barrier to capture when the boron is a near-neighbor of the vacancy.

  6. Where Boron? Mars Rover Detects It

    NASA Image and Video Library

    2016-12-13

    This map shows the route driven by NASA's Curiosity Mars rover (blue line) and locations where the rover's Chemistry and Camera (ChemCam) instrument detected the element boron (dots, colored by abundance of boron according to the key at right). The main map shows the traverse from landing day (Sol 0) in August 2012 to the rover's location in September 2016, with boron detections through September 2015. The inset at upper left shows a magnified version of the most recent portion of that traverse, with boron detections during that portion. Overlapping dots represent cases when boron was detected in multiple ChemCam observation points in the same target and non-overlapping dots represent cases where two different targets in the same location have boron. Most of the mission's detections of boron have been made in the most recent seven months (about 200 sols) of the rover's uphill traverse. The base image for the map is from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. North is up. The scale bar at lower right represents one kilometer (0.62 mile). http://photojournal.jpl.nasa.gov/catalog/PIA21150

  7. Properties of vacuum-evaporated boron films

    NASA Technical Reports Server (NTRS)

    Feakes, F.

    1973-01-01

    The work on the properties of thin boron films made by vacuum evaporation of elemental boron using an electron beam as the energy source is reported. The program aimed at characterizing the properties of vacuum evaporated films. The work was directed toward those variables considered to be important in affecting the tensile strength of the boron films. In general, the thickness of the films was less than 0.002 in. The temperature of the substrate on which the boron was condensed was found to be most important. Three distinctly different forms of boron deposit were produced. Although the transition temperature was not sharply defined, at substrate temperatures of less than approximately 600 deg C the boron deposits were amorphous to X-ray. If the substrate were highly polished, the deposits were black and mirror-like. For substrates with coefficients of thermal expansion close to that of boron, the deposits were then continuous and uncracked. The studies suggest that the potential continues to exist for film-type composites to have both high strength and high modulus.

  8. Boron-Loaded Silicone Rubber Scintillators

    SciTech Connect

    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.

  9. Extraction-spectrophotometric determination of boron with 4,6-Di-tert-butyl-3-methoxycatechol and ethyl violet.

    PubMed

    Oshima, M; Shibata, K; Gyouten, T; Motomizu, S; Tôei, K

    1988-05-01

    4,6-Di-tert-butyl-3-methoxycatechol (DBMC) has been developed as a new reagent for boron, the complex anion formed being extracted as an ion-associate with Ethyl Violet into toluene, and the absorbance measured at 610 nm. The calibration graph is linear up to 0.43 mug of boron, the molar absorptivity is 1.02 x 10(5) 1.mole(-1).cm(-1) and the relative standard deviation 1.2%. The method has been applied to the determination of boron in sea-water and river water with satisfactory results.

  10. Conductivity of boron-doped polycrystalline diamond films: influence of specific boron defects

    NASA Astrophysics Data System (ADS)

    Ashcheulov, P.; Šebera, J.; Kovalenko, A.; Petrák, V.; Fendrych, F.; Nesládek, M.; Taylor, A.; Vlčková Živcová, Z.; Frank, O.; Kavan, L.; Dračínský, M.; Hubík, P.; Vacík, J.; Kraus, I.; Kratochvílová, I.

    2013-10-01

    The resistivity of boron doped polycrystalline diamond films changes with boron content in a very complex way with many unclear factors. From the large number of parameters affecting boron doped polycrystalline diamond film's conductivity we focused on the role of boron atoms inside diamond grains in terms of boron contribution to the continuum of diamond electronic states. Using a combination of theoretical and experimental techniques (plane-wave Density Functional Theory, Neutron Depth Profiling, resistivity and Hall effect measurements, Atomic Force Microscopy and Raman spectroscopy) we studied a wide range of B defect parameters - the boron concentration, location, structure, free hole concentration and mobility. The main goal and novelty of our work was to find the influence of B defects (structure, interactions, charge localisation and spins) in highly B-doped diamonds - close or above the metal-insulator transition - on the complex material charge transport mechanisms.

  11. JAGUAR Procedures for Detonation Behavior of Explosives Containing Boron

    NASA Astrophysics Data System (ADS)

    Stiel, Leonard; Baker, Ernest; Capellos, Christos

    2009-06-01

    The JAGUAR product library was expanded to include boron and boron containing products. Relationships of the Murnaghan form for molar volumes and derived properties were implemented in JAGUAR. Available Hugoniot and static volumertic data were analyzed to obtain constants of the Murnaghan relationship for solid boron, boron oxide, boron nitride, boron carbide, and boric acid. Experimental melting points were also utilized with optimization procedures to obtain the constants of the volumetric relationships for liquid boron and boron oxide. Detonation velocities for HMX - boron mixtures calculated with these relationships using JAGUAR are in closer agreement with literature values at high initial densities for inert (unreacted) boron than with the completely reacted metal. These results indicate that boron mixtures may exhibit eigenvalue detonation behavior, as observed by aluminized combined effects explosives, with higher detonation velocities than would be achieved by a classical Chapman-Jouguet detonation. Analyses of calorimetric measurements for RDX - boron mixtures indicate that at high boron contents the formation of side products, including boron nitride and boron carbide, inhibits the energy output obtained from the detonation of the formulation.

  12. Thermodynamic limitation on boron energy realization in ramjet propulsion

    NASA Astrophysics Data System (ADS)

    Gany, Alon

    2014-05-01

    This study addresses a specific boron combustion aspect, revealing that thermodynamic conditions associated with highly boron-loaded ramjet combustors, may lead to blockage of the reaction between boron and air, causing termination of the combustion process, incomplete chemical reaction, and only partial realization of the potential boron combustion energy. Sustained boron combustion may take place when the evaporation rate of the protective liquid boron oxide layer B2O3(l) on the boron particles exceeds its generation rate by the oxidation reaction, typically at temperatures above 1900-2000 K. However, if the actual partial pressure of gaseous boron oxide B2O3(g) produced in the combustion process attains the equilibrium vapor pressure of boron oxide at the conditions existing in the combustion chamber, condensation of the boron oxide to form a liquid layer on the boron particle surfaces may take place, extinguishing the particle combustion by blocking the reaction between the boron and the surrounding oxidizing gas. The study predicts conditions for blockage and incomplete boron combustion over a range of chamber pressures and temperatures. This effect may be characteristic to combustors employing boron-containing fuels, but may not be encountered in the combustion of individual boron particles in air.

