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Sample records for boron lined counters

  1. Neutron sensitivity improvement in boron-lined proportional counters

    International Nuclear Information System (INIS)

    Dighe, P.M.; Prasad, K.R.; Kataria, S.K.

    2002-01-01

    Various techniques have been employed to improve the neutron sensitivity of boron-coated proportional counters developed indigenously. A boron-lined proportional counter (67 mm ID x 750 mm length) of 17 cps/nv thermal neutron sensitivity is developed by coating 92% enriched 10 B on the inner wall of the counter. This counter can be used for low thermal neutron flux (∼0.2 nv) at various applications such as neutron area monitoring, reactor start-up instrumentation, assay of fissile materials and detection of fuel failure. An improvement in sensitivity was also achieved by summing the output signals from four 10 B lined counters and two BF 3 proportional counters. The summation did not change the susceptibility of the device to gamma interference. In view of the scarcity of enriched 10 B isotope, indigenously available natural boron coated two prototype proportional counters are developed of 0.8 cps/nv and 1.1 cps/nv thermal neutron sensitivity. Efforts have been made to improve the sensitivity with boron coated 3-dimensional structures introduced into the sensitive volume. Tests in thermal neutron flux showed 50% improvement in the sensitivity due to the introduction of additional boron coated wires. Another counter with 51 boron-coated annular discs (23 mm OD X 10 mm ID X 1 mm thick) mounted perpendicular to the axis of the cathode showed 1.7 cps/nv neutron sensitivity, an improvement by a factor of 2.5. (author)

  2. New cathode design boron lined proportional counters for neutron area monitoring application

    International Nuclear Information System (INIS)

    Dighe, Priyamvada M.

    2007-01-01

    A new cathode design boron lined proportional counter of 26mm IDx100mm sensitive length SS304 cathode has been developed with boron-coated baffles separated by 3mm spacers inserted in the sensitive volume perpendicular to the axis. The baffles and the spacers were coated with indigenously available 27.7% enriched 10 B. The introduction of baffles enhanced the boron coated surface area by a factor of 2.8. Tests in 120nv thermal neutron flux show that the counter has 0.84cps/nv thermal neutron sensitivity, which shows enhancement in the sensitivity by a factor of 2.78 due to baffle structure. For comparison standard cylindrical cathode geometry counter coated with 92% enriched 10 B on its inner wall with a coating thickness of 0.8mg/cm 2 is developed with same outer dimensions for neutron area monitoring applications. The counter has 1cps/nv thermal neutron sensitivity. Comparative tests carried out on counters with and without baffle structure show that the baffles enhance the neutron sensitivity and in 2kR/h gamma background the effect of gamma pile up is similar on both the counters. The variation in cathode internal diameter due to baffle structure gives higher voltage plateau slope (2.8%/10V) as compared to conventional cylindrical geometry counter (1.2%/10V). The usability of boron lined counters for neutron area monitoring applications for the cylindrical geometry counter has been studied

  3. 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.

  4. Indigenous development of B-10 lined proportional counters

    International Nuclear Information System (INIS)

    Dighe, P.M.; Prasad, K.R.

    1997-01-01

    Boron lined proportional counters are required for neutron flux measurements in many important applications that include research and power reactor startup instrumentation, REM monitoring in health physics, plutonium waste monitoring in radiological laboratories and so forth. An all-welded high purity aluminium counter with integral m.i. cable assembly having 3.5 cps/nv neutron sensitivity has been developed. Special explosion welded SS-Al clad plate has been used as end plate to weld the ceramic metal seals and also to weld the m.i. cable outer sheath. It was filled with Ar+CO 2 gas mixture at 20cm Hg. This counter showed 40% reduction in sensitivity in 1000r/h gamma background. There was no change in its performance at 100 deg C. Similar counters are under fabrication for Fast Breeder Test Reactor (FBTR) start up instrumentation. Another SS counter with 28 mm OD and 100 mm sensitive length with the same gas filling has been developed. It has 0.8 cps/nv sensitivity and will be used for REM monitoring. 9 refs., 8 figs

  5. A passive rem counter based on CR39 SSNTD coupled with a boron converter

    CERN Document Server

    Agosteo, S; Ferrarini, c, M; Silari, M

    2009-01-01

    A passive neutron rem counter using a CR39 SSNTD coupled with a boron converter has been developed. The rem counter is a polythene sphere with cadmium and lead insets, designed to have a response function proportional to the fluence to ambient dose equivalent conversion coefficients, H*(10)/Φ, for energies ranging from thermal up to 1 GeV. At its centre is a thermal neutron detector made of a CR39 SSNTD coupled with an enriched boron neutron converter. The rem counter was first calibrated at CERN and at the Politecnico di Milano, and then tested in high-energy neutron fields at GSI, Darmstadt, Germany and at the CERF facility at CERN. Its most important features are a very high neutron sensitivity and conversely a complete insensitivity to gamma radiation.

  6. Study of temperature and timing properties of slow-neutron boron counters of the SNM-11 and SNM-32 types

    International Nuclear Information System (INIS)

    Andrianov, V.V.; Demidov, F.P.; Karlashchuk, V.I.; Kondrat'ev, I.A.; Kokhov, E.D.; Krejndlin, I.I.; Telkov, Yu.N.

    1979-01-01

    Investigation results of characteristics of slow-neutron boron counters within temperature range from -60 to +150 deg C, and at temperature cyclic effects are given. Eight counters of SNM-11 and 16 counters of SNM-32 type have been chosen for investigation. Analysis of differential pulse spectra of SNM-11 and CNM-32 type counters shows, that parameters of dicrimination characteristics are not, practically, changed within temperature range from -60 to +20 deg C, while whithin +20-+150 deg C temperature range plato extension of the discrimination characteristics decreases, in average, in 15% due to growth of noise level. It is stated on the base of the analysis of temperature dependences of counter counting rate, that SNM-11 type counters have better temperature stability, than SNM-32 type counters. Dependences of counter counting rate on the number of temperature effect cycles are also given. It is stated that counter residual phenomena do not take place after the effect of 10 cycles of temperature drops. Investigations of time instability of counters have given the following results: mean square deviation within 3 days does not exceed 0.8% for SNM-11 type counters, and 1.1%-for SNM-32 type counters. It is concluded on the basis of the obtained results, that SNM-11 type counters are more preferable by their temperature and time characteristics, than SNM-32 type counters

  7. Ab initio study of boron nitride lines on graphene

    Science.gov (United States)

    Mata-Carrizal, Berenice; Sanginés-Mendoza, Raúl; Martinez, Edgar

    2013-03-01

    Graphene has unusual electronic properties which make it a promising material for electronic devices. Neverthless, the absence of a band gap sets limitations on its practical applications. Thus, it is crucial to find methods to create and tune the band gap of systems based on graphene. In this way, we explore the modulation of the electronic properties of graphene through doping with boron nitride lines. In particular, we studied the electronic structure of graphene sheets doped with boron nitride lines armchair and zigzag type. The calculations were performed using the pseudopotential LCAO method with a Generalized Gradient Approximation (GGA) for the exchange-correlation energy functional. We found that both doping lines type induce a bandgap and that the energy gap increases as the length of doping lines increases. Accordingly to our DFT calculations, we found that the energy gap on graphene doped with armchair and zigzag lines is due to a two different mechanisms to drain charge from pi- to sigma- orbitals. Thus, we found that doping graphene with boron nitride lines is a useful way to induce and modulate the bandgap on graphene. This research was supported by Consejo Nacional de Ciencia y Tecnología (Conacyt) under Grant No. 133022.

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

    OpenAIRE

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

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Andrić Luka

    2016-01-01

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

  10. Measuring the sensitivity of a boron-lined ion chamber

    International Nuclear Information System (INIS)

    Barton, D.M.

    1992-03-01

    Boron-lined ion chambers are used to monitor external neutron flux from fissionable materials assembled at the Los Alamos Critical Assembly Experiment Facility. The sensitivity of these chambers must be measured periodically in order to detect changes in filling gas and to evaluate other factors that may affect chamber performance. We delineate a procedure to measure ion chamber response using a particular neutron source ( 239 PuBe) in a particular moderating geometry of polyethylene. We also discuss use of the amplifier, high-voltage power supply, recorders, and scram circuits that comprise the complete ion chamber monitoring system

  11. Source Lines Counter (SLiC) Version 4.0

    Science.gov (United States)

    Monson, Erik W.; Smith, Kevin A.; Newport, Brian J.; Gostelow, Roli D.; Hihn, Jairus M.; Kandt, Ronald K.

    2011-01-01

    Source Lines Counter (SLiC) is a software utility designed to measure software source code size using logical source statements and other common measures for 22 of the programming languages commonly used at NASA and the aerospace industry. Such metrics can be used in a wide variety of applications, from parametric cost estimation to software defect analysis. SLiC has a variety of unique features such as automatic code search, automatic file detection, hierarchical directory totals, and spreadsheet-compatible output. SLiC was written for extensibility; new programming language support can be added with minimal effort in a short amount of time. SLiC runs on a variety of platforms including UNIX, Windows, and Mac OSX. Its straightforward command-line interface allows for customization and incorporation into the software build process for tracking development metrics. T

  12. Design and evaluation of experimental on line boron meter for Light Water Reactors

    International Nuclear Information System (INIS)

    Dighe, P.M.; Kamble, L.P.; Bhatnagar, P.V.; Das, D.; Swetha, M.; Patel, P.; Nathani, K.; Sen, S.K.

    2018-01-01

    Measurement of boron concentration in most PWR reactors is a critical activity, as dissolved boron is used to provide the required negative reactivity margins, whereas control rods provide control and safety actions. In nuclear plants, the usual and mandatory practice for boron concentration measurement is a manual, off line chemical titrimetry of boron. However, with current technological solutions such measurements can also be performed online to provide continuous signal to the operator. In the PWR reactors at Kudankulam present Online Boron meters (OLBM) installed are based on the imported design. Commercially OLBM are reported to be developed by Areva, Rolls-Royce etc. For indigenisation and to provide import substitute, efforts are underway to design and develop OLBMs. Towards this development an experimental set up was constructed taking inputs from Kudankulam OLBMs and by simulations using FLUKA Monte-Carlo software. The set up was experimentally evaluated for generation of calibration curves

  13. Boron-10 ABUNCL Active Testing

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-09

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

  14. Solution In-Line Alpha Counter (SILAC) Instruction Manual-Version 4.00

    International Nuclear Information System (INIS)

    Alferink, Steven M.; Farnham, Joel E.; Fowler, Malcolm M.; Wong, Amy S.

    2002-01-01

    The Solution In-Line Alpha Counter (SILAC) provides near real-time alpha activity measurements of aqueous solutions in gloveboxes located in the Plutonium Facility (TA-55) at Los Alamos National Laboratory (LANL). The SILAC detector and its interface software were first developed by Joel Farnham at LANL [1]. This instruction manual describes the features of the SILAC interface software and contains the schematic and fabrication instructions for the detector

  15. Development of a low-level, in-line alpha counter (LLILAC)

    International Nuclear Information System (INIS)

    Gritzo, R.E.; Farnham, J.E.; Fowler, M.M.; Wouters, J.

    1996-01-01

    This is the final report of a two-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). With the increasing awareness of water contamination issues and the rising consequences of any form of contamination, real-time continuous monitoring is rapidly becoming a necessity. In particular, monitoring for the presence of any radioactive material is paramount. The most difficult of such monitoring tasks is that of detecting alpha-emitting radionuclides in water. Our development of the Low Level In-Line Alpha Counter (LLILAC) addresses the need for on-line, near real-time monitoring of alpha-emitting radionuclides in aqueous streams in a wide variety of applications. Although primarily designed as an on-line instrument for real-time applications, the detector can also be used for long-term in situ/post-closure monitoring. This detection system operates by allowing the stream to be monitored to come in contact with a large number of small rods or tubes made of scintillation material. By maximizing the surface to volume ratio of the scintillator, the response to alpha particles is favored over other types of radiation. Several configurations of scintillator and light collection schemes have been investigated to optimize the detection efficiency. We have also written several Monte Carlo codes to help to predict and understand the detector performance

  16. A simple efficient method of delay-line termination and timing-signals extraction in position-sensitive proportional counters

    International Nuclear Information System (INIS)

    Birk, M.; Breskin, A.; Trautner, N.

    1976-01-01

    Pulse transformers are used to match the readout delay line (Z 0 approximately 1.5 kΩ) in a position-sensitive proportional counter to 50-ohm cables, which are terminated by the input impedances of remotely located ground-gate FET aplifiers. Good terminations and high slope-to-noise ratios were achieved. (author)

  17. Use of GEANT4 vs. MCNPX for the characterization of a boron-lined neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    Ende, B.M. van der; Atanackovic, J.; Erlandson, A.; Bentoumi, G.

    2016-06-01

    This work compares GEANT4 with MCNPX in the characterization of a boron-lined neutron detector. The neutron energy ranges simulated in this work (0.025 eV to 20 MeV) are the traditional domain of MCNP simulations. This paper addresses the question, how well can GEANT4 and MCNPX be employed for detailed thermal neutron detector characterization? To answer this, GEANT4 and MCNPX have been employed to simulate detector response to a {sup 252}Cf energy spectrum point source, as well as to simulate mono-energetic parallel beam source geometries. The {sup 252}Cf energy spectrum simulation results demonstrate agreement in detector count rate within 3% between the two packages, with the MCNPX results being generally closer to experiment than are those from GEANT4. The mono-energetic source simulations demonstrate agreement in detector response within 5% between the two packages for all neutron energies, and within 1% for neutron energies between 100 eV and 5 MeV. Cross-checks between the two types of simulations using ISO-8529 {sup 252}Cf energy bins demonstrates that MCNPX results are more self-consistent than are GEANT4 results, by 3–4%.

  18. Fields of line charges in coaxial counters of circular or square cross sections

    International Nuclear Information System (INIS)

    Carli, C.

    1989-10-01

    Counters of square cross section with a thin wire as central conductor are gaining increasing importance in high energy physics experiments. The potential, the electrical field and the charges induced on strips corresponding to the sides of the square are calculated in a two -dimensional model using complex field representation. The Green's function of the square counter is calculated from the Green's function of the circular counter by conformal mapping. The convergence of series expansions of the Green's function is improved by extracting singularities of the source and of image charges. Counters without dielectric layer on the electrodes and a more sophisticated model of counters with a thin dielectric layer on the outer electrode are considered. (author)

  19. Water Stress and Foliar Boron Application Altered Cell Wall Boron and Seed Nutrition in Near-Isogenic Cotton Lines Expressing Fuzzy and Fuzzless Seed Phenotypes

    Science.gov (United States)

    2015-01-01

    Our previous research, conducted under well-watered conditions without fertilizer application, showed that fuzziness cottonseed trait resulted in cottonseed nutrition differences between fuzzy (F) and fuzzless (N) cottonseed. Under water stress conditions, B mobility is further limited, inhibiting B movement within the plant, affecting seed nutrition (quality). Therefore, we hypothesized that both foliar B and water stress can affect B mobility, altering cottonseed protein, oil, and mineral nutrition. The objective of the current research was to evaluate the effects of the fuzziness seed trait on boron (B) and seed nutrition under water stress and foliar B application using near-isogenic cotton lines (NILs) grown in a repeated greenhouse experiment. Plants were grown under-well watered conditions (The soil water potential was kept between -15 to -20 kPa, considered field capacity) and water stress conditions (soil water potential between -100 and -150 kPa, stressed conditions). Foliar B was applied at a rate of 1.8 kg B ha-1 as H3BO3. Under well-watered conditions without B the concentrations of seed oil in N lines were higher than in F lines, and seed K and N levels were lower in N lines than in F lines. Concentrations of K, N, and B in leaves were higher in N lines than in F lines, opposing the trend in seeds. Water-stress resulted in higher seed protein concentrations, and the contribution of cell wall (structural) B to the total B exceeded 90%, supporting the structural role of B in plants. Foliar B application under well-watered conditions resulted in higher seed protein, oil, C, N, and B in only some lines. This research showed that cottonseed nutrition differences can occur due to seed fuzziness trait, and water stress and foliar B application can alter cottonseed nutrition. PMID:26098564

  20. 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.

  1. Development of an on-line isotope dilution laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) method for determination of boron in silicon wafers.

    Science.gov (United States)

    Yang, Chao-Kai; Chi, Po-Hsiang; Lin, Yong-Chine; Sun, Yuh-Chang; Yang, Mo-Hsiung

    2010-01-15

    A method has been developed based on an on-line isotope dilution technique couple with laser ablation/inductively coupled plasma mass spectrometry (LA-ICP-MS), for the determination of boron in p-type silicon wafers. The laser-ablated sample aerosol was mixed on-line with an enriched boron aerosol supplied continuously using a conventional nebulization system. Upon mixing the two aerosol streams, the isotope ratio of boron changed rapidly and was then recorded by the ICP-MS system for subsequent quantification based on the isotope dilution principle. As an on-line solid analysis method, this system accurately quantifies boron concentrations in silicon wafers without the need for an internal or external solid reference standard material. Using this on-line isotope dilution technique, the limit of detection for boron in silicon wafers is 2.8x10(15)atomscm(-3). The analytical results obtained using this on-line methodology agree well with those obtained using wet chemical digestion methods for the analysis of p-type silicon wafers containing boron concentrations ranging from 1.0x10(16) to 9.6x10(18)atomscm(-3).

  2. Beam Cherenkov counter conception for in line identification of 270 GeV/c Σ- Ξ- and Ω-

    International Nuclear Information System (INIS)

    Touillon, R.

    1991-06-01

    The purpose of this thesis is to design a beam Cerenkov counter. This counter will provide an on line identification of the Σ - , Ξ - and Ω - hyperons (270 GeV/c) in the experiment WA89 at CERN. The acceptance of the detector should allow tagging these hyperons in a large momentum range (± 25%) and for a beam divergence up to 250 microrad. The first part of this report is devoted to the physical goals such as the study of charmed baryons, the search of multiquark states, and the determination of hadronic and electromagnetic hyperon radii. The experimental WA89 setup is also presented. The major part deals with the design of the Cerenkov counter. The dimension of the detector, the Cerenkov angle value, the focal length of the spherical mirror, etc... are derived from a Monte-Carlo simulation. Various methods of simple photon detection (gaz detector: TEA, TMAE; solid detectors: PM and Image Intensifier) are investigated. The most performing solution uses two conical mirrors in order to reduce the size of the Cerenkov circles and an image intensifier (which detects the single photon) followed by an optical fiber matrix transmitting the luminous signal to 160 photomultipliers. The on line procedure for calculating the radius of each circle (identification of the particle) is studied in detail. Finally, the optimization of the optical system to achromatize the Cerenkov light is discussed [fr

  3. Measurement of in-phantom neutron flux and gamma dose in Tehran research reactor boron neutron capture therapy beam line.

    Science.gov (United States)

    Bavarnegin, Elham; Sadremomtaz, Alireza; Khalafi, Hossein; Kasesaz, Yaser

    2016-01-01

    Determination of in-phantom quality factors of Tehran research reactor (TRR) boron neutron capture therapy (BNCT) beam. The doses from thermal neutron reactions with 14N and 10B are calculated by kinetic energy released per unit mass approach, after measuring thermal neutron flux using neutron activation technique. Gamma dose is measured using TLD-700 dosimeter. Different dose components have been measured in a head phantom which has been designed and constructed for BNCT purpose in TRR. Different in-phantom beam quality factors have also been determined. This study demonstrates that the TRR BNCT beam line has potential for treatment of superficial tumors.

  4. Boron neutron capture therapy (BNCT) using fast neutrons: Effects in two human tumor cell lines

    International Nuclear Information System (INIS)

    Sauerwein, W.; Ziegler, W.; Szypniewski, H.; Streffer, C.

    1990-01-01

    The results demonstrate that the effect of fast neutrons on cell survival in cell culture can be enhanced by boron neutron capture reaction. Even with lower enhancement ratios, the concept of NCT assisted fast neutron therapy may successfully be applied for tumor treatment with the Essen cyclotron. (orig.)

  5. 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.

  6. A gamma-ray telescope for on-line measurements of low boron concentrations in a head-phantom for BNCT

    Energy Technology Data Exchange (ETDEWEB)

    Verbakel, W.F.A.R.

    1996-06-01

    In Boron Neutron Capture Therapy the {sup 10}B(n, {alpha}){sup 7}Li reaction is used to create a tumour destructing field by the emitted high-LET (Linear Energy Transfer) particles. This reaction is accompanied by the emission of a photon of energy 478 keV. This can serve as a probe for detection of the reaction rate and thereby provide a tool to assess the boron concentration during therapy. An experimental configuration has been designed for on-line measurements of the {sup 10}B prompt gamma rays in a background of hydrogen neutron capture prompt gamma rays, neutrons and gamma rays coming from the reactor. At a facility with epithermal neutrons of the Low Flux Reactor a head phantom has been irradiated with neutorns. This phantom is filled with water and a small volume of 7.8 cm{sup 3} containing 62 ppm {sup 10}B, simulating a tumour. The experimental configuration for prompt gamma measurements has been expanded to perform tomography. The reconstruction of the position and the size of the tumour and its boron cencentration appeared to be possible. The first experiments at the therapy room in the High Flux Reactor showed that this method can probably be expanded for on-line monitoring of the total boron amount in a patients head. Next to this, Monte Carlo calculations and foil activation measurements have been performed to obtain the neutron spectrum of the epithermal beam of the LFR. With the insight achieved with these calculations it has been possible to optimize the total neutron flux. By introduction of a graphite scatter in the beam tube close to the reactr core, the flux has been rainsed with about 65%. With the computer code DORT neutron distributions over the phantom have been calculated for 47 energy groups. These calculations are necessary for ultimate boron tomography. (orig.).

  7. Studi Awal Pengaruh Pemberian Asam Boron dan Penembakan Neutron terhadap cell fibroblast dan cell lineKanker Payudara

    Directory of Open Access Journals (Sweden)

    Giner Maslebu

    2017-11-01

    Full Text Available Kanker merupakan salah satu penyakit mematikan yang mendapatkan perhatian serius oleh peneliti dan praktisi di bidang kesehatan. Penyakit kanker adalah penyakit yang timbul akibat pertumbuhan tidak normal sel jaringan tubuh yang berubah menjadi sel kanker.Dari berbagai jenis kanker, kasus yang paling banyak terjadi pada kaum perempuan adalah kanker payudara. Teknik pengobatan kanker terus dikembangkan sehingga mampu secara selektif membunuh target sel kanker (cell targeting dan memberikan efek yang minimal bagi sel sehat di sekitar target. Salah satu teknik pengobatan yang menjanjikan adalah Boron Neutron Captured Teraphy (BNCT. Dalam penelitian ini, sel fibroblast dan sel kanker payudara T47D dipanen pada sumuran setelah diinkubasi selama 16 jam, kemudian diberikan perlakuan  asam boron dengan dosis asam boron berjenjang 100 µM, 200 µM, 400 µM.Penembakan neutron diberikan dengan flux sebesar 1010 neutron/cm2s mengggunakan sumber neutron pada fasilitas reaktor Kartini PSTA-Batan terhadap kultur selselama 30 menit. Pada sel fibroblast tingkat kematian sel berkisar antara 2,5-21,212 % setelah pemberian asam Boron dan meningkat menjadi 24,242-71,424 % setelah penembakan neutron. Pada sel kanker payudara T47D tingkat kematian sel berkisar antara 26,761-48,76 % setelah pemberian asam Boron dan meningkat menjadi 36,585-56,25 % setelah penembakan neutron. Hasil penelitian ini menunjukkan ada pengaruh pemberian asam Boron dan penembakan Neutron terhadap tingkat kematian sel.

  8. First evaluation of the biologic effectiveness factors of boron neutron capture therapy (BNCT) in a human colon carcinoma cell line.

    Science.gov (United States)

    Dagrosa, Maria Alejandra; Crivello, Martín; Perona, Marina; Thorp, Silvia; Santa Cruz, Gustavo Alberto; Pozzi, Emiliano; Casal, Mariana; Thomasz, Lisa; Cabrini, Romulo; Kahl, Steven; Juvenal, Guillermo Juan; Pisarev, Mario Alberto

    2011-01-01

    DNA lesions produced by boron neutron capture therapy (BNCT) and those produced by gamma radiation in a colon carcinoma cell line were analyzed. We have also derived the relative biologic effectiveness factor (RBE) of the neutron beam of the RA-3- Argentine nuclear reactor, and the compound biologic effectiveness (CBE) values for p-boronophenylalanine ((10)BPA) and for 2,4-bis (α,β-dihydroxyethyl)-deutero-porphyrin IX ((10)BOPP). Exponentially growing human colon carcinoma cells (ARO81-1) were distributed into the following groups: (1) BPA (10 ppm (10)B) + neutrons, (2) BOPP (10 ppm (10)B) + neutrons, (3) neutrons alone, and (4) gamma rays ((60)Co source at 1 Gy/min dose-rate). Different irradiation times were used to obtain total absorbed doses between 0.3 and 5 Gy (±10%) (thermal neutrons flux = 7.5 10(9) n/cm(2) sec). The frequency of micronucleated binucleated cells and the number of micronuclei per micronucleated binucleated cells showed a dose-dependent increase until approximately 2 Gy. The response to gamma rays was significantly lower than the response to the other treatments (p irradiations with neutrons alone and neutrons + BOPP showed curves that did not differ significantly from, and showed less DNA damage than, irradiation with neutrons + BPA. A decrease in the surviving fraction measured by 3-(4,5-dimetiltiazol-2-il)-2,5-difeniltetrazolium bromide (MTT) assay as a function of the absorbed dose was observed for all the treatments. The RBE and CBE factors calculated from cytokinesis block micronucleus (CBMN) and MTT assays were, respectively, the following: beam RBE: 4.4 ± 1.1 and 2.4 ± 0.6; CBE for BOPP: 8.0 ± 2.2 and 2.0 ± 1; CBE for BPA: 19.6 ± 3.7 and 3.5 ± 1.3. BNCT and gamma irradiations showed different genotoxic patterns. To our knowledge, these values represent the first experimental ones obtained for the RA-3 in a biologic model and could be useful for future experimental studies for the application of BNCT to colon carcinoma

  9. Boron reclamation

    International Nuclear Information System (INIS)

    Smith, R.M.

    1980-07-01

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

  10. Space-Confined Synthesis of Three-Dimensional Boron/Nitrogen-Doped Carbon Nanotubes/Carbon Nanosheets Line-in-Wall Hybrids and Their Electrochemical Energy Storage Applications

    DEFF Research Database (Denmark)

    Zhu, Shan; Li, Jiajun; Li, Qingfeng

    2016-01-01

    and CNTs in this unique pattern, the LIW-NB integrates advantages of three aspects: first, the doped heteroatoms enhancing electrochemical properties of carbon matrix; second, the warp-proof nanosheets supplying high specific surface area; and the extracted and embedded CNTs serving as electron conductive...... paths and reinforcing the whole architecture. As a result, the 3D LIW-NB shows excellent electrochemical properties: as the electrode of supercapacitors, LIW-NB exhibits high specific capacity at different current densities (389 F g-1 at 1 A g-1 and 129 F g-1 at 20 Ag-1); as the lithium ion battery......This research demonstrates a flexible one-pot strategy for fabricating three-dimensional (3D) boron/nitrogen-doped networks of carbon nanotubes(CNTs)/carbon nanosheets "Line-in-Wall" hybrids (LIWNB) based on the space-confined template method. In the synthesis, the high rate of freezing step...

  11. Boron isotopic enrichment by displacement chromatography

    International Nuclear Information System (INIS)

    Mohapatra, K.K.; Bose, Arun

    2014-01-01

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

  12. Nuclear timer/counter

    International Nuclear Information System (INIS)

    Wuthayavanich, S.

    1978-01-01

    This thesis represents the development of a Timer/COUNTER compatible to the standard Nuclear Instrument Module Specifications. The unit exhibits high accuracy, light weight and ease of maintenance. The unit also has a built-in precision discriminator to discriminate unwanted signals that may cause interference in counting. With line frequency time base the timer can be preset in steps from 0.1 sec. to 9 x 10 5 min. The counter with six digits miniature display and an overflow output has a maximum counting rate of 10 MHz. The accumulated counting data can be transferred to a teletype or printer for hard copy printout with the aid of ORTEC 777 Line Printer or 432 A Print-out Control or any print out interface with input compatible to the print output of the Timer/Counter. Owing to its NIM compatibility the unit is directly powered by the NIM power supply

  13. On-line coupling of counter-current chromatography and macroporous resin chromatography for continuous isolation of arctiin from the fruit of Arctium lappa L.

