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Sample records for boron 10

  1. Boron-10 ABUNCL Models of Fuel Testing

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-10-01

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

  2. Boron-10 ABUNCL Prototype Initial Testing

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-12-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-07-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-04-23

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

  7. 10B and 11B high-resolution NMR studies on boron-doped diamond

    Science.gov (United States)

    Murakami, M.; Shimizu, T.; Tansho, M.; Takano, Y.; Ishii, S.; Ekimov, E. A.; Sidorov, V. A.; Takegoshi, K.

    2010-12-01

    11B magic-angle spinning (MAS) NMR experiments are applied to B-doped diamond samples prepared by high-pressure and high-temperature methods. From the spectrum, we show that there are at least four boron signal components and the one at 28.5 ppm is ascribed to the substitutional boron in the diamond structure providing the carriers responsible for conductivity. We further apply two-dimensional (2D) NMR to examine 1H dipolar broadening and 11B-11B boron spin diffusion, and candidates purported so far for the excess boron, that is, a boron + hydrogen complex and -B-B- and/or -B-C-B- clusters are negated. Furthermore, we show that 10B MAS NMR is useful to selectively observe the substitutional boron in the diamond structure appearing at 28.5 ppm, whose quadrupolar coupling is much smaller than that of the excess boron at 65.5 ppm.

  8. {sup 1}H and {sup 10}B NMR and MRI investigation of boron- and gadolinium-boron compounds in boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Bonora, M., E-mail: marco.bonora@unipv.it [Physics Department ' A. Volta' , University of Pavia, Via Bassi 6, 27100 Pavia (Italy)] [CNISM Unit (Italy); Corti, M.; Borsa, F. [Physics Department ' A. Volta' , University of Pavia, Via Bassi 6, 27100 Pavia (Italy)] [CNISM Unit (Italy); Bortolussi, S.; Protti, N.; Santoro, D.; Stella, S.; Altieri, S. [Nuclear and Theoretical Physics Department, University of Pavia, Via Bassi 6, 27100 Pavia (Italy)] [INFN Pavia (Italy); Zonta, C.; Clerici, A.M.; Cansolino, L.; Ferrari, C.; Dionigi, P. [Surgical Sciences Department, Experimental Surgery Laboratory, University of Pavia, Pavia (Italy); Porta, A.; Zanoni, G.; Vidari, G. [Organic Chemistry Department, University of Pavia, Via Taramelli 10, 27100 Pavia (Italy)

    2011-12-15

    {sup 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 {sup 1}H and {sup 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.

  9. Boron-10 prompt gamma analysis using a diffracted neutron beam

    International Nuclear Information System (INIS)

    A prompt gamma neutron activation analysis (PGNAA) facility has been built at the 5 MW MITR-II Research Reactor to support the ongoing boron neutron capture therapy (NCT) program. This facility is used to determine the concentration of B-10 in NCT relevant samples such as blood and urine. The B-10 concentration is needed to determine the radiation doses that tumor and healthy brain receive during neutron irradiation of a patient. Assaying for B-10 by PGNAA has several advantages over conventional chemical methods. It is rapid, accurate, nondestructive (allowing for re-analysis), inexpensive, sensitive (ppm level), generally independent of the chemical or physical matrix of the B-10, and does not require chemical manipulations of the sample. The authors goal was to build an inexpensive facility with a suitably high thermal neutron flux for PGNAA and a low level of photon and fast neutron contamination. Their design is unique in that it uses a diffracted beam. Most prompt gamma facilities use direct beams; these beams have a high thermal flux (> 107 n/cm2-sec), but are heavily contaminated with protons and fast neutrons. Other prompt gamma facilities use totally reflecting guide tubes; these beams have little contamination, but are expensive. The high thermal flux of direct beam facilities might not be an advantage since the detector usually must be moved further away from the sample to avoid high dead times in the multichannel analyzer

  10. Boron-10 layers, Neutron Reflectometry and Thermal Neutron Gaseous Detectors

    CERN Document Server

    Piscitelli, Francesco

    2014-01-01

    Nowadays neutron facilities are going toward higher fluxes, e.g. the European Spallation Source (ESS) in Lund (Sweden), and this translates into a higher demand in the instrument performances. Because of its favorable properties,He-3 has been the main actor in thermal neutron detection for years. Starting in about 2001 the He-3 stockpile has been declining. The world is now experiencing the shortage of He-3. This makes the construction of large area detectors (several squared meters) not realistic anymore. A way to reduce the He-3 demand for those applications is to move users to alternative technologies, such as Boron-10. Although it is absolutely necessary to replace He-3 for large area applications, this is not the main issue for what concerns small area detectors for which the research is focused on improving their performances. Some technologies appear promising, though implementation would likely present technical challenges. There are several aspects that must be investigated in order to validate those...

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

    CERN Document Server

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

    2016-01-01

    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 boron-10 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...

  12. Boron

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-01-22

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

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

    International Nuclear Information System (INIS)

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

  15. Continuous measurement of boron-10 concentration in rabbit brain tissue and blood using prompt gamma-ray spectrometry

    International Nuclear Information System (INIS)

    One of the important factors which influence the efficacy of boron neutron capture therapy (BNCT) in patients with malignant brain tumor is the boron-10 concentrations in tumors. The boron-10 concentration in normal brain tissue and the tumor/blood concentration in normal brain tissue and the tumor/blood concentration ratio are also valuable factors to decide the irradiation time and protect the normal tissue from radiation injury. Therefore, it is valuable to know the boron-10 concentration in the tumor, normal brain tissue and blood just before and during neutron irradiation. In this study the authors investigated continuously the boron-10 concentrations in the normal brain tissue of living rabbits and blood for 5-24 hours after injection of boron-10 compound using prompt gamma-ray spectrometry

  16. Analysis of boron concentration deviation and 10B abundance evolution in primary loop of pressurized nuclear plants

    International Nuclear Information System (INIS)

    The 10B abundance evolution under two conditions, i.e., with and without boronizing, is calculated and analyzed with theoretical derivation method, and the evolution pattern of 10B abundance for one cycle in PWR is provided. The comparison of the calculated and measured 10B abundance shows that the abundance equation considering the boronizing is accurate. With this, the theoretical boron concentration provided by the fuel management software can be corrected and validated. According to the equation and analysis method, the boron concentration deviation problem could be well understood or even solved. (authors)

  17. Electroextraction of boron from boron carbide scrap

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-10-15

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

  18. Electroextraction of boron from boron carbide scrap

    International Nuclear Information System (INIS)

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

  19. A suggestion for B-10 imaging during boron neutron capture therapy

    OpenAIRE

    Cortesi, M.

    2007-01-01

    Selective accumulation of B-10 compound in tumour tissue is a fundamental condition for the achievement of BNCT (Boron Neutron Capture Therapy), since the effectiveness of therapy irradiation derives just from neutron capture reaction of B-10. Hence, the determination of the B-10 concentration ratio, between tumour and healthy tissue, and a control of this ratio, during the therapy, are essential to optimise the effectiveness of the BNCT, which it is known to be based on the selective uptake ...

  20. Performance of Boron-10 based Neutron Coincidence Counters

    International Nuclear Information System (INIS)

    Helium-3 gas-filled detectors have been used in neutron coincidence counting for non-destructive assay for over 30 years. With the current shortage of 3He gas, GE's Reuter-Stokes business developed a 10B lined proportional counter and a 10B hybrid coincidence counter, in which a small amount of 3He is added to a 10B detector to enhance the neutron sensitivity. GE's Reuter-Stokes business modelled, designed, built and tested prototype coincidence counters using the 10B lined detectors and the 10B hybrid detectors. We will present these systems and their applications for non-destructive assay. (author)

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

    International Nuclear Information System (INIS)

    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 E2g mode of vibration in 10h-BN

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

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Pervaiz, E-mail: pervaizahmad@siswa.um.edu.my, E-mail: Pervaiz-pas@yahoo.com; Khandaker, Mayeen Uddin, E-mail: mu-khandaker@yahoo.com, E-mail: mu-khandaker@um.edu.my; Amin, Yusoff Mohd [University of Malaya, Department of Physics, Faculty of Science (Malaysia); Khan, Ghulamullah [University of Malaya, Department of Mechanical Engineering (Malaysia); Ramay, Shahid M. [King Saud University, Department of Physics and Astronomy, College of Science (Saudi Arabia); Mahmood, Asif [King Saud University, Department of Chemical Engineering, College of Engineering (Saudi Arabia); Amin, Muhammad [University of the Punjab, Department of Physics (Pakistan); Muhammad, Nawshad [Interdisciplinary Research Centre in Biomedical Materials (IRCBM) COMSATS Institute of Information Technology (Pakistan)

    2016-01-15

    {sup 10}Boron nitride nanotubes ({sup 10}BNNTs) are a potential neutron sensing element in a solid-state neutron detector. The aligned {sup 10}BNNT can be used for its potential application without any further purification. Argon-supported thermal CVD is used to achieve vertically aligned {sup 10}BNNT 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 {sup 10}BNNTs with ball-like catalytic tips at top. EDX reveals magnesium (Mg) contents in the tips that refer to catalytic growth of {sup 10}BNNT. HR-TEM shows tubular morphology of the synthesized {sup 10}BNNT 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 {sup 10}Boron nitride ({sup 10}h-BN) nature of the synthesized {sup 10}BNNT, 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{sup −1}) that corresponds to E{sub 2g} mode of vibration in {sup 10}h-BN.

  3. Reprocessing of the irradiated boron carbide enriched by boron-10 isotope and its reuse in the control rods of the fast breeder reactors

    International Nuclear Information System (INIS)

    The present paper discusses the development of technology for reprocessing of irradiated boron carbide, which provides complete removal of radionuclides from irradiated materials. This technology allows the repeated use of B10 enriched with B4C in fast reactors. (author). 4 figs, 1 tab

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

    International Nuclear Information System (INIS)

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

  5. Radiometric determination of boron with mandelic acid and zinc-65-labelled bis(1,10-phenanthroline)zinc(II)

    International Nuclear Information System (INIS)

    The use of solvent extraction methods for the radiometric determination of boron is scarce. This work was undertaken to examine the feasibility of an indirect radiometric method for the determination of trace amounts of boron by solvent extraction. Mandelic acid was used as the complexing agent for boron and the complex anion formed was extracted as an ion associate with zinc-65-labelled bis(1,10-phenanthroline)zinc(II) into isobutyl methyl ketone. The activity of zinc in the organic layer was measured using an NaI-Tl well-type scintillation detector, and was a linear function of the concentration of boron in the aqueous phase over the range 0-10 μg in a final volume of 15 ml. A detection limit of 0.25 μg of boron in a 15 ml aqueous volume could be achieved. The interfering effect of various ions was overcome by selective distillation of boron as methyl borate. The method was applied to the determination of boron in Cr-Mo-B alloy, ointments, talcum powder and eye lotion samples. The reliability of the proposed method was checked by comparing the results obtained for the above samples with those given by ICP-AES. (author)

  6. Preparation, structure and some properties of boron crystals with different content of 10B and 11B isotopes

    International Nuclear Information System (INIS)

    The present work deals with the analysis of data on preparation and investigation of boron with different content of 10B and 11B isotopes. It was established that influence of isotopes on the structure and physical-mechanical properties of boron varies with regard to the type and percentage of an applied isotope. Microhardness of the specimens was measured at room temperatures. Peculiarities of changes observed in the values of microhardness, thermal expansion coefficients and characteristics of the relaxation processes are discussed from the point of view of probable changes in inter-atomic forces created due to substitution of natural boron atoms with their isotopes

  7. R and D studies at IGCAR on boron enrichment using ion exchange chromatography process. Contributed Paper IT-10

    International Nuclear Information System (INIS)

    Boron Carbide enriched in 10B isotope is used as control rod material for fast reactors. The natural abundance of 10B isotope of boron is about 20%. In addition to the use in control rods for fast reactors, enriched boron compounds find many other applications in nuclear industry such as in neutron detection, shielding and burnable poison in moderators of thermal reactors and also in neutron capture therapy. To meet the growing demand for 10B enriched materials, it has become necessary to develop efficient processes to enrich this isotope of boron. Among the known processes, ion exchange chromatography is a viable option for the industrial enrichment of this isotope of boron. Pilot scale experiments were carried out to study the band velocity, influence of complexing agent, variation of HETP with time, influence of initial eed enrichment and particle size of the resin. A Model for ion exchange chromatography was developed and validated to predict HETP for different operating conditions. This model is effective in analysing plant operation and also design of new boron enrichment plants

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

    Science.gov (United States)

    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. Separation of boron isotopes in anion exchange resin column. Isotopic enrichment of 10 B

    International Nuclear Information System (INIS)

    The separation of boron isotopes (10 B and 11 B) was carried out by isotopic exchange reaction between boric acid in solution and borate/poly borate anions adsorbed on an ammonium quaternary (Dowex 1 X 8 and 2 X 8) anion exchange resin packed in columns. Each resin column had 100 cm length and 1.4 cm in diameter. The columns were connected in series during displacement of boric bands. The enrichment line used pressure ranging from 2.5 to 3.0 Kg f.cm-2. N2 gas was used as in inert atmosphere in order to prevent C O2 formation. Enrichments in 10 B of 43% were obtained using Dowex 1 X 8 resin, 0.1 eq.L-1 H3 B O3 solution and band displacement of 1,876 cm. With Dowex 2 X 8 the enrichment was 40% with 1,330 cm of band displacement and 0.1 eq. L-1 H3 B O3. The boron isotopes were analysed, as methyl borate, by mass spectrometry. (author). 13 refs, 5 figs, 2 tabs

  10. A suggestion for B-10 imaging during boron neutron capture therapy

    CERN Document Server

    Cortesi, M

    2007-01-01

    Selective accumulation of B-10 compound in tumour tissue is a fundamental condition for the achievement of BNCT (Boron Neutron Capture Therapy), since the effectiveness of therapy irradiation derives just from neutron capture reaction of B-10. Hence, the determination of the B-10 concentration ratio, between tumour and healthy tissue, and a control of this ratio, during the therapy, are essential to optimise the effectiveness of the BNCT, which it is known to be based on the selective uptake of B-10 compound. In this work, experimental methods are proposed and evaluated for the determination in vivo of B-10 compound in biological samples, in particular based on neutron radiography and gammaray spectroscopy by telescopic system. Measures and Monte Carlo calculations have been performed to investigate the possibility of executing imaging of the 10B distribution, both by radiography with thermal neutrons, using 6LiF/ZnS:Ag scintillator screen and a CCD camera, and by spectroscopy, based on the revelation of gamm...

  11. Heat affected zone (HAZ) hot cracking in 18 Cr.10 Ni stainless steels due to small boron content

    International Nuclear Information System (INIS)

    Boron lowers resistance to hot cracking in the heat affected zone of 18.10 Ti and 18.12 Mo stainless steels: this element brings down the temperature above which fusions occur. Those fusions occur in the metal when it is heated during welding. They concern a part of the heat affected zone which is all the more extended as the temperature at the start of the fusions is low, therefore as the boron content is high. Due to the welding strains, the zones in which the fusions occur get cracked

  12. Measurement of the isotopic abundance of boron-10 by inductively coupled plasma-quadrupole mass spectrometry

    International Nuclear Information System (INIS)

    This article describes the method for measuring the isotopic abundance of 10B in nuclear grade boron carbide using inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS). The results of investigation revealed that both the integration time and the dwell time have a major influence on the reproducibility of ICP-QMS measurements. As a result of optimization of the measurement conditions, reproducibility below 0.2% relative standard deviation (RSD) (0.17% RSD maximum) was achieved. In addition, the measured value of the isotopic abundance of 10B for each sample well agreed with the values measured by the TIMS. Thus, the method described in the present investigation was very effective in the analysis of isotopic abundance of 10B in B4C or H3BO3. The results of this study suggest that ICP-QMS could be applied to the precise analysis of the isotopic abundance of 10B required in the field of nuclear applications. (author)

  13. Multi-Grid Boron-10 detector for large area applications in neutron scattering science

    CERN Document Server

    Andersen, Ken; Birch, Jens; Buffet, Jean-Claude; Correa, Jonathan; van Esch, Patrick; Guerard, Bruno; Hall-Wilton, Richard; Hultman, Lars; Höglund, Carina; Jensen, Jens; Khaplanov, Anton; Kirstein, Oliver; Piscitelli, Francesco; Vettier, Christian

    2012-01-01

    The present supply of 3He can no longer meet the detector demands of the upcoming ESS facility and continued detector upgrades at current neutron sources. Therefore viable alternative technologies are required to support the development of cutting-edge instrumentation for neutron scattering science. In this context, 10B-based detectors are being developed by collaboration between the ESS, ILL, and Link\\"{o}ping University. This paper reports on progress of this technology and the prospects applying it in modern neutron scattering experiments. The detector is made-up of multiple rectangular gas counter tubes coated with B4C, enriched in 10B. An anode wire reads out each tube, thereby giving position of conversion in one of the lateral co-ordinates as well as in depth of the detector. Position resolution in the remaining co-ordinate is obtained by segmenting the cathode tube itself. Boron carbide films have been produced at Link\\"{o}ping University and a detector built at ILL. The characterization study is pres...

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

    International Nuclear Information System (INIS)

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

  15. 10Boron distribution measurement in laser ablated B4C thin films using (n,α) reaction and LR-115 passive detector

    International Nuclear Information System (INIS)

    Lateral distribution of the 10B isotope within a boron carbide film of 550 nm maximum thickness deposited on silicon wafer using pulsed laser deposition technique has been determined taking advantage of the high cross section for (n,α) reaction and nuclear tracks detectors (NTD - LR-115 Kodak Pathe). A radioisotope neutron source (252Cf, 20 μg) and a 60 x 60 x 80 cm3 graphite cube as moderator produce a relatively uniform thermal neutron field. Details of the passive detector etching process and data processing are included. The track density reveals the boron density spatial distribution. A 3D picture is produced to visualize the boron-10 spatial distribution. The result suggests that a gradient in the boron distribution exists to almost a factor of three. The advantages of the technique are discussed.

  16. {sup 10}Boron distribution measurement in laser ablated B{sub 4}C thin films using (n,alpha) reaction and LR-115 passive detector

    Energy Technology Data Exchange (ETDEWEB)

    Sajo-Bohus, L., E-mail: sajobohus@gmail.co [Universidad Simon Bolivar, Nuclear Physics Section, Valle de Sartenejas, Caracas 89000A (Venezuela, Bolivarian Republic of); Simon, A. [Institute of Nuclear Research of the Hungarian Academy of Sciences, Debrecen 4026 (Hungary); Csako, T. [Dep. of Optics and Quantum Electronics, University of Szeged, P.O. Box 406, H-6701 Szeged (Hungary); Nemeth, P.; Palacios, D. [Universidad Simon Bolivar, Nuclear Physics Section, Valle de Sartenejas, Caracas 89000A (Venezuela, Bolivarian Republic of); Espinosa, G. [Universidad Nacional Autonoma de Mexico, Mexico City (Mexico); Greaves, E.D. [Universidad Simon Bolivar, Nuclear Physics Section, Valle de Sartenejas, Caracas 89000A (Venezuela, Bolivarian Republic of); Szoerenyi, T. [Dep. of Nat. Sci. and Environ. Prot., College of Dunaujvaros, P.O. Box 152, H-2401 Dunaujvaros (Hungary); Barros, H. [Universidad Simon Bolivar, Nuclear Physics Section, Valle de Sartenejas, Caracas 89000A (Venezuela, Bolivarian Republic of)

    2009-10-15

    Lateral distribution of the {sup 10}B isotope within a boron carbide film of 550 nm maximum thickness deposited on silicon wafer using pulsed laser deposition technique has been determined taking advantage of the high cross section for (n,alpha) reaction and nuclear tracks detectors (NTD - LR-115 Kodak Pathe). A radioisotope neutron source ({sup 252}Cf, 20 mug) and a 60 x 60 x 80 cm{sup 3} graphite cube as moderator produce a relatively uniform thermal neutron field. Details of the passive detector etching process and data processing are included. The track density reveals the boron density spatial distribution. A 3D picture is produced to visualize the boron-10 spatial distribution. The result suggests that a gradient in the boron distribution exists to almost a factor of three. The advantages of the technique are discussed.

  17. Selective boron accumulation in human ocular melanoma by 10B1-para-boronophenylalanine administration for neutron capture therapy

    International Nuclear Information System (INIS)

    Malignant melanoma occurs not only in the skin but also in ocular tissues. Ocular melanoma located superficially as in conjunctiva can be treated successfully by BNCT. In the present study, we investigated 10B dynamics in ocular melanoma and the surrounding normal tissues, to evaluate the possibility of applying BNCT to ocular melanoma. In three ocular melanoma patients, 10B concentration in melanoma after administration of 10B-BPA by oral or drip infusion ranged from 10.4 to 21.5 ppm. The boron concentrations in lens and vitreous body were lower than blood level, whereas higher than blood in sclera and palpebral skin. These results suggest that we can treat such a superficial melanoma lesions as conjunctival melanoma by BNCT using 10B1-BPA. (author)

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    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. PMID:24559940

  20. Sputtering behavior of boron and boron carbide

    International Nuclear Information System (INIS)

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

  1. Inverse-Frontal Chromatography studies on enrichment of Boron-10 using quaternery 4-vinylpyridine-divinylbenzene resin

    International Nuclear Information System (INIS)

    In order to enrich 10B, band migration of boric acid-mannitol with hydrochloric acid solution was performed by inverse frontal chromatography on a porous, 25% crosslinked, 38% quaternized 4-vinylpyridine-divinylbenzene resin (py-resin). The work was initiated to replace the existing strong base anion exchange resin type-II (SBA-II) which is used in Boron Enrichment Plant (BEP) of heavy water plant Manuguru. Before its application in BEP, it is mandatory to evaluate py-resin for its performance. The studies showed that maximum of 40% 10B enrichment observed after 13 m band movement and there was no further improvement, hence profile sampling carried out after 28 m. (author)

  2. Capillary electrophoresis-electrospray mass spectrometry and HR-ICP-MS for the detection and quantification of 10B-boronophenylalanine (10B-BPA) used in boron neutron capture therapy.

    Science.gov (United States)

    Pitois, Aurélien; de las Heras, Laura Aldave; Zampolli, Antonella; Menichetti, Luca; Carlos, Ramon; Lazzerini, Guido; Cionini, Luca; Salvatori, Pietro Alberto; Betti, Maria

    2006-02-01

    Boron neutron capture therapy (BNCT) is a bimodal radiotherapeutic treatment based on the irradiation of neoplastic tissues with neutrons after the tissues have selectively accumulated molecules loaded with nuclides with large neutron capture cross-sections (such boron-10). Boron-10 carriers have been tested to a limited extent, and clinical trials have been conducted on sulfhydryl borane (10B-BSH) and boronophenylalanine (10B-BPA). However, precise and accurate measurements of boron-10 concentrations (0.1-100 microg/g) in specimens and samples of limited size (microg scale) are needed in order to be able to biologically characterise new compounds in predictive tissue dosimetry, toxicology and pharmacology studies as well as in clinical investigations. A new approach based on fast separation and detection of 10B-BPA performed by coupling capillary electrophoresis to electrospray mass spectrometry is reported. This method allows the quantitative analysis and characterisation of 10B-BPA in a short time with a high separation efficiency. Detection limits of 3 microM for 10B-BPA and 30 ng/mL for 10B were obtained with CE-ESI-MS. A quantification limit of 10 microM for 10B-BPA (100 ng/mL for 10B) was attained. The total boron-10 concentration was determined by high-resolution inductively coupled mass spectrometry in order to validate the method. Boron-10 isotope measurements were carried out by HR-ICP-MS at medium resolution (R=4000) due to the presence of an isobaric interference at mass 10. Good agreement was obtained between the values from CE-ESI-MS and those from HR-ICP-MS. The method has been successfully used to determine the 10B-BPA in two lines of cultured cells. PMID:16372182

  3. Proton magnetic resonance spectroscopy of a boron neutron capture therapy 10B-carrier, L-p-boronophenylalanine-fructose complex

    Energy Technology Data Exchange (ETDEWEB)

    Timonen, M.