  13. Use of boron cluster-containing redox nanoparticles with ROS scavenging ability in boron neutron capture therapy to achieve high therapeutic efficiency and low adverse effects.

    PubMed

    Gao, Zhenyu; Horiguchi, Yukichi; Nakai, Kei; Matsumura, Akira; Suzuki, Minoru; Ono, Koji; Nagasaki, Yukio

    2016-10-01

    A boron delivery system with high therapeutic efficiency and low adverse effects is crucial for a successful boron neutron capture therapy (BNCT). In this study, we developed boron cluster-containing redox nanoparticles (BNPs) via polyion complex (PIC) formation, using a newly synthesized poly(ethylene glycol)-polyanion (PEG-polyanion, possessing a (10)B-enriched boron cluster as a side chain of one of its segments) and PEG-polycation (possessing a reactive oxygen species (ROS) scavenger as a side chain of one of its segments). The BNPs exhibited high colloidal stability, selective uptake in tumor cells, specific accumulation, and long retention in tumor tissue and ROS scavenging ability. After thermal neutron irradiation, significant suppression of tumor growth was observed in the BNP-treated group, with only 5-ppm (10)B in tumor tissues, whereas at least 20-ppm (10)B is generally required for low molecular weight (LMW) (10)B agents. In addition, increased leukocyte levels were observed in the LMW (10)B agent-treated group after thermal neutron irradiation, and not in BNP-treated group, which might be attributed to its ROS scavenging ability. No visual metastasis of tumor cells to other organs was observed 1 month after irradiation in the BNP-treated group. These results suggest that BNPs are promising for enhancing the BNCT performance.

  14. Combination of boron and gadolinium compounds for neutron capture therapy. An in vitro study.

    PubMed

    Matsumura, A; Zhang, T; Nakai, K; Endo, K; Kumada, H; Yamamoto, T; Yoshida, F; Sakurai, Y; Yamamoto, K; Nose, T

    2005-03-01

    In neutron capture therapy, the therapeutic effect of the boron compound is based on alpha particles produced by the B(n, alpha) reaction while with the gadolinium compound the main radiation effect is from gamma rays derived from the Gd(n, gamma) reaction. The uptake and distribution within the tumor may be different among these compounds. Thus, the combination of the boron and gadolinium compounds may be beneficial for enhancing the radiation dose to the tumor. Chinese hamster fibroblast V79 cells were used. For the neutron targeting compounds, 10B (BSH) at 0, 5, 10, and 15 ppm, and 157Gd (Gd-BOPTA) at 0, 800, 1600, 2400, 3200, and 4800 ppm, were combined. The neutron irradiation was performed with thermal neutrons for 30 min. (neutron flux: 0.84 x 10(8) n/cm2/s in free air). The combination of the boron and gadolinium compounds showed an additive effect when the gadolinium concentration was lower than 1600 ppm. This additive effect decreased as a function of gadolinium concentration at 2400 ppm and resulted in no additive effect at more than 3200 ppm of gadolinium. In conclusion, the combination of the boron and gadolinium compounds can enhance the therapeutic effect with an optimum concentration ratio. When the gadolinium concentration is too high, it may weaken the boron neutron capture reaction due to the high cross-section of gadolinium compound against neutrons.

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

    NASA Astrophysics Data System (ADS)

    Rosenberg, David

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

  16. Boron thermal/epithermal neutron capture therapy

    SciTech Connect

    Fairchild, R.G.

    1982-01-01

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

  17. Comparative effects of daily and weekly boron supplementation on plasma steroid hormones and proinflammatory cytokines.

    PubMed

    Naghii, Mohammad Reza; Mofid, Mahmoud; Asgari, Ali Reza; Hedayati, Mehdi; Daneshpour, Maryam-Saddat

    2011-01-01

    Boron possesses widespread properties in biochemistry and nutrition. Acute supplementation with 11.6 mg of boron resulted in a significant increase in plasma boron concentration. Given such a fast bioavailability, the objective was to determine whether acute (hourly or daily), and weekly supplementation could have any significant biological effects on the steroid hormones and further on some inflammatory biomarkers. Eight healthy male volunteers attended the laboratory on three occasions (days 0, 1 and 7). On the first day (day 0), a blood sample collection at 8.00 A.M was followed by ingestion of placebo with the breakfast. On the next day (supplementation-day 1), similar procedure was followed by ingestion of a capsule containing 10mg of boron. On both occasions blood was collected every 2h for the next 6h. Subjects were requested to consume a capsule of 10mg boron every day with their breakfast, and on the day 7, the blood collection was carried out at 8.00 A.M, again. Boron in plasma increased significantly following hours and weekly consumption. Six hours supplementation showed a significant decrease on sex hormone binding globulin (SHBG), high sensitive CRP (hsCRP) and TNF-α level. After one week (in samples taken at 8.00 A.M, only), the mean plasma free testosterone increased and the mean plasma estradiol decreased significantly. Dihydrotestosterone, cortisol and vitamin D was elevated. Also, concentrations of all three inflammatory biomarkers decreased after supplementation. Of note, despite decreased proinflammatory cytokines, based on recent clinical data, this must be the first human study report to show an increase level of free testosterone after boron consumption.

  18. Crystallization of Beryllium-Boron Metallic Glasses

    SciTech Connect

    Jankowski, A F; Wall, M A; Nieh, T G

    2002-02-14

    Prior studies of evaporation and sputter deposition show that the grain size of pure beryllium can be dramatically refined through the incorporation of metal impurities. Recently, the addition of boron at a concentration greater than 11% is shown to serve as a glassy phase former in sputter deposited beryllium. Presently, thermally induced crystallization of the beryllium-boron metallic glass is reported. The samples are characterized during an in-situ anneal treatment with bright field imaging and electron diffraction using transmission electron microscopy. A nanocrystalline structure evolves from the annealed amorphous phase and the crystallization temperature is affected by the boron concentration.