    Science.gov (United States)

    Guo, Mengzhe; Liang, Junling; Wu, Shihua

    2010-08-13

    In this work, we have developed a novel hybrid two-dimensional counter-current chromatography and liquid chromatography (2D CCC x LC) system for the continuous purification of arctiin from crude extract of Arctium lappa. The first dimensional CCC column has been designed to fractionalize crude complex extract into pure arctiin effluent using a one-component organic/salt-containing system, and the second dimensional LC column has been packed with macroporous resin for on-line adsorption, desalination and desorption of arctiin which was effluent purified from the first CCC dimension. Thus, the crude arctiin mixture has been purified efficiently and conveniently by on-line CCC x LC in spite of the use of a salt-containing solvent system in CCC separation. As a result, high purity (more than 97%) of arctiin has been isolated by repeated injections both using the ethyl acetate-8% sodium chloride aqueous solution and butanol-1% sodium chloride aqueous solution. By contrast with the traditional CCC processes using multi-component organic/aqueous solvent systems, the present on-line CCC x LC process only used a one-component organic solvent and thus the solvent is easier to recover and regenerate. All of used solvents such as ethyl acetate, n-butanol and NaCl aqueous solution are low toxicity and environment-friendly. Moreover, the lower phase of salt-containing aqueous solution used as mobile phase, only contained minor organic solvent, which will save much organic solvent in continuous separation. In summary, our results indicated that the on-line hybrid 2D CCC x LC system using one-component organic/salt-containing aqueous solution is very promising and powerful tool for high-throughput purification of arctiin from fruits of A. lappa. 2010 Elsevier B.V. All rights reserved.

  14. Separation of polyphenols from leaves of Malus hupehensis (Pamp.) Rehder by off-line two-dimensional High Speed Counter-Current Chromatography combined with recycling elution mode.

    Science.gov (United States)

    Liu, Qi; Zeng, Hualiang; Jiang, Shujing; Zhang, Li; Yang, Fuzhu; Chen, Xiaoqing; Yang, Hua

    2015-11-01

    In this study, off-line two-dimensional High Speed Counter-Current Chromatography (2D HSCCC) strategy combined with recycling elution mode was developed to isolate compounds from the ethyl acetate extract of a common green tea--leaves of Malus hupehensis (Pamp.) Rehder. In the orthogonal separation system, a conventional HSCCC was employed for the first dimension and two recycling HSCCCs were used for the second in parallel. Using a solvent system consisting of n-hexane-ethyl acetate-methanol-water (1:4:0.6:4.4, v/v) in the first and second dimension, four compounds including 3-hydroxy-phlorizin (1), phloretin (2), avicularin (3) and kaempferol 3-O-β-D-glucoside (4) were obtained. The purities of these four compounds were all over 95.0% as determined by HPLC. And their structures were all identified through UV, MS and (1)H NMR. It has been demonstrated that the combination of off-line 2D HSCCC with recycling elution mode is an efficient technique to isolate compounds with similar polarities in natural products. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Neutron position sensitive proportional counter

    International Nuclear Information System (INIS)

    Gal'tsov, V.S.; Zakharkin, I.I.; Kuznetsov, V.A.; Shchetinin, O.I.

    1979-01-01

    A design of a position-sensitive neutron counter is given in which ionizing events are positioned along the length of the counter on the basis of time shift between signals propagating towards both ends of the counter. The propagation velocity decreases due to the use of a spiral cathode which, together with an external grounded frame, constitutes an electromagnetic delay line. The counter frame is made of a steel tube 200 mm long and 32 mm in diameter. The spiral cathode is a single-layer solenoid, 27.5 mm in internal diameter, which is made of a copper wire. The counter filled with 3 He (1200 torr) and Kr (750 torr) mixture, its efficiency of thermal neutron detection is 48% for the 3 He(n,p) 2 H reaction. An evaluated spatial resolution is 5 mm. Total delay time for the above design of the counter is 280 ns

  16. Clinical evaluation of neodymium-iron-boron (Ne2Fe14B) rare earth magnets in the treatment of mid line diastemas

    Science.gov (United States)

    Manoj-Kumar, Mitta; Gowri-Sankar, Singaraju; Chaitanya, Nellore; Vivek-Reddy, Ganugapanta; Venkatesh, Nettam

    2016-01-01

    Background To evaluate the closure of midline diastema using the Neodymium-Iron-Boron magnets and to compare the treatment duration of midline diastemas with the use of magnets compared to regular orthodontic treatment. Material and Methods Thirty patients with age group 12 to 30 years with the midline diastema ranging from 0.5 to 3mm were selected. These patients were divided into two groups. Diastema closure in one group was accomplished by conventional method, in other group was done with Ne2Fe14B magnets. These magnets were fitted to the labial surfaces of the maxillary central incisors such a way that the opposite poles of the magnets face each other. At each appointment, study models and radiographs were taken for study subjects and the midline diastema was measured using digital vernier calipers on the study models obtained. Descriptive statistics carried out using Paired t-test. Results Subjects treated with Ne2Fe14B magnets showed a significant difference compared to fixed orthodontic appliance subjects with respect to time of closure, rate of space closure and incisal inclination. Significant difference between 2 groups with reduction of 64.6 days in time to diastema closure in subjects treated with Ne2Fe14B magnets (Pclosure of mid line diastema in less duration of time. Key words:Midline diastema, Ne2Fe14B magnets, rare earth magnets, space closure. PMID:27034757

  17. Lattice dynamics of α boron and of boron carbide

    International Nuclear Information System (INIS)

    Vast, N.

    1999-01-01

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

  18. Crystalline boron nitride aerogels

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-12-12

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

  19. An approach to on-line electrospray mass spectrometric detection of polypeptide antibiotics of enramycin for high-speed counter-current chromatographic separation.

    Science.gov (United States)

    Inoue, Koichi; Hattori, Yasuko; Hino, Tomoaki; Oka, Hisao

    2010-04-06

    In the field of pharmaceutical and biomedical analysis of peptides, a rapid on-line detection and identification for a methodology have been required for the discovery of new biological active products. In this study, a high-speed counter-current chromatography with electrospray mass spectrometry (HSCCC/ESI-MS) was developed for the on-line detection and purification of polypeptide antibiotics of enramycin-A and -B. The analytes were purified on HSCCC model CCC-1000 (multi-layer coil planet centrifuge) with a volatile solvent of two-phase system composed of n-butanol/hexane/0.05% aqueous trifluoroacetic acid solution (43/7/50, V/V/V), and detected on an LCMS-2010EV quadrupole mass spectrometer fitted with an ESI source system in positive ionization following scan mode (m/z 100-2000). The HSCCC/ESI-MS peaks indicated that enramycin-A (major m/z 786 [M+3H](3+) and minor m/z 1179 [M+2H](2+)) and enramycin-B (major m/z 791 [M+3H](3+) and minor m/z 1185 [M+2H](2+)) have the peak resolution value of 2.9 from 15mg of loaded enramycin powder. The HSCCC collected amounts of the peak fractions were additionally 4.3mg (enramycin-A), and 5.9mg (enramycin-B), respectively. These purified substances were analyzed by LC/ESI-MS with scan positive mode. Based on the LC/ESI-MS chromatograms and spectra of the fractions, enramycin-A and -B were estimated to be over 95% purity. The overall results indicate that this approach of HSCCC/ESI-MS is a powerful technique for the purification and identification of bioactive peptides. Copyright 2009 Elsevier B.V. All rights reserved.

  20. Screening of Wheat Genotypes for Boron Efficiency in Bangladesh

    Science.gov (United States)

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

  1. A γ-ray telescope for on-line measurements of low boron concentrations in a head-phantom for BNCT

    International Nuclear Information System (INIS)

    Verbakel, W.F.A.R.

    1997-02-01

    In Boron Neutron Capture Therapy the 10 B(n, α) 7 Li reaction is used to create a tumour destructing field of high LET (Linear Energy Transfer) particles. The therapy requires a high boron concentration in the tumour and a low boron concentration in the healthy tissue. The boron neutron capture reaction is accompanied by the emission of a photon of energy 478 keV. It is investigated whether measuring of these photons can serve as a tool to determine the boron concentration during therapy in the tumour as well as in the healthy tissue. Such a measurement is complicated by the presence of a large background photon field. To study the feasibility, an experimental configuration has been designed at a test facility of the Low Flux Reactor (LFR). The LFR provides an epithermal neutron beam for irradiation of a head phantom which simulates a human head with a tumour. This paper shows that the reconstruction of the position and the size of the tumour as well as the ratio of the boron concentrations appeared to be possible. In a second stage is shown that these measurements can be expanded to experiments with the therapy neutron beam of the High Flux Reactor. (orig.)

  2. Body counter

    International Nuclear Information System (INIS)

    Koeppe, P.

    1975-01-01

    The paper gives a survey on some applications of the whole body counter in clinical practice and a critical study of its application as a routine testing method. Remarks on the necessary precautions are followed by a more detailed discussion of the determination of the natural potassium content, the iron metabolism, the vitamin B12 test, investigations of the metabolism of the bone using 47 Ca and 85 Sr, investigations with iodine and iodine-labelled substances, clearance investigations (in particular the 51 Cr EDTA clearance test), as well as the possibilities of neutron activation in vivo. (ORU/AK) [de

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

    International Nuclear Information System (INIS)

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

    1986-01-01

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

  4. Scintillation Counters

    Science.gov (United States)

    Bell, Zane W.

    Scintillators find wide use in radiation detection as the detecting medium for gamma/X-rays, and charged and neutral particles. Since the first notice in 1895 by Roentgen of the production of light by X-rays on a barium platinocyanide screen, and Thomas Edison's work over the following 2 years resulting in the discovery of calcium tungstate as a superior fluoroscopy screen, much research and experimentation have been undertaken to discover and elucidate the properties of new scintillators. Scintillators with high density and high atomic number are prized for the detection of gamma rays above 1 MeV; lower atomic number, lower-density materials find use for detecting beta particles and heavy charged particles; hydrogenous scintillators find use in fast-neutron detection; and boron-, lithium-, and gadolinium-containing scintillators are used for slow-neutron detection. This chapter provides the practitioner with an overview of the general characteristics of scintillators, including the variation of probability of interaction with density and atomic number, the characteristics of the light pulse, a list and characteristics of commonly available scintillators and their approximate cost, and recommendations regarding the choice of material for a few specific applications. This chapter does not pretend to present an exhaustive list of scintillators and applications.

  5. Cell diameter measurements obtained with a handheld cell counter could be used as a surrogate marker of G2/M arrest and apoptosis in colon cancer cell lines exposed to SN-38

    International Nuclear Information System (INIS)

    Tahara, Makiko; Inoue, Takeshi; Miyakura, Yasuyuki; Horie, Hisanaga; Yasuda, Yoshikazu; Fujii, Hirofumi; Kotake, Kenjiro; Sugano, Kokichi

    2013-01-01

    Highlights: •Chemo-sensitivity to SN-38 was assayed by the automated cell counter. •Colon cancer cell line, HCT116 cells were more sensitive to SN-38 than HT29 cells. •Increase of cell size reflects G2/M arrest. •Appearance of small particles indicates cell apoptosis. -- Abstract: In vitro assessment of chemosensitivity are important for experiments evaluating cancer therapies. The Scepter 2.0 cell counter, an automated handheld device based on the Coulter principle of impedance-based particle detection, enables the accurate discrimination of cell populations according to cell size and volume. In this study, the effects of SN-38, the active metabolite of irinotecan, on the colon cancer cell lines HCT116 and HT29 were evaluated using this device. The cell count data obtained with the Scepter counter were compared with those obtained with the 3 H-thymidine uptake assay, which has been used to measure cell proliferation in many previous studies. In addition, we examined whether the changes in the size distributions of these cells reflected alterations in the frequency of cell cycle arrest and/or apoptosis induced by SN-38 treatment. In our experiments using the Scepter 2.0 cell counter, the cell counts were demonstrated to be accurate and reproducible measure and alterations of cell diameter reflected G2/M cell cycle arrest and apoptosis. Our data show that easy-to-use cell counting tools can be utilized to evaluate the cell-killing effects of novel treatments on cancer cells in vitro

  6. Boron nitride composites

    Science.gov (United States)

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

    2017-02-21

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

  7. Boron Nitride Nanotubes

    Science.gov (United States)

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

    2012-01-01

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

  8. Methods of forming boron nitride

    Science.gov (United States)

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

    2015-03-03

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

  9. Distributed performance counters

    Science.gov (United States)

    Davis, Kristan D; Evans, Kahn C; Gara, Alan; Satterfield, David L

    2013-11-26

    A plurality of first performance counter modules is coupled to a plurality of processing cores. The plurality of first performance counter modules is operable to collect performance data associated with the plurality of processing cores respectively. A plurality of second performance counter modules are coupled to a plurality of L2 cache units, and the plurality of second performance counter modules are operable to collect performance data associated with the plurality of L2 cache units respectively. A central performance counter module may be operable to coordinate counter data from the plurality of first performance counter modules and the plurality of second performance modules, the a central performance counter module, the plurality of first performance counter modules, and the plurality of second performance counter modules connected by a daisy chain connection.

  10. Feasibility study of SMART core with soluble boron

    International Nuclear Information System (INIS)

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

    2000-11-01

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

  11. Boron nitride converted carbon fiber

    Science.gov (United States)

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

    2016-04-05

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

  12. Development and application of a new in-line coupling of a miniaturized boronate affinity monolithic column with capillary zone electrophoresis for the selective enrichment and analysis of cis-diol-containing compounds.

    Science.gov (United States)

    Espina-Benitez, Maria Betzabeth; Randon, Jérôme; Demesmay, Claire; Dugas, Vincent

    2017-04-21

    An integrated, miniaturized and fully automated system was developed for the analysis (preconcentration/purification, separation and detection) of cis-diol containing molecules in complex matrices. This innovative in-line coupling system was achieved via the in-situ and localized synthesis of a short segment of silica-based monolith at the inlet of a 75-μm inner diameter fused silica capillary. The monolithic segment was locally functionalized with an acrylamide derivative of phenylboronic acid by free radical photopolymerization within 10min of irradiation time. Efficiency of the photopolymerization reaction was followed by frontal affinity chromatography of 1,2-dihydroxybenzene (catechol) as cis-diol model solute. An active-site amount of 0.43nmolcm -1 (9.8nmolμL -1 ) of phenylboronic acid moieties was obtained, with a K d value of about 290μM close to reported value for the phenyl boronate-catechol complex. The optimal conditions of use of the miniaturized boronate affinity monolithic column (μBAMC) were determined and adapted to the in-line coupling with capillary electrophoresis. Catechol was specifically preconcentrated in a pH 8.5 phosphate buffer/MeOH (80/20, v/v) mixture. A volume up to 20 times the monolith volume can be percolated with a quantitative recovery yield. Three catecholamines were purified, preconcentrated and in-line separated. Elution from the μBAMC was performed with a small plug of acidic solution, allowing field amplified sample stacking of solutes within the plug before their in-line electrophoretic separation at pH 8.75. This unique in-line coupling was successfully used for the fully automated analysis of catecholamines neurotransmitters in urine samples, highlighting the purification efficiency of the μBAMC and the potential of such a fully integrated approach. In addition to the low sample volume required (less than 2μL), the limits of detection (LOD) accomplished with this coupling were estimated at 9.0, 9.5 and 4.8ngmL -1

  13. Scintillation counter, segmented shield

    International Nuclear Information System (INIS)

    Olson, R.E.; Thumim, A.D.

    1975-01-01

    A scintillation counter, particularly for counting gamma ray photons, includes a massive lead radiation shield surrounding a sample-receiving zone. The shield is disassembleable into a plurality of segments to allow facile installation and removal of a photomultiplier tube assembly, the segments being so constructed as to prevent straight-line access of external radiation through the shield into radiation-responsive areas. Provisions are made for accurately aligning the photomultiplier tube with respect to one or more sample-transmitting bores extending through the shield to the sample receiving zone. A sample elevator, used in transporting samples into the zone, is designed to provide a maximum gamma-receiving aspect to maximize the gamma detecting efficiency. (U.S.)

  14. Whole Body Counters (rev.)

    Energy Technology Data Exchange (ETDEWEB)

    Woodburn, John H. [Walter Johnson High School, Rockville, MD; Lengemann, Frederick W. [Cornell University

    1967-01-01

    Whole body counters are radiation detecting and measuring instruments that provide information about the human body. This booklet describes different whole body counters, scientific principles that are applied to their design, and ways they are used.

  15. On-line purity monitoring in high-speed counter-current chromatography: application of HSCCC-HPLC-DAD for the preparation of 5-HMF, neomangiferin and mangiferin from Anemarrhena asphodeloides Bunge.

    Science.gov (United States)

    Zhou, Tingting; Zhu, Zhenyu; Wang, Chen; Fan, Guorong; Peng, Jinyong; Chai, Yifeng; Wu, Yutian

    2007-05-09

    An efficient on-line purity monitoring strategy based on on-line coupling of high-speed counter-current chromatography (HSCCC) with high-performance liquid chromatography-diode array detection (HPLC-DAD) was successfully applied for the first time to the isolation and purification of 5-hydroxymethyl-furancarboxaldehyde (5-HMF), mangiferin and neomangiferin from the Chinese medicinal plant Anemarrhena asphodeloides Bunge, a plant used in the traditional Chinese medicine. The introduction of on-line purity monitoring in HSCCC has greatly improved the efficiency of this technique by overcoming the drawbacks of post-purification sample handling in HSCCC isolation. The effluent from the outlet of HSCCC was split into two parts, and one was collected, while the other was introduced directly through a switch valve into a HPLC-DAD system for purity monitoring. Using this method the desired fractions with high purities could be collected. From 600 mg partially purified extract, 165.6 mg neomangiferin and 292.8 mg mangiferin with purities of 98.9 and 99.5%, respectively, were obtained with a two-phase solvent system composed of n-butanol-water (1:1, v/v) by increasing the flow-rate of the mobile phase stepwise from 1.0 to 2.2 ml min(-1) after 210 min. A 17.1mg 5-HMF with purity of 96.6% was also isolated for the first time.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-15

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

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

    Science.gov (United States)

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

    2010-01-01

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

  18. LINES

    Directory of Open Access Journals (Sweden)

    Minas Bakalchev

    2015-10-01

    Full Text Available The perception of elements in a system often creates their interdependence, interconditionality, and suppression. The lines from a basic geometrical element have become the model of a reductive world based on isolation according to certain criteria such as function, structure, and social organization. Their traces are experienced in the contemporary world as fragments or ruins of a system of domination of an assumed hierarchical unity. How can one release oneself from such dependence or determinism? How can the lines become less “systematic” and forms more autonomous, and less reductive? How is a form released from modernistic determinism on the new controversial ground? How can these elements or forms of representation become forms of action in the present complex world? In this paper, the meaning of lines through the ideas of Le Corbusier, Leonidov, Picasso, and Hitchcock is presented. Spatial research was made through a series of examples arising from the projects of the architectural studio “Residential Transformations”, which was a backbone for mapping the possibilities ranging from playfulness to exactness, as tactics of transformation in the different contexts of the contemporary world.

  19. The first CEDAR counter

    CERN Multimedia

    CERN PhotoLab

    1976-01-01

    The first differential Cerenkov counter with chromatic corrections (called CEDAR) successfully tested at the PS in July 75. These counters were used in the SPS hadronic beams for particle identification. Some of the eight photomultipliers can be seen: they receive the light reflected back through the annular diaphragm. René Maleyran stands on the left.

  20. Anticoincidence scintillation counter

    CERN Multimedia

    CERN PhotoLab

    1966-01-01

    This anticoincidence scintillation counter will be mounted in a hydrogen target vessel to be used in a measurement of the .beta. parameter in the .LAMBDA0. decay. The geometry of the counter optimizes light collection in the central part where a scintillation disk of variable thickness can be fitted.

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

    International Nuclear Information System (INIS)

    Lang, F.M.; Finck, C.

    1956-01-01

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

  2. Separation and purification of bovine serum albumin binders from Fructus polygoni orientalis using off-line two-dimensional complexation high-speed counter-current chromatography target-guided by ligand fishing.

    Science.gov (United States)

    Liu, Qi; Shi, Shuyun; Liu, Liangliang; Yang, Hua; Su, Wen; Chen, Xiaoqing

    2013-08-23

    In this study, off-line two-dimensional (2D) complexation high speed counter-current chromatography (HSCCC) was developed for the separation of bovine serum albumin (BSA) binders from the ethyl acetate extract of Fructus polygoni orientalis. Target-guided strategy of BSA functionalized iron oxide magnetic nanoparticles coupled with high performance liquid chromatography-tandem mass spectrometry ((BSA-Fe3O4 MNPs)-HPLC-MS/MS) experiment was proposed. In the orthogonal separation system, a Normal-Phase HSCCC with 0.01mol/L copper ion as complexation agent in the aqueous phase was employed for the first dimension and Recycling HSCCC, Reverse-Phase HSCCC with 0.1mol/L copper ion were used for the second dimension in parallel. Including two pairs of cis-trans isomers, seven BSA binders including 3,5,7-Trihydroxychromone (1), taxifolin (2), N-cis-paprazine (3), N-cis-feruloyltyramine (4), N-trans-paprazine (5), N-trans-feruloyltyramine (6) and an unidentified compound (7) were obtained. The purities of these seven compounds were all over 95.0% as determined by HPLC. The complexation HSCCC behaviors of seven compounds were also investigated by studying their relationship with copper ion. Results showed that the combinative method using (BSA-Fe3O4 MNPs)-HPLC and HSCCC is a quick, efficient, and reproductive technique to isolate potentially bioactive compounds from the complex mixture system of natural products. And the usage of off-line 2D-HSCCC and introduction of chelating metal ion into solvent system are effective ways to implement HSCCC separations in complex samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Kinetics of chemical vapor deposition of boron on molybdenum

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  4. Spectrographic determination of traces of boron in steels

    International Nuclear Information System (INIS)

    Alduan, F.A.; Roca, M.

    1976-01-01

    A spectrographic method has been developed to determine quantitatively boron in steels in the 0.5 to 250 ppm concentration range. The samples are dissolved in acids and transformed into oxides, avoiding boron losses by the addition of mannitol. For the fluoride evolution of boron in the dc arc the following compounds have been considered: CuF 2 , LiF, NaF, and SrF 2 . CuF 2 , at a concentration of 10%, provides the highest line-to-background intensity ratio. An arc current of 5 amperes eliminates the interference from iron spectrum on the most sensitive boron line - B 2497.7 A. Variations in chromium and nickel contents have no effect on the analytical results. (author)

  5. International perspectives on countering school segregation

    NARCIS (Netherlands)

    Bakker, J.T.A.; Denessen, E.J.P.G.; Peters, T.J.M.; Walraven, G.

    2010-01-01

    School segregation is perceived as an unyielding problem worldwide, which is manifest along both ethnic and socio-economic lines. With this edited volume we aim to share information about school segregation and policies focused on countering school segregation from an international perspective. Many

  6. Portable multiplicity counter

    Science.gov (United States)

    Newell, Matthew R [Los Alamos, NM; Jones, David Carl [Los Alamos, NM

    2009-09-01

    A portable multiplicity counter has signal input circuitry, processing circuitry and a user/computer interface disposed in a housing. The processing circuitry, which can comprise a microcontroller integrated circuit operably coupled to shift register circuitry implemented in a field programmable gate array, is configured to be operable via the user/computer interface to count input signal pluses receivable at said signal input circuitry and record time correlations thereof in a total counting mode, coincidence counting mode and/or a multiplicity counting mode. The user/computer interface can be for example an LCD display/keypad and/or a USB interface. The counter can include a battery pack for powering the counter and low/high voltage power supplies for biasing external detectors so that the counter can be configured as a hand-held device for counting neutron events.

  7. A large Cerenkov counter

    CERN Multimedia

    1981-01-01

    The photo shows the vertex Cerenkov counter C0 back side (with 12 mirrors) of the NA9 experiment. On foreground are members of the team (CERN and Wuppertal Uni), Salvo .., Manfred Poetsch, ..., Jocelyn Thadome, Helmut Braun, Heiner Brueck.

  8. Counter-cryptanalysis

    NARCIS (Netherlands)

    M.M.J. Stevens (Marc); R. Canetti; J.A. Garay

    2013-01-01

    textabstractWe introduce \\emph{counter-cryptanalysis} as a new paradigm for strengthening weak cryptographic primitives against cryptanalytic attacks. Redesigning a weak primitive to more strongly resist cryptanalytic techniques will unavoidably break backwards compatibility. Instead,

  9. Shower counter resolution scaling

    International Nuclear Information System (INIS)

    Kirk, T.B.W.

    1991-01-01

    The EM shower counter for the SDC detector has a resolution expression containing two stochastic terms plus a constant term. Recent measurements clarifying the sources of these terms are presented here. 3 refs., 4 figs

  10. A position sensitive parallel plate avalanche counter

    International Nuclear Information System (INIS)

    Lombardi, M.; Tan Jilian; Potenza, R.; D'amico, V.

    1986-01-01

    A position sensitive parallel plate avalanche counter with a distributed constant delay-line-cathode (PSAC) is described. The strips formed on the printed board were served as the cathode and the delay line for readout of signals. The detector (PSAC) was operated in isobutane gas at the pressure range from 10 to 20 torr. The position resolution is better than 1 mm and the time resolution is about 350 ps, for 252 Cf fission-spectrum source

  11. Boronated liposome development and evaluation

    International Nuclear Information System (INIS)

    Hawthorne, M.F.

    1995-01-01

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

  12. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

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

  13. Analysis of counter-rotating wind turbines

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Zakkam, Vinod Arun Kumar; Sørensen, Jens Nørkær

    2007-01-01

    This paper presents a study on the performance of a wind turbine with two counter-rotating (CRWT) rotors. The characteristics of the two counter-rotating rotors are on a 3-bladed Nordtank 500 kW rotor. The analysis has been carried out by using an Actuator Line technique implemented in the Navier......-Stokes code EllipSys3D. The analysis shows that the Annual Energy Production can be increased to about 43.5 %, as compared to a wind turbine with a single rotor. In order to determine the optimal settings of the CRWT turbine, parameters such as distance between two rotors and rotational speed have been...

  14. Enrichment of boron 10

    International Nuclear Information System (INIS)

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

    1990-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-06-06

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

  16. Gas proportional scintillation counter

    International Nuclear Information System (INIS)

    Iguchi, Tetsuo; Nakazawa, Masaharu; Sekiguchi, Akira

    1980-01-01

    As the trial in the first stage of utilizing recoil helium for the measurement of 2 - 14 MeV neutron spectra in the simulated blanket for a nuclear fusion reactor, the He-Xe system gas proportional scintillation counter (GPSC) has been manufactured for trial, giving consideration to the advantages of gas scintillators and further to improve the energy resolution. In GPSC, delayed secondary scintillation pulses are produced, and its amplitude gives the energy resolution the adverse effect. Thus, in order to improve the energy resolution, it is desirable to realize such geometry of proportional counters that the electric field in the vicinity of center wire is sufficiently intense to induce the secondary excitation or ionization. The counters of such construction are called GPSC, in which the actual energy resolution can be improved according to the secondary scintillation pulses without losing the fast primary scintillation pulses useful for fast coincidence technique. The experimental results and the consideration on them are described. As compared with proportional counters, GPSC can give large output pulses even at low voltage, improve the energy resolution greatly as compared with ordinary gas scintillators, and measure the time data by the primary scintillation and the energy data based on the secondary scintillation simultaneously. However, it is likely to be affected by gas impurities more than proportional counters, and inferior in the reproducibility and stability of measurement. (Wakatsuki, Y.)

  17. Effect of Boronization on Ohmic Plasmas in NSTX

    International Nuclear Information System (INIS)

    Skinner, C.H.; Kugel, H.; Maingi, R.; Wampler, W.R.; Blanchard, W.; Bell, M.; Bell, R.; LeBlanc, B.; Gates, D.; Kaye, S.; LaMarche, P.; Menard, J.; Mueller, D.; Na, H.K.; Nishino, N.; Paul, S.; Sabbagh, S.; Soukhanovskii, V.

    2001-01-01

    Boronization of the National Spherical Torus Experiment (NSTX) has enabled access to higher density, higher confinement plasmas. A glow discharge with 4 mTorr helium and 10% deuterated trimethyl boron deposited 1.7 g of boron on the plasma facing surfaces. Ion beam analysis of witness coupons showed a B+C areal density of 10 to the 18 (B+C) cm to the -2 corresponding to a film thickness of 100 nm. Subsequent ohmic discharges showed oxygen emission lines reduced by x15, carbon emission reduced by two and copper reduced to undetectable levels. After boronization, the plasma current flattop time increased by 70% enabling access to higher density, higher confinement plasmas

  18. Lattice dynamics of {alpha} boron and of boron carbide; Proprietes vibrationnelles du bore {alpha} et du carbure de bore

    Energy Technology Data Exchange (ETDEWEB)

    Vast, N

    1999-07-01

    The atomic structure and the lattice dynamics of {alpha} boron and of B{sub 4}C boron carbide have been studied by Density Functional Theory (D.F.T.) and Density Functional Perturbation Theory (D.F.P.T.). The bulk moduli of the unit-cell and of the icosahedron have been investigated, and the equation of state at zero temperature has been determined. In {alpha} boron, Raman diffusion and infrared absorption have been studied under pressure, and the theoretical and experimental Grueneisen coefficients have been compared. In boron carbide, inspection of the theoretical and experimental vibrational spectra has led to the determination of the atomic structure of B{sub 4}C. Finally, the effects of isotopic disorder have been modeled by an exact method beyond the mean-field approximation, and the effects onto the Raman lines has been investigated. The method has been applied to isotopic alloys of diamond and germanium. (author)

  19. X-ray proportional counter with neon for analysis and control of light impurities

    International Nuclear Information System (INIS)

    Petrascu, H.; Petrascu, M.; Apostolescu, S.; Caragheorgheopol, G.