    2010-07-01

    Boron neutron capture therapy (BNCT) is a radiotherapy that has mainly been used to treat malignant brain tumours, melanomas, and head and neck cancer. In BNCT, the patient receives an intravenous infusion of a 10B-carrier, which accumulates in the tumour area. The tumour is irradiated with epithermal or thermal neutrons, which result in a boron neutron capture reaction that generates heavy particles to damage tumour cells. In Finland, boronophenylalanine fructose (BPA-F) is used as the 10B-carrier. Currently, the drifting of boron from blood to tumour as well as the spatial and temporal accumulation of boron in the brain, are not precisely known. Proton magnetic resonance spectroscopy (1H MRS) could be used for selective BPA-F detection and quantification as aromatic protons of BPA resonate in the spectrum region, which is clear of brain metabolite signals. This study, which included both phantom and in vivo studies, examined the validity of 1H MRS as a tool for BPA detection. In the phantom study, BPA quantification was studied at 1.5 and 3.0 T with single voxel 1H MRS, and at 1.5 T with magnetic resonance imaging (MRSI). The detection limit of BPA was determined in phantom conditions at 1.5 T and 3.0 T using single voxel 1H MRS, and at 1.5 T using MRSI. In phantom conditions, BPA quantification accuracy of +- 5% and +- 15% were achieved with single voxel MRS using external or internal (internal water signal) concentration references, respectively. For MRSI, a quantification accuracy of <5% was obtained using an internal concentration reference (creatine). The detection limits of BPA in phantom conditions for the PRESS sequence were 0.7 (3.0 T) and 1.4 mM (1.5 T) mM with 20 x 20 single voxel MRS, and 1.0 mM with acquisition-weighted MRSI, respectively. In the in vivo study, an MRSI or single voxel MRS or both was performed for ten patients (patients 1-10) on the day of BNCT. Three patients had glioblastoma multiforme (GBM), and five patients had a recurrent or

  4. Determination of boron by ICP-AES in normal and malignant cells incubated 'in vitro' with fructose 10BPA

    International Nuclear Information System (INIS)

    This paper describes the development and optimization of methodology for total boron concentration in cell cultures coming from fixation and accumulation of this element by normal and malignant cells. On account of sample mass and low volume resulting from dilution, generally about 1 mL, a procedure for automatic injection of micro volumes was designed, developed and optimized. Iron interference was carefully studied. Linear calibration curves were obtained for 50 to 2500 ng B/mL range. Determination limits were 10 and 20 ng B/mL for B 249.772 nm and 249.677 nm, respectively. Repeatability, expressed as relative standard deviation was better than 5% for a 100 ng B/mL. Recovery of analyte added to real samples ranged between 95 and 103%. The method was applied to studies on F-98 cells (rat glioma) and normal glia in BNCT project frame. (author)

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

    Science.gov (United States)

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

    2008-05-21

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

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-05-21

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

  8. First boronization in KSTAR

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-11-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

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

  10. Utilization of boron ({sup 10}B) derived from fertilizer by sugar cane

    Energy Technology Data Exchange (ETDEWEB)

    Franco, Henrique Coutinho Junqueira; Trivelin, Paulo Cesar Ocheuze, E-mail: hjfranco@cena.usp.b, E-mail: pcotrive@cena.usp.b [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil); Vitti, Andre Cesar, E-mail: acvitti@apta.sp.gov.b [Agencia Paulista de Tecnologia dos Agronegocios (APTA), Piracicaba, SP (Brazil). Polo Centro Sul; Otto, Rafael, E-mail: rotto@esalq.usp.b [Universidade de Sao Paulo (USP), Piracicaba, SP (Brazil). Escola Superior de Agricultura Luiz de Queiroz; Faroni, Carlos Eduardo, E-mail: cfaroni@ctc.com.b [Centro de Tecnologia Canavieira (CTC), Piracicaba, SP (Brazil); Tovajar, Joao Gabriel, E-mail: jgtoaliari@bol.com.b [Cosan S.A., Valparaiso, SP (Brazil). Unidade Univalem

    2009-11-15

    The response to B in agricultural systems of sugar cane is still an unexplored issue; B application has however recently been widely publicized and used with a certain degree of frequency. The use of {sup 10}B-labeled fertilizers may further contribute to clarify this practice. With the objective of evaluating sugar cane use of B ({sup 10}B) derived from fertilizer (boric acid), an experiment was conducted under field conditions in the 2005/2006 growing season. The experiment consisted of the installation of microplots (2 x 1.5 m) where 4 kg ha{sup -1} B (boric acid with 85.95 % in {sup 10}B atoms) dissolved in water was applied 90 days after planting (May 2005). The solution was applied to the soil on both sides of the plant row at a distance of 20 cm. After harvest (June 2006) the B content and {sup 10}B abundance in % atoms in all parts of the sugar cane plants (stalks, dry leaves, tips and roots) were determined. Results showed that the total B accumulated was 471 g ha{sup -1} in the entire plant (35 % in the stalks, 22 % in the dry leaves, 9 % in the tips and 34 % in the roots). The sugar cane plants used on average 14 % of the total accumulated B in the above-ground part (44 g ha{sup -1}) and 11 % in the roots (19 g ha{sup -1}), totaling 13 % in the entire plant (63 g ha{sup -1}). The recovery of 10B-fertilizer by sugar cane plants was low, around 2 % of the total applied amount. (author)

  11. Utilization of boron (10B) derived from fertilizer by sugar cane

    International Nuclear Information System (INIS)

    The response to B in agricultural systems of sugar cane is still an unexplored issue; B application has however recently been widely publicized and used with a certain degree of frequency. The use of 10B-labeled fertilizers may further contribute to clarify this practice. With the objective of evaluating sugar cane use of B (10B) derived from fertilizer (boric acid), an experiment was conducted under field conditions in the 2005/2006 growing season. The experiment consisted of the installation of microplots (2 x 1.5 m) where 4 kg ha-1 B (boric acid with 85.95 % in 10B atoms) dissolved in water was applied 90 days after planting (May 2005). The solution was applied to the soil on both sides of the plant row at a distance of 20 cm. After harvest (June 2006) the B content and 10B abundance in % atoms in all parts of the sugar cane plants (stalks, dry leaves, tips and roots) were determined. Results showed that the total B accumulated was 471 g ha-1 in the entire plant (35 % in the stalks, 22 % in the dry leaves, 9 % in the tips and 34 % in the roots). The sugar cane plants used on average 14 % of the total accumulated B in the above-ground part (44 g ha-1) and 11 % in the roots (19 g ha-1), totaling 13 % in the entire plant (63 g ha-1). The recovery of 10B-fertilizer by sugar cane plants was low, around 2 % of the total applied amount. (author)

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

    International Nuclear Information System (INIS)

    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 10BSH-containing water-in-oil-in-water emulsion (10BSH-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 10BSH-WOW can be used as novel intra-arterial boron carriers during BNCT for HCC. - Highlights: • We started the pilot clinical study of BNCT to recurrence hepatic cancer. • The tumor size was remained stable during 3 months after BNCT(SD). • No adverse effect as a result of BNCT was observed during follow-up period. • 10B-containing WOW emulsion can be applied as a novel intra-arterial boron carrier for BNCT for HCC

  13. Influence of BNCT radiations on the blood-brain barrier in terms of boron-10 uptake

    International Nuclear Information System (INIS)

    A key issue is to determine whether fractionated BNCT is a feasible proposition. This issue has been reviewed by Dorn et al, who call for further experimental investigation of BNCT induced changes in the blood brain barrier and investigated by Hatanaka et al. In order to investigate the effect on BNCT, the authors measured 10B concentration and water content in the normal brain which has been subjected to BNCT regimen

  14. Phantoms with 10BF3 detectors for boron neutron capture therapy applications

    International Nuclear Information System (INIS)

    Two acrylic cube phantoms have been constructed for BNCT applications that allow the depth distribution of neutrons to be measured with miniature 10BF3 detectors in 0.5-cm steps beginning at 1-cm depth. Sizes and weights of the cubes are 14 cm, 3.230 kg, and 11 cm, 1.567 kg. Tests were made with the epithermal neutron beam from the patient treatment port of the Brookhaven Medical Research Reactor. Thermal neutron depth profiles were measured with a bare 10BF3 detector at a reactor power of 50 W, and Cd-covered detector profiles were measured at a reactor power of 1 kW. The resulting plots of counting rate versus depth illustrate the dependence of neutron moderation on the size of the phantom. But more importantly the data can serve as benchmarks for testing the thermal and epithermal neutron profiles obtained with accelerator-based BNCT facilities. Such tests could be made with these phantoms at power levels about five orders of magnitude lower than that required for the treatment of patients with brain tumors. copyright 1998 American Association of Physicists in Medicine

  15. Modification of Sn-1.0Ag-0.5Cu solder using nickel and boron

    Institute of Scientific and Technical Information of China (English)

    Jun-Feng Qu; Jun Xu; Qiang Hu; Fu-Wen Zhang; Shao-Ming Zhang

    2015-01-01

    Effects of Ni and B additions on the microstructure and growth behavior of the intermetallic compound (IMC) of Sn-1.0Ag-0.5Cu alloys (SAC105) were investigated in this study.Results show that microadditions of Ni and B result in volume fraction of primary Sn increasing and the grain size decreasing observably.It is found that a large number of fine reinforcement particles with network-like shape are found in the solder,and the thickness of interfacial IMC layer in the solder joint is grew less than that of SAC 105 with longer aging time.Shear test results reveal that as-soldered solder joints of microalloyed SAC105 have better shear strength than that of SAC 105 solder alloy.

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

    Directory of Open Access Journals (Sweden)

    Meltem Bilici Başkan

    2014-03-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Carpano, Marina; Perona, Marina; Rodriguez, Carla [Department of Radiobiology, National Atomic Energy Commission, San Martín (Argentina); Nievas, Susana; Olivera, Maria; Santa Cruz, Gustavo A. [Department of Boron Neutron Capture Therapy, National Atomic Energy Commission, San Martín (Argentina); Brandizzi, Daniel; Cabrini, Romulo [Department of Radiobiology, National Atomic Energy Commission, San Martín (Argentina); School of Dentistry, University of Buenos Aires, Buenos Aires (Argentina); Pisarev, Mario [Department of Radiobiology, National Atomic Energy Commission, San Martín (Argentina); National Research Council of Argentina, Buenos Aires (Argentina); Department of Human Biochemistry, School of Medicine, University of Buenos Aires, Buenos Aires (Argentina); Juvenal, Guillermo Juan [Department of Radiobiology, National Atomic Energy Commission, San Martín (Argentina); National Research Council of Argentina, Buenos Aires (Argentina); Dagrosa, Maria Alejandra, E-mail: dagrosa@cnea.gov.ar [Department of Radiobiology, National Atomic Energy Commission, San Martín (Argentina); National Research Council of Argentina, Buenos Aires (Argentina)

    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

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

    International Nuclear Information System (INIS)

    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 (10BPA) 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 4 106 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 10B 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 (R2 = 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 (R2 = 0.81, logistic function fit). Conclusion: We propose that these methods could be suitable for designing new screening protocols applied before melanoma BNCT treatment for each individual

  19. Boron analyses in the reactor coolant system of French PWR by acid-base titration ([B]) and ICP-MS (10B atomic %): key to NPP safety

    International Nuclear Information System (INIS)

    Boron is widely used by Nuclear Power Plants and especially by EDF Pressurized Water Reactors to ensure the control of the neutron rate in the reactor coolant system and, by this way, the fission reaction. The Boron analysis is thus a major factor of safety which enables operators to guarantee the permanent control of the reactor. Two kinds of analyses carried out by EDF on the Boron species, recently upgraded regarding new method validation standards and developed to enhance the measurement quality by reducing uncertainties, will be discussed in this topic: Acid-Base titration of Boron and Boron isotopic composition by Inductively Coupled Plasma Mass Spectrometer - ICP MS. (authors)

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-12-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

    Neutron capture radiography (NCR) is a nuclear analytical imaging method. It is based on using thermal neutron induced nuclear reactions, such as (n,p), (n,α) or (n,f). Clearly NCR can be used for the detection of only those nuclides whose cross-section (σ) for one of these nuclear reactions is not too low. With σ being indicated in barns (1 barn 10-28m2) in brackets, this is the case especially with 14N (1.83), 35Cl (0.48), 40K (4.4) for (n,p) reactions; 6Li (941.4), 10B (3836), 17O (0.24), 35S (0.14), 40K (0.39) for (n,α) reactions; and 235U (583) and 239Pu (742) for neutron induced fissions (n,f). Some of these nuclear reactions are characteristic of stable isotopes (14N, 6Li, 10B, 17O) of chemical elements that are highly relevant for biology but have no radioactive isotope usable in practice. It is possible to use these stable isotopes for the labelling and analytical imaging of the corresponding elements almost as easily as with radioactive tracers when they exist. Some of these nuclear reactions are characteristic of stable isotopes (14N, 6Li, 10B, 17O) of chemical elements that are highly relevant for biology but have no radioactive isotope usable in practice. It is possible to use these stable isotopes for the labelling and analytical imaging of the corresponding elements almost as easily as with radioactive tracers when they exist. In conventional NCR studies, the biological specimen (a histological section in most cases) is laid against an appropriate detector (most often a film of cellulose nitrate or polycarbonate), and then this whole assembly is irradiated with thermal neutrons. The impact of the ionizing particles (p,α, fission fragments) emitted by the nuclear reactions creates latent tracks in the detecting film. Using an appropriate chemical treatment (most often by dipping the detectors in a strong alkaline solution), the latent tracks are enlarged to the size of tracks visible with an optical microscope. The features (especially the size

  4. In-beam test of the Boron-10 Multi-Grid neutron detector at the IN6 time-of-flight spectrometer at the ILL

    International Nuclear Information System (INIS)

    A neutron detector concept based on solid layers of boron carbide enriched in 10B has been in development for the last few years as an alternative for 3He by collaboration between the ILL, ESS and Linköping University. This Multi-Grid detector uses layers of aluminum substrates coated with 10B4C on both sides that are traversed by the incoming neutrons. Detection is achieved using a gas counter readout principle. By segmenting the substrate and using multiple anode wires, the detector is made inherently position sensitive. This development is aimed primarily at neutron scattering instruments with large detector areas, such as time-of-flight chopper spectrometers. The most recent prototype has been built to be interchangeable with the 3He detectors of IN6 at ILL. The 10B detector has an active area of 32 x 48cm2. It was installed at the IN6 instrument and operated for several weeks, collecting data in parallel with the regularly scheduled experiments, thus providing the first side-by-side comparison with the conventional 3He detectors. Results include an efficiency comparison, assessment of the in-detector scattering contribution, sensitivity to gamma-rays and the signal-to-noise ratio in time-of-flight spectra. The good expected performance has been confirmed with the exception of an unexpected background count rate. This has been identified as natural alpha activity in aluminum. New convertor substrates are under study to eliminate this source of background.

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

    International Nuclear Information System (INIS)

    Purpose: To evaluate GB-10-encapsulating transferrin (TF)-pendant-type polyethyleneglycol (PEG) liposomes as tumor-targeting 1B-carriers for boron neutron capture therapy. Methods and Materials: A free mercaptoundecahydrododecaborate-1B (BSH) or decahydrodecaborate-1B (GB-10) solution, bare liposomes, PEG liposomes, or TF-PEG liposomes were injected into SCC VII tumor-bearing mice, and 1B concentrations in the tumors and normal tissues were measured by γ-ray spectrometry. Meanwhile, tumor-bearing mice were continuously given 5-bromo-2'-deoxyuridine (BrdU) to label all intratumor proliferating cells, then injected with these 1B-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 1B 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 1B-carriers were significantly greater than BSH-containing 1B-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 1B-carriers

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

    Science.gov (United States)

    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. PMID:26346614

  7. Elementary boron and metal-boron compounds

    International Nuclear Information System (INIS)

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

  8. Boron isotopic enrichment by displacement chromatography

    International Nuclear Information System (INIS)

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

  9. Boron removal from geothermal waters by electrocoagulation

    International Nuclear Information System (INIS)

    Most of the geothermal waters in Turkey contain extremely high concentration of boron when they are used for irrigation. The use of geothermal waters for irrigation can results in excess amount deposition of boron in soil. On the other hand, a minimal boron concentration is required for irrigational waters. In this study, electrocoagulation (EC) was selected as a treatment process for the removal of boron from thermal waters obtained from Ilica-Erzurum in Turkey. Current density (CD), pH of solution and temperature of solution were selected as operational parameters. The results showed that boron removal efficiency increased from pH 4.0 to 8.0 and decreased at pH 10.0. Although boron removal efficiency was highest at pH 8.0, energy consumption was very high at this pH value compared to other pH intervals. Boron removal efficiency reached to 95% with increasing current density from 1.5 to 6.0 mA/cm2, but energy consumption was also increased in this interval. At higher temperatures of solution, such as 313 and 333 K, boron removal efficiency increased. At optimum conditions, boron removal efficiency in geothermal water reached up to 95%

  10. Boron removal from geothermal waters by electrocoagulation

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-05-01

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-11-01

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

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

    International Nuclear Information System (INIS)

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

  14. The boron trifluoride nitromethane adduct

    Science.gov (United States)

    Ownby, P. Darrell

    2004-02-01

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

  15. Boron doping a semiconductor particle

    Science.gov (United States)

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

    1998-06-09

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Kitaoka, Y. [ed.

    1998-12-01

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

  18. Boron nitride converted carbon fiber

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-04-05

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

  19. Mass spectrometric determination of boron isotope in boron carbide

    International Nuclear Information System (INIS)

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

  20. Sintering of boron carbide (B4C)

    International Nuclear Information System (INIS)

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

  1. First boronization in KSTAR: Experiences on carborane

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-08-01

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

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

    International Nuclear Information System (INIS)

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

  3. Boron-isotope fractionation in plants

    International Nuclear Information System (INIS)

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

  4. Analysis of boron at Koeberg Power Station

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

    We used synchrotron spectromicroscopy to study the microscopic distribution of boron in rat brain tumour and healthy tissue in the field of boron neutron capture therapy (BNCT). The success of this experimental cancer therapy depends on the preferential uptake of 10B in tumour cells after injection of a boron compound (in our case B12H11SH, or BSH). With the Mephisto (microscope a emission de photoelectrons par illumination synchrotronique de type onduleur) spectromicroscope, high-magnification imaging and chemical analysis was performed on brain tissue sections from a rat carrying an implanted brain tumour and the results were compared with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) detection of boron in bulk tissue. Boron was found to have been taken up more favourably by regions of tumour rather than healthy tissue, but the resulting boron distribution in the tumour was inhomogeneous. The results demonstrate that Mephisto can perform microchemical analysis of tissue sections, detect and localize the presence of boron with submicron spatial resolution. The application of this technique to boron in brain tissue can therefore be used to evaluate the current efforts to optimize BNC therapy. (author)

  7. Quantitative boron detection by neutron transmission method

    International Nuclear Information System (INIS)

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

  8. Boronization of Russian tokamaks from carborane precursors

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  10. Determination of boron and silicon in boron carbide

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  12. ADSORPTION POTENTIAL OF UNMODIFIED RICE HUSK FOR BORON REMOVAL

    OpenAIRE

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

    2012-01-01

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

  13. CVD-produced boron filaments

    Science.gov (United States)

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

    1980-01-01

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

  14. Inheritance of Boron Efficiency in Oilseed Rape

    Institute of Scientific and Technical Information of China (English)

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

    2009-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  17. Microstructure of boron nitride coated on nuclear fuels by plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Three nuclear fuels, pure urania, 5% and 10% gadolinia containing fuels were coated with boron nitride to improve nuclear and physical properties. Coating was done by plasma enhanced chemical vapor deposition technique by using boron trichloride and ammonia. The specimens were examined under a scanning electron microscope. Boron nitride formed a grainy structure on all fuels. Gadolinia decreased the grain size of boron nitride. The fractal dimensions of fragmentation and of area-perimeter relation were determined. (orig.)

  18. Microstructure of boron nitride coated on nuclear fuels by plasma enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Durmazucar, H.H. [Cumhuriyet Univ., Sivas (Turkey). Kimya Muehendisligi Boeluemue; Guenduez, G. [Kimya Muehendisligi Boeluemue, Orta Dogu Teknik Ueniversitesi, Ankara 06531 (Turkey); Toker, C. [Elektrik-Elektronik Muehendisligi Boeluemue, Orta Dogu Teknik Ueniversitesi, Ankara 06531 (Turkey)

    1998-08-03

    Three nuclear fuels, pure urania, 5% and 10% gadolinia containing fuels were coated with boron nitride to improve nuclear and physical properties. Coating was done by plasma enhanced chemical vapor deposition technique by using boron trichloride and ammonia. The specimens were examined under a scanning electron microscope. Boron nitride formed a grainy structure on all fuels. Gadolinia decreased the grain size of boron nitride. The fractal dimensions of fragmentation and of area-perimeter relation were determined. (orig.) 19 refs.

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

    Science.gov (United States)

    Rein, J E; Abernathey, R M

    1972-07-01

    Boron isotopic ratios are measured in boron carbide by thermionic ionization mass spectrometry with no prior chemical separation. A powder blend of boron carbide and sodium hydroxide is prepared, a small portion is transferred to a tantalum filament, the filament is heated to produce sodium borate, and the filament is transferred to the mass spectrometer where the(11)B/(10)B ratio is measured, using the Na(2)BO(2)(+) ion. Variables investigated for their effect on preferential volatilization of (10)B include the sodium hydroxide-boron carbide ratio and the temperature and duration of filament heating. A series of boron carbide pellets containing natural boron, of the type proposed for the control rods of the Fast Flux Test Facility reactor, were analysed with an apparently unbiased result of 4.0560 for the (11)B/(10)B ratio (standard deviation 0.0087). The pellets contained over 3% metal impurities typically found in this material. Time of analysis is 45 min per sample, with one analyst. PMID:18961131

  20. Combustion synthesis of boron carbide - a spectroscopic studies

    International Nuclear Information System (INIS)

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

  1. Wettability of boron carbide

    International Nuclear Information System (INIS)

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

  2. Boron in sillimanite.

    Science.gov (United States)

    Grew, E S; Hinthorne, J R

    1983-08-01

    Sillimanite in six granulite-facies, kornerupine-bearing rocks contains 0.035 to 0.43 percent B(2)O(3) and 0.02 to 0.23 percent MgO (by weight). Substitution of boron for silicon and magnesium for aluminum is coupled such that the ratio of magnesium to boron is about 0.5. Sillimanite incorporates more than 0.1 percent B(2)O(3) only at high temperatures in a boron-rich environment at very low partial pressures of water. In the amphibolite facies, the sillimanite boron contents are too low to appreciably affect the stability relations of sillimanite with kyanite and andalusite. PMID:17830955

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

    International Nuclear Information System (INIS)

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

  4. Boron Removal in Seawater Reverse Osmosis System

    KAUST Repository

    Rahmawati, Karina

    2011-07-01

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

  5. Boron nitride composites

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-02-16

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

  6. Does boron affect hormone levels of barley cultivars?

    Directory of Open Access Journals (Sweden)

    Muavviz Ayvaz

    2012-11-01

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

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

    International Nuclear Information System (INIS)

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

  8. First gaseous boronization during pulsed discharge cleaning

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-01-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-01

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

  10. Can Two-Dimensional Boron Superconduct?

    Science.gov (United States)

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

    2016-04-13

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

  11. Enhanced Plasma Performance by ICRF Boronization

    Institute of Scientific and Technical Information of China (English)

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

    2002-01-01

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

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

    International Nuclear Information System (INIS)

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

  13. Boronization during the first plasma operation on EAST

    International Nuclear Information System (INIS)

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

  14. Synthesis and photoluminescence property of boron carbide nanowires

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    1996-10-01

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

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

    Science.gov (United States)

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

    2015-09-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-09-15

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

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

    Science.gov (United States)

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

    2016-11-01

    Boron removal is an arising issue in desalination plants due to boron's toxicity. As an emerging treatment concept, bioelectrochemical systems (BES) can achieve potentially cost-effective boron removal by taking advantage of cathodic-produced alkali. Prior studies have demonstrated successful removal of boron in microbial desalination cells (MDCs) and microbial fuel cells (MFCs), both of which are representative BES. Herein, mathematical models were developed to further evaluate boron removal by different BES and understand the key operating factors. The models delivered very good prediction of the boron concentration in the MDC integrated with Donnan Dialysis (DD) system with the lowest relative root-mean-square error (RMSE) of 0.00%; the predication of the MFC performance generated the highest RMSE of 18.55%. The model results of salt concentration, solution pH, and current generation were well fitted with experimental data for RMSE values mostly below 10%. The long term simulation of the MDC-DD system suggests that the accumulation of salt in the catholyte/stripping solution could have a positive impact on the removal of boron due to osmosis-driven convection. The current generation in the MDC may have little influence on the boron removal, while in the MFC the current-driven electromigration can contribute up to 40% of boron removal. Osmosis-induced convection transport of boron could be the major driving force for boron removal to a low level 22.2 in order to avoid boron accumulation in the anolyte effluent. PMID:27387806

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

    Science.gov (United States)

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

    2004-01-01

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

  20. Boronated liposome development and evaluation

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-11-01

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

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

    International Nuclear Information System (INIS)

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

  2. Magnetron sputter deposition of boron and boron carbide

    International Nuclear Information System (INIS)

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

  3. 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))

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-03-01

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2015-12-01

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

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

    International Nuclear Information System (INIS)

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

  8. Atomic-scale study of the role of carbon on boron clustering

    International Nuclear Information System (INIS)

    Boron (BF2, 20 keV, 3.14/cm2) and carbon (13 keV, 1015/cm2) implanted silicon annealed at 800 oC during 30 min or at 1000 oC during 10 s has been investigated using a laser-assisted wide-angle tomographic atom probe (LaWaTAP) instrument. Boron-silicon clusters containing ∼ 1.3 at.% of boron atoms have been observed in boron implanted silicon with a concentration exceeding the solubility limit. Often identified as BICs, they are interpreted as a metastable phase. Furthermore, addition of carbon clearly reduced the clustering of boron. This was interpreted as a diminution of boron diffusion or as an increase of the solubility limit of boron. Carbon-silicon clusters containing ∼ 1.5 at.% of carbon atoms were observed, maybe the precursors of the SiC phase.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-08-01

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

  10. A method for selective separation and preconcentration of boron in nuclear grade graphite at trace levels

    International Nuclear Information System (INIS)

    Determination of trace amounts of boron in nuclear grade graphite was carried out using ICP-OES after selective preconcentration of boron on the boron specific anion exchange resin Amberlite IRA 743. Borate ion was quantitatively separated from aqueous solution by the anion exchange resin. Analytical parameters for pre-concentration of boron as borate ion from the matrix and its quantitative elution were optimized. The preconcentration achieved by the use of anion exchanger has improved the detection limit of boron using ICP-OES from 10 mgkg-1 to 0.1 mgkg-1. The recovery of boron in graphite matrix was in the range 95-99 %. This methodology has been applied to determine boron in graphite samples. (author)

  11. Novel Boron Based Multilayer Thermal Neutron Detector

    CERN Document Server

    SCHIEBER, M

    2010-01-01

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

  12. Boron cures cancer

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2010-10-01

    The effect of isotopes ((10)B-(11)B; (12)C-(13)C) on the infrared- and Raman-active phonons of boron carbide has been investigated. For B isotopes, the contributions of the virtual crystal approximation, polarization vector and isotopical disorder are separated. Boron and carbon isotope effects are largely opposite to one another and indicate the share of the particular atoms in the atomic assemblies vibrating in specific phonon modes. Some infrared-active phonons behave as expected for monatomic boron crystals. PMID:21403227

  15. Process for microwave sintering boron carbide

    International Nuclear Information System (INIS)

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

  16. Methods of producing continuous boron carbide fibers

    Energy Technology Data Exchange (ETDEWEB)

    Garnier, John E.; Griffith, George W.

    2015-12-01

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

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

    International Nuclear Information System (INIS)

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

  18. Nuclear characterizations and applications of boron-containing materials

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  1. Does boron affect hormone levels of barley cultivars?

    OpenAIRE

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

    2012-01-01

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

  2. Thermal neutron-induced killing effect on HeLa cells modified by a new nucleic acid precursor with boron-10

    International Nuclear Information System (INIS)

    A new 10B-containing nucleic acid precursor for neutron capture therapy, 5-carboranyluridine was used to increase the killing effect of thermal neutron beam of Kyoto University Reactor on HeLa S3 cells in vitro. The increase was calculated with four parameters of a linear-quadratic model on dose-survival curve, α, β, a mean inactivation dose (D) and a surviving fraction at 2 Gy irradiation (SF(2)). The results showed that this compound was taken in cells and probably accumulated on cell surface during the incubation of cells and increased the thermal neutron induced killing effect. (author)

  3. Different morphological effects of γ-rays and boron-10 neutron captured beams on the vegetative cells of Closterium ehrenbergii (green alga)

    International Nuclear Information System (INIS)

    Different cyto-morphological effects of γ-rays and 10B neutron captured beams (BNCB), 10B(n,α)7Li on the cells of Closterium ehrenbergii Meneghini (Chlorophyta) were studied at the stationary phase of cell growth. For BNCB, about 75% of absorbed dose was estimated to be due to α particles and recoiled lithium nuclei. Relative biological effectiveness of BNCB compared to γ-rays was ca. 5 at D37. Colony observations after γ-rays irradiation revealed that each dead cell in a single colony had different morphology at 2- to 4-cell stages. However, after BNCB irradiation, the morphology of some sister cells in a colony was the same or very similar to each other. These qualitative differences of radiation response between γ-rays and BNCB were probably due to the difference in LET. DNA content of this alga is 2C in plateau phase. It was inferred genetically that the two sets of DNA double strands in this alga lie side by side at least partially at this stage, and that simultaneous modification in the same locus on the two sets of DNA strands caused the concurrence of morphologically abnormal sister cells. These abnormal cells could be classified into three major morphogroups which were subgrouped to 12 minor types from the view point of morphogenesis. (author)

  4. Mass spectral investigations of boron neutron capture therapy (BNCT) agents

    International Nuclear Information System (INIS)

    Boron neutron capture therapy (BNCT) is a promising technique for the treatment of selected types of brain tumor and potentially for other tumor types. In this therapy, a 10B-enriched species is administered to the bloodstream and selectively deposited in the tumor. The selective deposition in the tumor is due to either the breakdown of the blood-grain barrier or to the chemical nature of the boron-containing compounds. Once a sufficient concentration of boron is attained in the tumor (approximately 25 ppm), the tumor is irradiated with a controlled energy neutron beam (preferable epithermal, 1 eV to 10 keV), at which time neutrons are captured by the incorporated boron atoms. The capture results in the reaction, 10B(n, ) Li, which produces a localized nuclear reaction capable of destroying the tumor cell containing the boron. A variety of boron containing compounds have been evaluated for use in BNCT. This paper addresses some of the most promising of the compounds, the disodium salt of mercaptoundecahydrododecaborate (Na2B12H11SH), commonly referred to as BSH

  5. Prompt gamma-ray neutron activation analysis methodology for determination of boron from trace to major contents

    International Nuclear Information System (INIS)

    Prompt gamma ray neutron activation analysis methodologies were standardized using a reflected neutron beam and Compton suppressed γ-ray spectrometer to quantify boron from trace to major concentrations. Neutron self-shielding correction factors for higher boron contents (0.2-10 mg) in samples were obtained from the sensitivity of chlorine by irradiating KCl with and without boron. This method was validated by determining boron concentrations in six boron compounds and applied to three borosilicate glass samples with boron contents in the range of 1-10 mg. Low concentrations of boron (10-58 mg kg-1) were also determined in two samples and five reference materials from NIST and IAEA. (author)

  6. Sintered boron, production and properties

    International Nuclear Information System (INIS)

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

  7. Fivefold twinned boron carbide nanowires.

    Science.gov (United States)

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

    2009-09-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-06-01

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

  9. Boron dose enhancement for Cf-252 brachytherapy

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

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

  11. Spectrographic determination of traces of boron in steels

    International Nuclear Information System (INIS)

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

  12. Functionalization and cellular uptake of boron carbide nanoparticles

    DEFF Research Database (Denmark)

    Mortensen, M. W.; Björkdahl, O.; Sørensen, P. G.; Hansen, T.; Jensen, M. R.; Gundersen, Hans Jørgen Gottlieb; Bjørnholm, T.