  19. Boron Nitride Nanoribbons: Synthesis and Future Directions

    NASA Astrophysics Data System (ADS)

    Gibb, Ashley; Erikson, Kris; Sinitskii, Alex; Rousseas, Michael; Alem, Nasim; Tour, James; Zettl, Alex

    2012-02-01

    Boron Nitride Nanoribbons (BNNR) have been theorized to have many interesting electrical and magnetic properties and edge states, but these characteristics have not been experimentally verified due to challenges in synthesis and purification. We have produced BNNRs by longitudinally splitting boron nitride nanotubes (BNNT) using potassium vapor as an intercalant. Due to the strong interactions between boron nitride sheets, separation of nanoribbons from their parent tubes is challenging. We have used various solvent systems to assist with separation of the ribbons with the goal of probing their properties.

  20. Boron distribution in sintered silicon carbide

    SciTech Connect

    Carter, W.D.; Holloway, P.H. ); White, C.; Clausing, R. )

    1988-01-01

    Boron concentrations on intergranular and transgranular fracture areas in sintered SiC were measured; {alpha}-SiC grains oriented parallel to the fracture surface would fracture at the {alpha}-{beta} interphase boundary. Auger electron spectroscopy showed that boron does not segregate to these boundaries in sintered SiC. This conclusion was generalized to include the other types of SiC grain boundaries. The absence of boron at grain boundaries suggests that its role in sintering is not to enhance diffusion rates. Chemical reactions and free surface segregation, which may explain the increased densification of SiC when B is present, are discussed.

  1. Boron Fullerenes: An Electronic Structure Study

    NASA Astrophysics Data System (ADS)

    Sadrzadeh, Arta; Pupysheva, Olga; Boustani, Ihsan; Yakobson, Boris

    2008-03-01

    Using ab initio calculations, we study electronic structure and frequency modes of B80, a member of boron fullerene family made from boron isomorphs of carbon fullerenes with additional atoms in the centers of hexagons. We also investigate geometrical and electronic structural properties of double-rings with various diameters, which are important as building blocks of boron nanotubes, and as the most stable clusters among the studied isomers with no more than 36 atoms. Double-rings also appear as building blocks of B80. Furthermore, we investigate the possibility of further stabilizing some of fullerenes by depleting them.

  2. Developments in boron magnetic resonance imaging (MRI)

    SciTech Connect

    Schweizer, M.

    1995-11-01

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

  3. Boron, Sodium and Chlorine in Mineral Vein Diyogha, Mars

    NASA Image and Video Library

    2016-12-13

    Examination of a calcium sulfate vein called "Diyogha" by the Chemical and Camera (ChemCam) instrument on NASA's Curiosity Mars rover found boron, sodium and chlorine. At left, an image from Curiosity's Mast Camera (Mastcam) shows the context of the pale vein in mudstone of the Murray formation on lower Mount Sharp. A red outline marks the area included in a magnified view, at right, from ChemCam's remote micro-imager. The magnified view is annotated with indicators of boron, sodium and chlorine content detected by ChemCam at individual points hit with the instrument's laser. Targets such as Diyogha indicate that the calcium sulfate veins in the Murray bedrock may have a source that is rich in evaporite minerals. Boron, chlorine and sodium all can be present in evaporites. Diyogha was examined on Sept. 7, 2016, during the 1,454th Martian day, or sol, of Curiosity's work on Mars. The scale bar for the inset is 10.4 millimeters, or about 0.41 inch. The ChemCam image is enhanced with color information from Mastcam. The vein is whiter in the middle due to the dust being blown away by impact of the laser. Point 2 hits a pebble and not the sulfate vein, so its chemistry is not included on the figure. http://photojournal.jpl.nasa.gov/catalog/PIA21252

  4. Boron neutron capture therapy: Moving toward targeted cancer therapy.

    PubMed

    Mirzaei, Hamid Reza; Sahebkar, Amirhossein; Salehi, Rasoul; Nahand, Javid Sadri; Karimi, Ehsan; Jaafari, Mahmoud Reza; Mirzaei, Hamed

    2016-01-01

    Boron neutron capture therapy (BNCT) occurs when a stable isotope, boton-10, is irradiated with low-energy thermal neutrons to yield stripped down helium-4 nuclei and lithium-7 nuclei. It is a binary therapy in the treatment of cancer in which a cytotoxic event is triggered when an atom placed in a cancer cell. Here, we provide an overview on the application of BNCT in cancer therapy as well as current preclinical and clinical evidence on the efficacy of BNCT in the treatment of melanoma, brain tumors, head and neck cancer, and thyroid cancer. Several studies have shown that BNCT is effective in patients who had been treated with a full dose of conventional radiotherapy, because of its selectivity. In addition, BNCT is dependent on the normal/tumor tissue ratio of boron distribution. Increasing evidence has shown that BNCT can be combined with different drug delivery systems to enhance the delivery of boron to cancer cells. The flexibility of BNCT to be used in combination with different tumor-targeting approaches has made this strategy a promising option for cancer therapy. This review aims to provide a state-of-the-art overview of the recent advances in the use of BNCT for targeted therapy of cancer.

  5. Consolidation of cubic and hexagonal boron nitride composites

    SciTech Connect

    Du Frane, W. L.; Cervantes, O.; Ellsworth, G. F.; Kuntz, J. D.

    2015-12-08

    When we Consolidate cubic boron nitride (cBN) it typically requires either a matrix of metal bearing materials that are undesirable for certain applications, or very high pressures within the cBN phase stability field that are prohibitive to manufacturing size and cost. We present new methodology for consolidating high stiffness cBN composites within a hexagonal boron nitride (hBN) matrix (15–25 vol%) with the aid of a binder phase (0–6 vol%) at moderate pressures (0.5–1.0 GPa) and temperatures (900–1300 °C). The composites are demonstrated to be highly tailorable with a range of compositions and resulting physical/mechanical properties. Ultrasonic measurements indicate that in some cases these composites have elastic mechanical properties that exceed those of the highest strength steel alloys. Moreover, two methods were identified to prevent phase transformation of the metastable cBN phase into hBN during consolidation: 1. removal of hydrocarbons, and 2. increased cBN particle size. Lithium tetraborate worked better as a binder than boron oxide, aiding consolidation without enhancing cBN to hBN phase transformation kinetics. These powder mixtures consolidated within error of their full theoretical mass densities at 1 GPa, and had only slightly lower densities at 0.5 GPa. This shows potential for consolidation of these composites into larger parts, in a variety of shapes, at even lower pressures using more conventional manufacturing methods, such as hot-pressing.