    1992-01-01

    To manufacture a high-resolution proportional counter sensitive to the 2.3 keV sulfur X-rays, a neon counter prototype was developed. The window of this counter consisted of beryllium, 15 mm in diameter and 0.15 mm thick. The counter was filled with neon at the pressure of 1 bar. To realize this prototype a technology work out for xenon proportional counters was used. The resolution of the counter at the K α sulfur line turned out to be 0.58 keV, better than the resolution of a xenon counter, which in term presented itself a very good resolution (0.85 keV) at the K α Mn line. This counter will be used for controlling sulfur technology processes and sulfur contaminations. (Author)

  20. Multichannel strobed photon counter

    International Nuclear Information System (INIS)

    Ganichev, V.A.; Elkin, O.K.; Zajdel', I.N.; Kozlov, V.A.; Lyapunov, G.M.; Malinovskij, A.L.; Ryabov, E.A.; Sil'kis, Eh.G.

    1987-01-01

    A multichannel strobed photon counter operating in the visible spectrum range is developed on the basis of luminescence amplifier with a microchannel plate and LI-706 supervidicon. The pulses overvoltaged supply mode of a microchannel plate has brought about amplification necessary for input into plateau of the counting characteristics and photoacceptor strobing in the nanosecond (140 ns) range. Device noises are practically completely determined by noises in luminescence amplifier photocathode. the above multichannel counter has a durable stability of parameters, electronic system simplicity and small dimensions of the photoacceptor

  1. An efficient anticoincidence counter

    CERN Multimedia

    1977-01-01

    This scintillation counter (about 25 cm diameter) was prepared at CERN for an experiment at the Saclay 600 MeV electron linac studying molecular processes originated in liquid hydrogen by muons. The counter is meant to surround the target and detect charged particles emerging from the hydrogen. The experiment was a CERN-Saclay collaboration which used the linac so as to take advantage of the time structure of the electron beam(see CERN Courier Sep 1977 and J. Bardin et al. Phys. Lett. B104 (1981) 320)

  2. Process for microwave sintering boron carbide

    Science.gov (United States)

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

    1993-10-12

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

  3. Bright prospects for boron

    NARCIS (Netherlands)

    Nanver, L.; Wassink, J.

    2012-01-01

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

  4. Methods of producing continuous boron carbide fibers

    Science.gov (United States)

    Garnier, John E.; Griffith, George W.

    2015-12-01

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

  5. Electromagnetically Operated Counter

    Science.gov (United States)

    Goldberg, H D; Goldberg, M I

    1951-12-18

    An electromagnetically operated counter wherein signals to be counted are applied to cause stepwise rotation of a rotatable element which is connected to a suitable register. The mechanism involved consists of a rotatable armature having three spaced cores of magnetic material and a pair of diametrically opposed electromagnets with a suitable pulsing circuit to actuate the magnets.

  6. Counter radicalization development assistance

    OpenAIRE

    van Hippel, Karin

    2006-01-01

    The paper reviews current research and practice and recommends strategies for development agencies working in the Arab and Muslim world. It builds on the basic assumption that the realization of the Millennium Development Goals will be vital to reduce support for terrorism in the long term. Within this overall framework, emphasis is placed on particular programs that could be specifically applied to counter radicalization.

  7. Irradiated fuel bundle counter

    International Nuclear Information System (INIS)

    Campbell, J.W.; Todd, J.L.

    1975-01-01

    The design of a prototype safeguards instrument for determining the number of irradiated fuel assemblies leaving an on-power refueled reactor is described. Design details include radiation detection techniques, data processing and display, unattended operation capabilities and data security methods. Development and operating history of the bundle counter is reported. (U.S.)

  8. Scintillation counter: photomultiplier tube alignment

    International Nuclear Information System (INIS)

    Olson, R.E.

    1975-01-01

    A scintillation counter, particularly for counting gamma ray photons, includes a massive lead radiation shield surrounding a sample-receiving zone. The shield is disassembleable into a plurality of segments to allow facile installation and removal of a photomultiplier tube assembly, the segments being so constructed as to prevent straight-line access of external radiation through the shield into the sample receiving zone. Provisions are made for accurately aligning the photomultiplier tube with respect to one or more sample-transmitting bores extending through the shield to the sample receiving zone. A sample elevator, used in transporting samples into the zone, is designed to provide a maximum gamma-receiving aspect to maximize the gamma detecting efficiency. (auth)

  9. Scintillation counter, maximum gamma aspect

    International Nuclear Information System (INIS)

    Thumim, A.D.

    1975-01-01

    A scintillation counter, particularly for counting gamma ray photons, includes a massive lead radiation shield surrounding a sample-receiving zone. The shield is disassembleable into a plurality of segments to allow facile installation and removal of a photomultiplier tube assembly, the segments being so constructed as to prevent straight-line access of external radiation through the shield into radiation-responsive areas. Provisions are made for accurately aligning the photomultiplier tube with respect to one or more sample-transmitting bores extending through the shield to the sample receiving zone. A sample elevator, used in transporting samples into the zone, is designed to provide a maximum gamma-receiving aspect to maximize the gamma detecting efficiency. (U.S.)

  10. Microdosimetry for Boron Neutron Capture Therapy

    International Nuclear Information System (INIS)

    Maughan, R.L.; Kota, C.

    2000-01-01

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

  11. Over-the-Counter Medicines

    Science.gov (United States)

    Over-the-counter (OTC) medicines are drugs you can buy without a prescription. Some OTC medicines relieve aches, pains and itches. ... medicine is safe enough to sell over-the-counter. Taking OTC medicines still has risks. Some interact ...

  12. Proportional counter end effects eliminator

    International Nuclear Information System (INIS)

    Meekins, J.F.

    1976-01-01

    An improved gas-filled proportional counter which includes a resistor network connected between the anode and cathode at the ends of the counter in order to eliminate ''end effects'' is described. 3 Claims, 2 Drawing Figures

  13. In vitro and in vivo studies in boron neutron capture therapy of malignant melanoma

    International Nuclear Information System (INIS)

    Allen, B.J.

    1982-01-01

    A multidisciplinary research project in boron neutron capture therapy of malignant melanoma is under consideration by the Australian Atomic Energy Commission. This paper reviews the biochemistry of melanoma and the properties of some melanoma-affined radiopharmaceuticals and their boron analogues. Human cell lines are being used for in vitro tests of uptake and incorporation of some of these compounds, and selected lines will then be implanted in nude mice for in vivo distribution studies. The fidelity of human melanoma xenografts in nude mice has been well studied, and results are reviewed in this paper. Boron concentration will be measured directly by plasma arc emission spectroscopy or liquid scintillation counting with 14 C-labelled boron analogues. Track-etch techniques will be used for the microscopic determination of boron in tumor sections. Neutron irradiation and radiobiology experiments are outlined

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

    OpenAIRE

    Chaoyu He; J. X. Zhong

    2013-01-01

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

  15. Fundamentals of gas counters

    International Nuclear Information System (INIS)

    Bateman, J.E.

    1994-01-01

    The operation of gas counters used for detecting radiation is explained in terms of the four fundamental physical processes which govern their operation. These are 1) conversion of neutral radiation into charged particles, 2) ionization of the host gas by a fast charge particle 3) transport of the gas ions to the electrodes and 4) amplification of the electrons in a region of enhanced electric field. Practical implications of these are illustrated. (UK)

  16. Fivefold twinned boron carbide nanowires.

    Science.gov (United States)

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

    2009-09-09

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

  17. Fiber-Optic Monitoring System of Particle Counters

    Directory of Open Access Journals (Sweden)

    A. A. Titov

    2016-01-01

    Full Text Available The article considers development of a fiber-optic system to monitor the counters of particles. Presently, optical counters of particles, which are often arranged at considerable distance from each other, are used to study the saltation phenomenon. For monitoring the counters, can be used electric communication lines.However, it complicates and raises the price of system Therefore, we offered a fiber-optic system and the counter of particles, free from these shortcomings. The difference between the offered counter of particles and the known one is that the input of radiation to the counter and the output of radiation scattering on particles are made by the optical fibers, and direct radiation is entered the optical fiber rather than is delayed by a light trap and can be used for lighting the other counters thereby allowing to use their connection in series.The work involved a choice of the quartz multimode optical fiber for communication, defining the optical fiber and lenses parameters of the counter of particles, and a selection of the radiation source and the photo-detector.Using the theory of light diffraction on a particle, a measuring range of the particle sizes has been determined. The system speed has been estimated, and it has been shown that a range of communication can reach 200km.It should be noted that modulation noise of counters of particles connected in series have the impact on the useful signal. To assess the extent of this influence we have developed a calculation procedure to illustrate that with ten counters connected in series this influence on the signal-to-noise ratio will be insignificant.Thus, it has been shown that the offered fiber-optic system can be used for monitoring the counters of particles across the desertified territories. 

  18. Orientation-dependent effects of EPR-measurements on β-rhombohedral boron

    International Nuclear Information System (INIS)

    Siems, C.D.; Geist, D.

    1976-01-01

    EPR studies on β-rhombohedral boron have been reported by several authors. Two EPR-lines with the same g-value have been found by measurements with and without illumination. The microwave frequency used was 9 GHz, as far as is known. In this paper EPR-measurements at 35 GHz on β-rhombohedral boron single crystals are reported. The investigations concerning the 'dark EPR-line' were made at 300 K. (Auth.)

  19. A fundamental study of industrial boron carbide

    International Nuclear Information System (INIS)

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

    1983-09-01

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

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

    Science.gov (United States)

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

    2015-04-01

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

  1. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

    Raman spectroscopic examination was carried out to study the nature of bonding and the allotropic form of boron obtained after electrodeposition. The results obtained from transmission electron microscopy showed the presence of nanocrystallites embedded in an amorphous mass of boron. Raman microscopic studies ...

  2. Countering antivaccination attitudes.

    Science.gov (United States)

    Horne, Zachary; Powell, Derek; Hummel, John E; Holyoak, Keith J

    2015-08-18

    Three times as many cases of measles were reported in the United States in 2014 as in 2013. The reemergence of measles has been linked to a dangerous trend: parents refusing vaccinations for their children. Efforts have been made to counter people's antivaccination attitudes by providing scientific evidence refuting vaccination myths, but these interventions have proven ineffective. This study shows that highlighting factual information about the dangers of communicable diseases can positively impact people's attitudes to vaccination. This method outperformed alternative interventions aimed at undercutting vaccination myths.

  3. Microchip Coulter particle counter

    DEFF Research Database (Denmark)

    Larsen, Ulrik Darling; Blankenstein, Gert; Branebjerg, J.

    1997-01-01

    This paper presents a micro device employing the Coulter principle for counting and sizing of living cells and particles in liquid suspension. The microchip Coulter particle counter (μCPC) has been employed in a planar silicon structure covered with glass, which enables detailed observation during...... and short contact time of liquids in microchannels. As a result, the width of the liquids can be controlled without knowing the actual flow rates. The μCPC has been fabricated by standard microfabrication techniques, including RIE, wet silicon etching, metalization and anodic bonding...

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

    Science.gov (United States)

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

    2014-04-01

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

  5. Functionalized boron nitride nanotubes

    Science.gov (United States)

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

    2014-04-22

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

  6. Boron Activated Neutron Thermometer

    Energy Technology Data Exchange (ETDEWEB)

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

    1952-01-09

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

  7. Boron atom reactions

    International Nuclear Information System (INIS)

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

    1982-01-01

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

  8. Performance of a Boron-Coated-Straw-Based HLNCC for International Safeguards Applications

    Energy Technology Data Exchange (ETDEWEB)

    Simone, Angela T. [ORNL; Croft, Stephen [ORNL; McElroy, Robert Dennis [ORNL; Sun, Liang [Proportional Technologies Inc.; Hayward, Jason P. [ORNL

    2017-08-01

    3He gas has been used in various scientific and security applications for decades, but it is now in short supply. Alternatives to 3He detectors are currently being integrated and tested in neutron coincidence counter designs, of a type which are widely used in nuclear safeguards for nuclear materials assay. A boron-coated-straw-based design, similar to the High-Level Neutron Coincidence Counter-II, was built by Proportional Technologies Inc., and has been tested by the Oak Ridge National Laboratory (ORNL) at both the JRC in Ispra and ORNL. Characterization measurements, along with nondestructive assays of various plutonium samples, have been conducted to determine the performance of this coincidence counter replacement in comparison with other similar counters. This paper presents results of these measurements.

  9. Development of simple neutron counters

    International Nuclear Information System (INIS)

    Satoh, S.; Hirota, K.

    2014-01-01

    Position sensitive neutron detectors are used for neutron scattering, neutron imaging, and neutron radiography. Developments in neutron detectors are mainly focused on spatial resolution and high counting rate in these fields. After the Fukushima nuclear power plant disaster, many simple radiation counters are now marketed in Japan and are useful for estimating the radiation level. However, no simple, equivalent device exists for neutron measurements. In this work, we have developed simple neutron counters (LiM counter and HeM counter) with the following features. In the LiM counter, a 6 Li glass scintillator is employed as a neutron converter for a large dynamic range. A silicon photon MPPC (multi-pixel photon counter) detector is used separately for photon counting, thus reducing the size of the device. In the HeM counter, a 3 He neutron detector is employed. Both counters employ a pulse-height analysis function for ensuring reliable data and display the pulse-height distribution on a graphical liquid crystal display (G-LCD). The LiM counter can be used for about 6 h using a battery, operating at 264 mA and 5.1 V. (author)

  10. Boron-Based Nanostructures, Stability, Functionality and Synthetic Routes

    Energy Technology Data Exchange (ETDEWEB)

    Yakobson, Boris I. [Rice Univ., Houston, TX (United States); Ajayan, Pulickel M. [Rice Univ., Houston, TX (United States)

    2017-08-04

    Boron (B) is one of the most intriguing elements not only because of its position between metals and nonmetals in periodic table but also because of its ability to form an enormous number of allotropes. Apart from several bulk three-dimensional (3D) phases, boron can form 0D clusters, 1D nanotubes and nanowires, and 2D layers. In particular, boron sheets of monoatomic thickness have raised interest as a potential new 2D-material and as a (conceptual) precursor, for example, so-called α-sheets, from which other boron structures - fullerene cages and tubes - might be constructed. In fact, a number of planar B clusters up to tens of atoms, found in experiments, appear as seeds for extended sheets. In this project we developed theoretical methods to guide synthesis, have successfully identified the material substrates (Ag, Au, Cu) to producing the pure boron layers, and further even predicted what atomistic structures should be expected. These guidelines have successfully led to discoveries in several labs and now have grown into an active line of research worldwide.

  11. 60 years Geiger-Mueller counter - 40 years scintillation counter

    International Nuclear Information System (INIS)

    Stolz, W.; Herforth, L.

    1988-01-01

    This review is devoted to two anniversaries that of the invention of the Geiger-Mueller counter sixty years ago and that of the development of the scintillation counter forty years ago. Besides the history described the importance at the present time is emphasized. The advances made in further improvement of these detectors are considered. 99 refs. (author)

  12. Space and power efficient hybrid counters array

    Science.gov (United States)

    Gara, Alan G [Mount Kisco, NY; Salapura, Valentina [Chappaqua, NY

    2009-05-12

    A hybrid counter array device for counting events. The hybrid counter array includes a first counter portion comprising N counter devices, each counter device for receiving signals representing occurrences of events from an event source and providing a first count value corresponding to a lower order bits of the hybrid counter array. The hybrid counter array includes a second counter portion comprising a memory array device having N addressable memory locations in correspondence with the N counter devices, each addressable memory location for storing a second count value representing higher order bits of the hybrid counter array. A control device monitors each of the N counter devices of the first counter portion and initiates updating a value of a corresponding second count value stored at the corresponding addressable memory location in the second counter portion. Thus, a combination of the first and second count values provide an instantaneous measure of number of events received.

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

    Science.gov (United States)

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

    2013-11-06

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

  14. Silica aerogel Cerenkov counter

    International Nuclear Information System (INIS)

    Yasumi, S.; Masaike, A.; Yamamoto, A.; Yoshimura, Y.; Kawai, H.

    1984-03-01

    In order to obtain silica aerogel radiators of good quality, the prescription used by Saclay group has been developed. We have done several experiments using beams from KEK.PS to test the performance of a Cerenkov counter with aerogel modules produced in KEK. It turned out that these modules had excellent quality. The production rate of silica aerogel in KEK is 15 -- 20 litres a week. Silica aerogel modules of 20 x 10 x 3 cm 3 having the refractive index of 1.058 are successfully being used by Kyoto University group in the KEK experiment E92 (Σ). Methodes to produce silica aerogel with higher refractive index than 1.06 has been investigated both by heating an module with the refractive index of 1.06 and by hydrolyzing tetraethyl silicate. (author)

  15. ELECTRICAL PULSE COUNTER APPARATUS

    Science.gov (United States)

    Kaufman, W.M.; Jeeves, T.A.

    1962-09-01

    A progressive electrical pulse counter circuit rs designed for the counting of a chain of input pulses. The circuit employs a series of direct connected bistable counting stages simultaneously pulsed by each input pulse and a delay means connected between each of the stages. Each bistable stage has two d-c operative states, which stage, when in its initial state, prevents the next succeeding stage from changing its condition when the latter stage is pulsed. Since the delay circuits between the stages prevents the immediate decay of the d-c state of each stage when the stages are pulsed, only one stage will change its state for each input pulse, thereby providing progressive stage-by-stage counting. (AEC)

  16. Boron isotopes and groundwater pollution

    International Nuclear Information System (INIS)

    Vengosh, A.

    1999-01-01

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

  17. 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.

  18. Nothing Boring About Boron

    Science.gov (United States)

    Pizzorno, Lara

    2015-01-01

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

  19. Hign sensitivity neutron rem counter

    International Nuclear Information System (INIS)

    Jiang Jinling; Wen Youqin; Xie Jianlun; Chen Changmao

    1986-01-01

    The constructions of two counters (NR1 and NR2) and their characteristics are presented. In the region from thermal energy to 17 MeV, the detectable dose equivalent values range from 10 -4 to 10 2 mrem.h -1 and the neutron dose equivalent sensitivity is approximately 140 cps/mrem.h -1 for the counter NR1; the detectable dose equivalent values range from 10 -4 to 65 mrem.h -1 and the dose equivalent sensitivity approx.= 209 cps/mrem.h -1 for the counter NR2 in the energy range from thermal energy to 7 MeV. Compared with the rem counter SIUDSVIK 2202D, their dose equivalent readings are consistent within +- 10% when neutron beams are approximatly perpendicular to the counter axis

  20. Modeling of boron control during power transients in a pressurized water reactor

    International Nuclear Information System (INIS)

    Mathieu, P.; Distexhe, E.

    1986-01-01

    Accurate control instructions in a reactor control aid computer are included in order to realize the boron makeup throughput, which is required to obtain the boron concentration in the primary coolant loop, predicted by a neutronic code. A modeling of the transfer function between the makeup and the primary loop is proposed. The chemical and volumetric control system, the pressurizer, and the primary loop are modeled as instantaneous diffusion cells. The pipes are modeled as time lag lines. The model provides the unstationary boron distributions in the different elements of the setup. A numerical code is developed to calculate the time evolutions of the makeup throughput during power transients

  1. Nano boron nitride flatland.

    Science.gov (United States)

    Pakdel, Amir; Bando, Yoshio; Golberg, Dmitri

    2014-02-07

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

  2. Analysis of boron dilution in a four-loop PWR

    Energy Technology Data Exchange (ETDEWEB)

    Sun, J.G.; Sha, W.T. [Argonne National Lab., IL (United States)

    1995-03-01

    Thermal mixing and boron dilution in a pressurized water reactor were analyzed with COMMIX codes. The reactor system was the four-loop Zion reactor. Two boron dilution scenarios were analyzed. In the first scenario, the plant is in cold shutdown and the reactor coolant system has just been filled after maintenance on the steam generators. To flush the air out of the steam generator tubes, a reactor coolant pump (RCP) is started, with the water in the pump suction line devoid of boron and at the same temperature as the coolant in the system. In the second scenario, the plant is at hot standby and the reactor coolant system has been heated to operating temperature after a long outage. It is assumed that an RCP is started, with the pump suction line filled with cold unborated water, forcing a slug of diluted coolant down the downcomer and subsequently through the reactor core. The subsequent transient thermal mixing and boron dilution that would occur in the reactor system is simulated for these two scenarios. The reactivity insertion rate and the total reactivity are evaluated and a sensitivity study is performed to assess the accuracy of the numerical modeling of the geometry of the reactor coolant system.

  3. Analysis of boron dilution in a four-loop PWR

    Energy Technology Data Exchange (ETDEWEB)

    Sun, J.G.; Sha, W.T.

    1995-12-31

    Thermal mixing and boron dilution in a pressurized water reactor were analyzed with COMMIX codes. The reactor system was the four loop Zion reactor. Two boron dilution scenarios were analyzed. In the first scenario, the plant is in cold shutdown and the reactor coolant system has just been filled after maintenance on the steam generators. To flush the air out of the steam generator tubes, a reactor coolant pump (RCP) is started, with the water in the pump suction line devoid of boron and at the same temperature as the coolant in the system. In the second scenario, the plant is at hot standby and the reactor coolant system has been heated up to operating temperature after a long outage. It is assumed that an RCP is started, with the pump suction line filled with cold unborated water, forcing a slug of diluted coolant down the downcomer and subsequently through the reactor core. The subsequent transient thermal mixing and boron dilution that would occur in the reactor system is simulated for these two scenarios. The reactivity insertion rate and the total reactivity are evaluated.

  4. Metal interactions with boron clusters

    International Nuclear Information System (INIS)

    Grimes, R.N.

    1982-01-01

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

  5. 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.

  6. A prototype threshold Cherenkov counter for DIRAC

    CERN Document Server

    Bragadireanu, M; Cima, E; Dulach, B; Gianotti, P; Guaraldo, C; Iliescu, M A; Lanaro, A; Levi-Sandri, P; Petrascu, C; Girolami, B; Groza, L; Kulikov, A; Kuptsov, A; Topilin, N; Trusov, S

    1999-01-01

    We have designed, built and tested a gas threshold Cherenkov counter as prototype for a larger counter foreseen for use in the DIRAC experiment, at CERN. We describe the performances of the counter on a test beam.

  7. DIRECT COUPLED PROGRESSIVE STAGE PULSE COUNTER APPARATUS

    Science.gov (United States)

    Kaufman, W.M.

    1962-08-14

    A progressive electrical pulse counter circuit was designed for the counting of a chain of input pulses of random width and/or frequency. The circuit employs an odd and even pulse input line alternately connected to a series of directly connected bistable counting stages. Each bistable stage has two d-c operative states which stage, when in its rnrtial state, prevents the next succeeding stage from changing its condition when the latter stage is pulsed. Since only altennate stages are pulsed for each incoming pulse, only one stage will change its state for each input pulse thereby providing prog essive stage by stage counting. (AEC)

  8. Determination of the boron content in polyethylene samples using the reactor Orphée

    CERN Document Server

    Gunsing, F; Aberle, O

    2017-01-01

    The boron content of two unknown types of polyethylene has been determined relative to a known reference type. Samples of polyethylene, including a known boron-less one, were irradiated with thermal neutrons at the reactor Orphée at Saclay in France. Prompt gamma rays were measured with a CeBr$_3$ detector and the intensity of the 478~keV line from $^{10}${B}(n,$\\alpha_1\\gamma$)$^{7}{Li*} was extracted.

  9. 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.

  10. A portable neutron coincidence counter

    Energy Technology Data Exchange (ETDEWEB)

    Peurrung, A.J.; Bowyer, S.M.; Craig, R.A.; Dudder, G.B.; Knopf, M.A.; Panisko, M.E.; Reeder, P.L.; Stromswold, D.C.; Sunberg, D.S.

    1996-11-01

    Pacific Northwest National Laboratory has designed and constructed a prototype portable neutron coincidence counter intended for use in a variety of applications, such as the verification and inspection of weapons components, safety measurements for novel and challenging situations, portable portal deployment to prevent the transportation of fissile materials, uranium enrichment measurements in hard-to-reach locations, waste assays for objects that cannot be measured by existing measurement systems, and decontamination and decommissioning. The counting system weighs less than 40 kg and is composed of parts each weighing no more than 5 kg. In addition, the counter`s design is sufficiently flexible to allow rapid, reliable assembly around containers of nearly arbitrary size and shape. The counter is able to discern the presence of 1 kg of weapons-grade plutonium within an ALR-8 (30-gal drum) in roughly 100 seconds and 10 g in roughly 1000 seconds. The counter`s electronics are also designed for maximum adaptability, allowing operation under a wide variety of circumstances, including exposure to gamma-ray fields of 1 R/h. This report provides a detailed review of the design and construction process. Finally, preliminary experimental measurements that confirm the performance capabilities of this counter are discussed. 6 refs., 18 figs., 3 tabs.

  11. A high-efficiency neutron coincidence counter for small samples

    International Nuclear Information System (INIS)

    Miller, M.C.; Menlove, H.O.; Russo, P.A.

    1991-01-01

    The inventory sample coincidence counter (INVS) has been modified to enhance its performance. The new design is suitable for use with a glove box sample-well (in-line application) as well as for use in the standard at-line mode. The counter has been redesigned to count more efficiently and be less sensitive to variations in sample position. These factors lead to a higher degree of precision and accuracy in a given counting period and allow for the practical use of the INVS counter with gamma-ray isotopics to obtain a plutonium assay independent of operator declarations and time-consuming chemicals analysis. A calculation study was performed using the Los Alamos transport code MCNP to optimize the design parameters. 5 refs., 7 figs., 8 tabs

  12. Spent fuel counter

    International Nuclear Information System (INIS)

    Drayer, D.D.

    1988-09-01

    In many cases the IAEA must inspect spent fuel shipping casks before they leave facilities. Similarly, inspections may be required at the location where a cask is received and unloaded. In order to reduce the number of inspections required, it would be desirable to develop a system to count spent fuel assemblies as they are loaded or removed from shipping casks. This report discusses several methods which potentially could be used for performing this function. A concept for a Spent Fuel Counter System is proposed which uses a Laser Surveillance System (LASSY), Cerenkov Viewing Device (CVD), and Modular Integrated Video System (MIVS), all coupled together. In the proposed system, LASSY would provide an indication that an object is being placed into or removed from the cask, the CVD would be used to determine if the object has the radiation characteristics of a spent fuel assembly, and the MIVS would record the information. The system may need to be designed so that the operator could determine that it was operating correctly during the loading operations. This would help prevent anomalies from occurring which could only be resolved through reverification measures. Before such a system could be implemented testing would be necessary to determine that the individual components would each work adequately in this application. The issues of reliability, intrusiveness, and cask sealing should also be addressed before a development program is undertaken. 12 refs., 1 fig

  13. Space-charge effects of the proportional counters in a multiple-ionization chamber

    International Nuclear Information System (INIS)

    Mang, M.

    1993-01-01

    At the ALADIN spectrometer of the GSI in october 1991 for the first time the new multiple ionization chamber was applied, in the two anode planes of which are additional multiwire-proportional counters. The proportional counters are required in order to make the detection of light fragments (Z 4 gold projectiles per second by these positive space charges the homogeneous electric field of the MUSIC is disturbed. This effect is especially strong in the beam plane. As consequence of the space charge additionally electrons are focused on the proportional counter so that their amplitudes in dependence on the beam intensity increase up to the 2.5-fold. Furthermore the y coordinate is falsified, because the electrons are diverted to the medium plane. On the measurement of the x coordinate this diversion has with maximally 0.1% only a small influence. These space-charge effects can be qualitatively described by a schematic model, which assumes a stationary positive space charge. Additionally for the proportional counters, which are not in the beam plane, their resolution was determined. In these counters the space-charge effects are small, because essentially fewer particles are registrated than in the medium MWPC's. By this charges of fragments with Z<10 could be separated. The charge resolution amounted at lithium 0.8 charge units. The position resolution of the proportional counters in y direction was determined to less than 8 mm. The detection probability of the fragments amounts for lithium 90% and from boron all fragments are detected

  14. Position sensitive proportional counters as focal plane detectors

    International Nuclear Information System (INIS)

    Ford, J.L.C. Jr.

    1979-01-01

    The rise time and charge division techniques for position decoding with RC-line proportional counters are reviewed. The advantages that these detectors offer as focal plane counters for nuclear spectroscopy performed with magnetic spectrographs are discussed. The theory of operation of proportional counters as position sensing devices is summarized, as well as practical aspects affecting their application. Factors limiting the position and energy resolutions obtainable with a focal plane proportional counter are evaluated and measured position and energy loss values are presented for comparison. Detector systems capable of the multiparameter measurements required for particle identification, background suppression and ray-tracing are described in order to illustrate the wide applicability of proportional counters within complex focal plane systems. Examples of the use of these counters other than with magnetic spectrographs are given in order to demonstrate their usefulness in not only nuclear physics but also in fields such as solid state physics, biology, and medicine. The influence of the new focal plane detector systems on future magnetic spectrograph designs is discussed. (Auth.)