    2006-01-01

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

  13. Electronic structure of boron-interstitial clusters in silicon

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-06-08

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

  14. The determination of boron in high-purity aluminium metal by spark-source mass spectrometry

    International Nuclear Information System (INIS)

    A method is described for the determination of boron in high-purity aluminium metal. Both isotopic boron lines (10B+1 and 11B+1) are used for the analysis. As there are no low-abundance isotopic lines for aluminium, measurements were made direct without reference to aluminium as an internal standard. The boron concentration values of eight aluminium samples analysed by this method compared favourably with results obtained from other techniques

  15. Boron content of the Freetown drinking water

    International Nuclear Information System (INIS)

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

  16. Plasma Spray Deposition of Boron Carbide

    Czech Academy of Sciences Publication Activity Database

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

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

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

    International Nuclear Information System (INIS)

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

  18. Boron and fish oil have different beneficial effects on strength and trabecular microarchitecture of bone.

    Science.gov (United States)

    Nielsen, Forrest H; Stoecker, Barbara J

    2009-01-01

    An experiment was performed to determine whether boron deprivation would adversely affect vertebra (trabecular) bone microarchitecture, and whether any adverse effect would be modified by dietary fatty acid composition. Female rats were fed diets containing 0.1mg (9 micromol) boron/kg in a factorial arrangement with variables of supplemental boron at 0 (boron-deprived) or 3 (boron-adequate) mg (278 micromol)/kg and fat sources of 75 g safflower oil/kg or 65 g fish (menhaden)oil/kg plus 10 g linoleic acid/kg. After 6 weeks, six females per treatment were bred. Dams and pups continued on their respective diets through gestation, lactation, and after weaning. At age 21 weeks, the microarchitecture of the fourth lumbar vertebrae from 12 randomly selected pups from each treatment was determined by microcomputed tomography. Boron deprivation decreased bone volume fraction and increased trabecular separation and structural model index. Boron deprivation decreased trabecular thickness when the dietary oil was safflower. A three-point bending test for bone strength found that boron deprivation decreased the maximum force needed to break the femur. Feeding fish oil instead of safflower oil decreased connectivity density in vertebrae of boron-deficient but not in boron-adequate rats. Fish oil instead of safflower oil increased the maximum force to break and the bending moment of the femur, especially in rats fed adequate boron. The findings confirm that boron and fish oil are beneficial to cortical bone strength, and show that nutritional intakes of boron are beneficial for trabecular bone microarchitecture and influence the beneficial effects of fish oil on bone. PMID:19486829

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-04-15

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

  20. Development of boron concentration analysis system and techniques for testing performance of BNCT facility

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hee Dong; Kim, Chang Shuk; Byun, Soo Hyun; Lee, Jae Yun; Sun, Gwang Min; Kim, Suk Kwon [Seoul National University, (Korea)

    2000-04-01

    I. Objectives and Necessity of the Project. Development of a boron concentration analysis system used for BNCT. Development of test techniques for BNCT facility. II. Contents and Scopes of the Project. (1) Design of a boron concentration analysis system at HANARO. (2) Component machining and instruments purchase, performance test. (3) Calculation and measurement of diffracted polychromatic beam quality. (4) Test procedures for boron concentration analysis system and BNCT facility. III. Result of the Project (1) Diffracted neutron beam quality for boron concentration analysis. (neutron flux: 1.2 * 10{sup 8} n/cm{sup 2}s, Cd-ratio : 1,600) (2) Components and instruments of the boron concentration analysis system. (3) Diffracted neutron spectrum and flux. (4) Test procedures for boron concentration analysis system and BNCT facility. 69 refs., 44 figs., 14 tabs. (Author)

  1. Laser-time resolved fluorimetric determination of trace of boron in U3O8

    International Nuclear Information System (INIS)

    In this work, a laser-time resolved fluorimetric determinatin of trace of boron in U3O8 had been developed. The boron complex with dibenzoyl methane (DBM) in a suitable medium is excited by a small nitrogen laser and emits the delay fluorescence with lifetime of 2 ms which is much longer than that of the fluorescence of uranium. Since the fluorescence of uranium doesn't interfere with determination of boron in the time resolved fluorimetric method boron need not be separated from uranium in advance. Thus the determination is very rapid and simple. The limit of determination is 0.02 ngB/ml. When 10 mgU is taken, 0.01 ppm of boron in uranium can be determined. Several samples of U3O8 with boron content from 0.04 to 0.5 ppm have been determined by using this method. The results of determination have been accordant with other methods

  2. Electrophoretic deposits of boron on duralumin plates used for measuring neutron flux

    International Nuclear Information System (INIS)

    Preparation of boron thin film deposits of around 1 mg per cm2 on duralumin plates with a diameter of 8 cm. The boron coated plates for ionization chambers were originally prepared at the CEA by pulverization of boron carbides on sodium silicates. This method is not controlling precisely enough the quantity of boron deposit. Thus, an electrophoretic method is considered for a better control of the quantity of boron deposit in the scope of using in the future boron 10 which is costly and rare. The method described by O. Flint is not satisfying enough and a similar electrophoretic process has been developed. Full description of the method is given as well as explanation of the use of dried methanol as solvent, tannin as electrolyte and magnesium chloride to avoid alumina formation. (M.P.)

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

    International Nuclear Information System (INIS)

    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 -δ + iβ close to the boron K edge (∼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.

  4. Optical properties of boron carbide near the boron K edge evaluated by soft-x-ray reflectometry from a Ru/B(4)C multilayer.

    Science.gov (United States)

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

    2009-12-10

    Soft-x-ray Bragg reflection from two Ru/B(4)C multilayers with 10 and 63 periods was used for independent determination of both real and imaginary parts of the refractive index n = 1 - delta + ibeta close to the boron K edge (approximately 188 eV). Prior to soft x-ray measurements, the structural parameters of the multilayers were determined by x-ray reflectometry using hard x rays. For the 63-period sample, the optical properties based on the predictions made for elemental boron major deviations were found close to the K edge of boron for the 10-period sample explained by chemical bonding of boron to B(4)C and various boron oxides. PMID:20011008

  5. Isotopic composition dependences of lattice constant and thermal expansion of β-rhombohedral boron

    International Nuclear Information System (INIS)

    Boron isotope substitution in boron-containing crystalline structures is important because many properties of these materials are structure sensitive. In the present work, we studied the unit cell expansion at the fixed temperature and temperature dependence of thermal expansion for the β-rhombohedral modification of boron, when 11B is replaced by 10B isotope. Theoretical analysis of experimental results associates the observed changes in structures of the β-rhombohedral boron samples of various isotope compositions with isotope effects rather than with technologically concomitant impurities.

  6. Boron thermal regeneration system

    International Nuclear Information System (INIS)

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

  7. BORONIZING OF STEEL

    Directory of Open Access Journals (Sweden)

    Arzum ULUKÖY

    2006-02-01

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

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

    Science.gov (United States)

    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. PMID:27050491

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

    OpenAIRE

    Penland, J G

    1994-01-01

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

  10. Spectrographic determination of small quantities of boron in iron and steels by means of order sorter

    International Nuclear Information System (INIS)

    Small quantities of boron in iron and steels have been determined by means of a spectrographic method using an order sorter. Samples containing more than 5 ppm of boron can be analysed with standard deviation of about 10 per cent. (authors)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-03-01

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

  12. Banishing brittle bones with boron

    Energy Technology Data Exchange (ETDEWEB)

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

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

    International Nuclear Information System (INIS)

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

  14. Boron-lined proportional counters with improved neutron sensitivity

    CERN Document Server

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

    2003-01-01

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

  15. Lattice dynamics of α boron and of boron carbide

    International Nuclear Information System (INIS)

    The atomic structure and the lattice dynamics of α boron and of B4C boron carbide have been studied by Density Functional Theory (D.F.T.) and Density Functional Perturbation Theory (D.F.P.T.). The bulk moduli of the unit-cell and of the icosahedron have been investigated, and the equation of state at zero temperature has been determined. In α boron, Raman diffusion and infrared absorption have been studied under pressure, and the theoretical and experimental Grueneisen coefficients have been compared. In boron carbide, inspection of the theoretical and experimental vibrational spectra has led to the determination of the atomic structure of B4C. Finally, the effects of isotopic disorder have been modeled by an exact method beyond the mean-field approximation, and the effects onto the Raman lines has been investigated. The method has been applied to isotopic alloys of diamond and germanium. (author)

  16. Considerations for boron neutron capture therapy studies

    International Nuclear Information System (INIS)

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

  17. Rice and wheat yield improvement by the application of boron in salt affected soils

    International Nuclear Information System (INIS)

    In recent past studies on wheat, rice and fruit plant showed that fairly large percentage of soils and crops are deficient in boron. Several times a question rose to study the boron responses in a cropping system to see the residual effect of boron. With the objective in mind, a field experiment was conducted at two sites in saline sodic soils to see the rice and wheat crops response to boron. Boron was applied to rice at the rate of 0.25, 0.50, 1.0, 1.5, and 2.0 Kg ha/sub -1/ as sodium tetra borate. The results showed that both paddy and straw yields increased with the increasing rates of boron and highest yield was obtained from 2 Kg ha/sub -l/. After harvesting of rice crop wheat was sown in the same layout. The treatments were divided into two equal portions. Boron was applied to one portion at the same rates as to rice while remaining half remained as such to study the residual effect of B on wheat. The results showed that grain anti straw yields increased with increasing rates of boron. In case of untreated plots to see the residual effect grain and straw yield increased with increasing rates of boron applied to rice. It was concluded that B applied to rice did show residual effect to the following wheat crop. Therefore, there is no need to apply B to following crop when B is applied to the previous crop. (author)

  18. Irradiation Effects in Fortiweld Steel Containing Different Boron Isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Grounes, M.

    1967-07-15

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

  19. Folate Functionalized Boron Nitride Nanotubes and their Selective Uptake by Glioblastoma Multiforme Cells: Implications for their Use as Boron Carriers in Clinical Boron Neutron Capture Therapy

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    2016-01-01

    Boron-resistant fungi were isolated from the wastewater of a boron mine in Turkey. Boron removal efficiencies of Penicillium crustosum and Rhodotorula mucilaginosa were detected in different media compositions. Minimal Salt Medium (MSM) and two different waste media containing molasses (WM-1) or whey + molasses (WM-2) were tested to make this process cost effective when scaled up. Both isolates achieved high boron removal yields at the highest boron concentrations tested in MSM and WM-1. The maximum boron removal yield by P. crustosum was 45.68% at 33.95 mg l(-1) initial boron concentration in MSM, and was 38.97% at 42.76 mg l(-1) boron for R. mucilaginosa, which seemed to offer an economically feasible method of removing boron from the effluents. PMID:26877036

  1. Boron concentration measurements by alpha spectrometry and quantitative neutron autoradiography in cells and tissues treated with different boronated formulations and administration protocols

    International Nuclear Information System (INIS)

    The possibility to measure boron concentration with high precision in tissues that will be irradiated represents a fundamental step for a safe and effective BNCT treatment. In Pavia, two techniques have been used for this purpose, a quantitative method based on charged particles spectrometry and a boron biodistribution imaging based on neutron autoradiography. A quantitative method to determine boron concentration by neutron autoradiography has been recently set-up and calibrated for the measurement of biological samples, both solid and liquid, in the frame of the feasibility study of BNCT. This technique was calibrated and the obtained results were cross checked with those of α spectrometry, in order to validate them. The comparisons were performed using tissues taken form animals treated with different boron administration protocols. Subsequently the quantitative neutron autoradiography was employed to measure osteosarcoma cell samples treated with BPA and with new boronated formulations. - Highlights: • A method for 10B measurements in samples based on neutron autoradiography was developed. • The results were compared with those of alpha spectrometry applied on tissue and cell samples. • Boronated liposomes were developed and administered to osteosarcoma cell cultures. • Neutron autoradiography was employed to measure boron concentration due to liposomes. • Liposomes were proved to be more effective in concentrating boron in cells than BPA

  2. Separation of boron isotopes using NMG type anion exchange resin

    International Nuclear Information System (INIS)

    Ion exchange separation of boron isotopes (B-10 and B-11) has been studied by using a special boron selective ion exchange resin; NMG (n-methyl glucamine)-type anion exchange resin. The resin has shown a large isotope separation coefficient of 1.02 at the experimental conditions of temperature, 80degC, and boric acid concentration, 0.2 M (mole/dm3). Enriched B-10 (92%) was obtained after the migration of 1149 m by a recyclic operation of ion exchange columns in a merry-go-round method. (author)

  3. Towards an understanding of deep boron: study of type IIb blue diamonds

    Science.gov (United States)

    Gaillou, E.; Rost, D.; Post, J. E.; Butler, J. E.

    2012-12-01

    diamonds, which was confirmed by mapping active boron using synchrotron FTIR. ToF-SIMS gives the spectrum of all the masses at once, so both 11B and 10B were detected. However, the counts on 10B were too low at the counting time we used (several hours) to provide significant δ11B measurements. We observed that there is not a strong correlation between the amount of boron and the color intensity in type IIb diamonds (Gaillou et al., 2012). However, the deep-blue colored diamonds are always associated with a "high" boron content, and therefore, future attempted measurements of boron isotopic ratios should be conducted on deep blue (and unfortunately, valuable) diamonds, using either a much longer counting time, or a different ion mass spectrometer (with different standards), that would consume more material. This study shows that the range of boron concentration, even if in the lower range of instrument detectability, should soon be able to provide boron isotopic measurements, and perhaps gives insights into the origin of boron in diamonds, e.g. from a subducted slab and/or from primitive mantle reservoir. Chaussidon M., Marty B. (1995) Primitive boron isotope composition of the mantle, Science, 269, 383-386. Gaillou E., Rost D., Post J.E., Butler J.E. (2012) Boron in natural type IIb blue diamonds: chemical and spectroscopic measurements. Am. Min., 1, 1-18.

  4. A study on the behavior of boron in iron-base alloys by neutron induced autoradiography

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jin Sung; Rhee, Chang Kyu; Cho, Hae Dong; Han, Chang Hee; Lee, Chang Hee; Jung, Jung Hwan; Kim, Yi Kyung; Lee, Yong Bok

    2001-02-01

    Boron is widely utilized in steel or alloy making to improve certain properties. However, due to its lightness boron is difficult to detect or characterize its behavior even through TEM/EDS or EELS techniques. Although many companies recognize the beneficial effects of boron, the role or mechanism of the boron is not yet clearly understood. Therefore it is required to develop the autoradiography technique to elucidate the boron behavior in alloys. As the only institute operating research reactor in the country, it would be the responsibility of the institute to develop the technique and provide it to the industries. Quantitative analyses of boron in type 316 L stainless steel by neutron induced autoradiography was attempted in this study. Nine experimental reference alloys with different amount of boron were prepared and reliable chemical composition data were obtained. Autoradiographs of reference materials with three different neutron fluences ( 1.9 10{sup 13}, 1.9 10{sup 14} and 1.9 10{sup 15}/cm{sup 2} ) were obtained and a trial calibration curve of boron content vs. track density was acquired.

  5. Cosmis Lithium-Beryllium-Boron Story

    Science.gov (United States)

    Vangioni-Flam, E.; Cassé, M.

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

  6. Synovectomy by neutron capture in boron

    International Nuclear Information System (INIS)

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

  7. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

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

    2013-12-01

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

  8. The preparation and characterization of boron-containing phenolic fibers

    International Nuclear Information System (INIS)

    The boron-containing phenolic fibers were prepared by melt-spinning a mixture of novolak resin and boron acid followed by curing the filaments with formaldehyde solution in the presence of an acid catalyst. The resulting fibers were heat-treated in N2 at elevated temperatures. The results show that the addition of 1.0 wt% boron acid in the precursor resin can greatly increase thermal stability, mechanical strength and flame resistance of the resultant fibers. In comparison the boron-containing phenolic fibers with the pure phenolic fibers, the weight loss of the boron-containing phenolic fibers (BPF-1.0), heat-treated at 240 deg. C for 2 h, decreases from 60.5 to 39.1% in N2, from 32.8 to 14.1% in air. Whereas, the limited oxygen index increases from 32.5 to 37.2%; the tensile strength increases from 129.3 to 163.4 MPa.

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

    Indian Academy of Sciences (India)

    Wolfgang Kaim; Narayan S Hosmane

    2010-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-06-15

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

  11. Solvent extraction of boron complex with H-resorcinol and diphenylguanidine

    International Nuclear Information System (INIS)

    Conditions have been studied for the formation of a complex of boron with H-resorcinol (2.4-dihydroxybenzene-azo-8-hydroxynaphthalene-3.6-disulphoric acid) and diphenylguanidine (DPG) which is extracted into higher alcohols (pentanols). The component ratio in the complex is B:HR:DPG=1:1:2. The reaction between boron and H-resorcinol is significantly accelerated in the presence of DPG that makes it possible to apply the reaction to extraction-photometric determination of boron. The infrared studies have confirmed the quinone-hydrazone form of H-resorcinol in the complex with boron. The method allows to determine 1x10-4 - 5x10-2% of boron

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-21

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

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

    International Nuclear Information System (INIS)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. Boron diffusion in silicon devices

    Science.gov (United States)

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

    2010-09-07

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

  17. Ion implantation of boron in germanium

    Energy Technology Data Exchange (ETDEWEB)

    Jones, K.S.

    1985-05-01

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

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

    International Nuclear Information System (INIS)

    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)

  19. Boron Fullerenes: A First-Principles Study

    Directory of Open Access Journals (Sweden)

    Gonzalez Szwacki Nevill

    2007-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-08-01

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

  1. Commercial Clinical Application of Boron Neutron Capture Therapy

    International Nuclear Information System (INIS)

    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 (Na2B10H10) 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

  2. Commercial Clinical Application of Boron Neutron Capture Therapy

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-07-01

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

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

    Institute of Scientific and Technical Information of China (English)

    郎五可; 张卫江; 唐银; 徐姣; 张雷

    2016-01-01

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

  6. Microwave digestion techniques applied to determination of boron by ICP-AES in BNCT program

    International Nuclear Information System (INIS)

    Recently, boron neutron capture therapy (BNCT) has merged as an interesting option for the treatment of some kind of tumors where established therapies show no success. A molecular boronated species, enriched in 10B is administrated to the subject; it localizes in malignant tissues depending the kind of tumor and localization. Therefore, a very important fact in BNCT research is the detection of boron at trace or ultra trace levels precisely and accurately. This is extremely necessary as boronated species do localize in tumoral tissue and also localize in liver, kidney, spleen, skin, membranes. By this way, before testing a boronated species, it is mandatory to determine its biodistribution in a statistically meaning population, that is related with managing of a great number of samples. In the other hand, it is necessary to exactly predict when to begin the irradiation and to determine the magnitude of radiation to obtain the desired radiological dose for a specified mean boron concentration. This involves the determination of boron in whole blood, which is related with boron concentration in the tumor object of treatment. The methodology selected for the analysis of boron in whole blood and tissues must join certain characteristics: it must not be dependant of the chemical form of boron, it has to be fast and capable to determine boron accurately and precisely in a wide range of concentrations. The design and validation of experimental models involving animals in BNCT studies and the determination of boron in blood of animals and subjects upon treatment require reliable analytical procedures to determine boron quantitatively in those biologic materials. Inductively coupled plasma-atomic emission spectrometry (ICP-AES) using pneumatic nebulization is one of the most promising methods for boron analysis, but the sample must be liquid and have low solid concentration. In our case, biological tissues and blood, it is mandatory to mineralize and/or dilute samples

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

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A laboratory experiment was undertaken to investigate the behaviour of boron at theseawater-air interface under air flow conditions. Dried air at 25 and 35℃ was passed over or bub-bled through seawater at the same temperature. A combination of ice-chilled condensers and KOHimpregnated cellulose fibre filters was used to collect boron from the reacted air. When air strippedof boron was passed over the seawater, boron was found in the reacted air, and its concentrationwas higher in the higher temperature test. In the tests where air was bubbled through seawater theconcentration of boron in the reacted air was directly proportional to the air flow rate. In this situa-tion the boron in the reacted air was mainly introduced as a spray of microdroplets. Isotopic analy-sis of the collected boron in the non-bubbled tests yields fractionation factors which demonstratethat the lighter isotope, 10B, is enriched in the reacted air. The size of the fractionation changeswith temperature, ruling out a purely kinetic effect.

  8. Growth, yield, and calcium and boron uptake of tomato(Lycopersicon esculentum L.) and cucumber (Cucumis sativus L.) asaffected by calcium and boron humate application in greenhouse conditions

    OpenAIRE

    EKİNCİ, MELEK; ESRİNGÜ, ASLIHAN; DURSUN, ATİLLA; YILDIRIM, Ertan; TURAN, METİN; KARAMAN, MEHMET RÜŞTÜ; ARJUMEND, TUBA

    2015-01-01

    The objective of this study was to examine the effect of calcium humate, boron humate, and humic acid solutions on growth, yield, quality, and calcium and boron uptake of tomato (Lycopersicon esculentum L.) and cucumber (Cucumis sativus L.), as well as changes in soil nutrient status after crop harvest. Four different concentrations (500, 1000, 3000, and 5000 mg kg-1) of calcium humate (12% CaO, 15% humic and fulvic acid), boron humate (10% BOH4, 15% humic and fulvic acid), and humic acid (15...

  9. Exploratory calculations for boron capture therapy using epithermal neutron beams

    International Nuclear Information System (INIS)

    To get an insight into the problems of boron neutron capture therapy of brain tumours, some calculations of the neutron distribution in a spherical human skull have been made with an ANISN program. The energy of the source neutrons was varied from about 1 keV to about 100 keV. Two different neutron group structures were used with corresponding different cross section libraries. For a spherically symmetric irradiation of a skull with radius 10 cm a source neutron energy of about 50 - 100 keV gives a rather flat boron capture rate over a large part of the skull. This shows the advantage of using epithermal neutrons in the treatment of deepseated tumours by the boron neutron capture method. (Auth.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-01

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

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

    International Nuclear Information System (INIS)

    Intrinsic efficiencies of multi-layer boron-10 thin-film detectors were studied theoretically and experimentally. For multi-layer schemes based on an optimized single-layer film thickness, the practical efficiency is limited to about 42% for thermal neutrons. This is about half the efficiency of a moderated 3He detectors in commercial use for portal monitoring. The efficiency limitation is due to charged particle loss in the boron layers and substrates. The same loss mechanism will prevent all substrate-based boron detectors from ever reaching the intrinsic efficiencies of high-pressure 3He tubes, independent of substrate geometry and material composition. Experimental data also indicate that the multi-layer detector configuration can have an efficiency approaching the theoretical limit. Excellent n/γ discrimination has also been achieved using an ionization chamber.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-03-03

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

  14. Significance of ICPMS in performance evaluation of Boron Enrichment Plant and elemental boron plant at Heavy Water Plant, Manuguru - an indigenization effort

    International Nuclear Information System (INIS)

    Boron has two naturally occurring stable isotopes viz. 10B (natural abundance ∼ 20%) and 11B. Due to very high neutron absorption cross section, 10B has important applications in the nuclear field. It is used in neutron detector (10B ≅90%) and as control material in fast breeder reactor (10B ≅65%). Heavy Water Board is involved in production of enriched boron (10B) using Ion Exchange Chromatography technique and Exchange Distillation technique. For boron isotope ratio measurement, properly tuned ICPMS gives quick analysis with good precision. During Plant operation, monitoring of each stage is essential. As sample load is very high, therefore a quick analysis technique is required. Though boron isotope ratio measurement on ICPMS has some limitation in terms of its low mass, memory effect etc., if proper care, in terms of plasma stability, can be taken, then ICPMS is the best choice. As ICPMS covers the full isotope concentration range, boron samples from Boron Enrichment Plant have been analysed on the above mentioned ICPMS routinely

  15. Tribological behavior of improved chemically vapor-deposited boron on beryllium

    International Nuclear Information System (INIS)

    Earlier chemical vapor deposition (CVD) experiments with diborane as the boron source gave well-bonded boron films up to 10 μm thick on beryllium, with layered intermetallic compounds below a top layer of boron. The films were nonuniform in thickness and cracked badly when given diffusion heat treatments to produce desired intermetallic compounds. By rotating the beryllium samples during the CVD, films of uniform thickness have now been produced. A variety of compounds of beryllium and boron have been produced on the outer surface of the CVD film by varying the concentration of diborane in the CVD gas. Wear and friction tests performed on various CVD surfaces using sapphire and diamond pins showed remarkable differences in that the CVD boron surface appeared to be substantially more compatible with diamond than with sapphire. The results of these tests are discussed. (Auth.)