  6. Large animal normal tissue tolerance with boron neutron capture

    SciTech Connect

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

    1994-03-30

    Normal tissue tolerance of boron neutron capture irradiation using borocaptate sodium (NA[sub 2]B[sub 12]H[sub 11]SH) in an epithermal neutron beam was studied. Large retriever-type dogs were used and the irradiations were performed by single dose, 5 [times] 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.

  7. Concentrations of boron, molybdenum, and selenium in chinook salmon

    USGS Publications Warehouse

    Hamilton, Steven J.; Wiedmeyer, Raymond H.

    1990-01-01

    The concentrations of boron, molybdenum, and selenium in young chinook salmon Oncorhynchus tshawytscha were determined in three partial life cycle chronic toxicity studies. In each study, fish were exposed to a mixture of boron, molybdenum, selenate, and selenite in the proportions found in subsurface agricultural drainage water in the basin of the San Joaquin Valley, California. Tests were conducted in well water and in site-specific fresh and brackish waters. No boron or molybdenum was detected in fish exposed to concentrations as high as 6,046 μg boron/L and 193 μg molybdenum/L for 90 d in well water or fresh water; however, whole-body concentrations of selenium increased with increasing exposure concentrations in well water and fresh water, but not in brackish water. Concentrations of selenium in chinook salmon were strongly correlated with reduced survival and growth of fish in well water and with reduced survival in a 15-d seawater challenge test of fish from fresh water. Concentrations of selenium in fish seemed to reach a steady state after 60 d of exposure in well water or fresh water. Fish in brackish water had only background concentrations of selenium after 60 d of exposure, and no effects on survival and growth in brackish water or on survival in a 10-d seawater challenge test were exhibited. This lack of effect in brackish water was attributed to initiation of the study with advanced fry, which were apparently better able to metabolize the trace element mixture than were the younger fish used in studies with well water and fresh water. In all three experimental waters, concentration factors (whole-body concentration/waterborne concentration) for selenium decreased with increasing exposure concentrations, suggesting decreased uptake or increased excretion, or both, of selenium at the higher concentrations.

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

    PubMed

    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.

  9. Mathematical modeling of boron diffusion from boron oxide glass film sources

    SciTech Connect

    Yeckel, A.; Middleman, S.

    1988-09-01

    Mathematical models are developed to examine two alternative means of boron doping from boron-rich glass films. For the planar source diffusion system, in which boron diffusion and glass film growth occur simultaneously at high temperature (900-1200/sup 0/C), glass film growth rates and the degree of doping achieved are predicted. In most cases, the solubility limit of boron in silicon is attained at the silicon surface. It is found that depletion of the boron source wafers used in this process may be slowed considerably by their removal from the reactor after a short time. Model predictions for an alternative method, in which the glass film is pregrown at low temperature (300/sup 0/C) and the diffusion subsequently performed at high temperature, demonstrate a strong dependence of the boron surface concentration on the initial boron content in the pregrown glass film, for concentrations of boron near the solubility limit. The conditions for which a masking film of SiO/sub 2/ is insufficient to prevent boron diffusion into silicon, known as mask failure, are also predicted by the models.

  10. Borocaptate sodium: a potential boron delivery compound for boron neutron capture therapy evaluated in dogs with spontaneous intracranial tumors.

    PubMed Central

    Kraft, S L; Gavin, P R; DeHaan, C E; Leathers, C W; Bauer, W F; Miller, D L; Dorn, R V

    1992-01-01

    Borocaptate sodium (Na2B12H11SH) is a boron-carrying compound under consideration for use in boron neutron capture therapy. The biodistribution of boron from borocaptate sodium administration will partly determine boron neutron capture therapy efficacy and normal tissue radiation tolerance. The biodistribution of boron was determined in 30 dogs with spontaneous intracranial tumors at 2, 6, or 12 hr after intravenous borocaptate sodium infusion. Blood and tissue boron concentrations were measured using inductively coupled plasma atomic emission spectroscopy. Mean tumor boron concentration (mean +/- standard error) was 35.9 +/- 4.6 (n = 15), 22.5 +/- 6.0 (n = 9), and 7.0 +/- 1.1 micrograms of boron per g (n = 6) at 2, 6, and 12 hr, respectively, after borocaptate sodium infusion. Peritumor boron concentrations were elevated above that of normal brain in half of the dogs. Normal brain boron concentration (mean +/- standard error) was 4.0 +/- 0.5, 2.0 +/- 0.4, and 2.0 +/- 0.3 micrograms of boron per g at 2, 6, and 12 hr after infusion, respectively. Some cranial and systemic tissues, and blood, had high boron concentration relative to tumor tissue. Geometric dose sparing should partly offset these relatively high normal tissue and blood concentrations. Borocaptate sodium biodistribution is favorable because tumor boron concentrations of recommended magnitude for boron neutron capture therapy were obtained and there was a high tumor-to-normal brain boron concentration ratio. PMID:1465427

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  12. The radiation biology of boron neutron capture therapy.

    PubMed

    Coderre, J A; Morris, G M

    1999-01-01

    Boron neutron capture therapy (BNCT) is a targeted radiation therapy that significantly increases the therapeutic ratio relative to conventional radiotherapeutic modalities. BNCT is a binary approach: A boron-10 (10B)-labeled compound is administered that delivers high concentrations of 10B to the target tumor relative to surrounding normal tissues. This is followed by irradiation with thermal neutrons or epithermal neutrons which become thermalized at depth in tissues. The short range (5-9 microm) of the alpha and 7Li particles released from the 10B(n,alpha)7Li neutron capture reaction make the microdistribution of 10B of critical importance in therapy. The radiation field in tissues during BNCT consists of a mixture of components with differing LET characteristics. Studies have been carried out in both normal and neoplastic tissues to characterize the relative biological effectiveness of each radiation component. The distribution patterns and radiobiological characteristics of the two 10B delivery agents in current clinical use, the amino acid p-boronophenylalanine (BPA) and the sulfhydryl borane (BSH), have been evaluated in a range of normal tissues and tumor types. Considered overall, BSH-mediated BNCT elicits proportionately less damage to normal tissue than does BNCT mediated with BPA. However, BPA exhibits superior in vivo tumor targeting and has proven much more effective in the treatment of brain tumors in rats. In terms of fractionation effects, boron neutron capture irradiation modalities are comparable with other high-LET radiation modalities such as fast-neutron therapy. There was no appreciable advantage in increasing the number of daily fractions of thermal neutrons beyond two with regard to sparing of normal tissue in the rat spinal cord model. The experimental studies described in this review constitute the radiobiological basis for the new BNCT clinical trials for glioblastoma at Brookhaven National Laboratory, at the Massachusetts Institute of

  13. Electroanalysis of tetracycline using nickel-implanted boron-doped diamond thin film electrode applied to flow injection system.