  15. In-vivo radiation counter

    International Nuclear Information System (INIS)

    Pollard, D.E.

    1983-01-01

    This patent specification describes a radiation counter utilizing at least one detector for sensing radiation from a living body. The radiation counter also includes an aperture for forming a corridor between the body and the detector. A shield outside the corridor prevents passage of background radiation through the corridor and gaining access to the detector. The counter also includes a device for isolating a selected portion of the body from the corridor such that radiation counting is restricted to a region of the body through a separate detector. The corridor formation permits a user to stand in an upright position while the detector and detectors are able to separately monitor different sections of the body. The radiation counter overcomes the problem of obtaining accurate and quick measurements or radiation doses sustained by a large group of persons. (author)

  16. The escape gated proportional counter

    International Nuclear Information System (INIS)

    Bibbo, G.; Sanford, P.W.

    1981-01-01

    Proportional counters, designed to detect hard X-rays, are generally filled with Xe or Kr or a mixture of Xe and Kr. In a large multichamber proportional counter the K-fluorescent radiation of these gases, which escapes the cell of origin, but is absorbed in other cells of the counter, provides an additional signal. A coincidence technique, which makes use of this signal to reduce the charged particle background and to correct the energy spectrum for the escape peak, has been evaluated. The detector has an improved energy resolution over that of the conventional proportional counter and preliminary results indicate that a reduction in the background by a factor of about 1000 can be obtained. Its combined properties of very efficient background reduction and improved energy resolution make this type of instrument most suitable for spectroscopic studies of astronomical X-ray sources in the energy range of 15-100 keV. (orig.)

  17. High-speed parallel counter

    International Nuclear Information System (INIS)

    Gus'kov, B.N.; Kalinnikov, V.A.; Krastev, V.R.; Maksimov, A.N.; Nikityuk, N.M.

    1985-01-01

    This paper describes a high-speed parallel counter that contains 31 inputs and 15 outputs and is implemented by integrated circuits of series 500. The counter is designed for fast sampling of events according to the number of particles that pass simultaneously through the hodoscopic plane of the detector. The minimum delay of the output signals relative to the input is 43 nsec. The duration of the output signals can be varied from 75 to 120 nsec

  18. Measurement of the STS-6 counter efficiency to gamma radiation

    International Nuclear Information System (INIS)

    Dyatlov, V.D.

    1981-01-01

    Gamma radiation measurements by the STS-6 proportional counters in bad geometry at 0.1-2 MeV γ-radiation are presented to evaluating the efficiency of measurement of the decay product radiation. This efficiency is reduced to ''good'' geometry by introduction of an effective space angle with account of γ-radiation losses and absorption of compton electrons in the material of the counter walls. The counter efficiency for γ-radiation photons of the given energy was determined as a ratio of difference of the real counting rate and the background to the number of photons in the counter active volume. It ws considered in this case, that the active volume of the counter is such a volume, where the secondary charged particles are detected with 100; probability. The experiments in which the counter was placed at different distances from the source were conducted for identification of this volume. At 17 mm distance of the counter from the source the effective space angle of the counter constituted 0.36 sr and its dependence on the energy did not exceed 2%. The error of efficiency determination comprised the error of radiation dose determination, error of measuring the real counting rate, background counting rate with account of the error of ''dead'' time determination as well as the error of identification of the effective space angle and the error of calculating partial efficiencies for certain lines occurring at the decay of the given nuclide. The total error with account of the errors of determining the half-decay periods constituted 3% [ru

  19. Practical techniques on radiation counters

    International Nuclear Information System (INIS)

    Sanada, Junpei

    1977-01-01

    The operating mechanisms of and the practical techniques on what are called ''counters'' among radiation detectors have already been described in detail in many literatures. The author describes his experiences about the fundamental problems and practical use that have not been clear yet unexpectedly. In core wire counters, it is important to produce incident radiation tracks in parallel as far as possible with the wire or with the wire plane in multi-wire counters. The electron avalanche in the non-uniform field in the vicinity of a wire is supposed to be generated like the shape of heart from the experimental results. In the needle counters having been used for a long time, the plateau of counting becomes considerably wider than wire counters, and the background count is less structurally. Therefore the needle counters are suitable for low background counting. When fabricating the silicon surface barrier semiconductor detector, the etching of the just inside of wax cover tends to proceed fast so that the central portion is separated in spite of the expectation that only the central surface is etched. If gold grains are put on and permitted to roll over the surface of a silicon wafer by the combination of rotation and reciprocating motion as the wafer is kept horizontally, the etching of the central surface can be successfully done because it proceeds 10 times as fast as the peripheral part. It proceeds about 3 times as fast by employing glass beads instead of gold grains. (Wakatsuki, Y.)

  20. Future boronated molecules for neutron capture therapy

    International Nuclear Information System (INIS)

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

    1986-01-01

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

  1. Compression and Associated Properties of Boron Carbide

    Science.gov (United States)

    2008-12-01

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

  2. Lattice vibrations in α-boron

    International Nuclear Information System (INIS)

    Richter, W.

    1976-01-01

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

  3. Synthesis of oligomeric boron-containing phospolyols

    International Nuclear Information System (INIS)

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

    2006-01-01

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

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

    OpenAIRE

    He, Chaoyu; Zhong, Jianxin

    2013-01-01

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

  5. Single photon emitters in boron nitride: More than a supplementary material

    Science.gov (United States)

    Koperski, M.; Nogajewski, K.; Potemski, M.

    2018-03-01

    We present comprehensive optical studies of recently discovered single photon sources in boron nitride, which appear in form of narrow lines emitting centres. Here, we aim to compactly characterise their basic optical properties, including the demonstration of several novel findings, in order to inspire discussion about their origin and utility. Initial inspection reveals the presence of narrow emission lines in boron nitride powder and exfoliated flakes of hexagonal boron nitride deposited on Si/SiO2 substrates. Generally rather stable, the boron nitride emitters constitute a good quality visible light source. However, as briefly discussed, certain specimens reveal a peculiar type of blinking effects, which are likely related to existence of meta-stable electronic states. More advanced characterisation of representative stable emitting centres uncovers a strong dependence of the emission intensity on the energy and polarisation of excitation. On this basis, we speculate that rather strict excitation selectivity is an important factor determining the character of the emission spectra, which allows the observation of single and well-isolated emitters. Finally, we investigate the properties of the emitting centres in varying external conditions. Quite surprisingly, it is found that the application of a magnetic field introduces no change in the emission spectra of boron nitride emitters. Further analysis of the impact of temperature on the emission spectra and the features seen in second-order correlation functions is used to provide an assessment of the potential functionality of boron nitride emitters as single photon sources capable of room temperature operation.

  6. Mapping boron in silicon solar cells using electron energy-loss spectroscopy

    DEFF Research Database (Denmark)

    by focused ion beam milling in order to map the boron distribution across a 200-nm-thick n-p amorphous silicon junction using energy-filtered TEM and EELS spectrum acquisition. EELS line scans are used to detect boron concentrations as low as 10^20cm-3. We also use monochromated EELS to measure changes......Amorphous silicon solar cells typically consist of stacked layers deposited on plastic or metallic substrates making sample preparation for transmission electron microscopy (TEM) difficult. The amorphous silicon layer - the active part of the solar cell - is sandwiched between 10-nm-thick n- and p......-doped layers. The typical boron concentration in the p-doped layer is ~10^21cm -3 and should not exceed 1017cm-3 in the neighbouring intrinsic (i) layer [1], where it acts as a charge recombination centre and decreases the internal electric field [2]. The detection of low boron concentrations with high spatial...

  7. Boron steel. I Part. Preparation

    International Nuclear Information System (INIS)

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

    1960-01-01

    With the advent of the first nuclear reactors arise the need for control rods and shielding duties for some types of radiations. One of the materials used for this purpose has been the high boron steel. This paper describes the melting and casting procedures employed for the production, at laboratory scale, of steels with Boron content ranging from 1 to 4 per cent, as well as the metallographic and X-Ray techniques used for the identification of the present phases. The electrolytic technique employed for the isolation of the Fe 2 B phase and its subsequent X-Ray identification has proved to be satisfactory. (Author) 11 refs

  8. Thermal conductivity of boron carbides

    Science.gov (United States)

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

    1985-01-01

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

  9. New Icosahedral Boron Carbide Semiconductors

    Science.gov (United States)

    Echeverria Mora, Elena Maria

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

  10. Chemical separation of boron isotopes

    International Nuclear Information System (INIS)

    Palko, A.A.

    1978-06-01

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

  11. Chemical separation of boron isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Palko, A.A.

    1978-06-01

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

  12. Boron cycling in subduction zones

    OpenAIRE

    Palmer, Martin R.

    2017-01-01

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

  13. Explosion-proof scintillation counter

    International Nuclear Information System (INIS)

    Opitts, P.; Borkert, R.

    1979-01-01

    It is noted that measuring devices used in the research works conducted with the help of radioactive isotopes on the chemical industry installations dangerous from the point of view of explosions, especially on the installations of the petrochemistry industry, must not limit the exploitation safety of these installations. The said especially concerns with the Geiger-Mueller type counters and scintillation detectors, located immediately in the places of measurements on the installations and supplied by high voltage power supply. It has been shown that electronic circuits for the detector's signals processing and obtaining working voltages can be located out of the explosive dangerous premices, for example, in the car trailer. Description is given of the device, with the help of which explosion safety is provided for the serially produced scintillation counter with forced ventilation (counter of the VA-S-50 type). Due to this device application, the exploitation parameters of the counter do not go down and there is no need for any changes in its design. Description is given of the device for external power supply and control of the counter which can swich off the power supply in the case of an accident, dangerous from the point of view of violation of the explosion safety conditions. The device is described for providing service to 10 measuring chanels, mounted on the car trailer [ru

  14. Determination of boron in the waters of Troia by inductively coupled plasma-atomic emission spectrometry (ICP-AES

    Directory of Open Access Journals (Sweden)

    HASAN OZCAN

    2005-10-01

    Full Text Available The inductively coupled plasma-atomic emission spectrometry method (ICP-EAS is proposed for the determination of boron in Troia water sources. In this study, boron samples were taken from 25 different locations during November 2002 and May 2003. The 249.773 nm boron emmision line was not affected by the samplematrix. The boron content was determined without further pretreatment of samples proposed ICP-AES method. An analysis of a given sample was completed in about 15 min. The determined boron concentrations in surface and ground water sources were between 0.00444–1.11200mgl-1. Inorder to compare the results obtained by the proposed method, selected water samples were also analysed titrimetically. Pearson correlation coefficient analysis showed that there is a close relationship between the ICP-AES and the titrimetric method and the determination coefficient (R2 was calculated to be 91.34 %.

  15. Boron Nitride Nanoribbons from Exfoliation of Boron Nitride Nanotubes

    Science.gov (United States)

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

    2017-01-01

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

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

    Indian Academy of Sciences (India)

    A ceramic precursor, prepared by condensation reaction from poly(vinyl alcohol) (PVA) and boric acid (H3BO3) in 1:1, 2:1 and 4:1 molar ratios, was synthesized as low temperature synthesis route for boron nitride ceramic. Samples were pyrolyzed at 850°C in nitrogen atmosphere followed by characterization using Fourier ...

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

    Science.gov (United States)

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

    2008-10-01

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

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

    International Nuclear Information System (INIS)

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

    1998-01-01

    The authors have investigated the diffusion enhancement mechanism of BED (boron enhanced diffusion), wherein the boron diffusivity is enhanced three to four times over the equilibrium diffusivity at 1,050 C in the proximity of a silicon layer containing a high boron concentration. It is shown that BED is associated with the formation of a fine-grain polycrystalline silicon boride phase within an initially amorphous Si layer having a high B concentration. For 0.5 keV B + , the threshold implantation dose which leads to BED lies between 3 x 10 14 and of 1 x 10 15 /cm -2 . Formation of the shallowest possible junctions by 0.5 keV B + requires that the implant dose be kept lower than this threshold

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

    Science.gov (United States)

    Kurachi, Ikuo; Yoshioka, Kentaro

    2015-09-01

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

  20. Evaluation of Aluminum-Boron Carbide Neutron Absorbing Materials for Interim Storage of Used Nuclear Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lumin [Univ. of Michigan, Ann Arbor, MI (United States). Department of Nuclear Engineering and Radiological Science; Wierschke, Jonathan Brett [Univ. of Michigan, Ann Arbor, MI (United States). Department of Nuclear Engineering and Radiological Science

    2015-04-08

    The objective of this work was to understand the corrosion behavior of Boral® and Bortec® neutron absorbers over long-term deployment in a used nuclear fuel dry cask storage environment. Corrosion effects were accelerated by flowing humidified argon through an autoclave at temperatures up to 570°C. Test results show little corrosion of the aluminum matrix but that boron is leaching out of the samples. Initial tests performed at 400 and 570°C were hampered by reduced flow caused by the rapid build-up of solid deposits in the outlet lines. Analysis of the deposits by XRD shows that the deposits are comprised of boron trioxide and sassolite (H3BO3). The collection of boron- containing compounds in the outlet lines indicated that boron was being released from the samples. Observation of the exposed samples using SEM and optical microscopy show the growth of new phases in the samples. These phases were most prominent in Bortec® samples exposed at 570°C. Samples of Boral® exposed at 570°C showed minimal new phase formation but showed nearly the complete loss of boron carbide particles. Boron carbide loss was also significant in Boral samples at 400°C. However, at 400°C phases similar to those found in Bortec® were observed. The rapid loss of the boron carbide particles in the Boral® is suspected to inhibit the formation of the new secondary phases. However, Material samples in an actual dry cask environment would be exposed to temperatures closer to 300°C and less water than the lowest test. The results from this study conclude that at the temperature and humidity levels present in a dry cask environment, corrosion and boron leaching will have no effect on the performance of Boral® and Bortec® to maintain criticality control.

  1. Boron removal from wastewater using adsorbents.

    Science.gov (United States)

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

    2007-01-01

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

  2. Plea and counter-plea

    International Nuclear Information System (INIS)

    1979-06-01

    The bulk of papers written during the hearing 'Plea and counter-plea', the so-called 'Gorleben hearing', which was held from 28th March until 3rd April 1979, comprises ca. 4,200 pages. It consists of the written comments put forward by the critics of nuclear energy, the minutes of the hearing as well as the supplementary statements of the counter-critics. This report is trying to confront those essential objections made by the critics which put in doubt the feasibility of a fuel-cycle centre with regard to safety engineering with the facts which are considered correct from the view of the DWK. The oral and written explanations of the counter-critics are particularly referred to in this debate. (orig./HP) [de

  3. 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.

  4. Boron isotopes in geothermal systems

    International Nuclear Information System (INIS)

    Aggarwal, J.

    1997-01-01

    Boron is a highly mobile element and during water-rock reactions, boron is leached out of rocks with no apparent fractionation. In geothermal systems where the water recharging the systems are meteoric in origin, the B isotope ratio of the geothermal fluid reflects the B isotope ratio of the rocks. Seawater has a distinctive B isotope ratio and where seawater recharges the geothermal system, the B isotope ratio of the geothermal system reflects the mixing of rock derived B and seawater derived B. Any deviations of the actual B isotope ratio of a mixture reflects subtle differences in the water-rock ratios in the cold downwelling limb of the hydrothermal system. This paper will present data from a variety of different geothermal systems, including New Zealand; Iceland; Yellowston, USA; Ibusuki, Japan to show the range in B isotope ratios in active geothermal systems. Some of these systems show well defined mixing trends between seawater and the host rocks, whilst others show the boron isotope ratios of the host rock only. In geothermal systems containing high amounts of CO 2 boron isotope ratios from a volatile B source can also be inferred. (auth)

  5. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

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

  6. Preparation process of boron nitride

    International Nuclear Information System (INIS)

    Mignani, G.; Ardaud, P.

    1990-01-01

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

  7. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

    Structural characterization of electrodeposited boron was carried out by using transmission electron microscopy and Raman spectroscopy. Electron diffraction and phase contrast imaging were carried out by using transmission electron microscopy. Phase identification was done based on the analysis of electron diffraction ...

  8. Method of separating boron isotopes

    Science.gov (United States)

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

    1984-01-01

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

  9. Prevention of uncontrolled boron dilution

    International Nuclear Information System (INIS)

    Sere, J. L.

    1997-01-01

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

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

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  11. Design and performance study of the TOP counter

    International Nuclear Information System (INIS)

    Matsuoka, Kodai

    2013-01-01

    A novel RICH detector called TOP counter has been developed for particle identification in Belle II. It measures the time of propagation (TOP) of Cherenkov photons traveling in the quartz radiator with micro-channel-plate photomultiplier tubes (MCP-PMTs) with a precision of 50 ps. A prototype TOP counter was tested with the 1.2 GeV/c electron beam in the Laser Electron Photon beam line at SPring-8 (LEPS). The TOP distribution was obtained as expected after taking into account the dependence of the MCP-PMT quantum efficiency on light incidence angle and polarization. In this paper, the key features of the TOP counter design and the beam test results are presented. -- Highlights: •The TOP counter has been developed for particle identification in Belle II. •A time of propagation (TOP) of Cherenkov light in the quartz radiator is measured. •Cherenkov light is detected by the MCP-PMTs with a resolution of about 40 ps. •A prototype TOP counter was tested with the 1.2 GeV/c electron beam at LEPS. •The TOP distribution measured in the beam test agrees with the expectation

  12. Dimensions of Counter-Narratives

    DEFF Research Database (Denmark)

    2019-01-01

    The book welcomes proposals for chapter contributions on a wide array of topics related to the narratological notion of counter-narratives. By way of example, the topic has hitherto been treated by disciplines and subjects such as literature studies, organization studies, corporate communication ...

  13. The Eros of Counter Education

    Science.gov (United States)

    Luzon, Pinhas

    2016-01-01

    Erotic Counter Education (ECE) is the educational position of the late Ilan Gur-Ze'ev. In ECE Gur-Ze'ev combines two opposing positions in the philosophy of education, one teleological and anti-utopian, the other teleological and utopian. In light of this unique combination, I ask what mediates between these two poles and suggest that the answer…

  14. The Micro Trench Gas Counter

    International Nuclear Information System (INIS)

    Schmitz, J.

    1991-07-01

    A novel design is presented for a gas avalanche chamber with micro-strip gas readout. While existing gaseous microstrip detectors (Micro-strip Gas Counters, Knife edge chambers) have a minimum anode pitch of the order of 100 μm, the pitch of the discussed Micro Trench Gas Counter goes down to 30-50 μm. This leads to a better position resolution and two track separation, and a higher radiation resistivity. Its efficiency and signal speed are expected to be the same as the Microstrip Gas Counter. The energy resolution of the device is expected to be equal to or better than 10 percent for the 55 Fe peak. Since the anode strip dimensions are larger than those in a MSGC, the device may be not as sensitive to discharges and mechanical damage. In this report production of the device is briefly described, and predictions on its operation are made based on electric field calculations and experience with the Microstrip Gas Counter. The authors restrict themselves to the application in High Energy Physics. (author). 10 refs.; 9 figs

  15. Effects of boron-water on cattle

    Energy Technology Data Exchange (ETDEWEB)

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

    1975-01-01

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

  16. CAMAC differential pulse discriminator-counter

    International Nuclear Information System (INIS)

    Tselikov, N.V.

    1987-01-01

    Differential pulse discriminator-counter for Moessbauer spectrometer is described. Input pulse setting into the channel is performed according to the following algorithm: the pulse is transmitted to the channel depending on the fact whether the preceding pulse has got to the discrimination window or not. The circuit does not contain delay lines, taking into account the delay of a signal from the upper level discriminator in relation to the lower level discriminator signal, which is connected with input pulse rise finite time, which in turn allows one to reduce the discriminator dead time up to the operation time of threshold circuits. The pulse counting rate is 150 MHz, input signal amplitude is ±3 V, dead time is 6 ns, delay time from input to output is 14 ns. The unit is made in CAMAC system

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1987-06-16

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

  18. Antibodies and antiestrogens combined with boron for use in the neutron capture therapy

    International Nuclear Information System (INIS)

    Abraham, R.

    1987-01-01

    The ZR-75-1 cell line developed from a mammary carcinoma was chosen to characterise the binding of antiestrogen U23.469-M to the cell, which was subsequently compared to that of a derivative combined with boron. It was found that the original U23.469-M showed antiestrogenic activity, while this effect was largely abolished after the substance had been modified using b-decachloro-o-carborane. In this study, boron-conjugated antibodies were produced in order to find out whether those modified immunoglobulins would be suitable to bind sufficient quantities of boron to the tumour cells. It was calculated by experts on radiation biology that a minimum of 1000 boron atoms is required for a tumour-specific antibody to be therapeutically effective. When oxidated dextran of a molecular weight of 33 kD was used as a linking molecule, a reproducible method could be developed that permitted more than 1000 boron atoms to be bound per antibody. In one of the monoclonal antibodies tested here a combination with boron could, however, only be achieved at the expense of complete inactivation. A model was developed allowing to significantly increase the number modified antibodies attached to any one tumour cell. The cell binding experiments and radioimmunoassays then carried out were able to show that the number of antibodies bound to tumour cells can be increased to different degrees, depending on the monoclonal antibody used in each case. (orig./MG) [de

  19. Basic Research Needs for Countering Terrorism

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, W.; Michalske, T.; Trewhella, J.; Makowski, L.; Swanson, B.; Colson, S.; Hazen, T.; Roberto, F.; Franz, D.; Resnick, G.; Jacobson, S.; Valdez, J.; Gourley, P.; Tadros, M.; Sigman, M.; Sailor, M.; Ramsey, M.; Smith, B.; Shea, K.; Hrbek, J.; Rodacy, P.; Tevault, D.; Edelstein, N.; Beitz, J.; Burns, C.; Choppin, G.; Clark, S.; Dietz, M.; Rogers, R.; Traina, S.; Baldwin, D.; Thurnauer, M.; Hall, G.; Newman, L.; Miller, D.; Kung, H.; Parkin, D.; Shuh, D.; Shaw, H.; Terminello, L.; Meisel, D.; Blake, D.; Buchanan, M.; Roberto, J.; Colson, S.; Carling, R.; Samara, G.; Sasaki, D.; Pianetta, P.; Faison, B.; Thomassen, D.; Fryberger, T.; Kiernan, G.; Kreisler, M.; Morgan, L.; Hicks, J.; Dehmer, J.; Kerr, L.; Smith, B.; Mays, J.; Clark, S.

    2002-03-01

    To identify connections between technology needs for countering terrorism and underlying science issues and to recommend investment strategies to increase the impact of basic research on efforts to counter terrorism.

  20. Training options for countering nuclear smuggling

    International Nuclear Information System (INIS)

    Ball, D Y; Erickson, S A

    1999-01-01

    The burden of stopping a nuclear smuggling attempt at the border rests most heavily on the front-line customs inspector. He needs to know how to use the technological tools at his disposal, how to discern tell-tale anomalies in export documents and manifests, how to notice psychological signs of a smuggler's tension, and how to search anything that might hide nuclear material. This means that assistance in the counter-nuclear smuggling training of customs officers is one of the most critical areas of help that the United States can provide. This paper discusses the various modes of specialized training, both in the field and in courses, as well as the types of assistance that can be provided. Training for nuclear customs specialists, and supervisors and managers of nuclear smuggling detection systems is also important, and differs from front-line inspector training in several aspects. The limitations of training and technological tools such as expert centers that will overcome these limitations are also discussed. Training assistance planned by DOE/NN-43 to Russia within the Second Line of Defense program is discussed in the light of these options, and future possibilities for such training are projected

  1. The Energy Variation of the Sensitivity of a Polyethylene Moderated BF3 Proportional Counter

    International Nuclear Information System (INIS)

    Fraeki, R.; Leimdoerfer, M.; Malmskog, S.

    1962-11-01

    The variation with neutron energy of the sensitivity of a polyethylene moderated boron counter has been investigated experimentally at 2.3 MeV, 550 keV, 210 keV, 110 keV, 340 eV and 5 eV, and theoretically by the multigroup diffusion method in the same range. Different moderator thicknesses up to 10 cm were considered Results show good agreement between experimental and theoretical sensitivities for the keV and MeV energies, while a discrepancy of the order of a factor 2 at the most is obtained in the eV region

  2. Counter-discourse in Zimbabwean literature

    NARCIS (Netherlands)

    Mangena, Tendai

    2015-01-01

    Counter-Discourse in Zimbabwean Literature is a study of specific aspects of counter-discursive Zimbabwean narratives in English. In discussing the selected texts, my thesis is based on Terdiman’s (1989) the postcolonial concept of counter-discourse. In Zimbabwean literature challenges to a dominant

  3. 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.

  4. Boron removal from geothermal waters by electrocoagulation.

    Science.gov (United States)

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

    2008-05-01

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

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

    Science.gov (United States)

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

    2006-01-01

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

  6. The boron geochemistry of siliceous sponges

    Science.gov (United States)

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

    2009-12-01

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

  7. Mineral resource of the month: boron

    Science.gov (United States)

    Crangle, Robert D.

    2012-01-01

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

  8. 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.

  9. Discharge quenching circuit for counters

    International Nuclear Information System (INIS)

    Karasik, A.S.

    1982-01-01

    A circuit for quenching discharges in gas-discharge detectors with working voltage of 3-5 kV based on transistors operating in the avalanche mode is described. The quenching circuit consists of a coordinating emitter follower, amplifier-shaper for avalanche key cascade control which changes potential on the counter electrodes and a shaper of discharge quenching duration. The emitter follower is assembled according to a widely used flowsheet with two transistors. The circuit permits to obtain a rectangular quenching pulse with front of 100 ns and an amplitude of up to 3.2 kV at duration of 500 μm-8 ms. Application of the quenching circuit described permits to obtain countering characteristics with the slope less than or equal to 0.02%/V and plateau extent greater than or equal to 300 V [ru

  10. Countering 21st Century Threats

    DEFF Research Database (Denmark)

    Scharling Pedersen, Peter; Pillai, Chad M.; Hun, Lee Jae

    2015-01-01

    The United States and its Allies confront an increasingly volatile world where threats range from traditional state-on-state challenges to non-state transnational networks. To successfully combat these 21st Century problems, in an era of resource and geo-political power constraints, the U...... to be addressed in order to successfully conduct IW. As result of researching the issues associated with developing a JIIM approach to IW, the paper makes the following recommendations: • Establishing universally accepted concepts and doctrines for IW, UW, Foreign Internal Defense (FID), Counter Insurgency (COIN......), Counter-Terrorism (CT), and Security and Stability Operations (SSO). • Establishing a construct that allows a strategic Whole-of-Government capacity for operations coordinated by joint interagency task forces. • Continue to developing the Global SOF network. • Increased intelligence sharing in areas...

  11. Countering Islamic Radicalization Indonesian Experiences

    Science.gov (United States)

    2016-02-16

    sense“ among Muslims that Muslim under attack by infidels , and the best way to solve Muslim problems is to apply Sharia as state law, if necessary by...three days the 8 11 income from oil it had taken a year to earn before the embargo and gave the kingdom all the petrodollars it needed to export... infidels ”. From the mid-1980s onward, to counter the Iranian Islamic revolution and Nasser’s Arab Nationalism influence among its Saudi population

  12. Counter support for WA35

    CERN Document Server

    CERN PhotoLab

    1977-01-01

    This assembly was equipped with 78 counters, each consisting of a lucite cone, to produce Cerenkov light, and a CsI scintillator plate of 3 mm thickness glued on the face of the cone. The experiment WA35 was set-up in the s1 beam (West Hall) by the Darmstadt-Heidelberg-Virginia-Warsaw Collaboration to measure angular distributions and multiplicities of pions and recoil protons produced by hadrons interacting in nuclei. (See Annual Report 1976 p. 39)

  13. INTRODUCING OVER THE COUNTER COUNSELING

    Directory of Open Access Journals (Sweden)

    Nataša Bakić-Mirić

    2009-01-01

    Full Text Available A pharmacist in today’s world has a great responsibility – to help and educate patients about diverse ways for effective self-treatment. Whereas self-care is becoming increasingly popular among patients today the availability of over-the-counter medications makes it possible for patients to treat numerous conditions on their own but still under the supervision of a healthcare provider. During the pharmacist-patient encounter, the pharmacist’s obligation is to evaluate the patient’s medical condition, provide proper advice and counsel the patient on the proper course of treatment to be taken. Also by employing effective over the counter (OTC counseling as the most proper means in a pharmacist/patient communication process and, accordingly, rapport building in the OTC area, the pharmacist needs to demonstrate high energy, enthusiasm, respect, empathy, know-how of sensitive intercultural issues alongside personal appearance, body language, eye contact that all together make his/her personal “signature”. Accordingly, apart from patient education, the primary objective of OTC counseling becomes to educate pharmacists on basic principles used in assisting patients in the selection of over-the-counter (OTC products, provide examples of proper communication techniques for effective patient counseling concerning the OTC products (i.e. dosage, administration technique, storage, food and beverage interaction, monitoring etc where the pharmacist plays the key role in helping patients maximize their pharmaceutical care.