  16. Thermal conductivity of boron carbide-boron nitride composites

    International Nuclear Information System (INIS)

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

  17. Irradiation Effects in Fortiweld Steel Containing Different Boron Isotopes

    International Nuclear Information System (INIS)

    Tensile specimens and miniature impact specimens of the low alloyed pressure vessel steel Fortiweld have been irradiated at 265 deg C in R2 to two neutron doses, 6.5 x 1018 n/cm2 (> 1 MeV) and 4 x 1019 n/cm2 (thermal) and also 9.0 x 1018 n/cm2 (> 1 MeV) and 6 x 1019 n/cm2 (thermal). Material from three laboratory melts, in which the boron consisted of 10B, 11B and natural boron respectively, were investigated. The results both of tensile tests and impact tests with miniature impact specimens show that the 10B-alloyed material was changed more and the 11B-alloyed material was changed less than the material containing natural boron. At the higher neutron dose the increase in yield strength (0.2 % offset yield strength) was 11 kg/mm in the 10B containing material compared to 5 kg/mm in the 11B-containing material. The decrease in total elongation was 5 and 0 percentage units respectively. The transition temperature was increased 190 deg C at the higher neutron dose in the 10B-alloyed material, 40 deg C in the 11B-alloyed material and 80 deg C in the material containing natural boron

  18. Micrometric rods grown by nanosecond pulsed laser deposition of boron carbide

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Quintas, Ignacio; Oujja, Mohamed; Sanz, Mikel; Benitez-Cañete, Antonio [Instituto de Química Física Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain); Chater, Richard J. [Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Cañamares, Maria Vega [Instituto de Estructura de la Materia, CSIC, Serrano 119, 28006 Madrid (Spain); Marco, José F. [Instituto de Química Física Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain); Castillejo, Marta, E-mail: marta.castllejo@iqfr.csic.es [Instituto de Química Física Rocasolano, CSIC, Serrano 119, 28006 Madrid (Spain)

    2015-02-15

    Highlights: • Micrometric rods obtained by ns pulsed laser deposition of boron carbide at 1064 and 266 nm. • At 1064 nm microrods display crystalline polyhedral shape with sharp edges and flat sides. • Microrods consist of a mixture of boron, boron oxide, boron carbide and aliphatic hydrocarbons. - Abstract: Micrometric size rods have been fabricated via pulsed laser deposition in vacuum from boron carbide targets using nanosecond pulses of 1064 and 266 nm and room temperature Si (1 0 0) substrates. Morphological, structural and chemical characterization of the microrods was made by applying scanning electron microscopy, focussed ion beam microscopy coupled to secondary ion mass spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy and micro-Raman spectroscopy. Ablation at 1064 nm favours the formation of microrods with high aspect ratio, sharp edges and pyramidal tips, typically 10 μm long with a cross section of around 2 μm × 2 μm. Differently, at 266 nm the microrods are of smaller size and present a more globular aspect. The analyses of the microrods provide information about their crystalline nature and composition, based on a mixture which includes boron, boron oxide and boron carbide, and allows discussion of the wavelength dependent growth mechanisms involved.

  19. Micrometric rods grown by nanosecond pulsed laser deposition of boron carbide

    International Nuclear Information System (INIS)

    Highlights: • Micrometric rods obtained by ns pulsed laser deposition of boron carbide at 1064 and 266 nm. • At 1064 nm microrods display crystalline polyhedral shape with sharp edges and flat sides. • Microrods consist of a mixture of boron, boron oxide, boron carbide and aliphatic hydrocarbons. - Abstract: Micrometric size rods have been fabricated via pulsed laser deposition in vacuum from boron carbide targets using nanosecond pulses of 1064 and 266 nm and room temperature Si (1 0 0) substrates. Morphological, structural and chemical characterization of the microrods was made by applying scanning electron microscopy, focussed ion beam microscopy coupled to secondary ion mass spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy and micro-Raman spectroscopy. Ablation at 1064 nm favours the formation of microrods with high aspect ratio, sharp edges and pyramidal tips, typically 10 μm long with a cross section of around 2 μm × 2 μm. Differently, at 266 nm the microrods are of smaller size and present a more globular aspect. The analyses of the microrods provide information about their crystalline nature and composition, based on a mixture which includes boron, boron oxide and boron carbide, and allows discussion of the wavelength dependent growth mechanisms involved

  20. Evaluation of the reduction of boron-10 in the control rods in the BWR of the Laguna Verde Central, through steady state calculations; Evaluacion de la reduccion del Boro-10 en las barras de control en los BWR de la CLV, mediante calculos en estado estacionario

    Energy Technology Data Exchange (ETDEWEB)

    Montes T, J.L.; Perusquia, R.; Hernandez, J.L.; Ramirez S, J.R. [Departamento de Sistemas Nucleares, ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2003-07-01

    One of the more important aspects related with the safety and economy in the operation of a nuclear power reactor, it is without a doubt the control of the reactivity. During the normal operation of a reactor of boiling water (BWR-Boiling Water Reactor), the control of the reactivity in the nucleus it is strongly determined by the efficiency of the control rods. In the case of the Laguna Verde Nuclear power station (CNLV) the nucleus of the reactors has 109 control rods grouped in 4 sets. The CNLV at the moment uses the CCC method (Control Cell Core) in the design of the cycle. With this method only the A2 group is used for the control of the reactivity at full power. With the purpose of quantifying the effect of the decrease of the burnable poison (B{sub 4}C) of the control rods and in particular to the effect due to the postulated lost of 10% of Boron 10, it was carried out a series of calculations of the nucleus in stationary state by means of the system of HELIOS/CM-PRESTO codes. In this work the main derived results of these 3D simulations(three dimensions) of the reactors of the CNLV are presented. It was analyzed the one behavior of the infinite neutron multiplication factor (K{sub infinite}), at fuel assemble cell level used in an equilibrium cycle for the CNLV. It was also analyzed the effect in the shutdown margin (ShutDown Margin- SDM) in cold condition CZP (Cold Zero Power). Its are also included those results of the ARI cases (All Rods In) and SRO (Strong Rod Out). From the cases in condition HFP (Hot Full Power) the behavior of the effective multiplication factor (K{sub eff}) is presented. (Author)

  1. Enhanced therapeutic effect on murine melanoma and angiosarcoma cells by boron neutron capture therapy using a boronated metalloporphyrin

    International Nuclear Information System (INIS)

    We have already achieved successful treatment of several human patients with malignant melanoma by boron neutron capture therapy (BNCT) using 10B1-paraboronophenylalanine (10B1-BPA·HCl). In this study we used a new compound, a manganese boronated protoporphyrin (Mn-10BOPP), and compared it to 10B1-BPA·HCl with respect to uptake in murine melanoma and angiosarcoma cells as well as to their cell killing effect. 10B uptake was measured in a new method, and the new compound was much more incorporated into both cells than 10B1-BPA·HCl. Furthermore, melanoma and angiosarcoma cells preincubated with the new compound were 15 to 20 times more efficiently killed by BNCT than cells preincubated with 10B1-BPA·HCl. (author)

  2. Boron carbide nanolumps on carbon nanotubes

    Science.gov (United States)

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

    2002-01-01

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

  3. Boron enrichment by ion exchange with Dowex 1X8 anion resin

    International Nuclear Information System (INIS)

    An isotopic separation pilot plant with five ion exchange columns interconnected in series were designed and built in the IEN. The boric acid solution is introduced in the separation columns until it reaches a absorbing zone lenght which is sufficient to obtain the desired boron-10 isotopic concentration. The boric acid absorbing zone movement is provided by the injection of a diluted hydrochloric acid solution, which replces the boric acid troughout the columns to its total lenght. The enriched boron-10 and the depleted boron are located in the final boundary and in the initial position of the absorbing zones, respectively. (author). 6 refs

  4. Production of polyoxoboronate as novel boron compound

    International Nuclear Information System (INIS)

    Polyoxometalates are negatively charged inorganic substances which contain early transitional metal ions such as tungsten, molybdenum, making a cluster with the surrounding oxygen atoms. We prepared novel boron compound, (H15[V1210B32O84Na4]·13H2O; 10B32), as the structure of polyoxometalates. With thermal neutron irradiation, 10B32 shows cytotoxic effect on the proliferation of AsPC-1 cells in colony formation assay. On BNCT model mice bearing AsPC-1, 10B32 shows tumor growth suppression, as well. These results indicate that 10B32 has anti-tumor activity being functioned as a novel neutron capture agent. (author)

  5. NEW ADVANCES IN BORON SOIL CHEMISTRY

    Science.gov (United States)

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

  6. Tumor growth suppression by boron neutron capture therapy using PEG-liposomal boron delivery in vivo

    International Nuclear Information System (INIS)

    The tumor cell destruction in boron neutron-capture therapy (BNCT) is due to the nuclear reaction between 10B and thermal neutrons. We prepare a polyethylene glycol (PEG) binding liposome (DPPC/cholesterol/DSPC-PEG2000) entrapped 10B compound for the delivery system. We evaluated the cytotoxic effects of intravenously injected 10B-PEG-liposome on human pancreatic carcinoma (AsPC-1) xenografts in nude mice with thermal neutron irradiation. After thermal neutron irradiation of mice injected with 10B-bare liposome or 10B-PEG-liposome, AsPC-1 tumour growth was suppressed relative to controls. Injection of 10B-PEG-liposome caused the greatest tumour suppression with thermal neutron irradiation in vivo. These results suggests that intravenous injection of 10B-PEG-liposome can increase the retention of 10B atoms by tumor cells, causing tumor growth suppression in vivo upon thermal neutron irradiation. (author)

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

    International Nuclear Information System (INIS)

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

  8. Boron isotope separation by ion exchange chromatography using weakly basic anion exchange resin

    International Nuclear Information System (INIS)

    Isotopic plateau displacement chromatography, a useful method for isotope separation is presented. The boric acid band formed in a column of weakly basic anion exchange resin Diaion WA21 can be eluted with pure water. In order to obtain good accumulation of the isotope effect, a series of experiments with different migration length were carried out. The boron-10 enriched part of the boric acid absorbed band was always preceded by the isotopic plateau part, in which the atomic fraction of boron-10 was maintained at its original value. The atomic fraction of boron-10 at the end of the chromatogram increased with migration length, and in the case of 256-m migration, boron-10 was enriched from its original atomic fraction of 19.84 to 91.00%, the separation factor S being constant irrespective of migration length: S = 1.0100 +- 0.0005. (author)

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Zubkov, V. I., E-mail: VZubkovspb@mail.ru; Kucherova, O. V.; Zubkova, A. V.; Ilyin, V. A.; Afanas' ev, A. V. [St. Petersburg State Electrotechnical University (LETI), Professor Popov Street 5, 197376 St. Petersburg (Russian Federation); Bogdanov, S. A.; Vikharev, A. L. [Institute of Applied Physics of the Russian Academy of Sciences, Ul' yanov Street 46, 603950 Nizhny Novgorod (Russian Federation); Butler, J. E. [St. Petersburg State Electrotechnical University (LETI), Professor Popov Street 5, 197376 St. Petersburg (Russian Federation); Institute of Applied Physics of the Russian Academy of Sciences, Ul' yanov Street 46, 603950 Nizhny Novgorod (Russian Federation); National Museum of Natural History (NMNH), P.O. Box 37012 Smithsonian Inst., Washington, D.C. 20013-7012 (United States)

    2015-10-14

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

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

    Science.gov (United States)

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

    2015-10-01

    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 × 10-13 down to 2 × 10-17 cm2 was noticed. Moreover, for the hopping conduction the capture cross section becomes 4 orders of magnitude less (˜2 × 10-20 cm2). At T > Troom 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.

  12. Boron steel. I Part. Preparation

    International Nuclear Information System (INIS)

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

  13. Shear amorphization of boron suboxide

    International Nuclear Information System (INIS)

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

  14. Thermal conductivity of boron carbides

    Science.gov (United States)

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

    1985-01-01

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

  15. Mechanical properties of boron coatings

    International Nuclear Information System (INIS)

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

  16. Determination of boron spectrophotometry in thorium sulfate

    International Nuclear Information System (INIS)

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

  17. Axial channeling of boron ions into silicon

    Science.gov (United States)

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

    1992-04-01

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

  18. Axial channeling of boron ions into silicon

    Energy Technology Data Exchange (ETDEWEB)

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

    1992-04-01

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

  19. Benefits of Low Boron Core Design Concept for PWR

    Energy Technology Data Exchange (ETDEWEB)

    Daing, Aung Tharn; Kim, Myung Hyun [Kyung Hee University, Yongin (Korea, Republic of)

    2009-10-15

    Nuclear design study was carried out to develop low boron core (LBC) based on one of current PWR concepts, OPR-1000. Most of design parameters were the same with those of Ulchin unit-5 except extensive utilization of burnable poison (BP) pins in order to compensate reactivity increase in LBC. For replacement of reduced soluble boron concentration, four different kinds of integral burnable absorbers (IBAs) such as gadolinia, integral fuel burnable absorber (IFBA), erbia and alumina boron carbide were considered in suppressing more excess reactivity. A parametric study was done to find the optimal core options from many design candidates for fuel assemblies and cores. Among them, the most feasible core design candidate was chosen in accordance with general design requirements. In this paper, the feasibility and design change benefits of the most favorable LBC design were investigated in more detail through the comparison of neutronic and thermal hydraulic design parameters of LBC with the reference plant (REF). As calculation tools, the HELIOS/MASTER code package and the MATRA code were utilized. The main purpose of research herein is to estimate feasibility and capability of LBC which was mainly designed to mitigate boron dilution accident (BDA), and for reduction of corrosion products. The LBC design concept using lower boron concentration with an elevated enrichment in {sup 10}B allows a reduction in the concentration of lithium in the primary coolant required to maintain the optimum coolant pH. All in all, LBC with operation at optimum pH is expected to achieve some benefits from radiation source reduction of reduced corrosion product, the limitation of the Axial Offset Anomaly (AOA) and fuel cladding corrosion. Additionally, several merits of LBC are closely related to fluid systems and system related aspects, reduced boron and lithium costs, equipment size reduction for boric acid systems, elimination of heat tracing, and more aggressive fuel design concepts.

  20. Monte-Carlo simulation of primary stochastic effects induced at the cellular level in boron neutron capture therapy; Simulation Monte-Carlo des effets stochastiques primaires induits au niveau cellulaire lors de la therapie par capture de neutrons sur le {sup 10}B

    Energy Technology Data Exchange (ETDEWEB)

    Cirioni, L.; Patau, J.P.; Nepveu, F. [Universite Paul Sabatier, 31 - Toulouse (France)

    1998-04-01

    A Monte Carlo code is developed to study the action of particles in Boron Neutron Capture Therapy (BNCT). Our aim is to calculate the probability of dissipating a lethal dose in cell nuclei. Cytoplasmic and nuclear membranes are considered as non-concentric ellipsoids. All geometrical parameters may be adjusted to fit actual configurations. The reactions {sup 10}B(n,{gamma} {alpha}){sup 7}Li and {sup 14}N(n,p) {sup 14}C create heavy ions which slow clown losing their energy. Their trajectories can be simulated taking into account path length straggling. The contribution of each reaction to the deposited dose in different cellular compartments can be studied and analysed for any distribution of {sup 10}B. (authors)

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

    International Nuclear Information System (INIS)

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

  2. Alleviation of Boron Stress through Plant Derived Smoke Extracts in Sorghum bicolor

    Directory of Open Access Journals (Sweden)

    Pirzada Khan

    2014-08-01

    Full Text Available Boron is an essential micronutrient necessary for plant growth at optimum concentration. However, at high concentrations boron affects plant growth and is toxic to cells. Aqueous extract of plant-derived smoke has been used as a growth regulator for the last two decades to improve seed germination and seedling vigor. It has been established that plant-derived smoke possesses some compounds that act like plant growth hormones. The present research was the first comprehensive attempt to investigate the alleviation of boron stress with plant-derived smoke aqueous extract on Sorghum (Sorghum bicolor seed. Smoke extracts of five plants, i.e. Cymbopogon jwarancusa, Eucalyptus camaldulensis, Peganum harmala, Datura alba and Melia azedarach each with six dilutions (Concentrated, 1:100, 1:200, 1:300, 1:400 and 1:500 were used. While boron solutions at concentrations of 5, 10, 15, 20 and 25 ppm were used for stress. Among the dilutions of smoke, 1:500 of E. camaldulensis significantly increased germination percentage, root and shoot length, number of secondary roots and fresh weight of root and shoot while, boron stress reduced growth of Sorghum. It was observed that combined effect of boron solution and E. camaldulensis smoke extract overcome inhibition and significantly improved plant growth. Present research work investigated that the smoke solution has the potential to alleviate boron toxicity by reducing the uptake of boron by maintaining integrity of plant cell wall. The present investigation suggested that plant derived smoke has the potential to alleviate boron stress and can be used to overcome yield losses caused by boron stress to plants.

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

    Science.gov (United States)

    Kurachi, Ikuo; Yoshioka, Kentaro

    2015-09-01

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

  4. Boron Neutron Capture Therapy for Malignant Brain Tumors

    Science.gov (United States)

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

    2016-01-01

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

  5. Analysis of boronized wall in LHD

    International Nuclear Information System (INIS)

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

  6. Boron Poisoning of Plutonium Solutions

    International Nuclear Information System (INIS)

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

  7. Boron sorption characteristics in resins

    International Nuclear Information System (INIS)

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

  8. Advanced microstructure of boron carbide.

    Science.gov (United States)

    Werheit, Helmut; Shalamberidze, Sulkhan

    2012-09-26

    The rhombohedral elementary cell of the complex boron carbide structure is composed of B(12) or B(11)C icosahedra and CBC, CBB or B□B (□, vacancy) linear arrangements, whose shares vary depending on the actual chemical compound. The evaluation of the IR phonon spectra of isotopically pure boron carbide yields the quantitative concentrations of these components within the homogeneity range. The structure formula of B(4.3)C at the carbon-rich limit of the homogeneity range is (B(11)C) (CBC)(0.91) (B□B)(0.09) (□, vacancy); and the actual structure formula of B(13)C(2) is (B(12))(0.5)(B(11)C)(0.5)(CBC)(0.65)(CBB)(0.16) (B□B)(0.19), and deviates fundamentally from (B(12))CBC, predicted by theory to be the energetically most favourable structure of boron carbide. In reality, it is the most distorted structure in the homogeneity range. The spectra of (nat)B(x)C make it evident that boron isotopes are not randomly distributed in the structure. However, doping with 2% silicon brings about a random distribution. PMID:22945740

  9. Boron isotopes in geothermal systems

    International Nuclear Information System (INIS)

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

  10. Isotopic effect on thermal physical properties of isotopically modified boron single crystals

    International Nuclear Information System (INIS)

    The measurement of specific heat and thermal conductivity at low temperature for isotopically modified boron single crystals was performed between 0.5 and 100K using relaxation method and steady heat flow method, respectively. The results indicate that the specific heat has obvious divergences at T10B-enriched crystal is about 570 W/m·K, which is 40% larger than that of natural boron crystal. The influence of lattice vibration modes and the isotopic effect on specific heat and thermal conductivity for isotopically modified boron are discussed. (author)

  11. Novel semiconducting boron carbide/pyridine polymers for neutron detection at zero bias

    International Nuclear Information System (INIS)

    Thin films containing aromatic pyridine moieties bonded to boron, in the partially dehydrogenated boron-rich icosahedra (B10C2HX), prove to be an effective material for neutron detection applications when deposited on n-doped (100) silicon substrates. The characteristic I-V curves for the heterojunction diodes exhibit strong rectification and largely unperturbed normalized reverse bias leakage currents with increasing pyridine content. The neutron capture generated pulses from these heterojunction diodes were obtained at zero bias voltage although without the signatures of complete electron-hole collection. These results suggest that modifications to boron carbide may result in better neutron voltaic materials. (orig.)

  12. Critical boron-doping levels for generation of dislocations in synthetic diamond

    OpenAIRE

    Alegre, Maria De La Paz; Araújo, Daniel; Fiori, Alexandre; Pinero, Jose Carlos; Lloret, Fernando; Villar, Maria Del Pilar; Achatz, Philippe; Chicot, Gauthier; Bustarret, Etienne; F. Jomard

    2014-01-01

    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 CH4 /H2 molar ratios and on growth directions. The critical boron concentration lied in the 6.5–17.0 X 10 20 at/cm3 range in the direction and at 3.2 X 1021 at/cm 3 for the one. Strain related effects induced by the doping are shown not to be respon...

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

    International Nuclear Information System (INIS)

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

  14. Friction anisotropy in boronated graphite

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-01

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

  15. Friction anisotropy in boronated graphite

    International Nuclear Information System (INIS)

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

  16. Analysis of boron carbides' electronic structure

    Science.gov (United States)

    Howard, Iris A.; Beckel, Charles L.

    1986-01-01

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

  17. Pressure-dependent boron isotopic fractionation observed by column chromatography

    Science.gov (United States)

    Musashi, M.; Oi, T.; Matsuo, M.; Nomura, M.

    2007-12-01

    Boron isotopic fractionation factor ( S ) between boron taken up in strongly basic anion exchange resin and boron in aqueous solution was determined by breakthrough column chromatography at 5 and 17 MPa at 25°C, using 0.1 mmol/L boric acid solution as feed solution. The S values obtained were 1.018 and 1.012, respectively, which were smaller than the value reported by using the same chromatographic method at atmospheric pressure at 25°C with the boron concentration of 10 mmol/L, but were larger than the values at the same condition with much higher concentration of 100 and 501 mmol/L, indicating that borate-polymerization reducing the isotopic fractionation was negligible. However, calculations based on the theory of isotope distribution between two phases estimated that 21% (5MPa) and 47% (17MPa) of boron taken up in the resin phase was in the three-coordinated B(OH)3-form, instead of in the four-coordinated B(OH)4--form, at high pressures even with the very diluted solution. We discussed this discrepancy by introducing (1) hydration or (2) a partial molar volume difference between isotopic molecules. It was inferred that borate ions were partially dehydrated upon transfer from the solution phase to the resin phase at high pressures, which resulted in smaller S values compared with those at the atmospheric pressure. Alternatively, it was likely that the S value decreased with increasing pressure, because the difference of the partial isotopic molar volumes between 10B(OH)3 and 11B(OH)3 was larger than that between 10B(OH)4- and 11B(OH)4-. If either will be the case, the influence of a pressure upon the isotope effect may not be negligible for boron isotopic exchange equilibrium. This knowledge is crucial for the principle of the boron isotopic pH-metry reconstructing a chemical variation at the paleo-deep oceanic environment where the early life may have been evolved.

  18. Effects of boron on experimental dental caries activity

    Energy Technology Data Exchange (ETDEWEB)

    Liu, F.T.Y.; Lin, H.S.

    1974-01-01

    Drinking water supplemented with 1, 10, 30, 50, 100 or 283 ppM of boron or 10 or 25 ppM of fluoride individually or in combination was supplied to weanling rats which were fed a cariogenic diet. Results showed that B did not exert a cariostatic effect nor did it synergize the F in reducing dental caries activity. 11 references, 4 figures, 3 tables.

  19. Coating on steel ST-37 type with nano powder pack of boron carbide

    International Nuclear Information System (INIS)

    Steel ST-37 is a material widely used in industry. The quality of steel ST-37 can be improved by means of surface coating. At present the development of the technology shows the tendency toward nanoscience and nanotechnology that can be applied to various fields, among others energy, industry, medicine, information technology and communication as well as food necessitated by people at competitive selling prices. The steps in powder pack boronizing include: Pre-treatment, powder preparation, boronizing agent preparation, container preparation, boronizing process, metallography, hardness testing and corrosion testing. From the study, it is concluded as follows. The mechanism of boronizing process is divided into three stages, which are the boride compound formation stage, the diffusion stage, and the grain growth and orientation stage. Carbon in B4C on boronizing process does not diffuse into the substrate. The formation of boride compound begins to occur at a temperature of 600 °C, the diffusion process at 700 °C, and the grain growth and orientation at 800 °C. The hardness of boron coating reaches a value of 1115 VHN. Coating by boronizing process shows corrosion resistance in 10% HCl. (author)

  20. Model for the boron-doping dependence of the critical temperature of superconducting boron-doped diamond

    Czech Academy of Sciences Publication Activity Database

    Šopík, Břetislav

    2009-01-01

    Roč. 11, č. 10 (2009), 103026/1-103026/10. ISSN 1367-2630 R&D Projects: GA AV ČR IAA100100712 Grant ostatní: GAČR(CZ) GA202/07/0597 Institutional research plan: CEZ:AV0Z10100521 Keywords : superconductivity * boron-doped diamond Subject RIV: BE - Theoretical Physics Impact factor: 3.312, year: 2009

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

    Science.gov (United States)

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

    2010-03-12

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

  2. Synthesis of boron nitride nanotubes by boron ink annealing

    International Nuclear Information System (INIS)

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

  3. Boron isotope fractionation in magma via crustal carbonate dissolution

    Science.gov (United States)

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

    2016-08-01

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

  4. The determination of boron in aluminium of high purity

    International Nuclear Information System (INIS)

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

  5. Very high energy implants of boron into silicon

    Science.gov (United States)

    La Ferla, A.; Rimini, E.; Ciavola, G.; Ferla, G.

    1989-02-01

    Boron ions of energy in the 15-50 MeV range and doses in the 10 13-10 15 cm -2 range were implanted into 1 kΩ cm n-type silicon wafers. The samples, after annealing at 800-1250 ° C, were analyzed by spreading resistance profilometry. A simple model was used to predict the range distribution of the implanted ions. The measured projected ranges compare moderately well with calculations, while the concentration in the long tail up to the surface is two to three orders of magnitude higher than that calculated. Annealing at 1250 ° C for 24 h of multiple energy boron implants gives rise to a nearly flat profile with a concentration of 5 × 10 16 cm -3 over 100 μm. A diode with a junction depth of about 120 μm was realized.

  6. Spectrophotometric determination of boron in ammonium diuranate and interference studies

    International Nuclear Information System (INIS)

    This paper describes determination of boron in ammonium diuranate by spectrophotometry employing curcumin as a complexing agent after extraction of boron with 2-ethyl hexane 1,3 diol. Two diluents namely ethyl alcohol (EtOH) and N,N-dimethyl formamide (DMF) were investigated for the preparation of final solution. It was observed that the blank is less with DMF presumably due to higher extent of deprotonation of uncomplexed curcumin. The detection limits of method for 25 and 10 ml dilution are 20 ng and 10 ng respectively. Interference studies for several cation and anion species like Al, Cr, Mg, Ca, Fe, Mn, Mo, F, W, NO, and different amount of 10% EHD in CHCl3 are also discussed. (author)

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2015-04-01

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

  9. Synthesis of Boron Nanowires, Nanotubes, and Nanosheets

    Directory of Open Access Journals (Sweden)

    Rajen B. Patel

    2015-01-01

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

  10. Analysis of magnetron sputtered boron oxide films

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-10-15

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

  11. Microwave sintering of boron carbide composites

    International Nuclear Information System (INIS)

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

  12. Prediction of boron carbon nitrogen phase diagram

    Science.gov (United States)

    Yao, Sanxi; Zhang, Hantao; Widom, Michael

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

  13. Boron clusters in luminescent materials.

    Science.gov (United States)

    Mukherjee, Sanjoy; Thilagar, Pakkirisamy

    2016-01-21

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

  14. Conduction mechanism in boron carbide

    Science.gov (United States)

    Wood, C.; Emin, D.

    1984-01-01

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

  15. Sintering behavior of boron carbide

    International Nuclear Information System (INIS)

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

  16. Boron Enrichment in Martian Clay

    OpenAIRE

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

    2013-01-01

    We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest minera...