    PubMed

    Treetepvijit, Surudee; Chuanuwatanakul, Suchada; Einaga, Yasuaki; Sato, Rika; Chailapakult, Orawon

    2005-05-01

    The electrochemical analysis of tetracycline was investigated using nickel-implanted boron-doped diamond thin film electrode by cyclic voltammetry and amperometry with a flow injection system. Cyclic voltammetry was used to study the electrochemical oxidation of tetracycline. Comparison experiments were carried out using as-deposited boron-doped diamond thin film electrode (BDD). Nickel-implanted boron-doped diamond thin film electrode (Ni-DIA) provided well-resolved oxidation irreversible cyclic voltammograms. The current signals were higher than those obtained using the as-deposited BDD electrode. Results using nickel-implanted boron-doped diamond thin film electrode in flow injection system coupled with amperometric detection are presented. The optimum potential for tetracycline was 1.55 V versus Ag/AgCl. The linear range of 1.0 to 100 microM and the detection limit of 10 nM were obtained. In addition, the application for drug formulation was also investigated.

  14. Layer speciation and electronic structure investigation of freestanding hexagonal boron nitride nanosheets

    NASA Astrophysics Data System (ADS)

    WangEqual Contribution To This Work., Jian; Wang, Zhiqiang; Cho, Hyunjin; Kim, Myung Jong; Sham, T. K.; Sun, Xuhui

    2015-01-01

    shows more significant detectable contaminants and defects such as tri-coordinated boron/nitrogen oxide. The nitrogen site has shown very weak or no excitonic character. The distinct excitonic effect on boron and nitrogen was interpreted to the partly ionic state of hBN. Bulk XANES of hBN nanosheets was also measured to confirm the spectro-microscopic STXM result. Finally, the unoccupied electronic structures of hBN and graphene were compared. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04445b

  15. Thermal conductivity of ultra-thin chemical vapor deposited hexagonal boron nitride films

    NASA Astrophysics Data System (ADS)

    Alam, M. T.; Bresnehan, M. S.; Robinson, J. A.; Haque, M. A.

    2014-01-01

    Thermal conductivity of freestanding 10 nm and 20 nm thick chemical vapor deposited hexagonal boron nitride films was measured using both steady state and transient techniques. The measured value for both thicknesses, about 100 ± 10 W m-1 K-1, is lower than the bulk basal plane value (390 W m-1 K-1) due to the imperfections in the specimen microstructure. Impressively, this value is still 100 times higher than conventional dielectrics. Considering scalability and ease of integration, hexagonal boron nitride grown over large area is an excellent candidate for thermal management in two dimensional materials-based nanoelectronics.

  16. Boron containing magnetic nanoparticles for neutron capture therapy--an innovative approach for specifically targeting tumors.

    PubMed

    Tietze, Rainer; Unterweger, Harald; Dürr, Stephan; Lyer, Stefan; Canella, Lea; Kudejova, Petra; Wagner, Franz M; Petry, Winfried; Taccardi, Nicola; Alexiou, Christoph

    2015-12-01

    The selective delivery of (10)B into the tumor tissue remains to be further improved for successful and reliable Boron Neutron Capture Therapy applications. Magnetic Drug Targeting using intraarterially administered superparamagnetic nanoparticles and external magnetic fields already exhibited convincing results in terms of highly efficient and selective drug deposition. Using the same technique for the targeted (10)B delivery is a promising new approach. Here, systematic irradiation experiments of phantom cubes containing different concentrations of boron and nanoparticles as well as varying three-dimensional arrangements have been performed.

  17. Fragment approach to the electronic structure of τ -boron allotrope

    NASA Astrophysics Data System (ADS)

    Karmodak, Naiwrit; Jemmis, Eluvathingal D.

    2017-04-01

    The presence of nonconventional bonding features is an intriguing part of elemental boron. The recent addition of τ boron to the family of three-dimensional boron allotropes is no exception. We provide an understanding of the electronic structure of τ boron using a fragment molecular approach, where the effect of symmetry reduction on skeletal bands of B12 and the B57 fragments are examined qualitatively by analyzing the projected density of states of these fragments. In spite of the structural resemblance to β boron, the reduction of symmetry from a rhombohedral space group to the orthorhombic one destabilizes the bands and reduces the electronic requirements. This suggests the presence of the partially occupied boron sites, as seen for a β boron unit cell, and draws the possibility for the existence of different energetically similar polymorphs. τ boron has a lower binding energy than β boron.

  18. Non-boronized compared with boronized operation of ASDEX Upgrade with full-tungsten plasma facing components

    NASA Astrophysics Data System (ADS)

    Kallenbach, A.; Dux, R.; Mayer, M.; Neu, R.; Pütterich, T.; Bobkov, V.; Fuchs, J. C.; Eich, T.; Giannone, L.; Gruber, O.; Herrmann, A.; Horton, L. D.; Maggi, C. F.; Meister, H.; Müller, H. W.; Rohde, V.; Sips, A.; Stäbler, A.; Stober, J.; ASDEX Upgrade Team