  14. 14-channel threshold gas Cerenkov counter

    International Nuclear Information System (INIS)

    Voichishin, M.N.; Devitsin, E.G.; Gus'kov, B.N.; Kapishin, M.N.; Zavertyaev, M.V.; Zinchenko, A.I.

    1985-01-01

    A 14-channel threshold gas Cerenkov counter filled with Freon-12 at a pressure of 1 atm is described. The radiator length is 150 cm. The counter efficiency for protons with a momentum of circa equal to or greater than 30 GeV/c exceeds 98%. The counter is a part of the system for identification of secondary charged particles of the BIS-2 spectrometer of the Institute of HighEnergy Physics. A diagram of the counter and its dimensions is shown. The counter consists of a light- and gasproof housing, a set of focusing mirrors, and a photomultiplier system

  15. Recent advances in gas scintillation proportional counters

    International Nuclear Information System (INIS)

    Palmer, H.E.

    1975-01-01

    Various geometrical configurations for gas scintillation proportional counters have been investigated in order to determine which is best for use in a large volume, high efficiency counter for measuring low energy gamma and x-rays. A xenon filled counter having a rod anode inside a cylindrical cathode appears to provide the best configuration for providing a uniform field and the best resolution over the total volume of the counter. The details of construction and operating characteristics of various shaped counters are described. (U.S.)

  16. Quality control of liquid scintillation counters

    International Nuclear Information System (INIS)

    Jaubert, F.; Tartes, I.; Cassette, P.

    2006-01-01

    Liquid scintillation counting (LSC) is widely used at LNHB for primary standardization of radionuclides (TDCR method), for secondary calibration and also for source stability studies or radioactive purity measurements. A total of five LSC counters are used for these purposes: two locally developed 3-photodetector counters for the implementation of the TDCR method, two Wallac 1414 counters and one Wallac 1220 Quantulus counter. The quality of the LSC measurements relies on the correct operation of these counters and their traceability to the frequency and time units

  17. Reduction of shallow boron and phosphorus diffusion by co-implantation

    Science.gov (United States)

    Vanderpool, Aaron

    Control of Boron and Phosphorus Transient Enhanced Diffusion (TED) is the key to the development of high performance n and p type Ultra Shallow Junctions (USJ). Carbon, Fluorine, and Germanium co-implants can be used to reduce or modify the Boron or Phosphorus Interstitialcy Clusters (BIC or PIC) that drive TED. Substitutional Carbon (Cs) or Fluorine-Vacancy (F-V) clusters do this by consuming the interstitials that drive TED by Carbon Kick-out or F-V annihilation. Germanium does this by inhibiting Interstitialcy formation through local lattice strain. It has been found that certain combinations of these techniques can combine to maximize TED reduction and several of the mechanisms have been characterized. Low energy 5keV Germanium and Carbon have yielded a Boron USJ with a junction depth (xj) of 16.8 nm and a sheet resistance (Rs) of 602 O/□, while 8keV Fluorine and Carbon have formed a Phosphorus USJ with xj = 29.5 nm and Rs ≈ 150 O/□. In addition record levels of Boron TED control have been found using Carbon and 12keV Phosphorus co-implants (xj = 13.3 nm). Record levels of Phosphorus TED control have been found using Carbon and 4keV Boron co-implants (xj = 22.2 nm). In these cases the counter-dopant below the USJ is probably forming PIC or BIC consuming interstitials more efficiently than non-electrical dopants dramatically limiting TED. For Phosphorus USJ there is a strong TED dependence on Boron co-implant energy. Uphill diffusion has been observed if the Phosphorus implant energy is below 3 keV, or without amorphization, and increases as Boron co-implant energy decreases. This work has also found the first experimental evidence of F-V clustering acting to limit TED in USJ by toggling the order of Halo implantation which generates a vacancy distribution. This causes a change in Boron diffusion that is well explained by the lack or presence of the F-V clusters. In addition, Phosphorus TED shows a slight decrease as Fluorine co-implant energy decreases

  18. In vitro and in vivo analysis of boronated porphyrins

    International Nuclear Information System (INIS)

    Edwards, Benjamin; Matthews, Kristin; Hou, Yongjin; Vicente, M.G.H.; Autry-Conwell, Susan; James, Boggan

    2000-01-01

    New series of meso-phenylporphyrins linked through carbon-carbon bonds to nido-carboranyl groups, and containing 26-31% boron by weight, have been reported. Dark toxicity, photo-toxicity, and measurements of uptake and efflux were performed using mouse, rat, and human malignant cell lines. Drug uptake and retention by log phase cells are shown by spectrophotometry (porphyrins) and ICP-MS (boron) of cellular extracts to be concentration and time dependent, and to be influenced by plasma lipoproteins. Plasma pharmacokinetics and tissues biodistribution were studied in adult male Fisher 344 rats with bilateral subcutaneous 9L tumors injected (2.2 ml, 2 mM i.v.) with carboranyl porphyrin solutions. Whole blood, brain, liver, spleen, skin and tumors were collected at 2, 8, 18, 24 and 48 hours post-injection. Blood cells were separated from plasma and stored frozen with the other tissues. Tissue boron content was determined quantitatively by ICP-MS analysis following microwave digestion of carefully weighed samples. (author)

  19. Killing effect of carboranyl uridine on boron neutron capture reaction

    International Nuclear Information System (INIS)

    Takagaki, M.; Oda, Y.; Zhang, Z.

    1994-01-01

    This paper deals with the killing effect of carboranyl uridine (CU) on thermal neutron capture reaction in cultured glioma cell line (C6). The tumoricidal effect of CU for boron neutron capture therapy in the cultured cell system is presented. To assess the uptake of CU, the number of germ cells was determined by comparing protein concentrations of C6 cells in vitro with that of intracranially transplanted C6 tumor cells in vivo. To assess tumoricidal effects of CU, human glioma cells (T98G), containing 25 ppm natural boron of CU, were irradiated with various doses of thermal neutrons at a constant fluence rate. The uptake and killing effects of mercaptoboron and boric acid were also investigated as controls. Subcellular boron concentrations confirmed the selective affinity to the nucleic acid synthesis. CU was found to have an affinity to nucleic acid synthesis and to be accumulated into nucleus of tumor cells. The irradiation dose which yielded 37% survival rate in the case of CU and control were 3.78+12E nvt and 5.80+12E nvt, respectively. The killing effect of CU was slightly higher than that of B-SH or BA. The effective way of CU injection should be further studied to obtain the uniform CU uptake in tumor cells. (N.K.)

  20. Boron-Coated Straw Collar for Uranium Neutron Coincidence Collar Replacement

    International Nuclear Information System (INIS)

    Hu, Jianwei; Croft, Stephen; McElroy, Robert Dennis

    2017-01-01

    The objective of this project was to design and optimize, in simulation space, an active neutron coincidence counter (or collar) using boron-coated straws (BCSs) as a non- 3 He replacement to the Uranium Neutron Coincidence Collar (UNCL). UNCL has been used by the International Atomic Energy Agency (IAEA) and European Atomic Energy Community (Euratom) since the 1980s to verify the 235 U content in fresh light water reactor fuel assemblies for safeguards purposes. This report documents the design and optimization of the BCS collar.

  1. Boron-Coated Straw Collar for Uranium Neutron Coincidence Collar Replacement

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jianwei [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Croft, Stephen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McElroy, Robert Dennis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-01-01

    The objective of this project was to design and optimize, in simulation space, an active neutron coincidence counter (or collar) using boron-coated straws (BCSs) as a non-3He replacement to the Uranium Neutron Coincidence Collar (UNCL). UNCL has been used by the International Atomic Energy Agency (IAEA) and European Atomic Energy Community (Euratom) since the 1980s to verify the 235U content in fresh light water reactor fuel assemblies for safeguards purposes. This report documents the design and optimization of the BCS collar.

  2. In situ synthesis of a large area boron nitride/graphene monolayer/boron nitride film by chemical vapor deposition

    Science.gov (United States)

    Wu, Qinke; Jang, Sung Kyu; Park, Sangwoo; Jung, Seong Jun; Suh, Hwansoo; Lee, Young Hee; Lee, Sungjoo; Song, Young Jae

    2015-04-01

    We describe the successful in situ chemical vapor deposition synthesis of a graphene-based heterostructure in which a graphene monolayer is protected by top and bottom boron nitride films. The boron nitride film/graphene monolayer/boron nitride film (BGB) was found to be a mechanically robust and chemically inert heterostructure, from which the deleterious effects of mechanical transfer processes and unwanted chemical doping under air exposure were eliminated. The chemical compositions of each film layer were monitored ex situ using UV-visible absorption spectroscopy and X-ray photoelectron spectroscopy, and the crystalline structures were confirmed using transmission electron microscopy and selected-area electron diffraction measurements. The performance of the devices fabricated using the BGB film was monitored over six months and did not display large changes in the mobility or the Dirac point, unlike the conventional graphene devices prepared on a SiO2 substrate. The in situ-grown BGB film properties suggest a novel approach to the fabrication of commercial-grade graphene-based electronic devices.We describe the successful in situ chemical vapor deposition synthesis of a graphene-based heterostructure in which a graphene monolayer is protected by top and bottom boron nitride films. The boron nitride film/graphene monolayer/boron nitride film (BGB) was found to be a mechanically robust and chemically inert heterostructure, from which the deleterious effects of mechanical transfer processes and unwanted chemical doping under air exposure were eliminated. The chemical compositions of each film layer were monitored ex situ using UV-visible absorption spectroscopy and X-ray photoelectron spectroscopy, and the crystalline structures were confirmed using transmission electron microscopy and selected-area electron diffraction measurements. The performance of the devices fabricated using the BGB film was monitored over six months and did not display large changes in the

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    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 Beams (LAMFI-USP) by the 10 B(p,αγ( 7 Be nuclear reaction, and measuring the 429 keV γ-ray. The in-air PIGE measurements at LAMFI have a quantification limit of the order of 10 16 at/cm 2

  4. Application of the boron neutron capture therapy to undifferentiated thyroid cancer using two boron compounds (BPA and BOPP)

    International Nuclear Information System (INIS)

    Viaggi, Mabel; Dagrosa, Maria A.; Juvenal, Guillermo J.; Pisarev, Mario A.; Longhino, Juan M.; Blaumann, Hernan R.; Calzetta Larrieu, Osvaldo A.; Kahl, Stephen B.

    2004-01-01

    We have shown the selective uptake of boronophenylalanine (BPA) by undifferentiated thyroid cancer (UTC) human cell line ARO, both in vitro and in vivo. Moreover, a 50% histologic cure of mice bearing the tumor was observed when the complete boron neutron capture therapy was applied. More recently we have analyzed the biodistribution of BOPP (tetrakis-carborane carboxylate ester of 2,4-bis-(ba-dihydroxyethyl)-deutero-porphyrin IX) and showed that when BOPP was injected 5 days before BPA, and the animals were sacrificed 60 min after the ip injection of BPA, a significant increase in boron uptake by the tumor was found (38-45ppm with both compounds Vs. 20 ppm with BPA alone). Five days post the ip BOPP injection and 1 hr after BPA, the ratios were: tumor/blood 3,75; tumor /distal skin 2. Other important ratios were tumor/thyroid 6,65 and tumor/lung 3,8. The present studies were performed in mice transplanted with ARO cells and injected with BOPP and BPA. Only in mice treated with the neutron beam and injected with the boronated compounds we observed a 100% control of tumor growth. Two groups of mice received different total absorbed doses: 3.00 and 6.01 Gy, but no further improvement in the outcome was found compared to the previous results using BPA alone (4.3 Gy). (author)

  5. Boron carbide synthesis by carbothermic reduction of boron oxide

    International Nuclear Information System (INIS)

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

    1988-01-01

    Boron carbide (B 4 C) is a ceramic material of technological applications due to its extreme hardness and high chemical as well as thermal stability. Some parameters of the process for obtaining B 4 C by carbothermic reduction of B 2 O 3 have been determined. The starting powders and the final products have been analysed by chemical, spectrographic and X-ray diffraction methods. The results show that the B 4 C obtained by the carbothermic reduction process is suitable for applications with a definite determination of the free carbon content. (author) [pt

  6. 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.

  7. 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.

  8. Hot flow behavior of boron microalloyed steels

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  9. Compression and associated properties of boron carbide

    Science.gov (United States)

    Ciezak, Jennifer; Dandekar, Dattatraya

    2009-06-01

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

  10. Ultratough single crystal boron-doped diamond

    Science.gov (United States)

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

    2015-05-05

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

  11. Spectral tailoring for boron Neutron capture therapy

    NARCIS (Netherlands)

    Nievaart, V.A.

    2007-01-01

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

  12. Fabrication of boron-phosphide neutron detectors

    International Nuclear Information System (INIS)

    Fitzsimmons, M.; Pynn, R.

    1997-01-01

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

  13. 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.

  14. 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.

  15. Continuum modeling of boron nitride nanotubes

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  16. 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.

  17. COUNTER-TERRORISM IN INDONESIA

    Directory of Open Access Journals (Sweden)

    Jordan Sebastian Meliala

    2015-04-01

    Full Text Available Since the incident of World Trade Center (WTC in USA, Indonesia has become an easy target for the next terrorism. Counterterrorist campaigns can be undertaken by military and paramilitary forces. Counterterrorism refers to proactive policies that specifically seek to eliminate terrorist environments and groups, Regardless of which policy is selected, the ultimate goal of counterterrorism is clear: to save lives by proactively preventing or decreasing the number of terrorist attacks. But, so far the Government of Indonesia is only able to capture the terrorists but is unable to eradicate terrorism. Therefore, the government of Indonesia still needs a comprehensive ways to counter terrorism in Indonesia

  18. Analysis of boron nitride by flame spectrometry methods

    International Nuclear Information System (INIS)

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

    1989-01-01

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

  19. Chemical vapor deposited boron carbide

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  20. 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.

  1. Boron Enrichment in Martian Clay

    Science.gov (United States)

    Nagashima, Kazuhide; Freeland, Stephen J.

    2013-01-01

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

  2. Positron annihilation in boron nitride

    Directory of Open Access Journals (Sweden)

    N.Amrane

    2006-01-01

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

  3. Fabrication and characterization of boron-doped nanocrystalline diamond-coated MEMS probes

    Science.gov (United States)

    Bogdanowicz, Robert; Sobaszek, Michał; Ficek, Mateusz; Kopiec, Daniel; Moczała, Magdalena; Orłowska, Karolina; Sawczak, Mirosław; Gotszalk, Teodor

    2016-04-01

    Fabrication processes of thin boron-doped nanocrystalline diamond (B-NCD) films on silicon-based micro- and nano-electromechanical structures have been investigated. B-NCD films were deposited using microwave plasma assisted chemical vapour deposition method. The variation in B-NCD morphology, structure and optical parameters was particularly investigated. The use of truncated cone-shaped substrate holder enabled to grow thin fully encapsulated nanocrystalline diamond film with a thickness of approx. 60 nm and RMS roughness of 17 nm. Raman spectra present the typical boron-doped nanocrystalline diamond line recorded at 1148 cm-1. Moreover, the change in mechanical parameters of silicon cantilevers over-coated with boron-doped diamond films was investigated with laser vibrometer. The increase of resonance to frequency of over-coated cantilever is attributed to the change in spring constant caused by B-NCD coating. Topography and electrical parameters of boron-doped diamond films were investigated by tapping mode AFM and electrical mode of AFM-Kelvin probe force microscopy (KPFM). The crystallite-grain size was recorded at 153 and 238 nm for boron-doped film and undoped, respectively. Based on the contact potential difference data from the KPFM measurements, the work function of diamond layers was estimated. For the undoped diamond films, average CPD of 650 mV and for boron-doped layer 155 mV were achieved. Based on CPD values, the values of work functions were calculated as 4.65 and 5.15 eV for doped and undoped diamond film, respectively. Boron doping increases the carrier density and the conductivity of the material and, consequently, the Fermi level.

  4. Electron paramagnetic resonance investigations of carbon-doped β rhombohedral boron

    International Nuclear Information System (INIS)

    Gercke, U.; Siems, C.-D.

    1979-01-01

    Electron paramagnetic resonance (EPR) measurements at 9 and 35 GHz on polycrystalline β rhombohedral boron with various carbon contents resulted in partly resolved absorption spectra. At 300 K the spin density ratio of two lines (called D and E) showed a linear increase with the carbon content. This ratio is temperature dependent. The lines D and E are photo-EPR active with different quantum efficiencies at various temperatures. (Auth.)

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

    Directory of Open Access Journals (Sweden)

    Santos Anacleto Ranulfo dos

    2004-01-01

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

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

    International Nuclear Information System (INIS)

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

    1990-01-01

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

  7. The atomic and electronic structure of nitrogen- and boron-doped phosphorene.

    Science.gov (United States)

    Boukhvalov, Danil W

    2015-10-28

    First principles modeling of nitrogen- and boron-doped phosphorene demonstrates the tendency toward the formation of highly ordered structures. Nitrogen doping leads to the formation of -N-P-P-P-N- lines. Further transformation into -P-N-P-N- lines across the chains of phosphorene occurs with increasing band gap and increasing nitrogen concentration, which coincides with the decreasing chemical activity of N-doped phosphorene. In contrast to the case of nitrogen, boron atoms prefer to form -B-B- pairs with the further formation of -P-P-B-B-P-P- patterns along the phosphorene chains. The low concentration of boron dopants converts the phosphorene from a semiconductor into a semimetal with the simultaneous enhancement of its chemical activity. Co-doping of phosphorene by both boron and nitrogen starts from the formation of -B-N- pairs, which provides flat bands and further transformation of these pairs into hexagonal BN lines and ribbons across the phosphorene chains.

  8. Geometric covers, graph orientations, counter games

    DEFF Research Database (Denmark)

    Berglin, Edvin

    are a type of abstract game played over a set of counters holding values, and these values may be moved between counters according to some set of rules. Typically they are played between two players: the adversary who tries to concentrate the greatest value possible in a single counter, and the benevolent......-directed graph is dynamic (can be altered by some outside actor), some orientations may need to be reversed in order to maintain the low out-degree. We present a new algorithm that is simpler than earlier work, yet matches or outperforms the efficiency of these results with very few exceptions. Counter games...... player who tries to prevent the adversary from doing so. These counter games are sometimes used as a behind-the-scenes tool for proving the efficiency of an algorithm, i.e. proving that the adversary is unable concentrate more than some specific value in a counter, also proves that the algorithm cannot...

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

    Science.gov (United States)

    Dyachkov, Sergey; Parshikov, Anatoly; Zhakhovsky, Vasily

    2017-06-01

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

  10. Hyaluronic acid as a potential boron carrier for BNCT: Preliminary evaluation.

    Science.gov (United States)

    Zaboronok, A; Yamamoto, T; Nakai, K; Yoshida, F; Uspenskii, S; Selyanin, M; Zelenetskii, A; Matsumura, Akira

    2015-12-01

    Hyaluronic acid (HA), a nonimmunogenic, biocompatible polymer found in different biological tissues, has the potential to attach to CD44 receptors on the surface of certain cancer cells, where the receptor is overexpressed compared with normal cells. Boron-hyaluronic acid (BHA) was tested for its feasibility as a potential agent for BNCT. BHA with low-viscosity 30 kDa HA could be administered by intravenous injection. The compound showed a certain degree of cytotoxicity and accumulation in C6 rat glioma cells in vitro. Instability of the chelate bonds between boron and HA and/or insufficient specificity of CD44 receptors on C6 cells to BHA could account for the insufficient in vitro accumulation. To ensure the future eligibility of BHA for BNCT experiments, using alternative tumor cell lines and chemically securing the chelate bonds or synthesizing BHA with boron covalently attached to HA might be required. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-01

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

  13. Boronline, a new generation of boron meter

    International Nuclear Information System (INIS)

    Pirat, P.

    2011-01-01

    Rolls-Royce is a global business providing integrated power systems for use on land, at sea and in the air. The Group has a balanced business portfolio with leading market positions - civil aerospace, defence aerospace, marine and energy Rolls-Royce understands the challenges of design, procurement, manufacture, operation and in-service support of nuclear reactor plants, with over 50 years of experience through the Royal Navy submarine programme. Rolls-Royce can therefore offer full product life-cycle management for new civil nuclear installations, as well as support to existing installations, including plant lifetime extensions. Rolls-Royce produced for 40 years, Instrumentation and Control (I and C) systems of and associated services for nuclear reactors in Europe, including 58 French reactors and others situated in the United States and in others countries, such as China. Rolls-Royce equipped in this domain 200 nuclear reactors in 20 countries. Among all of its nuclear systems, Rolls Royce is presenting to the conference its new generation of on-line boron measurement system, so called Boronline. (authors)

  14. Crate counter for normal operating loss

    International Nuclear Information System (INIS)

    Harlan, R.A.

    A lithium-loaded zinc sulfide scintillation counter to closely assay plutonium in waste packaged in 1.3 by 1.3 by 2.13m crates was built. In addition to assays for normal operating loss accounting, the counter will allow safeguards verification immediately before shipment of the crates for burial. The counter should detect approximately 10 g of plutonium in 1000 kg of waste

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

    OpenAIRE

    LI Jian-ping

    2014-01-01

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

  16. Composite boron nitride neutron detectors

    Science.gov (United States)

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

    2014-09-01

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

  17. Butane gas-flow proportional counter

    International Nuclear Information System (INIS)

    Han Jingquan; Ren Wei; Ma Liping

    2000-01-01

    It is experimentally proved that the butane can be used as an operating gas of the proportional counter. The operating performances of the counter with the butane are quite similar to that with the methane. A KX-50 butane flow proportional counter is described and its plateau characteristic is determined. For this counter, the plateau length, the slope of the plateau, the background count rate is 600 V, 1.7% per 100 V, 0.02s -1 for 239 Pu α source and about 500 V, 1.8% per 100 V, 3s -1 for 90 Sr- 90 Y source, respectively

  18. Boron-Loaded Silicone Rubber Scintillators

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-05-12

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

  19. Density separation of boron particles. Final report

    International Nuclear Information System (INIS)

    Smith, R.M.

    1980-04-01

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

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

    International Nuclear Information System (INIS)

    Kitaoka, Y.

    1991-07-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-11-25

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

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

    International Nuclear Information System (INIS)

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

    1978-09-01

    The sealed tube method of dissolution at high temperature and pressure has been successfully applied in the analysis of reactor grade boron carbide for the determination of boron. A 50 mg sample of boron carbide is completely dissolved by heating with concentrated nitric acid in a sealed tube at 300 0 C. The boron content of the resultant sample solution is determined by the mannitol potentiometric titration method. The precision of the method for the determination of 2.5 mg of boron using the Harwell automatic potentiometric titrator is 0.2% (coefficient of variation). The carbon content of a boron carbide sample is determined by combustion of the sample at 1050 0 C in a stream of oxygen using vanadium pentoxide to ensure the complete oxidation of the sample. The carbon dioxide produced from the sample is measured manometrically and the precision of the method for the determination of 4 mg of carbon is 0.4% (coefficient of variation). (author)

  3. Quantitative boron detection by neutron transmission method

    International Nuclear Information System (INIS)

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

    2008-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-01

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

  5. Boron Isotope Fractionation in Bell Pepper

    OpenAIRE

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

    2015-01-01

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

  6. Study on plasma sprayed boron carbide coating

    Science.gov (United States)

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

    2002-03-01

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

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

    Science.gov (United States)

    Edward Raja, Chellaiah; Omine, Kiyoshi

    2013-08-01

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

  8. Evaluation of waste crate counter

    International Nuclear Information System (INIS)

    Wachter, J.R.; Shaw, S.W.

    1994-01-01

    A novel nondestructive measurement system has been developed to perform combined gamma-ray, passive neutron, and active neutron analyses of radioactive waste packaged in large crates. The system will be used to examine low level and transuranic waste at the Waste Receiving and Processing facility at Westinghouse-Hanford Corp. Prior to delivery of the system, an extensive evaluation of its performance characteristics will be conducted. The evaluation is to include an assessment of the mechanical properties of the system, gamma-ray attenuation correction algorithms, instrument response as a function of source positions, performance of the high resolution gamma-ray detector for ''hot spot'' and isotopic analyses, active and passive neutron counter response, instrument sensitivity, matrix effects, and packaging effects. This report will discuss the findings of the evaluation program, to date, and indicate future directions for the program

  9. Numerical model of thyroid counter

    Directory of Open Access Journals (Sweden)

    Szuchta Maciej

    2016-03-01

    Full Text Available The aim of this study was to develop a numerical model of spectrometric thyroid counter, which is used for the measurements of internal contamination by in vivo method. The modeled detector is used for a routine internal exposure monitoring procedure in the Radiation Protection Measurements Laboratory of National Centre for Nuclear Research (NCBJ. This procedure may also be used for monitoring of occupationally exposed nuclear medicine personnel. The developed model was prepared using Monte Carlo code FLUKA 2011 ver. 2b.6 Apr-14 and FLAIR ver. 1.2-5 interface. It contains a scintillation NaI(Tl detector, the collimator and the thyroid water phantom with a reference source of iodine 131I. The geometry of the model was designed and a gamma energy spectrum of iodine 131I deposited in the detector was calculated.

  10. Laser surface alloying of commercially pure titanium with boron and carbon

    Science.gov (United States)

    Makuch, N.; Kulka, M.; Dziarski, P.; Przestacki, D.

    2014-06-01

    Laser surface alloying with boron and carbon was applied to produce the composite layers, reinforced by the hard ceramic phases (titanium borides and titanium carbides), on commercially pure titanium. The external cylindrical surface of substrate material was coated by paste containing boron, boron and graphite, or graphite. Then, the laser re-melting was carried out with using the continuous-wave CO2 laser. This enabled the formation of laser-borided, laser-borocarburized, and laser-carburized layers. The microstructure or the re-melted zone consisted of the hard ceramic phases (TiB+TiB2, TiB+TiB2+TiC, or TiC) located in the eutectic mixture of Tiα'-phase with borides, borides and carbides, or carbides, respectively. All the composite layers were characterized by the sufficient cohesion. The significant increase in microhardness and in wear resistance of all the laser-alloyed layers was observed in comparison with commercially pure titanium. The percentage of hard ceramic phases in more plastic eutectic mixture influenced the measured microhardness values. The dominant wear mechanism (abrasive or adhesive) depended on the method of laser alloying, and the type of test used. The wear tests for longer duration, without the change in the counter specimen, created the favourable conditions for adhesive wear, while during the shorter tests the abrasive wear dominated, as a rule.

  11. Low-pressure, multistep, multiwire proportional counter for the time-of-flight isochronous spectrometer

    International Nuclear Information System (INIS)

    Vieira, D.J.

    1985-01-01

    A low-pressure, multistep, multiwire proportional counter (MSMWPC) has been developed for the characterization and testing of the time-of-flight isochronous (TOFI) spectrometer and its associated secondary-beam transport line. This type of counter was selected because of its high sensitivity, large dynamic range, and good position (0.2 mm FWHM) and timing (180 ps FWHM) resolution. Furthermore, because the counter operates at low gas pressures (1-10 torr) and high electric-field strengths, which enable short collection times, it can be used as a transmission counter with thin gas-isolation windows and it can operate at high counting rates. Here the authors discuss the basic operating principle of the MSMWPC, describe the technical details of the detector and signal processing, and report on the performance they have measured for alpha particles and fission fragments

  12. Development of aerogel Cherenkov counters for KEDR detector

    International Nuclear Information System (INIS)

    Onuchin, A.P.; Shamov, A.G.; Vorobiov, A.I.; Danilyuk, A.F.; Gorodetskaya, T.A.; Kunznetsov, V.L.

    1990-01-01

    A threshold Cherenkov counters were proposed for particle identification in KEDR detector for B-mesons study. The counters are based on silica aerogel and phototubes, which can work in high magnetic field. Counters have a compact design and nearly 4π acceptance. In this paper design of counters is described. Tests of phototubes and Cherenkov counter prototype are presented

  13. On generating counter-rotating streamwise vortices

    KAUST Repository

    Winoto, S H

    2015-09-23

    Counter-rotating streamwise vortices are known to enhance the heat transfer rate from a surface and also to improve the aerodynamic performance of an aerofoil. In this paper, some methods to generate such counter-rotating vortices using different methods or physical conditions will be briefly considered and discussed.

  14. Charged particle identification: Cherenkov counters at ISABELLE

    International Nuclear Information System (INIS)

    Etkin, A.; Kostoulas, I.; Leith, D.W.G.S.; Thun, R.