  17. Determination of the critical conditions for the initiation of dynamic recrystallization in boron microalloyed steels

    International Nuclear Information System (INIS)

    Research highlights: → Critical conditions for the DRX onset of boron microalloyed steels are determined. → σc and εc tend to increase as strain rate increases and temperature decreases. → σc and εc tend to decrease as boron content increases. → Critical ratios σc/σp and εc/εp remain fairly constant (∼0.82 and ∼0.53). → Boron additions promote solid solution softening and acceleration of the DRX onset. - Abstract: From the present research, the critical conditions associated with the onset of dynamic recrystallization (DRX) of hot deformed boron microalloyed steels were precisely determined based on changes in the strain hardening rate (θ) as a function of the flow stress. For this purpose, a low carbon steel microalloyed with four different amounts of boron (29, 49, 62 and 105 ppm) was deformed by uniaxial hot-compression tests at high temperature (950, 1000, 1050 and 1100 deg. C) and constant true strain rate (10-3, 10-2 and 10-1 s-1). Results indicate that the critical conditions for the initiation of dynamic recrystallization depend on the temperature and strain rate. In addition, both critical stress σc, and critical strain εc, were noticed to decrease as boron content increased. Such a behavior is attributed to a solute drag effect by boron atoms on the austenitic grain boundaries and also to a solid solution softening effect. The critical ratios σc/σp and εc/εp for all boron microalloyed steels remain fairly constant (∼0.82 and ∼0.53, respectively), such values are in agreement with those commonly reported for Al-killed, C-Mn, Nb, Nb-Ti, high carbon and stainless steels.

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

    Science.gov (United States)

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

    2014-01-01

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

  19. Boron deposition from fused salts. Final report

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

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

    2010-01-01

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

  1. On characterization of deformation microstructure in Boron modified Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Addition of boron in small quantities to various titanium alloys have shown significant improvement in mechanical behavior of materials. In the present study, electron back-scatter diffraction (EBSD) techniques have been applied to investigate the deformation microstructure evolution in boron modified two-phase titanium alloy Ti-6Al-4V. The alloy was hot compressed at 750 deg. C up to 50% height reduction at two different strain rates (10-3 s-1 and 1 s-1). The EBSD analyses indicated significant differences in deformed microstructure of the base alloy and the alloy containing boron. A strong subgrain formation tendency was observed along with inhomogeneous distribution of dislocations inside large α colonies of Ti64. In contrast, α colonies were relatively strain free for Ti64 + B, with more uniform dislocation density distribution. The observed difference is attributed to microstructural modifications viz. grain size refinement and presence of TiB particles at grain boundary produced due to boron addition.

  2. Methods of synthesizing boron carbide powder and controlling its sintering piece density

    International Nuclear Information System (INIS)

    The boron carbide powder is synthesized directly and its composition, lattice constant and mean particle size are measured, the optimum technological parameters of synthetic reaction are determined experimentally. The volume density control method of hot pressing sintering boron carbide are studied, and its microstructure and properties are tested. The maximal deviation of volume density of sintering boron carbide is +-2% of theory density (T.D.), when position limitation piece in the furnace is used to control the piece density precision. The various property indexes of the sintered boron carbide with 92% T.D. of volume density can reach or exceed the various reference values required by the performance of reactor. The bending strength of the sintered piece gets about 10% lower when temperature increases from normal temperature to 600 degree C

  3. In ovo administration of boron alters bone mineralization of the chicken embryo.

    Science.gov (United States)

    King, N; Odom, T W; Sampson, H W; Pardue, S L

    1991-07-01

    It has been hypothesized that boron (B) is an essential element for animals, especially in bone metabolism. In this study, the influence of in ovo boron administration was assessed in the chicken. At 8 d of embryogenesis, carrier or B (0.1, 0.5, or 1.0 mg) was injected on to the chorioallantoic membrane of fertile eggs. At hatching, body weights were recorded and tissue samples collected. Although boron failed to alter bone mineralization, it decreased (p less than 0.05) dried bone weight, suggesting a reduction in the bone organic matrix. Furthermore, 1 mg boron decreased (p less than 0.05) hatchability and increased (p less than 0.05) the height of the proliferative zone in the growth plate, indicating an unfavorable effect on bone elongation of the developing chick. PMID:1718368

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

    International Nuclear Information System (INIS)

    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 10B 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

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

    International Nuclear Information System (INIS)

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

  6. Crystal structure refinement of reedmergnerite, the boron analog of albite

    Science.gov (United States)

    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.

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

    Institute of Scientific and Technical Information of China (English)

    赵志琦; 刘丛强; 肖应凯; 郎赟超

    2003-01-01

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

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

    International Nuclear Information System (INIS)

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

  9. Preparation of Boric-10 Acid Applied in Nuclear Industry

    Institute of Scientific and Technical Information of China (English)

    张雷; 张卫江; 徐姣; 李波

    2015-01-01

    Because of the superior features of boron-10 isotope in absorbing hot neutrons, boric-10 acid (H310BO3) has been used widely in nuclear industry. Boric-10 acid is obtained from boron-10 trifluoride (10BF3) by esterification and hydrolyzation. In this study, trimethyl borate-10 [(CH3O)310B] was prepared from boron-10 trifluoride (10BF3) through chemical exchange rectification. In addition, the hydrolyzation of trimethyl borate-10 was investigated with different pH values, temperatures and molar ratios of water to trimethyl borate-10. Under the optimum process condi-tions, high yield of boric-10 acid with nuclear industrial purity grade was realized.

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

    Institute of Scientific and Technical Information of China (English)

    XIAO; Yingkai

    2001-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2014-11-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-12-14

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-06-15

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

  16. Studies related to antibody-mediated boron delivery for BNCT

    International Nuclear Information System (INIS)

    Of the many methods of selective boron delivery to tumor presently under consideration the use of boron-labeled tumor-targeted monoclonal antibodies (Mabs) and their immunoreactive fragments appears to offer the most general, but complex, approach. Assuming that tumor cells generally carry 106 characteristic antigenic sites of any one type and that there are approximately 109 cells per gram of tumor, one calculates that about 600 10B atoms must be attached to each individual Mab molecule (if all antigenic sites are complexed) for each 10 ppm of 10B supplied to tumor. Rather than randomly attack IgG Mab molecules with a large number of relatively small boron-containing conjugation reagent molecules the authors have chosen to assemble a series of discrete, precisely synthesized oligomeric reagents ('trailers') each of which contains a fixed number of B-atoms up to approximately 200. These oligomeric reagents would carry a radioactive or fluorescent group for analytical purposes attached to a terminal-NH2 group of their chain and the remaining -COOH terminus would be free for conjugation with the lysine var-epsilon-NH2 groups of Mab protein. Two types of oligomeric trailer reagents are envisioned; hydrophilic peptides and polyamides

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-04-01

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

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

    International Nuclear Information System (INIS)

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

  19. Boron carbide synthesis by carbothermic reduction of boron oxide

    International Nuclear Information System (INIS)

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

  20. Possible toxicity of boron on sugar cane

    Energy Technology Data Exchange (ETDEWEB)

    Bravo C., M.

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

  1. New techniques for producing thin boron films

    International Nuclear Information System (INIS)

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

  2. Fabrication of boron-phosphide neutron detectors

    International Nuclear Information System (INIS)

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

  3. Computational Evidence for the Smallest Boron Nanotube

    Institute of Scientific and Technical Information of China (English)

    Xian Jie LIN; Dong Ju ZHANG; Cheng Bu LIU

    2006-01-01

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

  4. Boron carbide whiskers produced by vapor deposition

    Science.gov (United States)

    1965-01-01

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

  5. Boron Carbides As Thermo-electric Materials

    Science.gov (United States)

    Wood, Charles

    1988-01-01

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

  6. Nuclear fuel management and boron carbide coating

    International Nuclear Information System (INIS)

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

  7. Development and Kinetics of TiB2 Layers on the Surface of Titanium Alloy by Superplastic Boronizing

    Science.gov (United States)

    Taazim, Nor Taibah; Jauhari, Iswadi; Miyashita, Yukio; Sabri, Mohd Faizul Mohd

    2016-05-01

    The aim of this work is to explore the possibility of combining boronizing and superplastic deformation on titanium alloy (Ti6Al4V) substrate. Superplastic boronizing (SPB) is carried out at three different temperatures of 1173 K, 1223 K, and 1273 K (900 °C, 950 °C, and 1000 °C), and it is held for four different boronizing times of 1, 2, 3, and 6 hours. TiB2 is the only boride compound identified after the boronizing process. Boronized layer thickness in the range of 44.9 ± 1.1 to 149 ± 1 μm is formed on the surface of Ti6Al4V and the surface hardness values increase with respect of the formation's degree of the hard boronized layer. Diffusion coefficient values attained for all temperatures are (1.44 ± 0.8) × 10-13, (4.1 ± 1.5) × 10-13, and (8.86 ± 4.1) × 10-13 m2 s-1, respectively and the values are higher as compared to other works referred. The activation energy obtained for this process is 226.17 ± 8.3 kJ mol-1. The results obtained suggest that the SPB process provides a more competent and efficient process for the formation of a boronized layer on the alloy.

  8. XPS analysis of boron doped heterofullerenes

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-06-01

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

  9. Stabilization of boron carbide via silicon doping.

    Science.gov (United States)

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

    2015-01-14

    Boron carbide is one of the lightest and hardest ceramics, but its applications are limited by its poor stability against a partial phase separation into separate boron and carbon. Phase separation is observed under high non-hydrostatic stress (both static and dynamic), resulting in amorphization. The phase separation is thought to occur in just one of the many naturally occurring polytypes in the material, and this raises the possibility of doping the boron carbide to eliminate this polytype. In this work, we have synthesized boron carbide doped with silicon. We have conducted a series of characterizations (transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and x-ray diffraction) on pure and silicon-doped boron carbide following static compression to 50 GPa non-hydrostatic pressure. We find that the level of amorphization under static non-hydrostatic pressure is drastically reduced by the silicon doping. PMID:25427850

  10. Stabilization of boron carbide via silicon doping

    Science.gov (United States)

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

    2015-01-01

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

  11. Boron enrichment in martian clay.

    Directory of Open Access Journals (Sweden)

    James D Stephenson

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

  12. Boron enrichment in martian clay.

    Science.gov (United States)

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

    2013-01-01

    We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration. PMID:23762242

  13. Toxicity research of boron-nitrogen modifiers of wooden surface

    Directory of Open Access Journals (Sweden)

    Klyachenkova Ol'ga Aleksandrovna

    2014-07-01

    Full Text Available Boron-nitrogen compounds (BNC have been successfully used to create bio- and fire-protective compositions for wood. Within the framework of this study, our aim was to assess the toxicity of the boron-nitrogen compounds by bioluminescent method with the use of environmental control device "Biotox-10M" and highly sensitive biosensor "Ecolum". We also defined toxicological parameters EC20 and EC50 and concluded, that all the wood preservation compounds are highly toxic, whereby, it is advisable to use them for external protection of wooden structures. As a result of BNC toxicity assessment, it is necessary to consider that any effective bio- and fireprotectives, will be highly toxic. Our researches stated, that BNC protective compositions are highly toxic and, therefore, it is possible to conclude their applicability for external wood processing.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-10-01

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

  15. Medical aspects of boron-slow neutron capture therapy

    International Nuclear Information System (INIS)

    Earlier radiations of patients with cerebral tumors disclosed the need: (1) to find a carrier of the boron compound which would leave the blood and concentrate in the tumor, (2) to use a more penetrating neutron beam, and (3) to develop a much faster method for assaying boron in blood and tissue. To some extent number1 has been accomplished in the form of Na2 B12 H11 SH, number2 has yet to be achieved, and number3 has been solved by the measurement of the 478-keV gamma ray when the 10B atom disintegrates following its capture of a slow neutron. The hitherto unreported data in this paper describe through the courtesy of Professor Hiroshi Hatanaka his studies on the pharmacokinetics and quality control of Na2 B12 H11SH based on 96 boron infusions in 86 patients. Simultaneous blood and tumor data are plotted here for 30 patients with glioblastomas (Grade III-IV gliomas), illustrating remarkable variability. Detailed autopsy findings on 18 patients with BNCT showed radiation injury in only 1. Clinical results in 12 of the most favorably situated glioblastomas reveal that 5 are still alive with a 5-year survival rate of 58% and the excellent Karnofsky performance rating of 87%. For the first time evidence is presented that slow-growing astrocytomas may benefit from BNCT. 10 references, 8 figures, 5 tables

  16. New Pathways and Metrics for Enhanced, Reversible Hydrogen Storage in Boron-Doped Carbon Nanospaces

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifer, Peter [University of Missouri; Wexler, Carlos [University of Missouri; Hawthorne, M. Frederick [University of Missouri; Lee, Mark W. [University of Missouri; Jalistegi, Satish S. [University of Missouri

    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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

    A highly sensitive and simple method for the spectrophotometric determination of boron was developed. Boron was found to react with hydrobenzoin in weak alkaline medium to form a complex anion extractable into benzene with crystal violet, and the measurement of the absorbance of crystal violet in the extract at 600 nm enabled the determination of boron indirectly. The recommended procedure is as follows: Take an aliquot of the boron solution (2.0 x 10-4 mol l-1) into a 10-ml test tube. Add 1 ml of carbonate buffer solution (pH 9.4) and 0.25 ml of crystal violet solution (1.0 x 10-2 mol l-1), and dilute the mixed solution to 4 ml with deionized water. Shake the solution with 4 ml of benzene solution containing hydrobenzoin (2.0 x 10-2 mol l-1) for 2 min. Measure the absorbance of the organic phase at 600 nm using a 10-mm glass cell against benzene. The calibration curve obeyed Beer's law on the concentration range from 2.5 x 10-6 mol l-1 to 2.5 x 10-5 mol l-1 of boron, and the apparent molar absorptivity was 3.0 x 104 l mol-1 cm-1 at 200C. It was found that many kinds of co-existing ions interfered with the determination. However, this method was applicable to the determination of boron in sea water when chloride ion and cations such as Ca(II) and Mg(II) were previously eliminated by treating the sample solution with Ag2O and cation exchanger resin. The proposed method is a very simple and rapid one, because this method does not require apparatus other than common laboratories and the evaporation to dryness of sample or removal of the excess of reagent. (author)

  19. Development of a boron-copper neutron absorber composite

    International Nuclear Information System (INIS)

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

  20. Kinetics of formation of a platelet-reinforced ceramic composite prepared by the directed reaction of zirconium with boron carbide

    International Nuclear Information System (INIS)

    In this paper the kinetics of formation of a new class of ceramic composite material, zirconium diboride platelet-reinforced zirconium carbides, are discussed. These materials are prepared by the directed reaction of molten zirconium with boron carbide to form a ceramic material composed of zirconium diboride platelets approximately uniformly distributed in a zirconium carbide matrix containing a controlled amount of residual zirconium metal. Results from interrupted growth studies, differential thermal analysis, adiabatic reaction temperature calculations, and kinetic measurements have been used to study the kinetics of the process. The reaction is very fast and proceeds parabolically with time with a rate constant between 1.6 x 10-2 and 3.9 x 10-2 cm2/s. The proposed mechanism suggests that when molten zirconium contacts boron carbide, the molten zirconium exothermically reacts with the boron carbide to form a boron-rick liquid. Further reaction is sustained by the continuous dissolution of the boron carbide as the boron-rich liquid is drawn into the boron carbide. The product is a zirconium diboride/zirconium carbide/zirconium composite which homogenizes quickly at the reaction temperature to yield a uniform product microstructure throughout the composite. Two alternative rate-limiting steps are discussed and the implications of each are explored

  1. Systematic study of the electronic structure and optical properties of icosahedral boron and boron compounds

    Science.gov (United States)

    Li, Dong

    1997-11-01

    A systematic study of the electronic structures, total energies and optical properties of B12-based boron and boron-rich compounds and boron oxide compounds has been conducted by the first-principles orthogonalized linear combination of atomic orbitals method. The materials involved are: α-r-B12, B12As2,/ B12P2,/ B11C(CBC)/ (or/ B4C),/ B13C2,/ B12O2,/ (B10Si2)Si2,/ (B10Si2)Si2-I, B2O3-I and B2O3-II. The band structures show that α-r-B12,/ B12As2,/ B12P2,/ B11C(CBC),/ B12O2,/ (B10Si2)Si2, and (B10Si2)Si2-I are semiconductors with band gaps ranging from 1.29 eV to 3.04 eV while B13C2 is a metal with an intrinsic hole at the top of the valence band below a semiconductor-like gap. The study also shows that B2O3-I and B2O3-II are wide gap insulators with calculated LDA gaps of 6.20 eV and 8.85 eV separately. The calculated density of states are resolved into atomic and orbital partial components and the valence-charge distributions are also studied. The natural bonding characteristics in these crystals are illuminated by evaluating the Mulliken effective charges on each atom and overlap populations between pairs of atoms. It is shown that inter-icosahedral bonding is much stronger than the intra-icosahedral bonding in the B12- based crystals. The chain elements in B12As2,/ B12P2,/ (B10Si2)Si2 and (B10Si2)Si2-I donate electrons to the icosahedra, while B11C(CBC),/ B13C2 and B12O2 gain a slight amount of charge in forming strong covalent bonds. For boron oxide compounds, B2O3-II is found to be more ionic than B2O3-I. It is also concluded that the sp2 planar bonding in B2O3-I is stronger than the sp3 tetrahedral bonding in B2O3-II. The bulk moduli of α-r-B12,/ B12As2,/ B12P2,/ B11C(CBC),/ B13C2 and B12O2 are estimated by means of total energy calculation as a function of crystal volume, and are to be considered as upper limits. We have also calculated the interband optical conductivities and the complex dielectric functions. Static dielectric constants for icosahedral

  2. 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.

    Science.gov (United States)

    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. PMID:27467416

  3. Colorimetric Sugar Sensing Using Boronic Acid-Substituted Azobenzenes

    OpenAIRE

    Yuya Egawa; Ryotaro Miki; Toshinobu Seki

    2014-01-01

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

  4. Synthesis and characterization of ammonium phosphate fertilizers with boron

    OpenAIRE

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

    2010-01-01

    The concentration of boron, an essential micronutrient for plants, presents a narrow range between deficiency and toxicity. In order to provide the boron requirement for plants, and to avoid toxicity problems, boron compounds are mixed with basic fertilizers. Sodium borate pentahydrate was used as a boron source. Ammonium orthophosphates fertilizers with boron were prepared by neutralizing phosphoric acid with ammonia and addition of variable amounts of sodium tetraborate pentahydrate to the ...

  5. Synthesis of calcium diborate CaO·B2O3·4H2O (Ca 114) containing definite boron isotope

    International Nuclear Information System (INIS)

    A new method for the synthesis of calcium diborate in aqueous solutions from calcium oxide, sodium hydroxide and boric acid containing a definite boron isotope (10B or 11B) has been elaborated. Since the mother liquid can be utilized for repeated synthesis, the yield of the diborate with respect to boron is higher than in other processes

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

    International Nuclear Information System (INIS)

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

  7. Radiological analysis of plutonium glass batches with natural/enriched boron

    International Nuclear Information System (INIS)

    The disposition of surplus plutonium inventories by the US Department of Energy (DOE) includes the immobilization of certain plutonium materials in a borosilicate glass matrix, also referred to as vitrification. This paper addresses source terms of plutonium masses immobilized in a borosilicate glass matrix where the glass components include both natural boron and enriched boron. The calculated source terms pertain to neutron and gamma source strength (particles per second), and source spectrum changes. The calculated source terms corresponding to natural boron and enriched boron are compared to determine the benefits (decrease in radiation source terms) for to the use of enriched boron. The analysis of plutonium glass source terms shows that a large component of the neutron source terms is due to (a, n) reactions. The Americium-241 and plutonium present in the glass emit alpha particles (a). These alpha particles interact with low-Z nuclides like B-11, B-10, and O-17 in the glass to produce neutrons. The low-Z nuclides are referred to as target particles. The reference glass contains 9.4 wt percent B2O3. Boron-11 was found to strongly support the (a, n) reactions in the glass matrix. B-11 has a natural abundance of over 80 percent. The (a, n) reaction rates for B-10 are lower than for B-11 and the analysis shows that the plutonium glass neutron source terms can be reduced by artificially enriching natural boron with B-10. The natural abundance of B-10 is 19.9 percent. Boron enriched to 96-wt percent B-10 or above can be obtained commercially. Since lower source terms imply lower dose rates to radiation workers handling the plutonium glass materials, it is important to know the achievable decrease in source terms as a result of boron enrichment. Plutonium materials are normally handled in glove boxes with shielded glass windows and the work entails both extremity and whole-body exposures. Lowering the source terms of the plutonium batches will make the handling of

  8. boron nitride coating of uranium dioxide and uranium dioxide-gadolinium oxide fuels by chemical precipitation method

    International Nuclear Information System (INIS)

    In this research pure urania and urania-gadolinia (5 and 10 %) fuels were coated with boron nitride (BN). This is achieved through chemical vapor deposition (CVD) using boron tricloride BCl3) and ammonia (NH3) at 600 C.Boron tricloride and ammonia are carried to tubular furnace using hydrogen as carrier gas. The coated samples were sintered at 1600 K. The properties of the coated samples were observed using BET surface area analysis, infrared spectra (IR), X-Ray Diffraction and Scanning Electron Microscope (SEM) techniques

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

    Science.gov (United States)

    Rosenberg, David

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

  10. Developments in boron magnetic resonance imaging (MRI)

    Energy Technology Data Exchange (ETDEWEB)

    Schweizer, M.

    1995-11-01

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

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

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

    2010-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  15. Isotope geochemistry of boron in mantle rocks, tektites and meteorites

    International Nuclear Information System (INIS)

    Recent ion microprobe studies of fresh oceanic basalt glasses and chondrules from primitive meteorites give an overview of the distribution of boron isotopes in the mantle and in extra-terrestrial rocks. After removal of secondary boron isotope variations due to interactions between mantle melts and the oceanic crust, the primitive mantle is found to have a constant δ11B value of -10 ± 2 per mill, similar to that of the bulk continental crust. In contrast, large isotopic variations between -50 and +40 per mill are present at the micron scale in meteoritic chondrules which are among the most primitive objects of the solar system. These isotopic variations imply that a significant part of the boron of the solar system was synthesized in the presolar cloud, likely by spallation reactions between lo-energy cosmic rays and nebular hydrogen. These heterogeneities were partly preserved in chondrules which formed early in the evolution of the solar system but are not observed for the silicate Earth implying an efficient mixing just before or during the accretion of the Earth. (authors). 74 refs., 5 figs., 2 tabs

  16. Application of HVJ envelope system to boron neutron capture therapy (BNCT)

    International Nuclear Information System (INIS)

    Boron Neutron Capture Therapy (BNCT) has been used clinically for the treatment of malignant tumors. Two drugs, p-boronophenylalanine (BPA) and sulfhydral borane (BSH), have been used as boron delivery agents. These drugs seem to be taken up preferentially in solid tumors, but it is uncertain whether therapeutic quantities of boron atoms are taken up by micro-invasive or distant tumor cells. High accumulation and high selective delivery of boron into tumor tissues are the most important requirements to achieve efficient BNCT for malignant tumor. The HVJ envelope (HVJ-E) vector system is a novel fusion-mediated gene delivery system based on inactivated hemagglutinating virus of Japan (HVJ; Sendai virus). Although we developed this vector system for gene transfer, it can also deliver proteins, synthetic oligonucleotides, and drugs. HVJ-liposome, which is liposome fused with HVJ-E, has higher boron trapping efficiency than HVJ-E alone. We report the boron delivery into cultured cells with HVJ-liposome systems. The cellular 10B concentration after 60 min incubation with HVJ-E containing BSH was 24.9 μg/g cell pellet for BHK-21 cells (baby hamster kidney cells) and 19.4 μg/g cell pellet for SCC VII cells (murine squamous cell carcinoma). These concentrations are higher than that of 60 min incubated cells with BSH containing (100μg 10B/ml) medium. These results indicate the HVJ-E fused with tumor cell membrane and rapidly delivered boron agents, and that the HVJ-E-mediated delivery system could be applicable to BNCT. Plans are underway to begin neutron radiation experiments in vivo and in vitro. (author)

  17. Removal of Vanadium from Molten Aluminum—Part III. Analysis of Industrial Boron Treatment Practice

    Science.gov (United States)

    Khaliq, Abdul; Akbar Rhamdhani, Muhammad; Brooks, Geoffrey A.; Grandfield, John

    2014-04-01

    Transition metal impurities (V, Ti, Zr, and Cr) reduce the electrical conductivity of smelter grade aluminum. These impurities are removed in the form of their borides by reacting with added Al-B master alloys i.e., boron treatment. Although, boron treatment is widely used for the production of high purity aluminum alloys in casthouse the fundamental understanding is lacking and published industrial data are limited. In the current study, industrial trials on the removal of impurities were conducted at one of the high purity aluminum alloys producers in Australasia. Kinetics analysis revealed that the rate of reaction is controlled by the mass transfer of impurities in the bulk melt. The measured mass transfer coefficient ( k m) of V and Ti were 1.1 × 10-4 and 2.6 × 10-4 m/s respectively, in the naturally stirred molten aluminum. The rate of V and Ti removal was faster compared to Zr and Cr during the boron treatment of smelter grade aluminum. Mass balance analysis revealed that 70 wt pct of V and Ti combined as borides in the first hour of the total 12 hours of boron treatment process. The calculated amount of un-reacted B was approximately 25.5 wt pct of initial amount added that remained in the final alloy. There was no evidence of boride rings formation, although partially dissolved AlB12 particles were observed under scanning electron microscope. Finally, implications for industrial practice are discussed for the improvement of current boron treatment process that include changing the source of boron, multiple stage addition of boron and better stirring of the molten aluminum.

  18. Respiratory irritation associated with inhalation of boron trifluoride and fluorosulfonic acid

    NARCIS (Netherlands)

    Rusch, G.M.; Bowden, A.M.; Muijser, H.; Arts, J.

    2008-01-01

    The objectives of this study were to examine the respiratory irritancy of boron trifluoride (BF3) and fluorosulfonic acid (FSA) following acute inhalation exposure. Testing was conducted using groups of 10 male and 10 female rats (BF3) or groups of 6 male rats (FSA). Rats were exposed for a single 4

  19. Nanocrystalline Boron-doped Diamond: Spectro /Photo/ Electrochemical Properties and Prospective Applications in Solar Cells

    Czech Academy of Sciences Publication Activity Database

    Kavan, Ladislav; Vlčková Živcová, Zuzana; Krýsová, Hana; Petrák, Václav; Janda, Pavel; Tarábková, Hana; Nesládek, Miloš

    Barcelona: Phantoms Foundation, 2014. s. 106-106. [Trends in Nanotechnology 2014. 27.10.2014-31.10.2014, Barcelona] R&D Projects: GA ČR GA13-31783S Institutional support: RVO:61388955 ; RVO:68378271 Keywords : nanocrystalline boron-doped diamond * electrochemistry * dye-sensitized solar cell Subject RIV: CG - Electrochemistry

  20. Preliminary results of a new boron coated neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    Gervino, G., E-mail: gervino@to.infn.it [Dipartimento di Fisica Università di Torino (Italy); INFN Torino (Italy); Balma, M.; Devona, D. [SELEX Galileo, San Maurizio Canavese, TO (Italy); Lavagno, A. [Dipartimento di Fisica Politecnico di Torino (Italy); INFN Torino (Italy); Palmisano, C. [Dipartimento di Fisica Università di Torino (Italy); Zamprotta, L. [Dipartimento di Fisica Università di Torino (Italy); INFN Torino (Italy); Scarfone, A. [ISC-CNR Torino (Italy); INFN Torino (Italy); Tintori, C. [C.A.E.N. S.p.A., Viareggio, LU (Italy)

    2013-08-01

    The proliferation of neutron detection applications based upon {sup 3}He counter has triggered a critical shortage of {sup 3}He gas. Nowadays there is an increasing demand for alternative neutron detectors that can cover large solid angles, have low sensitivity to gamma background and low cost. We present a low cost neutron detector based upon 3 cm diameter, 150 cm long cylindrical metal tube coated on the inside with a thin layer of {sup 10}B-enriched boron carbide ({sup 10}B{sub 4}C) fulfilled by 1 atm nitrogen.