    2009-04-01

    After completion of the tungsten coating of all plasma facing components, ASDEX Upgrade has been operated without boronization for 1 1/2 experimental campaigns. This has allowed the study of fuel retention under conditions of relatively low D co-deposition with low-Z impurities as well as the operational space of a full-tungsten device for the unfavourable condition of a relatively high intrinsic impurity level. Restrictions in operation were caused by the central accumulation of tungsten in combination with density peaking, resulting in H-L backtransitions induced by too low separatrix power flux. Most important control parameters have been found to be the central heating power, as delivered predominantly by ECRH, and the ELM frequency, most easily controlled by gas puffing. Generally, ELMs exhibit a positive impact, with the effect of impurity flushing out of the pedestal region overbalancing the ELM-induced W source. The restrictions of plasma operation in the unboronized W machine occurred predominantly under low or medium power conditions. Under medium-high power conditions, stable operation with virtually no difference between boronized and unboronized discharges was achieved. Due to the reduced intrinsic radiation with boronization and the limited power handling capability of VPS coated divertor tiles (≈10 MW m-2), boronized operation at high heating powers was possible only with radiative cooling. To enable this, a previously developed feedback system using (thermo-)electric current measurements as approximate sensor for the divertor power flux was introduced into the standard AUG operation. To avoid the problems with reduced ELM frequency due to core plasma radiation, nitrogen was selected as radiating species since its radiative characteristic peaks at lower electron temperatures in comparison with Ne and Ar, favouring SOL and divertor radiative losses. Nitrogen seeding resulted not only in the desired divertor power load reduction but also in improved

  19. Mg-doping experiment and electrical transport measurement of boron nanobelts

    SciTech Connect

    Kirihara, K. . E-mail: kz-kirihara@aist.go.jp; Hyodo, H.; Fujihisa, H.; Wang, Z.; Kawaguchi, K.; Shimizu, Y.; Sasaki, T.; Koshizaki, N.; Soga, K.; Kimura, K.

    2006-09-15

    We measured electrical conductance of single crystalline boron nanobelts having {alpha}-tetragonal crystalline structure. The doping experiment of Mg was carried out by vapor diffusion method. The pure boron nanobelt is a p-type semiconductor and its electrical conductivity was estimated to be on the order of 10{sup -3} ({omega} cm){sup -1} at room temperature. The carrier mobility of pure boron nanobelt was measured to be on the order of 10{sup -3} (cm{sup 2} Vs{sup -1}) at room temperature and has an activation energy of {approx}0.19 eV. The Mg-doped boron nanobelts have the same {alpha}-tetragonal crystalline structure as the pristine nanobelts. After Mg vapor diffusion, the nanobelts were still semiconductor, while the electrical conductance increased by a factor of 100-500. Transition to metal or superconductor by doping was not observed. - Graphical abstract: SEM micrographs of boron nanobelt after Ni/Au electrode fabrication by electron beam lithography. Display Omitted.

  20. Boron Filled Siloxane Polymers for Radiation Shielding

    DOE PAGES

    Labouriau, Andrea; Robison, Tom; Shonrock, Clinton Otto; ...

    2017-09-01

    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,more » 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. In conclusion, 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.« less

  1. Boron-Filled Hybrid Carbon Nanotubes.

    PubMed

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

    2016-07-27

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

  2. Boron-Filled Hybrid Carbon Nanotubes

    PubMed Central

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

    2016-01-01

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

  3. Ni doping of semiconducting boron carbide

    SciTech Connect

    Hong, Nina; Liu Jing; Adenwalla, S.; Langell, M. A.; Kizilkaya, Orhan

    2010-01-15

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

  4. Bipolaron Hopping Conduction in Boron Carbides

    SciTech Connect

    ASELAGE, TERRENCE L.; EMIN, D.; MCCREADY, STEVEN S.

    1999-09-20

    The electrical conductivities of boron carbides, B{sub 12+x}C{sub 3{minus}x} with 0.1 < x < 1.7, between 300 and 1200K suggest the hopping of a nearly temperature-independent density of small (bi)polarons. The activation energies of the nobilities are low, {approx} 0.16 eV, and are nearly independent of the composition. At lower temperatures, conductivities have non-Arrhenius temperature dependencies and strong sensitivity to carbon concentration. Percolative aspects of low-temperature hopping are evident in this sensitivity to composition. Boron carbides' Seebeck coefficients are anomalous in that (1) they are much larger than expected from boron carbides' large carrier densities and (2) they depend only weakly on the carrier density. Carrier-induced softening of local vibrations gives contributions to the Seebeck coefficient that mirror the magnitudes and temperature dependencies found in boron carbides.

  5. Boron strengthening in FeAl

    SciTech Connect

    Baker, I.; Li, X.; Xiao, H.; Klein, O.; Nelson, C.; Carleton, R.L.; George, E.P.

    1998-11-01

    The effect of boron on the strength of B2-structured FeAl is considered as a function of composition, grain size and temperature. Boron does not affect the concentrations of antisite atoms or vacancies present, with the former increasing and the latter decreasing with increasing deviation from the stoichiometric composition. When vacancies are absent, the strength increase per at. % B per unit lattice strain, {Delta}{sigma}/({Delta}c x {epsilon}) increases with increasing aluminum concentration, but when vacancies are present (>45 at. % Al), {Delta}{sigma}/({Delta}c x {epsilon}) decreases again. Boron increases grain size strengthening in FeAl. B strengthening is roughly independent of temperature up to the yield strength peak but above the point, when diffusion-assisted deformation occurs, boron strengthening increases dramatically.

  6. New approach to obtain boron selective emitters

    SciTech Connect

    Moehlecke, A.; Luque, A.

    1994-12-31

    Selective emitters, used in high efficiency solar cells, need a series of oxidations and photolithographic steps that render the process more expensive. In this paper, a new way to make selective emitters using boron is presented. The main feature of this approach is to save oxide growths and photolithographic processes and it is based on the property of boron doped silicon surfaces to be resistant to anisotropic etchings like the one performed during the texturization. Using this characteristic of boron emitter surfaces, the authors can obtain a highly doped emitter under metal grid and simultaneously a shield to avoid texture on these surfaces. First cells were processed and short wavelength response of p{sup +}nn{sup +} solar cells was enhanced by using lightly doped boron emitters in the uncovered area.