    1977-01-01

    A brief summary is given of a study of Cherenkov counters for ISABELLE. The study was certainy not exhaustive and was meant primarily to suggest future detector development. A substantial research effort is needed in order to insure that Cherenkov counters utilizing photoionization are fully exploited

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

    Directory of Open Access Journals (Sweden)

    Nurlia Pramita Sari

    2017-08-01

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

  16. Breaking the icosahedra in boron carbide.

    Science.gov (United States)

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

    2016-10-25

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

  17. Boron adsorption on hematite and clinoptilolite

    International Nuclear Information System (INIS)

    Gainer, G.M.

    1993-01-01

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

  18. Determination of boron in amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

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

    1985-10-01

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

  19. Boron precipitates in ion implanted silicon

    International Nuclear Information System (INIS)

    Wu, W.K.; Washburn, J.

    1975-03-01

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

  20. Spectromicroscopy in Boron Neutron Capture Therapy Research

    Science.gov (United States)

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

    1998-03-01

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

  1. Behaviour of boron in Mandovi estuary (Goa)

    Digital Repository Service at National Institute of Oceanography (India)

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

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

  2. Aerogel Cherenkov Counters of the KEDR Detector

    CERN Document Server

    Ovtin, I V; Barnyakov, M Y; Bobrovnikov, V S; Buzykaev, A R; Danilyuk, A F; Katcin, A A; Kononov, S A; Kravchenko, E A; Kuyanov, I A; Onuchin, A P; Rodiakin, V A

    2017-01-01

    The particle identification system of the KEDR detector is based on aerogel threshold Cherenkov counters called ASHIPH counters. The system consists of 160 counters arranged in two layers. An event reconstruction program for the ASHIPH system was developed. The position of each counter relative to the tracking system was determined using cosmic muons and Bhabha events. The geometric efficiency of the ASHIPH system was verified with Bhabha events. The efficiency of relativistic particle detection was measured with cosmic muons. A π/K separation of 4δ in the momentum range 0.95 −1.45 GeV/c was confirmed. A simulation program for the ASHIPH counters has been developed.

  3. Proportional neutron counters for reactor engineering

    International Nuclear Information System (INIS)

    Artem'eva, I.V.; Zasadych, Yu.B.; Malyshev, E.K.

    1986-01-01

    Proportional neutron counters, designed for measuring the neutron flux density at nuclear reactors; position sensitive proportional neutron counters and recoil proton proportional counters, used at research reactors and accelerators are considered. Modern level of proportional neutron counters is described and trends in development of that field of engineering are determined. Specifications of detectors for industrial application are presented. The main trend in reactor detector development is the increase of service life, radiation resistance and thermal resistance. A particular place among the counters is occupied by position sensitive detectors, which appear to be the most rapidly developing detector type. Their further development and application sphere expansion depend on the production technology improvement, the development and lowering the price of the measuring electronic equipment

  4. Boron

    Science.gov (United States)

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

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

    Directory of Open Access Journals (Sweden)

    Si eLi

    2015-02-01

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

  6. Abrasive slurry composition for machining boron carbide

    Science.gov (United States)

    Duran, Edward L.

    1985-01-01

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

  7. Boron-rich oligomers for BNCT

    International Nuclear Information System (INIS)

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

    2000-01-01

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

  8. Discharge cleaning on TFTR after boronization

    International Nuclear Information System (INIS)

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

    1991-05-01

    At the beginning of the 1990 TFTR experimental run, after replacement of POCO-AXF-5Q graphite tiles on the midplane of the bumper limiter by carbon fiber composite (CFC) tiles and prior to any Pulse Discharge Cleaning (PDC), boronization was performed. Boronization is the deposition of a layer of boron and carbon on the vacuum vessel inner surface by a glow discharge in a diborane, methane and helium mixture. The amount of discharge cleaning required after boronization was substantially reduced compared to that which was needed after previous openings when boronization was not done. Previously, after a major shutdown, about 10 5 low current (∼20 kA) Taylor Discharge Cleaning (TDC) pulses were required before high current (∼400 kA) aggressive Pulse Discharge Cleaning (PDC) pulses could be performed successfully. Aggressive PDC is used to heat the limiters from the vessel bakeout temperature of 150 degrees C to 250 degrees C for a period of several hours. Heating the limiters is important to increase the rate at which water is removed from the carbon limiter tiles. After boronization, the number of required TDC pulses was reduced to <5000. The number of aggressive PDC pulses required was approximately unchanged. 14 refs., 1 tab

  9. 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.

  10. Countering violent extremism via de-securitisation on Twitter

    Directory of Open Access Journals (Sweden)

    Anna Warrington

    2017-06-01

    Full Text Available The case of a civil society actor on Twitter entering a securitized discourse on terrorism illustrates the transformative theoretical potential that emerges from new forms of communication online. Through a qualitative analysis of tweets from the Average Mohamed profile, the potential to change a negative narrative of violent extremism operating within a securitised discourse of Islamic terrorism, is discussed in an online context. The arguments forming from this analysis offers a new approach to studying online counter narratives by linking a theoretical framework of securitisation and de-securitisation to recent political efforts Countering Violent Extremism (CVE and Preventing Violent Extremism (PVE. Through the inclusion of a civil society Twitter account as an illustrative case, this paper explores how social media can challenge existing assumptions of who can be a de-securitising actor within security theory by blurring the lines between political and societal sectors in a securitised threat from Islamic terrorism. If and how a civil society actor can loosen the dichotomous discursive relationship between Self/Other relations within a contemporary discourse on terrorism becomes relevant for a theoretical discussion by presenting an argument suggesting that online CVE polices are more effective within the sphere of ‘normal’ politics rather than within the realm of securitization. This theoretical perspective offers an analytical framework including a wide range of actors involved in counter narratives policies which is useful for further CVE research.

  11. Evolution of FBR surveillance using a noise analysis and an on-line signal processing

    International Nuclear Information System (INIS)

    Trapp, J.P.; Lebrun, A.; Lhuillier, C.; Berger, R.; Martin, L.

    1996-01-01

    In a fast breeder reactor with a liquid sodium cooling as in the French nuclear type, the main goal of the surveillance and protection systems is to warrant the reactor integrity against every kind of incidents or accidents threatening the reactor, personnel and environment safety. In the future, the surveillance systems could be used to prevent all the events which could lead to an incident. In this way, a large number of neutronic detectors (fission chambers, boron counters), acoustic (sensors with wave guide), thermal (sodium-steel thermocouple) and vibratory sensors have been implemented in and out the primary vessel of these reactors. After a brief presentation of the standard surveillance and protection systems is given, with a recall of the main results obtained in France in the FBR noise analysis range is given. We show the results recently obtained at Phenix and Superphenix in the case of neutronic, thermal, acoustic and vibratory noises. In addition, we present the ALPES system, recently implemented, on line, at SPX with the goal to improve the core thermal surveillance; numeric processing of the thermocouples at the subassembly outlet are used. We show the main results and the improvements in the domain of the local accidents surveillance. Finally, we summarize the possibilities of an on-line noise analysis system for the early detection of FBR abnormalities. (authors)

  12. Avalanche localization and its effects in proportional counters

    International Nuclear Information System (INIS)

    Fischer, J.; Okuno, H.; Walenta, A.H.

    1977-11-01

    Avalanche development around the anode wire in a gas proportional counter is investigated. In the region of proportional gas amplification, the avalanche is found to be well localized on one side of the anode wire, where the electrons arrive along the field lines from the point of primary ionization. Induced signals on electrodes surrounding the anode wire are used to measure the azimuthal position of the avalanche on the anode wire. Practical applications of the phenomena such as left-right assignment in drift chambers and measurement of the angular direction of the primary ionization electrons drifting towards the anode wire are discussed

  13. A multiwire proportional counter for very high counting rates

    International Nuclear Information System (INIS)

    Barbosa, A.F.; Guedes, G.P.; Tamura, E.; Pepe, I.M.; Oliveira, N.B.

    1997-12-01

    Preliminary measurements in a proportional counter with two independently counting wires showed that counting rates up to 10 6 counts/s per wire can be reached without critical loss in the true versus measured linearity relation. Results obtained with a detector containing 30 active wires (2 mm pitch) are presented. To each wire is associated a fast pre-amplifier and a discriminator channel. Global counting rates in excess to 10 7 events/s are reported. Data acquisition systems are described for 1D (real time) and 2D (off-line) position sensitive detection systems. (author)

  14. A multiwire proportional counter for very high counting rates

    International Nuclear Information System (INIS)

    Barbosa, A.F.; Guedes, G.P.; Tamura, E.; Cardoso, M.R.; Pepe, I.M.; Oliveira, N.B.

    1997-01-01

    Full text. In order to obtain high counting rates with a gas detector, it is showed that a proportional counter with two independently counting wires can reach up to 10 6 counts/s per wire, without critical loss in the 'true versus measured' linearity relation. Results obtained with a detector containing 30 active wires (2 mm pitch) are presented. To each wire is associated a fast pre-amplifier and a discriminator channel. Global counting rates in excess to 10 7 events/s are reported. Data acquisition systems are described for 1D (real time) and 2D (off-line) position sensitive detection systems. (author)

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

    International Nuclear Information System (INIS)

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

    1994-01-01

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

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

    Science.gov (United States)

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

  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. Instability of counter-rotating stellar disks

    Science.gov (United States)

    Hohlfeld, R. G.; Lovelace, R. V. E.

    2015-09-01

    We use an N-body simulation, constructed using GADGET-2, to investigate an accretion flow onto an astrophysical disk that is in the opposite sense to the disk's rotation. In order to separate dynamics intrinsic to the counter-rotating flow from the impact of the flow onto the disk, we consider an initial condition in which the counter-rotating flow is in an annular region immediately exterior the main portion of the astrophysical disk. Such counter-rotating flows are seen in systems such as NGC 4826 (known as the "Evil Eye Galaxy"). Interaction between the rotating and counter-rotating components is due to two-stream instability in the boundary region. A multi-armed spiral density wave is excited in the astrophysical disk and a density distribution with high azimuthal mode number is excited in the counter-rotating flow. Density fluctuations in the counter-rotating flow aggregate into larger clumps and some of the material in the counter-rotating flow is scattered to large radii. Accretion flow processes such as this are increasingly seen to be of importance in the evolution of multi-component galactic disks.

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

    Science.gov (United States)

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

    1993-01-01

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

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

    Science.gov (United States)

    Torigoe, Kazuhisa; Ono, Toshiaki

    2017-06-01

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

  1. 21 CFR 866.2170 - Automated colony counter.

    Science.gov (United States)

    2010-04-01

    ...) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2170 Automated colony counter. (a) Identification. An automated colony counter is a mechanical device intended for medical...

  2. Boron-containing thioureas for neutron capture therapy

    International Nuclear Information System (INIS)

    Ketz, H.

    1993-01-01

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

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

    Science.gov (United States)

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

    2017-05-01

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

  4. High pressure BF3 proportional counter

    International Nuclear Information System (INIS)

    Mihara, Masaru; Gotoh, Eiichiro; Kodama, Masahiro

    1978-01-01

    Plateau and pulse characteristics of high pressure BF 3 proportional counter were investigated in terms of counter geometry and gas pressure, in order to develop a small-sized and high-sensitive one. Description is given of the construction of improved gas filling equipment with filling procedure. A tentative brass counter, 67 mm in cathode diameter, 40 micron in anode diameter, filled to 1.2 kg/cm 2 revealed characteristics of 150 volts plateau range, the slope of which being 3% per 100 volts at the operation voltage of around 3.3 kV, and 103% full width at half-maximum in the pulse height distribution. (auth.)

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

    Czech Academy of Sciences Publication Activity Database

    Grüner, Bohumír; Štíbr, Bohumil

    2015-01-01

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

  6. Removal of boron from aqueous solution using cryptocrystalline magnesite

    CSIR Research Space (South Africa)

    Masindi, Vhahangwele

    2016-05-01

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

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

    International Nuclear Information System (INIS)

    Kuehl, D.K.

    1975-01-01

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

  8. Method of manufacture of atomically thin boron nitride

    Science.gov (United States)

    Zettl, Alexander K

    2013-08-06

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

  9. An Ultra-High Pressure Proportional Counter for Hard X-Ray Astronomy.

    Science.gov (United States)

    Ye, Zongnan

    1992-01-01

    This thesis describes the successful development of ultra-high pressure proportional counters for balloon -borne hard X-ray astronomy. The proportional counters were filled with argon/xenon at pressures up to {~}30atm. The properties of proportional counters filled at such pressures have been studied by the author in the laboratory. The spatial response of these counters to X-rays and charged particles, and the energy response to X-rays up to 1MeV have been analysed. Gas gain measurements using the charge collection technique and analysis of the subsequent data show that simple extrapolation from low pressures cannot explain the observed behaviour (e.g. the mobility of positive ions and quenching efficiency) of these counters at high pressures. A hard X-ray telescope consisting of 32 such proportional counters filled at ultra-high pressures is being constructed, details of which are described. The sensitivity of this telescope for both continuum and narrow-line spectra is superb compared to contemporary balloon-and satellite-borne hard X-ray detectors. Together with an imaging phoswich Anger camera, it is scheduled for launch from Alice Springs in November 1992. An anticoincidence system for an X-ray detector, consisting of a combined passive and active shield, has been designed and constructed by the author, and flown on a balloon. The active shield, made of a plastic scintillator, has resulted in an additional reduction of 25% in the background registered at balloon altitudes.

  10. Enhanced Boron Tolerance in Plants Mediated by Bidirectional Transport Through Plasma Membrane Intrinsic Proteins.

    Science.gov (United States)

    Mosa, Kareem A; Kumar, Kundan; Chhikara, Sudesh; Musante, Craig; White, Jason C; Dhankher, Om Parkash

    2016-02-23

    High boron (B) concentration is toxic to plants that limit plant productivity. Recent studies have shown the involvement of the members of major intrinsic protein (MIP) family in controlling B transport. Here, we have provided experimental evidences showing the bidirectional transport activity of rice OsPIP1;3 and OsPIP2;6. Boron transport ability of OsPIP1;3 and OsPIP2;6 were displayed in yeast HD9 mutant strain (∆fps1∆acr3∆ycf1) as a result of increased B sensitivity, influx and accumulation by OsPIP1;3, and rapid efflux activity by OsPIP2;6. RT-PCR analysis showed strong upregulation of OsPIP1;3 and OsPIP2;6 transcripts in roots by B toxicity. Transgenic Arabidopsis lines overexpressing OsPIP1;3 and OsPIP2;6 exhibited enhanced tolerance to B toxicity. Furthermore, B concentration was significantly increased after 2 and 3 hours of tracer boron ((10)B) treatment. Interestingly, a rapid efflux of (10)B from the roots of the transgenic plants was observed within 1 h of (10)B treatment. Boron tolerance in OsPIP1;3 and OsPIP2;6 lines was inhibited by aquaporin inhibitors, silver nitrate and sodium azide. Our data proved that OsPIP1;3 and OsPIP2;6 are indeed involved in both influx and efflux of boron transport. Manipulation of these PIPs could be highly useful in improving B tolerance in crops grown in high B containing soils.

  11. Counter-Bioterrorism, US Intelligence Challenges

    National Research Council Canada - National Science Library

    Mardis, Howard

    2002-01-01

    This paper discusses challenges the US intelligence community faces in helping to counter bioterrorism a real and emerging threat that has the potential to cause mass destruction in the United States...

  12. Counter-Leadership Targeting and Conflict Termination

    National Research Council Canada - National Science Library

    Taylor, Bradly

    1999-01-01

    .... Can the leader be found? And, is it legal and ethical to attack the leader? Analysis rarely has been conducted to determine whether the targeted organization is vulnerable to Counter Leadership Targeting (CLT...

  13. ASHIPH counters for the KEDR detector

    CERN Document Server

    Barnyakov, A Y; Bobrovnikov, V S; Buzykaev, A R; Danilyuk, A F; Guber, F F; Kolachev, G M; Kononov, S A; Krasnov, V A; Kravchenko, E A; Kurepin, A B; Minakov, G D; Onuchin, A P; Savinov, G A; Tayursky, V A

    2002-01-01

    The status of the ASHIPH (Aerogel, wavelength SHIfter, and PHotomultipliers) system of the KEDR detector is described. The measurement of the quality of the particle identification with the ASHIPH counters was performed. The pi/K separation is 4.5 sigma for the momentum 1.2 GeV/c and 4.7 sigma for the momentum 0.86 GeV/c. Timing properties of the ASHIPH counter are measured. The time resolution for pions is 2 ns, and the BBQ decay time is 15 ns. The advantages and disadvantages of Cherenkov counters filled with aerogel crumb are discussed. The process of the mass counter production for the KEDR detector is described.

  14. Track reconstruction in BES barrel shower counter

    International Nuclear Information System (INIS)

    Zhao Haiwen; Wang Taijie; Mao Zepu; Li Jin; Li Weiguo; Yan Wuguang; Chen Guangpei; Liu Jing; Li Peiqin; Rong Gang; Yuan Ye; Liu Hongtao

    1999-01-01

    The track reconstruction of BES barrel shower counter was presented and the shower finding, pattern recognition technique were described. The reconstruction results from experimental data were presented and discussed

  15. Using over-the-counter medicines safely

    Science.gov (United States)

    ... ency/patientinstructions/000882.htm Using over-the-counter medicines safely To use the sharing features on this ... need to know about OTC drugs. About OTC Medicines You can buy OTC medicines without a prescription ...

  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. Impact scenarios in boron carbide: A computational study

    OpenAIRE

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

    2016-01-01

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

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

    International Nuclear Information System (INIS)

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

    1995-01-01

    A technology is developed for producing 'Phosphobor' fertilizer based on the rock phosphate weal (17-18% P 2 O 5 ) with additions of boron-magnesium compound. Boron is part of polyphosphate fertilizer in the form of polymeric compounds of phosphorus and boron. Phosphorus and boron copolymers -boratophosphates - are easily formed in the process of polyphosphate fertilizers production, since borates undergo a mutual polycondensation reaction with phosphates. 8 refs., 1 fig

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

    International Nuclear Information System (INIS)

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

    1990-01-01

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

  20. 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

  1. Bureaucracy vs. Bioterrorism: Countering a Globalized Threat

    Science.gov (United States)

    2011-02-16

    AIR WAR COLLEGE AIR UNIVERSITY BUREAUCRACY VS. BIOTERRORISM: COUNTERING A GLOBALIZED THREAT by Stephen G. Hoffman, Lt Col, USAF...DATES COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE Bureaucracy vs. Bioterrorism: Countering a Globalized Threat 5a. CONTRACT NUMBER...and novel biothreats to our adversaries. Globalization and the increasing availability of knowledge required to develop biothreats coupled with

  2. Quality control and the multicrystal counter

    International Nuclear Information System (INIS)

    Hart, G.C.; Davis, K.M.

    1983-01-01

    The reliability of multicrystal counters for use in counting large numbers of radioimmunoassay samples is studied. In particular, the dependencies of the outputs from the array of detectors, and hence their degree of matching, on the count rate and volume of the samples being counted are investigated. Quality control procedures are described to assist in the assurance of consistent performance of the counter in the clinical situation. (U.K.)

  3. Development of a Mobile Ice Nucleus Counter

    Energy Technology Data Exchange (ETDEWEB)

    Kok, Gregory [Droplet Measurement Technologies, Boulder, CO (United States); Kulkarni, Gourihar [Droplet Measurement Technologies, Boulder, CO (United States)

    2014-07-10

    An ice nucleus counter has been constructed. The instrument uses built-in refrigeration systems for wall cooling. A cascade refrigeration system will allow the cold wall to operate as low as -70°C, and a single stage system can operate the warm wall at -45C. A unique optical particle counter has been constructed using polarization detection of the scattered light. This allows differentiation of the particles exiting the chamber to determine if they are ice or liquid.

  4. Lifetime characteristics of Gaiger-Muller counters

    Directory of Open Access Journals (Sweden)

    Kartalović Nenad M.

    2016-01-01

    Full Text Available This paper discusses the process of functional aging of Geiger-Muller counters. Two types of Geiger-Muller counter chambers were characterized in an experiment using a combined constant voltage. Chamber A had a coaxial geometry and chamber B had a plan-parallel geometry. The experimental results indicate that the aging process was faster in the case of chambers with a coaxial geometry. The results are explained based on the process of electrical discharges in gasses.

  5. Boron-Loaded Silicone Rubber Scintillators

    CERN Document Server

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

    2003-01-01

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

  6. Hot ductility behavior of boron microalloyed steels

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  7. Update on human health effects of boron.

    Science.gov (United States)

    Nielsen, Forrest H

    2014-10-01

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

  8. Self-assembled monolayer of graphene/Pt as counter electrode for efficient dye-sensitized solar cell.

    Science.gov (United States)

    Gong, Feng; Wang, Hong; Wang, Zhong-Sheng

    2011-10-21

    Monolayer of PDDA/graphene/PDDA/H(2)PtCl(6) is fabricated on conductive glass using electrostatic layer-by-layer self-assembly technique, which is then converted to graphene/Pt monolayer for use as counter electrode in dye-sensitized solar cell (DSSC). As compared to the sputtered Pt counter electrode, the self-assembled monolayer reduces the Pt amount by about 1000-fold but exhibits comparable photovoltaic performance. This finding provides a new route to fabrication of cheap and efficient counter electrodes for flow-line production of DSSCs. This journal is © the Owner Societies 2011

  9. Personality Interactions and Scaffolding in On-Line Discussions

    Science.gov (United States)

    Nussbaum, E. Michael; Hartley, Kendall; Sinatra, Gale M.; Reynolds, Ralph E.; Bendixen, Lisa D.

    2004-01-01

    The potential of on-line discussions to prompt greater reflection of course material is often stymied by a tendency of students to agree with one another rather than to formulate counter-arguments. This article describes an experiment using note starters and elaborated cases to encourage counter-argumentation and examines interactions with…

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

    Directory of Open Access Journals (Sweden)

    N. F. Nevar

    2010-01-01

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

  11. Geiger-Mueller counters for measuring tritium

    International Nuclear Information System (INIS)

    Kostadinov, K.N.; Yanev, Y.I.; Todorovsky, D.S.

    1978-01-01

    In the course of building up a procedure for easy and inexpensive assay of low 3 H-activity in water samples pure acetylene filling of GM counters was carried out. The counters used were of the Johnston type with a stainless steel cathodes and tungsten anode wire. When filled with pure acetylene, synthesized in specially constructed vacuum apparatus, they showed very good characteristics in the GM region. In the range of acetylene pressures 40-100 mm Hg, the length of plateaus varied from 150 to 250 V and there was a clear dependence of the plateau length on the acetylene pressure in the counter. The same was true of the threshold and working voltage. Increasing acetylene pressure led to a certain increase in the background of the counter probably due to photosensitivity. When using acetylene pressures exceeding 70 mm Hg, the increase in the background was negligible. The slope of the plateau was usually not more then 2-3%/100V and the dead time determined by the Stever method was 150 s. The obtained characteristics of the counter support the conclusion that acetylene can be used as pure filling gas of Geiger counters to measure tritium. (K.M.)

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

    International Nuclear Information System (INIS)

    Kitaoka, Yoshinori

    1992-09-01

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

  13. Simulating the effect of boron doping in superconducting carbon

    Science.gov (United States)

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

    2018-02-01

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

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

    African Journals Online (AJOL)

    engin

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

  15. Mesoscale Modeling of Dynamic Compression of Boron Carbide Polycrystals

    Science.gov (United States)

    2013-05-01

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

  16. 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.

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

    Science.gov (United States)

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

  18. CAMAC-compatible differential pulse discriminator-counter

    International Nuclear Information System (INIS)

    Tselikov, I.V.

    1988-01-01

    A differential pulse discriminator-counter for a Moessbauer spectrometer is described. Input pulses are collected according to the following algorithm; a pulse is admitted into the channel depending on whether or not the preceding pulse fell into the discrimination window. The circuit does not contain delay lines to allow for the delay lines to allow for the delay of the signal from the upper-level discriminator with respect to the signal from the lower-level discriminator due to the finite rise time of the input pulses, which makes it possible to reduce the dead time of the discriminator to the actuation time of the threshold circuits. The pulse count rate is 150 MHz, the input amplitude is +/-3 V, the dead time is 6 nsec, and the delay from input to output is 14 nsec. The unit is CAMAC-compatible

  19. {sup 10}B uptake by cells for boron neutron capture synovectomy

    Energy Technology Data Exchange (ETDEWEB)

    Binello, E.; Yanch, J.C. [MIT, Department of Nuclear Engineering, Cambridge, MA (United States); Shortkroff, S. [Brigham and Women' s Hospital, Department of Orthopedic Surgery, Boston, MA (United States)

    2000-10-01

    Boron Neutron Capture Synovectomy (BNCS) proposes to use the {sup 10}B(n,{alpha}){sup 7}Li reaction to ablate inflamed synovium (a tissue lining articular joints) in patients with Rheumatoid Arthritis. Boron uptake is an important parameter for treatment design. In this study, a simple method was developed to determine K{sub 2}B{sub 12}H{sub 12} (KBH) uptake in vitro by non-adhering monocytic cells (representative of synovial cells in inflamed joints). Uptake was quantified as a function of incubation time and boron concentration, as well as following washout: no significant difference was found between incubation times tested; average uptake ranged from 55 to 60% of {sup 10}B incubation concentrations varying from 1000 to 5000 ppm: approximately 15% of the {sup 10}B concentration was measured upon re-incubation in boron-free medium. These results agree well with those obtained ex vivo using human arthritic synovium, a significant finding in light of the difficulty typically associated with obtaining such tissue. The full characterization of {sup 10}B uptake for BNCS (with KBH) is discussed. (author)

  20. Hyaluronic acid as a potential boron carrier for BNCT: Preliminary evaluation

    International Nuclear Information System (INIS)

    Zaboronok, A.; Yamamoto, T.; Nakai, K.; Yoshida, F.; Uspenskii, S.; Selyanin, M.; Zelenetskii, A.; Matsumura, Akira

    2015-01-01

    Hyaluronic acid (HA), a nonimmunogenic, biocompatible polymer found in different biological tissues, has the potential to attach to CD44 receptors on the surface of certain cancer cells, where the receptor is overexpressed compared with normal cells. Boron–hyaluronic acid (BHA) was tested for its feasibility as a potential agent for BNCT. BHA with low-viscosity 30 kDa HA could be administered by intravenous injection. The compound showed a certain degree of cytotoxicity and accumulation in C6 rat glioma cells in vitro. Instability of the chelate bonds between boron and HA and/or insufficient specificity of CD44 receptors on C6 cells to BHA could account for the insufficient in vitro accumulation. To ensure the future eligibility of BHA for BNCT experiments, using alternative tumor cell lines and chemically securing the chelate bonds or synthesizing BHA with boron covalently attached to HA might be required. - Highlights: • Hyaluronic acid (HA) is a nonimmunogenic, biocompatible polymer. • Boron–HA (BHA) acid can contain a large number of boron atoms for BNCT. • Active targeting can be realized with CD44 and other HA receptors on tumor cells. • BHA showed a certain degree of toxicity against C6 tumor cells and V79 fibroblasts. • BHA was injected into rats via the tail vein, boron was detected in tumors in vivo.

  1. Quantitative description of microstructure defects in hexagonal boron nitrides using X-ray diffraction analysis

    International Nuclear Information System (INIS)

    Schimpf, C.; Motylenko, M.; Rafaja, D.

    2013-01-01

    A routine for simultaneous quantification of turbostratic disorder, amount of puckering and the dislocation and stacking fault density in hexagonal materials was proposed and tested on boron nitride powder samples that were synthesised using different methods. The routine allows the individual microstructure defects to be recognised according to their effect on the anisotropy of the X-ray diffraction line broadening. For quantification of the microstructure defects, the total line broadening is regarded as a linear combination of the contributions from the particular defects. The total line broadening is obtained from the line profile fitting. As testing material, graphitic boron nitride (h-BN) was employed in the form of hot-isostatically pressed h-BN, pyrolytic h-BN or a h-BN, which was chemically vapour deposited at a low temperature. The kind of the dominant microstructure defects determined from the broadening of the X-ray diffraction lines was verified by high resolution transmission electron microscopy. Their amount was attempted to be verified by alternative methods. - Highlights: • Reliable method for quantification of microstructure defects in BN was suggested. • The method is based on the analysis of anisotropic XRD line broadening. • This XRD line broadening is unique and characteristic of the respective defect. • Thus, the quantification of coexistent microstructure defects is possible. • The method was tested on hexagonal BN, which was produced by different techniques

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

    Science.gov (United States)

    Halverson, Danny C.; Landingham, Richard L.

    1988-01-01

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

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

    International Nuclear Information System (INIS)

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

    1991-09-01

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

  4. Accelerator-driven boron neutron capture therapy

    Science.gov (United States)

    Edgecock, Rob

    2014-05-01

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

  5. The ternary system nickel-boron-silicon

    International Nuclear Information System (INIS)

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

    1975-01-01

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

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

    Science.gov (United States)

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

    2008-03-01

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

  7. On the Mechanism of Boron Ignition

    Science.gov (United States)

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

    1997-01-01

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

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

    NARCIS (Netherlands)

    Mohammadi, V.; Nihtianov, S.