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

    International Nuclear Information System (INIS)

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

  2. Thermal conductivity of ultra-thin chemical vapor deposited hexagonal boron nitride films

    Science.gov (United States)

    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.

  3. Influence of disorder on thermal transport properties of boron nitride nanostructures

    Science.gov (United States)

    Sevik, Cem; Kinaci, Alper; Haskins, Justin B.; Çaǧın, Tahir

    2012-08-01

    The impact of isotopes on thermal transport in boron nitride nanotubes (BNNTs) and boron nitride white graphene is systematically studied via molecular dynamic simulations. By varying the concentration of the 10B isotope in these materials, we find that thermal conductivity ranges from 340 to 500 W/m-1 K-1, closely agreeing with experimental observations for isotopically pure and natural (19.9% 10B) BNNTs. Further, we investigate the interplay between dimension and isotope disorder in several C-based materials. Our results show a general trend of decreasing influence of isotope disorder with dimension of these materials.

  4. Boron

    International Nuclear Information System (INIS)

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

  5. Preparation of a radioactive boron compound (B-I-131-lipiodol) for neutron capture therapy of hepatoma

    International Nuclear Information System (INIS)

    In our research, a radioactive boron compound, B-I-131-lipiodol, that can be selectively retained in hepatoma cells was prepared. Combining the effect of α particles produced by boron neutron capture reaction with the β particles released by radionuclides in the radioactive boron compounds will produce a synergistic killing effect on cancer cells. Human hepatoma HepG2 cell cultures were used to examine the stability and the intracellular distribution of the radioactive boron drug. Microscopes were used to examine the interaction and retention of B-I-131-lipiodol globules in the individual hepatoma cell. Moreover, ICP-AES and NaI scintillation counter were performed to determine boron concentrations and I-131 radioactivity, respectively. Results showed that B-I-131-lipiodol with a boron concentration and a specific radioactivity ranged from 500-2000 ppm and 0.05-10 mCi/mL respectively was stably retained in serum. The radiochemical purity of B-I-131-lipiodol was 98%. After supplement with a medium containing B-I-131-lipiodol, the HepG2 cells had intracellular B-I-131-lipiodol globules in the cytoplasm as seen by inverted light microscope, the I-131 and boron can be stably retained in HepG2 cells. (author)

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

    Science.gov (United States)

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

    2014-11-01

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

  7. Elastic properties, sp3 fraction, and Raman scattering in low and high pressure synthesized diamond-like boron rich carbides

    International Nuclear Information System (INIS)

    Dense BCx phases with high boron concentration are predicted to be metastable, superhard, and conductors or superconductors depending on boron concentration. However, up to this point, diamond-like boron rich carbides BCx (dl-BCx) phases have been thought obtainable only through high pressure and high temperature treatment, necessitating small specimen volume. Here, we use electron energy loss spectroscopy combined with transmission electron microscopy, Raman spectroscopy, surface Brillouin scattering, laser ultrasonics (LU) technique, and analysis of elastic properties to demonstrate that low pressure synthesis (chemical vapor deposition) of BCx phases may also lead to the creation of diamond-like boron rich carbides. The elastic properties of the dl-BCx phases depend on the carbon sp2 versus sp3 content, which decreases with increasing boron concentration, while the boron bonds determine the shape of the Raman spectra of the dl-BCx after high pressure-high temperature treatment. Using the estimation of the density value based on the sp3 fraction, the shear modulus μ of dl-BC4, containing 10% carbon atoms with sp3 bonds, and dl-B3C2, containing 38% carbon atoms with sp3 bonds, were found to be μ = 19.3 GPa and μ = 170 GPa, respectively. The presented experimental data also imply that boron atoms lead to a creation of sp3 bonds during the deposition processes.

  8. The measurement of thermal neutron flux depression for determining the concentration of boron in blood

    International Nuclear Information System (INIS)

    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 1x104 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 1.11x1011 Bq and a maximum count rate of less than 1x104 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. (author)

  9. Synthesis of Boron-Containing Primary Amines

    Directory of Open Access Journals (Sweden)

    Sheng-Hsuan Chung

    2013-10-01

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

  10. Boron toxicity in oil palm (Elaeis guineensis)

    Energy Technology Data Exchange (ETDEWEB)

    Rajaratnam, J.A.

    1973-01-01

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

  11. Boron adsorption on hematite and clinoptilolite

    International Nuclear Information System (INIS)

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

  12. Boron-Filled Hybrid Carbon Nanotubes.

    Science.gov (United States)

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

    2016-01-01

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

  13. Boron neutron capture therapy. What is next?

    International Nuclear Information System (INIS)

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

  14. Ni doping of semiconducting boron carbide

    International Nuclear Information System (INIS)

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

  15. High temperature thermoelectric properties of boron carbide

    International Nuclear Information System (INIS)

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

  16. Effect of boron addition on disorder-order transformation of FePt thin films

    International Nuclear Information System (INIS)

    The MgO20nm/(FePt0.85B0.15)xnm/MgO20nm (x=10 and 50) films were prepared on Si (100) substrates by RF magnetron sputtering. The boron content in thin films was found to be about 15at% by wavelength dispersive spectroscopy. At 50nm of film thickness, the coercivity of Fe0.5Pt0.5 and (FePt)0.85B0.15 films increased drastically above 400deg. C. Measured lattice constants and coercivity indicated that addition of boron to the FePt film at 50nm thickness is not effective in reducing the ordering temperature. However, in case of 10-nm-thick films, addition of boron decreased the ordering temperature to 400deg. C, which is 200deg. C lower than that of the film without boron. Decrease of the ordering temperature is attributed (closely related) to the high diffusivities of Fe and Pt associated with the defects by movement of the boron atoms to interstitial or substitutional lattice site

  17. Tribological properties of undoped and boron-doped nanocrystalline diamond films

    International Nuclear Information System (INIS)

    Undoped and boron-doped nanocrystalline (NCD) diamond films were deposited on mirror polished Ti-6Al-4V substrates in a Microwave Plasma Assisted Chemical Vapor Deposition system. Sliding wear tests were conducted in ambient air with a nanotribometer. A systematic study of the tribological properties for both undoped and boron-doped NCD films were carried out. It was found for diamond/diamond sliding, coefficient of friction decreases with increasing normal loads. It was also found that the wear rate of boron-doped NCD films is about 10 times higher than that of undoped films. A wear rate of ∼ 5.2 x 10-9 mm3/Nm was found for undoped NCD films. This value is comparable to the best known value of that of polished polycrystalline diamond films. Although no surface deformation, film delamination or micro-cracking were observed for undoped films, boron-doped NCD film undergoes a critical failure at a normal stress of 2.2 GPa, above which surface deformation is evident. Combined with high hardness and modulus, tunable conductivity and improved open air thermal stability, boron-doped nanocrystalline diamond film has tremendous potentials for applications such as Atomic Force Microscope probes, Micro-Electro-Mechanical System devices and biomedical sensors

  18. Mg-doping experiment and electrical transport measurement of boron nanobelts

    International Nuclear Information System (INIS)

    We measured electrical conductance of single crystalline boron nanobelts having α-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 10-3 (Ω cm)-1 at room temperature. The carrier mobility of pure boron nanobelt was measured to be on the order of 10-3 (cm2 Vs-1) at room temperature and has an activation energy of ∼0.19 eV. The Mg-doped boron nanobelts have the same α-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

  19. Synthesis and biological evaluation of boronated polyglycerol dendrimers as potential agent for neutron capture therapy

    International Nuclear Information System (INIS)

    In this work, the polyglycerol dendrimer (PGLD) generation 5 was used to obtain a boronated macromolecule for boron neutron capture therapy. The PGLD dendrimer was synthesized by the ring opening polymerization of deprotonated glycidol using polyglycerol as core functionality in a step-growth processes denominated divergent synthesis. The PGLD dendritic structure was confirmed by gel permeation chromatography, nuclear magnetic resonance (1H-NMR, 13C-NMR) and matrix assisted laser desorption/ionization techniques. The synthesized dendrimer presented low dispersion in molecular weights (Mw/Mn = 1.05) and a degree of branching of 0.82, which characterize the polymer dendritic structure. Quantitative neutron capture radiography was used to investigate the boron-10 enrichment of the polyglycerol dendrimer. The in vitro cytotoxicity to Chinese hamster ovary cells of 10B-PGLD dendrimer indicate lower cytotoxicity, suggesting that the macromolecule is a biocompatible material. (author)

  20. Critical boron-doping levels for generation of dislocations in synthetic diamond

    Energy Technology Data Exchange (ETDEWEB)

    Alegre, M. P., E-mail: maripaz.alegre@uca.es; Araújo, D.; Pinero, J. C.; Lloret, F.; Villar, M. P. [Departamento de Ciencias de los Materiales e Ingeniería Metalúrgica y Química, Universidad de Cádiz, 11510 Puerto Real, Cádiz (Spain); Fiori, A.; Achatz, P.; Chicot, G.; Bustarret, E. [Université Grenoble Alpes, Institut NEEL, 25 av. des Martyrs, 38042 Grenoble (France); Jomard, F. [GEMaC, CNRS and Université de Versailles St Quentin, 45 Avenue des États-Unis, 78035 Versailles (France)

    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.

  1. Lithium-Beryllium-Boron : Origin and Evolution

    OpenAIRE

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

    1999-01-01

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

  2. Innovative boron nitride-doped propellants

    OpenAIRE

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

    2016-01-01

    The U.S. military has a need for more powerful propellants with balanced/stoichiometric amounts of fuel and oxidants. However, balanced and more powerful propellants lead to accelerated gun barrel erosion and markedly shortened useful barrel life. Boron nitride (BN) is an interesting potential additive for propellants that could reduce gun wear effects in advanced propellants (US patent pending 2015-026P). Hexagonal boron nitride is a good lubricant that can provide wear resistance and lower ...

  3. A neutron diffraction study of amorphous boron

    Science.gov (United States)

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

    1991-07-01

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

  4. THE EFFECTS OF BORON COMPOUNDS AND DIFFERENT MELAMINE CONTENTS IN MUF RESINS ON SOME PROPERTIES OF MDF PANELS

    OpenAIRE

    Derya Ustaomer; Mustafa Usta

    2011-01-01

    The objective of this study was to determine the effects of some boron compounds, which have fire retardant properties, as well as melamine-urea-formaldehyde (MUF) resins having different melamine contents (10%, 15%, and 20%) on some physical and mechanical properties of medium density fiberboard (MDF) panels. It was found that the water absorption (WA) and thickness swelling (TS) of MDF panels increased depending on types and concentrations of boron compounds. However, the WA and TS values o...

  5. Discharge cleaning on TFTR after boronization

    International Nuclear Information System (INIS)

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

  6. Amorphous boron nitride at high pressure

    Science.gov (United States)

    Durandurdu, Murat

    2016-06-01

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

  7. Innovative boron nitride-doped propellants

    Directory of Open Access Journals (Sweden)

    Thelma Manning

    2016-04-01

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

  8. Innovative boron nitride-doped propellants

    Institute of Scientific and Technical Information of China (English)

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

    2016-01-01

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

  9. Intracellular boron accumulation in CHO-K1 cells using amino acid transport control

    International Nuclear Information System (INIS)

    BPA used in BNCT has a similar structure to some essential amino acids and is transported into tumor cells by amino acid transport systems. Previous study groups have tried various techniques of loading BPA to increase intracellular boron concentration. CHO-K1 cells demonstrate system L (LAT1) activity and are suitable for specifying the transport system of a neutral amino acid. In this study, we examined the intracellular accumulation of boron in CHO-K1 cells by amino acid transport control, which involves co-loading with L-type amino acid esters. Intracellular boron accumulation in CHO-K1 cells showed the greatest increased upon co-loading 1.0 mM BPA, with 1.0 mM L-Tyr-O-Et and incubating for 60 min. This increase is caused by activation of a system L amino acid exchanger between BPA and L-Tyr. The amino acid esters are metabolized to amino acids by intracellular hydrolytic enzymes that increase the concentrations of intracellular amino acids and stimulate exchange transportation. We expect that this amino acid transport control will be useful for enhancing intracellular boron accumulation. - Highlights: • We examined optimal L-p-boronophenylalanine (BPA) loading in CHO-K1 cells. • Optimal BPA loading parameters were 1.0 mM and incubation for 60 min. • Intracellular boron accumulation increased upon co-loading BPA with L-Tyr-O-Et. • Optimal L-Tyr-O-Et loading parameters were 1.0 mM and incubation for 60 min. • Co-loading BPA with L-Tyr-O-Et can increase intracellular boron accumulation

  10. Metal-insulator transition and superconductivity in heavily boron-doped diamond and related materials

    Energy Technology Data Exchange (ETDEWEB)

    Achatz, Philipp

    2009-05-15

    During this PhD project, the metal-insulator transition and superconductivity of highly boron-doped single crystal diamond and related materials have been investigated. The critical boron concentration n{sub c} for the metal-insulator transition was found to be the same as for the normal-superconductor transition. All metallic samples have been found to be superconducting and we were able to link the occurence of superconductivity to the proximity to the metal-insulator transition. For this purpose, a scaling law approach based on low temperature transport was proposed. Furthermore, we tried to study the nature of the superconductivity in highly boron doped single crystal diamond. Raman spectroscopy measurements on the isotopically substituted series suggest that the feature occuring at low wavenumbers ({approx} 500 cm{sup -1}) is the A1g vibrational mode associated with boron dimers. Usual Hall effect measurements yielded a puzzling situation in metallic boron-doped diamond samples, leading to carrier concentrations up to a factor 10 higher than the boron concentration determined by secondary ion mass spectroscopy (SIMS). The low temperature transport follows the one expected for a granular metal or insulator, depending on the interplay of intergranular and intragranular (tunneling) conductance. The metal-insulator transition takes place at a critical conductance g{sub c}. The granularity also influences significantly the superconducting properties by introducing the superconducting gap {delta} in the grain and Josephson coupling J between superconducting grains. A peak in magnetoresistance is observed which can be explained by superconducting fluctuations and the granularity of the system. Additionally we studied the low temperature transport of boron-doped Si samples grown by gas immersion laser doping, some of which yielded a superconducting transition at very low temperatures. Furthermore, preliminary results on the LO-phonon-plasmon coupling are shown for the

  11. Metal-insulator transition and superconductivity in heavily boron-doped diamond and related materials

    International Nuclear Information System (INIS)

    During this PhD project, the metal-insulator transition and superconductivity of highly boron-doped single crystal diamond and related materials have been investigated. The critical boron concentration nc for the metal-insulator transition was found to be the same as for the normal-superconductor transition. All metallic samples have been found to be superconducting and we were able to link the occurence of superconductivity to the proximity to the metal-insulator transition. For this purpose, a scaling law approach based on low temperature transport was proposed. Furthermore, we tried to study the nature of the superconductivity in highly boron doped single crystal diamond. Raman spectroscopy measurements on the isotopically substituted series suggest that the feature occuring at low wavenumbers (∼ 500 cm-1) is the A1g vibrational mode associated with boron dimers. Usual Hall effect measurements yielded a puzzling situation in metallic boron-doped diamond samples, leading to carrier concentrations up to a factor 10 higher than the boron concentration determined by secondary ion mass spectroscopy (SIMS). The low temperature transport follows the one expected for a granular metal or insulator, depending on the interplay of intergranular and intragranular (tunneling) conductance. The metal-insulator transition takes place at a critical conductance gc. The granularity also influences significantly the superconducting properties by introducing the superconducting gap Δ in the grain and Josephson coupling J between superconducting grains. A peak in magnetoresistance is observed which can be explained by superconducting fluctuations and the granularity of the system. Additionally we studied the low temperature transport of boron-doped Si samples grown by gas immersion laser doping, some of which yielded a superconducting transition at very low temperatures. Furthermore, preliminary results on the LO-phonon-plasmon coupling are shown for the first time in aluminum

  12. Synthesis and properties of low-carbon boron carbides

    International Nuclear Information System (INIS)

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

  13. Development of magnetic resonance technology for noninvasive boron quantification

    International Nuclear Information System (INIS)

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

  14. Modeling of the hot flow behavior of advanced ultra-high strength steels (A-UHSS) microalloyed with boron

    International Nuclear Information System (INIS)

    In this research work, modeling of the hot flow behavior was carried out in a low carbon advanced ultra-high strength steels (A-UHSS) microalloyed with different amounts of boron (14, 33, 82, 126 and 214 ppm). For this purpose, experimental stress–strain data of uniaxial hot-compression tests over a wide range of temperatures (1223, 1273, 1323 and 1373 K (950, 1000, 1050 and 1100 °C)) and strain rates (10−3, 10−2 and 10−1 s−1) were used. The stress–strain relationships as a function of temperature and strain rate were successfully described on the basis of the approach proposed by Estrin, Mecking, and Bergström, together with the classical Avrami equation and the conventional hyperbolic sine function. The analysis of the modeling parameters of the hot flow curves shows that boron additions to A-UHSS play a major role in softening mechanisms rather than on hardening. The peak stress (σp) and steady-state stress (σss) values show a decreasing trend with increasing boron content, which indicates that boron additions promote a solid solution softening effect additional to that produced by DRX. The time for 50% recrystallization (t50%) tends to increase with boron additions, revealing that boron additions cause a delay of the DRX kinetics during hot deformation. Similarly, the presence of boron in the steel decreases the apparent activation energy for recrystallization (Qt), indicating that boron additions accelerate the onset of DRX. The constitutive equations developed in this way provided an excellent description of the experimental hot flow curves

  15. Modeling of the hot flow behavior of advanced ultra-high strength steels (A-UHSS) microalloyed with boron

    Energy Technology Data Exchange (ETDEWEB)

    Mejía, I., E-mail: imejia@umich.mx [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio “U”, Ciudad Universitaria, 58066 Morelia, Michoacán (Mexico); Altamirano, G.; Bedolla-Jacuinde, A. [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio “U”, Ciudad Universitaria, 58066 Morelia, Michoacán (Mexico); Cabrera, J.M. [Departament de Ciència dels Materials i Enginyeria Metallúrgica, ETSEIB – Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Fundació CTM Centre Tecnològic, Av. de las Bases de Manresa, 1, 08240 Manresa (Spain)

    2014-07-29

    In this research work, modeling of the hot flow behavior was carried out in a low carbon advanced ultra-high strength steels (A-UHSS) microalloyed with different amounts of boron (14, 33, 82, 126 and 214 ppm). For this purpose, experimental stress–strain data of uniaxial hot-compression tests over a wide range of temperatures (1223, 1273, 1323 and 1373 K (950, 1000, 1050 and 1100 °C)) and strain rates (10{sup −3}, 10{sup −2} and 10{sup −1} s{sup −1}) were used. The stress–strain relationships as a function of temperature and strain rate were successfully described on the basis of the approach proposed by Estrin, Mecking, and Bergström, together with the classical Avrami equation and the conventional hyperbolic sine function. The analysis of the modeling parameters of the hot flow curves shows that boron additions to A-UHSS play a major role in softening mechanisms rather than on hardening. The peak stress (σ{sub p}) and steady-state stress (σ{sub ss}) values show a decreasing trend with increasing boron content, which indicates that boron additions promote a solid solution softening effect additional to that produced by DRX. The time for 50% recrystallization (t{sub 50%}) tends to increase with boron additions, revealing that boron additions cause a delay of the DRX kinetics during hot deformation. Similarly, the presence of boron in the steel decreases the apparent activation energy for recrystallization (Q{sub t}), indicating that boron additions accelerate the onset of DRX. The constitutive equations developed in this way provided an excellent description of the experimental hot flow curves.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-10-22

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    1993-01-01

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

  19. Recombination methods for boron neutron capture therapy dosimetry

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2016-07-01

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    1997-10-01

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

  4. Effect of fast neutron irradiation on the properties of boron carbide pellet

    International Nuclear Information System (INIS)

    Boron carbide pellets were irradiated in the experimental fast reactor 'JOYO' to 10B burnup of up to 170x1026 cap/m3, fluences of 2x1026/m2 (E>0.1 MeV), and maximum temperatures of about 1,200degC. Post irradiation examinations were made of microstructural changes, helium release, swelling, and thermal conductivity. Boron carbide pellets irradiated to high burnups developed extensive cracking. Helium release from the pellets was initially low, but enhanced helium release was observed at high burnups and high temperatures. The swelling linearly increased with burnup, and when boron carbide was irradiated at high temperatures, the swelling rate began to decrease corresponding to the beginning of enhanced helium release. The correlation between swelling and the helium release was studied and the swelling was interpreted in terms of accumulation of helium in the boron carbide pellet. The thermal conductivity of the boron carbide pellets decreased rapidly by neutron irradiation accompanied with loss of temperature dependence. (author)

  5. Dispersion of boron carbide in a tungsten carbide/cobalt matrix

    International Nuclear Information System (INIS)

    Particles of boron carbide (105-125 microns) were coated with a layer (10-12 microns) of titanium carbide in a fluidized bed. These coated particles have been successfully incorporated in a tungsten carbide--cobalt matrix by hot pressing at 1 tonf/in2, (15.44 MN/m2) at 13500C. Attempts to produce a similar material by a cold pressing and sintering technique were unsuccessful because of penetration of the titanium carbide layer by liquid cobalt. Hot-pressed material containing boron carbide had a static strength in bend of approximately 175,000 lbf/in2, (1206MN/m2) which compares favorably with the strength of conventionally produced tungsten carbide/cobalt. The impact strength of the material containing boron carbide was however considerably lower than tungsten carbide/cobalt. In rock drilling tests on Darley Dale sandstone at low speeds and low loads, the material containing boron carbide drilled almost ten times as far without seizure as tungsten carbide/cobalt. In higher speed and higher load rotary drilling tests conducted by the National Coal Board, the material containing boron carbide chipped badly compared with normal NCB hardgrade material

  6. Boron content in type 316 L stainless steel by neutron induced autoradiography

    International Nuclear Information System (INIS)

    Boron is effective to the improvement of various properties of alloys, but it is difficult to characterize its behavior during the alloy processing. Neutron induced autoradiography (or called as F.T.E: Fission Track Etching) technique was attempted to quantitatively analyze boron content in type 316 L austenitic stainless steel. Reference samples with nine different boron contents were prepared and analyzed by conventional analysis method as well as by autoradiography technique using 'HANARO', a 30 MW research reactor in K.A.E.R.I. (Korea Atomic Energy Research Institute). Cd ratio of the neutron flux was about 200 and thermal neutron flux was around 2x1013/cm2/sec. A Kodak CN-85TM detector with an alloy sample was irradiated with two different thermal neutron fluences of 1013 and 1014/cm2. Track densities on the autoradiographs were measured using image analyzer. Within the range of 10 to 50 ppm of boron, track densities from autoradiography showed the linear relationship with results from conventional analyses. When complementarily applied with other analysis technique like E.B.S.D. (Electron Backscattered Diffraction) or E.D.S. (Energy Dispersive Spectroscopy) neutron induced autoradiography technique was found very useful in distinguishing and identifying phases with the different distribution coefficient of boron. (author)

  7. A Novel Boron-Loaded Liquid Scintillator for Neutron Detection

    OpenAIRE

    Sur, B.; Li, L.; E. Pruszkowski; Dai, X.; G. Bentoumi

    2012-01-01

    A boron-loaded liquid scintillator (LS) has been optimized for neutron detection application in a high gamma field environment. It is composed of the solvent linear alkylbenzene (LAB), a boroncontaining material, o-carborane (C2B10H12); a fluor, 2,5-diphenyloxazole (PPO); and a wavelength shifter, 1,4-bis[2-methylstyryl] benzene (bis-MSB). Preparation of the liquid scintillator and optimization of its chemical composition are described. The boronloaded LS has been tested with a neutron beam a...

  8. Design study of facilities for boron neutron capture therapy

    International Nuclear Information System (INIS)

    One of the authors organized a research group on boron neutron capture therapy (BNCT) during 1975 to 1979. The results of the research were summarized in two Japanese reports. It was concluded in 1976 that a nuclear reactor facility was required for developing BNCT and related research. Conceptual design of the facility was performed according to consultation among the group members, and is reported here. The optimum neutron energy for BNCT is shown to be between 10eV and 500eV

  9. 2,4-Difluoro anisole. A promising complexing agent for boron isotopes separation by chemical exchange reaction and distillation

    International Nuclear Information System (INIS)

    Although methods of boron isotopes separation were intensively pursued about 60 years, the chemical exchange distillation is the only method that has been applied in industrial scale production of 10B. The present anisole BF3 system suffers from the drawbacks like high melting point, relatively low separation coefficient and instability under reaction conditions, which demand a continuous search for more effective and efficient donors for boron isotope separation. A series of fluoro-substituted anisole derivatives were screened in this paper, among which 2,4-difluoro anisole exhibited good properties compared with anisole. Studies on the boron trifluoride and 2,4-difluoro anisole adduct, its thermodynamic and physical properties related to large-scale isotopic separation is reported. The results showed that 2,4-difluoro anisole is better than anisole in separation coefficient, freezing point and stability under pyrolysis conditions, which suggest a further detailed investigations on boron trifluoride and 2,4-difluoro anisole adduct. (author)

  10. Geometry of trigonal boron coordination sphere in boronic acids derivatives - a bond-valence vector model approach.

    Science.gov (United States)

    Czerwińska, Karolina; Madura, Izabela D; Zachara, Janusz

    2016-04-01

    The systematic analysis of the geometry of three-coordinate boron in boronic acid derivatives with a common [CBO2] skeleton is presented. The study is based on the bond-valence vector (BVV) model [Zachara (2007). Inorg. Chem. 46, 9760-9767], a simple tool for the identification and quantitative estimation of both steric and electronic factors causing deformations of the coordination sphere. The empirical bond-valence (BV) parameters in the exponential equation [Brown & Altermatt (1985). Acta Cryst. B41, 244-247] rij and b, for B-O and B-C bonds were determined using data deposited in the Cambridge Structural Database. The values obtained amount to rBO = 1.364 Å, bBO = 0.37 Å, rBC = 1.569 Å, bBC = 0.28 Å, and they were further used in the calculation of BVV lengths. The values of the resultant BVV were less than 0.10 v.u. for 95% of the set comprising 897 [CBO2] fragments. Analysis of the distribution of BVV components allowed for the description of subtle in- and out-of plane deviations from the `ideal' (sp(2)) geometry of boron coordination sphere. The distortions specific for distinct groups of compounds such as boronic acids, cyclic and acyclic esters, benzoxaboroles and hemiesters were revealed. In cyclic esters the direction of strains was found to be controlled by the ring size effect. It was shown that the syn or anti location of substituents on O atoms is decisive for the deformations direction for both acids and acyclic esters. The greatest strains were observed in the case of benzoxaboroles which showed the highest deviation from the zero value of the resultant BVV. The out-of-plane distortions, described by the vz component of the resultant BVV, were ascertained to be useful in the identification of weak secondary interactions on the fourth coordination site of the boron centre. PMID:27048726

  11. 1H MRS of a boron neutron capture therapy 10B-carrier, L-p-boronophenylalanine-fructose complex, BPA-F: phantom studies at 1.5 and 3.0 T

    International Nuclear Information System (INIS)

    The quantification of a BNCT 10B-carrier, L-p-boronophenylalanine-fructose complex (BPA-F), was evaluated using 1H magnetic resonance spectroscopy (1H MRS) with phantoms at 1.5 and 3.0 T. For proper quantification, relaxation times T1 and T2 are needed. While T1 is relatively easy to determine, the determination of T2 of a coupled spin system of aromatic protons of BPA is not straightforward with standard MRS sequences. In addition, an uncoupled concentration reference for aromatic protons of BPA must be used with caution. In order to determine T2, the response of an aromatic proton spin system to the MRS sequence PRESS with various echo times was calculated and the product of the response curve with exponential decay was fitted to the measured intensities. Furthermore, the response curve can be used to correct the intensities, when an uncoupled resonance is used as a concentration reference. BPA was quantified using both phantom replacement and internal water referencing methods with accuracies of ±5% and ±15%. Our phantom results suggest that in vivo studies on BPA concentration determination will be feasible

  12. Sodium mercaptoundecahydro-closo-dodecaborate (BSH), a boron carrier that merits more attention

    Energy Technology Data Exchange (ETDEWEB)

    Wittig, Andrea, E-mail: wittig@med.uni-marburg.de [Department of Radiotherapy and Radiation Oncology, University Hospital Giessen and Marburg, Philipps-University Marburg, Baldingerstrasse, 35043 Marburg (Germany); Stecher-Rasmussen, Finn [NCT Physics, Nassaulaan 12, 1815 GK Alkmaar (Netherlands); Hilger, Ralf A. [Department of Medical Oncology, University Duisburg-Essen, University Hospital Essen, Hufelandstrasse 55, 45122 Essen (Germany); Rassow, Juergen [NCTeam, Department of Radiation Oncology, University Hospital Essen, University Duisburg-Essen, Hufelandstrasse 55, 45122 Essen (Germany); Mauri, Pierluigi [Consiglio Nazionale delle Ricerche, Istituto di Tecnologie, Biomediche (CNR-ITB), Via Fratelli Cervi, 93, I-20090 Segrate (Italy); Sauerwein, Wolfgang [NCTeam, Department of Radiation Oncology, University Hospital Essen, University Duisburg-Essen, Hufelandstrasse 55, 45122 Essen (Germany)

    2011-12-15

    Boron neutron capture therapy relies on the preferential delivery of a {sup 10}B-compound to tumor cells. The BSH-biodistribution was investigated in nu/nu mice and human patients. The boron concentration was measured with prompt gamma ray spectroscopy. BSH accumulates to a very low extent not only in brain, but also in fat tissue, bone and muscle, which makes BSH an interesting drug not only for brain lesions but also for tumors located at the extremities. The differential uptake in different organs indicates a complex mechanism.