  7. Alternative Process for Manufacturing of Thin Layers of Boron for Neutron Measurement

    SciTech Connect

    Auge, Gregoire; Partyka, Stanislas; Guerard, Bruno; Buffet, Jean-Claude

    2015-07-01

    Due to the worldwide shortage of helium 3, Boron-lined proportional counters are developed intensively by several groups. Up to now, thin boron containing layers for neutron detectors are essentially produced by sputtering of boron carbide (B{sub 4}C). This technology provides high quality films but it is slow and expensive. Our paper describes a novel and inexpensive technology for producing boron layers. This technology is based on chemical synthesis of boron 10 nanoparticles, and on electrophoretic deposition of these particles on metallic plates, or on metallic pieces with more complex shapes. The chemical synthesis consists in: - Heating boron 10 with lithium up to 700 deg. C under inert atmosphere: an intermetallic compound, LiB, is produced; - Hydrolysing this intermetallic compound: LiB + H{sub 2}O → B + Li{sup +} + OH{sup -} + 1/2H{sub 2}, where B is under the form of nanoparticles; - Purifying the suspension of boron nanoparticles in water, from lithium hydroxide, by successive membrane filtrations; - Evaporating the purified suspension, in order to get a powder of nanoparticles. The obtained nanoparticles have size around 300 nm, with a high porosity, of about 50%. This particle size is equivalent to about 150 nm massive particles. The nanoparticles are then put into suspension in a specific solvent, in order to perform deposition on metallic surfaces, by electrophoretic method. The solvent is chosen so that it is not electrolysed even under voltages of several tens of volts. An acid is dissolved into the solvent, so that the nanoparticles are positively charged. Deposition is performed on the cathode within about 10 min. The cathode could be an aluminium plate, or a nickel coated aluminium plate. Homogeneous deposition may also be performed on complex shapes, like grids in a Multigrid detector. A large volume of pieces, can be coated with a Boron-10 film in a few hours. The thickness of the layer can be adjusted according to the required neutron

  8. Critical boron-doping levels for generation of dislocations in synthetic diamond

    SciTech Connect

    Alegre, M. P. Araújo, D.; Pinero, J. C.; Lloret, F.; Villar, M. P.; Fiori, A.; Achatz, P.; Chicot, G.; Bustarret, E.; Jomard, F.

    2014-10-27

    Defects induced by boron doping in diamond layers were studied by transmission electron microscopy. The existence of a critical boron doping level above which defects are generated is reported. This level is found to be dependent on the CH{sub 4}/H{sub 2} molar ratios and on growth directions. The critical boron concentration lied in the 6.5–17.0 × 10{sup 20}at/cm{sup 3} range in the 〈111〉 direction and at 3.2 × 10{sup 21 }at/cm{sup 3} for the 〈001〉 one. Strain related effects induced by the doping are shown not to be responsible. From the location of dislocations and their Burger vectors, a model is proposed, together with their generation mechanism.

  9. Formation of c-BN nanoparticles by helium, lithium and boron ion implantation

    NASA Astrophysics Data System (ADS)

    Aradi, Emily; Erasmus, Rudolph M.; Derry, Trevor E.

    2012-02-01

    Ion induced phase transformation from the soft graphitic hexagonal boron nitride ( h-BN) to ultrahard cubic boron nitride ( c-BN) nanoparticles is presented in the work herein. Ion implantation was used as a technique to introduce boron lithium and helium ions, at the energy of 150 keV and fluences ranging from 1 × 10 14 to 1 × 10 16 ions/cm 2, into hot pressed, polycrystalline h-BN. Analyses using Raman Spectroscopy showed that He +, Li + and B + led to a h-BN to c-BN phase transition, evident from the longitudinal optical (LO) Raman phonon features occurring in the implanted samples' spectra. The nature of these phonon peaks and their downshifting is explained using the spatial phonon correlation model.

  10. Large diameter carbon-boron fiber

    NASA Technical Reports Server (NTRS)

    Veltri, R. D.; Jacob, B. A.; Galasso, F. S.

    1975-01-01

    Investigations concerned with a development of large-diameter carbon fibers are considered, taking into account the employment of vapor deposition techniques. In the experiments a carbon monofilament substrate is used together with reacting gases which consist of combinations of hydrogen, methane, and boron trichloride. It is found that the described approach can be used to obtain a large-diameter carbon filament containing boron. The filament has reasonable strength and modulus properties.

  11. Formose reaction controlled by boronic acid compounds

    PubMed Central

    Imai, Toru; Michitaka, Tomohiro

    2016-01-01

    Formose reactions were carried out in the presence of low molecular weight and macromolecular boronic acid compounds, i.e., sodium phenylboronate (SPB) and a copolymer of sodium 4-vinylphenylboronate with sodium 4-styrenesulfonate (pVPB/NaSS), respectively. The boronic acid compounds provided different selectivities; sugars of a small carbon number were formed favorably in the presence of SPB, whereas sugar alcohols of a larger carbon number were formed preferably in the presence of pVPB/NaSS. PMID:28144337

  12. Boronate-tau mediated uptake in neurons.

    PubMed

    Pérez, Mar; Cuadros, Raquel; Pallas-Bazarra, Noemi; García, Carlos; Langa, Elena; Jurado-Arjona, Jerónimo; Hernández, Félix; Avila, Jesús

    2014-01-01

    We modified tau protein with boronic acid to facilitate its delivery into non neural or neural cultured cells lacking tau protein. Our results indicate that the incorporated tau promotes the formation of cytoplasmic extensions in non-neuronal cells, as well as the appearance of neurites in cultured tau knockout hippocampal neurons. In addition, boronated tau is incorporated into hippocampal neurons of tau knockout mice after intracranial injection in vivo. These findings describe a novel method to deliver exogenous tau protein into cells.

  13. Abrasive slurry composition for machining boron carbide

    DOEpatents

    Duran, E.L.

    1984-11-29

    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.

  14. Abrasive slurry composition for machining boron carbide

    DOEpatents

    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.

  15. Method of synthesizing enriched decaborane for use in generating boron neutron capture therapy pharmaceuticals

    DOEpatents

    Cowan, Robert L.; Ginosar, Daniel M.; Dunks, Gary B.

    2000-01-01

    A method is described for synthesizing decaborane wherein at least about 90% of the boron atoms in the decaborane are the .sup.10 B isotope, comprising the steps of: (a) reacting boric acid with a C.sub.1 to C.sub.10 alkanol to form a .sup.10 B-alkyl borate wherein at least about 90% of the boron atoms in the boric acid are the .sup.10 B isotope; (b) reducing the .sup.10 B-alkyl borate to form an alkali metal .sup.10 B-borohydride; (c) converting the alkali metal .sup.10 B-borohydride to a .sup.10 B-tetradecahydroundecaborate ion; and (d) converting the .sup.10 B-tetradecahydroundecaborate ion to .sup.10 B-decaborane. Methods of preparing tetradecahydroundecaborate ions and decaborane from alkali metal borohydrides are also described.