    2016-01-01

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

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

    Science.gov (United States)

    Kurachi, Ikuo; Yoshioka, Kentaro

    2014-03-01

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

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

    Science.gov (United States)

    Munhollon, Tyler Lee

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

  11. Boron removal by electrocoagulation and recovery.

    Science.gov (United States)

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

    2014-03-15

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

  12. Modular high speed counter employing edge-triggered code

    Science.gov (United States)

    Vanstraelen, G.F.

    1993-06-29

    A high speed modular counter (100) utilizing a novel counting method in which the first bit changes with the frequency of the driving clock, and changes in the higher order bits are initiated one clock pulse after a 0'' to 1'' transition of the next lower order bit. This allows all carries to be known one clock period in advance of a bit change. The present counter is modular and utilizes two types of standard counter cells. A first counter cell determines the zero bit. The second counter cell determines any other higher order bit. Additional second counter cells are added to the counter to accommodate any count length without affecting speed.

  13. 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.

  14. Thermal conductivity behavior of boron carbides

    Science.gov (United States)

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

    1983-01-01

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

  15. Designing your boron-charging system

    International Nuclear Information System (INIS)

    Miller, J.

    1979-01-01

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

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

    Science.gov (United States)

    Song, Ningning; Li, Xiaodong

    2018-01-01

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

  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. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2000-01-01

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

  19. Study of counter E.M.F. on external cathodes proportional counters

    International Nuclear Information System (INIS)

    Tobias, C.C.B.

    1990-01-01

    Results previously obtained in our laboratory with Geiger-Mueller counters with external cathodes (Maze type), led us to build a cylindrical proportional counter around a tube of soda glass, covered by a thin layer of acquadag. The characteristics of this proportional counter were studied for argon and argon-methane mixture at atmospheric pressure, under continuous flow. Using alpha particles, emitted by an Am-241 source, the results obtained shown that its pulse amplitude decreases slowly with an increase of the counting rate, due to the counter e.m.f. which appears between the internal counter surface and the external cathode. This small effect, does not influence either the pulse amplitude distribution or the resolution, due to the large time constant of the distributed charge. (author)

  20. Efficient boron abstraction using honeycomb-like porous magnetic hybrids: Assessment of techno-economic recovery of boric acid.

    Science.gov (United States)

    Oladipo, Akeem Adeyemi; Gazi, Mustafa

    2016-12-01

    Porous magnetic hybrids were synthesized and functionalized with glycidol to produce boron-selective adsorbent. The magnetic hybrid (MH) comparatively out-performed the existing expensive adsorbents. MH had a saturation magnetisation of 63.48 emu/g and average pore diameter ranging from meso to macropores. The magnetic hybrids showed excellent selectivity towards boron and resulted in 79-93% boron removal even in the presence of competing metal ions (Na + and Cr 2+ ). Experiments were performed in a column system, and breakthrough time was observed to increase with bed depths and decreased with flow rates. The batch experiments revealed that 60 min was enough to achieve equilibrium, and the level of boron sorption was 108.5 mg/g from a synthetic solution. Several adsorption-desorption cycles were performed using a simple acid-water treatment and evaluated using various kinetic models. The spent adsorbents could be separated easily from the mixture by an external magnetic field. The cost-benefit analysis was performed for the treatment of 72 m 3 /year boron effluent, including five years straight line depreciation charges of equipment. The net profit and standard percentage confirmed that the recovery process is economically feasible. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Neutronic calculations for Angra-1 steam line break accident

    International Nuclear Information System (INIS)

    Ponzoni Filho, Pedro; Sato, Sadakatu

    2000-01-01

    The reduction of boron concentration in the Boron Injection Tank (BIT), to the room temperature solubility level, makes necessary a reanalysis of the steam line break accident of Angra 1 NPP. This paper describes the neutronic calculation related to this reanalysis. The main steps of the work were: review of reactivity parameters used in the accident simulation; search of xenon profiles that cause the most severe core power distribution; calculation of hot channel factors and other neutronic parameters necessary for DNBR determination. The final conclusion, related to the steam line break accident, states the BIT concentration may be reduced to 2000 ppm. (author)

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

    Science.gov (United States)

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

    2016-09-01

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

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

    International Nuclear Information System (INIS)

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

    1990-01-01

    The boron neutron capture therapy (BNCT) has shown better prognosis in the treatment of glyemas and gluoblastomas grade III and IV than other therapies. During the treatment the levels of Na 2 10 B 12 H 11 SH must be known in several compartiments of the organism and with this purpose the method of colorimetric determination of boron using curcumine was established. This method is simple, reprodutible and adequate sensitivity for this control. (author) [pt

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

    International Nuclear Information System (INIS)

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

    1989-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-06

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

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

    Science.gov (United States)

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

    2016-10-01

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

  7. 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.

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

    Directory of Open Access Journals (Sweden)

    Joo-Young Jung

    2016-09-01

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

  9. Position-sensitive proportional counters using resistance-capacitance position encoding

    International Nuclear Information System (INIS)

    Kopp, M.K.; Borkowski, C.J.

    1975-12-01

    A new method was developed for encoding the position of individual photons, neutrons, or charged particles in proportional counters by using the distributed RC line characteristics of these counters. The signal processing is described and guidelines for the design and operation of these position sensitive proportional counters (PSPCs) are given. Using these guidelines, several prototypic PSPCs were constructed to improve the spatial resolution and shorten the signal processing time; for example, the intrinsic spatial uncertainty was reduced to 28 μ fwhm for alpha particles and 100 μ fwhm for low-energy x rays (2 to 6 keV). Also, the signal processing time was reduced to 0.6 μsec without seriously degrading the spatial resolution. These results have opened new fields of application of the RC position encoding method in imaging distributions of photons, charged particles, or neutrons in nuclear medicine, physics, and radiography

  10. Testing boron carbide under triaxial compression

    Science.gov (United States)

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

    2012-03-01

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

  11. Kinetic analysis of boron carbide sintering

    International Nuclear Information System (INIS)

    Borchert, W.; Kerler, A.R.

    1975-01-01

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

  12. Compaction of amorphous iron–boron powder

    DEFF Research Database (Denmark)

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

    1993-01-01

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

  13. Boron nitride nanosheets reinforced glass matrix composites

    Czech Academy of Sciences Publication Activity Database

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

    2015-01-01

    Roč. 114, SEP (2015), S26-S32 ISSN 1743-6753 R&D Projects: GA MŠk(CZ) 7AMB14SK155 EU Projects: European Commission(XE) 264526 Institutional support: RVO:68081723 Keywords : Boron nitride nanosheets * Borosilicate glass * Mechanical properties Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.162, year: 2015

  14. Energetics of Boron Doping of Carbon Pores

    Science.gov (United States)

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

    2014-03-01

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

  15. Anomalous Seebeck coefficient in boron carbides

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  16. Reaction of boron carbide with molybdenum disilicide

    International Nuclear Information System (INIS)

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

    1989-01-01

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

  17. 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...

  18. NEW ADVANCES IN BORON SOIL CHEMISTRY - Paper

    Science.gov (United States)

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

  19. NEW ADVANCES IN BORON SOIL CHEMISTRY

    Science.gov (United States)

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

  20. Perfomance analysis of boron carbide in LMFBR

    International Nuclear Information System (INIS)

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

    1975-01-01

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

  1. Bandgap engineered graphene and hexagonal boron nitride

    Indian Academy of Sciences (India)

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

  2. Investigation into organic boron compounds complexing

    International Nuclear Information System (INIS)

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

    1983-01-01

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

  3. Counter-balanced, multiple cable construction crane

    Science.gov (United States)

    Mikulas, Martin M., Jr. (Inventor); Yang, Li-Farn (Inventor)

    1993-01-01

    The invention is a counter-balanced, multiple cable construction crane. The apparatus for hoisting payloads comprises a crane having a lifting means, the lifting means comprising an end effector means and three suspension means or cables. One end of each cable attaches to a different winding means located on the lifting means, and the other end of each cable attaches to a different point on the end effector, such that the three cables have a theoretical point of convergence with this point corresponding to the center of mass of the payload. Three controls command rotation of the winding means to a predetermined position. Accordingly, the crane provides precise and autonomous positioning of the payload without human guidance. The crane further comprises a counter-balancing means. Two controls position the counter-balancing means to offset the overturning moment which arises during the lifting of heavy payloads.

  4. An extended range neutron rem counter

    International Nuclear Information System (INIS)

    Birattari, C.; Nuccetelli, C.; Pelliccioni, M.; Silari, M.

    1990-01-01

    Extensive Monte Carlo calculations have been carried out to assess the possibility of extending the sensitivity of a neutron rem counter of the Andersson-Braun type up to several hundred MeV. The validity of the model adopted has first been checked by comparing with experimental data the calculated response curve and the angular dependence of the sensitivity for a well known commercial rem counter. Next, a number of modifications to the configuration of the moderator-attenuator have been investigated. The response functions and angular distributions produced by two simple solutions yielding an instrument with a sensitivity extended up to 400 MeV are presented. The response of the original rem counter and of its two modified versions to nine test spectra has also been calculated. The resulting instrument is transportable rather than portable, but the availability of an extended range neutron survey meter would be of great advantage at medium and high energy particle accelerator facilities. (orig.)

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

    DEFF Research Database (Denmark)

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

    2008-01-01

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

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

    Science.gov (United States)

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

    2015-10-01

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

  7. 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

  8. Calibration of nuclear medicine gamma counters

    International Nuclear Information System (INIS)

    Orlic, M.; Spasic-Jokic, V.; Jovanovic, M.; Vranjes, S. . E-mail address of corresponding author: morlic@vin.bg.ac.yu; Orlic, M.)

    2005-01-01

    In this paper the practical problem of nuclear medicine gamma counters calibration has been solved by using dose calibrators CRC-15R with standard error ±5%. The samples from technetium generators have been measured both by dose calibrators CRC-15R and gamma counter ICN Gamma 3.33 taking into account decay correction. Only the linear part of the curve has practical meaning. The advantage of this procedure satisfies the requirements from international standards: the calibration of sources used for medical exposure be traceable to a standard dosimetry laboratory and radiopharmaceuticals for nuclear medicine procedures be calibrated in terms of activity of the radiopharmaceutical to be administered. (author)

  9. Whole body counters: types, performance and uses

    International Nuclear Information System (INIS)

    Jales, R.L.C.

    1983-01-01

    The present monograph deals with Whole Counters, since its definition, evolution, performance, clinical indications and results. Scintillation crystals detection systems were described as well as scintillant solutions, plastic scintillations, and gaseous detectors, including its interplay forms and basal characteristics. Geometric arrangements of standard chair, arc and hammock, arrangements with scintillant solutions and plastic scintillations, as well as special geometric arrangements were equally commented. Clinic and experimental studies were also dealt with Whole Body Counters, giving examples with potassium, iron vitamin B 12 and albumin. (author)

  10. Extruded plastic counters with WLS fiber readout

    CERN Document Server

    Kudenko, Yu G; Mayatski, V A; Mineev, O V; Yershov, N V

    2001-01-01

    Extruded plastic scintillation counters with WLS fiber readout are described. For a 7 mm thick counter with 4.3 m long double-clad fibers spaced at 7 mm a light yield of 18.7 photoelectrons/MeV and a time resolution of 0.71 ns (sigma) were obtained. A prototype photon veto module consisting of 10 layers of 7 mm thick grooved plastic slabs interleaved with 1 mm lead sheets was also tested, which yielded 122 photoelectrons per minimum ionizing particle and time resolution of 360 ps.

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

    Science.gov (United States)

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

    2012-07-24

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

  12. Laser-induced photochemical enrichment of boron isotopes

    International Nuclear Information System (INIS)

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

    1976-01-01

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

  13. Higher boron rejection with a new TFC forward osmosis membrane

    KAUST Repository

    Valladares Linares, Rodrigo

    2014-07-17

    Due to the stringent limits for boron in drinking and irrigation water, water treatment facilities have to incur additional treatment to remove boron down to a safe concentration. Forward osmosis (FO) is a membrane technology that may reduce the energy required to remove boron present in seawater. In direct FO desalination hybrid systems, fresh water is recovered from seawater using a recoverable draw solution, FO membranes are expected to show high boron rejection. This study focuses on determining the boron rejection capabilities of a new generation thin-film composite (TFC) FO membrane compared to a first generation cellulose triacetate (CTA) FO membrane. The effects of water permeate flux, membrane structure, draw solute charge, and reverse solute flux on boron rejection were determined. For TFC and CTA FO membranes, experiments showed that when similar operating conditions are applied (e.g. membrane type and draw solute type) boron rejection decreases with increase in permeate flux. Reverse draw solute flux and membrane fouling have no significant impact on boron rejection. Compared to the first generation CTA FO membrane operated at the same conditions, the TFC FO membrane showed a 40% higher boron rejection capability and a 20% higher water flux. This demonstrates the potential for boron removal for new generation TFC FO membranes. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.

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

    Science.gov (United States)

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

    2010-05-15

    The removal of boron from aqueous solution by direct contact membrane distillation (DCMD) was studied with self-prepared polyvinylidene fluoride (PVDF) hollow fiber membranes in the present work. The effect of pH, boron concentration, temperature and salt concentration of the feed solution on the boron rejection was investigated. The experimental results indicated that boron rejection was less dependent on the feed pH and salt concentration. DCMD process had high boron removal efficiency (>99.8%) and the permeate boron was below the maximum permissible level even at feed concentration as high as 750 mg/L. Although the permeate flux was enhanced exponentially with the feed temperature increasing, the influence of feed temperature on the boron rejection could be neglected. Finally, the natural groundwater sample containing 12.7 mg/L of boron was treated by DCMD process. The permeate boron kept below 20 microg/L whether the feed was acidified or not, but pre-acidification was helpful to maintain the permeate flux stability. All the experimental results indicated that DCMD could be efficiently used for boron removal from aqueous solution. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  15. New particle detector - a spark counter with a localized discharge

    International Nuclear Information System (INIS)

    Laptev, V.D.; Pestov, Yu.N.; Petrovykh, N.V.; Sannikov, B.P.; Fedotovich, G.V.

    1978-01-01

    Described is a plane spark counter with a localized discharge, which provides better time and X-Y resolution over a large area and at a high counting speed. Unlike conventional counters, in case of puncture, voltage applied to the counter plates is taken off in a limited area round the discharge. Main characteristics of the counter with 0.1 mm gap between electrodes are given. It is shown that time resolution of spark counters with a localized discharge is better than that for other types of counters

  16. Cerenkov counters at the Omega Facility

    CERN Multimedia

    1975-01-01

    P. Petroff on the left. Here one sees both the gas Cerenkov counters sitting in front of the magnet to select forward emitted particles. The smaller one, working at high pressure, sits nearest to the Omega magnet (see photo 7505073X), the other (see photo 7505071X) works at atmospheric pressure.

  17. Calibration of proportional counters in microdosimetry

    International Nuclear Information System (INIS)

    Varma, M.N.

    1982-01-01

    Many microdosimetric spectra for low LET as well as high LET radiations are measured using commercially available (similar to EG and G) Rossi proportional counters. This paper discusses the corrections to be applied to data when calibration of the counter is made using one type of radiation, and then the counter is used in a different radiation field. The principal correction factor is due to differences in W-value of the radiation used for calibration and the radiation for which microdosimetric measurements are made. Both propane and methane base tissue-equivalent (TE) gases are used in these counters. When calibrating the detectors, it is important to use the correct stopping power value for that gas. Deviations in y-bar/sub F/ and y-bar/sub D/ are calculated for 60 Co using different extrapolation procedures from 0.15 keV/μm to zero event size. These deviations can be as large as 30%. Advantages of reporting microdosimetric parameters such as y-bar/sub F/ and y-bar/sub D/ above a certain minimum cut-off are discussed

  18. Townsend coefficients of gases in avalanche counters

    International Nuclear Information System (INIS)

    Brunner, G.

    1978-01-01

    Though much work has been done by many authors in the last few years in the development and application of avalanche counters for ion radiation, it is based upon values of the Townsend coefficients as the essential gas parameter, which were determined many years ago for much lower reduced field strengths F/p than prevail in such counters. Therefore absolute determinations of α in vapours of methyl alcohol, cyclohexane, acetone, and n-heptene were performed under original conditions of avalanche counters. The values obtained do not differ by more than 30%-50% from the former values indeed, extrapolated over F/p for the first three mentioned substances, but the amounts of A and B in the usual representation α/p=A exp(-B(F/p)) are much greater for the stronger reduced fields. This is of importance for such counter properties as the dependence of pulse heights on pressure, voltage, electrode distance etc., which are governed by other combinations of A and B than α/p itself. A comparison of results for different ionic radiations shows a marked influence of the primary ionization density along the particle tracks which is hard to explain. (Auth.)

  19. Imaging rings in ring imaging Cherenkov counters

    Energy Technology Data Exchange (ETDEWEB)

    Ratcliff, Blair N

    2002-11-25

    The general concepts used to form images in Ring Imaging Cherenkov (RICH) counters are described and their performance properties compared. Particular attention is paid to issues associated with imaging in the time dimension, especially in Detectors of Internally Reflected Cherenkov light (DIRCs).

  20. Can counter-stereotypes boost flexible thinking?

    NARCIS (Netherlands)

    Goclowska, M.A.; Crisp, R.J.; Labuschagne, K.

    2013-01-01

    To reduce prejudice psychologists design interventions requiring people to think of counter-stereotypes (i.e., people who defy stereotypic expectations—a strong woman, a Black President). Grounded in the idea that stereotypes constrain the ability to think flexibly, we propose that thinking of

  1. Incorporation monitoring with whole-body counters

    International Nuclear Information System (INIS)

    Steger, F.; Lovranich, E.; Urbanich, E.

    1988-01-01

    Whole-body counters are an important tool in dose measurements after incorporation. The present state in the design of whole-body measurements installations is shown and foreseeable developments are presented. Results of measurements and commited dose equivalent determinations are discussed with Chernobyl as an example. 9 refs., 10 figs., 3 tabs. (Authors, translated qui)

  2. Sealed drift tube cosmic ray veto counters

    Energy Technology Data Exchange (ETDEWEB)

    Rios, R., E-mail: rrios@lanl.go [Idaho State University, Pocatello, ID 83209 (United States); Tatar, E. [Idaho State University, Pocatello, ID 83209 (United States); Bacon, J.D.; Bowles, T.J.; Hill, R.; Green, J.A.; Hogan, G.E.; Ito, T.M.; Makela, M.; Morris, C.L.; Mortenson, R.; Pasukanics, F.E.; Ramsey, J.; Saunders, A.; Seestrom, S.J.; Sondheim, W.E.; Teasdale, W. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Saltus, M. [Sloan Enterprises, NC (United States); Back, H.O.; Cottrell, C.R. [North Carolina State University, Raleigh, NC 27695 (United States)

    2011-05-01

    We describe a simple drift tube counter that has been used as a cosmic ray veto for the UCNA experiment, a first-ever measurement of the neutron beta-asymmetry using ultra-cold neutrons. These detectors provide an inexpensive alternative to more conventional scintillation detectors for large area cosmic ray anticoincidence detectors.

  3. Counter Trafficking System Development "Analysis Training Program"

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, Dennis C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2010-12-01

    This document will detail the training curriculum for the Counter-Trafficking System Development (CTSD) Analysis Modules and Lesson Plans are derived from the United States Military, Department of Energy doctrine and Lawrence Livermore National Laboratory (LLNL), Global Security (GS) S Program.

  4. High School Equivalency as Counter-Space

    Science.gov (United States)

    Schwartz, Joni

    2014-01-01

    This chapter is based on the findings of an ethnographic study of an urban General Education Development (GED®) program and suggests that, for some marginalized African American and other young men of color, adult education programs are counter-spaces (Yosso, Ceja, Smith, & Solorzano, [Yosso, T., 2009]) of spatial justice in opposition to…

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

    Science.gov (United States)

    Chu, T. L.

    1975-01-01

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

  6. A multiwire proportional counter for very high counting rates

    International Nuclear Information System (INIS)

    Barbosa, A.F.; Guedes, G.P.; Tamura, E.; Pepe, I.M.; Oliveira, N.B.

    1998-01-01

    Preliminary measurements in a proportional counter with two independently counting wires showed that counting rates up to 10 6 counts s -1 wire -1 can be reached without critical loss in the 'true versus measured' linearity relation. Results obtained with a detector containing 30 active wires (2 mm pitch) are presented. With each wire is associated a fast pre-amplifier and a discriminator channel. Global counting rates in excess of 10 7 events s -1 are reported. Dead-time losses are corrected by use of simple mathematical-modelling functions. Data-acquisition systems are described for one-dimensional (real-time) and two-dimensional (off-line)position-sensitive detection systems

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

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  8. Diffusion Boronizing of H11 Hot Work Tool Steel

    Science.gov (United States)

    Jurči, Peter; Hudáková, Mária

    2011-10-01

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

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

    Science.gov (United States)

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

    2015-12-18

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

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

    Science.gov (United States)

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

    2017-09-01

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    The synthesis of boron nano wires, nano tubes, and nano sheets using a thermal vapor deposition process is reported. This work confirms previous research and provides a new method capable of synthesizing boron nano materials. The materials were made by using various combinations of MgB 2 , Mg(BH 4 ) 2 , MCM-41, NiB, and Fe wire. Unlike previously reported methods, a nanoparticle catalyst and a silicate substrate are not required for synthesis. Two types of boron nano wires, boron nano tubes, and boron nano sheets were made. Their morphology and chemical composition were determined through the use of scanning electron microscopy, transmission electron microscopy, and electron energy loss spectroscopy. These boron-based materials have potential for electronic and hydrogen storage applications.

  12. Boron autoradiography method applied to the study of steels

    International Nuclear Information System (INIS)

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

    1986-01-01

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

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

    Science.gov (United States)

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

    1987-01-01

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

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

    Science.gov (United States)

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

    1987-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-12-15

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

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

    Science.gov (United States)

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

    2017-04-05

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

  17. Can Counter-Gang Models be Applied to Counter ISIS’s Internet Recruitment Campaign

    Science.gov (United States)

    2016-06-10

    the unprecedented scope of the challenges posed by our enemy’s usage of the Internet to spread information.29 During the meeting, Lumpkin stated...CAN COUNTER-GANG MODELS BE APPLIED TO COUNTER ISIS’S INTERNET RECRUITMENT CAMPAIGN? A thesis presented to the Faculty of the... reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215

  18. 21 CFR 866.2180 - Manual colony counter.

    Science.gov (United States)

    2010-04-01

    ...) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2180 Manual colony counter. (a) Identification. A manual colony counter is a device intended for medical purposes that consists...

  19. Operating life of X-ray proportional counters

    International Nuclear Information System (INIS)

    Vajgachev, A.A.; Klyukvina, E.F.; Puzyrev, S.Yu.; Sorokin, L.S.; Chajkovskij, V.G.; Shchekin, K.I.

    1977-01-01

    The purpose of the work was to determine the operating time of X-ray proportional counters filled with a mixture of an inert gas with an organic additive. The counter energy resolution is used as the counter serviceability criterion. Counters operated at an integral counting speed of (3-8)x10 5 pulses per second and gas gain factor of 10 3 . A linear dependance of the counter operating time from the gas gain factor has been established (in the range of 10 2 -3x10 3 ). It has also been established that the counter operating time is independent of the inert gas type. An investigation into the counter anode filaments has been carried out. The obtained photographs of the anode surface indicate that during the counter operation the anode filament is covered with high spots caused by disintegration of the damping additive

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

    OpenAIRE

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2010-10-06

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

  2. Apparatus for the production of boron nitride nanotubes

    Science.gov (United States)

    Smith, Michael W; Jordan, Kevin

    2014-06-17

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

  3. Behavior of disordered boron carbide under stress.

    Science.gov (United States)

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

    2006-07-21

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

  4. Steam activation of boron doped diamond electrodes

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  5. Facile Synthesis of Ternary Boron Carbonitride Nanotubes

    Directory of Open Access Journals (Sweden)

    Luo Lijie

    2009-01-01

    Full Text Available Abstract In this study, a novel and facile approach for the synthesis of ternary boron carbonitride (B–C–N nanotubes was reported. Growth occurred by heating simple starting materials of boron powder, zinc oxide powder, and ethanol absolute at 1150 °C under a mixture gas flow of nitrogen and hydrogen. As substrate, commercial stainless steel foil with a typical thickness of 0.05 mm played an additional role of catalyst during the growth of nanotubes. The nanotubes were characterized by SEM, TEM, EDX, and EELS. The results indicate that the synthesized B–C–N nanotubes exhibit a bamboo-like morphology and B, C, and N elements are homogeneously distributed in the nanotubes. A catalyzed vapor–liquid–solid (VLS mechanism was proposed for the growth of the nanotubes.

  6. CVD mechanism of pyrolytic boron nitride

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  7. Boron Nitride Nanotube: Synthesis and Applications

    Science.gov (United States)

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

    2014-01-01

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

  8. Synthesis and characterization of boron nitrides nanotubes

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  9. Characterization of boron doped nanocrystalline diamonds

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  10. Development of boron epoxy rocket motor chambers.

    Science.gov (United States)

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

    1972-01-01

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

  11. Microadditions of boron and vanadium in ADI

    Directory of Open Access Journals (Sweden)

    Rzychoń T.

    2007-01-01

    Full Text Available In the second part of the study, describing the role of vanadium and boron microadditions in the process of structure formation in heavy-walled castings made from ADI, the results of own investigations were presented. Within this study two series of melts of the ductile iron were made, introducing microadditions of the above mentioned elements to both unalloyed ductile iron and the ductile iron containing high levels of nickel and copper (the composition typical of ADI. Melts were conducted with iron-nickel-magnesium master alloy. Thermal analysis of the solidification process of the cast keel blocks was conducted, the heat treatment of the alloys was carried out, and then the effect of the introduced additions of boron and vanadium on the hardenability of the investigated cast iron was examined and evaluated.

  12. A fast photo-counter with multi-level buffers

    International Nuclear Information System (INIS)

    Peng Hu; Zhou Peiling; Yao Kun; Guo Guangcan

    1992-01-01

    Digital Photon Correlator (DPC) is composed of a Photo-counter and a data processing unit. The performance of Photo-counter in data acquisition system has a direct influence on data processing. The Photo-counter with fast carry designed here has multi-level buffers. Photon pulses can be correctly and dynamically recorded by the Photo-counter and processed by a single chip computer

  13. Dependence of boron cluster dissolution on the annealing ambient

    International Nuclear Information System (INIS)

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

    2002-01-01

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

  14. Molecular Dynamics Modeling of Piezoelectric Boron Nirtride Nanotubes

    Data.gov (United States)

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

  15. Cobalt Doping of Semiconducting Boron Carbide Using Cobaltocene

    National Research Council Canada - National Science Library

    Carlson, Lonnie

    2007-01-01

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

  16. Electron-Spin Resonance in Boron Carbide

    Science.gov (United States)

    Wood, Charles; Venturini, Eugene L.; Azevedo, Larry J.; Emin, David

    1987-01-01

    Samples exhibit Curie-law behavior in temperature range of 2 to 100 K. Technical paper presents studies of electron-spin resonance of samples of hot pressed B9 C, B15 C2, B13 C2, and B4 C. Boron carbide ceramics are refractory solids with high melting temperatures, low thermal conductives, and extreme hardnesses. They show promise as semiconductors at high temperatures and have unusually large figures of merit for use in thermoelectric generators.

  17. High resolution imaging of boron carbide microstructures

    International Nuclear Information System (INIS)

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

    1986-01-01

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

  18. Amorphous Carbon-Boron Nitride Nanotube Hybrids

    Science.gov (United States)

    Kim, Jae Woo (Inventor); Siochi, Emilie J. (Inventor); Wise, Kristopher E. (Inventor); Lin, Yi (Inventor); Connell, John (Inventor)

    2016-01-01

    A method for joining or repairing boron nitride nanotubes (BNNTs). In joining BNNTs, the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures. In repairing BNNTs, the damaged site of the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures at the damage site.

  19. Boron isotopes as an artificial tracer.

    Science.gov (United States)

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

    2006-01-01

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

  20. Boron Isotopes Enrichment via Continuous Annular Chromatography

    OpenAIRE

    Sağlam, Gonca

    2016-01-01

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

  1. Clinical aspects of boron neutron capture therapy

    International Nuclear Information System (INIS)

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

    1986-01-01

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

  2. Efficiency calibration of solid track spark auto counter

    International Nuclear Information System (INIS)

    Wang Mei; Wen Zhongwei; Lin Jufang; Liu Rong; Jiang Li; Lu Xinxin; Zhu Tonghua

    2008-01-01

    The factors influencing detection efficiency of solid track spark auto counter were analyzed, and the best etch condition and parameters of charge were also reconfirmed. With small plate fission ionization chamber, the efficiency of solid track spark auto counter at various experiment assemblies was re-calibrated. The efficiency of solid track spark auto counter at various experimental conditions was obtained. (authors)

  3. Generalization of the development of liquid-sparkling counter

    International Nuclear Information System (INIS)

    Bian Zhengzhu; Zhang Jue; Zhang Jinwei

    2006-01-01

    This paper includes five parts. It not only reviews the development history of liquid-sparkling counter but refers that the appearance of coincident circuit is its milestone. The paper summarizes the resembled hard ware and soft ware and soft ware of liquid-sparkling counter of indoor and overseas, and prospects the development of liquid-sparkling counter in our country. (authors)

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

    Science.gov (United States)

    An, Qi; Goddard, William A.