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

    International Nuclear Information System (INIS)

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

  14. Improvements in Boron Plate Coating Technology for Higher Efficiency Neutron Detection and Coincidence Counting Error Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Menlove, Howard Olsen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Henzlova, Daniela [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-25

    This informal report presents the measurement data and information to document the performance of the advanced Precision Data Technology, Inc. (PDT) sealed cell boron-10 plate neutron detector that makes use of the advanced coating materials and procedures. In 2015, PDT changed the boron coating materials and application procedures to significantly increase the efficiency of their basic corrugated plate detector performance. A prototype sealed cell unit was supplied to LANL for testing and comparison with prior detector cells. Also, LANL had reference detector slabs from the original neutron collar (UNCL) and the new Antech UNCL with the removable 3He tubes. The comparison data is presented in this report.

  15. Direct Colorimetric Detection of Hydrogen Peroxide Using 4-Nitrophenyl Boronic Acid or Its Pinacol Ester

    OpenAIRE

    Gregory Su; Yibin Wei; Maolin Guo

    2011-01-01

    A colorimetric method for the direct determination of hydrogen peroxide in aqueous solution is described. H2O2 stoichiometrically converts 4-nitrophenyl boronic acid or 4-nitrophenyl boronic acid pinacol ester into 4-nitrophenol, which can be quantified by measuring the absorption at 400 nm in neutral or basic media. The reactions proceed fast under basic conditions and complete in 2 minutes to at pH 11 and 80?C. The linear range for the colorimetric method extends beyond 1.0 to 40 µM H2O2, a...

  16. Histopathological changes of testes and eyes by neutron irradiation with boron compounds in mice

    OpenAIRE

    Kim, Yeon-Joo; Yoon, Won-Ki; Ryu, Si-Yun; Chun, Ki-Jung; Son, Hwa-Young; Cho, Sung-Whan

    2006-01-01

    This study was performed to investigate the biological effects of boron neutron capture therapy (BNCT) on the testes and eyes in mice using HANARO Nuclear Reactor, Korea Atomic Energy Research Institute. BNCT relies on the high capacity of 10B in capturing thermal neutrons. Sodium borocaptate (BSH, 75 ppm, iv) and boronophenylalanine (BPA, 750 ppm, ip) have been used as the boron delivery agents. Mice were irradiated with neutron (flux: 1.036739E +09, Fluence 9.600200E+12) by lying flat pose ...

  17. Sodium mercaptoundecahydro-closo-dodecaborate (BSH), a boron carrier that merits more attention

    International Nuclear Information System (INIS)

    Boron neutron capture therapy relies on the preferential delivery of a 10B-compound to tumor cells. The BSH-biodistribution was investigated in nu/nu mice and human patients. The boron concentration was measured with prompt gamma ray spectroscopy. BSH accumulates to a very low extent not only in brain, but also in fat tissue, bone and muscle, which makes BSH an interesting drug not only for brain lesions but also for tumors located at the extremities. The differential uptake in different organs indicates a complex mechanism.

  18. Synthesis and oxidation behavior of boron-substituted carbon powders by hot filament chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Boron-substituted carbon powder, BxC1-x with x up to 0.17, has been successfully synthesized by hot filament chemical vapor deposition. The boron concentration in prepared BxC1-x samples can be controlled by varying the relative proportions of methane and diborane. X-ray diffraction, transmission electron microscopy, and electron energy loss spectrum confirm the successful synthesis of an amorphous BC5 compound, which consists of 10―20 nm particles with disk-like morphology. Thermogravimetry measurement shows that BC5 compound starts to oxidize ap-proximately at 620℃ and has a higher oxidation resistance than carbon.

  19. Biomedical irradiation system for boron neutron capture therapy at the Kyoto University reactor

    International Nuclear Information System (INIS)

    Physics studies related to radiation source, spectroscopy, beam quality, dosimetry, and biomedical applications using the Kyoto University Reactor Heavy Water Facility are described. Also, described are a Nickel Mirror Neutron Guide Tube and a Super Mirror Neutron Guide Tube that are used both for the measurement of boron concentration in phantom and living tissue and for precise measurements of neutron flux in phantom in the presence of both light and heavy water. Discussed are: (1) spectrum measurements using the time of flight technique, (2) the elimination of gamma rays and fast neutrons from a thermal neutron irradiation field, (3) neutron collimation without producing secondary gamma rays, (4) precise neutron flux measurements, dose estimation, and the measurement of boron concentration in tumor and its periphery using guide tubes, (5) the dose estimation of boron-10 for the first melanoma patient, and (6) special-purpose biological irradiation equipment. Other related subjects are also described

  20. Phase transitions to 120 GPa for shock-compressed pyrolytic and hot-pressed boron nitride

    International Nuclear Information System (INIS)

    Shock-compression characteristics of two types of hexagonal graphitelike boron nitride have been investigated. Highly oriented very pure pyrolytic boron nitride exhibits shock-velocity versus particle-velocity discontinuities that appear to be manifestations of the initiation of a sluggish phase transition. This transition begins at 20 GPa and is driven to completion (melting) at 75 GPa. Discontinuities in the plot for impure hot-pressed boron nitride indicate initiation at 10 GPa and completion at 20 GPa. The (U/sub s/, U/sub p/) plots follow essentially the same paths for 4.0 < U/sub p/ < 5.2 km/sec. No evidence for a transition to a metalliclike state was seen. Temperature calculations indicate that the material is liquid above approx.80 GPa

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

    Science.gov (United States)

    Werheit, H; Kuhlmann, U

    2011-11-01

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

  2. A multiple quantum NMR (MQNMR) study of hydrogen microstructure in boron doped a-Si:H

    International Nuclear Information System (INIS)

    In this paper, an IR and multiple quantum NMR (MQNMR) study of hydrogen microstructure in three boron doped a-Si:H is discussed. The total Si-bonded H content of all films was 6.5 ± 1.0 at. % as determined by the 640 cm-1 IR wagging mode, but their boron content, which was determined by secondary ion mass spectrometry, ranged from 0.02 to 0.3 at %. The number of correlated hydrogen, as measured at a preparation time of 600 μs, was found to be more weakly dependent on the boron content than previously observed in phosphorous-doped glow-discharge films. Upon annealing at 220 degrees C the MQNMR spectrum show a moderate increase in the number of correlated hydrogen in all three samples

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

    International Nuclear Information System (INIS)

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

  4. 15th International Conference on Boron Chemistry (IMEBORON XV)

    Czech Academy of Sciences Publication Activity Database

    Grüner, Bohumír; Štíbr, Bohumil

    2015-01-01

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

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

    International Nuclear Information System (INIS)

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

  6. The determination of boron in ferrous and non-ferrous alloys by neutron transmission

    International Nuclear Information System (INIS)

    A method has been developed for the determination of 0.1 to over 20% of boron in aluminium- and complex ferro-alloys, based on the neutron-absorbing properties of the 10B nucleus. It has also been applied to stainless steel. The determination is fully automatic and results are conveniently processed by computer. (author)

  7. Effect of boron dimers on the superconducting critical temperature inboron-doped diamond

    Czech Academy of Sciences Publication Activity Database

    Šopík, Břetislav; Lipavský, P.

    2012-01-01

    Roč. 21, č. 1 (2012), 77-82. ISSN 0925-9635 R&D Projects: GA ČR GAP204/10/0212 Institutional research plan: CEZ:AV0Z10100521 Keywords : boron * superconductivity * disorder * correlations * dimers Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.709, year: 2012

  8. Spectral Sensitization of Nanocrystalline Boron-Doped Diamond Electrode for Application in Photoelectrochemical Solar Cells

    Czech Academy of Sciences Publication Activity Database

    Kavan, Ladislav; Vlčková Živcová, Zuzana; Krýsová, Hana; Petrák, Václav; Bartoň, Jan; Cígler, Petr; Nesládek, M.

    San Francisco: Material Research Society, 2015. [2015 MRS Spring Meeting & Exhibit. Program: Symposium R—Photoactive Nanoparticles and Nanostructures. 06.04.2015-10.04.2015, San Francisco] R&D Projects: GA ČR GA13-31783S Institutional support: RVO:68378271 ; RVO:61388955 ; RVO:61388963 Keywords : nanocrystalline boron doped diamond * electrochemistry * photoelectrochemistry Subject RIV: CG - Electrochemistry

  9. 氮化硼和氧化镁复配对导热绝缘PAIOT复合材料性能的影响%Synergistic Effect of Boron Nitride and Magnesia on the Properties of Thermally Conductive and Electrically Insulative PA10T Composites

    Institute of Scientific and Technical Information of China (English)

    蒋智强; 易庆锋; 麦杰鸿; 姜苏俊

    2012-01-01

    Thermally conductive and electrically insulative poly(decamethylene terephthalamide)(PA10T) composites were prepared using an instant-agglomerated boron nitride (BN) powder and a microspheric magnesia (MgO) powder as fillers. A few amount of chopped glass fiber was loaded to improve the strength. Keeping the total filler loading of chopped glass fiber and fillers at 10 vet % and 60 wt % respectively, the effect of the weight ratio of BN to MgO on the thermally conductive and mechanical properties as well as flow abilities of the composites was studied. It was observed that the two thermally conductive fillers had an enormously synergistic effect on the thermal conductivity when the weight ratio of BN to MgO was 20 to 40. In this case, the through-plane thermal conductivity was as high as 3. 5 W/m .I.A higher weight ratio of BN to MgO usually led to poorer mechanical and flowing properties.%采用氮化硼微球粉末和球状氧化镁作为复配导热填料,少量短切玻璃纤维作为增强填料,制备了导热绝缘耐高温聚对苯二甲酰癸二胺(PA10T)复合材料。考察了在玻璃纤维含量和导热填料总含量分别为10%(质量分数,下同)和60%不变的前提下,氮化硼和氧化镁的复配比例对复合材料的导热、力学和流动性能的影响。结果表明,当氮化硼和氧化镁的质量比为20:40时,2种填料之间产生了良好的复配协同效果,所制备的复合材料的法向热导率最高,可达3.5w/m·K;在复配填料含量相同的前提下,氮化硼/氧化镁的质量比越高,材料的力学性能越差,流动性也越差。

  10. Boron determination in biological samples - Intercomparison of three analytical methods to assist development of a treatment protocol for neoplastic diseases of the liver with Boron Neutron Capture Therapy

    OpenAIRE

    Schütz, Christian L.

    2012-01-01

    Die Bor-Neuroneneinfang-Therapie (engl.: Boron Neutron Capture Therapy, BNCT) ist eine indirekte Strahlentherapie, welche durch die gezielte Freisetzung von dicht ionisierender Strahlung Tumorzellen zerstört. Die freigesetzten Ionen sind Spaltfragmente einer Kernreaktion, bei welcher das Isotop 10B ein niederenergetisches (thermisches) Neutron einfängt. Das 10B wird durch ein spezielles Borpräparat in den Tumorzellen angereichert, welches selbst nicht radioaktiv ist. rnAn der Johannes Gutenbe...

  11. Aqueous compatible boron nitride nanosheets for high-performance hydrogels

    Science.gov (United States)

    Hu, Xiaozhen; Liu, Jiahui; He, Qiuju; Meng, Yuan; Cao, Liu; Sun, Ya-Ping; Chen, Jijie; Lu, Fushen

    2016-02-01

    Hexagonal boron nitride nanosheets (BNNSs) possess ultimate thermal and chemical stabilities and mechanical strengths. However, the unmodified BNNSs are hydrophobic and insoluble in water, which hinders their use in many technological areas requiring aqueous compatibility. In this work, h-BN was treated with molten citric acid to produce aqueous dispersible boron nitride sheets (ca-BNNSs). The resultant ca-BNNSs were used to fabricate ca-BNNS/polyacrylamide (i.e., BNNS2.5/PAAm) nanocomposite hydrogels, targeting high water retentivity and flexibility. The BNNS2.5/PAAm hydrogel (initially swollen in water) largely remained swollen (water content ~94 wt%) even after one-year storage under ambient conditions. Importantly, the swollen BNNS2.5/PAAm hydrogel (water content ~95 wt%) was highly flexible. Its elongation and compressive strength exceeded 10 000% and 8 MPa at 97% strain, respectively. Moreover, the aforementioned hydrogel recovered upon the removal of compression force, without obvious damage. The substantially improved water retentivity and flexibility revealed that BNNSs can serve as a promising new platform in the development of high-performance hydrogels.Hexagonal boron nitride nanosheets (BNNSs) possess ultimate thermal and chemical stabilities and mechanical strengths. However, the unmodified BNNSs are hydrophobic and insoluble in water, which hinders their use in many technological areas requiring aqueous compatibility. In this work, h-BN was treated with molten citric acid to produce aqueous dispersible boron nitride sheets (ca-BNNSs). The resultant ca-BNNSs were used to fabricate ca-BNNS/polyacrylamide (i.e., BNNS2.5/PAAm) nanocomposite hydrogels, targeting high water retentivity and flexibility. The BNNS2.5/PAAm hydrogel (initially swollen in water) largely remained swollen (water content ~94 wt%) even after one-year storage under ambient conditions. Importantly, the swollen BNNS2.5/PAAm hydrogel (water content ~95 wt%) was highly flexible. Its

  12. Boron neutrino flux and resonant conversion of solar neutrinos

    International Nuclear Information System (INIS)

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

  13. Measurements and applications of high energy boron implants in silicon

    Science.gov (United States)

    La Ferla, A.; Rimini, E.; Carnera, A.; Gasparotto, A.; Ciavola, G.; Ferla, G.

    1991-04-01

    Boron ions were implanted into high resistivity Si wafers at energies in the 15-50 MeV range and doses in the 10 11-10 16 cm -2 range. The distribution of the implanted ions was analyzed by spreading resistance profilometry and for the high fluences by secondary ion mass spectrometry. Some samples were implanted with the beam normal to the wafer surface to study the channeling effect in a pure electronic stopping power regime of slowing down. The experimental measurements of the projected ranges and of the stragglings are compared with calculations based on the usual LSS and Bethe-Bloch formulas for the stopping power. This classic approach justifies quantitatively the distribution for the samples implanted in a random direction. The I- V characteristic of a diode performed by multiple energy boron implants of 15, 22 and 50 MeV is presented. The obtained breakdown voltage, 5 × 10 3 V, represents a possible application of the high energy implants.

  14. Separation of boron isotopes by exchange distillation process

    International Nuclear Information System (INIS)

    Boron has two stable isotopes namely 10B and 11B with natural abundance of 19.9 % and 80.1 % respectively. Both the isotopes find extensive use in the nuclear industry and can be used for the production of two radioisotopes: 11C and 13N as well as tracers to study reaction mechanisms in biological systems. 10B has a large neutron capture cross-section and, therefore, used to assist control of nuclear reactors, a shield against radiation and in neutron detection. 10B is also used in boron neutron capture therapy (BNCT) of brain cancer patients. 11B is useful as a neutron reflector and largely immune to radiation damage so can be very useful in radiation hardened semiconductor designs to be used in spacecrafts. 11B is also an attractive candidate as a fuel for aneutronic fusion. The full potential of 11B is yet to be realized in the last two applications and its demand likely to pick up in future

  15. Boron isotope fractionation during brucite deposition from artificial seawater

    OpenAIRE

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

    2011-01-01

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

  16. Characterization of boron carbide with an electron microprobe

    Science.gov (United States)

    Matteudi, G.; Ruste, J.

    1983-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1981-11-03

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-06-01

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    N. F. Nevar

    2016-02-01

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

  3. Colorimetric Sugar Sensing Using Boronic Acid-Substituted Azobenzenes

    Directory of Open Access Journals (Sweden)

    Yuya Egawa

    2014-02-01

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

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

    International Nuclear Information System (INIS)

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

  5. Anomalous electronic transport in boron carbides

    Science.gov (United States)

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

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2015-05-01

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

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

    International Nuclear Information System (INIS)

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-31

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

  11. Plasma deposition of boron films with high growth rate and efficiency using carborane

    International Nuclear Information System (INIS)

    The injection of carborane (C2B10H12) on the PISCES-B linear plasma device has been used to produce boron containing films on various target species. Film growth rates achieved are extremely high (up to 30 nm/s) compared to those typically found for glow discharges (∼0.01 nm/s). For low-Z target materials (C and Al) the film production is highly efficient, with the boron film growth rate comparable to the incident ion flux and the injection rate of boron atoms. The boron to carbon ratio is 3.0-3.6 for these films. Similarly high growth rates (∼10 nm/s) are obtained with high-Z target (W), but with lower deposition efficiency and higher B/C film ratio. The high film growth rate/efficiency are apparently linked to the high degree of carborane ionization and dissociation caused by the ∼40 eV PISCES-B plasma, compared with T<1 eV plasmas of glow discharges. This technique opens the possibility of continuously producing protective B films in thermonuclear devices where net erosion rates approach 10 nm/s

  12. Boron Nitride Nanotubes for Spintronics

    Directory of Open Access Journals (Sweden)

    Kamal B. Dhungana

    2014-09-01

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

  13. Stable isotope ratio mass spectrometry of nanogram quantities of boron and sulfur

    Science.gov (United States)

    Wieser, Michael Eugene

    1998-09-01

    Instrumentation and analytical techniques were developed to measure isotope abundances from nanograms of sulfur and boron. Sulfur isotope compositions were determined employing continuous flow isotope ratio mass spectroscopy (CF-IRMS) procedures and AsS+ thermal ionization mass spectrometry techniques (AsS+-TIMS). Boron isotope abundances were determined by BO2/sp--TIMS. CF-IRMS measurements realized δ34S values from 10 μg sulfur with precisions of ±0.3/perthous. To extend sulfur isotope measurements to much smaller samples, a TIMS procedure was developed to measure 75As32S+ and 75As34S+ at masses 108 and 109 from 200 ng S on a Finnigan MAT 262 with an ion counter. This is possibly the smallest amount of sulfur which has been successfully analyzed isotopically. The internal precision of 32S/34S ratios measured by AsS+-TIMS was better than ±0.15 percent. δ34S-values calculated relative to the measured 32S/34S value of an IAEA AG2S standard (S-1) agreed with those determined by CF-IRMS to within ±3/perthous. The increasing sensitivity of S-isotope analyses permits hiterto impossible investigations e.g. sulfur in tree rings and ice cores. Boron isotope abundances were measured as BO2/sp- from 50 ng B using an older thermal ionization mass spectrometer which had been extensively upgraded including the addition of computer control electronics, sensitive ion current amplification and fiber optic data bus. The internal precisions of the measured 11B/10B ratios were ±0.15 percent and the precisions of δ11B values calculated relative to the accepted international standard (SRM-951) were ±3/perthous. Two applications of boron isotope abundance variations were initiated (1) ground waters of Northern Alberta and (2) coffee beans in different regions of the world. In the first it was demonstrated that boron isotopes could be used to trace boron released during steam injection of oil sands into the surrounding environment. Data from the second study suggest that boron

  14. Investigations to increase the efficiency of fluorine and boron removal from groundwater using radiation-induced graft polymerization adsorbent

    International Nuclear Information System (INIS)

    The Japan Atomic Energy Agency is performing a research project in the Mizunami Underground Research Laboratory (MIU) to build a firm scientific and technological basis for the studies of the deep underground environment in crystalline rock. In the project, it is necessary to reduce the fluorine and boron concentrations in groundwater pumped from the MIU shafts to levels below the environmental standards. This is done at the MIU water treatment facility using coagulation and ion exchange treatment for fluorine and boron, respectively. In addition, in 2006, research started on the efficient treatment of groundwater for removal of fluorine and boron using a radiation-induced graft polymerization adsorbent. The adsorbent removed boron at a flow rate (space velocity (SV)=120 h-1) higher than that of a general ion exchange resin (SV=10 h-1) and the adsorbent could be used repeatedly. It was also apparent that the pH of groundwater had an influence on adsorption performance. With respect to fluorine removal, more than 90% of fluorine was removed. However, the adsorbent for fluorine showed a lower adsorption capacity than that for boron. The reason for this difference is considered to be related to the initial concentration difference between fluorine and boron in the groundwater. Therefore, it is necessary to define the initial concentrations of dissolved materials, which can be used as better indicators of the performance of the adsorbent. (author)

  15. Fabrication and characterization of silicon based thermal neutron detector with hot wire chemical vapor deposited boron carbide converter

    International Nuclear Information System (INIS)

    In order to utilize the well established silicon detector technology for neutron detection application, a silicon based thermal neutron detector was fabricated by integrating a thin boron carbide layer as a neutron converter with a silicon PIN detector. Hot wire chemical vapor deposition (HWCVD), which is a low cost, low temperature process for deposition of thin films with precise thickness was explored as a technique for direct deposition of a boron carbide layer over the metalized front surface of the detector chip. The presence of B-C bonding and 10B isotope in the boron carbide film were confirmed by Fourier transform infrared spectroscopy and secondary ion mass spectrometry respectively. The deposition of HWCVD boron carbide layer being a low temperature process was observed not to cause degradation of the PIN detector. The response of the detector with 0.2 µm and 0.5 µm thick boron carbide layer was examined in a nuclear reactor. The pulse height spectrum shows evidence of thermal neutron response with signature of (n, α) reaction. The results presented in this article indicate that HWCVD boron carbide deposition technique would be suitable for low cost industrial fabrication of PIN based single element or 1D/2D position sensitive thermal neutron detectors

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

    International Nuclear Information System (INIS)

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

  17. Fabrication and characterization of silicon based thermal neutron detector with hot wire chemical vapor deposited boron carbide converter

    Science.gov (United States)

    Chaudhari, Pradip; Singh, Arvind; Topkar, Anita; Dusane, Rajiv

    2015-04-01

    In order to utilize the well established silicon detector technology for neutron detection application, a silicon based thermal neutron detector was fabricated by integrating a thin boron carbide layer as a neutron converter with a silicon PIN detector. Hot wire chemical vapor deposition (HWCVD), which is a low cost, low temperature process for deposition of thin films with precise thickness was explored as a technique for direct deposition of a boron carbide layer over the metalized front surface of the detector chip. The presence of B-C bonding and 10B isotope in the boron carbide film were confirmed by Fourier transform infrared spectroscopy and secondary ion mass spectrometry respectively. The deposition of HWCVD boron carbide layer being a low temperature process was observed not to cause degradation of the PIN detector. The response of the detector with 0.2 μm and 0.5 μm thick boron carbide layer was examined in a nuclear reactor. The pulse height spectrum shows evidence of thermal neutron response with signature of (n, α) reaction. The results presented in this article indicate that HWCVD boron carbide deposition technique would be suitable for low cost industrial fabrication of PIN based single element or 1D/2D position sensitive thermal neutron detectors.

  18. Fabrication and characterization of silicon based thermal neutron detector with hot wire chemical vapor deposited boron carbide converter

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhari, Pradip, E-mail: pradipcha@gmail.com [Semiconductor Thin Films and Plasma Processing Laboratory, Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai – 400076 (India); Singh, Arvind, E-mail: arvindsingh1884@gmail.com [Electronics Division, Bhabha Atomic Research Centre, Trombay, Mumbai – 400085 (India); Topkar, Anita, E-mail: anita.topkar@gmail.com [Electronics Division, Bhabha Atomic Research Centre, Trombay, Mumbai – 400085 (India); Dusane, Rajiv, E-mail: rodusane@iitb.ac.in [Semiconductor Thin Films and Plasma Processing Laboratory, Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai – 400076 (India)

    2015-04-11

    In order to utilize the well established silicon detector technology for neutron detection application, a silicon based thermal neutron detector was fabricated by integrating a thin boron carbide layer as a neutron converter with a silicon PIN detector. Hot wire chemical vapor deposition (HWCVD), which is a low cost, low temperature process for deposition of thin films with precise thickness was explored as a technique for direct deposition of a boron carbide layer over the metalized front surface of the detector chip. The presence of B-C bonding and {sup 10}B isotope in the boron carbide film were confirmed by Fourier transform infrared spectroscopy and secondary ion mass spectrometry respectively. The deposition of HWCVD boron carbide layer being a low temperature process was observed not to cause degradation of the PIN detector. The response of the detector with 0.2 µm and 0.5 µm thick boron carbide layer was examined in a nuclear reactor. The pulse height spectrum shows evidence of thermal neutron response with signature of (n, α) reaction. The results presented in this article indicate that HWCVD boron carbide deposition technique would be suitable for low cost industrial fabrication of PIN based single element or 1D/2D position sensitive thermal neutron detectors.