  16. Boron supplementation improves bone health of non-obese diabetic mice.

    PubMed

    Dessordi, Renata; Spirlandeli, Adriano Levi; Zamarioli, Ariane; Volpon, José Batista; Navarro, Anderson Marliere

    2017-01-01

    Diabetes Mellitus is a condition that predisposes a higher risk for the development of osteoporosis. The objective of this study was to investigate the influence of boron supplementation on bone microstructure and strength in control and non-obese diabetic mice for 30days. The animals were supplemented with 40μg/0,5ml of boron solution and controls received 0,5ml of distilled water daily. We evaluated the biochemical parameters: total calcium, phosphorus, magnesium and boron; bone analysis: bone computed microtomography, and biomechanical assay with a three point test on the femur. This study consisted of 28 animals divided into four groups: Group water control - Ctrl (n=10), Group boron control - Ctrl±B (n=8), Group diabetic water - Diab (n=5) and Group diabetic boron - Diab±B (n=5). The results showed that cortical bone volume and the trabecular bone volume fraction were higher for Diab±B and Ctrl±B compared to the Diab and Ctrl groups (p≤0,05). The trabecular specific bone surface was greater for the Diab±B group, and the trabecular thickness and structure model index had the worst values for the Diab group. The boron serum concentrations were higher for the Diab±B group compared to non-supplemented groups. The magnesium concentration was lower for Diab and Diab±B compared with controls. The biomechanical test on the femur revealed maintenance of parameters of the bone strength in animals Diab±B compared to the Diab group and controls. The results suggest that boron supplementation improves parameters related to bone strength and microstructure of cortical and trabecular bone in diabetic animals and the controls that were supplemented.

  17. Boron

    SciTech Connect

    Cozen, L.F. )

    1991-05-01

    This paper reports that borate minerals and refined borates are used extensively for the manufacture of vitreous materials such as insulation and textile fiberglasses, borosilicate glass, and porcelain enamels and frits. In North America, these applications are estimated to account for over 54% of the borate consumption. Other substantial uses are in soaps and detergents, metallurgy, fire retardants, industrial biocides, agriculture, and various miscellaneous applications. Reported domestic borate consumption in 1990 was estimated by the U.S. Bureau of Mines to be 320 000 metric tons B{sub 2}O{sub 3} versus 354 000 metric tons B{sub 2}O{sub 3} in 1989. Consumption is projected to remain essentially static in 1991. Imports were estimated by the Bureau to be 50 000 metric tons B{sub 2}O{sub 3} in 1990. Exports of boric acid and refined borates were approximately 650 000 metric tons of product, a 15 000 metric ton increase from the 1989 level. This increase partially offsets the drop in the 1990 consumption level.

  18. The abundance of boron in diffuse interstellar clouds

    NASA Astrophysics Data System (ADS)

    Ritchey, Adam M.

    The origins of the stable isotopes of boron remain uncertain despite much theoretical and observational effort. Spallation reactions between relativistic Galactic cosmic rays (GCR) and interstellar nuclei can adequately account for the production of 10 B and contribute to the cosmic abundance of 11 B. However, an additional source of 11 B synthesis is required to raise the isotopic ratio of 11 B/ 10 B from its GCR spallation value (2.4) to the value measured in carbonaceous chondrites (4.0). The n-process, neutrino-induced spallation in Type II supernovae, is a potentially significant source of 11 B production. Since neutrino-induced spallation does not result in substantial yields for 10 B, this process could naturally explain the enhancement in 11 B/ 10 B over the predictions of standard GCR spallation. Without the n-process, enhanced 11 B production, relative to 10 B, could be attributed to an increased flux of low- energy (5-40 MeV nucleon -1 ) cosmic rays, which are unobservable from Earth due to magnetic shielding by the solar wind. In this thesis, I present a comprehensive survey of boron abundances in diffuse interstellar clouds from Space Telescope Imaging Spectrograph (STIS) observations made with the Hubble Space Telescope in an effort to identify the sources responsible for light element nucleosynthesis. The present sample of 56 Galactic sight lines is the result of a complete search of archival STIS data for the B II l1362 resonance line. Each detection is confirmed by the presence of absorption due to O I l1355, Cu II l1358, and Ga II l1414 (when available) at the same velocity. Like B + , these species represent the dominant ionization stage of their element in neutral diffuse clouds and therefore should coexist. Profile templates based on synthesized absorption profiles of O I, Cu II, and Ga II are fitted to the B II line, yielding the total boron column density along each line of sight. By synthesizing B II profiles with components seen in high

  19. Amorphous boron nitride at high pressure

    NASA Astrophysics Data System (ADS)

    Durandurdu, Murat

    2016-06-01

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

  20. Effects of ball milling and sintering on alumina and alumina-boron compounds

    NASA Astrophysics Data System (ADS)

    Cross, Thomas

    Alumina has a wide variety of applications, but the processing of alumina based materials can be costly. Mechanically milling alumina has been shown to enhance the sintering properties while decreasing the sintering temperature. Additions of boron have also proven to increase sintering properties of alumina. These two processes, mechanical milling and boron additions, will be combined to test the sintering properties and determine if they are improved upon even further compared to the individual processes. Multiple samples of pure alumina, 0.2 weight percent boron, and 1.0 weight percent boron are batched and processed in a ball mill for different time intervals. These samples are then characterized to observe the structure and properties of the samples after milling but before sintering. Pellets are dry pressed from the milled powders, sintered at 1200°C for one to 10 hours, and characterized to determine the impact of processing. X-ray diffractometry (XRD) was used on each sample to determine crystallite size and lattice parameters at different stages throughout the experiment. XRD was also used to identify any samples with an aluminum borate phase. Scanning electron microscopy (SEM) was used to observe the powder and pellet morphology and to measure bulk chemical composition. Samples were sputter coated with an Au-Pd coating observed in the SEM to characterize the topography as a function of variables such as milling time, boron composition, and sintering time. Additionally, porosity and change in diameter were measured to track the sintering process. Milling sample for longer periods of time would be unnecessary due to the crystallite size leveling off between 10 and 12 hours of milling time. Samples of alumina with 0.2 weight percent boron prove to have very little effect on the sintering properties. At 1.0 weight percent boron, there are changes in diffraction patterns and topography after being sintered for one hour. The porosities of all of the sintered