    2017-03-01

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

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

    Science.gov (United States)

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

    1986-01-01

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

  6. Boron determination in U3O8

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  7. Considerations for boron neutron capture therapy studies

    International Nuclear Information System (INIS)

    Faria Gaspar, P. de.

    1994-01-01

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

  8. Hybrid indirect/direct contactor for thermal management of counter-current processes

    Energy Technology Data Exchange (ETDEWEB)

    Hornbostel, Marc D.; Krishnan, Gopala N.; Sanjurjo, Angel

    2018-03-20

    The invention relates to contactors suitable for use, for example, in manufacturing and chemical refinement processes. In an aspect is a hybrid indirect/direct contactor for thermal management of counter-current processes, the contactor comprising a vertical reactor column, an array of interconnected heat transfer tubes within the reactor column, and a plurality of stream path diverters, wherein the tubes and diverters are configured to block all straight-line paths from the top to bottom ends of the reactor column.

  9. Governmentality, Counter-conduct and Prefigurative Demonstrations

    DEFF Research Database (Denmark)

    McIlvenny, Paul

    2016-01-01

    This chapter attends to the micro-ethnographic detail of actual practices, procedures and technologies – the techne – of governance, especially those practices that manifest as what Foucault called ‘counter-conducts’. The interactional and categorial practices of a prefigurative protest demonstra......This chapter attends to the micro-ethnographic detail of actual practices, procedures and technologies – the techne – of governance, especially those practices that manifest as what Foucault called ‘counter-conducts’. The interactional and categorial practices of a prefigurative protest...... how fields of visibility, forms of knowledge, technologies and apparatuses, and subjectivities and identities are negotiated and accomplished collaboratively. Specific tools and methods that are well suited to investigating the situated practices, procedures and technologies of governmentality...

  10. Sources of Brazil's Counter-Hegemony

    Directory of Open Access Journals (Sweden)

    Marcos Aurelio Guedes de Oliveira

    2010-01-01

    Full Text Available There have been two key initiatives taken in the last two decades in Brazil to create a counter-hegemonic project for the country. One initiative resulted from Brazil's business community and high-level State bureaucracy and aimed at forming a regional economic and political bloc that would guarantee and enlarge a relative independence from the hegemonic powers. The other resulted from the emergence of the new unionist movement in São Paulo and from the formation of Partido dos Trabalhadores and aimed at promoting radical democratization and reducing social exclusion. Both initiatives have created policies and changes that have converged to enhance Brazil's counter-hegemonic position as a regional and emerging power.

  11. Pulse triggering mechanism of air proportional counters

    International Nuclear Information System (INIS)

    Aoyama, T.; Mori, T.; Watanabe, T.

    1983-01-01

    This paper describes the pulse triggering mechanism of a cylindrical proportional counter filled with air at atmospheric pressure for the incidence of β-rays. Experimental results indicate that primary electrons created distantly from the anode wire by a β-ray are transformed into negative ions, which then detach electrons close to the anode wire and generate electron avalanches thus triggering pulses, while electrons created near the anode wire by a β-ray directly trigger a pulse. Since a negative ion pulse is triggered by a single electron detached from a negative ion, multiple pulses are generated by a large number of ions produced by the incidence of a single β-ray. It is therefore necessary not to count pulses triggered by negative ions but to count those by primary electrons alone when use is made of air proportional counters for the detection of β-rays. (orig.)

  12. Calibration of the neutron scintillation counter threshold

    International Nuclear Information System (INIS)

    Noga, V.I.; Ranyuk, Yu.N.; Telegin, Yu.N.

    1978-01-01

    A method for calibrating the threshold of a neutron counter in the form of a 10x10x40 cm plastic scintillator is described. The method is based on the evaluation of the Compton boundary of γ-spectrum from the discrimination curve of counter loading. The results of calibration using 60 Co and 24 Na γ-sources are given. In order to eValuate the Compton edge rapidly, linear extrapolation of the linear part of the discrimination curve towards its intersection with the X axis is recommended. Special measurements have shown that the calibration results do not practically depend on the distance between the cathode of a photomultiplier and the place where collimated γ-radiation of the calibration source reaches the scintillator

  13. Engaging Civil Society in Countering Violent Extremism

    Directory of Open Access Journals (Sweden)

    Bibi van Ginkel

    2012-08-01

    Full Text Available In this Research Paper Dr. Bibi van Ginkel takes an in depth look at how multi-lateral institutions, engage with civil society to counter violent extremism. Dr. van Ginkel argues that civil society can play a crucial role in preventing and countering violent extremism in numerous ways – by working on development programs, through their work in conflict transformation, in providing a platform to raise political grievances and to facilitate dialogue, or through their work in empowering victims and survivors of terrorism. The Paper finds that over the last decade there has been a more intensive coordination of activities between the UN and other multi-lateral organisations and civil society but the question remains whether the implementation as well as the drafting of these policies will live up to their potential effectiveness. This Paper gauges how effective these measures have been and what more there is to do. The final section concludes with a series of policy recommendations.

  14. Synovectomy by neutron capture in boron

    International Nuclear Information System (INIS)

    Vega C, H.R.

    2002-01-01

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

  15. Method and apparatus for coating thin foil with a boron coating

    Energy Technology Data Exchange (ETDEWEB)

    Lacy, Jeffrey L.

    2018-01-16

    An apparatus and a process is disclosed for applying a boron coating to a thin foil. Preferably, the process is a continuous, in-line process for applying a coating to a thin foil comprising wrapping the foil around a rotating and translating mandrel, cleaning the foil with glow discharge in an etching chamber as the mandrel with the foil moves through the chamber, sputtering the foil with boron carbide in a sputtering chamber as the mandrel moves through the sputtering chamber, and unwinding the foil off the mandrel after it has been coated. The apparatus for applying a coating to a thin foil comprises an elongated mandrel. Foil preferably passes from a reel to the mandrel by passing through a seal near the initial portion of an etching chamber. The mandrel has a translation drive system for moving the mandrel forward and a rotational drive system for rotating mandrel as it moves forward. The etching chamber utilizes glow discharge on a surface of the foil as the mandrel moves through said etching chamber. A sputtering chamber, downstream of the etching chamber, applies a thin layer comprising boron onto the surface of the foil as said mandrel moves through said sputtering chamber. Preferably, the coated foil passes from the mandrel to a second reel by passing through a seal near the terminal portion of the sputtering chamber.

  16. Prediction of Two-Dimensional Phase of Boron with Anisotropic Electric Conductivity.

    Science.gov (United States)

    Cui, Zhi-Hao; Jimenez-Izal, Elisa; Alexandrova, Anastassia N

    2017-03-16

    Two-dimensional (2D) phases of boron are rare and unique. Here we report a new 2D all-boron phase (named the π phase) that can be grown on a W(110) surface. The π phase, composed of four-membered rings and six-membered rings filled with an additional B atom, is predicted to be the most stable on this support. It is characterized by an outstanding stability upon exfoliation off of the W surface, and unusual electronic properties. The chemical bonding analysis reveals the metallic nature of this material, which can be attributed to the multicentered π-bonds. Importantly, the calculated conductivity tensor is anisotropic, showing larger conductivity in the direction of the sheet that is in-line with the conjugated π-bonds, and diminished in the direction where the π-subsystems are connected by single σ-bonds. The π-phase can be viewed as an ultrastable web of aligned conducting boron wires, possibly of interest to applications in electronic devices.

  17. Fast differential pulse discriminator-counter

    International Nuclear Information System (INIS)

    Shelevoj, K.D.

    1985-01-01

    The flowsheet of a differential pulse discriminator counter is described; the result of discrimination here is independent from the shape of the input pulse. Rate of the analysis of input pulses with minimum amplitude up to 0.3 mV coming out from the photomultiplier makes up 220 MHz. The flowsheet of the discriminator used in the system of photon counting for atmosphere probing is presented

  18. Light Obscuration Particle Counter Fuel Contamination Limits

    Science.gov (United States)

    2015-10-08

    limits were derived from 1.0 mg/L concentration levels for ISO 12103-1 A1Ultrafine and ISO 12103-1 A2 Fine test dusts , and down to a 5 ppm free water...AND USE OF LIQUID FUELS Charleston, South Carolina USA 4-8 October 2015 LIGHT OBSCURATION PARTICLE COUNTER FUEL CONTAMINATION LIMITS Joel... contamination . Based on this work the Department of Defense Tri-Service Petroleum, Oil and Lubricants Technical Steering Committee has recommended

  19. Universal Fast Breeder Reactor Subassembly Counter manual

    Energy Technology Data Exchange (ETDEWEB)

    Menlove, H.O.; Eccleston, G.W.; Swansen, J.E.; Goris, P.; Abedin-Zadeh, R.; Ramalho, A.

    1984-08-01

    A neutron coincidence counter has been designed for the measurement of fast breeder reactor fuel assemblies. This assay system can accommodate the full range of geometries and masses found in fast breeder subassemblies under IAEA safeguards. The system's high-performance capability accommodates high plutonium loadings of up to 16 kg. This manual describes the system and its operation and gives performance and calibration parameters for typical applications.

  20. Universal Fast Breeder Reactor Subassembly Counter manual

    International Nuclear Information System (INIS)

    Menlove, H.O.; Eccleston, G.W.; Swansen, J.E.; Goris, P.; Abedin-Zadeh, R.; Ramalho, A.

    1984-08-01

    A neutron coincidence counter has been designed for the measurement of fast breeder reactor fuel assemblies. This assay system can accommodate the full range of geometries and masses found in fast breeder subassemblies under IAEA safeguards. The system's high-performance capability accommodates high plutonium loadings of up to 16 kg. This manual describes the system and its operation and gives performance and calibration parameters for typical applications

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

    Science.gov (United States)

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

    2013-01-01

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    These wastes contain about 0.3-0.8 wt% boric acid and have been concentrated through an evaporation treatment. Boric acid tends to crystallize owing to its solubility, and to plug the evaporator. The volume reduction obtained through evaporation is limited by the amount of boric acid in the waste. As an emerging technology, forward osmosis (FO) has attracted growing interest in wastewater treatment and desalination. FO is a membrane process in which water flows across a semi-permeable membrane from a feed solution of lower osmotic pressure to a draw solution of higher osmotic pressure. However, very few studies on the removal of boron by FO have been performed. The objective of this study is to evaluate the possibility of boron separation in radioactive liquid waste by FO. In this study, the performance of FO was investigated to separate boron in the simulated liquid waste under the factors such as pH, osmotic pressure, ionic strength of the solution, and membrane characteristic. The boron separation in radioactive borate liquid waste was investigated with an FO membrane. When the feed solution containing boron is treated by the FO membrane, the boron permeation depends on the type of membrane, membrane orientation, pH of the feed solution, salt and boron concentration in the feed solution, and osmotic pressure of the draw solution. The boron flux begins to decline from pH 7, and increases with an increase in the osmotic driving force. The boron flux of the CTA-ES and ALFD membrane orientation is higher than those of the CTA-NW and ALFF orientation, respectively. The boron permeation rate is constant regardless of the osmotic pressure and membrane orientation. The boron flux decreases slightly with the salt concentration, but it is not heavily influenced at a low salt concentration

  3. Which future for nuclear counter-proliferation?

    International Nuclear Information System (INIS)

    Duval, M.

    2010-01-01

    Dealing with the case of nuclear weapons possessed by nuclear states (but not eventually by terrorists), the author first identifies the constants of counter-proliferation: it is linked to interest conflicts between those who try to preserve their monopoly and those who try to acquire a new weapon either because of a threat or for reasons of regional prestige, the evolution from use to deterrence, the appearance of new actors after the USA and Russia, the role of nuclear tactical weapons, and the future of Russian weapons and know-how. He presents the international counter-proliferation context: the Non Proliferation Treaty (NPT), the IAEA and its controls, the Nuclear Supplier Group (NSG), the nuclear-free zones, the Comprehensive Test Ban Treaty (CTBT), the Missile Technology Control Regime (MTCR). He describes how and why proliferation occurs: uranium enrichment and plutonium technology, political reasons in different parts of the world. Then, he gives an overview of the proliferation status by commenting the cases of Israel, Iraq, India, Pakistan, North Korea, and Iran. He discusses the future of proliferation (involved countries, existence of a nuclear black market) and of counter-proliferation as far as Middle-East and North Korea are concerned. He tries finally to anticipate the consequences for nuclear deterrence strategy, and more particularly for Europe and France

  4. Selective uptake of p-boronophenylalanine by osteosarcoma cells for boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, C. [Department of Surgery, Experimental Surgery Laboratory, University of Pavia, Piazza Botta, Pavia (Italy)], E-mail: ferraric@unipv.it; Zonta, C.; Cansolino, L.; Clerici, A.M.; Gaspari, A. [Department of Surgery, Experimental Surgery Laboratory, University of Pavia, Piazza Botta, Pavia (Italy); Altieri, S.; Bortolussi, S.; Stella, S. [Department of Nuclear and Theoretical Physics of University, Via Bassi, 6, Pavia (Italy); National Institute of Nuclear Physics (INFN) Section of Pavia, Via Bassi, 6, Pavia (Italy); Bruschi, P. [Department of Nuclear and Theoretical Physics of University, Via Bassi, 6, Pavia (Italy); Dionigi, P.; Zonta, A. [Department of Surgery, Experimental Surgery Laboratory, University of Pavia, Piazza Botta, Pavia (Italy)

    2009-07-15

    Osteosarcoma is the most common non-hematologic primary cancer type that develops in bone. Current osteosarcoma treatments combine multiagent chemotherapy with extensive surgical resection, which in some cases makes necessary the amputation of the entire limb. Nevertheless its infiltrative growth leads to a high incidence of local and distant recurrences that reduce the percentage of cured patients to less than 60%. These poor data required to set up a new therapeutic approach aimed to restrict the surgical removal meanwhile performing a radical treatment. Boron neutron capture therapy (BNCT), a particular radiotherapy based on the nuclear capture and fission reactions by atoms of {sup 10}B, when irradiated with thermal neutrons, could be a valid alternative or integrative option in case of osteosarcoma management, thanks to its peculiarity in selectively destroying neoplastic cells without damaging normal tissues. Aim of the present work is to investigate the feasibility of employing BNCT to treat the limb osteosarcoma. Boronophenylalanine (BPA) is used to carry {sup 10}B inside the neoplastic cells. As a first step the endocellular BPA uptake is tested in vitro on the UMR-106 osteosarcoma cell line. The results show an adequate accumulation capability. For the in vivo experiments, an animal tumor model is developed in Sprague-Dawley rats by means of an intrafemoral injection of UMR-106 cells at the condyle site. The absolute amounts of boron loading and the tumor to normal tissue {sup 10}B ratio are evaluated 2 h after the i.v. administration of BPA. The boron uptake by the neoplastic tissue is almost twice the normal one. However, higher values of boron concentration in tumor are requested before upholding BNCT as a valid therapeutic option in the treatment of osteosarcoma.

  5. Hardware support for software controlled fast multiplexing of performance counters

    Science.gov (United States)

    Salapura, Valentina; Wisniewski, Robert W.

    2013-01-01

    Performance counters may be operable to collect one or more counts of one or more selected activities, and registers may be operable to store a set of performance counter configurations. A state machine may be operable to automatically select a register from the registers for reconfiguring the one or more performance counters in response to receiving a first signal. The state machine may be further operable to reconfigure the one or more performance counters based on a configuration specified in the selected register. The state machine yet further may be operable to copy data in selected one or more of the performance counters to a memory location, or to copy data from the memory location to the counters, in response to receiving a second signal. The state machine may be operable to store or restore the counter values and state machine configuration in response to a context switch event.

  6. Double peak effect in microdosimetric proportional counters and its interpretation

    International Nuclear Information System (INIS)

    Bednarek, B.; Olko, P.; Booz, J.

    1989-01-01

    In calibration measurements with low energy X-rays, a double peak effect appears in low pressure proportional counters with a helix, when used for simulation of tissue equivalent diameters considerably larger than 2 μm. An interpretation of this phenomenon is discussed, based upon electron capture and electric field perturbation at the counter helix. A description of the physical processes is presented showing that the double peak effect is a problem in the case of helix counters (called also Rossi counters) for all simulated diameters. Conclusions are drawn on systematic errors introduced by the counter helix into microdosimetric spectra and anti y D of photons and neutrons. The authors recommend to use cylindrical counters with optimized geometrical and electronic parameters rather than the spherical counters with a helix discussed. (orig.)

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

    Science.gov (United States)

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

    2013-07-15

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

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

    Science.gov (United States)

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

    2014-07-07

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

  9. Method for removal of phosgene from boron trichloride

    Science.gov (United States)

    Freund, S.M.

    1983-09-20

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

  10. Finite Element Analysis Of Boron Diffusion In Wood

    DEFF Research Database (Denmark)

    Krabbenhøft, Kristian; Hoffmeyer, Preben; Bechgaard, Carl

    2002-01-01

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

  11. Boron Diffusion in Surface-Treated Framing Lumber

    Science.gov (United States)

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

    2013-01-01

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

  12. Low-dimensional boron structures based on icosahedron B12

    Science.gov (United States)

    Kah, C. B.; Yu, M.; Tandy, P.; Jayanthi, C. S.; Wu, S. Y.

    2015-10-01

    One-dimensional icosahedral boron chains and two-dimensional icosahedral boron sheets (icosahedral α, δ6, and δ4 sheets) that contain icosahedra B12 as their building units have been predicted in a computer simulation study using a state-of-the-art semi-empirical Hamiltonian. These novel low-dimensional icosahedral structures exhibit interesting bonding and electronic properties. Specifically, the three-center, two-electron bonding between icosahedra B12 of the boron bulk (rhombohedral boron) transforms into a two-center bonding in these new allotropes of boron sheets. In contrast to the previously reported stable buckled α and triangular boron monolayer sheets, these new allotropes of boron sheets form a planar network. Calculations of electronic density of states (DOS) reveal a semiconducting nature for both the icosahedral chain and the icosahedral δ6 and δ4 sheets, as well as a nearly gapless (or metallic-like) feature in the DOS for the icosahedral α sheet. The results for the energy barrier per atom between the icosahedral δ6 and α sheets (0.17 eV), the icosahedral δ6 and δ4 sheets (0.38 eV), and the icosahedral α and δ4 sheets (0.27 eV), as indicated in the respective parentheses, suggest that these new allotropes of boron sheets are relatively stable.

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

    NARCIS (Netherlands)

    Duval, F.L.

    2015-01-01

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

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

    Science.gov (United States)

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

    2002-07-15

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

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

    Directory of Open Access Journals (Sweden)

    Ashraf Metwally

    2012-01-01

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

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

    Indian Academy of Sciences (India)

    TECS

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

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

    International Nuclear Information System (INIS)

    2002-01-01

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

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

    Indian Academy of Sciences (India)

    TECS

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

  19. Vacancy complexes in carbon and boron nitride nanotubes

    CSIR Research Space (South Africa)

    Mashapa, MG

    2012-10-01

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

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

    African Journals Online (AJOL)

    STORAGESEVER

    2009-09-15

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

  1. Non-invasive estimation of BPA-derived boron concentration in tumors by18F-FBPA PET.

    Science.gov (United States)

    Yoshimoto, Mitsuyoshi; Honda, Natsuki; Kurihara, Hiroaki; Hiroi, Kenta; Nakamura, Satoshi; Ito, Masashi; Shikano, Naoto; Itami, Jun; Fujii, Hirofumi

    2018-03-02

    In boron neutron capture therapy (BNCT), 10 B-4-borono-L-phenylalanine (BPA) is commonly used as a 10 B carrier. Positron emission tomography using 4-borono-2- 18 F-fluoro-phenylalanine ( 18 F-FBPA PET) has been performed to estimate boron concentration and predict the therapeutic effects of BNCT; however, the association between tumor uptake of 18 F-FBPA and boron concentration in tumors remains unclear. The present study investigated the transport mechanism of 18 F-FBPA and BPA, and evaluated the utility of 18 F-FBPA PET in predicting boron concentration in tumors. The transporter assay revealed that 2-aminobicyclo-(2.2.1)-heptane-2-carboxylic acid, an inhibitor of the L-type amino acid transporter, significantly inhibited 18 F-FBPA and 14 C-BPA uptake in FaDu and LN-229 human cancer cells. 18 F-FBPA uptake strongly correlated with 14 C-BPA uptake in seven human tumor cell lines (r = 0.93; p BPA uptake by continuous intravenous infusion. The results of this study revealed that evaluating tumor uptake of 18 F-FBPA by PET was useful for estimating 10 B concentration in tumors. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

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

    International Nuclear Information System (INIS)

    MacIver, B.A.

    1975-01-01

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

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

    Science.gov (United States)

    Ray, P. K.; Shutthanandan, V.

    1998-01-01

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

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

    Indian Academy of Sciences (India)

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

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

    Indian Academy of Sciences (India)

    A ceramic precursor, prepared by condensation reaction from poly(vinyl alcohol) (PVA) and boric acid (H3BO3) in 1:1, 2:1 and 4:1 molar ratios, was synthesized as low temperature synthesis route for boron nitride ceramic. Samples were pyrolyzed at 850°C in nitrogen atmosphere followed by characterization using Fourier ...

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

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  7. Data transfer from Beckman LS 5800 liquid scintillation counters to IBM personal computers.

    Science.gov (United States)

    Maan, A C

    1985-09-01

    This communication describes a short routine in BASICA for the IBM-PC, written to collect data from a Beckman liquid scintillation counter. In the form presented here the routine converts incoming bytes into separate lines and saves these lines in a file. There are many possible applications for further use of the data in these files. A few suggestions are given as to the format in which data can be stored and how to process these data automatically after all samples have been counted. The only hardware needed is an asynchronous communications adapter for the IBM-PC and an RS232 cable.

  8. H2O-induced trigonal-to-tetrahedral transition in boron zeolites

    International Nuclear Information System (INIS)

    Fois, E.; Gamba, A.; Trudu, F.; Tabacchi, G.

    2008-01-01

    The behaviour of a protonated boron-containing zeolite at intermediate hydration degree has been investigated by means of periodic DFT approaches. Results of a combined room-temperature Car-Parrinello molecular dynamics blue-moon path sampling simulation indicate that, in the line with experimental findings, the BO 3 /Si-OH acid site typical of dry samples is converted to a hydrated H 3 O + hydrogen bonded to tetrahedral BO 4 - at moderate water content (four H 2 O per B site) with an activation free barrier of the order of few k T.

  9. Consumer Preferences for High Welfare Meat in Germany: Self-service Counter or Service Counter?

    Directory of Open Access Journals (Sweden)

    Ramona Weinrich

    2015-01-01

    Full Text Available Many people view animal welfare standards in the agricultural industry as critical and some consumers would prefer to buy high welfare meat. In order to successfully introduce high welfare meat products onto the market, some important marketing decisions must be made. Due to limited shelf space in retail outlets, niche products like high welfare meat cannot be placed both at the self-service counter and at the service counter. In order to analyze where to place it best an online survey of 642 German consumers was conducted. By means of factor and cluster analyses, consumers’ animal welfare attitudes and their preference for a point of purchase were combined. The different target groups were joint using cross tabulation analysis. The results reveal that consumers in the target group show a more positive attitude to the service counter.

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

    Science.gov (United States)

    Hunt, Curtiss D

    2012-06-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

  12. Boron effect on stainless steel plasticity under hot deformation

    International Nuclear Information System (INIS)

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

    1978-01-01

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

  13. Fracture toughness of borides formed on boronized ductile iron

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  14. Metal-Free Boron-Containing Heterogeneous Catalysts.

    Science.gov (United States)

    Fang, Yuanxing; Wang, Xinchen

    2017-12-04

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

  15. Additive Manufacturing of Dense Hexagonal Boron Nitride Objects

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-05-12

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

  16. Problems and possibilities of development of boron nitride ceramics

    International Nuclear Information System (INIS)

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

    1988-01-01

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

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

    Science.gov (United States)

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

    2006-02-01

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

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

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

    Science.gov (United States)

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

    2017-08-01

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

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

    Science.gov (United States)

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

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

    NARCIS (Netherlands)

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

    2012-01-01

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

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-11-05

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

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

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  6. Wettability of Pyrolytic Boron Nitride by Aluminum

    Science.gov (United States)

    Chiaramonte, Francis P.; Rosenthal, Bruce N.

    1991-01-01

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

  7. Fabrication of boron nitride planar field emitters

    Science.gov (United States)

    Yokota, Yuuko; Tagawa, Shigeru; Sugino, Takashi

    1999-05-01

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

  8. Magnesium doping of boron nitride nanotubes

    Science.gov (United States)

    Legg, Robert; Jordan, Kevin

    2015-06-16

    A method to fabricate boron nitride nanotubes incorporating magnesium diboride in their structure. In a first embodiment, magnesium wire is introduced into a reaction feed bundle during a BNNT fabrication process. In a second embodiment, magnesium in powder form is mixed into a nitrogen gas flow during the BNNT fabrication process. MgB.sub.2 yarn may be used for superconducting applications and, in that capacity, has considerably less susceptibility to stress and has considerably better thermal conductivity than these conventional materials when compared to both conventional low and high temperature superconducting materials.

  9. Stability analysis of zigzag boron nitride nanoribbons

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  10. Processing of boron carbide-aluminum composites

    International Nuclear Information System (INIS)

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

    1989-01-01

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

  11. Method for exfoliation of hexagonal boron nitride

    Science.gov (United States)

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

    2012-01-01

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

  12. Synthesis of a boron modified phenolic resin

    Directory of Open Access Journals (Sweden)

    Aparecida M. Kawamoto

    2010-08-01

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

  13. Hydrothermal synthesis of cubic boron nitride crystals

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  14. Boron carbide nanowires with uniform CNx coatings

    Science.gov (United States)

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

    2007-01-01

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

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

    International Nuclear Information System (INIS)

    Gunduz, G.

    1997-11-01

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

  16. Efficient Boron Nitride Nanotube Formation via Combined Laser-Gas Flow Levitation

    Science.gov (United States)

    Whitney, R. Roy (Inventor); Jordan, Kevin (Inventor); Smith, Michael W. (Inventor)

    2014-01-01

    A process for producing boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula B(sub x)C(sub y)N(sub z) The process utilizes a combination of laser light and nitrogen gas flow to support a boron ball target during heating of the boron ball target and production of a boron vapor plume which reacts with nitrogen or nitrogen and carbon to produce boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula B(sub x)C(sub y)N(sub z).

  17. Efficient Boron-Carbon-Nitrogen Nanotube Formation Via Combined Laser-Gas Flow Levitation

    Science.gov (United States)

    Whitney, R. Roy (Inventor); Jordan, Kevin (Inventor); Smith, Michael W. (Inventor)

    2015-01-01

    A process for producing boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula BxCyNz. The process utilizes a combination of laser light and nitrogen gas flow to support a boron ball target during heating of the boron ball target and production of a boron vapor plume which reacts with nitrogen or nitrogen and carbon to produce boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula BxCyNz.

  18. Concentrating lightguide for threshold Cherenkov counters

    International Nuclear Information System (INIS)

    Gavrishchuk, O.P.; Onuchin, V.A.; Semenov, V.K.; Suzdalev, V.I.

    1991-01-01

    A method of manufacturing lightguides (Winston lenses) is proposed to increase the effective area of light collection on photodetectors (with diameter of detectiving area from 45 to 120 mm) and to broaden angular range of radiation detection in threshold Cherenkov counters. The concentrating lightguides with height and diameter up to 300 mm were pressure formed of 3 to 5 mm thick plexiglass sheets. Dependences of the light reflection coefficient on the wavelength (for wavelengths between 185 and 650 nm) of the deposited lightguide are presented. 10 refs.; 4 figs

  19. Industrial espionage and technical surveillance counter measurers

    CERN Document Server

    Androulidakis, Iosif

    2016-01-01

    This book examines technical aspects of industrial espionage and its impact in modern companies, organizations, and individuals while emphasizing the importance of intellectual property in the information era. The authors discuss the problem itself and then provide statistics and real world cases. The main contribution provides a detailed discussion of the actual equipment, tools and techniques concerning technical surveillance in the framework of espionage. Moreover, they present the best practices and methods of detection (technical surveillance counter measures) as well as means of intellectual property protection.

  20. The counter-conventional mindsets of entrepreneurs

    OpenAIRE

    Mullins, J

    2017-01-01

    These days, it seems, nearly everyone aspires to be an entrepreneur. But many entrepreneurs think and act differently than the ways in which most other businesspeople do and the ways much of today’s business education encourages them to think and act. My in-depth examination of dozens of entrepreneurs I’ve come to know well over the past two decades tells me that their unconventional – or, dare I say, counter-conventional – mindsets and behaviors are marked by six common patterns:\\ud “Yes, we...