  19. A DMS kinetic study of the boron oxides vapor in the combustion front of SHS system Mo + B

    International Nuclear Information System (INIS)

    The distribution of the boron oxides vapor in the combustion wave of the SHS system Mo + B has been studied by the dynamic mass spectrometry technique (DMS) to test the thermodynamically based hypothesis for the key role of gas-phase transport in solid-state combustion. The molecular beam sampling of the gases over the burning tablet was performed by a stationary probe cone from the moving combustion wave. Ion currents of boron oxides were recorded at 10--20 ms intervals that afforded spatial resolution of 0.1--0.2 mm. It has been found that the distribution of the boron oxides vapor pressure along the combustion wave corresponds to the known zones of preheating, reaction, and postcombustion. The rapid increase of B2O2 pressure takes place in the preheating zone as a result of the reaction B(s) + B2O3(g) = B2O2(g). Boron oxides are not observed over the reaction zone because of their complete decay in the reaction with Mo(s) to form molybdenum boride(s). The appearance The appearance of boron oxide vapors over the postcombustion zone is due to the evaporation of B2O3(l). The effective kinetic parameters are estimated from the data obtained. The results show that solid-state combustion of the Mo + B system proceeds predominantly through formation of gas-phase boron oxides

  20. Reactive sputter deposition of boron nitride

    International Nuclear Information System (INIS)

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

  1. Thermal conductivity behavior of boron carbides

    Science.gov (United States)

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

    1983-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-12-31

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

  5. Novel Boron-10-based detectors for Neutron Scattering Science

    OpenAIRE

    Piscitelli, Francesco; project, for the ILL/ESS/LiU collaboration for the development of the B10 detector technology in the framework of the CRISP

    2015-01-01

    Nowadays neutron scattering science is increasing its instrumental power. Most of the neutron sources in the world are pushing the development of their technologies to be more performing. The neutron scattering development is also pushed by the European Spallation Source (ESS) in Sweden, a neutron facility which has just started construction. Concerning small area detectors (1m^2), the 3He technology, which is today cutting edge, is reaching fundamental limits in its development. Counting rat...

  6. Boron-10 layers, Neutron Reflectometry and Thermal Neutron Gaseous Detectors

    OpenAIRE

    Piscitelli, Francesco

    2014-01-01

    Nowadays neutron facilities are going toward higher fluxes, e.g. the European Spallation Source (ESS) in Lund (Sweden), and this translates into a higher demand in the instrument performances. Because of its favorable properties,He-3 has been the main actor in thermal neutron detection for years. Starting in about 2001 the He-3 stockpile has been declining. The world is now experiencing the shortage of He-3. This makes the construction of large area detectors (several squared meters) not real...

  7. Novel Boron-10-based detectors for Neutron Scattering Science

    CERN Document Server

    Piscitelli, Francesco

    2015-01-01

    Nowadays neutron scattering science is increasing its instrumental power. Most of the neutron sources in the world are pushing the development of their technologies to be more performing. The neutron scattering development is also pushed by the European Spallation Source (ESS) in Sweden, a neutron facility which has just started construction. Concerning small area detectors (1m^2), the 3He technology, which is today cutting edge, is reaching fundamental limits in its development. Counting rate capability, spatial resolution and cost-e?ectiveness, are only a few examples of the features that must be improved to ful?fill the new requirements. On the other hand, 3He technology could still satisfy the detector requirements for large area applications (50m^2), however, because of the present 3He shortage that the world is experiencing, this is not practical anymore. The recent detector advances (the Multi-Grid and the Multi-Blade prototypes) developed in the framework of the collaboration between the Institut Laue...

  8. Criticality safety evaluation of spent fuel storage rack under accident condition using soluble boron credit

    International Nuclear Information System (INIS)

    A boraflex attached on a consolidated storage spent fuel rack as neutron absorber has a characteristic that silica and boron carbide(B4C) present in the boraflex are dissolved into pent fuel pool water due to the long term irradiation of boraflex by spent fuels. in this report it is analyzed how in a case of complete dissolution of boron from the boraflex into the pool water, the adapted cresit of the dissolved boron affects on the criticality of storage spent fules to compensate an excessive reactivity due to postulated accidents. For criticality analyses PHOENIX-P and SCALE4.4 were used and benchmark calculations were carried out to verify the bias and uncertainties of the codes. The result of criticality analyses for postulated accident conditions shows that most of postulated accident such as spent fuel drop did not cause reactivity to increase significantly. However, the most severe accident to increase reactivity was a postulated abnormal loading of spent fuel under checkerboard loading pattern and the maximum required soluble boron concentration to compensate the increased reactivity in this case was 698.45ppm. The soluble boron concentration to make up the uncertainty from the burnup calculation and measurement of the spent duels was 116.65ppm so that the total required soluble boron concentration for compensation of the increased reactivity due to the most severe accident could be taken 815.10ppm by arithmetic addition of 698.45 and 116.65 ppm. It can be concluded that 2,300ppm minimum soluble requirement in technology specification of spent fuel storage pool operation of Ulchin NPP No. 2 is large enough to maintain sub-critical of the spent fuel storage pool under all of postulated accidents conditions

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-02-15

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

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

    Institute of Scientific and Technical Information of China (English)

    ZHAO; Zhiqi; (

    2003-01-01

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

  11. Boron carbide-based ceramics via polymer route synthesis

    International Nuclear Information System (INIS)

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

  12. Determination of carbon and sulphur in boron carbide

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2016-07-01

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

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

    Science.gov (United States)

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

    2007-01-01

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

  15. Ground-water pollution determined by boron isotope systematics

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  17. Removal properties of dissolved boron by glucomannan gel.

    Science.gov (United States)

    Oishi, Kyoko; Maehata, Yugo

    2013-04-01

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

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

    Science.gov (United States)

    Roosta, Sara; Hashemianzadeh, Seyed Majid; Ketabi, Sepideh

    2016-10-01

    Encapsulation of cisplatin anticancer drug into the single walled (10, 0) carbon nanotube and (10, 0) boron-nitride nanotube was investigated by quantum mechanical calculations and Monte Carlo Simulation in aqueous solution. Solvation free energies and complexation free energies of the cisplatin@ carbon nanotube and cisplatin@ boron-nitride nanotube complexes was determined as well as radial distribution functions of entitled compounds. Solvation free energies of cisplatin@ carbon nanotube and cisplatin@ boron-nitride nanotube were -4.128kcalmol(-1) and -2457.124kcalmol(-1) respectively. The results showed that cisplatin@ boron-nitride nanotube was more soluble species in water. In addition electrostatic contribution of the interaction of boron- nitride nanotube complex and solvent was -281.937kcalmol(-1) which really more than Van der Waals and so the electrostatic interactions play a distinctive role in the solvation free energies of boron- nitride nanotube compounds. On the other hand electrostatic part of the interaction of carbon nanotube complex and solvent were almost the same as Van der Waals contribution. Complexation free energies were also computed to study the stability of related structures and the free energies were negative (-374.082 and -245.766kcalmol(-1)) which confirmed encapsulation of drug into abovementioned nanotubes. However, boron-nitride nanotubes were more appropriate for encapsulation due to their larger solubility in aqueous solution. PMID:27287103

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

    Institute of Scientific and Technical Information of China (English)

    ZHUDUANWEI; PIMEIMEI; 等

    1997-01-01

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

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

    OpenAIRE

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

    2014-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    David W. Nigg

    2012-05-01

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

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

    International Nuclear Information System (INIS)

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

  4. Histopathological changes of testes and eyes by neutron irradiation with boron compounds in mice.

    Science.gov (United States)

    Kim, Yeon-Joo; Yoon, Won-Ki; Ryu, Si-Yun; Chun, Ki-Jung; Son, Hwa-Young; Cho, Sung-Whan

    2006-03-01

    This study was performed to investigate the biological effects of boron neutron capture therapy (BNCT) on the testes and eyes in mice using HANARO Nuclear Reactor, Korea Atomic Energy Research Institute. BNCT relies on the high capacity of 10B in capturing thermal neutrons. Sodium borocaptate (BSH, 75 ppm, iv) and boronophenylalanine (BPA, 750 ppm, ip) have been used as the boron delivery agents. Mice were irradiated with neutron (flux: 1.036739E +09, Fluence 9.600200E+12) by lying flat pose for 30 (10 Gy) or 100 min (33 Gy) with or without boron carrier treatment. In 45 days of irradiation, histopathological changes of the testes and eyes were examined. Thirty-three Gy neutron irradiation for 100 min induced testicular atrophy in which some of seminiferous tubules showed complete depletion of spermatogenic germ cells. Lens epithelial cells and lens fiber were swollen and showed granular changes in an exposure time dependent manner. However, boron carrier treatment had no significant effect on the lesions. These results suggest that the examination of histopathological changes of lens and testis can be used as "biological dosimeters" for gauging radiation responses and the HANARO Nuclear Reactor has sufficient capacities for the BNCT. PMID:16434844

  5. Nanodefects in ultrahard crystalline cubic boron nitride

    International Nuclear Information System (INIS)

    Cubic boron nitride (cBN), the second hardest known material after diamond, exhibits high thermal conductivity and an excellent ability to be n or p doped, which makes it a strong candidate for the next generation of high-temperature micro optical and micro electronic devices. According to recent studies, cBN exhibits a better resistance to radiation damage than diamond, which suggests potential applications in extreme radiation environments. Crystalline cBN powders of up to 0.5 mm linear size is obtained in a similar way as diamond, by catalytic conversion of hexagonal BN (hBN) to cBN at even higher pressures (> 5GPa) and temperatures (∼ 1900 K). Considering the essential role played by the nanodefects (point defects and impurities) in determining its physical properties, it is surprising how limited is the amount of published data concerning the properties of nanodefects in this material, especially by Electron Paramagnetic Resonance (EPR) spectroscopy, the most powerful method for identification and characterization of nanodefects in both insulators and semiconductors. This seems to be due mainly to the absence of natural cBN gems and the extreme difficulties in producing even mm3 sized synthetic crystals. We shall present our recent EPR studies on cBN crystalline powders, performed in a broad temperature range from room temperature (RT) down to 1.2 K on several sorts of large size cBN powder grits of yellow and amber color for industrial applications. Previous multifrequency (9.3 GHz and 95 GHz) EPR studies of brown to black cBN crystallites prepared with excess of boron, resulted in the discovery of two new types of paramagnetic point defects with different spectral properties, called the D1 and D2 centers. Our X(9.3 GHz)-band EPR investigations resulted in the observation in amber cBN crystalline powders of a spectrum with a strong temperature dependence of the lineshape. It was found that for high and low temperatures, respectively, the numerical

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

    Science.gov (United States)

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

    2008-05-01

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

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

    International Nuclear Information System (INIS)

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

  8. PWR core response to boron dilution transient

    International Nuclear Information System (INIS)

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

  9. Pechmann Reaction Promoted by Boron Trifluoride Dihydrate

    Directory of Open Access Journals (Sweden)

    J. Mezger

    2005-08-01

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

  10. New insight into pecan boron nutrition

    Science.gov (United States)

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

  11. Channeling of boron ions into silicon

    International Nuclear Information System (INIS)

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

  12. Influence of pollution of boron chlorinity ratio

    Digital Repository Service at National Institute of Oceanography (India)

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

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

  13. Boron carbide morphology changing under purification

    Science.gov (United States)

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

    2015-10-01

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

  14. Boron carbide synthesis at plasma spray process

    Czech Academy of Sciences Publication Activity Database

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

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

  15. Joining of boron carbide using nickel interlayer

    International Nuclear Information System (INIS)

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

  16. Boron nitride nanosheets reinforced glass matrix composites

    Czech Academy of Sciences Publication Activity Database

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

    2015-01-01

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

  17. The manufacturing method of boron carbide

    International Nuclear Information System (INIS)

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

  18. On-line reconstruction of low boron concentrations by in vivo γ-ray spectroscopy for BNCT

    International Nuclear Information System (INIS)

    Boron neutron capture therapy (BNCT) is a radiation therapy in which the neutron capture reaction of 10B is used for the selective destruction of tumours. At the High Flux Reactor (HFR) in Petten, a therapy facility with an epithermal neutron beam has been built. In the first instance, patients with brain tumours will be treated. The doses delivered to the tumour and to the healthy tissue depend on the thermal neutron fluence and on the boron concentrations in these regions. An accurate determination of the patient dose during therapy requires knowledge of these time-dependent concentrations. For this reason, a γ-ray telescope system, together with a reconstruction formalism, have been developed. By using a γ-ray detector in a telescope configuration, boron neutron capture γ-rays of 478 keV emitted by a small specific region can be detected. The reconstruction formalism can calculate absolute boron concentrations using the measured boron γ-ray detection rates. Besides the boron γ-rays, a large component of 2.2 MeV γ-rays emitted at thermal neutron capture in hydrogen is measured. Since the hydrogen distribution is almost homogeneous within the head, this component can serve as a measure of the total number of thermal neutrons in the observed volume. By using the hydrogen γ-ray detection rate for normalization of the boron concentration, the reconstruction tool eliminates the greater part of the influence of the inhomogeneity of the thermal neutron distribution. MCNP calculations are used as a tool for the optimization of the detector configuration. Experiments on a head phantom with 5 ppm 10B in healthy tissue showed that boron detection with a standard deviation of 3% requires a minimum measuring time of 2 min live time. From two position-dependent measurements, boron concentrations in two compartments (healthy tissue and tumour) can be determined. The reconstruction of the boron concentration in healthy tissue can be done with a standard deviation of 6

  19. BCM6: New Generation of Boron Meter

    International Nuclear Information System (INIS)

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

  20. Boron carbide nanowires: Synthesis and characterization

    Science.gov (United States)

    Guan, Zhe

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

  1. Facile preparation and multifunctional applications of boron nitride quantum dots

    Science.gov (United States)

    Lei, Zhouyue; Xu, Shengjie; Wan, Jiaxun; Wu, Peiyi

    2015-11-01

    Boron nitride quantum dots are obtained by a facile sonication-solvothermal technique. They are proven to be promising fluorescent bioimaging probes for bioimaging with remarkably low cytotoxicity and easily integrated into high-performance proton exchange membranes. This work will probably trigger research interest in BN and its new applications in a variety of fields.Boron nitride quantum dots are obtained by a facile sonication-solvothermal technique. They are proven to be promising fluorescent bioimaging probes for bioimaging with remarkably low cytotoxicity and easily integrated into high-performance proton exchange membranes. This work will probably trigger research interest in BN and its new applications in a variety of fields. Electronic supplementary information (ESI) available: AFM images of BN nanosheets, TEM, HRTEM and AFM images of BN QDs prepared in DMSO, digital photographs of DMF, DMSO, DMF with the addition of BN raw materials and DMSO with the addition of BN raw materials, UV-vis and FTIR spectra of the BN QDs, cell viability of the BN QDs, a summary of cell viabilities of different fluorescent QDs, digital photographs and CLSM images of the as-prepared PEMs, TGA and DSC curves of the PEMs, and AFM images of the PEMs. See DOI: 10.1039/c5nr05960g

  2. Non inflammatory boronate based glucose-responsive insulin delivery systems.

    Directory of Open Access Journals (Sweden)

    Indrani Dasgupta

    Full Text Available Boronic acids, known to bind diols, were screened to identify non-inflammatory cross-linkers for the preparation of glucose sensitive and insulin releasing agglomerates of liposomes (Agglomerated Vesicle Technology-AVT. This was done in order to select a suitable replacement for the previously used cross-linker, ConcanavalinA (ConA, a lectin known to have both toxic and inflammatory effects in vivo. Lead-compounds were selected from screens that involved testing for inflammatory potential, cytotoxicity and glucose-binding. These were then conjugated to insulin-encapsulating nanoparticles and agglomerated via sugar-boronate ester linkages to form AVTs. In vitro, the particles demonstrated triggered release of insulin upon exposure to physiologically relevant concentrations of glucose (10 mmoles/L-40 mmoles/L. The agglomerates were also shown to be responsive to multiple spikes in glucose levels over several hours, releasing insulin at a rate defined by the concentration of the glucose trigger.

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

    Science.gov (United States)

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

    2009-10-01

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

  4. Synthesis of hexagonal boron nitride graphene-like few layers

    Science.gov (United States)

    Yuan, S.; Toury, B.; Journet, C.; Brioude, A.

    2014-06-01

    Self-standing highly crystallized hexagonal boron nitride (h-BN) mono-, bi- and few-layers have been obtained for the first time via the Polymer Derived Ceramics (PDCs) route by adding lithium nitride (Li3N) micropowders to liquid-state polyborazylene (PBN). Incorporation of Li3N as a crystallization promoter allows the onset of crystallization of h-BN at a lower temperature (1200 °C) than under classical conditions (1800 °C). The hexagonal structure was confirmed by both electron and X-ray diffraction.Self-standing highly crystallized hexagonal boron nitride (h-BN) mono-, bi- and few-layers have been obtained for the first time via the Polymer Derived Ceramics (PDCs) route by adding lithium nitride (Li3N) micropowders to liquid-state polyborazylene (PBN). Incorporation of Li3N as a crystallization promoter allows the onset of crystallization of h-BN at a lower temperature (1200 °C) than under classical conditions (1800 °C). The hexagonal structure was confirmed by both electron and X-ray diffraction. Electronic supplementary information (ESI) available: See DOI: 10.1039/c4nr01017e

  5. Temperature dependence of damage in boron-implanted silicon

    International Nuclear Information System (INIS)

    The authors have performed a systematic investigation of boron implantation at 30 keV into n-type silicon in the 77-300 K temperature range and mostly at 9 x 1015 cm-2 fluence. The analyses have been performed with ion channeling and cross sectional transmission electron microscopy both in as-implanted samples and in samples annealed in vacuum furnace at 500 degree C and 850 degree C for 30 min. They confirm the impossibility of amorphization at room temperature and the presence of residual damage mainly located at the boron projected range. On the contrary, a continuous amorphous layer can be obtained for implants at 77 K and 193 K; the thickness of the implanted layer is increased by lowering the temperature, at the same time the amorphous-crystalline interface becomes sharper. Sheet resistance measurements performed after isochronal annealing shows an apparent reverse annealing of the dopant only in the sample implanted at 273 K. The striking differences between light and heavy ions observed at room temperature implantation disappears at 77 K and full recovery with no residual damage of the amorphous layer is observed. 10 refs., 5 figs

  6. Boron carbide neutron screen for GRR-1 neutron spectrum tailoring

    International Nuclear Information System (INIS)

    The presence of fast neutron spectra in new reactor concepts (such as Gas Cooled Fast Reactor, new generation Sodium Cooled Fast Reactor, Lead Fast Reactor, Accelerator Driven System and nuclear Fusion Reactors) is expected to induce a strong impact on the contained materials, including structural materials (e.g. steels), nuclear fuels, neutron reflecting materials (e.g. beryllium) and tritium breeding materials (for fusion reactors). Therefore, effective operation of these reactors will require extensive testing of their components, which must be performed under neutronic conditions representative of those expected to prevail inside the reactor cores when in operation. Depending on the material, the requirements of a test irradiation can vary. In this work preliminary studies were performed to observe the behavior of the neutron spectrum within a boron carbide neutron screen inserted in a hypothetical reflector test hole of the Greek Research Reactor. Four different screen configurations were simulated with Monte Carlo code TRIPOLI-4. The obtained data showed that the insertion of boron carbide caused not only elimination of the thermal (E < 1 eV) component of the neutron energy spectrum but also absorption of a considerable proportion of the intermediate energy neutrons (1x10-6 MeV < E < 1 MeV). (author)

  7. Boron carbide, a potentially dangerous material in nuclear reactors

    International Nuclear Information System (INIS)

    Certain kinds of nuclear reactors, e.g. Boiling Water Reactors (BWRs) are controlled by rods containing some neutron absorbing material. A common material of that kind is boron carbide (B4C). The control rods are made from stainless steel, and have cavities filled with B4C. At first sight, this appears to be an ideal combination, as there is a high concentration of the neutron absorbing element boron, and both materials are comparatively inert. At high temperatures they may, however, react violently producing a chemically aggressive melt. The reaction is exothermic and once started, it continues spontaneously. Differential Thermal Analysis (DTA) has been used to measure the reaction enthalpy for a mixture of 10% (by weight) of B4C and 90% of stainless steel. A reaction enthalpy of 4.37 ± 0.19 kJ/g B4C has been found. The reaction starts at 1100 deg. C, or even lower temperature. In a reactor accident, this may cause the control rods to melt at a temperature that is more than 400 degrees lower than the melting point of stainless steel. Furthermore, it has been found that the resulting melt is able to dissolve at least its own weight of stainless steel. Thus, in addition to loss of control rods, the reaction may cause a premature failure of the reactor vessel, as the bottom may dissolve in the molten control rods. (authors)

  8. Modelling of Boron Trapping at End-of-Range defects in pre-amorphized ultra-shallow junctions

    Energy Technology Data Exchange (ETDEWEB)

    Bazizi, E.M. [LAAS/CNRS, University of Toulouse, 7 av. Col. Roche, 31077 Toulouse (France); STMicroelectronics, 850 rue Jean Monnet, 38926 Crolles Cedex (France); CEMES/CNRS, 29 rue J. Marvig, 31055 Toulouse (France)], E-mail: bazizi@laas.fr; Fazzini, P.F. [LAAS/CNRS, University of Toulouse, 7 av. Col. Roche, 31077 Toulouse (France); Zechner, C.; Tsibizov, A. [Synopsys Switzerland LLC, Affolternstrasse 52, 8050 Zuerich (Switzerland); Kheyrandish, H. [CSMA, Queens Road, Penkhull, Stoke-on-Trent, Staffordshire ST4 7LQ (United Kingdom); Pakfar, A.; Ciampolini, L.; Tavernier, C. [STMicroelectronics, 850 rue Jean Monnet, 38926 Crolles Cedex (France); Cristiano, F. [LAAS/CNRS, University of Toulouse, 7 av. Col. Roche, 31077 Toulouse (France)

    2008-12-05

    In this work, the evolution of boron trapping at End-of-Range (EOR) defects was investigated by secondary ion mass spectrometry (SIMS) and transmission electron microscope (TEM). Si wafers with a constant boron concentration of 2 x 10{sup 18} cm{sup -3} were implanted with 30 keV germanium and with a dose of 10{sup 15} cm{sup -2} and then annealed at 700, 800, or 900 deg. C in an N{sub 2} ambient for various times. The experimental results suggest that the evolution of boron-trapping peak is driven by the evolution of {l_brace}3 1 1{r_brace} defects and that the dislocation loops contribution to the trapping mechanism is less pronounced. An analytic model for the concurrent boron trapping at {l_brace}3 1 1{r_brace} defects and dislocation loops was developed by taking into account the geometry of the EOR defects. The trapped species is represented by neutral BI pairs which can be captured either by {l_brace}3 1 1{r_brace} defects or by dislocation loops. The model accurately reproduces the complex evolution of the trapping peak as a function of both the annealing time and temperature. These results confirm that the evolution of the boron-trapping peak is closely related to the evolution of the {l_brace}3 1 1{r_brace} defects, therefore suggesting that boron trapping is associated to the capture and release of boron atoms at the {l_brace}3 1 1{r_brace} defects formed in the EOR region.

  9. P13.09ADVANCES IN CLINICAL APPLICATION OF BORON NEUTRON CAPTURE THERAPY (BNCT) IN GLIOBLASTOMA

    OpenAIRE

    Detta, A.; Cruickshank, G.C.; Green, S.; Lockyer, N.P.; Ngoga, D.; Ghani, Z.; Phoenix, B

    2014-01-01

    BNCT is a biologically targeted form of enhanced cellular radiotherapy where preferential accumulation of boron in the cancerous as opposed to adjacent normal cells is able to interact with incident neutrons to cause irreversible alpha particle DNA damage. The key to the implementation of this potentially powerful and selective therapy is the delivery of at least 30ppm 10B within the tumour tissue while minimising superfluous 10B in healthy tissue. It is thus an elegant technique for treating...

  10. Properties of Boron Carbide Coatings and Free-Standing Parts Prepared by WSP(r)

    Czech Academy of Sciences Publication Activity Database

    Matějíček, Jiří; Nanobashvili, S.; Ctibor, Pavel; Brožek, Vlastimil; Neufuss, Karel; Chráska, Pavel

    Franfurkt : WerkstoffInformationsgesselschaft, 2002, s. článek č.914. ISBN 3-88355-302-6. [Materials Week 2001.. Mnichov (DE), 01.10.2001-04.10.2001] R&D Projects: GA ČR GA104/01/0149 Institutional research plan: CEZ:AV0Z2043910 Keywords : water-stabilized plasma spraying, boron carbide, material properties Subject RIV: JK - Corrosion ; Surface Treatment of Materials

  11. Boron absorption imaging in rat lung colon adenocarcinoma metastases

    Science.gov (United States)

    Altieri, S.; Bortolussi, S.; Bruschi, P.; Fossati, F.; Vittor, K.; Nano, R.; Facoetti, A.; Chiari, P.; Bakeine, J.; Clerici, A.; Ferrari, C.; Salvucci, O.

    2006-05-01

    Given the encouraging results from our previous work on the clinical application of BNCT on non-resectable, chemotherapy resistant liver metastases, we explore the possibility to extend our technique to lung metastases. A fundamental requirement for BNCT is achieving higher 10B concentrations in the metastases compared to those in healthy tissue. For this reason we developed a rat model with lung metastases in order to study the temporal distribution of 10B concentration in tissues and tumoral cells. Rats with induced lung metastases from colon adenocarcinoma were sacrificed two hours after intraperitoneal Boronphenylalanine infusion. The lungs were harvested, frozen in liquid nitrogen and subsequently histological sections underwent neutron autoradiography in the nuclear reactor Triga Mark II, University of Pavia. Our findings demonstrate higher Boron uptake in tumoral nodules compared to healthy lung parenchyma 2 hours after Boronphenylalanine infusion.

  12. Reprocessing of {sup 10}B-contaminated {sup 10}Be AMS targets

    Energy Technology Data Exchange (ETDEWEB)

    Simon, K.J., E-mail: ksz@ansto.gov.au [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee NSW 2232 (Australia); Pedro, J.B. [Institute of Marine and Antarctic Studies, Private Bag 129, Hobart TAS 7001 (Australia); Antarctic Climate and Ecosystems Cooperative Research Centre, Private Bag 80, Hobart TAS 7001 (Australia); Smith, A.M.; Child, D.P.; Fink, D. [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee NSW 2232 (Australia)

    2013-01-15

    {sup 10}Be 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 {sup 10}Be measurements through interference from the isobar {sup 10}B. 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 H{sub 2}SO{sub 4}. The solution was then heated with HF to remove the boron as volatile BF{sub 3} before re-precipitating as Be(OH){sub 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 Multiplication-Sign , which were sufficiently low and similar to previous successful batches of ice core, snow and associated blank samples, thus allowing a successful {sup 10}Be 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 H{sub 2}SO{sub 4} + HF step has been subsequently added to the standard ice processing method.

  13. Studies of boron hydrides: new heteroboranes

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    KAUST Repository

    Valladares Linares, Rodrigo

    2014-07-17

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

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

    International Nuclear Information System (INIS)

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

  17. ISOBORDAT: An Online Data Base on Boron Isotopes

    International Nuclear Information System (INIS)

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

  18. Synthesis and characterization of ammonium phosphate fertilizers with boron

    Directory of Open Access Journals (Sweden)

    ANGELA MAGDA

    2010-07-01

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

  19. Structure and single-phase regime of boron carbides

    Science.gov (United States)

    Emin, David

    1988-09-01

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

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

    International Nuclear Information System (INIS)

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